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Biomedical subjects

S Steen

Publications and source records attributed to S Steen.

101 records · Page 6Linked to original sources
PubMed1984

beta 2 microglobulin binding activity associated with lymphocytotoxic antibodies in sera containing multiple autoantibodies.

Lymphocytotoxic antibodies (LCA) determined by complement-dependent lysis at room temperature were detected in sera containing antibodies reactive with cell nuclear (ANA) or thyroid antigens (ATA); however, the prevalence of LCA was significantly increased in sera containing both ANA and ATA. Strongly reactive LCA were only partially inhibited by beta 2-microglobulin (beta 2m) in lymphocytoxicity. Serum binding to beta 2m, determined by an enzyme-linked solid phase immunoassay (ELISA), however, was significantly increased in LCA-positive sera compared with both LCA-negative sera and normal sera; moreover, serum binding to beta 2m was significantly correlated with the frequency of LCA. There was no correlation between serum binding to beta 2m and levels of either serum immunoglobulin or serum beta 2m. These data have indicated that the prevalence of LCA in sera containing ANA was significantly associated with the separate presence of ATA suggesting some form of common escape from immunoregulation of autoimmunity; LCA activity was strongly correlated with increased serum binding to beta 2m.

Antibodies, Antinuclear↗
PubMed1984

Comparison between absorbable and nonabsorbable, monofilament sutures for end-to-end arterial anastomoses in growing pigs.

End-to-end anastomoses of the iliac arteries in growing pigs were constructed with interrupted 7-0 absorbable polydioxanone (PDS) or polypropylene (Prolene) sutures. Comparison between the two monofilament suture materials was made with respect to macroscopic and microscopic examinations, angiographic findings, recorded tensile breaking forces, and calculated blood flow values within the arterial walls at the level of the anastomoses. The angiographic examinations and the recorded tensile breaking forces did not reveal any difference between PDS- and Prolene-sutured anastomoses. On the other hand, the macroscopic findings, the histologic examination, and the calculated blood flow values (6.1 +/- 4.7 and 16.8 +/- 2.3 ml/min/100 gm for PDS- and Prolene-sutured anastomoses, respectively) point to a far more pronounced inflammatory tissue reaction with Prolene. The obtained differences clearly suggest the use of absorbable PDS instead of nonabsorbable Prolene sutures for arterial anastomoses.

Animals↗
PubMed1983

Immunological evaluation of renal transplant patients: changes in levels of beta-2-microglobulin, immunoglobulins and complement components during graft rejection.

Levels of IgG and IgM and complement components C4 and C3 were measured using rate nephelometry and serum levels of beta-2-microglobulin (beta 2m) by rocket immunoelectrophoresis (RIEP) and these assays have been applied serially following cadaveric renal transplantation on 28 patients 14 of whom were treated with cyclosporin A. There were 31 rejection episodes of which 7 were irreversible. Elevated pre-transplant serum beta 2m levels fell rapidly in the first 24-48 hr post-transplant in all patients with primary functioning grafts and the mean base-line control value was 4.5 +/- 1.27 micrograms/ml in patients with stable graft function in the period 5-10 days post-transplant. At the onset of all 31 rejection episodes however the level of beta 2m increased compared to control values and significantly exceeded the 95% confidence limits of +/- 2.0 micrograms/ml. Control values for serum IgG and IgM were significantly lower than paired pre-transplant levels and, whereas IgM increased during rejection episodes with significant differences between paired rejection and control values, no significant changes in IgG levels were detected. In contrast mean control values for C4 and C3 were not significantly different to mean pre-transplant values; however, mean levels of C4 and C3 decreased significantly during rejection episodes compared to both pre-transplant and control values.

Complement C3↗
PubMed1982

Effect of vasopressin on canine gastric mucosal circulation.

Continuous intravenous infusion of small doses of vasopressin (0.05 microgram/kg/h) in anaesthetized dogs was effective in reducing gastric mucosal flow, whereas moderate doses (0.2 micrograms/kg/h) induced a substantial flow reduction. Larger doses of vasopressin (2-4 micrograms/kg/h) precipitated massive gastric flow reduction with subsequent hyperaemia, which was not effectively controlled by moderate vasopressin doses. The effect of intraportal infusion of vasopressin on mucosal flow was similar to that of intravenous infusion. Prolonged intravenous infusion of moderate vasopressin doses maintained mucosal flow reduction over extended periods. The implications of the findings are discussed with particular reference to clinical use of vasopressin as a means of controlling bleeding from gastric mucosal lesions in patients.

Animals↗
PubMedDate not supplied

Initial tests with a new cardiac assist device.

Before, during, and after cardiac intervention, there is occasionally a need for circulatory support because of hemodynamic deterioration. For this purpose, a new minimally invasive cardiac assist device has been developed, and an early prototype has been studied in a bench test and in three pigs. The pump is a catheter system with a distal motor driven propeller (0-15,000 rpm) surrounded by a cage. The catheter was first tested in a tube in a water bath, where efficiency with respect to pressure generation and flow properties was measured. In the pig experiments, the pump was placed in the descending part of the aorta via a graft, and hemodynamic effects were recorded with three different propellers. The bench tests showed a velocity dependent pressure generation in the tube to the second power of the rpm, and 30 cm of water (> 22 mm Hg) could easily be achieved with all propellers. A pressure dependent flow in the tube was observed, with maximum flows of 20 L at 12,000 rpm and 27 L at 15,000 rpm. In the animal experiments, there was a velocity dependent mean pressure difference across the propeller, with up to 48 mm of mercury for the biggest propeller. An increase in cardiac output in all of the pigs was observed as well as a drop in pressure in the proximal part of the aorta. This study demonstrates the efficiency of this new device in vitro and in vivo. Hemodynamic changes are pronounced and are related to the speed and size of the propeller.

Animals↗
PubMedDate not supplied

A new method for autotransfusion of shed blood.

A new autotransfusion device for collection and retransfusion of whole blood is described. The construction, function and possible advantages of the system compared with currently available systems are discussed. The system is built up around a hollow fibre haemoconcentrator (dialysis filter), a cardiotomy reservoir and a large volume infusion bag. To prevent clotting, citrate (ACD-solution) is added in the suction tubing as well as locally. The blood is driven through the system by a roller pump.

Blood↗
PubMedDate not supplied

Autotransfusion of whole blood in massive bleeding. An experimental study in the pig.

An experimental model for controlled massive bleeding in pigs was developed to evaluate a new method for intraoperative autotransfusion of concentrated whole blood. The animals were injured in the descending thoracic aorta, creating a massive bleeding into the left pleural cavity. By means of a new system for autotransfusion, the animals were kept alive by retransfusing the blood at the same rate as it was shed. All animals were in good condition after autotransfusion of bleeding corresponding to three blood volumes. The postoperative hematological status including hemoglobin, hematocrit, platelet counts and electrolytes was not significantly different from the values before the experiment. The coagulation assays, including platelet adhesiveness, were normal after the experiment. In one pig the urine was positive for hemoglobin using a Hemostix test although it was macroscopically clear. This new method allows autotransfusion of whole blood with a desired hematocrit, with intact platelets and coagulation factors.

Animals↗
PubMedDate not supplied

A ruptured aortic aneurysm that "spontaneously healed".

A case of recovery after rupture of an abdominal aortic aneurysm without surgery is presented. The natural course of an abdominal aortic aneurysm is described by means of ultrasound examinations. The healing process after rupture is demonstrated with CT-scan. The question of whether all abdominal aneurysms should be resected is discussed.

Aged↗