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Biomedical subjects

B Risberg

Publications and source records attributed to B Risberg.

At least 217 records · Page 12Linked to original sources
PubMed1986

No protection in sheep by high-dose methylprednisolone against pulmonary microvascular injury following trauma.

The osmotic reflection coefficient (sigma) of the pulmonary microvessels in sheep was estimated after a preparative trauma, and the effect of a single, high (30 mg kg -1 b.w.) dose of methylprednisolone (MP) (n = 7) compared to a dose of normal saline (S) (n = 8) was evaluated. After bilateral thoracotomies for lung lymph cannulation and placement of a balloon catheter in the left atrium, the animals were followed during anesthesia for 1 hour. Left atrial pressure (Pla) was then increased and 2 levels of filtration-independent lymph to plasma protein concentration ratio (L/P) were recorded. After the operation leukocyte and platelet counts in both groups decreased significantly. Lung lymph flow (QL) increased during the first hour without hemodynamic changes, whereas L/P decreased in the MP group but was unaffected in the S group. Partial pressure of oxygen (PaO2) was spontaneously improved postoperatively in the MP group but remained unchanged in the S group. The 2 levels of filtration-independent L/P were reached at Pla 28.7 +/- 2.8 and 34.3 +/- 1.6 mm Hg in the MP group and 25.6 +/- 2.2 and 31.3 +/- 1.3 mm Hg in the S group. QL increased by 500 +/- 80% (n = 7) and 930 +/- 210% (n = 7) at the 2 levels of increased Pla with unchanged L/P at 0.44 +/- 0.03 and 0.46 +/- 0.04, respectively, in the MP group. Corresponding values in the S group were a 590 +/- 160 (n = 5) and 730 +/- 180% (n = 3) increase in QL with L/P 0.41 +/- 0.02 and 0.40 +/- 0.03, respectively. sigma in the MP group was 0.54 +/- 0.04, and sigma in the S group was 0.62 +/- 0.02, which was not significantly different. Thus pretreatment with MP did not prevent the development of a permeability lesion following surgical pulmonary trauma, but an early minor protective effect of MP could not be ruled out.

Animals↗
PubMed1985

Modulation of tissue fibrinolysis from hypoxia and hyperoxia.

The effects from alterations in inspired oxygen tension on the fibrinolytic activity in vessel walls was studied in rats. Tissue plasminogen activator activity was measured semiquantitatively with the histochemical technique. During severe hypoxic conditions (FIO2 = 0.05) the fibrinolytic activity in the aorta was significantly reduced as compared to control animals. At 24 hours with slightly higher oxygen tension (FIO2 = 0.08) the activity was increased. When breathing pure oxygen (FIO2 = 1.0) the fibrinolytic activity was increased in the aorta after 8 hours. Following chronic hypoxia for 6 weeks (FIO2 = 0.1) the activity in the caval vein was increased. Changes in inspired oxygen tension thus affected the endothelial cells and changed their expression of plasminogen activator activity.

Animals↗
PubMed1985

Castleman's tumor with retroperitoneal location: a malignant-appearing benign tumor.

A case of a large retroperitoneal tumor in the pararenal region is presented. The tumor had an initial appearance of a malignant neoplasm both radiographically and at operation but histopathologically it turned out to be a rare benign tumor, Castleman's disease. Based on the benign nature of this lymphoid tumor extensive surgical procedures should be avoided as limited excision of the tumor appears to have been curative in all the patients reported in the literature.

Adult↗
PubMed1985

A spectrophotometric method for measuring oxygen consumption in monolayers of cultured endothelial cells.

