Organisation and association of kappa-carrageenan helices under different salt conditions

Mixtures of the added salts NaI and CsI can be used to gradually 'tune' the propensity of kappa-carrageenan (KC) helices to aggregate in solution. We show that this method can be used to resolve the molecular events by which helix formation, under certain conditions, leads to gelation. We also present an overview of the various states of aggregation and organisation that appear for helical KC (non-degraded or ultrasonically degraded) when the NaI/CsI ratio and the concentration of KC are varied. A transition to rigid, superhelical rods is found above a well-defined fraction of cesium. This transition is reflected in a range of experimental measurements, such as cryo-transmission electron microscopy, optical rotation, viscometry and small deformation oscillatory measurements. The superhelical-rod state also seems essential for the association of KC with locust bean gum, and locust bean gum is found to stabilise this state. Novel states of KC alone have been found at cesium contents below the transition threshold. Non-degraded KC forms weak gels at sufficiently high concentrations (> ca. 1%). In contrast, ultrasonically degraded KC forms a chiral nematic liquid crystalline phase at sufficiently high concentrations (> ca. 5%) under these salt conditions.     

Safety, tolerance, and pharmacokinetics of a small unilamellar liposomal formulation of amphotericin B (AmBisome) in neutropenic patients

The safety, tolerance, and pharmacokinetics of a small unilamellar liposomal formulation of amphotericin B (AmBisome) administered for empirical antifungal therapy were evaluated for 36 persistently febrile neutropenic adults receiving cancer chemotherapy and bone marrow transplantation. The protocol was an open-label, sequential-dose-escalation, multidose pharmacokinetic study which enrolled a total of 8 to 12 patients in each of the four dosage cohorts. Each cohort received daily doses of either 1.0, 2.5, 5.0, or 7.5 mg of amphotericin B in the form of AmBisome/kg of body weight. The study population consisted of patients between the ages of 13 and 80 years with neutropenia (absolute neutrophil count, <500/mm3) who were eligible to receive empirical antifungal therapy. Patients were monitored for safety and tolerance by frequent laboratory examinations and the monitoring of infusion-related reactions. Efficacy was assessed by monitoring for the development of invasive fungal infection. The pharmacokinetic parameters of AmBisome were measured as those of amphotericin B by high-performance liquid chromatography. Noncompartmental methods were used to calculate pharmacokinetic parameters. AmBisome administered as a 1-h infusion in this population was well tolerated and was seldom associated with infusion-related toxicity. Infusion-related side effects occurred in 15 (5%) of all 331 infusions, and only two patients (5%) required premedication. Serum creatinine, potassium, and magnesium levels were not significantly changed from baseline in any of the dosage cohorts, and there was no net increase in serum transaminase levels. AmBisome followed a nonlinear dosage relationship that was consistent with reticuloendothelial uptake and redistribution. There were no breakthrough fungal infections during empirical therapy with AmBisome. AmBisome administered to febrile neutropenic patients in this study was well tolerated, was seldom associated with infusion-related toxicity, was characterized by nonlinear saturation kinetics, and was effective in preventing breakthrough fungal infections.     

在VB平台上开发的太阳能喷射制冷实验台测控系统

本文主要介绍了在VB6.0平台上开发的太阳能喷射制冷实验台的数据采集、监控软件,通过VB的强大功能,本软件将实验台的数据采集、控制和仿真计算与一身,为实验和理论研究提供了极大便利.     

Ranitidine controls nocturnal gastric acid breakthrough on omeprazole: a controlled study in normal subjects

