Metabolic Rate Research Articles

Are haloclines distributional barriers in anchialine ecosystems? Physiological response of cave shrimps to salinity.

Anchialine systems are coastal groundwater habitats around the world which host a unique community of cave adapted species (stygobionts). Such communities are expected to be separated by haloclines into either fresh or saline groundwater communities, hence climate changes (e.g., eustatic sea level shifts) and anthropic driven changes (e.g., salinization) may have a great impact on these stygobiont communities. Here we used cave-restricted species of Typhlatya from the Yucatan Peninsula as models to identify physiological capacities that enable the different species to thrive in marine groundwater (T. dzilamensis) or fresh groundwater (T. mitchelli and T. pearsei), and test if their distribution is limited by their salinity tolerance capacity. We used behavior, metabolic rates, indicators of the antioxidant system and cellular damage, and lactate content to evaluate the response of individuals to acute changes in salinity, as a recreation of crossing a halocline in the anchialine systems of the Yucatan Peninsula. Our results show that despite being sister species, some are restricted to the freshwater portion of the groundwater, while others appear to be euryhaline.

Prevalence and clinical correlates of abnormal lipid metabolism in older Chinese patients with first-episode drug-naïve major depressive disorder

BackgroundOlder major depressive disorder (MDD) patients have more complex clinical symptoms and higher abnormal lipid metabolism (ALM) rates. This study aimed to compare clinical differences between those with and without ALM in a sample of older first-episode drug naïve (FEDN) patients.MethodsWe recruited 266 older MDD patients. Socio-demographic variables, clinical data, and lipid parameters were obtained. The Hamilton Depression Rating Scale (HAMD), Hamilton Anxiety Rating Scale (HAMA), and the positive subscale of the Positive and Negative Syndrome Scale (PANSS-P) were conducted to evaluate patients’ depression, anxiety and psychotic symptoms, respectively.ResultsIn this study, we found that the prevalence of comorbid ALM was 86.1% in older MDD patients. Compared with the non-abnormal lipid metabolism (NALM) group, the ALM group had a higher duration of illness, higher clinical global impression of severity scale (CGI-S) and HAMD scores, higher thyroid stimulating hormone (TSH) and glucose levels. Logistic regression analysis indicated that duration of illness (OR = 1.11, P = 0.023, 95%CI = 1.015–1.216) and CGI-S score (OR = 2.28, P = 0.014, 95%CI = 1.18–4.39) were associated with ALM in older MDD patients.ConclusionThe importance of regular lipid assessment in older MDD patients needs to be taken into account.

Glucagon Clearance is Decreased in Chronic Kidney Disease, but Preserved in Liver Cirrhosis.

It is not completely clear which organs are responsible for glucagon elimination in humans, and disturbances in the elimination of glucagon could contribute to the hyperglucagonemia observed in chronic liver disease and chronic kidney disease (CKD). Here, we evaluated kinetics and metabolic effects of exogenous glucagon in individuals with stage 4 CKD (n =16), individuals with Child-Pugh A-C cirrhosis (n = 16) and matched control individuals (n = 16), before, during and after a 60-minute glucagon infusion (4 ng/kg/min). Individuals with CKD exhibited a significantly lower mean metabolic clearance rate of glucagon (14.0 [95% CI 12.2;15.7] mL/kg/min) both compared to individuals with cirrhosis (19.7 [18.1;21.3] mL/kg/min, P < 0.001) and to control individuals (20.4 [18.1;22.7] mL/kg/min, P < 0.001). Glucagon half-life was significantly prolonged in the CKD group (7.5 [6.9;8.2] minutes) compared to individuals with cirrhosis (5.7 [5.2;6.3] minutes, P = 0.002) and control individuals (5.7 [5.2;6.3] minutes, P < 0.001). No difference in the effects of exogenous glucagon on plasma glucose, amino acids, or triglycerides was observed between groups. In conclusion, chronic kidney disease, but not liver cirrhosis leads to a significant reduction in glucagon clearance, supporting the kidneys as a primary site for human glucagon elimination.

