Short-Term Effects of Lower Air Temperature and Cold Spells on Myocardial Infarction Hospitalizations in Sweden.

BACKGROUND: Lower air temperature and cold spells have been associated with an increased risk of various diseases. However, the short-term effect of lower air temperature and cold spells on myocardial infarction (MI) remains incompletely understood. OBJECTIVES: The purpose of this study was to investigate the short-term effects of lower air temperature and cold spells on the risk of hospitalization for MI in Sweden. METHODS: This population-based nationwide study included 120,380 MI cases admitted to hospitals in Sweden during the cold season (October to March) from 2005 to 2019. Daily mean air temperature (1 km2 resolution) was estimated using machine learning, and percentiles of daily temperatures experienced by individuals in the same municipality were used as individual exposure indicators to account for potential geographic adaptation. Cold spells were defined as periods of at least 2 consecutive days with a daily mean temperature below the 10th percentile of the temperature distribution for each municipality. A time-stratified case-crossover design incorporating conditional logistic regression models with distributed lag nonlinear models using lag 0 to 1 (immediate) and 2 to 6 days (delayed) was used to evaluate the short-term effects of lower air temperature and cold spells on total MI, non-ST-segment elevation myocardial infarction (NSTEMI) and ST-segment elevation myocardial infarction (STEMI). RESULTS: A decrease of 1-U in percentile temperature at a lag of 2 to 6 days was significantly associated with increased risks of total MI, NSTEMI, and STEMI, with ORs of 1.099 (95% CI: 1.057-1.142), 1.110 (95% CI: 1.060-1.164), and 1.076 (95% CI: 1.004-1.153), respectively. Additionally, cold spells at a lag of 2 to 6 days were significantly associated with increased risks for total MI, NSTEMI, and STEMI, with ORs of 1.077 (95% CI: 1.037-1.120), 1.069 (95% CI: 1.020-1.119), and 1.095 (95% CI: 1.023-1.172), respectively. Conversely, lower air temperature and cold spells at a lag of 0 to 1 days were associated with decreased risks for MI. CONCLUSIONS: This nationwide case-crossover study reveals that short-term exposures to lower air temperature and cold spells are associated with an increased risk of hospitalization for MI at lag 2 to 6 days.

Establishment and characterization of a gill cell line from Takifugu obscurus and transcriptome analysis of its gene expression profiles upon low temperature.

Takifugu obscurus is a farmed fish of great economic importance in China. The rapid development of T. obscurus aquaculture industry has been accompanied by disease and low-temperature stress, resulting in huge economic losses. Cell lines are used extensively in teleost physiology and pathology as the most cost-effective platform for in vitro research. A novel gill cell line of T. obscurus (named TOG) was first successfully established, and passed through 52 generations. The optimal conditions for TOG growth were 20 % FBS concentration and 24 °C, TOG could be grown in both hypotonic (150 mOsmol-kg-1) and hypertonic (600 mOsmol-kg-1) environments. TOG was determined to be derived from T. obscurus by sequencing the mitochondrial COI gene. Karyotype analysis revealed that the chromosome number of TOG was 44 (2n = 44). Transfection experiment showed that TOG was able to express foreign genes. Furthermore, several immune-related genes were significantly up-regulated in TOG after LPS and poly (I:C) stimulation, including tlr3, isg15, il1ß and il10. Additionally, transcriptome analysis of TOG under low-temperature stress (24 °C, 18 °C, 12 °C, 10 °C and 8 °C) found that differentially expressed genes (DEGs) were significantly clustered in several immunological and energy metabolic pathways, and cold stress could disrupt the immune barrier and reduce immunity by downregulating the immune-related pathways. Additionally, weighted gene co-expression network analysis (WGCNA) revealed that bule module and turquoise module, which were closely correlated with low temperature and the degree of fish damage, were both predominantly found in PPAR, NOD-like receptor and Toll-like receptor signaling pathway. Hub genes were identified in these two modules, including mre11, clpb, dhx15, ddx18 and utp15. TOG cell line will become an effective experimental platform for genetic and immunological research, and our results would help us gain a deeper insight into the molecular mechanism of cold tolerance in teleost.

A 19-year analysis of hot and cold temperature burdens on mortality in Amman, Jordan.

