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Biomedical subjects

B Berglund

Publications and source records attributed to B Berglund.

At least 73 records · Page 4Linked to original sources
PubMed1992

Environmentally induced changes in sensory sensitivities.

For studying changes in the sensory sensitivities, psychophysical methods offer a variety of models. The psychophysical approach also holds for applications on indoor air quality. The human senses can be used for characterizing environments in terms of effects on health and comfort, and have been used by the WHO for determining recommended exposure limits. The use of psychophysical methods for air pollution applications is illustrated by two studies on effects on sensory functions in smokers and passive smokers. Olfactory as well as auditory effects were found. Furthermore, methodological findings are presented, such as obtaining information on detectability and perceived intensity in the very same estimation procedure. The results also demonstrate the need for calibrating scales with regard to individual scaling behavior in perceived intensity measurements as well as the capability of the master scale principle for performing such a calibration.

Air Pollution, Indoor↗
PubMed1992

Ileostomy output of gas and feces before and after conversion from conventional to reservoir ileostomy.

In 28 patients who had previously had a proctocolectomy for ulcerative colitis, the ileostomy output of feces was determined before and after conversion to continent reservoir ileostomy, as was the output of gas in 20 of the patients. The median output of feces/24 hours collected in the hospital was 576 g before and 692 g after conversion (P less than 0.05); when collected at home the corresponding figures were 734 g and 740 g, respectively. In the majority of patients, the change in fecal ileostomy output after the conversion was not considerable, while in a few patients there was a marked increase. The fecal output was 24 percent (P less than 0.01) and 11 percent (P less than 0.01) larger at home than in hospital before and after conversion, respectively. The proportion dry weight of ileostomy discharge decreased after conversion (P less than 0.01). The median gas volume in the ileostomy output/24 hours was 1,664 ml before and 1,450 ml after conversion. The gas constituted 58 percent of the output and is significant with respect to the required reservoir capacity. Recording the emptying volumes and frequency in patients with reservoir ileostomy showed that, in general, patients with large output expand their reservoir capacity instead of increasing their emptying frequency.

Adult↗
PubMed1992

Myocardial lactate extraction and release at rest and during heavy exercise in healthy men.

The relationship between myocardial lactate extraction and blood lactate concentration and the possibility that simultaneous uptake and release of lactate occur in the normal human heart was investigated by measuring arterial-coronary sinus differences of lactate and of labelled lactate during infusion of 14C lactate in 13 healthy young male volunteers. Measurements were done at rest, during increased cardiac work with unaltered arterial lactate concentration achieved by atrial pacing and during increased cardiac work and increased arterial lactate concentration achieved by supine cycle ergometer exercise. There was on no occasion a significant difference in 14C lactate specific activity between arterial and coronary sinus blood, i.e. no significant admixture of non-labelled lactate occurred in the coronary sinus indicating that on no occasion was there any sign of lactate release. The myocardial extraction of lactate seemed to be a linear function of arterial lactate concentration. During exercise with an arterial lactate concentration of 6 mmol l-1 and above, lactate could have covered approximately 75-100% of the oxidative metabolism. Thus, during short-term heavy work myocardial lactate extraction dominates over other substrates (mainly free fatty acids and glucose) taken up by the heart, and used for oxidation by the heart muscle cells.

Adult↗
PubMed1992

High-altitude training. Aspects of haematological adaptation.

