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.

Adult and elderly population access to trauma centers: an ecological analysis evaluating the relationship between injury-related mortality and geographic proximity in the United States in 2010.

Background: Ongoing development and expansion of trauma centers in the United States necessitates empirical analysis of the effect of investment in such resources on population-level health outcomes. Methods: Multiple linear regressions were performed to predict state-level trauma-related mortality among adults and the elderly across 50 US states in 2010. The number of trauma centers per capita in each state and the percentage of each state's population living within 45-min of a trauma center served as the key independent variables and injury-related mortality served as the dependent variable. All analyses were stratified by age (adult versus elderly; elderly ≥ 65 years old) and were performed in SPSS. Results: The proportion of a population with geographic proximity to a trauma center demonstrates a consistent inverse linear relationship to injury-related mortality. The relationship reliably retains its significance in models including demographic covariates. Interestingly, access to Levels I and II trauma centers demonstrates a stronger correlation with mortality than was observed with Level III centers. Conclusion: Trauma center access is associated with reduced trauma-related mortality among both adults and the elderly as measured by state reported mortality rates. Ongoing efforts to designate and verify new trauma centers, particularly in poorly-served 'trauma deserts', could lead to lower mortality for large populations.

Erosion of Transplantation Tolerance After Infection.

Recent clinical studies suggest that operational allograft tolerance can be persistent, but long-term surviving allografts can be rejected in a subset of patients, sometimes after episodes of infection. In this study, we examined the impact of Listeria monocytogenes (Lm) infection on the quality of tolerance in a mouse model of heart allograft transplantation. Lm infection induced full rejection in 40% of tolerant recipients, with the remaining experiencing a rejection crisis or no palpable change in their allografts. In the surviving allografts on day 8 postinfection, graft-infiltrating cell numbers increased and exhibited a loss in the tolerance gene signature. By day 30 postinfection, the tolerance signature was broadly restored, but with a discernible reduction in the expression of a subset of 234 genes that marked tolerance and was down-regulated at day 8 post-Lm infection. We further demonstrated that the tolerant state after Lm infection was functionally eroded, as rejection of the long-term surviving graft was induced with anti-PD-L1 whereas the same treatment had no effect in noninfected tolerant mice. Collectively, these observations demonstrate that tolerance, even if initially robust, exists as a continuum that can be eroded following bystander immune responses that accompany certain infections.

Delayed Cytotoxic T Lymphocyte-Associated Protein 4-Immunoglobulin Treatment Reverses Ongoing Alloantibody Responses and Rescues Allografts From Acute Rejection.

Antibody-mediated rejection has emerged as the leading cause of late graft loss in kidney transplant recipients, and inhibition of donor-specific antibody production should lead to improved transplant outcomes. The fusion protein cytotoxic T lymphocyte-associated protein 4-immunoglobulin (CTLA4-Ig) blocks T cell activation and consequently inhibits T-dependent B cell antibody production, and the current paradigm is that CTLA4-Ig is effective with naïve T cells and less so with activated or memory T cells. In this study, we used a mouse model of allosensitization to investigate the efficacy of continuous CTLA4-Ig treatment, initiated 7 or 14 days after sensitization, for inhibiting ongoing allospecific B cell responses. Delayed treatment with CTLA4-Ig collapsed the allospecific germinal center B cell response and inhibited alloantibody production. Using adoptively transferred T cell receptor transgenic T cells and a novel approach to track endogenous graft-specific T cells, we demonstrate that delayed CTLA4-Ig minimally inhibited graft-specific CD4(+) and T follicular helper responses. Remarkably, delaying CTLA4-Ig until day 6 after transplantation in a fully mismatched heart transplant model inhibited alloantibody production and prevented acute rejection, whereas transferred hyperimmune sera reversed the effects of delayed CTLA4-Ig. Collectively, our studies revealed the unexpected efficacy of CTLA4-Ig for inhibiting ongoing B cell responses even when the graft-specific T cell response was robustly established.

Regulation of ACh release from guinea pig bladder urothelial cells: potential role in bladder filling sensations.

