Constitutive CD8 expression allows inefficient maturation of CD4+ helper T cells in class II major histocompatibility complex mutant mice.

Although mature CD4+ T cells bear T cell receptors (TCRs) that recognize class II major histocompatibility complex (MHC) and mature CD8+ T cells bear TCRs that recognize class I MHC, it is possible that the initial commitment of an immature thymocyte to a CD4 or CD8 lineage is made without regard to the specificity of the TCR. According to this model, CD4+ cells with class I TCR do not mature because the CD8 coreceptor is required for class I MHC recognition and positive selection. If this model is correct, constitutive expression of CD8 should allow CD4+ T cells with class I-specific TCRs to develop. In this report, we show that mature peripheral CD4+ cells are present in class II MHC-deficient mice that express a constitutive CD8.1 transgene. These cells share a number of properties with the major class II MHC-selected CD4 population, including the ability to express CD40 ligand upon activation. Although mature CD4 cells are also detectable in the thymus of class II MHC mutant/CD8.1 transgenic mice, they represent a small fraction of the mature CD4 cells found in mice that express class II MHC. These results indicate that some T cells choose the CD4 helper lineage independent of their antigen receptor specificity; however, the inefficiency of generating class I-specific CD4 cells leaves open the possibility that an instructive signal generated upon MHC recognition may bias lineage commitment

Vertical distribution of buoyant Microcystis blooms in a Lagrangian particle tracking model for short‐term forecasts in Lake Erie

Cyanobacterial harmful algal blooms (CHABs) are a problem in western Lake Erie, and in eutrophic fresh waters worldwide. Western Lake Erie is a large (3000 km2), shallow (8 m mean depth), freshwater system. CHABs occur from July to October, when stratification is intermittent in response to wind and surface heating or cooling (polymictic). Existing forecast models give the present location and extent of CHABs from satellite imagery, then predict two‐dimensional (surface) CHAB movement in response to meteorology. In this study, we simulated vertical distribution of buoyant Microcystis colonies, and 3‐D advection, using a Lagrangian particle model forced by currents and turbulent diffusivity from the Finite Volume Community Ocean Model (FVCOM). We estimated the frequency distribution of Microcystis colony buoyant velocity from measured size distributions and buoyant velocities. We evaluated several random‐walk numerical schemes to efficiently minimize particle accumulation artifacts. We selected the Milstein scheme, with linear interpolation of the diffusivity profile in place of cubic splines, and varied the time step at each particle and step based on the curvature of the local diffusivity profile to ensure that the Visser time step criterion was satisfied. Inclusion of vertical mixing with buoyancy significantly improved model skill statistics compared to an advection‐only model, and showed greater skill than a persistence forecast through simulation day 6, in a series of 26 hindcast simulations from 2011. The simulations and in situ observations show the importance of subtle thermal structure, typical of a polymictic lake, along with buoyancy in determining vertical and horizontal distribution of Microcystis.Key Points:Microcystis vertical distribution is a dynamic balance between turbulence and buoyancyAppropriate time step and numerical scheme avoid artifacts in random walk modelsVertical mixing with buoyancy improved simulation of bloom spatial distributionPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134116/1/jgrc21832_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134116/2/jgrc21832.pd

Experiences of being exposed to intimate partner violence during pregnancy

In this study a phenomenological approach was used in order to enter deeply into the experience of living with violence during pregnancy. The aim of the study was to gain a deeper understanding of women's experiences of being exposed to intimate partner violence (IPV) during pregnancy. The data were collected through in-depth interviews with five Norwegian women; two during pregnancy and three after the birth. The women were between the age of 20 and 38 years. All women had received support from a professional research and treatment centre. The essential structure shows that IPV during pregnancy is characterized by difficult existential choices related to ambivalence. Existential choices mean questioning one's existence, the meaning of life as well as one's responsibility for oneself and others. Five constituents further explain the essential structure: Living in unpredictability, the violence is living in the body, losing oneself, feeling lonely and being pregnant leads to change. Future life with the child is experienced as a possibility for existential change. It is important for health professionals to recognize and support pregnant women who are exposed to violence as well as treating their bodies with care and respect

A Systematic Review of African Studies on Intimate Partner Violence against Pregnant Women: Prevalence and Risk Factors

