Absence Of Vas Research Articles

Germ Cell Lineage Homeostasis in Drosophila Requires the Vasa RNA Helicase.

The conserved RNA helicase Vasa is required for germ cell development in many organisms. In Drosophila melanogaster loss of PIWI-interacting RNA pathway components, including Vasa, causes Chk2-dependent oogenesis arrest. However, whether the arrest is due to Chk2 signaling at a specific stage and whether continuous Chk2 signaling is required for the arrest is unknown. Here, we show that absence of Vasa during the germarial stages causes Chk2-dependent oogenesis arrest. Additionally, we report the age-dependent decline of the ovariole number both in flies lacking Vasa expression only in the germarium and in loss-of-function vasa mutant flies. We show that Chk2 activation exclusively in the germarium is sufficient to interrupt oogenesis and to reduce ovariole number in aging flies. Once induced in the germarium, Chk2-mediated arrest of germ cell development cannot be overcome by restoration of Vasa or by downregulation of Chk2 in the arrested egg chambers. These findings, together with the identity of Vasa-associated proteins identified in this study, demonstrate an essential role of the helicase in the germ cell lineage maintenance and indicate a function of Vasa in germline stem cell homeostasis.

178 Low Adherence to Post-Vasectomy Semen Analysis in the VA Population

Post-vasectomy semen analysis (PVSA) is required to confirm the success of vasectomy procedure per established guidelines. We sought to determine the performance of PVSA as well as factors that influenced adherence in veterans who underwent vasectomy over a 10-year period. A retrospective review of men who underwent vasectomy at our Veterans Administration Medical Center between January 2006 and May 2016 was performed. All patients had pre-procedure consultation and counselling at least once. Counselling included emphasis that PVSA was required for definitive confirmation of the procedure's success and other contraceptive methods should be used prior to negative PVSA. Vasectomies were performed under local anesthesia in the outpatient clinic setting or under general anesthesia in the operating room. All specimens were sent for pathologic confirmation of presence or absence of vas with lumen. Post-vasectomy management included follow-up in in 2-4 weeks for wound check with semen analysis performed within 1-3 months after 15-20 post-procedural ejaculations. Standard statistical analysis was performed to assess for factors that predicted adherence to PVSA.

Cystic fibrosis transmembrane conductance regulator mutations and polymorphisms associated with congenital bilateral absence of vas deferens in a restricted group of patients from North Africa

Background: Congenital bilateral absence of vas deferens (CBAVD) is responsible for 2–6% of male infertility. It occurs in 95% of men with cystic fibrosis.This malformation is present in patients with a sterile obstructive azoospermia but without clinical evidence of cystic fibrosis. Molecular study of the cystic fibrosis transmembrane conductance regulator (CFTR) gene responsible for cystic fibrosis could show the relationship between this disease and bilateral absence of vas deferens.Patients and methods: The study involved 20 male patients aged between 28–40 years, referred with suspected cystic fibrosis and in whom bilateral absence of vas deferens was confirmed by cyto-biochemical analyses and urogenital ultrasound. Molecular study of the CFTR gene was based on several techniques: DHPLC, DGGE and direct sequencing.Results: Thirteen patients had CFTR mutations: F508del, G542X, W1282X, E1104X, 711+1G → T, V201M (TG) m and IVS8-5T. These mutations were associated with polymorphisms: M470V and D1270N. Seven cases presented only polymorphisms.Conclusion: The different mutations found in this study were associated with polymorphisms which decrease the severity of the disease and delay its onset. Thus, bilateral agenesis of the vas deferens is classed as a form of cystic fibrosis with only genital expression.

Fertility in Men With Cystic Fibrosis: An Update on Current Surgical Practices and Outcomes

Men with cystic fibrosis (CF) have bilateral absence of the vas deferens causing an obstructive azoospermia that is not amenable to surgical correction. Advances in the field of reproductive medicine allow for the procurement of viable sperm and facilitate fertilization and pregnancy in couples where the man has CF. To describe patient anatomy and semen characteristics and to determine the pregnancy rates of couples in whom the male partner has CF and who have undergone microsurgical epididymal sperm aspiration coupled with in vitro technology, specifically intracytoplasmic sperm injection (ICSI). Retrospective analysis. Clinical department of urology and two reproductive medicine units. Thirteen married men with CF who were referred for infertility. History, physical examination, semen analysis, transrectal and renal ultrasonography, CF mutation analysis, and microsurgical sperm aspiration coupled with ICSI. All 13 men had low-volume azoospermia, absent vasa, and aplasia/hypoplasia of the seminal vesicles. CF mutation analysis was carried out in 11 of 13 men, and 9 of 11 were DeltaF508 homozygous. Eight men underwent microsurgical sperm aspiration, and their partners underwent one or more cycles of ICSI. Five couples (62.5%) achieved a pregnancy, with four couples delivering (three sets of twins and one singleton). CF in men is accompanied by bilateral vasal aplasia. The resultant obstructive azoospermia can be treated quite successfully with a combination of sperm aspiration and ICSI. It is important for physicians involved in the care of men with CF to convey the message that prospects for fatherhood are excellent with current technology.

A modern view of male infertility

It is archaic to view male factor infertility today separately from in vitro fertilization (IVF) and treatment of the female partner. Oligoasthenozoospermia may be an inherited condition (most likely on the Y chromosome), and is refractory to any treatment of the male including hormones and varicocelectomy. IVF technology is the only justifiable approach for achieving a pregnancy in these couples. The reasons for this view and the suggested modern approach to couples with oligoasthenozoospermia are outlined in this review. However, obstructive azoospermia is different as it can be successfully corrected with microsurgery in over 90% of men. When it cannot be corrected, as in congenital absence of vas, microsurgical sperm retrieval combined with IVF can still be highly effective in producing pregnancy with sperm from the husband. The most important arena for research into male infertility in the next decade will be to map out the deletions on the Y chromosome that might result in defective spermatogenesis, and which probably cause most cases of non-obstructive male factor infertility.

Congenital bilateral absence of the vas deferens and cystic fibrosis. A genetic commonality.

CF and CBAVD are really just ends of a clinical spectrum. The type and nature of the mutations in the CF gene probably determine the phenotypic expression of the patient. Perhaps all patients homozygous for delta F508, for example, will have severe pulmonary and pancreatic disease as well as absent vasa, whereas those with other combinations, such as delta F508/D1270N, will be unaffected in terms of pulmonary and pancreatic function but will have absent vasa. Besides contributing to a better understanding of the nature of CBAVD, this linkage of CF and CBAVD most importantly mandates genetic screening and counseling for appropriate family members and even the patient's spouse. In addition, a broader understanding of CF is now at hand, as this brings a whole new cohort of patients under the CF umbrella. Many of these will have at least one, if not two, rare or novel CF gene mutations. Once all of these mutations have been detected and defined, our knowledge of the CF gene, its mutations, and their implications will be dramatically expanded.

Cystic fibrosis and absence of vasa

Cystic fibrosis and absence of vasa

Further observations on the mechanism of ulcer pain.

Excerpt Direct chemical irritation by hydrochloric acid and disordered motor activity of the stomach and duodenum have been implicated in the causation of ulcer pain. The presence or absence of vas...