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  • 1
    Electronic Resource
    Electronic Resource
    Circadian and ultradian variations of pituitary and pineal hormones in normal men: Evidence for a link between melatonin, gonadotropin, and prolactin secretion (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 18 (1995), S. 0 
    Details
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The study was performed to investigate the physiological relationship between the pineal hormone melatonin and pituitary functions in normal men. Se-ries of blood samples were obtained at 10-min intervals for 24-hr periods from 10 male volunteers (age 19–25 years). Samplings were repeated after 2 weeks and 3 months. Serum levels of melatonin, follicle-stimulating hormone (FSH), luteiniz-ing hormone (LH), prolactin (PRL), and testosterone (T) were estimated by immu-noassay methods (LH, PRL, every sample; melatonin, every 30 min; T, every 4 hrs; FSH once for each session). Diurnal characteristics of PRL and melatonin profiles were estimated by complex cosinor analysis, while short-term pulsatility of LH and PRL secretion was analyzed by the PULSAR algorithm. Data were cor-related by linear regression analysis. The combined information of all three sam-pling sessions revealed significant negative correlations between the following parameters (N = 10): Amplitude (Ampl) melatonin and Ampl PRL: r = -0.727, P 〈 0.02; Ampl melatonin and maximal (Max) PRL values: r = -0.73, P 〈 0.02; Max melatonin and Max PRL: r = -0.725, P 〈 0.02; area under the curve (AUC) melatonin and Ampl PRL: r = -0.637, P 〈 0.05; AUC melatonin and Max PRL: r = -0.640; P 〈 0.05; duration (Dur) of melatonin synthesis and Ampl PRL: r = -0.685, P 〈 0.03; Dur melatonin and Max PRL: r = -0.676, P 〈 0.04; Dur mela-tonin and FSH levels: r = -0.663, P 〈 0. 04; AUC melatonin and LH mean con-centration: r = -0.732, P 〈 0. 02; Max melatonin and LH mean concentration: r = -0.657, P 〈 0.04. These correlations varied considerably between the three ses-sions, mainly due to intra-individual variabilities of secretory patterns of PRL and LH, while the melatonin profiles were comparably stable. The results indicate that melatonin production and pituitary functions may be related in normal men. Be-cause of the substantial intra- and inter-individual variations in hormone secretory patterns, large numbers of volunteers and/or repeated measurements are essential for studies addressing the pineal-pituitary connection in normal humans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1600-079X.1995.tb00138.x
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  • 2
    Electronic Resource
    Electronic Resource
    A male contraceptive pill (1996)
    [s.l.] : Nature Publishing Group
    Nature medicine 2 (1996), S. 722-722 
    Details
    ISSN: 1546-170X
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Medicine
    Notes: [Auszug] To the editor — Pott's conclusion that men would not be susceptible to a systemic method to interrupt their fertility or that such a method might not be physiologically or socially sound is naive and should not go uncontested. He appears to have overlooked the successful research efforts over ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nm0796-722b
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  • 3
    Electronic Resource
    Electronic Resource
    Severe impairment of permatogenesis in mice lacking the CREM gene (1996)
    [s.l.] : Nature Publishing Group
    Nature 380 (1996), S. 162-165 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The vector used to target the CREM gene in embryonic stem (ES) cells is shown in Fig. la. This deletion disrupts the gene and removes the coding information for both of the leucine zipper domains. Leucine zipper domains have been shown to be essential for dimerization and subsequent DNA binding ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/380162a0
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  • 4
    Electronic Resource
    Electronic Resource
    Distinct spectrum of CFTR gene mutations in congenital absence of vas deferens (1997)
    Springer
    Human genetics 〈Berlin〉 100 (1997), S. 365-377 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Congenital absence of the vas deferens (CAVD) is a frequent cause for obstructive azoospermia and accounts for 1%–2% of male infertility. A high incidence of mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene has recently been reported in males with CAVD. We have investigated a cohort of 106 German patients with congenital bilateral or unilateral absence of the vas deferens for mutations in the coding region, flanking intron regions and promotor sequences of the CFTR gene. Of the CAVD patients, 75% carried CFTR mutations or disease-associated CFTR variants, such as the “5T” allele, on both chromosomes. The distribution of mutation genotypes clearly differed from that observed in cystic fibrosis. None of the CAVD patients was homozygous for ΔF508 and none was compound heterozygous for ΔF508 and a nonsense or frameshift mutation. Instead, homozygosity was found for a few mild missense or splicing mutations, and the majority of CAVD mutations were missense substitutions. Twenty-one German CAVD patients were compound heterozygous for ΔF508 and R117H, which was the most frequent CAVD genotype in our study group. Haplotype analysis indicated a common origin for R117H in our population, whereas another frequent CAVD mutation, viz. the “5T allele” was a recurrent mutation on different intragenic haplotypes and multiple ethnic backgrounds. We identified a total of 46 different mutations and variants, of which 15 mutations have not previously been reported. Thirteen novel missense mutations and one unique amino-acid insertion may be confined to the CAVD phenotype. A few splice or missense variants, such as F508C or 1716 G→A, are proposed here as possible candidate CAVD mutations with an apparently reduced penetrance. Clinical examination of patients with CFTR mutations on both chromosomes revealed elevated sweat chloride concentrations and discrete symptoms of respiratory disease in a subset of patients. Thus, our collaborative study shows that CAVD without renal malformation is a primary genital form of cystic fibrosis in the vast majority of German patients and links the particular expression of clinical symptoms in CAVD with a distinct subset of CFTR mutation genotypes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004390050518
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  • 5
