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Biomedical subjects

G Nyberg

Publications and source records attributed to G Nyberg.

At least 217 records · Page 12Linked to original sources
PubMed1979

Effects of labetalol and propranolol on blood pressure at rest and during isometric and dynamic exercise.

The influence of intravenous labetalol and propranolol on the blood pressure response to isometric and dynamic exercise was examined in a double blind study in eight, young, normotensive volunteers. Effects were recorded after propranolol 7.5, 15 and 30 mg i. v., and after labetalol 30, 60 and 120 mg i. v. In control experiments saline was administered. Mean blood pressure rose with successive handgrip tests following saline and propranolol, but not after labetalol, and the difference was significant. The total dose of each drug produced the same reduction in heart rate during sub-maximal bicycle exercise. The exercise-induced systolic blood pressure response did not differ between the drugs.

Adult↗
PubMed1979

Limitation of work performance in normal adult males in the presence of beta-adrenergic blockade.

The effect on work performance of a single oral dose of the cardio-selective beta-adrenoreceptor blocking agent, metoprolol, was compared with an equipotent dose of the non-selective agent, propranolol, in the same subjects. A number of biochemical and physiological variables including heart rate, oxygen consumption, ventilation, lactate, free fatty acid and glucose levels were measured. Following exercise in the presence of both active drugs, subjects complained of excessive leg fatique. For the group there was a significant reduction in the total work performed and the maximum heart rate achieved on both drugs. There was a significant correlation between plasma levels of metoprolol, reduction in total work performed and reduction in maximum heart rate. By contrast, after propranolol, there was a wide variation in work performed at a time when the reduction in maximum heart rate was similar for all subjects. This suggests for propranolol that a reduction in heart rate alone is an inappropriate guide to the impairment of work performance. There was a fail in the circulating level of free fatty acids at the end of exercise in the presence of both drugs and it is possible that this biochemical variable contributed to the decrease in work performance.

Adult↗
PubMed1979

QT time in patients treated with alprenolol or placebo after myocardial infarction.

Studies were made on the effects of long-term beta-blockade on the QT interval in patients discharged alive from hospital after myocardial infarction. The patients (n = 230) in this study constituted all those who participated in the alprenolol study on postmyocardial patients in Göteborg, Sweden. The study was double-blind (alprenolol 200 mg b.i.d. or placebo) and randomised. The patients were divided into 4 risk groups (1-4) with different predicted mortality. The electrocardiograms before and after 8 weeks of treatment were analysed with respect to heart rate and QT time. There was a decrease in heart rate of about 10% in the alprenolol treated patients. The QT time was not significantly influenced by alprenolol. The rate corrected QT time (QTc) decreased in the subgroup of the most severely diseased patients (subgroup 4) treated with alprenolol.

Aged↗
PubMed1978

Results from a multicentre trial of metoprolol and a study of hypertensive patients with chronic obstructive lung disease.

Ninety-nine patients took part in a multicentre, long-term study of metoprolol in the treatment of hypertension. Significant reductions in blood pressure and heart rate were achieved by the use of metoprolol alone, or in combination with other antihypertensive agents. Side effects were similar to those seen with other beta-adrenergic blocking agents, except that bronchospasm and cold extremities were rarely encountered. Results of monitoring for the abnormal eye symptoms and antinuclear factor titre are discussed. In a second study, 14 hypertensive patients with asthma (11 patients) or history thereof (three patients), received metoprolol for their hypertension. In general, no significant change in forced expiratory volume in one second (FEV1) was found, despite significant reduction in blood pressure and heart rate. The concomitant use of a beta2-agonist is discussed.

Adult↗
PubMed1978

Angiography of the testicular artery as a diagnostic aid in boys with nonpalpable testis.

Selective angiography of the testicular artery was performed in 12 boys (age 3-14 yr) with nonpalpable testis. The angiographic, operative, and microscopic findings are described. True aplasia was diagnosed in seven patients. In three patients previously operated upon, the second exploration was facilitated by angiography. This method might be a valuable diagnostic aid in selected cases previously operated for gonadal disorders or inadequately explored for cryptorchism in order to avoid more extensive surgical exploration.

Adolescent↗
PubMed1978

Comparison of intra-arterial and indirect blood pressures at rest and during isometric exercise in hypertensive patients before and after metoprolol.

