Plasma Lactate Concentrations Research Articles

Endocrine data provide further evidence of physiologic derangement in sea turtles affected by the Deepwater Horizon oil spill

This study was conducted to characterize the adrenocortical and thyroid status of Kemp’s ridley sea turtles Lepidochelys kempii that were affected by the Deepwater Horizon oil spill. A plasma aldosterone assay was validated for L. kempii, and it was used along with previously validated assays for corticosterone and free thyroxine to assess hormone concentrations of 30 L. kempii that were hospitalized due to oil exposure, representing 2 severities of oiling (lightly or heavily oiled). Hormone concentrations were also assessed in relation to 8 clinical biochemical analytes. Analysis of paired samples indicated that oiled turtles had significantly higher initial aldosterone and corticosterone concentrations, which declined during convalescence (average 96 and 90% decrease, respectively). Thyroxine concentrations significantly increased between admission and convalescence (average 65% increase). Initial biochemical data indicated significantly higher plasma potassium, ionized magnesium, and lactate concentrations compared to convalescent values. Aldosterone concentrations were positively correlated with corticosterone, negatively correlated with free thyroxine, and variably correlated with several clinical biochemical analytes. Results of this study indicate that L. kempii had robust adrenocortical activity after oiling, capture, and transport to the hospital, regardless of the degree of oiling, resulting in very high plasma concentrations of aldosterone and corticosterone. This study also confirms that aldosterone can be reliably measured in sea turtle plasma samples, providing another diagnostic tool for the physiologic assessment of this Critically Endangered species.

Relationship between Neonatal Cerebral Fuels and Neurosensory Outcomes at 3 Years in Well Babies: Follow-Up of the Glucose in Well Babies (GLOW) Study

Plain Language SummaryIn the Glucose in Well babies and their later Neurodevelopment (GLOWiNg) study, we investigated whether the availability of brain fuels in healthy term babies during the first 5 days after birth was associated with their neurodevelopmental progress at 3 years of age. We had measured plasma glucose, lactate, and beta-hydroxybutyrate concentrations when the children were babies, as these are the most common brain fuels. We used the Ages and Stages questionnaire, which is completed by parents, to assess the child’s development in areas including communication, motor skills (fine and gross), and problem solving.We studied 64 families whose babies were part of the Glucose in Well Babies (GLOW) study in New Zealand. Using both structural equation modelling and linear regression, we found that even though many babies experienced episodes of low plasma glucose concentrations, there was no detectable relationship between these episodes and developmental progress at 3 years of age. We explored other factors, including glucose concentrations, total fuels available, and the duration of low glucose episodes, and found no significant associations. Our results suggest that in healthy term babies, episodes of low glucose concentrations in the first days after birth may be part of the normal metabolic transition after birth and may not have long-term implications for neurodevelopment. However, larger studies using different assessment tools are needed to confirm these findings.

Effects of restrictive fluid therapy on the time to resolution of hyperlactatemia in ICU patients with septic shock. A secondary post hoc analysis of the CLASSIC randomized trial.

The aim of this study was to examine the effects of intravenous (IV) fluid restriction on time to resolution of hyperlactatemia in septic shock. Hyperlactatemia in sepsis is associated with worse outcome. Sepsis guidelines suggest targeting lactate clearance to guide fluid therapy despite the complexity of hyperlactatemia and the potential harm of fluid overload. We conducted a post hoc analysis of serial plasma lactate concentrations in a sub-cohort of 777 patients from the international multicenter clinical CLASSIC trial (restriction of intravenous fluids in intensive care unit (ICU) patients with septic shock). Adult ICU patients with septic shock had been randomized to restrictive (n = 385) or standard (n = 392) intravenous fluid therapy. The primary outcome, time to resolution of hyperlactatemia, was analyzed with a competing-risks regression model. Death and discharge were competing outcomes, and administrative censoring was imposed 72 h after randomization if hyperlactatemia persisted. The regression analysis was adjusted for the same stratification variables and covariates as in the original CLASSIC trial analysis. The hazard ratios (HRs) for the cumulative probability of resolution of hyperlactatemia, in the restrictive vs the standard group, in the unadjusted analysis, with time split, were 0.94 (confidence interval (CI) 0.78-1.14) at day 1 and 1.21 (0.89-1.65) at day 2-3. The adjusted analyses were consistent with the unadjusted results. In this post hoc retrospective analysis of a multicenter randomized controlled trial (RCT), a restrictive intravenous fluid strategy did not seem to affect the time to resolution of hyperlactatemia in adult ICU patients with septic shock.

