Virus-directed post-translational cleavage in Sindbus virus-infected cells.

The viral polypeptides synthesized in cells coinfected with group C and group D or E Sindbis virus mutants were studied. Cleavage of the ts2 protein occurs in cells coinfected with ts2 and ts20. Since the ts2 protein fails to chase in cells infected with ts2 alone, the activity effecting this cleavage must be, at least in part, virus specified.     

TLC Luminescence of gramine and related indole alkaloids in phalaris arundinacea

Luminescence characteristics of gramine, dimethyltryptamine and related indoles on Si gel TLC are described, chromatographic conditions are devised which enhance the luminescence, and a fluorometric TLC scanning procedure is developed for the quantitative determination of gramine in Phalaris arundinacea. 5-Methoxy-and 5-hydroxyindoles are readily distinguished from the indoles lacking a polar substituent at position 5.     

Comparison of two methods of altering blood pressures for assessing neonatal cerebral blood flow autoregulation

The cerebral blood flow of newborn lambs at reduced and elevated arterial blood pressures, induced by intravenous infusion of sodium nitroprusside and phenylephrine hydrochloride as well as blood withdrawal and reinfusion, were compared. Both blood withdrawal and sodium nitroprusside infusion reduced mean arterial pressure from 83 to 60 mmHg (1 mmHg = 133 Pa). Reinfusion of blood increased arterial pressure to 94 mmHg. Phenylephrine hydrochloride infusion increased arterial pressure to 102 mmHg. The cerebral blood flows at corresponding arterial pressures were similar (coefficient of correlation = 0.88, P less than 0.01). Cerebral blood flow before and after infusion of phenylephrine hydrochloride and sodium nitroprusside into the brain via the carotid artery did not change. The results indicate that blood-borne phenylephrine hydrochloride and sodium nitroprusside, in concentrations that would alter arterial blood pressure significantly from its resting level, do not change cerebral blood flow directly.     

Effects of aspirin and paracetamol on ATPases of human fetal brain: an in vitro study

In vitro effects of aspirin and paracetamol at the doses 200, 400, 600, 800 nmole/mg protein on ATPases activity were studied in the cerebrum and cerebellum of human fetus covering the age range from 10 weeks to 32 weeks of gestation. Both aspirin and paracetamol inhibit Na+K+ ATPase and Mg2+ ATPase in a dose dependent manner. The inhibition of Na+K+ ATPase and Mg2+ ATPase activity which may affect the release and uptake of biogenic amines in CNS, hinders the maturation of human fetal brain.     

Pyridine and other coal tar constituents as free radical-generating environmental neurotoxicants

Summary We have tested the hypothesis that chronic exposure to the principal constituents of the aqueous fraction of coal tar extracts can lead to the in vivo formation of substances which may produce neurological damage as the result of free radical generation and lipid peroxidation, these may be involved in the etiology of some neurological disorders. Artificial mixtures of the aqueous fraction of coal tar extracts were given in low concentrations to pigmented mice in their drinking water over a 3-month period. This resulted in significant increases in lipid peroxidation in the striatum, cerebellum and liver of the mice under test, the rank order being striatum > cerebellum > liver. These results are compatible with the possibility that coal tar emissions (as would be recovered or liberated in the burning, refining or beneficiation of coal) constitute a potential source of neurotoxicants with a predilection for damaging the nigrostriatal neuronal pathway. Our observations may thus have identified an important and hitherto unsuspected environmental source of neurotoxic chemicals, a possibility consistent with the proposed involvement of an environmental chemical factor in Parkinson's disease and perhaps in other neurological disorders.     

Morphological and biochemical effects of gentamicin and cyclosporin-a on urinary cell phospholipids and phospholipases in man

The morphology, lipid composition, and activity of sphingomyelinase (E.C. 3.1.4.12) and phospholipases A (E.C. 3.1.1.32) and C (E.C. 3.1.4.3) were studied in the urinary cells from four normal subjects, four patients receiving gentamicin (G), and four patients receiving cyclosporin-A (CsA). We report that abnormal urinary excretion of proximal tubular cells occurred in patients receiving G and CsA. Membrane-enclosed sudanophilic material and numerous vacuoles were found in the cytoplasm of the proximal tubular cells from both patients receiving G and those receiving CsA. Patients receiving G shed higher levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), and sphingomyelin (SM) in the order of 78%, 38%, and 30% relative to normal. In contrast, the excretions of phosphatidylinositol (PI) and PC were 50% and 30% lower, respectively, in patients receiving CsA as compared to control. Sphingomyelin levels, however, were moderately elevated in these patients' urinary renal tubular cells. The activity of acid sphingomyelinase was one half the normal level in the cells of patients receiving G and CsA. The most striking result was a tenfold decrease in the activity of neutral sphingomyelinase in patients receiving G. In contrast, the activity of neutral sphingomyelinase in patients receiving CsA was similar to control. Phospholipase A activity was decreased and increased 35% and 15%, respectively, in urinary proximal tubular cells from patients receiving G and CsA. We conclude that deficient neutral sphingomyelinase activity precedes phospholipid (PL) overloading and gross pathological changes in patients receiving gentamicin but not in patients receiving cyclosporin-A.     

Membrane carbohydrate characterization of Acanthamoeba astronyxis, A. castellanii and Naegleria fowleri by fluorescein-conjugated lectins

A comparative study of membrane carbohydrate characteristics of pathogenic and non-pathogenic trophozoites and cysts of free-living Acanthamoeba castellanii, Naegleria fowleri and A. astronyxis, respectively from sewage sludge in India was carried out by means of fluorescein-conjugated lectin binding using eight lectins. Two lectins, viz. Concanavalin A and Phytohaemagglutinin P, could bind all free-living amoebae at different concentrations. The most notable feature of the study is that peanut agglutinin (PNA) and wheatgerm agglutinin (WGA) can differentiate between the pathogenic A. castellanii and non-pathogenic A. astronyxis strain, respectively. However, Ulex agglutinin I (UEA I) was the only lectin positive to both pathogenic A. castellanii and N. fowleri. During in vitro conversion from trophozoites to cysts, A. castellanii and N. fowleri cysts gained WGA-specific saccharide whereas A. castellanii; A. astronyxis and N. fowleri lost or reduced Dolichos biflorus agglutinin, PNA; WGA and ConA, and UEA I-specific saccharides, respectively. Neuraminidase could not alter the fluorescein-lectin binding to WGA and PNA. These demonstrated that only two lectins can recognize the factors giving Acanthamoeba their pathogenic (PNA-specific) and non-pathogenic (WGA-specific) status. More interestingly, UEA I can only differentiate between pathogenic and non-pathogenic amoebae. It is also suggested that during stage conversion the surface of the organism exhibited replacement of saccharides.