Clinical Implication of Smoking-Related Aryl-Hydrocarbon Receptor Repressor (AHRR) Hypomethylation in Japanese Adults.

BACKGROUND: Tobacco smoking is a leading preventable cause of morbidity and mortality worldwide; still, the success rate of smoking cessation is low in general. From the viewpoint of public health and clinical care, an objective biomarker of long-term smoking behavior is sought.Methods and Results: This study assessed DNA methylation as a biomarker of smoking in a hospital setting through a combination of molecular approaches including genetic, DNA methylation and mRNA expression analyses. First, in an epigenome-wide association study involving Japanese individuals with chronic cardiovascular disease (n=94), genome-wide significant smoking association was identified at 2 CpG sites on chromosome 5, with the strongest signal at cg05575921 located in intron 3 of the aryl-hydrocarbon receptor repressor (AHRR) gene. Highly significant (P<1×10-27) smoking-cg05575921 association was validated in 2 additional panels (n=339 and n=300). For the relationship of cg05575921 methylation extent with time after smoking cessation and cumulative cigarette consumption among former smokers, smoking-related hypomethylation was found to remain for ≥20 years after smoking cessation and to be affected by multiple factors, such as cis-interaction of genetic variation. There was a significant inverse correlation (P=0.0005) between cg05575921 methylation extent and AHRR mRNA expression. CONCLUSIONS: The present study results support that reversion of AHRR hypomethylation can be a quantifiable biomarker for progress in and observance of smoking cessation, although some methodological points need to be considered.

Case Report of Left Ventricular Noncompaction Cardiomyopathy Characterized by Undulating Phenotypes in Adult Patients.

Left ventricular noncompaction cardiomyopathy (LVNC) is a heart muscle disorder morphologically characterized by reticulated trabeculations and intertrabecular recesses in the left ventricular (LV) cavity. LVNC is a genetically and phenotypically heterogeneous condition, which has been increasingly recognized with the accumulation of evidence provided by genotype-phenotype correlation analyses. Here, we report 2 sporadic adult cases of LVNC; both developed acute heart failure as an initial clinical manifestation and harbored causal sarcomere gene mutations. One case was a 57-year-old male with digenic heterozygote mutations, p.R1344Q in myosin heavy chain 7 (MYH7) and p.R144W in troponin T2, cardiac type (TNNT2), who showed morphological characteristics of LVNC in the lateral to apical regions of the LV together with a comorbidity of non-transmural myocardial infarction, resulting from a coronary artery stenosis. After the removal of ischemic insult and standard heart failure treatment, LVNC became less clear, and LV function gradually improved. The other case was a 36-year-old male with a heterozygote mutation, p.E334K in myosin binding protein C3 (MYBPC3), who exhibited cardiogenic shock on admission with morphological characteristics of LVNC being most prominent in the apical segment of the LV. The dosage of beta-blocker was deliberately increased in an outpatient clinic over 6 months following hospitalization, which remarkably improved the LV ejection fraction from 21% to 54.3%. Via a combination of imaging and histopathological and genetic tests, we have found that these cases are not compatible with a persistent phenotype of primary cardiomyopathy, but their morphological features are changeable in response to treatment. Thus, we point out phenotypic plasticity or undulation as a noticeable element of LVNC in this case report.

Effects of renal Na+/Ca2+ exchanger 1 inhibitor (SEA0400) treatment on electrolytes, renal function and hemodynamics in rats.

