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Biomedical subjects

O Jonsson

Publications and source records attributed to O Jonsson.

At least 73 records · Page 4Linked to original sources
PubMed1988

Effects of sodium restriction and energy reduction on erythrocyte sodium transport in obese hypertensive men.

Twelve moderately obese middle-aged male out-patients with untreated mild hypertension reduced their sodium intake by about 120 mmol/day during 4-6 weeks. The low sodium diet period was followed by a period of energy reduction as well as sodium restriction for 15 weeks. Mean body mass was then reduced by 7.5 +/- 1.0 kg. Intraerythrocyte sodium (IeNa), sodium influx (Na-influx) and sodium efflux rate constant (Na-efflux rate), were measured before intervention, during salt restriction and during salt and energy restriction. Plasma renin activity (PRA) and urinary excretion of aldosterone (U-Aldo) and noradrenaline (U-NA) were also determined during the three observation periods. During sodium restriction there was a significant increase in PRA and U-Aldo, but no change was seen in IeNa, Na-influx or Na-efflux rate constant. During sodium restriction there was a significant positive correlation between PRA and both Na-influx and Na-efflux rate constant. When energy reduction was combined with sodium restriction, PRA and U-NA both diminished significantly. Na-influx and Na-efflux rate also exhibited a significant decrease while IeNa did not change. Sodium restriction caused a significant fall in mean arterial blood pressure and a tendency to a further decrease was seen when energy intake was also reduced. No significant correlation could be found between the fall in blood pressure and changes in cellular sodium transport. These data indicate that the renin-angiotensin-aldosterone system and sympathetic activity influence the regulation of erythrocyte sodium turnover during sodium and energy restriction in obese hypertensive men.

Biological Transport↗
PubMed1987

Fibrinopeptide A and fibrinogen fragment B beta 15-42 and their relation to the operative trauma and post-operative thromboembolism in neurosurgical patients.

In an earlier study on post-operative thromboembolism in neurosurgery the incidence of deep vein thromboses (DVT) diagnosed by the fibrinogen uptake test and phlebography was reduced to the same extent by two different prophylactic methods (low dose heparin or calf muscle stimulation + dextran). However, patients with lower limb paresis due to a brain lesion experienced relatively often a less successful prophylaxis compared to patients with spinal lesions. There are few reports on successful clinical methods for haematological screening of post-operative DVT. The aim of this study was to examine possible haematological indicators for post-operative thromboembolism and secondarily to elucidate whether there exist some special coagulatory or fibrinolytic characteristics in patients who had been operated upon for brain lesions. We have studied two specific coagulatory factors (FPA reflecting thrombin generation and B beta 15-42 reflecting plasmin activity) in connection with neurosurgical operations. Patients in the above-mentioned study on post-operative DVT operated upon for malignant cerebral tumours or intracranial vascular disease exhibited post-operatively higher values for FPA compared to other neurosurgical diagnoses. B beta 15-42 was higher in the malignant tumour group and almost significantly higher in the intracranial vascular group (p less than 0.065). These differences could not be ascribed to the occurrence of DVT. Another 15 patients divided into a minor and a major lesion group were investigated with determination of both parameters pre- and post-operatively. Concerning FPA an increase was noticed post-operatively compared to pre-operatively in the major lesion group.(ABSTRACT TRUNCATED AT 250 WORDS)

Brain Diseases↗
PubMed1987

Protection of renal cells against free radical damage in vitro. A morphologic and functional study on human and rabbit kidney cells.

The morphologic and functional effects of free radicals on renal cells in vitro were investigated, as well as the possibility of avoiding them by pretreatment with scavenger enzymes or a xanthine oxidase inhibitor. Cultured human kidney cells, incubated together with a free radical-generating system, with and without protective agents, were examined by light and scanning electron microscopy. The vimentin filament structure of the incubated cells was visualized by immunofluorescence. The membrane function was studied in human kidney cells by using a dye exclusion test and in rabbit kidney slices by determination of the sodium-potassium pump activity. Exposure of the cells to free radicals caused rapid development of severe morphologic lesions, including extensive cytoskeletal disorganization. After pretreatment, only a few cells had similar, although less severe, lesions. The results of the dye exclusion test and indirect evaluation of the sodium-potassium pump activity did not indicate any major damage to the cell membranes after exposure to free radicals.

Animals↗
PubMed1987

Effects of ischaemia on leakage of albumin in rabbit kidneys.

The effect of ischaemia on the leakage of proteins across the vessel walls in rabbit kidneys was studied. The leakage of proteins was estimated from the distribution space of labelled albumin. Various methods to calculate the vascular volume yielding the true extravascular leakage were tested. The most reliable method appeared to be to use the same tracer (131I-albumin, 125I-albumin) for both estimating the leakage and the intravascular volume. One hour of ischaemia induced a drastic increase in the extravasation of proteins in the cortex and outer zone of the medulla but not in the inner zone.

