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PubMed2026

Spermidine and melatonin ameliorate heat stress-induced decline in sheep semen quality.

Heat stress impairs reproductive performance in sheep through endocrine disruption and oxidative stress. This study evaluated the protective effects of spermidine (SPD) and melatonin (MT) supplementation on semen quality in Dorper rams during summer. Twenty-four rams were randomly assigned to a control group, an SPD group (5 mg/kg, dietary supplementation), or an MT group (60 mg, subcutaneous implantation) and treated for 60 days. The temperature-humidity index (THI) was monitored throughout the experimental period. Compared with the control group, MT significantly reduced serum cortisol concentration on day 30 (P < 0.05), whereas no significant differences were observed at the other sampling time points. Serum testosterone, spermidine, and melatonin concentrations remained unchanged throughout the study (P > 0.05). SPD supplementation significantly increased ejaculate volume on day 35 and sperm motility on day 42 (P < 0.05), whereas MT did not significantly affect these parameters. Neither treatment reduced the overall sperm abnormality rate. However, both SPD and MT significantly decreased the proportion of acephalic and decaudated sperm on day 56 (P < 0.05). Neither treatment significantly affected pregnancy rate, delivery rate, or the expression of PMFBP1 and SUN5 proteins in semen (P > 0.05). Regarding oxidative stress, MT significantly downregulated CAT protein expression (P < 0.05), whereas SPD significantly reduced MDA content and SOD1 protein expression (P < 0.05); MT showed similar but non-significant trends for these two markers (P > 0.05). Collectively, these findings demonstrate that SPD and MT exert distinct protective effects against heat stress, with SPD improving selected semen quality traits and both treatments reducing sperm head-tail separation, although these benefits did not translate into improved reproductive performance.

Animals↗

PubMed2026

A Review on Heat Stress in Broiler Chickens: Mechanisms, Effects and Mitigation Strategies.

BACKGROUND: Heat stress (HS) is a major environmental challenge for broilers, particularly under rising global temperatures and high humidity. Broiler chickens are highly susceptible because of their rapid growth rate, high metabolic heat production, limited thermoregulatory capacity and genetic selection for fast growth. OBJECTIVE: This review aims to synthesise current evidence, evaluate the effectiveness of existing mitigation strategies, identify key knowledge gaps and provide future research directions to improve broiler resilience, welfare and productivity under increasingly HS conditions. METHODS: This review synthesised evidence published between 2010 and 2025 on the physiological, metabolic, intestinal, immunological and productive consequences of HS and evaluated mitigation strategies. RESULTS: The reviewed studies demonstrate that HS reduces feed intake by approximately 10%-30%, suppresses body weight gain and feed efficiency and increases mortality, with severity depending on temperature, humidity and broiler genotype. HS disrupts carbohydrate, protein and lipid metabolism; induces acid-base imbalance and oxidative stress; compromises intestinal barrier integrity; alters gut microbiota; suppresses immune function; and reduces meat quality. Nutritional interventions, including dietary electrolyte balance, antioxidants, vitamins, selenium, zinc, phytogenic compounds, probiotics, betaine and optimised feeding strategies, environmental management and genetic approaches, including naked-neck and frizzle genes, can partially alleviate these adverse effects. However, inconsistencies among studies persist because of differences in broiler strains, environmental conditions, dietary formulations and experimental protocols. CONCLUSION: HS substantially compromises broiler health, welfare, productivity and meat quality. Nutritional, environmental and genetic approaches can partially mitigate its adverse effects; however, further research is needed to improve broiler resilience under increasingly HS conditions.

Animals↗

PubMed2026

Potential Links Between Physiological and Perceptual Strain in High Heat Stress.

The physiological strain index (PhSI) is widely used to quantify thermoregulatory and cardiovascular strain during heat stress. However, direct physiological measurements may not always be feasible in occupational or athletic settings. Therefore, this study aimed to examine the relationship and agreement between perceptual strain and integrated physiological strain indices during high heat stress. Ten healthy, physically active, non-heat-acclimated males (29 (7) yr; 1.79 (0.11) m; 77.4 (9.3) kg) completed two randomized crossover exercise trials in hot-dry (HD) and warm-humid (WH) environments with equivalent wet-bulb globe temperatures. Heart rate, rectal temperature, skin temperature, rating of perceived exertion, and thermal sensation were measured at baseline and every 15 minutes during 60 minutes of cycling. Physiological strain index (PhSI), adaptive physiological strain index (aPhSI), and perceptual strain index (PeSI) were calculated using validated equations. Repeated-measures correlation analyses demonstrated very strong associations between PeSI and both PhSI and aPhSI under HD (Rrm = 0.940-0.943) and WH (Rrm = 0.980-0.982; all p < 0.001). Receiver operating characteristic analyses demonstrated good-to-excellent discrimination of physiological strain by PeSI (AUC = 0.895-0.969). Mixed-effects analyses showed that higher PeSI values were associated with increased PhSI (β = 1.325, p < 0.001) and aPhSI (β = 1.459, p < 0.001). However, Bland-Altman analyses demonstrated relatively small mean biases (0.4-0.9 AU) but wide limits of agreement (-2.8 to 4.2 AU), indicating that PeSI and physiological strain indices are not interchangeable. These findings suggest that PeSI may serve as a practical adjunctive or screening indicator of physiological strain when direct physiological measurements are unavailable.

