Metabolism of carbon tetrachloride to phosgene

Aerobic incubation of hepatic microsomal fractions in the presence of carbon tetrachloride, NADPH and cysteine resulted in the formation of phosgene which was identified by gas chromatography/mass spectrometry as the adduct, 2-oxothiazolidine-4-carboxylic acid, formed by its reaction with cysteine. [¹³C]-Carbon tetrachloride was metabolized to 2-[¹³C]-oxothiazolidine-4-carboxylic acid the , when carbon tetrachloride was incubated in the presence of [¹⁸O]-O₂, 2- [¹⁸O]-oxothiazolidine-4-carboxylic acid was formed. The reaction was inhibited by carbon monoxide showing the involvement of the cytochrome P-450-dependent mixed function oxidase system. The metabolism of carbon tetrachloride to phosgene may play a role in the production of hepatotoxicity by this compound.     

Enzymatic System of Metabolism and Detoxication of Xenobiotics as a Basis of Metabolic Portraiting during Prognostication of Risk of Pathological Processes

We studied intraspecific features of the main enzymes of metabolism and detoxication of xenobiotics on mice (eight inbred lines) and rats (five lines) for estimation of possible variants of complete or incomplete metabolic equality. Significant genetically determined intraspecific differences for activities of the enzymes of metabolism and detoxication of xenobiotics were described. Generalized criteria for comparison of the metabolic status were proposed on the basis of activities of the main enzymes: cytochrome P-450 (hydroxylation and epoxidation), epoxyhydrolase, glutathione-S-transferase, UDP-glucuronosyl transferase, and sulfotransferase. The proposed criteria for estimation of the metabolic parameters of an individual can serve as a basis of metabolic portraiting.     

Novel inhibition of proteoglycan synthesis and exocytosis by diethylcarbamazine in the Swarm rat chondrocyte

Pretreatment of cultured chondrosarcoma chondrocytes at 37 degrees C for 15 min with 15 mM diethylcarbamazine (DEC) followed by a 60-min pulse with [35S] sulfate in the presence of DEC resulted in an approximate 40% inhibition of synthesis and a 75% inhibition of secretion of 35S-proteoglycan. The inhibition was dose-related and was not due to a decrease in protein synthesis. Chondrocytes exposed for 75 min to 15 mM DEC, washed, incubated for 17 h in DEC-free medium, and then pulsed with [35S]sulfate showed no inhibition in the rate of synthesis of proteoglycan or in the per cent of radiolabeled proteoglycans exocytosed into the culture medium, indicating full reversibility of the inhibitory effect. When chondrocytes were incubated for 75 min with both 1 mM beta-D-xyloside and 15 mM DEC, secretion of beta-D-xyloside-bound 35S-glycosaminoglycan was inhibited by more than 70% despite an approximate 3-fold increase in intracellular 35S-macromolecules, as compared to cells exposed to beta-D-xyloside alone. Upon removal of DEC, the block in the secretion of beta-D-xyloside-bound 35S-glycosaminoglycans was reversed, although there was a 15-30-min lag in the initiation of exocytosis. Light and electron microscopic examination of chondrocytes after 75 min of incubation with 15 mM DEC revealed large vacuoles, a distended Golgi apparatus, and a distended endoplasmic reticulum which contained electron dense material. Upon removal of DEC, the vacuoles disappeared and distended organelles returned to their normal appearance between 15 and 30 min, coincident with the start of exocytosis of 35S-proteoglycan and beta-D-xyloside-bound 35S-glycosaminoglycan. These biochemical and morphological studies indicate that DEC treatment of chondrosarcoma chondrocytes alters the transport of molecules from the endoplasmic reticulum to the Golgi and the transport of molecules from the Golgi to the cell surface.     

