Electrophysiological analysis of a sensorimotor integration task

The present experiment aimed at investigating electrophysiologic changes observed as beta band asymmetry, by Quantitative Electroencephalography (qEEG), when individuals performed a reaching motor task (catching a ball in free fall). The sample was composed of 23 healthy individuals, of both sexes, with ages varying between 25 and 40 years old. All the subjects were right handed. A two-way ANOVA was applied for the statistical analysis, to verify the interaction between task moment (i.e., 2 s before and 2 s after ball's fall) and electrode (i.e., frontal, central and temporal regions). The first analysis compared electrodes placed over the somatosensory cortex. Central sites (C3–C4) were compared with temporal regions (T3–T4). The results showed a main effect for moment and position. The second analysis was focused over the premotor cortex, which was represented by the electrodes placed on the frontal sites (F3–F4 versus F7–F8), and a main effect was observed for position. Taken together, these results show a pattern of asymmetry in the somatosensory cortex, associated with a preparatory mechanism when individuals have to catch an object during free fall. With respect to task moment, after the ball's fall, the asymmetry was reduced. Moreover, the difference in asymmetry between the observed regions were related to a supposed specialization of areas (i.e., temporal and central). The temporal region was associated with cognitive processes involved in the motor action (i.e., explicit knowledge). On the other hand, the central sites were related to the motor control mechanisms per se (i.e., implicit knowledge). The premotor cortex, represented by two frontal regions (i.e., F3–F4 versus F7–F8), showed a decrease on neural activity in the contralateral hemisphere (i.e., to the right hand). This result is in agreement with other experiments suggesting a participation of the frontal cortex in the planning of the apprehension task. This sensorimotor paradigm may contribute to the repertoire of tasks used to study clinical conditions such as depression, alzheimer and Parkinson diseases.     

Melosis in holocentric chromosomes: Kinetic activity is randomly restricted to the chromatid ends of sex univalents inGraphosoma italicum (Heteroptera)

We have determined the number and location of the nucleolar organizing regions in spermatocytes ofGraphosoma italicum (2n=12A+ XY/XX) by means of silver impregnation, chromomycin A₃/distamycin A staining and fluorescencein situ hybridization. The identification of only one nucleolar organizing region located at one of the X chromosome ends has provided a suitable cytological marker to analyse the segregation of this univalent and that of the XY pseudobivalent during the first and second meiotic divisions respectively. Our results clearly show that at first meiotic metaphase the chromatids of the X chromosome are orientated with their long axes perpendicular to the polar axis. Although the kinetic activity is restricted to only one end in both X chromatids during the first meiotic division, both ends of the same chromatid have the same probability of showing such kinetic activity. In this sense, we also report that the chromatid segregation maybe initiated either at the same sister chromatid ends or at opposite ends in each chromatid. Thus, this indicates a sex chromatid independence as regards to the chromatid segregation during the first meiotic division. Throughout the second meiotic division both ends of the X chromatid are involved with the same probability in the end-to-end association to conform the XY pseudobivalent. This also implies a random localization of the kinetic activity at the ends opposite to those involved in the end-to-end association.accepted for publication by J. S. (Pat) Heslop-Harrison     

Aboriginal status is a prognostic factor for mortality among antiretroviral naïve HIV-positive individuals first initiating HAART

Background  

Although the impact of Aboriginal status on HIV incidence, HIV disease progression, and access to treatment has been investigated previously, little is known about the relationship between Aboriginal ethnicity and outcomes associated with highly active antiretroviral therapy (HAART). We undertook the present analysis to determine if Aboriginal and non-Aboriginal persons respond differently to HAART by measuring HIV plasma viral load response, CD4 cell response and time to all-cause mortality.     

The ribosomal DNA of the Zygomycete Mucor miehei

The ribosomal DNA from the Zygomycete Mucor miehei has been characterised. The complete rDNA unit was cloned by heterologous PCR using primers whose sequence matched conserved regions of the rDNA from related fungal species. The sequence of the overlapping PCR products revealed the existence of a repeated unit of 9574 bp. The genes encoding the different rRNA species were identified by their homology to the corresponding sequences from other fungi. We estimate that the rDNA unit is present in the genome of M. miehei in about 100 copies. This estimation was made by comparing the intensity of its hybridisation signal in a Southern blot with that of the mmp gene coding for aspartyl protease, which was assumed to be contained in single copy. The size and structure of the M. miehei rDNA unit was similar to that of other fungi. The genes encoding the 25S, 18S and 5.8S RNAs are closely linked within the repeated unit which also contains the 5S gene. This latter gene appears to be transcribed in the opposite direction. The 25S, 18S and 5.8S genes showed 70–80% homology to the corresponding genes from other fungi, whereas the degree of homology for the 5S gene was much lower. The highest homology (about 80%) corresponded to the few available sequences from other Mucor species. Homology to genes from other Zygomycota was no higher than that observed for genes from the Ascomycota or Basidiomycota fungi. Received: 21 December 1999 / 1 March 2000     

Hypoplastic left heart syndrome with intact atrial septum associated with deletion of the short arm of chromosome 18.