BACKGROUND AND PURPOSE: The aim of this study was to quantify and characterize the mechanism of non-neuronal ACh release from bladder urothelial cells and to determine if urothelial cells could be a site of action of anti-muscarinic drugs. EXPERIMENTAL APPROACH: A novel technique was developed whereby ACh could be measured from freshly isolated guinea pig urothelial cells in suspension following mechanical stimulation. Various agents were used to manipulate possible ACh release pathways in turn and to study the effects of muscarinic receptor activation and inhibition on urothelial ATP release. KEY RESULTS: Minimal mechanical stimulus achieved full ACh release, indicating a small dynamic range and possible all-or-none signal. ACh release involved a mechanism dependent on the anion channel CFTR and intracellular calcium concentration, but was independent of extracellular calcium, vesicular trafficking, connexins or pannexins, organic cation transporters and was not affected by botulinum-A toxin. Stimulating ACh receptors increased ATP production and antagonizing them reduced ATP release, suggesting a link between ACh and ATP release. CONCLUSIONS AND IMPLICATIONS: These results suggest that release of non-neuronal ACh from the urothelium is large enough and well located to act as a modulator of ATP release. It is hypothesized that this pathway may contribute to the actions of anti-muscarinic drugs in reducing the symptoms of lower urinary tract syndromes. Additionally the involvement of CFTR in ACh release suggests an exciting new direction for the treatment of these conditions.

Modulation of spontaneous activity in the overactive bladder: the role of P2Y agonists.

Spinal cord transection (SCT) leads to an increase in spontaneous contractile activity in the isolated bladder that is reminiscent of an overactive bladder syndrome in patients with similar damage to the central nervous system. An increase in interstitial cell number in the suburothelial space between the urothelium and detrusor smooth muscle layer occurs in SCT bladders, and these cells elicit excitatory responses to purines and pyrimidines such as ATP, ADP, and UTP. We have investigated the hypothesis that these agents underlie the increase in spontaneous activity. Rats underwent lower thoracic spinal cord transection, and their bladder sheets or strips, with intact mucosa except where specified, were used for experiments. Isometric tension was recorded and propagating Ca(2+) and membrane potential (E(m)) waves were recorded by fluorescence imaging using photodiode arrays. SCT bladders were associated with regular spontaneous contractions (2.9 ± 0.4/min); ADP, UTP, and UDP augmented the amplitude but not their frequency. With strips from such bladders, a P2Y(6)-selective agonist (PSB0474) exerted similar effects. Fluorescence imaging of bladder sheets showed that ADP or UTP increased the conduction velocity of Ca(2+)/E(m) waves that were confined to regions of the bladder wall with an intact mucosa. When transverse bladder sections were used, Ca(2+)/E(m) waves originated in the suburothelial space and propagated to the detrusor and urothelium. Analysis of wave propagation showed that the suburothelial space exhibited properties of an electrical syncitium. These experiments are consistent with the hypothesis that P2Y-receptor agonists increase spontaneous contractile activity by augmenting functional activity of the cellular syncitium in the suburothelial space.

Neuronal-derived nitric oxide modulates the activity of mouse detrusor smooth muscle.

AIMS: We investigated the roles of neuronal-derived nitric oxide (NO) in the modulation of spontaneous activity of mouse detrusor smooth muscle. METHODS: Detrusor smooth muscle strips were isolated from nNOS gene knock-out (nNOS(-/-) ) mice and their wild type siblings (nNOS(+/+) ). The properties of smooth muscle cells were assessed using intracellular electrophysiology and Ca(2+) imaging by laser-scanning confocal microscopy. The effects of an nNOS inhibitor, 7-nitro indazole (7-NI) on electrically evoked contractility were assessed using nNOS(+/+) mouse detrusor strips. RESULTS: In spontaneously active cells, the frequency of spontaneous action potentials (sAPs) and whole cell Ca(2+) flashes in nNOS(-/-) preparations was lower than that in the nNOS(+/+) preparations. The frequency of sAPs was enhanced by a nitric oxide donor, diethylamine NONOate sodium salt (NONOate; 100 µM), both when used alone and when the cGMP pathway was blocked by 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ, 10 µM). 7-NI (100 µM) significantly suppressed the electrically evoked contraction of mouse detrusor strips. CONCLUSIONS: We suggest that neuronal-derived NO facilitates the generation of spontaneous activity via a cGMP-independent pathway, and consequently enhances the evoked contraction of detrusor. Dysregulation of nNOS containing nerves may underlie bladder pathologies.

