Biomedical subjects
Publications and source records attributed to B Bengtsson.
During 1977 and 1978 visual screening was performed in 1511 persons born 1907-1921 and taking part in a population survey. 8.4 years later the visual field screening was repeated in 2039 eyes of 1038 persons. The rates of unsuccessful tests improved or remained unchanged. The incidence of non-glaucomatous visual field defects was 0.006/year. Thus repeated visual field screening of persons in their seventies was both feasible and fruitful.
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Respiratory smooth muscle at different levels of the respiratory tract was isolated from rabbit, rat and guinea-pig and incubated with the Ca antagonists, verapamil, D-600, felodipine, and nifedipine. There was no effect of the Ca antagonists when added on top of an already developed contraction. When added before the contractile agent at high concentrations (10-100 microM) the Ca antagonists reduced the contractions. Lanthanum (2 mM) was considerably more effective to prevent contractions than the Ca antagonists. Preparations from the trachea and bronchus responded in all animals, whereas the third generation bronchus from rat and guinea-pig failed to contract and that from rabbit showed very weak contractions. The failure to contract was not specific for the agonist, as depolarization with isotonic potassium solution (124 mM) did not evoke contractions either. Microscopic investigation showed well-developed smooth muscle in the trachea and main bronchus of the rat, whereas the muscle of the third generation bronchus was inhomogenous with scattered groups of muscle cells.
The mechanical responses to potassium of the rabbit and rat uterus were different. The force of a potassium-induced contracture showed a rapid decline in the rabbit uterus, whereas it was fully maintained for a long period in the rat uterus. The increase in 45Ca influx following exposure to high KCl was substantial and similar (0.3 mmol kg-1) in both rat and rabbit uterus. Calcium uptake in post nuclear supernatant (PNS) from the rat myometrium was significantly lower than that from the rabbit myometrium in both the rate and capacity of uptake. This uptake was reduced to about 10% in the presence of sodium azide in PNS from both rat and rabbit myometria. Both the rate and capacity of calcium uptake by mitochondria isolated from PNS of rat myometrium were considerably lower than that by rabbit myometrial mitochondria. Microsomes isolated from rat and rabbit PNS had very low capacity for calcium uptake compared with mitochondria. No difference was found in the rate or the capacity of uptake between the rat and the rabbit myometrial microsomes. The data support the argument for a role of mitochondria in myometrial relaxation and further provide evidence for a considerable species difference in calcium uptake by myometrial mitochondria.
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The neuropeptide substance P (SP), which is released from sensory C-fibres after stimulation by chemical irritants. accelerates mucociliary activity in rabbit maxillary sinus in vivo. In order to investigate the mechanism behind this finding, we recorded ciliary beat frequency (CBF) in vitro from various respiratory explants by a photoelectric technique. It was noticed that ciliated cells from the maxillary sinus displayed a higher beating frequency than cells from the trachea and the bronchus, in that order. SP 10(-10)-10(-4) M did not influence the CBF in explants from rabbit maxillary sinus, rabbit trachea and main bronchi, guinea-pig trachea and human adenoids. Neurokinin A (NKA) 10(-6)-10(-5) M, which is also thought to be released from sensory C-fibres, did not influence the CBF in guinea-pig trachea. Neither did the C-fibre stimulant capsaicin 10(-8)-10(-4) M increase CBF in explants from human adenoids. The present findings indicate that the mucociliary effect of SP in vivo is not mediated by an effect on the cilia themselves.
The present study was performed to investigate the predictive value of casual blood pressure recordings for mortality in a geographically defined population (n = 1917), for which the primary health care services are responsible. Isotonic regression of blood pressure on age was used to define groups with low, medium and high blood pressure. In the age group 40 to 69 years mortality turned out to be a U-shaped function of blood pressure. In those aged 70 years and over blood pressure appeared to be of less importance as a risk indicator of death. The study has shown that a limited number of subjects in a defined population can be utilized in epidemiological studies of mortality as a function of blood pressure if an appropriate statistical method is used in the analyses, thereby justifying our model for studies in primary health care.
Concentrations of oxytetracycline (OTC) in serum and tissue-cage fluid (TCF) from subcutaneous tissue-cages were determined after single and repeated intravenous and intramuscular doses of 10 mg/kg to calves. Intravenous administration resulted in higher levels, and greater area under curve (AUC) in TCF, than did intramuscular administration. However, the penetration measured as the ratio of AUC in TCF to AUC in serum was equal, and therefore independent of the route of administration. A linear relationship between AUC in serum and AUC in TCF could be demonstrated. Half-lives of OTC in serum were 4.9 +/- 3.1 h after intravenous, and 6.1 +/- 2.0 h after intramuscular administration. In TCF the half-lives were 21.5 +/- 4.4 h and 24.5 +/- 11.5 h after intravenous and intramuscular administration, respectively. Repeated dosing resulted in accumulation of OTC in TCF. Lesser accumulation in older cages indicated altered characteristics of the cages with the passage of time. In serum, no substantial accumulation was seen after repeated i.v. dosing until the dosing interval was shortened to 6 h.
