Apoptosis via the B cell antigen receptor requires Bax translocation and involves mitochondrial depolarization, cytochrome C release, and caspase-9 activation

Various routes to apoptosis can be active during B cell development. In a model system of mature B cells, differences in caspase-3 processing have suggested that antigen receptor (BCR)-mediated apoptosis may involve a zVAD-insensitive initiator protease(s). In search of the events leading to caspase-3 activation, we now establish that both CD95- and BCR-mediated apoptosis depend on Bax activation and cytochrome C (cytC) release. Nevertheless, the timing and caspase-dependence of mitochondrial membrane depolarization differed considerably after CD95- or BCR-triggering. To delineate events subsequent to cytC release, we compared apoptosis induced via BCR triggering and via direct mitochondrial depolarization by CCCP. In both cases, partial processing of caspase-3 was observed in the presence of zVAD. By expression in 293 cells we addressed the potential of candidate initiator caspases to function in the presence of zVAD, and found that caspase-9 efficiently processed caspase-3, while caspase-2 or -8 were inactive. Finally, retroviral expression of dominant-negative caspase-9 inhibited both CD95- and BCR-mediated apoptosis. In conclusion, we obtained no evidence for involvement of a BCR-specific protease. Instead, our data show for the first time that the BCR-signal causes Bax translocation, followed by mitochondrial depolarization, and cytC release. Subsequent caspase-9 activation can solely account for events further downstream.     

Assessment of sleep and sleepiness in Parkinson disease

STUDY OBJECTIVES: To develop a short and practical scale (SCOPA-SLEEP) that evaluates nighttime sleep and daytime sleepiness. The scale is developed for research in Parkinson disease but may be of value for other somatic diseases. DESIGN: Postal survey including 4 instruments, the SCOPA-SLEEP nighttime sleep (5 items) and daytime sleepiness (6 items), the Pittsburgh Sleep Quality Index, and the Epworth Sleepiness Scale. SETTING: Movement Disorders Center, Department of Neurology, Leiden University Medical Center, Leiden, The Netherlands. PARTICIPANTS: 143 patients with Parkinson disease and 104 controls. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Reliability of the scale was high: internal consistency of the nighttime sleep and daytime sleepiness scales were 0.88 and 0.91, respectively (Cronbach alpha), and test-retest reliabilities were 0.94 and 0.89, respectively (intraclass correlation coefficient). Scale scores differed significantly between patients and controls (P < .001). Construct validity was assessed by correlations with scales that addressed similar constructs. Correlation between the nighttime sleep scale and the Pittsburgh Sleep Quality Index was 0.83 (P < .001), and the correlation between the daytime sleepiness scale and the Epworth Sleepiness Scale was 0.81 (P < .001). Factor analysis revealed 1 factor each for both scales, indicating that the scales measure 1 construct, which justifies the calculation of sumscores. The coefficient of variation of both the nighttime sleep and the daytime sleepiness scale was higher than that of the Pittsburgh Sleep Quality Index and the Epworth Sleepiness Scale, indicating a better ability to detect differences between individuals. CONCLUSIONS: The SCOPA-SLEEP is a reliable and valid instrument for assessing nighttime sleep and daytime sleepiness in patients with Parkinson disease.     

Cox proportional hazards models have more statistical power than logistic regression models in cross-sectional genetic association studies

Cross-sectional genetic association studies can be analyzed using Cox proportional hazards models with age as time scale, if age at onset of disease is known for the cases and age at data collection is known for the controls. We assessed to what degree and under what conditions Cox proportional hazards models have more statistical power than logistic regression models in cross-sectional genetic association analyses. Analyses were conducted in an empirical study on the association of 65 polymorphisms and risk of coronary heart disease among 2400 familial hypercholesterolemia patients, and in a simulation study that considered various combinations of sample size, genotype frequency, and strength of association between the genotype and coronary heart disease. We applied Cox proportional hazards models and logistic regression models, and compared effect estimates (hazard ratios and odds ratios) and statistical power. In the empirical study, Cox proportional hazards models generally showed lower P-values for polymorphisms than logistic regression models. In the simulation study, Cox proportional hazards models had higher statistical power in all scenarios. Absolute differences in power did depend on the effect estimate, genotype frequency and sample size, and were most prominent for genotypes with minor effects. For example, when the genotype frequency was 30% in a sample with size n=2000 individuals, the absolute differences were the largest for effect estimates between 1.1 and 1.5. In conclusion, Cox proportional hazards models can increase statistical power in cross-sectional genetic association studies, especially in the range of effect estimates that are expected for genetic associations in common diseases.European Journal of Human Genetics (2008) 16, 1111-1116; doi:10.1038/ejhg.2008.59; published online 2 April 2008.     

