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Biomedical subjects

Shoichiro Nagasaka

Publications and source records attributed to Shoichiro Nagasaka.

13 recordsLinked to original sources
PubMed2003

Porphyromonas gingivalis infection is associated with carotid atherosclerosis in non-obese Japanese type 2 diabetic patients.

The aim of the present study was to investigate whether non-obese Japanese type 2 diabetic patients with porphyromonas gingivalis infection have atherosclerotic vascular diseases. A total of 134 non-obese Japanese type 2 diabetic patients (96 men and 38 women, aged 36 to 84 years, body mass index [BMI] 20.1 to 26.9 kg/m(2)) were studied. In conjunction with BMI, glycosylated hemoglobin (HbA(1c)), fasting glucose, and serum lipids (triglycerides, total cholesterol, high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol) were measured. LDL cholesterol was calculated using the Friedewald formula. Using high-resolution B-mode ultrasound scan, we measured intimal medial thickness (IMT) in plaque-free segments of bilateral common carotid arteries, and the mean of IMT in 2 vessels was used for the analysis. Furthermore, we calculated the degree of stenosis in plaque segments of bilateral common carotid arteries. The degree of carotid atherosclerosis was expressed as a percentage ratio between the area of plaque and that of the lumen using the formula (Lumen Area Residual - Lumen Area)/Lumem Area x 100. Both the areas were automatically measured by the system on a frozen transverse scanning plane at the site of maximal narrowing. When 2 or more plaques were present in the vessel, only that causing the greatest degree of stenosis was considered for analysis. Values represent mean+/-SEM unless otherwise stated. Immunoglobulin G (IgG) titer against porphyromonas gingivalis was 245 +/- 65 (mean +/- 2 SD) in nondiabetic healthy subjects. In contrast, there was a wide variation in IgG titer against porphyromonas gingivalis in type 2 diabetic patients studied (range, 16 to 26,800). Thus, we classified our type 2 diabetic patients into 2 subpopulations according to the value of mean +/- 2 SD (= 310) of nondiabetic healthy subjects: one with high IgG titer against porphyromonas gingivalis (>310) (1,422 +/- 408) and the other with normal IgG titer against porphyromonas gingivalis (<310) (152 +/- 10, P =.002). The populations did not differ with respect to age, sex, BMI, fasting glucose, HbA(1c), serum triglycerides, total, HDL, and LDL cholesterol levels. Although the mean IMT in plaque-free segments was not different between the 2 groups (0.73 +/-0.03 v 0.68 +/- 0.02 mm, P =.098), the degree of stenosis in plaque segments was significantly higher in the high IgG titer group (12.0% +/- 2.2%) than in normal one (5.5% +/- 1.4%, P =.009). From these results, it can be concluded that porphyromonas gingivalis infection, although still a subclinical infection, is associated with atherosclerotic vascular disease in non-obese Japanese type 2 diabetic patients.

Adult↗
PubMed2003

Relationship between exercise training-induced increase in insulin sensitivity and adiponectinemia in healthy men.

Circulating concentrations of adiponectin, an adipocyte-derived protein, are increased by thiazolidinediones and by weight reduction, accompanied with improvement in insulin sensitivity. The effect of exercise training, another therapy to increase insulin sensitivity (SI), on adiponectinemia is currently unclear. The present study was undertaken to clarify whether exercise training-induced increase in SI is related to changes in adiponectinemia in healthy men. Twelve healthy non-obese men underwent ergometer training at lactate threshold (LT) intensity for 60 min/day for 5 days/week for 6 weeks. An insulin-modified intravenous glucose tolerance test was performed before and at 16 h and 1 week after the last training session to determine SI using a minimal-model approach. Serum levels of adiponectin were determined at the same time. After the exercise training, VO2max and LT were significantly increased by 7.2% and 22.3% (P<0.01), while BMI and body fat mass remained unchanged. SI was significantly increased at 16 h after the last training session (from 7.0 +/- 3.1 to 9.6 +/- 3.6 [x 10(-4) x (microU/ml)(-1) x min(-1)], P<0.01), but returned toward the basal levels at 1 week after the cessation of the training. Serum adiponectin concentrations before the training (20.9 +/- 7.4 microg/ml) were positively correlated with SI. The concentrations were slightly but significantly decreased at 16 h (17.2 +/- 6.6 microg/ml, P<0.05), and returned to the basal values at 1 week after the training. From these results, it can be concluded that exercise training-induced increase in SI is not dependent on the increase in adiponectinemia in healthy men.

Adiponectin↗
PubMed2003

Close association of severe hyponatremia with exaggerated release of arginine vasopressin in elderly subjects with secondary adrenal insufficiency.

