Rise In Lactate Research Articles

Lactoylglutathione promotes inflammatory signaling in macrophages through histone lactoylation

Chronic, systemic inflammation is a pathophysiological manifestation of metabolic disorders. Inflammatory signaling leads to elevated glycolytic flux and a metabolic shift towards aerobic glycolysis and lactate generation. This rise in lactate corresponds with increased generation of lactoylLys modifications on histones, mediating transcriptional responses to inflammatory stimuli. Lactoylation is also generated through a non-enzymatic S-to-N acyltransfer from the glyoxalase cycle intermediate, lactoylglutathione (LGSH). Here, we report a regulatory role for LGSH in mediating histone lactoylation and inflammatory signaling. In the absence of the primary LGSH hydrolase, glyoxalase 2 (GLO2), RAW264.7 macrophages display significant elevations in LGSH and histone lactoylation with a corresponding potentiation of the inflammatory response when exposed to lipopolysaccharides. An analysis of chromatin accessibility shows that lactoylation is associated with more compacted chromatin than acetylation in an unstimulated state; upon stimulation, however, regions of the genome associated with lactoylation become markedly more accessible. Lastly, we demonstrate a spontaneous S-to-S acyltransfer of lactate from LGSH to CoA, yielding lactoyl-CoA. This represents the first known mechanism for the generation of this metabolite. Collectively, these data suggest that LGSH, and not intracellular lactate, is the primary driving factor facilitating histone lactoylation and a major contributor to inflammatory signaling.

Warburg-Effect Driven Lactic Acidosis Is Associated with Early Death in Patients with Lymphoma

Introduction: Lactic acidosis is a medical emergency and in most cases results from an imbalance between tissue oxygenation and oxygen demand (Type A). However, Type B lactic acidosis occurs in the absence of a recognizable impairment in systemic oxygen delivery, and is most commonly associated with drug or toxin ingestion, sepsis, severe nutritional deficits such as thiamine, and less commonly, malignancy. The capacity of shifting glucose metabolism to anaerobic pathway despite the presence of adequate oxygen, enhancing the rate of glucose uptake, accelerated glycolysis and hence producing more lactate, is a well-defined phenomenon in malignant cell metabolism, and is called the Warburg Effect (WE) or aerobic glycolysis. A systemic rise in lactate and lactic acidosis has been reported in hematologic malignancies and less commonly in solid tumors, and is thought to occur as a consequence of both increased production of lactate- reflecting high malignancy burden, and impaired lactate turnover or elimination by liver or kidney. Few case reports or series have demonstrated a possible correlation between early death and elevated lactate in patients with hematologic malignancy (Table 1). We aimed to characterize the incidence and clinical impact of Warburg-driven lactic acidosis on outcome including early death. Methods: A retrospective study of patients admitted to the haemato-oncology department in a large tertiary medical center between the years 2013- 2022, that presented with elevated lactate levels during the first week of admission. Patients with hematologic diseases other than lymphoma were excluded. Of 40 patients reviewed, 21 patients were excluded because of underlying hematological malignancy other than lymphoma. Medical records were retrieved and reviewed for a recognizable cause for elevated lactate, or non (assigned as the WE group). Early-death was defined as death of any cause within 4 weeks of admission. Results: Nineteen patients had lymphoma and elevated lactate levels within the first week of admission. Of these, 12 patients fulfilled the criteria for WE and 7 patients had their high lactate attributed to other causes such as hemorrhagic shock (n=1), sepsis (n=5) and concomitant metformin use (n=1). Median age among patients with WE was 72.5 years (range 66-86) with 41.6% (n=5) males. All but one had aggressive lymphoma. Diffuse Large B cell Lymphoma was the most frequent type (n=9) followed by T cell Lymphoma (n=2) and follicular lymphoma (n=1). Most patients had advanced disease (Stage III-IV in 75%) and the median International Prognostic Index (IPI) of the patients was 4 (range 3-5). The median lactate level was 31.5 mg/dL (range 25-64; with upper limit of normal value-20 mg/dL). Two patients received thiamin therapy once WE was recognized. Early-death rate was 75% (9 patients) among patients with WE. The established cause of death in this population was: sepsis (n=3), DIC (n=1), uremia and multi organ failure (n=2) and respiratory failure due to lung infiltration by lymphoma (n=3). Both steroid and chemotherapy were initiated earlier in surviving patients as compared to those who died early (within 4 weeks of admission); in surviving patients, chemotherapy was initiated at a median of 3 days before first elevated lactate was detected (range (-)7-1), and steroids at median of 3 days before first elevated lactate was detected, while in those who died early, chemotherapy was initiated at median of 5 days after first elevated lactate was detected (range (-)2-18) and steroids at median 1 day after first elevated lactate (p=0.29 and 0.05 for steroids and chemo, respectively). (Table 2). Conclusion: Warburg driven lactic acidosis is a marker of ‘acute cancer’ in lymphoma patients and is associated with a very high mortality rate. Early recognition of this very high-risk clinical scenario is of utmost importance and should prompt immediate anti-lymphoma therapy that may improve outcome.

