Physiological Mechanisms Research Articles

Comparative Salt-Stress Responses in Salt-Tolerant (Vikinga) and Salt-Sensitive (Regalona) Quinoa Varieties. Physiological, Anatomical and Biochemical Perspectives

Soil salinization is an important stress factor that limits plant growth and yield. Increased salinization is projected to affect more than 50% of all arable land by 2050. In addition, the growing demand for food, together with the increase in the world population, forces the need to seek salt-tolerant crops. Quinoa (Chenopodium quinoa Willd.) is an Andean crop of high importance, due to its nutritional characteristics and high tolerance to different abiotic stresses. The aim of this work is to determine the physiological, anatomical, and biochemical salt-tolerance mechanisms of a salt-tolerant (Vikinga) and a salt-sensitive (Regalona) quinoa variety. Plants were subjected to salinity stress for 15 days, starting at 100 mM NaCl until progressively reaching 400 mM NaCl. Physiological, anatomical, and biochemical parameters including growth, chlorophyll content, quantum yield of PSII (ϕPSII), gas exchange, stomatal density, size, and lipid peroxidation (via malondialdehyde, MDA) were measured. Results show that chlorophyll content, ϕPSII, and MDA were not significantly reduced under saline stress in both varieties. The most stress-affected process was the CO2 net assimilation, with an up to 60% reduction in both varieties, yet Vikinga produced higher dry weight than Regalona due to the number of leaves. The stomatal densities increased under salinity for both varieties, with Regalona the one showing higher values. The averaged stomatal size was also reduced under salinity in both varieties. The capacity of Vikinga to generate higher dry weight is a function of the capacity to generate greater amounts of leaves and roots in any condition. The stomatal control is a key mechanism in quinoa’s salinity tolerance, acquiring higher densities with smaller sizes for efficient management of water loss and carbon assimilation. These findings highlight the potential of Vikinga for cultivation in temperate salinized environments during winter, such as Deltas and lowlands where rice is grown during summer.

Day Late, Dollar Short: Runts of Asynchronously Hatched Songbird Broods Have Reduced Survival, Body Size, and Persistent Energy Deficits.

Many songbirds begin active incubation after laying their penultimate egg, resulting in synchronous hatching of the clutch except for a last-hatched individual ("runt") that hatches with a size deficit and competitive disadvantage to siblings when begging for food. However, climate change may elevate temperatures and cause environmental incubation as eggs are laid, resulting in asynchronous hatching and larger size hierarchies among siblings. Although previous work demonstrated that asynchronous hatching reduces nestling growth and survival relative to synchrony, the physiological mechanisms underlying these effects are unclear. To test the effects of asynchronous hatching on runt growth, survival, physiology, and compensatory growth-related tradeoffs, we manipulated incubation temperature in nest boxes of European starlings (Sturnus vulgaris) to increase asynchronous hatching and collected nestling morphological measurements and blood samples to assess physiology and development. Independent of heating treatment, runts from asynchronously hatched nests had lower survival than runts from more synchronous nests. Surviving runts from asynchronous nests were smaller and had reduced stress-induced corticosterone concentrations and reduced circulating glucose compared with runts from synchronous nests. Despite persistent size and energy deficits, runts from asynchronous nests did not have significant deficits in immunity or telomere length when compared with runts from synchronous nests, suggesting no trade-off between investment in immune development or telomere maintenance with growth. Overall, these results suggest that increased asynchrony due to climate change could reduce clutch survival for altricial songbirds, especially for the smallest chicks in a clutch, and that the negative effects of asynchrony may be driven by persistent energetic deficits.

