Peripheral chemoreflex inhibition with low-dose dopamine: new insight into mechanisms of extreme apnea.

The purpose of this study was to determine the impact of peripheral chemoreflex inhibition with low-dose dopamine on maximal apnea time, and the related hemodynamic and cerebrovascular responses in elite apnea divers. In a randomized order, participants performed a maximal apnea while receiving either intravenous 2 μg·kg(-1)·min(-1) dopamine or volume-matched saline (placebo). The chemoreflex and hemodynamic response to dopamine was also assessed during hypoxia [arterial O2 tension, (PaO2 ) ∼35 mmHg] and mild hypercapnia [arterial CO2 tension (PaCO2 ) ∼46 mmHg] that mimicked the latter parts of apnea.

Mesopic luminance assessed with minimally distinct border perception.

In photopic vision, the border between two fields is minimally distinct when the two fields are isoluminant; that is, when the achromatic luminance of the two fields is equal. The distinctness of a border between extrafoveal reference and comparison fields was used here as an isoluminance criterion under a variety of adaptation conditions ranging from photopic to scotopic. The adjustment was done by trading off the amount of blue against the amount of red in the comparison field.

Pain Phenotypes and Associated Clinical Risk Factors Following Traumatic Amputation: Results from Veterans Integrated Pain Evaluation Research (VIPER).

Objective: To define clinical phenotypes of postamputation pain and identify markers of risk for the development of chronic pain.

Design: Cross-sectional study of military service members enrolled 3-18 months after traumatic amputation injury.

Setting: Military Medical Center.

Oxycodone/naloxone preparation can cause acute withdrawal symptoms when misused parenterally or taken orally.

Context: Oral oxycodone/naloxone preparations are designed to reduce the incidence of constipation associated with oxycodone use. The low oral bioavailability (< 2%) of naloxone makes the precipitation of the acute opioid withdrawal symptoms unlikely following oral oxycodone/naloxone exposure. The incidence of acute opioid withdrawal symptoms following both oral and intravenous administration of oxycodone/naloxone preparations has not been described.

Impact of hindcast length on estimates of seasonal climate predictability.

Unlabelled: It has recently been argued that single-model seasonal forecast ensembles are overdispersive, implying that the real world is more predictable than indicated by estimates of so-called perfect model predictability, particularly over the North Atlantic. However, such estimates are based on relatively short forecast data sets comprising just 20 years of seasonal predictions. Here we study longer 40 year seasonal forecast data sets from multimodel seasonal forecast ensemble projects and show that sampling uncertainty due to the length of the hindcast periods is large.

Why hearts flutter: Distorted dim motions.

When a display of red spots or hearts on a blue surround is moved around under dim light, the spots appear to wobble or flutter relative to the surround (the "fluttering hearts" effect). We explain this as follows: Rods and cones both respond to the hearts. Rods are more sluggish than cones, with a latency of ∼50 ms, and they are also much more sensitive to blue than to red (the Purkinje shift; Purkinje, 1825).

End tidal-to-arterial CO2 and O2 gas gradients at low- and high-altitude during dynamic end-tidal forcing.

We sought to characterize and quantify the performance of a portable dynamic end-tidal forcing (DEF) system in controlling the partial pressure of arterial CO2 (Pa(CO2)) and O2 (Pa(O2)) at low (LA; 344 m) and high altitude (HA; 5,050 m) during an isooxic CO2 test and an isocapnic O2 test, which is commonly used to measure ventilatory and vascular reactivity in humans (n = 9). The isooxic CO2 tests involved step changes in the partial pressure of end-tidal CO2 (PET(CO2)) of -10, -5, 0, +5, and +10 mmHg from baseline. The isocapnic O2 test consisted of a 10-min hypoxic step (PET(O2) = 47 mmHg) from baseline at LA and a 5-min euoxic step (PET(O2) = 100 mmHg) from baseline at HA.

A lack of experience-dependent plasticity after more than a decade of recovered sight.

In 2000, monocular vision was restored to M. M., who had been blind between the ages of 3 and 46 years.

The contribution of arterial blood gases in cerebral blood flow regulation and fuel utilization in man at high altitude.