Physical training at high altitude improves performance at high altitude. However, studies assessing performance improvements at sea level after training at higher altitudes have produced ambiguous and inconclusive results. Hypoxia-induced secondary polycythemia is a major contributor to increased work capacity at altitude. The common finding upon exposure to hypoxia is a transient increase in haemoglobin concentration and haematocrit because of a rapid decrease in plasma volume followed by an increase in erythropoiesis per se. Both nonathletes and elite endurance athletes have maximal reticulocytosis after about 8 to 10 days at moderate altitude. Training periods of 3 weeks at moderate altitudes result in individual increase of haemoglobin concentration of about 1 to 4%. A more accentuated increase in haemoglobin can be obtained with longer sojourns at moderate altitude. The normal erythropoietin reaction upon exposure to hypoxia comprises initially increased levels followed by a decrease after about 1 week. Thus, the maintenance of a high erythropoietin concentration is not a prerequisite for a sustained increase in erythrocyte formation at high altitude. The main pharmacological modulator of erythropoietin production seems to be adenosine. But modulators such as growth hormone and catecholamines may also potentiate the effect of hypoxia per se on erythropoietin production. On the other hand, there is a risk that the stress hormones may induce a relative depression of the bone marrow particularly in the early phase of altitude training when the adaptation is minimal and the stress reaction is most accentuated. The most important 'erythropoiesis-specific' nutrition factor is iron availability which can modulate erythropoiesis over a wide range in humans. Adequate iron stores are a necessity for haematological adaptation to hypoxia. However, at moderate altitude, there is a need for rapid mobilisation of iron and even if the stores are normal there is a risk that they cannot be mobilised fast enough for an optimal synthesis of haemoglobin. Data from healthy athletes training at moderate altitudes suggest a true increase in haemoglobin concentration of about 1% per week. Complete haematological adaptation occurred when sea level residents have similar haemoglobin concentrations at moderate altitude compared with residents. The normal difference in haemoglobin concentrations can be estimated to be about 12% between permanent residents at sea level and at 2500m above sea level. This difference indicates a necessary adaptation time of about 12 weeks. If the training period at moderate altitude must be shorter, several sojourns at short intervals are recommended. The important factor in haematological adaptation in athletes at moderate altitude is hypoxia.(ABSTRACT TRUNCATED AT 400 WORDS)

Acclimatization↗
PubMed1992

Significance of the antireflux valve for upper urinary tract pressure. An experimental study in patients with urinary diversion via a continent ileal reservoir.

When bladder substitution is required, a low pressure receptacle and an antireflux valve with low resistance to flow is essential for preservation of the upper urinary tract. The aim of this study was to evaluate whether these criteria are attained in the continent ileal reservoir used for urinary diversion. The investigations were performed in six patients more than one year after supravesical urinary diversion via a continent ileal reservoir. The pressure was recorded simultaneously both in the afferent loop and in the reservoir during filling of the reservoir. There was a slow parallel increase in the basal pressure in the reservoir and the afferent loop. Pressure waves appeared sometimes simultaneously and sometimes in only one compartment at a time. Only during short periods of time did the pressure exceed 25 cm of water. The frequency of pressure waves increased with increased filling of the reservoir. The "total pressure" was larger in the reservoir than in the afferent loop. It is the antireflux valve which prevents pressure rises in the reservoir from being conveyed to the upper urinary tract. The resistance to urinary flow was moderate.

Humans↗
PubMed1991

Effect of recombinant human erythropoietin treatment on blood pressure and some haematological parameters in healthy men.

The aim of this study was to evaluate the effect of treatment with subcutaneous injections of recombinant human erythropoietin (rhEpo), 20-40 IU kg-1 body weight, 3 times a week, on resting blood pressure, blood pressure response during submaximal exercise, some haematological parameters, and subjective side-effects in 15 healthy male subjects. RhEpo increased both haemoglobin (Hb) concentration and haematocrit (Hct) significantly, the values for Hb being 152 +/- 4.2 g l-1 before treatment and 169 +/- 9.3 g l-1 (mean values +/- SD) after 6 weeks of rhEpo treatment (P less than 0.001). The corresponding values for Hct were 44.5 +/- 1.5% and 49.7 +/- 1.9% (P less than 0.001), respectively. The systolic and diastolic blood pressure values at rest were unchanged after rhEpo treatment. A marked increase in systolic blood pressure was observed during submaximal exercise at 200 W, the initial and final values being 177 +/- 14.2 mmHg and 191 +/- 19.5 mmHg (P less than 0.01), respectively. Heart rate during exercise at 200 W was significantly lower after rhEpo treatment than before it: 144 +/- 15 beats min-1 compared to 136 +/- 8 beats min-1 (P less than 0.001). The leucocyte count remained unchanged after rhEpo treatment, but there was a significant decrease (P less than 0.05) in the number of lymphocytes. Reticulocyte and platelet counts were unchanged. Serum (S) ferritin decreased from 87.3 +/- 41.8 mmol l-1 to 59.3 +/- 27.8 mmol l-1 after rhEpo treatment (P less than 0.001). Serum-Na, S-K, S-Ca, S-creatinine, S-bilirubin, S-aspartate aminotransferase (ASAT), S-alanine aminotransferase (ALAT), and S-lactate dehydrogenase (LD) were unchanged after rhEpo treatment. No subjective side-effects were reported. In conclusion, low doses of rhEpo increased Hb levels and Hct by more than 10% after 6 weeks. Blood pressure at rest was unchanged, but rhEpo induced a markedly accentuated blood pressure reaction during exercise. A minor decrease in the lymphocyte count was observed, but electrolyte and creatinine levels remained unchanged after rhEpo treatment.

