Enzyme-linked immunosorbent assay for products of the 60-megadalton plasmid of Escherichia coli serotype O157:H7

Eighty strains of pathogenic Escherichia coli, representing each of the major diarrheal disease-causing groups, were examined by direct enzyme-linked immunosorbent assay (ELISA) for the presence of proteins associated with a 60-MDa plasmid from E. coli serotype O157:H7. Antiserum specific for plasmid-encoded proteins was prepared by immunizing a rabbit with a wild-type E. coli O157:H7 strain (strain 7785) and absorbing the serum with a plasmid-cured derivative (strain 2-45). Use of this antiserum in Western immunoblot analysis detected two proteins of 82 and 92 kDa in strain 7785 but not in strain 2-45. All 16 wild-type E. coli O157:H7 strains and all 10 Shiga-like toxin (SLT)-producing E. coli strains of serotypes other than O157 were ELISA positive. Thirteen of 14 enterotoxigenic and all of 24 enteroinvasive E. coli strains were ELISA negative, as were all of 16 E. coli strains isolated from healthy persons. Of 16 traditional enteropathogenic E. coli (EPEC) serotypes, 10 were ELISA positive, including 10 of 12 strains carrying the EPEC adherence factor gene. Absorption of the serum with an EPEC adherence factor-positive EPEC eliminated EPEC reactivity. This study demonstrates that two plasmid-mediated proteins are common to E. coli O157:H7 strains and to SLT-producing strains of other serotypes. Detection of these proteins by ELISA provides a sensitive and specific screening test for identifying SLT-producing E. coli of both O157 and non-O157 serotypes. Identification of the cross-reactive proteins found in EPEC could provide the basis for a single assay to detect both EPEC and SLT-producing E. coli.

CCK-8, CCK-4 and gastrin-induced contractions in guinea pig ileum: evidence for differential release of acetylcholine and substance P by CCK-A and CCK-B receptors

The cholecystokinin (CCK) receptor involved in contraction of guinea pig ileal longitudinal muscle to cholecystokinin is poorly understood; some studies have suggested that contraction was mediated via a CCK-A receptor whereas other studies have implicated CCK-B receptors in ileal contraction to CCK. To clarify this, we compared the effects of CCK-8 sulfate, CCK-4 and gastrin in radioligand binding studies and longitudinal ileal contractility in vitro. Contraction to all three peptides was abolished by tetrodotoxin (3 x 10(-7)M), confirming the neuronal nature of the CCK receptors mediating contraction to all three peptides. Maximal CCK-8S contractions were inhibited by 80% in the presence of atropine (10(-6)M), and entirely by the combination of atropine and a substance P receptor antagonist (3 x 10(-5)M). CCK-4 and gastrin-induced contractions were unaffected by substance P receptor blockade, but were abolished by atropine. Two selective CCK-A and CCK-B receptor antagonists, L-364,718 and L-365,260, respectively, were used to probe further the receptors involved in ileal contraction to this peptide family. Radioligand binding studies in mouse brain, rat pancreas and guinea pig stomach confirmed the selectivity of these antagonists. The CCK-A selective antagonist, L-364,718, potently inhibited ileal contractions to CCK-8S (-log KB = 9.35) with 10-fold lower affinity at receptors mediating contraction to CCK-4 (-log KB = 8.25). In contrast, the CCK-B receptor antagonist, L-365,260, did not affect contraction to CCK-8S (-log KB less than 7) but potently inhibited contraction to CCK-4 (-log KB = 9.24).(ABSTRACT TRUNCATED AT 250 WORDS)

Hypotensive properties of the protein kinase inhibitor, staurosporine, in normotensive and spontaneously hypertensive rats

The protein kinase inhibitor, staurosporine, was examined for hemodynamic actions in conscious rats and for its effects on isolated vascular smooth muscle. In conscious normotensive rats, staurosporine, 0.1 to 1.0 mg/kg intravenous, produced a dose-related decrease in blood pressure. Doses of 0.1 and 0.5 mg/kg produced reflex tachycardia, while heart rate decreased following 1.0 mg/kg. Higher doses of staurosporine (5 and 10 mg/kg), although not significantly altering heart rate, caused a precipitous drop in blood pressure and all rats died within 48 hours of treatment. Spontaneously hypertensive rats were significantly more sensitive than normotensive rats to the blood pressure lowering effects of staurosporine. The depressor activity of staurosporine was also observed in cord-stimulated pithed rats indicating that hypotension is a peripherally- rather than centrally-mediated effect of staurosporine. In ring preparations of rat thoracic aorta, staurosporine (3 nM to 0.1 mM) produced a concentration-dependent inhibition of serotonin-induced contraction, consistent with its ability to lower blood pressure by an effect at a peripheral vascular site. These results provide the first documentation of the potent cardiovascular activity of staurosporine in the conscious rat and support the contention that protein kinases, in particular protein kinase C, may be important in the regulation of vascular tone.