BACKGROUND: Most studies on climate-induced health effects have primarily focused on developed countries. Jordan, in particular, has seen limited research in quantifying the differential impacts of temperature on mortality. Jordan's unique demographic composition, characterized by significant refugee population influxes, necessitates research in this area to identify vulnerable populations. This study aims to: 1) quantify the mortality burden of hot and cold temperature in Amman, Jordan, and 2) identify vulnerable groups within the population. METHODS: We collected 19 years of daily all-cause mortality records from 2000 to 2018 in Amman, Jordan, aggregated by sex and nationality. We used a time series design in a distributed lag non-linear model for temperature to estimate non-linear associations and lagged effects of temperature on mortality across sex and nationality. We calculated attributable mortality for temperatures above (heat) and below (cold) the minimum mortality temperature for each category. RESULTS: We analyzed 184,166 all-cause mortalities; 106,977 were males, and 22,118 were non-Jordanians. Amman's calculated minimum mortality temperatures were 23.2 °C for males, 21.5 °C for females, 22.3 °C for Jordanians, and 24.7 °C for non-Jordanians. Our findings reveal that females exhibited greater vulnerability to heat, with a 2.59 % (1.54 %, 3.59 %) heat attributable mortality fraction compared to 1.17 % (0.53 %, 1.80 %) for males, while non-Jordanians were susceptible to cold, with an 8.36 % (2.83 %, 14.66 %) cold attributable mortality fraction compared to 5.91 % (4.37 %, 7.41 %) for Jordanians. CONCLUSION: This study highlights the increased vulnerability of marginalized communities in Amman to temperature extremes. It emphasizes the need for further research to identify at-risk groups not only in Amman but also in other cities across Jordan. Such research is crucial for developing targeted protective strategies to safeguard these populations.

Mortality risk and burden of sudden cardiac arrest associated with hot nights, heatwaves, cold spells, and non-optimum temperatures in 0.88 million patients: An individual-level case-crossover study.

Sudden cardiac arrest (SCA) is a global health concern, imposing a substantial mortality burden. However, the understanding of the impact of various extreme temperature events, when accounting for the effect of daily average temperature on SCA, remains incomplete. Additionally, the assessment of SCA mortality burden associated with temperatures from an individual-level design is limited. This nationwide case-crossover study collected individual SCA death records across all (2844) county-level administrative units in the Chinese Mainland from 2013 to 2019. Four definitions for hot nights and ten for both cold spells and heatwaves were established using various temperature thresholds and durations. Conditional logistic regression models combined with distributed lag nonlinear models were employed to estimate the cumulative exposure-response relationships. Based on 887,662 SCA decedents, this analysis found that both hot nights [odds ratio (OR): 1.28; attributable fraction (AF): 1.32 %] and heatwaves (OR: 1.40; AF: 1.29 %) exhibited significant added effects on SCA mortality independent of daily average temperatures, while cold spells were not associated with an elevated SCA risk after accounting for effects of temperatures. Cold temperatures [below the minimum mortality temperature (MMT)] accounted for a larger mortality burden than high temperatures (above the MMT) [AF: 12.2 % vs. 1.5 %]. Higher temperature-related mortality risks and burdens were observed in patients who experienced out-of-hospital cardiac arrest compared to those with in-hospital cardiac arrest. This nationwide study presents the most compelling and comprehensive evidence of the elevated mortality risk and burden of SCA associated with extreme temperature events and ambient temperatures amid global warming.

Increased Risk of Influenza Infection During Cold Spells in China: National Time Series Study.

