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J Gromoll

Publications and source records attributed to J Gromoll.

At least 19 recordsLinked to original sources
PubMed2002

The CAG repeat polymorphism in the androgen receptor gene modulates body fat mass and serum concentrations of leptin and insulin in men.

AIMS/HYPOTHESIS: The relationship of androgens to the metabolic syndrome has not been resolved. The polymorphic number of CAG repeats within the androgen receptor gene is inversely associated with the transcriptional activity of target genes. This polymorphism might thus influence testosterone effects on body fat content and serum concentrations of leptin and insulin. The direct and indirect role of androgens within the metabolic syndrome should become clearer if this genetically determined effector is taken into account. METHODS: The hypothesis was investigated in a cross-sectional study involving 106 healthy 20-50 year old males. RESULTS: Multiple regression models showed a positive independent correlation of the CAG repeat number with body fat content, leptin and insulin (partial r=0.39, 0.36 and 0.28, p<0.001, p<0.001 and p=0.006, respectively). Factor analysis yielded a five-dimensional model: two dimensions were influenced by the androgen receptor polymorphism, namely "body composition" which consisted of leptin, body fat mass, insulin, the number of CAG repeats (positive loadings) and physical activity (negative loading), and "lipid profile" which comprised low density lipoprotein cholesterol, cigarette smoking, triglycerides (positive loadings) as well as high density lipoprotein cholesterol and number of CAG repeats (negative loadings). CONCLUSIONS/INTERPRETATION: A low number of CAG repeats were independently associated with protective parameters (low body fat mass and plasma insulin) as well as with adverse parameters (low high density lipoprotein cholesterol concentrations). This suggests that the pivotal role of this polymorphism in modulating androgen effects on cardiovascular risk factors is of a complex nature and implies that its clinical impact, similar to that of androgens, is dependent on exogenous cofactors.

Adipose Tissue↗
PubMed2002

TestisBank: an internet-based gene sequence database of the testis.

The testis is a highly transcriptionally active organ with hundreds of genes expressed during different stages of spermatogenesis. Scientists working on the testis are restricted to using two sources for further information on testicular genes, GenBank and MEDLINE. However, these two databases are not completely linked and give only very little information on the cellular type of expression or whether a gene is cloned in other tissues but is also expressed in the testis. We have generated an organ-specific database named TestisBank, which is capable of retrieving a more complete set of genes expressed in the different cell types of the testis. Furthermore, it extends to the epididymis which plays an important role in germ cell maturation. TestisBank is automatically updated to match the current status of sequence entries in the genome databases and it provides the user with an interface convenient to handle and provides useful links related to male reproduction. The TestisBank is publicly available at http://medweb.uni-muenster.de/TestisBank/. The design of the TestisBank may provide a simple model for the development of databases in which molecular and literature data are merged, thereby allowing detailed insight into the contribution of different cells/genes to the complex process of spermatogenesis.

Databases, Bibliographic↗
PubMed2002

Distribution and function of FSH receptor genetic variants in normal men.

Follicle stimulating hormone (FSH) plays a key role in the maintenance of qualitatively and quantitatively normal spermatogenesis. It controls gamete development through Sertoli cells, via binding to its receptor. The influence and importance of FSH receptor (FSHR) variants on Sertoli cell function is not completely understood and remains to be investigated. In this retrospective study, we explored the impact and action of two distinct FSHR isoforms, Thr307/Asn680 and Ala307/Ser680, in a large group of men. This investigation includes 288 normal healthy men, 86 of whom were proven fathers previously studied, and 202 were newly recruited subjects. The FSHR polymorphism at position 680 was analyzed in the whole group, while position 307 was investigated in 150 subjects, both of them by single-stranded conformation polymorphism (SSCP) gel electrophoresis. The distribution frequency for position 680 was 29% for the Asn/Asn, 52% for the Asn-Ser, 19% for the Ser-Ser variant, and for position 307, 27% for the Thr-Thr, 55% for the Ala-Thr, 18% for the Ala-Ala, respectively. Polymorphism combinations that were different from Thr307/Asn680 - Ala307/Ser680 were found in four subjects. When subjects were grouped according to genotype at position 680, no significant differences between basal FSH, testosterone, inhibin B levels and semen parameters were found. This clinical finding demonstrates that, differently from females, in whom a significant correlation between FSHR polymorphism and basal FSH levels was found, the FSHR genotype has no influence on clinical parameters in males.

