Biomedical subjects
Akihiko Sasaki
Publications and source records attributed to Akihiko Sasaki.
Transition of nanostructure in DNA-cationic surfactant complexes with the added salt.
Nanostructures of complexes of DNA with single-chain surfactant of octadecyltrimethylammonium (OTA) and double-chain surfactant of didodecyldimethylammonium (DDA) in aqueous NaCl solution at concentration, Cs, from 0 to 500 mM were studied using small-angle-scattering techniques (SAXS). SAXS profiles of the DNA-OTA complex show two SAXS peaks with a spacing ratio of 1:3(1/2) in the solution at Cs below 150 mM and three peaks with a spacing ratio of 1:3(1/2):4(1/2) at Cs above 250 mM. Contents of Na+ and Cl- ions in the complexes evaluated from the atomic absorbance for Na+ and the potentiometry for Cl- revealed charge molar ratios of OTA/DNA = 1 and DDA/DNA = 1.25. Contents of Na+ and Cl- ions per ionic unit of DNA molecule in the DNA-OTA complex equilibrating with the solution at Cs below 100 mM were much less than 0.1, while they increased with NaCl concentration at Cs above 200 mM. The DNA-OTA complex in the solution at Cs above 260 mM exhibited an endothermic peak in the DSC measurements, and the others did not. On the basis of the experimental results, the salt concentration dependent nanostructures are discussed.
Risk factors for heatstroke among Japanese forestry workers.
We examined the risk factors for heatstroke among forestry workers in Japan during the summer. We distributed a questionnaire to 124 forestry workers to determine heatstroke symptoms, degree of sweating and hydration, as well as perceived hotness and amount of sunlight at work sites. Forty of the workers (32.3%) reported experiencing heatstroke symptoms. Thirteen and 21 of them reported such symptoms during July and August, respectively. Eleven workers experienced heatstroke at around 14:00; 5 and 4 developed symptoms at around 11:00 and 10:00, respectively. Groups with and without heatstroke symptoms significantly differed in terms of perceived hotness (p<0.05), sunlight (p<0.05), degree of sweating (p<0.01) and frequency of hydration (p<0.05) while working. Heatstroke symptoms developed in 60.6% of workers aged up to 50 yr, but in only 22.0% of those over the age of 51 (p<0.01). Multiple regression analysis selected the following key variables associated with the development of heatstroke symptoms (R(2)=0.236 and p=0.006): frequency of urination, hotness, BMI and years of forestry work (standard coefficients: +0.229, +0.194, +0.280 and -0.162, respectively). The results of the present study showed that one third of forestry workers developed some symptoms of early heatstroke during summer forestry work. Furthermore, the results indicate that a short duration of forestry service was one of the risk factors contributing to the onset of heatstroke, in addition to heat stress, loss of body water and electrolytes, and obesity.
Protonation-induced structural change of lyotropic liquid crystals in oley- and alkyldimethylamine oxides/water systems.
Lyotropic phase behavior of the nonionic and the half-ionized oleyldimethylamine oxide (OlDMAO)/water systems was investigated using polarized light microscopy, small-angle X-ray diffraction, and differential scanning calorimetry. Nonionic OlDMAO formed isotropic micellar solution, nematic, hexagonal, cubic, and lamellar liquid crystalline phases as the surfactant concentration increased. In contrast, half-ionized OlDMAO (i.e., 1:1 mixture of the nonionic and the protonated species) had a greater tendency to form bilayer structures, and the phase diagram became quite similar to those of double-chained ionic surfactants rather than single-chained ones, despite the introduction of positive charges to the nonionic one. The preference of the bilayer structures in the half-ionized OlDMAO was interpreted in terms of the dimers stabilized by the hydrogen bond between the nonionic and protonated species. For alkyldimethylamine oxides with a saturated hydrocarbon chain (CnDMAO, chain length: n = 14, 16, and 18), the phase sequence of lyotropic liquid crystals was hardly affected by the protonation, but an elongation of the cylinders of the hexagonal phase was observed for the half-ionized C14DMAO. Consequently, it can be considered that the dominant bilayer formation of the half-ionized OlDMAO is attributed to the combined effect of the hydrogen-bonded dimer formation and the cis-double-bond configuration of the alkyl chain.
[Deficiency of 11beta-hydroxysteroid dehydrogenase type 1].
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Circulating insulin-like growth factor-1 and insulin-like growth factor binding protein-3 are associated with early carotid atherosclerosis.
