BACKGROUND: High temperatures are known to be associated with an increased risk of self-harm, but the influence of demographic changes and country-level indicators on the burden of heat-related self-harm remains unclear. This study examined the key factors driving changes in self-harm mortality linked to high temperatures and explored their impact at the country level. METHODS: This is an ecological study that analyzes data from the 2021 Global Burden of Disease (GBD) study, the World Bank, and the Climate Research Unit (CRU) were analyzed. Decomposition analyses were used to identify key factors driving changes in high temperature-related self-harm mortality between 1990 and 2021. A panel data model assessed the impact of national indicators on heat-related self-harm mortality. RESULTS: In 2021, 14,885 deaths globally were attributed to heat-related self-harm, a 41.94% increase from 1990, with low-middle SDI regions accounting for 47.84% of these deaths. While the global death rate from heat-related self-harm declined slightly over this period, South Asia and low-middle SDI regions contributed most to the decline. However, population aging exacerbated mortality rates. Demographic and meteorological factors were also linked to heat-related self-harm. CONCLUSION The global decline in heat-related self-harm mortality is largely driven by reductions in females, low-middle SDI regions, and South Asia. However, population aging and growth in these regions have added to the mortality burden, slowing the overall decline. Factors such as population density are also associated with heat-related self-harm. Targeted measures are needed to mitigate heat-induced self-harm more effectively in future.
Humans ; Self-Injurious Behavior/etiology* ; Hot Temperature/adverse effects* ; Global Health/statistics & numerical data* ; Female ; Male ; Adult ; Middle Aged ; Aged ; Young Adult ; Adolescent

BACKGROUND: Neck cooling is a practical method for preventing heat-related illness, however, its effectiveness in general workers is not well established. This study aimed to assess the effects of neck cooling on core body temperature and other physiological markers during exercise in a hot environment. METHODS: This randomized crossover trial was conducted from November 2023 to April 2024 at the Shared-Use Research Center at UOEH. Fourteen healthy adult males participated in the study under two conditions: with neck cooling (COOL) and without neck cooling (CON). All participants completed both conditions, and the order of condition assignment was determined by a random draw. Participants first rested for 10 minutes in a 28.0 °C, 50% relative humidity environment, followed by a rest in a 35.0 °C, 50% relative humidity environment for another 10 minutes. In the COOL condition, participants wore a neck cooler containing 1,200 g of ice while exercising at 50% Heart Rate Reserve on a bicycle ergometer for 20 minutes. Afterward, they rested for 15 minutes in the hot environment while still wearing the cooler. MAIN OUTCOME MEASURES: Core body temperature (rectal and esophageal), forehead skin temperature, and heart rate were continuously monitored and compared using a mixed model. Estimated sweat volume was calculated based on changes in body weight before and after the experiment. RESULTS: At the end of the rest period, no significant differences were observed between the COOL and CON conditions in rectal temperature (37.76 ± 0.18 °C versus 37.75 ± 0.24 °C, p = 0.9493), esophageal temperature (37.75 ± 0.30 °C versus 37.76 ± 0.23 °C, p = 0.7325), forehead skin temperature (36.87 ± 0.29 °C versus 36.88 ± 0.27 °C, p = 0.2160), or heart rate (104.18 ± 7.56 bpm versus 107.52 ± 7.40 bpm, p = 0.1035). Estimated sweat loss was similar between conditions (578 ± 175 g for CON versus 572 ± 242 g for COOL, p = 0.5066). While more participants felt cooler in the COOL condition, RPE showed no significant difference. CONCLUSION Neck cooling did not significantly affect core temperature or perceived exertion. Maintaining close contact with the skin at sufficiently low temperatures or utilizing cooling methods that prevent excessive negative feedback may be necessary to enhance the effectiveness of neck cooling.
Humans ; Male ; Cross-Over Studies ; Exercise/physiology* ; Adult ; Neck/physiology* ; Hot Temperature/adverse effects* ; Young Adult ; Body Temperature ; Heart Rate ; Skin Temperature ; Body Temperature Regulation ; Cold Temperature

