Identification of RAS genotypes that modulate blood pressure change by outdoor temperature

Monitoring with wearable devices will clarify the association between indoor temperature and blood pressure

The association of blood pressure and temperature is well known in seasonal observation, and low temperature in the winter season is often considered a cause of high blood pressure. The current evidence for short-term studies of temperature and blood pressure is based on the daily observation, however continuous monitoring with wearable devices will allow us to evaluate the rapid effect of cold temperature exposure on blood pressure. In a Japanese, prospective intervention study from 2014 to 2019 (the Smart Wellness Housing survey), approximately 90% of Japanese lived in cold houses (indoor temperature less than 18 °C). Importantly, the indoor temperature was associated with the increase of morning systolic blood pressure. We recently addressed the sympathetic nervous activation of individuals in both their houses and a highly insulated and airtight model house in the winter season using portable electrocardiography equipment. A few subjects showed a morning surge in sympathetic activity, which was more intense at their cold houses, which suggests the importance of the indoor environment in the management of early morning hypertension. In near future, real-time monitoring with wearable devices will provide important information for a better life-environment, leading to risk reduction of morning surge and cardiovascular events.

The effect of ambient temperature on blood pressure of patients undergoing hemodialysis in the Pantanal-Brazil

The objective was to analyze the association of changes in pre-dialysis systolic and diastolic blood pressure with air temperature in a municipality in the Brazilian Pantanal, a tropical climate area. Longitudinal panel study, with analysis of mixed effects models of 133 hemodialysis patients in the city of Cáceres-Mato Grosso in 2014. Air temperature showed an inverse association with pre-dialysis systolic and diastolic blood pressure. With each increase of 1 °C in the mean air temperature, the pre-dialysis systolic blood pressure decreases -0.730mmHg (p ≤ 0.000) and the pre-dialysis diastolic blood pressure decreases -0.280mmHg (p ≤ 0.000). The estimated effect was greater for systolic blood pressure, but both pre-dialysis blood pressure measures are reduced with an increase in lag (up to two days), even when adjusted for relative air humidity. Air temperature is determinant for changes in pre-dialysis systolic and diastolic blood pressure in hemodialysis patients. The temperature effect was greater for systolic blood pressure than for diastolic blood pressure.

Acute effects of temperature exposure on blood pressure: An hourly level panel study

BACKGROUND

Several epidemiological studies have shown that blood pressure changes with temperature based on the daily temperature and linear relationship assumption. However, little is known about the true curve shape of the relationship between temperature and blood pressure.

OBJECTIVES

The objective of this study was to investigate the non-linear relationship between hourly temperature and blood pressure.

METHODS

This is a prospective panel study comprising 100 participants in Suzhou, China. The blood pressure of each participant was measured >50 times between October 2013 and January 2016. Hourly temperature data were derived from the nearest monitoring station owned by the China Meteorological Administration. A Distributed Lag Nonlinear Model (DLNM) was used to investigate the relationship between hourly temperature and blood pressure.

RESULTS

We found that the relationship between hourly temperature and blood pressure was parabolic. Short-term exposure to hourly temperatures had significant cold and heat effects on systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP), and mean arterial pressure (MAP). The hourly temperature had a significant lag effect on blood pressure, with a lag time of 0-5 h. Alcohol users were more sensitive to the cold effects of hourly temperature, and the diabetic population was more sensitive to the heat effects of hourly temperature on PP.

CONCLUSION

Temperature imparts short-term effects on blood pressure. Therefore, timely protective measures during cold waves or cold weather are beneficial to maintain stable blood pressure levels to reduce the risk of blood pressure related diseases.

Modulation of blood pressure in response to low ambient temperature: The role of DNA methylation of zinc finger genes

BACKGROUND

Blood pressure rises with a drop in external temperature, but the role of DNA methylation in such blood pressure modulation has not been studied in detail. We evaluated blood pressure and DNA methylation of vascular disease-related genes in association with low temperature.

METHODS

To examine changes in blood pressure and DNA methylation associated with low temperature, we conducted repeated measures analysis among 50 participants over 3 repeated visits, and validated the association among another 52 participants. In addition, the mean of methylation changes in the identified CpG sites was evaluated with changes in blood pressure. Mediation analyses were also conducted to model the indirect association between low ambient temperature and blood pressure through changes in DNA methylation.

RESULTS

With a 1°C decrease in temperature, increases of 0.6mmHg (standard error (SE), 0.2) in SBP and 0.3mmHg (SE, 0.1) in DBP occurred (P<0.05). Of 24,490 CpG sites in vascular genes, 2 CpG sites of zinc finger (ZNF) genes were significantly associated with temperature after Bonferroni's correction in discovery and replication data. A 10% increase in methylation expression in 2 CpG sites in ZNF genes was associated with a 4-mmHg elevation in DBP (SE, 1.8; P=0.0236). The hypermethylation was attributable to the association of ambient temperature with DBP (proportion of mediation=11.8-20.4%).