A new method for measuring oxygen consumption in monolayer cell cultures is described. Cells are cultured in shallow microchambers etched in glass chips. A haemoglobin solution is added and the microchambers are sealed airtight, the oxygenated haemoglobin solution serving as an indicator of oxygen tension within the microchamber as well as a source of oxygen. With cellular extraction of oxygen, an increasing amount of reduced haemoglobin is formed within the microchamber resulting in an increased absorbance of the haemoglobin solution at 435 nm. With a specially prepared device, it is possible to record this absorbance change with an ordinary laboratory spectrophotometer and, from this recording, it is possible to calculate the respiratory rate, provided the number of cells (or any other quantity of biological material), microchamber volume and haemoglobin concentration are known. Repeated measurements on the same undisturbed culture is possible. The system was tested on monolayer cultures of endothelial cells from the rat pulmonary artery.

Animals↗
PubMed1985

Effects of 5-hydroxytryptamine and related agents on endothelial cell oxidative metabolism in vitro.

A recently described microrespirometric method was used to determine the influence of 5-hydroxytryptamine (5-HT), nialamide, imipramine and ouabain alone and in combinations on oxidative metabolism in monolayer cultures of endothelial cells from the rat pulmonary artery. It was found that exposure to 5-HT increased oxygen uptake in the cultures, while imipramine or ouabain decreased respiration; nialamide had no obvious effect. When used in combinations, the effect of ouabain or imipramine dominated over the 5-HT effect. The explanation for this 5-HT stimulating effect on endothelial cell oxidative metabolism, previously undescribed, is suggested to be that 5-HT exposure stimulated individual cells to contract. This active contraction resulted in an increased energy demand reflected in elevated oxygen consumption, an effect inhibited by ouabain or imipramine.

Animals↗
PubMed1985

Prevention of edema formation in the perfused lung preparation by oxygen radical scavengers.

Oxygen-derived free radicals have been implicated as mediators of pulmonary microvascular injury. In the present study we addressed the question of the role of radicals formed in the lung parenchyma in development of pulmonary edema. Rat lungs were perfused with cell-free solutions with and without addition of colloid. Edema formation was measured as dry-wet weight ratios. Edema developed following 30 min perfusion with all perfusates except nonoxygenated Dextran-Tyrode. Addition of free radical scavengers, superoxide dismutase and catalase, reduced the edema formation with the various oxygenated perfusates. We conclude that in the isolated lung perfused with oxygenated solutions oxygen-derived radicals are formed that mediate increased permeability.

Animals↗
PubMed1985

The role of high dose corticosteroids (HDC) in pulmonary capillary-alveolar membrane integrity.

Disturbed microvascular integrity is an initial event in the development of respiratory insufficiency following trauma and shock. Increased permeability in the pulmonary microvessels has been demonstrated in both experimental animals and in man. High dose corticosteroids have been used to prevent the development of the permeability lesion and to reduce it once it has occurred. Data from experimental animals are indicative of a positive effect of HDC and in patients with adult respiratory distress syndrome leakage of macromolecules over the capillary alveolar membrane was reduced significantly. Using the lung lymph fistula preparation in sheep we have demonstrated that the pulmonary microvascular sieving capacity was reduced (as indicated by a reduced osmotic reflection coefficient) following the operative trauma and manipulation of lungs necessary for cannulation of the lymphatics. We studied the effects of HDC (methyl-prednisolone 30 mg/kg) given preoperatively in 7 operated sheep and compared to 3 nonoperated controls. Permeability surface area product (PS) and osmotic reflection coefficient (sigma) for total protein were calculated by iterative curve fitting using the non-linear flux equation and data were compared to sigma achieved at maximal lymph flow following increased left atrial pressure. After surgery there were no differences between the two groups in baseline observations. In the experimental group lymph to plasma ratio for total protein (L/P) at maximal lymph flow was 0.46 +/- 0.09 corresponding to a sigma of 0.54. Maximal lymph flow was attained at microvascular pressure (Pmv) 38 +/- 2 mmHg. Calculated sigma was 0.61 +/- 0.03 and PS 0.09 +/- 0.01. Corresponding values in the control group were 0.69 +/- 0.003 and 0.1 +/- 0.0003 respectively. L/P at maximal lymph flow was 0.39 +/- 0.04 at Pmv = 35 +/- 6 mmHg in the control group. In this experiment HDC did not prevent the increase in pulmonary microvascular permeability as demonstrated after operative trauma by a decrease in the osmotic reflection coefficient for total protein. Data from patients indicate however, that HDC may have a beneficial effect on the integrity of the alveolar capillary membrane. Further studies are needed to elucidate these problems.

