Combined cold-water immersion and breathwork may be associated with improved mental health and reduction in the duration of upper respiratory tract infection - a case-control study

A polar plunge is a term referring to an ice-cold water immersion (CWI), usually in the winter period. It is also a part of a specific training program (STP) which currently gains popularity worldwide and was proven to display paradigm-shifting characteristics. The aim of this study was to compare the indices of mental functioning (including depression, anxiety, mindfulness) and duration of upper respiratory tract infection (URTI) measured among the study participants. A set of questionnaires was distributed via the Internet. Participants declaring regular STP practice were selected (N = 77). Two groups were matched based on a case-control principle: the first one (the control group) comprised participants who did not declare nor CWI practice, nor STP practice. The second one comprised participants declaring regular CWI practice only. The CWI only group displayed better mental health indices and shorter URTIs compared to the control group. Moreover, the STP group also displayed better general mental health, less somatic complaints, and shorter URTIs compared to the CWI only group. This study suggests the existence of CWI's potential in boosting mental health and immune system functioning, however when complemented by a specific breathwork, this potential can be increased. However, further research is required.

Effect of Cold Adaptation on the State of Cardiovascular System and Cardiac Tolerance to Ischemia/Reperfusion Injury

Despite the unconditional success achieved in the treatment and prevention of AMI over the past 40 years, mortality in this disease remains high. Hence, it is necessary to develop novel drugs with mechanism of action different from those currently used in clinical practices. Studying the molecular mechanisms involved in the cardioprotective effect of adapting to cold could contribute to the development of drugs that increase cardiac tolerance to the impact of ischemia/reperfusion. An analysis of the published data shows that the long-term human stay in the Far North contributes to the occurrence of cardiovascular diseases. At the same time, chronic and continuous exposure to cold increases tolerance of the rat heart to ischemia/ reperfusion. It has been demonstrated that the cardioprotective effect of cold adaptation depends on the activation of ROS production, stimulation of the β2-adrenergic receptor and protein kinase C, MPT pore closing, and KATP channel.

Impacts of ethanol blended fuels and cold temperature on VOC emissions from gasoline vehicles in China

The Chinese central government has initiated pilot projects to promote the adoption of gasoline containing 10%v ethanol (E10). Vehicle emissions using ethanol blended fuels require investigation to estimate the environmental impacts of the initiative. Five fuel formulations were created using two blending methods (splash blending and match blending) to evaluate the impacts of formulations on speciated volatile organic compounds (VOCs) from exhaust emissions. Seven in-use vehicles covering China 4 to China 6 emission standards were recruited. Vehicle tests were conducted using the Worldwide Harmonized Test Cycle (WLTC) in a temperature-controlled chamber at 23 °C and -7 °C. Splash blended E10 fuels led to significant reductions in VOC emissions by 12%-75%. E10 fuels had a better performance of reducing VOC emissions in older model vehicles than in newer model vehicles. These results suggested that E10 fuel could be an option to mitigate the VOC emissions. Although replacing methyl tert-butyl ether (MTBE) with ethanol in regular gasoline had no significant effects on VOC emissions, the replacement led to lower aromatic emissions by 40%-60%. Alkanes and aromatics dominated approximately 90% of VOC emissions for all vehicle-fuel combinations. Cold temperature increased VOC emissions significantly, by 3-26 folds for all vehicle/fuel combinations at -7 °C. Aromatic emissions were increased by cold temperature, from 2 to 26 mg/km at 23 °C to 33-238 mg/km at -7 °C. OVOC emissions were not significantly affected by E10 fuel or cold temperature. The ozone formation potential (OFP) and secondary organic aerosol formation potential (SOAFP) of splash blended E10 fuels decreased by up to 76% and 81%, respectively, compared with those of E0 fuels. The results are useful to update VOC emission profiles of Chinese vehicles using ethanol blended gasoline and under low-temperature conditions.

Dietary fat supplementation relieves cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis in pigs

BACKGROUND

Cold stress has negative effects on the growth and health of mammals, and has become a factor restricting livestock development at high latitudes and on plateaus. The gut-liver axis is central to energy metabolism, and the mechanisms by which it regulates host energy metabolism at cold temperatures have rarely been illustrated. In this study, we evaluated the status of glycolipid metabolism and oxidative stress in pigs based on the gut-liver axis and propose that AMP-activated protein kinase (AMPK) is a key target for alleviating energy stress at cold temperatures by dietary fat supplementation.

RESULTS

Dietary fat supplementation alleviated the negative effects of cold temperatures on growth performance and digestive enzymes, while hormonal homeostasis was also restored. Moreover, cold temperature exposure increased glucose transport in the jejunum. In contrast, we observed abnormalities in lipid metabolism, which was characterized by the accumulation of bile acids in the ileum and plasma. In addition, the results of the ileal metabolomic analysis were consistent with the energy metabolism measurements in the jejunum, and dietary fat supplementation increased the activity of the mitochondrial respiratory chain and lipid metabolism. As the central nexus of energy metabolism, the state of glycolipid metabolism and oxidative stress in the liver are inconsistent with that in the small intestine. Specifically, we found that cold temperature exposure increased glucose transport in the liver, which fully validates the idea that hormones can act on the liver to regulate glucose output. Additionally, dietary fat supplementation inhibited glucose transport and glycolysis, but increased gluconeogenesis, bile acid cycling, and lipid metabolism. Sustained activation of AMPK, which an energy receptor and regulator, leads to oxidative stress and apoptosis in the liver; dietary fat supplementation alleviates energy stress by reducing AMPK phosphorylation.

CONCLUSIONS

Cold stress reduced the growth performance and aggravated glycolipid metabolism disorders and oxidative stress damage in pigs. Dietary fat supplementation improved growth performance and alleviated cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis. In this study, we highlight the importance of AMPK in dietary fat supplementation-mediated alleviation of host energy stress in response to environmental changes.

Designing and validating an experimental protocol to induce airway narrowing in older adults with and without asthma

BACKGROUND

Persons with asthma may experience excessive airway narrowing due to exercise or exposure to cold air, worsening their daily functionality. Exercise has several benefits for asthma control, but it may induce airway narrowing in some persons with asthma. When combined with cold temperatures, it introduces another layer of challenges. Therefore, managing this interaction is crucial to increase the quality of life in individuals with asthma. The purpose of this study was to develop a reliable experimental protocol to assess the effects of exercise and cold air on airway narrowing in adults with asthma in a controlled and safe environment.

METHODS

This study was a randomized cross-over study in adults with and without asthma. Participants underwent a protocol involving a 10-min seated rest, followed by a 10-min cycling on a stationary bike in different temperatures of 0, 10, or 20 ∘ C. The sequence of room temperatures was randomized, and there was a 30-min interval for recovery between each temperature transition. In each temperature, to measure lung function and respiratory symptoms, oscillometry and a questionnaire were used at 0 min (baseline), after 10 min of sitting and before starting biking (pre-exercise), and after 10 min of biking (post-exercise). At each room temperature, the changes in airway mechanics and asthma symptoms among baseline, pre-exercise, and post-exercise were compared with one-way repeated measures ANOVA or Friedman Rank Test. Within each arm, cardiac and thoraco-abdominal motion respiration signals were also measured continuously using electrodes and calibrated respiratory inductance plethysmographs, respectively.

RESULTS

A total of 23 persons with asthma (11 females, age: 56.3 ± 10.9 years, BMI: 27.4 ± 5.7 kg/m2) and 6 healthy subjects (3 females, age: 61.8 ± 9.1 years, BMI: 28.5 ± 3.1 kg/m2) were enrolled in the study. Cold temperature of 0∘ C induced airway narrowing in those with and without asthma after 10 and 20 min, respectively. Exercise intervention had significant changes in airway narrowing in participants with asthma in the range of 10-20∘ C. Our results showed that in asthma, changes in subjective respiratory symptoms were due to both cold temperatures of 0 and 10∘ C and exercise in the 0-20∘ C range. Respiratory symptoms were not noticed among the healthy participants.

CONCLUSION

In conclusion, our findings suggest that exposure to cold temperatures of 0∘ C could serve as a reliable method in the experimental protocol for inducing airway narrowing in asthma. The impact of exercise on airway narrowing was more variable among participants. Understanding these triggers in the experimental protocol is essential for the successful management of asthma in future studies.

Isolation, characterization, and application of a novel, lytic phage vB_SalA_KFSST3 with depolymerase for the control of Salmonella and its biofilm on cantaloupe under cold temperature

This study investigated the efficacy of a novel Salmonella phage with depolymerase activity to control S. Typhimurium (ST) and its biofilm on cantaloupes, for the first time, under simulated cold temperature. vB_SalA_KFSST3 forming a halo zone was isolated and purified from a slaughterhouse with a final concentration of 12.1 ± 0.1 log PFU/mL. Based on the morphological and bioinformatics analyses, vB_SalA_KFSST3 was identified as a novel phage belonging to the family Ackermannviridae. Before employing the phage on cantaloupe, its genetic characteristics, specificity, stability, and bactericidal effect were investigated. Genetic analyses confirmed its safety and identified endolysin and two depolymerase domains possessing antibiofilm potential. In addition, the phage exhibited a broad specificity with great efficiencies toward five Salmonella strains at 4 °C, 22 °C, and 37 °C, as well as stable lytic activity over a wide range of pHs (3 to 11) and temperatures (-20 °C to 60 °C). The optimal multiplicity of infection (MOI) and exposure time of phage were determined to be 100 and 2 h, respectively, based on the highest bacterial reduction of ∼2.7 log CFU/mL. Following the formation of ST biofilm on cantaloupe at 4 °C and 22 °C, the cantaloupe was treated with phage at an MOI of 100 for 2 h. The antibiofilm efficacy of phage was evaluated via the plate count method, confocal laser scanning microscopy, and scanning electron microscopy (SEM). The initial biofilm population at 22 °C was significantly greater and more condensed than that at 4 °C. After phage treatment, biofilm population and the percentage of viable ST in biofilm were reduced by ∼4.6 log CFU/cm2 and ∼90% within 2 h, respectively, which were significantly greater than those at 22 °C (∼2.0 log CFU/cm2 and ∼45%) (P < 0.05). SEM images also confirmed more drastic destruction of the cohesive biofilm architecture at 4 °C than at 22 °C. As a result of its cold temperature-robust lytic activity and the contribution of endolysin and two depolymerases, vB_SalA_KFSST3 demonstrated excellent antibiofilm efficacy at cold temperature, highlighting its potential as a promising practical biocontrol agent for the control of ST and its biofilm.

