Reliable purity assay of highly hygroscopic trichloroacetic acid for the development of high-purity reference material of NMIJ CRM 4074-a.

Trichloroacetic acid is known as one of the harmful disinfection byproducts with chlorine of tap water and is regulated according to legally binding standards in Japanese Drinking Water Quality Standards. We developed a high-purity trichloroacetic acid reference material, NMIJ CRM 4074-a, with certified purity as a traceability source of standard solution supplied under the Japan Calibration Service System (JCSS). As trichloroacetic acid is hygroscopic, water could be the main impurity. Although all impurities in the sample can be possibly detected by the freezing point depression method (FPD), it was unclear for trichloroacetic acid whether water was detected by FPD owing to evaporation of water from the sample during fusion. Therefore, we confirmed that water in trichloroacetic acid was detected as an impurity by FPD. The procedure was validated from an increment of purity by FPD due to reduction of water content and an agreement of purity by FPD with those by neutralization titrimetry (NT) and mass balance approach (MBA), both methods were based on different measurement principles from FPD. The certified value was determined to be (0.999 ± 0.003) kg kg-1 from the purity assay by FPD and NT, and uncertainties due to the homogeneity and stability of the CRM were included in the expanded uncertainty. The reliability of the certified value was verified by the agreement of purities by FPD, NT, and MBA.

Determination of PAHs in Solution with a Single Reference Standard by a Combination of 1H Quantitative NMR Spectroscopy and Chromatography.

We have applied a combination of 1H quantitative NMR spectroscopy (1H-qNMR) and chromatography (GC or LC) to establish reliable analytical methods (qNMR/GC and qNMR/LC) for organic compounds. In this method, a reference standard is used as an internal standard for both 1H-qNMR and chromatography to estimate relative molar sensitivity (RMS) for analytes. The RMS values are calculated from the molar ratios between analytes and the reference standard obtained by 1H-qNMR; and the response ratio between them obtained by chromatography. Concentrations of analytes in the organic solution can be simultaneously determined from the RMS and amount of the reference standard added in the sample solution. This analytical method is an innovative one because only one reference standard with International System of Units (SI)-traceable property value, purity, or concentration, is necessary to determine accurate concentrations of multiple organic components in organic solutions, without the respective certified reference standards for various analytes. To verify this method, a certified reference material, NIST SRM 1647f, was used. Among the 16 polycyclic aromatic hydrocarbons (PAHs) included in NIST SRM 1647f, naphthalene and benzo[a]pyrene were selected as analytes for this method, using 1,4-bis(trimethylsilyl)benzene-d4 as the reference standard. Each quantitative value obtained by qNMR/GC and qNMR/LC agreed with each certified value within its expanded uncertainty.

Usefulness of carotid plaque (sum and maximum of plaque thickness) in combination with intima-media thickness for the detection of coronary artery disease in asymptomatic patients with diabetes.

AIMS/INTRODUCTION: The usefulness of markers of carotid plaque, such as sum (PS) and maximum (P-max) of the plaque thickness, in combination with intima-media thickness in the common carotid artery (CIMT) for the detection of obstructive coronary artery disease (CAD) was investigated in patients with type 2 diabetes without known CAD. MATERIALS AND METHODS: B-mode ultrasonographic scanning of the carotid artery and multislice computed tomography coronary angiography were carried out in 332 asymptomatic patients with type 2 diabetes. RESULTS: For the presence of obstructive CAD when incorporating PS or P-max to standard risk factors in a multiple logistic regression model, the classification ability in PS and P-max increased greatly (area under the curve [AUC] 0.827 vs 0.720 [net reclassification index {NRI} = 0.652, P < 0.01] and AUC 0.820 vs 0.720 [NRI = 0.775, P < 0.01], respectively), and it in CIMT increased slightly (AUC 0.740 vs 0.720, NRI = 0.230, P = 0.041). Furthermore, the classification abilities for a model with interaction terms between PS* or P-max* and CIMT were statistically larger than those for a model without interaction terms (AUC 0.833 vs 0.827 [NRI = 0.411, P < 0.01] and 0.823 vs 0.820 [NRI = 0.269, P < 0.05], respectively). Partitioning showed the patients in the values of the PS <2.6 mm and CIMT <0.725 mm (100%), or in P-max <2.1 mm and CIMT <0.725 mm (95.4%), did not have obstructive CAD, whereas those in the values of PS ≧2.6 mm, presence of hyperlipidemia and CIMT ≧0.675 mm (84%) or those in the value of P-max ≧2.1 mm and body mass index ≧24 (91.7%) had obstructive CAD. CONCLUSIONS: Although the P-max and PS in the carotid artery were useful as detectors of CAD, combining them with CIMT provided a much superior first-line screening method in detecting CAD in asymptomatic patients with diabetes.

Purity Determination of Acetaldehyde in an Acetaldehyde Certified Reference Material.

