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Biomedical subjects

O Jonsson

Publications and source records attributed to O Jonsson.

At least 55 records · Page 3Linked to original sources
PubMed1993

Altered erythrocyte transmembrane transport of sodium and potassium in patients with conventional or reservoir ileostomy.

After proctocolectomy, the loss of the colonic absorptive capacity of sodium is compensated for by increased small intestine sodium absorption and renal conservation of Na by enhanced tubular reabsorption. These processes entail increased cellular sodium transport in the enterocytes and in the renal tubular cells. In order to evaluate if there is a general increase in cellular transport of Na after proctocolectomy for inflammatory bowel diseases erythrocyte Na and K contents and the transmembrane Na fluxes were determined in 35 patients with conventional ileostomy, 23 of which were reinvestigated after conversion to continent reservoir ileostomy. A selected group of another 12 patients having high output from their reservoir ileostomy and low urinary Na were studied concomitantly and 33 healthy subjects served as controls. The intracellular Na content did not differ between the groups while the intracellular K levels were higher in patients with conventional or continent ileostomy compared to controls. In addition, the Na influx and the efflux rate constant of Na were both increased after conversion to reservoir ileostomy. Na influx correlated positively with intake and urinary excretion of Na in conventional ileostomy patients. The results suggest that patients with ileostomy have an increased cellular K uptake and that construction of a reservoir ileostomy further alters cell cation transport by increasing the transmembrane Na turnover.

Adult↗
PubMed1992

Effects of clonidine-induced hypotension and dopamine-induced hypertension on blood flows in prostatic adenocarcinoma (Dunning R3327) and normal tissues.

In the present study it was investigated whether hypertension induced by dopamine or hypotension induced by clonidine could influence the relative blood distribution in a s.c. transplanted prostatic adenocarcinoma in relation to blood flow in normal tissues in rats. The blood flow was measured by using a radioactive microspheres technique. A bolus injection of 5 micrograms clonidine caused a decrease in the systemic blood pressure with 15-45 mm Hg, and blood flow to the central parts of the tumor, decreased with more than 50%. In the prostate, testes and ileo-psoas muscle a similar reaction was seen. During an infusion of 95-120 micrograms/kg/min dopamine, the blood pressure increased with 15-30 mm Hg, but the blood flow to the tumor was unchanged. However, in the testes and kidneys a decreased blood flow was observed. Moreover, mean blood flow to the central parts of the tumor decreased with increase in tumor size. The results further indicated that hyper- or hypotension or concomitantly given vasoactive drugs with the specific cancer treatment can have unwarranted effects on the distribution of cytotoxic drugs and oxygenation of the tumor.

Adenocarcinoma↗
PubMed1992

Effect of substance P on detrusor muscle in rats with diabetic cystopathy.

Diabetic cystopathy (DCP) is a well known complication in diabetes mellitus (DM). In the present experimental study, DM was induced in rats by streptozotocin and DCP was confirmed on cystometry. In vitro studies on detrusor strips from diabetic rats showed an increased contractile response to substance P (SP) compared with controls, indicating denervation supersensitivity. A decreased response to capsaicin in diabetic detrusor strips indicated a decreased neuronal content of SP or a diminished number of SP-containing sensory nerves. This suggests that DM induces alterations in nerves containing SP which may be at least partly responsible for sensory loss and the development of DCP.

Animals↗
PubMed1992

ESR-measurement of production of oxygen radicals in vivo before and after renal ischaemia in the rabbit.

This study describes a spin trap technique to determine production of oxygen radicals in rabbit kidneys after ischaemia and reperfusion. OXANOH was infused intra-arterially. When exposed to oxygen free radicals OXANOH is oxidized to the stable radical OXANO(.). The concentration of OXANO. in samples of renal venous blood was determined by ESR. Production of oxygen radicals was calculated from the amount of OXANO. in the venous blood and the blood flow which was determined by an ultrasound technique. The radical production at reperfusion after ischaemia was expressed as a per cent of the pre-ischaemic value. A drastic increase in radical production was observed during (60 min) reperfusion after 60 min of ischaemia. Pretreatment with oxypurinol (20 mg kg-1) before ischaemia and before recirculation almost completely abolished the rise in radical production at recirculation. Similar results were obtained when oxypurinol was given before recirculation only.

