Biomedical subjects

G Johansson

Publications and source records attributed to G Johansson.

At least 235 records · Page 13Linked to original sources

PubMed1989

REM sleep deprivation increases early morning pineal melatonin in castrated rats.

Recently nighttime melatonin levels have been shown to be attenuated in depressive patients or patients with dementia of the Alzheimer type. On the other hand, depression can be transiently relieved by deprivation of rapid eye movement sleep. Since exogenous melatonin administration increases rapid eye movement sleep and slow wave sleep in the rat, could rapid eye movement sleep deprivation then inversely influence endogenous melatonin production? We found indices that in castrated Wistar rats 4 days of rapid eye movement sleep deprivation by the cuff pedestal method elevates the pineal content of melatonin by a factor of two at 1 to 2 h after light onset. Rapid eye movement sleep is thus suggested to influence pineal activity. This mechanism might be involved in the human depression-alleviating effect of rapid eye movement sleep deprivation.

Animals↗

PubMed1989

Serum electrolytes and parathyroid hormone in patients in a coronary care unit.

A prospective study was carried out in 499 patients admitted to a coronary care unit (CCU) in order to evaluate the incidence of clinically significant electrolyte disturbances. Low serum potassium values (less than 3.6 mmol l) occurred in 7% of the CCU patients and low serum magnesium values (less than 0.70 mmol l-1) in 6%. Few patients had low values of both these ions (1.9%). In 49 patients the contents of these electrolytes in muscle biopsies were similar to the values of control subjects and were unrelated to treatment with diuretics. Serum calcium was determined in 444 of the patients and was above the reference range in 11 (2.5%). If we consider their concomitant parathyroid hormone (PTH) values, primary hyperparathyroidism was likely to occur in at least seven patients (1.5%). Patients with acute myocardial infarction (AMI) had mean PTH and electrolyte values similar to those of individuals without this disease. In conclusion, the present study indicates that clinically important disturbances of magnesium, potassium or calcium homeostasis are rare among unselected patients admitted to a CCU.

Adrenergic beta-Antagonists↗

PubMed1989

Dyspnoea in chronic primary fibromyalgia.

We investigated the prevalence of dyspnoea, according to a 5-grade score proposed by the World Health Organization (WHO), among 87 consecutive women (age 44.0 +/- 8.4, range 26-65 years), with severe chronic primary fibromyalgia (CPF). In total 73 women (84%) were dyspnoeic, 47, 17, six and four patients reported dyspnoea corresponding to WHO grades 1, 2, 3 and 4, respectively. In multivariate analysis WHO dyspnoea grade was the most important determinator of exercise capacity. The higher WHO dyspnoea grade reported, the lower exercise capacity and heart rate were reached at graded bicycle exercise tests (r = -0.48, P less than 0.001 and r = -0.40, P less than 0.001). WHO dyspnoea grade correlated directly to breathing frequency at rest (r = 0.45, P less than 0.001) and inversely to maximum inspiratory pressure (r = -0.29, P less than 0.01). It did not correlate with maximum expiratory pressure, nor with spirometric measurements of pulmonary function. It is concluded that dyspnoea is common among CPF patients and is not explained by cardiac or pulmonary causes, but may partly be due to diaphragmatic muscular insufficiency and physical inactivity.

Adult↗

PubMed1989

Cardiotoxicity of ropivacaine--a new amide local anaesthetic agent.

