Quantifying systemic molecular networks affected during high altitude de-acclimatization.

High altitude acclimatization and disease have been the centerpiece of investigations concerning human health at high altitude. Almost all investigations have focused on either understanding and ameliorating high altitude disease or finding better methods of acclimatization/training at high altitude. The aspect of altitude de-induction/de-acclimatization has remained clouded despite the fact that it was documented since the first decade of twentieth century. A few recent studies, particularly in China, have stated unanimously that high altitude de-acclimatization involved multiple observable clinical symptoms ranging from headache to abdominal distention. These symptoms have been collectively referred to as "high altitude de-acclimatization syndrome" (HADAS). However, computational omics and network biology centric investigations concerning HADAS are nascent. In this study, we focus on the quantitative proteo-informatics, especially network biology, of human plasma proteome in individuals who successfully descended from high altitude areas after a stay of 120 days. In brief, the protein list was uploaded into STRING and IPA to compute z-score based cut-offs which were used to analyze the directionality and significance of various identified protein networks as well as the proteins within them. Relevant upstream regulators extracted using computational strategies were also validated. Time-points till the 180th day of de-induction have been investigated to comparatively assess the changes in the plasma proteome and protein pathways of such individuals since the 7th day of arrival at altitude. Our investigation revealed extensive effects of de-induction on lipid metabolism, inflammation and innate immune system as well as coagulation system. This novel study provides a conceptual framework for formulating therapeutic strategies to ease the symptoms of HADAS during de-acclimatization. Such strategies should focus on normalization of lipid metabolism, inflammatory signaling and coagulation systems.

Ginkgo biloba L. Prevents Hypobaric Hypoxia-Induced Spatial Memory Deficit Through Small Conductance Calcium-Activated Potassium Channel Inhibition: The Role of ERK/CaMKII/CREB Signaling.

Hypobaric hypoxia (HH) is a stressful condition, which is more common at high altitudes and can impair cognitive functions. Ginkgo biloba L. leaf extract (GBE) is widely used as herbal medicine against different disorders. Its ability to improve cognitive functions, reduce oxidative stress, and promote cell survival makes it a putative therapeutic candidate against HH. The present study has been designed to explore the effect of GBE on HH-induced neurodegeneration and memory impairment as well as possible signaling mechanisms involved. 220-250 gm (approximately 6- to 8-week-old) Sprague Dawley rats were randomly divided into different groups. GBE was orally administered to respective groups at a dose of 100 mg/kg/day throughout the HH exposure, i.e., 14 days. Memory testing was performed followed by hippocampus isolation for further processing of different molecular and morphological parameters related to cognition. The results indicated that GBE ameliorates HH-induced memory impairment and oxidative damage and reduces apoptosis. Moreover, GBE modulates the activity of the small conductance calcium-activated potassium channels, which further reduces glutamate excitotoxicity and apoptosis. The exploration of the downstream signaling pathway demonstrated that GBE administration prevents HH-induced small conductance calcium-activated potassium channel activation, and that initiates pro-survival machinery by activating extracellular signal-regulated kinase (ERK)/calmodulin-dependent protein kinase II (CaMKII) and the cAMP response element-binding protein (CREB) signaling pathway. In summary, the current study demonstrates the beneficial effect of GBE on conditions like HH and provides various therapeutic targets involved in the mechanism of action of GBE-mediated neuroprotection.

Elucidating the role of hypoxia/reoxygenation in hippocampus-dependent memory impairment: do SK channels play role?

