Changes In Lactate Concentrations Research Articles

Post hospital admission blood lactate measurements are associated with mortality but not neurologic morbidity in children with cerebral malaria.

In children with cerebral malaria (CM) admission blood lactate has previously guided intravenous fluid therapy and been validated as a prognostic biomarker associated with death. The usefulness of post-admission measurements of blood lactate in children with CM is less clear. The strength of association between blood lactate and neurological sequelae in CM survivors, as well as the optimal duration of post-admission measurements of blood lactate to identify children at higher risk of adverse outcomes is unknown. A retrospective cohort study of 1674 Malawian children with CM hospitalized from 2000 to 2018 who had blood lactate measurements every 6h for the first 24h after admission was performed. The strength of association between admission lactate or values measured at any time point in the first 24h post-admission and outcomes (mortality and neurological morbidity in survivors) was estimated. The duration of time after admission that lactate remained a valid prognostic biomarker was assessed. When lactate is analysed as a continuous variable, children with CM who have higher values at admission have a 1.05-fold higher odds (95% CI 0.99-1.11) of death compared to those with lower lactate values. Children with higher blood lactate at 6h have 1.16-fold higher odds (95% CI 1.09-1.23) of death, compared to those with lower values. If lactate levels are dichotomized into hyperlactataemic (lactate > 5.0 mmol/L) or not, the strength of association between admission lactate and mortality increases (OR = 2.49, 95% CI 1.47-4.22). Blood lactate levels obtained after 18h post-admission are not associated with outcomes. Similarly, the change in lactate concentrations through time during the first 24h of hospital admission is not associated with outcomes. Blood lactate during hospitalization is not associated with adverse neurologic outcomes in CM survivors. In children with CM, blood lactate is associated with death but not neurologic morbidity in survivors. To comprehensively estimate prognosis, blood lactate in children with CM should be assessed at admission and for 18h afterwards.

Visual ratiometric fluorescence sensing of L-lactate in sweat by Eu-MOF and the design of logic devices

Using 1, 4-H2NDC as ligand and Eu as the center metal, the lanthanide MOF Eu-NDC was synthesized by hydrothermal method. The material showed a fast ratiometric response to L-lactate, and the fluorescence of the material varied from red to blue with the growth of lactate concentration, which can be used as a fluorescent sensor for L-lactate in sweat. The sensor exhibited good fluorescence stability to interfering components in human sweat and good detection limits for lactate in artificial sweat. Based on this, a visualized molecular logic gate that can monitor sweat lactate levels was constructed, and the material's characteristic of showing different colors with lactate concentration changes was used to indicate possible hypoxia during exercise, opening a new path for combining sweat lactate monitoring with smart molecular devices.

In vivo calibration of genetically encoded metabolite biosensors must account for metabolite metabolism during calibration and cellular volume.

Isotopic assays of brain glucose utilization rates have been used for more than four decades to establish relationships between energetics, functional activity, and neurotransmitter cycling. Limitations of these methods include the relatively long time (1-60 min) for the determination of labeled metabolite levels and the lack of cellular resolution. Identification and quantification of fuels for neurons and astrocytes that support activation and higher brain functions are a major, unresolved issues. Glycolysis is preferentially up-regulated during activation even though oxygen level and supply are adequate, causing lactate concentrations to quickly rise during alerting, sensory processing, cognitive tasks, and memory consolidation. However, the fate of lactate (rapid release from brain or cell-cell shuttling coupled with local oxidation) is long disputed. Genetically encoded biosensors can determine intracellular metabolite concentrations and report real-time lactate level responses to sensory, behavioral, and biochemical challenges at the cellular level. Kinetics and time courses of cellular lactate concentration changes are informative, but accurate biosensor calibration is required for quantitative comparisons of lactate levels in astrocytes and neurons. An in vivo calibration procedure for the Laconic lactate biosensor involves intracellular lactate depletion by intravenous pyruvate-mediated trans-acceleration of lactate efflux followed by sensor saturation by intravenous infusion of high doses of lactate plus ammonium chloride. In the present paper, the validity of this procedure is questioned because rapid lactate-pyruvate interconversion in blood, preferential neuronal oxidation of both monocarboxylates, on-going glycolytic metabolism, and cellular volumes were not taken into account. Calibration pitfalls for the Laconic lactate biosensor also apply to other metabolite biosensors that are standardized in vivo by infusion of substrates that can be metabolized in peripheral tissues. We discuss how technical shortcomings negate the conclusion that Laconic sensor calibrations support the existence of an in vivo astrocyte-neuron lactate concentration gradient linked to lactate shuttling from astrocytes to neurons to fuel neuronal activity.