Cold housing environments: defining the problem for an appropriate policy response

Researchers across disciplines are increasing attention to cold housing environments. Public health, environmental and social sciences, architecture, and engineering each define and measure cold housing environments differently. Lack of standardisation hinders our ability to combine evidence, determine prevalence, understand who is most at risk--and to formulate policy responses. We conducted a systematic, cross-disciplinary review of literature to document the measures used. We examined benefits and limitations of each approach and propose a conceptualisation of cold housing: where temperature is too low to support optimal health and wellbeing of inhabitants, measured using one or a combination of economic, 'objective', or subjective approaches. More accurate data on home temperatures for all population groups, combined with an understanding of factors leading to cold homes, will enable appropriate policy response to reduce adverse health effects and costs. Policies targeting better building standards and energy subsidies both improve temperature conditions in housing environments.

Impact of seasonal variations on incidence and laterality of testicular torsion

Nowadays, there is confusing evidence in the literature regarding the association between seasonal variations and events of testicular torsion (TT). We attempted to assess the correlation between seasonal variations, including season, ambient temperatures, and humidity levels to onset and laterality of testicular torsion. We conducted a retrospective review of patients diagnosed with testicular torsion and confirmed surgically between January 2009 and December 2019, at Hillel Yaffe Medical Center. Weather data was collected from meteorological observation stations near the hospital. TT incidents were stratified into five temperature categories (< 15 °C, 15-20 °C, 20-25 °C, 25-30 °C, > 30 °C) and into two categories of humidity (≤ 50%, > 50%). Potential associations between TT and seasonal variations were investigated. Of 235 patients diagnosed with TT, 156 (66%) were children and adolescents and 79 (34%) were adults. In both groups, rate of TT incidents increased in winter and fall months. Significant correlation between TT and temperatures below 15 °C was observed in both groups; OR 3.3 [95% IC 1.54-7.07], p = 0.002 in children and adolescents and 3.77 [1.79-7.94], p < 0.001) in adults. The correlation between TT and humidity was non-significant in both groups. Among children and adolescents left-sided TT was observed in most of the cases, with strong correlation to lower temperatures; OR 3.15 [1.34-7.40], p = 0.008. Higher rates of acute TT were observed in patients admitted to the emergency department (ED) during the cold seasons in Israel. Significant association was observed between left-side TT and temperatures below 15 °C in the children and adolescents' group. Our findings suggest that there might be a predilection for TT occurrence in cold weather, particularly left-side laterality among children and adolescents.

Low ambient temperature and temperature drop as novel risk factors of acute glaucoma: a case-crossover study

The prevalence of glaucoma has seasonal variation in population, but the role of ambient temperature and its variation remains unclear in this seasonal trend. So, we conducted a time-stratified case-crossover study to examine the association of ambient temperature and temperature change between neighboring days (TCN) with the risk of acute glaucoma. Data on meteorological parameters and glaucoma outpatient visit between 2015 and 2021 covered all districts of Shanghai. Conditional logistic regression with distributed lag nonlinear model was applied to estimate the association of temperature or TCN with the risk of acute glaucoma. A total of 7,746 patients diagnosed with acute primary angle-closure glaucoma (APACG) were included in this analysis. We observed a significant increase in the risk of acute glaucoma with cold temperature and temperature drop. Compared with the referent temperature (32℃), moderate low (12 °C) and extreme low (4 °C) temperature exposures were associated with higher risk of acute glaucoma outpatient visit, with the highest cumulative OR of 1.46 (95% CI: 1.11, 1.91) and 1.50 (95% CI: 1.09, 2.06) over lag 0-2 days. Temperature drop (TCN =  - 4 °C) also increases the risk of acute glaucoma (OR = 1.34, 95% CI: 1.07, 1.67) over lag 0-7 days, comparing with no temperature change. Patients of female and above age 65 were more vulnerable to cold exposure and temperature drop. This case-crossover study provided novel and robust individual-level evidence that low ambient temperature and temperature drop significantly increase the acute glaucoma risk. The findings provide protective strategies for glaucoma patient, especially for female and the old, under cold exposure and sudden temperature decline.

Cold exposure induces browning of bovine subcutaneous white fat in vivo and in vitro

White adipocytes can be transformed into beige adipocytes through the process of browning under cold exposure. To investigate the effects and underlying mechanisms of cold exposure on subcutaneous white fat in cattle, in vitro and in vivo studies were performed. Eight bulls of Jinjiang cattle breed (Bos taurus) aged 18 months were allocated to the control group (n = 4, autumn) or the cold group (n = 4, winter) by different slaughter seasons. Biochemical and histomorphological parameters were detected in blood and backfat samples. Subcutaneous adipocytes from Simental cattle (Bos taurus) were then isolated and cultured at a normal body temperature (37 °C) and at a cold temperature (31 °C) in vitro. In the in vivo study, cold exposure stimulated subcutaneous white adipose tissue (sWAT) browning by reducing adipocyte sizes and up-regulating the expression levels of browning-specific makers (UCP1, PRDM16, and PGC-1α) in cattle. In addition, cold-exposed cattle displayed lower lipogenesis transcriptional regulator levels (PPARγ and CEBPα) and higher lipolysis regulator levels (HSL) in sWAT. In the in vitro study, cold temperature inhibited subcutaneous white adipocytes (sWA) adipogenic differentiation by reducing lipid contents and decreasing the expression of adipogenic marker genes and proteins. Furthermore, cold temperature led to sWA browning which was characterized by increased browning-related genes, mitochondrial contents, and mitochondrial biogenesis-specific markers. In addition, p38 MAPK signaling pathway activity was stimulated by the incubation in cold temperature for 6 h in sWA. We concluded that the cold-induced browning of the subcutaneous white fat was beneficial to the production of heat and the maintenance of body temperature regulation in cattle.

Study on spoilage potential and its molecular basis of Shewanella putrefaciens in response to cold conditions by Label-free quantitative proteomic analysis

To elucidate how Shewanella putrefaciens survives and produces spoilage products in response to cold conditions, the metabolic and protease activity of S. putrefaciens DSM6067 cultured at three different temperatures (30 °C, 10 °C, and 4 °C) was studied by determining the bacterial growth, total volatile basic nitrogen (TVB-N), biogenic amines, extracellular protease activity, as well as the differential expressed proteins via Label-free quantitative proteomics analysis. The lag phase of the strain cultured at 10 °C and 4 °C was about 20 h and 120 h longer than at 30 °C, respectively. The TVB-N increased to 89.23 mg N/100 g within 28 h at 30 °C, and it needed at least 72 h and 224 h at 10 °C and 4 °C, respectively. Cold temperatures (10 °C and 4 °C) also inhibited the yield factors and the extracellular protease activity per cell at the lag phase. However, the protease activity per cell and the yield factors of the sample cultivated at 10 °C and 4 °C well recovered, especially at the mid and latter stages of the log phase. The further quantitative proteomic analysis displayed a complex biological network to tackle cold stress: cold stress responses, nutrient uptake, and energy conservation strategy. It was observed that the protease and peptidase were upregulated, so as to the degradation pathways of serine, arginine, and aspartate, which might lead to the accumulation of spoilage products. This study highlighted the spoilage potential of S. putrefaciens still should be concerned even at low temperatures.

Cold air exposure at - 15 °C induces more airway symptoms and epithelial stress during heavy exercise than rest without aggravated airway constriction

Purpose

Exposure to cold air may harm the airways. It is unclear to what extent heavy exercise adds to the cold-induced effects on peripheral airways, airway epithelium, and systemic immunity among healthy individuals. We investigated acute effects of heavy exercise in sub-zero temperatures on the healthy airways.

Methods

Twenty-nine healthy individuals underwent whole body exposures to cold air in an environmental chamber at − 15 °C for 50 min on two occasions; a 35-min exercise protocol consisting of a 5-min warm-up followed by 2 × 15 min of running at 85% of VO₂max vs. 50 min at rest. Lung function was measured by impulse oscillometry (IOS) and spirometry before and immediately after exposures. CC16 in plasma and urine, and cytokines in plasma were measured before and 60 min after exposures. Symptoms were surveyed pre-, during and post-trials.

Results

FEV₁ decreased after rest (− 0.10 ± 0.03 L, p < 0.001) and after exercise (− 0.06 ± 0.02 L, p = 0.012), with no difference between trials. Exercise in − 15 °C induced greater increases in lung reactance (X5; p = 0.023), plasma CC16 (p < 0.001) as well as plasma IL-8 (p < 0.001), compared to rest. Exercise induced more intense symptoms from the lower airways, whereas rest gave rise to more general symptoms.

Conclusion

Heavy exercise during cold air exposure at − 15 °C induced signs of an airway constriction to a similar extent as rest in the same environment. However, biochemical signs of airway epithelial stress, cytokine responses, and symptoms from the lower airways were more pronounced after the exercise trial.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00421-022-05004-3.

