Perturbations In Physiology Research Articles

Gut-Gonad Perturbations in Type-1 Diabetes Mellitus: Role of Dysbiosis, Oxidative Stress, Inflammation and Energy-Dysbalance.

Type 1 diabetes mellitus is a major metabolic disorder that affects people of all age groups throughout the world. It is responsible for the alterations in male gonadal physiology in experimental models as well as in clinical cases. On the other side, diabetes mellitus has also been associated with perturbations in the gut physiology and microbiota dysbiosis. The accumulating evidence suggests a link between the gut and gonad as evident from the i) experimental data providing insights into type 1 diabetes mellitus induced gut perturbations, ii) link of gut physiology with alterations of testicular health, iii) role of gut microbiota in androgen metabolism in the intestine, and iv) epidemiological evidence linking type 1 diabetes mellitus with inflammatory bowel disease and male infertility. Considering all the pieces of evidence, it is summarized that gut dysbiosis, oxidative stress, inflammation and energy dys-balance are the prime factors involved in the gonadal damage under type 1 diabetes mellitus, in which the gut contributes significantly. Identification of novel biomarkers and intervention of suitable agents targeting these prime factors may be a step forward to restore the gonadal damage in diabetic conditions.

Anthelmintic efficacy of febantel against a monogenean parasite, Gyrodactylus kobayashii

Monogenean parasites pose a significant challenge to aquaculture, leading to adverse effects on fish health and yields. Current anthelmintic treatments for monogeneans have demonstrated limited efficacy and are further complicated by potential issues, which emphasize the necessity for effective and safe therapeutic strategies to manage monogeneans in aquaculture. In this study, in vivo and in vitro anthelmintic activity of febantel against Gyrodactylus kobayashii on goldfish (Carassius auratus), as well as its toxicity to goldfish were evaluated. In vivo assays indicated that febantel exhibited potent anthelmintic activity against G. kobayashii with an EC50 value of 0.03 mg/L and 100 % anthelmintic efficacy at 0.1 mg/L after 48 h of exposure. Moreover, in vivo trials also revealed a notable post-treatment effect of febantel, where infected goldfish transferred to drug-free water after short 6-h exposure could still result in full eradication of the worms, indicating febantel might induce persistent perturbations in parasite physiology. In vitro assays showed a negative correlation between febantel concentrations and the survival of G. kobayashii. However, increasing the febantel concentration to 2.0 mg/L did not result in the complete death of all worms. Oral administration of febantel demonstrated limited anthelmintic activity, with only 49 % efficacy at a dosage of 200 mg/kg body weight daily over five days. Acute toxicity assays revealed the 48-h LC50 value of febantel was 5.47 mg/L, which was 182.23 times higher than the 48-h EC50 value, indicating that febantel has a favorable safety profile. However, febantel exposure potentially interfered with hepatic metabolism and oxidative status, as indicated by variations in SOD, GST, and P450 gene expression. In conclusion, treatment with 0.1 mg/L febantel for 24 h completely eradicated G. kobayashii infection on goldfish, demonstrating febantel’s potent anthelmintic activity. Coupled with its safety profile and extended post-treatment effectiveness, febantel is a promising candidate for controlling Gyrodactylus infections in aquaculture.

Breathlessness in a virtual world: An experimental paradigm testing how discrepancy between VR visual gradients and pedal resistance during stationary cycling affects breathlessness perception.

