Identification of Gender-Specific Candidate Genes that Influence Bone Microarchitecture in Chromosome 1

Studies on the identification of the genetic basis for sexual dimorphism in peak bone mass are obviously important for providing novel therapeutic approaches to prevent or treat metabolic bone diseases. Our goal in this study was to identify the bone microstructure that could lead to differences in volumetric bone mineral density (vBMD) and new candidate genes that regulate the gender effect on bone. We used a congenic line of mice that carry the BMD1–4 locus from CAST/EiJ (CAST) mice in a C57BL/6J (B6) background and show greater vBMD in female, but not male, congenics compared to age- and gender-matched B6 mice. To assess the vBMD variations between the two lines of mice, we performed μCT measurements and found no difference in cortical bone volume by tissue volume (BV/TV) between congenics and B6 mice. However, trabecular BV/TV was significantly greater in female, but not male, congenics compared to corresponding B6 mice, which was due to increased trabecular thickness but not reduced trabecular separation, suggesting that bone formation, but not bone resorption, is responsible for the trabecular bone phenotype observed in the female, but not male, congenics. To identify the gender candidate genes, we determined the polymorphisms between B6 and CAST within the BMD1–4 locus and performed gene expression profiling. We identified EF-hand calcium binding domain (Efcab2), consortin, connexin sorting protein (Cnst), and presenilin 2 (Psen2) as potential candidate genes that regulate bone mass by influencing trabecular thickness in a gender-specific manner.     

Genetic regulation of femoral bone mineral density: complexity of sex effect in chromosome 1 revealed by congenic sublines of mice

The findings that sex-specific effects on femoral structure and peak bone mineral density (BMD) are linked to quantitative trait loci (QTL) provide evidence for the involvement of specific genes that contribute to gender variation in skeletal phenotype. Based on previous findings that the BMD QTL in chromosome 1 (Chr 1) exerts a sex-specific effect on femoral structure, we predicted that congenic sublines of mice that carry one or more of the Chr 1 BMD loci would exhibit gender difference in the volumetric BMD (vBMD) phenotype. To test this hypothesis, we compared skeletal parameters of male and female of five C57BL/6J (B6).CAST/EiJ (CAST)-1 congenic sublines of mice that carry overlapping CAST chromosomal segments from the vBMD loci in Chr 1. Femur vBMD measurements were performed by the peripheral quantitative computed tomography in male and female mice at 16 weeks of age. The skeletal phenotype of the C175-185 and C178-185 congenic sublines of mice provided evidence for the presence of the BMD1-4 locus at 178-180 Mb from the centromere. This QTL affects femur vBMD only in female mice. In contrast, CAST chromosomal region carrying BMD1-1 locus increased femur vBMD both in male and female mice. Furthermore, a gender specific effect on BMD of femur mid-shaft region (mid-BMD) was identified at 168-176 Mb in Chr 1 (F=16.49, P=0.0002), while no significant effect was found on total femur BMD (F=2.67, P=0.11). Moreover, this study allowed us to locate a body weight QTL at 168-172 Mb of Chr 1, the effect of this locus was altered in female mice that carry CAST chromosomal segment 168-176 Mb of Chr 1. Based on this study, we conclude that Chr 1 carries at least two vBMD gender-dependent loci; one genetic locus at 178-180 Mb (BMD1-4 locus) which affects both mid-shaft and total femur vBMD in female mice only, and another gender-dependent locus at 168-176 Mb (BMD1-2 locus) which affects femur mid-shaft vBMD in female but not male mice.     

Atteintes cardiovasculaires associées à la polykystose rénale autosomique dominante

Autosomal dominant polycystic kidney disease is the most frequent genetic kidney disease. Cardiovascular disorders associated with autosomal dominant polycystic kidney disease are multiple and may occur early in life. In autosomal dominant polycystic kidney disease cardiovascular morbidity and mortality are related both to the nonspecific consequences of chronic kidney disease and to the particular phenotype of autosomal dominant polycystic kidney disease. Compared to the general population, patients with autosomal dominant polycystic kidney disease present an increased prevalence of hypertension, left ventricular hypertrophy, atrial fibrillation, valvular diseases, aneurisms and arterial dissections. This review article provides an update on cardiovascular disorders associated with autosomal dominant polycystic kidney disease and recent pathophysiological developments.     

