Critical function for the Ras-GTPase activating protein RASA3 in vertebrate erythropoiesis and megakaryopoiesis

Phenotype-driven approaches to gene discovery using inbred mice have been instrumental in identifying genetic determinants of inherited blood dyscrasias. The recessive mutant scat (severe combined anemia and thrombocytopenia) alternates between crisis and remission episodes, indicating an aberrant regulatory feedback mechanism common to erythrocyte and platelet formation. Here, we identify a missense mutation (G125V) in the scat Rasa3 gene, encoding a Ras GTPase activating protein (RasGAP), and elucidate the mechanism producing crisis episodes. The mutation causes mislocalization of RASA3 to the cytosol in scat red cells where it is inactive, leading to increased GTP-bound Ras. Erythropoiesis is severely blocked in scat crisis mice, and ~94% succumb during the second crisis (~30 d of age) from catastrophic hematopoietic failure in the spleen and bone marrow. Megakaryopoiesis is also defective during crisis. Notably, the scat phenotype is recapitulated in zebrafish when rasa3 is silenced. These results highlight a critical, conserved, and nonredundant role for RASA3 in vertebrate hematopoiesis.     

Antibody-dependent anti-cytomegalovirus activity of human γδ T cells expressing CD16 (FcγRIIIa)

Human cytomegalovirus (HCMV) infection is an important cause of morbidity and mortality in transplant recipients. Long-term protective immunity against HCMV requires both sustained specific T-cell response and neutralizing IgG production, but the interplay between these effector arms remains poorly defined. We previously demonstrated that γδ T cells play a substantial role as anti-HCMV T-cell effectors. The observation that CD16 (FcγRIIIA) was specifically expressed by the majority of HCMV-induced γδ T cells prompted us to investigate their cooperation with anti-HCMV IgG. We found that CD16 could stimulate γδ T cells independently of T-cell receptor (TCR) engagement and provide them with an intrinsic antibody-dependent cell-mediated cytotoxic (ADCC) potential. Although CD16(+)γδ T cells did not mediate ADCC against HCMV-infected cells, in accordance with the low level of anti-HCMV IgGs recognizing infected cells, they produced IFNγ when incubated with IgG-opsonized virions. This CD16-induced IFNγ production was greatly enhanced by IL12 and IFNα, 2 cytokines produced during HCMV infection, and conferred to γδ T cells the ability to inhibit HCMV multiplication in vitro. Taken together, these data identify a new antiviral function for γδ T cells through cooperation with anti-HCMV IgG that could contribute to surveillance of HCMV reactivation in transplant recipients.     

Maternal vitamin K deficient embryopathy: Association with hyperemesis gravidarum and Crohn disease

Chondrodysplasia punctata (CDP) is an etiologically heterogeneous disorder characterized by the radiographic finding of stippled epiphyses (punctate calcifications). It is often accompanied by a characteristic facial appearance, known as the Binder phenotype, which is attributed to hypoplasia of the nasal cartilages; abnormal distal phalanges (brachytelephalangy) are a common component manifestation as well. We report eight patients with a Binder phenotype with or without CDP who all shared a known or suspected maternal deficiency of vitamin K. We suspect that this phenotype is probably under recognized, and we hope to increase awareness about the maternal risk factors, especially hyperemesis gravidarum, which lead to nutritional deficiency. © 2013 Wiley Periodicals, Inc.     

Proximity to HIV is associated with a high rate of HIV testing among men who have sex with men living in Douala, Cameroon

In low- and middle-income countries, men who have sex with men (MSM) are 19 times more likely to be HIV positive compared with background populations. Criminalisation and social rejection of homosexuality in most sub-Saharan African countries reinforce stigma and exclude MSM from prevention activities, including HIV testing. This paper's purpose is to identify factors associated with never having been HIV tested (NHT), among a sample of Cameroonian MSM. In 2008, a community-based study was conducted in Douala, the economic capital city of Cameroon, by a local NGO Alternatives-Cameroun, recruiting participants through the snowball technique and administering a questionnaire during face-to-face interviews. Proximity to HIV was investigated according to the following criteria: knowing at least one person living with HIV and having been exposed to HIV prevention interventions. NHT was defined as reporting to have never been HIV tested. A logistic regression was used to identify factors associated with NHT. Among the 165 MSM of our study group who reported that they were not HIV positive, 19% reported NHT. Factors independently associated with NHT were as follows: being younger, being Muslim, not having a steady male partner, not knowing any person living with HIV and never having been exposed to HIV prevention interventions. In this MSM population, a small proportion reported that they had never been HIV tested and among these, the percentage was higher among individuals not in proximity to HIV. Despite the hostile context of sub-Saharan African countries towards MSM, local and national HIV testing campaigns to date may have played a substantial role in raising HIV awareness in the MSM population living in Douala, and peer-based counselling may have educated those in contact with Alternatives-Cameroun regarding the positive value of HIV testing. This result is a further argument for continuing community-based prevention and extending it to difficult-to-reach MSM.     

Intratumoral inflammation is associated with more aggressive prostate cancer

Purpose

Inflammation may play a role in the development and progression of many cancers, including prostate cancer. We sought to test whether histological inflammation within prostate cancer was associated with more aggressive disease.

Methods

The slides of prostatectomy specimens were reviewed by a board-certified pathologist on 287 men from a Veterans Affairs Medical Center treated with radical prostatectomy from 1992 to 2004. The area with the greatest tumor burden was scored in a blinded manner for the degree of inflammation: absent, mild, or marked. We used logistic and Cox proportional hazards regression analysis to examine whether categorically coded inflammation score was associated with adverse pathology and biochemical progression, respectively.

Results

No inflammation was found in 49 men (17 %), while 153 (53 %) and 85 (30 %) had mild and marked inflammation. During a median follow-up of 77 months, biochemical recurrence occurred among 126 (44 %) men. On multivariate analysis, more inflammation was associated with greater risk of positive margins, capsular penetration, and seminal vesicle invasion (all p < 0.05). Marked inflammation was associated with increased PSA recurrence risk when adjusting for preoperative features only (HR 2.08, 95 % CI 1.02–4.24), but not after adjusting for pathologic features.

Conclusions

Inflammation within prostate cancer was associated with more advanced disease, although it is unclear whether aggressive disease caused increased inflammation or inflammation caused aggressive disease.