BACKGROUND: Na(+)/Ca(2+) exchanger 1 (NCX1) controls intracellular Ca(2+) concentration in various cell types. In the kidney, NCX1 is expressed mainly in the distal tubular basolateral membrane as well as in vascular smooth muscle. Tubular NCX1 is involved in Ca(2+) reabsorption, and NCX1 in renal arterioles may control intraglomerular pressure. However, the functions of renal NCX1 have not been studied in vivo. Therefore, this study examined the effects of renal NCX1 blockade on water and solute metabolism, renal function and blood pressure in rats. METHODS: Wistar-Kyoto rats were uninephrectomized, and an osmotic mini pump was implanted to infuse the remnant kidney cortex with a specific NCX1 inhibitor, SEA0400 (SEA), or vehicle for 7 days. RESULTS: Serum Ca(2+) concentration and urinary Ca(2+) excretion were similar between the vehicle- and SEA-treated groups. However, serum phosphate was significantly decreased by 8 % in the SEA group, with similar urinary phosphate excretion between the two groups. Systolic blood pressure was higher in the SEA group (117 ± 3 vs. 126 ± 1 mmHg, n = 9-11), with a 1.6-fold increase in plasma aldosterone concentration. However, SEA significantly reduced urinary protein excretion and the glomerular sectional area by 16 and 8 %, respectively. Similar experiment in spontaneously hypertensive rats produced different results. CONCLUSION: Renal SEA treatment reduced serum phosphate concentration, urinary protein and glomerular size with higher systemic blood pressure compared to control Wistar-Kyoto rats. Further study on renal NCX1 may be beneficial in delineating the pathophysiology of glomerular pressure control and calcium/phosphate regulations.

Effects of a high-sodium diet on renal tubule Ca2+ transporter and claudin expression in Wistar-Kyoto rats.

BACKGROUND: Urinary Ca2+ excretion increases with dietary NaCl. NaCl-induced calciuria may be associated with hypertension, urinary stone formation and osteoporosis, but its mechanism and long-term effects are not fully understood. This study examined alterations in the expressions of renal Ca2+ transporters, channels and claudins upon salt loading to better understand the mechanism of salt-induced urinary Ca2+ loss. METHODS: Eight-week old Wistar-Kyoto rats were fed either 0.3% or 8% NaCl diet for 8 weeks. Renal cortical expressions of Na+/Ca2+ exchanger 1 (NCX1), Ca2+ pump (PCMA1b), Ca2+ channel (TRPV5), calbindin-D28k, and claudins (CLDN-2, -7, -8, -16 and -19) were analyzed by quantitative PCR, western blot and/or immunohistochemistry. RESULTS: Fractional excretion of Ca2+ increased 6.0 fold with high-salt diet. Renal cortical claudin-2 protein decreased by approximately 20% with decreased immunological staining on tissue sections. Claudin-16 and -19 expressions were not altered. Renal cortical TRPV5, calbindin-D28k and NCX1 expressions increased 1.6, 1.5 and 1.2 fold, respectively. CONCLUSIONS: Chronic high-salt diet decreased claudin-2 protein and increased renal TRPV5, calbindin-D28k, and NCX1. Salt loading is known to reduce the proximal tubular reabsorption of both Na+ and Ca2+. The reduction in claudin-2 protein expression may be partly responsible for the reduced Ca2+ reabsorption in this segment. The concerted upregulation of more distal Ca2+-transporting molecules may be a physiological response to curtail the loss of Ca2+, although the magnitude of compensation does not seem adequate to bring the urinary Ca2+ excretion down to that of the normal-diet group.

Venous thromboembolism is caused by prothrombin p.Arg541Trp mutation in Japanese individuals.

Venous thromboembolism (VTE) is a multifactorial disease. Because low-frequency variants and rare mutations have been found to predispose carriers toward VTE, there is a need for variant discovery in clinical settings. Therefore, we used a whole-exome approach for a young VTE patient with a positive family history. We identified in the proband and his affected mother a rare, functional missense variant of prothrombin, p.Arg541Trp, which contributes to the clinical picture of VTE.

Urinary Sodium-to-Potassium Ratio Tracks the Changes in Salt Intake during an Experimental Feeding Study Using Standardized Low-Salt and High-Salt Meals among Healthy Japanese Volunteers.

