The electron transport chain of the microbicidal oxidase of phagocytic cells and its involvement in the molecular pathology of chronic granulomatous disease.

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Authors

A W Segal

Acquired C1 inhibitor (C1-INH) deficiency type II. Replacement therapy with C1-INH and analysis of patients' C1-INH and anti-C1-INH autoantibodies.

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The response of two patients with autoantibody-mediated C1-inhibitor (C1-INH) deficiency to replacement therapy with C1-INH was studied over a period of 3 d. In patient 1 an acute attack of angioedema was successfully managed by infusion of 1,000 U of C1-INH concentrate. C1-INH function returned to normal levels within 30 min, while CH50 and C4 peaked after 6-7 h and C1 hemolytic activity reached 50-60% of normal after 3 d. Immediately after the injection an increase in C1-INH-anti-C1-INH complexes was observed. Based on NH2-terminal sequence analysis of the patients' Mr 96,000 C1-INH, it is concluded that this fragment is generated after cleavage of C1-INH in its active site by one of its target proteases without generating a covalent C1-INH-enzyme complex. In a second patient with a four to five times higher anti-C1-INH antibody titer, the infusion of 500 ml of plasma or of 2,000 U of C1-INH concentrate influenced neither the severity of the patient's angioedema nor the tested parameters, except for an increase in the amount of C1-INH-anti-C1-INH complexes. Analysis of patients' anti-C1-INH antibodies revealed that the antibodies recognize different epitopes within the C1-INH. This suggests that patients with acquired angioedema type II are a heterogenous group with respect to the C1-INH autoantibodies.

Authors

J Alsenz, J D Lambris, K Bork, M Loos

Effects of exogenous free radicals on electromechanical function and metabolism in isolated rabbit and guinea pig ventricle. Implications for ischemia and reperfusion injury.

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Oxygen-derived free radicals have been implicated in the pathogenesis of cardiac dysfunction during ischemia, postischemic myocardial "stunning," and reperfusion injury. We investigated the effects of oxygen-derived free radicals on cardiac function in intact isolated rabbit hearts and single guinea pig ventricular myocytes. In the intact rabbit ventricle, exposure to free radical-generating systems caused increased cellular K+ efflux, shortening of the action potential duration, changes in tension, and depletion of high energy phosphates similar to ischemia and metabolic inhibition. In patch-clamped single ventricular myocytes, free radical-generating systems activated ATP-sensitive K+ channels, decreased the calcium current, and caused cell shortening by irreversibly inhibiting glycolytic and oxidative metabolism. The results suggest that free radicals generated during ischemia and reperfusion may contribute to electrophysiologic abnormalities and contractile dysfunction by inhibiting glycolysis and oxidative phosphorylation. Inhibition of metabolism by free radicals may be an important factor limiting functional recovery from an ischemic insult after reestablishment of effective blood flow.

Authors

J I Goldhaber, S Ji, S T Lamp, J N Weiss

Immune system control of rat and rabbit colonic electrolyte transport. Role of prostaglandins and enteric nervous system.

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The role of the immune system in controlling intestinal electrolyte transport was studied in rat and rabbit colon in Ussing chambers. A phagocyte stimulus, the chemotactic peptide FMLP, and a mast cell stimulus, sheep anti-rat IgE, caused a brief (less than 10 min) increase in short-circuit current (Isc). Products of immune system activation, platelet-activating factor (PAF) and reactive oxygen species (ROS), caused a sustained, biphasic increase in the Isc. Ion replacement and flux studies indicated that these agonists stimulated electrogenic Cl secretion and inhibited neutral NaCl absorption; responses that were variably inhibited by the cyclooxygenase blockers indomethacin and piroxicam. Lesser degrees of inhibition by nordihydroguaiaretic acid could be accounted for by decreased prostaglandin synthesis rather than by lipoxygenase blockade. Tetrodotoxin, hexamethonium, and atropine also inhibited immune agonist-stimulated Isc, but had no effect on immune agonist-stimulated production of PGE2 or PGI2. These results indicate that immune system agonists alter intestinal epithelial electrolyte transport through release of cyclooxygenase products from cells in the lamina propria with at least 50% of the response being due to cyclooxygenase product activation of the enteric nervous system. The immune system, like the enteric nervous system and the endocrine system, may be a major regulating system for intestinal water and electrolyte transport in health and disease.

Authors

M J Bern, C W Sturbaum, S S Karayalcin, H M Berschneider, J T Wachsman, D W Powell

Protection against nerve toxicity by monoclonal antibodies to the sodium channel blocker tetrodotoxin.

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The sodium channel blocker, tetrodotoxin (TDT), was conjugated to keyhole limpet hemocyanin (KLH) and used to immunize BALB/c mice. Anti-TDT antibodies were detected in serum by ELISA and reached stable levels 4-5 wk after the first immunization. Spleens from immunized mice were fused with NS-1 mouse myeloma cells and approximately 9,329 resultant hybrids were screened by ELISA for reactivity to TDT. Two stable hybrids were isolated, subcloned, and characterized. These hybrids, termed TD13a1 and TD2C5, secreted specific anti-TDT antibodies that recognized TDT but not the related sodium channel blocker, saxitoxin (STX), as determined by competition ELISA. Both antibodies were of the IgG1k subclass with Ka's approaching 10(7) M-1. The inhibitory ability of these antibodies was tested by a competitive displacement assay for [3H]STX on rat brain membranes. Both antibodies strongly inhibited TDT binding to membranes. A nanomole of TD2C5 was able to bind approximately 1.8 nmol of TDT, whereas a comparable amount of TD13a1 bound half as much. Furthermore, TD2C5 was able to protect against TDT-induced reduction of peripheral nerve action potentials in rat tibial nerve when administered in situ. These antibodies thus represent potentially useful reagents for neurobiologic research, detection of toxin contamination and diagnosis of poisoning, and may provide protection against the toxicity of TDT in vivo.

Authors

R I Huot, D L Armstrong, T C Chanh

Normal human intestinal B lymphocytes. Increased activation compared with peripheral blood.

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The state of activation of normal human intestinal mononuclear cells obtained from transplant donors was studied. Compared with PBMC, freshly isolated intestinal mononuclear cells expressed significantly more cell surface activation antigens on both B and T lymphocytes. Intestinal mononuclear cells contained significant numbers of immunoglobulin secreting cells immediately after cell separation. This population included CD5-positive B cells that secreted predominantly IgA. Cells from the large bowel consistently revealed higher numbers of IgA secreting cells than cells from the small bowel. Thus, intestinal B cells are markedly activated in vivo compared with PBMC and this increased activation correlates with increased spontaneous antibody secretion. B cells from the large intestine are more highly activated and secrete more antibody than do cells from the small intestine. The intestinal lamina propria lymphoid compartment exhibits a heightened state of activation that may be important for its distinct role in mucosal defense.

Authors

M G Peters, H Secrist, K R Anders, G S Nash, S R Rich, R P MacDermott

Production of GAWK (chromogranin-B 420-493)-like immunoreactivity by endocrine tumors and its possible diagnostic value.