Impact of varying lactate concentration in sweat on thermo-physiological comfort of multi-layered ensembles

PurposeSweating is thermo-regulatory behaviour that occurs when a person performs vigorous activity even in cold climatic condition. One of important component of sweat is the presence of lactate. Based on climatic condition, age, gender, maturity and nature of activity level, the change in lactate concentration is inevitable. Hence, the present study is focussed on the impact of change in the lactate concentration on the moisture transmission behaviour through the clothing. The purpose of this paper is to investigate the impact of changing lactate concentration on the moisture vapour transmission behaviour through multi-layered clothing ensembles.Design/methodology/approachFor the investigation, sweat solution representing male and female sweat were taken for present study. Two different multi-layered ensembles consisting of either spacer or fleece as middle layer were considered. The water vapour permeability and drying rate test were done at standard atmospheric conditions. After testing, ANOVA analysis was done in order to determine the most significant parameters.FindingsFabric structure (constituent layers) behaved differently when tested individually and as the layered component with different sweat solutions. Water vapour permeability of sweat solution with higher lactate concentration was lower as compared to sweat solution with lower lactate concentration. Individual layers showed higher rate of vapour permeability with sweat solution containing lower lactate concentration as compared to multi-layered ensembles. Role of PU coated nylon fabric was predominant in case of multi-layered ensembles. Difference in transmission of sweat solution was found higher in case of uni-directional stitched multi-layer spacer ensembles whereas marginal difference was observed in case of bi-directional seamed multi-layer spacer ensemble. Drying rate of sweat containing lower concentration of lactate was higher as compared to the other sweat solution for all the selected fabrics. Density of liquid and amount of the water available for drying influenced the drying behaviour and thus accounted for difference in drying rate of sweat solution differing in the lactate concentration. The contribution percentage of layers, i.e. type of structure was higher (nearly 93–96%) compared to that of solution type (3.3–4.9%) in case of individual layers whereas in the case of the multi-layer ensembles; type of seam had maximum contribution percentage (71–77%) followed by solution type (10–15%). Type of layers had least contribution percentage (nearly 7–9%).Practical implicationsThe findings from the study are expected to be realistic and important in designing and development of cold weather garment ensemble for different gender type depending on their activity level especially in case of military personnel and those performing combat activities.Originality/valueThis experimental work based will provide the insight about the behaviour of actual sweat transmission through the layered fabric ensembles and ways to prevent the accumulation of moisture near to human skin surface by manufacturing suitable design structures (in terms of layering composition and seam patterns) per the morphology and requirement of specific consumers.

Characterization of Eight Bacterial Biosensors for Microbial Diagnostic and Therapeutic Applications.

The engineering of microbial cells to produce and secrete therapeutics directly in the human body, known as advanced microbial therapeutics, is an exciting alternative to current drug delivery routes. These living therapeutics can be engineered to sense disease biomarkers and, in response, deliver a therapeutic activity. This strategy allows for precise and self-regulating delivery of a therapeutic that adapts to the disease state of the individual patient. Numerous sensing systems have been characterized for use in prokaryotes, but a very limited number of advanced microbial therapeutics have incorporated such sensors. We characterized eight different sensors that respond to physiologically relevant conditions and molecules found in the human body in the probiotic strain Escherichia coli Nissle 1917. The resulting sensors were characterized under aerobic and anaerobic conditions and were demonstrated to be functional under gut-like conditions using the nematode Caenorhabditis elegans as an in vivo model. We show for the first time how a biosensor is able to detect in vivo the bile acid-like molecule Δ4-dafachronic acid, a small molecule in C. elegans that regulates lifespan. Furthermore, we exemplify how bacterial sensors can be used to dynamically report on changes in the intestinal environment of C. elegans, by demonstrating the use of a biosensor able to detect changes in lactate concentrations in the gut lumen of individual C. elegans. The biosensors presented in this study allow for dynamic control of expression in vivo and represent a valuable tool in further developing advanced microbiome therapeutics.