The sensation of breathlessness is often attributed to perturbations in cardio-pulmonary physiology, leading to changes in afferent signals. New evidence suggests that these signals are interpreted in the light of prior "expectations". A misalignment between afferent signals and expectations may underly unexplained breathlessness. Using a novel immersive virtual reality (VR) exercise paradigm, we investigated whether manipulating an individual's expectation of effort (determined by a virtual hill gradient) may alter their perception of breathlessness, independent from actual effort (the physical effort of cycling). Nineteen healthy volunteers completed a single experimental session where they exercised on a cycle ergometer while wearing a VR headset. We created an immersive virtual cycle ride where participants climbed up 100 m hills with virtual gradients of 4%, 6%, 8%, 10% and 12%. Each virtual hill gradient was completed twice: once with a 4% cycling ergometer resistance and once with a 6% resistance, allowing us to dissociate expected effort (virtual hill gradient) from actual effort (power). At the end of each hill, participants reported their perceived breathlessness. Linear mixed effects models were used to examine the independent contribution of actual effort and expected effort to ratings of breathlessness (0-10 scale). Expectation of effort (effect estimate ± std. error, 0.63 ± 0.11, P < 0.001) and actual effort (0.81 ± 0.21, P < 0.001) independently explained subjective ratings of breathlessness, with comparable contributions of 19% and 18%, respectively. Additionally, we found that effort expectation accounted for 6% of participants' power and was a significant, independent predictor (0.09 ± 0.03; P = 0.001). An individuals' expectation of effort is equally important for forming perceptions of breathlessness as the actual effort required to cycle. A new VR paradigm enables this to be experimentally studied and could be used to re-align breathlessness and enhance training programmes.

Critical role of the coronary microvasculature in heart disease: From pathologic driving force to “innocent” bystander

The coronary microvasculature is responsible for providing oxygen and nutrients to myocardial tissue. A healthy microvasculature with an intact and properly functioning endothelium accomplishes this by seemless changes in vascular tone to match supply and demand. Perturbations in the normal physiology of the microvasculature, including endothelial and/or vascular smooth muscle dysfunction, result in impaired function (vasoconstriction, antithrombotic, etc.) and structural (hypertrophic, fibrotic) abnormalities that lead to microvascular ischemia and potential organ damage. While coronary microvascular dysfunction (CMD) is the primary pathologic driving force in ischemia with non-obstructive coronary artery disease (INOCA), angina with no obstructive coronary arteries (ANOCA), and myocardial infarction with non-obstructed coronary arteries (MINOCA), it may be a bystander in many cardiac disorders which later become pathologically associated with signs and/or symptoms of myocardial ischemia. Importantly, regardless of the primary or secondary basis of CMD in the heart, it is associated with important increases in morbidity and mortality. In this review we discuss salient features pertaining to known pathophysiologic mechanisms driving CMD, the spectrum of heart diseases where it places a critical role, invasive and non-invasive diagnostic testing, management strategies, and the gaps in knowledge where future research efforts are needed.

A study on alterations in membrane physiology of human erythrocytes due to extracellular tonicity through dielectrophoresis

To get an insight into the physiological reality of biological cells it is necessary to obtain knowledge regarding their electrical make. It is in this view an attempt has been made to study the dielectric property of human erythrocytes suspended in solutions of different tonicity (Isotonic, Hypertonic, and Hypotonic) using the technique of Dielectrophoresis. This technique is concerned with the electrical constitution of the cell and is sensitive to small perturbations in cell physiology. In the present study, Erythrocytes suspended in different prepared solutions are subjected to Non- Uniform Electric Field produced by Pin-Pin Electrode configuration.

Developmental Manipulation-Induced Changes in Cognitive Functioning.

Schizophrenia is a complex neurodevelopmental disorder with as-yet no identified cause. The use of animals has been critical to teasing apart the potential individual and intersecting roles of genetic and environmental risk factors in the development of schizophrenia. One way to recreate in animals the cognitive impairments seen in people with schizophrenia is to disrupt the prenatal or neonatal environment of laboratory rodent offspring. This approach can result in congruent perturbations in brain physiology, learning, memory, attention, and sensorimotor domains. Experimental designs utilizing such animal models have led to a greatly improved understanding of the biological mechanisms that could underlie the etiology and symptomology of schizophrenia, although there is still more to be discovered. The implementation of the Research and Domain Criterion (RDoC) has been critical in taking a more comprehensive approach to determining neural mechanisms underlying abnormal behavior in people with schizophrenia through its transdiagnostic approach toward targeting mechanisms rather than focusing on symptoms. Here, we describe several neurodevelopmental animal models of schizophrenia using an RDoC perspective approach. The implementation of animal models, combined with an RDoC framework, will bolster schizophrenia research leading to more targeted and likely effective therapeutic interventions resulting in better patient outcomes.