Base Sequence↗
PubMed2002

Manifestation of Y-chromosomal deletions in the human testis: a morphometrical and immunohistochemical evaluation.

BACKGROUND: Deletions of the AZF (azoospermia factor) subregions on the Y chromosome are accompanied by a diverse spectrum of spermatogenic disturbances ranging from hypospermatogenesis to total depletion of germ cells causing infertility. The AZF region encodes gene products which are candidates for the genetic control of spermatogenesis. Although it is known which genes are involved, a general principle of cause and effect cannot yet be deciphered and the deletion type has non-uniform histological phenotypes. METHODS AND RESULTS: We analysed morphological parameters of testicular biopsies from 17 patients diagnosed for Y chromosome microdeletions. As control groups we analysed testes from patients with idiopathic Sertoli cell-only (SCO) syndrome (n = 11), mixed atrophy (n = 10) and complete spermatogenesis (n = 11). A detailed genetic analysis on the extension of the observed microdeletions revealed similar breakpoints in the distal and proximal region of the AZFc region, indicating a common mechanism of homologous recombination for such deletions, as has been suggested before. Morphometric parameters such as the diameter of the tubules, lumen, thickness of the lamina propria and height of the tubule epithelia were investigated. The diameter of the tubules from patients with microdeletions was found to be significantly smaller compared with patients with mixed atrophy. Considering also the size of the tubules, lumen and epithelia, a Y-chromosomal microdeletion represents an intermediate state between an idiopathic SCO and normal spermatogenesis. The immunohistochemical analysis of six different Sertoli cell markers, cytokeratin 18, vimentin, inhibin alpha subunit, 14-3-3 theta, FSH receptor and androgen receptor, revealed no impact of AZF deletion on the specific expression pattern of these genes. CONCLUSIONS: Our results suggest that, notwithstanding the deletion of a common region in the AZFc region, microdeletions of the Y chromosome lead to an intermediate status between idiopathic SCO and complete spermatogenesis, resulting in a heterogeneous histological profile regardless of the seminiferous activity. The Sertoli cell function seems not to be altered.

Adult↗
PubMed2002

Natural transmission of a partial AZFb deletion of the Y chromosome over three generations: case report.

The natural transmission of microdeletions of the Y chromosome is occasionally reported in the literature. Here we describe the natural transmission of a partial AZFb deletion over three generations. PCR amplification of several sequence tagged site markers in the three AZF regions of the Y chromosome was carried out in a patient with oligoasthenoteratozoospermia, his father and his naturally conceived son. The deletion was confirmed by Southern blotting. The propositum, his father and his son showed a probably identical, partial deletion of the distal part of the AZFb region, involving sY130 and sY143. The deletion was confirmed by Southern blotting using the sY130 probe. Partial AZFb microdeletions can be associated with moderate oligozoospermia allowing natural conception and therefore natural transmission of this genetic anomaly. Further studies are needed to define the pathogenetic significance of microdeletions involving sY130 and sY143.

Adult↗
PubMed2001

The relationship between Y chromosome DNA haplotypes and Y chromosome deletions leading to male infertility.

Microdeletions on the short arm of the Y chromosome have defined three non-overlapping regions (AZFa, b, c) recurrently deleted among infertile males. These regions contain several genes or gene families involved in male germ-cell development and maintenance. Even though a meiotic origin for these microdeletions is assumed, the mechanisms and causes leading to microdeletion formation are largely unknown. In order to assess whether some Y chromosome groups (or haplogroups) are predisposed to, or protected against, deletion formation during male meiosis, we have defined and compared Y chromosome haplogroup distribution in a group of infertile/subfertile males harbouring Yq deletions and in a relevant Northwestern European control population. Our analyses suggest that Y chromosome deletion formation is, at least in the study populations, a stochastic event independent of the Y chromosome background on which they arise and may be caused by other genetic and/or environmental factors.

