Neeraj Joshi

Pch2 links chromosome axis remodeling at future crossover sites and crossover distribution during yeast meiosis.

Segregation of homologous chromosomes during meiosis I depends on appropriately positioned crossovers/chiasmata. Crossover assurance ensures at least one crossover per homolog pair, while interference reduces double crossovers. Here, we have investigated the interplay between chromosome axis morphogenesis and non-random crossover placement. We demonstrate that chromosome axes are structurally modified at future crossover sites as indicated by correspondence between crossover designation marker Zip3 and domains enriched for axis ensemble Hop1/Red1. This association is first detected at the zygotene stage, persists until double Holliday junction resolution, and is controlled by the conserved AAA+ ATPase Pch2. Pch2 further mediates crossover interference, although it is dispensable for crossover formation at normal levels. Thus, interference appears to be superimposed on underlying mechanisms of crossover formation. When recombination-initiating DSBs are reduced, Pch2 is also required for viable spore formation, consistent with further functions in chiasma formation. pch2Δ mutant defects in crossover interference and spore viability at reduced DSB levels are oppositely modulated by temperature, suggesting contributions of two separable pathways to crossover control. Roles of Pch2 in controlling both chromosome axis morphogenesis and crossover placement suggest linkage between these processes. Pch2 is proposed to reorganize chromosome axes into a tiling array of long-range crossover control modules, resulting in chiasma formation at minimum levels and with maximum spacing.

Astrocyte activation and neurotoxicity: A study in different rat brain regions and in rat C6 astroglial cells.

The present study was conducted to investigate the effect of rotenone on astrocytes activation, their viability and its effect on neuronal death in different brain regions. Rotenone was injected in rat brain by intracerebroventricularly (bilateral) route at dose of 6 μg and 12 μg. In vitro C6 cells were treated with rotenone at concentration of 0.1, 0.25, 0.5, 1 and 2 μM. Rotenone administration to rat brain caused significant astrocytes activation in frontal cortex, cerebellum, cerebellar nucleus, substantia nigra, hypothalamus and hippocampus regions of the rat brain. Rotenone administration also led to significant degeneration of cells in all the studied regions along with altered nuclear morphology assessed by hematoxylin-eosin and cresyl violet staining. Histological staining showed the significantly decreased number of cells in all the studied regions except cerebellar nucleus in dose and time dependant manner. Rotenone administration in the rat brain also caused significant decrease in glutathione levels and augmented nitrite levels. In vitro treatment of rotenone to astrocytic C6 cells caused significantly increased expression of glial fibrillar acidic protein (GFAP) and decreased viability in dose and time dependent manner. Rotenone treatment to C6 cells exhibited significant generation of reactive oxygen species, augmented nitrite level, impaired mitochondrial activity, apoptotic chromatin condensation and DNA damage in comparison to control cells. Findings showed that oxidative stress play a considerable role in rotenone induced astrocyte death that was attenuated with co-treatment of antioxidant melatonin. In conclusion, results showed that rotenone caused significant astrocytes activation, altered nuclear morphology, biochemical alteration and apoptotic cell death in different rat brain regions. In vitro observations in C6 cells showed that rotenone treatment exhibited oxidative stress mediated apoptotic cell death, which was attenuated with co treatment of melatonin.

Promising Role of Melatonin as Neuroprotectant in Neurodegenerative Pathology

Melatonin treatment showed a potent neuroprotective action in experimental models and in clinical studies. However, the entire disease prevention is not observed with melatonin treatment. Therefore, findings have suggested its future use in combination therapies for neurological diseases. Several studies have showed its free radical scavenging, antioxidant property, antiapoptotic activity, and its action towards enhanced mitochondrial function. It has direct and indirect effects on mitochondrial functions. Neurodegenerative disease pathology includes the impaired mitochondrial functions and apoptotic death of neurons due to energy crisis which could be prevented with antiapoptotic activity of melatonin. However, for the therapeutic use of melatonin, researchers also need to pay attention towards the various intermediary events taking place in apoptotic death of neurons during disease pathology. Age-related neurological diseases include the decreased level of melatonin in neuronal death. Therefore, it is worthwhile to discuss about the different functions of melatonin in aspect of its antioxidative property, its role in the enhancement of mitochondrial function, and its antiapoptotic attributes. This review summarizes the reports to date showing the potent role of melatonin in experimental models and clinical trials and discussing the employment of melatonin as future potent neuroprotective agent.