BACKGROUND: Although smoking rates have been declining worldwide, new types of tobacco products have been gradually spreading in recent years, especially in Japan, where heated tobacco products (HTPs) users are rapidly increasing. Oxidative stress caused by reactive oxygen species (ROS) is one of the causes of smoking-induced carcinogenesis, respiratory diseases, and cardiovascular diseases. However, information on the amount of ROS contained in mainstream smoke from HTPs is limited. In this study, we measured the amount of ROS generated from HTPs to evaluate the oxidative stress-related toxicity of HTPs. METHODS: IQOS ILUMA, glo hyper+, and Ploom X ADVANCED were used as the HTP devices. Mainstream smoke was collected from each HTP according to Health Canada Intense regime (smoke volume, 55 mL; smoke duration, 2 s). The collected ROS were reacted with 2,7'-dichlorodihydrofluorescein reagents, and the amount of ROS was calculated as H₂O₂ equivalent from the fluorescence intensity obtained. RESULTS: The ROS in the mainstream smoke from IQOS ILUMA, glo hyper+ (high-temperature mode), and Ploom X ADVANCED was found to be 48.8 ± 8.6, 86.6 ± 12.6, and 40.8 ± 5.7 nmol H₂O₂/stick, respectively (n = 6, mean ± standard deviation), with the highest being from glo hyper+ (high-temperature mode). The amount of ROS was significantly higher in the high-temperature mode of glo hyper+ than in the standard mode of glo hyper+. Additionally, the estimated amount of ROS from smoking 20 heated sticks per day (674-2160 nmol H₂O₂/day) was equivalent to 2.2-96 times the amount of daily exposure to ROS in the urban atmosphere (approximately 22-300 nmol H₂O₂/day). CONCLUSIONS We found that ROS is generated from HTPs of different devices. This study suggests that HTPs users may be exposed to much more ROS than they are exposed to in normal life.
Reactive Oxygen Species/analysis* ; Tobacco Products/analysis* ; Smoke/analysis* ; Hot Temperature ; Japan ; Oxidative Stress

BACKGROUND: Heated tobacco products (HTPs) are widely used in Japan, following cigarettes, but their health effects remain unclear. HTPs are often considered a less harmful alternative to cigarettes and are commonly used by adults with asthma, even though smoking is one of the most obvious and treatable factors in asthma. We aimed to elucidate the association between HTP use and asthma symptoms in adults with asthma. METHODS: A total of 3,787 individuals with asthma were extracted from the data in the Japan COVID-19 and Society Internet Survey 2023, an ongoing longitudinal internet-based cohort study conducted by a nationwide internet research company in Japan. They were categorized into three groups (never, past, and current smokers) based on cigarette use. The association between HTP use and worsening of asthma symptoms within the previous 2 months in each group was analyzed using univariate and multivariate logistic regression analyses. Both exposure and outcomes were assessed by self-reporting. RESULTS: Among the participants, 2,470 (65.2%) were never smokers, 845 (22.3%) were past smokers, and 472 (12.5%) were current smokers. Overall, the proportion of HTP users was 429 (11.3%), and worsened asthma symptoms were observed in 400 (10.6%) individuals. The total proportion of HTP users and worsened asthma symptoms was 70 (2.8%) and 259 (10.5%) among never smokers, 180 (21.3%) and 72 (8.5%) among past smokers, and 179 (37.9%) and 69 (14.6%) among current smokers. After adjusting for confounders, the odds ratio (OR) was 3.25 (95% confidence interval [CI] 1.86-5.68, p < 0.001), 1.47 (95% CI 0.93-2.34, p = 0.1), and 2.23 (95% CI 1.46-3.43, p < 0.001) for never, past, and current cigarette smokers with HTP use, respectively, where never smokers without HTP use were set as the standard. CONCLUSION The use of HTPs, not only cigarette smoking, was associated with worsening of asthma symptoms in adults with asthma. Therefore, people need to understand the harmful effects of HTPs on asthma symptoms.
Humans ; Japan/epidemiology* ; Asthma/etiology* ; Male ; Female ; Middle Aged ; Adult ; Aged ; Tobacco Products/adverse effects* ; Internet ; Surveys and Questionnaires ; Young Adult ; Hot Temperature ; Longitudinal Studies