Clinical Relevance of Plasma Lactic Acid in the Onset and Prognosis of Sudden Deafness.

Sudden deafness poses a significant threat to patients' quality of life, yet effective indicators for evaluating its onset and prognosis remain elusive. The inner ear is primarily supplied by the labyrinthine artery, which lacks collateral circulation. Changes in coagulation function and hemorheology can cause spasm or thrombosis of the labyrinthine artery, leading to ischemia, hypoxia, and microcirculation disorders in the inner ear, ultimately resulting in sudden deafness. This retrospective study examined 196 patients with sudden deafness, utilizing the 2015 Chinese guideline for diagnosis and treatment classification. Coagulation system analysis used the STA-R Evolution automatic coagulation analyzer, measuring activated partial thromboplastin time (APTT), prothrombin time (PT), and fibrinogen (FIB). Plasma lactate concentration was determined using a Johnson and Johnson Fusion 5.1 model plasma lactate detector. Results of the study revealed a correlation between the degree of hearing loss and disease prognosis. Patients with higher grade hearing loss exhibited elevated plasma lactate levels upon admission compared with those with lower grade hearing loss. Importantly, elevated plasma lactate levels at admission served as predictive indicators for treatment outcomes. In addition, patients with ineffective treatment demonstrated a more coagulable blood state, as evidenced by the lower APTT (ineffective treatment: 31.47 ± 4.55 seconds, effective treatment: 35.17 ± 5.38 seconds) and PT on admission, but higher plasma FIB. In conclusion, plasma lactate levels upon admission hold promise as prognostic markers for sudden deafness treatment outcomes, providing valuable insights for clinical management.

Venous blood gas and lactate values in adult giraffe trained for voluntary jugular phlebotomy.

Blood gas analyses have previously been performed for giraffe under anesthesia and with physical restraint in a chute; however, reference values for giraffe that are trained to participate in venipuncture without chemical or physical restraint have not previously been described. Using a point-of-care blood gas and lactate analyzer and 20 giraffe trained for voluntary phlebotomy, values were determined for venous blood gasses and plasma lactate concentration. Ninety-five percent confidence in the mean values for venous pH (7.34-7.46), partial pressure of carbon dioxide (PCO2; 28.5-37.8 mmHg), partial pressure of oxygen (PO2; 56-102 mmHg), bicarbonate (HCO3 -; 18.9-21.0 mmol/L), base excess (BE; -6.0 to -3.6 mmol/L), total carbon dioxide (TCO2; 19.9-22.0 mmol/L), and lactate (0.32-0.56 mmol/L) were calculated. This is the first report on venous blood gas analysis values for giraffe without chemical or physical restraint. These data will provide a reference for clinical interpretation of venous blood gas and lactate values in giraffe and demonstrate some of the potential diagnostic benefits to training giraffe and other zoo species for voluntary medical procedures.

Influence of High-Intensity Interval Training on Neuroplasticity Markers in Post-Stroke Patients: Systematic Review.

Background: Exercise has shown beneficial effects on neuronal neuroplasticity; therefore, we want to analyze the influence of high-intensity interval training (HIIT) on neuroplasticity markers in post-stroke patients. Methods: A systematic review of RCTs including studies with stroke participants was conducted using the following databases (PubMed, LILACS, ProQuest, PEDro, Web of Science). Searches lasted till (20/11/2023). Studies that used a HIIT protocol as the main treatment or as a coadjutant treatment whose outcomes were neural plasticity markers were used and compared with other exercise protocols, controls or other kinds of treatment. Studies that included other neurological illnesses, comorbidities that interfere with stroke or patients unable to complete a HIIT protocol were excluded. HIIT protocol, methods to assess intensity, neuroplasticity markers (plasmatic and neurophysiological) and other types of assessments such as cognitive scales were extracted to make a narrative synthesis. Jadad and PEDro scales were used to assess bias. Results: Eight articles were included, one included lacunar stroke (less than 3 weeks) and the rest had chronic stroke. The results found here indicate that HIIT facilitates neuronal recovery in response to an ischemic injury. This type of training increases the plasma concentrations of lactate, BDNF and VEGF, which are neurotrophic and growth factors involved in neuroplasticity. HIIT also positively regulates other neurophysiological measurements that are directly associated with a better outcome in motor learning tasks. Conclusions: We conclude that HIIT improves post-stroke recovery by increasing neuroplasticity markers. However, a limited number of studies have been found indicating that future studies are needed that assess this effect and include the analysis of the number of intervals and their duration in order to maximize this effect.

