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Biomedical subjects

B Risberg

Publications and source records attributed to B Risberg.

At least 145 records · Page 8Linked to original sources
PubMed1993

Gastric mucosal microcirculation and purine nucleotide metabolism after retransfusion of rats in hemorrhagic shock.

Gastric mucosal microcirculation and purine nucleotide metabolism were studied after hemorrhagic shock and retransfusion in rats. The number of perfused microvessels and the concentration of adenosine triphosphate, adenosine monophosphate, inosine monophosphate, inosine, hypoxanthine, xanthine, and uric acid were investigated in mucosal biopsy specimens after 15 or 45 min of hemorrhagic shock and after 15 min of shock followed by 30 min of retransfusion. During shock a dephosphorylation of nucleotides and a decrease in the number of perfused microvessels occurred, the more the longer the duration of the shock period. Retransfusion led to an additional reduction in the number of perfused microvessels, but there was a partial restoration of high-energy phosphate metabolites in those areas of the mucosa which maintained a blood flow. The results indicate that there is a renewal of energy stores in gastric mucosa after hemorrhagic shock and reperfusion, although parts of the vascular bed are not reperfused.

Animals↗
PubMed1993

Erythrocyte-leukocyte interactions in the vascular bed of isolated perfused rat lungs.

An earlier study of perfused rat lungs showed that leukocytes, given as bolus injections, seemed to become more or less permanently trapped in the pulmonary microvascular bed under erythrocyte-free perfusion. The aim of the present study was, therefore, to investigate the rheologic effects of erythrocytes on the leukocyte microcirculation of perfused rat lungs. Leukocyte and erythrocyte suspensions were given as bolus injections during cell-free, constant pressure perfusion of ventilated rat lungs. Leukocyte numbers were counted in samples of the venous effluent and flow resistance changes were computed from registrations of flow rate, arterial and venous pressures. The preparations showed a continuous efflux of leukocytes which had been trapped in the pulmonary microcirculation before the perfusion was started. A bolus infusion of erythrocytes (3 ml, hematocrit: 30%) caused a transient flow resistance increase during the passage of the erythrocyte bolus through the vascular bed. This initial peak was accompanied by an increased venous efflux of leukocytes and followed by a lower second peak, attributed to a redistribution of trapped leukocytes in the capillary bed. Infusions of mixed cell suspensions (20-30 x 10(6) leukocytes in 30% hematocrit) caused a transient resistance increase similar to that caused by erythrocytes and a sustained resistance increase, less persistent than that caused by leukocytes. The present data suggest that the infusion of erythrocytes caused a re-distribution and an increased efflux of leukocytes, pooled in the pulmonary microcirculation. The rheological effects of erythrocytes could, hypothetically, result from mechanical interactions with the leukocytes in the pulmonary microvessels.

Animals↗
PubMed1992

Endometrial effects of transdermal estradiol/norethisterone acetate.

The efficacy of transdermal norethisterone acetate in sequence with transdermal estradiol has been investigated in a multicenter study of 136 post-menopausal women to determine the incidence of endometrial hyperplasia, the effects on the vaginal cytology and the control of bleeding. Treatment consisted of 12 cycles of 4 weeks each (2 weeks estradiol 50 micrograms/day followed by 2 weeks of a new combined patch delivering norethisterone acetate 0.25 mg/day and estradiol 50 micrograms/day). Endometrial histology was assessed by two pathologists. Of the 136 pre-treatment biopsies 89% provided no material, an inadequate sample or an inactive (atrophic or non-secretory) endometrium. Of the post-treatment biopsies from 110 women who completed the study: 65% showed secretory, 3% proliferative and 24% inadequate material or inactive endometrium. Hyperplasia was found in two biopsies (2%); in one of these focal atypical hyperplasia was agreed by both pathologists, in another a hyperplastic endometrial polyp was diagnosed by one pathologist. The bleeding was regular in 80% of the 1195 cycles and irregular in 11%. No bleeding occurred in 9% of the cycles. Vaginal cytology showed a significant shift towards increased maturation during treatment.

Administration, Cutaneous↗
PubMed1992

Combined angioplasty with the Kensey catheter and balloon angioplasty in occlusive arterial disease. A preliminary report.

The Kensey dynamic angioplasty catheter is an instrument for mechanical intravascular atherectomy using a rotating cam to recanalize occluded arteries. Twelve dynamic angioplasties were performed in 11 patients. The procedure was followed by an additional balloon dilatation in all cases. A technical success, i.e., a restored lumen, was recorded in 7 patients but only 4 had a functional improvement. No distal embolization or other serious complication occurred. This preliminary report shows that the therapeutic potential with this technique must be further investigated.

