Frank-Michael Köhn

Bio: Frank-Michael Köhn is an academic researcher from University of Giessen. The author has contributed to research in topics: Medicine & Gynecology. The author has an hindex of 4, co-authored 15 publications receiving 1253 citations.

Human Y Chromosome Azoospermia Factors (AZF) Mapped to Different Subregions in Yq11

Abstract: In a large collaborative screening project, 370 men with idiopathic azoospermia or severe oligozoospermia wereanalysed for deletions of 76 DNA loci in Yq11. In 12 individuals, we observed de novo microdeletions involvingseveral DNA loci, while an additional patient had an inherited deletion. They were mapped to three differentsubregions in Yq11. One subregion coincides to the AZF region defined recently in distal Yq11. The second andthird subregion were mapped proximal to it, in proximal and middle Yq11, respectively. The different deletionsobserved were not overlapping but the extension of the deleted Y DNA in each subregion was similar in eachpatient analysed. In testis tissue sections, disruption of spermatogenesis was shown to be at the same phasewhen the microdeletion occurred in the same Yq11 subregion but at a different phase when the microdeletionoccurred in a different Yq11 subregion. Therefore, we propose the presence of not one but three spermatogenesisloci in Yq11 and that each locus is active during a different phase of male germ cell development. As the mostsevere phenotype after deletion of each locus is azoospermia, we designated them as: AZFa, AZFb and AZFc.Their probable phase of function in human spermatogenesis and candidate genes involved will be discussed. INTRODUCTIONGenes for male germ cell development are present on the Ychromosome in different species groups (1–3). In men, theposition of a spermatogenesis locus was mapped in theeuchromatic part of the long Y arm (Yq11). It was called‘azoospermia factor’ (AZF), as the first six men observed withterminal deletions in Yq were azoospermic (4). Mature spermcells were not detectable in their seminal fluid. In all cases, the Ydeletions included the large heterochromatin block of the long Yarm (Yq12) and an undefined amount of the adjacent euchromatin(Yq11). Subsequently, the presence of AZF in Yq11 wasconfirmed by numerous studies at both cytogenetic (5) andmolecular level (6–8). However, the genetic complexity of AZFcould not be revealed by these analyses.This first became possible by the detection of sterile patientswith small interstitial deletions (i.e. microdeletions) in Yq11. Ina study with 13 sterile men suffering from idiopathic azoospermiatwo different microdeletions in Yq11 were observed (9). Theywere mapped to two non overlapping positions in Yq11 interval6 (10). However, further studies of Yq11 microdeletionsassociated to the phenotype of male sterility, only confirmed theposition of an AZF locus in distal Yq11 (11,12). The mostextensive study was performed by Reijo et al. (13) on 89 sterile

Diagnostik, Klinik und Therapie der frühen Chromoblastomykose an einem Fallbeispiel

Abstract: Despite the availability of modern antimycotics, which produce high cure rates in early infections, the therapy of advanced chromoblastomycosis is still unsatisfactory. An initial chromoblastomycosis caused by a hitherto unidentified species of the genus Phialophora was diagnosed in a 46-year-old teacher. The organism was isolated twice at an interval of 6 weeks from a partly psoriasiform, partly verrucous lesion on the 4th toe. The infection was apparently acquired 4 years ago during a holiday at Cape Verde. Treatment with itraconazole (Sempera). 200 mg/day, and amphotericin B (Ampho-Moronal) cream for 6 weeks initially resulted in rapid regression. However, 4 weeks after cessation of therapy, the Phialophora species was cultured again from skin scrapings. Complete healing was achieved after re-treatment with itraconazole for 20 weeks at the same dosage in combination with topical amorolfine and local hyperthermia. Until now, no relapse has occurred. The present case demonstrates that this rare disease, which mainly occurs as a traumatic mycosis in the rural population of tropical regions, must be included in the differential diagnosis of psoriasiform or verrucous skin lesions and also included in the list of diseases which may be acquired while on vacation in exotic locations.

Hydrogen hexachloroplatinate induces the acrosome reaction in human spermatozoa

Abstract: Summary Human spermatozoa from healthy donors (n= 7) were washed in Tyrode's medium containing 0.6 mg/ml freeze-dried egg yolk, filtered through glass wool and exposed to 0.5, 5, 50, 500 or 1000 μM hydrogen hexachloroplatinate. Viability, membrane integrity and the acrosome reaction were examined using trypan blue exclusion, hypo-osmotic swelling test and fluoresceinated Pisum sativum agglutinin, respectively, after incubation for 3 or 6 h at 37°C. While sperm motility, viability and membrane integrity were not affected by the platinum compound after incubation for 3 h, the number of acrosome-reacted spermatozoa increased from 16.0 ± 6.4% (control, mean ± SEM) to 21.0 ± 3.3 (0.5 μM), 22.3 ± 4.3% (5 μM), 28.0 ± 4.3% (50 μM, p<0.01), 29.3 ± 3.9% (500 μM, p<0.01) and 43.9 ± 7.4% (1mM, p<0.001); a further increase was detected after incubation for 6 h. However, the percentages of dead and immotile spermatozoa and those with defective membranes were also higher, suggesting that the acrosome reaction was caused by degenerative processes after long-term incubation. In conclusion, hydrogen hexachloroplatinate does not affect sperm motility, membrane integrity or viability, but it does induce the acrosome reaction after incubation for 3 h before cytotoxic effects are measurable. Similar effects of halide salts of platinum on receptor-mediated exocytosis have been described in other cells such as mast cells and basophils in vivo and in vitro.