Cold exposure, gut microbiota, and hypertension: A mechanistic study

Cold exposure has been recognized as an important risk factor for hypertension, and altered gut microbiota has been reported to be associated with hypertension. We hypothesized that there is a plausible relationship between gut microbiota and cold-induced hypertension (CIH). Therefore, we explored the potential link between the gut microbiota and its metabolites with CIH. Male Sprague-Dawley (SD) rats were randomly divided into the normal temperature group (NT, 20 ± 2 °C) and the cold exposure group (CE, 4 ± 1 °C), and faecal bacteria cross-transplantation was performed after six weeks. We analyzed the gut microbiota of rats using the 16S rDNA sequence and measured the blood pressure of rats and the content of short-chain fatty acids in rat faeces. After six weeks of cold exposure, the CIH rat model was successfully established. The cold exposure reduced the diversity of the gut microbiota, increased the abundance of potentially pathogenic and conditionally pathogenic bacteria (e.g., Quinella, Rothia, and Senegalimassilia genera), and reduced the abundance of beneficial bacteria (e.g., Lactobacillus genus) and butyric acid-producing bacteria (e.g., Lachnospiraceae UCG-008 and Ruminococcaceae UCG-013 genera). Faecal bacteria cross-transplantation altered gut microbiota composition and regulated blood pressure levels. The NT group rats transplanted with CIH rats' faecal bacteria were enriched with certain conditional pathogenic bacteria such as Prevotellaceae UCG-003 genus. The CIH rats transplanted with faecal bacteria from the NT group rats were enriched with beneficial bacteria such as Bacteroides genus. In addition, we found a significant reduction in butyric acid levels in CIH rats, which may be related to the increase in blood pressure. In conclusion, CIH is associated with altered gut microbiota and reduced butyric acid. Our findings provide novel insights for the prevention and treatment of CIH by modulating the gut microbiota through supplementation of beneficial bacteria/butyrate.

Seasonal residual activity in adult familial Mediterranean fever: a longitudinal observational study

Although it is assumed that cold exposure triggers inflammation in patients with familial Mediterranean fever (FMF), seasonal differences in FMF have not yet been investigated. This study aims to investigate the association of seasonal changes with the frequency of attacks, disease severity, and subclinical inflammation in FMF. This longitudinal study examined adult patients with FMF on an established treatment followed up for at least 1 year in Istanbul. Clinical characteristics, medications, intraseasonal attacks counts, arthralgia and arthritis, disease severity, and the subclinical inflammation parameters were recorded covering four seasons. Friedman's and Cochran's Q tests were used to analyze changes in the above-mentioned data over seasons. Additionally, all attacks experienced in each season were added, and interseasonal differences were compared with the Chi-square goodness-of-fit test. Data for 240 observations (60 patients) were analyzed. The mean age and disease duration were 39.78 (SD 11.91) and 10 (IQR 6-22.75) years, respectively. The comparison of medians for four seasons did not show any statistical differences in terms of attack frequency, disease severity parameters, markers of subclinical inflammation, and the presence of arthralgia and arthritis. The total number of intraseasonal attacks experienced by patients differed among the seasons (p = 0.023), with a higher count in winter. Adult individuals with established FMF are more likely to experience attacks in winter than summer, but this difference may not be seen in the general parameters of disease activity/severity. This result supports the notion that there is a pronounced residual activity in winter.

A breathing mask attenuates acute airway responses to exercise in sub-zero environment in healthy subjects

PURPOSE

Cold air exposure is associated with increased respiratory morbidity and mortality. Repeated inhalation of cold and dry air is considered the cause of the high prevalence of asthma among winter endurance athletes. This study assessed whether a heat- and moisture-exchanging breathing device (HME) attenuates airway responses to high-intensity exercise in sub-zero temperatures among healthy subjects.

METHODS

Using a randomized cross-over design, 23 healthy trained participants performed a 30-min warm-up followed by a 4-min maximal, self-paced running time trial in - 15 °C, with and without HME. Lung function was assessed pre- and immediately post-trials. Club cell protein (CC-16), 8-isoprostane, and cytokine concentrations were measured in plasma and urine pre- and 60 min post trials. Symptoms were assessed prior to, during, and immediately after each trial in the chamber.

RESULTS

HME use attenuated the decrease in forced expiratory volume in 1 s (FEV₁) post trials (∆FEV₁: mean (SD) HME - 0.5 (1.9) % vs. no-HME - 2.7 (2.7) %, p = 0.002). HME also substantially attenuated the median relative increase in plasma-CC16 concentrations (with HME + 27% (interquartile range 9-38) vs no-HME + 121% (55-162), p < 0.001) and reduced airway and general symptom intensity, compared to the trial without HME. No significant changes between trials were detected in urine CC16, 8-isoprostane, or cytokine concentrations.

CONCLUSION

The HME attenuated acute airway responses induced by moderate-to-maximal-intensity exercise in - 15 °C in healthy subjects. Further studies are needed to examine whether this HMEs could constitute primary prevention against asthma in winter endurance athletes.

Cold temperature and sudden temperature drop as novel risk factors of asthma exacerbation: a longitudinal study in 18 Chinese cities

BACKGROUND

Few studies have explored the role of ambient temperature in asthma exacerbation.

OBJECTIVE

We aimed to explore the association of temperature with diurnal peak expiratory flow (PEF) variation and asthma exacerbation.

METHOD

We developed a longitudinal study among asthmatic adults in 18 Chinese cities. Subjects recorded PEF in dynamic pulmonary function monitoring from 2017 to 2020. Linear mixed-effect model and generalized additive model with distributed non-linear models were used to assess the effect of temperature and temperature change between neighboring days (TCN) on diurnal PEF variation and the risk of asthma exacerbation.

RESULT

We evaluated a total of 79,217 daily PEF monitoring records from 4467 adult asthmatic patients. There were significant increase of diurnal PEF variation and higher risk of asthma exacerbation with cold and sudden temperature drop. Compared with the referent temperature (99th percentile, 32 °C), exposure to moderate cold (25th percentile, 3 °C) and extreme cold (2.5th percentile, -7 °C) was associated with elevations of 1.28% and 1.16% in diurnal PEF variation over lag 0-2 days, respectively. The odds ratios of asthma exacerbation (determined by diurnal PEF variation >20%) at the two temperature cutoffs were 1.68 and 1.73. A sudden temperature drop (2.5th percentile of TCN, -5 °C) was associated with 1.13% elevation in diurnal PEF variation, and with increased risk of asthma exacerbation (odd ratio = 1.50) over lag 0-4 days.

CONCLUSION

This large multicenter study provided the first-hand empirical evidence that cold temperature and a temperature drop may increase the risk of asthma exacerbation.

The Effects of Cool Dialysate on Vital Signs, Adequacy and Complications during Hemodialysis

BACKGROUND

Cooling the dialysate is an important factor that contributes to the hemodynamic stability in patients during hemodialysis. The aim of this study was to determine the effect of cool dialysate on vital signs, and the adequacy and common complications of hemodialysis.

MATERIALS AND METHODS

The present crossover, triple-blind, clinical trial was performed on 62 dialysis patients, who were selected through stratified block randomization. First, one group underwent hemodialysis using a cool dialysate (35°C), and the other received routine hemodialysis (36.5°C). Each patient received a total of eight hemodialysis sessions. Then, treatment methods were swapped, and each group received the other group's method. The patients' blood pressure, pulse rate, and temperature were measured before dialysis, and in the first, second, third, and fourth hours of dialysis. The frequency of common complications of hemodialysis and dialysis efficacy were measured. The marginal model and Generalized Estimating Equations (GEE) were used to analyze the data.

RESULTS

The participants' systolic (p = 0.01) and diastolic blood pressures significantly increased with a decrease in temperature (p = 0.005). The patients' pulse rate (p = 0.143), adequacy of dialysis (p = 0.922), and common complications of hemodialysis did not significantly differ between the two temperatures (p > 0.05).

CONCLUSIONS

Reducing dialysate temperature from 36.5 to 35°C led to hemodynamic stability; the blood pressure of the patients undergoing hemodialysis was more stable with the cool dialysate method and the number of drops in the blood pressure during the hemodialysis was reduced.

Effects of ambient temperature and cold starts on excess NOx emissions in a gasoline direct injection vehicle

Studies have demonstrated that vehicles with gasoline direct injection (GDI) engines produce significantly higher emissions during a cold start than under hot-stabilized periods. A cold start is typically defined by the temperature of the engine or the catalytic converter; its extended effect on emissions, after the vehicle reaches the warm-up stage, has seldom been investigated. In this study, the influence of the post cold start period on nitrogen oxides (NO_x) emissions was evaluated using real-world measurements. Vehicle on-board diagnostic data, fuel consumption, and emissions of multiple pollutants were collected on a 2020 GDI sports utility vehicle equipped with a Portable Emission Measurement System (PEMS). A total of 31 trips, with two drives per day, were conducted along arterial roads and highways in Toronto, Canada. The results indicate that during the first trip of the day after an overnight soak, the average NO_x emission rate was 0.27 g/litre and 0.037 g/km, 384% and 299% higher than the emission rate on the second trip of the day. The amount of trip total NO_x emissions is positively associated with the length of the catalytic converter warm-up period with correlation coefficient 0.67. We also observe that the catalyst warm-up time is negatively correlated with ambient temperature, and a negative relationship between ambient temperature and NO_x emissions throughout the trip is depicted with correlation coefficient -0.44. The measured data reveal an extended effect of the cold start on NO_x emissions even after the temperatures of the engine coolant and catalyst reach a stable level.

