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Biomedical subjects

G Semino

Publications and source records attributed to G Semino.

16 recordsLinked to original sources
PubMed1997

A pharmacokinetic model describing pulsatile uptake of orally-administered carbon tetrachloride.

Many rodent bioassays have been conducted using oral gavage for delivery of test chemicals. Highly lipophilic compounds are generally administered to rodents dissolved in corn oil, a dosing vehicle shown to influence xenobiotic toxicity, carcinogenicity and pharmacokinetics by altering chemical absorption processes. In this paper, we present a multi-compartmental description of the gastrointestinal (GI) tract linked to a physiologically based pharmacokinetic (PB-PK) model to describe the complex oral uptake of carbon tetrachloride (CCl4) administered in corn oil and 0.25% Emulphor. The GI submodel was described using a series of subcompartments, each subcompartment described with an absorption constant (Ka, 1/h), a bioavailability term (A, unitless), and a compartment emptying time (T, h). The model was parameterized by fitting multi-peak blood and exhaled breath chamber concentration-time profiles following oral gavage of CCl4 in corn oil and aqueous vehicles to male Fischer 344 rats. Successful fitting of experimental data was accomplished by varying values of Ka, A, and T until adequate fits were obtained. Values of Ka and A required to fit data from aqueous gavage were greater than corn oil. Utilization of the multi-compartmental GI tract submodel provided increased precision in fitting complex oral uptake profiles compared to previously used one- and two-compartment oral uptake models. This model provides estimates of absorption rate constants and bioavailabilities as well as providing a framework for generation of more complete, physiologically-realistic descriptions of oral absorption.

Administration, Oral↗
PubMed1997

[Cystic dilatation of the choledochus associated with stenosis of the hepatic duct bifurcation. An analysis of a clinical case].

The authors report a case of cystic dilatation of the choledochus associated with narrow stenosis at the confluence of the left and right hepatic ducts which was found to be inflammatory on histological examination. This pathology is becoming an increasingly more commonplace clinical finding. The case reported here is particularly interesting owing to the onset of the disease and the way in which it was treated. An attempt was made to treat the patient using a simple operation which was to the least radical possible. The authors take this opportunity of reviewing the literature on the subject.

Aged↗
PubMed1995

[Malignant tumors of the pancreas and periampullary area. Our experience].

The authors analyse and evaluate the clinical records of 45 patients treated in the last 4 years for pancreatic cancer and neoplasm of the bilioduodenapancreatic area, comparing the results with data available in the literature. In the group of patients treated with resection (12 cases), postoperative morbidity and mortality were respectively 28% and 6%, and three-years survival was 22%. The authors discuss particularly about reconstruction ways after duodenopancreatectomy, showing good results after reconstruction by Y loop sec. Roux and pancreato-jejunal anastomosis.

Adenocarcinoma↗
PubMed1989

Body composition in subjects with surgically obtained stable body weight normalization.

The body composition of lean control subjects was compared with that of subjects following biliopancreatic diversion for morbid obesity, when their excess weight had been stabilized at under 40 per cent of the ideal body weight value for over two years. Lean body mass, body cell mass and fat were indirectly calculated from total body water and total body sodium, measured by isotope dilution technique. The body composition in the two groups of subjects was essentially normal, as was indicated by the percentage values of the body composition parameters and by the linear correlations between body weight and the lean body compartments size.

Adult↗
PubMed1986

[Total nitrogen concentration in human liver tissue. Correlations between morphological and microanalytical data].

The degree of hepatic steatosis and percentage total nitrogen content were evaluated simultaneously in a group of obese patients and after bypass surgery for obesity. The straight line relationship between sample weight and gas chromatographic response integrals shows that samples had the same water content. The higher concentration of total nitrogen in patients with higher levels of steatosis and the inverse correlation between degree of adipose infiltration and degree of total nitrogen, when water content is the same, suggest that the total liver parenchyma nitrogen concentration closely reflects the structural protein content.

Adult↗
PubMed1986

The presence of mercury (total and organic) and selenium in human placentae.

The concentrations of mercury (total and organic) and selenium in samples of human placentae obtained after normal births from 22 women living in Genova (Italy), were determined by atomic absorption spectrometry. The concentration of total mercury was between less than 0.005 and 0.230 microgram Hg/g dry weight, and the average value was 0.076 microgram Hg/g dry weight. For the same samples, the average percentage of organic mercury as mercury was 65%, with a maximum of 95%. Smaller variations were observed for selenium, i.e. concentrations ranging between 0.38 and 1.03 microgram Se/g dry weight, with an average value of 0.77 microgram Se/g dry weight. The ratio between wet weight and dry weight was determined for each sample and the average value found was 6.32. The placental selenium concentration did not correlate with total and organic mercury content, which is in accordance with the results of other researchers.

Diet↗
PubMed1984

Extracellular matrices produced in the presence of dexamethasone: a natural "growth agent" for human cultured endothelium.

Cultured endothelium synthesizes an extracellular matrix that resembles the basement membrane of the vessels. We studied the aspect of extracellular matrices produced in presence or absence of dexamethasone by immunofluorescent technique for fibronectin; the glycoprotein is more abundant in matrices produced in the presence of dexamethasone than controls and forms a very dense meshwork. When endothelial cells resuspended in medium without FCS were seeded on these preformed matrices they adhered and replicated. The endothelium grown on matrices preformed in the presence of steroid showed a better morphology and covered a greater area indicating the presence of more abundant fibronectin content in basal lamina.

Cell Adhesion↗
PubMed1984

The effect of ticlopidine on human endothelial cells in culture.

The effect of ticlopidine at various concentrations (150, 30, 6 microM), has been studied on cultured endothelial cells derived from human umbilical cord vein. Ticlopidine affects the initial attachment of endothelial cells to artificial substrata and has an inhibitory effect on endothelial cell growth rate which correlates to the concentration of the chemical in the culture medium. These effects are related to a marked reduction of intra- and extracellular fibronectin as evidentiated by immunofluorescence. The drug seems to interfere with the formation of fibronectin filaments from intracellular granules. The reduction of fibronectin availability could affect platelet adhesion to subendothelium as well as endothelial cell repair, and subsequently influence the bleeding time. The inhibition of cell proliferation and its possible effect on the thickness of the vessel wall should be considered as additional mechanisms of action for this substance.

Anticoagulants↗
PubMed1983

Interactions between tumor cells and vascular endothelium.-I) Adhesion properties of cell lines with different metastasizing capacity.

The authors describe the adhesive properties of four murine tumor lines, chemically and virus induced, with different metastasizing potential. Cancer cells show similar behaviour in attachment kinetics when tested with endothelium monolayer or plastic surfaces, without differences between the lines with high or low malignancy. The time required for a complete adhesion to endothelial cells is three hours while to plastic surfaces is 90 min. The role of divalent cations is not required in the first phases of cellular attachment of tumor lines to plastic dishes.

Animals↗