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Biomedical subjects

E Svensson

Publications and source records attributed to E Svensson.

97 records · Page 6Linked to original sources
PubMed1976

Sex-specific occurrence of androgen receptors in rat brain.

The metabolism and binding of [1, 2, 6, 7-3H] testosterone in male and female rat brain has been studied in an attempt to find an explanation for the relative androgen unresponsiveness characterizing the female hypothalamo-pituitary axis involved in regulation of hepatic steroid metabolism. The most significant sex differences in the pattern of [3H] testosterone metabolites recovered from several brain regions (including pituitary, pineal gland, and hypothalamus) after intraperitoneal administration of [3H] testosterone were the predominance of testosterone and androstenedione in male brain compared to the quantitative importance of 5alpha-androstane-3alpha, 17beta-diol, 5alpha-androstane-3beta, 17beta-diol, epitestosterone, and dihydroepitestosterone in female brain. One possible explanation for the androgen unresponsiveness of female rats is, therefore, the faster metabolism of testosterone to inactive compounds in female brain. Experiments both in vivo and in vitro showed the presence of high affinity, low capacity binding sites for [3H] testosterone in male pituitary, pineal gland, and hypothalamus (Kd values in the region of 1 X 10(-10) to 1 X 10(-9) M and number of binding sites 1.0 to 1.4 X 10(-14) mol per mg of protein). The steroid - macromolecular complexes generally had a pI of 5.1, were excluded from Sephadex G-200, were heat-labile, and were sensitive to protease. Competition experiments indicated the following order of ligand affinities: testosterone is greater than 5alpha-dihydrotestosterone and estradiol is greater than androstenedione is greater than corticosterone. No steroid-binding proteins of similar nature were found in pituitary, pineal gland, or hypothalamus from female rats. On the basis of these results it is suggested that the androgen unresponsiveness of female rats referred to above relates to the absence of receptor protein for androgens in female rat brain. In support of this hypothesis, 28-day-old female rats, which are known to be affected by androgens with regard to liver enzyme activities, were shown to contain receptor proteins for androgen in the brain. In conclusion, the relative androgen unresponsiveness of the female hypothalamo-pituitary axis is probably explained by the absence of receptor proteins for androgen in female hypothalamus and pituitary. The fast metabolism of testosterone in female rat brain also serves to decrease the availability of active androgen to potential receptor sites. It may be speculated that the presence of androgen receptors in male brain is the result of neonatal programming ("imprinting") by testicular androgen.

Animals↗
PubMedDate not supplied

Separation of systematic and random differences in ordinal rating scales.

We introduce a new statistical method, which separates and measures different types of variability between paired ordered categorical measurements. The key to the separation is a two-way augmented ranking approach of observations in a contingency table. It means that cases classified in a specific category by one rater will be internally ranked according to the classifications from the other. This enables us to extract the component of interobserver variation which is not systematic. The variance of the rank differences between judgements is a suitable measure of this interrater variability, which we characterize as random. The empirical measure of random interjudge disagreement, which lies between 0 and 1, is called the relative rank variance and is an estimate of a parameter defined on the multinomial probability distribution in the contingency table. The systematic differences are determined by the marginals and described by two empirical measures, relative position and relative concentration; both measures lie between -1 and 1. Our method is applied to data sets from a reliability study of two clinical rating scales for assessing hydrocephalus and subarachnoid haemorrhage.

Data Interpretation, Statistical↗
PubMedDate not supplied

A health education program for elderly persons with visual impairments and perceived security in the performance of daily occupations: a randomized study.

OBJECTIVE: The purpose of this randomized, longitudinal study was to investigate the impact of a health education program on perceived security in the performance of daily occupations 4 months after the intervention period. METHOD: Two groups of persons with age-related macular degeneration were compared: Those who had followed a newly developed health education program that was based on occupation and those who took part in a standard individual intervention program. RESULTS: Significant differences in the level of perceived security between the groups were found for 13 of 28 occupations. Participants in the health education group maintained or improved their level of perceived security in 22 daily occupations, whereas those in the individual intervention group declined to a lower level in 17 daily occupations. CONCLUSION: This study provides support for the effectiveness of the health education program to enhance security and hinder a progressive decline in perceived security in daily occupations.

Aged↗
PubMedDate not supplied

Degradation in peritoneal dialysis fluids may be avoided by using low pH and high glucose concentration.

OBJECTIVE: When glucose is present in a medical fluid, the heat applied during sterilization leads to degradation. The glucose degradation products (GDPs) give rise to bioincompatible reactions in peritoneal dialysis patients. The extent of the degradation depends on a number of factors, such as heating time, temperature, pH, glucose concentration, and catalyzing substances. In the present work, we investigated the influence of pH and concentration in order to determine how to decrease the amounts of GDPs produced. DESIGN: Glucose solutions (1%-60% glucose; pH 1-8) were heat sterilized at 121 degrees C. Ultraviolet (UV) absorption, aldehydes, pH, and inhibition of cell growth (ICG) were used as measures of degradation. RESULTS: Glucose degradation was minimum at an initial pH (prior to sterilization) of around 3.5 and at a high concentration of glucose. There was considerable development of acid degradation products during the sterilization process when the initial pH was high. Two different patterns of development of UV-absorbing degradation products were seen: one below pH 3.5, dominated by the formation of 5-hydroxy-methyl-2-furaldehyde (5-HMF); and one above, dominated by degradation products absorbing at 228 nm. 3-Deoxyglucosone (3-DG) concentration and the portion of 228 nm UV absorbance not caused by 5-HMF were found to relate to the in vitro bioincompatibility measured as ICG; there was no relation between 5-HMF or absorbance at 284 nm and bioincompatibility. CONCLUSION: In order to minimize the development of bioincompatible GDPs in peritoneal dialysis fluids during heat sterilization, pH should be kept around 3.2 and the concentration of glucose should be high. 5-HMF and 284 nm UV absorbance are not reliable as quality measures. 3-DG and the portion of UV absorbance at 228 nm caused by degradation products other than 5-HMF seem to be reliable indicators of bioincompatibility.

Acetaldehyde↗