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O6-methylguanine-DNA methyltransferase in human fetal tissues: fetal and maternal factors 总被引:1,自引:0,他引:1
O6-Methylguanine methyltransferase (O6-MT) was measured and compared in extracts of 7 human fetal tissues obtained from 21 different fetal specimens as a function of fetal age and race and of maternal smoking and drug usage. Liver exhibited the highest activity followed by kidney, lung, small intestine, large intestine, skin, and brain. Each fetal organ homogenate exhibited a 3- to 5-fold level of interindividual variation of O6-MT. There did not appear to be any significant differences of O6-MT as a function of fetal race and age and in the tissues obtained from mothers who smoked cigarettes during pregnancy. The fetal tissues obtained from an individual using phenobarbital exhibited 4-fold increases in O6-MT activity. The tissues obtained from another individual on kidney dialysis were 2- to 3-fold higher than the normal population. These data suggest a possible enhancement of human fetal O6-MT by certain xenobiotics, with little if any modulation by racial factors and maternal smoking habits. 相似文献
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Nicholas Denko James Stringer Maqsood Wani Peter Stambrook 《Somatic Cell and Molecular Genetics》1995,21(4):241-253
Induced expression of a mutant human Ha-ras oncogene in NIH3T3 cells leads to the rapid production of multicentric chromosomes, acentric chromosome fragments, double minute chromosomes, increased heteroploidy, and increased capacity to undergo gene amplification. In this study we have used fluorescent-in-situ hybridization (FISH) to demonstrate that induction of the Ha-ras oncogene also leads to disruption of the mitotic machinery, resulting in aberrant mitoses and abnormal daughter cells. Cells induced to express an oncogenic Ha-ras transgene accumulate chromosomes that lag outside of the rest of the chromosomal architecture, chromosomes that form bridges between daughter nuclei at anaphase, and that form micronuclei. Many of these mitotic aberrations contain structurally abnormal chromosomes. Theseras-induced changes were suppressed by the introduction of a gene encoding the dominant negative effector ofras, raf 301. Expression ofraf301 in cells induced to express Ha-ras reduced the level of growth in soft agar, chromosome aberrations, mitotic aberrations, and frequency of gene amplification. These data provide evidence for an association between Ha-ras induced transformation, chromosome aberrations and gene amplification. Furthermore they offer insight into how the cell responds to the formation of aberrant chromosomes, and how disrupting chromosomal architecture could lead to further imbalances in the distribution of genetic material between daughter cells. 相似文献
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Wani T Kakru DK Shaheen R Nazir A Lone R Shakeel S Shah A 《Indian journal of pathology & microbiology》2004,47(1):76-77
Endocarditis is a rare complication of typhoid fever. We report a case in which Salmonella enterica serotype typhi was isolated from a case of endocarditis. The isolate was resistant to ampicillin, chloramphenicol and ciprofloxacin but sensitive to ceftriaxone, amikacin and gentamicin. 相似文献
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A linear mathematical model of the electromyogram (e.m.g.) has been developed for the biceps muscle. The number of motor units (and therefore muscle fibres) contributing to the resultant e.m.g. at any stage of movement has been found from the force analysis of elbow flexion. The depths of various motor units and the phase difference between the recruitment of any two motor units have been formulated using a spiral spread of recruitment sequence. The attenuation of individual motor-unit action potentials due to varying depths has been taken into consideration, and due regard has been taken of the length-tension diagram of a muscle while performing the force analysis. Attention has been focused on the flexion of the elbow joint, in which a method of finding the individual contribution of the biceps and brachialis muscles has been developed and applied. The results predicted by the model have been verified by experiments. The model can also be extended to the e.m.g. of other fast skeletal muscles. The conditions and limitations for such generalisations have been stated and discussed. 相似文献
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The kidneys are vital organs in the management of fluid balance, waste product removal, electrolyte homeostasis, acid–base balance and endocrine function. Waste products removed by the kidney are urea, uric acid and creatinine; other foreign products with similar physiochemical properties are also excreted. Urea and uric acid are by products of protein metabolism and creatinine is generated by the metabolism of creatine compounds from muscle. The kidney regulates fluid and electrolyte balance through controlling the composition and volume of urine. In the proximal convoluted tubule and the loop of Henle, 90% of sodium, potassium, calcium and magnesium are reabsorbed. Acid–base balance is achieved by regulating the excretion of hydrogen ions and bicarbonate buffering. The kidney also has a number of endocrine functions including the production of renin and erythropoietin as well as hydroxylation of vitamin D. The kidneys receive 25% of cardiac output, generating 170–200 litres of ultrafiltrate per day. Urine output is approximately 1.5 litres per day, which is concentrated ultrafiltrate through selective reabsorption of solutes and water. In this article we will discuss tests frequently used to assess renal function. 相似文献
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A rare case of hydatid cyst of the pancreas is reported. Although ultrasonography and computerised tomography scan confirmed the presence of a cystic mass in the body and tail of the pancreas, diagnosis was made only on laparotomy. A distal pancreatectomy was done and the diagnosis of hydatid cyst of the pancreas was confirmed by histopathology. Though very rare, pancreatic hydatidosis should be considered in the differential diagnosis of cystic lesions of the pancreas in the appropriate epidemiological setting. 相似文献