Choice and conflict about census data: adjusting the American census count

In this paper "reasons for inevitable defects in the census count are listed in the first section; the second section reports efforts by the U.S. Census Bureau to identify sources of error in census coverage, and make estimates of the size of the errors.... The paper describes the conflict between statistical practices, laws and public policy about census adjustment in the United States, and concludes by considering the extent to which causes [of error] in America are likely to be found in other countries."

Synthesis and biochemical evaluation of tritium-labeled 1-methyl-N-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-1H-indazole-3-carboxa mide, a useful radioligand for 5HT3 receptors

The advent of potent, highly selective 5HT3 receptor antagonists has stimulated considerable interest in 5HT3 receptor mediated physiology and pharmacology. To permit detailed biochemical studies regarding interaction of the indazole class of serotonin (5HT) antagonists with 5HT3 receptors in multiple tissues, we synthesized 1-methyl-N-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-1H-indazole- 3-carboxamide (LY278584, compound 9) in high specific activity, tritium-labeled form. This radioligand was selected as a synthetic target because of its potency as a 5HT3-receptor antagonist, its selectivity for this receptor viz a viz other 5HT-receptor subtypes, and the ability to readily incorporate three tritia via the indazole N-CH3 substituent. Alkylation of N-(8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-1H-indazole-3-carboxamide (8) with sodium hydride and tritium-labeled iodomethane, followed by HPLC purification, resulted in [3H]-9 with a radiochemical purity of 99% and a specific activity of 80.5 Ci/mmol. This radioligand bound with high affinity to a single class of saturable recognition sites in membranes isolated from cerebral cortex of rat brain. The Kd was 0.69 nM and the Bmax was 16.9 fmol/mg of protein. The specific binding was excellent, and accounted for 83-93% of total binding at concentrations of 2 nM or less. The potencies of known 5HT3-receptor antagonists as inhibitors of [3H]-9 binding correlated well with their pharmacological receptor affinities as antagonists of 5HT-induced decreases in heart rate and contraction of guinea pig ileum, suggesting the central recognition site for this radioligand may be extremely similar to or identical with peripheral 5HT3 receptors.

Experimental cardiac tamponade: correlation of pressure, flow velocity, and echocardiographic changes

Seven episodes of experimental cardiac tamponade were induced in five anesthetized closed-chest dogs. Simultaneous pericardial and intracavitary pressures were synchronized with superior vena caval and transvalvular pulsed-Doppler flow tracings. The earliest indication of tamponade was the development of a negative transmural right atrial pressure that occurred during early ventricular diastole and was associated with echocardiographic evidence of right atrial collapse. This was also associated with reversal of diastolic flow in the superior vena cava and with diminished early diastolic flow velocity across the tricuspid as well as the mitral valve. During more advanced cardiac tamponade, the transmural right atrial pressure became negative during both early and late ventricular diastole as well as during isovolumic ventricular systole. This was associated with a disappearance of early diastolic ventricular filling and right ventricular diastolic collapse as observed on two-dimensional echocardiography. In hypotensive cardiac tamponade (cardiac output diminished by 70%), the decreased transmural right atrial pressure that developed during ventricular systole was accompanied by diminished antegrade flow in the superior vena cava. In advanced and hypotensive tamponade, ventricular filling occurred mainly during atrial contraction.

Bradykinin-induced contractions of canine prostate and bladder: effect of angiotensin-converting enzyme inhibition

Alpha-adrenergic, cholinergic, and serotonergic receptor-mediated contractile responses have been well characterized in the genitourinary tissues of several mammalian species. The present study characterizes the in vitro contractile responsiveness of canine bladder and prostate to the peptides, bradykinin, angiotensin I, and angiotensin II. All preparations contracted to 0.15 M KCl. Bradykinin elicited contractile responses in both prostate (10(-10) to 10(-7) M) and bladder (10(-10) to 10(-6) M). In both tissues, angiotensin II produced minimal responses and angiotensin I failed to elicit contractions. The potent angiotensin converting enzyme (ACE) inhibitor, enalaprilic acid [MK-422] (10(-6) M) increased the contractile response to the prostate to bradykinin two-fold while having no effect on bradykinin-induced contractions in the bladder. Enalaprilic acid did not affect the contractile responses of the two tissues to angiotensin I or angiotensin II. The canine urogenital tissue contractile responses to bradykinin, angiotensin I, and angiotensin II may have relevance to human physiology. Previous studies have demonstrated that human prostatic tissue, specifically benign prostatic hyperplasia (BPH), has the highest concentration of ACE activity of tissues evaluated. Bradykinin is a potent peptidergic contractile agent in canine bladder and prostate. The activity of enalaprilic acid to amplify the bradykinin-induced contractions in the canine prostate is consistent with high levels of ACE in the tissue. These data confirm the sensitivity of the canine prostate to bradykinin and report for the first time, the ability of bradykinin to induce contractions in the prostate. These studies support the possibility that bradykinin may be involved in mediating micturition under normal and pathological states such as infravesical obstruction secondary to BPH. Furthermore, the results from these investigations in canine urogenital tissues, if applicable to humans, suggest that urinary function be closely monitored in patients receiving ACE inhibitor therapy.