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Already existing data derived from two population surveys and the clinical records of a few 'ordinary' glaucoma patients in one and the same district were explored. Previous reports of a high prevalence of disc haemorrhage in chronic glaucoma were confirmed. The hypothesis that evident prepapillary vitreous opacities are more frequent in persons with glaucoma than in other persons was supported. Symptomatic vitreous detachment was the original reason for encounter in 5 out of 12 'selfselected' patients with chronic glaucoma. If a disc haemorrhage is found in a patient with a symptomatic vitreous detachment, early chronic glaucoma should be seriously considered even if there are no other glaucomatous signs.
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This study was performed to investigate whether a moderately sized population of men (n = 954) living in a geographically defined area could be utilized and give valid results in a 13-year prospective study regarding mortality as a function of blood pressure. Isotonic regression of blood pressure on age was used to define groups of men with low, medium, and high blood pressure. Men aged 40-69 years in both extreme groups showed an excess death risk in comparison with those in the medium group. Thus, mortality appeared to be a U-shaped function of blood pressure in this age group. The mortality ratios of the low and high blood pressure groups vis-à-vis the medium group were higher during the first than during the second half of the observation period. Chronic diseases at the time of the initial examination were more common among men who died in the lowest blood pressure group than among those who died in the medium group. In males aged 70-99 years, blood pressure appeared to be of less importance as a risk indicator of death.
The influence of theophylline and the related drug caffeine on the mechanical performance of fatigued muscle fibre isolated from semitendinosus muscle of Rana temporaria (2.5-6.7 degrees C) was investigated. The fibre was stimulated supramaximally to produce I s fused tetani and 2 s and 10 s partially fused tetani at intervals of 10 min. Fatigue was produced by shortening the contraction interval to 15 and 30 s. This caused a 15-20% decline in the maximum tension during fused tetanus and a 40-50% decline during partially fused tetanus. Theophylline and caffeine (0.1-0.5 mM) did not change the maximum tension developed by the fatigued fibre during fused tetanization. Both drugs, however, markedly increased the tension output of the fatigued muscle fibre during partially fused tetanus. It was observed that the increase in partially fused tetanic tension by theophylline and caffeine was associated with an increase in the degree of fusion. This later effect was even more pronounced in the presence of diethyl-stilboestrol. It is concluded that these drugs may not reverse the metabolic changes caused by fatigue, since they are unnable to increase fused tetanic force of a fatigued muscle fibre. The increase in partially fused tetanic tension of a fatigued muscle fibre by these drugs is probably due to enhancement of the activator calcium release from the sarcoplasmic reticulum in response to stimulation.
Contractions were evoked in isolated strips of rat trachea by potassium and acetylcholine (ACh) respectively. Extracellular calcium (Ca) was removed by EGTA and Ca influx was inhibited by diethylstilboestrol (DES). Contractions evoked by potassium were completely inhibited in the presence of EGTA or DES. ACh-induced contractions were rapidly abolished by EGTA whereas DES did not completely block these responses when a high concentration of ACh (10(-4) M) was used. Repeated activation by ACh in the presence of DES displayed two different phases of the contractile response; one initial brief contraction that decreased only slowly in the presence of DES, and a second phase with sustained contraction that was more readily depressed by DES. It is suggested that the smooth muscle in rat trachea is activated by Ca originating both intra- and extracellularly. As EGTA almost immediately blocked even the initial contractile response, the intracellular store is apparently located in or very close to the plasma membrane.
The fractional release of [3H]noradrenaline was measured in rings from the rat trachea. Transmitter release was induced either by isotonic KCl (124 mM) or by 2.5 mM Ca added to a Ca-free depolarizing solution. Felodipine, a Ca antagonist (10(-4)M), had no effect on the basal release of [3H]NA whereas it reduced the overflow of transmitter caused by KCl or Ca. Diethyl-stilboestrol (25 microM), which also inhibits Ca influx in smooth muscle, had a stronger inhibitory effect than felodipine on [3H]NA release induced by high K and addition of Ca. Basal efflux of [3H]NA was increased by diethyl-stilboestrol. This increase also occurred in the absence of extracellular Ca.