The effect of PGI2 and theophylline on the response of platelets subjected to shear stress

A specially designed rotational viscometer was used to investigate the effects of the antiplatelet agent PGI2 in combination with theophylline on the response of human platelets subjected to shear stress. Samples of citrated platelet-rich plasma (PRP) were exposed to shear stress in the viscometer for a period of 5 min at 23 degrees C. The levels of stress studied ranged from 50 to 300 dynes/sq cm. Pretreatment of the platelets with 0.01 microM PGI2 and 500 microM theophylline before exposure to shear stress caused a large reduction in shear-induced platelet aggregation. However, it was also observed that the PGI2-- theophylline pretreatment concomitantly caused a large increase in shear-induced platelet lysis and serotonin release at stress levels equal to or greater than 150 dynes/sq cm. This observed increase in platelet fragility may have important implications for clinical applications of PGI2. The results are discussed and compared to those obtained in prior work in which platelets were pretreated with acetylsalicylic acid or with PGE1.     

Exogenous oxidants initiate hydrolysis of endothelial cell inositol phospholipids

Oxidants released from inflammatory cells contribute to the pathogenesis of acute inflammatory edema in many models. Chemically produced oxidants can reversibly alter the barrier properties of cultured endothelial and epithelial monolayers. This report examines the effects of nonlytic doses of H2O2 on endothelial cell lipids. H2O2 oxidized omega-6 fatty acids in the endothelial cells and initiated hydrolysis of endothelial cell phospholipids. When endothelial cells were exposed to peroxidized linoleic acid, it caused lysis of the cells at doses 1,000-fold lower than effective doses of H2O2. The phospholipid hydrolysis was directed primarily at the inositol phospholipids and consisted of both A and C type phospholipase activity. The phospholipase A hydrolysis resulted in increases in endothelial cell free fatty acids and lysophosphatidylinositol. The phospholipase C hydrolysis resulted in increases in diglycerides, phosphatidic acid, and inositol polyphosphate levels. The phospholipase C hydrolysis of phosphatidylinositol is known to activate protein kinase C in most cells. Stimulation of protein kinase C with phorbol- 12,13-dibutyrate increased albumin flux across endothelial monolayers and altered endothelial cell shape, similar to effects of oxidants. These data are consistent with the hypothesis that oxidant-initiated hydrolysis of endothelial cell inositol phospholipids contributes to oxidant-mediated reversible changes in endothelial monolayer barrier function.     

The response of gastric secretion and serum gastrin to an insulin infusion test in patients with duodenal ulcer

The intravenous infusion of insulin 0.04 U/kg-hr for 2-1/2 hours was performed in 26 patients with chronic duodenal ulcer. In 15 patients this infusion test was compared with the standard test of a single intravenous injection of insulin 0.2 U/kg. The mean lowest blood glucose level in the infusion group (25.1 mg/100 ml) was significantly higher than in the standard test (17.4 mg/100 ml), and the interval from injection to acid stimulation about twice as long (75versus 45 minutes). The peak acid output and mean rise in acidity were comparable in the two procedures. Serum gastrin responded reciprocally to insulin-induced hypoglycemia with a significant inverse correlation between blood glucose and gastrin. In 13 patients tested after vagotomy, there was no significant difference in the rise in acidities in the two groups, and the Hollander status was the same in all but one patient. The mean basal, peak, and absolute rise of serum gastrin in unoperated patients and patients with incomplete vagotomy were almost identical. In patients with complete vagotomy there was no significant rise in serum gastrin after insulin infusion. Unpleasant side effects as assessed by an independent observer were fewer and less severe in patients undergoing infusion tests than in the standard test. The insulin infusion test is recommended as a safer and more acceptable test than the standard insulin test since it avoids severe hypoglycemia and has milder side effects yet achieves comparable acidity and acid outputs. Measurements of serum gastrin after either insulin test provide no additional information helpful in the assessment of the completeness of vagotomy.     

Differentiating Acute Hepatitis B from the First Episode of Symptomatic Exacerbation of Chronic Hepatitis B

