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Biomedical subjects

B Bengtsson

Publications and source records attributed to B Bengtsson.

At least 109 records · Page 6Linked to original sources
PubMed1985

Repeated automatic visual field screening in a cohort study.

During 1977 and 1978 automatic visual field screening was performed in 1511 persons born 1907-1921 and taking part in a population study. Three years later automatic visual field screening was repeated in 2565 eyes of 1293 persons. "Irrelevant" defects were common and had a limited repeatability. "Relevant" defects were easily detected at the first and reproduced at the second survey. From a clinical point of view, the yield of the visual field screening at the second survey was restricted. We concluded that repeated visual field screening by automatic perimetry is quite feasible but has little reward.

Diagnostic Errors↗
PubMed1985

Acute haemodynamic effects of felodipine and verapamil in man, singly and with metoprolol.

In a single-blind randomised study in 9 healthy men we compared the acute haemodynamic effects of the calcium antagonists felodipine and verapamil, singly and in combination with metoprolol. Three different cumulative intravenous doses of 0.25, 0.75 and 1.5 mg felodipine and of 2.0, 4.0 and 8.0 mg verapamil or placebo were given as constant infusions over 5 minutes on 3 occasions and were followed by intravenous metoprolol (15 mg). Felodipine caused a significant and dose-dependent decrease in the total peripheral resistance, and an increase in the forearm blood flow by 8, 48 and 163% with progressively increasing doses showing that the drug is a potent arteriolar vasodilator. A significant and dose-dependent increase in heart rate and a decrease in the pre-ejection period/left ventricular ejection time (PEP/LVET) ratio of up to 15% was also recorded, mainly reflecting a reflexogenic increase in the sympathetic tone. Total peripheral resistance, forearm blood flow, heart rate and the systolic time intervals were mainly unchanged after verapamil, whereas the PQ interval was prolonged. Metoprolol given after the 2 calcium antagonists caused a decrease in heart rate and blood flow and an increase in the total peripheral resistance and PEP/LVET ratio. The tolerability was good to all infusions.

Adult↗
PubMed1985

Acute diuretic/natriuretic properties of felodipine in man.

The natriuretic/diuretic effect of felodipine was investigated in 2 studies. The first was performed as an open study using intravenous and oral felodipine in healthy male subjects. The second was a double-blind study where a high and a low dose of oral felodipine were given to hypertensive patients on long term treatment with beta-blockers; the different doses of felodipine were chosen to decrease and to have no effect on the blood pressure, respectively. In both studies an oral placebo solution was used as a reference. Felodipine caused a significant increase in natriuresis. Compared with placebo and corrected for total 24-hour excretion, the sodium output during the first 4 hours after drug administration was increased by 219 +/- 53% (mean +/- SEM) after intravenous administration in healthy subjects (p less than 0.01) and by 80 +/- 43% in the first 3 hours after the high dose in hypertensive patients (p less than 0.05). For the same period, the urine excretion was increased by 114 +/- 38% (p less than 0.05) in the healthy subjects and by 36 +/- 22% in the hypertensive patients (not significant). However, the 24-hour excretion of urine, Na+ and K+ was not significantly changed from placebo. A significantly lower blood pressure was recorded after the higher dose (0.10 mg/kg) when given to hypertensive patients, but no such effect was seen after the lower dose (0.01 mg/kg) or in healthy subjects. The changes in diastolic blood pressure seem to be negatively correlated with the diuretic but not with the natriuretic effect.

Adult↗
PubMed1985

A five-year experience with terbutaline for preterm labor: low rate of severe side effects.

The medical records of 330 patients treated with terbutaline infusion for the inhibition of preterm labor were reviewed over a five-year period. In patients with intact membranes the results were uniformly good, particularly when treatment was instituted before the 30th week. Half these patients had a prolonged labor of six weeks or more; in most cases of treatment failure complications already existed on admission. In only nine patients (2.7%) terbutaline treatment was stopped due to side effects: predominantly maternal tachycardia or vomiting. Two patients had chest symptoms, but in no case was pulmonary edema diagnosed. The results suggested that a low incidence of severe side effects can be obtained if the following precautions are taken: glucose is used as the infusion medium, instead of sodium chloride; concentrated solutions are given to avoid fluid overload; the patients are carefully controlled; and the infusion is immediately reduced or stopped if signs of severe side effects appear.

Dose-Response Relationship, Drug↗
PubMed1984

Calcium dependency of pregnant rat myometrium: comparison of circular and longitudinal muscle.