Effects of lead on avian thermoregulation in the heat: An experimental test with pied crows (Corvus albus)

Many of the negative physiological effects of lead involve the hypothalamus, but the possibility that thermoregulation is affected has received little attention. We tested the hypothesis that lead exposure reduces avian thermoregulatory performance under hot conditions in pied crows (Corvus albus) experimentally exposed to lead in their diet. Crows in our high lead treatment (blood [Pb] = 87.3 ± 44.7 μg dL−1) showed significantly higher air temperature (Tair) inflections for evaporative water loss (EWL) and resting metabolic rate (RMR) compared to control (6.4 ± 1.8 μg dL−1) or intermediate (53.9 ± 23.7 μg dL−1) lead groups, which did not differ. EWL, RMR and body temperature (Tb) all increased more rapidly at Tair >Tb in the high lead treatment. In contrast, neither maximum Tair tolerated by the crows nor maximum Tb varied with treatment. Our data reveal that water and energy balance during hot weather is affected by lead exposure.

The effect of time-restricted eating on arterial stiffness indices in men with metabolic syndrome: study protocol for a randomized controlled trial

BackgroundTime-restricted eating (TRE) has been shown to be associated with improvements in some aspects of the metabolic syndrome. Nevertheless, only a few studies have addressed the effect of TRE on pulse wave velocity (PWV). We thus propose a randomized controlled trial to compare the effects of TRE with standard dietary advice on PWV and thereby present the protocol.MethodsForty-eight participants will be assigned to either TRE or control groups using simple randomization. The TRE group will consume their meals during a 10-h period and experience 14 h of fasting. They will also be advised to consume their last meal no later than 20:00. Both groups will receive standard dietary advice. The participants will be followed for 6 weeks. The primary outcome will be changes in PWV. Laboratory measurements, including lipid profile, liver enzyme tests, fasting blood glucose (FBG), insulin concentrations, and insulin resistance, as well as anthropometric data, blood pressure, basal metabolic rate, appetite status, physical activity level, sleep quality, cognitive function, quality of life, and calorie intake, will be evaluated throughout the study.DiscussionThe outcomes of this study will allow a comparison of the effects of TRE and standard dietary recommendations on PWV and other cardiometabolic factors in individuals with metabolic syndrome (MetS).Trial registrationIranian Registry of Clinical Trials; code: IRCT20201230049889N1; registered on August 14, 2022. The registration of the trial is accessible at: https://www.IRCT.ir/trial/64485?revision=281341.

Acute effects of fast, slow, and graded Suryanamaskar on cardiorespiratory and cardiac autonomic functions

BackgroundSuryanamaskar (SN) is a popular yogic practice due to its health benefits and fitness promises. This study aims to assess the acute effects of different paces of SN on cardiorespiratory responses and heart rate variability (HRV). MethodsIn this self-as-control comparative study, seventeen male yoga practitioners performed three rounds of SN at fast (FSN), slow (SSN), and graded (GSN) pace in a randomly allocated sequence. Cardiorespiratory responses and HRV kinetics were continuously monitored using a metabolic gas analyzer and heart rate sensor, respectively, and were analyzed by repeated-measures ANOVA and paired t-test. ResultsFSN involved the highest VO2, followed by GSN and SSN. Average HR (AHR) was significantly greater during FSN compared to SSN (p < 0.01; d = 0.81) and GSN (p < 0.05; d = 0.39). GSN demanded significantly higher (p < 0.05; d = 0.41) stroke volume compared to FSN. VO2, AHR, and energy expenditure (EE) showed a gradual increase across rounds in FSN and SSN, whereas in GSN those significantly reduced. SSN showed significantly lesser EE, fat% utilization, and METS as compared to FSN (p < 0.001) and GSN (p < 0.01). SSN also showed significantly reduced LF power (p < 0.01; d = 0.67), LF/HF ratio, and higher HF power than GSN and FSN. ConclusionFSN is more metabolically demanding compared to the other two paces. SSN is more effective in bringing a state of parasympathetic dominance and GSN brings progressive relaxation. The results provide insights into the acute HRV and cardio-metabolic responses to different SN paces suggesting its potential as a complementary therapy and to promote holistic health and well-being.

Enhancing precision in bone metastasis diagnosis for lobular breast cancer: reassessing the role of 18F-FDG PET/CT.

