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Biomedical subjects

S Tvete

Publications and source records attributed to S Tvete.

13 recordsLinked to original sources
PubMed1983

The effects of angiotensin on the diagnostics and haemodynamics in renal angiography.

In 20 patients referred for renal angiography, series were obtained, 30 s., 3 and 10 min. (control) after administration of 0.5 microgram of angiotensin into the selective arterial catheter. 30 s. after angiotensin there was decreased renal volume, decreased renal blood flow, unchanged arterial diameters but narrower veins. The vascular resistance was increased. The diagnostics in neoplasms and cysts were not improved. Angiotensin administration cannot replace a well performed standard renal angiography.

Angiography↗
PubMed1982

Effect of adriamycin on blood flow in renal tumour and normal renal tissue.

The effect of adriamycin (Adm) on local blood flow was simultaneously measured in neoplastic tumour, diameter 3-5 mm, and intact tissue in rat kidneys using the H2 gas washout technique. Constant rate i.v. infusion of Adm, 0.3-6 mg/kg/min for 3-15 min, increased mean arterial blood pressure (AP) by 20%, a maximum already obtained at the lower infusion rate, without affecting heart rate. Control tumour flow averaged 0.9 (0.4-1.1) ml/min/g. Flow was inversely related to Adm infusion rate in both tissues, but tumour flow tended to be relatively less affected. In another series of experiments total renal blood flow (RBF) was recorded electromagnetically during constant rate infusion of Adm into the renal blood stream, 0.03-3 mg/kg/min for 3-20 min. AP increased and RBF decreased during the first 2 min of infusion, whereafter steady levels were maintained. Both parameters returned to control levels within 4 min after completed infusion, irrespective of infusion rate and duration. High i.a. infusion rates, 2-3 mg/kg/min, almost stopped RBF but gave no further AP increase (max at approximately 0.5 mg/kg/min), indicating a direct constrictor effect on renal vessels. On the other hand, the AP response persisted when renal circulation was excluded, suggesting a general pressor response evoked by Adm. A 60% RBF reduction was obtained by 1 mg/kg/min i.a. as compared to 4-6 mg/kg/min i.v. infusions. This indicates that a several times higher Adm concentration was maintained in renal blood during i.a. infusion. Taken together with the recovery time, this observation also suggests a post-infusion blood clearance of Adm with an initial half-time of about 2 min or less. This was confirmed in additional experiments where [3H]-labelled Adm was determined in timed blood samples.

Animals↗
PubMed1982

Portohepatic bypass by splenohepatopexy in rats with prehepatic portal hypertension. A long-term (12-month) study of the development of splenohepatic collaterals and their effect on portal vein pressure.

Transposition to the liver of the spleen in rats with prehepatic portal hypertension due to a calibrated portal vein stenosis with a diameter of 1.2 mm resulted in the development of new venous collaterals from the spleen into the liver parenchyma. The collaterals were visualized macro- and microscopically as well as angiographically and were found to drain into intrahepatic branches of the portal vein, sinusoids, and hepatic veins. The portal pressure 12 months after stenosis and transposition was found to be significantly lower in rats with transposed spleens than in rats with portal vein stenosis alone. The collaterals were sufficiently well developed to significantly reduce the increase in portal vein pressure that follows acute occlusion of the portal vein and the natural splenorenal collaterals.

Animals↗
PubMed1981

Effects of vasopressin, noradrenalin and oxytocin on blood flow distribution in rat kidney with neoplasm.

The arterial blood flow distribution between tumour and intact renal tissue was investigated in rats with transplanted sarcomas. Changes in tissue flow were measured by the microsphere tracer technique, and the redistributing effects on blood flow of vasopressin, noradrenalin and oxytocin was recorded. Bolus injections of vasopressin gave a transient decrease of intact tissue flow, not found in tumours. At increasing doses of vasopressin and in early tumour growth phase, the flow discriminating effect tended to vanish. Constant intravenous infusion of vasopressin gave similar reduction of flow in tumour and intact tissue. Selective administration into the renal artery reduced flow in intact tissue but produced ambiguous effects in tumour tissue. Noradrenalin produced less reduction of tumour flow as compared with intact tissue flow. Oxytocin increased tumour blood flow while no flow change occurred in intact tissue. Oxytocin thus appeared to produce the most favourable redistribution of flow within tumour kidneys for the prospect of conveying cytotoxic agents selectively to the tumour.

Animals↗
PubMed1981

Effect of exogenous angiotensin-II on local blood flow in kidneys with neoplasm. Experiments in the rat.

The effect of angiotensin-II on the local renal blood flow and arterial blood pressure was investigated in the rat with the H2 gas washout technique. Increasing intravenous infusion rates gave a decreasing blood flow and increasing blood pressure, renal vascular resistance being close to proportional to the log of infusion rate. In kidneys with experimental neoplasm, the flow reduction was proportionally less in the tumor than in intact renal tissue. The respective flow levels were maintained for 10 to 45 min without tendency to change.

Angiotensin II↗
PubMed1980

Frontobasal skull fracture patterns.

30 cases of frontobasal skull fractures are studied. The fracture lines are registered and shown to make patterns characteristic for this type of lesion. The patterns depend on the architecture of the anterior skull fossa, deflecting the energy of the trauma.

Adolescent↗
PubMed1979

Porto-hepatic bypass by organohepatopexy in rats with prehepatic portal hypertension. Formation of new venous porto-hepatic collaterals following omento-, jejuno-, and splenohepatopexy, and their effect on portal vein pressure.

Transposition to the liver of the greater omentum; the jejunum, and the spleen in 3 groups of rats with prehepatic portal hypertension due to a calibrated portal vein stenosis with a diameter of 1.2 mm resulted in the formation of new venous collaterals from the transposed organs into the liver parenchyma. The collaterals were visualized macro- and microscopically, as well as angiographically, and were found to drain into intrahepatic branches of the portal vein, sinusoids, and hepatic veins. The portal vein pressure 8 weeks after stenosis and transposition was found to be significantly lower in rats with transposed organs than in controls. The collaterals were sufficiently well developed to significantly reduce the increase in portal vein pressure that follows acute occlusion of the portal vein and the natural splenorenal collaterals.

Animals↗