Balancing Tradition and Science: Acupuncture in Pain Control

Introduction: Pain management is a critical component of healthcare, addressing acute and chronic conditions that significantly impact quality of life. Traditional pharmacological approaches, while effective, often present side effects and dependency risks. Acupuncture, rooted in traditional Chinese medicine, has emerged as a complementary and alternative therapy, leveraging the body’s natural mechanisms to alleviate pain through the strategic insertion of fine needles at acupoints. Purpose of Work: This research investigates the role of acupuncture in pain management, examining its efficacy across various pain conditions, understanding its physiological mechanisms, and evaluating its integration into modern medical practice. It seeks to assess the scientific evidence supporting acupuncture and its potential as a non-pharmacological pain management strategy. State of Knowledge: Studies have demonstrated acupuncture's effectiveness in reducing pain intensity for conditions such as migraines, osteoarthritis, fibromyalgia, and postoperative pain. Mechanistic research highlights its role in modulating neural pathways, enhancing endogenous opioid release, and reducing inflammation. Guidelines from health organizations now recognize acupuncture as a viable option in multidisciplinary pain management. Material and methods: The study methodology entailed defining the objectives, conducting a systematic literature search, and implementing a structured process for screening relevant studies. The research encompassed a comprehensive search across scientific databases, such as PubMed and Google Scholar. Summary: Acupuncture presents a promising, evidence-supported intervention for pain management. By combining traditional techniques with modern scientific insights, acupuncture addresses the growing need for holistic, safe, and effective approaches to alleviating pain and enhancing patient well-being.

Advancements in Mass Spectrometry-Based Targeted Metabolomics and Lipidomics: Implications for Clinical Research.

Targeted metabolomics and lipidomics are increasingly utilized in clinical research, providing quantitative and comprehensive assessments of metabolic profiles that underlie physiological and pathological mechanisms. These approaches enable the identification of critical metabolites and metabolic alterations essential for accurate diagnosis and precision treatment. Mass spectrometry, in combination with various separation techniques, offers a highly sensitive and specific platform for implementing targeted metabolomics and lipidomics in clinical settings. Nevertheless, challenges persist in areas such as sample collection, quantification, quality control, and data interpretation. This review summarizes recent advances in targeted metabolomics and lipidomics, emphasizing their applications in clinical research. Advancements, including microsampling, dynamic multiple reaction monitoring, and integration of ion mobility mass spectrometry, are highlighted. Additionally, the review discusses the critical importance of data standardization and harmonization for successful clinical implementation.

The kidney under heat stress: a vulnerable state.

This review examines the effects of occupational heat stress on kidney health. It focuses on the role of hyperthermia in the development of acute kidney injury (AKI) and its potential progression to chronic kidney disease of nontraditional etiology (CKDnt). We highlight the physiological mechanisms by which hyperthermia affects kidney function and discuss emerging preventive strategies. Hyperthermia places the kidneys in a vulnerable state. As body temperature increases, blood flow is directed toward the skin to aid in cooling, diverting it away from internal organs like the kidneys to support blood pressure regulation. At the same time, hyperthermia and dehydration increases energetic demand to promote fluid and electrolyte conservation. Collectively, this can create a localized supply-demand mismatch, resulting in tissue hypoxia that can damage kidney tissues. These findings highlight that heat hyperthermia can lead to subclinical kidney damage, with potential long-term implications for kidney health. Heat-induced AKI is a growing public health concern. Individuals engaged in manual labor with prolonged exposure are at risk of CKDnt. Interventions aimed to prevent hyperthermia show promise in mitigating the risk of AKI. Further research is necessary to refine these strategies and establish evidence-based guidelines for reducing heat-related kidney injuries.

PLASMA TRACE ELEMENTS IN MANAGED HUMBOLDT PENGUINS (SPHENISCUS HUMBOLDTI) FROM A SINGLE ZOOLOGICAL COLLECTION IN GERMANY.

Only limited data on concentrations of trace elements in the blood of avian species have been published. This information can play an important role in the conservation of endangered species and their protection from environmental pollutants and can also be clinically relevant in managed individuals. Some elements are essential for the health of the animals in human care, but little is known about expected concentrations for some of these elements. Therefore, 21 elements (silver, arsenic, gold, barium, cadmium, cobalt, chromium, copper, iron, iodine, mercury, magnesium, manganese, molybdenum, nickel, platinum, antimony, selenium, thallium, vanadium, and zinc) were measured by inductively coupled plasma mass spectrometry in lithium-heparinized plasma samples from Humboldt penguins (Spheniscus humboldti) from a single zoological collection in Germany (n = 39). The plasma concentrations of cadmium, nickel, platinum, antimony, and thallium were under the limit of detection in most of the analyzed samples. The results also showed that the females had significantly (P ≤ 0.05) higher concentrations of silver, barium, cobalt, chromium, iron, mercury, magnesium, vanadium, and zinc in their plasma in comparison with males. A correlation between the element plasma concentration and the age of the individuals could not be found. The differences in plasma concentrations of individual element between males and females could be due to hormonal influences on the metabolism. Further studies in different seasons and other age groups are needed in the future to investigate environmental and host effects in more detail and to understand physiological mechanisms responsible for observed differences.