Anesthesia↗
PubMed1992

Relationship between plasma growth hormone concentration and cellular sodium transport in acromegaly.

We investigated the relationship between mean plasma growth hormone (GH) concentration and cellular sodium transport in untreated and treated acromegaly. Seventeen patients (age 55 +/- 3 years) with active acromegaly were studied with respect to plasma GH (mean of 24 h GH profile) and erythrocyte electrolyte content as well as transmembrane sodium transport. The patients were reinvestigated two weeks after successful surgery (N = 14) and again after one year (N = 13). Erythrocyte electrolytes were analyzed by flame photometry and sodium influx and efflux rate constant determined by in vitro incubation using a modified Keyne's formula. In patients with active acromegaly there was a significant positive correlation between IGF-1 and cellular sodium transport, while GH tended to show a negative relationship to the same parameter. After successful treatment, both IGF-1 and GH disclosed a positive relationship to cellular sodium transport. After one year, a significant increase in erythrocyte sodium content was seen in the patients compared to the preoperative situation. In conclusion, if this is a generalized phenomenon the results are compatible with a sodium-retaining effect of GH via stimulation of transmembrane sodium transport. In active acromegaly this may be counteracted by a sodium transport inhibitor giving the reverse relationship between GH and cellular sodium transport.

Acromegaly↗
PubMed1991

Decreased absorption of 22Na and 36Cl in ileal reservoirs after exposure to urine. An experimental study in patients with continent ileal reservoirs for urinary or fecal diversion.

After urinary diversion to intestinal segments, reabsorption of chloride, ammonium, and hydrogen ions occurs, sometimes leading to hyperchloremic acidosis. The mucosa of ileal reservoirs exposed to urine show substantial atrophy, indicating a loss of absorptive capacity. In ten patients with urinary diversion via a continent ileal reservoir, the absorption of [22Na] and [36Cl] was studied after instillation for 15 min into the reservoir of a test solution containing 50 kBq [22Na] and 50 kBq [36Cl]. The activity of the radionuclides was determined in serum samples after 60 and 180 min and the fractions absorbed were calculated. Absorption of the two radionuclides was also calculated by comparison of the activities in samples of the test solution taken before and 15 min after instillation into the reservoir. The same investigations were performed in seven patients with continent ileostomy reservoirs. The study demonstrated a decreased capacity to absorb [22Na] and [36Cl] across the mucosa of the reservoirs exposed to urine compared to the mucosa of those exposed to feces. Due to the transformation of the ileal mucosa after exposure to urine, the risk for development of metabolic disturbances should be minimal after urinary diversion to a continent ileal reservoir.

Chlorine↗
PubMed1991

Blunted renal sodium excretion during acute saline loading in normotensive men with positive family histories of hypertension.

The natriuretic and intra-arterial blood pressure response to an acute saline load (1000 mL 0.9% NaCl), was studied in normotensive young men with positive (n = 11) and negative (n = 21) family histories of hypertension. The age-matched (36 +/- 5 years) control group with negative family histories of hypertension was subdivided into two groups, one matched for body mass index (BMI) to the subjects with positive family histories of hypertension (n = 10), and another lean control group (n = 11). Baseline blood pressure was significantly higher in subjects with positive family histories of hypertension and in controls matched for BMI as compared with lean controls. Sodium excretion increased in all three groups during the saline infusion, while subjects with positive family histories of hypertension disclosed a diminished natriuretic response as compared with the two control groups. Systolic blood pressure increased significantly during the saline load in subjects with positive family histories of hypertension, while in subjects with negative family histories of hypertension, no significant change in blood pressure was observed. Plasma renin activity, angiotensin II, serum aldosterone, plasma noradrenaline, blood volume, and ouabain-sensitive erythrocyte sodium efflux rate constant did not differ between the three groups at baseline. A significant negative correlation was found between baseline sodium excretion and sodium efflux rate constant in subjects with positive family histories of hypertension. We conclude that the subjects with positive family histories of hypertension exhibit a blunted natriuretic and an exaggerated blood pressure response to an acute saline load as compared with the two control groups with negative family histories of hypertension. This could be of neuronal and/or hormonal origin.