Detection of osseous metastases by imaging can be challenging in patients with invasive lobular breast cancer (ILC). ILC may demonstrate low metabolic rate due to lower tumor cell density, decreased proliferation rate, diffuse infiltration of surrounding tissue, and low level of GLUT-1 expression. The aim of this study is to assess the diagnostic accuracy of 18F-FDG PET/CT in identifying bone metastases in ILC patients. Out of 52 individuals diagnosed with lobular breast cancer and underwent 18F-FDG PET/CT for evaluation of metastases, 21 patients were included in our study population after applying inclusion and exclusion criteria. The radiological and clinical follow-up of at least 6 months served as the reference standard comparator. Bone metastases were confirmed in six patients. 18F-FDG PET/CT was true positive in two and false negative in four patients. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 18F-FDG PET/CT were 33.33, 93.33, 66.67, 77.78, and 76.19%, respectively (95% confidence interval). The tendency of ILC osseous metastases to be more sclerotic explains the low diagnostic accuracy of 18F-FDG PET/CT in detection of bone metastases, making it a less suited method of evaluation. The results of the present study indicate that 18F-FDG PET/CT has a low diagnostic accuracy in detecting bone metastases in lobular breast cancer and, by inference, new functional modalities can be explored in these patients. The findings contribute valuable insights to optimize the integration of molecular imaging into the diagnostic algorithm for this specific breast cancer subtype.

A new human metabolic rate sensing model optimization and wearable sensor realization

Accurate assessment of metabolic rate is crucial for predicting human thermal comfort. However, many existing instruments are bulky, invasive, and inconvenient. Additionally, wearable metabolic rate measurements have faced long-standing challenges due to a lack of a comprehensive theoretical model with easy-to-measure parameters. This paper optimizes our previously proposed theoretical approach for wearable metabolic rate measurement that incorporates heart rate, whole-body unit heat loss, skin resistance, and body muscle percentage. We have improved the evaluation approach for whole-body unit heat loss by introducing a newly designed convective heat loss coefficient from various body segments. Regarding the wearable sensor design, a heat loss measuring system with serpentine channel was verified as the most suitable design following calibration experiments. We also integrated a modified square-wave-based skin resistance design, resulting in an upgraded integrated metabolic sensor. To validate our sensor and model performance, we conducted experiments with ten subjects of both genders at three temperature conditions (22, 25 and 28 °C) and four levels of activities (rest, tiptoe heel, slight walk, and moderate walk). First, our results demonstrate a strong positive relationship between the metabolic rate obtained by our optimized sensor and Quark CPET instrument, with high coefficients of determination (highest:0.97 from the male group, 0.98 from the female group). Our approach achieved at least 96 % accuracy and less than 2.5 % uncertainty for both groups. Second and increasingly, we found that only one metabolic rate model was required across combined temperature conditions when the person was fixed. Third, the positive relationship was further improved by incorporating whole-body unit heat loss. Finally, we obtained information from different segments on skin temperatures. In summary, our study provides a powerful methodology for predicting and evaluating human metabolic rate through an innovative wearable approach. Our approach and sensor have the potential to substantially contribute to energy-saving efforts in smart buildings.

Characterization of a Syngeneic Orthotopic Model of Cholangiocarcinoma by [18F]FDG-PET/MRI.

Cholangiocarcinoma (CCA) is a type of primary liver cancer originating from the biliary tract epithelium, characterized by limited treatment options for advanced cases and low survival rates. This study aimed to establish an orthotopic mouse model for CCA and monitor tumor growth using PET/MR imaging. Murine CCA cells were implanted into the liver lobe of male C57BL/6J mice. The imaging groups included contrast-enhanced (CE) MR, CE-MR with static [18F]FDG-PET, and dynamic [18F]FDG-PET. Tumor volume and FDG uptake were measured weekly over four weeks. Early tumor formation was visible in CE-MR images, with a gradual increase in volume over time. Dynamic FDG-PET revealed an increase in the metabolic glucose rate (MRGlu) over time. Blood analysis showed pathological changes in liver-related parameters. Lung metastases were observed in nearly all animals after four weeks. The study concludes that PET-MR imaging effectively monitors tumor progression in the CCA mouse model, providing insights into CCA development and potential treatment strategies.