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GAWK (chromogranin-B 420-493) is a 74 amino acid peptide recently isolated from human pituitaries. Using two different antibodies (directed against GAWK [1-17] and [20-38] fragments) GAWK-LI was measured in tumors from 194 patients and in the plasma of 434 patients by RIA. The highest tissue concentrations of GAWK-LI were found in pheochromocytoma (GAWK [1-17]-LI, 18,173 +/- 3,915; GAWK [20-38]-LI, 17,852 +/- 2,763 [mean +/- SEM] pmol/g wet wt tissue; n = 9), which were at least ten times higher than any other tumors producing GAWK-LI. High concentrations of GAWK-LI were also found in other types of endocrine tumors including carcinoid, medullary carcinoma of thyroid, pancreatic, and ACTH-producing lung tumors. On the other hand, low concentrations of GAWK-LI were found in nonendocrine tumors. Plasma concentrations of GAWK-LI were found to be elevated in patients with endocrine tumor, but more so in those with pancreatic tumors than with pheochromocytomas. Plasma concentrations returned to normal after successful tumor removal. Chromatographic profiles of GAWK-LI in extracts of pheochromocytomas and normal adrenals showed high molecular weight peaks that were absent in the extracts of other endocrine tumors and normal pancreas, suggesting differential tissue-specific processing. Thus GAWK-LI is produced by a variety of endocrine tumors and may serve as a plasma tumor marker, especially in patients with pancreatic endocrine tumors.

Authors

K Sekiya, M A Ghatei, M J Salahuddin, A E Bishop, Q A Hamid, H Ibayashi, J M Polak, S R Bloom

Human immunodeficiency virus infection of helper T cell clones. Early proliferative defects despite intact antigen-specific recognition and interleukin 4 secretion.

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HIV selectively inhibited the proliferative response of clonal CD4+ T lymphocytes to alloantigen while other alloantigen-dependent responses were unperturbed. Specifically, impaired blastogenesis could be dissociated from alloantigen-specific induction of the B cell activation molecule CD23, IL-4 release, and inositol lipid hydrolysis. In addition, membrane expression of pertinent T cell receptor molecules, including CD2, CD3, and T cell antigen receptor (Ti), remained intact. Using two MHC class II-specific human CD4+ helper T cell clones, the proliferative defect was shown to be an early consequence of HIV infection, occurring within 4 d of viral inoculation and preceding increases in mature virion production. It was generalizable to three distinct methods of T cell activation, all independent of antigen-presenting cells: anti-CD3 mediated cross-linking of the CD3/Ti complex; anti-CD2 and phorbol 12-myristic 13-acetate (PMA); and anti-CD28 plus PMA. These abnormalities were not mitigated by addition of exogenous IL-2, even though expression of the IL-2 receptor (CD25) was unaltered. These studies define a selective blockade in T cell function early after HIV exposure that could serve as a model for certain in vivo manifestations of AIDS.

Authors

J Laurence, S M Friedman, E K Chartash, M K Crow, D N Posnett

Failure of postnatal adaptation of the pulmonary circulation after chronic intrauterine pulmonary hypertension in fetal lambs.

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To determine the effects of chronic intrauterine pulmonary hypertension on the perinatal pulmonary circulation, we induced chronic elevations of pulmonary artery pressure in 24 late-gestation fetal lambs by maintaining partial compression of the ductus arteriosus with an inflatable vascular occluder. Pulmonary artery pressure was increased from 44 +/- 1 to 62 +/- 3 mmHg for 3-14 d. Although left pulmonary artery blood flow initially increased during acute partial ductus compression, the increase in flow was not sustained during chronic ductus compression despite persistent elevations of pulmonary artery pressure (P less than 0.01). Chronic hypertension decreased the slope of the pressure-flow relationship from 3.4 +/- 0.3 (initial) to 0.9 +/- 0.1 ml/min per mmHg, and blunted the fetal pulmonary vascular response to small increases in PO2 (P less than 0.0001). Pulmonary hypertension for greater than 8 d increased the wall thickness of small pulmonary arteries (P less than 0.001). Compared with controls, hypertensive animals had higher pulmonary artery pressure, lower pulmonary blood flow, and predominant right-to-left ductus shunting after cesarean-section delivery (P less than 0.0001). We conclude that chronic pulmonary hypertension in utero, in the absence of hypoxemia or sustained increases in blood flow, causes abnormal fetal pulmonary vasoreactivity, structural remodeling, and the failure to achieve the normal decline in pulmonary resistance at birth.

Authors

S H Abman, P F Shanley, F J Accurso

Contributions of cellular leak pathways to net NaHCO3 and NaCl absorption.

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Proton and formic acid permeabilities were measured in the in vivo microperfused rat proximal convoluted tubule by examining the effect on intracellular pH when [H] and/or [formic acid] were rapidly changed in the luminal or peritubular fluids. Apical and basolateral membrane H permeabilities were 0.52 +/- 0.07 and 0.67 +/- 0.18 cm/s, respectively. Using these permeabilities we calculate that proton backleak from the luminal fluid to cell does not contribute significantly to net proton secretion in the early proximal tubule, but may contribute in the late proximal tubule. Apical and basolateral membrane formic acid permeabilities measured at extracellular pH 6.62 were 4.6 +/- 0.5 X 10(-2) and 6.8 +/- 1.5 X 10(-2) cm/s, respectively. Control studies demonstrated that the formic acid permeabilities were not underestimated by either the simultaneous movement of formate into the cell or the efflux of formic acid across the opposite membrane. The measured apical membrane formic acid permeability is too small to support all of transcellular NaCl absorption in the rat by a mechanism that involves Na/H-Cl/formate transporters operating in parallel with formic acid nonionic diffusion.

Authors

P A Preisig, R J Alpern

Profile of human T cell response to leishmanial antigens. Analysis by immunoblotting.

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Control and resolution of leishmanial infection depends primarily on T cell-mediated immune mechanisms. The nature of the leishmanial antigens involved in eliciting T cell immunity is unknown. We have examined the pattern of peripheral blood lymphocyte responses in patients with active, healed, or subclinical leishmanial infection to fractionated leishmanial antigens using a T cell immunoblotting method in which nitrocellulose-bound leishmanial antigen, resolved by one or two dimensional electrophoresis, are incorporated into lymphocyte cultures. The proliferative and IFN-gamma responses of cells from patients with healed mucosal or cutaneous leishmaniasis were remarkably heterogeneous and occurred to as many as 50-70 distinct antigens. In contrast, responses from subjects with active, nonhealing, diffuse cutaneous leishmaniasis were either absent or present to only a small number of antigens. Control and resolution of leishmaniasis, and resistance to reinfection, is therefore associated with a T cell response to a large and diverse pool of parasite antigens. The method of T cell immunoblotting appears to offer a powerful, rapid, and relatively simple approach to the identification of antigens involved in eliciting a T cell response in human leishmaniasis.

Authors

P C Melby, F A Neva, D L Sacks

Relationship between calcium loading and impaired energy metabolism during Na+, K+ pump inhibition and metabolic inhibition in cultured neonatal rat cardiac myocytes.

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Abstract

This study tested the hypothesis that the initiating mechanism is a major determinant of the response to calcium (Ca) accumulation in myocardium. Cultured neonatal rat ventriculocytes were exposed to Na+, K+ pump inhibition with 1 mM ouabain and metabolic inhibition with 20 mM 2-deoxy-D-glucose and 1 mM cyanide (DOG-CN) for up to 2 h. Microspectrofluorometry of myocytes loaded with fura-2 showed that ouabain resulted in a relatively rapid increase in [Ca2+]i up to 2-3 microM (two to threefold above peak systolic level) and that DOG-CN produced an initial decrease and then a relatively slow increase in [Ca2+]i up to peak systolic level. Electron probe x-ray microanalysis (EPMA) showed prominent increases in Na and Ca and decreases in K and Mg in cytoplasm and mitochondria with both interventions, although the increases in Ca were greater with ouabain than DOG-CN. ATP was reduced by 58% after 1 and 2 h of ouabain and by 70 and 90% after 1 and 2 h of DOG-CN, respectively. Thus, ouabain produced greater calcium accumulation and less ATP reduction than DOG-CN. Upon return to normal medium for 30 min, myocytes showed recovery of most electrolyte alterations and resumption of normal Ca2+ transients after 1 h exposure to either ouabain or DOG-CN; however, recovery was less after 2 h of either treatment, with elevated [Ca2+]i maintained in many myocytes. We conclude that the severity of myocyte injury is influenced by the magnitude and duration of both ATP reduction and calcium accumulation.

