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Biomedical subjects

M Miyakawa

Publications and source records attributed to M Miyakawa.

At least 37 records · Page 2Linked to original sources
PubMed1999

Serum leptin levels and bioelectrical impedance assessment of body composition in patients with Graves' disease and hypothyroidism.

We investigated whether thyroid status modulates serum leptin concentrations and body composition as determined by bioelectric impedance analysis (BIA). The percent body fat mass (%FM) in male Graves' disease was significantly lower than that in age- and sex- matched normal subjects, at the levels of 11.4+/-6.4% (mean+/-SD) vs 19.9+/-9.2% for men (n=12, P<0.05) but not for women (22.6+/-7.6% vs 24.9+/-13.1%, n=28). In contrast, in female hypothyroidism (n=11) %FM was significantly higher than that in normal subjects (32.9+/-11.5%, P<0.01). Among other body composition parameters, the percentage of body water (%BW), and lean body mass (LBM) were significantly lower in hypothyroid patients, and the ECM (extracellular mass)/BCM (body cell mass) ratio was significantly (P<0.0001) increased in Graves' disease which was the result of marked depletion of BCM with concomitant expansion of ECM. The serum leptin levels were significantly decreased in male Graves' patients (2.3+/-0.7 ng/ml, P<0.05), whereas in female Graves' patients (8.8+/-5.9 ng/ml) and patients with hypothyroidism (9.5+/-7.6 ng/ml), the levels were not different from those of normal controls matched for BMI or %FM. There was a positive correlation between serum leptin levels and %FM in female Graves' patients (r=0.635, P=0.001) and in hypothyroid patients (r=0.801, P=0.014) but not in male Graves patients. There was no significant relationship between serum leptin levels and thyroid hormones, TRAb, or TSAb. In euthyroid obese subjects there was a positive relationship between serum leptin levels and serum TSH levels (r=0.37, P<0.01). These results suggest that hyperthyroidism is characterized by the decreased fat mass and serum leptin levels in men, but female patients appear to be resistant to the effect of thyroid hormones. Together with previous reports, thyroid status has a minor role in the regulation of serum leptin levels.

Adult↗
PubMed1999

Interaction between leptin and growth hormone (GH)/IGF-I axis.

In order to identify the mutual interaction between GH and leptin, we studied the effect of GH on fatty Zucker rats. GH administration at a high dose (5.0 IU/kg) reduced % body fat after 7 days. The leptin mRNA level in subcutaneous fat tissue was not changed but that in epididymal fat tissue was decreased by an even lower dose of GH (1.5 IU/kg). IGF-I treatment (200 microg/kg/day) did not change the % body fat or leptin mRNA level. These observations suggest that GH directly interacts with visceral fat and reduces fat mass and leptin expression. We also measured serum leptin levels in patients. The levels in patients with acromegaly were significantly lower than those in normal subjects with the same amount of body fat, but serum IGF-I and urinary C peptide excretion rates were higher in the acromegalic. These observations also suggests that GH directly interacts with adipose tissue and reduces leptin expression. Next we investigated the direct action of leptin on GH release from the pituitary. Leptin pretreatment of pituitary cells in culture or rats in a fasted or fed condition did not change GRH induced GH secretion. As indicated also by other recent studies, leptin may increase GRH or decrease somatostatin secretion by the hypothalamus. Thus GH interacts with fat tissues and leptin may be a good marker of the interaction.

Acromegaly↗
PubMed1999

Effect of cytokines on production of insulin-like growth factor binding proteins (IGFBPs) from human fibroblasts in culture.