Does the systemic rise in serum lactate levels correlate to free flap failure in head and neck reconstructive surgeries—series of cases

BackgroundHead and neck reconstructive surgeries needs free tissue transfer but it fails sometimes. As most of the flap failure occurs in first 24 h. Local rise in lactate level or glucose lactate ratio provides clear indicator of tissue ischemia and further recovery. The question is about systemic rise in lactate levels with failing flap. Hence, we aimed to use systemic lactate levels to indicate free flap failure. To correlate the systemic rise in serum lactate levels to free flap failure in head and neck reconstructive surgeries. The series of cases were targeted undergoing free fibular graft, posted electively for head and reconstructive surgery operated by same surgeon. Record of blood loss, need of blood transfusion and use of microspan was also done. Monitoring of arterial blood gas values mainly lactate and vitals were done.ResultsOut of 15 patients studied, only 2(13.3%) patients had flap re-exploration (group F). Twelve (80%) patients were of ASA class I. Lactate, pH, blood sugars, base deficits and hemoglobin and vitals studied over 24 h in two groups had no statistically significant difference in the two groups. Lactate rise was noted in all cases for first few hours after starting surgery but elevated values were not observed during hours of flap re-exploration.ConclusionsWe could not establish relation between systemic rise in lactate levels and flap re-exploration or flap failure but continuous acidosis can impact outcome. We need to be vigilant and need to have individualized approach for management.

Anion gap(AG) or serum lactate-in search of a better prognostic marker in sepsis a cross-sectional study in a rural tertiary care hospital

Background: In intensive care units, sepsis is a common diagnosis. Serum lactate rise has been established as an essential measure for predicting the outcome of sepsis. Higher anion gap(AG) has been associated with an increased risk of death in critically ill individuals. We measured blood lactate levels and AG and looked at how these predicted in-hospital outcomes (death or discharge).This study aimed to estimate anion gap values in sepsis syndrome, to measure the serum lactate levels in sepsis syndrome, to correlate the anion gap and serum lactate values with the outcome (mortality and discharge) in patients with sepsis syndrome. Methods: The Department of Medicine at Jawaharlal Nehru Medical College conducted this single-center, prospective, observational cross-sectional study with a cohort design. A total of 160 patients with sepsis were screened in the ICU. Sepsis was diagnosed using SEPSIS-3 criteria. Results: In this study, we included 160 patients with sepsis with sequential organ failure assessment (SOFA) score >2.Mean serum lactate was 5.1±1.2 mmol/L and it was ≥4 mmol/L in 90% of patients. Mean AG was 14.0±3.9 and it was ≥12 in 75.6% of patients. Similarly, the proportion of patients who had lactate levels ≥4 mmol/L was higher in those with AG ≥12 than AG <12 (95.9% vs. 71.8%, p<0.0001). The AUC of ROC in predicting mortality was significant for both serum lactate (AUC 0.797, p<0.0001) and AG (AUC 0.835, p<0.0001). Conclusions: Along with other parameters predicting mortality, serum lactate and AG also act as important predictors of mortality in sepsis patients. We conclude that on admission serum lactate ≥4 mmol/L and AG ≥12 can be used in predicting short-term mortality in patients with sepsis.

456: A CHALLENGING CASE OF RAPID-ONSET MULTISYSTEM ORGAN FAILURE IN A BURN PATIENT

Introduction: Burns are significant injuries that cause a cascade of inflammatory responses. Patients with large burns and inhalation injury often experience respiratory failure, renal failure, liver dysfunction, and sepsis. The COVID-19 virus has added a unique challenge as a current or recent COVID-19 infection seems to lend to worse outcomes, However, we do not yet have enough data to understand the full implication of COVID-19 on burn patients. Description: A 41-year-old man with no remarkable medical history was admitted to the Burn Intensive Care Unit (BICU) with 58% body surface area burns with smoke inhalation. He was given appropriate burn resuscitation and placed on the volumetric diffusive respirator (VDR). Admission COVID-19 PCR was negative, and COVID-19 Spike IgG was 12 IU/mL. Both labs and vital signs remained stable and he went to the OR on hospital day 4 for excision and grafting and the first 24 hours post-op were unremarkable. On post-op day 1, he had an abrupt rise in lactate with worsening acidosis. Sepsis guidelines were followed and he required initiation of renal replacement therapy (CRRT) along with bedside laparotomy with no significant findings. Repeat lab work showed a COVID-19 Spike IgG level >800. Patient’s conditioned worsened despite maximal medical intervention, and he died on hospital day 8. Since the sudden, rapid decline in patient’s condition at this point in his hospitalization is somewhat atypical, we theorize that patient was either admitted with COVID-19 infection that was undetectable, or this was a nosocomial infection. Though he had no significant comorbidities, it certainly seems that this new infection unduly stressed his immune system, leading to multi-system organ failure and death. Discussion: Large burn injuries are often challenging to manage, but improved therapies and treatments have led to increasingly good outcomes. The addition of current or recent COVID-19 infection adds a new challenge which needs further study as we learn more about the inflammatory and long-term implications of this disease on lung function and immune systems. Our experience of rapid onset organ failure and death in a burn patient with likely new COVID-19 infection presented a unique burn and critical care management challenge that needs further study.