OBJECTIVE: Hyponatremia occurs not infrequently in hypopituitarism. Arginine vasopressin (AVP)-induced impaired water excretion is found in patients with hypopituitarism and experimental models of glucocorticoid deficiency. DESIGN: The present study was undertaken to determine whether augmented release of AVP is involved in the development of hyponatremia in elderly subjects with secondary adrenal insufficiency. METHODS: Forty patients with ACTH-deficient, secondary adrenal insufficiency were examined. They were divided into three groups according to the age at which diagnosis was ascertained (group A <20 Years, group B 20-64 Years, and group C>or=65 Years). RESULTS: Hyponatremia was more manifest in the elderly group than in the other two groups, serum sodium (Na) levels being 124.7 mmol/l in the elderly group, a value significantly less than 141.5 and 133.5 mmol/l in groups A and B. Plasma AVP levels seemed likely to be high compared with the respective hypo-osmolality in plasma in the elderly group, as plasma AVP levels were 1.7 pmol/l despite a mean plasma osmolality of 259 mmol/kg. Such an alteration was less clear in group B and was not found in group A. Therefore, elevation of plasma AVP was apparent in the elderly patients. Hydrocortisone replacement promptly normalized serum Na levels from 125 to 142 mmol/l (P<0.01) and reduced plasma AVP levels from 1.7 to 0.9 pmol/l (P<0.05), which were comparable to the respective plasma osmolality in the elderly patients. CONCLUSION: These results indicate that non-suppressible release of AVP is crucially involved in the impaired water excretion and hyponatremia seen in elderly patients with secondary adrenal insufficiency compared with the younger patients, and that exaggerated release of AVP becomes manifest as the subjects grow older.

Adolescent↗
PubMed2002

Ultrasonographically assessed carotid atherosclerosis in Japanese type 2 diabetic patients: Role of nonesterified fatty acids.

The aim of the present study was to evaluate the association of carotid atherosclerosis (intimal-medial thickness [IMT] in plaque-free segments and carotid stenosis in plaque segments) with serum nonesterified fatty acids (NEFA) in diabetic and nondiabetic patients. Fifty-one nonobese nonhypertensive Japanese type 2 diabetic patients aged 38 to 83 years (60.0 +/- 1.5 years, mean +/- SEM) and 23 age-matched (60.4 +/- 2.2 years, P =.439; range, 36 to 74 years) and sex-matched nondiabetic subjects were examined. The duration of diabetes was 9.6 +/- 1.0 years. Body mass index (BMI), blood pressure (systolic pressure, diastolic pressure), glycosylated hemoglobin (HbA(1c)), and fasting concentrations of plasma glucose, serum lipids (triglycerides, total, and high-density lipoprotein [HDL] cholesterol, low-density lipoprotein [LDL] cholesterol) and serum NEFA were measured. Using high-resolution B-mode ultrasound scan, we measured IMT in plaque-free segments of bilateral common carotid arteries, and the mean of IMT in 2 vessels was used for the analysis. Furthermore, we calculated the degree of stenosis in plaque segments of bilateral common carotid arteries. The degree of carotid stenosis was expressed as a percentage ratio between the area of plaque and that of the lumen using the formula (Lumen Area - Residual Lumen) x 100. Both the areas were automatically measured by the system on a frozen transverse scanning plane at the site of maximal narrowing. When 2 or more plaques were present in the vessel, only that causing the greatest degree of stenosis was considered for analysis. Univariate regression analyses showed that mean IMT in plaque-free segments was positively correlated with age (r =.498, P =.0004) and NEFA (r =.354, P =.0188) in type 2 diabetic patients. The degree of stenosis was positively correlated to age (r =.422, P =.0028), duration of diabetes (r =.313, P =.0268) and NEFA (r =.540, P =.0003) in diabetic patients. Other variables, including BMI and lipid profile, were not associated both with mean IMT in plaque-free segments and the degree of stenosis in plaque segments in our diabetic patients. Multiple regression analyses showed that mean IMT in plaque-free segments was independently associated with age (P =.0003, F = 15.2), which explained 26.1% of the variability of IMT in our diabetic patients. The degree of stenosis was independently predicted by NEFA (P =.0047, F = 8.9), which explained 17.2% of the variability of the carotid stenosis in our diabetic patients. In contrast, mean IMT in plaque-free segments was positively correlated to age in nondiabetic subjects (r =.450, P =.0347). There was, however, no relationship between the degree of stenosis and the variables, including age and NEFA, in nondiabetic subjects. These results indicate that the factors contributing to IMT in plaque-free segments and the degree of carotid stenosis in plaque segments are different in nonobese nonhypertensive Japanese type 2 diabetic patients. IMT in plaque-free segments was independently associated with age both in nondiabetic and diabetic subjects, whereas the serum NEFA level independently predicted the degree of stenosis in plaque segments in our diabetic patients, while not in nondiabetic subjects. Thus, NEFA is considered to be one of the new risk factors responsible for the progression of carotid atherosclerosis in nonobese nonhypertensive Japanese type 2 diabetic patients.