Congenital tricuspid valve stenosis with atrial septal defect and left anterior fascicular block

Congenital tricuspid valve stenosis in the absence of other valvular abnormalities is rare. In this report we describe a patient with congenital tricuspid valve stenosis, ostium secundum atrial septal defect, and electrocardiographic left anterior fascicular block, who presented with paradoxical emboli. This case, as well as previous case reports, suggests that congenital tricuspid stenosis with ostium secundum atrial septal defect is associated with left anterior fascicular block.

Pharmacological and molecular evidence that the contractile response to serotonin in rat stomach fundus is not mediated by activation of the 5-hydroxytryptamine1C receptor

The receptor mediating contraction in response to serotonin in the rat stomach fundus has not been characterized in light of the currently acceptable serotonergic receptor classification scheme. Several biochemical and pharmacological approaches to a characterization of this receptor have demonstrated nonidentity with the 5-hydroxytryptamine2 (5HT2), 5HT3, 5HT1A, and 5HT1B receptors, as defined by radiolabeled ligand binding studies in brain cortical membranes. Although there have been reports suggesting that the receptor in the rat stomach fundus may be analogous to the 5HT1C receptor, other pharmacological and biochemical studies have not been consistent with this idea. The present study utilized high affinity ligands for the 5HT1C receptor and the recently derived 5HT1C receptor cDNA clone to provide a more definitive approach to the examination of the relationship between the 5HT1C receptor and the serotonergic contractile receptor in the rat stomach fundus. Using three ligands with high affinity at the 5HT1C receptor, LY53857, ritanserin, and SCH23390, the contractile response to serotonin was inhibited by all three ligands. However, inhibition did not appear competitive nor was the inhibitory potency of these ligands consistent with their affinity at 5HT1C binding sites in brain cortical membranes. We further showed that SCH23390, unlike LY53857 and ritanserin, was also a partial agonist, producing a maximal contraction that was approximately 50% of the maximal response to serotonin in the rat stomach fundus. Thus, the use of these ligands did not support the contention that the receptor mediating serotonin-induced contractions in the rat stomach is identical to the 5HT1C receptor. In more definitive studies using a 5HT1C receptor cDNA probe, we were unable to detect hybridization of the probe with any mRNA species from the rat stomach fundus, whereas the 5HT1C receptor cDNA probe did hybridize to the 5HT1C receptor mRNA in rat brain. Because the cathepsin-D cDNA probe hybridized equally in rat brain and stomach fundus, ensuring the integrity of the RNA preparation from both tissues, the absence of measurable quantities of the 5HT1C receptor mRNA in the rat stomach was probe specific and not an artifact. Furthermore, primers specific for the rat 5HT1C receptor sequence did not detect significant levels of receptor mRNA in rat fundus, although the target sequence was amplified a minimum of 10(5)-fold in a polymerase chain reaction. These studies do not support the contention that the receptor mediating contractile responses to serotonin in the rat stomach fundus is identical to the 5HT1C receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

LY277359 maleate: a potent and selective 5-HT3 receptor antagonist without gastroprokinetic activity

Several 5-hydroxytryptamine (5-HT3) receptor antagonists have been described. In addition to 5-HT3 receptor antagonist activity, many of these agents also possess gastroprokinetic activity. In the present report, we identify compound LY277359 maleate as a potent, p.o. active, highly selective 5-HT3 receptor antagonist lacking gastroprokinetic effects. LY277359 maleate was a potent and selective antagonist of 2-methyl 5-HT-induced contraction in the guinea pig ileum (KB = 1.6 nM), a response mediated by activation of 5-HT3 receptors. Given both i.v. (0.0003, 0.001 and 0.003 mg/kg) and p.o. (0.01 and 0.03 mg/kg), LY277359 maleate inhibited the bradycardic response to i.v. administered 5-HT in urethane-anesthetized rats. The duration of antagonism of 5-HT-induced bradycardia persisted beyond 6 hr after p.o. administration of LY277359 maleate (0.03 mg/kg p.o.). In contrast to its potent 5-HT3 receptor antagonist activity, LY277359 maleate, in doses up to 1 mg/kg p.o., did not affect gastric emptying in rats, suggesting minimal, if any, gastroprokinetic activity of LY277359 maleate. This is in contrast to another 5-HT3 receptor antagonist, zacopride, which did produce a marked increase in gastric emptying in rats at doses of 0.1 mg/kg p.o. and higher. LY277359 maleate (0.03 and 0.1 mg/kg i.v. and 0.07, 0.1, 0.3 and 1.0 mg/kg p.o.) did have effects consistent with other 5-HT3 antagonists, to inhibit cisplatin-evoked emesis in dogs.(ABSTRACT TRUNCATED AT 250 WORDS)