Effects of foot reflexology on disease.

In this article, we review a recently published article to explore the significance of foot reflexology in modern medical practice. With the advancement of modern medicine, we are increasingly committed to finding the specific physiological mechanisms of foot reflexes to treat diseases, thereby better proving the therapy's effectiveness. It has been reported that foot reflexes can activate the cerebral cortex and organs corresponding to the feet, stimulating blood flow, nutrition and nerves through neural and endocrine regulation to achieve the purpose of treating and preventing diseases and promoting health. The therapy shows unique potential and value, and provides a new perspective on integrating traditional medicine and modern medicine.

Isometric Exercise for Blood Pressure and Endothelial Function in Metabolic Syndrome: A Review

Context: Metabolic syndrome (MetS) is characterized by a cluster of metabolic disorders, including hypertension, insulin resistance, and dyslipidemia, which collectively heighten the risk of cardiovascular diseases (CVDs). The global prevalence of MetS is steadily increasing, paralleling the rise in obesity and sedentary lifestyles. Pharmacological treatments for MetS often face challenges such as inadequate blood pressure (BP) control and limited improvements in cardiovascular outcomes. Consequently, there is a growing emphasis on non-pharmacological interventions, particularly exercise. Among various exercise modalities, isometric resistance training (IRT), which involves static muscle contractions without joint movement, has emerged as a promising strategy for effectively lowering BP and enhancing endothelial function, both of which are critical for cardiovascular health. Evidence Acquisition: This comprehensive literature review synthesizes existing research on the effects of isometric exercise on BP regulation and endothelial function in individuals diagnosed with MetS. The review examines studies sourced from databases such as PubMed, Scopus, and Web of Science, focusing on randomized controlled trials, meta-analyses, and observational studies published in peer-reviewed journals. Key discussion areas include the underlying physiological mechanisms of IRT, comparisons with other exercise modalities, clinical implications, and recommendations for future research. Articles were selected based on qualitative and descriptive reviews. Results: Evidence indicates that isometric resistance training effectively reduces both systolic and diastolic BP, achieving results comparable to other exercise forms like aerobic and dynamic resistance training. Furthermore, IRT has significantly improved endothelial function, particularly among populations with MetS. These physiological benefits are attributed to mechanisms such as enhanced nitric oxide bioavailability, reduced oxidative stress, and improved autonomic regulation. Conclusions: The review supports the integration of isometric exercise into hypertension management protocols, especially for individuals with MetS. Isometric resistance training offers a viable non-pharmacological alternative or adjunct to traditional treatments, with the added advantages of accessibility and adaptability for diverse populations. However, further research is necessary to optimize exercise protocols, determine long-term outcomes, and fully elucidate the molecular mechanisms underlying the cardiovascular benefits of IRT.

Unveiling the Virulence Mechanism of Leptosphaeria maculans in the Brassica napus Interaction: The Key Role of Sirodesmin PL in Cell Death Induction.

Leptosphaeria maculans is the causal agent of blackleg disease in Brassica napus, leading to substantial yield losses. Sirodesmin PL, the principal toxin produced by L. maculans, has been implicated in the infective process in plants. However, the precise molecular and physiological mechanisms governing its effects remain elusive. This study investigates the changes induced by Sirodesmin PL at the transcriptomic, physiological, and morphological levels in B. napus cotyledons. Sirodesmin PL treatment upregulates genes associated with plant defense processes, including response to chitin, sulfur compound biosynthesis, toxin metabolism, oxidative stress response, and jasmonic acid/ethylene synthesis and signaling. Validation of these transcriptomic changes is evidenced by several typical defense response processes, such as the accumulation of reactive oxygen species (ROS) and callose deposition. Concomitantly, oxidized Sirodesmin PL induces concentration- and exposure duration-dependent cell death. This cellular death is likely attributed to diminished activity of photosystem II and a reduction in the number of chloroplasts per cell. In agreement, a down-regulation of genes associated with the photosynthesis process is observed following Sirodesmin PL treatment. Thus, it is plausible that L. maculans exploits Sirodesmin PL as a virulence factor to instigate cell death in B. napus during its necrotrophic stage, favoring the infective process.

