Polycyclic aromatic hydrocarbons in placenta, maternal blood, umbilical cord blood and milk of Indian women

Human placenta, umbilical cord blood, maternal blood and breast milk samples from mothers were analysed for the presence of selected polycyclic aromatic hydrocarbons (PAHs). Benzo(a) pyrene (B(a)P), dibenzo(a,c)anthracene (DBA) and chrysene (Chy) were detected in all the four types of sample. Levels of dibenzo(a,c)anthracene were higher in the above samples compared with the other two PAHs. Umbilical cord blood and breast milk samples showed relatively high concentrations of all the three PAHs and thus demonstrated that the developing foetus/new born were exposed to these carcinogenic environmental contaminants. The possible implications of PAHs in relation to human health are discussed.     

Maturation and differentiation of cultured fetal stomach. Effects of corticosteroids, pentagastrin, and cytochalasin B

Gastric mucosa of fetal rats undergoes striking developmental changes during the last few days of gestation in utero. To investigate some aspects of this process, gastric explants from 18-day fetuses (4 days before birth) were maintained in organ culture for 3 days, then assessed by light and electron microscopy. The epithelia from base line uncultured stomachs were stratified and morphologically undifferentiated. During culture in basic medium (Leibovitz L 15), modest maturation of antral and fundic architecture occurred, characterized by epithelial invagination to produce small pit-glands. Secretory granules appeared in occasional epithelial cells, and cytochemistry indicated that most were mucous granules. Addition of pentagastrin (10(-9) to 2 X 10(-7) M) did not induce further morphological maturation in this system. However, addition of cortisol (10(-6) to 10(-5) M) resulted in a marked, dose-related increase of pit-gland formation and of cytological differentiation (appearance of secretory granules). This cortisol-induced architectural maturation was completely inhibited by the mold metabolite cytochalasin B (10(-5) M). The results indicate that fetal gastric maturation can be partially reproduced by culture in chemically defined media, and also suggest that corticosteroids may plan an important role in gastric organogenesis.     

The pharmacokinetics and electroencephalogram response of remifentanil alone and in combination with esmolol in the rat

PURPOSE: The goal of this study was to determine if the co-administration of esmolol (ES), a short acting cardioselective beta-blocker, significantly alters the pharmacokinetics and/or pharmacodynamics of remifentanil (REMI), an ultra short-acting opioid, in the rat. METHODS: Sprague-Dawley rats (N = 8, Wt. = 325 +/- 15 g) were surgically implanted with stainless steel cerebrocortical EEG electrodes three days before the study. Each rat was dosed with REMI (15 micrograms/kg/min), and REMI & ES (15 micrograms/kg/min and 600 micrograms/kg/min) for 21 minutes in a random crossover design. Six serial blood samples were collected over 25 minutes into test-tubes containing 0.5 ml acetonitrile. Blood samples were extracted with methylene chloride and analyzed by a validated GC-MS assay. EEG was captured and subjected to power spectral analysis (0.1-50 Hz) for spectral edge (97%). RESULTS: No significant differences (p < 0.05) were found in clearance (REMI = 287 + 73 ml/min/leg vs. REMI & ES = 289 +/- 148 ml/min kg) or Vd (REMI = 286 +/- 49 ml/kg vs REMI & ES = 248 + 40 ml/kg). A linked sigmoid Emax PK-PD model was used and the pharmacodynamic parameters were not statistically different. Mean Emax and EC50 after REMI were 18.0 +/- 6.0 Hz and 32 +/- 12 ng/ml; and after REMI + ES were 19 + 4.8 Hz and 26 + 8.6 ng/ml. CONCLUSIONS: At the doses tested, there is no pharmacokinetic or pharmacodynamic interaction between remifentanil and esmolol in the rat.     

Pharmacokinetics of a high dose of gentamicin administered intravenously or intramuscularly to horses

PURPOSE: The effect of uridine (UR) coadministration on the intestinal metabolism from 5'-deoxy-5-fluorouridine (5'-DFUR) to 5-fluorouracil (5-FU) was evaluated by a method of concentration difference between portal and systemic bloods in conscious rats (PS method). METHODS: 5'-DFUR (100 mg/kg) alone (Group A), or 5'-DFUR + UR (100 mg/kg each) (Group B) was orally administered to conscious rats. The portal and arterial bloods were simultaneously withdrawn from two canulas at appropriate time intervals, and blood concentrations of 5'-DFUR, 5-FU, UR and uracil (U) were assayed by HPLC. The concentration-time profiles of these drugs and its metabolites were analyzed by local moment analysis. RESULTS: UR coadministration made the local absorption ratio (Fa) of 5'-DFUR decrease significantly from 60.1 +/- 10.5% to 38.0 +/- 18.6% of dose. Though the local absorption ratios (Fm(a)) of the metabolite (5-FU) were the same between Group A and Group B (8.3 +/- 1.9 and 8.7 +/- 4.0% of 5'-DFUR, respectively), AUC of arterial 5-FU in Group B was 5 times greater than that in Group A. UR was not detected in the portal blood, and Fm(a) of U was estimated to be 41.9 +/- 26.8% of UR in Group B. CONCLUSIONS: It is predicted that a large portion of 5-FU generated from 5'-DFUR is further degraded in the intestine in Group A, and U generated from UR blocks 5-FU degradation in the intestine and the systemic circulation in Group B.     

