Biomedical subjects

J H Petersen

Publications and source records attributed to J H Petersen.

At least 19 recordsLinked to original sources

PubMed2002

Safety and quality of food contact materials. Part 1: evaluation of analytical strategies to introduce migration testing into good manufacturing practice.

The results of a research project (EU AIR Research Programme CT94-1025) aimed to introduce control of migration into good manufacturing practice and into enforcement work are reported. Representative polymer classes were defined on the basis of chemical structure, technological function, migration behaviour and market share. These classes were characterized by analytical methods. Analytical techniques were investigated for identification of potential migrants. High-temperature gas chromatography was shown to be a powerful method and 1H-magnetic resonance provided a convenient fingerprint of plastic materials. Volatile compounds were characterized by headspace techniques, where it was shown to be essential to differentiate volatile compounds desorbed from those generated during the thermal desorption itself. For metal trace analysis, microwave mineralization followed by atomic absorption was employed. These different techniques were introduced into a systematic testing scheme that is envisaged as being suitable both for industrial control and for enforcement laboratories. Guidelines will be proposed in the second part of this paper.

Chromatography, Gas↗

PubMed2002

Time to pregnancy in relation to semen quality assessed by CASA before and after sperm separation.

BACKGROUND: In order to provide a reference for infertile men, we defined normal values of semen quality in a population of fertile men, using computer-assisted semen analysis (CASA) before and after sperm separation. Additionally, we investigated the relationship between semen quality and time to pregnancy (TTP). METHODS AND RESULTS: Semen samples were obtained from 315 proven fertile men. The median sperm concentration in fresh samples was 107 x 10(6)/ml (5-95 percentiles: 16-322 x 10(6)/ml), the median percentage of motile sperm cells was 65% (14-87%) and the median percentage of progressively motile cells was 37% (5-64%). After density gradient sperm separation, the median total sperm count was 46 x 10(6) (4-350 x 10(6)), the median percentage of motile sperm cells was 77% (16-95%) and the median percentage of progressively motile cells was 63% (11-84%). No significant associations were found between TTP and sperm counts or sperm motility, either before or after sperm separation. This may be due in part to the fact that the study comprised couples with proven fertility. CONCLUSION: We have defined semen parameters, including the results of density gradient separation, in a population of normal fertile men which may be of interest in the evaluation of semen samples from infertile men.

Adult↗

PubMed2001

Unusual Multilayer Surface Alloy: Al(100)-c(2 x 2)-2Li.

An unusual multilayer surface alloy is formed by adsorption of one monolayer Li on Al(100). It is shown by low energy electron diffraction that the first three layers consist of a mixed Al-Li layer, a pure Al layer, and a second Al-Li layer. Thus the alloy has the same layer stoichiometry as the (100) surface of the metastable Al(3)Li bulk alloy. However, the relative orientation of the two mixed layers is the same as that in the Al(3)Ti-type structure. These findings are confirmed by total-energy calculations, which lead further to the prediction that the bulk Al(3)Li alloy has a faulted, Al(3)Ti-type surface.

Journal Article↗

PubMed2001

Embryo quality and developmental potential is compromised by age.

AIMS: The aim of this retrospective study was to assess whether and how the age of the woman affects the quality and developmental potential of the oocytes and embryos in an ART program. METHOD AND MATERIAL: A total of 878 IVF cycles was included as a consecutive series of single transfers (n=292), dual transfers (n=366) and triple transfers (n=220), where all the transferred embryos in each cycle were of identical quality score and identical cleavage stage. RESULTS: We found a highly significant decrease in oocyte recovery with increasing age with about one oocyte per 2.3 years (95% CI 1.8 years to 3.1 years, p<0.0001). Further, we found that the number of oocytes that cleaved declined significantly with increasing age with one per 3.7 years (95% CI 2.7 years to 5.5 years, p<0.0001). This decline was mainly due to the decline in number of oocytes retrieved as the ratio of aspirated oocytes that cleaved with increasing age (approx. -0.04/10 year 95% CI: -0.10; +0.009) was not significantly different (p=0.10). The percentage of transfers using fragmented embryos did not increase significantly with increasing age (p=0.08). The odds of fragmentation increased by 3% per year. The average number of embryos transferred decreased significantly (p=0.03) with age from approximately 2.1 at the age of 25 to approximately 1.8 at the age of 40. In a selected subgroup of embryos all consisting of good quality embryos, a significant decrease was found in implantation rate with increasing age (approx. -0.08/10 years, 95% CI: -1.6; +0.00, p=0.05). Of the 357 pregnancies achieved in this study we found a significantly decreased ongoing pregnancy rate and a significantly increased abortion rate with increasing age (p=0.03). The decrease in the rate of ongoing pregnancies was almost linear, decreasing by approximately 1.5% per year. CONCLUSIONS: We conclude that age has an impact throughout a woman's reproductive life and that it is important to realize that the age-related decline in fertility may start already in the late twenties and not in the mid-thirties as is generally assumed.