Adult↗
PubMed1991

Normotensive young men with family histories of hypertension gain weight and decrease their intraerythrocyte sodium content during a 5-year follow-up.

Young normotensive men matched for age and body mass index with (n = 16) and without (n = 13) family histories of hypertension were investigated at baseline and after 5 years of follow-up with respect to blood pressure, body weight and intracellular sodium content. Subjects with positive family histories of hypertension increased significantly in body weight (from 81.9 +/- 11.5 kg to 89.5 +/- 11.4 kg, P less than 0.001) compared to subjects with negative family histories of hypertension (from 79.9 +/- 10.8 kg to 80.7 +/- 12.2 kg, NS). Their blood pressure did not differ initially (137 +/- 12/75 +/- 11 mmHg vs. 135 +/- 8/72 +/- 9 mmHg), but was reduced in subjects without family histories of hypertension (to 125 +/- 3/68 +/- 13 mmHg) in the follow-up examination. At follow-up, body mass index showed a positive correlation with blood pressure among subjects with positive family histories of hypertension (r = 0.77, P less than 0.001). At baseline, subjects with hypertensive fathers had significantly higher intraerythrocyte sodium levels than subjects with normotensive parents. At re-examination 5 years later, this difference was no longer present. We conclude that normotensive subjects with positive family histories of hypertension are predisposed to gain weight rather than to show an increase in blood pressure at this age. Normalization of intracellular sodium content, as found in the present study, could be a consequence of this weight gain and the ensuing metabolic adaption.

Adult↗
PubMed1991

Pregnancy and delivery in patients with urinary diversion through the continent ileal reservoir.

The social and psychologic sequelae after external urinary diversion are known to be fewer in patients with urinary diversion through the continent ileal reservoir (Kock pouch) compared with those with diversion through the incontinent ileal conduit. Therefore, in young female patients treated surgically with urinary diversion through the continent ileal reservoir, a number of pregnancies can be expected. We report herein the results of four pregnancies in three women with this type of reservoir. All deliveries were vaginal. One patient showed urinary obstruction at the end of the pregnancy and delivery was induced. This particular infant was treated with phototherapy because of hyperbilirubinemia; the other three infants were mature. No damage to renal function was noted and revisional surgical treatment of the reservoir was not necessary in any. Consequently, pregnancy is not contraindicated after urinary diversion through the continent ileal reservoir (Koch pouch).

Adult↗
PubMed1990

Erythrocyte sodium transport in malignant hypertension.

Twenty-three patients with treated malignant hypertension (MH), 23 patients with treated non-malignant hypertension (NMH) and 46 normotensive control subjects were investigated with regard to intraerythrocyte sodium (Na) and potassium (K) levels, as well as transmembrane fluxes of sodium (Na-influx and Na-efflux rate constant). Intraerythrocyte Na and K concentrations were determined by flame photometry. The Na-influx and Na-efflux rate constant were calculated from uptake values for 22Na in vitro. In NMH the Na-influx and Na-efflux rate constant were significantly higher while intraerythrocyte Na and K levels did not differ from the controls. Patients with MH tended to have an elevated intraerythrocyte Na concentration, but an unchanged Na-influx and Na-efflux rate constant relative to controls. The increased rate of erythrocyte membrane transport of Na in treated NMH could be due to a stimulatory effect of antihypertensive treatment on cellular Na transport. Patients with treated MH do not show this effect, and in addition, tend to have an elevated intraerythrocyte Na concentration, which is compatible with the existence of a more pronounced abnormality of cellular ion transport in MH.