Physiological Evaluation of Salt Tolerance in Sunflower Seedlings Across Different Genotypes

Sunflower (Helianthus annuus L.) is an important oilseed crop cultivated extensively across the globe. High salinity adversely impacts plant growth and physiological processes. In this study, the data on the phenotypes, physiological indices, and expression of relevant genes from different pathways responding to the stress were collected to clarify the physiological mechanisms underlying sunflower’s salt tolerance with the seedlings of two salt-tolerant (182265 and 182283) and two salt-sensitive (182093 and 186096) genotypes, which were exposed to 350 mM NaCl for 5 days. The findings revealed that, during the seedling stage, salt-tolerant sunflowers accumulated less Na+ and more K+, resulting in a higher K+/Na+ ratio that mitigated ionic toxicity throughout the plants, compared to the salt-sensitive resources. Furthermore, the salt-tolerant germplasms also exerted salt tolerance through the following several pathways: they maintained robust osmotic regulation by accumulating higher levels of proline, soluble sugars, and other osmolytes; they neutralized reactive oxygen species (ROS) by elevating the activity of antioxidant enzymes such as POD, SOD, CAT, APX, and GR; and they sustained optimal growth by boosting photosynthesis. Taken together, this study provided a more comprehensive assessment of the sunflower’s physiological salt tolerance, providing insights that will inform further molecular studies on salt tolerance and accelerating the breeding process for sunflower varieties with improved salt resilience.

The impact of vitamin d on psychiatric and physiological mechanisms in the context of epilepsy

The impact of vitamin d on psychiatric and physiological mechanisms in the context of epilepsy

Physiological changes and molecular regulation in sweetpotato responses to low‐temperature stress

AbstractSweetpotato (Ipomoea batatas [L.] Lam) is highly adaptable to different soils and climates, but it is more sensitive to cold due to its tropical origin. Low‐temperature stress is a key factor affecting storage and has a significant impact on sweetpotato quality. During sweetpotato storage, prolonged exposure to low temperatures causes chilling damage to the root system, altering its physiological functions. This is manifested by wilting of the tuberous roots, nutrient loss, and reduced antioxidant enzyme activity. At the same time, it leads to a significant downregulation of genes associated with cold signaling pathways. Understanding the physiological and molecular mechanisms of sweetpotato's response to low‐temperature stress, which is crucial for improving its quality during storage. In addition, methods such as high‐voltage alternating electric field, controlled atmosphere, hot water treatment, and hot air treatment can better preserve the nutrients of sweetpotato and maintain their high commercial quality during low‐temperature storage. This article reviews and summarizes key studies on the nutrient and physiological changes, as well as the molecular regulatory mechanisms of sweetpotato during low‐temperature storage, and identifies unresolved questions in this field. It provides insights for further research on low‐temperature stress in sweetpotato.

Exploring the Physiological and Molecular Mechanisms by Which Potassium Regulates Low-Temperature Tolerance of Coconut (Cocos nucifera L.) Seedlings