Enrichment of medium-quality colostrum by adding colostrum replacer, combined or not with transition milk in the feeding of dairy calves

Fifty Holstein calves were allocated in randomized blocks and distributed in a 2 × 2 factorial arrangement; (A) two sources of Ig: (1) Control: bovine colostrum (25% Brix); (2) Enriched colostrum: mid-quality bovine colostrum (20% Brix) enriched with colostrum replacer to 25% Brix; and (B) two transition feeding diets: (1) Whole milk (WM): supply of 4 L/day of whole milk for 3 days after the colostrum feeding; and (2) Formulated transition milk (FTM): supply 4 L/day of whole milk enriched with 70 g/L of colostrum replacer for 3 days after the colostrum feeding. Blood samples were collected at 0, 24, 48, and 72 h of age to determine total serum protein (TSP), glucose, non-esterified fatty acids (NEFA), erythrocyte and leukocyte concentrations. IgG was measured at 48 h. During the preweaning period, calves received 6 L/day of whole milk. Blood samples were collected weekly to determine TSP, glucose, and lactate. The colostrum protocols were equally efficient for transfer of passive immunity with IgG concentration at 48 h ≥ 49.6 g/L. Colostrum or transition feeding program did not influence the erythrocyte and leukocyte concentrations. The TSP concentration measured until 72 h was higher for calves fed maternal colostrum. Calves fed milk in the transition period had higher glucose concentrations. Calves receiving bovine colostrum and FTM had higher glucose concentrations in the preweaning period, while the enriched colostrum decreased plasma lactate concentrations. In summary, enrichment of mid-quality colostrum is an alternative in situations of a shortage of high-quality colostrum; however, feeding 4 L/day of FTM only for 3 days after colostrum feeding does not show additional benefits.

85 Evaluation of a Saccharomyces cerevisiae fermentation product on performance, plasma metabolites, rumen parameters, and fecal pathogen shedding in feedlot steers

Abstract The objective of the experiment was to evaluate a commercial Saccharomyces cerevisiae fermentation product (SCFP; NaturSafe, Dimond V, Cedar Rapids, IA) on performance, plasma metabolites, rumen parameters, and fecal pathogen shedding in feedlot steers. Crossbred steers (n = 61; 271 ± 48.1 kg) were sourced from 3 different research units at Oklahoma State University and assigned to 1 of 3 experimental treatments in a randomized complete block design. Steers were group housed in pens equipped with an automated individual feed intake system. Treatments consisted of a negative control (CON), CON with tylosin phosphate (TYL; 9.9 mg · kg-1 of diet DM), or CON with SCFP (1.63 g · kg-1 of diet DM). Body weight and feed efficiency did not differ among treatments (P ≥ 0.12). However, steers fed SCFP tended to have greater ADG from d 35 to 56 (P = 0.10). In addition, steers fed SCFP exhibited increased DMI from d 56 to 112 (P = 0.03), a tendency for increased DMI from d 112 to final (P = 0.07), and increased DMI overall (P = 0.05). There was no treatment × time interaction for pH, pH change, or lactate concentrations in rumen fluid (P ≥ 0.11), but all were impacted by time (P < 0.01). A treatment × time interaction (P < 0.01) was detected for fecal pH and fecal pH change, with the pH being greater in TYL fed steers on d 56 and in CON fed steers on the final day. Steers that consumed CON had a reduced fecal pH (P < 0.01) and steers consuming SCFP tended to have a reduced fecal pH (P = 0.08) from d 35 to 56 compared with TYL fed steers, while both CON and SCFP fed steers experienced an increase in fecal pH from d 56 to 112 (P < 0.01). A time effect was detected (P ≤ 0.04) for plasma glucose, lactate, urea nitrogen, and non-esterified fatty acid concentrations among treatment groups. A treatment × time interaction was observed (P < 0.02) for stx2 genes of Shiga toxin producing Escherichia coli (STEC) in individual fecal samples where SCFP and TYL fed steers tended to exhibit an increased concentration compared with CON fed steers on d 14, while on d 190 CON and SCFP fed steers exhibited an increased concentration compared with TYL fed steers. Overall, STEC, E. coli O157:H7, and Salmonella concentrations were all impacted by time (P < 0.001). This experiment suggests that SCFP could be utilized as a potential alternative to TYL in feedlot cattle without adversely affecting cattle performance. However, SCFP did not impact pathogen shedding. In addition, CON fed steers performed similarly to both SCFP and TYL fed steers.

