Arati Patel

Role of H- and D- MATE-type transporters from multidrug resistant clinical isolates of Vibrio fluvialis in conferring fluoroquinolone resistance.

Background The study seeks to understand the role of efflux pumps in multidrug resistance displayed by the clinical isolates of Vibrio fluvialis, a pathogen known to cause cholera-like diarrhoea. Methodology Two putative MATE family efflux pumps (H- and D-type) were PCR amplified from clinical isolates of V. fluvialis obtained from Kolkata, India, in 2006 and sequenced. Bioinformatic analysis of these proteins was done to predict protein structures. Subsequently, the genes were cloned and expressed in a drug hypersusceptible Escherichia coli strain KAM32 using the vector pBR322. The recombinant clones were tested for the functionality of the efflux pump proteins by MIC determination and drug transport assays using fluorimeter. Results The sequences of the genes were found to be around 99% identical to their counterparts in V. cholerae. Protein structure predicting servers TMHMM and I-TASSER depicted ten-twelve membrane helical structures for both type of pumps. Real time PCR showed that these genes were expressed in the native V. fluvialis isolates. In the drug transport assays, the V. fluvialis clinical isolates as well as recombinant E. coli harbouring the efflux pump genes showed the energy-dependent and sodium ion-dependent drug transport activity. KAM32 cells harbouring the recombinant plasmids showed elevated MIC to the fluoroquinolones, norfloxacin and ciprofloxacin but H-type pumps VCH and VFH from V. cholerae and V. fluvialis respectively, showed decreased MIC to aminoglycosides like gentamicin, kanamycin and streptomycin. Decrease in MIC was also observed for acriflavin, ethidium bromide, safranin and nalidixic acid. Significance Increased resistance towards fluoroquinolones exhibited due to these efflux pumps from multidrug resistant clinical isolates of V. fluvialis implies that treatment procedure may become more elaborate for this simple but highly infectious disease. To the best of our knowledge, this is the first report of cloning and characterization of efflux pumps from multidrug resistant clinical isolates of V. fluvialis.

Clinical effects of air pollution on the central nervous system; a review

The purpose of this review is to describe recent clinical and epidemiological studies examining the adverse effects of urban air pollution on the central nervous system (CNS). Air pollution and particulate matter (PM) are associated with neuroinflammation and reactive oxygen species (ROS). These processes affect multiple CNS pathways. The conceptual framework of this review focuses on adverse effects of air pollution with respect to neurocognition, white matter disease, stroke, and carotid artery disease. Both children and older individuals exposed to air pollution exhibit signs of cognitive dysfunction. However, evidence on middle-aged cohorts is lacking. White matter injury secondary to air pollution exposure is a putative mechanism for neurocognitive decline. Air pollution is associated with exacerbations of neurodegenerative conditions such as Alzheimers and Parkinsons diseases. Increases in stroke incidences and mortalities are seen in the setting of air pollution exposure and CNS pathology is robust. Large populations living in highly polluted environments are at risk. This review aims to outline current knowledge of air pollution exposure effects on neurological health.

Stroke Damage Is Exacerbated by Nano-Size Particulate Matter in a Mouse Model

This study examines the effects of nano-size particulate matter (nPM) exposure in the setting of murine reperfused stroke. Particulate matter is a potent source of inflammation and oxidative stress. These processes are known to influence stroke progression through recruitment of marginally viable penumbral tissue into the ischemic core. nPM was collected in an urban area in central Los Angeles, impacted primarily by traffic emissions. Re-aerosolized nPM or filtered air was then administered to mice through whole body exposure chambers for forty-five cumulative hours. Exposed mice then underwent middle cerebral artery occlusion/ reperfusion. Following cerebral ischemia/ reperfusion, mice exposed to nPM exhibited significantly larger infarct volumes and less favorable neurological deficit scores when compared to mice exposed to filtered air. Mice exposed to nPM also demonstrated increases in markers of inflammation and oxidative stress in the region of the ischemic core. The findings suggest a detrimental effect of urban airborne particulate matter exposure in the setting of acute ischemic stroke.