Abstract 053: Urinary Extracellular Messenger RNA Transcripts as Biomarkers of Mineralocorticoid Receptor Activity

Objectives: Mineralocorticoid receptor (MR) activation regulates sodium homeostasis &amp; blood pressure. Our objective was to identify a non-invasive biomarker of MR activation in humans. Background: MR is a ligand-activated transcription factor that alters expression of target genes in the distal renal tubule, as shown in cell &amp; animal models. Renal tubular cells secrete extracellular vesicles which carry RNA into urine. Whether human urinary extracellular mRNA reflects changes in gene expression in the renal tubule &amp; thus might provide insight into MR activation is unknown. Methods: Pre-hypertensive participants consumed a low-sodium diet followed by sodium loading. We designed qPCR assays for MR gene targets &amp; control genes not expected to respond to MR activation. Using samples collected during low-sodium diet &amp; after sodium infusion, we assayed plasma renin activity (PRA), serum aldosterone, urinary sodium &amp; urinary MR-responsive &amp; control extracellular mRNA. Results: Eighteen participants’ low-sodium &amp; 17 participants’ sodium-loaded urine samples were available. PRA &amp; serum aldosterone were higher ( P &lt;0.001) &amp; urinary sodium excretion was lower ( P &lt;0.001) during low-sodium diet. Four of 14 target gene qPCR assays (29%) changed after sodium loading, including assays for SCNN1A , SCNN1G &amp; TSC22D3 ( P =0.006 to 0.01), whereas an assay for SGK1 approached significance ( P =0.07). In contrast, only 1 out of 10 control gene assays (for NR3C2 , encoding MR itself) was significantly different after sodium loading ( P =0.003). Log serum aldosterone inversely associated with C t values for 7 of 14 target gene assays (including assays for SCNN1A , SCNN1G , SGK1 &amp; TSC22D3 [r= -0.46 to -0.52, P =0.003 to 0.048]) &amp; for control gene assays for NR3C2 &amp; UMOD . C t values for 6 of 14 target gene qPCR assays associated with log urinary sodium/creatinine ratio including assays for SCNN1A , SCNN1G , SGK1 &amp; TSC22D3 associated with log urinary sodium/creatinine ratio ([r= 0.36 to 0.52, P =0.003 to 0.048]) but not with control gene assays. Conclusions: Perturbations in human endocrine physiology can be detected as changes in urinary extracellular mRNA. Our findings suggest a new strategy to screen for mineralocorticoid excess &amp; to assess pharmacologic or dietary changes in MR activity.

Extensive phenotypic characterization of a new transgenic mouse reveals pleiotropic perturbations in physiology due to mesenchymal hGH minigene expression

The human growth hormone (hGH) minigene used for transgene stabilization in mice has been recently identified to be locally expressed in the tissues where transgenes are active and associated with phenotypic alterations. Here we extend these findings by analyzing the effect of the hGH minigene in TgC6hp55 transgenic mice which express the human TNFR1 under the control of the mesenchymal cell-specific CollagenVI promoter. These mice displayed a fully penetrant phenotype characterized by growth enhancement accompanied by perturbations in metabolic, skeletal, histological and other physiological parameters. Notably, this phenotype was independent of TNF-TNFR1 signaling since the genetic ablation of either Tnf or Tradd did not rescue the phenotype. Further analyses showed that the hGH minigene was expressed in several tissues, also leading to increased hGH protein levels in the serum. Pharmacological blockade of GH signaling prevented the development of the phenotype. Our results indicate that the unplanned expression of the hGH minigene in CollagenVI expressing mesenchymal cells can lead through local and/or systemic mechanisms to enhanced somatic growth followed by a plethora of primary and/or secondary effects such as hyperphagia, hypermetabolism, disturbed glucose homeostasis, altered hematological parameters, increased bone formation and lipid accumulation in metabolically critical tissues.

Skeletal muscle inflammation and atrophy in heart failure.