Short-Term Storage of Mobilized Peripheral Blood Stem Cells in a Closed System Changes the Microenvironment and May Affect the Quantity of CD34+ and CD34+CD38-CD45RA-CD90+ Cells

Hypoxic conditions preserve the multipotency and self-renewing capacity of murine bone marrow and human cord blood stem cells. Blood samples stored in sealed blood gas tubes become hypoxic as leukocytes metabolize and consume oxygen. Taken together, these observations suggest that peripheral blood stem cell (PBSC) samples stored under airtight conditions become hypoxic, and that the stem cells contained may undergo qualitative or quantitative changes. This study aimed to determine the effect of storage for 8 hours in a sealed system on PBSC samples. Granulocyte colony-stimulating factor-mobilized PBSC samples were collected prospectively from 9 patients with myeloma or amyloidosis prior to apheresis, followed by measurement of CO2, O2, hydrogen ion (pH), lactate, and glucose concentrations in the blood and immunophenotyping of stem cell and multipotent progenitor cell populations before and after 8 hours of storage in sealed blood collection tubes. Blood concentrations of O2 and glucose and pH measurements were significantly decreased, whereas concentrations of CO2 and lactate were significantly increased after storage. Significantly higher concentrations of CD34+ cells (552 ± 84 cells/106total nucleated cells [TNCs] versus 985 ± 143 cells/106TNCs; P=.03), CD34+CD38- cells (98 ± 32 cells/106TNCs versus 158 ± 52 cells/106TNCs; P=.03), CD34+CD38+ cells (444 ± 92 cells/106TNCs versus 789 ± 153 cells/106TNCs; P=.03), and CD34+CD38-CD45RA-CD90+ cells (55 ± 17 cells/106TNCs versus 89 ± 25 cells/106TNCs; P=.02) were detected after 8 hours of storage. The changes in concentrations of CD34+CD38+ cells and CD34+ cells were inversely associated with the change in glucose concentration (P=.003 and P < .001, respectively) and positively associated with the change in lactate concentration (P=.01 and P <.001, respectively) after 8 hours of airtight storage. Storage of PBSC samples in a sealed, airtight environment is associated with microenvironmental changes consistent with hypoxia and increased concentrations of immunophenotypically defined stem cells. These results may have clinical implications with regard to the collection and processing of stem cell products and warrant confirmation with functional and mechanistic studies.

A Platinized Carbon Fiber Microelectrode-Based Oxidase Biosensor for Amperometric Monitoring of Lactate in Brain Slices.

Background: Direct and real-time monitoring of lactate in the extracellular space can help elucidate the metabolic and modulatory role of lactate in the brain. Compared to in vivo studies, brain slices allow the investigation of the neural contribution separately from the effects of cerebrovascular response and permit easy control of recording conditions. Methods: We have used a platinized carbon fiber microelectrode platform to design an oxidase-based microbiosensor for monitoring lactate in brain slices with high spatial and temporal resolution operating at 32 °C. Lactate oxidase (Aerococcus viridans) was immobilized by crosslinking with glutaraldehyde and a layer of polyurethane was added to extend the linear range. Selectivity was improved by electropolymerization of m-phenylenediamine and concurrent use of a null sensor. Results: The lactate microbiosensor exhibited high sensitivity, selectivity, and optimal analytical performance at a pH and temperature compatible with recording in hippocampal slices. Evaluation of operational stability under conditions of repeated use supports the suitability of this design for up to three repeated assays. Conclusions: The microbiosensor displayed good analytical performance to monitor rapid changes in lactate concentration in the hippocampal tissue in response to potassium-evoked depolarization.

EVALUATION OF PROGNOSTIC INDICATORS FOR INJURED TURTLES PRESENTING TO A WILDLIFE CLINIC.

The Turtle Rescue Team (TRT) at North Carolina State University College of Veterinary Medicine currently sees over 500 chelonian cases a year. Each turtle receives a thorough physical examination as the main evaluation of its health because further diagnostics are cost prohibitive in a donation-based facility. Thus, there is a need to further understand how a few economical diagnostics can evaluate the prognosis of chelonians. The objectives were to evaluate lactate, PCV, total solids, glucose, temperature, and HR as prognostic indicators in multiple chelonian species and to determine how the change in lactate concentrations over a 24 h period affects prognosis. Eastern box turtles (Terrapene carolina carolina), yellow-bellied sliders (Trachemys scripta scripta), river cooters (Pseudemys concinna), painted turtles (Chrysemys picta), and common snapping turtles (Chelydra serpentina) were evaluated because of prevalence of presentation to the TRT, differences in habitat, and differences in physiology. Hyperlactatemia, an increased lactate over 24 h when the initial lactate concentration was greater than 5 mM/L, and anemia were determined to be significant prognostic indicators of mortality for all turtles, and hypoglycemia was a significant prognostic indicator of mortality for male turtles (P < 0.05).

