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Biomedical subjects

B Isaksson

Publications and source records attributed to B Isaksson.

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

A study of amikacin given once versus twice daily in serious infections.

Forty-five mostly elderly patients with serious infections were treated in a prospective, comparative and randomized pharmacokinetic study with amikacin 11.0 or 15.0 mg/kg administered in a single daily dose as an intravenous, short-term infusion or with amikacin 7.5 mg/kg administered twice daily in the same way. The results indicate that administration of amikacin 15 mg/kg in a single daily dose should be a practical and safe principle of administration. However elderly patients often have reduced creatinine clearance and should preferably be given a lower dose of 11 mg/kg bw. The risk of nephrotoxicity did not increase, but conclusions on ototoxicity and clinical efficacy cannot be drawn from this limited study. This should be considered as an initial part of a future multicentre trial.

Aged↗
PubMed1988

CNS-induced natriuresis during dopamine receptor blockade. Further support for the existence of, at least, two separate natriuretic hormonal systems.

Intracerebroventricular (ICV) stimulation with hypertonic sodium chloride solutions has previously shown indications to stimulate the release of a blood-borne natriuretic factor. Sodium excretion in this situation increases in the order of 10-20 times. Acute isotonic volume expansion has shown to be a potent stimulus for endogenous release of the atrial natriuretic factor (ANF). It has also been demonstrated that the natriuretic response to both volume expansion and exogenously applied ANF can be attenuated by the dopamine receptor blocker haloperidol. The present study was performed to investigate if the natriuretic response to ICV stimulation also could be attenuated with haloperidol, thus indicating similar effector mechanisms as for ANF. A first group of anaesthetized animals was, therefore, pre-treated with haloperidol (H) and then ICV stimulated (H-ICV). A second group of animals was subjected to acute isotonic volume expansion (VE, 2% b.w.h.-1) to evoke the documented ANF release. In a third group of animals pre-treatment with haloperidol was followed by volume expansion (H-VE). In the H-ICV group there was a more than 30-fold increase in sodium excretion, due to an increase both in urine flow rate (more than sixfold) and in the urinary concentration of sodium (more than fourfold). Potassium excretion increased more than eightfold, urine osmolality was unchanged, and blood pressure increased by 7%. In the VE group sodium excretion increased more than 18-fold, consequent to large increases in urine flow rate (more than 23-fold), while the urinary concentration of sodium tended to decrease. Potassium excretion increased more than threefold, urine osmolality decreased by 88%, and blood pressure was unchanged.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Body composition in the elderly estimated with an electrical impedance method.

The purpose of the present study was to test the reliability and validity of a new electrical impedance method for estimating body composition in 35 healthy persons and patients in different sex and age groups, and to obtain basal data on the size of different body composition compartments in elderly individuals in health and disease. The reliability studies showed no significant differences with the new method in intraindividual comparisons before and after changing the positions of the electrodes, drinking of water, and overnight fasting, as well as at a double estimation on 2 consecutive days. The results with this method are compared to results from measurements of total body potassium and total body water, and from a four-compartment model technique using total body potassium and total body water. We conclude that the method has an acceptable reliability and validity and should be of great value not only in field studies but also in clinical practice. Data on body composition with the electrical impedance method are obtained from 147 individuals in different groups, namely healthy females, 80-81-year-old males, female patients from a nursing home, and patients of both sexes from a day care unit.

Adolescent↗
PubMed1986

Body composition, intraerythrocyte sodium content, volume regulation and blood pressure during moderate sodium restriction in hypertensive men.

Eleven moderately obese middle-aged male outpatients with untreated mild hypertension reduced their sodium intake by about 120 mmol per day during 4-6 weeks. Diastolic blood pressure was then significantly reduced in comparison with a matched control group. The reduction of urinary sodium excretion was significantly correlated to the change in mean arterial pressure. Mean body mass showed a small significant decrease, although there were no significant changes in total body water or body fat as determined from measurements of 40K and tritiated water. Nor did mean extracellular water or plasma volume (Evan's blue) show any significant change. The decrease in urinary sodium excretion was associated with increases in plasma renin activity and urinary aldosterone excretion, while a sympathetic nervous natriuretic index (urinary dopamine to noradrenaline excretion ratio) decreased. 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 about 8 kg. The systolic but not the diastolic blood pressure showed a significant decrease. The intraerythrocyte content of water, sodium and potassium did not change significantly during any of the diet periods. We conclude that moderate sodium restriction lowered the blood pressure and affected the renin-aldosterone and sympathetic nervous system to retain sodium which might explain the constancy of the plasma volume.