Heart failure represents a systemic disease with profound effects on multiple peripheral tissues including skeletal muscle. Within the context of heart failure, perturbations in skeletal muscle physiology, structure, and function strongly contribute to exercise intolerance and the morbidity of this devastating disease. There is growing evidence that chronic heart failure imparts specific pathological changes within skeletal muscle beds resulting in muscle dysfunction and tissue atrophy. Mechanistically, systemic and local inflammatory responses drive critical aspects of this pathology. In this review, we will discuss pathological mechanisms that drive skeletal muscle inflammation and highlight emerging roles for distinct innate immune subsets that reside within damage muscle tissue focusing on the recently described embryonic and monocyte-derived macrophage lineages. Within this context, we will discuss how immune mechanisms can be differentially targeted to stimulate skeletal muscle inflammation, catabolism, fiber atrophy, and regeneration.

OP.7C.01] UROMODULIN-NACL INTERACTION ON MRNA EXPRESSION OF ION TRANSPORTERS IN ISOLATED TUBULES OF UMOD+/+ AND UMOD−/− MICE

Objective: UMOD−/− mice have low blood pressure and decreased salt-sensitivity indicating interactions between UMOD and sodium transport in the TAL. However, it's unclear whether the effect of UMOD is solely through interaction with cognate molecules in the TAL or whether the perturbations in physiology are more complex with involvement of both TAL and other parts of the nephron. We propose to answer this by profiling mRNA expression levels of the main ion transporters and signalling molecules in tubules from UMOD+/+ and UMOD−/− mice. Design and method: Male mice of 12 weeks of age were treated ±2% NaCl ad libitum in the drinking water for 6 weeks (n = 5 per group). Following the stimulation period mice were sacrificed, kidneys excised, and tubule isolations prepared for mRNA expression analysis utilising qRT-PCR. Results: The following transporters were differentially expressed in the UMOD−/− mice: Proximal convoluted tubule; NHE3 (down regulated during steady state and further attenuated during salt loading) and SLC26A4 (up regulated during steady state and remained unchanged during salt loading); Thick ascending limb/Distal convoluted tubule; NKCC2, ROMK, ClC-KB, Barttin, NCC, and NHE3, were all down regulated during steady state and further attenuated during salt loading, whereas SLC26A4, and Nedd4 were up regulated during steady state and remained unchanged during salt loading. TNFa was up regulated at steady state and further increased during salt loading; Macula densa; ACE2 and COX2 were up regulated during steady state and remained unchanged during salt loading, AT1 and A1AR were down regulated during steady state and remained unchanged with salt loading, and NOS1 was attenuated during steady state and remained down regulated during salt loading; finally, the Collecting ducts; SLC26A4 was up regulated during steady state and remained unchanged during salt loading and ENaC down regulated during steady state and remained unchanged with salt loading. Conclusions: This study demonstrates the impact of the absence of UMOD gene on renal transporter gene expression across the length of the nephron. Additionally, genes involved in tubuloglomerular feedback, revealing a key role of UMOD in sodium homeostasis which should lead to new therapies for hypertension by targeting this gene.

Update on Severe Burn Management for the Intensivist.

Thermal injury of humans causes arguably the most severe perturbations in physiology that can be experienced. These physiologic derangements start immediately and can persist in some form until months or even years after the burn wounds are healed. Burn shock, marked activation of the systemic inflammatory response, multiple-organ failure, infection, and wound failure are just a few of the insults that may require management by the intensivist. The purpose of this article is to review recent advances in the critical care management of thermally injured patients.

Underground Adaptation to a Hostile Environment: Acute Myeloid Leukemia vs. Natural Killer Cells.

Acute myeloid leukemia (AML) is a heterogeneous group of malignancies which incidence increases with age. The disease affects the differentiation of hematopoietic stem or precursor cells in the bone marrow and can be related to abnormal cytogenetic and/or specific mutational patterns. AML blasts can be sensitive to natural killer (NK) cell antitumor response. However, NK cells are frequently defective in AML patients leading to tumor escape. NK cell defects affect not only the expression of the activating NK receptors, including the natural cytotoxicity receptors, the NK group 2, member D, and the DNAX accessory molecule-1, but also cytotoxicity and IFN-γ release. Such perturbations in NK cell physiology could be related to the adaptation of the AML to the immune pressure and more generally to patient’s clinical features. Various mechanisms are potentially involved in the inhibition of NK-cell functions in AML, including defects in the normal lymphopoiesis, reduced expression of activating receptors through cell-to-cell contacts, and production of immunosuppressive soluble agents by leukemic blasts. Therefore, the continuous cross-talk between AML and NK cells participates to the leukemia immune escape and eventually to patient’s relapse. Methods to restore or stimulate NK cells seem to be attractive strategies to treat patients once the complete remission is achieved. Moreover, our capacity in stimulating the NK cell functions could lead to the development of preemptive strategies to eliminate leukemia-initiating cells before the emergence of the disease in elderly individuals presenting preleukemic mutations in hematopoietic stem cells.