The effects of partial acclimatization to high altitude (HA; 5,050 m) on cerebral metabolism and cerebrovascular function have not been characterized. We hypothesized (1) increased cerebrovascular reactivity (CVR) at HA; and (2) that CO2 would affect cerebral metabolism more than hypoxia. PaO2 and PaCO2 were manipulated at sea level (SL) to simulate HA exposure, and at HA, SL blood gases were simulated; CVR was assessed at both altitudes.

Using multi-country household surveys to understand who provides reproductive and maternal health services in low- and middle-income countries: a critical appraisal of the Demographic and Health Surveys.

Objective: The Demographic and Health Surveys (DHS) are a vital data resource for cross-country comparative analyses. This study is part of a set of analyses assessing the types of providers being used for reproductive and maternal health care across 57 countries. Here, we examine some of the challenges encountered using DHS data for this purpose, present the provider classification we used, and provide recommendations to enable more detailed and accurate cross-country comparisons of healthcare provision.

Individual-Specific, Beat-to-beat Trending of Significant Human Blood Loss: The Compensatory Reserve.

Current monitoring technologies are unable to detect early, compensatory changes that are associated with significant blood loss. We previously introduced a novel algorithm to calculate the Compensatory Reserve Index (CRI) based on the analysis of arterial waveform features obtained from photoplethysmogram recordings. In the present study, we hypothesized that the CRI would provide greater sensitivity and specificity to detect blood loss compared with traditional vital signs and other hemodynamic measures.

Improved upper limits on the stochastic gravitational-wave background from 2009-2010 LIGO and Virgo data.

Gravitational waves from a variety of sources are predicted to superpose to create a stochastic background. This background is expected to contain unique information from throughout the history of the Universe that is unavailable through standard electromagnetic observations, making its study of fundamental importance to understanding the evolution of the Universe. We carry out a search for the stochastic background with the latest data from the LIGO and Virgo detectors.

Visualizing the uncertainty in the relationship between seasonal average climate and malaria risk.

Around $1.6 billion per year is spent financing anti-malaria initiatives, and though malaria morbidity is falling, the impact of annual epidemics remains significant. Whilst malaria risk may increase with climate change, projections are highly uncertain and to sidestep this intractable uncertainty, adaptation efforts should improve societal ability to anticipate and mitigate individual events.

Compensation for red-green contrast loss in anomalous trichromats.

For anomalous trichromats, threshold contrasts for color differences captured by the L and M cones and their anomalous analogs are much higher than for normal trichromats. The greater spectral overlap of the cone sensitivities reduces chromatic contrast both at and above threshold. But above threshold, adaptively nonlinear processing might compensate for the chromatically impoverished photoreceptor inputs.

Regulation of brain blood flow and oxygen delivery in elite breath-hold divers.

The roles of involuntary breathing movements (IBMs) and cerebral oxygen delivery in the tolerance to extreme hypoxemia displayed by elite breath-hold divers are unknown. Cerebral blood flow (CBF), arterial blood gases (ABGs), and cardiorespiratory metrics were measured during maximum dry apneas in elite breath-hold divers (n=17). To isolate the effects of apnea and IBM from the concurrent changes on ABG, end-tidal forcing ('clamp') was then used to replicate an identical temporal pattern of decreasing arterial PO2 (PaO2) and increasing arterial PCO2 (PaCO2) while breathing.

Influence of high altitude on cerebral blood flow and fuel utilization during exercise and recovery.

We examined the hypotheses that: (1) during incremental exercise and recovery following 4-6 days at high altitude (HA) global cerebral blood flow (gCBF) increases to preserve cerebral oxygen delivery (CDO2) in excess of that required by an increasing cerebral metabolic rate of oxygen ( CM RO2); (2) the trans-cerebral exchange of oxygen vs. carbohydrates (OCI; carbohydrates = glucose + ½lactate) would be similar during exercise and recovery at HA and sea level (SL). Global CBF, intra-cranial arterial blood velocities, extra-cranial blood flows, and arterial-jugular venous substrate differences were measured during progressive steady-state exercise (20, 40, 60, 80, 100% maximum workload (Wmax)) and through 30 min of recovery.

The role of the private sector in the provision of antenatal care: a study of Demographic and Health Surveys from 46 low- and middle-income countries.

Objective: To examine the role of the private sector in the provision of antenatal care (ANC) across low- and middle-income countries.

Methods: Demographic and Health Survey (DHS) data from 46 countries (representing 2.6 billion people) on components of ANC given to 303 908 women aged 15-49 years for most recent birth were used.