Adult↗
PubMed1991

Hemostatic responses to mental stress during the menstrual cycle.

To study the effect of sex hormones on the hemostatic responses to stress, blood samples were collected before, during, and after 20 min of mental stress from 9 healthy, non-smoking female volunteers, examined in the follicular and luteal phase. Mental stress caused significant increases in heart rate, blood pressure, and plasma catecholamines. In addition, analysis of variance indicated significant changes of leukocyte count, hematocrit, fibrinogen, von Willebrand factor antigen, t-PA activity and antigen in response to the stress test. However, in contrast to a male group previously investigated, there were no significant changes in factor VII coagulant activity in either menstrual phase. Overall the responses were more pronounced in the luteal as compared to the follicular phase. The findings support the concept that both gender and physiological variations in female sex hormones may modulate hemostatic responses to psychosocial stress.

Adult↗
PubMed1991

Regional fibrinolysis following total hip replacement.

The local effect of operative trauma on the fibrinolytic system was studied in ten patients undergoing total hip replacement. Catheters were inserted in the femoral veins on both sides and blood was sampled from these catheters perioperatively. The following fibrinolytic variables were analysed in plasma and related to the different steps of surgery: tissue plasminogen activator (t-PA) activity, t-PA antigen and plasminogen activator inhibitor (PAI-1) activity. During surgery PAI-1 activity and t-PA antigen in the operated limb were significantly increased compared with preoperative values. There was a significant difference in PAI-1 activity and t-PA antigen between the operated and the non-operated limbs during surgery and within one hour postoperatively. During fixation of the femoral implant there was a significant difference between the operated and the non-operated limbs in t-PA activity. Thus the regional fibrinolytic response to trauma was dissociated from the response in the non-operated limb. The clinical relevance of the observed alterations in regional fibrinolysis, as related to thrombogenic mechanisms after hip surgery, remains to be elucidated.

Aged↗
PubMed1991

Impaired fibrinolysis and postoperative thromboembolism in orthopedic patients.

The incidence of deep vein thrombosis (DVT) and pulmonary embolism was studied prospectively in patients undergoing elective total hip replacement. 96 patients were randomly allocated to receive either low molecular weight heparin (LMWH) or unfractionated heparin (UFH). All patients had bilateral phlebography and pulmonary perfusion/ventilation scintigraphy 10-12 days after surgery. The following fibrinolytic variables were analysed in plasma and related to thromboembolism: tissue plasminogen activator (t-PA) activity, t-PA antigen (t-PA Ag), plasminogen activator inhibitor (PAI-1) activity and PAI-1 antigen (PAI-1 Ag). No significant difference was found, regarding the fibrinolytic response to surgery, between patients treated with LMWH and UFH. The level of PAI-1 activity was significantly increased before operation in patients developing DVT as compared to non-DVT patients (p less than 0.03). Immediately after surgery and in the morning the first postoperative day the levels of PAI-1 activity, PAI-1 Ag and t-PA Ag were positively correlated to thromboembolism. PAI-1 activity was the only preoperative fibrinolytic variable correlated to thromboembolism.

Aged↗
PubMed1991

Disseminated intravascular coagulation.

This review encompasses a description of the main pathophysiological events leading to disseminated intravascular coagulation (DIC). Emphasis has been put on microcirculatory disturbances and endothelial dysfunction. The normal hemostatic functions of the vascular endothelium are described. The close connection between endothelium and superimposed immuno-modulators is stressed as is the interrelation between the proteolytic cascade systems in the blood. The importance of differentiating local and systemic events is discussed. Organ dysfunction in multiple organ failure (MOF) is exemplified by pulmonary insufficiency in the adult respiratory distress syndrome (ARDS). Essential laboratory tests of DIC are described as are the cornerstones of treatment.

Disseminated Intravascular Coagulation↗
PubMed1991

Oxygen radicals and lung injury.

This article describes the formation of oxygen radicals and their biological effects, especially in relation to lung injury. Various recent experimental data are reviewed. The relationships between hydrostatic effects and permeability effects in producing injury and edema are stressed. Means of prevention and problems related to extrapolation to clinical situations are focused.

Animals↗
PubMed1991

Changes in gastric mucosal microcirculation and purine nucleotide metabolism during hemorrhagic shock in rats.