Suspected vagal reflex bradycardia in a calf undergoing surgical resection of an infected urachus

A four-week-old Charolais heifer was referred for surgical treatment of an infected umbilicus. The heifer was sedated with intravenous xylazine, and an indwelling intravenous jugular cannula was placed. General anaesthesia...

Effects of Antibiotics on Bacterial Species Composition and Metabolic Activities in Chemostats Containing Defined Populations of Human Gut Microorganisms

The composition and metabolic activities of the human colonic microbiota are modulated by a number of external factors, including diet and antibiotic therapy. Changes in the structure and metabolism of the gut microbiota may have long-term consequences for host health. The large intestine harbors a complex microbial ecosystem comprising several hundreds of different bacterial species, which complicates investigations on intestinal physiology and ecology. To facilitate such studies, a highly simplified microbiota consisting of 14 anaerobic and facultatively anaerobic organisms (Bacteroides thetaiotaomicron, Bacteroides vulgatus, Bifidobacterium longum, Bifidobacterium infantis, Bifidobacterium pseudolongum, Bifidobacterium adolescentis, Clostridium butyricum, C. perfringens, C. bifermentans, C. innocuum, Escherichia coli, Enterococcus faecalis, Enterococcus faecium, Lactobacillus acidophilus) was used in this investigation. Ampicillin [9.2 μg (ml culture)(-1)] was added to two chemostats operated at different dilution rates (D; 0.10 h(-1) and 0.21 h(-1)), and metronidazole [76.9 μg (ml culture)(-1)] was added to a third vessel (D = 0.21 h(-1)). Perturbations in bacterial physiology and metabolism were sampled over a 48-h period. Lactobacillus acidophilus and C. bifermentans populations did not establish in the fermentors under the imposed growth conditions. Ampicillin resulted in substantial reductions in bacteroides and C. perfringens populations at both dilution rates. Metronidazole strongly affected bacteroides communities but had no effect on bifidobacterial communities. The bacteriostatic effect of ampicillin on bifidobacterial species was growth rate dependent. Several metabolic activities were affected by antibiotic addition, including fermentation product formation and enzyme synthesis. The growth of antibiotic-resistant bifidobacteria in the large bowel may enable them to occupy ecological niches left vacant after antibiotic administration, preventing colonization by pathogenic species.

A Diurnal Rhythm in Glucose Uptake in Brown Adipose Tissue Revealed by In Vivo PET‐FDG Imaging

Using a micro-PET/CT scanner, we have measured 18F-fluorodeoxyglucose uptake in interscapular brown adipose tissue (iBAT) in C57Bl/6 mice at intervals across a 24-hour light-dark cycle. Our data reveals a strong 24-hour profile of glucose uptake of iBAT, peaking at approximately 9 hours into the light phase of the 12 hour light, 12 hour dark day. BAT is increasingly gaining attention as being involved in metabolic phenotypes and obesity, where BAT, as observed by PET analysis, negatively correlates with obesity and age. Conversely, animals that show perturbations in circadian clocks, behavior and physiology show metabolic phenotypes. The observation of a 24-hour rhythm in glucose uptake in iBAT makes this tissue a candidate site of interaction between metabolic and circadian systems.

