Frigid Zone Medicine

Abstract:
Cardiovascular diseases (CVDs) have been the top-ranked cause of human death in the world for years, according to the World Health Organization. Accumulating evidence from epidemiological data supports the view that the risk of CVDs is higher in northern China than in southern area. There is no doubt that living environment has become a crucial factor contributing to the occurrence and progression of CVDs in northern region. However, there have not been any clinical guidelines for the prevention strategy of environment-related CVDs, especially for cold exposure. Thus, there is an urgent need for better understanding of the clinical characteristics and underlying mechanisms of cold-induced CVDs in order to formulate and implement proper and effective measures for minimizing the risk of CVDs for people residing in low-temperature area. Cold exposure, air pollution, lack of sunlight and irrational diet are believed to be crucial factors responsible for environment-related CVDs, and preventive measures might be carried out accordingly to decrease the high risk of CVDs in northern China.

Effect of aging on cardiovascular responses to cold stress in humans

Tiankai Li, Qi Wang, Cheping Cheng

2022, 2(3): 149-157. doi: 10.2478/fzm-2022-0022

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Abstract:
Cold exposure increases the risk of adverse events related to cardiovascular causes, especially in the elderly. In this review, we focus on recent findings concerning the impact of aging on the regulatory mechanisms of cold-induced cardiovascular responses. In response to cold exposure, the initial physiological thermoregulation in healthy young persons, such as cutaneous vasoconstriction to reduce heat loss, is attenuated in older individuals, resulting in a reduced ability of the older persons to maintain body temperature in cold environment. Impaired sympathetic skin response, reduced noradrenergic neurotransmitter synthesis, insufficient noradrenergic transmitters, and altered downstream signaling pathways inside the vascular smooth muscle may be among the underlying mechanisms for the maladaptive vasoconstrictive response to cold stress in the elderly. The increase in blood pressure during cold exposure in young persons may be further augmented in aging adults, due to greater central arterial stiffness or diminished baroreflex sensitivity with aging. Cold stress raises myocardial oxygen demand caused by increased afterload in both young and old adults. The elderly cannot adjust to meet the increased oxygen demand due to reduced left ventricular compliance and coronary blood flow with advancing age, rendering the elderly more susceptible to hypothermiainduced cardiovascular complications from cold-related diseases. These age-associated thermoregulatory impairments may further worsen patients' health risk with existing cardiovascular diseases such as hypertension, coronary artery disease, and heart failure. We searched PubMed for papers related to cold stress and its relationship with aging, and selected the most relevant publications for discussion.

RNA modification by M6A methylation in cardiovascular diseases: Current trends and future directions

Jinglin Wang, Lingfeng Zha

2022, 2(3): 158-177. doi: 10.2478/fzm-2022-0023

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Abstract:
N6-methyladenosine (M6A) is the most common modification in eukaryotic RNAs for the regulation of RNA transcription, processing, splicing, degradation, and translation. RNA modification by M6A is dynamically reversible, involving methylated transferase, demethylase, and methylated reading protein. M6A-mediated gene regulation involves cell differentiation, metastasis, apoptosis, and proliferation. Dysregulation of M6A can lead to various diseases. Cardiovascular disease (CVD) seriously endangers human health and brings great social burden. Seeking effective prevention and treatment strategies for CVD is a challenge to both fundamentalists and clinicians. Substantial evidence has suggested the key role of M6A modification in the development of CVDs. This review summarizes the mechanism of M6A RNA modification and the latest research progress in respect with its role in CVDs, including atherosclerosis, coronary artery disease, myocardial infarction and cardiac remodeling, myocardial ischemia-reperfusion injury, heart failure, hypertension, and aortic aneurysm, and the potential applications of the findings to CVDs, thereby providing new ideas and approaches for the diagnosis and therapy of CVDs.

Extreme temperature increases the severity of intracerebral hemorrhage: An analysis based on the cold region of China

Xun Xu, Chunyang Liu, Rui Liu, Qiuyi Jiang, Enzhou Lu, Chao Yuan, Yanchao Liang, Huan Xiang, Boxian Zhao, Xin Chen, Ailing Lian, Qi Zhou, Guang Yang

2022, 2(3): 178-185. doi: 10.2478/fzm-2022-0024

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Abstract:
Objective The purpose of this study was to find a suitable model to evaluate the relationship between temperature and intracerebral hemorrhage (ICH) and explore the effects of cold spells and heat waves on the clinicopathological parameters of ICH patients. Methods We conducted a retrospective study based on the ICH admission in the First Affiliated Hospital of Harbin Medical University from 2015 to 2020 (N = 11 124). The relationship between different seasons and the number of patients with ICH was explored. Poisson Akaike information criterion (AIC) was used to select the optimal model for temperature and ICH. Binary logistic regression analysis was used to investigate the association between extreme temperatures and clinicopathological features. Results Hospital admissions for patients with ICH showed monthly changes. The optimal cold spell was defined as the daily average temperature < 3rd percentile, lasting for five days, while the optimal heat wave was defined as the daily average temperature > 97th percentile, lasting for three days. Based on the generalized extreme weather model, cold climate significantly increased the risk of hematoma volume expansion (OR 1.003; 95% CI: 1.000-1.005, P = 0.047). In the optimal model, the occurrence of cold spells and heat waves increased the risk of midline shift in both conditions (OR 1.067; 95% CI: 1.021-1.115, P = 0.004; OR 1.077; 95% CI: 1.030-1.127, P = 0.001). Conclusion Our study shows that seasonal cold spells and heat waves are essential factors affecting ICH severity, and targeted preventive measures should be taken to minimize the pathological impacts.

The influence of extreme cold ambient temperature on out of hospital cardiac arrest: A systemic review and meta-analysis

Yanxia Lin, Huanrui Zhang, Shijie Zhao, Guohui Hua, Wen Tian

2022, 2(3): 186-192. doi: 10.2478/fzm-2022-0025

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Abstract:
Objective Many researches have demonstrated the effects of the extreme cold ambient temperature on the risk of out-of-hospital cardiac arrest (OHCA); yet, the results have been inconsistent. We performed a meta-analysis to evaluate whether extreme cold ambient temperature is related to OHCA. Methods We searched for time-series studies reporting associations between extreme cold ambient temperature and OHCA in PubMed, web of science and Cochrane database. Results Six studies involving 2 337 403 cases of OHCA were qualified for our meta-analysis. The odds ratio (OR) of OHCA was significantly increased in extreme cold weather (defined as the 1st or 5th centile temperature year-round) compared to reference temperature (as the 25th centile temperatures or daily mean temperature with minimum risk of OHCA) (OR=1.49, 95% CI 1.18-1.88). The subgroup analysis for the elderly and the female failed to detect the influence of extreme cold weather on OHCA, the ORs are 1.25 (95% CI 0.89-1.75) and 1.19 (95% CI 0.87-1.64), respectively. Conclusion The risk of OHCA is significantly higher in extreme cold ambient temperatures than in reference temperature, according to a relative temperature scale with percentiles of the regionspecific temperature distribution.

2022 Vol. 2, No. 3

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