The metabolic enhancer piracetam attenuates mitochondrion-specific endonuclease G translocation and oxidative DNA fragmentation

This study was performed to investigate the involvement of mitochondrion-specific endonuclease G in piracetam (P)-induced protective mechanisms. Studies have shown the antiapoptotic effects of piracetam but the mechanism of action of piracetam is still an enigma. To assess the involvement of endonuclease G in piracetam-induced protective effects, astrocyte glial cells were treated with lipopolysaccharide (LPS) and piracetam. LPS treatment caused significantly decreased viability, mitochondrial activity, oxidative stress, chromatin condensation, and DNA fragmentation, which were attenuated by piracetam cotreatment. Cotreatment of astrocytes with piracetam showed its significantly time-dependent absorption as observed with high-performance liquid chromatography. Astrocytes treated with piracetam alone showed enhanced mitochondrial membrane potential (MMP) in comparison to control astrocytes. However, in LPS-treated cells no significant alteration in MMP was observed in comparison to control cells. Protein and mRNA levels of the terminal executor of the caspase-mediated pathway, caspase-3, were not altered significantly in LPS or LPS + piracetam-treated astrocytes, whereas endonuclease G was significantly translocated to the nucleus in LPS-treated astrocytes. Piracetam cotreatment attenuated the LPS-induced endonuclease G translocation. In conclusion this study indicates that LPS treatment of astrocytes caused decreased viability, oxidative stress, mitochondrial dysfunction, chromatin condensation, DNA damage, and translocation of endonuclease G to the nucleus, which was inhibited by piracetam cotreatment, confirming that the mitochondrion-specific endonuclease G is one of the factors involved in piracetam-induced protective mechanisms.

Biased expression of T cell receptor genes characterizes activated T cells in multiple sclerosis cerebrospinal fluid

To better characterize the inflammatory response that occurs in the nervous system in multiple sclerosis (MS), T‐cell receptor (TCR) gene expression was quantified from cerebrospinal fluid (CSF) cells of 21 patients with active disease. Unstimulated CSF cells expressed each of 22 different TCR beta chain variable region (Vβ) gene families in proportion to their expression in simultaneously sampled peripheral blood. When CSF cells from individuals with MS were expanded by in vitro culture in T‐cell growth factor/interleukin 2 and 4‐containing medium (TCGF/IL2/IL4), restricted numbers of Vβ genes were expressed. In many subjects, expanded CSF cells expressed predominantly Vβ2. In contrast to CSF, expansion of corresponding peripheral blood mononuclear cells (PBMC) in TCGF/IL2/IL4 resulted in persistent expression of an Vβ gene families. Within individuals, different Vβ genes were overexpressed by PBMC compared with CSF cells. No effect of the HLA haplotype of the individual on CSF Vβ gene expression was observed. Expanded CSF cells retained their capacity to respond to mitogen stimulation, but the proliferative response to myelin basic protein (MBP) was not enhanced. Finally, freshly obtained CSF cells stimulated directly with MBP also expressed a limited number of Vβ genes, although these were generally different from patterns observed following stimulation with TCGF/IL2/IL4. Thus, restricted populations of T cells capable of responding to TCGF/IL2/IL4, presumably reflecting in vivo activated cells, are compartmentalized in the nervous system in MS.

Neurodegenerative signaling factors and mechanisms in Parkinson's pathology

Parkinsons disease (PD) is a chronic and progressive degenerative disorder of central nervous system which is mainly characterized by selective loss of dopaminergic neurons in the nigrostrial pathway. Clinical symptoms of this devastating disease comprise motor impairments such as resting tremor, bradykinesia, postural instability and rigidity. Current medications only provide symptomatic relief but fail to halt the dopaminergic neuronal death. While the etiology of dopaminergic neuronal death is not fully understood, combination of various molecular mechanisms seems to play a critical role. Studies from experimental animal models have provided crucial insights into the molecular mechanisms in disease pathogenesis and recognized possible targets for therapeutic interventions. Recent findings implicate the involvement of abnormal protein accumulation and phosphorylation, mitochondrial dysfunction, oxidative damage and deregulated kinase signaling as key molecular mechanisms affecting the normal function as well survival of dopaminergic neurons. Here we discuss the relevant findings on the PD pathology related mechanisms and recognition of the cell survival mechanisms which could be used as targets for neuroprotective strategies in preventing this devastating disorder.