Background: Studies have reported the adverse effects of cold events on influenza. However, the role of critical factors, such as characteristics of cold spells, and regional variations remain unresolved. Objective: We aimed to systematically evaluate the association between cold spells and influenza incidence in mainland China. Methods: This time series analysis used surveillance data of daily influenza from 325 sites in China in the 2014-2019 period. A total of 15 definitions of cold spells were adopted based on combinations of temperature thresholds and days of duration. A distributed lag linear model was used to estimate the short-term effects of cold spells on influenza incidence during the cool seasons (November to March), and we further explored the potential impact of cold spell characteristics (ie, intensity, duration, and timing during the season) on the estimated associations. Meta-regressions were used to evaluate the modification effect of city-level socioeconomic indicators. Results: The overall effect of cold spells on influenza incidence increased with the temperature threshold used to define cold spells, whereas the added effects were generally small and not statistically significant. The relative risk of influenza-associated with cold spells was 3.35 (95% CI 2.89-3.88), and the estimated effects were stronger during the middle period of cool seasons. The health effects of cold spells varied geographically and residents in Jiangnan region were vulnerable groups (relative risk 7.36, 95% CI 5.44-9.95). The overall effects of cold spells were positively correlated with the urban population density, population size, gross domestic product per capita, and urbanization rate, indicating a sterner response to cold spells in metropolises. Conclusions: Cold spells create a substantial health burden on seasonal influenza in China. Findings on regional and socioeconomic differences in the health effects of cold spells on seasonal influenza may be useful in formulating region-specific public health policies to address the hazardous effects of cold spells.

Association between temperatures and type 2 diabetes: A prospective study in UK Biobank.

OBJECTIVE: This study aims to prospectively examine the association between temperatures and the occurrence of type 2 diabetes (T2D). METHODS: We used the CPH models to analyze 103,215 non-diabetic participants in the UK Biobank cohort who answered questions about workplace temperature, to evaluate the survival relationship, and the interaction effects of working environmental temperature and T2D-related genetic risk scores (GRS) on the occurrence of T2D. The occurrence of T2D was assessed by hospital inpatient records. The weighted T2D-related GRS were calculated. RESULTS: During 1,355,200.6 person-years follow-up, a total of 2436 participants were documented as having diagnosed T2D. After adjustment, compared to the comfortable group, the participants working in non-comfortable environmental temperature had greater risk of T2D (HR: 1.27, 95 %CI: 1.04 to 1.55, for cold; HR: 1.32, 95 %CI: 1.17 to 1.48 for hot; HR: 1.51, 95 %CI: 1.38 to 1.65 for alternate). Similarly, individuals exposed to different levels of genetic risk scores in alternating hot and cold work environments had a higher risk of developing type 2 diabetes. CONCLUSIONS: This study found working in single non-comfortable environmental temperatures was associated with greater risk of T2D occurrence, and exposure to alternating environmental temperatures had the highest risk of range and severity.

Effects of combined exposure to fine particulate matter and cold waves and on IHD hospitalizations at low and high altitudes.

Climate change and air pollution are major challenges facing the world today. Cold waves and air pollution significantly impact ischemic heart disease (IHD), but the extent of these effects at different altitudes remains unclear, especially their interactions. We collected daily meteorological, pollutant, and IHD hospitalization data from Xining and Xinxiang from 2016 to 2021. Using a time-stratified case-crossover approach, we fitted conditional Poisson regression models to assess the association between cold waves, PM2.5, and IHD hospitalizations and quantified their interactions. Additionally, we calculated the attributable fraction (AF) and attributable number (AN) of hospitalizations due to exposure to cold waves and medium to high-level PM2.5. We also performed stratified analyses by altitude, gender, and age. Both cold waves and PM2.5 were positively associated with IHD hospitalization rates in Xining and Xinxiang, but the differences between the two regions were not significant. The relative risk of cold waves was 1.15 (1.07, 1.24) in Xining and 1.16 (1.11, 1.21) in Xinxiang. In Xining, there was an interaction between cold waves and different levels of PM2.5. We estimated the attributable fraction due to the joint exposure of cold waves and PM2.5 to be 0.14-0.49 in Xining and 0.26-0.36 in Xinxiang. Older adults and males faced higher risks. This study highlights the importance of reducing PM2.5 exposure and optimizing extreme weather warning systems and suggests further exploration of the impacts of individual behaviors and regional characteristics on IHD.

Effects of cold and hot temperatures on the renal function of people with chronic disease.