OBJECTIVE: To compare the cyclic fatigue resistance of nickel-titanium files made by 3 new heat treatment in simulated S-shaped root canals at different temperatures. METHODS: Gold heat-treated nickel-titanium files TruNatomy (25 mm, tip size 26#/0.04) and ProTaper Gold (25 mm, tip size 25#/0.08) were selected as the experimental group, M wire technique nickel-titanium file ProTaper Next (25 mm, tip size 25#/0.06) was selected as the control group. It was speculated that the Gold technique used in TruNatomy nickel-titanium file was R phase separation technique, which included a complete intermediate R-phase, increasing its flexibility. ProTaper Gold was a CM wire nickel-titanium file and the increased phase transformation temperature by heat treatment introduced martensite at room temperature, while it underwent gold heat treatment on the surface, generating an intermediate R phase during phase transformation, providing hyperelastic. ProTaper Next used M wire technique, M wire included austenite at room temperature, where heat mechanical processing introduced hardened martensite, which was incapable of participating phase transformation. Because of the lower elastic modulus of hardened martensite than austenite, the flexibility of the file was increased. Twenty instruments of each nickel-titanium file were submitted to the cyclic fatigue test by using a simulated canal with double curvatures at room tem-perature (24 ℃) and 65 ℃, 10 instruments of each nickel-titanium file were selected at each temperature (n=10). At the same temperature, the number of cyclic fatigue (NCF) and fragment length were analyzed by using One-Way analysis of variance at a significance level of P < 0.05. NCF and fragment length of the same nickel-titanium file at room temperature and 65 ℃ were compared by paired sample t test and the significance level was α=0.05. Fractured surfaces were analyzed by using scanning electron microscope. RESULTS: In double-curved canals, all the failure of the files due to cyclic fatigue was first seen in the apical curvature before the coronal curvature. At room temperature, in the apical curvature, NCF of TruNatomy was 344.4±96.6, ProTaper Gold was 175.0±56.1, ProTaper Next was 133.3±39.7, NCF of Tru Natomy was the highest (P < 0.05). In the coronal curvature, NCF of TruNatomy was 618.3± 75.3, ProTaper Gold was 327.5±111.8, ProTaper Next was 376.6±67.9, NCF of TruNatomy was also the highest (P < 0.05). There was no significant difference among the apical and coronal fragment length of the 3 nickel-titanium files (P>0.05). At 65 ℃, in the apical curvature, NCF of TruNatomy was 289.6±65.8, ProTaper Gold was 187.5±75.4, ProTaper Next was 103.0±38.5, NCF of TruNatomy was the highest (P < 0.05). In the coronal curvature, NCF of TruNatomy was 454.2±45.4, ProTaper Gold was 268.3±31.4, ProTaper Next was 283.8±31.7, NCF of TruNatomy was also the highest (P < 0.05). The apical fragment length of ProTaper Next was the highest (P < 0.05), and there was no significant difference among coronal fragment length of the 3 nickel-titanium files (P>0.05). Compared with room temperature, at 65 ℃, in the coronal curvature, NCF of TruNatomy decreased significantly (P < 0.05). The fractured surfaces of the three nickel-titanium files demonstrated typical cyclic fatigue. CONCLUSION Gold heat-treated nickel-titanium file had better cyclic fatigue resistance than M wire nickel-titanium file in S-shaped root canals.
Nickel/chemistry* ; Titanium/chemistry* ; Hot Temperature ; Root Canal Preparation/methods* ; Humans ; Materials Testing ; Gold/chemistry* ; Dental Alloys/chemistry* ; Stress, Mechanical