Bioactivity of Insulin-like growth factors (IGEs) are positively or negatively regulated by IGF binding proteins (IGFBPs). Like IGFs, production of IGFBPs are influenced by a number of hormonal factors. We studied the effects of cytokines on production of IGFBPs in human fibroblasts in culture. Both IL-1beta and TNF-alpha inhibited IGFBP-3 (42/38 KDa species) production in a concentration dependent manner judged by Western ligand blot. Expression of IGFBP-3 mRNA was also decreased by these cytokines. Moreover, the treatment with IL-1beta and TNF-alpha resulted in appearance of smaller mol weight (26 KDa) immunoreactive IGFBP-3 fragment(s) which lacked the ability to bind 125I-IGFs, indicating that these cytokines degrade IGFBP-3 via activation of proteases. Both IL-1beta and TNF-alpha decreased production of IGFBP-4, whereas they increased that of IGFBP-6, IL-6 had little effect on production of IGFBPs. Likewise, interferon-gamma failed to affect of production of IGFBPs except at high concentrations. The present data demonstrate that cytokines, especially IL-1beta and TNF-alpha are potent regulators of IGFBPs production and degradation. These cytokines may alter tissue uptake of IGFs and help to counteract the catabolic state induced by them.

Blotting, Western↗
PubMed1999

Growth hormone directly inhibits leptin gene expression in visceral fat tissue in fatty Zucker rats.

Growth hormone (GH) is known to interact with adipose tissue and to induce lipolysis. Adipocytes produce leptin which regulates appetite and energy expenditure. In order to elucidate the role of GH in leptin production, we studied the effect of GH on leptin gene expression and body fat in fatty Zucker rats, a model of obesity with resistance to both leptin and insulin. Recombinant human GH administered subcutaneously at 0.5 mg/kg per day (low dose) as well as at 1.65 mg/kg per day (high dose) reduced leptin mRNA levels in epididymal fat tissue but not in subcutaneous fat tissue after 7 days. GH administration only at the high dose reduced percentage body fat. Insulin-like growth factor-I infusion (200 microg/kg per day) did not change percentage body fat or leptin mRNA levels in epididymal fat. These observations suggest that GH directly interacts with adipose tissue and reduces leptin gene expression in visceral fat tissue.

Adipose Tissue↗
PubMed1999

Volume-weighted mean nuclear volume as a prognostic factor in renal cell carcinoma.

Volume-weighted mean nuclear volume (MNV) has been reported to have important prognostic value in many cancers. We investigated the prognostic value of MNV in patients with renal cell carcinoma (RCC). A retrospective study of the 155 patients with RCC treated by radical nephrectomy between 1976 and 1996 was conducted. MNV was evaluated in the surgical specimens using a stereologic technique. Univariate analyses by the log-rank test and then a multivariate analysis by the Cox proportional hazards model were performed to analyze the prognostic value of histopathologic parameters such as Robson stage, tumor-node-metastasis (TNM) classification, tumor grade, and MNV. There were significant correlations between MNV and Robson stage, TNM classification and tumor grade. Robson stage, TNM classification, tumor grade, and MNV were correlated significantly with disease-specific survival of RCC patients. There was no significant difference in disease-specific survival between patients with Grade 1 and Grade 2 tumors (94.8% of all patients), but MNV could predict the clinical outcome of these groups. MNV also was correlated significantly with disease-specific survival at all tumor stages. Multivariate analysis showed pT classification, M classification, tumor grade, and MNV to be independently associated with survival. These studies strongly suggest that MNV may provide new and useful information to accurately predict the prognosis of patients with RCC.

Adult↗
PubMed1999

[Laparoscopic nephropexy for symptomatic nephroptosis: a case report].

We present our clinical findings of laparoscopic nephropexy performed on a 32-year-old woman with symptomatic nephroptosis. Supine and erect excretory urography (DIP) revealed right renal descent of 2.5 vertebral bodies with hydronephrosis. Laparoscopic transperitoneal nephropexy was performed using nonabsorbable sutures, polyglactin net, hernial staplers and tissue adhesive. An upright DIP 1 month postoperatively revealed renal descent of only 1 vertebral body and no hydronephrosis. One year postoperatively, the patient is asymptomatic. A laparoscopic procedure, which is safe, effective and causes minimal morbidity, represents an excellent approach for repair of symptomatic nephroptosis.

