Reactive oxygen and nitrogen species during meiotic resumption from diplotene arrest in mammalian oocytes

Mammalian ovary is metabolically active organ and generates by‐products such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) on an extraordinary scale. Both follicular somatic cells as well as oocyte generate ROS and RNS synchronously and their effects are neutralized by intricate array of antioxidants. ROS such as hydrogen peroxide (H₂O₂) and RNS such as nitric oxide (NO) act as signaling molecules and modulate various aspects of oocyte physiology including meiotic cell cycle arrest and resumption. Generation of intraoocyte H₂O₂ can induce meiotic resumption from diplotene arrest probably by the activation of adenosine monophosphate (AMP)‐activated protein kinase A (PRKA)—or Ca²⁺‐mediated pathway. However, reduced intraoocyte NO level may inactivate guanylyl cyclase‐mediated pathway that results in the reduced production of cyclic 3′,5′‐guanosine monophosphate (cGMP). The reduced level of cGMP results in the activation of cyclic 3′,5′‐adenosine monophosphate (cAMP)‐phosphodiesterase 3A (PDE3A), which hydrolyses cAMP. The reduced intraoocyte cAMP results in the activation of maturation promoting factor (MPF) that finally induces meiotic resumption. Thus, a transient increase of intraoocyte H₂O₂ level and decrease of NO level may signal meiotic resumption from diplotene arrest in mammalian oocytes. J. Cell. Biochem. 111: 521–528, 2010. © 2010 Wiley‐Liss, Inc.     

A 12-Crown-4 Ether Containing Dipeptide Boc-12-Crown-4-<Emphasis Type="SmallCaps">l</Emphasis>-DOPA-Gly-OMe Induces Cell Cycle Arrest and Apoptosis in Rat Eggs Cultured In Vitro

The study was designed to investigate whether crown ether containing dipeptide Boc-12-crown-4-l-DOPA-Gly-OMe has potential to induce meiotic cell cycle arrest and apoptosis in rat eggs cultured in vitro. The immature female rats were subjected to superovulation induction protocol and ovulated eggs were collected from ampulla of the fallopian tube. Ovulated eggs arrested at metaphase-II (M-II) stage of meiotic cell cycle were cultured in media-199 with or without various concentrations (0.0, 0.025, 0.050, 0.10, and 0.20 mM) of dipeptide for 3 h in vitro. Morphological apoptotic changes, hydrogen peroxide (H₂O₂) concentration, cytochrome c level, caspase-3 level as well as activity and DNA fragmentation were analysed in eggs cultured in vitro. Culture of M-II arrested eggs in plain medium for 3 h in vitro induced meiotic exit from M-II arrest in majority of eggs as evidenced by initiation of extrusion of second polar body (II PB). The dipeptide induced maintenance of M-II arrest and morphological apoptotic features in a concentration-dependent manner prior to degeneration. The dipeptide-induced morphological features were associated with increased H₂O₂ and cytochrome c levels in treated eggs. The increased cytochrome c induced caspase-3 level and activity and thereby DNA fragmentation as evidenced by DAB positive staining in treated eggs. Our results suggest that dipeptide Boc-12-C-4-l-DOPA-Gly-OMe induces cell cycle arrest at M-II stage and apoptosis in rat eggs cultured in vitro.     

Airborne fungal spores in an industrial area: seasonal and diurnal periodicity

Qualitative and quantitative studies of atmospheric fungal spores at a chloralkali factory, Jayashree Chemicals. were made during 1993 employing culture plate and rotorod methods. A total of 57 sporulating fungal types, including three sterile mycelial forms, were recorded by the culture plate method and 51 spore types, including the hyphal fragments and unidentified spores, were recorded by the rotorod method. As to the seasonal variation, winter was found to be the greatest contributor of fungal spores as compared to the summer and rainy season. Instead, when considering the hour of the day, the peak number of fungal propagules was recorded at noon (12.00 h) followed by evening and morning values, an exception being recorded in winter months, when maximum CFUs ofCladosporium were monitored in the morning. The seasonal variation in fungal concentration and composition was found to be influenced by temperature, rainfall and relative humidity, whereas diurnal incidence was the effect of varying temperature and relative humidity during day time only. Moderate temperature and relative humidity favoured the maximum fungal spore load in the atmosphere.Cladosporium, Nigrospora, Alternaria, Lasiodiplodia, Drechslera, Pestalotia, Curvularia, Epicoccum, Aspergillus, Penicillium andChaetomium were the commonest fungal spores in the factory area.     

Afropolitan projects: African immigrant identities and solidarities in the United States

This article explores how Africans born or raised in the United States employ ethnicity to understand their racial and cultural identities. I argue that African immigrants engage positive narratives about Africa along with their experiences of anti-black racism to articulate identities as “Africans of the world”. I call this articulation of identity Afropolitan projects. The Afropolitan as an ethnicity is not meant to shield Africans from anti-black racism, but instead helps articulate a particular relationship to this form of inequality. The following analysis derives from a qualitative case study of a voluntary association comprising Ghanaians primarily raised in the United States. I find that the group’s identity is as much about being black, African, and American as it is about being middle-class, Christian, and heterosexual. Through their Afropolitan projects, this group emphasizes solidarities with a global middle-class heterosexual patriarchy while foreclosing solidarities with working class, queer, and other people of colour.     

Risk of Deaths,AIDS-Defining and Non-AIDS Defining Events among Ghanaians on Long-Term Combination Antiretroviral Therapy

Combination antiretroviral therapy (cART) has been widely available in Ghana since 2004. The aim of this cohort study was to assess the incidences of death, AIDS-defining events and non-AIDS defining events and associated risk factors amongst patients initiating cART in a large treatment centre. Clinical and laboratory data were extracted from clinic and hospital case notes for patients initiating cART between 2004 and 2010 and clinical events graded according to recognised definitions for AIDS, non-AIDS events (NADE) and death, with additional events not included in such definitions such as malaria also included. The cumulative incidence of events was calculated using Kaplan Meier analysis, and association of risk factors with events by Cox proportional hazards regression. Data were closed for analysis on 31^st December, 2011 after a median follow-up of 30 months (range, 0–90 months). Amongst 4,039 patients starting cART at a median CD4 count of 133 cells/mm³, there were 324 (8%) confirmed deaths, with an event rate of 28.83 (95% CI 25.78–32.15) deaths per 1000-person follow-up years; the commonest established causes were pulmonary TB and gastroenteritis. There were 681 AIDS-defining events (60.60 [56.14–65.33] per 1000 person years) with pulmonary TB and chronic diarrhoea being the most frequent causes. Forty-one NADEs were recorded (3.64 [2.61–4.95] per 1000 person years), of which hepatic and cardiovascular events were most common. Other common events recorded outside these definitions included malaria (746 events) and respiratory tract infections (666 events). Overall 24% of patients were lost-to-follow-up. Alongside expected risk factors, stavudine use was associated with AIDS [adjusted HR of 1.08 (0.90–1.30)] and death (adjusted HR of 1.60 [1.21–2.11]). Whilst frequency of AIDS and deaths in this cohort were similar to those described in other sub-Saharan African cohorts, rates of NADEs were lower and far exceeded by events such as malaria and respiratory tract infections.