Animals↗
PubMed1986

Post-operative thromboembolism in neurosurgery. A study on the prophylactic effect of calf muscle stimulation plus dextran compared to low-dose heparin.

This study compares the safety and effectiveness of two methods for the prophylaxis of post-operative thromboembolism in neurosurgical patients: A: low-dose heparin (5,000 IU X 2 s.c.) started preoperatively and continued daily for one week post-operatively, and B: per-operative electrical calf muscle stimulation with groups of impulses plus post-operative dextran infusions every other day for one week. Neurosurgical patients aged 40 years or more with normal laboratory coagulation values and operated under general anaesthesia were included. The 125:I-fibrinogen uptake test (FUT) was used for screening and phlebography for verification of deep venous thrombosis (DVT). 122 patients entered the study and 104 completed the prophylactic protocol, 58 in group A and 46 in group B. The two groups were comparable according to pre-operative data and distribution of diagnoses. 89 patients completed screening for post-operative DVT. We found an overall incidence of 5/49 (10 percent) DVT in group A and 5/40 (13 percent) in group B, compared to a frequency of 32-50 percent for controls without prophylaxis reported in the literature, In spite of prophylaxis our patients with intracranial neoplasms and intracranial vascular disease showed a relatively higher incidence of DVT, 4/23 (17 percent) and 4/14 (29 percent) respectively, compared to patients with spinal diagnoses 2/25 (8 percent). In combination with cranial diagnoses paretic lower limbs meant an apparent risk factor, 4/7 (57 percent). However, paretic limbs appearing in cases with spinal disorders did not predetermine an unsuccessful prophylaxis, 2/14 (14 percent). Blood loss, transfusion requirements and post-operative complications did not differ significantly between the two prophylactic groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Central Nervous System Diseases↗
PubMed1986

Kidney protection by pretreatment with free radical scavengers and allopurinol: renal function at recirculation after warm ischaemia in rabbits.

Renal function and morphology were studied before and after 60 min of renal ischaemia and contralateral nephrectomy in five groups of rabbits. The animals were pretreated with superoxide dismutase, catalase, allopurinol or mannitol. One group was not pretreated and served as a control. A moderate transient increase in serum creatinine concentration was observed in the control rabbits, while a significantly less pronounced increase was noted after pretreatment with superoxide dismutase, catalase and mannitol. Pretreatment with allopurinol did not significantly reduce the postoperative increase in serum creatinine and sodium excretion, but the urine osmolality returned to normal more rapidly than in the control group. The appearance under the light microscope of kidney tissue taken from surviving rabbits was found to be normal irrespective of pretreatment. Severe tubular necrosis was observed in the kidneys from rabbits that died during the observation period.

Allopurinol↗
PubMed1986

Cellular sodium turnover in obese hypertensive men.

Seventeen moderately obese middle-aged male outpatients with untreated mild hypertension (OH) and 47 normotensive men with normal weight (C) were investigated with respect to intraerythrocyte electrolytes, transmembrane sodium fluxes, PRA and urinary excretion of aldosterone (U-ALDO). There was no difference between the groups in intraerythrocyte sodium but red cell potassium was significantly elevated in OH compared to C. Sodium influx and the rate constant for sodium efflux were also significantly higher in OH. There was a significant positive correlation between sodium influx and U-ALDO (r = 0.56, p less than 0.05).

Adult↗
PubMed1986

Influence of intrapelvic pressure on excretion of sodium from human hydronephrotic kidneys.

The influence on urinary excretion of sodium (NNa . V) of intrapelvic pressure, urinary flow, and mean arterial blood pressure during forced diuresis was evaluated in 12 patients with unilateral hydronephrosis. Total and divided renal functions were measured using 51Cr-EDTA clearance and isotope renography. The amount of sodium, excreted by the obstructed kidney, decreased with higher maximum intrapelvic pressure and increased with higher differences between the mean arterial blood pressure and maximum intrapelvic pressure. The higher the concentrating ability, the lower the amount of sodium excreted by the obstructed kidney. There was a highly significant negative correlation between maximum intrapelvic pressure and urinary flow, but no correlation between mean arterial blood pressure and maximum intrapelvic pressure. Thus, obstructed kidneys with normal concentrating ability have the same excretion of sodium as the nonobstructed contralateral kidney during forced diuresis. Obstructed kidneys with decreased concentrating ability on the other hand excrete comparatively more sodium. This is probably due to a defect in sodium resorption.

Adult↗
PubMed1986

Effect of oxygen free radicals on rabbit and human erythrocytes. Studies on cellular deformability.