514 ATAXIA TELANGIECTASIA MUTATED PROTEIN MODULATES GLUCOSE AND LIPID METABOLISM IN THE HEART

Abstract Background Ataxia Telangiectasia Mutated (ATM) protein kinase is the major sensor of DNA damage response (DDR) and oxidative stress, variously implicated in cellular metabolism. Previous studies on ATM functions in the heart have produced conflicting results. Here we hypothesized that ATM might regulate cardiomyocyte metabolic homeostasis and function. Methods Atm-mutated mice (Atm-/-) and their wild-type littermates (Atm+/+) were used to assess the effects of ATM inactivation on cardiomyocyte hypertrophy, cardiac structure, function, DDR and metabolism under sham conditions or after pressure overload by transverse aortic constriction (TAC). Results ATM inactivation induced cardiomyocyte hypertrophy (FIG.1 A), fetal gene expression re-activation and a specific metabolomic signature in the heart, characterized by significant accumulation of pyruvate, branched chain amino-acids, short-medium acyl-carnitines and metabolites of tricarboxylic acid cycle (FIG.1 C, D),. Importantly, pyruvate was trapped in the cytosol because mitochondrial carriers were suppressed and the enzymes that process pyruvate were dysregulated. As a consequence of pyruvate metabolic block, fatty acids oxidation was inefficient and resulted in the accumulation of acyl-carnitines and insulin resistance. Although these metabolic changes were present constitutively in Atm-/- mice, they were amplified by TAC, which rapidly induced heart failure (FIG.1 B) in Atm-/- mice. ATM inactivation also increased basal and TAC-induced genomic stress in cardiomyocytes, as shown by the levels of p-γ-H2AX, 8-oxodG glycosylase (OGG1/2) and apurinic site nuclease (APE1). Cardiac metabolic changes induced by ATM loss (rise of pyruvate, lactate and succinate levels) were also present in Atm-/- brains, although the basal conditions were different. Conclusions ATM rewires the metabolism of cardiac cells by inducing glycolysis and fatty acids oxidation. Combining metabolomic, DNA damage and cardiac phenotypes, we deduce that ATM stimulates glycolysis to repair DNA lesions and protect the heart against stress-induced dysfunction.

Effect of caffeine on mitochondrial biogenesis in the skeletal muscle - A narrative review.

Caffeine is one of the most widely used substances as recreational drug for performance-enhancement in sport, underpinned by a strong evidence base. Although the effects of caffeine are widely investigated within the scope of performance physiology, the molecular effects of caffeine within skeletal muscle remain unclear. Evidence from invitro and invivo models suggest that caffeine regulates the glucose metabolism in the skeletal muscle. Moreover, caffeine seems to stimulate CaMKII, PPARδ/β, AMPK and PGC1α, classical markers of exercise-adaptations, including mitochondrial biogenesis and mitochondrial content. This review summarizes evidence to suggest caffeine-effects within skeletal muscle fibers, focusing on the putative role of caffeine on mitochondrial biogenesis to explore whether caffeine supplementation might be a strategy to enhance mitochondrial biogenesis.

Hypothermia Alleviates Reductive Stress, a Root Cause of Ischemia Reperfusion Injury

Ischemia reperfusion injury is common in transplantation. Previous studies have shown that cooling can protect against hypoxic injury. To date, the protective effects of hypothermia have been largely associated with metabolic suppression. Since kidney transplantation is one of the most common organ transplant surgeries, we used human-derived renal proximal tubular cells (HKC8 cell line) as a model of normal renal cells. We performed a temperature titration curve from 37 °C to 22 °C and evaluated cellular respiration and molecular mechanisms that can counteract the build-up of reducing equivalents in hypoxic conditions. We show that the protective effects of hypothermia are likely to stem both from metabolic suppression (inhibitory component) and augmentation of stress tolerance (activating component), with the highest overlap between activating and suppressing mechanisms emerging in the window of mild hypothermia (32 °C). Hypothermia decreased hypoxia-induced rise in the extracellular lactate:pyruvate ratio, increased ATP/ADP ratio and mitochondrial content, normalized lipid content, and improved the recovery of respiration after anoxia. Importantly, it was observed that in contrast to mild hypothermia, moderate and deep hypothermia interfere with HIF1 (hypoxia inducible factor 1)-dependent HRE (hypoxia response element) induction in hypoxia. This work also demonstrates that hypothermia alleviates reductive stress, a conceptually novel and largely overlooked phenomenon at the root of ischemia reperfusion injury.