Authors

A C Morris, H K Hagler, J T Willerson, L M Buja

Type I C1 inhibitor deficiency with a small messenger RNA resulting from deletion of one exon.

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The molecular genetic basis of C1 inhibitor (C1 INH) deficiency in a patient with type I hereditary angioneurotic edema was studied. This patient was found to have an abnormally short C1 INH mRNA together with a normal message. Restriction fragment length polymorphism of the C1 INH gene was detected by Southern blot analysis of the patient's DNA after digestion with Pst I or Sac I, and hybridization with a full-length C1 INH cDNA. Hybridization of the same blot with three different fragments of the full-length cDNA suggested that exon VII and portions of both flanking introns were deleted in the C1 INH gene. Northern blot analysis of RNA from cultured monocytes, using a probe corresponding to exon VII, also indicated that the abnormal C1 INH mRNA had a deletion of these nucleotides. To confirm the hypothesis that the short C1 INH mRNA contained a deletion, the involved segment of the patient's C1 INH mRNA was amplified using the polymerase chain reaction (PCR). PCR amplification yielded two C1 INH DNA fragments of different lengths (380 and 160 bp). Southern blot and sequence analysis of both DNA fragments clearly revealed that the smaller 160-bp DNA was derived from the abnormal message and had a deletion of nucleotides corresponding to exon VII.

Authors

T Ariga, T Igarashi, N Ramesh, R Parad, M Cicardi, A E Davis 3rd

RNA fingerprinting of respiratory syncytial virus using ribonuclease protection. Application to molecular epidemiology.

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We have used the technique of ribonuclease protection to define genomic variation among circulating isolates of subgroup A respiratory syncytial (RS) virus. RNAs extracted from HEp-2 cells infected with strains to be analyzed were hybridized with a 32P-labeled RNA probe corresponding to the RS virus G glycoprotein (A2 strain). Areas of nonhomology were detected by cleavage with ribonuclease A. Using this technique, multiple distinct RNA cleavage patterns could be distinguished among viral isolates recovered from infants residing in the same metropolitan area and infected during the same epidemic season. Epidemiologically related isolates (from coinfected twins, from infants infected during a nosocomial outbreak at an extended care facility, and from institutionalized adults infected during an outbreak) yielded identical patterns. In two separate outbreaks, differences in cleavage patterns among certain isolates corresponded to epidemiologically significant differences among the individuals from whom the isolates were recovered. We conclude that substantial genomic heterogeneity exists among circulating isolates of subgroup A RS virus. Ribonuclease protection can be used as a molecular fingerprinting tool for expanded studies of the molecular epidemiology of this virus.

Authors

G A Storch, C S Park, D E Dohner

Identification and regulation of 1,25-dihydroxyvitamin D3 receptor activity and biosynthesis of 1,25-dihydroxyvitamin D3. Studies in cultured bovine aortic endothelial cells and human dermal capillaries.

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Because 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) has been shown to play roles in both proliferation and differentiation of novel target cells, the potential expression of 1,25(OH)2D3 receptor (VDR) activity was investigated in cultured bovine aortic endothelial cells (BAEC). Receptor binding assays performed on nuclear extracts of BAEC revealed a single class of specific, high-affinity VDR that displayed a 4.5-fold increase in maximal ligand binding (Nmax) in rapidly proliferating BAEC compared with confluent, density-arrested cells. When confluent BAEC were incubated with activators of protein kinase C (PKC), Nmax increased 2.5-fold within 6-24 h and this upregulation was prevented by sphingosine, an inhibitor of PKC, as well as by actinomycin D or cycloheximide. Immunohistochemical visualization using a specific MAb disclosed nuclear localized VDR in venular and capillary endothelial cells of human skin biopsies, documenting the expression of VDR, in vivo, and validating the BAEC model. Finally, additional experiments indicated that BAEC formed the 1,25(OH)2D3 hormonal metabolite from 25(OH)D3 substrate, in vitro, and growth curves of BAEC maintained in the presence of 10(-8) M 1,25(OH)2D3 showed a 36% decrease in saturation density. These data provide evidence for the presence of a vitamin D microendocrine system in endothelial cells, consisting of the VDR and a 1 alpha-hydroxylase enzyme capable of producing 1,25(OH)2D3. That both components of this system are coordinately regulated, and that BAEC respond to the 1,25(OH)2D3 hormone by modulating growth kinetics, suggests the existence of a vitamin D autocrine loop in endothelium that may play a role in the development and/or functions of this pathophysiologically significant cell population.

Authors

J Merke, P Milde, S Lewicka, U Hügel, G Klaus, D J Mangelsdorf, M R Haussler, E W Rauterberg, E Ritz

Modulation of polymorphonuclear leukocyte microbicidal activity and oxidative metabolism by fibrinogen degradation products D and E.

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Fibrinogen degradation products (FDP) D and E are typically present in blood of patients with disseminated intravascular coagulation and related conditions in which granulocyte (PMN) defense against bacterial infection may be compromised. This study was intended to determine whether FDP modify PMN functions critical to their bactericidal activity. Incubation of human PMN and Escherichia coli with 50-100 micrograms/ml FDP did not affect phagocytosis, but reduced by greater than 90% the cells' ability to inhibit bacterial colony growth compared with control PMN incubated with albumin or fibrinogen. FDP (10-100 micrograms/ml) inhibited PMN O2- release and chemotaxis stimulated by FMLP by 17-50% (P less than 0.005) and 41% (P less than 0.01), respectively. Fragment E3, and not fragment D1, was primarily responsible for inhibition of FMLP-induced PMN O2- release. Phorbol myristate acetate (10 ng/ml), 1-oleoyl-2-acetylglycerol (10(-6) M), AA (4.2 x 10(-5) M), and zymosan-activated serum-stimulated PMN O2- release were also decreased 37-63% by FDP compared with control protein. There are at least two mechanisms by which FDP may impair PMN responses. With respect to FMLP, FDP (16-100 micrograms/ml) inhibited specific binding to the cell surface over a ligand concentration range of 1.4-85 nM [3H]FMLP. In contrast, FDP did not effect the extent of phorbol ester binding to PMN but blocked activation of protein kinase C. These data suggest that elevated plasma FDP inhibit several PMN functions critical to the bactericidal role of these inflammatory cells.

Authors

J W Kazura, J D Wenger, R A Salata, A Z Budzynski, G H Goldsmith

17-beta-estradiol increases mitogenic activity of medium from cultured preadipocytes of massively obese persons.

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Having reported that omental preadipocytes from massively obese persons release into the culture medium proteins mitogenic for preadipocytes, this study aimed to determine whether estrogens contribute to the production of these factors. Sub-cultured omental preadipocytes from 13 massively obese women were grown in the presence or absence of 17-beta-estradiol, and during the last 24 h the conditioned medium was prepared in the absence of serum. Media from cells of 8 of 13 subjects contained significantly higher mitogenic activity when grown in the presence of 17-beta-estradiol. 17-Alpha-estradiol was not effective. The bioassay system involved rat perirenal preadipocytes, since these have been well characterized. Partial purification by gel filtration chromatography indicated that the estrogen-dependent factors had Mr greater than 250,000 and approximately 30,000. Thus, estrogens might contribute to the development of massive obesity in genetically susceptible subjects by promoting the production of paracrine/autocrine principles by adipose cells.