Updates on immunity and inflammation in Parkinson disease pathology

Studies in the last decade have suggested the association of both neuroinflammatory processes and immune responses in Parkinson disease (PD) pathology. PD pathology is related to depleted dopamine levels, α‐synuclein aggregation, and death of nigrostriatal dopaminergic neurons. Reports have suggested central and peripheral inflammation in the prodromal stage of the disease, which is sustained during disease progression. Alongside the activation of peripheral immune system exacerbates the dissonant central inflammatory responses and could contribute in synergistic neurodegeneration. Activated glial cells contribute significantly in the neuroinflammatory process during the occurrence of the disease and are also acknowledged as a hallmark of disease progression. However, the contribution of glial cells is not well defined in the context of neurodegeneration and neuroprotection. This review provides an overview of the roles of immune and inflammatory responses and their consequences in PD disease pathogenesis and also discusses possible therapeutic strategies for PD based on these findings.

6-Hydroxydopamine and lipopolysaccharides induced DNA damage in astrocytes: Involvement of nitric oxide and mitochondria

The present study was conducted to investigate the effect of the neurotoxins 6-hydroxydopamine and lipopolysaccharide on astrocytes. Rat astrocyte C6 cells were treated with different concentration of 6-hydroxydopamine (6-OHDA)/lipopolysaccharides (LPS) for 24 h. Both neurotoxins significantly decreased the viability of astrocytes, augmented the expression of inducible nitric oxide synthase (iNOS) and the astrocyte marker--glial fibrillar acidic protein. A significantly decreased mitochondrial dehydrogenase activity, mitochondrial membrane potential, augmented reactive oxygen species (ROS) level, caspase-3 mRNA level, chromatin condensation and DNA damage was observed in 6-OHDA/LPS treated astroglial cells. 6-OHDA/LPS treatment also caused the significantly increased expression of iNOS and nitrite level. Findings showed that 6-OHDA/LPS treatment caused mitochondrial dysfunction mediated death of astrocytes, which significantly involve the nitric oxide. Since we have observed significantly increased level of iNOS along with mitochondrial impairment and apoptotic cell death in astrocytes, therefore to validate the role of iNOS, the cells were co-treated with iNOS inhibitor aminoguanidine (AG, 100 μM). Co-treatment of AG significantly attenuated the 6-OHDA/LPS induced cell death, mitochondrial activity, augmented ROS level, chromatin condensation and DNA damage. GFAP and caspase-3 expression were also inhibited with co-treatment of AG, although the extent of inhibition was different in both experimental sets. In conclusion, the findings showed that iNOS mediated increased level of nitric oxide acts as a key regulatory molecule in 6-OHDA/LPS induced mitochondrial dysfunction, DNA damage and apoptotic death of astrocytes.

Astrocytes: inexplicable cells in neurodegeneration

Astrocytes are the most explored non-neuronal cells in the brain under neurophysiological and neurodegenerative conditions. Extensive research has been done to understand their specific role during neuropathological conditions but still the existing findings could not conclude their mechanism of action and their specific role in neurodegenerative conditions. This review discusses their physiological and pathological roles, their activation, morphological alterations and their probable use in search of new therapeutic targets for the treatment of neurodegenerative diseases.

Optimizing Emergency Department Imaging Utilization Through Advanced Health Record Technology

muchofthedatacontainedinEHRs are stored as free-text documents and are difficult to access and review efficiently by care providers, which may lead to redundant or inappropriate utilization of health care resources.Inresponsetothisdifficulty, a team of clinicians and software developers within our Department of Radiology’s informatics division has leveraged advanced EHR technologytodevelopasearchenginefor theEHRknownasQueriablePatient Inference Dossier (QPID) [8]. QPID