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Biomedical subjects

M Alpsten

Publications and source records attributed to M Alpsten.

At least 55 records · Page 3Linked to original sources
PubMed1984

Intratumor distribution of capillary permeability surface area product (PS) correlated to tumor vascular space and blood flow.

The intratumor distribution of the capillary permeability surface area product (PS) correlated to the intratumor distribution of vascular space and of blood flow was studied by labeled albumin in a transplantable rat fibrosarcoma. A wide heterogeneity in intratumor distribution of PS was found. The tumor PS values were not significantly correlated to tumor vascular space or to blood flow values. This might suggest that intravascularly administered drugs could reach a comparative high intratissue concentration also in less vascularized tumor areas.

Albumins↗
PubMed1983

Reduction of gastric haemorrhage by fibrinolysis inhibition - an experimental study in rats.

Gastric ulcerations were induced in rats by pyloric ligature and instillation of 1.0 N HCl. After four hours all rats had developed ulcerations. Increased release of plasminogen activators from the mucosa during these conditions has previously been demonstrated. In the present study we investigated the role of fibrinolysis inhibition versus H2-receptor blockade on the gastric bleeding. Tranexamic acid - a synthetic inhibitor of the fibrinolytic system - was found to significantly (p less than 0.01) reduce blood loss into the gastric juice by 30% measured by 51Cr labelled red blood cells; cimetidine did not reduce the gastric haemorrhage under the experimental conditions used. Both treatment regimes significantly (p less than 0.02) reduced the secretion of gastric juice. These results indicate a contribution of the fibrinolytic system in gastric bleeding from experimentally induced gastric ulcerations.

Animals↗
PubMed1982

Gastric emptying and absorption of acetylsalicylic acid administered as enteric-coated micro-granules.

Enteric-coated and uncoated microgranules of acetylsalicylic acid (ASA), labelled with 51Cr, were administered orally to six healthy male volunteers in a cross-over study. Gastric emptying was studied using a profile scanning radiation technique. Absorption of ASA was followed by measuring the plasma concentration of salicylate. Gastric emptying both of uncoated and enteric-coated granules varied considerably between individuals, but in most cases was gradual and extended over a period of several hours. The median time until 50% and 90% were emptied from the stomach was 1 and 3-3.5 h, respectively, for both the uncoated and enteric-coated granules. The absorption of ASA from the uncoated granules occurred in parallel with the gastric emptying. However, with the enteric-coated granules, absorption was delayed for about 3 h after gastric emptying. It was concluded that the slow absorption of ASA from enteric-coated granules could be explained partly by gradual gastric emptying and partly by slow dissolution of the ASA granules in the intestine.

Adult↗
PubMed1981

Influence of tranexamic acid on tumour blood flow.

The influence on the intratumour blood flow distribution in a transplantable rat sarcoma by a potent antifibrinolytic drug, tranexamic acid, administered intraperitoneally for 3 or 10 days was studied by the intratumour distribution of intravenously injected 86Rb. A local Xenon clearance technique was used to study the direct effect of tranexamic acid on local tumour blood flow. local tumour blood flow and the intratumour blood flow distribution after administration of tranexamic acid for 3 days were unchanged compared to controls. Prolonged administration of tranexamic acid changed the intratumour blood flow distribution significantly towards low flow values. This might be one mechanism behind the inhibiting effect of tranexamic acid in tumour growth rate, previously observed in both experimental and clinical studies.

Animals↗
PubMed1980

The influence of trauma, Dextran 1000, and Dextran 40 on the lodgement of circulating tumor cells.

Earlier studies have shown that trauma and infusion of Dextran 1000 increased the formation of pulmonary metastases after i.v. tumor cell injection in rats. Infusion of Dextran 40 enhanced the pulmonary metastasis formation in traumatized but not in non-traumatized animals. In this study tumor cells labelled with a radioactive isotope were used to register the lodgement circulating tumor cells after trauma and infusion of Dextran 1000 and Dextran 40. It was found that the pulmonary lodgement of tumor cells was increased after trauma and infusion of Dextran 1000. Dextran 40 did not influence the lodgement in a significant way either in normal or in traumatized animals. Thus, the increased formation of metastases after trauma and infusion of Dextran 1000 seems to depend upon an increased tumor cell lodgement.

Animals↗
PubMed1980

Studies on mechanisms involved in metastasis formation from circulating tumor cells. Factors influencing tumor cell lodgement during normal and post-traumatic conditions.

As shown in earlier studies the formation of metastases after i.v. tumor cell injection in rats is increased in the immediate post-traumatic period and treatment with heparin, thrombocytopenia, and defibrinogenation decreases the formation of metastases. Thrombocytopenia also inhibits the stimulating effect of trauma on metastasis formation. The results of the studies reported in this paper show that the changes of metastasis formation induced by the factors mentioned above with few exceptions are well correlated to the lodgement of the injected tumor cells. Thus, heparin treatment and thrombocytopenia decrease the pulmonary lodgement of i.v. injected tumor cells. Trauma increases the pulmonary lodgement of i.v. injected tumor cells but when trauma is combined with thrombocytopenia, the effect of thrombocytopenia dominates and the pulmonary lodgement of tumor cells decreases when compared to control conditions. Despite this, trauma still gives rise to increased tumor cell lodgement during thrombocytopenia.