1. Blood pressure was measured both directly and indirectly in seven hypertensive patients before and after a single oral dose of 100 mg metoprolol, at rest and during sustained handgrip. 2. Intra-arterially measured systolic and diastolic blood pressure increased linearly with time during sustained handgrip at 50% of maximal voluntary contraction. This linearity persisted for 60 s or more in most cases. Heart rate increased linearly for the first 30 s. 3. Indirectly measured blood pressure using an observer bias minimizing Auto-Manometer, under-read systolic and over-read diastolic pressure both at rest and during handgrip. 4. By exact timing of recorded values during handgrip and linear extrapolation (or interpolation) from base-line readings, mean values at 30 and 60 s of handgrip were calculated. The relationship between direct and indirect values remained the same at base-line and 30 s of handgrip. At 60 s of handgrip, this was true only for diastolic pressure. For systolic pressure, indirect and direct values almost coincided. 5. After metoprolol, directly recorded pressure fell slightly (7--12 mm Hg, 0.02 less than P less than 0.10), both at rest and during handgrip, and heart rate fell by 15--18 beats/min (P less than 0.01). The systolic blood pressure and heart rate effect of metoprolol at 1 min handgrip correlated with peak plasma drug levels. Indirectly measured blood pressure did not change significantly. 6. The rate of rise in heart rate and blood pressure from base-line to 60 s handgrip was not significantly influenced by metoprolol.

Adult↗
PubMed1978

Hydrogen peroxide and superoxide radical formation in anaerobic broth media exposed to atmospheric oxygen.

Fourteen different broth media were autoclaved under anaerobic conditions and then exposed to atmospheric oxygen. The hydrogen peroxide and superoxide radical formation as well as the bactericidal effect of the media were studied. The rate of killing of Peptostreptococcus anaerobius VPI 4330-1 was high in media that rapidly autoxidized and accumulated hydrogen peroxide. In actinomyces broth (BBL), 50% of the cells were killed within 2 min, and in Brewer thioglycolate medium (Difco), 50% were killed within 11 min, whereas more than 50% of the cells survived for more than 2 h in Clausen medium (Oxoid), fluid thioglycolate medium (BBL), and thioglycolate medium without dextrose or indicator (Difco). Only media that contained phosphate and glucose had a tendency to accumulate hydrogen peroxide. A solution of phosphate and glucose autoxidized when it had been heated to 120 degrees C for at least 5 min and when the pH of the solution was higher than 6.5. Transitional metal ions catalyzed the autoxidation, but they were not necessary for the reaction to occur. Of the other substances heated in phosphate buffer, only alpha-hydroxycarbonyl compounds autoxidized with accumulation of hydrogen peroxide. Superoxide dismutase decreased the autoxidation rate of most of the broth media. This indicated that superoxide radicals were generated in these media.

Anaerobiosis↗
PubMed1977

Quantitative analysis of tricyclic antidepressants in serum from psychiatric patients.

A method for the quantitative analysis of tricyclic antidepressants in the serum of psychiatric patients is described. The method can be used for determining amitriptyline, nortriptyline, imipramine, demethyllimipramine, clomipramine, demethylclomipramine, trimipramine and protriptyline. The method consists in a series of extraction steps followed by gas chromatography with flame-ionization detector. The drugs are determined in their native state. The internal standard method is used for the quantitation.

Antidepressive Agents, Tricyclic↗
PubMed1977

Human adipose tissue in culture. VII. The long-term effect on growth hormone.

Biopsies of human adipose tissue were cultured for one week in vitro with or without different concentrations of human growth hormone (GH). After preincubation they were incubated in vitro for 2 hours analogous to the technique generally used for short-term experiments. The release of glycerol and incorporation of glucose into triglycerides were measured under basal conditions as well as in the presence of insulin or noradrenaline. An impairment in the basal glucose incorporation rate was found after the culture period with GH, but there was no concomitant effect on lipolysis. The effect of insulin on glucose incorporation was stimulating to the same extent as in the controls but the metabolis rate was even in the presence of insulin still below that of the controls. The effects of noradrenaline and of insulin on lipolysis were similar to those in the control group. It is concluded from the present study that a direct "diabetogenic" effect of GH on human adipose tissue can be detected. This effect developed successively over the seven days that the incubations were performed. It was due to a diminished basal rate of glucose incorporation and not to a direct resistance to the action of insulin and it was not related to increased lipolysis.

Adipose Tissue↗
PubMed1977

Indirect blood pressure and heart rate measured quickly without observer bias using a semi-automatic machine (auto-manometer)--response to isometric exercise in normal healthy males and its modification by beta-adrenoceptor blockade.

1 In a double-blind crossover study, six volunteers performed sustained handgrip at 50% of maximal voluntary contraction before and 90 min following oral administration of 0.25 and 100 mg metoprolol tartrate, a beta1 selective adrenoceptor blocking agent. Blood pressure and heart rate were measured with the Auto-Manometer, an electronic semi-automatic device based on the principles of the London School of Hygiene and Tropical Medicine sphygmomanometer. It eliminates observer and digital bias completely, and also records heart rate at the same time as blood pressure is recorded. 2 Resting heart rate fell 15% after 25 mg, 21% after 100 mg and was unchanged after placebo. Systolic blood pressure fell 6% on both doses and was unchanged on placebo. Diastolic pressure did not change with any of the doses. 3 At 1 min of handgrip, heart rate was significantly lower after 25 and 100 mg than before drug or after placebo. There was no difference between the blood pressure levels attained before or after any of the dose levels. The rise of heart rate tended to be somewhat dampened after 100 mg only. The rise in blood pressure was unchanged after any dose compared with before.