Effect of a 14-Day Period of Heat Acclimation on Horses Using Heated Indoor Arenas in Preparation for Tokyo Olympic Games.

To optimise the performance and welfare of horses during equestrian competitions in hot climates, it is advised to acclimate them to the heat. The effects of training in a heated indoor arena were studied. Four Olympic horses (13.3 ± 2.2 years; three eventers, one para-dressage horse) were trained for 14 consecutive days in a heated indoor arena (32 ± 1 °C; 50-60% humidity) following their normal training schedule in preparation for the Tokyo Olympic games. Standardised exercise tests (SETs) were performed on Day 1 and Day 14, measuring heart rate (HR; bpm), plasma lactate concentration (LA; mmol/L), deep rectal temperature (Trec; °C), sweat loss (SL; L), and sweat composition (K+, Cl- and Na+ concentration). The data were analysed using linear mixed models. The Trec and HR were significantly decreased after acclimation (estimate: -0.106, 95% CI -0.134, -0.078; estimate: -4.067, 95% CI -7.535, -0.598, respectively). Furthermore, for all the horses, the time taken to reach their peak Trec and heat storage increased, while their LA concentrations decreased. The SL, Cl-, and Na+ concentrations decreased in three out of the four horses. Conclusions: Fourteen days of normal training in a heated indoor arena resulted in a reduction in cardiovascular and thermal strain. This is advantageous because it shows that elite sport horses can be acclimated while training as usual for a championship.

Incidence of concurrent systemic injuries with traumatic proptosis and its effect on outcome - 100 dogs.

To evaluate the incidence of concurrent systemic injuries in dogs with traumatic ocular proptosis and their effect on survival to discharge. Additionally, to evaluate for associations between the type of trauma, each presenting vital signs, minimum laboratory database findings including packed cell volume, total solids, plasma glucose and lactate concentrations, and the diagnosis of concurrent systemic injury and survival. Retrospective study between the years 2017 and 2022. One university teaching hospital and one large, private practice. One hundred dogs presenting to the hospital with a diagnosis of traumatic ocular proptosis. Medical records were retrospectively reviewed; signalment, breed, sex, age, weight, date of presentation, type of trauma sustained, time from trauma to presentation, vitals on presentation, and minimum laboratory database findings including packed cell volume (PCV), total solids (TS), plasma glucose concentration, and plasma lactate concentration were recorded. A modified animal trauma triage (ATT) score was retrospectively calculated. A total of 17 dogs (17%) had concurrent systemic injury. Compared to dogs without systemic injuries, dogs with systemic injuries had a significantly lower body temperature [median 101.1F (38.3C) vs. 101.6F (38.6C); P = 0.008], significantly higher plasma glucose concentrations (125 mg/dL, 6.9 mmol/L vs. 112 mg/dL, 6.2 mmol/L; P = 0.012) and approaching statistical significance, lower PCV values (median 40 vs. 46%; P = 0.051). Dogs presenting with traumatic ocular proptosis do present with concurrent systemic, non-ocular injuries; however, these concurrent injuries do not seem to be associated with survival to discharge.

Prospective evaluation of platelet function and fibrinolysis in 20 dogs with trauma.