Intravital fluorescence microscopy and morphometry were used to study the microcirculation in the rat gastric mucosa during and after hemorrhagic shock. Under control conditions the circulation appeared homogeneous and unaffected by superfusion with 0.1 N HCl. During hemorrhagic shock, scattered areas of the mucosa lost circulation. Morphometry showed that the number of perfused mucosal vessels decreased significantly in the abluminal part of the mucosa both in perfused and ischemic areas, the reduction being most pronounced in the ischemic areas, where the number of perfused luminal vessels also decreased significantly. During reperfusion, bleedings occurred from the mucosa. A key finding was that the bleedings always had their origin at the border zone between ischemic and perfused areas. After hemorrhagic shock adenosine triphosphate and energy charge levels dropped significantly in both perfused and ischemic areas but with significantly lower levels in the ischemic areas. The hypoxanthine levels increased in both perfused and ischemic areas. The experiments show that local mucosal ischemia and accelerated nucleotide degradation are of pathogenetic importance in the development of stress ulcers after hemorrhagic shock. The border zone between circulated and ischemic areas seems to be an area of special interest.

Animals↗
PubMed1991

Prevention of deep-vein thrombosis and pulmonary embolism after total hip replacement. Comparison of low-molecular-weight heparin and unfractionated heparin.

In a prospective, randomized, double-blind study, the efficacy and safety of a low-molecular-weight heparin were compared with those of unfractionated sodium heparin (standard heparin) in 136 patients who had elective total hip replacement. The patients received subcutaneous injection of either 5000 international units of low-molecular-weight heparin once daily or 5000 international units of standard heparin three times a day. Treatment with low-molecular-weight heparin began twelve hours before the operation, and treatment with standard heparin began two hours preoperatively; both regimens were continued for ten days. Twelve days postoperatively, bilateral ascending phlebography was performed in 122 patients, sixty-three in the treatment group that received low-molecular-weight heparin and fifty-nine in the treatment group that received standard heparin. Pulmonary scintigraphy was performed in 127 patients. Deep-vein thrombosis was diagnosed in forty-four patients: nineteen (30 per cent) of the sixty-three who received low-molecular-weight heparin and twenty-five (42 per cent) of the fifty-nine who received standard heparin. All but four patients, two from each treatment group, were asymptomatic. The difference in the total rate of thrombosis in the two groups was not significant (p = 0.189). However, thrombosis occurred in the thigh in only six (10 per cent) of the patients who received low-molecular-weight heparin but in eighteen (31 per cent) of those who received standard heparin, a significant difference (p = 0.011). Pulmonary embolism was detected in twenty-seven patients: eight (12.3 per cent) of those who received low-molecular-weight heparin and nineteen (30.6 per cent) of those who received standard heparin. Only three patients had clinical signs of embolism. Pulmonary embolism was significantly more frequent in the group that received standard heparin (p = 0.016). Total loss of blood and the total amount of blood that was transfused were significantly reduced in the patients who received low-molecular-weight heparin compared with those who received standard heparin. Prophylaxis was not discontinued because of hemorrhage in any patient. The efficacy of low-molecular-weight heparin was superior to that of standard heparin in the prevention of femoral thrombosis and pulmonary embolism, although the over-all incidence of deep-vein thrombosis was not statistically different.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1990

Lipoprotein (a) and coronary heart disease: a prospective case-control study in a general population sample of middle aged men.

OBJECTIVE: To examine the association between the serum lipoprotein (a) concentration and subsequent coronary heart disease. DESIGN: Prospective case-control study based on a six year follow up of a general population sample of men aged 50 at baseline in 1983-4. Serum samples were frozen at the time of the baseline examination and kept at -70 degrees C for six years, after which the lipoprotein (a) concentrations in the samples were measured in cases and controls. SETTING: City of Gothenburg, Sweden. SUBJECTS: 26 Men, from a general population sample of 776 men, who had sustained a myocardial infarction or died of coronary heart disease during the six years and 109 randomly selected controls from the same sample who had remained free of myocardial infarction. In neither cases nor controls was there a history of myocardial infarction at baseline. MAIN OUTCOME MEASURES: Proportion of myocardial infarction or deaths from coronary heart disease, or both, in relation to the serum lipoprotein (a) concentration. RESULTS: Men who suffered coronary heart disease had significantly higher serum lipoprotein (a) concentrations than controls (mean difference 105 mg/l; 95% confidence interval 18 to 192 mg/l). Men with the highest fifth of serum lipoprotein (a) concentrations (cut off point 365 mg/l) suffered a coronary heart disease rate which was more than twice that of men with the lowest four fifths of concentrations. Logistic regression analysis showed the serum lipoprotein (a) concentration to be significantly associated with coronary heart disease independently of other risk factors. CONCLUSION: The serum lipoprotein (a) concentration in middle aged men is an independent risk factor for subsequent myocardial infarction or death from coronary heart disease.