Anaesthetically equipotent doses of lidocaine, bupivacaine and a new bupivacaine-like local anaesthetic agent, ropivacaine, were injected into the left anterior descending coronary artery of pentobarbital-anaesthetized pigs. The aim was to study the cardiotoxicity of ropivacaine in relation to the two other drugs. A random, crossover, dose response study design was used. The following doses of the drugs were administered: lidocaine (L): 1,2,4,8 and 16 mg, bupivacaine (B): 0.25, 0.5, 1,2 and 4 mg and ropivacaine (R): 0.33, 0.66 1.33, 2.66 and 5.33 mg. Systemic haemodynamics, left ventricular dP/dT and a 12-lead electrocardiogram were recorded continuously during the study period. The drugs depressed cardiac contractility in relation to their local anaesthetic potency on the isolated nerve-4:3:1 (B:R:L). The prolongation of the ECG QRS-interval was regarded as a measure of electrophysiologic toxicity. Comparable prolongation of the QRS-interval was recorded after 2 mg of bupivacaine, 4.5 mg of ropivacaine and 30 mg of lidocaine. Thus, the electrophysiological toxicity ratio was 15:6.7:1 (B:R:L). Provided local anaesthetic potency data can be extrapolated from the isolated nerve preparation to regional anaesthesia in humans, ropivacaine appears to provide a greater margin of safety than bupivacaine, if inadvertently injected into the venous circulation.

Amides↗

PubMed1989

Cardiac manifestation and blood catecholamine levels during succinylcholine-induced stress of malignant hyperthermia sensitive pigs.

Fifteen crossbred pigs of Swedish Landrace and Yorkshire, about 6 months of age and susceptible to develop malignant hyperthermia (MH) when exposed to halothane, were subjected to stress provoked by the myorelaxant succinylcholine. The results were compared with those of 12 normal pigs. During the stress the halothane-sensitive (HS) pigs showed much higher levels of plasma noradrenaline and adrenaline and more severe ventricular arrhythmias than the controls. The degree of myocardial degeneration and necrosis being similar to catecholamine induced myocardial damage was significantly higher in the HS pigs than in the controls. The ultrastructural examination revealed three main types of changes in affected myocardial cells. One type of myocardial cell damage was characterized by various degree of hypercontraction, enlarged mitochondria with dense bodies and dilated sarcoplasmic reticulum. The other type showed mitochondria with tubular configuration whereas the third type of cell damage was characterized by almost normal mitochondria combined with a severe damage of the myofilaments. Three HS pigs which died within 30 min after stress showed signs of malignant hyperthermia. No signs of the disease were observed in the other 12 HS pigs.

Animals↗

PubMed1989

Anevac-D, a new system for close scavenging of anesthetic gases in dental practice.

Anevac-D, a new system for close scavenging of anesthetic gases in dental practice is described. It consists of a rubber nose mask surrounded by an outer rigid shell and a chin scavenger. A vacuum in the slot between the nose masks provides scavenging of gases escaping from the inner mask. Gases escaping from the mouth are evacuated mainly by the skin scavenger. The efficiency of this system was assessed in healthy volunteers using argon as a tracer gas. Mass spectrometry was used for measurement of inspired, expired, and scavenged gas concentrations. The scavenging efficiency of the complete system was around 80% and was not affected by poor patient cooperation. It decreased to about 65% when the chin scavenger was removed. The dentist's exposure was measured by sampling of argon in the breathing zone by a Saran system. The average 4-min exposure varied between 90 and 250 ppm depending on system configuration and patient cooperation. Patient acceptance and clinical applicability were judged good. It is concluded that the Anevac-D system provides excellent scavenging properties and exposure levels well within the official recommendations by the Swedish Board of Occupational Safety and Health.

Adolescent↗

PubMed1989

Effect of different nocturnal illuminances on melatonin, prolactin, and gonadotropins in male rats.