CONCLUSIONS

Methylation changes in ZNF genes might be involved in the elevation of blood pressure when the body is exposed to cold temperature.

Contextualizing Genetics for Regional Heart Failure Care

Congestive heart failure (CHF) is a chronic and often devastating cardiovascular disorder with no cure. There has been much advancement in the last two decades that has seen improvements in morbidity and mortality. Clinicians have also noted variations in the responses to therapies. More detailed observations also point to clusters of diseases, phenotypic groupings, unusual severity and the rates at which CHF occurs. Medical genetics is playing an increasingly important role in answering some of these observations. This developing field in many respects provides more information than is currently clinically applicable. This includes making sense of the established single gene mutations or uncommon private mutations. In this thematic series which discusses the many factors that could be relevant for CHF care, once established treatments are available in the communities; this section addresses a contextual role for medical genetics.

Effects of cold and hot temperature on dehydration: a mechanism of cardiovascular burden

The association between temperature (cold or heat) and cardiovascular mortality has been well documented. However, few studies have investigated the underlying mechanism of the cold or heat effect. The main goal of this study was to examine the effect of temperature on dehydration markers and to explain the pathophysiological disturbances caused by changes of temperature. We investigated the relationship between outdoor temperature and dehydration markers (blood urea nitrogen (BUN)/creatinine ratio, urine specific gravity, plasma tonicity and haematocrit) in 43,549 adults from Seoul, South Korea, during 1995-2008. We used piece-wise linear regression to find the flexion point of apparent temperature and estimate the effects below or above the apparent temperature. Levels of dehydration markers decreased linearly with an increase in the apparent temperature until a point between 22 and 27 °C, which was regarded as the flexion point of apparent temperature, and then increased with apparent temperature. Because the associations between temperature and cardiovascular mortality are known to be U-shaped, our findings suggest that temperature-related changes in hydration status underlie the increased cardiovascular mortality and morbidity during high- or low-temperature conditions.

Dynamic regulation of the angiotensinogen gene by DNA methylation, which is influenced by various stimuli experienced in daily life

Angiotensinogen (AGT) has a central role in maintaining blood pressure and fluid balance. DNA methylation is an epigenomic modification maintaining a steady pattern in somatic cells. Herein we summarize the link between AGT regulation and DNA methylation. DNA methylation negatively regulates AGT expression and dynamically changes in response to continuous AGT promoter stimulation. High-salt intake and excess circulating aldosterone cause DNA demethylation around the CCAAT enhancer-binding protein-binding sites, thereby converting the phenotype of AGT expression from an inactive to an active state in visceral adipose tissue. Salt-dependent hypertension may be partially affected by increased adipose AGT expression. Because angiotensin II is a well-established aldosterone-releasing hormone, stimulation of adipose AGT by aldosterone creates a positive feedback loop. This effect is pathologically associated with obesity-related hypertension, although it would be physiologically favorable for humans to efficiently retain their body fluid. The clear difference in DNA demethylation patterns between aldosterone and cortisol indicates a difference in the respective target DNA-binding sites between mineralocorticoid and glucocorticoid receptors in the AGT promoter. Stimulation-induced interactions between transcription factors and target DNA-binding sites trigger DNA demethylation. Dynamic changes in DNA methylation occur in relaxed chromatin regions both where transcription factors actively interact and where transcription is initiated. In contrast to rapid histone modifications, DNA demethylation and remethylation will progress relatively slowly over days or years. A wide variety of stimuli in daily life will continue to slowly and dynamically change DNA methylation patterns throughout life. Wise choices of beneficial stimuli will improve health.

Angiotensin-converting enzyme gene polymorphisms and hypertension in occupational noise exposure in Egypt

BACKGROUND

The gene-environment interaction in the pathogenesis of hypertension has not been extensively studied in occupational noise.

OBJECTIVES

The aim of this study was to determine the relationship between noise and hypertension in Egyptian workers, the interaction of angiotensin-converting enzyme (ACE) gene polymorphisms as modifiers, and the possible relationship between noise hearing impairment and hypertension.

METHODS

Study subjects were divided into two groups depending on noise exposure level. The control group (n = 161) was exposed to noise intensity <85 dB and the exposed group (n = 217) was exposed to noise intensity ≧85 dB. A polymerase chain reaction was used to differentiate the various genotypes of ACE insertion/deletion (I/D) and ACE G2350A.

RESULTS

Noise significantly increased the likelihood of hypertension. Carriers of the genotypes AG, GG, and DD were vulnerable to hypertension on noise exposure. No association between hypertension and hearing impairment or noise-induced hearing loss (NIHL) was found.

CONCLUSION

Our results support the association between ACE gene polymorphisms and occurrence of hypertension in noise-exposed workers.