Case-Control Studies↗
PubMed1990

Abdominal obesity is associated with an impaired fibrinolytic activity and elevated plasminogen activator inhibitor-1.

Recent epidemiologic studies have shown that abdominal obesity, characterized by a high waist to hip circumference ratio (WHR), is associated with increased cardiovascular morbidity and mortality. The present study examines components of the fibrinolytic system in obese and lean middle-aged women with a high and low WHR. Ten women in each group were carefully matched with respect to age, body weight, lean body mass, and body fat. Fibrinogen and endothelial type of plasminogen activator inhibitor -1 (PAI-1) were significantly elevated in the obese women with a high WHR compared with the obese women with a low WHR or with both groups of lean women. In addition, obese women with a high WHR exhibited a greater metabolic risk profile (elevated glucose, insulin, and triglyceride levels). When all subjects were pooled for the analyses, both fibrinogen and PAI-1 levels correlated positively with glucose and insulin levels. PAI-1 was also negatively related to degree of insulin sensitivity measured with the euglycemic clamp technique. In the obese groups, WHR but not body mass index (BMI), correlated with PAI-1 levels. No such correlations were seen in the lean groups. In conclusion, the data show that a high WHR in obese, but not lean middle-aged women, is associated with an impaired fibrinolytic activity. This perturbation becomes enhanced when it is associated with hyperinsulinemia and insulin resistance, which is a typical feature of abdominal obesity.

Cardiovascular Diseases↗
PubMed1990

DNA ploidy, morphometry, and nuclear grade as prognostic factors in endometrial carcinoma.

In a retrospective analysis of 106 cases of endometrial carcinoma stages I-IV (FIGO), the prognostic value of DNA ploidy and nuclear morphometry of tumor cells was evaluated and compared with that of conventional clinical and histopathologic parameters. Paraffin-embedded tumor tissue from the original curettage specimens was used. A flow cytometric technique was employed to distinguish diploid from aneuploid tumors. It was not possible to estimate S-phase rates by this method. Eight different nucleus-related morphometric parameters were computed from representative tumor regions on the original slides. All histologic specimens were reviewed by on the pathologist and graded according to FIGO; nuclear grade was determined separately. Tumor stage, depth of myometrial infiltration, and nuclear grade were the most important prognostic factors with regard to tumor-related survival. DNA ploidy and nuclear morphometry did not add significant prognostic information that could be used to distinguish high-risk and low-risk populations with endometrial carcinomas. The simple nuclear grading system should be further evaluated in prospective studies and compared with DNA analysis and nuclear morphometry performed on fresh-frozen tissue.

Adult↗
PubMed1990

Venous endoscopy in thrombectomy of the iliac veins using the choledochoscope.

In the present communication venoscopy using a flexible choledochoscope is advocated after thrombectomy of the iliac veins. In 10 patients operated upon for occlusive thrombi in the pelvic veins, venoscopy was used to assess the status of the vein. The procedure was conveniently performed using a regular flexible choledochoscope. Venoscopy gave detailed information of the veins and lead to altered therapy in seven of the 10 patients. Venoscopy is recommended for intra-operative control during surgical thrombectomy and the use of a choledochoscope can simplify this procedure.

Endoscopes↗
PubMed1990

Endothelial cell seeding reduces thrombogenicity of Dacron grafts in humans.

Vascular prostheses in humans do not endothelialize spontaneously. In the present study we explored the feasibility of seeding autologous endothelial cells into prostheses implanted in patients undergoing reconstruction of the infrarenal aorta. In 22 patients one limb of an aortic Dacron bifurcation prosthesis was seeded with autologous endothelial cells harvested from the distal portion of the saphenous vein. The other limb was sham-seeded with culture medium only. The effect of seeding was studied by use of indium 111 radiolabeled platelets and external gamma camera scanning at 1, 4, and 12 months after surgery. No complications ascribable to the seeding procedure were seen. During the first year after surgery a gradual decrease in platelet accumulation occurred over the whole vascular prosthesis. At all time points studied the seeded graft limbs exhibited significantly less deposition of radiolabeled platelets than did control limbs. The observed difference in platelet accumulation on autologous endothelial seeding-treated graft segments merits further investigation of this technique in humans.

Aged↗