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J Gromoll

Publications and source records attributed to J Gromoll.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1999

The Old World monkey DAZ (Deleted in AZoospermia) gene yields insights into the evolution of the DAZ gene cluster on the human Y chromosome.

The DAZ gene cluster on the human Y chromosome is a candidate for the Azoospermia Factor (AZFc). According to the current evolutionary model, the DAZ cluster derived from the autosomal homolog DAZL1 through duplications and rearrangements and is confined to Old World monkeys, apes and humans. To study functional and evolutionary aspects of this gene family we have isolated from a cynomolgus (Old World) monkey testis cDNA library the Y chromosomal cynDAZ and the autosomal cynDAZL1 cDNA. cynDAZL1 contains one DAZ repeat and displays high homology to human DAZL1. cynDAZ comprises 11 repeats, each consisting of exons 7 and 8, whereas the human DAZ cDNA repeat units contain predominantly exon 7. Genomic studies revealed the same amplific- ation events of a 2.4 kb genomic unit encompassing exons 7 and 8 in both species, indicating that after splitting of the two lineages, in the human mainly exon 8 was converted to a pseudoexon by splice site mutations. The structural features of cynDAZ reveal a more detailed model for the sequence of events leading to the present form of human DAZ. Thus, in a monkey species DAZ is present in a form more ancestral than that of the human. Studies on the immunolocalization of cynDAZ / DAZL1 in cynomolgus monkey testis revealed a biphasic expression pattern with proteins being detectable in A-pale to B-spermatogonia, late spermatocytes and spermatids, but not in early spermatocytes and late spermatids. In contrast, in the marmoset monkey, an animal lacking DAZ, DAZL1 protein was only expressed in late spermatocytes and early spermatids. These findings point to an additional function of cynDAZ / cynDAZL1 during spermato- genesis in the Old World monkey not needed in the New World monkey.

Animals↗
PubMed1999

Transmission of a Y chromosomal deletion involving the deleted in azoospermia (DAZ) and chromodomain (CDY1) genes from father to son through intracytoplasmic sperm injection: case report.

The transmission of a deleted in azoospermia (DAZ) deletion from a severely oligozoospermic patient to his son following intracytoplasmic sperm injection (ICSI) treatment is reported. The case report highlights the fertilizing capacity of spermatozoa carrying Y chromosome deletions in patients treated with ICSI and stresses the importance of genetic counselling in severe male infertility.

Adult↗
PubMed1999

Mutational analysis of the follicle-stimulating hormone (FSH) receptor in normal and infertile men: identification and characterization of two discrete FSH receptor isoforms.

In a search for pathophysiological causes of idiopathic male infertility we investigated the occurrence of mutations of the FSH receptor in 48 men with this disorder. The entire FSH receptor gene was analyzed by single stranded conformation polymorphism analysis (SSCP). A heterozygous point mutation without functional consequences, exchanging Val to Ala in codon 341, was found in one patient. SSCP analysis led to the identification of 2 polymorphisms in exon 10 associated in 2 discrete FSH receptor allelic variants, i.e. Thr307-Asn680 and Ala307-Ser680. The frequency and distribution of the two allelic variants was further analyzed in 86 proven fathers and 75 infertile men by SSCP (codon 307) and restriction fragment length polymorphism (codon 680). The 2 receptor isoforms showed similar Mendelian distribution in proven fathers and in infertile men. Serum FSH, inhibin B, and combined testicular volume did not differ between subjects with different receptor isoforms. Binding studies in transiently transfected COS-7 cells showed similar binding affinity for the two receptor variants. Moreover, the Ala307-Ser680 and the Thr307-Asn680 FSH receptors responded in vitro to FSH with comparable cAMP production. These data suggest that different isoforms of the FSH receptor with similar functional properties exist in normal and infertile men. We conclude that mutations of the FSH receptor or the FSH receptor genotype do not play a pathogenic role in male idiopathic infertility. The possibility that different FSH isoforms might interact differently with the 2 receptor variants remains to be investigated.

Animals↗
PubMed1999

Role of FSH in male gonadal function.