Animals↗
PubMed1985

High dose corticosteroids and cell-cell interactions.

Adult Respiratory Distress Syndrome (ARDS) is a feared complication of trauma or sepsis, characterized by an interstitial and alveolar edema due to increased pulmonary microvascular permeability. In ARDS polymorphonuclear granulocytes (PMN) aggregate and accumulate in the pulmonary microvessels and activation of the complement system, especially C5a, is suggested to be of importance supporting this aggregation. Such complement activated PMN can increase vascular permeability, probably by initiating endothelial cell (EC) damage. Addition of PMN and C5a to cultured EC monolayers in vitro produced both morphological and functional EC damage. A similar EC damage could be reproduced in the absence of white cells by exposing EC monolayers to oxygen free radicals induced by xanthine and xanthine oxidase or hydrogen peroxide. High dose corticosteroid (HDC) administration has been advocated in shock and ARDS and it has been experimentally demonstrated that methylprednisolone or hydrocortisone at a concentration corresponding approximately to a dose of 30 mg/kg i.v. inhibited both PMN aggregation and adhesion to the endothelium. On the other hand, no effect of HDC on PMN thromboxane synthesis or cell membrane morphology alterations was found. It has been suggested that HDC increases PMN hydrophobicity and thus reduces the tendency of the white cells to adhere to the endothelium of the microvasculature. Furthermore, it has been demonstrated that HDC can inhibit PMN production of oxygen free radicals. Platelets seem to play a role in ARDS. Serotonin released from platelets increased the cytotoxic effect of PMN on EC more than 100% in vitro, and activated PMN seemed to recruit platelets and release vasoactive substances. On the other hand, platelet serotonin enhanced the adhesion of complement stimulated PMN to EC, thus creating a vicious circle. To conclude, complement activated PMN aggregate and adhere to the pulmonary microvascular EC which are injured by e.g. PMN-generated oxygen free radicals. Platelet aggregation and release of serotonin augments this injury and activated PMN probably stimulate platelet aggregation and release. Agents capable of diminishing PMN activation and aggregation, e.g. HDC, might be of value in attenuating these cell-cell interactions in ARDS.

Adrenal Cortex Hormones↗
PubMed1984

Effect of venous stasis on vessel wall fibrinolysis.

The effects of prolonged venous stasis on release of plasminogen activators (PA) from the caval vein of rats were studied. PA activity was continuously reduced in the intimal layer and after 8 hr of stasis the reduction was statistically significant. After 2 and 3 days no intimal PA activity was found. The PA activity in the adventitial vasa vasorum was unchanged during the experimental period.

Animals↗
PubMed1984

Effects of prophylactic antibiotics in vascular surgery. A prospective, randomized, double-blind study.

In a prospective, randomized, double-blind study the effects on infection rates of a 1-day and a 3-day course of cefuroxime versus placebo were studied in patients undergoing peripheral vascular surgery. During a 30-month study period 211 patients were randomized to one of three treatment groups: Group I Placebo; Group II cefuroxime 1 day; Group III cefuroxime 3 days. Cefuroxime was administered intravenously (1.5 g every 8 hours) and the first dose was given 1 hour before surgery. Wound infection rates in the three treatment groups were: Group I 16.7%; Group II 3.8% (p less than 0.05 vs placebo); Group III 4.3% (p less than 0.05 vs placebo). One graft infection occurred in 110 patients at risk (0.9%) and this occurred in the placebo group. No allergic reactions or other side effects were noted in any of the treatment groups. No cefuroxime-resistant bacteria were found in Group II or III. In conclusion, prophylactic administration of cefuroxime during 1 day significantly reduced the incidence of infectious complications following peripheral vascular surgery. Extension of the prophylaxis beyond the day of surgery offered no additional effect. The study supports the use of short-term prophylactic antibiotics in vascular surgery.