Authors

S C Cooper, D A Roncari

Inhibition of osteoclast-like cell formation by bisphosphonates in long-term cultures of human bone marrow.

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Bisphosphonates inhibit bone resorption in vivo and in vitro by unknown mechanisms. The effect of bisphosphonates on the formation of osteoclasts from their mononuclear hematopoietic precursors was investigated using human long-term marrow cultures in which multinucleated cells form that express most of the known features of the osteoclast phenotype (e.g., bone resorption, tartrate-resistant acid phosphatase, calcitonin responsiveness, and reactivity with specific MAbs). The five bisphosphonates that were tested strongly inhibited 1,25-dihydroxyvitamin D3-stimulated formation of these cells with the same relative potencies as they inhibit bone resorption in vivo. Two representative compounds (3-amino-1-hydroxypropylidene-1,1-bisphosphonate and dichloromethylene bisphosphonate) failed to inhibit the proliferation of precursors of the osteoclast-like cells. However, these compounds decreased the proportion of mononuclear and multinucleated cells expressing an osteoclast antigen, thus suggesting a degree of specificity for cells of the osteoclast lineage. We conclude that bisphosphonates are potent inhibitors of osteoclast-like cell formation in long-term human marrow cultures, and that this may be related to their ability to inhibit bone resorption in vivo.

Authors

D E Hughes, B R MacDonald, R G Russell, M Gowen

Inhibition of O2- generation by dexamethasone is mimicked by lipocortin I in alveolar macrophages.

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Glucocorticoids inhibit superoxide (O2-) generation by phagocytes through a mechanism that remains unclear. We investigated this effect by using dexamethasone on guinea pig alveolar macrophages. O2- generation was induced either by the calcium ionophore A23187, a potent stimulus of phospholipase A2, or by the protein kinase C activator, phorbol myristate acetate (PMA). Dexamethasone inhibited O2- generation initiated by A23187 by 50-55%. This inhibition required: (a) more than 45 min incubation and was maximal after 2 h; (b) glucocorticoid receptor occupancy; and (c) protein synthesis. The inhibitory effect of dexamethasone could not be explained by an interaction with the respiratory burst enzyme NADPH oxidase since O2- generation was only weakly affected upon PMA stimulation. Lipocortin I, a glucocorticoid inducible and phospholipase A2 inhibitory protein, inhibited O2- generation initiated by A23187 but failed to modulate the respiratory burst activated by PMA. These results were obtained with lipocortin I purified from mouse lungs, human blood mononuclear cells, and with human recombinant lipocortin I. We propose that lipocortin I is capable of inhibiting the activation of NADPH oxidase only when membrane signal transduction involves phospholipase A2. By mimicking the effect of dexamethasone, lipocortin I may extend its potential anti-inflammatory action to the partial control of the formation of oxygen reactive species by phagocytes.

Authors

I Maridonneau-Parini, M Errasfa, F Russo-Marie

Androgen regulation of rat renal angiotensinogen messenger RNA expression.

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Renal angiotensinogen (ang-n) mRNA concentration in the male WKY rat increases significantly during puberty. Furthermore, renal angiotensinogen mRNA level in the adult female WKY rat is considerably lower than in the male. The present study investigates the role of androgen in differential renal ang-n mRNA expression. Northern and slot blot analyses with alpha-32P labeled ang-n cDNA (pRang 3) demonstrated that castration lowered ang-n mRNA levels in the male kidney by greater than or equal to 60% compared with control, suggesting that androgen may be involved with renal ang-n gene regulation. Moreover, male WKY rats castrated as weanlings and normal adult female WKY rats each implanted with testosterone displayed significant (P less than 0.05) increases in renal ang-n mRNA levels. Our observations, taken together with previous reports that androgen influences proximal tubule morphology and the tubular expression of transport proteins (e.g., Na+/H+ antiporter), may have important physiological implications for understanding the relationship between androgen and angiotensin in the regulation of tubular function.

Authors

K E Ellison, J R Ingelfinger, M Pivor, V J Dzau

Atherosclerosis influences the vasomotor response of epicardial coronary arteries to exercise.

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We studied the vasomotion of epicardial coronary arteries during exercise and tested the hypotheses that abnormal vasoconstriction is related to the presence of atherosclerosis and may be related to endothelial dilator dysfunction. During cardiac catheterization quantitative coronary angiography was performed in 21 patients during supine bicycle exercise. 21 of 28 smooth, angiographically normal vessel segments dilated (14.0 +/- 1.8%) during exercise; four smooth segments did not change whereas only three constricted. In contrast, 15 of 16 vessel segments with irregularities constricted in response to exercise (17.0 +/- 0.1%) with only one segment dilating. All 10 stenotic segments constricted to exercise (23 +/- 4%). Six patients also received intracoronary acetylcholine before exercise to test endothelium-dependent dilator function. In five of six patients all nine vessel segments showed the same directional response to acetylcholine and exercise. Three irregular and two stenotic segments constricted with acetylcholine (51 +/- 21%) and exercise (9.0 +/- 0.6%). In contrast, four smooth segments dilated to acetylcholine (19 +/- 6%) and exercise (9 +/- 1%). Both exercise and acetylcholine generally dilated smooth but constricted irregular and stenosed coronary segments. It appears likely that atherosclerosis plays an important role in the abnormal vasomotion of diseased coronary arteries during exercise and the pattern of abnormality suggests impairment of vasodilator function.

Authors

J B Gordon, P Ganz, E G Nabel, R D Fish, J Zebede, G H Mudge, R W Alexander, A P Selwyn

Elevated intracellular Ca2+ acts through protein kinase C to regulate rabbit ileal NaCl absorption. Evidence for sequential control by Ca2+/calmodulin and protein kinase C.

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Calcium/calmodulin is involved in the regulation of basal rabbit ileal active Na and Cl absorption, but the mechanism by which elevated intracellular Ca2+ affects Na and Cl transport is unknown. To investigate the roles of the Ca2+/calmodulin and protein kinase C systems in ileal NaCl transport, two drugs, the isoquinolenesulfonamide, H-7, and the naphthalenesulfonamide, W13, were used in concentrations that conferred specificity in the antagonism of protein kinase C (60 microM H-7) and Ca2+/calmodulin (45 microM W13), respectively, as determined using phosphorylation assays in ileal villus cells. W13 but not H-7 stimulated basal active NaCl absorption. H-7 inhibited changes in Na and Cl absorption caused by maximal concentrations of Ca2+ ionophore A23187 and carbachol and serotonin, secretagogues that act by increasing cytosol Ca2+, while W13 had no effect. In contrast, neither H-7 nor W13 altered the change in NaCl transport caused by the cyclic nucleotides 8-Br-cAMP and 8-Br-cGMP. These data suggest that: (a) basal rabbit ileal NaCl absorption is regulated by the Ca2+/calmodulin complex and not by protein kinase C; (b) the effect of elevating intracellular Ca2+ to decrease NaCl absorption is mediated via protein kinase C but not by Ca2+/calmodulin; (c) the effects of protein kinase C are not overlapping or synergistic with those of Ca2+/calmodulin on either basal absorption or on the effects of increased Ca2+; and (d) neither Ca2+/calmodulin nor protein kinase C are involved in the effects of cAMP and cGMP on ileal active NaCl transport.

Authors

M Donowitz, M E Cohen, M Gould, G W Sharp

Formyl peptide-induced chemotaxis of human polymorphonuclear leukocytes does not require either marked changes in cytosolic calcium or specific granule discharge. Role of formyl peptide receptor reexpression (or recycling).