Humans↗

PubMed2025

Protective effects of liver-derived apolipoprotein A1 against heat stress-induced hypothalamic lipid metabolism and blood-brain barrier integrity.

Heat stress (HS), a prevalent occupational and environmental hazard, has increasingly been recognized as a major contributor to multiple physiological disorders. The hypothalamus, a key regulator of thermoregulation and endocrine signaling, is especially susceptible to metabolic and inflammatory disturbances induced by HS. This study investigates the interplay among lipid metabolism, blood-brain barrier (BBB) integrity, and neuroinflammation in the hypothalamus under HS conditions, with a specific focus on apolipoprotein A1 (APOA1) as a potential protective factor. To achieve this, we integrated proteomic and lipidomic analyses with experimental validation in porcine and murine models. Proteomic analysis identified 266 differentially expressed proteins (DEPs) in the hypothalamus following HS, with significant enrichment in lipid metabolism pathways-especially glycerophospholipid (GP) metabolism-in which APOA1 displayed a marked increase. Lipidomic profiling further revealed HS-induced disruptions in phosphatidylcholine (PC), phosphatidylethanolamine (PE), and cardiolipin (CL) metabolism. Additionally, blood-brain barrier integrity was compromised, as evidenced by increased perivascular IgG extravasation, reduced pericyte coverage, and decreased expression of tight junction proteins ZO-1 and Occludin. HS also triggered pronounced neuroinflammation, characterized by elevated levels of iNOS, GFAP, and pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). Notably, administration of D-4F, an APOA1 mimetic peptide, alleviated blood-brain barrier damage, reduced neuroinflammation, and preserved synaptic integrity, thereby suggesting a neuroprotective role for APOA1 in HS-induced hypothalamic dysfunction. These findings underscore the critical role of lipid metabolism in maintaining hypothalamic homeostasis under HS conditions and position APOA1 as a key regulator with potential therapeutic implications for mitigating HS-related neuroinflammatory and metabolic disturbances.

Blood-Brain Barrier↗

PubMed1979

Adult hypophosphatasia. Clinical, laboratory, and genetic investigation of a large kindred with review of the literature.

Investigation of the kindred of a 58-year-old woman with all of the features of "adult" hypophosphatasia revealed 12 individuals in 3 generations with subnormal circulating total alkaline phosphatase (AP) activity. The pattern of inheritance suggested autosomal dominant transmission, with incomplete penetrance of the trait particularly in the young males. Hypophosphatasic individuals other than the proposita were clinically well but had loss of permanent teeth, showing that dental abnormalities could be the only clinical manifestation of the disorder. Radiographic investigation of the proposita revealed that completion of stress fractures was necessary for healing; maturation of incomplete fractures resulted in stable Looser zones. Skeletal survey and radionuclide bone imaging were unremarkable in hypophosphatasic individuals without fracture. Subclinical osteopenia was found in several affected women by metacarpal cortical width and bone densitometric measurements. Laboratory studies showed increased plasma and urinary phosphoethanolamine levels in affected individuals. Phosphoethanolamine and phosphoserine appeared to be natural subtrates for AP since a negative correlation existed between each substrate and circulating total AP activity. Phosphoethanolamine and phosphoserine levels were greatest in the clinically affected proposita; furthermore, only she showed absence of leukocyte AP activity. Heat fractionation of her total circulating AP activity suggested severe reduction in the bone isoenzyme. Hypophosphatasic children had higher levels of total circulating AP than affected adults; the increase was apparently secondary to increased bone isoenzyme. Iliac crest bone biopsies showed greater abnormality in affected women. Osteoidosis was particularly pronounced in the proposita's younger affected sister and hypophosphatasic daughter. Histomorphometric analyses of the biopsies revealed a paucity of osteoblasts despite increased quantities of unmineralized matrix. The finding that hypophosphatasic children in this kindred had higher circulating total AP activity than adults and were able to model their skeleton normally, together with observations that the bone biopsy in adults had a paucity of osteoblasts, suggests that some factor(s) during growth is able to induce both AP activity and osteoblast function, or, that this disorder is an "abiotrophy" with deficient osteoblastic formation and/or accelerated destruction in adult life.

Adolescent↗

PubMed1977

Oedema and heart-failure in the tropics.