To determine platelet function and assess fibrinolysis in dogs following trauma using multiple electrical impedance aggregometry and a modified thromboelastographic (TEG) technique. To determine if the severity of trauma, as assessed by the Animal Trauma Triage (ATT) score and clinicopathological markers of shock, is associated with a greater degree of platelet dysfunction and fibrinolysis. University teaching hospital. Twenty client-owned dogs with trauma (occurring <24h prior to admission and blood sampling) and ATT score of >4 were prospectively recruited. A control group of 10 healthy dogs was included. None. Platelet function was measured using multiple electrode platelet aggregometry (MEPA) utilizing arachidonic acid, ADP, and collagen agonists. Fibrinolysis was assessed in citrated whole blood with the addition of tissue plasminogen activator (tPA; 50U/mL) using kaolin-activated TEG. Conventional statistical analysis was performed to compare coagulation parameters between the groups and assess linear correlations. Median (interquartile range) ATT score was 5 (5-7), and 65% (n=13) of dogs suffered polytrauma. Mean(±SD) time from trauma to blood sampling was 9hours (±6). Median (interquartile range) shock index and plasma lactate concentration were 1.1 (0.7-2.0, n=16) and 2.9mmol/L (0.9-16.0, n=18), respectively. Four dogs did not survive to discharge (20%). There were no differences between the trauma and control group coagulation variables. A moderate negative correlation between ATT score and area under the curve for ADP was found (P=0.043, r2 =-0.496). Preliminary evaluation of platelet function measured by MEPA, and fibrinolysis measured by tPA-modified TEG, is not significantly different in this population of dogs with traumatic injury compared to healthy dogs.

Physiological and skeletal muscle responses to high-intensity interval exercise in Thoroughbred horses.

The purpose of this study was to determine whether acute high-intensity interval exercise or sprint interval exercise induces greater physiological and skeletal muscle responses compared to moderate-intensity continuous exercise in horses. In a randomized crossover design, eight trained Thoroughbred horses performed three treadmill exercise protocols consisting of moderate-intensity continuous exercise (6 min at 70% VO2max; MICT), high-intensity interval exercise (6 × 30 s at 100% VO2max; HIIT), and sprint interval exercise (6 × 15 s at 120% VO2max; SIT). Arterial blood samples were collected to measure blood gas variables and plasma lactate concentration. Biopsy samples were obtained from the gluteus medius muscle before, immediately after, 4 h, and 24 h after exercise for biochemical analysis, western blotting and real-time RT-PCR. Effects of time and exercise protocol were analyzed using mixed models (p < 0.05). Heart rate and plasma lactate concentration at the end of exercise were higher in HIIT and SIT than those in MICT (heart rate, HIIT vs. MICT, p = 0.0005; SIT vs. MICT, p = 0.0015; lactate, HIIT vs. MICT, p = 0.0014; SIT vs. MICT, p = 0.0003). Arterial O2 saturation and arterial pH in HIIT and SIT were lower compared with MICT (SaO2, HIIT vs. MICT, p = 0.0035; SIT vs. MICT, p = 0.0265; pH, HIIT vs. MICT, p = 0.0011; SIT vs. MICT, p = 0.0023). Muscle glycogen content decreased significantly in HIIT (p = 0.0004) and SIT (p = 0.0016) immediately after exercise, but not in MICT (p = 0.19). Phosphorylation of AMP-activated protein kinase (AMPK) in HIIT showed a significant increase immediately after exercise (p = 0.014), but the increase was not significant in MICT (p = 0.13) and SIT (p = 0.39). At 4 h after exercise, peroxisome proliferator-activated receptor γ co-activator-1α mRNA increased in HIIT (p = 0.0027) and SIT (p = 0.0019) and vascular endothelial growth factor mRNA increased in SIT (p = 0.0002). Despite an equal run distance, HIIT and SIT cause more severe arterial hypoxemia and lactic acidosis compared with MICT. In addition, HIIT activates the AMPK signaling cascade, and HIIT and SIT elevate mitochondrial biogenesis and angiogenesis, whereas MICT did not induce any significant changes to these signaling pathways.

