The role of retinoic acid in the commitment to meiosis / 亚洲男科学杂志(英文版)

Male meiosis is a complex process whereby spermatocytes undergo cell division to form haploid cells. This review focuses on the role of retinoic acid (RA) in meiosis, as well as several processes regulated by RA before cell entry into meiosis that are critical for proper meiotic entry and completion. Here, we discuss RA metabolism in the testis as well as the roles of stimulated by retinoic acid gene 8 (STRA8) and MEIOSIN, which are responsive to RA and are critical for meiosis. We assert that transcriptional regulation in the spermatogonia is critical for successful meiosis.

Effects of mono-[2-ethylhexyl] phthalate and DI-[2-ethylhexyl] phthalate administrations on oocyte meiotic maturation, apoptosis and gene quantification in mouse model

Objective: Phthalates, which are commonly used to render plastics into soft and flexible materials, have also been determined as developmental and reproductive toxicants in human and animals. The purpose of this study was to evaluate the effect of mono-[2-ethylhexyl] phthalate [MEHP] and di-[2-ethylhexyl] phthalate [DEHP] oral administrations on maturation of mouse oocytes, apoptosis and gene transcription levels

Materials and Methods: In this experimental study, immature oocytes recovered from Naval Medical Research Institute [NMRI] mouse strain [6-8 weeks], were divided into seven different experimental and control groups. Control group oocytes were retrieved from mice that received only normal saline. The experimental groups I, II or III oocytes were retrieved from mice treated with 50, 100 or 200 micro l DEHP [2.56 micro M] solution, respectively. The experimental groups IV, V or VI oocytes were retrieved from mouse exposed to 50, 100 or 200 micro l MEHP [2.56 micro M] solution, respectively. Fertilization and embryonic development were carried out in OMM and T6 medium. Apoptosis was assessed by annexin V-FITC/Dead Cell Apoptosis Kit, with PI staining. In addition, the mRNA levels of Pou5f1, Ccna1 and Asah1 were examined in oocytes. Finally, mouse embryo at early blastocyst stage was stained with acridine-orange [AO] and ethidium-bromide [EB], in order to access their viability

Results: The proportion of oocytes that progressed up to metaphase II [MII] and 2-cells embryo formation stage was significantly decreased by exposure to MEHP or DEHP, in a dose-dependent manner. Annexin V and PI positive oocytes showed greater quantity in the treated mice than control. Quantitative reverse transcriptase-polymerase chain reaction [qRT-PCR] revealed that expression levels of Pou5f1, Asah1 and Ccna1 were significantly lower in the treated mouse oocytes than control. The total cell count for blastocyst developed from the treated mouse oocytes was lower than the controls

Conclusion: These results indicate that oral administration of MEHP and DEHP could negatively affect mouse oocyte meiotic maturation and development in vivo, suggesting that phthalates could be risk factors for mammalians' reproductive health. Additionally, phthalate-induced changes in Pou5f1, Asah1 and Ccna1 transcription level could explain in part, the reduced developmental ability of mouse-treated oocytes

Inducible protective processes in animal systems XV: Hyperthermia enhances the Ethyl methanesulfonate induced adaptive response in meiotic cells of grasshopper Poecilocerus pictus

Purpose: To understand the role of hyperthermia in adaptive response, Ethyl methanesulfonate [EMS] an anticarcinogenic agent, adapted meiotic cells of Poecilocerus pictus was used

Materials and methods: Based on the pilot toxicity study, the effective higher temperatures of 40[degree sign]C and 45[degree sign]C for 15 or 30 min were chosen. P. pictus were treated with conditioning [L] or challenging [H] doses of EMS and 2 h time lag [TL] between these doses [L-2 h-H] was employed. Different treatment schedules were used to analyze the influence of hyperthermia on EMS induced adaptive response namely [i] pre treatment; [ii] inter treatment; [iii] post treatment and [iv] cross adaptation. After each treatment schedule, animals were sacrificed at 12, 24, 36 and 48 h recovery times, testes were processed for meiotic chromosome preparations and anomalies were analyzed

Results: The frequencies of anomalies induced by both conditioning and challenging doses of EMS were significantly higher [p< 0.05] compared to those of the control and hyperthermia groups. The combined treatments resulted in 44-50% reduction compared to additive effect of EMS. The pre, inter, post and cross adaptation treatments with hyperthermia significantly reduced the frequencies of chromosomal anomalies compared to the challenge and combined treatments with EMS at all recovery times [p< 0.05] tested

Conclusion: There is a protection against EMS induced anomalies by hyperthermia in in vivo P. pictus. As far as our knowledge is concerned, this is the first report to demonstrate that hyperthermia enhances the EMS induced adaptive response in in vivo meiotic cells

Dieta y cáncer gástrico en México y en el mundo / Diet and gastric cancer in Mexico and in the world

El cáncer gástrico (CG) es la cuarta causa de muerte por cáncer a nivel global. La dieta y el consumo de alcohol y tabaco, además de la infección por Helicobacter pylori determinan un gran número de casos de esta neoplasia. Algunos alimentos contienen sustancias que podrían influir en el proceso de carcinogénesis gástrica, aunque los mecanismos subyacentes no están completamente dilucidados. En México y el mundo, la disminución en el consumo de frutas, vegetales no feculentos y allium, leguminosas y alimentos fuente de selenio, así como el aumento en el consumo de sal, alimentos salados, salmuera y ahumados, chile, carnes procesadas y asadas o a la parrilla se han asociado respectivamente con un aumento de riesgo de CG. Con la evidencia disponible, se podrían desarrollar y evaluar programas para la prevención y control del CG.