Rev-erbα and Rev-erbβ coordinately protect the circadian clock and normal metabolic function

The nuclear receptor Rev-erbα regulates circadian rhythm and metabolism, but its effects are modest and it has been considered to be a secondary regulator of the cell-autonomous clock. Here we report that depletion of Rev-erbα together with closely related Rev-erbβ has dramatic effects on the cell-autonomous clock as well as hepatic lipid metabolism. Mouse embryonic fibroblasts were rendered arrhythmic by depletion of both Rev-erbs. In mouse livers, Rev-erbβ mRNA and protein levels oscillate with a diurnal pattern similar to that of Rev-erbα, and both Rev-erbs are recruited to a remarkably similar set of binding sites across the genome, enriched near metabolic genes. Depletion of both Rev-erbs in liver synergistically derepresses several metabolic genes as well as genes that control the positive limb of the molecular clock. Moreover, deficiency of both Rev-erbs causes marked hepatic steatosis, in contrast to relatively subtle changes upon loss of either subtype alone. These findings establish the two Rev-erbs as major regulators of both clock function and metabolism, displaying a level of subtype collaboration that is unusual among nuclear receptors but common among core clock proteins, protecting the organism from major perturbations in circadian and metabolic physiology.

A Model of Oxidative Stress Management: Moderation of Carbohydrate Metabolizing Enzymes in SOD1-Null Drosophila melanogaster

The response to oxidative stress involves numerous genes and mutations in these genes often manifest in pleiotropic ways that presumably reflect perturbations in ROS-mediated physiology. The Drosophila melanogaster SOD1-null allele (cSODn108) is proposed to result in oxidative stress by preventing superoxide breakdown. In SOD1-null flies, oxidative stress management is thought to be reliant on the glutathione-dependent antioxidants that utilize NADPH to cycle between reduced and oxidized form. Previous studies suggest that SOD1-null Drosophila rely on lipid catabolism for energy rather than carbohydrate metabolism. We tested these connections by comparing the activity of carbohydrate metabolizing enzymes, lipid and triglyceride concentration, and steady state NADPH:NADP+ in SOD1-null and control transgenic rescue flies. We find a negative shift in the activity of carbohydrate metabolizing enzymes in SOD1-nulls and the NADP+-reducing enzymes were found to have significantly lower activity than the other enzymes assayed. Little evidence for the catabolism of lipids as preferential energy source was found, as the concentration of lipids and triglycerides were not significantly lower in SOD1-nulls compared with controls. Using a starvation assay to impact lipids and triglycerides, we found that lipids were indeed depleted in both genotypes when under starvation stress, suggesting that oxidative damage was not preventing the catabolism of lipids in SOD1-null flies. Remarkably, SOD1-nulls were also found to be relatively resistant to starvation. Age profiles of enzyme activity, triglyceride and lipid concentration indicates that the trends observed are consistent over the average lifespan of the SOD1-nulls. Based on our results, we propose a model of physiological response in which organisms under oxidative stress limit the production of ROS through the down-regulation of carbohydrate metabolism in order to moderate the products exiting the electron transport chain.

Simulation of differential drug pharmacokinetics under heat and exercise stress using a physiologically based pharmacokinetic modeling approach

Under extreme conditions of heat exposure and exercise stress, the human body undergoes major physiological changes. Perturbations in organ blood flows, gastrointestinal properties, and vascular physiology may impact the body's ability to absorb, distribute, and eliminate drugs. Clinical studies on the effect of these stressors on drug pharmacokinetics demonstrate that the likelihood of pharmacokinetic alteration is dependent on drug properties and the intensity of the stressor. The objectives of this study were to use literature data to quantify the correlation between exercise and heat exposure intensity to changing physiological parameters and further, to use this information for the parameterization of a whole-body, physiologically based pharmacokinetic model for the purposes of determining those drug properties most likely to demonstrate altered drug pharmacokinetics under stress. Cardiac output and most organ blood flows were correlated with heart rate using regression analysis. Other altered parameters included hematocrit and intravascular albumin concentration. Pharmacokinetic simulations of intravenous and oral administration of hypothetical drugs with either a low or high value of lipophilicity, unbound fraction in plasma, and unbound intrinsic hepatic clearance demonstrated that the area under the curve of those drugs with a high unbound intrinsic clearance was most affected (up to a 130% increase) following intravenous administration, whereas following oral administration, pharmacokinetic changes were smaller (<40% increase in area under the curve) for all hypothetical compounds. A midazolam physiologically based pharmacokinetic model was also used to demonstrate that simulated changes in pharmacokinetic parameters under exercise and heat stress were generally consistent with those reported in the literature.