Low oxygen in inspired air causes severe cerebrocortical hypoxia and cell death in the cerebral cortex of awake rats

Type 1 respiratory failure (T1RF) is associated with secondary acute brain injury (sABI). The underlying mechanisms of sABI could include injury to brain cells mediated either by hypoxia or by lung injury-triggered inflammation. To elucidate to what extent T1RF causes hypoxia and a consequent hypoxic injury in the brain in the absence of lung injury, we exposed healthy, conscious Sprague-Dawley rats to 48 h long low partial pressure of O2 in inspired air (PiO2) (7.5–8 % O2 in N2, CO2 < 0.5 %, normal barometric pressure) and measured the partial pressure of oxygen in the premotor cortex (PtO2), cerebral blood flow (CBF), lactate concentrations, and cell death. Low PiO2 significantly affected PtO2, which was 52.3 (SD 2.1) mmHg when PiO2 was normal but declined to 6.4 (SD 3.8) mmHg when PiO2 was low for 1 h. This was accompanied by increased lactate concentrations in plasma, CSF, and premotor cortex. Low PiO2 elevated the number of dead cells in the cerebral cortex from 5.6 (SD 4.8) % (when PiO2 was normal) to 20.5 (SD 4.1) % and 32.37 (SD 6.5) % after 24 h and 48 h exposure to low PiO2, respectively. The Mann-Kendall test could not detect any monotonic increase or decrease in pial blood flow during the 48 h exposure to low PiO2. In summary, our findings suggest that exposure to low PiO2 caused a severe hypoxia in the cerebral cortex, which triggers a massive cell death. Since these conditions mimic T1RF, hypoxic injury could be an important underlying cause of T1RF-induced sABI.

Elevated liver glycogenolysis mediates higher blood glucose during acute exercise in Barth syndrome.

Male TAFAZZIN shRNA transgenic (TG) and wild-type (WT) mice completed exhaustive treadmill running protocols to test exercise tolerance. Mice underwent 2H- and 13C-stable isotope infusions at rest and during a 30-minute treadmill running bout to quantify hepatic glucose production and associated nutrient fluxes under sedentary conditions and during acute exercise. Circulating and tissue (skeletal muscle and liver) samples were obtained during and following exercise to assess static metabolite levels. TG mice reached exhaustion sooner during exhaustive treadmill running protocols and exhibited higher plasma lactate concentrations after exhaustive exercise compared to WT mice. Arterial glucose levels were comparable between genotypes at rest, but higher in TG mice compared to WT mice during exercise. Consistent with the higher blood glucose, TG mice showed increased endogenous glucose production owing to elevated glycogenolysis compared to WT mice during exercise. Total gluconeogenesis, gluconeogenesis from glycerol, gluconeogenesis from phosphoenolpyruvate, pyruvate cycling, total cataplerosis, and anaplerotic fluxes were similar between TG and WT mice at rest and during exercise. However, lactate dehydrogenase flux and TCA cycle fluxes trended higher in TG mice during exercise. Liver glycogen content in TG was higher in TG vs. controls. Our data in the Tafazzin knockdown mouse suggest that elevated anaerobic metabolism during rest and exercise previously reported in humans with BTHS are supported by the finding of higher hepatic glycogenolysis.

Physiological stress responses of European seabass Dicentrarchus labrax related to changing operations of floating net cages in intensive farming conditions at the Moroccan M'diq bay.

The present study purposed to quantify and compare in-situ the primary and secondary physiological stress responses, related to the operation of floating net-cages changing, in both sub-adults (523 days post hatching) and adults (916 dph) European sea bass Dicentrarchus labrax, under intensive farming conditions in the Moroccan M'diq Bay. Levels of cortisol, glucose, total cholesterol, total protein and lactate, as well as the percentage of hematocrit were measured before and after stress. The results showed significantly elevated levels of cortisol and blood glucose in both age groups, while total cholesterol and protein levels were unaffected. In fact, blood lactate was significantly reduced in sub-adults, while in adults this parameter was not affected by the operation. However, the hematocrit percentages measured after the operation were significantly higher than those found before the operation in both groups of fish, which is linked to the increased rate of oxygen renewal by the new net cages and the lower water temperature inside the cages. With regard to the age-specific response during this essential operation - before and after the operation - plasma cortisol, blood glucose and lactate concentrations, as well as plasma total protein levels, were significantly higher in sub-adults than in adults. It is concluded that aquaculture practices such as changing the aquaculture net-cage could have repercussions in terms of the classic physiological responses to stress in D. labrax. This article is protected by copyright. All rights reserved.

