Role of City Texture in Urban Heat Islands at Nighttime.

An urban heat island (UHI) is a climate phenomenon that results in an increased air temperature in cities when compared to their rural surroundings. In this Letter, the dependence of an UHI on urban geometry is studied. Multiyear urban-rural temperature differences and building footprints data combined with a heat radiation scaling model are used to demonstrate for more than 50 cities worldwide that city texture-measured by a building distribution function and the sky view factor-explains city-to-city variations in nocturnal UHIs. Our results show a strong correlation between nocturnal UHIs and the city texture.

Association of stromal-derived factor-1 alpha and endogenous sex hormones in men aged over 50 years with stable coronary artery disease.

PURPOSE: Many studies indicate an inverse relationship between stromal-derived factor-1 alpha (SDF-1 alpha), a chemokine, and coronary risk factors. Moreover, SDF-1 alpha is crucial in neoangiogenesis and in the mobilization and homing of endothelial progenitor cells to the ischemic coronary vessels. Numerous studies indicate that circulating sex hormones are associated with atherogenesis during male aging. The aim of this study was therefore to determine whether there exists a relationship between SDF-1 alpha and endogenous sex hormones in aging men with stable coronary artery disease (CAD). MATERIAL AND METHODS: Plasma concentrations of SDF-1 alpha, testosterone (T), estradiol (E2), and sex hormone binding globulin (SHBG) were measured and the E2/T ratio was calculated in a cross-sectional study of 82 men over 50 years of age with stable CAD. RESULTS: SDF-1 alpha was positively and significantly correlated with T (r = 0.233; p = 0.036) and with SHBG (r = 0.312; p = 0.004). There was a significant inverse correlation between SDF-1 alpha and the E2/T ratio (r = -0.463; p < 0.001). After adjustment for age, body mass index and smoking status, SHBG and E2/T ratio were the only factors associated with SDF-1 alpha. CONCLUSIONS: T and SHBG (directly) and the E2/T ratio (inversely) may be involved in the etiopathogenesis of CAD through their relationships to SDF-1 alpha.

Polymorphisms of angiotensin-converting enzyme and angiotensin II receptor type 1 genes in essential hypertension in a Polish population.

BACKGROUND: The angiotensin-converting enzyme gene and the angiotensin II type 1 receptor gene meet the criteria for candidate genes in the pathogenesis of essential hypertension. The aim of this study was to assess the possible association between polymorphisms of these genes and essential hypertension in a Polish population, to evaluate them as possible genetic markers of susceptibility to hypertension, and to search for interaction between the two polymorphisms. MATERIAL AND METHODS: The insertion/deletion polymorphism at the angiotensin-converting enzyme gene locus and the A1166C polymorphism at the angiotensin II type 1 receptor gene locus were detected using the polymerase chain reaction and restriction fragment length methods. 250 patients with stable essential hypertension lasting at least 1 year were compared to 150 individuals without signs and symptoms of cardiovascular disease or family history of hypertension. RESULTS: No association was found between the insertion/deletion polymorphism at the angiotensin-converting enzyme locus and essential hypertension in the study population, although the DD genotype occurred more often (p<0.01) among patients with hypertension and a negative family history of hypertension than among hypertensives with a positive family history. There was an association in our study population between hypertension and the A1166C polymorphism at the angiotensinogen II type 1 receptor gene locus. The frequency of occurrence of the C1166 variant was higher among patients with hypertension (0.29) than in control subjects (0.20). The CC genotype occurred more frequently among hypertensives (0.10) than in the control group (0.04). Both these differences were statistically significant. This association was stronger in males, patients with a negative family history of hypertension, and non-obese patients with a body mass index less than 26 kg/m2. To test the interaction between the polymorphisms in question, the distribution of the A1166 and C1166 variants among ACE genotypes was assessed. The A1166 variant occurs more often among DD genotype normotensives. CONCLUSIONS: There was no association in our study population between essential hypertension and the I/D polymorphism at the angiotensin-converting enzyme gene locus. The C1166 variant of the angiotensin II type 1 receptor gene was associated with hypertension in our study population, while the A1166 variant seems to be protective as regards susceptibility to hypertension.

[Methylenetetrahydrofolate reductase gene polymorphism in patients with type 2 diabetes]. / Polimorfizm genu reduktazy metylenotetrahydrofolianu u pacjentów z cukrzyca typu 2.

