Linkage and association of adrenergic and dopamine receptor genes in the distal portion of the long arm of chromosome 5 with systolic blood pressure variation

Elevated blood pressure is an important risk factor for renal-, cerebro- and cardiovascular diseases. We used an efficient discordant sib-pair ascertainment scheme to investigate the impact of the distal end of the long arm of human chromosome 5 (chromosomal region 5q31.1-qter) containing genes for the alpha1B and beta2 adrenergic receptors and the dopamine receptor type 1A on variation of systolic blood pressure in young Caucasians. We measured eight highly polymorphic markers spanning this positional candidate gene-rich region in 427 individuals from 55 three-generation pedigrees containing 69 discordant sibling pairs, and calculated multipoint identity by descent (MIBD) probabilities. The results of genetic linkage and association tests indicate that the region between markers D5S2093 and D5S462 is significantly linked to one or more polymorphic genes influencing interindividual variation in systolic blood pressure levels. Since the alpha1B adrenergic receptor and dopamine receptor type 1A genes are located close to these markers, these data suggest that genetic variation in one or both of these G protein-coupled receptors, which participate in the control of vascular tone, plays an important role in influencing interindividual variation in systolic blood pressure levels.      

Monoclonal antibodies to the enterotoxin of Bacteroides fragilis: production, characterization, and immunodiagnostic application.

A monoclonal antibody, ICT11, specific for the toxin of enterotoxigenic Bacteroides fragilis (ETBF) neutralized the cytotoxic effect of the toxin on human colonic cell line HT-29/C1. In an evaluation using 115 diarrheal stool specimens and culture as the "gold standard," the assay showed a sensitivity of 85% and a specificity of 100%. An ICT11-based sandwich enzyme-linked immunosorbent assay showed a sensitivity of 100% and a specificity of 98% for direct detection of toxin from stool samples compared with those of culture. Thus, ICT11-based assays will be useful for screening for ETBF.     

Regulation of intestinal guanylate cyclase by the heat-stable enterotoxin of Escherichia coli (STa) and protein kinase C.

The heat-stable enterotoxin of Escherichia coli (STa) stimulates membrane-bound guanylate cyclase in intestinal epithelium and induces fluid and ion secretion. Using the T84 human colon carcinoma cell line as a model, we observed that phorbol esters markedly enhanced STa-stimulated cyclic GMP accumulation in T84 cells (C. S. Weikel, C. L. Spann, C. P. Chambers, J. K. Crane, J. Linden, and E. L. Hewlett, Infect. Immun. 58:1402-1407, 1990). In this study we document that the phorbol ester treatment increases 125I-STa-binding sites as well as membrane-bound guanylate cyclase activity in T84 cells and provide evidence that both effects are mediated by phosphorylation. Guanylate cyclase activity was increased approximately 50% in membranes prepared from intact T84 cells treated with phorbol-12,13-dibutyrate (beta-PDB) and after treatment of homogenates with beta-PDB in a manner dependent on ATP, MgCl2, and cytosol. Similarly, treatment of membranes with purified bovine brain protein kinase C in the presence of appropriate cofactors and beta-PDB resulted in an increase in STa-stimulated guanylate cyclase activity of about 70%. Likewise, the number of 125I-STa-binding sites was increased by about 25 to 40% in membranes prepared from intact cells or homogenates treated with beta-PDB; no effect on binding affinity (Kd = 0.15 nM) was noted. These experiments suggest that protein kinase C may phosphorylate the STa receptor-guanylate cyclase or a closely related protein and increase guanylate cyclase activity. The stimulatory effects of protein kinase C on STa-sensitive guanylate cyclase are opposite in direction to the profound inhibitory effects of the kinase on atrial natriuretic peptide-stimulated guanylate cyclase, demonstrating differential regulation by protein kinases within the guanylate cyclase-receptor family.     

Evidence of only one H-2D/L-related glycoprotein in H-2dm1 mutant cells

Analyses of the H-2D/L-related glycoproteins from dm1 mutant cell extracts by sequential immunoprecipitation, by SDS gel electrophoresis and by tryptic peptide mapping indicate that dm1 cells express only a single glycoprotein with H-2D/L-related determinants. In contrast to the four H-2D/L-related antigens identified for the parental d haplotype viz. H-2Dd, H-2Md, H-2Ld and H-2Rd, separate and distinguishable "H-2Ddm1", "H-2Mdm1", "H-2Ldm1" and "H-2Rdm1" glycoprotein counterparts are apparently lacking in the dm1 mutant haplotype. Only a single H-2D/L-related glycoprotein is identified in dm1 extracts by standard serological methods and this glycoprotein is designated H-2D/Ldm1 because of its H-2Dd/H-2Ld hybrid characteristics, as recently shown by Burnside and colleagues (1984). Thus, the seemingly complex phenotype of the dm1 mutant appears to originate primarily from one molecule having properties of two (or more) molecules of the parental haplotype.     

Delayed hypersensitivity skin testing and anergy in a population of gay men

Anergy is almost universal among patients with the acquired immunodeficiency syndrome (AIDS). To determine the prevalence and correlates of anergy in a population at risk for AIDS, we performed skin tests in 1120 gay men who were enrolled in a prospective study of the natural history of human immunodeficiency virus (HIV) infection. Anergy, defined as no induration to any of four intradermal antigens, was present in 12%. Individually, no induration was detected in response to tetanus toxoid (41%), mumps (28%), candida (47%), and trichophyton (72%). Anergy was strongly associated with the presence of antibody to HIV and with a reduced number of T helper lymphocytes, but not independently with generalized lymphadenopathy, the number of reported male sexual partners in the previous 2 years, the number of T suppressor lymphocytes, or with high titers of antibodies to cytomegalovirus. Nine percent of HIV antibody-negative subjects and 20% of antibody-positive subjects were anergic; anergy is not specific for serologically documented HIV infection in this population. Skin testing with only tetanus toxoid, candida, and mumps antigens may be sufficient to detect anergy. In the presence of HIV antibody, the ability of anergy to predict progressive immunodeficiency remains to be determined.     