Adult↗
PubMed1991

Intensified conventional insulin treatment retards the microvascular complications of insulin-dependent diabetes mellitus (IDDM): the Stockholm Diabetes Intervention Study (SDIS) after 5 years.

Ninety-six patients with insulin-dependent diabetes mellitus (IDDM) and non-proliferative retinopathy were randomized to intensified conventional treatment (ICT) (n = 44) or regular treatment (RT) (n = 52), and followed up for 5 years. HbA1c decreased from 9.5 +/- 0.2% (mean value +/- SEM) to 7.2 +/- 0.1% in the ICT group, and from 9.4 +/- 0.2% to 8.7 +/- 0.1% in the RT group (difference between the groups, P less than 0.001). Retinopathy increased in both groups (P less than 0.001), but after 5 years it was worse in the RT group (P less than 0.05). The urinary albumin excretion rate was higher in the RT group than in the ICT group after 5 years (239.9 +/- 129.7 micrograms min-1 vs. 46.0 +/- 26.1 micrograms min-1, P less than 0.05). Eight RT patients developed manifest nephropathy, compared with none in the ICT group (P less than 0.01). After 5 years the conduction velocities of the sural (P less than 0.05), peroneal (P less than 0.01) and tibial (P less than 0.001) nerves were lower in the RT group. The respiratory sinus arrhythmia was 12.1 +/- 1.2 beats min-1 in the RT group and 16.7 +/- 1.4 beats min-1 in the ICT group at the end of the study (P less than 0.01). The increases in retinopathy (P less than 0.01), nephropathy (P less than 0.01) and neuropathy (P less than 0.001) were all related to the mean HbA1c value during the study. Smoking habits only influenced the progression of retinopathy (P less than 0.05). Serious hypoglycaemia occurred in 34 ICT patients and 29 RT patients (242 and 98 episodes, respectively) (P less than 0.05). Whereas weight was stable in the RT group, the body mass index increased by 5.8% in the ICT group (P less than 0.01). In conclusion, microvascular complications of diabetes were retarded by intensified conventional insulin treatment. However, such treatment increased the frequency of serious hypoglycaemia, and led to an increase in body weight.

Adult↗
PubMed1991

Effect of coronary bypass surgery on anaerobic myocardial lactate metabolism during pacing-induced angina pectoris.

Myocardial lactate metabolism was studied by coronary sinus catheterization in nine patients before and 8-12 months after coronary bypass surgery. Measurements were performed at rest and during atrial pacing increased to a heart rate which produced strong chest pain. The estimation of myocardial lactate extraction and release was facilitated by a constant rate infusion of 14C lactate and coronary sinus blood flow (CSBF) was measured by thermodilution. Pre-operatively strong chest pain could be elicited in all patients and isotope data indicated a significant myocardial lactate release in all of them, although the net a-cs difference was negative in only half of them. After bypass surgery the maximum tolerable heart rate was increased by 23 beats min-1 and chest pain both at heart rate 110 beats min-1 and at the highest heart rate achieved was reduced or absent in eight of the nine patients. The increase in chest pain during pacing was quantitatively related to the increase in myocardial lactate release, and the correlation between these two variables followed the same course after the operation as it did before. It is concluded that the improvement in chest pain limited cardiac performance after bypass surgery is well correlated with the improvement in myocardial aerobic metabolism.

Aged↗
PubMed1991

Myocardial blood flow and lactate metabolism at rest and during exercise with reduced arterial oxygen content.