Prevalence and mechanisms of environmental hyperoxia-induced thermal tolerance in fishes.

Recent evidence has suggested environmental hyperoxia (O2 supersaturation) can boost cardiorespiratory performance in aquatic ectotherms, thereby increasing resilience to extreme heat waves associated with climate change. Here, using rainbow trout (Oncorhynchus mykiss) as a model species, we analysed whether improved cardiorespiratory performance can explain the increased thermal tolerance of fish in hyperoxia (200% air saturation). Moreover, we collated available literature data to assess the prevalence and magnitude of hyperoxia-induced thermal tolerance across fish species. During acute warming, O2 consumption rate was substantially elevated under hyperoxia relative to normoxia beyond 23°C. This was partly driven by higher cardiac output resulting from improved cardiac contractility. Notably, hyperoxia mitigated the rise in plasma lactate at temperatures approaching upper limits and elevated the critical thermal maximum (+0.87°C). Together, these findings show, at least in rainbow trout, that hyperoxia-induced thermal tolerance results from expanded tissue O2 supply capacity driven by enhanced cardiac performance. We show 50% of the fishes so far examined have increased critical thermal limits in hyperoxia (range: 0.4–1.8°C). This finding indicates environmental hyperoxia could improve the ability of a large number of fishes to cope with extreme acute warming, thereby increasing resilience to extreme heat wave events resulting from climate change.

Attenuation of metabolic stress response during spinal surgery under general anaesthesia - A comparison between preoperative carbohydrate drink or no carbohydrate load

Background: Surgery is a stress which stimulates the increase of counter regulatory hormones. Pre-operative prolonged fasting increases stress further. Although a pre-operative carbohydrate (CHO) drink has been variably reported to yield benefit in reducing the perioperative stress and is being used frequently for elective surgeries, some recent reports also reports that preoperative CHO loading did not result in increase or decrease in the post-operative complication rates when compared with placebo or fasting group. Aims and Objectives: The present study was designed to determine the stress response in the postoperative period at 24 h in terms of changes in the levels of cortisol and other biomarkers. Materials and Methods: This randomized, parallel group, and double-blind study was conducted in 75 patients aged 18–65 years, of American Society of Anesthesiologists Physical Status Classes I and II, scheduled for elective lumbar spine surgery under general anesthesia. The patients were randomly allocated to receive 300 ml plain water at 9 pm on the day before surgery and 2 h before operation (Group C, control, n=25), or 300 ml plain water at 9 pm on the day before surgery and solution containing 75 grams of glucose dissolved in 300 ml water in the morning 2 h before surgery (Group CHO-1, n=25), or to receive 75 grams of glucose dissolved in 300 ml water at 9 pm in the night before the surgery and again in the morning at 2 h before surgery (Group CHO-2, n=25). In all the three groups, the levels of insulin (C-peptide), lactate, glucose, and cortisol were determined preoperatively (before the induction of anesthesia) and 24 h postoperatively. Results: There was considerable difference between post-operative blood cortisol level among the three groups (583.9 vs. 462.3 vs. 389.6 nMol/L, Control vs., CHO load once or twice, respectively, P<0.0001). A significant difference in post-operative values was also seen with other parameters such as serum lactate, glucose, and C-peptide. Considerable differences were seen in both preoperative and postoperative period in case of cortisol and lactate whereas it was limited to postoperative values in case of glucose and C-peptide. Conclusion: Pre-operative glucose loading showed better efficacy in suppressing perioperative stress response in terms of less rise of serum cortisol and lactate as compared to no CHO load.

Acute arm and leg muscle glycogen and metabolite responses to small-sided football games in healthy young men.

Studies have indicated upper body involvement during football, provoking long-term muscular adaptations. This study aimed at examining the acute metabolic response in upper and lower body skeletal muscle to football training organized as small-sided games (SSG). Ten healthy male recreational football players [age 24 ± 1 (± SD) yrs; height 183 ± 4cm; body mass 83.1 ± 9.7kg; body fat 15.5 ± 5.4%] completed 1-h 5v5 SSG (4 × 12min interspersed with 4-min recovery periods). Muscle biopsies were obtained from m. vastus lateralis (VL) and m. deltoideus (DE) pre- and post-SSG for muscle glycogen and metabolite analyses. Blood lactate samples were obtained at rest, middle and end of the SSG. Muscle glycogen in VL decreased (P < 0.01) by 21% and tended (P = 0.08) to decrease in DE by 13%. Muscle lactate increased in VL (117%; P < 0.001) and DE (81%; P < 0.001) during the game, while blood lactate rose threefold. Muscle ATP and PCr were unaltered, but intermuscular differences were detected for ATP at both time points (P < 0.001) and for PCr at pre-SSG (P < 0.05) with VL demonstrating higher values than DE, while muscle creatine rose in VL (P < 0.001) by 41% and by 22% in DE (P = 0.02). Baseline citrate synthase maximal activity was higher (P < 0.05) in VL compared to DE, whereas baseline muscle lactate concentration was higher (P < 0.05) in DE than VL. The upper body may be extensively involved during football play, but besides a rise in muscle lactate in the deltoideus muscle similar to the leg muscles, the present study did not demonstrate acute metabolic changes of an order that may explain the previously reported training effect of football play in the upper extremities.

