What is the point of cerebral blood flow? DOI Creative Commons
Jay M. J. R. Carr

The Journal of Physiology, Journal Year: 2024, Volume and Issue: 602(4), P. 537 - 538

Published: Feb. 1, 2024

Teleological justification – that is, assigning function to phenomena as opposed describing in purely mechanistic terms is inescapable Physiology, due the explanatory power it brings. Think: heart pumps blood order supply a situation-appropriate cardiac output and properly compensates when called upon. This teleological of serving relatively agreeable, vast body literature both supports takes tacit premise. Nevertheless, number physiologists have presented alternative non-cardiocentric conceptualizations (e.g. Furst & González-Alonso, 2023; Stöhr, 2022). Stöhr (2022) suggested perhaps serves different, yet unknown, purpose. posits: creation specific an example accidental utility rather than González-Alonso (2023) extended this: heart's purpose equilibrate arterial venous forces, but movement 'primed' by metabolic processes. Perhaps neither explanation perfectly correct answer lies dynamically somewhere amongst proposed theories. matter may be discussed heatedly rightly so; challenges convention require testing, can, if found case, generate new directions questions field. In similar vein, regarding cerebral vascular function, current issue The Journal Professor Buxton suggests extension understanding served sensitivity gases (Buxton, 2024). He responses flow (CBF) neural activation, hypoxia hypercapnia occur maintain ratio O2 CO2 brain tissue, which aids preserving appropriate phosphorylation potential, thus protects metabolism. Should tissue O2/CO2 fall below critical threshold, metabolism will also compromised. uses exceptionally comprehensive thermodynamic modelling convective diffusive transport estimate during different physiological states hypercapnia). Then, these estimates are compared calculated from published data CBF gases. Buxton's work provides perspective for how through upkeep (see Fig. 1). Further assessment use outcome measure exposure various environmental would aid deliberation this teleology's power. For instance, recent evidence CM R O 2 ${\mathrm{CM}}{{\mathrm{R}}_{{{\mathrm{O}}_{\mathrm{2}}}}}$ can become reduced iso-oxic (unpublished observations) could interpreted lens prioritization. During hypercapnia, elevated P C ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ cannot 'fixed' increasing CBF; increases and, despite continued washout, continues greater (aside extreme exogenous hypercapnia) production. One interpret findings model indicate increase reduces degree compensated via changes, so oxidative reduction potential. Concerning contracting heart, argues principles mechanics such preload afterload, etc. been well characterized fact should considered modifying explanations illuminate beating '… because they modify contraction themselves do not explain it, since no clear biological has established relation principles…'. change akin Buxton's. They, essence, argue physiology concerning (1) reactivity ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ (2) hypo- pH merely describe activity control, while 'clear purpose' lacking. I believe no-one disagrees metabolism, control delivery regulation/CO2 washout; however, expands suggest protection occurs maintenance ratio. Indeed, explaining sensitivity. Distinguishing authentic challenge embraced. Disputes functions often receive confused objection advocates order. Yet, charge our calling take subject them empirical examination shrewd study design careful measurement tease out truth, exists. consideration here thus: Does truly serve conceptual 'tissue ratio' accident? Or does ratio's direct ties conservation accidently. Disentangling somehow simultaneous (difficult) all factors isolated manipulations each (impossible?). Assuredly, noumenal reality likely combination options more, where combined 'pressures' measurable unmeasurable heat, pH, , perfusion pressure, relevant cations anions, endo-, para- autocrine signals, plus trans-cerebral gradients each), therefore best explained some unifying theory everything. But, explanation, among contemporary options, cuts closest truth greatest us physiologists? To echo Joyner's (2024) conclusion (2023), complex 'brain context proves hold true more situations arguably simpler alternatives, offers power, useful insights applications, then taken up. Either way, there done. Please note: publisher responsible content or functionality any supporting information supplied authors. Any queries (other missing content) directed corresponding author article. No competing interests declared. Sole author. funding was received work.

Language: Английский

Early prediction of sepsis associated encephalopathy in elderly ICU patients using machine learning models: a retrospective study based on the MIMIC-IV database DOI Creative Commons
Yupeng Han,

Xiyuan Xie,

Jiapeng Qiu

et al.