Categorical Versus Dimensional Approaches to Autism-Associated Intermediate Phenotypes in 22q11.2 Microdeletion Syndrome

BACKGROUND 22q11.2 Microdeletion syndrome (22q11DS) is associated with elevated rates of autism spectrum disorders (ASDs), although the diagnosis is controversial. In order to determine whether there is a biological substrate of ASD in 22q11DS, we examined neurocognitive and structural neuroanatomic differences between those with 22q11DS and an ASD diagnosis (22q11DS-ASD+) and those with 22q11DS without ASD (22q11DS-ASD-); we then determined whether these differences were better characterized within a categorical or dimensional framework. METHODS We collected multiple neurocognitive measures and high-resolution T1-weighted scans on 116 individuals (29 22q11DS-ASD+, 32 22q11DS-ASD-, 55 typically developing controls) between 6 and 26 years of age. Measures of subcortical volume, cortical thickness (CT), and surface area were extracted using the FreeSurfer image analysis suite. Group differences in neurocognitive and neuroanatomic measures were assessed; regression analyses were then performed to determine whether a categorical or dimensional measure of ASD was a better predictor of neurocognitive impairment and/or neuroanatomic abnormalities observed in 22q11DS-ASD+. RESULTS In comparison to 22q11DS-ASD-, 22q11DS-ASD+ participants exhibited decreased bilateral hippocampal CT and decreased right amygdala volumes. Those with 22q11DS-ASD+ also showed slowed processing speed and impairments in visuospatial and facial memory. Neurocognitive impairments fit a dimensional model of ASD, whereas reductions in parahippocampal CT were best explained by a categorical measure of ASD. CONCLUSIONS A combination of categorical and dimensional measures of ASD may provide the most comprehensive understanding of ASDs in 22q11DS.

Chronic cerebral hypoperfusion induced by bilateral carotid artery stenosis causes selective recognition impairment in adult mice

Abstract Objectives: Chronic cerebral hypoperfusion (CCH) can result in vascular dementia and small vessel white matter ischemic injury. These findings have previously been demonstrated in a murine experimental model of CCH secondary to bilateral common carotid artery stenosis (BCAS). This study sought to elucidate the effects of CCH on recognition memory as assessed by the novel object recognition (NOR) test and histological analysis of the hippocampus and perirhinal cortex. Methods: Studies were performed on ten-week-old male mice using bilateral 0.18 mm microcoils to narrow the carotid arteries in accordance with prior publications. Following surgery, BCAS (n = 6) and sham (n = 6) mice were evaluated using NOR and 8-arm radial maze testing paradigms. Tissue damage was assessed using H&E staining on a parallel cohort of mice (n = 6 BCAS, n = 7 sham). Results: In the NOR paradigm, BCAS mice demonstrated significant deficits in short-term memory. Consistent with prior studies, BCAS mice also performed significantly worse on 8-arm radial maze testing. BCAS mice exhibited significantly more neuronal injury in the perirhinal cortex when compared to sham-operated mice. However, no significant differences in neuronal damage were observed in the CA1 region of the hippocampus. Discussion: Experimental CCH secondary to BCAS results in recognition memory deficits on NOR testing. Damage to the perirhinal cortex, rather than to the hippocampus, may underlie this impairment.

Neuroprotective strategies following intraparenchymal hemorrhage

Intracerebral hemorrhage and, more specifically, intraparenchymal hemorrhage, are devastating disease processes with poor clinical outcomes. Primary injury to the brain results from initial hematoma expansion while secondary hemorrhagic injury occurs from blood-derived products such as hemoglobin, heme, iron, and coagulation factors that overwhelm the brains natural defenses. Novel neuroprotective treatments have emerged that target primary and secondary mechanisms of injury. Nonetheless, translational application of neuroprotectants from preclinical to clinical studies has yet to show beneficial clinical outcomes. This review summarizes therapeutic agents and neuroprotectants in ongoing clinical trials aimed at targeting primary and secondary mechanisms of injury after intraparenchymal hemorrhage.

Estradiol Protects White Matter of Male C57BL6J Mice against Experimental Chronic Cerebral Hypoperfusion

BACKGROUND AND PURPOSE Estradiol is a sex steroid hormone known to protect the brain against damage related to transient and global cerebral ischemia. In the present study, we leverage an experimental murine model of bilateral carotid artery stenosis (BCAS) to examine the putative effects of estradiol therapy on chronic cerebral hypoperfusion. We hypothesize that long-term estradiol therapy protects against white matter injury and declarative memory deficits associated with chronic cerebral hypoperfusion. METHODS Adult male C57BL/6J mice underwent either surgical BCAS or sham procedures. Two days after surgery, the mice were given oral estradiol (Sham+E, BCAS+E) or placebo (Sham+P, BCAS+P) treatments daily for 31-34 days. All mice underwent Novel Object Recognition (NOR) testing 31-34 days after the start of oral treatments. Following sacrifice, blood was collected and brains fixed, sliced, and prepared for histological examination of white matter injury and extracellular signal-regulated kinase (ERK) expression. RESULTS Animals receiving long-term oral estradiol therapy (BCAS-E2 and Sham-E2) had higher plasma estradiol levels than those receiving placebo treatment (BCAS-P and Sham-P). BCAS-E2 mice demonstrated less white matter injury (Klüver-Barrera staining) and performed better on the NOR task compared to BCAS-P mice. ERK expression in the brain was increased in the BCAS compared to sham cohorts. Among the BCAS mice, the BCAS-E2 cohort had a greater number of ERK + cells. CONCLUSION This study demonstrates a potentially protective role for oral estradiol therapy in the setting of white matter injury and declarative memory deficits secondary to murine chronic cerebral hypoperfusion.