Adult↗
PubMed1999

[Relationship of dietary habits pattern and body build of parents to child obesity].

Patterns of eating habits were analyzed to elucidate its relationship to the temporal change of body build from childhood through school age in subjects of the Toyama study. Survey questionnaires at the time of entrance to elementary school were used. Subjects were 6,452 (males 3,293, and females 3,159). Subjects were classified into 6 clusters among the males, 8 clusters among females based on the results of cluster analysis of eating habits. The cluster in males that preferred egg, milk, dairy products, fats, fish and shellfish, soybeans, fruits, green yellow vegetables indicated more frequent subjects whose BMI were less that 14. The cluster in girls that preferred fats indicated more frequent subjects whose BMI were more or equal to 18. The ANOVA showed significant relation of parental body build on their children. Even after grouping by parental body build, the cluster based on patterns of eating habits showed different frequencies of obese children. Preference for intake of milk indicated less frequent obese children among the similar parental body build for boys, while preference for intake of fats indicated more frequent obese children among a similar parental body build for girls. In conclusion, the obesity of a school child has a close relationship to parent's body build. However, the temporal changes of obesity were seen among eating habits clusters even if body builds of their parents are the same. It was shown that patterns of eating habit are important in school children's obesity development.

Body Mass Index↗
PubMed1998

Health risk assessment for diabetes mellitus based on longitudinal analysis of MHTS database.

This study was designed with a follow up of 16 years to provide the epidemiological model evaluating the risk of developing diabetes mellitus in Japan. A cohort of 2573 subjects (1851 males and 722 females) from a MHTS in Tokyo, who were nondiabetic (fasting blood glucose (FBS) less than 110 mg/dl) in the initial year, were selected. This cohort was followed every year to identify the occurrence of diabetes mellitus. Diabetes Mellitus was defined as fasting blood glucose over 110 mg/dl, or the initiation of diabetic therapy. We compared two prognosis groups (a normal group and a diabetic group) in terms of age, examination findings, and prevalence of health risks (lifestyle, stress, and working form). We also assessed family history of diabetes and past histories including hypertension, hypercholesterolemia, and hyperuricemia. After assessing each variable by univariate analysis (t-test, chi 2 test), we employed Cox's proportional hazards model analysis. We used stepwise model adopting risk factors. The diabetic group had significant differences compared to the normal group in age, BMI (body mass index), FBS, smoking, drinking, not eating breakfast, dairy intake, hypertension, hypercholesterolemia, hyperuricemia, and family history by univariate analysis. According to proportional hazards model analysis, FBS, age, family history, hypertension, smoking, and BMI were incorporated into significant risk factors for diabetes in males, and not eating breakfast, FBS, age, drinking, and hypertension were incorporated in females. Diabetes seemed to be related to fixed factors (age), or genetic factors (family history and FBS) in males. For females, lifestyle (not eating breakfast and drinking habit) seemed to play an important role. It will be worthwhile to assess the risks of developing diabetes mellitus by this epidemiological model.

Adolescent↗
PubMed1998

Effect of growth hormone (GH) on serum concentrations of leptin: study in patients with acromegaly and GH deficiency.