Changes in deformability of rabbit and human erythrocytes caused by exposure in vitro to the oxygen free radical generator hypoxanthine and xanthine oxidase were studied. The deformability reduction observed after 30 min of exposure to hypoxanthine-xanthine oxidase could be prevented by pretreatment with SOD, while after only 5 min of such exposure allopurinol and catalase also appeared to have a protective effect. Exposure of human erythrocytes to hypoxanthine and xanthine oxidase in Krebs solution prevented an otherwise occurring hemolysis. Exposure to both substances or to xanthine oxidase alone in Dulbeccos phosphate solution produced a reduction in deformability. The results indicate that exposure of erythrocytes to free oxygen radicals reduces deformability and that this effect may contribute to the myocardial dysfunction and the epicardial erythrostasis observed during open-heart surgery.

Adult↗
PubMed1986

Deformability and electrolyte changes of erythrocytes in connection with open heart surgery.

Red cell damage was studied in 16 patients undergoing open heart surgery. The damage was assessed by red cell deformability measuring red cell filtration rate (RFR) using a microfiltration technique. Simultaneous estimations of red cell sodium, potassium and water content were carried out. During and after cardiopulmonary bypass (CPB) RFR decreased with simultaneous loss of potassium and gain in sodium. These ionic changes are known to induce an increase in cellular calcium content via raised calcium influx. Since elevated intracellular calcium content provokes reduced deformability of the red cells the observed reduction in RFR in connection with CPB might at least partly be secondary to the reduction in the K+-Na+ ratio. A comparison between the regression lines between K+/Na+ and RFR for cold blood not subjected to the trauma caused by the heart-lung machine and for patient blood suggests that approximately 20% of the reduction in RFR observed in connection with CPB is due to the reduction in K+/Na+. The severity of the erythrocyte electrolyte changes was positively correlated to the amount of oxygen used in the heart-lung machine. The results suggest that the flow of oxygen and blood through the heart-lung machine should be kept as low as possible.

Aged↗
PubMed1985

Prostaglandin synthetase inhibition of renal pelvic smooth muscle in the rabbit.

The prostaglandin synthetase inhibitors diclofenac and indomethacin relieve pain in renal colic probably by decreasing renal pelvic pressure. Decreased diuresis and effects on the oedema around the obstructing stone are plausible explanations. In the present study on rabbit renal pelvic tissue strips it was found that both indomethacin and diclofenac decreased the spontaneous phasic activity of the strips. ED50 was 5.4 +/- 0.7 X 10(-5) M for indomethacin and 2.4 +/- 0.5 X 10(-5) M for diclofenac (P less than 0.001). With the prostaglandin synthetase inhibitors still in the tissue bath the activity was regained when either prostaglandin E2 or F2 alpha was added, prostaglandin E2 being more potent in this respect. It was concluded that prostaglandin synthetase inhibitors seem to reduce smooth muscle activity in the renal pelvis, a mechanism which might contribute to the pain-relieving ability of these drugs in renal colic.

Animals↗
PubMed1984

Increased erythrocyte sodium efflux during overfeeding without evidence of mediation by circulating catecholamines or thyroid hormone.

Ten slightly obese middle-aged men were instructed to increase their energy intake 25% during a period of 1 week, which was preceded by a control period of seven days. Body weight increased by 0.67 kg (SD 0.60) indicating good compliance with the regimen. Transmembrane sodium fluxes were determined with the use of 22Na. The pre-diet erythrocyte sodium content was 9.7 mmol/L (SD 0.8) decreasing to 8.9 mmol/L (SD 1.1) (P less than 0.05) during overfeeding. The Na-efflux rate constant increased from 0.40 h-1 to 0.54 h-1 (P less than 0.05). Urinary excretion of catecholamines and concentrations of catecholamines and insulin in plasma and of thyroxine, triiodothyronine, and reverse T3 in serum did not change. Thus, overfeeding seems to enhance the total Na efflux in erythrocytes from slightly obese men. There were no measurable changes in thyroid hormone or catecholamine levels leaving the regulatory mechanisms unexplained.

Adult↗
PubMed1984

Blood pressure and intra-erythrocyte sodium during normal and high salt intake in middle-aged men: relationship to family history of hypertension, and neurogenic and hormonal variables.