Predicting outcomes of mesenteric ischemia postcardiac surgery: A systematic review.

This systematic review aims to identify predictors of outcomes of mesenteric ischemia in patients following cardiac surgery. A comprehensive literature search was done on EMBASE, PubMed, Ovid MEDLINE, and SCOPUS using keywords relating to bowel ischemia and cardiac surgery. Database search results were screened by at least two authors and 32 articles were selected for inclusion in this review. Data on 1907 patients were analyzed. The mean age was 70.0 ± 2.99 years and the prevalence of bowel ischemia was 1.74%. Advanced age was a significant risk factor. 63.16% of patients reported were men, and 58.4% of patients died in hospital. There was heterogeneity in the reported significance of the following preoperative risk factors: hypertension, smoking status, type 2 diabetes mellitus, end-stage renal disease, preoperative left ventricular ejection fraction<35%. Cardiopulmonary bypass(CPB) time, preoperative/operative intra-aortic balloon pump(IABP) support, and inotrope usage were significantly associated with the development of mesenteric ischemia; however, other intraoperative factors including the type of cardiac surgery and duration of aortic cross-clamping had varying levels of reported significance. There were discrepancies in the reported significance of leukocytosis and metabolic acidosis (pH<7.3) as postoperative markers. Postoperative vasopressor use, prolonged ventilation time, and elevation in lactate, transaminases, creatinine, and intestinal fatty acid-binding protein(IFABP) levels were found to be strongly associated with bowel ischemia. This systematic review found the strongest associations of mesenteric ischemia postcardiac surgery to be advanced age, CPB time, rise in lactate, transaminases, creatinine, and IFABP. IABP support, vasopressor, and inotrope use as well as prolonged ventilation were strongly linked too.

Magnetic resonance reveals mitochondrial dysfunction and muscle remodelling in spinal muscular atrophy.

Genetic therapy has changed the prognosis of hereditary proximal spinal muscular atrophy, although treatment efficacy has been variable. There is a clear need for deeper understanding of underlying causes of muscle weakness and exercise intolerance in patients with this disease to further optimize treatment strategies. Animal models suggest that in addition to motor neuron and associated musculature degeneration, intrinsic abnormalities of muscle itself including mitochondrial dysfunction contribute to the disease aetiology.To test this hypothesis in patients, we conducted the first in vivo clinical investigation of muscle bioenergetics. We recruited 15 patients and 15 healthy age and gender-matched control subjects in this cross-sectional clinico-radiological study. MRI and 31P magnetic resonance spectroscopy, the modality of choice to interrogate muscle energetics and phenotypic fibre-type makeup, was performed of the proximal arm musculature in combination with fatiguing arm-cycling exercise and blood lactate testing. We derived bioenergetic parameter estimates including: blood lactate, intramuscular pH and inorganic phosphate accumulation during exercise, and muscle dynamic recovery constants. A linear correlation was used to test for associations between muscle morphological and bioenergetic parameters and clinico-functional measures of muscle weakness.MRI showed significant atrophy of triceps but not biceps muscles in patients. Maximal voluntary contraction force normalized to muscle cross-sectional area for both arm muscles was 1.4-fold lower in patients than in controls, indicating altered intrinsic muscle properties other than atrophy contributed to muscle weakness in this cohort. In vivo31P magnetic resonance spectroscopy identified white-to-red remodelling of residual proximal arm musculature in patients on the basis of altered intramuscular inorganic phosphate accumulation during arm-cycling in red versus white and intermediate myofibres. Blood lactate rise during arm-cycling was blunted in patients and correlated with muscle weakness and phenotypic muscle makeup. Post-exercise metabolic recovery was slower in residual intramuscular white myofibres in patients demonstrating mitochondrial ATP synthetic dysfunction in this particular fibre type.This study provides the first in vivo evidence in patients that degeneration of motor neurons and associated musculature causing atrophy and muscle weakness in 5q spinal muscular atrophy type 3 and 4 is aggravated by disproportionate depletion of myofibres that contract fastest and strongest. Our finding of decreased mitochondrial ATP synthetic function selectively in residual white myofibres provides both a possible clue to understanding the apparent vulnerability of this particular fibre type in 5q spinal muscular atrophy types 3 and 4 as well as a new biomarker and target for therapy.