Chromosome Deletion↗
PubMed2001

The CAG repeat polymorphism in the androgen receptor gene affects bone density and bone metabolism in healthy males.

OBJECTIVE: Bone metabolism and bone density (BD) are influenced by sex hormones. Testosterone (T) action is exerted through the androgen receptor (AR). We investigated the potential impact of the CAG repeat (CAGR) polymorphism within the AR gene on BD and bone metabolism in healthy younger males. PATIENTS AND MEASUREMENTS: The number of CAGRs in 110 healthy men aged 20-50 years was determined by sequence analysis. We assessed BD by the radiation-free method of quantitative ultrasound (QUS) of the phalanges. Serum levels of bone-specific alkaline phosphatase (BAP) and urine secretion of free deoxypyridinoline (DPD, corrected for creatinine), serum levels of sex hormones, body fat content and lifestyle factors were determined. RESULTS: In stepwise multiple regression models controlling for age, body fat content and lifestyle factors, the number of CAGRs was an independent negative predictor of BD (partial r = - 0.286, P = 0.001), whereas it was positively associated with markers of bone turnover (for BAP: partial r = 0.32, P= 0.001; for DPD: partial r = 0-241, P = 0.013). Levels of free T and oestradiol showed an independent and positive association with BD; age contributed significantly to lower BD. Age and free T were negatively associated with markers of bone turnover, whereas oestradiol showed a positive correlation with BAP and DPD. ANOVA in groups according to age and the CAGR length suggested an increased age-dependent bone loss in subjects with a CAGR length of 22-31 compared with 14-21 CAGRs (overall P < 0.01). CONCLUSIONS: A high number of CAG repeats within the androgen receptor gene attenuates testosterone effects on bone density and bone metabolism. This seems to be associated with accelerated age-dependent bone loss.

Adult↗
PubMed2001

Prevalence of Y chromosome microdeletions in infertile men who consulted a tertiary care medical centre: the Münster experience.

The long arm of the human Y chromosome is required for male fertility. Microdeletions in three different regions of the human Y chromosome, designated AZFa, AZFb and AZFc, respectively, are frequently associated with male infertility. The varying frequency of Y microdeletions found in cohorts of infertile men (0.4-55.5%) is probably related to the criteria by which the patients are selected. We report the diagnosis of Y chromosomal microdeletion in a total of 1,470 men who attended our infertility clinic, the largest sample of infertile patients to have been analysed to date. This cohort consists of three populations. The first subgroup comprises 228 selected patients with severely impaired spermatogenesis. Since microdeletions had also been reported in patients with less severe defects in spermatogenesis, we then intended to define the deletion frequency in unselected patients (population II: 378 patients). Population III comprises 864 prospectively selected patients and intracytoplasmic sperm injection candidates. Altogether, 19 patients with microdeletions were found (1.3%). The microdeletion frequencies in populations I, II and III were 3.5%, 0.3% and 1.2%, respectively. Our study helps to define a subgroup of infertile men at risk of Y chromosomal microdeletions, and strongly supports the recommendation that Y microdeletion analysis should be limited to azoospermic and severely oligozoospermic men and candidates for intracytoplasmic sperm injection.

Adult↗
PubMed2001

The CAG repeat polymorphism in the AR gene affects high density lipoprotein cholesterol and arterial vasoreactivity.

Genomic effects of T are exerted via the AR. The length of the polymorphic CAG repeat sequence in the AR gene is inversely correlated with the transcriptional regulation of target genes by T. In 110 healthy men (20-50 yr), we investigated the interactions among this polymorphism, serum levels of sex hormones, cardiovascular risk factors, and flow-mediated and nitrate-induced vasodilatation of the brachial artery. The number of CAG repeat had no significant correlations with serum concentrations of total or free T. Stepwise multiple regression analysis revealed positive correlations of the number of CAG repeat with serum levels of high density lipoprotein cholesterol (partial r = 0.44; P < 0.001) and flow-mediated vasodilatation (partial r = 0.37; P < 0.001). The association of CAG repeat with high density lipoprotein (HDL) cholesterol was independent of body fat content and serum levels of free T, which both had significant negative correlations with HDL cholesterol. The association of CAG repeat with flow-mediated vasodilatation was independent of cigarette smoking and serum levels of free T and low density lipoprotein cholesterol, which also were correlated with flow-mediated vasodilatation. We conclude that a low number of CAG repeat in the AR gene implies a greater chance for low levels of HDL cholesterol and reduced endothelial response to ischemia, which are both important risk factors for coronary heart disease.

