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Biomedical subjects

P Magnus

Publications and source records attributed to P Magnus.

190 records · Page 11Linked to original sources
PubMed1981

Genetics of the low density lipoprotein receptor: III. Evidence for multiple normal alleles at the low density lipoprotein receptor locus.

Fibroblast association (plasma membrane binding plus intracellular accumulation) and degradation of radioiodinated low density lipoprotein (125I-LDL) index plasma membrane LDL receptor activity. Cultured fibroblasts from 23 subjects affected with familial hypercholesterolemia (HC) and from 95 subjects without HC (non-HCs) were tested for 125I-LDL association and degradation. Both LDL receptor activity indices were twice as high in non-HC and HC heterozygous cell strains. This is compatible with a major gene effect on LDL receptor activity. However, a considerable overlap between non-HC and HC heterozygous values was found in the 125I-LDL association assay [median (range) 970 (330-2500), and 450 (250-490), respectively] and in the degradation assay [median (range) 810 (280-2020), and 470 (160-790), respectively]. The values are expressed as ng 125I-LDL X mg cell protein-1 X 4.5 h-1. These great overlaps in the LDL receptor activity indices support the view that the influence of LDL receptor activity on the HC phenotype may be smaller than believed previously. Furthermore, for the diagnosis of HC, these LDL receptor activity assays are far more expensive and have less sensitivity and specificity than simple serum cholesterol determination. The LDL receptor-dependent 125I-LDL association values for the HC heterozygous individuals clustered into four groups. Family data supported the hypothesis that this variation could be due to four different LDL receptor variants, each coded for by different alleles at the LDL receptor locus. If confirmed, this finding may have implications for the understanding of the variable expression of HC and also of the genetic impact on lipoprotein metabolism and susceptibility to atherosclerosis in non-HCs.

Adolescent↗
PubMed1980

Myofascial pain dysfunction (MPD) syndrome in twins.

The Myofascial Pain Dysfunction Syndrome (MPD) was investigated in 94 twin pairs (21 male pairs and 73 female pairs), who had not been selected with respect to MPD. The frequency of past and/or present symptoms was found to be 10% in males and 27% in females. No differences between monozygous (identical) and dizygous (non-identical) female twins was found in pair-wise concordance rates, the concordance rate being higher than expected to occur by chance in both twin types. The findings are compatible with the view that environmental influences give rise to this specific stress-reaction pattern.

Diseases in Twins↗
PubMed1980

Circadian rhythmicity of the urinary excretion of mercury, potassium and catecholamines in unconventional shift-work systems.

The round the clock urinary excretion rates of mercury were assessed for two series of unconventional patterns of activity and sleep in subjects who were not exposed to occupational, medical, or other obvious sources of mercury. In the first series the urine was collected in 3-h periods from six subjects during the first and last 2 d of a four-week, continuous 6-h shift (car ferry, watches either 0800--1400 and 2000--0200 or 1400--2000 and 0200--0800). In the second series the urine was collected in 4-h periods from five subjects working an 8-h experimental rotation shift compressed into 5 d (work two mornings--8-h interval--work two nights--8-h interval--work two afternoons). The mean daily excretion rate of the 11 subjects (48 investigation days, 334 urine samples) was 14.5 pmol of mercury/min (range 5.5--24.4 pmol of mercury/min). The mercury excretion oscillated regularly during 24 h by +/- 20--25% of the individual's daily mean excretion rates. The peak excretion rates were found at 0652 in the first and 0642 in the second series (cosinor treatment). Due to the circadian rhythm the mean 24-h excretion rates were best represented (correlation coefficient 0.92) by analyses of urine produced around noon (spot samples, collection periods 1100--1400 and 1000-1400, respectively). The circadian oscillations of mercury excretion were not influenced by the widely different and varying activity-sleep patterns of the two series. The rhythmicity of potassium excretion (peaks at around 1400) was more irregular. The stable oscillations of mercury excretion contrasted most with the excretion of adrenaline and noradrenaline, which, without losing the basic 24-h rhythmicity, closely followed the unconventional patterns of activity and sleep.