Adult↗

PubMed2001

Body proportions, body composition and pubertal development of children in competitive sports.

The aim of this study was primarily to investigate anthropometric variables, body composition and pubertal development in children aged 9-13 participating in competitive sports. Secondly, the influence of age, sport, training hours and pubertal development/maternal menarcheal age on body composition and pubertal development was explored. A total of 183 (96 girls, 87 boys) children performing swimming (Sw), tennis (Te), European team handball (TH), and gymnastics (Gy) took part in the study. Anthropometric measurements and pubertal development were determined. The participants completed a questionnaire regarding hours of training per week and maternal menarcheal age. Significant differences in stature (z-scores) were found in both boys (Sw=0.06; Te=0.04; TH=0.05; Gy=-0.66, P<0.004) and girls (Sw=0.12; Te=0.19; TH=0.25; Gy=-0.96, P<0.004). In girls, sum of skinfolds in millimetres (Sw=33.4; Te=33.3; TH=41.0; Gy= 27.2, P<0.02) and body mass index z-scores (SW=0.00; Te=-0.27; TH=0.35; Gy=-0.25, P<0.001) were different between the sports. A regression analysis revealed that in girls, age and maternal menarcheal age were significantly associated with pubertal development (P<0.005 and P<0.01), respectively, and sport was associated with the sum of skinfolds (P<0.05). In boys, only age was significantly associated with pubertal development (P<0.005). In conclusion, anthropometric and body composition differences exist in athletes of both sexes from different sports but are more evident in females. Most importantly, we did not find any effect of training on body composition or pubertal development, confirming previous data that children in competitive sports are selected due to constitutional factors.

Adolescent↗

PubMed2001

Thyroid function in survivors of childhood acute lymphoblastic leukaemia: the significance of prophylactic cranial irradiation.

OBJECTIVE: Focus on long-term side-effects after cancer therapy in childhood has become of the utmost importance. The hypothalamic-pituitary thyroid (HPT) axis is exposed to irradiation when some children are treated for acute lymphoblastic leukaemia (ALL) with prophylactic cranial irradiation (CIR). Whether this treatment causes hypofunction of the HPT axis remains controversial. DESIGN: We measured plasma levels of total T3 (T3), total T4 (T4) and TSH before stimulation with TRH and plasma levels of TSH, 30 and 150 minutes after stimulation with TRH in 95 patients in first continuous remission of childhood ALL. PATIENTS: Patients diagnosed with ALL before the age of 15 years between 1970 and 1991 and who were in first continuous remission and off treatment for at least one year were studied. The children were aged between 0.5 and 14.8 years (median: 3.9) at diagnosis of ALL. Thyroid function was assessed between 1.2 and 18.3 years (median: 7.6) after completion of therapy. MEASUREMENTS: We measured T4 levels before, and compared TSH levels before and after, stimulation with TRH in patients who were treated with prophylactic CIR (15-24 Gy) (n = 38) (CIR group) with patients who were treated with chemotherapy only (n = 57) (non-CIR group). RESULTS: We found that T3 and T4 levels were normal in all individuals (excluding the women who were on oral contraceptives). The median time from end of treatment to time at follow-up was 9.1 years in the non-CIR group vs. 4.2 years in the CIR group (P < 0.001), and the effect on follow-up time was significant (P = 0.04). It was estimated that just after irradiation, the TSH levels before and 30 and 150 minutes after TRH stimulation was 49% lower in the CIR group; however, after 4.0 years, TSH levels were not significantly different between the two groups. Although within normal limits, the T4 levels were significantly higher in the CIR group compared to the non-CIR group (P = 0.003). It was estimated that, just after the end of treatment, T4 was 19.9% higher in the CIR group. However, in the CIR group, the T4 level decreased significantly over time with -1.5% per year (P = 0.025), while the difference in the non-CIR group was not significant. There was no correlation between T4 and TSH levels and sex, age at diagnosis, age at the end of treatment or age at follow-up. CONCLUSIONS: We conclude that, in our cohort of survivors of childhood ALL, prophylactic cranial irradiation of the central nervous system did not have an adverse effect on hypothalamo-pituitary-thyroid function within a median follow-up time of 8 years.

