Functional and genomic approaches reveal an ancient CHEK2 allele associated with breast cancer in the Ashkenazi Jewish population

Functional and genomic approaches can be integrated to screen efficiently for pathogenic alleles in founder populations. We applied such approaches to analysis of the cancer-associated cell cycle regulator CHEK2 in the Ashkenazi Jewish population. We first identified two extended haplotypes at CHEK2 that co-segregated with breast cancer in high-risk families. We sequenced CHEK2 in a case representing each haplotype and discovered two novel amino acid substitutions, CHEK2.S428F in the kinase domain and CHEK2.P85L in the N-terminal region. To assay these alleles for loss of CHEK2 function, we tested their capacity to complement Rad53 deletion in Saccharomyces cerevisiae. CHEK2.S428F failed to complement Rad53 and thus largely abrogates normal CHEK2 function, whereas CHEK2.P85L complemented Rad53 as well as did wild-type CHEK2. Epidemiologic analyses were concordant with the functional tests. Frequencies of CHEK2.S428F heterozygotes were 2.88% (47/1632) among female breast cancer patients not selected for family history or age at diagnosis and 1.37% (23/1673) among controls (OR=2.13, 95% CI [1.26, 3.69], P=0.004), whereas frequencies of CHEK2.P85L were 0.92% among cases and 0.83% among controls. On the basis of the experience of mothers, sisters and daughters of probands, breast cancer risk due to CHEK2.S428F was estimated as 0.17 (+/-0.08) by age 60. We conclude that CHEK2.S428F increases breast cancer risk approximately 2-fold among Ashkenazi Jewish women, whereas CHEK2.P85L is a neutral allele. In general, these results suggest that selecting probands with extended haplotypes that co-segregate with disease can improve the efficiency of resequencing efforts and that quantitative complementation tests in yeast can be used to evaluate variants in genes with highly conserved function.     

Striatal expression of GDNF and differential vulnerability of midbrain dopaminergic cells

Glial cell line-derived neurotrophic factor (GDNF) is a member of the transforming growth factor-beta superfamily that when exogenously administrated exerts a potent trophic action on dopaminergic (DA) cells. Although we know a lot about its signalling mechanisms and pharmacological effects, physiological actions of GDNF on the adult brain remain unclear. Here, we have used morphological and molecular techniques, and an experimental model of Parkinson's disease in rats, to investigate whether GDNF constitutively expressed in the adult mesostriatal system plays a neuroprotective role on midbrain DA cells. We found that although all midbrain DA cells express both receptor components of GDNF (GFRalpha1 and Ret), those in the ventral tegmental area (VTA) and rostromedial substantia nigra (SNrm) also contain GDNF but not GDNFmRNA. The levels of GDNFmRNA are significantly higher in the ventral striatum (vSt), the target region of VTA and SNrm cells, than in the dorsal striatum (dSt), the target region of DA cells in the caudoventral substantia nigra (SNcv). After fluoro-gold injection in striatum, VTA and SNrm DA cells show triple labelling for tyrosine hydroxylase, GDNF and fluoro-gold, and after colchicine injection in the lateral ventricle, they become GDNF-immunonegative, suggesting that GDNF in DA somata comes from their striatal target. As DA cells in VTA and SNrm are more resistant than those in SNcv to intracerebroventricular injection of 6-OHDA, as occurs in Parkinson's disease, we can suggest that the fact that they project to vSt, where GDNF expression is significantly higher than in the dSt, is a neuroprotective factor involved in the differential vulnerability of midbrain DA neurons.     

Cortical distinction between the neural encoding of objects that appear to glow and those that do not

Objects that appear to glow appear very different from those that do not. However, the neural representation of glow has not been investigated. We present data from an fMRI study which suggest that an extra-striate visual area is involved in the encoding of glowing stimuli, and that this activation does not arise from luminance or contrast factors. Possible functional reasons for the existence of such an area are discussed.     

Reduced extracellular space in the brain of tenascin-R- and HNK-1-sulphotransferase deficient mice