PK/PD investigation of antiviral host matriptase/TMPRSS2 inhibitors in cell models

Certain corona- and influenza viruses utilize type II transmembrane serine proteases for cell entry, making these enzymes potential drug targets for the treatment of viral respiratory infections. In this study, the cytotoxicity and inhibitory effects of seven matriptase/TMPRSS2 inhibitors (MI-21, MI-463, MI-472, MI-485, MI-1900, MI-1903, and MI-1904) on cytochrome P450 enzymes were evaluated using fluorometric assays. Additionally, their antiviral activity against influenza A virus subtypes H1N1 and H9N2 was assessed. The metabolic depletion rates of these inhibitors in human primary hepatocytes were determined over a 120-min period by LC–MS/MS, and PK parameters were calculated. The tested compounds, with the exception of MI-21, displayed potent inhibition of CYP3A4, while all compounds lacked inhibitory effects on CYP1A2, CYP2C9, CYP2C19, and CYP2D6. The differences between the CYP3A4 activity within the series were rationalized by ligand docking. Elucidation of PK parameters showed that inhibitors MI-463, MI-472, MI-485, MI-1900 and MI-1904 were more stable compounds than MI-21 and MI-1903. Anti-H1N1 properties of inhibitors MI-463 and MI-1900 and anti-H9N2 effects of MI-463 were shown at 20 and 50 µM after 24 h incubation with the inhibitors, suggesting that these inhibitors can be applied to block entry of these viruses by suppressing host matriptase/TMPRSS2-mediated cleavage.

Metabolism of a fungicide propiconazole by Cunninghamella elegans ATCC36112.

The metabolic breakdown of propiconazole by fungi was examined, and it was found that the microbial model (Cunninghamella elegans ATCC36112) efficiently degrades the triazole fungicide propiconazole through the action of cytochrome P450. This enzyme primarily facilitates the oxidation and hydrolysis processes involved in phase I metabolism. We observed major metabolites indicating hydroxylation/oxidation of propyl groups of propiconazole. Around 98% of propiconazole underwent degradation within a span of 3days post-treatment, leading to the accumulation of five metabolites (M1-M5). The experiments started with a preliminary identification of propiconazole and its metabolites using GC-MS. The identified metabolites were then separated and identified by in-depth analysis using preparative UHPLC and MS/MS. The metabolites of propiconazole are M1 (CGA-118245), M2(CGA-118244), M3(CGA-136735), M4(GB-XLIII-42-1), and M5(SYN-542636). To further investigate the role of key enzymes in potential fungi, we treated the culture medium with piperonyl butoxide (PB) and methimazole (MZ), and then examined the kinetic responses of propiconazole and its metabolites. The results indicated a significant reduction in the metabolism rate of propiconazole in the medium treated with PB, while methimazole showed weaker inhibitory effects on the metabolism of propiconazole in the fungus C. elegans.

Metabolic rate and saliva cortisol concentrations in socially housed adolescent guinea pigs.

An individual's energetic demands and hence metabolic rate can strongly change during adolescence, a phase characterized by profound morphological, physiological, and endocrine changes. Glucocorticoid hormones (e.g. cortisol) are released in response to hypothalamic-pituitary-adrenal-axis activity, modulate several metabolic processes, and can also be linked to increased metabolic rate. In domestic guinea pigs (Cavia aperea f. porcellus) housed in same-sex groups, cortisol concentrations increase during adolescence in males but remain stable in females, which was suggested to be related to different energetic demands by age. We therefore measured metabolic rate through oxygen (O2) consumption over 2.5h in male and female guinea pigs housed in same-sex groups during adolescence at ages of 60, 120, and 180days, which was paralleled by analyses of saliva cortisol concentrations before and after the measurement. The statistical analyses involved whole body metabolic rate (ml O2/h), body mass-corrected metabolic rate (ml O2/h/kg), and body mass-independent metabolic rate (ml O2/h statistically corrected for body mass). We found increasing cortisol concentrations with age in males only, but none of the three metabolic rate analyses revealed a sex difference by age. On the individual level, repeatability across ages was found in metabolic rate as well as in body mass and cortisol concentrations after the measurement, but not in "basal" cortisol concentrations. Our results suggest no sex-specific changes in metabolic rate and hence equal energetic demands in male and female guinea pigs during adolescence. Moreover, metabolic rate clearly represents a highly stable physiological trait already early in a guinea pig's life irrespective of rather fluctuating cortisol concentrations.

Small RNA and Freeze Survival: The Cryoprotective Functions of MicroRNA in the Frozen Muscle Tissue of the Grey Tree Frog.