We studied the role of nocturnal illuminance as a possible regulatory factor in the production and secretion of reproductive hormones. Adult male rats were kept under artificial lighting conditions (LD 12/12 hours) where the daily illuminance was 520-550 lx and the nocturnal illuminance 0, less than 0.1, or 1-1.5 lx. After a 7 day adaptation period, the pineal contents of melatonin, the serum levels of LH, FSH, and prolactin, and the pituitary contents of these hormones were measured by radioimmunoassay in samples taken 4 and 7 hours after the onset of light and onset of darkness. When the rats were kept in full darkness or under the minimal nocturnal iluminance (less than 0.1 lx), the patterns of pineal melatonin were equal. When nocturnal illuminance was 1-1.5 lx, the pineal melatonin contents at night were lower than in complete darkness. However, this illuminance level did not totally abolish the nocturnal increase of melatonin synthesis. The serum levels of LH, FSH, and prolactin were all affected by the increase of nocturnal illuminance so that the difference between the daytime and nighttime levels increased (higher values during the night). The variation of nocturnal illuminance did not change the pituitary contents of gonadotropins. The effects on pituitary prolactin were negligible as well. The results are interpreted to support the concept that nocturnal illuminance levels may regulate the secretion of the studied hormones in male rats.

Animals↗

PubMed1989

Lighting conditions affect testosterone feedback sensitivity in castrated rats.

It has been shown in the Syrian hamster that a short photoperiod sensitizes the hypothalamo-hypophyseal axis of castrated animals to the negative feedback effect of testosterone. There is some evidence that even the reproductive system of the rat, which is generally considered not to be very sensitive to light, can respond to changes in illumination. Therefore, we found it of interest to examine whether alterations in lighting conditions produce changes of sensitivity in the negative feedback effect of testosterone in the rat. We kept intact, castrated, and castrated testosterone-treated animals either in periodic (L:D 12:12) or constant light for 7 days starting 4 weeks after castration. In all 3 testosterone-injected groups, serum luteinizing hormone (LH) was lower in constant than in periodic light. Exogenous testosterone did not decrease the castration-induced elevations of pituitary LH and follicle-stimulating hormone (FSH). On the contrary, testosterone increased the pituitary contents of LH and FSH, especially in constant light. We conclude that, in constant light, the hypothalamo-hypophyseal axis of the castrated rat becomes more sensitive to the negative feedback action of testosterone.

Animals↗

PubMed1989

Effect of neonatal androgenization on the testosterone feedback sensitivity in adult rats in two lighting conditions.

Neonatally androgenized and intact adult male Wistar rats received daily, during 1 week, either testosterone propionate or sesame oil injections in periodic or constant light. Serum and pituitary gonadotropins and hypothalamic LHRH were measured. In periodic light, neonatal androgenization did not change the serum concentration or pituitary contents of gonadotropins, or the hypothalamic content of LHRH. Testosterone injections decreased serum concentration and pituitary content of gonadotropin of intact rats but failed to decrease the pituitary gonadotropin content of neonatally androgenized rats. In constant light, serum FSH was decreased in neonatally androgenized rats. Testosterone injections decreased both serum LH and FSH concentrations of intact rats but only serum LH of androgenized rats. Pituitary gonadotropin and hypothalamic LHRH contents remained unchanged. We conclude that neonatal androgenization renders the male rat hypothalamo-pituitary axis more resistant to changes of testosterone concentration in adulthood. Constant light did not sensitize the neonatally androgenized rats to testosterone, but on the contrary, testosterone injections were less effective in constant than in periodical light.

Androgens↗

PubMed1989

Daily illuminance levels affect pituitary prolactin in male rats.

The 24-h patterns of melatonin, PRL, and gonadotropins in male rats maintained under natural lighting conditions have been found to differ from the patterns in rats kept under artificial lighting. In the present experiments we studied the role of different daily illuminances as a possible causative factor for the variation of the hormonal patterns. Three groups of male rats were kept under artificial lighting conditions (12 h on/12 h off), where the daily illuminance was 550, 110 or 25 lux. After a 7-day adaptation period the pineal content of melatonin, the serum levels of LH, FSH and PRL, and the pituitary content of these hormones were measured by RIAs in samples taken at 10.00, 13.00, 22.00 and 01.00 h. The patterns of pineal melatonin were equal in all three groups. The variation of daily illuminance did not change the serum levels of LH, FSH and PRL or the pituitary content of the gonadotropins. However, the pituitary content of PRL during the light phase was inversely related to the illuminance. The results suggest that the intensity of daily lighting in the studied range does not affect the patterns of melatonin or gonadotropins, but the synthesis of prolactin may be significantly regulated by the daily illuminance level.