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We examined the role of intracellular and extracellular calcium on the ability of human polymorphonuclear leukocytes to migrate chemotactically and reexpress (or recycle) formyl peptide receptors when challenged with the synthetic chemotactic peptide, N-formyl-methionyl-leucyl-phenylalanine (FMLP). Extracellular calcium was not required for either optimal chemotactic responses or receptor reexpression. Depletion and chelation of intracellular calcium resulted in significant diminution in the ability of polymorphonuclear leukocytes to release the specific granule constituents lactoferrin and vitamin B12-binding protein during the process of chemotaxis, but had no effect on the capability of these cells to respond chemotactically. Similarly, chelation of intracellular calcium did not affect the ability of these cells to reexpress a population of formyl peptide receptors. Inhibition of receptor reexpression, by a nonagglutinating derivative of wheat-germ agglutinin, was associated with inhibition of chemotactic responses to FMLP. Thus, it appears that large changes in cytosolic free calcium are not necessary for formyl peptide-induced polymorphonuclear leukocyte chemotaxis. In contrast, continuous reexpression (or recycling) of formyl peptide receptors is required for polymorphonuclear leukocyte chemotactic responses to FMLP, a process that appears to be independent from specific granule fusion with plasma membrane.

Authors

H D Perez, F Elfman, S Marder, E Lobo, H E Ives

Clonal analysis of childhood acute lymphoblastic leukemia with "cytogenetically independent" cell populations.

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Acute lymphoblastic leukemia (ALL) is generally regarded as a clonal disease in which a single abnormal progenitor cell gives rise to neoplastic progeny. Five of 463 cases of childhood ALL with adequately banded leukemic cells were found to have two cytogenetically independent cell populations. In addition, two of the four cases tested had more than two rearranged immunoglobulin genes and (or) T cell receptor genes. To investigate the clonality of these unusual leukemias, we examined the neoplastic cells for X-linked markers extrinsic to the disease. Leukemic cells from each of the three patients heterozygous for an X-linked, restriction fragment length polymorphism showed a single active parental allele, suggesting that both apparently independent cell populations developed from a common progenitor. These cases provide evidence that leukemogenesis involves a multistep process of mutation and suggest that karyotypic abnormalities may be a late event of malignant transformation.

Authors

C H Pui, W H Raskind, G R Kitchingman, S C Raimondi, F G Behm, S B Murphy, W M Crist, P J Fialkow, D L Williams

Molecular basis of factor VIII inhibition by human antibodies. Antibodies that bind to the factor VIII light chain prevent the interaction of factor VIII with phospholipid.

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Abstract

Most antibodies to factor VIII have recently been shown to react with discrete regions of the factor VIII light chain (within the C2 domain) and/or the factor VIII heavy chain (within the amino-terminal segment of the A2 domain). The mechanism by which these antibodies, usually designated "factor VIII inhibitors," interfere with factor VIII function has been examined by determining their effect on factor VIII binding to a phospholipid. Factor VIII-phosphatidylserine binding was prevented by all seven factor VIII inhibitors that had strong factor VIII light chain reactivity and reduced by two inhibitors with weak anti-light chain reactivity. None of four inhibitors with heavy chain reactivity prevented factor VIII-phosphatidylserine interaction, though a partial reduction (less than 50%) was noted for the intact IgG preparations. However, when Fab' fragments were substituted, no detectable reduction in factor VIII-phosphatidylserine binding was noted for the anti-heavy chain inhibitors and complete inhibition was retained by the anti-light chain inhibitors. These data suggest that a subset of factor VIII inhibitors, those that bind to light chain determinants, inactivate factor VIII by preventing its effective interaction with phospholipid.

Authors

M Arai, D Scandella, L W Hoyer

Characterization and histologic localization of human growth hormone-variant gene expression in the placenta.

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Abstract

The human growth hormone-variant (hGH-V) gene is one of five highly similar growth hormone-related genes clustered on the short arm of chromosome 17. Although the pattern of expression of the adjacent normal growth hormone (hGH-N) and chorionic somatomammotropin (hCS) genes in this cluster are well characterized, the expression of the hGH-V gene remains to be defined. In previous studies, we have demonstrated that the hGH-V gene is transcribed in the term placenta and expressed as two alternatively spliced mRNAs: one is predicted to encode a 22-kD hormone (hGH-V), the other retains intron 4 in its sequence resulting in the predicted synthesis of a novel 26-kD hGH-V-related protein (hGH-V2). In the present report, we document the expression of both of these hGH-V mRNA species in the villi of the term placenta, demonstrate an increase in their concentrations during gestation, and directly sublocalize hGH-V gene expression to the syncytiotrophoblastic epithelium of the term placenta by in situ cDNA-mRNA histohybridization. The demonstrated similarity in the developmental and tissue-specific expression of the hGH-V gene with that of the related hCS gene suggests that these two genes may share common regulatory elements.

Authors

S A Liebhaber, M Urbanek, J Ray, R S Tuan, N E Cooke

Identification and characterization of cell-substratum adhesion receptors on cultured human endothelial cells.

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Abstract

A series of immunological approaches was utilized to identify the molecules involved in cell-substratum adhesion of human endothelial cells (EC) derived from adult large vessels, fat capillaries, and umbilical veins. A polyclonal antibody prepared against partially purified extracellular matrix receptors disrupted adhesion of EC to a wide variety of substrates and identified four groups of glycoproteins migrating with apparent Mr of 150, 125, 110, and 95 kD in immunoprecipitation experiments. Specific monoclonal antibodies identified these proteins as members of the Integrin family of extracellular matrix receptors and included the alpha and beta chains of the fibronectin receptor (alpha 5/beta 1), a collagen receptor (alpha 2 beta 1), a multifunctional receptor that binds to fibronectin, collagen, and laminin (alpha 3/beta 1), as well as a receptor related to platelet IIb/IIIa (alpha v/beta 3). To directly test the importance of these molecules in cell-substratum adhesion, these proteins were purified by a combination of ion exchange, lectin affinity, and immunoaffinity chromatography and used to block the biological activity of the adhesion-disrupting polyclonal antibody. Immunofluorescence experiments further supported the role of these glycoproteins in adhesion. The GPIIb/IIIa-like receptor localized to well-formed adhesion plaques on EC plated on fibrinogen, but not on fibronectin, laminin, or type IV collagen. Receptors containing the beta 1 subunit were visualized as discontinuous fibrils which colocalized with fibronectin fibrils and actin stress fibers.

Authors

S M Albelda, M Daise, E M Levine, C A Buck

Mithramycin blocks protein binding and function of the SV40 early promoter.

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Abstract

Specific interactions between DNA and transcription factors are necessary for transcription initiation. These interactions provide a potential target for the selective inhibition of eukaryotic gene expression. Mithramycin is a DNA binding antibiotic which, in the presence of Mg2+, binds G-C containing sequences in the minor groove. The SV40 early promoter contains six G-C decanucleotide sequences, which are binding sites for the transcriptional activating factor, Sp1. Each of the six Sp1 binding sites of this promoter is protected from DNAse 1 digestion by mithramycin binding. Mithramycin binding to the G-C rich sequences in the SV40 early promoter prevents subsequent protein binding to these sequences. The gel retardation of the SV40 early promoter fragment incubated with a HeLa cell extract is completely abrogated by pretreatment of the DNA fragment with mithramycin. The functional significance of mithramycin binding is reflected in the ability of mithramycin to block promoter function. Mithramycin inhibits promoter dependent transcription in an in vitro runoff transcription system in a concentration dependent manner. This suggests that mithramycin prevents transcriptional activation of the SV40 early promoter by blocking binding of transcriptional activating proteins to G-C rich promoter regions.

Authors

R Ray, R C Snyder, S Thomas, C A Koller, D M Miller

Cooperative interactions of LFA-1 and Mac-1 with intercellular adhesion molecule-1 in facilitating adherence and transendothelial migration of human neutrophils in vitro.