Adult↗
PubMed1984

The uptake of 5-hydroxytryptamine in endothelial cells cultured from the pulmonary artery in rats. A cytochemical study.

Endothelial cells from the rat pulmonary artery were cultured and identified ultrastructurally and immunocytochemically by the presence of factor VIII antigens. Monolayers of cultured cells were treated according to the Hillarp-Falck technique and studied cytofluorimetrically to estimate intracellular serotonin (5-HT) levels. An uptake of 5-HT from the incubation medium was demonstrated at a concentration of 10(-3) M. However, after inhibition of monoamine oxidase (nalamide 5 X 10(-4) M) to prevent intracellular degradation of the amine an uptake could be demonstrated at 10(-5) M. The amine uptake into endothelial cells utilizes an active pumpmechanism, since it was effectively antagonized by either imipramine (10(-4) M) or ouabain (10(-5) M). These in vitro findings contrast earlier cytofluorimetric in vivo studies, where 5-HT uptake predominantly occurred in interstitial mast cells.

Animals↗
PubMed1984

Paraganglioma involving the larynx.

Paraganglioma is a rare tumor in the upper respiratory tract. More than 30 paragangliomas have been reported arising in the larynx but only a few in the trachea. The organoid arrangements of the cell nests reproduce the classic 'Zellballen' of the normal gland. Neurosecretory granules can be seen at electron microscopy. Angiography may be a valuable diagnostic adjunct. Malignant degeneration may occur. The 44-year-old woman reported had a dumbbell-shaped tumor involving the subglottic larynx but with its largest portion outside the larynx and within the left lobe of the thyroid gland. The tumor may very well have arisen from the inferior laryngeal paraganglia. An important differential diagnosis is hemangiopericytoma, which was the preoperative diagnosis in this case. A laryngectomy including the left lobe of the thyroid gland was performed and there is no sign of local recurrence or metastases 7 years after operation.

Adult↗
PubMed1984

Abdominal aortic aneurysm complicated by rectal necrosis. An unusual complication.

Spontaneous ischemic colitis is an often dramatic but common condition. Following resections of abdominal aneurysms it is not an unusual complication. Most cases will have mild symptoms. In patients with multiple arteriosclerotic disease there is an increased risk for rectal necrosis when the flow from the internal iliac arteries is impaired. We report a patient with multiple arteriosclerotic disease who developed necrosis of the left colon and rectum following occlusion of the inferior mesenteric artery.

Aged↗
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↗
PubMed1983

Origin of carcinoma in secretory endometrium--a study using a whole-organ sectioning technique.

Uteri from four patients with endometrial adenocarcinoma and concomitant "functioning" endometrium were examined by a whole-organ sectioning technique. All showed one or several "progesterone-refractory" mucosal areas or polyps, mainly in the tubal recesses. In one patient the adenocarcinoma obviously originated in a fundal polyp, and in the others the tumors could have arisen in mucosal areas not adequately responding to progesterone. These findings do not in fact contradict the "unopposed estrogen" theory of the genesis of endometrial carcinoma.

Adenocarcinoma↗
PubMed1983

Local fibrinolytic activity and its structural basis in experimental gastric ulcers.

The stomach contains plasminogen activators localized to submucosal vessels and to the mucosa. To study the release of plasminogen activators from mucosal cells, we induced mucosal damage by pyloric ligature and instillation of 0.5 mol/l HCl in rats. After 4 h, all rats developed focal necrotic lesions and a diffuse mucosal damage, as studied both by light microscopy and by scanning electron microscopy. Diffuse mucosal damage was accompanied by significant increase (P less than 0.001) in mucosal fibrinolytic activity based on plasminogen activators. This activity was probably derived from injured mucosal cells since focal necrotic lesions (erosions and ulcers) with total denudation of the mucosal epithelium lacked fibrinolytic activity. The results obtained in this study support the hypothesis that plasminogen activators are released during cellular degeneration.

Animals↗