Adenosine Diphosphate↗
PubMed1980

Intratumor distribution of blood flow and of vascular volume in a transplantable rat sarcoma.

The intratumor distribution of plasma volume and of blood flow was studied simultaneously by radioisotope techniques in a transplantable, slightly differentiated 20-methylcholanthrene-induced rat sarcoma. A significant change toward lower tumor blood flow was found in the sarcoma with increasing tumor growth, accompanied by a reduced plasma volume. The distributions of plasma volume and blood flow were similar in peripheral and central parts of tumors. However, no significant correlation between plasma volume and blood flow was found in separate tumor specimens.

Animals↗
PubMed1978

The effect of parietal cell vagotomy and selective vagotomy with pyloroplasty on gastric emptying of a solid meal. A prospective randomized study.

A new technique is described whereby gastric emptying of a 51Cr-labelled solid meal (hamburger, vegetables, potatoes) was measured by way of a movable NaJ(T1) detector. The technique allowed separate measurements over the proximal and the distal part of the stomach. Seven volunteers took part in a study which revealed good correlation between two individual consecutive tests. Eight patients who took part in a controlled randomized series of parietal cell vagotomy (PCV) versus total gastric selective vagotomy and pyloroplasty (SV+P) underwent the test preoperatively and 6 to 8 months postoperatively. Following both operations gastric emptying was retarded. The time taken for the amount of meal remaining in the stomach to be reduced to 75,50 and 25% respectively was significantly longer postoperatively than before surgery, but there were no differences in this respect between PCV and SV+P. The retardation of gastric emptying of solids was in contrast to the emptying of 10% glucose solution, which in the same series of patients was found to be accelerated. Following PCV there was a change in the distribution of the meal within the stomach immediately after the intake of the meal: a larger part of the meal was found in the proximal stomach post-operatively than before operation. There was no significant change in this intragastric distribution of the meal after SV+P.

Adult↗
PubMed1975

[Fibrinogen metabolism and distribution in tourniquet-trauma].

The distribution and turn-over of 131J-labelled fibrinogen was studied in traumatized rats. Tourniquet-trauma resulted in a pronounced accumulation of labelled fibrinogen in the traumatized region. The accumulation was at the expense of all nontraumatized-tissue. In controls there was a parallel decline of total-body-activity and plasmaactivity. The T.B.A. of traumatized animals showed a similar disapprearance-rate, while there was a pronounced reduction of circulating labelled fibrinogen.

Animals↗
PubMedDate not supplied

Dose reduction for body composition measurements with CT.

The purpose was to obtain reliable measures of fat and muscle tissue areas with CT at a reduced radiation dose level. Repeated CT-scans with four different levels of reduced radiation dose were perfomed on a water phantom and a volunteer at the L4-L5 level. Dose measurements were performed in a phantom and free in air. A histogram model function for fat, muscle and partial volume affected voxels was proposed and used in the analysis of image noise. The result was at most a 25-fold reduction in radiation dose with an image noise of 40 HU but only a minor influence on the tissue area determination [corrected].

Adult↗
PubMedDate not supplied

A comparison of different methods to measure body composition in patients.

A comparison of different methods to measure body composition in growth hormone deficient patients is presented. The technical limitations of the available methods are discussed. The techniques used to measure body composition and fat free mass has been by total body water, total body potassium, dual energy X-ray absorptiometry, bioelectrical impedance and total body nitrogen.

Absorptiometry, Photon↗
PubMedDate not supplied

Influence of a prostaglandin synthesis inhibitor and of thrombocytopenia on tumor blood flow and tumor vascular permeability. Experimental studies in the rat.

The intratumor distribution of vascular permeability in two transplantable rat tumors was studied by calculating tissue-plasma ratios of two intravenously injected labeled albumins with an interval of five hours between albumin injections. The data were calculated and presented as the capillary permeability surface area product (PS) in multiple tumor biopsies. Furthermore, the intratumor distribution of blood flow was studied by the intratumor uptake of intravenously injected 86Rb. The same parameters were also studied in normal striated muscle. Prolonged administration of a prostaglandin synthesis inhibitor, diclofenac-sodium (Voltaren) changed significantly the tumor blood flow towards higher values. A similar change was observed in animals with induced thrombocytopenia. Tumor PS values were increased by administration of diclofenac-sodium, but not by induced thrombocytopenia. The intratumor distribution of plasma volume, calculated from tissue-plasma values of albumin injected 5 minutes before the animals were killed, was not significantly changed as well as blood flow, plasma volume and PS in normal muscle. There was no significant correlation between separate tumor blood flow and PS values, while such a significant correlation was found in normal muscle. The observations made in this study suggest that a release of both prostaglandins and serotonin might be included in the regulation of tumor blood flow and vascular permeability.

Animals↗