OBJECTIVE: Growth hormone (GH)-insulin-like growth factor (IGF)-1 axis regulates growth and survival of vascular cells and cardiomyocytes. The role of GH-IGF-1 axis in cardiovascular disease is controversial. METHODS AND RESULTS: We assessed the association of circulating levels of IGF-1 and IGF binding protein-3 (IGFBP-3) with early carotid atherosclerosis and atherosclerotic risk factors in 330 Japanese men (age 51.6+/-8.6 years, range 29 to 77, body mass index [BMI] 23.6+/-2.9 kg/m2). Intima-media thickness (IMT) of the common carotid artery was measured by ultrasound. Abdominal visceral adipose and subcutaneous adipose tissue area by computer-assisted tomographic scan were determined. Correlation coefficients were calculated by partial correlation analysis. BMI and plasma insulin showed positive associations with circulating IGF-1 and IGFBP-3. Subcutaneous adipose tissue was correlated with IGF-1. High-density lipoprotein cholesterol was inversely associated with IGF-1. Blood pressure, total cholesterol, triglyceride, and visceral adipose tissue were positively associated with IGFBP-3. IGF-1 and IGFBP-3 were associated with carotid IMT independent of age, BMI, blood pressure, and insulin. Insulin was associated with carotid IMT in univariate analysis. However, it was not correlated with carotid IMT in the multivariate analyses which included IGF-1 or IGFBP-3 as a covariate. CONCLUSIONS: Increased circulating IGF-1 and IGFBP-3 may be stimulators of atherosclerosis.
Changes in health habits of female shift workers.
This paper examines the effects of shift work on the lifestyles of female factory workers. As an indicator of healthy lifestyle habits, we used a scoring system (referred to below as the 'health score') based on Lester Breslow's health habits. The 'health score' of the women was higher than that of the men, but the shift workers' score was lower than that of the non-shift workers (p<0.01). In addition, the score of workers who had changed from non-shift work to double-shift work was remarkably low (p<0.01). These results suggest that, while the female shift workers manage to maintain relatively healthy lifestyles in comparison with the males, they have more difficulty maintaining these habits than do female workers who do not perform shift work. It can be concluded that, in addition to heightening women's consciousness of their own health, surrounding entities such as the work environment, the home, and the community in general need to pay due care to Japan's female shift workers.
Effect of shift work on mental state of factory workers.
This paper examines the effects of shift work on the mental state of factory workers. As an indicator of the workers' mental condition, the authors used a scoring system (referred to below as the 'depression tendency score') based on the SRQ-D investigative report. The depression tendency score of the men was higher among the shift worker group than among the regular day worker group (p < 0.01). The depression tendency score of the male back-to-back shift workers was higher than that of the male regular day workers among skilled workers (p < 0.05). Among the women, no notable difference in depression tendency score was observed between the regular day worker group and the shift worker group. However, the depression tendency score of the female two-shift workers was higher than that of the female regular day workers among skilled workers (p < 0.05). We conclude that the mental health of men is easily affected by back-to-back shift work and that of women is affected by two-shift work because of the difference in modern societal/home role between man and woman.
[Formaldehyde exposure levels and exposure control measures during an anatomy dissecting course].
The evaporation of formaldehyde from cadavers can produce high exposures among students and instructors. A possible causal role for formaldehyde has been considered likely for tumor of the nasopharynx and the nasal cavities in human beings. Due to this reason, Japan Ministry of Education, Culture, Sports, Science and Technology (MEXT) has set a guideline, which includes--decrease in gaseous formaldehyde in gross anatomy dissection laboratories and a guide to medical students about the toxicity of formaldehyde and protective method to avoid damages to skin, mucous, membrane, etc, in 2002. To understand what effective plans should be regarding the awareness of students about this notification, this study measured the gaseous formaldehyde concentrations in the anatomy dissection room and also analyzed the formaldehyde-related symptoms, and frequency of using protective measures. The study was conducted over a period of 3 months during the anatomy dissection exercise. We found that immediately after removing the cadavers' plastic covering, formaldehyde concentrations in the dissection room increased sharply. The concentration reached a peak point of 0.62 ppm after 10 minutes of starting of the class. This was much above the recommended level of 0.5 ppm set by Japan Society for Occupational Health. After 30 minutes of achieving the peak the formaldehyde level started decreasing gradually to a level of 0.11 ppm. Formaldehyde-related symptoms were observed in 59% of students. They had experienced symptoms of irritation of eyes, nose, throat, airways, skin, and headache during the course. Ocular discomfort was found significantly higher in the contact lenses users compared to the spectacle users or the normal eye sight group. Although, the guidelines about toxicity of formaldehyde and its protective measures to prevent damages to skin, mucous membrane etc. were informed to every student, only 52% of the students used both the mask containing activated carbon and the rubber gloves in every practical class without fail. Environmental Health Criteria 89 of International Program of Chemical Safety states, "It must be regarded that formaldehyde fluid is not absorbed directly into tissues through the skin". So the students may be allowed in some cases to touch the cadaver, treated by formaldehyde content fixative, by bare hands to understand the feel of certain organs and tissues. These results support that the rules of health supervision including necessity to use of protective measures, monitoring of indoor air formaldehyde etc. should be adhered by students and instructors in anatomy dissection room during the practical class.
