PubMed Health⌕ Search

Biomedical subjects

A Suciu

Publications and source records attributed to A Suciu.

At least 19 recordsLinked to original sources
PubMed1998

Endothelin-1 and endothelin-converting enzyme-1 gene regulation by shear stress and flow-induced pressure.

Hemodynamic forces have been shown to modulate the expression of endothelin (ET-1) and endothelin-converting enzyme (ECE-1) in endothelial cells. We have subjected E.A. hy 926 cells in culture to steady fluid shear stress with and without flow-induced pressure. The effect of combining these two mechanical forces on the expression of genes in the ET system was studied and the changes were compared to the mRNA levels in static culture. Analysis of total RNA by Northern blot analysis and RNAse protection showed that steady shear stress induced ET-1 gene expression three- to fourfold in this system. The same condition had little to no effect on altering expression of ECE-1 isoforms. A range of flow-induced pressure (80-160 mm Hg) was not able to further augment ET-1 or ECE-1 gene expression. Overall, with the mechanical environment studied, we have been able to detect a predominant contribution of shear stress to altering the ET-1 gene in our system. Furthermore, this induction was independent of an alteration of ECE-1 gene levels, suggesting that these two genes have a different pattern of regulation by the same stimuli in this cell type.

Aspartic Acid Endopeptidases↗
PubMed1997

Model for the alignment of actin filaments in endothelial cells subjected to fluid shear stress.

Cultured vascular endothelial cells undergo significant morphological changes when subjected to sustained fluid shear stress. The cells elongate and align in the direction of applied flow. Accompanying this shape change is a reorganization at the intracellular level. The cytoskeletal actin filaments reorient in the direction of the cells' long axis. How this external stimulus is transmitted to the endothelial cytoskeleton still remains unclear. In this article, we present a theoretical model accounting for the cytoskeletal reorganization under the influence of fluid shear stress. We develop a system of integro-partial-differential equations describing the dynamics of actin filaments, the actin-binding proteins, and the drift of transmembrane proteins due to the fluid shear forces applied on the plasma membrane. Numerical simulations of the equations show that under certain conditions, initially randomly oriented cytoskeletal actin filaments reorient in structures parallel to the externally applied fluid shear forces. Thus, the model suggests a mechanism by which shear forces acting on the cell membrane can be transmitted to the entire cytoskeleton via molecular interactions alone.

Actins↗
PubMed1995

Synergistic effects of fluid shear stress and cyclic circumferential stretch on vascular endothelial cell morphology and cytoskeleton.

The development of atherosclerosis is thought to be initiated by a dysfunctional state of the vascular endothelium. The proposal that mechanical forces play a role in the localization of this disease has led researchers to develop in vitro models to assess their effects on cultured endothelial cells. The arterial endothelium is exposed simultaneously to circumferential hoop stretch and wall shear stress, yet previous investigations have focused on the isolated effects of either cyclic stretch or shear stress. The influence of physiological levels of combined shear stress and hoop stretch on the morphology and F-actin organization of bovine aortic endothelial cells was investigated. Cells subjected for 24 hours to shear stresses higher than 2 dyne/cm2 or to hoop stretch greater than 2% elongated significantly compared with unstressed controls and oriented along the direction of flow and perpendicular to the direction of stretch. Exposure to more than 4% stretch significantly enhanced the responses to shear stress. Both shear stress and hoop stretch induced formation of stress fibers that were aligned with the cells' long axes. Simultaneous exposure to both stimuli appeared to enhance stress fiber size and alignment. These results indicate that shear stress and hoop stretch synergistically induce morphological changes in endothelial cells, which suggests that circumferential strain might modulate sensitivity of endothelial cells towards shear stress.

Animals↗
PubMed1990

Helicobacter-like organisms in gastroduodenal diseases.

The incidence of the Helicobacter-like organisms (HLO) was investigated on biopsy specimens of antral gastric mucosa, stained by the Wayson technique, in 509 patients with various gastric and duodenal diseases. The incidence of HLO was: 72.8 percent in gastric ulcer, 69.6 percent in duodenal ulcer, 69.2 percent in bulbitis, 61.0. percent in chronic gastritis, 37.5 percent in the postoperative stomach, 50 percent in gastric cancer, and 34.3 percent on healthy controls. The HLO were present over the whole year, with a peak in March. Sex and age had little influence on the HLO incidence. The Wayson staining technique proved to be a good technique of detection of HLO on gastric mucosa smears.

Adult↗
PubMed1979

[The mechanism of action of phenobarbital on the metabolism of 131J-B.S.P. in cholestasis induced by ANIT in isolated and perfused rat liver (author's transl)].