The accuracy of a near-infrared spectroscopy cerebral oximetry device and its potential value for estimating jugular venous oxygen saturation.

Background: An intriguing potential clinical use of cerebral oximeter measurements (SctO2) is the ability to noninvasively estimate jugular bulb venous oxygen saturation (SjvO2). Our purpose in this study was to determine the accuracy of the FORE-SIGHT(®) (CAS Medical Systems, Branford, CT), which is calibrated to a weighted average of 70% (SjvO2) and 30% arterial saturation, for Food and Drug Administration pre-market approval 510(k) certification by adapting an industry standard protocol, ISO 9919:2005 (www.ISO.

Impact of hypocapnia and cerebral perfusion on orthostatic tolerance.

We examined two novel hypotheses: (1) that orthostatic tolerance (OT) would be prolonged when hyperventilatory-induced hypocapnia (and hence cerebral hypoperfusion) was prevented; and (2) that pharmacological reductions in cerebral blood flow (CBF) at baseline would lower the 'CBF reserve', and ultimately reduce OT. In study 1 (n = 24; aged 25 ± 4 years) participants underwent progressive lower-body negative pressure (LBNP) until pre-syncope; end-tidal carbon dioxide (P ET , CO 2) was clamped at baseline levels (isocapnic trial) or uncontrolled. In study 2 (n = 10; aged 25 ± 4 years), CBF was pharmacologically reduced by administration of indomethacin (INDO; 1.

Towards seasonal forecasting of malaria in India.

Background: Malaria presents public health challenge despite extensive intervention campaigns. A 30-year hindcast of the climatic suitability for malaria transmission in India is presented, using meteorological variables from a state of the art seasonal forecast model to drive a process-based, dynamic disease model.

Methods: The spatial distribution and seasonal cycles of temperature and precipitation from the forecast model are compared to three observationally-based meteorological datasets.

Vaccinia virus binds to the scavenger receptor MARCO on the surface of keratinocytes.

Patients with altered skin immunity, such as individuals with atopic dermatitis (AD), can have a life-threatening disruption of the epidermis known as eczema vaccinatum after vaccinia virus (VV) infection of the skin. Here, we sought to better understand the mechanism(s) by which VV associates with keratinocytes. The class A scavenger receptor known as MARCO (macrophage receptor with collagenous structure) is expressed on human and mouse keratinocytes and found to be abundantly expressed in the skin of patients with AD.

Search for gravitational waves associated with γ-ray bursts detected by the interplanetary network.

We present the results of a search for gravitational waves associated with 223 γ-ray bursts (GRBs) detected by the InterPlanetary Network (IPN) in 2005-2010 during LIGO's fifth and sixth science runs and Virgo's first, second, and third science runs. The IPN satellites provide accurate times of the bursts and sky localizations that vary significantly from degree scale to hundreds of square degrees. We search for both a well-modeled binary coalescence signal, the favored progenitor model for short GRBs, and for generic, unmodeled gravitational wave bursts.

Effects of elevated oxygen and carbon dioxide partial pressures on respiratory function and cognitive performance.

Hyperoxia during diving has been suggested to exacerbate hypercapnic narcosis and promote unconsciousness. We tested this hypothesis in male volunteers (12 at rest, 10 at 75 W cycle ergometer exercise) breathing each of four gases in a hyperbaric chamber. Inspired Po2 (PiO2 ) was 0.

PI3K and Bcl-2 inhibition primes glioblastoma cells to apoptosis through downregulation of Mcl-1 and Phospho-BAD.

Unlabelled: Glioblastoma multiforme (GBM) is a highly malignant human brain neoplasm with limited therapeutic options. GBMs display a deregulated apoptotic pathway with high levels of the antiapoptotic Bcl-2 family of proteins and overt activity of the phosphatidylinositol 3-kinase (PI3K) signaling pathway. Therefore, combined interference of the PI3K pathway and the Bcl-2 family of proteins is a reasonable therapeutic strategy.

Constraints on cosmic strings from the LIGO-Virgo gravitational-wave detectors.

Cosmic strings can give rise to a large variety of interesting astrophysical phenomena. Among them, powerful bursts of gravitational waves (GWs) produced by cusps are a promising observational signature. In this Letter we present a search for GWs from cosmic string cusps in data collected by the LIGO and Virgo gravitational wave detectors between 2005 and 2010, with over 625 days of live time.