Simultaneous detection of metabolite concentration changes, water BOLD signal and pH changes during visual stimulation in the human brain at 9.4T

This study presents a method to directly link metabolite concentration changes and BOLD response in the human brain during visual stimulation by measuring the water and metabolite signals simultaneously. Therefore, the metabolite-cycling (MC) non-water suppressed semiLASER localization technique was optimized for functional 1H MRS in the human brain at 9.4 T. Data of 13 volunteers were acquired during a 26:40 min visual stimulation block-design paradigm. Activation-induced BOLD signal was observed in the MC water signal as well as in the NAA-CH3 and tCr-CH3 singlets. During stimulation, glutamate concentration increased 2.3 ± 2.0% to a new steady-state, while a continuous increase over the whole stimulation period could be observed in lactate with a mean increase of 35.6 ± 23.1%. These increases of Lac and Glu during brain activation confirm previous findings reported in literature. A positive correlation of the MC water BOLD signal with glutamate and lactate concentration changes was found. In addition, a pH decrease calculated from a change in the ratio of PCr to Cr was observed during brain activation, particularly at the onset of the stimulation.

Investigation of Lactate, Heart Rate and Handgrip Force Responses of Climbers

Abstract Introduction. Sport climbing, which is included in 2020 Olympic Games, is a new sport that is both recreational and performance-focused while being the subject of scientific research all around the world. The aim of this study was to analyze the changes in lactate concentration, heart rate and handgrip forces all at once in the actual sport climbing competition. Material and Methods. Thirteen male climbers volunteered for this study. The climbers climbed three different routes prepared according to the International Federation of Sport Climbing standards that are classified as easy, medium and difficult. Lactate, heart rate, dominant and non-dominant handgrip forces were measured for each route before climbing, immediately after, and during the third and fifth minutes after climbing. Climbing performance was determined using the number of holds that the competitor reached. Results. We observed significantly higher post-lactate concentration in comparison to the pre-climbing values for all climbing routes (p &lt; 0.05). Statistical observation shows that post-climbing heart rate values were considerably higher than the pre-climbing values for all three climbing trials (p &lt; 0.05). There were also statistically significant differences in climbing performance and handgrip force between the three routes (p &lt; 0.05). Conclusions. According to the results of this study, significant increases were noted in all three climbing routes relative to the pre-climb in lactate, heart rate and climbing performance data between the routes.

Renin Kinetics Are Superior to Lactate Kinetics for Predicting In-Hospital Mortality in Hypotensive Critically Ill Patients.