Corona and Reproduction, or Why the Corona Vaccination Does Not Result in Infertility

Abstract: Background As the COVID-19 pandemic persists and new vaccines are developed, concerns among the general public are growing that both infection with the SARS-CoV-2 virus and vaccinations against the coronavirus (mRNA vaccines) could lead to infertility or higher miscarriage rates. These fears are voiced particularly often by young adults of reproductive age. This review summarizes the current data on the impact of SARS-CoV-2 infection and corona vaccinations on female and male fertility, based on both animal models and human data. Method A systematic literature search (PubMed, Embase, Web of Science) was carried out using the search terms “COVID 19, SARS-CoV-2, fertility, semen, sperm, oocyte, male fertility, female fertility, infertility”. After the search, original articles published between October 2019 and October 2021 were selected and reviewed. Results Despite the use of very high vaccine doses in animal models, no negative impacts on fertility, the course of pregnancy, or fetal development were detected. In humans, no SARS-CoV-2 RNA was found in the oocytes/follicular fluid of infected women; similarly, no differences with regard to pregnancy rates or percentages of healthy children were found between persons who had recovered from the disease, vaccinated persons, and controls. Vaccination also had no impact on live-birth rates after assisted reproductive treatment. No viral RNA was detected in the semen of the majority of infected or still infectious men; however, a significant deterioration of semen parameters was found during semen analysis, especially after severe viral disease. None of the studies found that corona vaccines had any impact on male fertility. Discussion Neither the animal models nor the human data presented in recent studies provide any indications that fertility decreases after being vaccinated against coronavirus. However, there is a growing body of evidence that severe SARS-CoV-2 infection has a negative impact on male fertility and there is clear evidence of an increased risk of complications among pregnant women with SARS-CoV-2 infection. The counseling offered to young adults should therefore take their fears and concerns seriously as well as providing a structured discussion of the current data.

Medikamentöse Therapie bei männlichen Fertilitätsstörungen und Hypogonadismus

Abstract: Kausale medikamentose Therapieregime mit in kontrollierten Studien zweifelsfrei nachgewiesener Wirksamkeit stehen nur bei mannlicher Infertilitat als Folge des hypogonadotropen Hypogonadismus zu Verfugung. Eine medikamentose Therapie der retrograden Ejakulation ist ebenfalls effektiv, wurde aber bisher nicht durch doppelblinde, plazebo-kontrollierte, randomisierte Studien uberpruft. Im Gegensatz dazu sind die Angaben bei empirischer Therapie mit z. B. Kallikrein, Tamoxifen, Clomiphen, Pentoxifyllin, Mastzellblockern, Testolakton, Vitamin E, Captopril, alpha-Rezeptoren-Blockern, Glutathion, Indometacin, Interferon alpha, Wachtumshormon, Zinksalzen, Ketoprofen, Mesterolon oder Testosteronundecanoat entweder widerspruchlich oder die vorgelegten Studien reichen fur eine abschliesende Bewertung noch nicht aus. Neuere Studien weisen moglicherweise auf eine Beeinflussung von Spermatozoenfunktionen durch pures FSH hin. Dahingegen haben GnRH und FSH bei normogonadotropen Mannern keinen Einflus auf die Spermatogenese.

Multiplex PCR: critical parameters and step-by-step protocol.

Abstract: By simultaneously amplifying more than one locus in the same reaction, multiplex PCR is becoming a rapid and convenient screening assay in both the clinical and the research laboratory. While numerous papers and manuals discuss in detail conditions influencing the quality of PCR in general, relatively little has been published about the important experimental factors and the common difficulties frequently encountered with multiplex PCR. We have examined various conditions of the multiplex PCR, using a large number of primer pairs. Especially important for a successful multiplex PCR assay are the relative concentrations of the primers at the various loci, the concentration of the PCR buffer, the cycling temperatures and the balance between the magnesium chloride and deoxynucleotide concentrations. Based on our experience, we propose a protocol for developing a multiplex PCR assay and suggest ways to overcome commonly encountered problems.

Functional coherence of the human Y chromosome.

Abstract: A systematic search of the nonrecombining region of the human Y chromosome (NRY) identified 12 novel genes or families, 10 with full-length complementary DNA sequences. All 12 genes, and six of eight NRY genes or families previously isolated by less systematic means, fell into two classes. Genes in the first group were expressed in many organs; these housekeeping genes have X homologs that escape X inactivation. The second group, consisting of Y-chromosomal gene families expressed specifically in testes, may account for infertility among men with Y deletions. The coherence of the NRY's gene content contrasts with the apparently haphazard content of most eukaryotic chromosomes.

Oxidative stress, DNA damage and the Y chromosome.

Abstract: Recent advances in understanding of male infertility have implicated two major causative factors, oxidative stress and Y chromosome deletions. A major cause of oxidative stress appears to be the high rate of reactive oxygen species generation associated with the retention of excess residual cytoplasm in the sperm midpiece. Other possible causes include the redox cycling of xenobiotics, and antioxidant depletion or apoptosis. Oxidative stress induces peroxidative damage in the sperm plasma membrane and DNA damage in both the mitochondrial and nuclear genomes. Nuclear DNA damage in the germ line of the father may be associated with pathology in the offspring, including childhood cancer and infertility. Gene deletions on the non-recombining region of the Y chromosome account for the infertility observed in about 15% of patients with azoospermia and 5-10% of subjects with severe oligozoospermia. The Y chromosome is particularly susceptible to gene deletions because of the inability of the haploid genome to deploy recombination repair in retrieving lost genetic information. Aberrant recombination, defective chromatin packaging, abortive apoptosis and oxidative stress may all be involved in the aetiology of DNA damage in the germ line. The factors responsible for Y chromosome deletions in spermatozoa remain unresolved but may be one facet of a central reproductive problem: controlling the amount of oxidative stress experienced by germ cells during their differentiation and maturation in the male reproductive tract.