BACKGROUND & AIMS: Proton pump inhibitors administered twice daily do not provide complete nocturnal acid suppression. Acid breakthrough, or decrease in intragastric pH to <4 for an hour or longer, occurs in three quarters of normal subjects and patients at night. We compared the effect of a third dose of omeprazole at bedtime with that of a dose of ranitidine at bedtime on residual nocturnal acid secretion in patients receiving omeprazole twice daily. METHODS: Twelve volunteers underwent overnight intragastric pH monitoring after 7 days of treatment with omeprazole, 20 mg twice daily, followed by different treatment supplements at bedtime: placebo; additional omeprazole, 20 mg; ranitidine, 150 mg; and ranitidine, 300 mg. RESULTS: Additional omeprazole at bedtime reduced the percentage of time with intragastric pH of <4 from 48% to 31% (P < 0.005) compared with omeprazole twice daily with placebo at bedtime. Ranitidine at bedtime reduced this parameter more, 5% with 150 mg and 6% with 300 mg (P <0.01 vs. omeprazole twice daily plus bedtime). Results for percentage of time with intragastric pH <3 were similar. Eleven subjects had acid breakthrough with placebo at bedtime; 7 with omeprazole at bedtime (P = NS); 4 with ranitidine, 150 mg at bedtime; and 3 with ranitidine, 300 mg at bedtime (P < 0. 05, ranitidine vs. placebo). CONCLUSIONS: Bedtime ranitidine is more effective than bedtime omeprazole on residual nocturnal acid secretion in patients receiving omeprazole twice daily. This finding suggests that fasting breakthrough nocturnal acid secretion in patients receiving omeprazole twice daily is most likely histamine related.     

Proton nuclear magnetic resonance studies on dideoxyribonucleoside methylphosphonates

A series of dideoxyribonucleoside methylphosphonates, d-ApA, d-ApT, d-TpA, and TpT, were synthesized chemically and the diastereoisomers of each dimer were separated [Miller, P. S., Yano, J., Yano, E., Carroll, C., Jayaraman, K., & Ts'o, P. O. P. (1979) Biochemistry 18, 5134]. The 1H NMR spectra of these compounds are similar to those of their parent diester compounds. Specifically, the assignments of the 1H resonances of the two diastereoisomers of d-ApA (designated as 1 and 2) were reaffirmed by comparing with the unmodified, parent d-ApA. The absolute configuration of the phosphonate methyl group of the two isomers (d-ApA)1 and (d-ApA)2 was determined by the NOE technique. The 1H NMR spectra of the diastereoisomers of d-ApA, as well as the corresponding monomer components dAp and CH3pdA, and TpT were analyzed by spectrum simulation techniques. Thus, all the coupling constants and chemical shifts of the proton resonances of the deoxyribofuranose ring and the phosphonate methyl group could be precisely determined. These data provide the information for an analysis of the sugar puckering and backbone conformations of these novel nonionic nucleic acid analogues. It was found that the conformations of the sugar-phosphate backbones of each isomer are similar to each other and are similar to the conformations of the parent dinucleoside monophosphates. The average adenine stacking conformations of (d-ApA)1 and (d-ApA)2 were described in numerical coordinates derived from a computer analysis which included both ring-current magnetic anisotropy and atomic diamagnetic anisotropy effects. The two computer-derived conformational models are similar to those derived from the graphic approximation based only on the ring-current effects. For each pair of dimer analogues, the base stacking mode of isomer 1 is similar to that of its parent diester while the extent of base overlap in isomer 2 is less than that in isomer 1. The results of the conformational analysis based on NMR data are consistent with the results obtained from ultraviolet and circular dichroism measurements on these dimers.     

Adenoviral-mediated interferon-gamma gene therapy augments pulmonary host defense of ethanol-treated rats

A case of anuric acute renal failure due to bilateral renal artery obstruction in a 42 year-old man is presented. The obstruction was caused by bilateral thrombosis secondary to arteritis. Autopsy showed granulomatous and necrotizing vasculitis in both main renal arteries. Scarring and also necrotizing vasculitis were found from interlobular to arcuate renal arteries. The present case indicates that vasculitis should be considered when there is renal artery obstruction in young patients.     

Amino acid incorporation into liver and tumor proteins in patients with hepatic neoplasms-effects of liver dearterialization

The effects of liver dearterialization on the rate of amino acid incorporation into liver and tumor proteins were studied with an in vitro method in seven patients with liver metastases. Before liver dearterialization the incorporation rate was 0.074 +/- 0.020 nmol leucine x mg prot-1 x h-1 in liver tissue and 0.234 +/- 0.049 nmol leucine x mg prot-1 x h-1 in tumor tissue. After dearterialization for 1 h the incorporation rate was reduced to about half of the initial values in both liver and tumor tissue. The vascularity of the tumors was evaluated from preoperative hepatic angiograms. The reduction of the incorporation rate was more pronounced in highly vascularized tumors than in poorly vascularized tumors and liver tissue. The clinical implications of a more pronounced metabolic effect of the dearterialization in high vascularized tumors are discussed.