Frontiers in Cellular and Infection Microbiology, Journal Year: 2025, Volume and Issue: 15

Published: April 17, 2025

Sepsis associated encephalopathy (SAE) is prevalent among elderly patients in the ICU and significantly affects patient prognosis. Due to symptom similarity with other neurological disorders absence of specific biomarkers, early clinical diagnosis remains challenging. This study aimed develop a predictive model for SAE patients. The data sepsis were extracted from MIMIC IV database (version 3.1) divided into training test sets 7:3 ratio. Feature variables selected using LASSO-Boruta combined algorithm, five machine learning (ML) models, including Extreme Gradient Boosting (XGBoost), Categorical (CatBoost),Light Machine(LGBM), Multilayer Perceptron (MLP), Support Vector Machines (SVM), subsequently developed these variables. A comprehensive set performance metrics was used assess accuracy, calibration, applicability models. For best performance, we employed SHapley Additive Explanations(SHAP) method visualize model. Based on strict inclusion exclusion criteria, total 3,156 enrolled study, an incidence rate 48.7%. mortality who higher than that non-SAE group (28.78% vs. 12.59%, P < 0.001). 18 feature construction ML algorithm. Compared four models traditional scoring systems, XGBoost demonstrated overall Area Under Curve(AUC)=0.898, accuracy=0.830, recall=0.819, F1-Score=0.820, specificity=0.840, Precision=0.821. Furthermore, results Decision Curve Analysis (DCA) calibration curves has significant value stable performance. ten-fold cross-validation further confirmed robustness generalizability In addition, simplified based SHAP importance ranking, indicated retains excellent ability (AUC=0.858). effectively predicts may serve as reliable tool clinicians identify high-risk

Language: Английский

Citations

0
Chain-mediated effect of physical activity between Chinese language-based L2 motivational self-system and intended effort DOI Creative Commons
Zimei Bu, Yang Liu, Yi Ba

et al.

Scientific Reports, Journal Year: 2025, Volume and Issue: 15(1)

Published: Jan. 26, 2025

The L2 Motivational Self System (L2MSS) determines an individual's motivation in second language learning and influences the experience intended effort. Although physical activity (PA) has been shown to enhance academic efficacy, role of PA whether it promotes efficacy not elucidated. Therefore, present study examined as a mediator explored its ameliorative effects L2MSS. A total 981 international students from different countries were selected 8 universities Beijing research subjects surveyed by International Physical Activity Questionnaire (IPAQ), L2MSS, Learning Experience Scale, Intended Effort Scale. Differences, correlations, mediated model analyzed ANOVA, Pearson, structural equation modeling (SEM). proportions this comparable those observed previous studies, with lowest prevalence individuals exhibiting high levels PA, followed medium levels, highest low levels. With exception ideal self, had significant enhancing effect on experience, effort (F = 2.36, η²=0.05, ; F 3.16, η²=0.04, 2.33, η²=0.05; P < 0.05), was incrementally associated ought-to l2 endeavor degree, time spent 4.23, 7.21, 5.93, η²=0.03; 0.01). In terms there general positive correlations between rest indicators (r > 0.3, except for desire self 0.293). According SEM test, addition direct L2MSS effort, following paths existed: (1) ILS→PA→IE (effect=-0.265, ratio 31.28%, 95%CI=[0.124, 0.527]), (2) OLS→PA→IE (effect 0.179, 17.94%, 95%CI=[0.074, 0.256]), (3) ILS→PA→LE→IE 0.116, 10.69%, 95%CI=[0.042, 0.248]), (4) OLS→PA→LE→IE 0.108, 4.15%, 95%CI=[0.039, 0.126]). indirect effect为0.304 (ratio 59.61%, 95%CI=[0.069, 0.289]). increasing level increased significance effect. positively predicts is important process that so MPA at least 3 days week can increase efficiency learning. This will provide referable predictive richer theoretical foundation Chinese dissemination.