As leptin, an ob gene product, plays a pivotal role in the regulation of adiposity and energy homeostasis, the level of its expression is likely to fluctuate under various physiological, nutritional, and disease conditions. Reports regarding the effect of GH on serum leptin levels are inconsistent. We have measured serum leptin levels and correlated them with several variables in patients with acromegaly, patients with adult GH deficiency (GHD), and normal controls. In 116 normal subjects, the mean serum concentration of leptin was 5.0+/-2.8 (mean +/- SD) ng/mL in men (n = 42) and 10.7+/-7.3 ng/mL in women (n = 73), respectively. As reported previously, the leptin levels in women were significantly (P < 0.001) higher than in men, and there was a strong positive correlation between log-transformed serum leptin levels and percent body fat in simple regression analysis (in men: r = 0.606; P < 0.0001; in women: r = 0.707; P < 0.0001). In 36 acromegalic patients, the percent body fat mass was significantly lower than that in normal subjects, and the mean serum leptin level was 2.2+/-1.8 ng/mL in men (n = 18) and 3.6+/-2.5 ng/mL in women (n = 18). Analysis of covariance revealed that serum leptin levels in acromegalics were significantly lower than those in normal subjects after correcting percent body fat (P = 0.016 for men and P < 0001 for women). In male patients with GHD (n = 20), the mean percent body fat was significantly (P < 0.05) higher than that in age-matched controls, whereas the value in female GHD patients (n = 15) did not differ from that in age-matched controls. Serum leptin levels in GHD patients were 5.1+/-2.5 ng/mL in men and 11.5+/-8.1 ng/mL in women, which were not different from those in normal subjects adjusted for percent body fat mass. In multiple regression analysis models with log-transformed leptin as the dependent variable, gender, percent body fat (or body fat mass), and serum insulin-like growth factor I levels entered the equations at a statistically significant level. These data suggest that excess GH/insulin-like growth factor I reduces serum leptin levels by reducing body fat mass and/or by unknown mechanisms.

Acromegaly↗
PubMed1998

HRA model for hypercholesterolemia based on a longitudinal health database.

To evaluate the risk factors for hypercholesterolemia, we examined 4,371 subjects (3,207 males and 1,164 females) who received medical checkups more than twice at an AMHTS in Tokyo during the period from 1976 through 1991; and whose serum total cholesterol was under 250 mg/dl. The mean follow-up duration was 6.6 years. A self-registering questionnaire was administered at the time of the health checkup. The endpoint of this study was the onset of hypercholesterolemia when the level of serum total cholesterol was 250 mg/dl and over. We compared two prognosis groups (normal and hypercholesterol) in terms of age, examination findings and lifestyle. After assessing each variable, we employed Cox's proportional hazards model analysis to determine the factors related to the occurrence of hypercholesterolemia. According to proportional hazards model analysis, total cholesterol, triglyceride and smoking at the beginning, and hypertension during the observation period were selected in males; and total cholesterol at the beginning and age were selected in females to determine the factors related to the occurrence of hypercholesterolemia.

Adult↗
PubMed1998

[The effect of quality of life in Behçet disease patients on subjective life satisfaction].

The purpose of this study is to elucidate the relationships between subjective life satisfaction and the following 8 factors of quality of life: physical condition, daily living activities, working condition, economic status, social status, medical status, marriage status, mental status. One hundred and fifty-four male and 116 female Behçet patients in 13 medical facilities were analyzed in this study. Mantel-Haenszel's odds ratio method and stepwise logistic regression analysis were applied to evaluate the influence of quality of life on subjective life satisfaction in Behçet disease patients. Males had higher problem scores than females in the following: physical condition, daily living activities, working condition, economic status, social status, marriage status, mental status. With regard to the effect on subjective life satisfaction, physical condition, daily living activities, working phase, economic phase, social phase, marriage relations, mental phase showed significantly high odds ratio in male, while physical condition, working phase, economic phase, social phase, medical phase, marriage relations, mental phase showed significantly high odds ratios in females by Mantel-Haenzel age-adjusted method. Physical condition, daily living activities, working phase, economic phase, social phase, and mental phase showed significantly high odds ratios in males after adjusting for active disease symptom periods, while physical condition, working phase, economic phase, social phase, medical phase, marriage relations, mental phase showed significantly high odds ratio in females after adjusting for active disease symptom. By stepwise logistic regression analysis, working phase and mental phase in males, economic phase and mental phase in females were shown to be significant. Improvement of quality of life including mental phase and working phase appear to raise the life satisfaction in Behçet's disease patients.

Adult↗
PubMed1997

Oncostatin M: a new potent inhibitor of iodine metabolism inhibits thyroid peroxidase gene expression but not DNA synthesis in porcine thyroid cells in culture.