Blood Pressure↗
PubMed1986

Redistribution of glomerular filtration and renal plasma flow in CNS-induced natriuresis.

Infusion of hypertonic sodium chloride solution into the third cerebral ventricle results in a marked increase in renal sodium output, indicating an important regulator of extracellular volume homeostasis. The intrarenal events governing the enhanced excretion have not been thoroughly studied previously. In 12 anaesthetized male rats a stainless steel cannula was introduced stereotaxically into the right lateral cerebral ventricle. Urine volume and excretion rates, Na, K, and osmotically active particles were measured during control infusion of artificial cerebrospinal fluid and during stimulation of central mechanisms with I M NaCl (520 nl min-1). At the end of the stimulation period, regional renal plasma flow (86RbCl) and glomerular filtration rate (51Cr-EDTA) were measured with single injection techniques. A second group of 12 non-stimulated rats served as controls. During ICV stimulation, the urine flow rate increased from 1.8 +/- 0.19 to 6.4 +/- 1.01 microliter min-1 (P less than 0.001). The urinary concentrations of Na and K increased, leading to a rise in the excretion rates of these ions from 0.12 +/- 0.025 to 0.96 +/- 0.352 mumol min-1 (P less than 0.001) and 0.40 +/- 0.083 to 1.70 +/- 0.196 (P less than 0.001), respectively. The osmolar excretion rate was 2.9 +/- 0.35 mu Osm min-1 before stimulation and 9.6 +/- 1.09 higher (P less than 0.001) during stimulation. Simultaneously the inner medullary plasma flow rose two-fold from 0.7 +/- 0.06 to 1.4 +/- 0.12 microliter min-1 tissue (P less than 0.008).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

A multi-centre study on completeness of urine collection in 11 European centres. I. Some problems with the use of creatinine and 4-aminobenzoic acid as markers of the completeness of collection.

We have studied the completeness of urine collections in 11 European centres. The completeness of collection was examined by questioning the participants, by calculating the ratio of observed to expected creatinine, and by measuring the recovery of p-aminobenzoic acid (PABA) in the urine after administration of a 240 mg dose. The ratio of observed to expected creatinine is a fairly insensitive measure of undercollection. People who report that their collection is incomplete are likely to have collected incompletely to a considerable degree. It was concluded that the use of PABA in epidemiological studies is still questionable; overcollection cannot be detected by using PABA, and it appeared that people sometimes forget or refuse to take the capsules. It is also suggested that differences in the meal-time patterns between countries may interfere with the PABA recovery test.

4-Aminobenzoic Acid↗
PubMed1986

Whole kidney response to reduced arterial pressure during converting enzyme inhibition in the rat.

Autoregulatory efficiency of renal blood flow (RBF) and glomerular filtration rate (GFR) was evaluated in male Sprague-Dawley rats during interference with the renin-angiotensin system by a converting enzyme inhibitor (CEI), captopril (3 mg X h-1 X kg-1 BW). RBF and GFR were approximately 25 (p less than 0.01) and 20% (p less than 0.02) higher, respectively, in rats infused with CEI than in control rats at spontaneous renal arterial pressure (RAP). A reduction of RAP to 100 mm Hg (within the autoregulatory range) resulted in effective autoregulation of GFR and RBF in control rats. In rats given CEI, however, the autoregulation of GFR was markedly impaired. GFR decreased by 35% (p less than 0.001), while RBF remained relatively unchanged. This caused the filtration fraction to decrease from 0.33 +/- 0.01 to 0.29 +/- 0.01 (p less than 0.001). RAP had a consistent effect on the urine flow rate, even though both GFR and RBF were well autoregulated in control rats. No significant decrease in electrolyte excretion was detected within the autoregulatory range in control rats, but during converting enzyme blockade this excretion decreased progressively as RAP was reduced, and the decrease correlated well to the reduction in GFR. In summary, these results suggest that the renin-angiotensin system plays an important intrarenal role in the autoregulation of GFR, probably through an efferent arteriolar mechanism. Furthermore, it is demonstrated that the contralateral kidney efficiently compensates in urinary electrolyte excretion for an acute unilateral reduction of RAP.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

A multi-centre study on within-person variability in the urinary excretion of sodium, potassium, calcium, magnesium and creatinine in 8 European centres.

