Radioimmunoassay of measles virus antibodies in SSPE

A sensitive radioimmunological assay (RIA) was introduced for detection of measles virus IgG and IgM antibodies. The hyperimmune response to measles virus could be demonstrated more precisely by RIA than by haemagglutination inhibition (HI). The ratio between RIA and HI antibody titres was decidedly higher in sera and cerebrospinal fluids (CSF) of patients with subacute sclerosing panencephalitis (SSPE) than in those of other groups tested.     

The FAD-containing monooxygenase-catalyzed N-oxidation and demethylation of trimethylamine in rat liver microsomes

Trimethylaminuria (TMAuria), the excessive urinary excretion of the odorous trimethylamine (TMA), accompanies elimination of TMA in sweat and corresponding "fish-odor" syndrome. TMA was oxidized in vitro in rat liver microsomes from male Sprague-Dawley rats to TMA N-oxide and N-demethylated to dimethylamine (DMA). Both reactions were inhibited to 1-3% of normal activity by preincubation of microsomes without NADPH-generating system at 37 degrees C for 10 minutes indicating the FAD-containing monooxygenase-catalyzed reactions. On the other hand, the reactions were not inhibited by gas phase containing up to 80% carbon monoxide/20% oxygen mixture. The results are compatible with the hypothesis that in rat liver microsomes the N-oxygenation and N-demethylation of TMA are catalyzed only or predominantly by FAD-containing monooxygenases, and the cytochrome P-450 monooxygenases play a negligible, if any, role.     

Reduced cardiotoxicity of doxorubicin given in the form ofN-(2-hydroxypropyl) methacrylamide conjugates: an experimental study in the rat

Summary A rat model was used to evaluate the general acute toxicity and the late cardiotoxicity of 4 mg/kg doxorubicin (DOX) given either as free drug or in the form of threeN-(2-hydroxypropyl)methacrylamide (HPMA) copolymer conjugates. In these HPMA copolymers, DOX was covalently bound via peptide linkages that were either non-biodegradable (Gly-Gly) or degradable by lysosomal proteinases (Gly-Phe-Leu-Gly). In addition, one biodegradable conjugate containing galactosamine was used; this residue was targeted to the liver. Over the first 3 weeks after the i.v. administration of free and polymer-bound DOX, all animals showed a transient reduction in body weight. However, the maximal reduction in body weight seen in animals that received polymer-bound DOX (4 mg/kg) was significantly lower than that observed in those that received free DOX (4 mg/kg) or a mixture of the unmodified parent HPMA copolymer and free DOX (4 mg/kg;P<0.01). Throughout the study (20 weeks), deaths related to cardiotoxicity were observed only in animals that received either free DOX or the mixture of HPMA copolymer and free DOX; in these cases, histological investigations revealed marked changes in the heart that were consistent with DOX-induced cardiotoxicity. Sequential measurements of cardiac output in surviving animals that received either free DOX or the mixture of HPMA copolymer and free DOX showed a reduction of 30% in function beginning at the 4th week after drug administration. The heart rate in these animals was 12% lower than that measured in age-matched control rats (P<0.05). Animals that were given the HPMA copolymer conjugates containing DOX exhibited no significant change in cardiac output throughout the study (P<0.05). In addition, no significant histological change was observed in the hearts of animals that received DOX in the form of HPMA copolymer conjugates and were killed at the end of the study. However, these animals had shown a significant increase in heart rate beginning at 8 weeks after drug administration (P<0.01). This study demonstrates that covalent binding of DOX to HPMA copolymer conjugates via both stable and biodegradable peptidyl linkages considerably reduces both the general acute toxicity and the late cardiotoxicity of DOX in the rat and could offer the potential for improving the therapeutic index in the clinical application of DOX.     

Effect of phenobarbital pretreatment on in vitro enzyme kinetics and in vivo biotransformation of benzene in the rat

Phenobarbital pretreatment (50 mg/kg/day for 3 days orally) of male Wistar rats increased V _max of benzene in vitro hepatic microsomal biotransformation about 6-fold without changing K _m . However, benzene blood levels after oral, intraperitoneal, or subcutaneous benzene administration (3–3.5 mmoles/kg) were not influenced by phenobarbital pretreatment. The phenol blood levels after oral or intraperitoneal benzene were increased by phenobarbital pretreatment, but less than expected from in vitro data and only 3 h after benzene administration. Phenol elimination in urine after subcutaneous benzene was not affected by phenobarbital. After oral or intraperitoneal benzene administration, phenol urine excretion closely followed the levels of phenol in blood, i.e., rate of phenol urine excretion was significantly, but shortly increased, and the cumulative urine excretion of phenol increased very little or remained unchanged. Differences between the in vitro and in vivo observations of the effect of phenolbarbital on benzene biotransformation may partly be explained by distribution of benzene, which apparently limited benzene availability for biotransformation (V _d =5.5) and caused rapid decrease of benzene concentrations in blood. Conditions for enzyme activity may have been substantially different in vitro vs. in vivo: in vitro concentrations of benzene were at least by an order of magnitude higher than phenol concentrations, while in vivo, an opposite relation prevailed making a competition for microsomal monooxygenase possible. Cofactor availability may be another rate-limiting step or factor of in vivo benzene biotransformation, as benzene ring hydroxylation requires high energy. The rate of in vitro hepatic microsomal benzene biotransformation proved to be of limited value when predicting benzene quantitative biotransformation in vivo in contradistinction to various substrates where the in vitro and in vivo biotransformation data are in good agreement     