In countries with intermediate or high endemicity for chronic hepatitis B virus (HBV) infection, exacerbations of chronic hepatitis B (CHB) are common. We studied the clinical, biochemical, and virologic characteristics of patients first presenting clinically with features of acute icteric hepatitis B, to identify features that might differentiate between acute viral hepatitis B (AVHB) from first episode of exacerbation of chronic hepatitis (ECHB). We retrospectively analyzed 79 patients (mean age 35.4 ± 14 years; M:F = 60:19) who first presented clinically as AVHB, within 4 weeks of onset of symptoms. Patients who on follow-up cleared HBsAg and/or did not develop any clinical, radiologic, or histologic evidence of chronic liver disease (CLD) were categorized as AVHB (group 1). Patients who had persistence of HBsAg and developed clinical, biochemical, radiologic, or histologic evidence of chronic liver disease were categorized as ECHB (group 2). Forty-nine patients were in group 1 and 30 in group 2. The 2 groups were comparable with respect to prodrome, onset of jaundice, serum bilirubin, ALT, prothrombin time prolongation, serum albumin, and A/G ratio. Among group 1 patients, 78% had IgM anti-HBc positive in titers > 1:1000; in group 2, there were negative or positive in titers < 1:1000 in 70% patients (P < .001). Forty-seven of 49 (95.9%) patients in group 1 had HBV-DNA levels < 0.5 pg/mL, whereas 26 of 30 (86.73%) patients in group 2 had levels > 0.5 pg/mL (P ≤ .001). Quantitative HBV DNA and IgM anti-HBc titers at initial presentation can differentiate patients with a true episode of acute hepatitis B from patients with first episode of symptomatic exacerbation of chronic hepatitis B. Clinical and biochemical features do not help in differentiating the two.     

Analysis of T-cell receptor beta chain (T beta) gene rearrangements demonstrates the monoclonal nature of T-cell chronic lymphoproliferative disorders

We investigated the rearrangement patterns of the gene coding for the beta chain of the T cell receptor (T beta) in 11 patients with T-cell derived chronic lymphoproliferative disorders, including T-cell prolymphocytic leukemia (T-PLL) and T-cell chronic lymphocytic leukemia (T-CLL). We found that all five cases of T-PLL, and five of six cases of T-CLL, displayed T beta-gene rearrangements, clearly establishing their monoclonal nature. Clonality could not be determined in one case of T-CLL where the T beta gene was found unrearranged. Our results demonstrate that the majority of cases of both clinically aggressive T- PLL and clinically indolent T-CLL are monoclonal. These results suggest that the analysis of T beta gene rearrangements represents a valid tool for the differential diagnosis and clinical monitoring of T-cell derived chronic lymphoproliferative diseases.     

Erectile Impotence in Chronic Alcoholics

Erectile impotence is a common complaint in alcoholics, but its mechanism is unknown. We have studied nocturnal penile erection in 13 alcoholics who complained of impotence. Seven had normal erections and their impotence was therefore psychogenic. Six were found to have diminished or absent nocturnal erections. Plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were elevated in this latter group, with the exception of one patient who had only raised FSH. They also had more evidence of neurological damage than the other seven alcoholics, and two had evidence of damage to the parasympathetic nervous system. Investigation of erection during sleep in alcoholic patients with impotence may be useful in differentiating clinically between patients with psychogenic causes and patients with organic causes of impotence.     

Blood pressure response to the first dose of angiotensin-converting enzyme inhibitors in congestive heart failure

Angiotensin-converting enzyme (ACE) inhibitors improve survival in heart failure and delay progression to clinical heart failure in patients with left ventricular dysfunction after myocardial infarction. Increasing numbers of older patients are being considered for such treatment. However, there are reports of excessive and prolonged decreases in blood pressure (BP) after the first dose of some ACE inhibitors. We have studied the hemodynamics, pharmacokinetics, and neurohumoral responses to the first dose of oral captopril 6.25 mg, enalapril 2.5 mg, perindopril 2.0 mg, intravenous enalaprilat 1.5 mg, and perindoprilat 1.0 mg, compared with oral or intravenous placebo in 6 parallel groups of 12 elderly patients each with moderate-to-severe (New York Heart Association classes II-IV) heart failure. Oral dosing with active drugs led to different temporal responses. After captopril, there was an early short-lived decrease in BP. Enalapril led to a later long-lasting decrease, but perindopril was not different from placebo. Intravenous enalaprilat and intravenous perindoprilat each lowered BP to a similar extent. The doses of drugs used appeared to be comparable because plasma ACE inhibition was similar following perindopril or enalapril and also comparing perindoprilat and enalaprilat. These studies indicate that oral ACE inhibitors have different profiles of acute BP changes after the first dose. The explanation is not clear, but could include physicochemical differences in the interaction between prodrug ester and diacid metabolites leading to differences in tissue distribution and local enzyme inhibition.     

Propulsion and retropulsion of normal colonic contents

Conclusion In conclusion, it may be said that the propulsion of colonic contents can be effected either by systolic or progressive contractions of the bowel wall. The two modes of transportation can usually be identified in time-lapse cinefluorograms even at 1 frame/min from the regularity of the movement of opaque contents. Evidence is presented of a form of progressive propulsion which has all the characteristics of peristalsis that are recognizable by this method of study, and yet is capable of travelling adorally up the colon. It is not possible to say what the relationship of this kind of movement is to the strictly aboral mass peristalsis with which workers in this field are so much more familiar.Supported by grants from the Medical Research Council and the Nuffield Committee.