The purpose of this study was to determine if the changes in spontaneous contractions of circular uterine muscle during pregnancy were related to alterations in calcium (Ca) sensitivity or dependence. Circular muscle (CM) and longitudinal muscle (LM) segments from rats on Days 16-17 of gestation and at term were compared with respect to: sensitivity of potassium (K)-induced contractions to changes in extracellular Ca, and rate and magnitude of decrease of K- and acetylcholine (ACh)-induced contractions in Ca-free medium and in methoxyverapamil (D-600). The effects of low Ca and D-600 on spontaneous electrical activity of CM were also studied. Ca sensitivity was no different in CM and LM and did not change between Day 16 and term. There was no difference in the Ca-dependence of K- or ACh-induced contractions during this time. Potassium contractions declined more rapidly than ACh contractions in Ca-free media, especially in CM. Spontaneous action potentials in CM were Ca-dependent and disappeared in low Ca or D-600 on Days 16-17 and at term. Therefore the changes in contractions of CM during pregnancy are not related directly to Ca sensitivity or dependence, but indirectly via Ca modulation of the action potentials.

Acetylcholine↗
PubMed1984

The short-term effect of laser trabeculoplasty on the glaucomatous visual field. A prospective study using computerized perimetry.

Several earlier studies have shown improvement of glaucomatous visual fields after pressure reduction achieved by acetazolamide or filtering surgery, while other studies have given conflicting results. In the present study laser trabeculoplasty was used to reduce the IOP in 42 eyes with glaucomatous visual field defects. Although good pressure reduction was achieved, no general regression of field defects was observed. The changes of the visual field were not correlated to the degree of pressure reduction. The results do not support the hypothesis that glaucomatous field defects are reversible when the IOP is reduced.

Adult↗
PubMed1984

Survival of elderly ophthalmic out-patients.

Elderly ophthalmic out-patients that had visited an eye-clinic were searched in a population register 7 years later. Observed numbers of survivors were compared with those expected according to appropriate life tables. Most observed numbers of survivors came close to the expected ones. Patients, aged more than 80 years when visiting the eye-clinic, had, however, a consistently increased survival rate. Glaucoma patients, less than 80 years old, had a slightly (not significantly) lower survival rate than expected.

Aged↗
PubMed1984

Activity of circular muscle of rat uterus at different times in pregnancy.

UNLABELLED: During pregnancy, circular muscle activity changes from weak irregular contractions at midterm to strong regular contractions at term. The present study was designed to determine if this change is related to contractile ability or to membrane electrical events. Myometrial segments were taken from rats on days 16-17, 18-19, 20, and 21 (term) of gestation. Contractile ability was estimated as the maximum force elicited by 121 mM KCl or 0.6 mM acetylcholine. The K- and acetylcholine-induced contractions were significantly greater than spontaneous and no different at midterm and term. Electrical activity was measured with intracellular electrodes. Between days 16 and 21, action potentials evolved from single, plateau-type to repetitive spike trains. Plateau potentials were associated with small contractions and repetitive spikes with larger contractions. On day 21, there was a transient increase in membrane potential and cessation of spontaneous activity. Before delivery, the membrane potential declined and spontaneous spike trains appeared and triggered large contractions. CONCLUSION: the change in circular muscle activity during pregnancy is related to electrical events and not to contractile ability.

Acetylcholine↗
PubMed1984

Plasma concentration and side-effects of terbutaline.

Infusion of terbutaline sulphate (0.25 mg) was followed by increases of plasma insulin and blood glucose concentrations and by a decrease in plasma potassium. Similar metabolic changes were seen on the first day of oral terbutaline administration (5 mg, 3 times daily). Heart rate was moderately increased by terbutaline over the entire period (13 days) of oral dosing. Hand tremor always increased after terbutaline, but to a lesser degree on days 5 and 13 than after the first oral dose. On day 13, there was a very small increase in plasma insulin and no reduction in plasma potassium. Blood glucose increased slightly from an elevated morning value. Plasma terbutaline showed similar maximum concentrations on days 1 and 13. Since the concentration at the effector organs should be at least as high on day 13 as on day 1, these findings indicate that the tolerance was mediated through reduced response of the effector organs.

Adult↗
PubMed1983

Estrogen inhibition of noradrenaline release in the rabbit oviduct.