Background: Intimate partner violence (IPV) is very high in Africa. However, information obtained from the increasing number of African studies on IPV among pregnant women has not been scientifically analyzed. This paper presents a systematic review summing up the evidence from African studies on IPV prevalence and risk factors among pregnant women. Methods: A key-word defined search of various electronic databases, specific journals and reference lists on IPV prevalence and risk factors during pregnancy resulted in 19 peer-reviewed journal articles which matched our inclusion criteria. Quantitative articles about pregnant women from Africa published in English between 2000 and 2010 were reviewed. At least two reviewers assessed each paper for quality and content. We conducted meta-analysis of prevalence data and reported odds ratios of risk factors. Results: The prevalence of IPV during pregnancy ranges from 2% to 57% (n = 13 studies) with meta-analysis yielding an overall prevalence of 15.23% (95% CI: 14.38 to 16.08%). After adjustment for known confounders, five studies retained significant associations between HIV and IPV during pregnancy (OR1.48-3.10). Five studies demonstrated strong evidence that a history of violence is significantly associated with IPV in pregnancy and alcohol abuse by a partner also increases a woman's chances of being abused during pregnancy (OR 2.89-11.60). Other risk factors include risky sexual behaviours, low socioeconomic status and young age. Conclusion: The prevalence of IPV among pregnant women in Africa is one of the highest reported globally. The major risk factors included HIV infection, history of violence and alcohol and drug use. This evidence points to the importance of further research to both better understand IPV during pregnancy and feed into interventions in reproductive health services to prevent and minimize the impact of such violence

First Finding of the Amphipod \u3ci\u3eEchinogammarus ischnus\u3c/i\u3e and the Mussel \u3ci\u3eDreissena bugensis\u3c/i\u3e in Lake Michigan

The first finding of the amphipod Echinogammarus ischnus and the mussel Dreissena bugensis in Lake Michigan is documented. These two species are widespread and abundant in the lower lakes, but had not yet been reported from Lake Michigan. E. ischnus is generally considered a warmwater form that is typically associated with hard substrates and Dreissena clusters in the nearshore zone. Along the eastern shoreline of Lake Michigan, this species was present at rocky, breakwall habitats along the entire north-south axis of the lake. Although not abundant, this species was also found at soft-bottomed sites as deep as 94 m in the southern basin. The finding of this species in deep offshore waters apparently extends the known habitat range for this species in the Great Lakes, but it is found in deep water areas within its native range (Caspian Sea). D. bugensis was not abundant, but was present in both the southern and northern portions of the lake. Individuals of up to 36 mm in length were collected, indicating that it had probably been present in the lake for 2 or more years. Also presented are depth-defined densities of D. polymorpha at 37 sites in the Straits of Mackinac in 1997, and densities at up to 55 sites in the southern basin in 1992/93 and 1998/99. Mean densities decreased with increased water depth in both regions. Maximum mean density in the Straits in 1997 was 13,700/m2 (≤ 10 m), and maximum density in the southern basin in 1999 was 2,100/m2 (≤ 30 m). Mean densities at the ≤ 30-m interval in the southern basin remained relatively unchanged between 1993 and 1999, but increased from 25/m2 to 1,100/m2 at the 31 to 50 m interval over the same time period. D. polymorpha was rare at sites \u3e 50 m. The presence of E. ischnus and the expected population expansion of D. bugensis will likely contribute to further foodweb changes in the lake

Changes in the Freshwater Mussel Community of Lake St. Clair: from Unionidae to \u3ci\u3eDreissena polymorpha\u3c/i\u3e in Eight Years

To determine density changes in both the zebra mussel, Dreissena polymorpha, and native mussels, Unionidae, in Lake St. Clair, surveys were conducted in 1990, 1992, and 1994 and compared to a similar survey in 1986 when no D. polymorpha was found. Collection methods were the same each year; divers used the quadrat method to collect 10 replicate samples at 29 sites located throughout the lake. The total number of unionids collected declined from 281 in 1986, to 248 in 1990, 99 in 1992, and 6 in 1994, while the number of species collected in each of the four respective years was 18, 17, 12, and 5. The decline in the unionid community occurred gradually over this time period as the D. polymorpha population expanded from the southeast region of the lake to the northwest region. Mean density and biomass of D. polymorpha throughout the lake was 1,700 m-2 and 4.7 gDW m-2 in 1990, 1,500 m-2 and 3.5 gDW m-2 in 1992, and 3,200 m-2 and 3.1 gDW m-2 in 1994. The density increase can be attributed to the expansion of the population into the northwest region, while the decrease in biomass was mostly a result of a decline in the weight per unit length. Mean biomass of the D. polymorpha population in 1994 was actually lower than the mean biomass of unionids in 1986; however, based on literature-derived filtering rates, the filtering capacity of the D. polymorpha population in 1994 was 12 times greater than the filtering capacity of the unionid community in 1986. This increase has likely led to reported changes in the Lake St. Clair ecosystem (increased water clarity, increased plant growth, and shifts in fish communities)