The functions of thyroid cells are regulated by a number of cytokines and growth factors in addition to TSH. Recent studies have revealed that several cytokines including interleukin (IL)-6 are involved in thyroid dysfunction. Oncostatin M (OSM) is a glycoprotein belonging to the same family of cytokines as IL-6, to which it is related by sequence and structural homology and the use of the signal-transducing receptor component gp130. We, therefore, studied the effect of OSM on iodide uptake and DNA synthesis by porcine thyroid cells in culture. OSM increased c-fos and c-jun mRNA levels but did not stimulate DNA synthesis. OSM inhibited iodide uptake stimulated by TSH; while IL-6 also inhibited iodide uptake, it was only about one-tenth as potent. IL-6 had about the same potency as OSM when it was added with soluble IL-6 receptor. OSM had no effect on cAMP production but inhibited iodide uptake stimulated by 8-bromo-cAMP and forskolin. These findings suggest that OSM exerts its inhibitory effects at the post-cAMP production step(s). OSM also inhibited thyroid peroxidase mRNA levels but had little effect on thyroglobulin mRNA levels. Investigations of the signal transduction system showed that gp130 and leukemia inhibitory factor (LIF) receptor beta subunit mRNA were detectable in porcine thyroid cells by reverse transcription (RT)-polymerase chain reaction (PCR). Together with the report that serum OSM and IL-6 concentrations are elevated to the same levels in patients with sepsis, these results suggest that OSM may contribute to the thyroid dysfunction in this condition.

Animals↗
PubMed1997

Increased concentration of vascular endothelial growth factor/vascular permeability factor in cyst fluid of enlarging and recurrent thyroid nodules.

Human thyrocytes produce vascular endothelial growth factor (VEGF), a potent angiogenic factor, also known as vascular permeability factor (VPF), which increases vascular permeability. Based on the assumption that VEGF/VPF is involved in fluid accumulation in thyroid cysts, we determined the VEGF/VPF concentration in cyst fluids of thyroid nodules from 79 patients. VEGF/VPF was found to be abundantly present in the cyst fluids (0.02-183 ng/mL). There was no significant difference of VEGF/VPF concentration in the cyst fluid obtained from thyroid adenoma or from adenomotous goiter with cystic degeneration. Immunoreactive VEGF/VPF in cyst fluid was eluted mainly at 45 kDa, and stimulated endothelial cell proliferation, which was partially blocked by anti-VEGF/VPF antibody. The VEGF/ VPF concentration in the cyst fluid obtained from patients who required repeated aspiration or underwent surgical resection because of recurrent accumulation (84.8 +/- 58.3 ng/mL, mean +/- SD, n = 18) was significantly higher than that in the cysts that regressed or disappeared after a single aspiration (4.3 +/- 4.4 ng/mL, n = 12, P < 0.001). These in vitro and clinical findings suggest that VEGF/VPF is at least partly involved in the accumulation of cyst fluid in thyroid nodules, and that a high VEGF/VPF concentration predicts rapid accumulation of the cyst fluid, possibly necessitating interventional treatment.

Adenoma↗
PubMed1997

[Evaluation of marble burying behavior: induced alteration of monoamine metabolism in mouse brain].

Evaluation of marble burying behavior (MBB) housing-induced alteration of monoamine metabolism in mouse brain was performed by measuring metabolite levels with HPLC-ECD. Isolated housing of mice, each in a cage (22 x 32 x 14 cm; sawdust, 1-mm diameter; 5 cm in thickness) with 15 evenly spaced glass marbles on the floor (2.5-cm diameter; control, without marbles) for 24-168 hr, 5-HIAA contents were decreased in three regions: the midbrain, thalamus and hypothalamus. 5-HT turnover was not inhibited except for in the hypothalamus due to the decreases of 5-HT in the other two regions. On the other hand, DOPAC content and DA turnover were decreased in four regions: striatum, midbrain, thalamus, hypothalamus. The decrease in hypothalamic monoamine neurons was observed notably after 72 hr of MBB housing. No alterations were observed in feeding, water-drinking, spontaneous locomotor activity, number of buried marbles, serum corticosterone and serum glucose concentrations during MBB keeping compared with the control mice. These results suggested that the isolated mouse housed in a cage with evenly spaced glass marbles for a long period may be a model animal for alteration of monoamine metabolism in brain regions without physical infringement.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Automatic head positioning system using PSD-equipped camera-based photostereometry and a 5-degree-of-freedom robotized chair: calibration and accuracy verification.

