Transport studies and enzyme assays in mice infected with human Giardia lamblia

It is well established that Giardia infection causes malabsorption. However, the precise mechanism of such a malabsorptipn is not known. To investigate this, transport studies, using the tissue accumulation technique, were carried out in mice infected with G. lamblia obtained from human stools. There was a significant fall in the transport of D-glucose, L-alanine and glycine in the infected animals compared with the controls. Kinetics of the D-glucose and glycine transport system were examined by measuring the tissue uptake in the presence of different concentrations of the substrate. For glucose, the affinity constant (Km) for the transport site was the same (4·37mM) in normal and infected animals but the maximal transport rate (V max) was considerably reduced in infected animals (158·7 μ moles/hr/g tissue) compared with (357·1 μ moles/hr/g tissue) in controls. Results with glycine were similar; the Km was similar in control and infected animals (5·7 mM) whereas the V max was reduced in infected animals (27·02 μ moles/hr/g tissue) compared with controls (45·5 μ moles/hr/g tissue).Analysis of the intestinal enzymes showed a significant decrease in the levels of brush border sucrase, lactase and alkaline phosphatase in infected animals; the cellular enzymes, LDH, GOT and GPT remained unaffected.The observed aberrations in the transport functions and brush border enzymes suggest that G. lamblia causes malabsorption by damaging the epithelial membrane of the enterocyte.     

Defective sarcoplasmic reticular calcium transport in diabetic cardiomyopathy

The effects of insulin and thyroid hormone treatments on cardiac sarcoplasmic reticular function were investigated in chronic streptozotocin-induced diabetes in rats. ATP-dependent Ca2+ transport and Ca2+-stimulated ATPase activities were depressed significantly in microsomal samples from diabetic rats in comparison with control (P less than 0.05). This defect was seen at various times of incubation (1-20 min) and different concentrations of free Ca2+ (10(-7) to 10(-5) M Ca2+) and was accompanied by changes in the protein composition and phospholipid contents of the microsomal fraction. The defect in calcium transport in microsomal vesicles was not evident until 28 days after streptozotocin (65 mg/kg iv) injection, whereas increases in plasma glucose levels due to insulin-deficiency occurred within 3 days. All changes in function and composition of the sarcoplasmic reticulum were reversed by insulin administration to the diabetic rats. Although the plasma level of thyroid hormone was decreased in the diabetic rat, thyroid hormone treatment did not restore microsomal calcium transport in the diabetic animals. The results of this study provide some evidence that the depression in cardiac sarcoplasmic reticular calcium accumulation during diabetes is a consequence of insulin deficiency and associated chronic metabolic changes but the hypothyroid condition that accompanies experimental diabetes does not appear to play any role in this defect.     

Oral Immunization of Mice with Killed Salmonella typhimurium Vaccine

A study was undertaken to assess the efficacy of oral, parenteral, and intraperitoneal immunization methods of administering killed Salmonella typhimurium vaccine to mice and to evaluate the effectiveness of single and multiple doses of the vaccine containing varied numbers of the killed bacteria. A further objective of this study was to evaluate the effect of adding substances to the vaccine to which have been ascribed "adjuvant" properties. The protection was estimated by isolation of bacteria from the spleen and feces after oral challenge of the mice with live S. typhimurium. The results showed that one or more doses of 10(10) organisms given orally led to significant protection. This rate of protection increased proportionately with the number of doses up to 10 doses, which offered 100% protection. Streptomycin, when added to multiple doses of 10(9) or more organisms given orally, increased the degree of protection, but beryllium sulfate and pertussis vaccine did not. Although multiple doses afforded similar systemic protection by all three routes of immunization, oral immunization yielded significantly greater local protection than that observed after subcutaneous or intraperitoneal immunization.     

A study of morbidity pattern among prostitutes attending a municipal clinic in Pune

The findings of the present study revealed that out of 200 prostitutes attending a clinic for various ailments, 81.50% were suffering from sexually transmitted diseases (STD) thus posing a potential risk of transmitting these diseases to their clients. Syphilis was found to be the commonest STD afflicting 36.80% of the respondents, the next common being the chancroid (31.28%); 5.52% of the respondents were found to be suffering from concomitant venereal infections. The other important communicable diseases with which some respondents were found to be afflicted, included--tinea infection (3 cases), scabies (2 cases), leprosy (2 cases), pulmonary tuberculosis (4 cases) and upper respiratory tract infection [3 cases). Thus, the prostitutes remain an undisputed potential source of infection not only of STDs but also several other communicable diseases. Therefore, their continuous surveillance, early diagnosis, appropriate treatment and subsequent follow-up should be meticulously carried out. On the other hand the public, particularly the sexually promiscuous individuals must be imparted vigorous health education to avoid exposure to this source.     