The grey tree frog, Dryophytes versicolor, survives whole-body freezing for weeks during cold winter months. Survival in a state devoid of available food, water, or oxygen forces a reliance on metabolic rate depression (MRD) and the reprioritization of bodily functions. This study utilizes next-generation sequencing (NGS) and bioinformatic analyses to characterize changes in the microRNAome of D. versicolor. When comparing control to frozen groups, five microRNAs (miRNA) were found to be differentially regulated (miR-143-3p, miR-30e-3p, miR-10a-5p, miR-140-3p, and miR-148a-3p), suggesting that they play key roles in freeze survival. The KEGG and GO analyses of these changes predicted a significant negative enrichment of terms associated with cell proliferation and active metabolism while simultaneously predicting the upregulation of cell signalling terms. These results suggest a fast-acting regulatory role for miRNA in contributing to the reorganization of gene expression and the limitation of energy-expensive processes during MRD in the hind leg skeletal muscle of the frog.

Pleiotropic effects of an eQTL in the CELSR2/PSRC1/SORT1 cluster that associates with LDL-C and resting metabolic rate.

The locus CELSR2-PSRC1-SORT1, a primary genetic signal for lipids, has recently been implicated in different metabolic processes. Our investigation identified its association with energy metabolism. To determine biological mechanisms that govern diverse functions of this locus. Genotypes for 491,265 variants in 7,000 clinically characterized American Indians were previously determined using a custom-designed array specific for this longitudinally studied American Indian population. Among the genotyped individuals, 5,205 had measures of fasting lipid levels and 509 had measures of resting metabolic rate (RMR) and substrate oxidation rate assessed through indirect calorimetry. A genome-wide association study (GWAS) for LDL-C levels identified a variant in CELSR2 and the molecular impact of this variant on gene expression was assessed in skeletal muscle biopsies from 207 participants, followed by functional validation in mouse myoblasts using a luciferase assay. A GWAS in American Indians identified rs12740374 in CELSR2 as the top signal for LDL-C levels (P = 1 × 10-22); further analysis of this variant identified an unexpected correlation with reduced RMR (effect = -44.3 kcal/day/minor-allele) and carbohydrate oxidation rate (effect = -5.21 mg/hour/kg-EMBS). Tagged variants showed a distinct linkage disequilibrium architecture in American Indians, highlighting a potential functional variant, rs6670347 (minor-allele frequency = 0.20). Positioned in the glucocorticoid receptor's core binding motif, rs6670347 is part of a skeletal muscle-specific enhancer. Human skeletal muscle transcriptome analysis showed CELSR2 as the most differentially expressed gene (P = 1.9 × 10-7), with the RMR-lowering minor allele elevating gene expression. Experiments in mouse myoblasts confirmed enhancer-based regulation of CELSR2 expression, dependent on glucocorticoids. Rs6670347 also associated with increased oxidative phosphorylation gene expression; CELSR2 as a regulator of these genes, suggests potential influence on energy metabolism through muscle oxidative capacity. Variants in the CELSR2/PSRC1/SORT1 locus exhibit tissue-specific effects on metabolic traits, with an independent role in muscle metabolism through glucocorticoid signaling.

The hard life of an octopus embryo is seen through gene expression, energy metabolism, and its ability to neutralize radical oxygen species

The reproductive process in Octopus maya was analyzed to establish the amount of reactive oxygen species that the embryos inherit from females, during yolk synthesis. At the same time, respiratory metabolism, ROS production, and the expression of some genes of the antioxidant system were monitored to understand the ability of embryos to neutralize maternal ROS and those produced during development. The results indicate that carbonylated proteins and peroxidized lipids (LPO) were transferred from females to the embryos, presumably derived from the metabolic processes carried out during yolk synthesis in the ovary. Along with ROS, females also transferred to embryos glutathione (GSH), a key element of the antioxidant defense system, thus facilitating the neutralization of inherited ROS and those produced during development. Embryos are capable of neutralizing ROS thanks to the early expression of genes such as catalase (CAT) and superoxide dismutase (SOD), which give rise to the synthesis of enzymes when the circulatory system is activated. Also, it was observed that the levels of the routine metabolic rate of embryos are almost as high as those of the maximum activity metabolism, which leads, on the one hand, to the elevated production of ROS and suggests that, at this stage of the life cycle in octopuses, energy production is maximum and is physically limited by the biological properties inherent to the structure of embryonic life (oxygen transfer through the chorion, gill surface, pumping capacity, etc.). Due to its role in regulating vascularization, a high expression of HIf-1A during organogenesis suggests that circulatory system development has begun in this phase of embryo development. The results indicate that the routine metabolic rate and the ability of O. maya embryos to neutralize the ROS are probably the maximum possible. Under such circumstances, embryos cannot generate more energy to combat the free radicals produced by their metabolism, even when environmental factors such as high temperatures or contaminants could demand excess energy.