Hyperhomocysteinemia is recognised as a risk factor of ischaemic heart disease and vascular complications of arterial hypertension. Methylenetetrahydrofolate reductase (MTHFR) gene C677T polymorphism is associated with hyperhomocysteinaemia. The aim of the study was the assessment of an association of the above polymorphism with type 2 diabetes with special attention to myocardial infarction and arterial hypertension accompanying diabetes. The study group consisted of 172 type 2 diabetics. 172 control subjects with normal glucose tolerance were age and sex matched to patients with diabetes. C677T polymorphism in MTHFR gene locus was detected using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method. CT and TT genotypes were found more often among diabetics (OR 1.83, 95% CI 1.16-2.89; p < 0.01). This finding may be secondary to the excess of T allele bearers among diabetics with myocardial infarction when compared to diabetics without infarction and to control group. Upon obtained results the potential role of genotypes CT and TT as risk factors of myocardial infarction among patients with type 2 diabetes could not be excluded (OR 2.33, 95% CI 0.93-5.8; p = 0.07). Genotypes containing T allele are not associated with diabetes type 2 and concomitant arterial hypertension (OR 1.45, 95% CI 0.89-2.57; p = 0.14). A confirmation in further studies is needed for the presented findings.

Restriction fragment length polymorphisms in the apolipoprotein B gene in survivors of myocardial infarction.

INTRODUCTION: The aim of this study was to investigate the association between Pvu II and Msp I polymorphisms of the human apolipoprotein B gene and risk of myocardial infarction in 90 survivors of myocardial infarction. Apolipoprotein B is important in the metabolism of lipoproteins and there is an evidence suggesting that this apolipoprotein plays a central role in atherogenesis. Some polymorphisms in the apolipoprotein B gene are associated with peripheral arterial disease, coronary artery disease and risk of myocardial infarction. MATERIAL AND METHODS: DNA was prepared from the whole blood. Samples from patients and control group were digested with Pvu II restriction enzyme. Filters were prepared by Southern blotting technique and hybridized with ApoB probe (LB25-A). Genotypes for Msp I polymorphism were determined with polymerase chain reaction. RESULTS: The frequency of the rarer allele (P2) for Pvu II polymorphism in the apolipoprotein B gene was significantly higher in myocardial infarction group (P = 0.001) compared with healthy individuals. A significant association was also found between P2 allele and the age at which myocardial infarction occurred. CONCLUSION: The results suggest that in Polish population the individuals with P2 allele of the apolipoprotein B gene are at increased risk of developing myocardial infarction. No significant correlation with myocardial infarction event was found for the Msp I polymorphism.

[Angiotensin converting enzyme gene polymorphism in type 2 diabetes mellitus]. / Polimorfizm genu enzymu konwertujacego angiotensyne (ACE) u chorych na cukrzyce typu 2.

The aim of this study is the assessment of the association of human angiotensin-converting enzyme gene I/D polymorphism with type 2 diabetes in 155 diabetic patients and 139 healthy individuals. These polymorphism were studied using polymerase chain reaction. Angiotensin converting enzyme gene DD genotype associated with type 2 diabetes in overweight and obese patients and patients with normal total plasma cholesterol. There is also association of DD genotype with arterial hypertension and with myocardial infarction in type 2 diabetic patients.

[M235T polymorphism of human angiotensinogen gene in essential hypertension in Polish population]. / Polimorfizm M235T ludzkiego genu angiotensynogenu w pierwotnym nadcisnieniu tetniczym w populacji polskiej.

Genetic factors play very important role in the pathogenesis of essential hypertension. Angiotensinogen gene is one of the candidate genes in the research concerning genetic background of elevated blood pressure. The aim of this work was to assess an association of M235T polymorphism in human angiotensinogen gene with essential hypertension in Polish population. 250 patients with essential hypertension and 150 normotensives were involved in the study. M235T polymorphism was detected using polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) methods. Polymorphic allele and genotypes frequencies did not differ between hypertensive and normotensive groups. However T allele and TT genotype frequency among hypertensive men was higher than in normotensive men. The difference is statistically significant. T allele and TT genotype occurred more frequently in hypertensives with positive family history of essential hypertension. The difference between hypertensive men with positive family history and normotensive men was even more significant. This results are similar to those already published by other authors concerning Caucasian populations and indicate that angiotensinogen gene is involved in the determination of at least some cases of essential hypertension.