Effect of tranquilizers on the total acetylcholine content and acetylcholinesterase activity in the brain tissue of Arvicanthis niloticus

The effect of reserpine and meprobamate on the total acetylcholine content and acetylcholinesterase activity in the brain tissue of the kusu rat, Arvicanthis niloticus, was studied. The total acetylcholine content and acetylcholinesterase activity were determined 1 hr after i.p. injection of different doses of reserpine (0.25, 0.5 and 1 mg/ml/100 g body wt) and meprobamate (6.25, 12.5 and 25 mg/ml/100 g body wt). The effect of different time intervals (1, 10, 30 min, 1, 2.5, 5, 8, 12, 24 and 48 hr) on the total acetylcholine content and acetylcholinesterase activity was investigated after i.p. injection of 0.5 mg of reserpine and 12.5 mg of meprobamate/ml/100 g body wt. Both reserpine and meprobamate caused an increase in the total ACh content in the brain tissue of Arvicanthis niloticus which was suggested to be due to a decrease in the release of ACh, since both reserpine and meprobamate inhibited AChE activity after some tested periods. The effect of meprobamate was observed to be stronger than that of reserpine.     

Antibodies to the hepatitis A virus in the healthy population of Moscow

Serum specimens collected from 1002 persons in Moscow were tested for the presence of antibodies to hepatitis A virus (anti-HAV antibodies) by solid-phase enzyme immunoassay. The prevalence of these antibodies increased progressively with age from 10% in children aged 5-9 years to over 90% in the age groups of 40-49 years and over, the 50% immunity level being established at the age of 18 years. 79% of infants under 1 year were found to be immune, which was obviously due to the placental transfer of antibodies from mother to child. In a considerable part of seropositive persons over 30 years high or medium antibody titers were detected. These age groups showed a stable proportion of the low, medium and high level of anti-HAV antibodies. The prevalence of such antibodies was not related to sex. The presence of an ample amount of anti-HAV antibodies was determined in all of 18 tested lots of commercial serum immunoglobulin obtained from 3 different manufacturers.     

Vegetative fallows and potential value of the neem tree (Azadirachta indica) in the tropics

Research into the systems of agriculture based on vegetative fallows should begin from enquiries into the shrubs and trees most efficient in restoring soil productivity and providing firewood, timber, fodder and other products essential to meeting basic needs at the rural household and community level. Local processing of such products can give rise to the establishment of thriving village industries and thus generate employment and additional income. Neem tree,Azadirachta indica, of the semiarid regions is one outstanding example of a species which is not only an efficient soil ameliorant but can also provide a series of products highly competitive in price and quality with petroleum-based synthetics. Enough scientific evidence has been gathered from several hundred references on the subject to warrant the launching of a well coordinated multidisciplinary research and development programme leading to agricultural, industrial and commercial exploitation of this tree. Proposals for the implementation of several projects within the programme are briefly outlined in this paper.     

A chronobiological study of delta-amino levulinic acid urinary excretion

Determination of urinary delta-amino levulinic acid (ALA) is now systematically used in occupational health to detect an excessive exposure to lead in professionally exposed workers. However, to determine whether circadian changes of the urinary excretion of ALA alter the significance of the test, we quantified the ALA levels in the urine of 19 healthy young adults. Urine samples were taken every 3 hr between 0700 and 2300 hr and ALA levels were determined by a spectrocolorimetric method. The data indicated that the 24-hr mean ALA level was: 1.81 mg/g creatinine. The peak values (2.24 +/- 0.24) were obtained between 1400 and 1700 hr whereas the lowest ALA levels were found between 2200 and 0300 hr. Cosinor analysis revealed a significant circadian rhythm while no significant difference could be found according to sex. Possible explanations of our findings are discussed.     

Initial decomposition ofNymphoides peltata (Gmel.) O. Kuntze (Menyanthaceae), as studied by the leaf-marking method

Summary In this paper the leaf-marking method as used for the study of the development and initial decomposition of floating leaves is described and the reliability of the various measurements is tested and/or discussed. Some general results obtained withNymphoides peltata (Gmel.) O. Kuntze in tanks and in the field are presented and crltically discussed. Autolysis followed by microbial decay was in all cases the most important factor by which leaves disintegrated. In the field plots animals were responsible for the disappearance of 22% of the total leaf area produced during a growth season. This is, however, the combined effect of consumption and damage succeeded by microbial decay. Real grazing can be estimated to be no more than 10% of the production of floating leaves. Fungi can have an important role in initial decomposition, especially after the flowering period, as is demonstrated forSeptoria villarsiae Desm. All damage types show temporal and, in the case of animals, also spatial distribution patterns.