AZF Microdeletions in Human Semen Infected with Bacteria--论文代写范文精选

男性不育与许多非遗传性因素有关。非基因因素包括性腺机能减退,和环境因素如生殖器感染。在对男性尿道感染,这是一个重要作用，通过影响不同网站的男性生殖系统,。下面的paper代写范文进行详述。

Abstract
Bacterial infections are associated with infertility in men. This study was aimed to investigate microdeletions on Yq chromosome in semen infected with bacteria by using bacteriological, biochemical, and serological assays. The investigation showed that 107 of 300 (84.80%) semen samples collected from infertile men with primary or secondary infertility were infected with different species of bacteria. Chlamydia trachomatis and Neisseria gonorrheae were the most frequently diagnosed bacteria in the infected semen samples. The percentages of infections of semen samples with C. trachomatis and N. gonorrhea were 42.31% and 35.28% respectively. Genomic DNA from each semen sample infected with predominant bacteria was analyzed for AZF deletions by using multiplex PCR. Different patterns of AZF microdeletions were obtained. It can be concluded that sexually transmitted bacteria may contribute in microdeletions of Yq chromosome by indirectly producing reactive oxygen species and causing gene defect in AZF regions. 
Key Words: Male infertility; Yq microdeletion, Chlamydia trachomatis, Neisseria gonorrheae

Introduction
Male infertility has been associated with a number of non-genetic and genetic factors.1 The non-genetic factors include hypogonadotrophic hypogonadism, previous inguinal and scrotal surgery, and environmental factors such as genital infections. In respect to male urogenital tract infection, it was found that asymptomatic bacteriospermia had an important role in male infertility through affecting different sites of male reproductive tract, such as the testis, the epididymus and male accessory gland.2 The contribution of genetic factors in male infertility has been reported. 

In this respect, it was observed that Yq chromosome, and in particular Yq11.23 was involved in the sexual development and spermatogenesis.3 Yq contains three AZF regions designated AZFa, AZFb, and AZFc from proximal to distal Yq.4 A more recent study reported a new region designated AZFd and it was mapped between STS and sY145-sY221.5 Many microdeletions on Yq have been implicated as significant causes of infertility. These microdeletions are often observed at Azoospermia Factor (AZF) locus.6 AZF locus harbor genes, RBMY (RNA Binding Motif on Y) and DAZ (Deleted in Azoospermia), that involved in spermatogenic failure.7 Many researchers have linked positive bacterial semen cultures with poor semen quality8-10 but to best of our knowledge no study has correlated between the existence of bacteriospermia and gene’s defect on Yq chromosome. Thus, this study was aimed to investigate the occurrence of microdeletions on Yq in semen infected with bacteria.

Patients and Methods 
The study was conducted during January 2010 to December 2010 on 300 infertile men attending Kamal Al-Samaraie Hospital/IVF Center in Baghdad, Iraq. The patients had either primary infertility (n=242) or secondary infertility (n=58). Those patients were interviewed about their medical history, family backgrounds, reproductive problems and possible consanguinities. In addition, a physical examination was conducted in all cases, in order to identify anatomical problems. In addition, 30 fertile men were used as control. Semen samples were obtained after a 7 days period of sex-inhibition. The semen samples were collected from patients following the World health organization (WHO) guidelines11, and were subjected to microbiological tests for identification bacteria. 

Each sample was cultured on different selective media (Blood agar, Chocolate agar, MacConkey agar, Mannitol salt agar, Chromogenic UTI agar) and incubated at 37ºC for 24-48 hrs. After incubation period, the colonies were identified by using standard bacteriological and biochemical assays.12,13 Furthermore, several specific tests were used to detect the suspected colonies, for example BactiCard Neisseria test was used to detect Neisseria gonorrheae, H.V.D.R.L test was used to identify Treponema pallidum, and Furazolidone disk test was used to differentiate Staphylococci from Micrococci.14,15 ELISA assay was also used to detect anti-Chlamydia trachomatis antibodies IgG by using a specific kit (Euroimmune, Germany).16