The effect of a reduction in arterial oxygen content, equivalent to acute exposure to an altitude of 2300 metres above sea level, on myocardial blood flow and oxygen and lactate exchange was studied by coronary sinus catheterization in 12 healthy men. Measurements were made at rest, during atrial pacing and during submaximal and maximal exercise both breathing air and breathing 15% oxygen (hypoxia). Coronary sinus blood flow was measured by thermodilution and the possibility of a simultaneous uptake and release of lactate by the heart was calculated using intravenous infusion of 14C lactate. At all levels of cardiac power output myocardial oxygen consumption was the same during hypoxia as during air breathing. At rest this was achieved entirely by a more complete extraction of oxygen from the coronary blood, during maximal exercise entirely by a greater coronary sinus blood flow, while at intermediate levels of cardiac power output a combination of these mechanisms prevailed. At rest and during submaximal work myocardial lactate extraction was lower with hypoxia than air breathing suggesting a change in myocardial redox state, while the 14C lactate data suggested no significant lactate release or possibly limited areas with some lactate production. During maximal exercise, however, there was no difference in myocardial lactate net extraction between hypoxia and air breathing, which together with the greater blood flow suggests that the heart has a 'coronary flow reserve' permitting maximal exercise at moderate altitude without anaerobic myocardial metabolism.

Adult↗
PubMed1991

Stimulus sequence and the exponent of the power function for loudness.

In two experiments, 15 and 13 subjects estimated the loudness of 12 sound-pressure levels (38-104 dB; 6-dB intervals) of a 1000-Hz tone by the method of magnitude estimation with a modulus assigned to the first stimulus presented. The tone duration was 1 sec. and the interstimulus interval was 6 sec. The presentation order was systematically ascending-descending in one experiment and balanced-irregular in the other. The results indicate that (1) loudness is a power function of sound pressure with an exponent of 0.60 for the systematic order and 0.29 for the irregular order. (2) For both the irregular and systematic orders, a large step-size (12 or 18 dB) between the stimulus on Trial n and on Trial n-1 (or n-3) results in a slight assimilation effect. This also occurs for the small step-size (6 dB) in the irregular order. (3) The size of momentary exponents (based on two points, Trials n and n-1 or n-3) depends on the sound pressures of successive stimuli, whether the steps are positive or negative, and whether the stimuli have been presented in systematic or irregular order. For positive steps, the momentary exponent is lower for a soft tone (Trial n) than for a loud tone, whereas for negative steps the momentary exponent is lower for a loud tone than for a soft tone. These effects ar more pronounced when these stimuli are presented in an irregular order. A relative judgment model is offered for magnitude estimation. It assumes that subjects judge the loudness of a stimulus in terms of three reference markers: the minimum and maximum sound pressures as well as the sound pressure of the previous stimulus.

Adult↗
PubMed1991

Inhibition of gastrin release induced by fundic distension. Evidence of a defective inhibition in duodenal ulcer patients.

The serum gastrin response to an infusion of gastrin-releasing peptide (GRP), with or without simultaneous fundic distension, was studied in healthy volunteers and in patients with duodenal ulcer disease before and after a complete proximal gastric vagotomy (PGV). We also studied the effect of fundic distension alone on gastrin release and intraluminal gastric pressure in healthy volunteers and in patients after PGV. We observed an increased intraluminal pressure in patients after PGV compared with healthy subjects. During fundic distension with 600 ml of air no significant increase in gastrin values was observed in healthy subjects or in duodenal ulcer patients. In healthy subjects fundic distension significantly inhibited the gastrin response to the higher dose of GRP. This inhibitory effect exerted by fundic distension was counteracted by cholinergic blockade. In contrast, fundic distension did not alter the gastrin response to GRP in duodenal ulcer patients, suggesting a defective inhibitory mechanism in duodenal ulcer patients. After PGV, GRP infusion resulted in an enhanced gastrin response, and fundic distension seemed to facilitate the gastrin-stimulatory effect of GRP. This supports the concept of a vagally dependent inhibitory oxyntopyloric mechanism and that fundic distension can elicit both inhibitory and stimulatory secretory mechanisms.

Adult↗
PubMed1991

Reservoir function after subtotal or total gastrectomy with or without gastric substitute.