We have studied the within-person variability in the excretion of sodium, potassium, calcium, magnesium and creatinine in 20-60-year old men and women from 8 European centres. Only the data from people who reported that their collections were complete were entered in the analysis. The within-person coefficients of variation for the electrolytes ranged from 28 to 38 and that for creatinine from 21 to 24. The corresponding number of days required to estimate the excretion of electrolytes and creatinine to within 20 per cent of the habitual excretion (95 per cent confidence interval) varied between 4 for creatinine in men to 14 for magnesium in both men and women. The results of this study demonstrate once more that creatinine is unsuitable as a marker of completeness of urine collection for the individual.

Adult↗
PubMed1985

Nutritional status, energy and protein intake in general medical patients in three Nordic hospitals.

The energy and protein intake before and during hospitalization was studied in 56 elderly patients (age 70 +/- 9 yr) admitted to general medical service in three Nordic hospitals. Nutritional status at admission was evaluated using weight index, arm muscle circumference, triceps skinfold, serum albumin, total iron-binding capacity, haemoglobin and serum iron levels. A history of food intake before hospitalization was taken at admission. Food intake during hospital stay was estimated from precise weighing and recording and intake of energy and protein calculated. On admission, 16 patients (28.5 per cent) had three or more of the studied nutritional parameters below reference value. Mean energy intake for men at home and in hospital was 10.0 +/- 2.3 MJ/d and 7.1 +/- 1.3 MJ/d, respectively, and for women 7.8 +/- 1.7 MJ/d and 6.6 +/- 1.4 MJ/d, respectively. Mean protein intake for men at home and in hospital was 72 +/- 19 g/d and 74 +/- 15 g/d, respectively, and for women 60 +/- 15 g/d and 68 +/- 13 g/d, respectively. In patients with a hospital stay exceeding two weeks a correlation between changes in body weight and energy intake was found. Likelihood of developing undernutrition during hospitalization, defined as a daily energy intake below 90 kJ/kg BW per day, was seen in 20 patients (36 per cent). The data obtained indicate that at least 120 kJ/kg should be regarded as necessary to maintain body weight in elderly general medical patients. It reveals the importance of regular nutritional assessment of these patients.

Aged↗
PubMed1984

Blood pressure control during weight reduction in obese hypertensive men: separate effects of sodium and energy restriction.

The separate and combined effects of dietary energy and sodium restriction on regulation of blood pressure were investigated in 30 middle aged obese men with essential hypertension attending the outpatient department. In group 1 (n = 15) a basal period with no dietary restriction was followed by a period taking an energy reduced diet (5.1 MJ; 1230 kcal), the sodium intake being supplemented and hence unchanged (1:ErSn). In group 2 (n = 15) the basal period preceded a control period with no intervention, which was followed by taking a diet restricted in energy (5.1 MJ; 1220 kcal) and sodium (2:ErSr). During period 1:ErSn there were reductions in heart rate and urinary noradrenaline output but not in systolic or diastolic blood pressure. Body weight decreased by 4.9-11.7 kg and urinary sodium excretion did not change. In period 2:ErSr urinary sodium output was reduced by 81.4 (SEM 17.8) mmol(mEq)/24 h and there was a weight loss of 8.2 (SEM 0.7) kg. Systolic and diastolic blood pressures fell significantly, as did the heart rate and urinary noradrenaline excretion. These results show that in hypertensive obese men a moderate weight reducing diet decreases indices of sympathetic nervous system activity. Reduction of blood pressure to the normotensive range was observed only when there was a concomitant restriction of sodium intake.

