Creatinine to Cystatin C Ratio as a Marker of Bone Property in Older Adults: The J-SHIPP Study

OBJECTIVES

To clarify whether serum creatinine to cystatin C ratio (CCR), a marker of muscle mass and muscle function may be used as a simple marker of bone property.

DESIGN

A cross-sectional analysis.

SETTING

A general population-based observation study.

PARTICIPANTS

1,606 middle-aged to elderly (≥50 years, mean age: 66.9 ± 7.5 years old) men (n = 642) and post-menopausal women (n = 964).

MEASUREMENT

Speed of sound (SOS) at the calcaneal bone was used as a surrogate marker of bone mineral density. The cross-sectional area of the muscle at the mid-thigh was measured using computed tomography.

RESULTS

There was significant linear correlation between the quartiles of CCR and SOS (Q1: 1,495 ± 25, Q2: 1,499 ± 24, Q3: 1,507 ± 26, Q4: 1,511 ± 25 m/sec; P < 0.001) even in a sex-separated analysis. This association was independent of major covariates (Q1: β = -0.126, P < 0.001; Q2: β = -0.096, P = 0.001; Q3: β = -0.022; P = 0.412, Q4: reference) and the mid-thigh muscle mass, while creatinine alone or eGFR did not show clear association with SOS.

CONCLUSION

The CCR may be used as a simple marker of bone property independently of muscle mass in a general population with preserved renal function.

Mouth breathing, another risk factor for asthma: the Nagahama Study

BACKGROUND

Allergic rhinitis, a known risk factor for asthma onset, often accompanies mouth breathing. Mouth breathing may bypass the protective function of the nose and is anecdotally considered to increase asthma morbidity. However, there is no epidemiological evidence that mouth breathing is independently associated with asthma morbidity and sensitization to allergens. In this study, we aimed to clarify the association between mouth breathing and asthma morbidity and allergic/eosinophilic inflammation, while considering the effect of allergic rhinitis.

METHODS

This community-based cohort study, the Nagahama Study, contained a self-reporting questionnaire on mouth breathing and medical history, blood tests, and pulmonary function testing. We enrolled 9804 general citizens of Nagahama City in the Shiga Prefecture, Japan.

RESULTS

Mouth breathing was reported by 17% of the population and was independently associated with asthma morbidity. The odds ratio for asthma morbidity was 1.85 (95% CI, 1.27-2.62) and 2.20 (95% CI, 1.72-2.80) in subjects with mouth breathing alone and allergic rhinitis alone, which additively increased to 4.09 (95% CI, 3.01-5.52) when mouth breathing and allergic rhinitis coexisted. Mouth breathing in nonasthmatics was a risk for house dust mite sensitization, higher blood eosinophil counts, and lower pulmonary function after adjusting for allergic rhinitis.

CONCLUSION

Mouth breathing may increase asthma morbidity, potentially through increased sensitization to inhaled allergens, which highlights the risk of mouth-bypass breathing in the 'one airway, one disease' concept. The risk of mouth breathing should be well recognized in subjects with allergic rhinitis and in the general population.

Missense variants of the alanine: glyoxylate aminotransferase 2 gene correlated with carotid atherosclerosis in the Japanese population

Alanine:glyoxylate aminotransferase 2 (AGXT2; EC 2.6.1.44) degrades asymmetric dimethylarginine (ADMA), a competitive inhibitor of nitric oxide (NO) synthase. Increased ADMA, reduced NO, and hypertension are shown in Agxt2 knockout mice. There are four single nucleotide polymorphisms (rs37370, rs37369, rs180749, and rs16899974) with which AGXT2 activity changes in humans and may be related to vulnerability of vascular sclerosis. To examine the relationship between them, we studied the functional haplotypes of the AGXT2 gene and decided their relationship with arteriosclerotic changes via carotid intima-media thickness (carotid IMT) in Japanese subjects. Genotyping of those polymorphisms and the carotid IMT in 1,426 Japanese subjects were then evaluated. Subjects with C-A-A-A haplotype (rs37370, rs37369, rs180749, rs16899974) showed low AGXT2 activity (P<0.0001; Pearson’s correlation coefficients: 0.497). The C-A-A-A haplotype was significantly associated with mean carotid IMT (P=0.049) and max carotid IMT (P=0.004). Subjects with two C-A-A-A haplotypes exhibited thicker mean carotid IMT (P=0.022) and maximum carotid IMT (P=0.001). In multiple regression analysis, subjects with two C-A-A-A haplotypes were independently and positively associated with mean carotid IMT (P=0.02) and maximum IMT (P=0.005) after correction. There was a significant correlation between the functional variants in the AGXT2 gene and carotid IMT in Japanese. The AGXT2 genotype may be an important factor underlying atherosclerosis.