In the present study, we investigated the influence of estrogen on 3H-noradrenaline (3H-NA) release induced in the oviductal isthmus by electrical stimulation, potassium and calcium. The fractional release of 3H-NA was measured in oviducts isolated from ovariectomized rabbits and from ovariectomized rabbits treated with estradiol cypionate, 70 micrograms/kg im 72 h before an experiment. Electrical field stimulation of the intramural nerves induced muscle contraction and augmented the release of labelled NA from the muscle. The 3H-NA release was reduced after estrogen treatment when reuptake of NA into the nerve terminals was blocked by desipramine, 10(-6) M. Estrogen also reduced the 3H-NA release evoked by exposure of the oviducts to 121 mM KC1 in the presence of calcium (2.5 mM) and in a high potassium, calcium-free medium upon the addition of 2.5 mM calcium. In the presence of desipramine a small fraction of 3H-NA was released in high potassium, calcium-free medium. This release was unaffected by estrogen. These results suggest that estrogen reduces the release of NA from the adrenergic nerves within the oviduct and that this action is exerted primarily on the calcium-dependent release. It therefore might be due to a reduction in the entry of calcium into the nerve terminal.

Adrenergic Fibers↗
PubMed1983

The glaucoma theory updated.

The natural history of splinter haemorrhages on the optic disc is an argument in favour of the belief that the glaucomatous process starts in the small vessels of the papilla. The probable existence of factors in the aqueous, whose generation depend on the state of oxygenation in the posterior parts of the eye and which affect the outflow resistance, supports the idea that the pressure increase is a secondary effect. Reduced perfusion by increased IOP or reduced blood pressure etc. is likely to accelerate a process already begun in the papilla.

Glaucoma↗
PubMed1982

Extrapulmonary effects of terbutaline during prolonged administration.

Hand tremor, heart rate, and electrolyte, plasma (pl) insulin, blood (bl) glucose, and pl terbutaline levels were measured in 11 healthy men during infusion and oral administration of terbutaline. Infusion of terbutaline (250 micrograms) was followed by increases in pl insulin concentration and bl glucose and by a decrease in pl K. Similar metabolic changes were seen on day 1 of oral terbutaline (5 mg x 3). Heart rate was moderately increased by terbutaline over the entire period (13 days) or oral dosing. Hand tremor always increased after terbutaline, but to a lesser degree on days 4 and 13 than after the first oral dose. On day 13 there was a very small increase in pl insulin and no reduction in pl K; bl glucose increased slightly from an elevated basal level. Pl terbutaline was of similar maximum concentrations on days 1 and 13, indicating that the tolerance was mediated through reduced response of the effector organs.

Adult↗
PubMed1982

Two new beta 2-adrenoceptor agonists, D-2343 and QH 25, studied in asthmatic patients.

Two new beta 2-adrenoceptor agonists, D-2343 and QH 25, have been studied in asthmatic patients. Animal experiments indicated less effect on skeletal muscle than on bronchial muscle. D-2343 (four i.v. cumulatively increasing doses, 0.21--6.3 micrograms kg-1 min-1) and i.v. terbutaline (four cumulative doses 0.07--2.1 micrograms kg-1 min-1) were single-blindly compared in a randomized crossover study in eight asthmatics. It was shown that D-2343 is an effective beta 2-adrenoceptor agonist with 5--6 times lower potency than terbutaline. The tremor-inducing effect of D-2343 was the same as that of terbutaline, when the same degree of bronchodilation was obtained. The effect of QH 25 (0.25, 0.75 and 2.25 mg cumulatively) administered orally, was single-blindly compared with the effect of oral salbutamol (2, 6 and 18 mg) in a randomized crossover study in eight asthmatics. QH 25 was shown to be an effective beta 2-adrenoceptor stimulant about 12 times more potent than salbutamol. The tremor-inducing capacity was the same as for salbutamol when equipotent bronchodilating doses were studied.

Adrenergic beta-Agonists↗
PubMed1982

Factors of importance for regulation of uterine contractile activity.

The myometrium of mammals consists of smooth muscle, having differing origin, structure and function. Isolated strips from human uterus show different patterns of contraction and different reactions to drugs if the strips are taken from different regions of the uterus. In the rat the myometrium is clearly separated in two layers - one outer longitudinal and one inner circular muscle. These two muscles show differing patterns of contraction. In the longitudinal layer there is a gradual increase in frequency and coordination of contraction towards the end of the gestation. The circular muscle contracts with high frequency and low amplitude until 3--4 days before delivery, when the contractions become more regular, less frequent and greater in amplitude. On day 21, immediately before parturition, spontaneous activity diminishes appreciably, but when delivery begins, strong, regular contractions are again evident. The electrical activity too differs in longitudinal vis-à-vis circular muscle; in the latter there are, as a pregnancy proceeds, characteristic changes in the action potentials. The changes in spontaneous contractions are not explained by changes in the overall ability of the muscle to contract, or of the calcium sensitivity of the muscles, but may be due to variations in the resting membrance potential. D-600, an agent known to reduce calcium influx, was found to reduce the contraction of circular muscle more than that of longitudinal muscle, whereas isoprenaline had a stronger inhibitory effect on the longitudinal than on the circular muscle.

Action Potentials↗