Gastric cancer (GC) is the fourt leading cause of cancer death at global level. Diet, alcohol and tobacco, in addition to Helicobacter pylori infection, account for a large number of cases. Some substances contained in foods may influence GC carcinogenesis process; however, the underlying mechanisms have not been fully elucidated. In Mexico and worldwide, a low intake of fruits, non-starchy and allium vegetables, pulses, and foods containing selenium, as well as high intake of salt, salty, salted and smoked foods, chili pepper, processed and grilled/barbecued meats, have been respectively associated with an increased risk of GC. Based on the available evidence, programs for GC prevention and control could be developed and evaluated.

influence of meiotic spindle configuration by cysteamine during in vitro maturation of mouse oocytes

The aim of this study was to assess effects of cysteamine as an anti-oxidant on rate of in vitro maturation of oocyte and determination of its effects on spindle size and shape. Pre-mature mice were primed with pregnant mare stimulating gonadotrophin [PMSG] and germinal vesicle [GV] stage oocytes were obtained 48 h after. The oocytes were cultured in tissue culture medium [TCM 199] with 50, 100, 200 and 500 microM cysteamine. Experiments also included a group of ovulated oocytes [in vivo matured] after priming with PMSG and human chorionic gonadotrophin. For spindle immuno-cytochemistry of metaphase II [MII], oocytes alpha and beta tubulin antibody were performed. Chromosome staining was performed with Hoechst. Our results showed that the rate of GV breakdown [GVBD] and MII increased in all cysteamine groups except in group cultured with 500 microM cysteamine. Immuno-cytochemistry analysis showed that spindle area in all in vitro Maturation oocytes increased when compared to in vivo oocytes. Spindle shape and size [spindle area] in 100 microM cysteamine in comparison to in vivo group was insignificant [P>0.05]. Our results revealed that cysteamine improved IVM rate in a dose dependant manner. The size and shape of spindle in the presence of given concentration of cysteamine was similar to in vivo. Therefore, cysteamine improved microtubule organization, rate of GVBD and MIl development

[Effect of fibroblastic growth factor on resumption of meiosis, in vitro maturation and embryo development of immature mouse oocytes]

The purpose of this study was to evaluate the effect of fibroblastic growth factor on resumption of meiosis, in vitro maturation of immature mouse oocytes and resulting embryo development with and without basic fibroblastic growth factor-4 [bFGF-4].Cumulus - oocyte complex [COCs] and germinal vesicle [GV] were obtained from female NMRI mice 46-48 hours after administration of an intra-peritoneal injection of 5 IU PMSG. COCs were cultured in TCM199 supplemented with different dosages of bFGF-4. After 24 hours, metaphase II [MII] oocytes were co-incubated with sperms for 4-6 hours in 16 medium. For all groups, the rate of cleaved embryos was assessed in the T6 medium until blastocyst stage. In all compared groups, the percentage of matured MII oocytes in the 10 ng/ml [%94.4] and 20 ng/ml [%92.5] of bFGF-4 treatment groups, was significantly higher [P<0.05] than those of the control group but the percentage of embryos that developed to blastocyst in 20 ng/ml bFGF-4 treatment group was significantly higher than those of the control group [P<0.05]. Exogenous bFGF-4 improved the oocyte maturation and embryo development

Effect of beta-mercaptoethanol or epidermal growth factor supplementation on in vitro maturation of canine oocytes collected from dogs with different stages of the estrus cycle

Supplementation of beta-mercaptoethanol (beta-ME) in in vitro maturation (IVM) medium was shown to improve embryo development and quality in several species. Epidermal growth factor (EGF) was also shown to improve IVM of human oocyte and embryo development after in vitro fertilization (IVF). The effect of these two compounds were suggested to be mediated through the synthesis of glutathione (GSH) which is known to play an important role in protecting the cell or embryos from oxidative damage. Thus, it is suggested that supplementation of canine IVM medium with beta-ME or EGF may be of benefit due to its positive role in IVM of various mammalian oocytes and embryo development, including cattle, pigs, rodents and humans. This study investigates the effect of ovarian estrus stage on canine oocyte quality and supplementation of medium with beta-ME or EGF on IVM of canine oocytes. As results, a significantly higher percentage of oocytes progressed to metaphase II (MII) stage in 50 or 100 microM of beta-ME supplemented oocytes collected from the follicular stage. The maturation rate to metaphase I (MI) stage was also significantly higher in oocytes collected from follicular stage and cultured with 25 or 100 microM compared to other experimental groups. After IVM culture, oocytes recovered from dogs with the follicular stage and matured in TCM-199 supplemented with 20 ng/ml EGF yielded better oocyte maturation to MII phase compared to other groups. Taken together, supplementation of beta-ME (50 or 100 microM) or EGF (20 ng/ml) improved IVM of canine oocytes to MII stage.