Association of central systolic blood pressure with intracerebral small vessel disease in Japanese

BACKGROUND

Recent studies have reported the association between advanced arterial stiffness and brain small vessel diseases (SVDs). Two possible hemodynamic mechanisms, increases in central blood pressure (BP) and pulsatile flow load to the brain, have been speculated to link arterial stiffness and SVD. The carotid flow augmentation index (AI) has been proposed as an index of pulsatile flow to the brain. We compared its association with brain SVD with that of central BP in a general population.

METHODS

Subjects were 500 individuals free from symptomatic cardiovascular diseases with a mean age of 66.9 +/- 8.4 years. Brachial-ankle pulse wave velocity (baPWV) was measured as an index of arterial stiffness. Carotid flow AI was obtained by Doppler ultrasonography. The presence of silent cerebral lacunar infarcts (SCI) was determined as a manifestation of SVD by 3-tesla magnetic resonance imaging (MRI). Second peak radial systolic BP (SBP2) and pulse pressure (PP2) were used as estimates of central BP.

RESULTS

baPWV was significantly associated with radial BP2 (r = 0.55, P < 0.0001) but not with carotid flow AI (r = 0.03, P = 0.51). Radial BPs and baPWV, but not flow AI, were significantly higher in subjects with SCI. Radial SBP2 had higher odds ratio for the presence of SCI than brachial SBP, PP, and radial PP2. Logistic regression analysis showed that radial SBP2, but not flow AI, was independently related to the presence of SCI.

CONCLUSION

These findings indicate that the SBP2, an estimate of central SBP, is significantly associated with the presence of SVD in an apparently healthy general population.

An association of 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism and common carotid atherosclerosis

Plasma homocysteine (Hcy) concentration has been shown to be influenced by a mutation in the gene coding methylenetetrahydrofolate reductase (MTHFR). Although plasma Hcy is related to atherosclerotic disorders, conflicting results have been reported about the association between MTHFR gene polymorphism and sclerotic lesions of the common carotid arteries. The effect of age-gene interaction on carotid arterial remodeling was investigated in elderly subjects with several risk factors for atherosclerosis. We evaluated sclerotic lesions of the common carotid arteries by ultrasonography in 326 patients (mean age +/- standard deviation, 73 +/- 12 years) and studied relations among the known risk factors for atherosclerosis, including MTHFR gene polymorphism and its interactions with age and sex. Of the 326 subjects studied, 136 had MTHFR genotype CC, 136 genotype CT, and 54 genotype TT. The three groups did not differ with respect to background factors such as age, history of cigarette smoking, blood pressure, lipids or uric acid, or in the incidence of atherosclerotic diseases. Spearman's rank correlation revealed a significant relationship between gender, age, Brinkman index, systolic blood pressure, triglycerides, HDL-cholesterol (HDL-C), uric acid, and MTHFR gene polymorphism. Multiple regression analysis using intima-media complex thickness (IMT) as a criterion variable and risk factors, including MTHFR gene polymorphism as explanatory variables showed that MTHFR gene polymorphism (P = 0.039) was a significant independent explanatory variable for IMT, along with gender (male) (P < 0.001), age (P < 0.001), systolic blood pressure (SBP) (P = 0.047), total cholesterol (T-C) (P < 0.001), and HDL-C (P < 0.001). Furthermore, a general linear model analysis revealed that interaction between age and MTHFR gene polymorphism was significantly associated with IMT, independently of age, SBP, T-C, and HDL-C in male subjects. However, age-gene interaction was not observed in female subjects. The findings of the present study confirm an association between MTHFR gene polymorphism and common carotid atherosclerosis in the Japanese population and further support the role of risk factor-gene interaction in common carotid atherosclerosis.