Experimental chronic cerebral hypoperfusion results in decreased pericyte coverage and increased blood–brain barrier permeability in the corpus callosum:

Murine chronic cerebral hypoperfusion (CCH) results in white matter (WM) injury and behavioral deficits. Pericytes influence blood–brain barrier (BBB) integrity and cerebral blood flow. Under hypoxic conditions, pericytes detach from perivascular locations increasing vessel permeability and neuronal injury. This study characterizes the time course of BBB dysfunction and pericyte coverage following murine experimental CCH secondary to bilateral carotid artery stenosis (BCAS). Mice underwent BCAS or sham operation. On post-procedure days 1, 3, 7 and 30, corpus callosum BBB permeability was characterized using Evans blue (EB) extravasation and IgG staining and pericyte coverage/count was calculated. The BCAS cohort demonstrated increased EB extravasation on postoperative days 1 (p = 0.003) 3 (p = 0.002), and 7 (p = 0.001) when compared to sham mice. Further, EB extravasation was significantly greater (p = 0.05) at day 3 than at day 30 in BCAS mice. BCAS mice demonstrated a nadir in pericyte coverage and count on post-operative day 3 (p < 0.05, compared to day 7, day 30 and sham). Decreased pericyte coverage/count and increased BBB permeability are most pronounced on postoperative day 3 following murine CCH. This precedes any notable WM injury or behavioral deficits.

Predictors of Surgical Site Infection After Nonemergent Craniotomy: A Nationwide Readmission Database Analysis

OBJECTIVE Surgical site infections (SSIs) carry significant patient morbidity and mortality and are a major source of readmissions after craniotomy. Because of their deleterious effects on health care outcomes and costs, identifying modifiable risk factors holds tremendous value. However, because SSIs after craniotomy are rare and most existing data comprise single-institution studies with small sample sizes, many are likely underpowered to discern for such factors. The objective of this study was to use a large hetereogenous patient sample to determine SSI incidence after nonemergent craniotomy and identify factors associated with readmission and subsequent need for wound washout. METHODS We used the 2010-2014 Nationwide Readmissions Database cohorts to discern for factors predictive of SSI and washout. RESULTS We identified 93,920 nonemergent craniotomies. There were 2079 cases of SSI (2.2%) and 835 reoperations for washout (0.89%) within 30 days of index admission and there were 2761 cases of SSI (3.6%) and 1220 reoperations for washout (1.58%) within 90 days. Several factors were predictive of SSI in multivariate analysis, including tumor operations, external ventricular drain (EVD), age, length of stay, diabetes, discharge to an intermediate-care facility, insurance type, and hospital bed size. Many of these factors were similarly implicated in reoperation for washout. CONCLUSIONS SSI incidence in neurosurgery is low and most readmissions occur within 30 days. Several factors predicted SSI after craniotomy, including operations for tumor, younger age, hospitalization length, diabetes, discharge to institutional care, larger hospital bed size, Medicaid insurance, and presence of an EVD. Diabetes and EVD placement may represent modifiable factors that could be explored in subsequent prospective studies for their associations with cranial SSIs.

Spine Surgery Complicated by an Engorged Lumbar Epidural Venous Plexus from Cerebrospinal Fluid Overshunting: A Case Report and Review of the Literature

BACKGROUND Overshunting of cerebrospinal fluid may lead to intracranial hypotension and dilation of spinal epidural veins. Radiculopathy may rarely occur secondary to engorged spinal epidural veins. In addition, the cause of radiculopathy may be obscured by concomitant spinal degenerative changes. We present a case and review the pathogenesis as well as the current clinical literature. CASE DESCRIPTION A 29-year-old woman presented with positional headaches from intracranial hypotension in the setting of cerebrospinal fluid overshunting. The patient also had back pain and lumbar radiculopathy, which became more severe after lumboperitoneal shunt placement. On radiographic work-up, there was evidence of right L5 nerve root impingement secondary to a disc bulge and an engorged lumbar epidural venous plexus secondary to overshunting. The patient underwent surgery for a planned L4-5 decompression with a transforaminal lumbar interbody fusion. The operation was complicated by rapid blood loss originating from the epidural venous plexus, and we were unable to safely place the interbody graft. CONCLUSIONS Spinal surgeons need to be aware of the rare diagnosis of radiculopathy secondary to epidural venous plexus engorgement, as it may change the treatment approach or lead to deleterious intraoperative consequences, such as hemorrhage.