Prostaglandin E2 induces spontaneous rhythmic activity in mouse urinary bladder independently of efferent nerves.

BACKGROUND AND PURPOSE: The acute effects of PGE(2) on bladder smooth muscle and nerves were examined to determine the origin of PGE(2)-induced spontaneous rhythmic contractions. EXPERIMENTAL APPROACH: Contraction studies, confocal Ca(2+) imaging and electrophysiological recordings in strips of mouse urinary bladder were used to differentiate the effects of PGE(2) on bladder smooth muscle and efferent nerves. KEY RESULTS: PGE(2) (50 µM) increased the tone and caused phasic contractions of detrusor smooth muscle strips. Confocal Ca(2+) imaging showed that PGE(2) increased the frequency of whole-cell Ca(2+) transients (WCTs) (72 ± 5%) and intracellular recordings showed it increased the frequency of spontaneous depolarizations, from 0.31·s(-1) to 0.90·s(-1). Non-selective inhibition of EP receptors using SC-51322 and AH-6809 (10 µM), or the L-type Ca(2+) channel blocker nifedipine (1 µM), prevented these phasic contractions and WCTs, and reduced the tone (by 45 ± 7% and 59 ± 6%, respectively). Blocking P2X1 receptors with NF449 (10 µM) caused a small but significant reduction in the frequency of PGE(2)-induced phasic contractions (24 ± 9%) and WCTs (28 ± 17%) but had no significant effect on spontaneous depolarizations or tone. Inhibiting muscarinic receptors with cyclopentolate (1 µM) had no significant effect on these measures. Spontaneous WCTs became synchronous in PGE(2), implying enhanced functional coupling between neighbouring cells. However, the electrical input resistance was unchanged. CONCLUSIONS AND IMPLICATIONS: It was concluded that depolarization alone is sufficient to explain a functional increase in intercellular coupling and the ability of PGE(2) to increase detrusor spontaneous rhythmic activity does not require parasympathetic nerves.

The physiological function of lower urinary tract smooth muscle.

The lower urinary tract is a muscular system composed of the urinary bladder and the outflow tract. During filling with urine the bladder is relaxed and the outflow tract offers a high resistance; during emptying the outflow resistance falls and the bladder wall generates a high wall tension to raise intravesical pressure. The coordination of these responses is organized in the brainstem and sacral spinal cord to control the activity of autonomic and somatic efferents to the smooth muscle of the bladder (detrusor) and the smooth and skeletal muscle of the bladder base and urethra. Detrusor contraction is predominantly controlled by parasympathetic fibres releasing acetylcholine and ATP; the outflow tract is controlled by parasympathetic and sympathetic fibres to the bladder base (trigone) and urethral smooth muscle (including a nitregic component) and somatic fibres to the urethral rhabdosphincter. The smooth muscles also develop spontaneous contractions that determine the tone of the musculature. The cellular signaling pathways that evoke contraction due to neurotransmitter release and the origin of spontaneous activity are discussed, as well as the electrical properties of the smooth muscle relevant to the propagation of electrical signals. Finally the interaction of muscle cells with other cell types (epithelium and interstitial cells) is considered, relevant to their ability to regulate muscle contractility. Throughout, the basic physiological processes are considered in relation to pathological developments that are prevalent in the human lower urinary tract, in particular the overactive bladder and urinary incontinence, and the identification of drug targets to manage these conditions.

Electrical and optical study of nerve impulse-evoked ATP-induced, P2X-receptor-mediated sympathetic neurotransmission at single smooth muscle cells in mouse isolated VAS deferens.

