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Biomedical subjects

J Olsen

Publications and source records attributed to J Olsen.

At least 109 records · Page 6Linked to original sources
PubMed2000

Molecular aspects of beta-ketoacyl synthase (KAS) catalysis.

Crystal structure data for Escherichia coli beta-ketoacyl synthase (KAS) I with C(10) and C(12) fatty acid substrates bound in conjunction with results from mutagenizing residues in the active site leads to a model for catalysis. Differences from and similarities to the other Claisen enzymes carrying out decarboxylations reveal two catalytic mechanisms, one for KAS I and KAS II, the other for KAS III and chalcone synthase. A comparison of the structures of KAS I and KAS II does not reveal the basis of chain-length specificity. The structures of the Arabidopsis thaliana KAS family are compared.

3-Oxoacyl-(Acyl-Carrier-Protein) Synthase↗
PubMed2000

Birthweight and semen characteristics.

A correlation between birthweight and sperm counts in adult life was anticipated because impaired fetal growth could impair replication of Sertoli cells produced in fetal life. Furthermore, it was expected that males born with a high birthweight might have impaired sperm production as they are expected to have been exposed to higher levels of oestrogen in fetal life. We examined these predictions by including midwives records for 296 Danish males that had taken part in studies on male fecundity for other reasons. The study provided no support for these expectations. If anything, males born with a birthweight of 3000-3999 g had slightly lower sperm counts and more abnormal spermatozoa.

Birth Weight↗
PubMed2000

Diurnal scrotal skin temperature and semen quality. The Danish First Pregnancy Planner Study Team.

It is well established that heat is associated with reduced sperm production, but the role of physiological variation in temperature has never been scrutinized in humans. We studied diurnal scrotal temperature and markers of male fertility in a population of couples planning their first pregnancy. Sixty men from a cohort of couples who were planning their first pregnancy were included and scrotal skin temperature was monitored during 3 days using a portable data recorder. Working hours and working postures were recorded daily in a questionnaire. Each man provided a fresh semen sample and the couples were followed for six menstrual cycles or until a clinical pregnancy was recognized. The median value of scrotal skin temperature was 33.3 degrees C in the daytime and 34.8 degrees C at night. In periods of sedentary work, the median temperature was on average 0.7 degrees C higher (SE=0.2 degrees C). In addition, scrotal temperature was higher in the daytime, in summer, and in leisure time compared with working hours. Median sperm concentration among men with more than 75% of their daytime readings above 35 degrees C was 33.4 x 10(6)/mL, compared with 91.8 x 10(6)/mL for men with less than half of their readings above 35 degrees C (difference 58.4; 95% CI: 25.9-77.8 x 10(6)/mL). It is concluded that a sedentary position is a significant source of increased scrotal skin temperature, and even moderate and physiological elevation in scrotal skin temperature is associated with a substantially reduced sperm concentration. Sedentary work should be considered as an important potential confounder for reduced sperm count in epidemiological research.

Circadian Rhythm↗
PubMed2000

Pregnancy outcome following prescription for sumatriptan.

BACKGROUND: Some 2.5% of fertile Danish women use sumatriptan, and the drug is also taken during pregnancy. Although sumatriptan reacts selectively in brain vessels, the possibility of reactions with placental blood flow and uterotonic activity cannot be ruled out. The aim of our study was to examine the association between sumatriptan exposure during pregnancy and the risk of preterm delivery and low birth weight. METHODS: Data from the Pharmaco-Epidemiological Prescription Database of North Jutland county regarding all women who had given birth in the county of North Jutland from 1991 to 1996 were linked to the Danish Medical Birth Registry. Women who were exposed to sumatriptan during pregnancy were identified (n = 34), and using logistic regression models their pregnancy outcome was compared with two groups of pregnant women: (1) healthy women (n = 15 955) and (2) migraine controls (n = 89), defined as migraine patients who did not redeem prescriptions for migraine treatment during pregnancy. RESULTS: The risk of preterm delivery was elevated among women exposed to sumatriptan compared with migraine controls (odds ratio [OR] 6.3, 95% confidence interval [CI] 1.2-32.0) and healthy women (OR 3.3, 95% CI 1.3-8.5). The odds ratio for having a newborn with a low birth weight was increased (OR 3.0, 95% CI 1.3-7.0) for all migraine patients who delivered at term (n=115) compared with the outcome of healthy pregnancies. CONCLUSIONS: We found that sumatriptan exposure during pregnancy was associated with an increased risk of preterm delivery and low birth weight. These findings may be due to drug exposure, but they may also reflect the impact of disease severity rather than the treatment itself, or confounding, or chance.