Animals↗

PubMed1989

Introduction: the need for new directions in research on work organization and health.

The articles in this issue of the Journal conclude the Special Section on work organization and health, dedicated to the late Bertil Gardell. We review here the earlier articles, which have addressed issues such as: the social epidemiology and psychobiology of work and health, psychosocial prevention and work reform, international developments in health policy, and multidisciplinary theoretical developments. The articles in this issue urge an expansion and redirection of research effort in this field into two new areas. The first article examines the relationship between gender, control, and work stress. It is proposed that because the vast majority of studies have previously been performed on males, there is a growing need to examine the work organization conditions of females. The second article discusses the need for a further expansion of knowledge concerning the underlying pathobiological mechanisms that link work stress exposure to chronic illness, and presents a biologically based model of the impact of exposure to low work control conditions on neuroendocrine response patterns. Finally, concluding comments concerning the Special Section are made.

Employment↗

PubMed1989

Organizational change and work reforms at the levels of society, trade union, work group, and task.

This article introduces the third series of articles in the Special Section on work organization and health. The authors follow up on themes addressed in earlier articles, among them the interrelations between work organization and health, organizational obstacles to democratization at the work place, and the need for employee involvement in attaining and developing democratic forms of work organization.

Democracy↗

PubMed1989

Job demands and stress reactions in repetitive and uneventful monotony at work.

Monotonous work has been analyzed from sociological and social psychological perspectives in terms of consequences for job satisfaction, life satisfaction, leisure activities, and health. In this article, a distinction is made between repetitive and uneventful monotony. Psychobiological reactions to these tasks are analyzed and related to possible long-term consequences for health. Strategies for work reform required for the two types of monotony are discussed.

Boredom↗

PubMed1989

Pharmacokinetics and central haemodynamic effects of doxorubicin and 4'epi-doxorubicin in the pig.

The relationship between the cardiotoxicity and the haemodynamics/pharmacokinetics of clinical concentrations of doxorubicin and 4'epi-doxorubicin was studied. Twelve pigs were randomized to receive i.v. infusions of either drug of 50 mg/m2 over 3.0 min. Aortic, pulmonary arterial, coronary sinus and central venous plasma concentrations of the agents were determined until 180 min after the infusion. The V5 ECG, left ventricular dP/dT, aortic, pulmonary arterial and right atrial pressures were recorded continuously, cardiac output and coronary sinus blood flow were recorded intermittently. No haemodynamic changes were recorded after administration of either drug. Pharmacokinetic data indicated myocardial extraction, followed by myocardial release of both drugs. This release was higher after administration of 4'epi-doxorubicin than after doxorubicin, within the range 2-4 min and 20-40 min after the infusion. The tendency of greater myocardial release of 4'epi-doxorubicin may explain its lower cardiotoxicity.

Animals↗

PubMed1988

A binding-site-deficient, catalytically active, core protein of endoglucanase III from the culture filtrate of Trichoderma reesei.

From the culture filtrate of Trichoderma reesei we have isolated a novel endoglucanase (38 kDa) which was shown to be identical to endoglucanase III (E III, 50 kDa), but lacking the first 61 N-terminal amino acids. This core protein, designated E III core, is fully active against soluble substrates, such as carboxymethylcellulose, whereas both activity against and adsorption to microcrystalline cellulose (Avicel) is markedly decreased. Sedimentation velocity experiments revealed that the intact E III enzyme has much higher asymmetry than the E III core protein, suggesting that the N-terminal region split off constitutes a protruding part of the native enzyme. These results lead to the proposal that native E III consists of two functionally separated domains: a catalytically active core and a protruding N-terminal domain which acts in the binding to insoluble cellulose. The N-terminal peptide missing in E III core corresponds to the heavily glycosylated common structural element found also in the N-terminus of cellobiohydrolase II and in the C-termini of cellobiohydrolase I and endoglucanase I. A similar bifunctional organization could thus be the rule for Trichoderma cellulases, endoglucanases as well as cellobiohydrolases.