An experimental exposure study revealing composite airway effects of physical exercise in a subzero environment

Exposure to a cold climate is associated with an increased morbidity and mortality, but the specific mechanisms are largely unknown. People with cardiopulmonary disease and winter endurance athletes are particularly vulnerable. This study aimed to map multiple domains of airway responses to exercise in subzero temperature in healthy individuals.

Thirty-one healthy subjects underwent whole-body exposures for 50 minutes on two occasions in an environmental chamber with intermittent moderate-intensity exercise in +10 °C and -10 °C. Lung function, plasma/urine CC16 , and symptoms were investigated before and after exposures.

Compared to baseline, exercise in -10 °C decreased FEV₁ (p=0.002), FEV₁/FVC (p<0.001), and increased R20Hz (p=0.016), with no differences between exposures. Reactance increased after +10 °C (p=0.005), which differed (p=0.042) from a blunted response after exercise in -10 °C. Plasma CC16 increased significantly within exposures, without differences between exposures. Exercise in -10 °C elicited more intense symptoms from the upper airways, compared to +10 °C. Symptoms from the lower airways were few and mild. 

Short-duration moderate-intensity exercise in -10 °C induces mild symptoms from the lower airways, no lung function decrements or enhanced leakage of biomarkers of airway epithelial injury, and no peripheral bronchodilatation, compared to exercise in +10 °C. 

Targeted temperature management after cardiac arrest. A systematic review and meta-analysis of animal studies

AIM

Animal studies are an important knowledge base when information from clinical trials is missing or conflicting. The goal of this systematic review and meta-analysis was to investigate the effect of conventional targeted temperature management (TTM) between 32-36 °C in animal cardiac arrest models, and to estimate the influence of effect modifiers on the pooled effect of TTM.

DATA SOURCES

We searched Medline and Scopus from inception to May 2020 for randomised controlled animal trials assessing the effect of conventional TTM versus normothermia on neurologic outcome after cardiac arrest. We extracted data on study characteristics, study quality data, neurologic outcome, mortality, and potential effect modifiers.

RESULTS

We retrieved 1635 studies, 45 studies comprising data of 981 animals met the inclusion criteria. Risk of bias was high in 17 studies and moderate in 28 studies. We undertook random-effects meta-analyses and meta-regression analyses to calculate the pooled effect and the influence of effect modifiers. There was a strong beneficial effect of TTM as compared to normothermia on neurologic outcome (standardised mean difference of 1.4 [95% CI -1.7 to -1.1; I² = 75%]). Faster cooling rates, lower target temperature of TTM within the range of 32-36 °C, and shorter duration of cooling were independently associated with an increasing effect size of TTM.

CONCLUSIONS

This systematic review of animal cardiac arrest studies showed a consistent favourable effect of postresuscitation TTM as compared to normothermia on neurologic outcome that increased with lower target temperatures.

Influence of Thermal and Gustatory Stimulus in the Initiation of the Pharyngeal Swallow and Bolus Location Instroke

INTRODUCTION/OBJECTIVE

The aim of this study is to analyze the influence of sour taste and cold temperature in the initiation of the pharyngeal swallow (IPS) and bolus location at pharyngeal swallow onset in individuals after stroke.

METHODS

Cross-sectional prospective study. The study included 52 individuals with unilateral ischemic stroke. Each individual was assessed by videofluoroscopic swallowing study with 5ml of paste bolus offering four different stimuli (natural, cold, sour, and sour-cold). The individuals were divided into two groups according to the offer sequence. Group 1 (G1) - received a randomized sequence of stimuli (24 individuals), and Group 2 (G2) -the stimuli were offered in the following order: natural, cold, sour, and sour-cold(28 individuals). The IPS time and bolus location at pharyngeal swallow onset were analyzed. The bolus location at pharyngeal swallow onset was defined using six different levels.

RESULTS

Individuals in G1 did not show a significant difference in IPS time between stimuli. However, individuals in G2 presented a significantly shorter IPS time with the sour and sour-cold stimuli than with natural or cold stimuli. The bolus location at pharyngeal swallow onset did not show significant difference between stimuli in both groups. On the other hand, in the G2 it was observed higher frequency of swallowing with sour-cold stimulus at level 1 (the bolus head was located in any region between the fauces pillar and the point where the tongue crosses the inferior border of the mandible).

CONCLUSION

The sour and sour-cold stimuli influenced the IPS time when they were offered in a sequential order. Moreover, both the IPS time and bolus location at pharyngeal swallow onset were not influenced by the sour and sour cold-bolus when offered in a random sequence.

Relative performance of commercial citric acid and quaternary ammonium sanitizers against Listeria monocytogenes under conditions relevant to food industry

Growth of Listeria monocytogenes in cold temperatures coupled with its tolerance of antimicrobials can promote its survival and persistence in food processing environments. The food industry relies heavily on cleaning and sanitation to control L. monocytogenes; therefore, it is important to understand the environmental context (i.e., temperature) on the efficacy of antimicrobials used in food industry. The minimum bactericidal concentrations (MBCs) of an "eco-friendly" citric acid-based (CAB) sanitizer and a conventional quaternary ammonium compound (CQAC) sanitizer were determined against 14 L. monocytogenes isolates at 4-30 °C. A subset of isolates (n = 3) was also exposed to sub-lethal concentrations of sanitizers to assess differences in growth behavior. CAB and CQAC were effective at manufacturer recommended concentrations in liquid assays. The MBC of CAB was significantly lower at 4 °C compared to 23 °C (p < 0.05), whereas the MBC of CQAC was unchanged between 4 °C and 23 °C. Manufacturers' recommendations for dose and duration of CAB and CQAC were unable to consistently achieve a >5-log reduction of L. monocytogenes attached to surfaces. Findings from this study demonstrate the importance of sanitizer evaluation under conditions representative of their use in the food industry.

Monitoring Euro 6 diesel passenger cars NOx emissions for one year in various ambient conditions with PEMS and NOx sensors

In this study, the NO_x emissions of four Euro 6 diesel passenger cars ranging from Euro 6 b to Euro 6 d-TEMP in different ambient conditions and driving routes were investigated with a Portable Emissions Measurement System (PEMS) and continuous NO_x concentration monitoring device. A model was also generated for translating NO_x concentration values into a gram basis. The results suggest that there is a marked difference in NO_x emissions based on the Euro 6 step for the car is type approved. The study showed that the conformity factor for NO_x emissions on a route in a city environment ("City route") changed from 0.65 to 5.2 depending on the Euro 6 step and car. Surprisingly, a Euro 6 b car equipped with Selective Catalytic Reduction SCR system and updated engine control unit (ECU) software for lower tailpipe NO_x emissions provided lower average NO_x emissions than a Euro 6 d-TEMP diesel car equipped with dual lean-NO_x traps. Results for the City route also showed that the road infrastructure (crossroads and speed limitations) can have a noticeable effect on promoting driving that leads to higher NO_x emissions even with a Euro 6 d-TEMP car. Estimations of NO_x emissions with modelling based on continuous NO_x concentration monitoring suggested that Euro 6 b diesel cars can provide NO_x emissions close to the current RDE legislation. In addition, the modelling suggested that the Euro 6 b car with updated ECU software and the Euro 6 d-TEMP diesel car are capable of extremely low daily average NO_x emissions, even close to 20 mg/km, in normal daily usage. Nevertheless, the monitoring results and model also suggest that cold ambient temperature has a high effect on the NO_x emissions reduction performance of these vehicles, occasionally increasing their daily average emissions to as high as 900 mg/km.

Is working in a cold environment associated with musculoskeletal complaints 7-8 years later? A longitudinal analysis from the Tromsø Study

Objective

Exposure to a cold environment at work is associated with a higher prevalence of musculoskeletal pain and chronic pain in cross-sectional studies. This study aims to determine the association between working in a cold environment ≥ 25% of the time and musculoskeletal complaints (MSC) 7–8 years later.

Methods

We followed participants from the sixth survey (Tromsø 6, 2007–2008) to the seventh survey (Tromsø 7, 2015–2016) of the Tromsø Study. Analyses included 2347 men and women aged 32–60 years who were not retired and not receiving full-time disability benefits in Tromsø 6. Three different binary outcomes were investigated in Tromsø 7: any MSC, severe MSC, and MSC in ≥ 3 anatomical regions. We excluded participants with severe MSC, MSC in ≥ 3 regions, or missing values in Tromsø 6. The association between working in a cold environment and future MSC were examined using Poisson regression and adjusted for age, sex, number of moderate MSC, education, physical activity at work, smoking status, body mass index, and self-reported health in Tromsø 6.

Results

258 participants reported to work in a cold environment ≥ 25% of the time in Tromsø 6. They had an increased risk of having any MSC in Tromsø 7 (incidence rate ratio 1.15; 95% confidence interval 1.03–1.29). There was no significantly increased risk of severe MSC or MSC in ≥ 3 regions.

Conclusion

Working in a cold environment was associated with future MSC, but not with future severe MSC or future MSC in ≥ 3 regions.

Electronic supplementary material

The online version of this article (10.1007/s00420-020-01606-6) contains supplementary material, which is available to authorized users.