Acute exercise in a hot environment increases heat shock protein 70 and peroxisome proliferator-activated receptor γ coactivator 1α mRNA in Thoroughbred horse skeletal muscle.

Heat acclimatization or acclimation training in horses is practiced to reduce physiological strain and improve exercise performance in the heat, which can involve metabolic improvement in skeletal muscle. However, there is limited information concerning the acute signaling responses of equine skeletal muscle after exercise in a hot environment. The purpose of this study was to investigate the hypothesis that exercise in hot conditions induces greater changes in heat shock proteins and mitochondrial-related signaling in equine skeletal muscle compared with exercise in cool conditions. Fifteen trained Thoroughbred horses [4.6 ± 0.4 (mean ± SE) years old; 503 ± 14 kg] were assigned to perform a treadmill exercise test in cool conditions [COOL; Wet Bulb Globe Temperature (WBGT), 12.5°C; n = 8] or hot conditions (HOT; WBGT, 29.5°C; n = 7) consisting of walking at 1.7 m/s for 1 min, trotting at 4 m/s for 5 min, and cantering at 7 m/s for 2 min and at 90% of VO2max for 2 min, followed by walking at 1.7 m/s for 20 min. Heart rate during exercise and plasma lactate concentration immediately after exercise were measured. Biopsy samples were obtained from the middle gluteal muscle before and at 4 h after exercise, and relative quantitative analysis of mRNA expression using real-time RT-PCR was performed. Data were analyzed with using mixed models. There were no significant differences between the two groups in peak heart rate (COOL, 213 ± 3 bpm; HOT, 214 ± 4 bpm; p = 0.782) and plasma lactate concentration (COOL, 13.1 ± 1.4 mmoL/L; HOT, 17.5 ± 1.7 mmoL/L; p = 0.060), while HSP-70 (COOL, 1.9-fold, p = 0.207; HOT, 2.4-fold, p = 0.045), PGC-1α (COOL, 3.8-fold, p = 0.424; HOT, 8.4-fold, p = 0.010), HIF-1α (COOL, 1.6-fold, p = 0.315; HOT, 2.2-fold, p = 0.018) and PDK4 (COOL, 7.6-fold, p = 0.412; HOT, 14.1-fold, p = 0.047) mRNA increased significantly only in HOT at 4 h after exercise. These data indicate that acute exercise in a hot environment facilitates protective response to heat stress (HSP-70), mitochondrial biogenesis (PGC-1α and HIF-1α) and fatty acid oxidation (PDK4).

S-Adenosylhomocysteine Is a Useful Metabolic Factor in the Early Prediction of Septic Disease Progression and Death in Critically Ill Patients: A Prospective Cohort Study.

A common final pathway of pathogenetic mechanisms in septic organ dysfunction and death is a lack or non-utilization of oxygen. Plasma concentrations of lactate serve as surrogates for the oxygen-deficiency-induced imbalance between energy supply and demand. As S-adenosylhomocysteine (SAH) was shown to reflect tissue hypoxia, we compared the ability of SAH versus lactate to predict the progression of inflammatory and septic disease to septic organ dysfunction and death. Using univariate and multiple logistic regression, we found that SAH but not lactate, taken upon patients' inclusion in the study close to ICU admission, significantly and independently contributed to the prediction of disease progression and death. Due to the stronger increase in SAH in relation to S-adenosylmethionine (SAM), the ratio of SAM to SAH, representing methylation potential, was significantly decreased in patients with septic organ dysfunction and non-survivors compared with SIRS/sepsis patients (2.8 (IQR 2.3-3.9) vs. 8.8 (4.9-13.8); p = 0.003) or survivors (4.9 (2.8-9.5) vs. 8.9 (5.1-14.3); p = 0.026), respectively. Thus, SAH appears to be a better contributor to the prediction of septic organ dysfunction and death than lactate in critically ill patients. As SAH is a potent inhibitor of SAM-dependent methyltransferases involved in numerous vital biochemical processes, the impairment of the SAM-to-SAH ratio in severely critically ill septic patients and non-survivors warrants further studies on the pathogenetic role of SAH in septic multiple organ failure.