Myocardial Ischemia During Off-Pump Coronary Artery Bypass Grafting – A Clinical Study

Objective: To evaluate relation among trans-esophageal echocardiography (TEE), biochemical and hemodynamic parameters which could possibly help in early detection of myocardial ischemia. Design: Prospective observational, single centre study. Participants: Patients diagnosed with coronary artery triple vessel disease undergoing Off-pump Coronary Artery Bypass Grafting (OPCAB). Results: Statistically significant changes in Coronary Sinus (CS) pH and lactate levels were observed during lateral wall grafting, as well as the highest proportion of new regional wall motion abnormalities observed which signify the presence of a substantial level of myocardial ischemia during this time. We found a significant rise in HR (Heart Rate) as well as CS lactate following lateral wall grafting which correlated with the other parameters indicating substantial ischemia occurring during grafting of that territory. Maximum lactate clearance was found during anterior wall grafting and minimum after inferior wall grafting. This signifies that maximum lactate accumulates after anterior wall grafting, signifying greater extent of myocardial ischemia. Statistically significant rise in (CVP/RAP) (central venous pressure, right atrial pressure was noted) during grafting of all coronary territories, but the maximal rise was seen at the end of lateral wall grafting, followed by grafting of posterior basal wall. Conclusions: Biochemical changes in form of rise in lactate and fall in CS pH doesn’t occur in absence of obvious hemodynamic derangements. Therefore, it is difficult to detect myocardial ischemia before any hemodynamic instability.

Lung branching morphogenesis is accompanied by temporal metabolic changes towards a glycolytic preference

BackgroundLung branching morphogenesis is characterized by epithelial-mesenchymal interactions that ultimately define the airway conducting system. Throughout this process, energy and structural macromolecules are necessary to sustain the high proliferative rates. The extensive knowledge of the molecular mechanisms underlying pulmonary development contrasts with the lack of data regarding the embryonic lung metabolic requirements. Here, we studied the metabolic profile associated with the early stages of chicken pulmonary branching.MethodsIn this study, we used an ex vivo lung explant culture system and analyzed the consumption/production of extracellular metabolic intermediates associated with glucose catabolism (alanine, lactate, and acetate) by 1H-NMR spectroscopy in the culture medium. Then, we characterized the transcript levels of metabolite membrane transporters (glut1, glut3, glut8, mct1, mct3, mct4, and mct8) and glycolytic enzymes (hk1, hk2, pfk1, ldha, ldhb, pdha, and pdhb) by qPCR. ldha and ldhb mRNA spatial localization was determined by in situ hybridization. Proliferation was analyzed by directly assessing DNA synthesis using an EdU-based assay. Additionally, we performed western blot to analyze LDHA and LDHT protein levels. Finally, we used a Clark-Type Electrode to assess the lung explant's respiratory capacity.ResultsGlucose consumption decreases, whereas alanine, lactate, and acetate production progressively increase as branching morphogenesis proceeds. mRNA analysis revealed variations in the expression levels of key enzymes and transporters from the glycolytic pathway. ldha and ldhb displayed a compartment-specific expression pattern that resembles proximal–distal markers. In addition, high proliferation levels were detected at active branching sites. LDH protein expression levels suggest that LDHB may account for the progressive rise in lactate. Concurrently, there is a stable oxygen consumption rate throughout branching morphogenesis.ConclusionsThis report describes the temporal metabolic changes that accompany the early stages of chicken lung branching morphogenesis. Overall, the embryonic chicken lung seems to shift to a glycolytic lactate-based metabolism as pulmonary branching occurs. Moreover, this metabolic rewiring might play a crucial role during lung development.

Acute perioperative hyperlactatemia in oncoplastic reconstructive surgeries: What is the significance?

Background and Aims:We aim to study the significance of intraoperative hyperlactatemia in reconstructive oncoplastic surgery.Material and Methods:A retrospective observational study was conducted on a cohort of patients who underwent reconstructive oncoplastic surgery with free flap for oral cancer over a 6-month period. The study population was divided into two groups based on peak lactate levels. Group N with peak lactate level less than 2 mmol/L and Group H peak lactate level more than 2 mmol/L. The various parameter studied were patient's comorbidities; intraoperative events (vasopressor requirement, blood transfusion, and duration of surgery); postoperative parameters including the need for re- exploration and duration of stay in hospital and intensive care unit.Results:The study demonstrates that intraoperative rise of lactate was not influenced by comorbidities. None of the intraoperative parameters studied influenced the lactate levels. Baseline lactate level was found to correlate with peak lactate level intraoperatively. But it was observed that there was normalization of lactate level within 24 hours postoperatively in both the groups. There was no difference in outcome parameters in the two groups.Conclusion:Intraoperative hyperlactatemia is not a significant prognostic factor for outcome in oncoplastic reconstructive surgery.

P38 mitogen activated protein kinase inhibitor improves platelet in vitro parameters and in vivo survival in a SCID mouse model of transfusion for platelets stored at cold or temperature cycled conditions for 14 days.