Comparison of Energy and Nutrient Intake vs. Estimated Needs in Warfighters: an Update

Active members of the military must perform optimally under conditions of thermal stress and/or energy deficiency. Military dietary reference intakes (MDRIs) provide guidelines for energy and nutrient intakes but is based studies largely conducted in Army. Needs may vary by service branch and/or position. New protein recommendations have emerged, which are not reflected in MDRIs. PURPOSE OF REVIEW: Compare reported dietary intake in active duty members to MDRIs and 2016 American College of Sports Medicine (ACSM) sports nutrition guidelines. RECENT FINDINGS: Active duty members are not meeting their energy and carbohydrate needs with low-to-adequate protein intake and adequate-to-high fat intake. Other nutrients of concern are vitamin D, calcium, iron, B-vitamins, and fiber. Thermal stress increases energy needs and suppresses appetite and thus increase risk for energy and nutrition deficiencies. Energy and nutrients needs can vary by branch of armed service, job responsibility, and external stressors.

Evaluation of the effect of Cooled HaEmodialysis on Cognitive function in patients suffering with end-stage KidnEy Disease (E-CHECKED): feasibility randomised control trial protocol

BACKGROUND

Cognitive impairment is common in haemodialysis (HD) patients and is associated independently with depression and mortality. This association is poorly understood, and no intervention is proven to slow cognitive decline. There is evidence that cooler dialysis fluid (dialysate) may slow white matter changes in the brain, but no study has investigated the effect of cooler dialysate on cognition. This study addresses whether cooler dialysate can prevent the decline in cognition and improve quality of life (QOL) in HD patients.

METHODS

This is a multi-site prospective randomised, double-blinded feasibility trial.

SETTING

Four HD units in the UK.

PARTICIPANTS AND INTERVENTIONS

Ninety HD patients randomised (1:1) to standard care (dialysate temperature 36.5 °C) or intervention (dialysate temperature 35 °C) for 12 months.

PRIMARY OUTCOME MEASURE

Change in cognition using the Montreal Cognitive Assessment (MoCA).

SECONDARY OUTCOME MEASURES

Recruitment and attrition rates, reasons for non-recruitment, frequency of intradialytic hypotension, depressive symptom scores, patient and carers burden, a detailed computerised cognitive test and QOL assessments.

ANALYSIS

mixed method approach, utilising measurement of cognition, questionnaires, physiological measurements and semi-structured interviews.

DISCUSSION

The results of this feasibility trial will inform the design of a future adequately powered substantive trial investigating the effect of dialysate cooling on prevention and/or slowing in cognitive decline in patients undergoing haemodialysis using a computerised battery of neuro-cognitive tests. The main hypothesis that would be tested in this future trial is that patients treated with regular conventional haemodialysis will have a lesser decline in cognitive function and a better quality of life over 1 year by using cooler dialysis fluid at 35 °C, versus a standard dialysis fluid temperature of 36.5 °C. This also should reflect in improvements in their abilities for activities of daily living and therefore reduce carers' burden. If successful, the treatment could be universally applied at no extra cost.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03645733 . Registered retrospectively on 24 August 2018.

Years of life lost with premature death due to ambient temperatures in a southwest plateau region of China: a cause-specific and individual characteristics stratified mortality study

We aimed to explore whether there were cold and heat temperature adverse effects on years of life lost (YLL) for non-accidental mortality in Yuxi, a southwest plateau region of China. From data for 89,467 non-accidental deaths over an 8-year study period, we used a general linear regression model combined with a distributed lag non-linear model to assess the burden of disease non-accidental mortality due to ambient temperature with the YLL indicator. We estimated the mean YLL change per 1 °C decrease from the 25th to 1st percentile mean temperature as the cold effect and per 1 °C increase from the 75th to 99th percentile as the heat effect. The 95% empirical confidence intervals (eCIs) were calculated by using a bootstrap simulation method. The exposure-response curve between average temperature and YLL was U-shaped. The cold effect peaked at the first day after exposure and disappeared at 2 weeks, and the heat effect only lasted for the first 3 days. A per 1 °C decrease from the 25th to 1st mean temperature percentile was associated with an increase of 15.6 (95% eCI: 2.4, 22.9) in YLL for non-accidental diseases, and the cumulative effects due to cold were stronger in contrast to that attributed by heat. Cold temperature had a significant impact on YLL among the subgroups, with higher YLL in cardiovascular disease, stroke, males, Han nationality, married, and those engaged in agriculture than their corresponding categories. An increasing death burden of non-accidental in Yuxi of China due to cold temperature was demonstrated, and the association was also modified by specific disease causes and individual features.

Comparison of Using Cold Versus Regular Temperature Tube on Successful Nasogastric Intubation for Patients in Toxicology Emergency Department: a Randomized Clinical Trial

Introduction: In view of the contradictory results for the use of cold tubes for the purpose of enhancing nasogastric tube insertion success there is a pressing need for further research in this area. This study aimed to determine the effect of using cold versus regular temperature nasogastric tube on successful nasogastric tube insertion for patients referring to toxicology emergency department.

Methods: This study is a clinical trial with two groups design of 65 patients admitted to toxicology emergency department who were divided into two groups by random allocation. Nasogastric tubes used in the intervention group had been stored in a refrigerator at 2°-8° C while the ones employed in the control group had been maintained at the room temperature of 22-28° C. Nasogastric tube insertions in both groups were done by the investigator according to standard methods. The data were analyzed using SPSS ver. 13.

Results: The placement of nasogastric tube was done in the first attempt with 27 (%84.4) of the subjects in the control group and 33 (%100.0) in the intervention group. The chi-square test results showed that the frequency of the number of attempts for gastric intubation in subjects between the two groups was statistically significant.

Conclusion: Cooling gastric tubes reduces the time required for nasogastric intubation. Thus, it is suggested that the gastric tubes be cooled before the application of the procedure so as to reduce complications, increase patient comfort and save nurses time.

Qualitative identification and characterisation of self-reported symptoms arising in humans during experimental exposure to cold air

Background: Exposure to cold air is associated with increased morbidity and mortality in the general population. It is difficult to study the effects of whole-body exposure to cold air under controlled conditions in real life. Objectives: The aim of this study was to (1) explore and describe the experience of symptoms in humans during experimental and controlled exposures to cold air, by using controlled environmental chamber exposures and qualitative methodology, and to (2) categorise the symptoms. Method: The study used a randomised, double blind design, in which 34 subjects undertook rest and moderate-intensity exercise in an environmental chamber set to two or three different temperatures (0, −10, and −17°C) on separate occasions. During the chamber exposures, subjects were interviewed. Qualitative content analysis was selected as the method of analysis. Findings: Subjects reported 50 distinct symptoms during the exposures. The symptoms were grouped into ten sub-categories and two major categories; airway versus whole-body symptoms. Conclusion: We have identified a broad range of symptoms in humans undertaking rest and moderate-intensity exercise at sub-zero temperatures. The symptoms and their categories may well be used to more extensively and quantitatively map cold-induced morbidity.

Study on the effect of a cold environment on the quality of three video laryngoscopes: McGrath MAC, GlideScope Ranger, and Pentax Airway Scope

Objective

Several environmental factors influence the prehospital use of video laryngoscopes (VLs). For example, fogging of the VL lens can occur in cold environments, and the low temperature can cause the VLs to malfunction. As relevant research on the effect of environment on VLs is lacking, we aimed to study the effect of a cold environment on three commonly used VLs.

Methods

McGrath MAC, Pentax Airway Scope (AWS), and GlideScope Ranger were exposed to temperatures of -5°C, -10°C, -20°C, and -25°C for 1 hour each and then applied to a manikin in a thermohydrostat room 5 times. Immediately after turning on the power and inserting the blade, the time until an appropriate glottic image appeared on the screen was measured.

Results

McGrath MAC was able to accomplish immediate intubation regardless of the temperature drop. However, GlideScope Ranger required an average of 4.9 seconds (-5°C to -20°C) and 10.1 seconds (-25°C) until appropriate images were obtained for intubation. AWS showed adequate image acquisition immediately after blade insertion despite slight fogging at -20°C, but at -25°C, images suitable for intubation did not appear on the screen for an average of 4.7 minutes.

Conclusion

All three devices appear to be usable without any limitations up to -20°C. However, GlideScope Ranger and AWS may not produce images immediately at temperatures below -25°C. Thus, medical practitioners performing VL in a cold environment should be aware of the characteristics of the VL devices in advance.

The Effects of Noise on Human Cognitive Performance and Thermal Perception under Different Air Temperatures

BACKGROUND

Environmental factors are interrelated, and human comfort is a complex state that is under the influence of all these factors perceived by a person. We aimed to investigate the effects of noise on human cognitive performance and thermal perception under different air temperatures.

STUDY DESIGN

An experimental study.

METHODS

This study was conducted on 24 volunteers (12 males and 12 females) aged 18-30 yr old. All the experiments were carried out in a climate chamber located in Hamadan University of Medical Sciences in 2018. The subjects were exposed to ten different conditions set by a combination of three different air temperatures (14, 18, and 22 °C), three different noise levels (55, 65 and 75 dBA), and one irrelevant speech level in the climate chamber. The n-back, CPT, and PVT tests were employed to evaluate different aspects of cognitive performance. Thermal comfort and thermal sensation were measured with subjective questionnaires.

RESULTS

With increasing noise under different air temperatures, working memory (P=0.001), sustained attention (P=0.001), and simple reaction time (P=0.001) were significantly disturbed. The combined effects of noise and low air temperature on working memory, sustained attention, and reaction time were higher than the effect of each of them individually. As compared with air temperature, noise has a larger effect on working memory, sustained attention, and reaction time in the test configurations.

CONCLUSION

The cognitive performance effects from noise has one veto power over these effects from low air temperature. Speech sound had more negative effects on subjects' cognitive functions than the typical noise caused by office equipment. The subjective thermal perceptions were also influenced by noise at lower air temperatures.