Biological Transport↗
PubMed1990

Renal function during reperfusion after warm ischaemia in rabbits: an experimental study on the possible protective effects of pretreatment with oxygen radical scavengers or lidoflazine.

Survival and renal function were studied after 60 min of renal ischaemia and contralateral nephrectomy in four groups of French loop rabbits. One group served as untreated control animals. The other groups were pretreated with superoxide dismutase (SOD) and catalase, lidoflazine or a buffered albumin solution containing mannitol, L-methionine and MgCl2. Six out of nine rabbits died during the 14-day follow-up period in the untreated control group, while the corresponding figure in each of the three treatment groups was one out of nine. Five of the rabbits that died exhibited azotaemia or hyperpotassaemia that could explain the death, while four died of non-renal related causes. In the surviving animals, no differences in serum creatinine, potassium and sodium concentration or urinary output of osmoles was observed between the four groups. The increase in serum creatinine of the French loop rabbits observed after 60 min of ischaemia was considerably less pronounced than the corresponding increase observed in New Zealand White rabbits, indicating that the kidneys of the former strain are more tolerant to ischaemia. A cardiomyodepressant factor could be demonstrated in the venous effluent from previously ischaemic kidneys. This release could not be prevented by pretreatment with SOD and catalase.

Animals↗
PubMed1990

Protective effects of pretreatment with superoxide dismutase, catalase and oxypurinol on tubular damage caused by transient ischaemia.

The effect of 60 min of ischaemia on glomerular and tubular functions (osmolar clearance, fractional Na+ excretion, K+ clearance, concentrating ability) after different periods of time was studied in New Zealand White rabbits. Pronounced changes in both glomerular and tubular functions were observed immediately on reperfusion and after 48 h. One week after ischaemia the functions appeared to be normalized. Mannitol is routinely used in clinical kidney transplantation due to its hyperosmolar effects and its ability to scavenge the hydroxyl radical. In the present study the possible additive protective effect against ischaemia-reperfusion damage of a combined pretreatment with mannitol and oxygen free radical scavengers or mannitol and a xanthine oxidase inhibitor was examined. Oxypurinol was chosen as the xanthine oxidase inhibitor due to its direct inhibitory effect. Concerning glomerular function, no protective effect of the combined pretreatment compared with mannitol alone was observed. However, concerning the tubular function tests combined pretreatment with either mannitol-superoxide dismutase-catalase or mannitol-oxypurinol turned out to be superior compared with that of mannitol alone.

Animals↗
PubMed1990

Effect of acute vascular fluid volume expansion on erythrocyte sodium transport in essential hypertension.

Evidence exists that volume expansion is associated with the appearance of a circulating sodium transport inhibitor. We have evaluated intra-arterial blood pressure (BP), central venous pressure (CVP), plasma renin activity (PRA), intraerythrocyte sodium content, erythrocyte sodium influx and rate constant of sodium efflux in 10 untreated primary hypertensive men (WHO stages I and II). The investigations were done during baseline conditions and after rapid intravenous infusion of 1 litre of saline (0.9% NaCl solution) over 15-20 min. Volume expansion caused an increase in CVP by 6.0 +/- 0.5 cmH2O (p less than 0.01), while BP only exhibited a slight increase. No significant changes in intraerythrocyte sodium content, sodium influx, sodium efflux rate constant or PRA were found after volume expansion compared to baseline. All patients with low normal PRA experienced a decrease in sodium efflux rate constant after volume expansion. We found a positive correlation between baseline PRA and change in sodium efflux rate constant after volume expansion (r = 0.62, p less than 0.05). At baseline the relationship between PRA and intraerythrocyte sodium content nearly reached statistical significance (r = 0.63, p = 0.054). These results may indicate that acute volume expansion influences the release of a circulating factor, modulating sodium transport in low-renin hypertension.

Adult↗
PubMed1990

Pharmacological interaction with quinoid antitumor drugs.