Preventability of death in a medical intensive care unit at a university hospital in a developing country

Objective:

To determine the incidence and characteristics of preventable in-ICU deaths.

Materials and Methods:

A one-year observational study was conducted in a medical ICU of a teaching hospital. All patients who died in medical ICU beyond 24 h were analyzed and reviewed during daily medical meeting. A death was considered preventable when it would not have occurred if the patient had received ordinary standards of care appropriate for the time of study. Preventability of death was classified by using a 1-6 point preventability scale. The types of medical errors causing preventable in-ICU deaths and the contributory factors to deaths were identified.

Results:

120 deaths (47 ± 19 years, 57 months-63 weeks) were analyzed (mortality: 23%; 95% confidence interval (CI):15-31%). At admission, Acute Physiology and Chronic Health Evaluation (APACHE) II score was 18 ± 7.6 and Charlson comorbidity index was 1.3 ± 1.6. The main diagnosis was infectious disease (57%) and respiratory disease (23%). The median period between the ICU admission and death was 5 days. The rate of preventable in-ICU deaths was 14.1% (17/120). The most common medical errors related to occurrence of preventable in-ICU deaths were therapeutic error (52.9%) and inappropriate technical procedure (23.5%). The preventable in-ICU deaths were associated with inadequate training or supervision of clinical staff (58.8%), no protocol (47.1%), inadequate functioning of hospital departments (29.4%), unavailable equipment (23.5%), and inadequate communication (17.6%).

Conclusion:

According to our study, one to two in-ICU deaths would be preventable per month. Our results suggest that the implementation of supervision and protocols could improve outcomes for critically ill patients.     

Identification of mouse Duffy antigen receptor for chemokines (Darc) as a BMD QTL gene

It is now well known that bone mineral density (BMD) variance is determined by both genetic and environmental factors. Accordingly, studies in human and animal models have revealed evidence for the presence of several quantitative trait loci (QTL) that contribute to BMD variations. However, the identification of BMD QTL genes remains a big challenge. In the current study, we focused our efforts to identify the BMD candidate gene in chromosome 1 (Chr 1) QTL that was detected from a cross involving high BMD CAST/EiJ (CAST) and low BMD C57BL/6J (B6) mice. To this end, we have combined several approaches including: (1) fine mapping the BMD QTL in Chr 1 of the B6.CAST F2 female mice using a large number of polymorphic markers; (2) the generation of congenic sublines of mice by repeated backcrossing of CAST with B6 mice and phenotype characterization; (3) expression profiling genes in the QTL region; and (4) SNP analyses to identify the mouse Duffy Antigen Receptor for Chemokines (Darc) as a candidate gene for Chr 1 BMD QTL2. We verified the involvement of the Darc protein in BMD variation by evaluating the skeletal phenotype of Darc-knockout mice and congenic sublines of mice carrying small chromosomal segments from CAST BMD QTL. Based on the findings that Darc-antibody blocked formation of multinucleated osteoclasts in vitro and that Darc from CAST binds chemokines, known to regulate osteoclast formation, with reduced affinity compared with Darc from B6 mice, we conclude that Darc regulates BMD negatively by increasing osteoclast formation, and that the genetic association between Darc gene polymorphism and BMD variations in humans merits investigation.     

Influence of steatosis on progression of fibrosis and virological response in chronic hepatitis C cases