Acetaldehyde is regulated as a toxic substance in various fields, and the method for monitoring or analysis of acetaldehyde is important. However, handling is difficult because of the high reactivity and low boiling point of acetaldehyde. Therefore, a reference material for high purity acetaldehyde with high accuracy was not available. Although the measuring method of acetaldehyde as a reagent is published in the Japanese Industrial Standard (JIS) where the specification of acetaldehyde purity is more than 80%, the analytical method described in JIS is not enough for an accuracy purity determination method. In this research, the high precision purity determination method for development of a certified reference material (CRM) of acetaldehyde was examined. By controlling the volatility and reactivity of acetaldehyde, we established the purity determination method of acetaldehyde with a relative standard uncertainty of less than 0.3%. Furthermore, this method was applied to develop a high purity acetaldehyde CRM with an expanded uncertainty of 0.005 kg kg(-1) (k = 2).

Usefulness of sum of the thickness of plaque in the carotid artery for predicting the presence and the extent of the coronary artery disease in patients with type 2 diabetes mellitus without known coronary artery disease.

AIMS: The usefulness of the sum of plaque thickness in the carotid artery (plaque score; PS), as a prediction of coronary artery disease (CAD) was investigated in patients with type 2 diabetes mellitus. METHODS: B mode ultrasonographic scanning of the carotid artery and multislice computed tomography (MSCT) coronary angiography were performed in 227 diabetic patients without known cardiac disease. RESULTS: The PS was useful to predict the presence of diseased [nonobstructive and obstructive] CAD (≧3 segments) and obstructive (≧50%) CAD with cut-off value of 3.5mm (area under curve: 0.745 and 0.782, respectively), according to a receiver operating characteristics curve analysis. A multivariate logistic analysis of baseline risk factors showed that the PS was independent risk factor for the prediction of diseased and obstructive coronary artery disease (R(2)=0.2165, p<0.0001 and R(2)=0.2265, p<0.0001, respectively). The PS was most significant predictor of the number of diseased and obstructive segments of the coronary artery in a multiple regression analysis (R(2)=0.2022, p<0.0001 and R(2)=0.2209, p<0.0001, respectively). CONCLUSIONS: The PS in the carotid artery was useful for the prediction of the presence and the extent of CAD, and was most important as a screening test for the identification of a high risk group of asymptomatic diabetic patients.

Genetic differences among C57BL/6 substrains.

The C57BL/6 mouse is the most well-known inbred mouse strain, and has been widely used as a genetic background for congenic and mutant mice. A number of C57BL/6 substrains have been derived from the C57BL/6 founder line and are reported to differ in several phenotypes. There are several major sources of C57BL/6 substrains for the biomedical research community. The importance of their genetic and phenotypic differences among substrains, however, has not yet been well recognized by biomedical researchers. Here, we report the result of screening of the functional deletion of the nicotinamide nucleotide transhydrogenase (Nnt) gene and 1,446 SNPs genotyping among seven C57BL/6 substrains from different sources, such as C57BL/6J, C57BL/6JJcl, C57BL/6JJmsSlc, C57BL/6NJcl, C57BL/6NCrlCrlj, C57BL/6NTac, and C57BL/6CrSlc. The deletion of exon 7-11 in the Nnt gene that was previously reported in C57BL/6J was also observed in other C57BL/6J substrains, indicating that this functional deletion probably occurred at an early stage in the establishment of C57BL/6J substrains. The genotyping of SNP loci clearly demonstrate genetic differences between C57BL/6J and C57BL/6N substrains at 11 loci. Besides, we found another SNP differing between C57BL/6J and other C57BL/6J substrains available from commercial breeders. No genetic difference was detected among C57BL/6N substrains. The C57BL/6CrSlc mouse, originally derived from the National Cancer Institute of the NIH was found to be the same as the C57BL/6N substrains by the SNP pattern. These data will be useful for accurate genetic monitoring of genetically engineered mice with the C57BL/6 background.

A serious clinical course of a very elderly patient with takotsubo cardiomyopathy.

An 86-year-old woman was admitted to our hospital because of vomiting and anorexia. Although serum cardiac markers, an electrocardiogram, and echocardiography suggested acute myocardial infarction, emergency cardiac catheterization revealed akinesis of the left ventricular apex without significant coronary artery stenosis. She was diagnosed as having takotsubo cardiomyopathy. The left ventricular dysfunction was considered transient and reversible but did not improve at all, contrary to our expectations. She died of worsening heart failure on day 14. We discuss this serious clinical course of a very elderly patient with takotsubo cardiomyopathy.

Ventricular septal perforation in a patient with takotsubo cardiomyopathy.

An 84-year-old woman was admitted with anorexia and because the serum cardiac markers, electrocardiogram and echocardiography suggested acute myocardial infarction she underwent emergency cardiac catheterization. Coronary angiography revealed no significant coronary artery stenosis, but left ventriculography revealed akinesis of the left ventricular apex with shunt flow to the right ventricle. The diagnosis was a rare case of takotsubo cardiomyopathy complicated by ventricular septal perforation. The patient died of cardiogenic shock on the day of admission day.

Catheter interventional therapy in an elderly patient with deep vein thrombosis and a brain tumor.

A 92-year-old woman with a brain tumor developed swelling of the left lower extremity. Venography showed considerable thrombi from the left common iliac vein to the femoral vein. Following implantation of a temporary inferior vena cava filter, catheter aspiration therapy and catheter-directed thrombolysis were performed. Venography after 3 days showed disappearance of the thrombi and an improvement in vein flow. A permanent inferior vena cava filter was implanted. Local intensive thrombectomy and thrombolysis by catheter together with a temporary inferior vena cava filter were effective treatments in this elderly patient with deep vein thrombosis.