Whole blood lactate concentration is widely used in shock states to assess perfusion. We aimed to determine if the change in plasma renin concentration over time would be superior to the change in lactate concentration for predicting in-hospital mortality in hypotensive patients on vasopressors. Prospective, observational cohort study. Tertiary academic ICU. Adult patients on vasopressors for greater than 6 hours to maintain a mean arterial pressure greater than or equal to 65 mm Hg during January 2020. Plasma renin concentrations were measured at enrollment and at 24, 48, and 72 hours. Whole blood lactate measurements were performed according to normal standard of care. Logistic regression was performed to evaluate whether the change in renin or lactate concentration could predict in-hospital mortality. Generalized estimating equations were used to analyze the association between renin and lactate concentration and in-hospital mortality. The area under the receiver operating characteristics curve was performed to measure the discriminative ability of initial and peak renin and lactate concentration to predict mortality. The association between renin and lactate concentration above the upper limit of normal at each timepoint with in-hospital mortality was also examined. The study included 197 renin and 148 lactate samples obtained from 53 patients. The slope of the natural log (ln) of renin concentration was independently associated with mortality (adjusted odds ratio, 10.35; 95% CI, 1.40-76.34; p = 0.022), but the slope of ln-lactate concentration was not (adjusted odds ratio, 4.78; 95% CI, 0.03-772.64; p = 0.55). The generalized estimating equation models found that both ln-renin (adjusted odds ratio, 1.18; 95% CI, 1.02-1.37; p = 0.025) and ln-lactate (adjusted odds ratio, 2.38; 95% CI, 1.05-5.37; p = 0.037) were associated with mortality. Area under the receiver operating characteristics curve analysis demonstrated that initial renin could predict in-hospital mortality with fair discrimination (area under the receiver operating characteristics curve, 0.682; 95% CI, 0.503-0.836; p = 0.05), but initial lactate could not (area under the receiver operating characteristics curve, 0.615; 95% CI, 0.413-0.803; p = 0.27). Peak renin (area under the receiver operating characteristics curve, 0.728; 95% CI, 0.547-0.888; p = 0.01) and peak lactate (area under the receiver operating characteristics curve, 0.746; 95% CI, 0.584-0.876; p = 0.01) demonstrated moderate discrimination. There was no significant difference in discriminative ability between initial or peak renin and lactate concentration. At each study time point, a higher proportion of renin values exceeded the threshold of normal (40 pg/mL) in nonsurvivors than in survivors, but this association was not significant for lactate. Although there was no significant difference in the performance of renin and lactate when examining the absolute values of each laboratory, a positive rate of change in renin concentration, but not lactate concentration, over 72 hours was associated with in-hospital mortality. For each one-unit increase in the slope of ln-renin, the odds of mortality increased 10-fold. Renin levels greater than 40 pg/mL, but not lactate levels greater than 2 mmol/L, were associated with in-hospital mortality. These findings suggest that plasma renin kinetics may be superior to lactate kinetics in predicting mortality of hypotensive, critically ill patients.

No effect of resveratrol in patients with mitochondrial myopathy: A cross-over randomized controlled trial.

Mitochondrial myopathies (MM) are caused by mutations that typically affect genes involved in oxidative phosphorylation. Main symptoms are exercise intolerance and fatigue. Currently, there is no specific treatment for MM. Resveratrol (RSV) is a nutritional supplement that in preclinical studies has been shown to stimulate mitochondrial function. We hypothesized that RSV could improve exercise capacity in patients with MM. The study design was randomized, double-blind, cross-over and placebo-controlled. Eleven patients with genetically verified MM were randomized to receive either 1000 mg/day RSV or placebo (P) for 8 weeks followed by a 4-week washout and then the opposite treatment. Primary outcomes were changes in heart rate (HR) during submaximal cycling exercise and peak oxygen utilization (VO2 max) during maximal exercise. Secondary outcomes included reduction in perceived exertion, changes in lactate concentrations, self-rated function (SF-36) and fatigue scores (FSS), activities of electron transport chain complexes I and IV in mononuclear cells and mitochondrial biomarkers in muscle tissue among others. There were no significant differences in primary and secondary outcomes between treatments. Mean HR changes were -0.3 ± 4.3 (RSV) vs 1.8 ± 5.0 bpm (P), P=.241. Mean VO2 max changes were 0.7 ± 1.4 (RSV) vs -0.2 ± 2.3 mL/min/kg (P), P=.203. The study provides evidence that 1000 mg RSV daily is ineffective in improving exercise capacity in adults with MM. These findings indicate that previous in vitro studies suggesting a therapeutic potential for RSV in MM, do not translate into clinically meaningful effects in vivo.

Fiber-Based Electrochemical Biosensors for Monitoring pH and Transient Neurometabolic Lactate.

Developing tools that are able to monitor transient neurochemical dynamics is important to decipher brain chemistry and function. Multifunctional polymer-based fibers have been recently applied to monitor and modulate neural activity. Here, we explore the potential of polymer fibers comprising six graphite-doped electrodes and two microfluidic channels within a flexible polycarbonate body as a platform for sensing pH and neurometabolic lactate. Electrodes were made into potentiometric sensors (responsive to pH) or amperometric sensors (lactate biosensors). The growth of an iridium oxide layer made the fiber electrodes responsive to pH in a physiologically relevant range. Lactate biosensors were fabricated via platinum black growth on the fiber electrode, followed by an enzyme layer, making them responsive to lactate concentration. Lactate fiber biosensors detected transient neurometabolic lactate changes in an in vivo mouse model. Lactate concentration changes were associated with spreading depolarizations, known to be detrimental to the injured brain. Induced waves were identified by a signature lactate concentration change profile and measured as having a speed of ∼2.7 mm/min (n = 4 waves). Our work highlights the potential applications of fiber-based biosensors for direct monitoring of brain metabolites in the context of injury.