Adult↗
PubMed1977

The effect of mental arithmetic in normotensive and hypertensive subjects, and its modification by beta-adrenergic receptor blockade.

1 The effects of a 5-min period of sustained mental arithmetic upon blood pressure and heart rate were determined in several groups of healthy subjects and hypertensive patients. 2 The arithmetic produced significant increases in heart rate and blood pressure (both systolic and diastolic) in both normotensive and hypertensive subjects. 3 The blood pressure changes were neither attenuated nor enhanced by the prior administration of basis. 4 In subjects habituated to the test the heart rate increase was unaffected by the drugs, but in those less familiar with the test it was usually attenuated. 5 Although the beta1-adrenoceptor selective blocker, metoprolol, caused decreases in baseline values for blood pressure and heart rate similar to those observed with the use of the two non-selective blockrs, it was shown in a double-blind crossover comparison with propranolol that the haemodynamic changes provoked by the mental arithmetic were not less in the presence of beta1-receptor blockade than when both beta1- and beta2-receptors were blocked. 6 These findings suggest that, during beta2-adrenoceptor blockade, the haemodynamic effects of minor mental stress are not exaggerated because of uncompensated alpha-receptor mediated vasoconstriction, such as occurs following adrenaline infusion.

Adrenergic beta-Antagonists↗
PubMed1977

Extraction and metabolism of lidocaine in rat liver.

The use of lidocaine as an oral antiarrhythmic drug is limited by its rapid disposition in the liver. In accordance with this we found that the drug was completely extracted during one passage through the perfused rat liver. The drug binds to rat liver microsomes with a type I spectral change of unusually high affinity. It is rapidly de-ethylated by the microsomes with an apparent Vmax of about 15 nmol per mg protein x min. The apparent Km for this reaction is about 250 muM. The reaction occures at about the same rate in isolated rat liver cells. We believe that the high affinity of lidocaine for the cytochrome P-450 system, as indicated by its type I spectral change, as well as the rapid oxidation of the drug are the two main determinants for the marked liver extraction and first pass effect of the drug.

Animals↗
PubMed1977

Effect of age on human adipose tissue metabolism and hormonal responsiveness.

The effects of age and fat cell size on the metabolism of white human adipose tissue were analysed independently. Abdominal subcutaneous adipose tissue specimens were obtained from children varying in age from 0-15 years and from adults (mean age +/- S.D.; 38.2 +/- 14.1 years). The basal rates of lipolysis and glucose incorporation into lipids were considerably higher in children than in adults even when differences in fat cell size had been taken into account. Lipolysis in response to a maximal concentration of noradrenalin was higher in fat cells from children. However, on a percentage basis the responsiveness to this agent was similar in children and adults. Irrespective of age, glucagon did not elicit a lipolytic response. Thus, it does not seem that the increased lipolysis known to occur in vivo in the neonatal period is due to a direct effect of glucagon on white adipose tissue. However, the overall lipolytic capacity is increased in fat cells from children.

Adipose Tissue↗
PubMed1977

Angiography of the testicular artery. II. Cryptorchism and testicular agenesis.

A selective angiography of the testicular artery was performed in 7 boys and 7 men without a palpable testicle in order to localize cryptorchid testes or to establish testicular agenesis. The examination could be carried out in all cases, and the angiographic diagnosis was confirmed at operation and at a subsequent microscopy in the 12 cases hitherto operated upon. The width of the artery and its branches are also presented.

Adolescent↗
PubMed1976

Human adipose tissue in culture. IV. Evidence for the formation of a hormone antagonist by catecholamines.

Explants of human adipose tissue were cultured for several days with noradrenaline (NA). After the culture period the explants were carefully washed, preincubated and then incubated for 2 h by a technique analogous to those generally used to study adipose tissue metabolism. The results show that explants cultured with NA were considerably less responsive to the acute lipolytic effect of catecholamines than explants not previously exposed to NA. The diminished responsiveness could not be reversed by the addition of phentolamine or by preincubating the explants with a prostaglandin antagonist and it was dependent upon the concentration of noradrenaline used in the culture medium as well as upon the period of time that the explants were exposed to the hormone. The cyclic AMP (cAMP) levels did not increase in response to NA in these explants. Addition of theophylline or dibutyryl cAMP elicited a lipolytic response. However, the phosphodiesterase levels were not increased in the explants cultured with noradrenaline. When freshly excised tissue specimens were incubated in the culture medium which had previously contained NA the acute lipolytic effect of catecholamines was blunted. The results indicate that an antagonist is formed during the incubation with NA which inhibits the responsiveness to catecholamines. The effect of the antagonist seems to be exerted at a step prior to the formation of cAMP.

3',5'-Cyclic-AMP Phosphodiesterases↗