Conserved features in papillomavirus and polyomavirus capsids

Capsids of papilloma and polyoma viruses (papovavirus family) are composed of 72 pentameric capsomeres arranged on a skewed icosahedral lattice (triangulation number of seven, T = 7). Cottontail rabbit papillomavirus (CRPV) was reported previously to be a T = 7laevo (left-handed) structure, whereas human wart virus, simian virus 40, and murine polyomavirus were shown to be T = 7dextro (right-handed). The CRPV structure determined by cryoelectron microscopy and image reconstruction was similar to previously determined structures of bovine papillomavirus type 1 (BPV-1) and human papillomavirus type 1 (HPV-1). CRPV capsids were observed in closed (compact) and open (swollen) forms. Both forms have star-shaped capsomeres, as do BPV-1 and HPV-1, but the open CRPV capsids are approximately 2 nm larger in radius. The lattice hands of all papillomaviruses examined in this study were found to be T = 7dextro. In the region of maximum contact, papillomavirus capsomeres interact in a manner similar to that found in polyomaviruses. Although papilloma and polyoma viruses have differences in capsid size (approximately 60 versus approximately 50 nm), capsomere morphology (11 to 12 nm star-shaped versus 8 nm barrel-shaped), and intercapsomere interactions (slightly different contacts between capsomeres), papovavirus capsids have a conserved, 72-pentamer, T = 7dextro structure. These features are conserved despite significant differences in amino acid sequences of the major capsid proteins. The conserved features may be a consequence of stable contacts that occur within capsomeres and flexible links that form among capsomeres.     

Basic characteristics of synthesis and technical requirements for fiber-forming polycarbosilanes

These studies showed that the conditions of synthesis and properties of polycarbosilane are a function of the purity of the stating polydimethylsilane, and the technical requirements for its quality were elaborated as a result of this. The temperature—time parameters of synthesis (350–380°C, 3–8 h) and concentration of promoter — polyborodiphenylsiloxane (1 wt. %), were determined for fabrication of stably formed polymers. The criteria for the end of synthesis and obtaining a polymer with the required degree of branching were established. The preliminary technical requirements for fiber-forming polycarbosilane were formulated.State Scientific-Research Institute of Chemistry and Technology of Organoelemental Compounds, Moscow. Translated from Khimicheskie Volokna, No. 4, pp. 16–18, July–August, 1992.     

Modulation of endothelial cell function by antiphospholipid antibodies

AIM: To observe the effect of captopril (Cap) on intracellular pH (pHi) in aortic smooth muscle cells (ASMC). METHODS: Cultured ASMC derived from rat and rabbit aortae were loaded with the fluorescent dye BCECF and pHi was determined using digital image processing method. RESULTS: The pHi of untreated SHR and WKY rats were 7.37 +/- 0.29 and 7.19 +/- 0.31, respectively. Oral Cap decreased pHi (7.11 +/- 0.26, P < 0.05) and exaggerated pHi response to angiotensin II (Ang-II, 0.1 mumol.L-1) in ASMC of SHR rats vs WKY rats (0.14 +/- 0.05 vs 0.21 +/- 0.05 pH units, P < 0.01). Cap in vitro had no effect on Ang-II induced intracellular alkalinization in ASMC of rabbits. CONCLUSION: Oral Cap inhibits Na+(-)H+ exchange activity in ASMC of SHR rats.     

Pyrolysis gas-liquid chromatography of the genus Bacillus: effect of growth media on pyrochromatogram reproducibility

Pyrolysis gas-liquid chromatography was performed on dried Bacillus microorganisms to evaluate the effects of growth media. Six cultures of Bacillus and six lot numbers of Trypticase soy agar (BBL) were used to test the hypothesis that a microorganism grown on various lot numbers of the same chromatogram. Also tested was the effect of three different media on chromatogram reproduction using the same six cultures. Results show little or no differences observed between the chromatograms of the individual Bacillus spp. grown on the six lot numbers of Trypticase soy agar. When chromatograms of the three different media were compared, several differences were observed, particularly in the areas most characteristic of individual species. Pryolysis gas-liquid chromatography can be a useful tool for the characterization or identification of the genus Bacillus if the chromatographic and cultural conditions are maintained.