Coconut holds significant importance as a fruit and oilseed crop in tropical and subtropical regions. However, low-temperature (LT) stress has caused substantial reductions in yield and economics and impedes coconut production, therefore constraining its widespread cultivation and utilization. The appropriate application of potassium (K) has the potential to enhance the cold tolerance of crops and mitigate cold damage, but the regulatory mechanisms by which K improves coconut adaptability to cold stress remain poorly understood. Transcriptome and metabolomic analyses were performed on coconut seedlings treated with LT (5 °C) and room temperature (25 °C) under various K conditions: K0 (0.1 mM KCL), KL (2 mM KCL), KM (4 mM KCL), and KH (8 mM KCL). Correlation analysis with physiological indicators was also conducted. The findings indicated that K absorption, nutrient or osmotic regulation, accumulation of substances, photosynthesis, hormone metabolism, and reactive oxygen species (ROS) clearance pathways played crucial roles in the adaptation of coconut seedlings to LT stress. LT stress disrupted the homeostasis of hormones, antioxidant enzyme activity, chlorophyll, K, and the regulation of nutrients and osmolytes. This stress also leads to the downregulation of genes and metabolites related to K transporters, hormone metabolism, transcription factors, and the metabolism of nutrients and osmolytes. Applying K helped maintain the homeostasis of hormones, antioxidant enzyme activity, chlorophyll, K, and the regulation of nutrients and osmolytes, promoted the removal of ROS, and reduced malondialdehyde, consequently diminishing the damage caused by LT stress to coconut seedlings. Furthermore, the comprehensive analysis of metabolomics and transcriptomics highlighted the importance of carbohydrate metabolism, biosynthesis of other secondary metabolites, amino acid metabolism, lipid metabolism, and ABC transporters in K’s role in improving coconut seedlings’ tolerance to LT stress. This study identified the pivotal biological pathways, regulatory genes, and metabolites implicated in K regulation of coconut seedlings to acclimate to LT stress.

The thermal optimum of photosynthetic parameters is regulated by leaf nutrients in neotropical savannas.

Global warming significantly threatens species in the Cerrado, the world's largest savannah. Therefore, understanding how plants respond to temperature change, particularly in relation to leaf-level photosynthetic capacity, is crucial to understanding the future of Cerrado vegetation. Here, we determined the optimum temperature of the maximum rate of RuBP-carboxylation and maximum electron transport rate (TOptV and TOptJ, respectively) of 12 tree species in two opposite borders (northeastern and southeastern) of the Cerrado with distinct temperature regimes. We focused on four widespread species found in both sites, four restricted to the northeast, and four to the southeast. We compared TOptV and TOptJ between regions and between widespread species (co-occurring in both sites) and species restricted to each ecoregion. Additionally, we also explored the relationship between TOptV and TOptJ with leaf nitrogen (N), phosphorus (P), and potassium (K). As a result, we found that TOptV and TOptJ values were similar across species, regardless of the study region or species distribution range. The similarity of TOpt values among species suggests that photosynthetic performance is optimized to current temperatures. Additionally, we also observed that the TOptV and TOptJ were similar to the local maximum ambient temperatures. Therefore, if these species do not have enough plasticity, the increasing temperature predicted for this region may reduce their photosynthetic performance. Finally, the studied species exhibited general relationships between the TOptV and TOptJ and foliar key nutrients, particularly with P, suggesting the nutrient availability has an important role on thermal acclimation of leaves. These findings offer valuable insights into physiological and ecological mechanisms in photosynthesis performance present at the Cerrado species.

Nanotechnological approaches to improve corticosteroids ocular therapy.

The administration of corticosteroids is the first-line treatment of the clinical conditions with ocular inflammation. Nonetheless, ocular physiological mechanisms, anatomical barriers and corticosteroid properties prevent it from reaching the target site. Thus, frequent topical administered doses or ocular injections are required, leading to a higher risk of adverse events and poor patient compliance. Designing novel drug delivery systems based on nanotechnological tools is a useful approach to overcome disadvantages associated with the ocular delivery of corticosteroids. Nanoparticle-based drug delivery systems represent an alternative to the current dosage forms for the ocular administration of corticosteroids, since due to their particle size and the properties of their materials, they can increase their solubility, improve ocular permeability, control their release and increase bioavailability after their ocular administration. In this way, lipid and polymer-based nanoparticles have been the main strategies developed, giving rise to novel patent applications to protect these innovative drug delivery systems as a product, its preparation or administration method. Additionally, it should be noted that at least 10 clinical trials are being carried out to evaluate the ocular application of different pharmaceutical formulations based on corticosteroid-loaded nanoparticles. Through a comprehensive and extensive analysis, this review highlights the impact of nanotechnology applications in ocular inflammation therapy with corticosteroids.

Various Hydrogel Types as a Potential In Vitro Angiogenesis Model.