Cold-induced ginsenosides accumulation is associated with the alteration in DNA methylation and relative gene expression in perennial American ginseng (Panax quinquefolius L.) along with its plant growth and development process

Background

Ginsenosides accumulation responses to temperature are critical to quality formation in cold-dependent American ginseng. However, the studies on cold requirement mechanism relevant to ginsenosides have been limited in this species.

Methods

Two experiments were carried out: one was a multivariate linear regression analysis between the ginsenosides accumulation and the environmental conditions of American ginseng from different sites of China and the other was a synchronous determination of ginsenosides accumulation, overall DNA methylation, and relative gene expression in different tissues during different developmental stages of American ginseng after experiencing different cold exposure duration treatments.

Results

Results showed that the variation of the contents as well as the yields of total and individual ginsenosides Rg1, Re, and Rb1 in the roots were closely associated with environmental temperature conditions which implied that the cold environment plays a decisive role in the ginsenoside accumulation of American ginseng. Further results showed that there is a cyclically reversible dynamism between methylation and demethylation of DNA in the perennial American ginseng in response to temperature seasonality. And sufficient cold exposure duration in winter caused sufficient DNA demethylation in tender leaves in early spring and then accompanied the high expression of flowering gene PqFT in flowering stages and ginsenosides biosynthesis gene PqDDS in green berry stages successively, and finally, maximum ginsenosides accumulation occurred in the roots of American ginseng.

Conclusion

We, therefore, hypothesized that cold-induced DNA methylation changes might regulate relative gene expression involving both plant development and plant secondary metabolites in such cold-dependent perennial plant species.

Effects of cold temperature and snowfall on stroke mortality: A case-crossover analysis

BACKGROUND

We sought to determine if cold temperature and snowfall are independently associated with stroke mortality, and whether effects differ between hemorrhagic and ischemic stroke.

MATERIALS AND METHODS

We conducted a case-crossover study of 13,201 stroke deaths utilizing weather records between the months of November and April for Quebec, Canada from 1981 to 2015. We compared exposure to cold temperature and snowfall with controls days when stroke death did not occur. We computed odds ratios (OR) and 95% confidence intervals (CI) for the association of minimum temperature and duration of snowfall with stroke, adjusted for change in barometric pressure and relative humidity.

RESULTS

The likelihood of mortality the day following exposure to cold temperature was elevated for hemorrhagic stroke in men, independent of snowfall. Relative to 0 °C, a temperature of -20 °C was associated with 1.17 times the odds of hemorrhagic stroke death (95% CI 1.04-1.32). An independent effect of snowfall was also present in men, with 12 h of snowfall associated with 1.12 times the odds of hemorrhagic stroke death (95% CI 1.00-1.24) compared with no snowfall. There was no evidence of an increased risk in women. Cold temperature and snowfall were not associated with ischemic stroke death in either men or women.

CONCLUSION

Our results suggest that cold temperature and snowfall are independent risk factors for death from hemorrhagic stroke in men. These findings imply that interventions to prevent fatal hemorrhagic stroke during winter should include both cold temperature exposure and snowfall in men.

Good safety practice in a randomized controlled trial (CadColdEx) involving increased cardiac workload in patients with coronary artery disease

Background

Methodological information acknowledging safety of cardiac patients in controlled medical experiments are lacking. The descriptive report presents one good practice for considering safety in a randomized controlled study involving augmented cardiovascular strain among persons with coronary artery disease (CAD).

Methods

The patients were pre-selected by a cardiologist according to strictly defined selection criteria. Further confirmation of eligibility included screening of health. In addition, assessments of physical capacity by a graded bicycle ergometer test were implemented and safety monitored by an exercise physiologist and medical doctor. In this context, an emergency simulation was also carried out. A total of 18 CAD patients each underwent four different experimental interventions where either temperature (+ 22 °C and − 15 °C) and the level of exercise (rest and brisk walking) were employed for 30 min in random order (72 experiments). Baseline (20 min) and follow-up (60 min) measurements were conducted resting at + 22 °C. ECG, and brachial blood pressure were measured and perceived exertion and symptoms of chest pain inquired throughout the experiments. An emergency nurse was responsible for the health monitoring and at least two persons followed the patient throughout the experiment. A medical doctor was available on call for consultation. The termination criteria followed the generally accepted international guidelines for exercise testing and were planned prior to the experiments.

Results

The exercise test simulation revealed risks requiring changes in the study design and emergency response. The cardiovascular responses of the controlled trials were related to irregular HR, ST-depression or post-exercise hypotension. These were expected and the majority could be dealt on site by the research personnel and on call consultation. Only one patient was encouraged to seek for external health care consultation.

Conclusions

Appropriate prospective design is a key to safe implementation of controlled studies involving cardiac patients and stimulation of cardiovascular function. This includes careful selection of participants, sufficient and knowledgeable staff, as well as identifying possible emergency situations and the required responses.

Trial registration

ClinicalTrials ID: NCT02855905.

Efficacy and safety of Ojeok-san in Korean female patients with cold hypersensitivity in the hands and feet: study protocol for a randomized, double-blinded, placebo-controlled, multicenter pilot study

BACKGROUND

This study aims to evaluate the safety, efficacy, and feasibility of a full randomized clinical trial of Ojeok-san in Korean female patients with cold hypersensitivity in the hands and feet.

METHODS

This study is a multicenter, double-blinded, randomized, placebo-controlled, two-arm, parallel-group pilot clinical trial. A total of 60 participants will be enrolled and randomly assigned to the Ojeok-san treatment group or the placebo control group, in a 1:1 ratio using an Internet-based randomization system. Each group will be administered Ojeok-san or placebo three times per day for 8 weeks. The primary outcome will be the mean change in the Visual Analog Scale scores of cold hypersensitivity in the hands from baseline to week 8. Secondary outcomes will include the mean changes in the skin temperature of the extremities, recovery rate of the skin temperature of hands after cold stress test, and the score of Korean version of the WHO Quality of Life Scale abbreviated version.

DISCUSSION

The findings of this study should provide meaningful information for a further large-scale, randomized controlled trial to confirm the safety and efficacy of Ojeok-san on cold hypersensitivity in the hands and feet in female patients.

TRIAL REGISTRATION

ClinicalTrials.gov, ID: NCT03083522 . Registered on 20 March 2017.

Sex difference in cold perception and shivering onset upon gradual cold exposure

To maintain a thermal balance when experiencing cold, humans reduce heat loss and enhance heat production. A potent and rapid mechanism for heat generation is shivering. Research has shown that women prefer a warmer environment and feel less comfortable than men in the same thermal condition. Using the Blanketrol^® III, a temperature management device commonly used to study brown adipose tissue activity, we tested whether the experimental temperature (T_E) at which men and women start to shiver differs. Twenty male and 23 female volunteers underwent a cooling protocol, starting at 24 °C and gradually decreasing by 1-2 °C every 5 min until an electromyogram detected the shivering or the temperature reached 9 °C. Women started shivering at a higher T_E than men (11.3 ± 1.8 °C for women vs 9.6 ± 1.8 °C for men, P = 0.003). In addition, women felt cool, scored by a visual analogue scale, at a higher T_E than men (18.3 ± 3.0 °C for women vs 14.6 ± 2.6 °C for men, P < 0.001). This study demonstrates a sex difference in response to cold exposure: women require shivering as a source of heat production earlier than men. This difference could be important and sex should be considered when using cooling protocols in physiological studies.

Transcriptional response to low temperature in the yellow drum (Nibea albiflora) and identification of genes related to cold stress

The yellow drum (Nibea albiflora) is an economically important maricultured fish in China, but the aquaculture of this species is severely affected by overwinter mortality associated with cold stress. Characterization of the molecular mechanisms underlying the susceptibility of the yellow drum to cold might increase our understanding of how this fish adapts to environmental challenges. Here, the transcriptional response of the yellow drum to cold stress (7.5 °C) was investigated with RNA-Seq analysis. We compared brain and muscle transcriptomes among cold-tolerant (Tol) fish that survived the cold treatment, cold-sensitive (Sen) fish that were killed by the cold treatment, and control (Con) fish that were not subjected to cold. Our analysis recovered 233,245 unigenes. The genes (DEGs) differentially expressed in the brain and muscle of the Tol versus Con group, the Sen versus Con group, and the Tol versus Sen group had tissue-specific expression patterns. Gene ontology, enrichment, and pathway analyses indicated the most highly enriched pathways in the DEGs were signaling molecules and interaction, signal transduction, carbohydrate metabolism, lipid metabolism, digestive system, and endocrine system pathways. These pathways were all associated with biological functions relevant to cold adaptation in the yellow drum, including transduction of stress signals, energy metabolism, and stress-induced cell membrane changes. We identified genes likely to be involved in cold-susceptibility and -tolerance as those differentially expressed in the Tol group as compared to the Sen group. Further investigation and characterization of these candidate genes might improve our understanding of the mechanisms underlying cold adaptation in the yellow drum.

Effects of prolonged running in the heat and cool environments on selected physiological parameters and salivary lysozyme responses

Introduction

Lysozyme is one of the salivary antimicrobial proteins which act as the “first line of defence” at the mucosal surface. The effects of prolonged exercise in the hot and cool environments among recreational athletes on salivary lysozyme responses are very limited in the literature, especially in the Asian countries.

Objective

To determine the effects of prolonged running in the hot and cool environments on selected physiological parameters and salivary lysozyme responses among recreational athletes.

Methods

Randomised and cross-over study design. Thirteen male recreational athletes (age: 20.9 ± 1.3 years old) from Universiti Sains Malaysia participated in this study. They performed two separate running trials; 90 min running at 60% of their respective maximum oxygen uptake (V˙O2max) One running trial was performed in the hot (31ºC) while the other was in the cool (18ºC) environment and this sequence was randomised. Each running trial was started with a 5 min warm-up at 50% of participant's respective V˙O2max Recovery period between these two trials was one week. In the both trials, saliva samples, blood samples, heart rate, ratings of perceived exertion, skin and tympanic temperatures, oxygen consumption, nude body weight, room temperature, and relative humidity were collected.