Adult↗
PubMed2001

Inverse correlation between sperm concentration and number of androgen receptor CAG repeats in normal men.

Androgens are essential for the maintenance of normal spermatogenesis. Androgen action is mediated by the androgen receptor (AR), which in the testis is expressed by Leydig, peritubular, and Sertoli cells. The fact that sperm numbers range from 20 up to 300 million/mL in normal men without any indication of changed endocrine parameters led us to assume that genetic variability of transduction of androgen signaling could be important. We therefore compared the variable number of CAG repeats in the AR with sperm concentrations in men with normal ejaculate parameters (62 fathers and 69 volunteers participating in clinical trials). In multivariate analysis CAG repeat length did not differ between the volunteers (19.4 +/- 3.1) and the fathers (20.6 +/- 3.0), but was significantly correlated to sperm concentrations with a coefficient of -0.25. When compared with a group of infertile men with (n = 14) or without (n = 30) a family history of infertility, no such correlation was found. These results indicate that men with short CAG repeats have the highest sperm output within the normal fertile population. Polymorphisms of the AR contribute to the efficiency of spermatogenesis in normal men, but do not play a predominant role in male infertility.

Humans↗
PubMed2000

Deletion of azoospermia factor a (AZFa) region of human Y chromosome caused by recombination between HERV15 proviruses.

Deletion of any of three regions of the human Y chromosome results in spermatogenic failure and infertility. We previously sequenced one of these regions, azoospermia factor a (AZFa) and found that it spanned approximately 800 kb. By sequence-tagged site (STS) content mapping, we roughly defined deletion breakpoints in two unrelated, azoospermic men with AZFa deletions. The positions of proximal and distal breakpoints were similar in the two men. Hypothesizing that the deletions might have been generated by homologous recombination, we searched electronically for DNA sequence similarities between the proximal and distal breakpoint regions. These comparisons revealed the most striking sequence similarities anywhere along or near the AZFa region. In the proximal breakpoint region, we identified a 10 kb provirus of the recently defined HERV15 class of endogenous retroviruses. In the distal breakpoint region, we found a second HERV15 provirus, 94% identical in DNA sequence to the first and in the same orientation. (A partial LINE insertion in this distal provirus proved to be the basis of the previously described DYS11/p12f polymorphism.) The AZFa deletions in the two men differed slightly, but all breakpoints fell within the HERV15 proviruses. Indeed, sequencing of deletion junctions from the two men revealed that homologous recombination had occurred within large domains of absolute sequence identity between the proximal and distal proviruses. When combined with published STS mapping data for other AZFa-deleted men, our findings suggest that recombination between these two HERV15 proviruses could account for most AZFa deletions.

Base Sequence↗
PubMed2000

Detection of mutations in glycoprotein hormone receptors.

The luteinizing, follicle-stimulating, and thyroid-stimulating hormone receptors belong to the huge family of G-protein-coupled receptors. Identification of either activating or inactivating mutations of these receptors has led to a fundamental improvement in our understanding of glycoprotein hormone/receptor interaction. Furthermore, clinical phenotypes such as precocious puberty, follicle-stimulating hormone (FSH) insensitivity syndrome, and congenital hypthyroidism are now being explained by mutated glycoprotein hormone receptors. Since there is an ongoing worldwide search for certain clinical phenotypes that might be caused by mutations of these receptors, there is a demand for strategies and techniques that can be used to screen patients in a effective and reliable way. This article focuses, therefore, on patient selection and techniques for the detection of mutations of glycoprotein hormone receptors, and compiles useful laboratory protocols to conduct such studies.