Platelets for transfusion are stored at room temperature (20–24°C) up to 7 days but decline in biochemical and morphological parameters during storage and can support bacterial proliferation. This decline is reduced with p38MAPK inhibitor, VX-702. Storage of platelets in the cold (4–6°C) can reduce bacterial proliferation but platelets get activated and have reduced circulation when transfused. Thermocycling (cold storage with brief periodic warm ups) reduces some of the effects of cold storage. We evaluated in vitro properties and in vivo circulation in SCID mouse model of human platelet transfusion of platelets stored in cold or thermocycled for 14 days with and without VX-702. Apheresis platelet units (N = 15) were each aliquoted into five storage bags and stored under different conditions: room temperature; cold temperature; thermocycled temperature; cold temperature with VX-702; thermocycled temperature with VX-702. Platelet in vitro parameters were evaluated at 1, 7 and 14 days. On day 14, platelets were infused into SCID mice to assess their retention in circulation by flow cytometry. VX-702 reduced negative platelet parameters associated with cold and thermocycled storage such as an increase in expression of activation markers CD62, CD63 and of phosphatidylserine (marker of apoptosis measured by Annexin binding) and lowered the rise in lactate (marker of increase in anaerobic metabolism). However, VX-702 did not inhibit agonist-induced platelet aggregation indicating that it does not interfere with platelet hemostatic function. In vivo, VX-702 improved initial recovery and area under the curve in circulation of human platelets infused into a mouse model that has been previously validated against a human platelet infusion clinical trial. In conclusion, inhibition of p38MAPK during 14-days platelet storage in cold or thermocycling conditions improved in vitro platelet parameters and platelet circulation in the mouse model indicating that VX-702 may improve cell physiology and clinical performance of human platelets stored in cold conditions.

Type 2 Diabetes Mellitus Patients Manifest Greater Muscle Fatigability Than Healthy Individuals During Dynamic Fatigue Protocol

ObjectiveThe present study aimed to investigate the electromyographic (EMG) indices of muscle fatigue along with biochemical marker of fatigue—that is, blood lactate—during a dynamic fatigue protocol in individuals with type 2 diabetes mellitus (T2DM) vs a healthy control group. Secondarily, it aimed to examine the association between EMG indices of muscle fatigue and blood lactate in these patients. MethodsThirty-four participants took part in the study: 19 individuals with T2DM (age, 53.5 ± 6.85 years) and 15 age-matched healthy controls (age, 50.2 ± 3.55 years). Participants performed a dynamic fatigue protocol consisting of 5 sets of 10 repetitions each at an intensity of the 10-repetition maximum. Surface EMG of the vastus medialis and vastus lateralis muscles was recorded during the dynamic fatigue protocol, and EMG indices such as median frequency (MF), slope of MF (MFslope), Dimitrov muscle fatigue spectral index, and root-mean-square were evaluated for each contraction across all the 5 sets. Blood lactate concentrations were also assessed 3 times during the fatigue protocol. ResultsFindings revealed that EMG muscle fatigue indices such as MF, MFslope, and Dimitrov muscle fatigue spectral index were significantly altered in individuals with T2DM vs healthy individuals across the sets and repetitions for both the vastus medialis (P < .001) and vastus lateralis muscles (P < .001). There was a significantly greater rise in blood lactate in individuals with T2DM than in healthy individuals (P < .001), which was not found to be associated with changes in EMG indices of muscle fatigue. ConclusionFindings suggest the existence of significantly greater fatigue in the knee extensor muscles of individuals with T2DM than healthy individuals.

Platelet consumption and hyperreactivity coexist in experimental traumatic hemorrhagic model

Introduction Platelets are critical for hemostasis, and a low platelet count predicts mortality in trauma. The role of platelet dysfunction in severe traumatic hemorrhage and coagulopathy needs to be further defined. The aim of this study was to evaluate the platelet function in a new model of experimental traumatic hemorrhage. Material and methods New Zealand white rabbits (n = 10) were subjected to tracheostomy and trauma laparotomy, and then bilateral femur fractures with 40% hemorrhage of their estimated blood volume. Arterial blood gases, standard coagulation tests, mean platelet volume, platelet aggregation using impedance aggregometry with agonist collagen, arachidonic acid (ASPI), and adenosine diphosphate (ADP), rotational thromboelastometry, and fibrinogen binding of platelets were analyzed using flow cytometry. Results After traumatic hemorrhage, there was a significant physiological response with a rise in lactate (P < .001) and a decrease in base excess (P < .001) and temperature (P < .001). Platelet count decreased from a mean of 244x109/L to 94 x109/L (P = .004) and the mean platelet volume increased from 5.1fL to 6.1fL (P = .002). Impedance aggregometry with the agonist collagen, ASPI, and ADP was all significantly decreased after hemorrhage (P = .007). However, there was an increased fibrinogen binding of ADP-activated platelets after traumatic hemorrhage analyzed by flow cytometry (P < .05). Conclusions This traumatic hemorrhage model presents two parallel pathophysiological responses of platelets; platelet consumption as evidenced by a significant decrease in platelet count and aggregation, and platelet hyperreactivity as shown by a higher mean platelet volume and enhanced platelet fibrinogen binding. Further studies are needed to characterize these different aspects of platelet function in severe traumatic hemorrhage.