Simultaneous and cumulative effects of tDCS on cerebral metabolic rate of oxygen in multiple sclerosis.

Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technique with simultaneous (during stimulation) and cumulative effects (after repeated sessions) on blood flow and neuronal metabolism. These effects remain mostly unclear especially in multiple sclerosis (MS). This work aims to elucidate brain metabolic and hemodynamic underpinnings of tDCS and its potential therapeutic impact in MS patients using quantitative tDCS-MRI. MS participants (n = 20; age = 45.4 ± 12.3 years, 7 males) underwent 3 T MRI scans before and after 20 daily sessions of dorsolateral prefrontal cortex (DLFPC) tDCS (2.0 mA, left anodal) paired with adaptive cognitive training (aCT). During both visits, imaging measurements of cerebral blood flow (CBF), cerebral venous blood oxygenation (Yv) and calculated cerebral metabolic rate of oxygen (CMRO2) were obtained at pre-tDCS, during-tDCS and post-tDCS. At baseline, significant increase from pre- to during-tDCS was observed in CMRO2 (7.6%; p = 0.002), CBF (11.0%; p < 0.0001) and Yv (1.9%; p = 0.006). At follow up, we observed an increase in pre-tDCS CMRO2 (140.59 ± 13.83 μmol/100 g/min) compared to baseline pre-tDCS levels (128.30 ± 14.00 μmol/100 g/min; p = 0.006). Sustained elevations in CMRO2 and CBF into post-tDCS were also observed (tDCS lingering effects). Cumulative tDCS effects were observed in the form of sustained elevations in CMRO2 and CBF in pre-tDCS follow up, reaching the magnitudes measured at baseline during-tDCS. TDCS induces an acute surge in metabolic activity persisting immediately after the stimulation is removed. Moreover, treatment composed of repeated tDCS-aCT paired sessions contributes to establishing long-lasting increases in neuronal activity.

Limnological Characteristics and Relationships with Primary Productivity in Two High Andean Hydroelectric Reservoirs in Ecuador

Studies on limnology are essential to reservoir management; nevertheless, few are known about the limnological features of the Andean reservoirs in Ecuador. To overcome this limitation in the information, from December 2018 to December 2019, the limnological characteristics of El Labrado and Chanlud reservoirs in the Machángara river basin (Ecuador south) were examined. Using the light/dark bottles technique, the primary productivity (PP) of phytoplankton was studied in conjunction with (1) vertical profiles of oxygen concentrations, water temperature, nitrogen, phosphorus, alkalinity, and heterotrophic bacteria; (2) Secchi disk transparency; and (3) meteorological factors such as wind force, precipitation, and water level. Data indicate that both reservoirs are polymictic, with alkaline waters, low nutrients, and low PP rates. Despite this, a principal component analysis revealed that Chanlud exhibits higher nitrogen, alkalinity, heterotrophic bacteria, and PP values. In two approaches through multiple linear regression analysis, each per reservoir, the PP was explained mainly by water temperature, depth, light, heterotrophic bacteria, and meteorological parameters. The low concentrations of nutrients and the low residency time explain the low PP values. Likewise, the altitudinal factor (i.e., both reservoirs are 3400 m above sea level) and the low human perturbations in surrounding reservoir zones play a crucial role in explaining their poor PP. Notwithstanding the low metabolic rates, clear seasonal trends were observed in both reservoirs; the lowest PP rates occurred during the cold season. To our knowledge, this is the first limnological study of high Andean reservoirs in Ecuador. These findings should be part of Andean reservoir management protocols, contributing significantly to local conservation efforts. Additionally, they could be extrapolated as a frame of reference to similar eco-hydrological systems.