Alleles↗
PubMed2000

Dazl protein expression in adult rat testis is up-regulated at meiosis and not hormonally regulated.

The Y-chromosomal DAZ (deleted in azoospermia) gene and the autosomal Dazl (deleted in azoospermia-like) gene are two crucial factors for the achievement and maintenance of spermatogenesis. Whereas Y-chromosomal DAZ is present in certain primates, it is lacking in rodents and other species. We have investigated the expression of Dazl protein during spermatogenesis in the adult rat testis using immunohistochemistry. Dazl immunoreactivity was found predominantly in the cytosol of primary pachytene spermatocytes. A weaker but clearly detectable signal was present in intermediate and B spermatogonia and in early spermatocytes from preleptotene to zygotene. The highest expression patterns were observed between stages IV and VIII during the spermatogenic cycle when spermatocytes prepare for the first meiotic division. Specific staining could also be observed in step 11-19 elongating spermatids in the acrosome region. Treatment for 42 days with a potent GnRH-antagonist abolished gonadotrophin secretion and led to a regressed testis, lacking most of the advanced germ cell types such as spermatids but still bearing spermatogonia and spermatocytes. No difference in staining pattern for Dazl protein was observed in GnRH antagonist-treated rats despite the lack of gonadotrophins and substantial impairment of the spermatogenic process, indicating that Dazl expression is clearly hormone-independent. The localization and level of Dazl expression suggests an important role in the regulation of the first meiotic stages of spermatogenesis. The hormone independent onset of expression points to an autonomous cell-cycle event in which Dazl seems to be essential for the entry into meiosis. The presence of Dazl in the acrosome region of elongating spermatids might reflect an unknown role of Dazl as a morphogenetic factor during spermiogenesis.

Animals↗
PubMed2000

Male hypogonadism caused by homozygous deletion of exon 10 of the luteinizing hormone (LH) receptor: differential action of human chorionic gonadotropin and LH.

We report the unique case of a patient with Leydig cell hypoplasia (LCH) type II caused by a genomic deletion resulting in the complete absence of exon 10 of the LH receptor (LHR). The patient presented at the age of 18 yr with retarded pubertal development, small testicles, and delayed bone maturation. LH was highly elevated, with very low serum testosterone levels. Genetic analysis revealed a homozygous deletion of approximately 5 kbp encompassing exon 10 of the LHR gene. Screening of family members demonstrated heterozygosity for the deletion, indicating autosomal recessive inheritance. At the time of examination, the patient displayed nearly normal male phenotype, but lacked pubertal development and was hypogonadal. Obviously, fetal male development sustained by hCG was normal, whereas LH action, important for pubertal development, was impaired. A hCG stimulation test induced testosterone biosynthesis and secretion within the normal range. Subsequently, hCG treatment was continued, resulting in an increase in testicular volume and the appearance of spermatozoa in the ejaculate after 16 weeks of treatment (5.3 million/mL). Despite highly elevated endogenous LH serum levels, the response to hCG indicates a possible dual mechanism of hormone binding and signal transduction for hCG and LH on a LHR that lacks exon 10. Furthermore, this patient represents the clinical counterpart of the normal male marmoset monkey (Callithrix jacchus), in which the expressed LHR lacks exon 10 in toto. This case provides important clinical insights about the possible role of exon 10 of the LHR in discriminating between LH and hCG actions.

Adolescent↗
PubMed2000

Ovarian response to follicle-stimulating hormone (FSH) stimulation depends on the FSH receptor genotype.