Adolescent↗

PubMed2001

Regional differences in semen quality in Europe.

Recent reports have indicated a decrease in semen quality of men in some countries, and suggested regional differences. A study was undertaken of semen samples from 1082 fertile men from four European cities (Copenhagen, Denmark; Paris, France; Edinburgh, Scotland; and Turku, Finland). Semen analysis was standardized, inter-laboratory differences in assessment of sperm concentration were evaluated, and morphology assessment centralized. Lowest sperm concentrations and total counts were detected for Danish men, followed by French and Scottish men. Finnish men had the highest sperm counts. Men from Edinburgh had the highest proportion of motile spermatozoa, followed by men from Turku, Copenhagen and Paris. Only the differences between Paris/Edinburgh and Paris/Turku were statistically significant (P < 0.003 and P < 0.002 respectively). No significant differences in morphology were detected. A general seasonal variation in sperm concentration (summer 70% of winter) and total sperm count (summer 72% of winter) was detected. Semen quality of a 'standardized' man (30 years old, fertile, ejaculation abstinence of 96 h) were estimated. Typically, sperm concentrations (x 10(6)/ml) for winter/summer were: Turku 132/93; Edinburgh 119/84; Paris 103/73; and Copenhagen 98/69. These differences in semen quality may indicate different environmental exposures or lifestyle changes in the four populations. However, it remains to be seen whether such changes can account for these differences. These data may also serve as a reference point for future studies on time trends in semen quality in Europe.

Adult↗

PubMed2000

A DANREF certified reference plastic for measurement of overall migration into the food simulant olive oil by single sided testing.

A reference material for the determination of overall migration from a plastic coextrudate into the fatty food simulant olive oil was produced and certified in an interlaboratory study. The analyses were carried out according to the ENV 1186 standard from the European Committee for Standardization (CEN) [ 1, 2, 3] with exposure of the coextrudate to olive oil for 10 days at 40 degrees C. After an initial preliminary interlaboratory study eight laboratories participated in the certification round, and two different methods were used to obtain single sided exposure of the plastic to the oil. The certified value was determined as the mean of laboratory mean values. No outliers were found. A reference value of 8.6 mg/dm2 +/- 1.4 mg/dm2 (+/- half width of the 95% confidence interval) was obtained which is within the range relevant for the regulatory limit (10 mg/ dm2), making this reference material suitable for laboratories measuring according to the EU overall migration limit [4]. The material has been found stable over 45 months.

Food Analysis↗

PubMed2000

Dynamics of prey moving through a predator field: a model of migrating juvenile salmon.

The migration of a patch of prey through a field of relatively stationary predators is a situation that occurs frequently in nature. Making quantitative predictions concerning such phenomena may be difficult, however, because factors such as the number of the prey in the patch, the spatial length and velocity of the patch, and the feeding rate and satiation of the predators all interact in a complex way. However, such problems are of great practical importance in many management situations; e.g., calculating the mortality of juvenile salmon (smolts) swimming down a river or reservoir containing many predators. Salmon smolts often move downstream in patches short compared with the length of the reservoir. To take into account the spatial dependence of the interaction, we used a spatially-explicit, individual-based modeling approach. We found that the mortality of prey depends strongly on the number of prey in the patch, the downstream velocity of prey in the patch, and the dispersion or spread of the patch in size through time. Some counterintuitive phenomena are predicted, such as predators downstream capturing more prey per predator than those upstream, even though the number of prey may be greatly depleted by the time the prey patch reaches the downstream predators. Individual-based models may be necessary for complex spatial situations, such as salmonid migration, where processes such as schooling occur at fine scales and affect system predictions. We compare some results to predictions from other salmonid models.

Animals↗

PubMed2000

Identification and quantification of estrogenic compounds in recycled and virgin paper for household use as determined by an in vitro yeast estrogen screen and chemical analysis.