With increasing age, the incidence of neoplastic disease and the likelihood of receiving multiple prescriptions increases. Antineoplastic drugs generally have a narrow therapeutic index and are delivered at doses close to toxic. Thus, a slight increase of the biological activity caused by an interaction with simultaneously delivered drugs could be deleterious for the patient. This article summarizes the known pharmacological interactions with quinoid anticancer drugs of some during antitumor therapy commonly used drugs. The effect of antiemetics (chlorpromazine, dixyrazin, droperidol, metoclopramide), and antimicrobial agents (piperacillin, sulfamethoxazole, benzylpenicillin, amphotericin B), and adrenoceptor antagonists (propranolol, metoprolol, phentolamine) on epirubicin-induced fibroblast toxicity as studied by clonogenic survival and DNA-precipitation assay is described.

Anti-Infective Agents↗
PubMed1988

Long-term followup of maximum concentrating ability and glomerular filtration rate in adult obstructed kidneys after pyeloplasty.

We investigated 34 patients with obstructed kidneys preoperatively and 8 to 10 years postoperatively concerning the separate glomerular filtration rate and maximum concentration ability. The mean glomerular filtration rate for the obstructed kidneys was approximately 10 per cent lower compared to that for the contralateral kidneys preoperatively and at followup. Although the mean value for obstructed kidneys was not improved at followup, kidneys with a decreased glomerular filtration rate preoperatively improved significantly after pyeloplasty. The maximum concentration ability was low preoperatively for the obstructed kidneys compared to the contralateral kidneys. The lowest maximum concentration ability was found in patients with a history of repeated upper urinary tract infections. At followup marked improvement was noted, which was most obvious for kidneys with severely reduced concentration ability preoperatively. However, the restoration was not total. There was a positive correlation between the improvement in glomerular filtration rate and improvement in maximum concentration ability.

Adult↗
PubMed1988

Different patterns of cellular sodium turnover in essential hypertension.

Erythrocyte sodium turnover was studied in 22 men aged 56 years who had been treated for hypertension for 7 years. Investigations were performed during treatment, and 1 and 4 weeks after withdrawal of therapy, and when hypertension had returned (blood pressure greater than or equal to 170/105 mmHg). Hypertension returned early in 11 patients (group A) and late in 11 patients (group B). There was no difference in blood pressure, therapy, body weight or peripheral resistance between the groups, but group A had a greater left ventricular mass. Intra-erythrocyte sodium was determined by flame photometry. Sodium influx and the rate constant of sodium efflux were calculated from uptake values of 22Na. In group B the return of hypertension was accompanied by a tendency for an increase in intra-erythrocyte sodium and a decrease in sodium efflux. In group A opposing changes were seen, so that significant differences occurred in sodium efflux and intra-erythrocyte sodium between the groups occurred at the reappearance of hypertension. The results are compatible with the appearance of a membrane abnormality in patients with a slow return of hypertension, whereas other mechanisms, e.g. increased sympathetic activity, may be associated with the more rapid rise in blood pressure in the other group.

Antihypertensive Agents↗
PubMed1988

Effects of oxygen free radical scavengers, xanthine oxidase inhibition and calcium entry-blockers on leakage of albumin after ischaemia. An experimental study in rabbit kidneys.

The effect of pretreatment with various substances protecting against oxygen free radicals on the leakage of proteins across the vessel walls of rabbit kidneys induced by ischaemia has been studied. The leakage of proteins was estimated from the difference between the 120-min distribution space of [131I]albumin and the 5-min distribution space of [125I]albumin, the latter mainly measuring the intravascular volume. Neither SOD (superoxide dismutase), catalase, allopurinol or two different Ca2+ channel blockers (nifedipine, felodipine) could alone reduce the leakage induced by ischaemia. A combined pretreatment with SOD, catalase and nifedipine reduced the leakage in the cortex, and pretreatment with mannitol alone reduced the leakage in the cortex and outer stripe of the medulla. The results indicate that oxygen free radicals are involved in the leakage of proteins across the vessel walls induced by ischaemia, but that other mechanisms are involved as well.

Allopurinol↗