Alterations of phosphatidylethanolamine N-methylation in rat heart by quinidine

To elucidate the molecular mechanism underlying the adverse depression of myocardial contractility observed during antiarrhythmic therapy of quinidine, we investigated its action on the phosphatidylethanolamine N-methyltransferase (EC 2.1.1.17) activities of cardiac subcellular membranes. Rat heart sarcolemma, mitochondria, and microsomes (sarcoplasmic reticular fragments) were isolated, and the three catalytic sites for N-methylation activities were examined with 0.055 (site I), 10 (site II), and 150 (site III) microM concentrations of S-adenosyl-L-[methyl-3H]methionine as a methyl donor. Total methyl group incorporation into sarcolemmal phosphatidylethanolamine was depressed by 10(-6)-10(-3) M quinidine at sites II and III. The activity of site I was stimulated at low (10(-9) M) concentrations and inhibited at high concentrations of the drug. A similar behaviour was observed with procainamide, although the inhibitory effect was less pronounced and was not additive with quinidine. Quinidine-induced inhibition was associated with a depression of Vmax, while the apparent affinity for S-adenosyl-L-methionine was unaltered. Analysis of individual methylated phospholipids confirmed inhibition by quinidine at sites II and III in sarcolemma. Microsomal phosphatidylethanolamine N-methylation was affected by 10(-6) M quinidine only at site II, whereas no changes were noted in mitochondria. Quinidine also inhibited both the positive inotropic response and concomitant increase in tissue N-methylated phospholipids observed upon L-methionine perfusion of rat heart. These results suggest that quinidine alters the intramembranal level of N-methylated phospholipids, and this may serve as a biochemical mechanism contributing to its negative inotropic effect.     

Oxidative metabolic status of blood monocytes and alveolar macrophages in the spectrum of human pulmonary tuberculosis.

The oxidative metabolic status of blood monocytes (BM) and alveolar macrophages (AM) in patients with active pulmonary tuberculosis (TB) (n = 40) and in successfully treated patients (n = 40) was assessed and compared with that of healthy control subjects (n = 40). Oxygen free radical (OFR) generation, measured by chemiluminescence (CL) and cytochrome c reduction assay and confirmed by using scavengers of different OFR, was suppressed in AM of the pulmonary TB group compared with healthy controls, whereas it was enhanced in BM. Successfully treated patients showed partial recovery of CL and cytochrome c reduction in AM. There was no significant change in BM of patients after having been treated. The overall capacity to generate OFR was markedly suppressed upon in vitro stimulation with latex in both BM and AM of TB patients. The observed suppressed oxidative metabolic activity in BM and AM was further elucidated by studying the molecular mechanism of respiratory burst. The activities of NADPH oxidase and enzymes of the hexose monophosphate (HMP) shunt were significantly (p less than 0.05) decreased in BM and AM of pulmonary TB patients compared with healthy controls. Patients who had been treated showed marked recovery of NADPH oxidase and HMP shunt activity. The present study suggests that tubercle bacilli escape the microbicidal action of macrophages as a result of suppressed OFR generation caused by decreased activity of HMP shunt, leading to decreased levels of NADPH, thereby preventing NADPH oxidase from working at its full capacity.     

Monoamine oxidase inhibition by the tremorogenic drug–-LON 954

N-Carbamovl−2−(2,6−dichlorophenyl)acetamidine HCl (LON 954), a tremorogenic drug, inhibited MAO activity in various tissue preparations in a reversible, competitive manner showing some degree of selectivity towards type-B MAO.     

Release of prostaglandin E from the isolated urinary bladder of the guinea-pig.

1 Release of prostaglandin E (PGE) from guinea-pig urinary bladder in vitro has been demonstrated both in the resting state and during electrical stimulation. 2 The electrically evoked release of PGE was significantly higher than the resting release and was frequency-dependent. 3 The released substance was characterized as PGE pharmacologically by (a) blockade of its response by SC-19220 on guinea-pig ileum, (b) reduction of the amount of the released substance by indomethacin and (c) the inhibitory effect of the released substance on adrenergic neurotransmission in guinea-pig vas deferens. 4 The prostaglandin seemed to originate from the muscle since tetrodotoxin treatment did not abolish the release during direct muscle stimulation; however, concomitant release from neuronal tissue could not be excluded in the present experiments. 5 Indomethacin failed to inhibit the mechanical responses of the bladder to transmural stimulation. 6 The present experiments suggest that PGE is not involved in mediating the non-cholinergic non-adrenergic neurotransmission in the guinea-pig urinary bladder.