OBJECTIVES: This study investigated the effects of hot and cold temperature on the renal function of people with chronic diseases, such as diabetes, hypertension, and chronic kidney disease, using large-scale clinical data. METHODS: We used retrospective cohort data from the Clinical Data Warehouse of the Seoul St Mary's Hospital, which contains clinical, diagnostic, laboratory, and other information about all patients who have visited the hospital since 1997. We obtained climate data from the Automated Synoptic Observing System of the Korea Meteorological Administration. The heat index was used as a measuring tool to evaluate heat exposure by indexing the actual heat that individuals feel according to temperature and humidity. The estimated glomerular filtration rate (eGFR) was calculated using the Chronic Kidney Disease Epidemiology Collaboration equation. To investigate changes in renal function trends with heat index, this study used generalized additive mixed models. RESULTS: Renal function decreased linearly with increasing heat index after approximately 25°C, which was considered the flexion point of temperature. A linear decrease in the eGFR was observed with the effects of 0 to 5 lag days. Although there was a correlation observed between the decrease in eGFR and temperatures below -10°C, the results did not indicate statistical significance. CONCLUSIONS: The results of our study provide scientific evidence that high temperatures affect the renal function of people with chronic diseases. These results can help prevent heat-related morbidity by identifying those who are more likely to develop renal disease and experience worsening renal function.

Temperature-related neonatal deaths attributable to climate change in 29 low- and middle-income countries.

Exposure to high and low ambient temperatures increases the risk of neonatal mortality, but the contribution of climate change to temperature-related neonatal deaths is unknown. We use Demographic and Health Survey (DHS) data (n = 40,073) from 29 low- and middle-income countries to estimate the temperature-related burden of neonatal deaths between 2001 and 2019 that is attributable to climate change. We find that across all countries, 4.3% of neonatal deaths were associated with non-optimal temperatures. Climate change was responsible for 32% (range: 19-79%) of heat-related neonatal deaths, while reducing the respective cold-related burden by 30% (range: 10-63%). Climate change has impacted temperature-related neonatal deaths in all study countries, with most pronounced climate-induced losses from increased heat and gains from decreased cold observed in countries in sub-Saharan Africa. Future increases in global mean temperatures are expected to exacerbate the heat-related burden, which calls for ambitious mitigation and adaptation measures to safeguard the health of newborns.

Cold-Induced Vasodilation, Rewarming, and Dexterity Impairment Following Second-Degree Frostbite.

Frostbite, a severe cold injury resulting from exposure to subfreezing temperatures, damages the skin and underlying tissues of the affected area and ranges in severity from first to fourth degree. This case report investigates the impact of second-degree frostbite suffered by a marine during winter training on cold-induced vasodilation (CIVD). Comparisons of CIVD before and after the injury revealed significant alterations in CIVD responses. CIVD, a physiological mechanism characterized by blood vessel dilation in response to cold exposure, plays a crucial role in operating in cold-weather environments and enhancing dexterity. The marine exhibited prolonged CIVD onset time, lower finger temperatures, increased pain sensations, and diminished dexterity after the frostbite injury during follow-up CIVD testing. The findings suggest that the frostbite-induced damage possibly compromised the microvascular function, contributing to the observed changes in CIVD. The marine reported persistent cold sensitivity and difficulty in maintaining hand warmth when assessed postinjury. This case underscores the potential long-term consequences of frostbite on CIVD and manual dexterity, emphasizing the importance of understanding these physiological changes for individuals engaged in cold-weather activities, particularly for military and occupational personnel.

Future temperature-related mortality in the UK under climate change scenarios: Impact of population ageing and bias-corrected climate projections.

BACKGROUND: Exposure to heat and cold poses a serious threat to human health. In the UK, hotter summers, milder winters and an ageing population will shift how populations experience temperature-related health burdens. Estimating future burdens can provide insights on the drivers of temperature-related health effects and removing biases in temperature projections is an essential step to generating these estimates, however, the impact of various methods of correction is not well examined. METHODS: We conducted a detailed health impact assessment by estimating mortality attributable to temperature at a baseline period (2007-2018) and in future decades (2030s, 2050s and 2070s). Epidemiological exposure-response relationships were derived for all England regions and UK countries, to quantify cold and heat risk, and temperature thresholds where mortality increases. UK climate projections 2018 (UKCP18)were bias-corrected using three techniques: correcting for mean bias (shift or SH), variability (bias-correction or BC) and extreme values (quantile mapping or QM). These were applied in the health impact assessment, alongside consideration of population ageing and growth to estimate future temperature-related mortality. FINDINGS: In the absence of adaptation and assuming a high-end emissions scenario (RCP8.5), annual UK temperature-related mortality is projected to increase, with substantial differences in raw vs. calibrated projections for heat-related mortality, but smaller differences for cold-related mortality. The BC approach gave an estimated 29 deaths per 100,000 in the 2070s, compared with 50 per 100,000 using uncorrected future temperatures. We also found population ageing may exert a bigger impact on future mortality totals than the impact from future increases in temperature alone. Estimating future health burdens associated with heat and cold is an important step towards equipping decision-makers to deliver suitable care to the changing population. Correcting inherent biases in temperature projections can improve the accuracy of projected health burdens to support health protection measures and long-term resilience planning.