We report on a female newborn with deletion of the short arm of the chromosome 18 (del 18p) and hypoplastic left heart syndrome (HLHS) with intact atrial septum. Several forms of congenital heart disease (CHD) are found in 10% of patients with this chromosomal abnormality, although HLHS has not been reported yet. Interesting coronary artery anomalies, as well as the presence of pulmonary lymphangiectasia, were found in our patient and were contributors to her fatal outcome. Del 18 p must be considered when evaluating a patient with characteristic phenotypical anomalies and HLHS with intact atrial septum.     

Prolonged waking reduces human immunodeficiency virus glycoprotein 120- or tumor necrosis factor alpha-induced apoptosis in the cerebral cortex of rats

The human immunodeficiency virus (HIV) induces neuronal death, presumably by apoptosis. This effect may be triggered by the glycoprotein 120 (HIVgp120) released by HIV when infecting a cell, and mediated by tumor necrosis factor alpha (TNF), a pro-inflammatory cytokine. Both molecules, HIVgp120 and TNF, increase sleep when administered acutely in the brain. On the other hand, sleep deprivation increases the levels of several growth factors. In this context, we challenged rats with HIVgp120 or TNF simultaneously with sleep deprivation. Our results indicate that both HIVgp120 and TNF increase neuronal death in the rat cerebral cortex, but not hippocampus, and that this effect is completely prevented by total deprivation of sleep. These results suggest that acute total deprivation of sleep protects against the HIVgp120 and TNF deleterious effects.     

Kidney disease in the Hispanic population: facing the growing challenge

The incidence of kidney disease in the United States is rising at a steady, alarming pace. The growth rate has been particularly rapid for end-stage renal disease (ESRD), which has been reported to double every 10 years. Of even greater concern is the emergence of striking racial disparities in the prevalence, morbidity, and mortality of kidney disease, and in the provision of optimal care to prevent or slow progression of the disease. Hispanics, who are among the fastest-growing racial groups in the United States, are twice as likely to develop kidney failure as non-Hispanic whites, largely due to the increased prevalence of diabetes mellitus in the Hispanic population. However, Hispanic patients are less likely than the general U.S. population to be screened for risk factors for kidney disease or receive optimal treatment after diagnosis. Several actions are required to redress these racial inequalities. Improved cultural sensitivity on the part of physicians is fundamentally important, as are patient education programs targeted specifically at the diverse Hispanic groups. In addition, local initiatives should be supported on a wider scale by healthcare policymakers to encourage improved medical care within Hispanic communities and thereby reduce the burden of kidney disease on American society as a whole.     

Plasma HIV-1 RNA decline within the first two weeks of treatment is comparable for nevirapine, efavirenz, or both drugs combined and is not predictive of long-term virologic efficacy: A 2NN substudy

BACKGROUND: The initial rate of plasma HIV-1 RNA (pVL) decline has been proposed as a marker of early efficacy of antiretroviral therapy (ART) and a possible predictor of late efficacy. We compared the rate of pVL decline in patients starting ART with nevirapine (NVP), efavirenz (EFV), or both drugs combined in addition to lamivudine (3TC) and stavudine (d4T). METHODS: Analysis of the viral decay constant (VDc) during the first 2 weeks of treatment in patients enrolled in the 2NN study who remained on allocated treatment. RESULTS: The median VDc (log10 copies per day, [interquartile range]) was similar for NVP (0.30 [0.25-0.36], EFV (0.31 [0.27-0.37]), and NVP + EFV (0.30 [0.27-0.36]). Patients with a baseline pVL >100,000 copies/mL were 8.7 (95% confidence interval [CI]: 6.2-12.3) times more likely to have a VDc >75th percentile. A high VDc was not associated with plasma drug concentration or with a decreased risk of virologic failure at week 48 after the start of therapy (hazard ratio = 0.8, 95% CI: 0.6-1.2). CONCLUSION: NVP, EFV, or NVP + EFV in combination with 3TC and d4T show similar rates of pVL decline during the first 2 weeks of treatment. The VDc with these regimens is not predictive of late virologic efficacy.     

Squash Procedure for Protein Immunolocalization in Meiotic Cells

Several techniques have been developed for protein immunolocalization in meiotic cells. However, most of them include treatments that lead to cell disruption and are only suitable for prophase-I cells. We describe a novel squash procedure of cell preparation for protein immunolabelling of different meiotic stages. This procedure is an alternative to both cryosectioning and whole spreading procedures. We present results obtained in mouse spermatocytes with three different antibodies: the MPM-2 mAb against mitotic phosphoepitopes, an anticentromere serum and a polyclonal serum against the SCP3 protein of the axial elements and lateral elements of the synaptonemal complex. The procedure was tested for single and double immunolabelling. With this technique a large number of cells at different meiotic stages can be analysed. Cell stages are easily identified and cell and chromosome structures are preserved. Thus, it allows the study of chromosome behaviour and the relations hips between the different structural elements of the cell throughout meiotic divisions. Our procedure is also suitable for three-dimensional (3D) analyses and proved to be reliable in a wide range of systems including insects and mammals. In addition, the procedure may be interesting to obtain a rapid immunological diagnosis.