Effects of Alendronate and Calcitonin on Bone Mineral Density in Postmenopausal Osteoporotic Women. An Observational Study

Objective: Alendronate and calcitonin are antiresorptive drugs that were used for the treatment of postmenopausal osteoporosis and were shown to increase bone mineral density (BMD). However, the effect of both drugs in daily clinical practice may differ from that observed in clinical trials.Method: About 50 postmenopausal osteoporotic women were observed during their first year of treatment. Among them, 32 patients used alendronate and 18 used calcitonin. Lumbar spine and femoral neck BMD were measured by dual energy X-ray absorptiometry (DXA) at baseline and after 1 year of therapy. Biochemical markers (B-ALP – bone-specific alkaline phosphatase, OTC – osteocalcin and DPD/UCr – deoxypyridinoline/creatinine ratio) of bone metabolism were measured at baseline and 6 months later. Patient compliance was assumed by tablet counting and verified at interview. Each patient was further questioned about her attitude towards the treatment, as well as her dairy product intake, physical activity, use of other medications, smoking and social status.Main outcome measure: (1) Annual percent change in BMD in lumbar spine and femoral neck after the one-year treatment with either alendronate or calcitonin. (2) The change in biochemical markers of bone turnover.Results: The lumbar spine BMD significantly increased by 7.0% (P < 0.001), the femoral neck BMD by 4.3% (P < 0.01). OTC, B-ALP and DPD/UCr decreased significantly during the therapy with alendronate. Compliance with therapy was 79% (95% CI 68–90%). In the calcitonin-treated group, the lumbar spine BMD significantly increased by 3.1 % (P < 0.05), while the femoral neck BMD remained unchanged. OTC, B-ALP and DPD/UCr did not change significantly during the treatment with calcitonin. Compliance with calcitonin therapy was 87% (95% CI 63–110%). The annual change of BMD in both treatment groups was independent on all questioned factors.Conclusion: In daily practice, alendronate enhanced significantly BMD both in lumbar spine and femoral neck. Calcitonin showed increase only in the lumbar spine BMD.     

Trio engagement via plasma membrane phospholipids and the myristoyl moiety governs HIV-1 matrix binding to bilayers

Localization of the HIV type-1 (HIV-1) Gag protein on the plasma membrane (PM) for virus assembly is mediated by specific interactions between the N-terminal myristoylated matrix (MA) domain and phosphatidylinositol-(4,5)-bisphosphate [PI(4,5)P₂]. The PM bilayer is highly asymmetric, and this asymmetry is considered crucial in cell function. In a typical mammalian cell, the inner leaflet of the PM is enriched in phosphatidylserine (PS) and phosphatidylethanolamine (PE) and contains minor populations of phosphatidylcholine (PC) and PI(4,5)P₂. There is strong evidence that efficient binding of HIV-1 Gag to membranes is sensitive not only to lipid composition and net negative charge, but also to the hydrophobic character of the acyl chains. Here, we show that PS, PE, and PC interact directly with MA via a region that is distinct from the PI(4,5)P₂ binding site. Our NMR data also show that the myristoyl group is readily exposed when MA is bound to micelles or bicelles. Strikingly, our structural data reveal a unique binding mode by which the 2′-acyl chain of PS, PE, and PC lipids is buried in a hydrophobic pocket whereas the 1′-acyl chain is exposed. Sphingomyelin, a major lipid localized exclusively on the outer layer of the PM, does not bind to MA. Our findings led us to propose a trio engagement model by which HIV-1 Gag is anchored to the PM via the 1′-acyl chains of PI(4,5)P₂ and PS/PE/PC and the myristoyl group, which collectively bracket a basic patch projecting toward the polar leaflet of the membrane.     

Forms of Smoking Among Children Ages 8 to 12 Years in Prague,Czech Republic

Smoking is rarely monitored in children younger than 12 years of age. In order to learn more about this demographic group, smoking behavior among 3,887 children ages 8 to 12 years was evaluated in Prague, Czech Republic. Among the children evaluated, 24.0% reported having ever smoked. The mean age of the first smoking experience was 8.2 years (SD = 1.7). Cigarettes were the most common form of smoking (16.5%), but children reported the use of other forms of smoking including water pipes (7.4%), cigars (3.9%), and marijuana (0.8%). These findings have important public health implications.