Mortality risk and burden of aortic aneurysm and dissection attributable to low temperatures: A nationwide case-crossover analysis in Brazil, a predominantly tropical country.

BACKGROUND: Low temperatures are adverse contributors to cardiovascular diseases, but the associations between short-term exposure to cold and the risk of death from aortic dissection and aneurysm remain unclear, particularly in tropical regions. OBJECTIVE: This study was conducted based on 123,951 records of deaths caused by aortic dissection and aneurysms extracted from the national Mortality Information System in Brazil between 2000 and 2019. METHODS: Relative risks and 95 % confidence intervals (CI) for the aortic-related deaths associated with low ambient temperatures were estimated using the conditional logistic model combined with the distributed lag nonlinear model. Subgroup analyses were performed by age group, sex, race, education level, and residential region. Furthermore, this study calculated the number and fraction of aortic-related deaths attributed to temperatures below the temperature threshold to quantify the cold-related mortality burden of aortic diseases. RESULTS: During the study period, aortic-related deaths and mortality rates in Brazil exhibited a steady increase, rising from 4419 (2.66/100,000) in 2000 to 8152 (3.88/100,000) in 2019. Under the identified temperature threshold (26 °C), per 1 °C decrease in daily mean temperature was associated with a 4.77 % (95 % CI: 4.35, 5.19) increase in mortality risk of aortic-related diseases over lag 0-3 days. Females, individuals aged 50 years or older, Asian and Black race, and northern residents were more susceptible to low temperatures. Low temperatures were responsible for 19.10 % (95 % CI: 17.71, 20.45) of aortic-related deaths in Brazil. CONCLUSION: This study highlights that low temperatures were associated with an increased risk of aortic-related deaths, with a remarkable burden even in this predominantly tropical country.

Surviving the cold: Assessing long-term outcomes among Korean CKD patients exposed to low perceived temperature during winter.

Perceived temperature (PT), which encompasses meteorological factors such as wind speed, cloud cover, and humidity, reflects the actual effect of temperature on the human body. However, limited data exist on the health implications of prolonged exposure to low temperatures during winter in individuals with chronic kidney disease (CKD). We investigated the association between winter PT and long-term outcomes among CKD patients. A total of 32,870 CKD patients from three tertiary hospitals in Seoul were enrolled in this retrospective study (2001-2018). PT was calculated using Staiger's equation, integrating temperature data from 29 automated weather stations across Seoul, along with dew point temperature, wind velocity, and cloud cover data. Kriging interpolation was utilized to estimate PT values at the patients' locations. Overall mortality and major adverse cardiovascular events (MACEs) were assessed using a time-varying Cox proportional hazards model. Additionally, the Cox regression model evaluated PT corresponding to temperature thresholds for cold surge watches or warnings. Over a median follow-up of 6.14 ± 3.96 years, 6147 deaths (18.7%) were recorded. We found that as the average or minimum PT and Ta decreased by 1 °C, the risk of overall mortality significantly increased. In multivariable analyses, the hazard ratio (HR) for the average PT was 1.049 (95% confidence interval [CI] 1.028-1.071), and that for the minimum PT was 1.038 (CI 1.027-1.052). Furthermore, a cold surge warning at a PT of -25.63 °C indicated an HR of 1.837 (CI 1.764-1.914) and a C-index of 0.792. The increased risk of mortality was more pronounced in patients with low or middle socioeconomic statuses. For MACEs, lower average and minimum PT and Ta were associated with an increased risk, following a similar trend to overall mortality, although not all results reached statistical significance. These findings emphasize the importance of targeted public health policies to mitigate risks among vulnerable CKD patients.