Adult↗
PubMed2002

Relationship of regional adiposity to insulin resistance and serum triglyceride levels in nonobese Japanese type 2 diabetic patients.

The aim of this study was to investigate the relationships between insulin resistance and regional abdominal fat area, body mass index (BMI), and serum lipid profile in nonobese Japanese type 2 diabetic patients. A total of 63 nonobese Japanese type 2 diabetic patients aged 45 to 83 years were examined. The duration of diabetes was 8.4 +/- 0.8 years. BMI, glycosylated hemoglobin (HbA(1c)) levels, and fasting concentrations of plasma glucose, serum lipids (total cholesterol, high-density lipoprotein [HDL] cholesterol, and triglycerides), and serum insulin were measured. The low-density lipoprotein (LDL) cholesterol level was calculated using the Friedewald formula (LDL cholesterol = total cholesterol - HDL cholesterol - 1/5 triglycerides). Insulin resistance was estimated by the homeostasis model assessment (HOMA-IR). Computed tomography (CT) was used to measure cross-sectional abdominal subcutaneous and visceral fat areas in all the patients. Adipose tissue areas were determined at the umbilical level. Subcutaneous and visceral abdominal fat areas were 136.5 +/- 6.0 and 86.0 +/- 4.1 cm(2), respectively. Univariate regression analysis showed that insulin resistance was positively correlated with subcutaneous (r =.544, P <.001) and visceral (r =.408, P =.001) fat areas, BMI (r =.324, P =.009), HbA(1c) (r =.254, P =.001), serum triglycerides (r =.419, P <.001), and serum LDL cholesterol (r =.290, P =.019) levels and was negatively correlated with serum HDL cholesterol level (r =.254, P =.041). Multiple regression analyses showed that insulin resistance was independently predicted by the areas of subcutaneous (F = 6.76, P <.001) and visceral (F = 4.61, P <.001) abdominal fat and serum triglycerides (F = 8.88, P <.001) level, which explained 36.9% of the variability of insulin resistance. Moreover, the present study demonstrated that whereas BMI was positively correlated with visceral (r =.510, P <.001) and subcutaneous (r =.553, P <.001) fat areas, serum triglyceride level was positively associated with visceral (r =.302, P =.015), but not with subcutaneous (r =.222, P =.074) fat area. From these results, it can be suggested that (1) both subcutaneous and visceral abdominal fat areas are independently associated with insulin resistance and (2) visceral fat area, but not the subcutaneous one, is associated with serum triglyceride levels in our nonobese Japanese type 2 diabetic patients.

Adipose Tissue↗
PubMed2002

C-reactive protein and insulin resistance in non-obese Japanese type 2 diabetic patients.

The aim of the present study was to investigate the relationship between C-reactive protein (CRP) and insulin resistance in non-obese Japanese type 2 diabetic patients. A total of 135 non-obese Japanese type 2 diabetic patients (96 men and 39 women, aged 36 to 83 years, with a body mass index [BMI] of 16.2 to 26.8 kg/m2) were studied. BMI, glycosylated hemoglobin (HbA(1c)), fasting concentrations of plasma glucose, serum lipids (triglycerides, low-density lipoprotein [LDL] cholesterol, high-density lipoprotein [HDL] cholesterol, and total cholesterol), CRP, and fibrinogen were measured. LDL cholesterol was calculated using the Friedewald formula. Insulin resistance was estimated by the insulin resistance index of homeostasis model assessment (HOMA-IR). Univariate regression analysis showed that CRP value was positively correlated to age (r = 0.218, P =.012), BMI (r = 0.239, P =.006), HOMA-IR (r = 0.397, P <.0001), triglycerides (r= 0.310, P <.005), LDL cholesterol (r= 0.179, P =.038), and fibrinogen (r = 0.371, P <.0001) levels and inversely correlated to HDL cholesterol (r = 0.174, P =.044) level in our diabetic patients. Multiple regression analysis showed that CRP was independently predicted by HOMA-IR (P<.0001, F = 11.6) and fibrinogen (P<.0001, F = 34.2), which explained 23.5% of the variability of CRP in our non-obese Japanese type 2 diabetic patients. These results indicate that insulin resistance and fibrinogen level are independent predictors of CRP in non-obese Japanese type 2 diabetic patients.