A mechanism is outlined to explain why oedema forms so readily in hot climates. A continual cutaneous vasodilation produces a low total peripheral resistance so that the mean arterial pressure cannot be raised except by increasing cardiac output. This inability to raise the arterial pressure as efficiently as usual will lead to difficulties in dealing with excess sodium and water loads, because the mean arterial pressure is the major determinant of urinary output. Anything which favours the retention of sodium and water in hot climates must therefore make things worse. This mechanism will also explain the post-partum cardiac failure syndrome which occurs in Northern Nigeria, since Hausa women take high-sodium diets and lie on heated beds during the post-partum period. The necessity for a further increase of cardiac output to excrete excess sodium and water in hot climates causes stress in persons with vulnerable myocardia and produces the symptoms and signs of cardiac failure more rapidly.

Body Temperature↗

PubMedDate not supplied

The seial thrombin time in the diagnosis of consumptive coagulopathy.

Acute consumptive coagulopathy may be initiated by diverse events. It is frequently necessary to establish the diagnosis with urgency. Rational therapy can only be approached with knowledge of the relative impact the primary consumption exerts upon hemostasis as well as the effects of secondary fibrinolysis. A constellation of interlocking tests within the capability of the small laboratory is presented. This includes the prothrombin time, the activated partial thromboplastin time, the serial thrombin time, the heat precipitation fibrinogen level, the platelet count, red cell morphology, the levels of fibrin (fibrinogen) degradation products and selected factor assays. This series can be completed within 45 minutes. Interpretation, with particular emphasis upon the stage in the natural history of the process when evaluation is instituted, and underlying diseases which modify typical patterns are discussed. The discriminant function of the serial thrombin time is stressed.

Adult↗

PubMed2025

Differential Expression of Erythrocyte Proteins in Patients with Alcohol Use Disorder.

Alcohol Use Disorder (AUD) poses global health challenges, and causes hematological alterations such as macrocytosis and oxidative stress. Disruption of protein structures by alcohol and/or its metabolites may exacerbate AUDs; proteomics can elucidate the underlying biological mechanisms. This study examined the proteins differentially expressed in the cytosol and membrane fractions of erythrocytes obtained from 30 male patients with AUD, comparing them to samples from 15 age- and BMI-matched social drinkers (SDs) and 15 non-drinkers (control). The analysis aimed to identify the molecular differences related to alcohol consumption. The AUD patient subgrouping was based on mean corpuscular volume (MCV), with 16 individuals classified as having a normal MCV and 14 having a high MCV. Proteins were separated via two-dimensional(2D)-gel electrophoresis, digested with trypsin, and identified via Matrix-Assisted Laser Desorption/Ionization Time-of-Flight (TOF) mass spectrometry (MALDI-TOF/TOF). Additionally, levels of malondialdehyde and 4-hydroxyalkenals (MDA + HAE), reduced glutathione (GSH), oxidized glutathione (GSSG), serum carbohydrate-deficient transferrin (%CDT), disialotransferrin (%DST), and sialic acid (SA) were analyzed. The results showed increased MDA + HAE and decreased total thiols in AUD patients, with GSSG elevated and the GSH/GSSG ratio reduced in the AUD MCV-high subgroup. Serum %CDT, %DST, and SA were significantly higher in AUD. Compared to the control profiles, the AUD group exhibited differential protein expression. Few proteins, such as bisphosphoglycerate mutase, were downregulated in AUD versus control and SD, as well as in the MCV-high AUD subgroup. Conversely, endoplasmin and gelsolin were upregulated in AUD relative to control. Cytoskeletal proteins, including spectrin-alpha chain, actin cytoplasmic 2, were overexpressed in the AUD group and MCV-high AUD subgroup. Several proteins, such as 14-3-3 isoforms, alpha-synuclein, translation initiation factors, heat shock proteins, and others, were upregulated in the MCV-high AUD subgroup. Under-expressed proteins in this subgroup include band 3 anion transport protein, bisphosphoglycerate mutase, tropomyosin alpha-3 chain, uroporphyrinogen decarboxylase, and WD repeat-containing protein 1. Our findings highlight the specific changes in protein expression associated with oxidative stress, cytoskeletal alterations, and metabolic dysregulation, specifically in AUD patients with an elevated MCV. Understanding these mechanisms is crucial for developing targeted interventions and identifying biomarkers of alcohol-induced cellular damage. The complex interplay between oxidative stress, membrane composition, and cellular function illustrates how chronic alcohol exposure affects cellular physiology.

Humans↗

PubMed1976

The visual stresses of the aerospace environment.

The aviator or astronaut is subject to alterations of the environment which may seriously affect his performance or survivability. In a series of experiments, the stresses of hypoxia, vibration, high and low gravity, heat and noise were investigated to determine their effects upon visual function. With the possible exceptions of the latter two, all were found to produce measurable decrements in performance even at moderate levels; however, it is most remarkable that significant capability remains even in rather severe stress. Certain hypotheses regarding these visual decrements that have appeared in the literature are rejected on the basis of experimental evidence.

Acceleration↗