The use of recycled paper for the manufacture of food contact materials is widespread, but very little is known about the presence of potential contaminants in the paper. The purpose of this study was to assess the worst-case migration of estrogenic active compounds using extracts of paper for household use. Twenty different brands of kitchen rolls, nine of which were made from recycled paper and the remainder from virgin paper, were obtained from retail shops. Paper extracts were subjected to (a) determination of the total estrogenic activity by using an in vitro estrogen screen based on yeast cells stably transfected with the human estrogen receptor alpha and (b) chemical analysis and quantification by GC/MS, GC/FTIR/MS, and GC/FID for detection of a variety of estrogenic compounds. A marked estrogenic response was observed in nine of the extracts, seven of which were made from recycled paper and two from virgin paper. The chemical analysis revealed that extracts made from recycled paper contained levels of bisphenol A ranging from 0.6 to 24 mg/kg of kitchen roll, whereas extracts from virgin paper contained no bisphenol A or only negligible amounts. In contrast, 4-tert-octylphenol, 4-nonylphenols, and di-n-butyl and diisobutyl phthalate were present to a varying degree in both recycled and virgin paper with no apparent preferable distribution between the two paper types. The estrogenic response of the two extracts made from virgin paper appeared to be due partly to the presence of the preservative propyl paraben. Diisopropylnaphthalene, which turned out to be weakly estrogenic active in vitro (EC(50) = 53 microM), was detected in minor amounts in most of the extracts with the major part, ranging from 0.3 to 4.7 mg/kg of paper, found in recycled paper. Our findings that recycled kitchen rolls contain bisphenol A and other xenoestrogens may apply to other types of recycled paper used for food packaging and emphasize the importance of identifying this and other contaminants in recycled paper in general. These data indicate that bisphenol A may be useful as a purity indicator for recycled paper.

Benzhydryl Compounds↗

PubMed2000

Inter-observer variation in the results of the clinical andrological examination including estimation of testicular size.

Inter-observer variation in andrological examination by 10 clinical investigators from five Nordic and Baltic countries was investigated. In addition, information on intra-observer variation was obtained for six of the 10 investigators. Testicular size was measured using Prader's orchidometer and one of the investigators also performed an ultrasound estimate of testicular size. A highly significant difference (p < 0.001) between observers was found with an inter-observer error of 16% in estimating testicular size in 23 young men. The difference in the estimate tended to increase with increasing testicular size. There was no significant intra-observer difference in two measurements performed on consecutive days. Only differences in median testis size, which were greater than 31% between measurements by two investigators, were found to be significant at the 5% level. The ultrasound estimate of testicular size was significantly lower than the orchidometer estimate, with a mean difference of 3.6 mL for the left testis and 4.3 mL for the right testis. Tanner staging of genitalia and diagnosis of a varicocele was subject to great inter-observer variation, and for the diagnosis of varicocele only one-third of the investigators was able to reproduce their results on a second examination. In conclusion, it was found that the clinical andrological examination of young men is subject to great inter-observer variation. This should be kept in mind when results from different studies are compared as well as in daily clinical practice.

Adult↗

PubMed2000

Plasticizers in total diet samples, baby food and infant formulae.

The plasticizers di-n-butylphthalate (DBP), butylbenzylphthalate (BBP), di-2-(ethylhexyl)phthalate (DEHP) and di-2-(ethylhexyl)adipate (DEHA) were analysed in 29 total diet samples, in 11 samples of baby food and in 11 samples of infant formulae. In all of the total diet samples the presence of one or more of the plasticizers was demonstrated. Maximum and minimum mean concentrations in the total diet samples were: 0.09-0.19 mg DBP/kg, 0.017-0.019 mg BBP/kg, 0.11-0.18 mg DEHP/kg and 0.13-0.14 mg DEHA/kg. One or more of the phthalates was also found in about 50% of the samples of baby food as well as in infant formulae. The calculated mean maximum intakes of the individual compounds from the total diet samples were below 10% of the restrictions proposed by the EU Scientific Committee for Food (SCF), and the spread in individual intakes was considerable. DEHP was the plasticizer determined most frequently and contributed the highest fraction of its tolerable daily intake (TDI). Hence, the maximum calculated intake of DEHP from single samples of the foodstuffs analysed could be up to one-third of the TDI. The calculated mean intake of DEHA was about 1% of the TDI with a maximum value of 13% of the TDI. Violations of the restrictions proposed by the EU Scientific Committee for Food (SCF) in the form of TDI values or specific migration limits were not found in this investigation.