Investigation of Plasma Lactate Concentration in Anemic Dogs

In many clinical situations, the importance of determining plasma lactate level is emphasised, while the effect of type and severity of anemia on plasma lactate concentration is not fully known. It was aimed to evaluate the effect of anemia type and severity on plasma lactate concentrations in dogs with anemia in this study. &#x0D; A total of 48 dogs (36 anemic, 12 healthy) of different breeds, ages and sexes were included in the study. Dogs with anemia were classified according to the severity and type of anemia. Hematologic evaluations included RBC, HGB, HCT, and MCV measurements. Plasma lactate concentrations were colourimetrically tested on a point-of-care analyser. &#x0D; Plasma lactate levels were significantly (P

337-OR: Hyperglycemia Lowers Lactate Clearance during Exercise in Type 1 Diabetes

To determine the role of hyperglycemia on lactate metabolism during exercise in type 1 diabetes (T1D), we studied 7 T1D participants during two visits (EuLoI; euglycemia, low insulin; HyLoI: hyperglycemia, low insulin) in random order. 7 nondiabetic (ND) subjects were studied on one occasion (EuLoI). Lactate turnover was measured using [1-13C] lactate before, during and after 60 min of exercise at 65% VO2 max. While lactate clearance was lower (p=0.031) during exercise at HyLoI than EuLoI in T1D, it was not different between T1D and ND subjects at EuLoI (p=0.707). In contrast, rate of lactate appearance during exercise was not different between EuLoI vs. HyLoI in T1D (p=0.129), demonstrating that higher plasma lactate concentration during exercise in HyLoI (p&amp;lt;0.001) was due to reduced lactate clearance in T1D. The results from this pilot study indicates that hyperglycemia modulates lactate metabolism during exercise by lowering lactate clearance in T1D individuals. This novel observation implies that exercise during hyperglycemia can lead to higher circulating lactate concentrations thus increasing the likelihood of reaching the lactate threshold sooner, in type 1 diabetes. Disclosure D.Romeres: None. Y.Yadav: None. F.Ruchi: None. R.Carter: None. C.Cobelli: None. R.Basu: Consultant; Sparrow Pharmaceuticals Inc, Research Support; Abbott Diabetes, AstraZeneca. A.Basu: None. Funding National Institutes of Health (DK29953 to R.B.), (DK85516 to A.B.)

Medical causes of poor performance and their associations with fitness in Standardbred racehorses.

Poor performance is a multifactorial syndrome of racehorses, commonly associated with subclinical disorders, which can be diagnosed by exercise testing. Describe the prevalence of medical causes of poor performance in Standardbreds unassociated with lameness, and evaluate their relationships with fitness variables measured by exercise treadmill test. Hospital population of 259 nonlame Standardbred trotters referred for poor performance. The horses' medical records were retrospectively reviewed. Horses underwent a diagnostic protocol including resting examination, plasma lactate concentration, treadmill test with continuous ECG and assessment of fitness variables, creatine kinase activity, treadmill endoscopy, postexercise tracheobronchoscopy, bronchoalveolar lavage (BAL), and gastroscopy. The prevalence of different disorders was evaluated, including cardiac arrhythmias, exertional myopathies, dynamic upper airway obstructions (DUAOs), exercise-induced pulmonary hemorrhage (EIPH), moderate equine asthma (MEA), and gastric ulcers (EGUS). The associations of these disorders with fitness variables were investigated individually and using multivariable models. Moderate equine asthma and EGUS were the most common disorders, followed by EIPH, DUAOs, cardiac arrhythmias, and exertional myopathies. Hemosiderin score was positively correlated with BAL neutrophils, eosinophils, and mast cells; increased creatine kinase activity was associated with BAL neutrophilia, DUAOs, premature complexes, and squamous gastric disease. Treadmill velocity at a plasma lactate concentration of 4 mmol/L and at heart rate of 200 beats per minute was negatively affected by BAL neutrophilia, multiple DUAOs, exertional myopathies, and squamous gastric disease. The multifactorial nature of poor performance was confirmed, with MEA, DUAOs, myopathies and EGUS representing the main diseases involved in fitness impairment.