Identification of prognostic imaging biomarkers in H3 K27-altered diffuse midline gliomas in adults: impact of tumor oxygenation imaging biomarkers on survival.

To investigate prognostic markers for H3 K27-altered diffuse midline gliomas (DMGs) in adults with clinical, qualitative and quantitative imaging phenotypes, including tumor oxygenation characteristics. Retrospective chart and imaging reviews were conducted on 32 adults with H3 K27-altered DMGs between 2017 and 2023. Clinical and qualitative imaging characteristics were analyzed. Quantitative imaging assessment was performed from the tumor mask via automatic segmentation to calculate normalized cerebral blood volume (nCBV), capillary transit time heterogeneity (CTH), oxygen extraction fraction (OEF), relative cerebral metabolic rate of oxygen (rCMRO2), and mean ADC values. Leptomeningeal metastases (LM) was diagnosed with imaging. Cox analyses were conducted to determine predictors of overall survival (OS) in entire patients and a subgroup of patients with contrast-enhancing (CE) tumor. The median patient age was 40.5 years (range 19.9-75.7), with an OS of 30.3 months (interquartile range 11.3-32.3). In entire patients, the presence of LM was the only independent predictor of OS (hazard ratio [HR] = 6.01, P = 0.009). In the subgroup of 23 (71.9%) patients with CE tumors, rCMRO2 of CE tumor (HR = 1.08, P = 0.019) and the presence of LM (HR = 5.92, P = 0.043) were independent predictors of OS. The presence of LM was independently associated with poor prognosis in adult patients with H3 K27-altered DMG. In patients with CE tumors, higher rCMRO2 of CE tumor, which may reflect higher metabolic activity in the tumor oxygenation microenvironment, may be a useful imaging biomarker to predict poor prognosis.

Noninvasive Quantification of Glucose Metabolism in Mice Myocardium Using the Spline Reconstruction Technique.

The spline reconstruction technique (SRT) is a fast algorithm based on a novel numerical implementation of an analytic representation of the inverse Radon transform. The purpose of this study was to compare the SRT, filtered back-projection (FBP), and the Tera-Tomo 3D algorithm for various iteration numbers, using small-animal dynamic PET data obtained from a Mediso nanoScan® PET/CT scanner. For this purpose, Patlak graphical kinetic analysis was employed to noninvasively quantify the myocardial metabolic rate of glucose (MRGlu) in seven male C57BL/6 mice (n=7). All analytic reconstructions were performed via software for tomographic image reconstruction. The analysis of all PET-reconstructed images was conducted with PMOD software (version 3.506, PMOD Technologies LLC, Fällanden, Switzerland) using the inferior vena cava as the image-derived input function. Statistical significance was determined by employing the one-way analysis of variance test. The results revealed that the differences between the values of MRGlu obtained via SRT versus FBP, and the variants of he Tera-Tomo 3D algorithm were not statistically significant (p > 0.05). Overall, the SRT appears to perform similarly to the other algorithms investigated, providing a valid alternative analytic method for preclinical dynamic PET studies.

Ontogenetic variation in metabolic rate-temperature relationships during larval development.

Predictive models of ectotherm responses to environmental change often rely on thermal performance data from the literature. For insects, the majority of these data focus on two traits, development rate and thermal tolerance limits. Data are also often limited to the adult stage. Consequently, predictions based on these data generally ignore other measures of thermal performance and do not account for the role of ontogenetic variation in thermal physiology across the complex insect life cycle. Theoretical syntheses for predicting metabolic rate also make similar assumptions despite the strong influence of body size as well as temperature on metabolic rate. The aim of this study was to understand the influence of ontogenetic variation on ectotherm physiology and its potential impact on predictive modeling. To do this, we examined metabolic rate-temperature (MR-T) relationships across the larval stage in a laboratory strain of the spongy moth (Lymantria dispar dispar). Routine metabolic rates (RMRs) of larvae were assayed at eight temperatures across the first five instars of the larval stage. After accounting for differences in body mass, larval instars showed significant variation in MR-T. Both the temperature sensitivity and allometry of RMR increased and peaked during the third instar, then declined in the fourth and fifth instar. Generally, these results show that insect thermal physiology does not remain static during larval ontogeny and suggest that ontogenetic variation should be an important consideration when modeling thermal performance.