Professionals and mountaineers often face the problem of reperfusion injury due to re-oxygenation, upon their return to sea-level after sojourn at high altitude. Small conductance calcium-activated potassium channels (SK channels) have a role in regulating hippocampal synaptic plasticity. However, the role of SK channels under hypoxia-reoxygenation (H/R) is unknown. The present study hypothesized that SK channels play a significant role in H/R induced cognitive dysfunction. Sprague-Dawley rats were exposed to simulated HH (25,000 ft) continuously for 7 days followed by reoxygenation periods 3, 6, 24, 48, 72 and 120 h. It was observed that H/R exposure caused impairment in spatial memory as indicated by increased latency (p < 0.001) and pathlength (p < 0.001). The SK1 channel expression increased upon HH exposure (102.89 ± 7.055), which abrogated upon reoxygenation. HH exposure results in an increase in SK2 (CA3, 297.67 ± 6.69) and SK3 (CA1, 246 ± 5.13) channels which continued to increase gradually upon reoxygenation. The number of pyknotic cells (24 ± 2.03) (p < 0.01) and the expression of caspase-3 increased with HH exposure, which continued in the reoxygenation group (177.795 ± 1.264). Similar pattern was observed in lipid peroxidation (p < 0.001), LDH activity (p < 0.001) and ROS production (p < 0.001). A positive correlation of memory, cell death and oxidative stress indicates that H/R exposure increases oxidative stress coupled with SK channel expression, which may play a role in H/R-induced cognitive decline and neurodegeneration.

Plasma protein(s)-based conceptual diagnostic tool for assessing high-altitude acclimation in humans.

Exposure to high altitude above 3000 m leads to two outcomes-acclimation or high-altitude maladies. To reach a particular outcome, the plasma proteome is modified differentially, either in context of an acclimation response or mal-acclimation response leading to disease. This ensures that hypoxia-responsive plasma protein trends reflect acclimation in acclimated individuals when compared with their levels prior to acclimation. Such protein trends could be used to assess acclimation in an individual and any significant deviation from this trend may indicate non-acclimation, thereby preventing high-altitude illnesses before they manifest. In this study, we investigate and statistically evaluate the trendlines of various hypoxia-responsive plasma protein levels, reported significantly perturbed in our previous studies, in individuals (male; n = 20) exposed to 3520 m at high-altitude day 1 (HAD1), HAD4, and HAD7L and to 4420 m at HAD7H, HAD30, and HAD120. We observe that thioredoxin (Trx), glutathione peroxidase 3 (GPx-3), and apolipoprotein AI (Apo-AI) are statistically robust markers to assess acclimation across the exposure duration while sulfotransferase 1A1 (ST1A1) is a capable negative control whose levels increase only in cases of HAPE. We also observe exposure day-specific and resident altitude-specific proteins capable of accurately assessing acclimation when compared with baseline levels or the lower altitude zone.

Hypobaric Hypoxia-Induced Learning and Memory Impairment: Elucidating the Role of Small Conductance Ca2+-Activated K+ Channels.

Hypobaric Hypoxia (HH) is well-known to cause cognitive impairment and synaptic dysfunction which results in neurodegeneration. Although the role of small conductance calcium-activated potassium channels (SK channels) has been reported in synaptic plasticity, cognition and different neurological disorders; however, the precise role of SK channels in HH-induced memory impairment remains yet to be explored. We, therefore, hypothesized the pivotal role of SK channels in HH-induced cognitive decline and investigated the SK channel expression during different duration of HH exposure (Control, 1, 3, 7 and 14 days) at mRNA and protein level in male Sprague-Dawley rats. Further the role of SK channels in spatial memory and neurodegeneration were explored by inhibiting SK channel through Apamin (a known SK channel blocker). Results from the present study revealed that acute exposure of HH for 3 days leads to significant increase in expression of SK1 and SK3 channels at mRNA and protein levels, which upon chronic exposure restored to normal. Remarkably, SK2 channel expression showed gradual increase from 3 days till 14 days. Immunohistochemical analysis revealed similar pattern in different regions of the hippocampus. Additionally, SK channel inhibition with Apamin prevented HH-induced neurodegeneration and memory impairment as evident from decreased number of Fluoro Jade-positive cells, pyknotic cells, and caspase-3 expression and improved performance in the Morris water maze task. Thus, the present study demonstrates that SK channels play a crucial role in HH-induced cognitive decline and neurodegeneration.