Therapeutic hypothermia is associated with a decrease in urine output in acute stroke patients

Aims It is unclear what effect therapeutic hypothermia may have on renal function, because its effect has so far been primarily evaluated in settings in which there may be possible confounding perturbations in cardiovascular and renal physiology, such deep intraoperative hypothermia, general anesthesia, and post-cardiac arrest. We sought to determine if therapeutic hypothermia affects renal function in awake patients with normal renal function who were enrolled into a clinical trial of hypothermia plus intravenous thrombolysis for acute ischemic stroke. Methods Eleven patients with normal renal function were cooled to 33 °C for 24 h using an endovascular catheter, and then re-warmed over 12 h to 36.5 °C, while hourly temperature, blood pressure, and fluid status data was recorded. Blood samples for blood urea nitrogen (BUN), creatinine, and hematocrit were drawn prior to treatment (baseline), immediately after hypothermia and re-warming (day 2), and again at day 7 or discharge, and values compared. Results On initiation of cooling, temperatures dropped from a median pre-treatment value of 36.1 °C (IQR: 35.8–36.4 °C) to 33.1 °C (IQR: 33.1–33.4 °C). Urine output decreased 5.1 ml/h for every 1 °C decrease in body temperature ( p-value = 0.001), with no associated serious adverse events. There were no statistically significant changes in BUN, creatinine, or hematocrit in the hypothermia patients. Conclusion Inducing hypothermia in patients with relatively unperturbed renal physiology results in a decrease in urine output that is linearly correlated with the decrease in core temperature. This has important implications for fluid management in patients undergoing therapeutic hypothermia.

A Role for the Transcriptional Coactivator PRC1 in Mitochondrial Biogenesis During Erythroid Development.

Abstract 3642Poster Board III-578Red cell development requires unparalleled mitochondrial metabolic and biosynthetic capacities to support hemoglobin formation. In addition to meeting the energetic requirements of the erythroblast and reticulocyte, mitochondria are the site of multiple steps in heme biosynthesis and are essential for iron utilization. As such, perturbation of mitochondrial function in hematopoietic cells appears to differentially affect red cell development. For instance, we show that the drug chloramphenicol (an inhibitor of mitochondrial protein synthesis) preferentially inhibits erythroid colony formation with relatively little effect on other types of myeloid progenitors. Similarly, we show that knockout of the mitochondrial superoxide dismutase (Sod2) preferentially inhibits BFU-E, CFU-E and GEMM colonies. Clinically, several mutations in mitochondrial DNA or in nuclear encoded mitochondria-localized proteins preferentially disrupt erythroid development resulting in sideroblastic anemia. In order to better understand regulation of mitochondrial activity during red cell development/differentiation, we have investigated expression of transcription factors and coactivators implicated as regulators of mitochondrial biogenesis in other tissues including PGC-1 α and β, ERR proteins, NRF 1 and NRF 2 in normal and Sod2 deficient murine erythroblasts. Microarray and qPCR data suggest that neither of the classic transcriptional coactivators PGC-1 α or β are expressed at appreciable levels in erythroblasts. However, a PGC-1 related coactivator, PRC1 is detectable at both the transcript and protein level in developing erythroid cells. In the Sod2 deficiency model, one of the most prominent transcriptional changes we have observed in erythroblasts is a broad down regulation of expression of nuclear encoded mitochondria localized protein transcripts including multiple components of the electron transport chain, TCA cycle enzymes and mitochondrial ribosomal proteins. We show that PRC1 expression is down regulated in Sod2 deficient cells—suggesting that this coactivator plays a key role in mitochondrial biogenesis during erythroid development. Further, using the MEL cell line, we show that PRC1 expression is turned on following induction of differentiation with DMSO. These results identify PRC1 as a novel, and perhaps exclusive regulator of mitochondrial biogenesis during erythroid development. A better understanding of regulation of PRC1 expression and identification of transcriptional targets of PRC1 during erythroid development will improve our understanding of how perturbations in mitochondrial physiology affect the red cell compartment. Disclosures:No relevant conflicts of interest to declare.