A novel device for detecting anaerobic threshold using sweat lactate during exercise

The lactate threshold (LT1), which is defined as the first rise in lactate concentration during incremental exercise, has not been non-invasively and conveniently determined in a clinical setting. We aimed to visualize changes in lactate concentration in sweat during exercise using our wearable lactate sensor and investigate the relationship between the lactate threshold (LT1) and ventilatory threshold (VT1). Twenty-three healthy subjects and 42 patients with cardiovascular diseases (CVDs) were enrolled. During exercise, the dynamic changes in lactate values in sweat were visualized in real-time with a sharp continuous increase up to volitional exhaustion and a gradual decrease during the recovery period. The LT1 in sweat was well correlated with the LT1 in blood and the VT1 (r = 0.92 and 0.71, respectively). In addition, the Bland–Altman plot described no bias between the mean values (mean differences: − 4.5 and 2.5 W, respectively). Continuous monitoring of lactate concentrations during exercise can provide additional information for detecting the VT1.

Metabolomics revealed the influence of breast cancer on lymphatic endothelial cell metabolism, metabolic crosstalk, and lymphangiogenic signaling in co-culture

Breast cancer metastasis occurs via blood and lymphatic vessels. Breast cancer cells ‘educate’ lymphatic endothelial cells (LECs) to support tumor vascularization and growth. However, despite known metabolic alterations in breast cancer, it remains unclear how lymphatic endothelial cell metabolism is altered in the tumor microenvironment and its effect in lymphangiogenic signaling in LECs. We analyzed metabolites inside LECs in co-culture with MCF-7, MDA-MB-231, and SK-BR-3 breast cancer cell lines using ^1hbox {H} nuclear magnetic resonance (NMR) metabolomics, Seahorse, and the spatial distribution of metabolic co-enzymes using optical redox ratio imaging to describe breast cancer-LEC metabolic crosstalk. LECs co-cultured with breast cancer cells exhibited cell-line dependent altered metabolic profiles, including significant changes in lactate concentration in breast cancer co-culture. Cell metabolic phenotype analysis using Seahorse showed LECs in co-culture exhibited reduced mitochondrial respiration, increased reliance on glycolysis and reduced metabolic flexibility. Optical redox ratio measurements revealed reduced NAD(P)H levels in LECs potentially due to increased NAD(P)H utilization to maintain redox homeostasis. ^{13}hbox {C}-labeled glucose experiments did not reveal lactate shuttling into LECs from breast cancer cells, yet showed other ^{13}hbox {C} signals in LECs suggesting internalized metabolites and metabolic exchange between the two cell types. We also determined that breast cancer co-culture stimulated lymphangiogenic signaling in LECs, yet activation was not stimulated by lactate alone. Increased lymphangiogenic signaling suggests paracrine signaling between LECs and breast cancer cells which could have a pro-metastatic role.

Time-weighted lactate as a predictor of adverse outcome in acute heart failure.

AimsThe role of dynamic changes in lactate concentrations on prognosis in acute heart failure has been poorly investigated. The aim of this study was to explore the predictive value of 24 h time‐weighted lactate (LACTW) in patients with acute heart failure.Methods and resultsNinety‐six consecutive acute heart failure patients presenting to the Emergency Department of San Paolo Hospital, Naples, Italy, were prospectively enrolled. Arterial blood lactate was measured at admission and during the following 24 h at random time intervals. LACTW was obtained by the sum of the average lactate values among consecutive time points multiplied by the intervals between consecutive time points and dividing the sum by the total time (24 h). The outcome was a composite of need of admission to the intensive care unit, hospitalization duration >7 days, or intra‐hospital death. Admission lactate, maximum measured lactate, and LACTW were collected. Univariate and multivariate Cox regression analysis was applied to determine the hazard ratio (HR) of developing the outcome. Forty‐three patients experienced the pre‐specified outcome. In sex‐adjusted and age‐adjusted multivariable analysis, LACTW predicted the outcome occurrence (HR: 1.51, 95% confidence interval: 1.24, 1.84, P < 0.001). Risk stratification analysis based on LACTW tertiles demonstrated a gradual increase in risk of developing the outcome (HR: 17.32, 95% confidence interval: 2.30, 130.23, P = 0.006) for the highest LACTW tertile.ConclusionsIn acute heart failure patients, 24 h LACTW had a significant independent predictive value for adverse intra‐hospital outcome. LACTW could be a useful index at identifying high‐risk patients who may require a more aggressive treatment during hospitalization.