Adult↗
PubMed2000

A teratological study of aminoglycoside antibiotic treatment during pregnancy.

The aim of this study was to investigate the teratogenicity of aminoglycoside antibiotics, such as parenteral gentamicin, streptomycin, tobramycin and oral neomycin, during pregnancy. Pair analysis of cases with congenital abnormalities and matched healthy controls was carried out. The setting was the population-based dataset of the Hungarian Case-Control Surveillance of Congenital Abnormalities, 1980-96. In total, 38,151 pregnant women who had newborn infants without any defects (control group) and 22,865 pregnant women who had foetuses or newborns with congenital abnormalities were included in the study. 38 (0.16%) and 42 (0.11%) pregnant women in the case and control groups, respectively, were treated with the aminoglycosides studied. A teratogenic potential of gentamicin and neomycin was not indicated by a comparison of the occurrence of aminoglycoside antibiotic treatments in the total control group as referent with the figures of different congenital abnormality groups. In addition, the case-control pair analysis during the second-third months of pregnancy did not show a teratogenic risk of gentamicin and neomycin. The conclusion of this study is that treatment with parenteral gentamicin and oral neomycin during pregnancy presents no detectable teratogenic risk to the foetus, when restricted to structural developmental disturbances.

Abnormalities, Drug-Induced↗
PubMed2000

Risk of spontaneous abortion following induced abortion is only increased with short interpregnancy interval.

We set out to study the risk of spontaneous abortion following a first trimester induced abortion as a function of the interpregnancy interval between two pregnancies. The cohort study is based on the following databases: Danish national registries: the Medical Birth Registry (MBR), the Hospital Discharge Registry (HDR), and the induced Abortion Registry (IAR). All primigravid women in the time period from 1980 to 1982 were identified in the MBR, the HDR and the IAR. A total of 15 727 women who terminated the pregnancy with a first trimester induced abortion were selected as the induced abortion cohort, and 46 026 women who did not terminate the pregnancy with an induced abortion constituted the control cohort. By register linkage all subsequent pregnancies which were not terminated by induced abortion were identified from 1980 to 1994. Only women who had a non-terminated pregnancy following the index pregnancy were selected. Women whose first pregnancy was terminated following a first trimester induced abortion had a risk of spontaneous abortion of 11.0% vs. 9.4% in the control cohort. This relative difference of 1.17 was not statistically significant in logistic regression analyses. An increased risk was only found for women who had an interpregnancy interval of less than 3 months (OR=4.06, 95% C.I.=1.98-8.31). The abortion method, vacuum aspiration with dilatation or evacuation with dilatation did not modify this elevated risk. Overall the study did not show an increased risk of spontaneous abortion following one or more induced abortions, except for women with a short interpregnancy interval between an induced abortion and a subsequent pregnancy. We recommend women who have a first trimester induced abortion be advised to wait at least 3-6 months before trying to become pregnant again.

Journal Article↗
PubMed2000

No strong long-term effect of vitamin A supplementation in infancy on CD4 and CD8 T-cell subsets. A community study from Guinea-Bissau, West Africa.

The World Health Organization recommends that 100,000 IU of vitamin A be given to infants between 6 and 12 months of age at the same time as measles vaccination in order to prevent vitamin A deficiency. In the present study, our aim was to assess the effect of vitamin A supplementation on T-cell subsets in a randomized factorial design, seeking a possible modifying effect of measles vaccination. Three hundred children were allocated either to two doses of measles vaccine at 6 and 9 months of age or to poliomyelitis vaccine at age 6 months and measles vaccine at age 9 months. Within each group, infants were to receive two doses of vitamin A or two doses of placebo at 6 and 9 months of age. We found no significant effect of vitamin A supplementation on CD4 and CD8 T-cell subsets at 3 and 9 months after supplementation. We found no effect of measles vaccine and no interaction between vitamin A supplementation and measles vaccine. Based on these observations, vitamin A supplementation does not seem to have a strong long-term effect on CD4 and CD8 T-cell subsets in infants without clinical vitamin A deficiency.

CD4-CD8 Ratio↗
PubMed2000

Fetal growth and blood pressure in a Danish population aged 31-51 years.