The production of male gametes depends on the concerted action of the two gonadotropins FSH and LH on the testis. The action of LH is mediated through the production of testosterone by the Leydig cells. Since male germ cells possess neither FSH nor androgen receptors, the action of FSH and testosterone occurs through the Sertoli cells. Although the precise function of these two hormones remains elusive, the existing evidence suggest that both FSH and testosterone are able to stimulate all phases of spermatogenesis. In the male FSH is required for the determination of Sertoli cell number, and for induction and maintenance of normal sperm production. The crucial role of FSH in male gonadal function has been clearly illustrated by the discovery of a patient with an activating mutation of the FSH receptor. This patient had been hypophysectomized because of a pituitary tumor and, under testosterone substitution was unexpectedly fertile in spite of undetectable serum gonadotropin levels and had fathered three children. In this patient we could demonstrate a heterozygous activating mutation of the FSH receptor which resulted in cAMP production independent of FSH stimulation. This finding represents the first description of an activating mutation of the FSH receptor and demonstrates that FSH alone maintains spermatogenesis in man. On the other hand, the effects of the lack of FSH action are unclear. Among five men with a homozygous inactivating mutation of the FSH receptor only one was infertile and spermatogenesis was variably affected in the others. However, serum inhibin B values in these men were not completely suppressed and serum FSH levels were only moderately elevated, indicating the possibility that FSH receptor function was not completely abolished by the mutation. Elimination of FSH action is a prerequisite to suppress completely spermatogenesis for contraceptive purposes, while administration of both LH and FSH is necessary to induce sperm production in patients with hypogonadotropic hypogonadism. Experimental immunization of male monkeys against FSH markedly reduced germ cell proliferation and even induced infertility. At the cellular level, FSH stimulates the cAMP-dependent activation of protein kinase A in Sertoli cells, but the molecular mechanism of FSH action is poorly understood. In the primate, the gonadotropin withdrawal achieved by administration of a GnRH antagonist leads to a premeiotic arrest of germ cell proliferation, probably due to inhibition of the mitotic division of A-pale spermatogonia. Therefore, FSH might be the prime inducer of spermatogonial proliferation, while the successive maturation process could proceed independently of FSH. In summary, clinical and experimental evidence support the concept of an irreplaceble role of FSH in the primate. Only the combination of FSH and testosterone, however, supports a qualitatively and quantitatively fully normal spermatogenesis.

Animals↗
PubMed1998

Molecular cloning and expression of rat contraception associated protein 1 (CAP1), a protein putatively involved in fertilization.

Epididymal fluid from rats rendered infertile by oral administration of ornidazole contains a protein CAP1 (contraception-associated protein 1) that is absent from epididymal fluid, but present on epididymal sperm, from fertile vehicle-treated rats. The gene for CAP1 has been isolated from a rat testis cDNA library and its expression investigated in different tissues. The deduced protein sequence of CAP1 contains 189 amino-acid residues and database searches revealed a high degree of homology (83-95%) with human and mouse DJ-1 at the nucleotide and amino acid levels. Northern blot hybridisation from different rat tissues indicated that CAP1 is encoded by a 1.6-kilobase RNA transcript and seems to be ubiquitiously expressed in the rat with a high level of expression in the testis.

Adult↗
PubMed1998

Identification of allelic variants in the follicle-stimulating hormone receptor genes of females with or without hypergonadotropic amenorrhea.

OBJECTIVE: To determine whether women with idiopathic hypergonadotropic amenorrhea have unique alterations in the FSH receptor gene that could account for reduced activity. DESIGN: Compare FSH receptor genes of affected women with normally menstruating control subjects. SETTING: Center for Reproductive Health and university departments. PATIENT(S): Fourteen female subjects, including four normally menstruating controls; four sibling sisters, two of whom developed premature ovarian failure (POF); four patients with POF; one patient with 46,XX gonadal dysgenesis (GD); and one patient with hypogonadotropic hypogonadism. INTERVENTION(S): Blood samples were collected. MAIN OUTCOME MEASURE(S): Restriction fragment length polymorphism (RFLP) analysis, single-stranded conformation polymorphism analysis, gel electrophoretic mobility of amplified genomic DNA, and FSH receptor gene sequence. RESULT(S): The DNA sequencing revealed allelic variants in one RFLP-positive control. There were two silent variants and one missense variant that resulted in a change from Asp to Gly at position 334 from the start Met in the amino acid sequence. Six of 10 subjects, including controls and patients with POF and GD, had an allelic variant in which A was changed to G at position 919 which caused Thr307 to be changed to Ala. CONCLUSION(S): Allelic variants in the FSH receptor gene occur commonly in control subjects and affected patients.

Alleles↗