Investigations into the Effects of pH on Quantitative Measurements of Lactate in Biological Media Using ATR-FTIR Spectroscopy.

Quantification of lactate/lactic acid in critical care environments is essential as lactate serves as an important biochemical marker for the adequacy of the haemodynamic circulation in shock and of cell respiration at the onset of sepsis/septic shock. Hence, in this study, ATR-FTIR was explored as a potential tool for lactate measurement, as the current techniques depend on sample preparation and fails to provide rapid response. Moreover, the effects of pH on PBS samples (7.4, 7, 6.5 and 6) and change in solution conditions (PBS to whole blood) on spectral features were also investigated. A total 189 spectra from five sets of lactate containing media were obtained. Results suggests that lactate could be measured with more than 90% accuracy in the wavenumber range of 1500–600 cm. The findings of this study further suggest that there exist no effects of change in pH or media, when estimating lactate concentration changes in this range of the Mid-IR spectral region.

Effect of Aging on Daily Rhythms of Lactate Metabolism in the Medial Prefrontal Cortex of Male Mice

Aging is associated with reduced amplitude and earlier timing of circadian (daily) rhythms in sleep, brain function, and behavior. We examined whether age-related circadian dysfunction extends to the metabolic function of the brain, particularly in the prefrontal cortex (PFC). Using enzymatic amperometric biosensors, we recorded lactate concentration changes in the PFC in Young (7 mos) and Aged (19 mos) freely-behaving C57BL/6N male mice. Both Young and Aged mice displayed diurnal and circadian rhythms of lactate, with the Aged rhythm slightly phase advanced. Under constant conditions, the Aged rhythm showed a reduced amplitude not seen in the Young mice. We simultaneously observed a relationship between arousal state and PFC lactate rhythm via electroencephalography, which was modified by aging. Finally, using RT-qPCR, we found that aging affects the daily expression pattern of Glucose Transporter 1 (GLUT-1).

A Self-Powered Biosensor for Monitoring Maximal Lactate Steady State in Sport Training

A self-powered biosensor for monitoring the maximal lactate steady state (MLSS) during exercise has been developed for intelligently assisting training system. It has been presented to create poly (vinylidene fluoride) (PVDF)/Tetrapod-shaped ZnO (T-ZnO)/enzyme-modified nanocomposite film through an efficient and cost-effective fabrication process. This sensor can be readily attached to the skin surface of the tester. Due to the piezoelectric surface coupling effect, this biosensor can monitor/sense and analyze physical information in real-time under the non-invasive condition and work independently without any battery. By actively outputting piezoelectric signals, it can quickly and sensitively detect body movements (changes of joint angle, frequency relative humidity during exercise) and physiological information (changes of lactate concentration in sweat). A practical application has been demonstrated by an excellent professional speed skater (male). The purpose of this study is to increase the efficiency of MLSS evaluation, promote the development of piezoelectric surface coupling effect and motion monitoring application, develop an intelligently assisting training system, which has opened up a new direction for human motion monitoring.

Near Infrared and Aquaphotomic analysis of water absorption in lactate containing media.

Increased concentrations of lactate levels in blood are often seen in patients with life-threatening cellular hypoperfusion or infections. State-of-the-art techniques used in clinical practice for measuring serum lactate concentrations rely on intermittent blood sampling and do not permit continuous monitoring of this all important parameter in critical care environments.In recent years, Near Infrared (NIR) Spectroscopy has been established as a possible alternative to existing methods that can mitigate these constraints and be used for non-invasive continuous monitoring of lactate. Nevertheless, the dominant absorption of -OH overtone bands of water in the NIR presents a challenge and complicates the accurate detection of other absorbers such as lactate. For this reason, comprehensive analysis of the -OH overtone bands with systematic lactate concentration changes is essential. This paper reports on the analysis of NIR spectra of two aqueous systems of varying concentrations of lactate in saline and whole blood using the principles of Aquaphotomics.The results show distinctive conformational and structural differences in lactate-water binding, which arise due to the molecular interactions of bonds present in respective solvents.