Exertional heatstroke is defined as a serious clinical syndrome typically characterized by impaired thermoregulation in high-temperature and high-humidity environments, resulting in heat production exceeding heat dissipation, causing core body temperature to exceed 40 centigrade, accompanied by central nervous system dysfunction and multi-organ failure. At present, the commonly used exertional heatstroke animal model is to put mice on a treadmill to run under high temperature and humidity conditions, but additional electrical stimulation is required to maintain the continuous running state of mice. However, additional electrical stimulation may lead to a further increase in mouse body temperature, which adversely affects the stability of the model. Therefore, medical staff from the intensive care unit of Xijing Hospital, Air Force Medical University, specially designed an intelligent experimental device for the exertional heatstroke model in mice, and obtained the national invention Patent of China (ZL 2022 1 1101721.2). The device integrates climate chamber, LCD touch screen and multiple sets of forced running wheel. Experimenters can observe and control the temperature, humidity, and wheel rotation parameters in the climate chamber in real time through a LCD touch screen. Each set of forced running wheel is equipped with a driving device that can be independently controlled. The device makes the mice run continuously without additional stimulation and enables the experimental personnel to observe and control the conditions in the climate chamber. The device successfully solves the problem of instability of the exertional heatstroke animal model and is convenient for the experimental personnel to control flexibly.
Animals ; Heat Stroke ; Mice ; Disease Models, Animal ; Hot Temperature ; Equipment Design ; Humidity ; Body Temperature

OBJECTIVE: To explore and quantify the association of hot night exposure during the sperm development period (0-90 lag days) with semen quality. METHODS: A total of 6,640 male sperm donors from 6 human sperm banks in China during 2014-2020 were recruited in this multicenter study. Two indices (i.e., hot night excess [HNE] and hot night duration [HND]) were used to estimate the heat intensity and duration during nighttime. Linear mixed models were used to examine the association between hot nights and semen quality parameters. RESULTS: The exposure-response relationship revealed that HNE and HND during 0-90 days before semen collection had a significantly inverse association with sperm motility. Specifically, a 1 °C increase in HNE was associated with decreased sperm progressive motility of 0.0090 (95% confidence interval [ CI]: -0.0147, -0.0033) and decreased total motility of 0.0094 (95% CI: -0.0160, -0.0029). HND was significantly associated with reduced sperm progressive motility and total motility of 0.0021 (95% CI: -0.0040, -0.0003) and 0.0023 (95% CI: -0.0043, -0.0002), respectively. Consistent results were observed at different temperature thresholds on hot nights. CONCLUSION Our findings highlight the need to mitigate nocturnal heat exposure during spermatogenesis to maintain optimal semen quality.
Humans ; Male ; Semen Analysis ; Adult ; Sperm Motility ; Hot Temperature/adverse effects* ; China ; Middle Aged ; Spermatozoa/physiology* ; Young Adult

Glucose oxidase (GOD) is an oxygen-consuming dehydrogenase that can catalyze the production of gluconic acid hydrogen peroxide from glucose, and its specific mechanism of action makes it promising for applications, while the low catalytic activity and poor thermostability have become the main factors limiting the industrial application of this enzyme. In this study, we used the glucose oxidase AtGOD reported with the best thermostability as the source sequence for phylogenetic analysis to obtain the GOD with excellent performance. Six genes were screened and successfully synthesized for functional validation. Among them, the glucose oxidase AhGODB derived from Aspergillus heteromorphus was expressed in Pichia pastoris and showed better thermostability and catalytic activity, with an optimal temperature of 40 ℃, a specific activity of 112.2 U/mg, and a relative activity of 47% after 5 min of treatment at 70 ℃. To improve its activity and thermal stability, we constructed several mutants by directed evolution combined with rational design. Compared with the original enzyme, the mutant T72R/A153P showcased the optimum temperature increasing from 40 to 50 ℃, the specific activity increasing from 112.2 U/mg to 166.1 U/mg, and the relative activity after treatment at 70 ℃ for 30 min increasing from 0% to 33%. In conclusion, the glucose oxidase mutants obtained in this study have improved catalytic activity and thermostability, and have potential for application.
Glucose Oxidase/chemistry* ; Enzyme Stability ; Aspergillus/genetics* ; Pichia/metabolism* ; Temperature ; Catalysis ; Fungal Proteins/metabolism* ; Hot Temperature

