Search PubMed⌕ Search

Biomedical subjects

R Tongiani

Publications and source records attributed to R Tongiani.

48 records · Page 3Linked to original sources
PubMed1969

I. Quantitative determination of the amount of DNA per nucleus by interference microscopy.

A method for the determination of the DNA content of isolated nuclei of different ploidy has been developed. It is based on measurement of the nuclear dry mass, with an integrating microinterferometer, before and after DNase treatment. The values found are slightly low, because, as indicated by biochemical determinations, consistently 5% to 8% of DNA is not extracted by DNase under these conditions. The average DNA values thus obtained for diploid and tetraploid nuclei of adult rat liver are 7.7 and 15.6 pg (10(-12) g), respectively. Definite advantages of this procedure are: i) comparisons with biochemical determinations to give DNA values for each class of ploidy, ii) comparisons with histophotometry of the Feulgen dye-DNA complex to give absolute values instead of arbitrary units.

Animals↗
PubMed1969

II. Differences in adrenal medulla nuclear DNA content among rats of different strains following intermittent exposure to cold.

The amount of DNA per nucleus in the adrenal medulla cells of four different strains of rats (Wistar, Sprague-Dawley, Long-Evans, and Italico) is determined both under control conditions and after 300 hr of intermittent exposure to cold. The adrenal medulla nuclei of the four strains of rats contain the same amount of DNA; however, the loss of DNA observed after the same experimental treatment differs markedly in the different strains. The loss is small in Wistar and Sprague-Dawley rats (8-13%), larger in Long-Evans rats (20%) and still larger in Italico rats (45%). The DNA loss in Wistar rats increases if the animals are fed the same diet as the Italico rats, and the DNA loss in Italico rats is reduced if the animals are fed the same diet as the Wistar rats. The different behavior of the four strains is discussed in terms of turnover of DNA.

Adaptation, Physiological↗
PubMedDate not supplied

Assessment of P-glycoprotein-dependent drug transport in isolated rat hepatocytes using rhodamine 123.

To test the activity of P-170 glycoprotein in isolated hepatocytes, a method has been developed employing the fluorescent dye rhodamine 123 (R-123). The uptake of R-123 by both freshly isolated and 4-hr-plated hepatocytes depends on dye concentration, time of incubation, and cell number. The efflux of R-123 from cells is inhibited by sodium azide and by verapamil. In standard conditions the efficiency of efflux of R-123 from cells correlates with the relative amount of immunoblottable glycoprotein. The method has been applied to detection of P-170 activity in hepatocytes from animals of different ages as well as from carcinogen-treated animals. The proposed assay appears a simple and adequate tool for the functional assessment of multidrug transporter in liver.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMedDate not supplied

Early biochemical liver changes following thiobenzamide poisoning.

Administration of thiobenzamide in a single dose (25 mg/100 g body wt by stomach tube) to male rats induced centrilobular necrosis, which became evident 10 h after the poisoning. In the meantime liver weight and water content underwent changes, glycogen was lost, triglycerides accumulated in the liver while decreasing in serum, [3H] leucine uptake in proteins was impaired and the activity of glucose-6-phosphatase and aminopyrine demethylase decreased. The activity of NADPH-cytochrome c reductase remained unchanged, whereas a reduction of the microsomal cytochrome P-450 occurred. The liver amount of reduced glutathione underwent no significant changes. Pretreatment of the animals with cobalt chloride or 20-methylcholanthrene decreased the liver damage caused by the drug. The in vitro addition of thiobenzamide to liver microsomes resulted in a spectral change. The appearance of conjugated dienes among microsomal lipids from drug-treated rats indicated for a lipoperoxidation taking place in vivo.

Alanine Transaminase↗
PubMedDate not supplied

Gamma-glutamyltranspeptidase activity in human ovarian carcinoma.

Gamma-glutamyltranspeptidase (GGT) is a cell membrane enzyme involved in the hydrolysis and uptake of extracellular glutathione. Histochemically detectable GGT has been shown in several human neoplasms. However, few studies have addressed the quantitative biochemical assessment of GGT activity in human tumors, and the importance of GGT activity in human tumor biology remains to be elucidated. The aim of the present study was to assess biochemically GGT enzyme activity in human ovarian surgical biopsies. GGT activity was assayed in homogenates of surgical samples of ovarian tumors and compared with the clinical data of the patients in order to establish: a) the level of tumor GGT activity, b) its correlation with other clinical parameters of the neoplasms, c) the possibility of the induction in vivo of GGT after anticancer platinum-based therapy, since some of the patients were pretreated. The results indicated that ovarian tumor expresses biochemically relevant GGT activity. The sensitive method used in this study allowed the quantitative evaluation of enzyme activity in all samples examined, showing that GGT activity values in ovarian carcinoma samples were extremely variable among the different subjects, both in untreated neoplasms (6.2 +/- 5.4 mU/mg protein) and in second-look laparotomy biopsies following platinum-based therapy (4.7 +/- 3.8 mU/mg protein). The mean GGT activity in benign ovarian tumors was lower than that in malignant tumors. No significant correlation was found between GGT activity and patient characteristics (tumor stage, age of patients, serum CA125, TAG-72, and GGT levels). However, the biological and pharmacological relevance of GGT expression remain to be elucidated in a large series of tumors.

Adult↗