Asian People↗
PubMed2002

S(G), S(I), and EGP of exercise-trained middle-aged men estimated by a two-compartment labeled minimal model.

To examine the effects of physical training on glucose effectiveness (S(G)), insulin sensitivity (S(I)), and endogenous glucose production (EGP) in middle-aged men, stable-labeled frequently sampled intravenous glucose tolerance tests (FSIGTT) were performed on 11 exercise-trained middle-aged men and 12 age-matched sedentary men. The time course of EGP during the FSIGTT was estimated by nonparametric stochastic deconvolution. Glucose uptake-specific indexes of glucose effectiveness (S(2*)(G) x 10(2): 0.81 +/- 0.08 vs. 0.60 +/- 0.05 dl. min(-1). kg(-1), P < 0.05) and insulin sensitivity [S(2*)(I) x 10(4): 24.59 +/- 2.98 vs. 11.89 +/- 2.36 dl. min(-1). (microU/ml)(-1). kg(-1), P < 0.01], which were analyzed using the two-compartment minimal model, were significantly greater in the trained group than in the sedentary group. Plasma clearance rate (PCR) of glucose was consistently greater in the trained men than in sedentary men throughout FSIGTT. Compared with sedentary controls, EGP of trained middle-aged men was higher before glucose load. The EGP of the two groups was similarly suppressed by approximately 70% within 10 min, followed by an additional suppression after insulin infusion. EGP returned to basal level at approximately 60 min in the trained men and at 100 min in the controls, followed by its overshoot, which was significantly greater in the trained men than in the controls. In addition, basal EGP was positively correlated with S(2*)(G) . The higher basal EGP and greater EGP overshoot in trained middle-aged men appear to compensate for the increased insulin-independent (S(2*)(G)) and -dependent (S(2*)(I)) glucose uptake to maintain glucose homeostasis.

Adult↗
PubMed2002

Urinary excretion of aquaporin-2 water channel in diabetic ketoacidosis.

We studied the changes in plasma arginine vasopressin (AVP) and urinary excretion of aquaporin-2 (UAQP-2) water channel in 3 patients with diabetic ketoacidosis. They had marked hyperglycemia of 27.9 +/- 2.8 mmol/l (mean +/- SEM), and elevated hemoglobin A1c of 8.8 +/- 1.4%. Circulatory blood volume was decreased by approximately 25%, which was determined by the changes in hematocrit. Plasma AVP levels were elevated to 10.3 +/- 3.0 pmol/l and UAQP-2, 578 +/- 200 fmol/mg creatinine (normal, 153 +/- 28) at the hospitalization. When hyperglycemia was improved by the intravenous infusion of a small dose of insulin plus fluid administration, both plasma AVP and UAQP-2 promptly decreased to 1.2 +/- 0.2 pmol/l and 252 +/- 29 fmol/mg creatinine on day 7, respectively. These alterations were concomitant with the recovery of circulatory blood volume. In the present study, UAQP-2, in addition to plasma AVP, indicates circulatory blood volume depletion, and the changes in UAQP-2 estimates the AVP-dependent recovery of circulatory blood volume during the therapeutic period in the patients with diabetic ketoacidosis.

Adult↗
PubMed2002

Decrease in urinary excretion of aquaporin-2 associated with impaired urinary concentrating ability in diabetic nephropathy.

Aquaporin-2 (AQP-2) is known to be expressed in the renal collecting duct cells and participates in urinary concentration in response to arginine vasopressin (AVP). The present study was undertaken to determine whether progression of renal dysfunction affects urinary excretion of AQP-2 in diabetic nephropathy. The study was composed of 8 control subjects and 14 patients with type 2 diabetes classified into two groups according to serum creatinine level (cut-off point; 1.5 mg/dl). After an 8-hour water deprivation, both urinary osmolality (U(osm)) and urinary excretion of AQP-2 significantly decreased in the diabetic patients with chronic renal failure as compared to the control subjects (p < 0.0001, p < 0.05, respectively). After a water load (10 ml/kg), no differences were found in plasma osmolality (P(osm)), AVP levels and U(osm), whereas urinary excretion of AQP-2 significantly decreased in the patients with chronic renal failure as compared to the control subjects (p < 0.05). These results indicate that the decreased urinary excretion of AQP-2 in diabetic nephropathy is due to the impaired cellular signaling of AVP in collecting duct cells, which may be partly involved in the urinary concentrating defect in renal failure.

Aquaporin 2↗