During 4 weeks 37 normotensive 50-year-old men identified by screening in a random population sample were given 12 g of NaCl daily, in addition to their usual dietary sodium intake. Blood pressure, heart rate, weight, urinary excretion of sodium, potassium and catecholamines, plasma aldosterone and noradrenaline and intra-erythrocyte sodium content were determined on normal and increased salt intake. The subjects were divided into those with a positive family history of hypertension (n = 11) and those without such a history (n = 26). Systolic blood pressure and weight increased significantly irrespective of a positive family history of hypertension. On normal salt intake intra-erythrocyte sodium content was significantly higher in those with a positive family history of hypertension. During high salt intake intra-erythrocyte sodium content decreased significantly in that group and the difference between the hereditary subgroups was no longer significant. In the whole group urinary excretion of noradrenaline, adrenaline and dopamine increased whereas plasma aldosterone decreased during the increased salt intake. Thus, in contrast to some earlier studies performed in young subjects, our results indicate that moderately increased sodium intake acts as a pressor agent in normotensive middle-aged men whether there was a positive family history of hypertension or not. We confirm that men with positive family history of hypertension have an increased intra-erythrocyte sodium content, and that an increase in salt intake seems to increase overall sympathetic activity.

Aldosterone↗
PubMed1984

Blood pressure, intraerythrocyte content, and transmembrane fluxes of sodium during normal and high salt intake in subjects with and without a family history of hypertension: evidence against a sodium transport inhibitor.

Seventeen young normotensive men with a family history of hypertension in two generations (H) and 15 age-matched control subjects (C) were studied with respect to blood pressure (BP), intraerythrocyte sodium content (IeNa), sodium influx, and rate of sodium efflux. The investigations were done during normal salt intake and after 4 weeks of ordinary intake plus 12 g NaCl daily. BP did not increase significantly in either of the two groups during increased salt intake. During normal salt intake H had a significantly (p less than 0.01) higher IeNa (9.5 +/- 1.5 mmol/L) compared with C (8.2 +/- 1.4 mmol/L). During high salt intake IeNa in H decreased significantly to 8.1 +/- 1.2 mmol/L, the difference from C (7.6 +/- 1.2 mmol/L) not being significant. While the Na influx was similar in the two groups, the rate constant for Na efflux was significantly lower during normal salt intake in H (0.23 +/- 0.08 vs 0.29 +/- 0.1 h-1, p less than 0.05). Salt intake increased the efflux rate constant significantly in H (0.28 +/- 0.08 h-1, p less than 0.05), while it did not change significantly in C (0.32 +/- 0.08 h-1) compared with the value for normal salt intake. Our results suggest that young men with a hereditary predisposition to hypertension have a higher IeNa secondary to a lower rate of Na efflux, while a normal Na influx indicates normal cell permeability to Na. The findings in H during high Na intake--a decreased IeNa and an increased efflux rate of Na--do not favor the existence of a sodium transport inhibitor, in subjects predisposed to hypertension, increasing during high salt intake and volume expansion and acting through inhibition of the Na efflux.

Biological Transport, Active↗
PubMed1984

Influence of anaesthesia on blood flow to the calves during surgery.

The blood flow to the calves during abdominal surgery under different kinds of general anaesthesia was measured by strain gauge plethysmography in 12 patients. The volume flow increased 100% during surgery in both light and deep anaesthesia, caused by a decrease in peripheral resistance. The increase in volume flow could partly be explained by the anaesthesia itself, possibly induced by the use of a nitrous oxide-oxygen gas mixture. The surgical procedure caused a further increase in volume flow. Possible underlying mechanisms are discussed.

Adult↗
PubMed1984

Intraerythrocyte sodium content and transmembrane sodium flux in hypertensive patients treated with diuretics or beta-adrenoceptorblockers.

Forty-seven male patients with essential hypertension were randomized to treatment with either a beta-adrenoceptorblocker (metoprolol), (n = 24), or a diuretic (hydrochlorothiazide), (n = 23). If their diastolic blood pressure was not lowered below 95 mm Hg by the maximum dose of either drug, hydralazine (15 patients) and in a few cases (6 patients) spironolactone was given. After five years of treatment all the patients were examined with respect to intraerythrocyte sodium (IeNa) and potassium (IeK), sodium influx and sodium efflux. Patients treated with the diuretic (D) tended to have a higher IeNa (9.8 +/- 0.4 mmol/l red cells) and sodium influx (0.044 +/- 0.002 mmol Na/l X min) compared with those taking the beta-adrenoceptorblocker (B) (8.9 +/- 0.3 mmol/l and 0.041 +/- 0.002 mmol Na/l X min), but neither of these differences was statistically significant. Sodium efflux, however, was significantly increased in D (0.073 +/- 0.003 mmol Na/l X min vs 0.061 +/- 0.003 mmol/l X min). No difference in IeK was noted between the two groups. Six patients taking spironolactone had a low IeNa (7.3 +/- 0.4 mmol/l), sodium influx (0.039 +/- 0.001 mmol Na/l X min) and sodium efflux (0.050 +/- 0.006 mmol Na/l X min).

Adrenergic beta-Antagonists↗