Simultaneous electrophysiology and confocal microscopy were used to investigate purinergic neurotransmission at single smooth muscle cells (SMCs) in mouse isolated vas deferens, and to explore the relationship between two high-resolution P2X-receptor-mediated measures of per pulse ATP release: transient peaks in the first time derivative of the rising phase of excitatory junction potentials (EJPs) recorded in single SMCs ('discrete events'; DEs) and neuroeffector Ca(2+) transients (NCTs) in the impaled SMCs. This study shows that discrete events represent neurotransmitter release onto the impaled cell. First, the median amplitude of the first derivative of the EJP was larger when there was a coincident NCT in the impaled cell, compared with instances when no coincident NCT occurred. Second, the time-to-peak amplitude of the first derivative was shorter if there was a coincident NCT in the impaled cell, compared with when no coincident NCT was observed within the field. Surprisingly, first derivative amplitude increased with the distance (of the corresponding NCT) from the microelectrode. The microelectrode did not locally inhibit the functional quantal size as there was no effect of distance on the normalized NCT amplitude. When the significant effect of distance (between the microelectrode and NCTs) on the first derivative amplitude was removed, there was no correlation between the unstandardized residual (of distance vs. first derivative amplitude) and NCT amplitude. The absence of a correlation between DE and NCT amplitudes suggests that the NCT amplitude is a poor measure of quantal size. The usefulness of NCTs hence lies primarily in locating neurotransmitter release and measuring changes in local release probability.

The origin of the skewed amplitude distribution of spontaneous excitatory junction potentials in poorly coupled smooth muscle cells.

The skewed amplitude distribution of spontaneous excitatory junction potentials (sEJPs) in the mouse vas deferens and other electrically-coupled smooth muscle syncytia has been attributed to electrically-attenuated depolarizations resulting from the spontaneous release of quantized packets of ATP acting on remote smooth muscle cells (SMCs). However, in the present investigation surface SMCs of the mouse isolated vas deferens were poorly electrically coupled, with input resistances (176+/-18 MOmega, range: 141-221 MOmega, n=4) similar to those of dissociated cells. Furthermore, the amplitude of evoked EJPs was more variable in surface compared with deeper SMCs (F test, F=17.4, P<0.0001). Using simultaneous electrophysiology and confocal microscopy to investigate these poorly-coupled cells, it is shown that alpha-latrotoxin-stimulated sEJPs correlate, in timing (median delay ranged from -30 to -57 ms, P<0.05 in all experiments, n=5) and amplitude (Pearson product moment correlation, rho>0.55 and P<0.001), with purinergic neuroeffector Ca2+ transients (NCTs) in SMCs. The temporal correlation between sEJPs of widely ranging amplitude with NCTs in the impaled SMC demonstrates that all sEJPs could arise from neurotransmitter action on the impaled cell and that the skewed distribution of sEJPs can be explained by the variable effect of packets of ATP on a single SMC. The amplitude correlation of sEJPs and NCTs argues against the attenuation of electrical signal amplitude along the length of a single SMC. The skewed sEJP amplitude distribution arising from neurotransmitter release on single SMCs is consistent with a broad neurotransmitter packet size distribution at sympathetic neuroeffector junctions.

Changes in TRPC channel expression during postnatal development of cerebellar neurons.

In the brain, classical (canonical) transient receptor potential (TRPC) channels are thought to be involved in different aspects of neuronal development. We investigated the developmental expression profile of TRPC channels in rat cerebellum during the first 6 weeks after birth. TRPC3 expression is significantly up-regulated whereas TRPC4 and TRPC6 expression are significantly down-regulated over this period of time. TRPC3 expression is mainly found on Purkinje cells and their dendrites, suggesting that the increase in TRPC3 expression reflects development of the dendritic tree of Purkinje cells. TRPC4 expression was restricted to granule and their precursor cells. TRPC6 expression is found on Purkinje cell bodies, on mature granule cells in the internal granule cell layer (but not their precursors) and interneurons in the molecular layer. The decrease in TRPC4 expression suggests that it is required for proper granule cell development whereas the decrease in TRPC6 expression is presumably correlated with interneuron development. Moreover, we demonstrate the presence of functional TRPC channels on Purkinje cell dendrites that are activated following stimulation of metabotropic glutamate receptors. Our results reveal cell-specific expression patterns for different TRPC proteins and suggest that developmental changes in TRPC protein expression may be required for proper postnatal cerebellar development.