Language: Английский

Citations

0
New Editor‐in‐Chief for Acta Physiologica DOI
Tobias Wang

Acta Physiologica, Journal Year: 2025, Volume and Issue: 241(5)

Published: April 4, 2025

Language: Английский

Citations

0
What is the point of cerebral blood flow? DOI Creative Commons
Jay M. J. R. Carr

The Journal of Physiology, Journal Year: 2024, Volume and Issue: 602(4), P. 537 - 538

Published: Feb. 1, 2024

Teleological justification – that is, assigning function to phenomena as opposed describing in purely mechanistic terms is inescapable Physiology, due the explanatory power it brings. Think: heart pumps blood order supply a situation-appropriate cardiac output and properly compensates when called upon. This teleological of serving relatively agreeable, vast body literature both supports takes tacit premise. Nevertheless, number physiologists have presented alternative non-cardiocentric conceptualizations (e.g. Furst & González-Alonso, 2023; Stöhr, 2022). Stöhr (2022) suggested perhaps serves different, yet unknown, purpose. posits: creation specific an example accidental utility rather than González-Alonso (2023) extended this: heart's purpose equilibrate arterial venous forces, but movement 'primed' by metabolic processes. Perhaps neither explanation perfectly correct answer lies dynamically somewhere amongst proposed theories. matter may be discussed heatedly rightly so; challenges convention require testing, can, if found case, generate new directions questions field. In similar vein, regarding cerebral vascular function, current issue The Journal Professor Buxton suggests extension understanding served sensitivity gases (Buxton, 2024). He responses flow (CBF) neural activation, hypoxia hypercapnia occur maintain ratio O2 CO2 brain tissue, which aids preserving appropriate phosphorylation potential, thus protects metabolism. Should tissue O2/CO2 fall below critical threshold, metabolism will also compromised. uses exceptionally comprehensive thermodynamic modelling convective diffusive transport estimate during different physiological states hypercapnia). Then, these estimates are compared calculated from published data CBF gases. Buxton's work provides perspective for how through upkeep (see Fig. 1). Further assessment use outcome measure exposure various environmental would aid deliberation this teleology's power. For instance, recent evidence CM R O 2 ${\mathrm{CM}}{{\mathrm{R}}_{{{\mathrm{O}}_{\mathrm{2}}}}}$ can become reduced iso-oxic (unpublished observations) could interpreted lens prioritization. During hypercapnia, elevated P C ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ cannot 'fixed' increasing CBF; increases and, despite continued washout, continues greater (aside extreme exogenous hypercapnia) production. One interpret findings model indicate increase reduces degree compensated via changes, so oxidative reduction potential. Concerning contracting heart, argues principles mechanics such preload afterload, etc. been well characterized fact should considered modifying explanations illuminate beating '… because they modify contraction themselves do not explain it, since no clear biological has established relation principles…'. change akin Buxton's. They, essence, argue physiology concerning (1) reactivity ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ (2) hypo- pH merely describe activity control, while 'clear purpose' lacking. I believe no-one disagrees metabolism, control delivery regulation/CO2 washout; however, expands suggest protection occurs maintenance ratio. Indeed, explaining sensitivity. Distinguishing authentic challenge embraced. Disputes functions often receive confused objection advocates order. Yet, charge our calling take subject them empirical examination shrewd study design careful measurement tease out truth, exists. consideration here thus: Does truly serve conceptual 'tissue ratio' accident? Or does ratio's direct ties conservation accidently. Disentangling somehow simultaneous (difficult) all factors isolated manipulations each (impossible?). Assuredly, noumenal reality likely combination options more, where combined 'pressures' measurable unmeasurable heat, pH, , perfusion pressure, relevant cations anions, endo-, para- autocrine signals, plus trans-cerebral gradients each), therefore best explained some unifying theory everything. But, explanation, among contemporary options, cuts closest truth greatest us physiologists? To echo Joyner's (2024) conclusion (2023), complex 'brain context proves hold true more situations arguably simpler alternatives, offers power, useful insights applications, then taken up. Either way, there done. Please note: publisher responsible content or functionality any supporting information supplied authors. Any queries (other missing content) directed corresponding author article. No competing interests declared. Sole author. funding was received work.

Language: Английский

Citations

0