Angiogenesis, the formation of new blood vessels, is a fundamental process in both physiological repair mechanisms and pathological conditions, including cancer and chronic inflammation. Hydrogels are commonly used as in vitro models to mimic the extracellular matrix (ECM) and support endothelial cell behavior during angiogenesis. Mesenchymal stem cells further augment cell and tissue growth and are therefore widely used in regenerative medicine. Here we examined the combination of distinct hydrogel types-fibrin, collagen, and human platelet lysate (HPL)-on the formation of capillaries in a co-culture system containing human umbilical vein endothelial cells (HUVECs) and bone marrow-derived mesenchymal stem cells (BM-MSCs). The mechanical properties and structural changes of the hydrogels were characterized through scanning electron microscopy (SEM) and nanoindentation over 10 days. Fibrin and HPL gels sustained complex network formations, with HPL gels promoting even vascular tube formation of up to 10-fold capillary caliber. Collagen gels supported negligible angiogenesis. Our results suggest that HPL gels in combination with MSC-EC co-culture may be employed to obtain robust vascularization in tissue engineering. This study provides a comparative analysis of fibrin, collagen, and HPL hydrogels, focusing on their ability to support angiogenesis under identical conditions. Our findings demonstrate the superior performance of HPL gels in promoting robust vascular structures, highlighting their potential as a versatile tool for in vitro angiogenesis modeling.

Blood Biomarker Signatures for Slow Gait Speed in Older Adults: An Explainable Machine Learning Approach.

Maintaining physical function is crucial for independent living in older adults, with gait speed being a key predictor of health outcomes. Blood biomarkers may potentially monitor older adults' mobility, yet their association with slow gait speed still needs to be explored. This study aimed to investigate the relationship between blood biomarkers and gait speed using the Midlife in the United States (MIDUS) study biomarker dataset. A cross-sectional design was employed for analysis, involving 405 individuals aged 60years and over. We used a machine learning framework, specifically the XGBoost algorithm, feature selection methods, and the Shapley Additive Explanations, to develop an explainable prediction model for slow gait speed. Our model demonstrated the highest cross-validation score with the six most important features among 35 variables, as elevated interleukin-6, C-reactive protein, glycosylated hemoglobin, interleukin-8, older age, and female sex were significantly associated with reduced gait speed (area under the curve=0.75). Our findings suggest that blood biomarkers can play a critical role in integrated models to assess and monitor slow gait speed in older adults. Identifying key blood biomarkers provides valuable insights into the underlying physiological mechanisms of mobility decline and offers promising avenues for early intervention to preserve mobility in the aging population.

Water content, fractional composition of water, carbohydrate and fatty acid composition of lipids in renewal buds of <I>Hylotelephium triphyllum</I> (Crassulaceae) during overwintering

Renewal buds are a good model for studying growth, metabolism and bioenergetics under the influence of environmental factors (light, temperature). Such studies can provide new information about physiological, biochemical and molecular mechanisms of shoot growth at the stage of growth inside the bud under the influence of exogenous and endogenous factors. The paper contains the data on seasonal changes in energy metabolism, fractional composition of water, content of photosynthetic pigments, soluble carbohydrates, protein, and fatty acids in renewal buds of Hylotelephium triphyllum (Haw.) Holub. In the renewal buds formed in August, the total water content is about 85%, the share of water passing into the crystalline state – more than 90%, the temperature of the water-to-ice phase transition – −6°C. The intensity of respiration decreases, and the rate of energy storage, accumulation of soluble carbohydrates and unsaturated fatty acids increases gradually against the high water content and high proportion of unbounded water in plant tissues as long as the average daily temperatures decrease. There is a direct relationship between the respiration intensity, heat release, and energy storage. During the autumn-winter-spring period, the proportion of stored energy from the energy produced by respiration is about 40%. The formation of the photosynthetic apparatus of renewal buds is accompanied by a decrease in the rate of heat release and in the amount of stored energy. The swelling of buds proceeds simultaneously with an increase in the content of fatty acids, which indicates the activation their synthesis and coincides with the spring maximum content of chlorophylls and carotenoids. At this period, the total water content is about 75%, the proportion of water passing into the crystalline state – about 99%. The temperature of the water-to-ice phase transition is −4.7°C. This temperature value of ice formation is probably the minimum possible temperature at which irreversible damages to cellular structures occur in renewal buds. Consequently, the high water saturation in renewal buds of Hylotelephium triphyllum maintains metabolic processes and, as a result, favors the implementation of morphophysiological and structural rearrangements in them but also significantly increases the risk of damage by negative temperatures in low-snow winters.