Pilot study of electrical stimulation on median nerve in comatose severe brain injured patients: 3-month outcome.

PRIMARY OBJECTIVE: To determine if electrical stimulation (ES) benefits (waking time, 3-month outcomes) treated coma patients. RESEARCH DESIGN: Double blind randomized-controlled study. METHODS AND PROCEDURES: Ten coma patients; six treatment and four controls, using the 'Respond Select' by EMPI. EXPERIMENTAL INTERVENTIONS: Treatment group received radial nerve ES applied in 300 ms intermittent pulses at 40 Hz, 15-20m A 8 hours a day up to 14 days of coma; control group received sham stimulation. MAIN OUTCOMES AND RESULTS: ES group emerged from coma mean 2 days earlier than controls, although this result was not statistically significant. At 3 months post-injury, there was no group difference in Glasgow Outcome Scale, although the ES group had improved function over controls as measured by the FIM/FAM (mean of 114 and 64.5, respectively, n.s.). CONCLUSIONS: These data show an interesting trend, although statistical power was limited in this small pilot study, suggesting the need for a larger trial.

The "July phenomenon" and the care of the severely injured patient: fact or fiction?

BACKGROUND: The "July phenomenon," a common belief in medical academia, refers to purported errors, inefficiency, and negative outcomes during the summertime transition of the house staff. We hypothesized that care in a trauma service is consistent throughout the year and that the July phenomenon therefore is a myth. METHODS: The records of adults admitted to a trauma service between July 1994 and September 1999 were evaluated. The care of and outcomes for patients admitted in July and August were compared with those of patients admitted in April and May. RESULTS: Nine hundred seventeen patients were evaluated over 5 years. Patients were well matched by the Injury Severity Score, the Glasgow Coma Score, by mechanism, and by survival probability. Patients admitted in the spring were significantly older, by a mean of 5.1 years. Length of stay and intensive care unit stay were similar. Emergency department times were similar, as were resuscitation times, infection rates, and hospital costs. The mortality of patients was similar between the 2 times. CONCLUSIONS: There was no evidence of an increase in negative outcomes early in the academic year compared with the end of the academic year. We believe that a systematic approach to the diagnosis, resuscitation, and treatment of trauma prevented a July phenomenon.

Outpatient laparoscopic cholecystectomy: patient outcomes after implementation of a clinical pathway.

OBJECTIVE: To determine the success of a clinical pathway for outpatient laparoscopic cholecystectomy (LC) in an academic health center, and to assess the impact of pathway implementation on same-day discharge rates, safety, patient satisfaction, and resource utilization. SUMMARY BACKGROUND DATA: Laparoscopic cholecystectomy is reported to be safe for patients and acceptable as an outpatient procedure. Whether this experience can be translated to an academic health center or larger hospital is uncertain. Clinical pathways guide the care of specific patient populations with the goal of enhancing patient care while optimizing resource utilization. The effectiveness of these pathways in achieving their goals is not well studied. METHODS: During a 12-month period beginning April 1, 1999, all patients eligible for an elective LC (n = 177) participated in a clinical pathway developed to transition LC to an outpatient procedure. These were compared with all patients undergoing elective LC (n = 208) in the 15 months immediately before pathway implementation. Successful same-day discharges, reasons for postoperative admission, readmission rates, complications, deaths, and patient satisfaction were compared. Average length of stay and total hospital costs were calculated and compared. RESULTS: After pathway implementation, the proportion of same-day discharges increased significantly, from 21% to 72%. Unplanned postoperative admissions decreased as experience with the pathway increased. Patient characteristics, need for readmission, complications, and deaths were not different between the groups. Patients surveyed were highly satisfied with their care. Resource utilization declined, resulting in more available inpatient beds and substantial cost savings. CONCLUSIONS: Implementation of a clinical pathway for outpatient LC was successful, safe, and satisfying for patients. Converting LC to an outpatient procedure resulted in a significant reduction in medical resource use, including a decreased length of stay and total cost of care.