Blood Pressure↗
PubMed1984

Effect of a moderately energy- and salt-reduced diet on body compartments and blood pressure control in obese men with mild hypertension.

Ten middle-aged moderately obese men with untreated mild hypertension were studied during a 6-week weight maintenance period and a 9-week period on a diet containing 5 MJ when body mass decreased by 8.4 kg (SE 1.4). According to urinary sodium excretion there was a mean reduction of 89 mmol/day (SE 16) in sodium intake. Mean arterial pressure fell by 2.5 to 14.1 mmHg (95% confidence interval) which was correlated to the reduction of body mass. The sympathetic nervous activity diminished with decreasing noradrenaline excretion and heart rate. There were no changes in the renin-aldosterone system. Estimation of the body composition with a four-compartment model utilizing determinations of body mass, total body potassium and total body water (TBW) showed reductions of body fat (8.4 kg (SE 1.4] and body cell mass (BCM) (2.4 kg (SE 0.6], but not of TBW. Extracellular water (ECW) increased significantly as judged from ECW/BCM calculations. Plasma volume was determined by Evan's blue and did not change significantly. We suggest that the observed changes in body composition represent one aspect of the adjustment to a weight reducing diet, while blood pressure is lowered by another mechanism in the adaptive response to dieting, i.e. reduction in sympathetic nervous activity.

Adipose Tissue↗
PubMed1984

Cytoprotective effect of 16,16-dimethyl prostaglandin (PGE2) on ischemic splanchnic injuries in the rat.

Cytoprotective effect of 16,16-dimethyl prostaglandin E2 (PGE2) was studied on splanchnic ischemia in rats. The superior mesenteric artery or the vascular pedicle to the isolated right hepatic lobe was occluded for 30 min, respectively, 1 or 2 h. Groups of rats were pretreated with PGE2 in a dose of 5 micrograms/kg b.w. 30 min before induction of ischemia. Ischemic damage was assessed by release of the lysosomal enzyme beta-glucuronidase and ALAT into circulation, the enzyme content in ischemic bowel and histology. Small bowel ischemia induced a marked enzyme release, a decrease of enzyme and protein content in the ischemic mucosa and typical histologic alterations. These findings were abolished in rats pretreated with PGE2. Occlusion of the vascular pedicle of the right hepatic lobe also caused enzyme release and histologic changes, but these were not affected by pretreatment with PGE2. PGE2 has a protective effect on small bowel ischemia and the observations support the concept that PGE2 may act by stabilization of cellular cytomembranes. No effect was observed on ischemic liver cell injury and this type of cell injury may be caused by other disturbances of cell function besides altered membrane function.

16,16-Dimethylprostaglandin E2↗
PubMed1984

Nitrogen balance studies in patients with uremia during treatment with protein-reduced diet and supplementation with essential amino acids or keto acids.

Nitrogen balance was studied in 4 patients with uremia during treatment with a protein-reduced diet (20 g) supplemented with either essential amino acids and histidine or a mixture of keto analogues of five of the essential amino acids and essential amino acids. 3 patients completed the study. Nitrogen balance was negative on the diet only and was improved with both forms of supplementation. However, supplementation with the keto acids did not offer any advantage over the conventional essential amino acid supplementation. 1 patient developed serious hypercalcemia during treatment with the keto acid supplementation.

Adult↗
PubMed1984

Acute intestinal ischemia. A 14-year retrospective investigation.

The records of 60 patients with acute intestinal ischemia treated between 1969 and 1982 were studied retrospectively. Fifty-three patients (88%) had thrombosis or embolus of the superior mesenteric artery and 7 patients (12%) occlusion of the superior mesenteric vein. Initial symptoms were obscure, although 25% presented with signs of peritonitis. The most frequently used investigation was plain abdominal X-ray with a positive finding in only 1/3. Forty-three patients (72%) were operated on. In 18 patients irreversible changes were found. Total mortality rate was 82%, in SMA-thromboembolism 85% and in SMV-thrombosis 57%. To improve the prognosis clinical awareness of the problem and attempts towards early diagnosis should be raised.

Acute Disease↗