The temporal variation in the effects of extreme temperature on respiratory mortality: Evidence from 136 cities in China, 2006-2019.

BACKGROUND: In the context of climate change and urbanization, the temporal variation of the adverse health effect of extreme temperature has attracted increasing attention. METHODS: The meteorological data and the daily death records of mortality from respiratory diseases of 136 Chinese cities were from 2006 to 2019. Heat wave and cold spell were selected as the indicator events of extreme high temperature and extreme low temperature, respectively. The generalized linear model and time-varying distributed lag model were used to perform a two-stage time-series analysis to evaluate the temporal variation of the mortality risk associated with extreme temperature in the total population, sub-populations (sex- and age- specific) and different regions (climatic zone and relative humidity level). RESULTS: During the study period, relative risk (RR) of respiratory mortality associated with heat wave decreased from 1.22 (95 %CI: 1.07-1.39) to 1.13 (95 %CI: 1.01-1.26) in the total population, and RR of respiratory mortality associated with cold spell decreased from 1.30 (95 %CI: 1.14-1.49) to 1.17 (95 %CI: 1.08-1.26). The impact of heat wave reduced in the males (P = 0.044) and in the females as with cold spell (P < 0.001). The respiratory mortality risk of people over 65 associated with cold spell decreased (P = 0.040 for people aged 65-74 and P < 0.001 for people over 75). The effect of cold spell reduced in cities from tropical or arid zone (P = 0.035). The effects of both heat wave and cold spell decreased in cities with the relative humidity in the first quartile (P = 0.046 and 0.010, respectively). CONCLUSION: The impact of heat wave on mortality of respiratory diseases decreased mainly in males and cities with the lowest relative humidity, while the impact of cold spell reduced in females, people over 65 and tropical and arid zone, suggesting adaptation to extreme temperature of Chinese residents to some extent.

Butyrate attenuates cold-induced hypertension via gut microbiota and activation of brown adipose tissue.

OBJECTIVE: Chronic exposure to cold temperature is known to elevate blood pressure, leading to a condition known as cold-induced hypertension (CIH). Our previous research suggested correlations between alterations in gut microbiota, decrease in butyrate level, and the onset and progression of CIH. However, the role of butyrate in CIH and the underlying mechanisms need further investigation. METHODS: We exposed Specific Pathogen Free (SPF) rats to continuous cold temperature (4 ± 1 °C) for 6 weeks to establish a CIH rat model. Rats were divided into different groups by dose and duration, and the rats under cold were administered with butyrate (0.5 or 1 g/kg/day) daily. We assessed hypertension-associated phenotypes, pathological morphological changes, and endocrine-related phenotypes of brown adipose tissue (BAT). The effects of butyrate on gut microbiota and intestinal content metabolism were evaluated by 16s RNA sequencing and non-targeted metabolomics, respectively. RESULTS: The systolic blood pressure (SBP) of rats exposed to cold after supplemented with butyrate were significantly lower than that of the Cold group. Butyrate may increase the species, abundance, and diversity of gut microbiota in rats. Specifically, butyrate intervention enriched beneficial bacterial genera, such as Lactobacillaceae, and decreased the levels of harmful bacteria genera, such as Actinobacteriota and Erysipeiotrichaceae. Cold exposure significantly increased BAT cells and the number of mitochondria. After butyrate supplementation, the levels of peroxisome proliferator-activated receptor gamma coactivator 1a and fibroblast growth factor 21 in BAT were significantly elevated (P < 0.05), and the volume and number of lipid droplets increased. The levels of ANG II and high-density lipoprotein were elevated in the Cold group but decreased after butyrate supplementation. CONCLUSION: Butyrate may attenuate blood pressure in CIH by promoting the growth of beneficial bacteria and the secretion of beneficial derived factors produced by BAT, thus alleviating the elevation of blood pressure induced by cold. This study demonstrates the anti-hypertensive effects of butyrate and its potential therapeutic mechanisms, offering novel insights to the prevention and treatment of CIH in populations living or working in cold environments.