The plant AT-rich sequence and zinc-binding protein (PLATZ) family is composed of plant-specific zinc finger-like transcription factors, which play important roles in plant growth, development, and stress tolerance. In this study, to gain a better understanding of the PLATZ gene in C. sinensis and elucidate its response under drought and high temperature conditions, the PLATZ gene family of the C. sinensis cultivar 'Tieguanyin' was systematically identified, and a total of 12 CsPLATZ family members were identified. Expasy online and other bioinformatics tools were used to analyze the members of the PLATZ gene family in terms of protein physicochemical properties, phylogenetic relationships, cis-acting elements, gene structures, and intra- and inter-species collinearity. The results of phylogenetic analysis classified the CsPLATZ family members into 2 subfamilies. The conserved domains and gene structures of PLATZ family members within the same subfamily had a high degree of consistency, whereas a certain degree of diversity was observed among the subfamilies. Twelve PLATZ genes were unevenly distributed across 7 chromosomes of C. sinensis and the promoter regions of these genes had multiple cis-acting elements related to hormone and stress responses. The collinearity analysis showed that there were 4 pairs of duplication events in the CsPLATZ gene family, all of which were segmental duplications. Based on this gene family, C. sinensis had a closer evolutionary relationship with A. thaliana than with O. sativa. The transcriptome analysis showed that the expression levels of CsPLATZ family members varied in different tissue samples of C. sinensis. 6 genes (CsPLATZ-1, CsPLATZ-2, CsPLATZ-3, CsPLATZ-4, CsPLATZ-6, and CsPLATZ-8) with high expression in shoots, young leaves, and roots were selected for high temperature and drought stress treatments, and their expression was quantified by qRT-PCR. The results indicated that the six genes might play important roles in the response to drought stress. In addition, CsPLATZ-2 and CsPLATZ-8 might have important functions in the response to high temperature stress. The results of this study will contribute to a better understanding of the biological functions of PLATZ genes and their possible roles in the growth, development, and stress responses of C. sinensis.
Droughts ; Camellia sinensis/physiology* ; Phylogeny ; Gene Expression Regulation, Plant ; Plant Proteins/genetics* ; Stress, Physiological/genetics* ; Multigene Family ; Transcription Factors/genetics* ; Hot Temperature ; Genes, Plant

Heat acclimation provides cardiovascular protection in high-temperature environments through multilevel mechanisms; however, the complete molecular basis of its effects remains unclear. In this paper, we systematically review the effects of heat acclimation on blood volume, vascular function, cardiac structure, energy metabolism, and anti-stress regulation, revealing their potential mechanisms in cardiovascular adaptive protection. We also summarizes the multilevel responses induced by heat stress and heat acclimation, including the modulatory effects of heat acclimation on heat shock proteins (HSPs), hypoxia inducible factor 1 (HIF-1), and apoptotic pathways. Additionally, we highlights the comprehensive protective effects of heat acclimation across various stressors (e.g., hypoxia, heat stress). This review provides a significant physiological basis for cardiovascular disease management and sports medicine, emphasizing the potential application of heat acclimation in response to multiple stressors and supporting its role as an effective tool in cardiovascular health management and stress protection interventions.
Humans ; Acclimatization/physiology* ; Hot Temperature ; Heat-Shock Proteins/metabolism* ; Animals ; Heat-Shock Response/physiology* ; Hypoxia-Inducible Factor 1/metabolism* ; Apoptosis/physiology*