During the past decade, studies have shown an inverse association between birth weight and blood pressure and risk of coronary heart disease in adult life. From old public archives we were able to trace the birth records of 545 out of 905 persons (60.2%) aged 31-51 years who participated in the Ebeltoft Health Promotion Project in Denmark. We examined the associations between birth weight, length at birth, Ponderal Index and systolic and diastolic blood pressure. No associations were found for women. For men, the mean systolic blood pressure fell from 131.1 mmHg with a birth weight of less than 3300 g to 129.6 mmHg with a birth weight of more than 4000 g, and for diastolic blood pressure 81.6 mmHg to 80.3 mmHg, respectively. For men, the mean systolic blood pressure fell from 135.7 mm Hg with a birth length of 30-51 cm to 131.6 with a birth length of 55-62 cm, and for diastolic blood pressure 83.0 mmHg to 78.8 mmHg, respectively. The associations may reflect organ programming in fetal life.

Adult↗
PubMed2000

Induced abortion and low birthweight in the following pregnancy.

BACKGROUND: To examine whether induced abortion increases the risk of low birthweight in subsequent singleton live births. METHODS: Cohort study using the Danish Medical Birth Registry (MBR), the Hospital Discharge Registry (HDR), and the Induced Abortion Registry (IAR). All women who had their first pregnancy during 1980-1982 were identified in the MBR, the HDR, and the IAR. We included all 15,727 women whose pregnancy was terminated by a first trimester induced abortion in the induced abortion cohort and 46,026 women whose pregnancy was not terminated by an induced abortion were selected for the control cohort. All subsequent pregnancies until 1994 were identified by register record linkage. RESULTS: Low birthweight (<2500 g) in singleton term live births occurred more frequently in women with one, two, three or more previous induced abortions, compared with women without any previous induced abortion of similar gravidity, 2.2% versus 1.5%, 2.4% versus 1.7%, and 1.8% versus 1.6%, respectively. Adjusting for maternal age and residence at time of pregnancy, interpregnancy interval, gender of newborn, number of previous spontaneous abortions and number of previous low birthweight infants (control cohort only), the odds ratios (OR) of low birthweight in singleton term live births in women with one, two or more previous first trimester induced abortions were 1.9 (95% CI: 1.6, 2.3), and 1.9 (95% CI: 1.3, 2.7), respectively, compared with the control cohort of similar gravidity. High risks were mainly seen in women with an interpregnancy interval of more than 6 months. CONCLUSIONS: The findings suggest a positive association between one or more first trimester induced abortions and the risk of low birthweight in subsequent singleton term live births when the interpregnancy interval is longer than 6 months. This result was unexpected and confounding cannot be ruled out.

Abortion, Induced↗
PubMed2000

Time to pregnancy as a correlate of fecundity: differential persistence in trying to become pregnant as a source of bias.

BACKGROUND: Subfecundity is a frequent and often serious problem and it is important to identify its preventable determinants and to monitor fecundity over time. Since follow-up studies are difficult and expensive to conduct, time to pregnancy (TTP) in pregnant women is often used as a surrogate measure of fecundity. TTP data can be retrieved at low costs and they need no valid population registry as a source for sampling. While TTP may serve as a valid surrogate measure in many situations, its validity rests upon a number of assumptions. We have analysed one of these overlooked assumptions, the importance of persistence in trying to become pregnant. METHODS: By means of computer simulations we estimated bias caused by differences in persistence in pregnancy attempts. We investigated whether the assumptions made in the simulation were realistic by using empirical data from a European study. RESULTS: The mean waiting time to pregnancy and other estimates of subfecundity (or infertility) strongly depend upon the persistence of couples in pursuing a pregnancy. We show that even moderate changes in the planning behaviour considerably modify the waiting time distribution. Empirical data confirm that persistence in trying to become pregnant is age-related. CONCLUSIONS: Persistence in pregnancy attempts affects outcome measures of subfecundity in studies based upon TTP in pregnant women. It is likely that the length of time during which couples keep trying to become pregnant is influenced by a number of factors which would probably change over time or be different between populations to be compared.

Adult↗
PubMed2000

Spontaneous abortion and physical strain around implantation: a follow-up study of first-pregnancy planners.

Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short time periods are the relevant measure. We followed a cohort of first pregnancy planners from termination of birth control until pregnancy for a maximum of six menstrual cycles. The analyses include 181 pregnancies, of which 32 were subclinical pregnancies detected by hCG analysis only. During early pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date of ovulation was 2.5 (95% CI = 1.3-4.6).

Abortion, Spontaneous↗
PubMed2000

Antidepressant medications and risk for cancer.