H-2 restriction and serotype crossreactivity of anti-reovirus cytotoxic T lymphocytes (CTL)

Murine anti-reovirus cytotoxic T lymphocytes (CTLs) were analyzed for H-2 restricted recognition of virus infected target cells and for potential cross-reactivity with cells infected by reovirus serotype 1 (T1; Lang strain) or by serotype 3 (T3; Dearing strain). Anti-reovirus CTL specifically lysed virus infected cells and lysis was shown to be H-2 restricted by the H-2Dd, H-2Ld, H-2Kd, H-2Kb, and H-2Kk antigens. No H-2 antigens were identified which failed to restrict virus recognition by anti-reovirus CTL. Anti-T1 and anti-T3 CTLs were also shown to crossreact completely with cells infected with the opposite virus serotype. Thus, anti-reovirus CTLs are restricted by a broad spectrum of H-2 antigens and they detect common rather than unique structural components of these two viral serotypes.     

Carcinoma of the esophagus with adenoid cystic differentiation

Adenoid cystic carcinoma of the esophagus is a relatively rare lesion which characteristically exhibits a clinically aggressive behavior. In spite of this aggressive nature, it is most often referred to as a counterpart of the more common adenoid cystic carcinoma of salivary gland origin, a comparatively indolent tumor. In this report, the clinical and pathologic findings in a series of six cases of esophageal adenoid cystic carcinomas are contrasted with those of typical salivary gland lesions, and also compared to similar tumors exhibiting "adenoid cystic" differentiation arising in other extrasalivary gland sites. It is concluded that the esophageal tumors, as well as certain similar lesions arising in other extrasalivary gland sites, represent a class of poorly differentiated basaloid neoplasms distinct both clinically and morphologically from the common adenoid cystic carcinoma of salivary gland origin.     

Vagal control of heart rate is modulated by extracellular potassium

Heart rate (HR) recovery from heavy exercise is associated with a shift in cardiac sympatho-vagal balance and a transient hypokalaemia. Since changes in extracellular potassium ([K+]0) affect membrane currents in the sino-atrial node, in particular the acetylcholine-activated potassium current (I(K,ACh)), the hyperpolarization-activated current (I(f)) and the L-type calcium current (I(Ca,L)), we investigated whether mimicking [K+]0 concentrations seen during and immediately after exercise could directly modulate the HR response to vagal nerve stimulation (VNS) in the isolated guinea-pig atria preparation pre-stimulated with noradrenaline (NA, 1 microM). Lowering [K+]0 from 4 to 3 mM significantly enhanced the HR response to VNS (5 Hz, 5 V, 30 s, deltaHR 84.5 +/- 14.1 bpm and 119.3 +/- 18.2 bpm, respectively). Increasing [K+]0 to 8 or 10 mM significantly decreased the drop in HR with VNS in comparison to the response to 3 mM K+ Tyrode (deltaHR 56.4 +/- 9.1 bpm and 52.1 +/- 8.7 bpm, respectively). These results could be simulated using the OXSOFT heart sino-atrial node computer model by activating I(K,ACh) during changes in [K+]0. However, changing [K+]0 in the model had no significant effect on the decrease in beating frequency brought about by decreasing I(f) or I(Ca,L). We conclude that the magnitude of the decrease in HR with VNS is enhanced in low [K +]0 and reduced in high [K+]0. The increased efficacy of cardiac vagal activation in low [K+]0 might therefore facilitate the drop in HR after heavy exercise where there is a transient hypokalaemia. Modelling suggests this result may be explained by the effects of changes in [K+]0 on the current-voltage relationship for I(K,ACh).     

Surgical management of subfoveal neovascularization in children.

OBJECTIVE: To report the authors' clinical experience with submacular surgery for subfoveal membranes in children and to evaluate the histopathologic findings of membranes in children with various etiologies of choroidal neovascularization. DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: Twelve eyes of 12 consecutive children with subfoveal choroidal neovascularization treated by vitrectomy and excision of the choroidal neovascular complex. INTERVENTION: Vitrectomy, excision of the choroidal neovascular complex, and air-fluid exchange. MAIN OUTCOME MEASURES: Visual acuity and recurrence of choroidal neovascular membrane. RESULTS: Preoperative visual acuities ranged from 20/60 to 20/800 (median, 20/300). Postoperative visual acuities ranged from 20/25 to 20/400 (median, 20/80) after an average follow-up of 20 months (range, 7-62 months). Ten of 12 eyes improved from immediate preoperative visual acuity, and four eyes developed recurrence of neovascular membranes over a mean follow-up of 18 months. Histopathologic examination of six excised membranes showed that the most common components of the membranes were retinal pigment epithelium, fibrocytes, vascular endothelium, and collagen. CONCLUSION: Selected eyes of children with subfoveal neovascular membranes and no evidence of membrane regression may benefit from submacular surgery. The histopathologic findings were similar to adult choroidal neovascularization not associated with age-related macular degeneration.