    Electronic Resource
    Electronic Resource
    The importance of clinical documentation in genetic studies of male infertility (1995)
    Springer
    Human genetics 〈Berlin〉 96 (1995), S. 500-501 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00191819
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  • 6
    Electronic Resource
    Electronic Resource
    Estimation of the duration of the cycle of the seminiferous epithelium in the non-human primate Macaca mulatta using the 5-bromodeoxyuridine technique (1997)
    Springer
    Cell & tissue research 288 (1997), S. 365-369 
    Details
    ISSN: 1432-0878
    Keywords: Key words: Spermatogenesis ; Testis ; Cell cycle ; Immunohistochemistry ; Macaca mulatta (Primates)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. A comparatively low yield of germ cells has been reported for the spermatogenic process in primates. Kinetic studies of spermatogenesis and the spermatogenic cycle are needed to investigate this phenomenon but require the application of radioactively labeled compounds or irradiation. We have therefore investigated the suitability of a non-radioactive approach, viz., administration of 5-bromodeoxyuridine, for the determination of the kinetics of the spermatogenic cycle in a non-human primate, the rhesus monkey (Macaca mulatta). Four adult in-season animals received a bolus of 33 mg/kg 5-bromodeoxyuridine, one testis from each monkey was removed 3 h later and the other testis after 10 days and 11 h. Tissue was fixed in Bouin’s solution and embedded in Paraplast. 5-Bromodeoxyuridine was localized by immunogold-silver staining with a monoclonal antibody. PAS-hematoxylin counterstaining was used for spermatogenic stage identification. At 3 h, the leptotene and zygotene spermatocytes in stages VII–IX were the most advanced 5-bromodeoxyuridine-positive cells. At 10 days 11 h, the label had advanced and pachytene spermatocytes in stages VI–IX contained 5-bromodeoxyuridine. The duration of the spermatogenic cycle was 10.42±0.07 days (range: 10.25–10.62 days). Peritubular cells and interstitial cells were rarely 5-bromodeoxyuridine-positive, and Sertoli cells were consistently negative for 5-bromodeoxyuridine. Importantly, our kinetic data closely resemble those obtained by means of the application of irradiation for this macaque species. We conclude that administration of 5-bromodeoxyuridine represents a non-radioactive reliable approach for studying kinetic aspects of the spermatogenic process in primates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410050822
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  • 7
    Electronic Resource
    Electronic Resource
    Low Multiple Pregnancy Rates and Reduced Frequency of Cancellation After Ovulation Induction with Gonadotropins, If Eventual Supernumerary Follicles Are Aspirated to Prevent Polyovulation (1998)
    Springer
    Journal of assisted reproduction and genetics 15 (1998), S. 111-116 
    Details
    ISSN: 1573-7330
    Keywords: intrauterine insemination ; ovulation induction ; ultrasound-guided follicle puncture ; ovarian stimulation ; multiple pregnancy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Our purpose was to demonstrate the feasibility of the routine aspiration of supernumerary follicles in infertile patients with imminent polyovulation after ovulation induction with gonadotropins and to examine its effect on the frequency of cycle cancellation and on the (multiple) pregnancy rate. Methods: The data on 796 treatment cycles, performed between 1989 and 1996 on 410 infertile couples, were analyzed retrospectively. From October 1992, whenever necessary, supernumerary ovarian follicles were selectively aspirated transvaginally under ultrasound guidance to prevent the ovulation of more than three follicles. Thereafter, intrauterine insemination was performed. Results: After the adoption of transvaginal ultrasound-guided aspiration of supernumerary follicles into the treatment protocol in October 1992, the number of canceled cycles (P 〈 0.0001) and the multiple pregnancy rate (P 〈 0.01) were significantly reduced compared to those previously. The overall pregnancy rate remained stable. No ovarian hyperstimulation syndrome requiring hospitalization was noted, and no complications resulting from the follicle aspiration were registered. Conclusions: Transvaginal ultrasound-guided aspiration of supernumerary ovarian follicles increases both the efficacy and the safety of ovulation induction with gonadotropins. Because of the limited equipment required, this method represents an alternative for conversion of overstimulated cycles to more costly alternatives such as in vitro fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1023000719569
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  • 8
    Electronic Resource
    Electronic Resource
    Production of reactive oxygen species by and hydrogen peroxide scavenging activity of spermatozoa in an IVF program (1996)
    Springer
    Journal of assisted reproduction and genetics 13 (1996), S. 495-500 
    Details
    ISSN: 1573-7330
    Keywords: catalase ; fertilization ; reactive oxygen species ; scavenging activity ; sperm function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: Reactive oxygen species (ROS) including H2O2 produced by spermatozoa have been suggested, on one hand, to be associated with idiopathic male infertility and, on the other hand, to stimulate certain sperm function leading to fertilization. The influence of ROS on fertilization was investigated in 75 IVF patients by correlating fertilization rates with the production of ROS and the H2O2-scavenging activity of swim-up spermatozoa prepared in parallel with the IVF samples. Results: Low rates of ROS production by the swim-up sperm was detected by the luminol-dependent chemiluminescence assay. They were not correlated with fertilization rates. The hydrogen peroxide scavenging capacity of these spermatozoa, measured as the removal of exogenous H2O2 assayed spectrophotometrically, decreased stepwise in groups of patients achieving higher fertilization rates, suggesting a positive effect of this ROS on fertilization. An alternative explanation of this correlation is plausible in view of the association of both high scavenging activities and poor fertilization rates with poor sperm morphology. Conclusions: ROS produced by spermatozoa selected by swim-up plays no negative, if not a positive, role in fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02066531
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