Activation of NLRP3 inflammasome complex potentiates venous thrombosis in response to hypoxia.

Venous thromboembolism (VTE), caused by altered hemostasis, remains the third most common cause of mortality among all cardiovascular conditions. In addition to established genetic and acquired risk factors, low-oxygen environments also predispose otherwise healthy individuals to VTE. Although disease etiology appears to entail perturbation of hemostasis pathways, the key molecular determinants during immediate early response remain elusive. Using an established model of venous thrombosis, we here show that systemic hypoxia accelerates thromboembolic events, functionally stimulated by the activation of nucleotide binding domain, leucine-rich-containing family, pyrin domain containing 3 (NLRP3) inflammasome complex and increased IL-1ß secretion. Interestingly, we also show that the expression of NLRP3 is mediated by hypoxia-inducible factor 1-alpha (HIF-1α) during these conditions. The pharmacological inhibition of caspase-1, in vivo knockdown of NLRP3, or HIF-1α other than IL-1ß-neutralizing antibodies attenuated inflammasome activation and curtailed thrombosis under hypoxic conditions. We extend the significance of these preclinical findings by studying modulation of this pathway in patients with altitude-induced venous thrombosis. Our results demonstrate distinctive, increased expression of NLRP3, caspase-1, and IL-1ß in individuals with clinically established venous thrombosis. We therefore propose that an early proinflammatory state in the venous milieu, orchestrated by the HIF-induced NLRP3 inflammasome complex, is a key determinant of acute thrombotic events during hypoxic conditions.

Neuroprotective Role of Intermittent Hypobaric Hypoxia in Unpredictable Chronic Mild Stress Induced Depression in Rats.

Hypoxic exposure results in several pathophysiological conditions associated with nervous system, these include acute and chronic mountain sickness, loss of memory, and high altitude cerebral edema. Previous reports have also suggested the role of hypoxia in pathogenesis of depression and related psychological conditions. On the other hand, sub lethal intermittent hypoxic exposure induces protection against future lethal hypoxia and may have beneficial effect. Therefore, the present study was designed to explore the neuroprotective role of intermittent hypobaric hypoxia (IHH) in Unpredictable Chronic Mild Stress (UCMS) induced depression like behaviour in rats. The IHH refers to the periodic exposures to hypoxic conditions interrupted by the normoxic or lesser hypoxic conditions. The current study examines the effect of IHH against UCMS induced depression, using elevated plus maze (EPM), open field test (OFT), force swim test (FST), as behavioural paradigm and related histological and molecular approaches. The data indicated the UCMS induced depression like behaviour as evident from decreased exploration activity in OFT with increased anxiety levels in EPM, and increased immobility time in the FST; whereas on providing the IHH (5000m altitude, 4hrs/day for two weeks) these behavioural changes were ameliorated. The morphological and molecular studies also validated the neuroprotective effect of IHH against UCMS induced neuronal loss and decreased neurogenesis. Here, we also explored the role of Brain-Derived Neurotrophic Factor (BDNF) in anticipatory action of IHH against detrimental effect of UCMS as upon blocking of BDNF-TrkB signalling the beneficial effect of IHH was nullified. Taken together, the findings of our study demonstrate that the intermittent hypoxia has a therapeutic potential similar to an antidepressant in animal model of depression and could be developed as a preventive therapeutic option against this pathophysiological state.

Candida nivariensis as an etiologic agent of vulvovaginal candidiasis in a tertiary care hospital of New Delhi, India.