In measurements of jaw movements employing an X-ray television, the orientation of the patient's head must be normalized relative to the measuring device. To avoid interferring with natural jaw movements caused by using a positioning jig, we have developed an automatic head positioning system consisting of a head position sensor and a robotized chair. The position and orientation of the head is monitored by detecting the three-dimensional positions of four non-coplanar LED markers mounted on the head, by means of a set of two photoelectronic cameras. If they are incorrect, the head is moved into the required position, using a 5-degree-of-freedom robotized chair. To accomplish this accurately, the positional relations of system components must be determined precisely. This paper proposes a least-square technique of calibrating the relationship between the position sensor and the chair. Consequently, accurate positioning is achieved. Accuracy verification studies revealed that overall positioning errors lay within 2.42 mm and 1.28 degrees with respect to the position and orientation, respectively, if the markers are secured to the head support of the chair.

Biomechanical Phenomena↗
PubMed1997

Controllability of temporomandibular joint loading by coordinative activities of masticatory muscles: a two-dimensional static analysis.

Masticatory and bite forces, when applied to the teeth, generate tremendous compressive energy in the temporomandibular joint (TMJ). Excessive 'TMJ loading', if left untreated, deteriorates articular functions. Normally, it is controlled, to a certain extent, by stomatognathic means. In an attempt to clarify this control mechanism, we analyzed the relationship between TMJ loading and the activities of the masticatory muscles, by employing a static two-dimensional jaw model. This comprises two rigid bodies, the upper and lower jaws, including three dominant muscles, i.e. the masseter, the anterior portion of the temporalis and the lateral pterygoid. Static equilibrium analyses determined that TMJ loading can be minimized, under controlled bite conditions, by pointing the loading vector in a direction solely indicated by individual morphological factors, such as the position and orientation of the masseter and the temporalis. This theoretically optimum direction of TMJ loading was also anatomically acceptable, because the load is applied exactly to those portions of the articular disk and mandibular head that can most easily sustain it. Interestingly, this factor was absolutely independent of both the activities of the lateral pterygoid and the direction of bite force. Consequently. TMI loading can be minimized, by coordinating the activities of the masseter and the anterior portion of the temporalis.

Bite Force↗
PubMed1997

[Effectiveness of magnetic resonance angiography for mass screening of unruptured intracranial aneurysms].

Magnetic resonance angiography (MRA) is widely used in screening for unruptured intracranial aneurysm (UIA) in the prevention of onset of subarachnoid hemorrhage (SAH) in Japan. However, the clinical efficacy of mass screening of UIA using MRA has not been established. This study aims to establish the clinical efficacy of mass screening of UIA using MRA by decision-making. The decision tree is constructed simulating a flow of population (100,000 persons, aged 50-59) starting from the MRA screening until the final outcomes of quality adjusted life or death in ten years. In order to estimate the numerical values various parameters were used as follows, prevalence rate: 1%; sensitivity of MRA: 74%; specificity of MRA: 76%; death rate by intracranial angiography: 0.1%; rupture rate of UIA: 2%/year; death rate of SAH: 57%; and death rate for surgery for UIA: 0.0%. The following results were obtained: 1. The number of lives saved by the MRA screening was 760, while the number saved without MRA was 79. 2. The number of deaths in those receiving the MRA screening was 52, while the number of deaths without MRA was 104. 3. The level of quality adjusted life with the MRA screening was higher than that without MRA in all cases. In conclusion, mass screening of UIA using MRA appears to be effective.

Decision Making↗