Assessing aggregate and cumulative pesticide risks using a probabilistic model.

Determining aggregate and cumulative risks from exposures to pesticides presents a number of challenges. The analysis must capture the correlations in residues that occur from both additive and exclusionary processes in the use of pesticides. The analysis also requires a quantitative mechanism for evaluating risks associated with exposures to mixtures of pesticides. This paper presents an analysis of aggregate exposures and risks associated with exposures to a pesticide, Alpha, and the cumulative exposure to and risk from three pesticides, Alpha, Beta, and Gamma. The cumulative risks are evaluated by determining the systemic (absorbed) doses that result from inhalation, dermal, and oral exposures to the pesticides. A 'relative toxicity' model is used to evaluate cumulative risks. The assessment of cumulative exposure was performed using the LifeLine Version 1.0. The model simulates pesticide exposure using an individual-based approach where daily exposures are evaluated for each person, season, and location.

Nitrate-cancrinite precipitation on quartz sand in simulated Hanford tank solutions.

Caustic NaNO3 solutions containing dissolved Al were reacted with quartz sand at 89 degrees C to simulate possible reactions between leaked nuclear waste and primary subsurface minerals at the U.S. Department of Energy's Hanford site in Washington. Nitrate-cancrinite began to precipitate onto the quartz after 2-10 days, cementing the grains together. Estimates of the equilibrium constant for the precipitation reaction differ for solutions with 0.1 or 1.0 m OH- (log Keq = 30.4 +/- 0.8 and 36.2 +/- 0.6, respectively). The difference in solubility may be attributable to more perfect crystallinity (i.e., fewer stacking faults) in the higher-pH cancrinite structure. This is supported by electron micrographs of crystal morphology and measured rates of Na volatilization under an electron beam. Precipitate crystallinity may affect radionuclide mobility, because stacking faults in the cancrinite structure can diminish its zeolitic cation exchange properties. The precipitation rate near the onset of nucleation depends on the total Al and Si concentrations in solution. The evolution of experimental Si concentrations was modeled by considering the dependence of quartz dissolution rate on AI(OH)4- activity, cancrinite precipitation, and the reduction of reactive surface area of quartz due to coverage by cancrinite.

Relative effectiveness of kinetic analysis vs single point readings for classifying environmental samples based on community-level physiological profiles (CLPP).

The relative effectiveness of average-well-color-development-normalized single-point absorbance readings (AWCD) vs the kinetic parameters mu(m), lambda, A, and integral (AREA) of the modified Gompertz equation fit to the color development curve resulting from reduction of a redox sensitive dye from microbial respiration of 95 separate sole carbon sources in microplate wells was compared for a dilution series of rhizosphere samples from hydroponically grown wheat and potato ranging in inoculum densities of 1 x 10(4)-4 x 10(6) cells ml-1. Patterns generated with each parameter were analyzed using principal component analysis (PCA) and discriminant function analysis (DFA) to test relative resolving power. Samples of equivalent cell density (undiluted samples) were correctly classified by rhizosphere type for all parameters based on DFA analysis of the first five PC scores. Analysis of undiluted and 1:4 diluted samples resulted in misclassification of at least two of the wheat samples for all parameters except the AWCD normalized (0.50 abs. units) data, and analysis of undiluted, 1:4, and 1:16 diluted samples resulted in misclassification for all parameter types. Ordination of samples along the first principal component (PC) was correlated to inoculum density in analyses performed on all of the kinetic parameters, but no such influence was seen for AWCD-derived results. The carbon sources responsible for classification differed among the variable types with the exception of AREA and A, which were strongly correlated. These results indicate that the use of kinetic parameters for pattern analysis in CLPP may provide some additional information, but only if the influence of inoculum density is carefully considered.