Inhibition of Escherichia coli heat-stable enterotoxin by indomethacin and chlorpromazine

Purified heat-stable enterotoxin (ST) from a procine strain of enterotoxigenic Escherichia coli activates quanylate cyclase in particulate fractions of rat intestinal tissue and induces fluid accumulation in suckling mice. These effects of ST were examined in the presence of either indomethacin or chlorpromazine. We also examined the effects of these two drugs on fluid accumulation in suckling mice induced by the 8-bromo analog of cyclic guanosine monophosphate. Either indomethacin or chlorpromazine reduced ST activation of guanylate cyclase. Both drugs also reduced intestinal fluid accumulation in suckling mice that resulted from submaximal doses of ST (both P < 0.001). However, there was no reduction in fluid secretion by either drug when a maximally effective dose of ST was used, suggesting that inhibition of fluid secretion by both drugs can be overcome by increasing the ST dose and that a threshold level of guanylate cyclase activity results in maximal secretory response. Both drugs also reduced basal guanylate cylase activity in rat intestinal tissue and fluid secreton in suckling mice. Chlorpromazine also reduced intestinal secretion mediated by 8-bromo cyclic guanosine monophosphate (P < 0.001). These findings indicate that chlorpromazine interferes with the effects of ST both before and after its activation of guanylate cyclase, whereas indomethacin interfers with ST only before its activation of guanylate cyclase.

Activation of intestinal guanylate cyclase by heat-stable enterotoxin of Escherichia coli: studies of tissue specificity, potential receptors, and intermediates

Heat-stable enterotoxin (ST) of Escherichia coli increased guanylate cyclase activity in homogenates of rat and rabbit intestinal mucosa and stimulated intestinal fluid secretion in suckling mice. The ST effect on guanylate cyclase was dose-dependent, occurred without a time lag, and was confined to the particulate fraction. ST activation of guanylate cyclase was tissue-specific; ST did not alter activity of soluble or particulate rat liver, lung, heart, kidney, or cerebral cortex enzyme. The ST activity on guanylate cyclase and secretion was methanol-soluble and alkali-labile, and its effects were not altered by phentolamine, propranolol, or atropine. Monosialoganglioside did not reduce ST-induced secretion. However, indomethacin and butylated hydroxyanisole decreased the ST effect on both guanylate cyclase and secretion. Fluid secretion with ST sppears to result from specific activation of particulate intestinal guanylate cyclase. While adrenergic and cholinergic events are probably not involved in this process, the effects of ST may be mediated through prostaglandin synthesis or oxidative mechnanisms.

Adrenocorticotropin inhibition of mineralocorticoid hormone production

1. Adrenocorticotropin (ACTH)-induced steroidogenesis, obtained by continuous administration of ACTH for 3 days, produces in man (a) sustained elevations of plasma deoxycorticosterone and cortisol concentrations, (b) transient elevations of plasma aldosterone and 18-hydroxycorticosterone concentrations that return to near-control values, and (c) brisk initial increases in plasma 18-hydroxydeoxycorticosterone and corticosterone concentrations that fall to 20-68% of peak values 30 h thereafter. 2. Dexamethasone (8 mg/day, orally) treatment for 2 days in man permits a greater postural increase in plasma aldosterone and 18-hydroxycortisone concentrations. A dampening effect of ACTH is suggested. 3. An ACTH-initiated inhibition of 11 beta- and 18-hydroxylation is proposed to be operative in regulation of mineralocorticoid hormones.

Transient traumatic "locked-in" syndrome

The first clinical case of transient traumatic locked-in syndrome is presented. The locked-in state lasted for 3 months. The patient's neurologic deficit and the abnormal auditory evoked responses pointed to a lesion involving the left pons and ventral midbrain. The locked-in syndrome caused by a traumatic damage of the brain stem structures can be transient and thus it may have a better prognosis than the locked-in syndrome secondary to the occlusion of the basilar artery.

Clinical significance of 99mtechnetium sulfur colloid accumulation in renal transplant patients

The accumulation of 99mtechnetium sulfur colloid (99mTcSC) was evaluated in 47 studies performed on 19 renal transplant patients by comparing its transplant activity to its bone marrow accumulation. There was a diagnosis of rejection of 21 of 22 studies (96.5%) in which marked transplant accumulation was noted. In 11 studies of patients with a clinical diagnosis of post-transplant acute tubular necrosis (ATN), the transplant activity varied from none to moderate. Rejection developed in 5 of 6 studies with minimal to moderate accumulation. Normally functioning renal transplant patients, or those with ATN and no superimposed rejection, do not show evidence of 99mTcSC accumulation.

Conversion of Scrap Tires by Pyrolysis in Molten Salts

Thermal decomposition in molten salts shows some promise as a method for recovering useful materials from scrap tires. Obviously, much technical development and engineering work needs to be done to evaluate that process. Applications of these techniques to other polymers is possible and is under study.

Hormonal stimulation of alpha-amylase synthesis in porcine pancreatic minces

Minces of porcine pancreas maintained a linear rate or protein synthesis for more than 4 h with similar kinetics in the presence of absence of hormones. alpha-Amylase protein, quantitated by using glycogen percipitation, SDS polyacrylamide gel analysis, and radioimmunoassay, was found to represent 6-7% of the total protein content of the minces. The addition of prostaglandin E1 (10-7M), or a pancreozymin preparation (3-10 Crick-Harper-Raper units/ml) to the incubation media produced within 60 min an increase in alpha-amylase protein above that stored in the tissue 10- to 20-fold greater than that observed in control minces. The addiction of cAMP analogs (10(-3)M) to the medium produced a more variable stimulation of alpha-amylase content. Quantitation of the incorporation of radiolabeled amino acid into alpha-amylase protein with simultaneous determination of the specific activity of the precursor pool suggested that these agents produced at least 3- to 5-fold stimulation of de novo alpha-amylase synthesis. This stimulation was not the result of decreased rates of alpha-amylase catabolism. The addition of actinomycin D (20 mug/ml), a concentration inhibiting more than 93% of new RNA synthesis, failed to alter the stimulation of alpha-amylase synthesis by these agents. Apparent hormonal stimulation of non-alpha-amylase protein synthesis was also observed.

Current-controlled phase retardation plate

A plate of fused quartz mounted in the jaws of a magnetic clamp serves as a current-controlled phase retardation plate. The current to the clamp controls the stress on the quartz plate, and hence the amount of stress-induced birefringence. The device described here can be used in a dc mode as a fixed phase retardation plate or in an ac mode as a polarization modulator at frequencies up to several hundred hertz. This device offers several advantages over other polarization modulators available.

Mercury Monitor for Ambient Air

An isotope-shift, Zeeman-effect atomic absorption spectrometer has been demonstrated to have sufficient sensitivity to continuously monitor the total mercury content of ambient air. At present, the minimum total mercury concentration detectable with this device is 0.2 microgram per cubic meter of air-one fifth of the proposed federal guideline. This is the first technique which responds to both mercury vapor and mercury in particulates available for continuous monitoring at this concentration.

Maturation of ribosomal RNA in stringent and relaxed bacteria

Experiments with relaxed and stringent strains of E. coli confirm that rRNA synthesis continues in both during amino acid starvation. rRNA species produced are exclusively in their precursor configurations and vulnerable to nuclease attack.