Results
Out of 300 cultured semen, 107 (84.80%) showed positive bacterial contamination (Table 1). Chlamydia trachomatis antibodies IgG were diagnosed in 58 (42.31%) samples. This bacterium markedly formed higher prevalence in secondary infertile men than primary infertility cases; the percentages were 24.13% and 18.18%, respectively. The second dominant bacteria was Neisseria gonorrheae; it was identified in 27 (11.15%) semen samples obtained from patients had primary infertility and in 14 (24.13%) cases had secondary infertility. In addition, Treponema pallidum was successfully isolated from 3 (1.23%) samples obtained from patients with primary infertility and 2 (3.44%) patients with secondary infertility. Whereas Staphyloccocus aureus was existed in lower incidence; it was found at 0.41% and 1.72% in primary and secondary infertile men respectively. Trailing behind these was Escherichia coli which isolated only from one patient (0.41%) with primary infertility. It is worth mentioning, no culture yielded a mixed growth of bacteria; on the other hand no bacterial isolates were recovered from samples of fertile men’s semen. 

Discussion
The occurrence of male genital tract and/or accessory gland infections has been considered as a potential hazard to male infertility. In this study, 107 (84.80%) of examined seminal fluid samples, collected from 300 patients with primary and secondary infertility, were infected with different species of bacteria: C. trachomatis, N. gonorrheae, T. pallidum, S. aureus, and E. coli. The obtained results showed that C. trachomatis and N. gonorrheae were the most prevalent bacteria isolated from semen; the percentage was 42.31% and 35.28%, respectively. 

It is worth mentioning, other investigators reported that the genital tract infections and inflammation were associated with 8-35% of male’s infertility cases8,19 and these bacteria were considered as asymptomatic bacteriospermia. Furthermore, there are indications that sexually transmitted infections, especially N. gonorrheae and C. trachomatis, account for a significant proportion of cases causing occlusion of the vas deferens and subsequent oligospermia and azoospermia.20 Hosseinzadeh and his group21 reported that the active component of C. trachomatis, lipopolysaccharide, was responsible for sperm death due its spermicidal properties. Research work conducted by Gomez and coworkers showed that the presence of N. gonorrheae in semen may result in azoospermia or oligospermia, then lead to infertility by binding to human sperms, and result in agglutation of sperms and decreasing the sperm’s motility.22 Kauer and his research team23 were able to isolate S. aureus (2.13%) and E. coli (0.14%) from infertile semen’s cultures. 

These bacteria can be considered as commonsalty bacteria. Whereas T. pallidum, a bacterium that cause syphilis, was reported to be associated with male infertility by lowering the sperm count and volume of ejaculate.24 In this study, the possible connection between bacterial infection and potential gene defects in human semen, which infected with predominant bacteriospermia, C. trachomatis and N. gonorrheae, was investigated. Regarding semen infected with C. trchomatis (Table 2), the most frequently microdeletions were seen in AZFc (85.70%). It was reported that the complete deletion in AZFc region (absence of sY254, sY157, sY255, sY242, sY208) means defect in DAZ gene family that had been regarded as the most likely candidate genes for spermatogenesis deficiency.17 

In addition, other study reported deletion in AZFa+b+c+d regions (3 of 44 cases, 6.81%), they suggested that this region probably involves the heterochromatic region on Y chromosome and causes severoligozoospermia.5 Whereas other study conducted by Kin (2004)5 reported that 7.14% of cases had deletion in AZFd, he suggested that deletion in this region may not be associated with extent of defective spermatogenesis. On the other hand, our results (Table 3) showed that the semen infected with N. gonorrheae, revealed 3 (13.63%) cases with primary infertility and the genome harbored deletion in AZFc. The obtained results showed that 14.28% of examined cases gave complete deletion in AZFa and AZFb. 

It had been reported that absence or deletion of AZFa, which harbors two genes, USP9Y and DBY, will cause spermatogenic failure, while deletion of AZFb, which contains RBMY1; will cause spermatogenic arrest.5 Further studies are required to explain the mechanism which causes the deletion. In general, when microbes invade the human body, it produces polymorphonuclear leukocytes and macrophages, which are the major sources of reactive oxygen species (ROS) production.27 Although there is no direct evidence that N. gonorrheae or C. trachomatis increases ROS production, the associated leukocytospermia is well known to produce ROS.28 Most importantly, leukocytospermia has been associated with occult sperm DNA damage, this may occur directly in the form of leukocytospermia, a manifestation of inflammation that is associated with cytokines, which can potentially alter spermatogenesis and cause DNA aberrations, or indirectly as a result of pathological ROS levels, which are frequent in leukocytospermia patients.29(paper代写)

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