Results

Participants' skin temperature, tympanic temperature, body weight changes, heart rate, ratings of perceived exertion, and plasma volume changes were significantly higher (p < 0.05) in the hot trial compared to the cool trial. Saliva flow rate was not significantly (p = 0.949) different between the hot (0.32 ± 0.08 ml/min) and cool (0.27 ± 0.05 ml/min) trials. However, in each trial, it significantly decreased (p < 0.05) at post-exercise as compared to pre-exercise but it returned to baseline value at 1 h post-exercise. In addition, there were no significant differences between and within hot and cool trials in salivary lysozyme concentration (p = 0.925; 4.79 ± 1.37 and 4.44 ± 1.11 μg/ml respectively) and secretion rate (p = 0.843; 1.67 ± 1.1 and 1.17 ± 1.0 μg/min respectively).

Conclusion

This study found similar lysozyme responses between both hot and cool trials. Thus, room/ambient temperature did not affect lysozyme responses among recreational athletes. Nevertheless, the selected physiological parameters were significantly affected by room temperature.

Risk of hospitalization for fire-related burns during extreme cold weather

BACKGROUND

Environmental factors are important predictors of fires, but no study has examined the association between outdoor temperature and fire-related burn injuries. We sought to investigate the relationship between extremely cold outdoor temperatures and the risk of hospitalization for fire-related burns.

MATERIAL AND METHODS

We carried out a time-stratified case-crossover study of 2470 patients hospitalized for fire-related burn injuries during cold months between 1989 and 2014 in Quebec, Canada. The main exposure was the minimum outdoor temperature on the day of and the day before the burn. We computed odds ratios (OR) and 95% confidence intervals (CI) to evaluate the relationship between minimum temperature and fire-related burns, and assessed how associations varied across sex and age.

RESULTS

Exposure to extreme cold temperature was associated with a significantly higher risk of hospitalization for fire-related burns. Compared with 0°C, exposure to a minimum temperature of -30°C was associated with an OR of 1.51 (95% CI 1.22-1.87) for hospitalization for fire-related burns. The associations were somewhat stronger for women, youth, and the elderly. Compared with 0°C, a minimum temperature of -30°C was associated with an OR for fire-related burn hospitalization of 1.65 for women (95% CI 1.13-2.40), 1.60 for age < 25 years (95% CI 1.02-2.52), and 1.73 for age ≥ 65 years (95% CI 1.08-2.77).

DISCUSSION

Extremely cold outdoor temperature is a risk factor for fire-related burns. Measures to prevent fires should be implemented prior to the winter season, and enhanced during extreme cold.

Color stability of dental restorative materials submitted to cold temperatures for forensic purposes

In the post-mortem examination of the dental arches of accident victims in cold locations, dental restorative materials can be found. Cold temperatures can be capable of causing color changes of aesthetic materials, such as composite resin (CR) and glass ionomer cement (GIC). The aim of this study was to evaluate the effect of the cold action on the color stability of CR and GIC restorations, in order to discriminate them and enable the adequate comparison between antemortem and post-mortem data. Sixty bovine teeth (30 CR and 30 GIC) were prepared (6 × 6 × 2 mm) and separated into groups (n = 10). The color readouts were taken by a portable spectrophotometer, before and after of cold action (2.5 °C, -20 °C, -80 °C) inside of freezers. There were color alterations in the coordinates (ΔE, ΔL^∗, Δa^∗ e Δb^∗) for both materials. The authors concluded that cold was capable of producing changes in color in the two esthetic materials, with similar intensities between the two, at all the temperatures studied, when analyzed at 7 days. After being submitted to cold for 30 days, the changes were more significant for CR, allowing it to be differentiated from GIC after 30 days, at all the temperatures tested. Therefore, the test proposed in the study was shown to be practical, feasible and capable of helping Forensic Odontology with the identification of victims.

Diabetes and impaired glucose metabolism is associated with more cold-related cardiorespiratory symptoms

AIMS

Diabetes and impaired glucose metabolism cause metabolic, neural and circulatory disturbances that may predispose to adverse cooling and related symptoms during the cold season. This study assessed the prevalence of cold-related cardiorespiratory symptoms in the general population according to glycaemic status.

METHODS

The study population consisted of 2436 men and 2708 women aged 45-74years who participated in the National FINRISK cold sub-studies in 2002 and 2007. A questionnaire assessed cold-related symptoms (respiratory, cardiac, peripheral circulation). Glycaemic status was determined based on fasting blood glucose, oral glucose tolerance tests or reported diagnosis of diabetes and categorized into normal glucose metabolism, impaired fasting blood glucose, impaired glucose tolerance, screening-detected type 2 diabetes and type 2 diabetes.

RESULTS

Type 2 diabetes was associated with increased odds for cold-related dyspnoea [Adjusted OR 1.72 (95% CI, 1.28-2.30)], chest pain [2.10 (1.32-3.34)] and respiratory symptoms [1.85 (1.44-2.38)] compared with normal glucose metabolism. Screened type 2 diabetes showed increased OR for cold-related dyspnoea [1.36 (1.04-1.77)], cough [1.41 (1.06-1.87)] and cardiac symptoms [1.51 (1.04-2.20)]. Worsening of glycaemic status was associated with increased odds for cold-related dyspnoea (from 1.16 in impaired fasting glucose to 1.72 in type 2 diabetes, P=0.000), cough (1.02-1.27, P=0.032), chest pain (1.28-2.10, P=0.006), arrhythmias (0.87-1.74, P=0.020), cardiac (1.11-1.99, P=0.000), respiratory (1.14-1.84, P=0.000) and all symptoms (1.05-1.66, P=0.003).

CONCLUSIONS

Subjects with diabetes and pre-diabetes experience more cold-related cardiorespiratory symptoms and need instructions for proper protection from cold weather to reduce adverse health effects.

The efficacy and safety of Danggui-Sayuk-Ga-Osuyu-Saenggang-tang on Korean patients with cold hypersensitivity in the hands: study protocol for a pilot, double-blind, randomized, placebo-controlled, parallel-group clinical trial

Background

In recent years, cold hypersensitivity in the hands (CHH) has become a common ailment of women in Korea. It can lead to gynecological problems such as irregular menstruation, miscarriage, and infertility. Traditionally, Korean herbal medicine has been the primary treatment method used to balance thermoregulation in the human body; however, its effectiveness has not been confirmed through systematic study. Thus, in this trial, we will investigate the feasibility of a full randomized clinical trial, Danggui-Sayuk-Ga-Osuyu-Saenggang-tang (DSGOST) in Korean women with CHH.

Methods

This study will be a pilot, multicenter, double-blind, randomized, parallel-group, two-arm, placebo-controlled clinical trial. A total of 66 participants will be randomly divided into two groups, a DSGOST treatment group and a placebo control group, in a 1:1 ratio using a web-based randomization system. Each group will take DSGOST or placebo three times daily for 6 weeks. The primary outcome will be measured using Visual Analogue Scale (VAS) scores of CHH. Secondary outcomes will include changes in skin temperature of the hands, Clinical Global Impressions (CGI) scale scores, recovery rate of skin temperature of the hands after the cold stress test, and the Korean version of the WHO Quality of Life Scale, abbreviated version (WHOQOL-BREF).

Discussion

This trial will be the first trial to reflect the newly defined disease range of CHH which was compiled by Korean medicine expert consensus. This study will provide considerable evidence for further large-scale trials and general clinical guidelines for CHH in the Korean medical field.

Trial registration

This study is registered at ClinicalTrials.gov, ID: NCT02645916. Registered on 30 December 2015.

Electronic supplementary material

The online version of this article (doi:10.1186/s13063-017-2002-8) contains supplementary material, which is available to authorized users.

Thermal perception thresholds among workers in a cold climate

Purpose

To investigate whether exposure to cold could influence the thermal perception thresholds in a working population.

Methods

This cross-sectional study was comprised of 251 males and females and was carried out at two mines in the northern part of Norway and Sweden. The testing included a baseline questionnaire, a clinical examination and measurements of thermal perception thresholds, on both hands, the index (Digit 2) and little (Digit 5) fingers, for heat and cold.

Results

The thermal perception thresholds were affected by age, gender and test site. The thresholds were impaired by experiences of frostbite in the fingers and the use of medication that potentially could affect neurosensory functions. No differences were found between the calculated normative values for these workers and those in other comparative investigations conducted in warmer climates.

Conclusions

The study provided no support for the hypothesis that living and working in cold climate will lead to impaired thermal perception thresholds. Exposure to cold that had caused localized damage in the form of frostbite was shown to lead to impaired thermal perception.

Association of cold temperature and mortality and effect modification in the subtropical plateau monsoon climate of Yuxi, China

BACKGROUND

Consistent evidence has shown excess mortality associated with cold temperature, but some important details of the cold-mortality association (e.g. slope and threshold) have not been adequately investigated and few studies focused on the cold effect in high-altitude areas of developing countries. We attempted to quantify the cold effect on mortality, identify the details, and evaluate effect modification in the distinct subtropical plateau monsoon climate of Yuxi, a high plateau region in southwest China.

METHODS

From daily mortality and meteorological data during 2009-2014, we used a quasi-Poisson model combined with a "natural cubic spline-natural cubic spline" distributed lag non-linear model to estimate the temperature-mortality relationship and then a simpler "hockey-stick" model to investigate the cold effect and details.