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Abstract

The adherence of human neutrophils to human umbilical vein endothelial cells (HUVEC) is partially dependent on the CD11/CD18 family of glycoproteins on the neutrophil and ICAM-1 on the HUVEC. The CD18 heterodimer involved in this adherence was evaluated in vitro using subunit-specific monoclonal antibodies (MAbs). The adherence of unstimulated neutrophils to IL-1-stimulated HUVEC was significantly inhibited by anti-CD11a but not CD11b MAbs, while the adherence of fMLP-stimulated neutrophils was significantly inhibited by both anti-CD11a and -CD11b. Anti-CD11a, but not anti-CD11b MAbs, reduced the adherence of unstimulated neutrophils on purified ICAM-1 to the same low level untreated neutrophils exhibited on a control protein, glycophorin. Stimulation with fMLP significantly increased neutrophil attachment to purified ICAM-1, but not to the control protein. Anti-CD11b MAbs reduced this chemotactically augmented adherence to that of unstimulated neutrophils, and in combination with anti-CD11a MAbs reduced adherence to that on the control protein. The results in this report indicate that unstimulated neutrophils exhibit LFA-1-dependent attachment to ICAM-1, and chemotactic stimulation enhances the attachment of human neutrophils to ICAM-1 by a Mac-1-dependent process.

Authors

C W Smith, S D Marlin, R Rothlein, C Toman, D C Anderson

Inhibition of cholesteryl ester transfer protein activity by monoclonal antibody. Effects on cholesteryl ester formation and neutral lipid mass transfer in human plasma.

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Abstract

We have employed a neutralizing monoclonal antibody, prepared against the Mr 74,000 cholesteryl ester transfer protein (CETP), to investigate the regulation of lecithin:cholesterol acyltransferase (LCAT) activity by cholesteryl ester (CE) transfer, and also to determine which lipoproteins are substrates for LCAT in human plasma. The incubation of normolipidemic plasma led to transfer of CE from HDL to VLDL, and of triglycerides from VLDL to LDL and HDL. This net mass transfer of neutral lipids between the lipoproteins was eliminated by the monoclonal antibody. However, CE transfer inhibition had no effect on the rate of plasma cholesterol esterification in plasma incubated from 10 min to 24 h at 37 degrees C. In the absence of CE transfer, HDL and LDL exhibited cholesterol esterification activity, whereas VLDL did not. The rate of CE formation in HDL was three to four times greater than in LDL during the first hour of incubation, but CE formation in HDL decreased after 6-8 h, while that in LDL continued. Thus, (a) the Mr 74,000 CETP is responsible for all neutral lipid mass transfer in incubated human plasma, (b) the rate of CE formation in plasma is not regulated by CE transfer from HDL to other lipoproteins, and (c) HDL is the major initial substrate for LCAT; LDL assumes a more significant role only after prolonged incubation of plasma.

Authors

F T Yen, R J Deckelbaum, C J Mann, Y L Marcel, R W Milne, A R Tall

pp60c-src activation in human colon carcinoma.

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Abstract

We measured the in vitro protein-tyrosine kinase activity of pp60c-src from human colon carcinoma cell lines and tumors. The activity of pp60c-src from six of nine carcinoma cell lines was higher (on average, fivefold as measured by enolase phosphorylation, or eightfold as measured by autophosphorylation) than that of pp60c-src from normal colonic mucosal cells, or human or rodent fibroblasts. Similarly, the activity of pp60c-src from 13 of 21 primary colon carcinomas was five- or sevenfold higher than that of pp60c-src from normal colonic mucosa adjacent to the tumor. The increased pp60c-src activity did not result solely from an increase in the level of pp60c-src protein, suggesting the specific activity of the pp60c-src kinase is elevated in the tumor cells. pp60c-src from colon carcinoma cells and normal colonic mucosal cells was phosphorylated at similar sites. We used immunoblotting with antibodies to phosphotyrosine to identify substrates of protein-tyrosine kinases in colonic cells. Three phosphotyrosine-containing proteins were detected at significantly higher levels in most colon carcinoma cell lines than in normal colonic mucosal cells or human or rat fibroblasts. All colon carcinoma cell lines with elevated pp60c-src in vitro kinase activity, showed increased phosphorylation of proteins on tyrosine in vivo, suggesting the presence of an activated protein-tyrosine kinase(s).

Authors

C A Cartwright, M P Kamps, A I Meisler, J M Pipas, W Eckhart

Molecular cloning and chromosomal mapping of DNA rearranged with the parathyroid hormone gene in a parathyroid adenoma.

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Abstract

Parathyroid adenomas are common benign neoplasms for which no chromosomal defects have been described. We recently found two parathyroid adenomas bearing clonal restriction fragment abnormalities involving the PTH locus, and now show that in one of these tumors: (a) a DNA rearrangement occurred at the PTH locus; (b) the rearrangement separated the PTH gene's 5' flanking region from its coding exons, conceivably placing a newly adjacent gene under the influence of PTH regulatory elements; (c) the DNA that recombined with PTH normally maps to 11q13, the known chromosomal location of several oncogenes and the gene for multiple endocrine neoplasia type I; and (d) the rearrangement was a reciprocal, conservative recombination of the locus on 11q13 (Human Gene Mapping Library assignment D11S287) with PTH (on 11p15). These data provide molecular cytogenetic evidence for the clonal occurrence of a major chromosome 11 aberrancy in this benign parathyroid tumor. The D11S287 clone could prove useful in genetic linkage analyses, in determining precise 11q13 breakpoints in other neoplasms, and in identifying a gene on chromosome 11 that may participate in parathyroid tumor development.

Authors

A Arnold, H G Kim, R D Gaz, R L Eddy, Y Fukushima, M G Byers, T B Shows, H M Kronenberg

Role of surface proteins in staphylococcal adherence to fibers in vitro.

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Abstract

To study the role of surface proteins in the adherence of Staphylococcus aureus to fibers that are used in tampon and surgical gauze pad manufacture, we have developed an adherence assay with S. aureus cells and cotton and rayon fibers. Results suggest that staphylococcal adherence is dependent on both the substrate and the material used to coat these fibers. Scanning electron micrographs supported the adherence results and revealed more cells on the surface of cotton than rayon fibers. Treatment of staphylococcal cells with proteolytic enzymes significantly reduced binding to pure cotton and detergent-treated cotton fibers. Immunoblot analysis of cell wall proteins suggested that surface proteins in the mol wt range of 120-220 kD were involved in the adherence of S. aureus to cotton fibers. Although the adherence of S. aureus to cotton fibers alone appeared to be mediated through surface charge or hydrophobic interactions, bacterial binding to fibers which have been pretreated with defibrinated blood appeared to be more specific and independent of the surface constituents of the fibers. The results of these studies implicate staphylococcal surface proteins in the adherence of S. aureus to commercially available tampon fibers and surgical gauze pads.

Authors

A L Cheung, V A Fischetti

Guanine nucleotide binding regulatory proteins and adenylate cyclase in livers of streptozotocin- and BB/Wor-diabetic rats. Immunodetection of Gs and Gi with antisera prepared against synthetic peptides.