Impaired neuronal migration and endochondral ossification in Pex7 knockout mice: a model for rhizomelic chondrodysplasia punctata

Rhizomelic chondrodysplasia punctata is a human autosomal recessive disorder characterized by skeletal, eye and brain abnormalities. The disorder is caused by mutations in the PEX7 gene, which encodes the receptor for a class of peroxisomal matrix enzymes. We describe the generation and characterization of a Pex7 mouse knockout (Pex7(-/-)). Pex7(-/-) mice are born severely hypotonic and have a growth impairment. Mortality in Pex7(-/-) mice is highest in the perinatal period although some Pex7(-/-) mice survived beyond 18 months. Biochemically Pex7(-/-) mice display the abnormalities related to a Pex7 deficiency, i.e. a severe depletion of plasmalogens, impaired alpha-oxidation of phytanic acid and impaired beta-oxidation of very-long-chain fatty acids. In the intermediate zone of the developing cerebral cortex Pex7(-/-) mice have an increase in neuronal density. In vivo neuronal birthdating revealed that Pex7(-/-) mice have a delay in neuronal migration. Analysis of bone ossification in newborn Pex7(-/-) mice revealed a defect in ossification of distal bone elements of the limbs as well as parts of the skull and vertebrae. These findings demonstrate that Pex7 knockout mice provide an important model to study the role of peroxisomal functioning in the pathogenesis of the human disorder.     

DRD4 7-repeat polymorphism moderates the association between maternal unresolved loss or trauma and infant disorganization

Previous studies have related attachment disorganization in children to either dopamine D4 receptor polymorphisms or maternal unresolved loss or trauma and frightening or anomalous parenting. In this study it was examined whether the interaction between genetic (DRD4 7-repeat and -521 C/T) and environmental risk factors (maternal unresolved loss/trauma and maternal frightening behavior) was associated with infant disorganization. A moderating role of the DRD4 gene was found. Maternal unresolved loss or trauma was associated with infant disorganization, but only in the presence of the DRD4 7-repeat polymorphism. The increase in risk for disorganization in children with the 7-repeat allele exposed to maternal unresolved loss/trauma compared to children without these combined risks was 18.8 fold. Similar moderating effects were not found for maternal frightening behavior. Our findings indicate that children are differentially susceptible to unresolved loss or trauma dependent on the presence of the 7-repeat DRD4 allele.     

Individualized cost-effective conventional ovulation induction treatment in normogonadotrophic anovulatory infertility (WHO group 2)

BACKGROUND: Conventional treatment in normogonadotrophic anovulatory infertility (WHO 2) consists of clomiphene citrate (CC), followed by exogenous gonadotrophins (FSH) and IVF. Response to these treatments may be predicted on the basis of individual patient characteristics. We aimed to devise a patient-tailored, cost-effective treatment algorithm involving the above-mentioned treatment modalities, based on individual patient characteristics. METHODS: Sixteen prognostic groups are defined, according to the presence or absence of: age >30 years, amenorrhea, elevated androgen levels and obesity. The chances of response with each of the three treatments were calculated using prediction models. Treatment costs were based on the data of 240 patients visiting a specialist academic fertility unit. Outcome was an ongoing pregnancy within 12 months after initiation of treatment. The costs per pregnancy of three different strategies were compared, with a threshold for cost-effectiveness of 10 000. RESULTS: The strategy CC + FSH + IVF compared with FSH + IVF generated more pregnancies against lower costs. Compared with CC + IVF, it also produced more pregnancies, but at higher costs. For <30 years of age with normal androgen levels, costs per pregnancy were less than 10 000. For women >30 years old, costs per pregnancy were 25 000 and over 200 000, when presenting with normal or elevated androgen levels, respectively. CONCLUSIONS: The conventional treatment protocol is efficient for women aged <30 years with normal androgen levels. For women >30 years old with elevated androgen levels, FSH may be skipped.     