Volume and pressure characteristics as a measure of reservoir function were studied in three patient groups greater than 1 year after gastrectomy for cancer, one group with straight Roux-en-Y esophagojejunostomy, one with an s-shaped gastric substitute after total gastrectomy, and the third group with subtotal gastrectomy. A large latex balloon was introduced into the proximal jejunum, gastric substitute or gastric remnant and then filled with water at a constant, slow rate. The maximal volume capacity was 400 ml at basal pressure 13.9 cmH2O in the remnant after subtotal gastrectomy and 475 ml at 10.4 cm in the gastric substitute, but only 180 ml at basal pressure 40.4 cmH2O in the proximal Roux limb of the straight esophagojejunostomy. Maximal basal pressure and maximal pressure amplitudes throughout the study period were significantly higher in the patients with straight Roux-en-Y esophagojejunostomy. The results suggest that a gastric substitute constructed as an s-shaped pouch is characterized by pressure and volume typical of a low-pressure reservoir, similar to that achieved by leaving the proximal part of the stomach intact.

Adult↗
PubMed1990

Coronary circulation in acute hypoxia.

Healthy young men were subjected to different degrees of hypoxia at rest and during increased levels of cardiac work induced by atrial pacing and physical exercise at submaximal and maximal loads. Coronary sinus (cs) blood flow was measured by thermodilution and a-cs differences of O2 and lactate were obtained. At low cardiac power output (rest, pacing) the reduction in arterial oxygen content was compensated for mainly by a more complete myocardial oxygen extraction producing lowered cs O2 saturation and tension, while at higher cardiac power (exercise) the compensatory mechanism was entirely an increased coronary blood flow. It was possible to compensate fully for a reduction in arterial O2 saturation of 9% even during maximal physical exercise. With a reduction in arterial oxygen content of more than 20-25% the flow increase was sufficient to supply the heart with enough O2 during submaximal (heart rate 157 beats min-1) but not maximal exercise, in which case anaerobic glycolysis contributed significantly to the myocardial energy metabolism. It is concluded that the normal heart has a 'coronary flow reserve' of about 33% above the flow prevailing during maximal physical exercise under air breathing.

Adaptation, Physiological↗
PubMed1990

Neuropeptide Y is released together with noradrenaline from the human heart during exercise and hypoxia.

The myocardial release of neuropeptide Y-like immunoreactivity (NPY-LI) and noradrenaline (NA) during exercise with and without arterial hypoxia was measured in 18 healthy men by arterial (a) and coronary sinus (cs) catheterization. Exercise was performed in the supine position on a cycle ergometer at a load, selected to produce a heart rate during air breathing of 120 beats min-1. Coronary sinus blood flow (CSBF) was measured and a and cs samples for NPY-LI, NA, oxygen and lactate analyses were taken at rest and after 6 min exercise. The inspiratory gas was then switched to 15% (n = 8) or 12% (n = 10) oxygen in nitrogen, exercise continued at the same load and measurements repeated after 6 min. At rest no significant release and during normoxic exercise a very small myocardial release of NPY-LI and NA was detected. During hypoxia compared to normoxia the cardiac NPY-LI release increased four-fold and the NA net release doubled at the same time as the arterial NPY-LI remained unaltered or only slightly increased. Both the NPY-LI and the NA net release from the heart correlated with the heart rate and the arterial but not the cs oxygen tension. The NPY-LI release was correlated with the NA net release. The findings suggest that arterial hypoxia stimulates cardiac NPY together with NA release which derives from local sympathetic nerves. The release from the heart seems to be greater than from other tissues.

Adult↗
PubMed1990

Emergence of cross-resistance to beta-lactam antibiotics in fecal Escherichia coli and Klebsiella strains from neonates treated with ampicillin or cefuroxime.

Both ampicillin and cefuroxime therapy of neonates selected drug- and species-dependent beta-lactam resistance patterns in fecal strains of Escherichia coli and Klebsiella spp. This was in contrast to our previous findings that ampicillin, but not cefuroxime, contributed to the emergence of beta-lactam resistance also by the promotion of nosocomial spread of resistant strains.

Ampicillin↗