The Na/K ratio is considered to be a useful index, the monitoring of which allows an effective Na reduction and K increase, because practical methods (self-monitoring devices and reliable individual estimates from spot urine) are available for assessing these levels in individuals. An intervention trial for lowering the Na/K ratio has demonstrated that a reduction of the Na/K ratio mainly involved Na reduction, with only a small change in K. The present study aimed to clarify the relationship between dietary Na intake and the urinary Na/K molar ratio, using standardized low- and high-salt diets, with an equal dietary K intake, to determine the corresponding Na/K ratio. Fourteen healthy young adult volunteers ingested low-salt (3 g salt per day) and high-salt (20 g salt per day) meals for seven days each. Using a portable urinary Na/K meter, participants measured their spot urine at each voiding, and 24-h urine was collected on the last day of each diet period. On the last day of the unrestricted, low-salt, and high-salt diet periods, the group averages of the 24-h urine Na/K ratio were 4.2, 1.0, and 6.9, while the group averages of the daily mean spot urine Na/K ratio were 4.2, 1.1, and 6.6, respectively. The urinary Na/K ratio tracked changes in dietary salt intake, and reached a plateau approximately three days after each change in diet. Frequent monitoring of the spot urine Na/K ratio may help individuals adhere to an appropriate dietary Na intake.

Characteristic expressions of GABA receptors and GABA producing/transporting molecules in rat kidney.

Gamma-aminobutyric acid (GABA) is an important neurotransmitter, but recent reports have revealed the expression of GABAergic components in peripheral, non-neural tissues. GABA administration induces natriuresis and lowers blood pressure, suggesting renal GABA targets. However, systematic evaluation of renal GABAergic components has not been reported. In this study, kidney cortices of Wistar-Kyoto rats (WKY) were used to assay for messenger RNAs of GABA-related molecules using RT-PCR. In WKY kidney cortex, GABAA receptor subunits, α1, ß3, δ, ε and π, in addition to both types of GABAB receptors, R1 and R2, and GABAC receptor ρ1 and ρ2 subunit mRNAs were detected. Kidney cortex also expressed mRNAs of glutamate decarboxylase (GAD) 65, GAD67, 4-aminobutyrate aminotransferase and GABA transporter, GAT2. Western blot and/or immunohistochemistry were performed for those molecules detected by RT-PCR. By immunofluorescent observation, co-staining of α1, ß3, and π subunits was observed mainly on the apical side of cortical tubules, and immunoblot of kidney protein precipitated with π subunit antibody revealed α1 and ß3 subunit co-assembly. This is the first report of GABAA receptor π subunit in the kidney. In summary, unique set of GABA receptor subunits and subtypes were found in rat kidney cortex. As GABA producing enzymes, transporters and degrading enzyme were also detected, a possible existence of local renal GABAergic system with an autocrine/paracrine mechanism is suggested.

Mini nutritional assessment as a useful method of predicting the development of pressure ulcers in elderly inpatients.

OBJECTIVES: To determine the usefulness of the Mini Nutritional Assessment (MNA) and plasma amino acid analysis in predicting the formation of pressure ulcers (PUs) in inpatients. DESIGN: Prospective, observational cohort study with a mean observation period of 62.2 ± 86.4 days. SETTING: Intermediate and acute care wards of a hospital in rural Japan. PARTICIPANTS: Inpatients with an average age of 85.0 ± 7.6 (N = 422). MEASUREMENTS: Mini Nutritional Assessment, Subjective Global Assessment (SGA), Braden Scale (PU prognostic score), PU formation, and biochemical analysis including plasma amino acid concentrations. RESULTS: PUs developed in 7.1% of participants. A MNA score of less than 8 was more sensitive than a rating of moderate or severe malnourishment on the SGA combined with a Braden Scale score of less than 15 in predicting future PUs. The area under the receiver operating characteristic curve (AUC) of the MNA was superior to that of the Braden Scale. The Braden Scale nutrition subscore had the lowest AUC of the six Braden Scale subscores. Individuals who developed PUs had significantly lower plasma arginine concentrations than those who did not. CONCLUSION: Mini Nutritional Assessment was able to predict the development of PUs. A MNA score of less than 8 performed better than the SGA, Braden Scale, and plasma arginine levels in predicting PU development. Although lower plasma arginine concentration at time of admission was associated with PU development, the AUC for arginine was not significantly different from 0.50. The findings from this prospective study support the use of nutritional assessment in inpatients to predict PU risk and target appropriate interventions.