Phenotype and function of human B cells expressing CD70 (CD27 ligand)

CD70, the cellular ligand of the tumor necrosis factor receptor family member CD27, can be found on a limited number of germinal center (GC) B cells in some tonsils, on scattered lymphocytes residing in secondary lymphoid organs, and on a fraction of the circulating B cell population. Due to the restricted expression of CD70 in vivo, we analyzed signals that determine CD70 expression levels and characterized the phenotype and function of CD70⁺ B cells. Expression of CD70 on B cells activated in vitro was found to be dependent on the continuous presence of a B cell antigen receptor cross-linking agent, and induced or potentiated by CD40 ligation but was down-modulated by the Th2 cytokines interleukin (IL)-4 and IL-13. Both in peripheral blood and tonsil cell suspensions, CD70⁺ B cell subpopulations were found to be enriched for CD27-and IgG-expressing cells, but contained less IgD⁺ B cells. Additional analysis of markers which define specific differentiation stages (Bm1-5) of mature B cells within human tonsils did not place CD70-expressing B cells in one of these subsets. Functional experiments revealed that whereas both CD70⁻ and CD70⁺ B cells can secrete immunoglobulin after activation with a combination of Staphylococcus aureus Cowan strain I and IL-2, only CD70⁺ B cells can produce large quantities of antibodies when stimulated in a T cell-dependent fashion. Our combined data imply that CD70 is a marker for mature B cells which have recently been primed by antigen in vivo.     

DRD4 7-repeat polymorphism moderates the association between maternal unresolved loss or trauma and infant disorganization

Abstract

Previous studies have related attachment disorganization in children to either dopamine D4 receptor polymorphisms or maternal unresolved loss or trauma and frightening or anomalous parenting. In this study it was examined whether the interaction between genetic (DRD4 7-repeat and -521 C/T) and environmental risk factors (maternal unresolved loss/trauma and maternal frightening behavior) was associated with infant disorganization. A moderating role of the DRD4 gene was found. Maternal unresolved loss or trauma was associated with infant disorganization, but only in the presence of the DRD4 7-repeat polymorphism. The increase in risk for disorganization in children with the 7-repeat allele exposed to maternal unresolved loss/trauma compared to children without these combined risks was 18.8 fold. Similar moderating effects were not found for maternal frightening behavior. Our findings indicate that children are differentially susceptible to unresolved loss or trauma dependent on the presence of the 7-repeat DRD4 allele.     

The role of disconnected and extremely insensitive parenting in the development of disorganized attachment: validation of a new measure

Early adverse caregiving experiences constitute an important risk factor for the development of disorganized attachment in infancy, especially extreme insensitivity and frightening behavior associated with an unresolved loss or trauma. Using existing measures for frightening parenting and disrupted communication, we developed a new measure assessing Disconnected and extremely Insensitive Parenting (DIP), in order to investigate the unique contribution of disconnected and extremely insensitive parenting behaviors to infant disorganization. Maternal behavior was assessed during a laboratory session in a low-risk sample of 202 mothers and their infants. Construct and discriminant validity of the DIP was established for both types of parental behavior. Disconnected parental behavior predicted infant disorganization but not organized attachment security, whereas extreme insensitivity was marginally related to organized attachment insecurity in boys but not to attachment disorganization.     

Loss of EBNA1-specific memory CD4+ and CD8+ T cells in HIV-infected patients progressing to AIDS-related non-Hodgkin lymphoma

We previously observed a loss of Epstein-Barr virus (EBV)-specific CD8+ T cells in subjects progressing to EBV-related non-Hodgkin lymphoma (NHL), correlating with loss of CD4+ T cells. The aim of the present study was to determine the role of EBV-specific CD4+ T cells in the development of NHL during chronic HIV infection. To this end, CD4+ and CD8+ memory T cells, capable of both proliferation and subsequent interferon gamma (IFNgamma) production, directed against a latent (Epstein-Barr virus nuclear antigen 1 [EBNA1]) and a lytic (BamH fragment Z left frame 1 [BZLF1]) EBV antigen were studied longitudinally in 9 progressors to NHL, 4 progressors to non-EBV-related AIDS, and 4 slow progressors to AIDS. In all 3 groups we observed a decline of EBV-specific memory CD4+ and CD8+ T-cell responses during HIV infection. However, whereas latent antigen EBNA1-specific CD4+ T cells were lost well before diagnosis in all subjects who developed an AIDS-related NHL (and EBNA1-specific CD8+ T cells were significantly lower compared with the other groups), these cells were better preserved in progressors to non-EBV-related disease and slow progressors. Loss of EBNA1-specific T-cell immunity thus might be important for progression to NHL. Interestingly, BZLF1-specific T cells were not lost in all progressors to NHL, suggesting a different function of these cells in the surveillance of EBV-infected B cells.