Adipates↗

PubMed2000

Is prepubertal growth adversely affected by sport?

PURPOSE: To study the effect of genetic factors, birth weight, early childhood growth, sport, hours of training, and pubertal status on the stature and body mass index (BMI) of children aged 9-13 participating in sports at a competitive level. METHODS: A total of 184 children (96 girls, 88 boys), competing in swimming, tennis, team handball, and gymnastics, were investigated, assessing their height, weight, pubertal development, and BMI. Of these, 137 (76 girls, 61 boys) returned a questionnaire, which enabled us to determine height and BMI at age 2-4, birth weight, and parental heights. RESULTS: Significant differences in standard deviation scores (SDS) for actual height and for height at age 2-4 were found in both sexes between the four sports. In girls, BMI SDS was significantly different between the four sports, whereas no difference was found in boys. Each sport investigated separately showed no change in height SDS and BMI SDS between ages 2-4 and 9-13. A regression analysis showed that target height, height at age 2-4, and pubertal status had a significant impact on actual height. Interestingly, the type of sport and hours of training per week had no effect on height SDS. In boys, BMI at age 2-4 and pubertal status had a significant effect on actual BMI, whereas in girls, only BMI at age 2-4 was significant. CONCLUSIONS: The results suggest that prepubertal growth is not adversely affected by sport at a competitive level and that constitutional factors are of importance for choice of sport in children.

Adolescent↗

PubMed2000

Interpreting parameters in the logistic regression model with random effects.

Logistic regression with random effects is used to study the relationship between explanatory variables and a binary outcome in cases with nonindependent outcomes. In this paper, we examine in detail the interpretation of both fixed effects and random effects parameters. As heterogeneity measures, the random effects parameters included in the model are not easily interpreted. We discuss different alternative measures of heterogeneity and suggest using a median odds ratio measure that is a function of the original random effects parameters. The measure allows a simple interpretation, in terms of well-known odds ratios, that greatly facilitates communication between the data analyst and the subject-matter researcher. Three examples from different subject areas, mainly taken from our own experience, serve to motivate and illustrate different aspects of parameter interpretation in these models.

Animals↗

PubMed2000

Serum inhibin A and inhibin B in healthy prepubertal, pubertal, and adolescent girls and adult women: relation to age, stage of puberty, menstrual cycle, follicle-stimulating hormone, luteinizing hormone, and estradiol levels.

Biochemical assessment of gonadal function during maturation in girls and in adult women can be troublesome. With the recent advent of specific assays for the gonadal peptides inhibin A and inhibin B, it might be possible to achieve a clearer picture of events. We therefore determined serum levels of inhibin A, inhibin B, FSH, LH and estradiol in a cross-sectional study of 403 healthy schoolgirls (aged 6 -20 yr) in relation to age and stage of puberty and in 181 healthy nonpregnant women (aged 20-32 yr) in relation to stage of the menstrual cycle. In addition, inhibin A and inhibin B were measured daily throughout the menstrual cycle in 10 healthy adult women. Levels of inhibin B are low or undetectable in prepubertal girls (median, 26.5 pg/mL; 95% prediction interval, <20-100 pg/mL), increase sharply through pubertal stage II to peak in stage III (median, 84 pg/mL; 95% prediction interval, 28-227 pg/mL) and thereafter decline through pubertal stages IV and V. These changes presumably reflect increasing ovarian stimulation through early puberty, resulting in an increased number of developing follicles, follicles reaching a later stage of development before undergoing atresia, or both. Declining levels in late puberty and adulthood probably reflect the onset of the menstrual cycle and the subsequent appearance of the luteal phase, where inhibin B levels are low. Inhibin A levels are undetectable or very low in early puberty (median, <7 pg/mL; 95% prediction interval, <7-14) pg/mL), increasing gradually through pubertal stages to reach their highest values in adult women (median, 21.5 pg/mL; 95% prediction interval, <7-129 pg/mL). Levels of inhibin A greater than 19 pg/mL are only seen in postmenarcheal girls in puberty and in adult women, again consistent with inhibin A being primarily produced by the corpus luteum. Determining cut-off levels of serum inhibin B regarding whether a girl had entered puberty resulted in similar (low) sensitivities and specificities as those found for cut-off levels of LH or estradiol due to the large overlap between serum values in Tanner stages I and II. Correlations between inhibin A and inhibin B and FSH, LH, and estradiol within pubertal stages are presented. In early puberty both inhibin A and inhibin B correlated positively with LH and FSH. In late puberty inhibin A correlated negatively with FSH and did not correlate with LH; inhibin B still correlated positively with both FSH and LH, now most strongly with FSH. In adult women during the menstrual cycle, serum inhibin B levels increased during the follicular phase, indicating the greatest production by follicles in early stages of development. In contrast, serum inhibin A levels peaked during the luteal phase, indicating the greatest production by the corpus luteum. In conclusion, serum inhibin A and inhibin B levels in normal puberty in girls show consistency with our knowledge of the manner in which these hormones are secreted within the menstrual cycle in adult women. The presented reference values may be of use in the clinical evaluation of pubertal development in girls.