Candida nivariensis is a cryptic species, phenotypically indistinguishable from Candida glabrata and identified by molecular methods. Aside its isolation from broncho-alveolar lavage, we report for the first time the etiologic role of C. nivariensis in 4 patients with vulvovaginal candidiasis. Of 100 phenotypically identified C. glabrata isolates originating from vaginal swabs, 4 were identified as C. nivariensis by polymerase chain reaction and confirmed by sequencing. All of the C. nivariensis isolates exhibited white colonies on CHROMagar. Phylogenetic analysis revealed genotypic diversity in the C. nivariensis isolates originating from within or outside of India. Barring a solitary C. nivariensis isolate with MIC, 16 µg/mL of fluconazole, the rest were susceptible to voriconazole, itraconazole, posaconazole, isavuconazole, amphotericin B, and echinocandins. The patient with high fluconazole MIC did not respond to fluconazole therapy. It is suggested that the prevalence of this species is likely to be much higher than apparent from the sporadic published reports.

Genital Ulcer Disease: How Worrisome Is It Today? A Status Report from New Delhi, India.

Background and Objectives. Genital ulcer diseases represent a diagnostic dilemma, especially in India, where few STI clinics have access to reliable laboratory facility. The changing STI trends require that a correct diagnosis be made in order to institute appropriate treatment and formulate control policies. The objective of this study was to determine recent trends in aetiology of genital ulcers, by using accurate diagnostic tools. Methods. Specimens from 90 ulcer patients were processed for dark field microscopy, stained smears, culture for H. ducreyi, and real-time PCR. Blood samples were collected for serological tests. Results. Prevalence of GUD was 7.45 with mean age at initial sexual experience as 19.2 years. Use of condom with regular and nonregular partners was 19.5% and 42.1%, respectively. Sexual orientation was heterosexual (92.2%) or homosexual (2.2%). There were 8 cases positive for HIV (8.9%). Herpes simplex virus ulcers were the commonest, followed by syphilis and chancroid. There were no cases of donovanosis and LGV. Conclusions. A valuable contribution of this study was in validating clinical and syndromic diagnoses of genital ulcers with an accurate aetiological diagnosis. Such reliable data will aid treatment and better define control measures of common agents and help eliminate diseases amenable to elimination, like donovanosis.

Permeation and gating in CaV3.1 (alpha1G) T-type calcium channels effects of Ca2+, Ba2+, Mg2+, and Na+.

We examined the concentration dependence of currents through Ca(V)3.1 T-type calcium channels, varying Ca(2+) and Ba(2+) over a wide concentration range (100 nM to 110 mM) while recording whole-cell currents over a wide voltage range from channels stably expressed in HEK 293 cells. To isolate effects on permeation, instantaneous current-voltage relationships (IIV) were obtained following strong, brief depolarizations to activate channels with minimal inactivation. Reversal potentials were described by P(Ca)/P(Na) = 87 and P(Ca)/P(Ba) = 2, based on Goldman-Hodgkin-Katz theory. However, analysis of chord conductances found that apparent K(d) values were similar for Ca(2+) and Ba(2+), both for block of currents carried by Na(+) (3 muM for Ca(2+) vs. 4 muM for Ba(2+), at -30 mV; weaker at more positive or negative voltages) and for permeation (3.3 mM for Ca(2+) vs. 2.5 mM for Ba(2+); nearly voltage independent). Block by 3-10 muM Ca(2+) was time dependent, described by bimolecular kinetics with binding at approximately 3 x 10(8) M(-1)s(-1) and voltage-dependent exit. Ca(2+)(o), Ba(2+)(o), and Mg(2+)(o) also affected channel gating, primarily by shifting channel activation, consistent with screening a surface charge of 1 e(-) per 98 A(2) from Gouy-Chapman theory. Additionally, inward currents inactivated approximately 35% faster in Ba(2+)(o) (vs. Ca(2+)(o) or Na(+)(o)). The accelerated inactivation in Ba(2+)(o) correlated with the transition from Na(+) to Ba(2+) permeation, suggesting that Ba(2+)(o) speeds inactivation by occupying the pore. We conclude that the selectivity of the "surface charge" among divalent cations differs between calcium channel families, implying that the surface charge is channel specific. Voltage strongly affects the concentration dependence of block, but not of permeation, for Ca(2+) or Ba(2+).