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Abstract

Adenylate cyclase in liver plasma membranes from streptozotocin-diabetic (STZ) or BB/Wor spontaneously diabetic rats showed increased responsiveness to GTP, glucagon, fluoroaluminate, and cholera toxin. Basal or forskolin-stimulated activity was unchanged in STZ rats, but increased in BB/Wor rats. No change in the alpha-subunit of Gi (alpha i) was observed in STZ or BB/Wor rats using pertussis toxin-stimulated [32P]ADP-ribosylation. Immunodetection using antibodies against the COOH-terminal decapeptides of alpha T and alpha i-3 showed no change in alpha i in STZ rats and a slight decrease in BB/Wor rats. Angiotensin II inhibition of hepatic adenylate cyclase was not altered in either diabetic rat. In both models of diabetes, Gs alpha-subunits were increased as measured by cholera toxin-stimulated [32P]-ADP-ribosylation of 43-47.5-kD peptides, reconstitution with membranes from S49 cyc- cells or immunoreactivity using antibodies against the COOH-terminal decapeptide of alpha s. These data indicate that STZ-diabetes increases hepatic Gs but does not change Gi or adenylate cyclase catalytic activity. In contrast, BB/Wor rats show increased hepatic Gs and adenylate cyclase. These changes could explain the increase in hepatic cAMP and related dysfunctions observed in diabetes.

Authors

C J Lynch, P F Blackmore, E H Johnson, R L Wange, P K Krone, J H Exton

Effects of polycations on pulmonary vascular permeability in conscious sheep.

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Abstract

The role of charged sites on the permeability characteristics of the pulmonary microvascular barrier were investigated using chronically instrumented unanesthetized sheep. In one series of experiments we studied the effects of the cationic amphiphile, dodecyl trimethylamine (DTA; 297 mol wt), and the anionic amphiphile, SDS (288 mol wt), on lung lymph flow rates (Ql), lung lymph to plasma protein ratios (L/P), pulmonary hemodynamics, and systemic hemodynamics. DTA significantly increased both Ql and L/P, whereas SDS had a more modest and transient effect on these variables. In a second series of experiments the polycations polybrene and poly-l-lysine were found to have very similar effects as those of DTA. In another series of experiments we tested the pretreatment inhibition potential of chlorpheniramine (an H1 receptor antagonist), dibutyryl-cyclic AMP (db-cAMP), and the calcium channel antagonists verapamil and nifedipine on polybrene-induced lung injury. We found that only verapamil and db-cAMP significantly attenuated the permeability effects of polybrene. We conclude that both cationic amphiphiles and polycations cause hemodynamic and permeability alterations in the pulmonary circulation of unanesthetized sheep. In addition, the permeability alterations induced by polybrene can be modulated by intracellular calcium and/or cAMP levels.

Authors

T Toyofuku, S Koyama, T Kobayashi, S Kusama, G Ueda

A gene conversion located 5' to the A gamma gene in linkage disequilibrium with the Bantu haplotype in sickle cell anemia.

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Abstract

Cloning and sequencing of the gamma-globin gene of a sickle cell anemia patient homozygous for the Bantu haplotype has revealed a gene conversion that involves the replacement of an A gamma sequence by a G gamma sequence in the promoter area of the A gamma gene. This event is similar to another gene conversion believed to be responsible for the very high homology between gamma-globin genes, suggesting that the promoter area of these genes is prone to this type of genetic rearrangement. Further analysis demonstrated that the chromosome bearing this gene conversion has a very high frequency among Bantu chromosomes and a very low or nil frequency in other haplotypes linked to the beta s gene. No correlation was found between the G gamma/A gamma ratio and the presence of the gene conversion among Bantu haplotype patients, thus excluding a portion of the gamma gene sequence in the determination of this ratio.

Authors

E E Bouhassira, H Lachman, R Krishnamoorthy, D Labie, R L Nagel

Effect of ultrasound on transdermal drug delivery to rats and guinea pigs.

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Abstract

The effect of therapeutic range ultrasound (1 MHz) on skin permeation of D-mannitol, a highly polar sugar alcohol, inulin, a high molecular weight polysaccharide and physostigmine, a lipophilic anticholinesterase drug was studied in rats and guinea pigs. D-Mannitol and inulin are totally and rapidly excreted, once they have penetrated through the skin into the blood stream, permitting direct in vivo monitoring. For evaluating skin penetration of physostigmine the decrease of whole blood cholinesterase was measured. Ultrasound nearly completely eliminated the lag time usually associated with transdermal delivery of drugs. 3-5 min of ultrasound irradiation (1.5 W/cm2 continuous wave or 3 W/cm2 pulsed wave) increased the transdermal permeation of inulin and mannitol in rats by 5-20-fold within 1-2 h following ultrasound application. Ultrasound treatment also significantly increased (P less than 0.05) the inhibition of cholinesterase during the first hour after application in both physostigmine treated rats and guinea pigs: while in control guinea pigs no significant inhibition of cholinesterase could be detected during the first 2 h after application of physostigmine, the ultrasound treated group showed a 15 +/- 5% (mean +/- SEM) decrease in blood cholinesterase 1 h after ultrasound application. For physostigmine-treated rats the level of cholinesterase inhibition 1 h after ultrasound application was 53 +/- 5% in the ultrasound-treated group and 35 +/- 5% in the controls.

Authors

D Levy, J Kost, Y Meshulam, R Langer

High concentrations of catecholamines in human hypothalamic-hypophysial blood.

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Abstract

While the hypothalamic-hypophysial portal system has been extensively studied in laboratory animals, equivalent studies have not been performed in humans. Here, we present an experimental procedure for collecting suprapituitary blood in man. To solve the question on the origin of such blood we investigated specific markers of hypothalamic secretory activity: the catecholamines (CAs). We found (a) norepinephrine (NE), dopamine (DA), and epinephrine (E) concentrations from approximately 1.5 to 2.5, 3.5 to 4.5, and 6- to 10-fold higher, respectively, in suprapituitary than peripheral blood, (b) different NE/DA and NE/E ratios in favor of DA and E in suprapituitary blood, and (c), a complete (100%) group separation (suprapituitary vs. peripheral) when discriminant analysis included only DA and E. These data indicate that suprapituitary blood composition is different from that of the peripheral blood, and is particularly rich in CAs and claimed differences between DA and E release on one hand and NE release on the other in suprapituitary blood also are observed. We advance the hypothesis of a hypothalamic source of such amines draining via median eminence into portal vasculature, and name this blood "hypothalamic-hypophysial blood." Besides serving as "classical" neurotransmitters, CAs may also have a direct neurohormonal role in the regulation of the human hypothalamic-hypophysial function.

Authors

R Paradisi, G Frank, G Grossi, S Venturoli, E Porcu, M Capelli, E Galassi, C Flamigni

Human decidua is a major source of renin.

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Abstract

Plasma prorenin levels are elevated in normal pregnant women. Current evidence suggests renin production by tissues of the uteroplacental unit contribute to this elevation. The purpose of this investigation was to define the source of renin biosynthesis within the human uteroplacental unit and to characterize the renin produced. RNA extraction and Northern blot analysis consistently demonstrated renin mRNA expression in uterine lining both in the pregnant (decidua) and nonpregnant states (endometrium) and in fetal chorion laeve, which is inseparable from the decidua. In contrast, renin mRNA expression was not detected in basal plate and intertwin chorion (which is separate from decidua), amnion, myometrium, or placental villi. The total renin content in decidual homogenates was two- to threefold greater than in endometrial homogenates, and cultured human decidual cells produced significantly more total renin than cultured human endometrial cells, suggesting that pregnancy enhanced renin production by the cells lining the uterus. Immunoblot analysis and [3H]leucine incorporation identified 47,000-mol wt prorenin as the major form of renin produced by cultured human decidual cells. These studies indicate that maternal decidua is the major source of prorenin in the uteroplacental unit.

Authors

K J Shaw, Y S Do, S Kjos, P W Anderson, T Shinagawa, L Dubeau, W A Hsueh

Selective expression of a normal action of the 1,25-dihydroxyvitamin D3 receptor in human skin fibroblasts with hereditary severe defects in multiple actions of that receptor.