Adolescent↗

PubMed1999

[Access to Danish health care by immigrant women. Access to hospital care among immigrant women with breast cancer compared with Danish women].

The study aim is to measure possible differences in access to health care among immigrant women with breast cancer compared with Danish women. We used tumour size at diagnosis as a proxy measure of access. The Danish Central Personal Register provided information from 1977-1996 on women between 20-75 years born in countries in which Islam is the dominating faith. These data were linked to the Danish Breast Cancer Cooperative Group, which registers data concerning tumour size. Sixty-five immigrant women with breast cancer were identified and matched with a control population of Danish women. The study showed larger tumours at diagnosis among women from ethnic minority groups compared to Danes. However, this tendency was not significant. Furthermore, mammographic screening had a significant effect on the tumour sizes of Danish women, but not on those of immigrants. The study indicates ethnic inequalities related to access to health services as measured by tumour size.

Adult↗

PubMed1999

Secular changes in anthropometric data in cystic fibrosis patients.

The aim of this study was to study the secular changes in anthropometric data over calendar time in patients with cystic fibrosis (CF). Growth curves were constructed for 270 patients based on height and weight registrations from the medical files. Height, body mass index (BMI), magnitude of pubertal peak height velocity (PHV) and age at PHV were analysed for possible secular changes from the 1960s to the 1990s. There was a significant change in height over calendar time in only 1 of 12 age groups. BMI showed a significant increase in 10- and 15-y-old boys and girls and in 5-y-old girls. The magnitude of PHV changed significantly over time, whereas age at PHV was constant. No significant changes in height and age at PHV over calendar time were observed; this was probably due to a selection bias since the oldest patients, who survived to be part of the present investigation, represented milder forms of the disease. The increase in BMI and change in magnitude of PHV over calendar time may reflect the improvement in treatment leading to a better survival and clinical status through puberty. The increase in BMI and change in magnitude of PHV were sufficient to overcome the selection bias from older patients with milder disease.

Adolescent↗

PubMed1999

Diurnal rhythm in serum levels of inhibin B in normal men: relation to testicular steroids and gonadotropins.

Inhibin B is a testicular glycoprotein that is secreted from the Sertoli cells and believed to play a role in FSH secretion. We characterized the diurnal profile of serum inhibin B and the relation to gonadotropins and testicular steroids. Serum inhibin B was measured in 13 healthy normal male volunteers (median age, 30 yr) by continuous blood drawing, with sampling every 30 min for 24 h. Blood samples were also analyzed for FSH, LH, testosterone, estradiol, and sex hormone-binding globulin. We found a significant diurnal variation in inhibin B, with peak values in the early morning and nadirs in the late afternoon, followed by gradual increasing nocturnal values. An average decline of 3%/h from 0900 until 1700 h was calculated. Significant cross-correlation was found between inhibin B and testosterone as well as estradiol, whereas no cross-correlation was found between inhibin B and FSH. Two-dimensional time-series analyses revealed a statistically significant influence of testosterone on inhibin B. In addition, estradiol and inhibin B had a significant influence on one another. In conclusion, we found a significant diurnal variation in inhibin B levels in normal men, with a pattern of higher values in the early morning hours and lower values in the late afternoon and evening. We did not find evidence for a role of FSH in this diurnal variation of inhibin B. However, covariation with serum levels of testosterone and estradiol suggested that these hormones might play a role in the diurnal rhythm of inhibin B, although some other common influence could not be excluded.

Adult↗