Tenascin-R (TN-R), a large extracellular glycoprotein, is an important component of the adult brain's extracellular matrix (ECM); tenascin-C (TN-C) is expressed mainly during early development, while human natural killer 1 (HNK-1) is a sulphated carbohydrate epitope that attaches to these molecules, modifying their adhesive properties. To assess their influence on extracellular space (ECS) volume and geometry, we used the real-time iontophoretic method to measure ECS volume fraction alpha and tortuosity lambda, and diffusion-weighted magnetic resonance imaging (MRI) to measure the apparent diffusion coefficient of water (ADC(W)). Measurements were performed in vivo in the cortex and CA1 hippocampal region of TN-R-, TN-C- and HNK-1 sulphotransferase (ST)-deficient adult mice and their wild-type littermate controls. In both cortex and hippocampus, the lack of TN-R or HNK-1 sulphotransferase resulted in a significant decrease in alpha and lambda. Compared with controls, alpha in TN-R-/- and ST-/- mice decreased by 22-26% and 9-15%, respectively. MRI measurements revealed a decreased ADC(W) in the cortex, hippocampus and thalamus. ADC(W) reflected the changes in alpha; the decrease in lambda indicated fewer diffusion obstacles in the ECS, presumably due to a decreased macromolecular content. No significant changes were found in TN-C-/- animals. We conclude that in TN-R-/- and ST-/- mice, which show morphological, electrophysiological and behavioural abnormalities, the ECS is reduced and its geometry altered. TN-R, as an important component of the ECM, appears to maintain an optimal distance between cells. The altered diffusion of neuroactive substances in the brain will inevitably affect extrasynaptic transmission, neuron-glia interactions and synaptic efficacy.     

Prenatal diagnosis in laminin alpha2 chain (merosin)-deficient congenital muscular dystrophy: a collective experience of five international centers

The congenital muscular dystrophies (CMD) are clinically and genetically heterogeneous. The merosin (laminin alpha2 chain) deficient form (MDC1A), is characterized clinically by neonatal hypotonia, delayed motor milestones and associated contractures. It is caused by deficiency in the basal lamina of muscle fibers of the alpha2 chain of laminins 2 and 4 (LAMA2 gene at 6q22-23). Laminin alpha2 chain is also expressed in fetal trophoblast, which provides a suitable tissue for prenatal diagnosis in families where the index case has total deficiency of the protein. This article reports the collective experience of five centers over the past 10 years in 114 prenatal diagnostic studies using either protein analysis of the chorionic villus (CV) of the trophoblast plus DNA molecular studies with markers flanking the 6q22-23 region and intragenic polymorphisms (n=58), or using only DNA (n=44) or only protein (n=12) approaches. Of the 102 fetuses studied by molecular genetics, 27 (26%) were predicted to be affected while 75 (74%) were considered as unaffected, with 52 (51%) being heterozygous, thus conforming closely to an autosomal recessive inheritance. In 18 of the 27 affected fetuses, the trophoblast was studied by immunocytochemistry and there was a total or only traces deficiency of the protein in CV basement membrane in all. In 10 cases material from the presumably affected fetus was available for analysis after termination of the pregnancy and immunohistochemical study confirmed the diagnosis in all of them. Prenatal studies of 'at risk' pregnancies in the five centers produced neither false negative (merosin-deficiency in CVs in a normal fetus), nor false positive (normal merosin expression in CVs and affected child), indicating the reliability of the technique, when all the necessary controls are done. Our experience suggests that protein and DNA analysis can be used either independently or combined, according to the facilities of each center, to provide accurate prenatal diagnosis of the MDC1A, and have an essential role in genetic counseling.     

Ethanol perturbs the secretory pathway in astrocytes

Ethanol exposure induces retention of glycoproteins in growing astrocytes. We examined the intracellular sites at which this retention occurs and investigated whether this effect is accompanied by alterations in the Golgi complex and microtubular system. We studied the effects of ethanol on the Golgi complex structure, as well as on the secretory pathway functionality by monitoring both the transport of the VSV-G protein and the protein levels of several molecules involved in the regulation of this pathway. Ethanol was found to delay VSV-G transport, modify Golgi complex morphology, and reduce the number of secretory vesicles. Moreover, ethanol affected the levels of mannosidase II, p58, betaCOP, rbet1, and several Rab GTPases. It also affected microtubule organization and polymerization and the levels of the motor proteins kinesin and dynein. Most of these effects were dose-dependent. These alterations, together with those previously reported concerning biosynthesis of glycoconjugates, provide novel insights into how ethanol impairs brain development.     