Physiological Mechanisms Underlying the Primary Respiratory Mechanism (PRM) and Cranial Rhythmic Impulse (CRI) in Osteopathy: A Systematic Review

Background: Cranial Rhythmic Impulse (CRI) or Primary Respiratory Mechanism (PRM), movement felt on the scalp or the rest of the body, respectively, is a fundamental concept used by osteopaths in their practice for their diagnosis and treatment. However, the physiological basis of this phenomenon remains unclear. Sutherland, the founder of cranial osteopathy, proposed in 1939 that PRM was due to the movement of the cranial bones pulled by the meninges, themselves pushed by the fluctuation of cerebrospinal fluid and the motility of the central nervous system. Since then, Sutherland’s theory has become dogma, despite scientific progress refuting it, and few osteopaths have attempted to find better explanations. Objective: This systematic review of Medline, Science Direct and the Cochrane Library indexed electronic databases explores current knowledge of the physiological mechanisms underlying the Primary Respiratory Movement (PRM) or Cranial Rhythmic Impulse (CRI). Methods: We entered the following identified keywords: “osteopathy in the cranial field”; “cranial rhythmic impulse”; and “primary respiratory mechanism”. We identified 193 studies, evaluated 115, and identified 28 articles that fulfilled our criteria. We classified the studies in terms of methodological rigor, types of studies and tools used. No study had three good-level items, and only five studies had two good-level items corresponding to the type of study and tools used. The protocol of the review has been registered on PROSPERO-CRD42023488497. Results: Out of the 28 articles, 20 referenced at least one of Sutherland’s hypotheses, often quoting the model to critique or challenge it, while 25 of them refer to other hypotheses and/or mechanisms underlying PRM/CRI: 11 concern vasomotion in blood vessels (7) and lymphatic vessels (6), 20 THM waves, 14 heart rate variability, 9 ventilation rate, 2 the extra-cellular matrix and 1 oxidative metabolism. Conclusions: Although Sutherland’s theory remains prevalent in general beliefs, in scientific literature, THM waves driven by autonomous system activity have gained prominence, emerging as the leading hypothesis. The results from this systematic review confirm the need for a paradigm shift for the CRI/PRM in osteopathy, and for more rigorous evaluation and communication on a model in step with evolving scientific data.

Effects of Acute Stress on Metabolic Interactions Related to the Tricarboxylic Acid (TCA) Cycle in the Left Hippocampus of Mice.

The acute stress response affects brain metabolites closely linked to the tricarboxylic acid (TCA) cycle. This response involves time-dependent changes in hormones and neurotransmitters, which contribute to resilience and the ability to adapt to acute stress while maintaining homeostasis. This physiological mechanism of metabolic dynamics, combined with time-series analysis, has prompted the development of new methods to observe the relationship between TCA cycle-related brain metabolites. This study aimed to observe the acute stress response through metabolic interactions using time-series proton magnetic resonance spectroscopy (1H-MRS) in the left hippocampus of mice. In this study, 4-week-old male C57BL/6N mice (n = 24) were divided into control (n = 12) and acute stress groups (n = 12). Acute stress was induced through a 2 h restraint protocol. Time-series 1H-MRS data were obtained on the left hippocampus of both groups using a 9.4 T 1H-MRS scanner. Time-series MRS data were quantified using LCModel, and significant metabolic interactions were identified through Spearman correlation analysis, a one-tailed sign test, and false discovery rate correction. No significant metabolic correlation coefficient was observed in the control group. However, in the acute stress group, glutathione (GSH) and N-acetyl aspartate (NAA) showed a significant positive correlation over time, with a high correlation coefficient exceeding 0.5. Temporal measurement of GSH and NAA, combined with correlation analysis, offers a comprehensive understanding for the metabolic dynamics during acute stress. This approach emphasizes their distinct roles and interdependence in the progression of oxidative stress, mitochondrial function, and the maintenance of physiological homeostasis.