Molecular biomarkers for assessing the heat-adapted phenotype: a narrative scoping review.

Heat acclimation/acclimatisation (HA) mitigates heat-related decrements in physical capacity and heat-illness risk and is a widely advocated countermeasure for individuals operating in hot environments. The efficacy of HA is typically quantified by assessing the thermo-physiological responses to a standard heat acclimation state test (i.e. physiological biomarkers), but this can be logistically challenging, time consuming, and expensive. A valid molecular biomarker of HA would enable evaluation of the heat-adapted state through the sampling and assessment of a biological medium. This narrative review examines candidate molecular biomarkers of HA, highlighting the poor sensitivity and specificity of these candidates and identifying the current lack of a single 'standout' biomarker. It concludes by considering the potential of multivariable approaches that provide information about a range of physiological systems, identifying a number of challenges that must be overcome to develop a valid molecular biomarker of the heat-adapted state, and highlighting future research opportunities.

Inkjet printing infiltration of Ni-Gd:CeO2 anodes for low temperature solid oxide fuel cells.

ABSTRACT: The effect of inkjet printing infiltration of Gd0.1Ce0.9O2-x in NiO-Gd0.1Ce0.9O2-x anodes on the performance of symmetrical and button cells was investigated. The anodes were fabricated by inkjet printing of suspension and sol inks. Symmetrical cells were produced from composite suspension inks on Gd0.1Ce0.9O2-x electrolyte. As-prepared scaffolds were infiltrated with Gd0.1Ce0.9O2 ink. Increasing the number of infiltration steps led to formation of "nano-decoration" on pre-sintered anodes. High resolution SEM analysis was employed for micro-structural characterization revealing formation of fine anode sub-structure with nanoparticle size varying in the range of 50-200 nm. EIS tests were conducted on symmetrical cells in 4% hydrogen/argon gas flow. The measurements showed substantial reduction of the activation polarization as a function of the number of infiltrations. The effect was assigned to the extension of the triple phase boundary. The i-V testing of a reference (NiO-8 mol% Y2O3 stabilized ZrO2/NiO-Gd0.1Ce0.9O2-x /Gd0.1Ce0.9O2-x /Gd0.1Ce0.9O2-x -La0.6Sr0.4Co0.2Fe0.8O3-δ ) cell and an identical cell with infiltrated anode revealed ~2.5 times improvement in the maximum output power at 600 °C which corresponded with the reduction of the polarization resistance of the symmetrical cells at the same temperature (2.8 times). This study demonstrated the potential of inkjet printing technology as an infiltration tool for cost effective commercial SOFC processing.

Infiltration of commercially available, anode supported SOFC's via inkjet printing.

Commercially available anode supported solid oxide fuel cells (NiO-8YSZ/8YSZ/LSCF- 20 mm in diameter) were anode infiltrated with gadolinium doped ceria (CGO) using a scalable drop-on-demand inkjet printing process. Cells were infiltrated with two different precursor solutions-water based or propionic acid based. The saturation limit of the 0.5 µm thick anode supports sintered at 1400 °C was found to be approximately 1wt%. No significant enhancement in power output was recorded at practical voltage levels. Microstructural characterisation was carried out after electrochemical performance testing using high resolution scanning electron microscopy. This work demonstrates that despite the feasibility of achieving CGO nanoparticle infiltration into thick, commercial SOFC anodes with a simple, low-cost and industrially scalable procedure other loss mechanisms were dominant. Infiltration of model symmetric anode cells with the propionic acid based ink demonstrated that significant reductions in polarisation resistance were possible.

Pearson syndrome: unique endocrine manifestations including neonatal diabetes and adrenal insufficiency.