Antidepressants appear to promote tumor growth in experimental studies; however, results from epidemiologic studies are inconclusive. We used a population-based cohort study to estimate the incidence of cancer after antidepressant treatment in 39,807 adult users of antidepressants identified in the Prescription Database of the County of North Jutland, Denmark between January 1, 1989 and December 31, 1995. Information on cancer occurrence was obtained from the Danish Cancer Registry. We categorized exposure according to use of tricyclic antidepressants, tetracyclic antidepressants, selective serotonin reuptake inhibitors, or monoamine oxidase inhibitors. In the follow-up period beginning 1 year after first known prescription, there were 966 cancers among users of antidepressants; our population estimate suggested an expected number of 946 for an overall standardized incidence ratio of 1.0 (95% confidence interval = 1.0-1.1). Users of tricyclic antidepressants had an excess of non-Hodgkin's lymphoma, with the risk increasing with the number of prescriptions of tricyclic antidepressants. The standardized incidence ratio was 2.5 (95% confidence interval, 1.4-4.2) for those with five or more prescriptions. Our results provide little evidence that antidepressants promote cancer at other sites, except for a possible effect of tricyclic antidepressants and tetracyclic antidepressants on non-Hodgkin's lymphoma.

Antidepressive Agents↗
PubMed2000

Low birth weight and preterm delivery as risk factors for asthma and atopic dermatitis in young adult males.

Gestational factors have been hypothesized to play a role in the susceptibility to asthma and atopic dermatitis. We examined whether fetal growth was associated with asthma and atopic dermatitis separately in a population of 4,795 male conscripts born between 1973 and 1975 in Denmark. The prevalence of asthma was 4.7%. The prevalence odds ratio of asthma in conscripts with a birth weight below 2,501 g was 1.5 (95% confidence interval = 0.7-3.1) compared with conscripts with a birth weight of 3,001-3,500 g, adjusted for gestational age and potential confounders. The adjusted prevalence odds ratio among conscripts born before 34 gestational weeks was 0.8 (95% confidence interval = 0.3-2.0) compared with conscripts born at term. The prevalence of atopic dermatitis was 1.0%. The prevalence odds ratio of atopic dermatitis among those with a birth weight below 2,501 g was 3.0 (95% confidence interval = 0.8-11.9) compared with those whose birth weight was between 3,001 and 3,500 g. Men whose gestational age had been below 34 weeks had an adjusted prevalence odds ratio of 0.3 (95% confidence interval = 0.0-3.1). These findings indicate that fetal growth retardation rather than preterm delivery of male infants is the main gestational factor underlying the associations but does not explain the apparent increase over time of asthma or atopic diseases.

Adult↗
PubMed2000

Handedness and mortality: a follow-up study of Danish twins born between 1900 and 1910.

The declining prevalence of left-handed individuals with increasing age has led to two main avenues of hypotheses; the association is due either (1) to a birth cohort effect and/or an age effect caused by a switch to right-handedness with advancing age or (2) to mortality selection that reduces survival in left-handed individuals, or both. It is uncertain whether a cohort or age effect can explain the decline in age-related prevalence, and conflicting evidence exists in favor of the mortality hypothesis. We compared mortality in a subgroup of 118 opposite-handed twin pairs by counting in how many instances the right-handed twin died first. There was no evidence of differential survival between right-handed and non-right-handed individuals in the entire 1900-1910 cohort. With respect to the number of right-handed twins who died first, there was no material disadvantage among those who were not right-handed. In 60% (95% confidence interval = 49.0-71.5%) of dizygotic pairs, the right-handed twins died first. In 50% of monozygotic pairs, right-handed twins died first. The prevalence of not being right-handed was higher among males (9.2%) than females (6.5%); there was a similar frequency of non-right-handedness in monozygotic (8.0%) and dizygotic (7.8%) twins. We did not find evidence of excess mortality among non-right-handed adult twins in this follow-up study.

Cause of Death↗
PubMed2000

Effect of home and hospital delivery on long-term cognitive function.

We examined the relation between place of birth and cognitive function in young adult life in a historical cohort study based upon birth data from the computerized Danish Medical Birth Registry and cognitive function as measured at time of drafting for military service in two Danish counties. The cohort included 4,296 Danish conscripts born between 1973 and 1976, 123 born at home and 4,173 born in hospital or at a birth clinic. Cognitive function was measured by the Boerge Prien test in men, 18 to 20 years of age. The highest possible score is 78. The mean Boerge Prien test score was 43.1 for conscripts born in specialized hospital departments, 2.4 higher for conscripts born in a birth clinic (95% confidence interval = 0.9-4.0), and 2.1 lower for conscripts born at home (95% confidence limits = -3.8 to -0.4) after adjusting for birth weight, length at birth, birth order, gestational age, maternal age, and marital and occupational status. Our findings raise the possibility that home birth can lead to lower cognitive function in adulthood; however, from our data we could not distinguish between planned and unplanned births at home.

Adult↗