Adult↗
PubMedDate not supplied

Education policy and the heritability of educational attainment.

Many workers assume that genetically determined differences in intellectual ability will be influenced little by changes in educational policy or other environmental interventions. Others, however, have suggested that increasing equality of educational opportunity will lead to an increase in the heritability of educational attainment. The resolution of this issue has been delayed until now because of the extremely large sample sizes which would be required. Education data on twins and their parents, from the Norwegian twin panel, provide a unique opportunity to determine the impact on the heritability of educational attainment of the more liberal social and educational policies introduced in Norway after the Second World War. As reported here, for individuals born before 1940 there is a strong effect of family background on educational attainment, accounting for 47% of the variance, though genetic factors account for an additional 41% of the variance. For females born after 1940 and before 1961, the relative importance of genetic (38-45%) and familial environmental (41-50%) differences changes very little. For males born during the same period, the broad heritability of educational attainment has increased substantially (67-74%), and the environmental impact of family background has correspondingly decreased (8-10%). For males, at least, having well-educated parents no longer predicts educational success, as measured by duration of education, independent of the individual's own innate abilities.

Achievement↗
PubMedDate not supplied

Correlations of birth weight and gestational age across generations.

Maternal birth weight is known to be a predictor of offspring birth weight. Less is known about the recurrence of gestational age. In order to estimate the recurrence risk of low birth weight and preterm birth across generations in a population-based sample, 11,092 pairs of mother-firstborn offspring were obtained through an internal linkage in the Norwegian Birth Registry based on the years 1967-1969 (mothers) and 1986-1989 (offspring). A low correlation coefficient of 0.086 was found for gestational age across generations, whereas the correlation between maternal and offspring birth weight was 0.242. Mothers with birth weight below 2500 g had a significantly increased risk (odds ratio = 3.03, 95% conf. interval 1.79-5.11) of having a low birth weight child compared with mothers with birth weight above 4 kg. On the other hand, if the mother was born before the 37th completed week of gestation, the risk of having a preterm child was not significantly increased (odds ratio = 1.46, conf. interval 0.96-2.21) compared with mothers who were born at term. Thus, in contrast to birth weight, human variation in gestational age does not appear to be influenced by genetic factors to any large degree.

Adult↗
PubMedDate not supplied

Hair nicotine concentrations in mothers and children in relation to parental smoking.

The health effects of environmental tobacco smoke (ETS) exposure constitute a main public health problem. Lack of presice methods for assessing personal tobacco smoke exposure, makes it difficult to estimate the health effects of such exposure. Measuring hair nicotine concentrations could be an improvement in the assessment of personal tobacco smoke exposure. The objective of the present study was to estimate quantitatively the relation between hair nicotine concentrations in mothers and children and tobacco smoke exposure assessed by questionnaires. Mothers' and children's hair nicotine concentrations in the proximal 2 cm of hair were measured in 94 families with children 12-36 months of age: 25 nonsmoking families, 40 families with one smoking parent, and 29 families with both parents smoking. Questionnaire information on tobacco smoke exposure was collected from the same families. In multivariate linear regression analysis, children's nicotine levels were linearly related to daily number of cigarettes smoked at home by both mothers (0.8 mg/g increase per cigarette, 95% confidence interval [CI] 0.43-1.18), and fathers (1.3, 0.81-1.73). Mothers' nicotine levels were linearly related to both personal smoking (2.7, 1.75-3.55) and fathers' smoking at home (2.1,0.74-3.49). Hair nicotine seems to be a good quantitative measure of exposure to tobacco smoke during the previous months both among active and passive smokers. The non-invasive and simple collection procedure makes the method especially suitable for estimating tobacco smoke exposure in children.

Child, Preschool↗