Because the ovarian response to FSH stimulation in assisted reproduction is variable, ranging from hyporesponse to hyperresponse, with the possible complication of ovarian hyperstimulation, it would be of great benefit to predict the response of the patients to FSH. To date, no clear-cut predictors of ovarian responsiveness to FSH have been identified. In this study, we investigated the role of two distinct FSH receptor (FSHR) variants, Thr307/Asn680 and Ala307/Ser680, in the response to FSH in women undergoing controlled ovarian stimulation. The FSHR polymorphism at position 680 was analyzed by restriction-fragment-length polymorphism in 161 ovulatory women below the age of 40 yr. With reference to the couple, infertility has been diagnosed as being attributable to male causes (76%), tubal factor (11%), or both (13%). The distribution was 29% for the Asn/Asn, 45% for the Asn/Ser, and 26% for the Ser/Ser FSHR variant. Peak estradiol levels, number of preovulatory follicles, and number of retrieved oocytes were similar in the 3 groups. However, basal FSH levels were significantly different among the 3 groups (6.4 +/- 0.4 IU/L, 7.9 +/- 0.3 IU/L, and 8.3 +/- 0.6 IU/L for the Asn/Asn, Asn/Ser, and Ser/Ser groups, respectively, P < 0.01). The number of FSH ampoules required for successful stimulation was significantly different among the 3 groups (31.8 +/- 2.4, 40.7 +/- 2.3, and 46.8 +/- 5.0 for the Asn/Asn, Asn/Ser, and Ser/Ser groups, respectively, P < 0.05). According to multiple linear regression analysis, the number of ampoules needed could be predicted from a linear combination of both the type of polymorphism and basal FSH levels (P < 0.001). These clinical findings demonstrate that the ovarian response to FSH stimulation depends on the FSHR genotype.

Adult↗
PubMed1999

Cloning and expression of cynomolgus monkey (Macaca fascicularis) gonadotropins luteinizing hormone and follicle-stimulating hormone and identification of two polymorphic sites in the luteinizing hormone beta subunit.

The genes encoding the cynomolgus monkey gonadotropin subunits, alpha, follicle-stimulating hormone (FSH) beta and luteinizing hormone (LH) beta, were cloned by reverse transcriptase polymerase chain reaction (RT-PCR) using pituitary RNA. The predicted amino acid sequences displayed 82, 96 and 87% identity to human subunit sequences, respectively. Northern blot hybridization of monkey tissues revealed pituitary specific transcripts of 1.0 and 0.6 kb for the alpha and LHbeta subunit, respectively, and two bands of 1.8 and 0.65 kb for the FSHbeta. Upon sequencing LHbeta cDNAs from different monkeys, two polymorphic sites were detected, resulting in the amino acid transitions Ser32Thr and His60Arg. Restriction analysis revealed different homo- and heterozygous combinations of the polymorphic sites indicating linkage dysequilibrium. Transient co-expression of the alpha subunit together with the FSHbeta or LHbeta subunit in COS7 and CHO cells resulted in secretion of in vitro bioactive hormones. This work represents a further step towards production of recombinant monkey LH and FSH which can be used in a homologous experimental setting in the cynomolgus monkey.

Amino Acid Sequence↗
PubMed1999

Mutation screening and isoform prevalence of the follicle stimulating hormone receptor gene in women with premature ovarian failure, resistant ovary syndrome and polycystic ovary syndrome.

OBJECTIVE: To determine whether mutations in the FSH receptor gene are associated with premature ovarian failure (POF) or resistant ovary syndrome (ROS) in women in the UK. To determine whether an allelic variant of the FSH receptor gene affects fertility parameters in women with polycystic ovary syndrome (PCOS). DESIGN: A mutation screen using DNA from women with POF and ROS. Restriction digest of amplified DNA from women with POF, ROS, PCOS and controls to determine allelic variant status. Fertility parameters were compared between allelic variant subgroups of women with PCOS. PATIENTS: The study population comprised 49 women with POF, 5 with ROS, 93 with PCOS and 51 controls. MEASUREMENTS: In women with PCOS, fertility and menstrual status was recorded and serum FSH and ovarian volume were measured. RESULTS: No mutation of the FSH receptor gene was found in women with POF or ROS. The allelic variant Thr307/Ser680 was found to be similarly prevalent in all study groups. The Thr307/Ser680 variant was found to have no phenotype in terms of fertility parameters in women with PCOS. CONCLUSIONS: Mutations of the FSH receptor gene are rare in women with premature ovarian failure or resistant ovary syndrome in the UK. Polymorphisms of the FSH receptor gene do not appear to have pathophysiological significance with regard to ovarian function.

Adult↗