[Suppression of rhinovirus infections with macrolide antibiotics].
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Effects of dietary treatment alone or diet with voglibose or glyburide on abdominal adipose tissue and metabolic abnormalities in patients with newly diagnosed type 2 diabetes.
UNLABELLED: OBJECTIVE; To examine the effects of diet and diet with voglibose or glyburide on abdominal adiposity and metabolic abnormalities in patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: A total of 36 Japanese patients with newly diagnosed type 2 diabetes (50.8 +/- 8.6 years of age, BMI 24.5 +/- 3.5 kg/m(2)) and 273 normal control subjects were studied. The patients were treated for 3 months with diet alone (30 kcal/kg per day) (n = 15), diet with voglibose (n = 12), or diet with glyburide (n = 9). They underwent 75-g oral glucose tolerance testing, assessment of insulin sensitivity (SI), and acute insulin response (AIR) with intravenous glucose tolerance testing based on the minimal model, and measurement of abdominal visceral adipose tissue area (VAT) and subcutaneous adipose tissue area (SAT) by computed tomography before and after treatment. RESULTS: The diabetic patients had comparable SAT but larger VAT than the control subjects. With a mean weight loss of 2-3 kg, VAT and SAT were decreased similarly in all treatment groups. The VAT-to-SAT ratio was decreased only in the voglibose group. Glycemic control and serum lipid profiles were improved in all groups. Changes in glycemic control after diet were closely correlated with changes in VAT but not with changes in SAT. SI and AIR were unchanged in the diet group but were improved in the voglibose and glyburide groups. CONCLUSIONS: In Japanese patients with newly diagnosed type 2 diabetes who were relatively lean but had excess VAT, diet with or without voglibose or glyburide effectively reduced VAT. Decrease in VAT was closely associated with improvement of glycemic control with diet. Additional use of voglibose or low-dose glyburide had no detrimental effects on abdominal adiposity and had beneficial effects on SI and AIR.
[Carbohydrate metabolism in glucocorticoid excess].
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[Diagnosis of effort angina pectoris at rest by first derivative electrocardiography].
OBJECTIVES: First derivative electrocardiography (FDECG) records the slope of the wave of the standard 12-lead electrocardiography (ECG) and enables quantification of ECG-T wave symmetry. This study investigated the usefulness of FDECG to diagnose effort angina pectoris in patients with chest pain. METHODS: All 62 patients who visited our hospital with exertional chest pain underwent FDECG at rest, and exercise electrocardiography or stress thallium scintigraphy. Patients with possible ischemic change underwent coronary angiography, and those with significant coronary artery stenosis (> or = 75% reduction) were classified as the angina pectoris group (23 subjects). The other patients (without ischemic change or without significant coronary artery stenosis) formed the non-angina pectoris group (39 subjects). The FDECG is a simple differential wave with two peaks. The first peak of the FDECG-T wave designated as the T1 wave and the second peak as the T2 wave. The heights (the T1 and T2 wave amplitude) and the T2/T1 ratio (T2 wave heights/T1 wave heights) were calculated in the two groups. RESULTS: The T2/T1 ratios in leads I, V3, V4, V5 and V6 were significantly (I, V3, V4: p < 0.01, V5: p < 0.0001, V6: p < 0.001) decreased in the angina pectoris group. Using the criterion of a T2/T1 ratio at the V5 lead of less than 1.30, FDECG could detect effort angina pectoris patients with 65% in sensitivity, 74% specificity and 71% accuracy. CONCLUSIONS: ECG-T waves in the angina pectoris group were symmetrical. T2/T1 ratio of the FDECG-T wave is a useful index to diagnose effort angina pectoris at rest.