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Abstract

We evaluated three actions of 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] in human skin fibroblasts to test for heterogeneity in hormone-response coupling. In fibroblasts from normal subjects the 1,25-(OH)2D3 concentrations for half-maximal effect (EC50) were: for mitogenic effect 0.0001-0.0005 nM, for antimitogenic effect 1 nM, and for induction of 25-OHD3 24-hydroxylase (24-OHase) 5 nM. To evaluate the effects of mutations presumed to be in the gene for the 1,25-(OH)2D3 receptor we examined cell lines representing four kindreds with hereditary resistance to 1,25-(OH)2D3 ("mutant" cell lines). In one mutant cell line all three 1,25-(OH)2D3 actions were severely abnormal. In one mutant cell line 24-OHase induction and mitogenic action were undetectable, but EC50 and maximal effect were normal for antimitogenic action of 1,25-(OH)2D3. In two mutant cell lines 24-OHase induction and antimitogenic actions were undetectable or severely impaired but mitogenic action were undetectable or severely impaired but mitogenic action was normal in EC50 and normal or increased in maximal effect. The mitogenic and antimitogenic actions in normal cells showed a similar profile of potency ratios for 1,25-(OH)2D3 and six analogues. Whenever a mutant cell showed a normal or even an abnormal mitogenic or antimitogenic effect of 1,25-(OH)2D3, these effects showed potency ratios similar to wild type, suggesting mediation by a similar 1,25-(OH)2D3 receptor. We conclude that three 1,25-(OH)2D3 actions show important differences in hormone response coupling indicated by differences in EC50 for 1,25-(OH)2D3 and by different consequences of receptor mutations.

Authors

J Barsony, W McKoy, D A DeGrange, U A Liberman, S J Marx

Gal-Gal pili vaccines prevent pyelonephritis by piliated Escherichia coli in a murine model. Single-component Gal-Gal pili vaccines prevent pyelonephritis by homologous and heterologous piliated E. coli strains.

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Abstract

The initial pathogenic step in nonobstructive Escherichia coli pyelonephritis usually involves the binding of a bacterial adhesin with host uroepithelial glycoprotein receptors containing the D-Gal p alpha 1----4 D-Gal p beta 1 (Gal-Gal) moiety. In this study, groups of mice were immunized with Gal-Gal pili and challenged 2 wk later intravesicularly with E. coli strains expressing homologous or heterologous pili. 63 of 129 pili-immunized mice (49%) were protected from subsequent E. coli renal colonization compared with 5 of 85 control mice (6%). Among mice that had E. coli cultured from their right kidney, control mice had greater bacterial colony counts than pili-immunized animals (P less than 0.05). Light microscopic examination of kidneys demonstrated less histopathology among pili immunized mice than among control mice (P less than 0.05). Protection correlated with the presence of specific IgG antibodies in the urine and serum that bind to the major pilin structural polypeptide and not to the Gal-Gal pili tip adhesin per se. These results support the concept that immunization with a bacterial surface-coat constituent can prevent mucosal infection by interfering with colonization. Also Gal-Gal pili of E. coli represent a suitable candidate for immunoprophylaxis against pyelonephritis.

Authors

B Pecha, D Low, P O'Hanley

Characterization of concentration- and use-dependent effects of quinidine from conduction delay and declining conduction velocity in canine Purkinje fibers.

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Abstract

The dynamic response of squared conduction velocity, theta 2, to repetitive stimulation in canine Purkinje fibers with quinidine was studied using a double-microelectrode technique. With stimulation, a frequency-dependent monoexponential increase in conduction delay (CD) and a decline in theta 2 were observed. The exponential rates and changes in steady-state CD and theta 2 were frequency- and concentration-dependent. The overall drug uptake rates describing blockade and the interpulse recovery interval were linearly related and steady-state values of theta 2 were linearly related to an exponential function of the stimulus intervals. Based on first-order binding, the frequency- and concentration-dependent properties of quinidine were characterized by the apparent binding and unbinding rates of 14.2 +/- 5.7 X 10(6) mol-1.s-1 and 63 +/- 12 s-1 for activated and 14.8 +/- 1.0 X 10(2) mol-1.s-1 and 0.16 +/- 0.03 s-1 for resting states. The recovery time constant extracted from the pulse train interpulse interval was 5.8 +/- 1.5 s compared with 5.1 +/- 0.6 s determined from a posttrain test pulse protocol. This study demonstrates that the kinetics of drug action can be derived from measures of impulse propagation. This provides a basis for characterizing frequency-dependent properties of antiarrhythmic agents in vivo and suggests the plausibility of a quantitative assessment of drug binding and recovery rates in man.

Authors

D L Packer, A O Grant, H C Strauss, C F Starmer

Lack of expression of aminoacylase-1 in small cell lung cancer. Evidence for inactivation of genes encoded by chromosome 3p.

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Abstract

A deletion involving chromosome 3p (14-23) characteristically occurs in small cell lung cancer (SCLC). Reduction to homozygosity, rather than complete loss, is typically observed for genes in the deleted region. Lack of expression for genes encoded by this region, implying inactivation of all alleles, has not been previously described. We have examined the expression of aminoacylase-1 (ACY-1), encoded by chromosome 3p21, using both an electrophoretic activity assay and a monoclonal antibody-based ELISA. A variety of human tissues, including lung, brain, liver, kidney, heart, adrenal medulla, and erythrocytes have previously been tested for ACY-1 activity and antigen; all but erythrocytes are positive. Thus, ACY-1 is expressed in all nucleated human cells examined to date. ACY-1 was undetectable in a significant number of SCLC cell lines (4/29) and tumors (1/8), but not in non-small cell lung cancer (NSCLC) cell lines (0/19) or tumors (0/9), nor in a variety of other human cell lines (0/15) or colon tumors (0/8). In addition, reduced (approximately 10% of normal) ACY-1 expression was common in SCLC cell lines (14/29) and tumors (3/8), but not in NSCLC cell lines (1/19) or tumors (0/9), nor in other human cell lines (0/15) or colon tumors (0/8). Thus, low or undetectable ACY-1 expression is highly specific for SCLC and occurs in both cell lines and tumor tissue. The finding of undetectable ACY-1 expression in SCLC supports the hypothesis that inactivation of all alleles of specific chromosome 3p genes occurs in a SCLC in a fashion analogous to Rb gene inactivation in retinoblastoma, and suggests that the structural gene for ACY-1 may be closely linked to a putative SCLC tumor suppressor gene.

Authors

Y E Miller, J D Minna, A F Gazdar

Intravenous infusion of apolipoprotein E accelerates clearance of plasma lipoproteins in rabbits.

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Abstract

Plasma cholesterol levels in cholesterol-fed rabbits were markedly reduced by the intravenous infusion or bolus injection of recombinant human apo E or rabbit plasma apo E. Administration of 6-70 mg of apo E resulted in an approximately 20-40% acute reduction in plasma cholesterol levels within 2-3 h. Plasma cholesterol levels remained reduced for 4-8 h after the administration of apo E. Furthermore, the intravenous injection of apo E reduced the plasma cholesterol levels in Watanabe heritable hyperlipidemic rabbits. The addition of apo E to [14C]cholesterol-labeled canine thoracic duct lymph or [14C]cholesterol-labeled chylomicrons resulted in accelerated plasma clearance of these diet-induced lipoproteins in normal rabbits, with the uptake occurring primarily in the liver. This study suggests that the amount or availability of apo E in the plasma of cholesterol-fed rabbits may be rate limiting for the normal clearance of diet-induced remnant lipoproteins.

Authors

R W Mahley, K H Weisgraber, M M Hussain, B Greenman, M Fisher, T Vogel, M Gorecki