Association between carotid arterial remodeling and plasma concentration of circulating hepatocyte growth factor

BACKGROUND

Several studies have reported that the circulating concentration of hepatocyte growth factor (HGF) was increased in individuals with clinically overt atherosclerotic disease, including coronary heart disease and peripheral arterial disease. However, whether changes in the circulating concentration of HGF are associated with early atherosclerotic changes in apparently healthy individuals remains to be determined.

OBJECTIVE

To investigate the relationship between the plasma concentration of HGF and carotid arterial remodeling.

METHODS

Plasma concentrations of HGF were measured in 201 community-dwelling healthy residents free from any medications and signs and history of cardiovascular disease. Carotid intima-media thickness (IMT) and carotid internal diameter were determined by ultrasonography with a 7.5 MHz probe. The study participants were divided into four groups according to the presence or absence of carotid atherosclerosis (presence of plaque, IMT > or = 0.85 mm) and carotid arterial dilatation (diameter > or = 7.0 mm).

RESULTS

Carotid arterial remodeling, atherosclerosis or dilatation, or combinations thereof, was associated with significantly greater concentrations of plasma HGF. Among risk factors, plasma HGF was significantly associated with advanced age (> or = 65 years), current smoking and diabetes mellitus, whereas sex, obesity, hypertension and hypercholesterolemia did not affect plasma concentrations of HGF. Multiple regression analysis showed that plasma HGF was independently associated with carotid arterial remodeling (atherosclerosis, dilatation, or both) in addition to age and systolic blood pressure.

CONCLUSIONS

These results indicate that the plasma concentration of HGF increases in relation to carotid arterial remodeling, independently of known risk factors for atherosclerosis. These findings further support a possible role of HGF in atherosclerosis.

Risk factor–gene interaction in carotid atherosclerosis: effect of gene polymorphisms of renin-angiotensin system

The risk factor-gene interaction in carotid atherosclerosis was investigated in 205 community-dwelling healthy subjects aged 50 years or more in Japan. The intima-media thickness (IMT) of the common carotid artery was evaluated by ultrasonography with a 7.5-MHz probe. Gene polymorphisms were determined for each subject with angiotensin-converting enzyme (ACE) insertion/deletion (I/D), angiotensinogen (AGT) M235T, angiotensin II type 1 receptor (AT1R) A1166C, and apolipoprotein E (apoE) genotypes. There was no genotype-specific difference in carotid IMT among any genes examined. Combinations of genotypes did not increase carotid IMT compared with subjects without these genotypes. In the total population, multiple regression analysis showed that age, systolic blood pressure (SBP), sex, and body mass index (BMI) were significantly associated with carotid IMT. However, the association between risk factors and IMT was genotype-specific. Age was significantly associated with IMT in ACE D carriers, but not in subjects with the ACE II genotype. Analysis of covariance adjusted with other risk factors showed that the age-dependent change in IMT was significantly different between subjects with the ACE II genotype and the ACE D carriers (F[1.196] = 4.97; P = 0.027). Similarly, the regression of IMT on SBP was significantly different between AGT TT and AGT MT + MM (F[1.196] = 7.20; P = 0.0079). The regression of IMT on BMI was also significantly different between apo E4 carriers and noncarriers (F[1.196] = 6.78; P = 0.0099). Furthermore, general linear model analysis with risk factors, genotype, and risk factor-genotype interactions revealed that the age*ACE genotype interaction, the SBP*AGT genotype interaction, and the BMI*apoE genotype interaction were significantly associated with IMT. These findings further support the role of risk factor-gene interaction in carotid atherosclerosis.