PURPOSE: Pearson syndrome is a very rare metabolic disorder that is usually present in infancy with transfusion dependent macrocytic anemia and multiorgan involvement including exocrine pancreas, liver and renal tubular defects. The disease is secondary to a mitochondrial DNA deletion that is variable in size and location. Endocrine abnormalities can develop, but are usually not part of the initial presentation. We report two patients who presented with unusual endocrine manifestations, neonatal diabetes and adrenal insufficiency, who were both later diagnosed with Pearson syndrome. METHODS: Medical records were reviewed. Confirmatory testing included: mitochondrial DNA deletion testing and sequencing of the breakpoints, muscle biopsy, and bone marrow studies. RESULTS: Case 1 presented with hyperglycemia requiring insulin at birth. She had several episodes of ketoacidosis triggered by stress and labile blood glucose control. Workup for genetic causes of neonatal diabetes was negative. She had transfusion dependent anemia and died at 24 months due to multisystem organ failure. Case 2 presented with adrenal insufficiency and anemia during inturcurrent illness, requiring steroid replacement since 37 months of age. He is currently 4 years old and has mild anemia. Mitochondrial DNA studies confirmed a 4.9 kb deletion in patient 1 and a 5.1 kb deletion in patient 2. CONCLUSION: The patients reported highlight the importance of considering mitochondrial DNA disorders in patients with early onset endocrine dysfunction, and expand the knowledge about this rare mitochondrial disease.

Periodic cardiovascular and ventilatory activity during midazolam sedation.

We have examined the effects of sedation with midazolam 0.1 mg kg-1 and reversal with flumazenil 0.5 mg on beat-to-beat heart rate (HR) variability (HRV), systolic arterial pressure (SAP), finger photoplethysmograph amplitude (PLA) and impedence pneumography in eight volunteers. With the onset of sedation there was a small decrease in SAP and increase in HR (ns). Spectral analysis of the HR time series showed reductions in the proportion of power in the high (> 0.15 Hz) frequency "ventilatory" band consistent with midazolam causing vagolysis. During sedation, low frequency (< 0.05 Hz) oscillations of PLA, HR, SAP and ventilation were observed. These were thought to be secondary to activity of coupled cardiorespiratory neurones within the brain stem and the ventilatory periodicity appeared similar to that observed during the early stages of sleep. The diminished high frequency and increased low frequency oscillations induced by midazolam sedation were reversed by administration of flumazenil.

Ozone uptake in awake Sprague-Dawley rats.

Knowledge of ozone (O3) uptake in rats in integral to efforts to quantitatively extrapolate animal data to man. We have measured percentage O3 uptake in 30 adult Sprague-Dawley rats exposed, nose only, for 1 hr to 0.3, 0.6, or 1.0 ppm O3. Tidal volume and breathing rate measurements, obtained by plethysmography, were time-matched with changes in airstream concentrations of O3, oxygen, and carbon dioxide, due to animal breathing, for computation of O3 uptake and respiratory gas exchange values. Ozone uptake was calculated by a fractional deposition technique, i.e. O3 in vs O3 out. Total respiratory system O3 uptake was found to be approximately 40% of that inspired and did not vary with O3 concentration nor during the 1-hr exposure. The quantity of O3 inhaled and retained by the rat increased proportionally with O3 concentration.

Laboratory and clinical evaluation of a new volume ventilator.

A three phase laboratory and clinical evaluation of a new fluidically controlled volume ventilator (Ohio 550) was undertaken to determine if this more compact, less complex and less costly unit retained the multiple advantages which have been established for volume ventilators in the continuous ventilatory support of patients in respiratory failure. Inspired volume, peak pressure, and flow rates were continuously monitored while a "test lung" was ventilated with its "effective compliance" reduced, and ambulatory patients with varying degrees of obstructive and restrictive ventilatory impairment were ventilated with the 550 respirator. Since adequate tidal and minute volumes were achieved under these conditions of markedly altered breathing mechanics, ten patients in acute respiratory failure requiring mechanical ventilation were managed with the 550 respirator. Aside from the absence of a sighing device, not considered by the authors to be a major disadvantage, the mechanical characteristics, inspired oxygen control and alarm systems were judged satisfactory and compared favorably with the volume ventilators currently available. The fluidic control system is expected to enhance the reliability and minimize the maintenance required of this respirator.