Background and study aimsHepatic steatosis seems to be frequently found histopathologically in chronic hepatitis C virus (HCV)-infected patients. The aim of this study is to determine the influence of steatosis on HCV disease severity (fibrosis) and to evaluate its impact on sustained virological response (SVR) to antiviral therapy.Patients and methodsFrom April 2008 to April 2010, 148 consecutive adults (87 females (59%) and 61 males (41%); mean age: 55.2 years) with HCV admitted for liver biopsy were included in this retrospective study. At least one element of metabolic syndrome was identified in all cases: Obesity (n = 44), hyperlipidaemia (n = 40), hypertension (n = 29) and diabetes (n = 21). Liver fibrosis was classified according to the Metavir score and hepatic steatosis described as following: S0: absent; S1: minimal (<30%); S2: moderate (30–60%); and S3: severe (>60%). Patients were divided into two groups: S0S1 group (absent or minimal steatosis) and S2S3 group (moderate to severe steatosis). Of the 148 patients, 53 were treated with pegylated interferon and ribavirin combination therapy.ResultsSteatosis was found in 40 patients (27%): S1 in 72.5%, S2 in 17.5% and S3 in 10% of cases. The distribution of patients according to the degree of fibrosis was as follows: in the S0S1 group, F1 = 12.4%, F2 = 36.5%, F3 = 21.1% and F4 = 21.1% and in the S2S3 group, F1 = 9%, F2 = 45.5%, F3 = 18.2% and F4 = 27.3%. There was no difference between the two groups regarding the degree of fibrosis (p ? 0.80). The rate of SVR was 64%: 63% in the S0S1 group and 75% in the S2S3 group. The difference was not statistically significant (p = 1).ConclusionSteatosis was found in 25% of cases. Liver steatosis in chronic hepatitis C is not a negative prognostic factor of response to combined antiviral therapy. These results must be confirmed by a large series of patients.     

Jagged1 regulates the activation of astrocytes via modulation of NFκB and JAK/STAT/SOCS pathways

The Notch pathway is implicated in many aspects of the central nervous system (CNS) development and functions. Recently, we and others identified the Notch pathway to be involved in inflammatory events of the CNS. To understand the implication of this pathway on astrocytes, we have studied the Jagged‐Notch‐Hes pathway under inflammatory conditions. LPS exposure induced an upregulation of Jagged1 expression on cultured astrocytes. To address the role of Jagged1 in the modulation of inflammation, we used a siRNA mediated silencing of Jagged1 (siRNA J1). Jagged1 inhibition induced important variations on the Notch pathway components like Hes1, Hes5, Notch3, and RBP‐Jκ. siRNA J1 repressed the mRNA expression of genes known as hallmarks of the gliosis like GFAP and endothelin(B) receptor. On activated astrocytes, the inhibition of Jagged1 had antiinflammatory effects and resulted in a decrease of LPS‐induced proinflammatory cytokines (IL1β, IL1α, and TNFα) as well as the iNOS expression. The inhibition of Jagged1 induced a modulation of the JAK/STAT/SOCS signaling pathway. Most interestingly, the siRNA J1 decreased the LPS‐induced translocation of NFκB p65 and this could be correlated to the phosphorylation of IκBα. These results suggest that during inflammatory and gliotic events of the CNS, Jagged1/Notch signaling sustains the inflammation mainly through NFκB and in part through JAK/STAT/SOCS signaling pathways. © 2009 Wiley‐Liss, Inc.     

Anti-Tumoral Effects of Anti-Progestins in a Patient-Derived Breast Cancer Xenograft Model

Breast cancer is a hormone-dependent disease in which estrogen signaling targeting drugs fail in about 10 % due to resistance. Strong evidences highlighted the mitogen role of progesterone, its ligands, and the corresponding progesterone receptor (PR) isoforms in mammary carcinoma. Several PR antagonists have been synthesized; however, some of them are non-selective and led to side or toxic effects. Herein, we evaluated the anti-tumor activity of a commercially available PR modulator, ulipristal acetate (UPA), and a new selective and passive PR antagonist “APR19” in a novel preclinical approach based on patient-derived breast tumor (HBCx-34) xenografted in nude mice. As opposed to P4 that slightly reduces tumor volume, UPA and APR19 treatment for 42 days led to a significant 30 % reduction in tumor weight, accompanied by a significant 40 % retardation in tumor growth upon UPA exposure while a 1.5-fold increase in necrotic areas was observed in APR19-treated tumors. Interestingly, PR expression was upregulated by a 2.5-fold factor in UPA-treated tumors while APR19 significantly reduced expression of both PR and estrogen receptor α, indicating a potential distinct molecular mechanism among PR antagonists. Cell proliferation was clearly reduced in UPA group compared to vehicle conditions, as revealed by the significant reduction in Ki-67, Cyclin D1, and proliferating cell nuclear antigen (PCNA) expression. Likewise, an increase in activated, cleaved poly(ADP-ribose) polymerase (PARP) expression was also demonstrated upon UPA exposure. Collectively, our findings provide direct in vivo evidence for anti-progestin-mediated control of human breast cancer growth, given their anti-proliferative and pro-apoptotic activities, supporting a potential role in breast cancer therapy.