Cortical regions involved in eye movements, shifts of attention, and gaze perception

Human vision is an active process that involves shifting attention across the visual scene, with or without moving the eyes. Such shifts of attention can be generated at will (endogenously) or be triggered automatically, i.e., generated in response to exogenous stimuli including socially relevant cues such as someone else's gaze. What are the common and distinct brain mechanisms involved in these processes? To address this question, we carried out a quantitative effect-location meta-analysis of 59 brain-imaging experiments whose results were published using standardized coordinates. For each condition of interest, namely voluntary and visually triggered eye movements, voluntary and visually triggered (covert) shifts of attention, and perception of someone else's gaze, we computed activation likelihood estimation (ALE) maps. Those maps represent at each voxel of the brain the probability of reporting a signal change related to the condition of interest. For eye movements, this analysis confirmed the spatial location of the frontal eye fields, supplementary eye fields, and parietal saccade-related regions. The map of covert shifts of attention demonstrated highest similarity with the map of saccadic eye movements. Gaze perception showed common activation likelihood with the other conditions in the right intraparietal sulcus and in the lateral precentral gyrus. It demonstrated more similarity with the reflexive than with the voluntary saccades and shifts of attention. We propose that a core network of frontoparietal and temporal brain regions is recruited when we shift the focus of our attention with or without eye movements in response to the appearance of a visual target, as well as when we see someone else shift his or her gaze.     

One-year outcome of psychotic depression after successful electroconvulsive therapy

BACKGROUND: Psychotic depression is thought to have a higher relapse frequency after electroconvulsive therapy (ECT) compared with nonpsychotic depression, although this observation is contradicted by previous studies that have found the opposite. In this study, the 1-year risk of relapse after successful ECT was determined prospectively in patients with psychotic depression and compared with the risk of relapse observed for depressed patients without psychotic features. METHOD: Fifty-nine responders to ECT (a decrease in Hamilton Rating Scale for Depression [HAM-D] score > or = 50%) were followed for 1 year: 29 with and 30 without psychotic features. Relapse was defined as meeting DSM-IV criteria for major depressive disorder and a HAM-D score > or = 16. The frequency of relapse after 4 and 12 months was compared between both samples, adjusted for the co-variables duration of the index episode and type of post-ECT pharmacotherapy. RESULTS:: At both 4 and 12 months after ECT, instances of relapse were significantly lower in patients with psychotic depression compared with nonpsychotic patients: 3/28 (11%) versus 16/27 (59%) and 4/27 (15%) versus 19/28 (68%), respectively. CONCLUSIONS: The main finding of the present study is the favorable 1-year outcome for patients with psychotic depression after response to ECT with a trend toward the same result at 4 months. The 1-year outcome of the total sample is also more favorable than expected.     

Psychopathology and treatment responsiveness of patients with first-episode schizophrenia

One hundred and four male patients hospitalized for the first time with the diagnosis of first-episode schizophrenia were comprehensively assessed on admission and discharge. Psychopathology, treatment response, and remission rates were evaluated (based on the Positive and Negative Syndrome Scale (PANSS), severity of symptoms only). On admission, the most frequently observed symptoms were lack of judgment and insight (87.6%), suspiciousness/feelings of persecution (82.3%), delusions (77%), poor attention (70%), disturbance of volition (65.4%), conceptual disorganization (64.7%), and active social avoidance (64%). Except for delusions and hallucinations, the positive items of the PANSS correlated significantly with negative symptoms, and conceptual disorganization correlated with the greatest number of negative symptoms. Individual negative symptoms were present in about half the patients. At discharge, the most frequent symptoms were again lack of judgment and insight (in 55.7%), and for negative symptoms they were blunted affect (22.1%), emotional withdrawal (21.2%), and passive/apathetic social withdrawal (19.5%). The positive symptoms of suspiciousness/feelings of persecution and grandiosity persisted in 20.6% of patients. On average, all symptoms were significantly reduced 44 days after admission. The negative symptoms improved less, compared with the positive ones. At discharge there was a high rate of responders (response defined as minimal 30% reduction of total PANSS): 73% and 74% of patients fulfilled the criteria for remission. On admission, the responders (n = 76) had significantly higher scores of most symptoms, both positive and negative ones than nonresponders (n = 28).     

Long-term lithium treatment and thyroid antibodies: a controlled study

OBJECTIVE: Because the role of thyroid autoimmunity in the development of lithium-induced thyroid dysfunction remains controversial, we compared the prevalence of thyroid autoantibodies in patients with affective disorders receiving long-term lithium maintenance therapy with that of age- and sex-matched controls. METHODS: We conducted a cross-sectional study with 100 adult patients with major affective disorders diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, revised (DSM-III-R), who were undergoing lithium therapy for 6 months or more at a specialized lithium university clinic and 100 age- and sex-matched controls with no history of an axis I psychiatric disorder. Serum autoantibodies against thyroid peroxidase (TPOAb), thyroglobulin (TgAb) and TSH receptors (TRAb) were measured. RESULTS: TPOAb were found in 7 patients and 11 controls, and TgAb were found in 8 patients and 15 controls. TRAb were not found in either group. CONCLUSIONS: In this sample of patients with affective disorders, long-term lithium treatment did not increase the prevalence of thyroid autoimmunity.