In order to establish whether the increased B.S.P. secretion in the bile following phenobarbital administration is the consequence of change in the bile output or represents a consequence of the enzymatic induction, the dynamics of the elimination of 131J-B.S.P. was studied in animals treated with ANIT and Phenobarbital in the conditions of isolated perfused liver. At the same time the levels of the conjugation enzyme of B.S.P. were also determined. It was noted that after Phenobarbital the biliary elimination of 131J-B.S.P. is in correlation with the important increase of the output; in the animals treated with ANIT, on the other hand, the biliary excretion of B.S.P. is minimal. The biliary elimination is directly proportional to the increased of the bile output and reflects the changes found in the perfusate. Our findings allow us to assume that the increased of the bile output and in a smaller extent the result of the stimulation B.S.P. conjugation with Gluthation.

1-Naphthylisothiocyanate↗
PubMed1978

Improvement of perfusion flow in the isolated rat liver under the influence of streptase. Autohistoradiographic aspects of 125I-labelled fibrinogen deposition.

The dynamics of the fibrinoplastic process were studied in rat isolated liver, perfused in normothermia with a synthetical medium. For the autohistoradiographical study, 125I-labelled fibrinogen was added to the perfusing medium. The historadiograms obtained suggest that the main link in the rise of trans-hepatic vascular resistance is thickening of the fibrin muff of the sinusoids. Consequent reduction of the capillary permeability determines favourable conditions for stasis and massive precipitation of fibrinogen under the form of fibrin thrombi into the intrahepatic vessels. Streptase addition to the perfusion medium prevents the intervention of these mechanisms during the studied period.

Animals↗
PubMed1977

[The action of silymarin on Galactosamine-induced hepatitis in the rat (author's transl)].

The hepatoprotective action of Silymarin was studied in 65 male Wistar rats, prior to and following D-galactosamine intoxication. There was a marked reduction in the histological and ultrastructural changes in the nucleolus, nuclear membrane, mitochondria, granular and agranular endoplasmic reticulum and lysosomes of the liver cell and also in the Kupffer stellate cells. The reduction in glycogen and RNA loss was determined biochemically. The activities of many enzymes were kept constant (oxidoreductases, NADH2 diaphorase, G-6-phosphatase, Mg++ and K+/Na+-dependent ATPases, acid phosphatases).

Acid Phosphatase↗
PubMed1976

Protecting action of aspartate on the hepatic changes induced by D-galactosamine.

The protective action of aspartic acid on isolated and perfused rat liver was studied. In case of D-galactosamine intoxication the GOT, GPT and SDH activity and the lactate and pyruvate concentration in the perfusion medium were less augmented and the glycogen level in hepatic tissue was less diminished in animals treated with aspartic acid, as compared to controls. The histochemical applied (PAS reaction for glycogen, nucleic acids, NADH2-diaphorase, glucose-6-phosphatase and membrane-ATP-ase), also stated a protecting effect in the treated animals. The protective action of aspartate is hypothetically considered to be exerted by its capacity to reestablish the cellular deficit of pyridine nucleotides and thus to improve the synthesis of nucleic acids, glycoprotein and glycolipids or/and by its participation in various metabolic pathways.

Adenosine Triphosphatases↗
PubMed1975

Familial clustering of degenerative cardiovascular diseases.

In two geographical areas; the Gurghiu Valley, in a mountain region, and the village of Jurilovca on the shores of the Razelm lagoon, investigations were performed in 390 subjects of both sexes over 20 years of age, first degree relatives of healthy index subjects (males aged 40 to 60 years) and 298 subjects of both sexes over the of 20, first degree relatives of index-subjects with coronary heart disease and/or hypertension. The prevalence of these diseases was found to be 40% higher in the families of diseased subjects. The authors assume the participation of a genetic factor in the etiology of these two degenerative cardiovascular diseases.

Adult↗
PubMed1975

Coronary heart disease and risk factors in some special type collectivities.

Transversal epidemiologic investigations carried out in different populations from several regions of Romania : Gurghiu Valley (lumberjacks from a mountain region), Danube Delta and Razelm lagoon complex (fishermen), and Bucharest have shown that, in spite of the high caloric value of food and even of a high intake of saturated fats, mean serum cholesterol is lower in the rural areas than in Bucharest, probably owing to the strenuous physical work. However, except myocardial infarction, more frequent in the urban than in the rural regions, the other forms of coronary heart disease have a relatively higher frequency in villages, particularly atrial fibrillation and ECG signs of ischemia. These findings might be explained by a greater prevalence of hypertension in these populations. It is concluded that the risk factors, which act synergically, depend on the complex structure of the "ecologic niche".

Adult↗