RESULTS

Cold temperature was associated with increased mortality, and the relative risk of cold effect (1st relative to 10th temperature percentile) on non-accidental, cardiovascular, and respiratory mortality for lag 0-21 days was 1.40 (95% confidence interval: 1.19-1.66), 1.61 (1.28-2.02), and 1.13 (0.78-1.64), respectively. A 1°C decrease below a cold threshold of 9.1°C (8th percentile) for lags 0-21 was associated with a 7.35% (3.75-11.09%) increase in non-accidental mortality. The cold-mortality association was not significantly affected by cause-specific mortality, gender, age, marital status, ethnicity, occupation, or previous history of hypertension.

CONCLUSIONS

There is an adverse impact of cold on mortality in Yuxi, China, and a temperature of 9.1°C is an important cut-off for cold-related mortality for residents.

Transcriptomic responses to low temperature stress in the Manila clam, Ruditapes philippinarum

The Manila clam, Ruditapes philippinarum, is an economically important shellfish in marine aquaculture, with a broad thermal tolerance. The ability to cope with cold stress is quite important for the survival of aquatic species under natural conditions. A cold-tolerant clam that can survive the winter at temperatures below 0 °C might extend our understanding of the mechanisms underlying the response to cold stress. In this study, the transcriptional response of the Manila clam to cold stress (-1 °C) was characterized using RNA sequencing. The transcriptomes of a cold-treatment (O) group of clams, which survived under cold stress, and the control group (OC2), which was not subjected to cold stress, were sequenced with the Illumina HiSeq platform. In all, 148,593 unigenes were generated. Compared with the unigene expression profile of the control group, 1760 unigenes were up regulated and 2147 unigenes were down regulated in the O group. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that signal transduction, mitochondrial metabolism, cellular component organization or biogenesis, and energy production processes were the most highly enriched pathways among the genes that were differentially expressed under cold stress. All these pathways could be assigned to the following biological functions in the cold-tolerant Manila clam: signal response to cold stress, antioxidant response, cell proliferation, and energy production.

All or nothing: Survival, reproduction and oxidative balance in Spotted Wing Drosophila (Drosophila suzukii) in response to cold

Winter severity and overwintering capacity are key ecological factors in successful invasions, especially in ectotherms. The integration of physiological approaches into the study of invasion processes is emerging and promising. Physiological information describes the mechanisms underlying observed survival and reproductive capacities, and it can be used to predict an organism's response to environmental perturbations such as cold temperatures. We investigated the effects of various cold treatments on life history and physiological traits of an invasive pest species, Drosophila suzukii, such as survival, fertility and oxidative balance. This species, a native of temperate Asian areas, is known to survive where cold temperatures are particularly harsh and has been recently introduced into Europe and North America. We found that cold treatments had a strong impact on adult survival but no effect on female's fertility. Although only minor changes were observed after cold treatment on studied physiological traits, a strong sex-based difference was observed in both survival and physiological markers (antioxidant defences and oxidative markers). Females exhibited higher survival, reduced oxidative defences, less damage to nucleic acids, and more damage to lipids. These results suggest that D. suzukii relies on a pathway other than oxidative balance to resist cold injury. Altogether, our results provide information concerning the mechanisms of successful invasion by D. suzukii. These findings may assist in the development of population models that predict the current and future geographic ranges of this species.

Abiotic stress of ambient cold temperature regulates the host receptivity to pathogens by cell surfaced sialic acids

Ambient cold temperature, as an abiotic stress, regulates the survival, stability, transmission, and infection of pathogens. However, the effect of cold temperature on the host receptivity to the pathogens has not been fully studied. In this study, the expression of terminal α-2,3- and α-2,6-sialic acids were increased in murine lung tissues, especially bronchial epithelium, by exposure to cold condition. The expression of several sialyltransferases were also increased by exposure to cold temperature. Furthermore, in human bronchial epithelial BEAS-2B cells, the expressions of α-2,3- and α-2,6-sialic acids, and mRNA levels of sialyltransferases were increased in the low temperature condition at 33 °C. On the other hand, the treatment of Lith-Gly, a sialyltransferase inhibitor, blocked the cold-induced expression of sialic acids on surface of BEAS-2B cells. The binding of influenza H1N1 hemagglutinin (HA) toward BEAS-2B cells cultured at low temperature condition was increased, compared to 37 °C. In contrast, the cold-increased HA binding was blocked by treatment of lithocholicglycine and sialyl-N-acetyl-D-lactosamines harboring α-2,3- and α-2,6-sialyl motive. These results suggest that the host receptivity to virus at cold temperature results from the expressions of α-2,3- and α-2,6-sialic acids through the regulation of sialyltransferase expression.

Asthma control and cold weather-related respiratory symptoms

BACKGROUND

In the northern hemisphere people are exposed recurrently to cold air and asthmatics experience more respiratory symptoms. We hypothesized that subjects with poor asthma control are more prone to experience cold weather-related respiratory symptoms than those with good asthma control.

METHODS

A population-based cross-sectional study of 1995 adult asthmatics (response rate 40.4%) living in the Northern Finland was conducted using a questionnaire where cold weather-related respiratory symptoms as well as questions related to asthma control were inquired. The Asthma Control Test (ACT) was defined based on five questions (disadvantage and occurrence of asthma symptoms, waking up because of asthma symptoms, use of rescue medication and self-assessment of asthma control during the past 4 weeks), and was divided into quartiles.

RESULTS

Cold weather-related respiratory symptoms were more frequent among asthmatics with poorly controlled asthma (ACT Q1 vs. ACT Q4); adjusted prevalence ratio (PR) for shortness of breath (men 1.47, 95% confidence interval 1.22-1.77; women 1.18, 1.07-1.30), cough (men 1.10, 0.91-1.34; women 1.18, 1.08-1.30), wheezing (men 1.91, 1.31-2.78; women 1.48, 1.17-1.87), phlegm production (men 1.51, 1.06-2.14; women 1.62, 1.27-2.08) and chest pain (men 4.47, 1.89-10.56; women 2.60, 1.64-4.12). The relations between asthma control and symptom occurrence seemed stronger among smokers than never smokers and subjects with body mass index (BMI) below and above 25-30.

CONCLUSIONS

Our study provides new evidence that subjects whose asthma is poorly controlled are more prone to experience cold weather-related respiratory symptoms and even a slight worsening of asthma control increases symptom prevalences.

Elevated relative risk of aneurysmal subarachnoid hemorrhage with colder weather in the mid-Atlantic region

We have previously reported an increase of 0.6% in the relative risk of aneurysmal subarachnoid hemorrhage (aSAH) in response to every 1°F decrease in the maximum daily temperature (Tmax) in colder seasons from patients presenting to our regional tertiary care center. We hypothesized that this relationship would also be observed in the warmer summer months with ambient temperatures greater than 70°F. From prospectively collected incidence data for aSAH patients, we investigated absolute Tmax, average daily temperatures, intraday temperature ranges, and the variation of daily Tmax relative to 70°F to assess associations with aSAH incidence for patients admitted to our institution between 1991 and 2009 during the hottest months and days on which Tmax>70°F. For all days treated as a group, the mean Tmax (± standard deviation) was lower when aSAH occurred than when it did not (64.4±18.2°F versus 65.8±18.3°F; p=0.016). During summer months, the odds ratio (OR) of aSAH incidence increased with lower mean Tmax (OR 1.019; 95% confidence interval 1.001-1.037; p=0.043). The proportion of days with aSAH admissions was lower on hotter days than the proportion of days with no aSAH (96% versus 98%; p=0.006). aSAH were more likely to occur during the summer and on days with a temperature fluctuation less than 10°F (8% versus 4%; p=0.002). During the hottest months of the year in the mid-Atlantic region, colder maximum daily temperatures, a smaller heat burden above 70°F, and smaller intraday temperature fluctuations are associated with increased aSAH admissions in a similar manner to colder months. These findings support the hypothesis that aSAH incidence is more likely with drops in temperature, even in the warmer months.

Cloning and characterization of aquaglyceroporin genes from rainbow smelt (Osmerus mordax) and transcript expression in response to cold temperature

Aquaglyceroporins (GLPs) are integral membrane proteins that facilitate passive movement of water, glycerol and urea across cellular membranes. In this study, GLP-encoding genes were characterized in rainbow smelt (Osmerus mordax mordax), an anadromous teleost that accumulates high glycerol and modest urea levels in plasma and tissues as an adaptive cryoprotectant mechanism in sub-zero temperatures. We report the gene and promoter sequences for two aqp10b paralogs (aqp10ba, aqp10bb) that are 82% identical at the predicted amino acid level, and aqp9b. Aqp10bb and aqp9b have the 6 exon structure common to vertebrate GLPs. Aqp10ba has 8 exons; there are two additional exons at the 5' end, and the promoter sequence is different from aqp10bb. Molecular phylogenetic analysis suggests that the aqp10b paralogs arose from a gene duplication event specific to the smelt lineage. Smelt GLP transcripts are ubiquitously expressed; however, aqp10ba transcripts were highest in kidney, aqp10bb transcripts were highest in kidney, intestine, pyloric caeca and brain, and aqp9b transcripts were highest in spleen, liver, red blood cells and kidney. In cold-temperature challenge experiments, plasma glycerol and urea levels were significantly higher in cold- compared to warm-acclimated smelt; however, GLP transcript levels were generally either significantly lower or remained constant. The exception was significantly higher aqp10ba transcript levels in kidney. High aqp10ba transcripts in smelt kidney that increase significantly in response to cold temperature in congruence with plasma urea suggest that this gene duplicate may have evolved to allow the re-absorption of urea to concomitantly conserve nitrogen and prevent freezing.