463P - Evaluation of pharmacodynamic (PD) biomarkers in advanced cancer patients treated with oxidative phosphorylation (OXPHOS) inhibitor, OPC-317 (OPC)

BackgroundWe reported that metabolic reprogramming towards OXPHOS-induced drug resistance in oncogene-addicted tumors. OXPHOS is an attractive drug target but clinical PD markers of OXPHOS inhibition are lacking. We present interim PD biomarker data from a dose-finding/phase IIa study of OPC in an advanced cancer population enriched for molecular pathway-driven tumors. MethodsAfter the dose-finding phase of OPC monotherapy at 3 levels (600mg, 400mg, 300mg), the study is now enrolling HER2+ breast cancer, EGFR+ NSCLC and c-KIT+ GIST patients to receive OPC 300mg, 3x/week, 21 days, in combination with their respective pathway inhibitors. Baseline (BL) and C1D15 tumor biopsies were analysed for mitochondrial DNA (mtDNA) copy number [qPCR] and immunohistochemistry (IHC) markers of mitochondrial biogenesis/OXPHOS [PGC1α, TFAM, SIRT1] and cancer stem cells [ALDH1A2]. Blood collected on days 1, 4/5 and 11/12 was analysed by flow cytometry of PBMCs for mitochondrial membrane potential (MMP) and serum metabolomics of amino/organic acids by LC-MS/GC-MS. Results13 patients (8 with molecular pathway-activated cancers) have been enrolled so far; 5 had evaluable paired biopsies. There were no G3/4 toxicities at the 300mg dose level (n=8). Tumor mtDNA copy number declined significantly with treatment (-45.0+6.0%, C1D15 vs BL, p=0.006). The expected decrease in IHC expression of ALDH1A2, TFAM, PGC1α (C1D15 vs BL) occurred in 80% (4/5), 60% (3/5) and 40% (2/5), respectively; expected rebound increase in SIRT1 expression was seen in 80% (4/5). Serum metabolomics (C1D4 vs BL) showed significant increase in TCA intermediates, citrate (+18.7+14.2%, p=0.004) and fumarate (+29.7+37.1%, p=0.043), indicative of NADH accumulation following OXPHOS inhibition. There was a non-significant rise in serum lactate (+17.2+ 27.1%, p=0.094) and reduction in PBMC MMP [0.71+0.67 vs 0.29+0.23, BL vs C1D11/12, p=0.068] (n=11). ConclusionsWe identified novel tumor/blood PD biomarkers with clear evidence of target modulatory effects at clinically tolerable doses of OPC. With validation, they can aid the clinical development of OXPHOS inhibitors as a novel class of cancer therapy. Clinical trial identificationNCT03158324. Legal entity responsible for the studyOtsuka Pharmaceutical Co. Ltd. FundingOtsuka Pharmaceutical Co. Ltd. DisclosureD.S. Tan: Honoraria (self): Roche; Honoraria (self), Research grant / Funding (institution): Bayer; Honoraria (self): MSD; Honoraria (self): Genmab; Honoraria (self), Research grant / Funding (institution): AstraZeneca; Honoraria (self): Merck Serono; Honoraria (self): Tessa Therapeutics; Honoraria (self): Novartis; Research grant / Funding (self): Karyopharm. R. Sundar: Honoraria (self): MSD; Honoraria (self), Advisory / Consultancy: Bristol-Myers Squibb; Honoraria (self): Lilly; Advisory / Consultancy: Eisai; Research grant / Funding (self): Paxman; Travel / Accommodation / Expenses: Roche; Travel / Accommodation / Expenses: AstraZeneca; Travel / Accommodation / Expenses: Taiho Pharmaceutical. J.S. Lim: Advisory / Consultancy: Pfizer; Advisory / Consultancy, Travel / Accommodation / Expenses: Novartis; Research grant / Funding (institution): Synthon; Travel / Accommodation / Expenses: AstraZeneca. N. Ohi: Full / Part-time employment: Fujii Memorial Research Institute, Otsuka Pharmaceutical Co. Ltd., Shiga, Japan. T. Tsunoda: Full / Part-time employment: Otsuka Pharmaceutical Co. Ltd., Tokyo, Japan. B. Goh: Research grant / Funding (institution): Otsuka Pharmaceutical Co. Ltd. A.L. Wong: Honoraria (self), Advisory / Consultancy, Travel / Accommodation / Expenses: Pfizer; Honoraria (self), Advisory / Consultancy: Novartis; Travel / Accommodation / Expenses: Eisai; Research grant / Funding (institution): Otsuka Pharmaceutical Co Ltd. All other authors have declared no conflicts of interest.