Amino Acid Sequence↗

PubMed1988

Toxins from the venom of the green mamba Dendroaspis angusticeps that inhibit the binding of quinuclidinyl benzilate to muscarinic acetylcholine receptors.

Two protein toxins that displace the muscarinic antagonist quinuclidinyl benzilate from rat cortex synaptosomal membranes have been isolated from the green mamba (Dendroaspis angusticeps) venom by gel filtration on sephadex G-50, chromatography on the ion-exchangers Bio-Rex 70 and Sulphopropyl-Sephadex C-25 and reversed-phase HPLC. Toxin 1 has 64 amino acids and four disulfides and a formula weight of 7200 and the corresponding values for toxin 2 are 63, 4 and 6840, respectively. Ultracentrifugation gave a molecular weight of 6900 for toxin 1 and 6700 for toxin 2, Quinuclidinyl benzilate that binds to all types of muscarinic cholinergic receptor was displaced to about 50% by both toxins. This partial displacement indicates that the toxins might be specific for one subtype of receptor.

Amino Acids↗

PubMed1988

Cardiopulmonary hemodynamics and pharmacokinetics after hepatic intraarterial infusion of 5-fluorouracil (5-FU). An experimental study in the pig.

Reported 5-FU-induced cardiac side effects may be explained by drug-induced hemodynamic changes and/or by direct myocardial toxicity due to regional drug uptake. This question was studied in 11 animals given constant infusions and 6 animals given bolus 5-FU infusions into the hepatic artery. Six animals, which received normal saline infusion, served as controls. A second aim was to study possible pulmonary drug clearance. Aortic, pulmonary arterial, and coronary sinus plasma 5-FU concentrations were determined during constant and after the bolus infusions of 5-FU. The V5 ECG, aortic, pulmonary arterial, and right atrial pressures were recorded continuously, and cardiac output and coronary sinus blood flow were recorded intermittently in all animals. No significant alterations in hemodynamic variables were seen during constant infusion. After the bolus infusion, an increased arterio-mixed venous oxygen content difference was recorded. Pharmacokinetic data after 3-min infusions indicated pulmonary drug uptake and release; during constant infusions, the data indicated myocardial drug uptake. As there were no alterations in myocardial oxygen demand or supply or in systemic hemodynamics during this myocardial drug uptake, it is likely that the cardiotoxicity is related to the direct effects of the drug on cardiac myocytes.

Animals↗

PubMed1988

Partition and counter-current distribution of membrane particles in aqueous dextran-poly(ethylene glycol) two-phase systems with special reference to synaptosomes.

Aqueous two-phase systems composed of water, dextran and poly(ethylene glycol) can be used for the separation of biological particles. The adjustment of the partition of such particles between the two phases and the interface between them has been studied by using a preparation of synaptosomes (from calf brain cortex) also containing free mitochondria. The partition has been affected by variation of polymer concentrations and addition of salts, e.g. phosphates and chloride. The time for separation of the phases showed a bimodal behaviour with an initially rapid formation of bulk phases followed by a slow phase separation. The relative amount of mixed phases at the time of the transition was proportional to the amount of particles included. Counter-current distribution with moderate time for the phase separation was carried out in such way that the interface material travelled with approximately half the speed of the moving upper phase. In this way the distribution of the particles between the upper phase and the interface as well as between the interface and the lower phase could be studied in the same experiment. The heterogeneity of the synaptosome preparation was clearly demonstrated by counter-current distribution at low polymer concentrations while no separation was obtained when the system contained larger amounts of polymers. Possible reasons for this behaviour are discussed.

Animals↗