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Biomedical subjects

Y Iwamoto

Publications and source records attributed to Y Iwamoto.

At least 145 records · Page 8Linked to original sources
PubMed2000

Antibody-mediated insulin resistance treated by cessation of insulin administration.

A 45-year-old Japanese man was referred to our hospital because of hyperglycemia despite the administration of as much as 120 U/day of human insulin. He had no history of injecting animal insulin. Free insulin was below 5 microU/ml, but a high titer of total insulin (about 3,000 microU/ml) was observed, suggesting the presence of antibodies against human insulin. Scatchard analysis showed an increased insulin binding capacity in the plasma characterized by a higher affinity for insulin. He was successfully treated by cessation of insulin administration. A Scatchard analysis series showed that a reduction in the insulin binding capacity of antibodies paralleled the improvement in glycemic control.

Blood Glucose↗
PubMed2000

beta-cell transcription factors and diabetes: no evidence for diabetes-associated mutations in the gene encoding the basic helix-loop-helix transcription factor neurogenic differentiation 4 (NEUROD4) in Japanese patients with MODY.

The basic helix-loop-helix (bHLH) family of transcription factors plays an important role in the normal development and function of the endocrine pancreas. Heterozygous mutations in the gene encoding one member of this family, NeuroD1/BETA2, are associated with a monogenic form of diabetes that resembles maturity-onset diabetes of the young (MODY) in many respects. This result prompted us to screen the genes encoding related bHLH transcription factors that are also expressed in pancreatic islets for diabetes-associated mutations. We have screened 57 unrelated Japanese subjects with a clinical diagnosis of MODY for mutations in the NeuroD4/Math-3/ATH-3 gene (NEUROD4). This analysis revealed seven frequent polymorphisms that were not associated with MODY, including five in the 5'-untranslated region (UTR) (-477G/A, -436delA, -324delT, -107insTTTT, and -104T/C [cDNA sequences]) and two in the 3'-UTR (1027C/T and 1076C/A). A missense mutation, K68T (203A/C), was found in a heterozygous state in one MODY subject and two nondiabetic subjects. The results of our study suggest that genetic variation in NEUROD4 is not a common cause of MODY in Japanese.

Basic Helix-Loop-Helix Proteins↗
PubMed2000

Beta-cell transcription factors and diabetes: no evidence for diabetes-associated mutations in the hepatocyte nuclear factor-3beta gene (HNF3B) in Japanese patients with maturity-onset diabetes of the young.

Mutations in the transcription factors hepatocyte nuclear factor (HNF)-4alpha and -1alpha, insulin promoter factor-1, and HNF-1beta are the causes of four forms of maturity-onset diabetes of the young (MODY1 and 3-5, respectively). The winged-helix transcription factor HNF-3beta has been implicated in the regulation of expression of each of these MODY genes, suggesting that mutations in the HNF-3beta gene (HNF3B) may also cause MODY. We have tested this hypothesis by screening a panel of 57 unrelated Japanese subjects with a clinical diagnosis of MODY for mutations in HNF3B. This analysis revealed four frequent polymorphisms that were not associated with MODY, including one in the promoter region (-213A/G), two silent mutations in the codons for Ala 97 (291C/T) and Gly 279 (837A/G), and one in the 3'-untranslated region (1424C/T). Two rare substitutions in the 5'-untranslated region, -156C/T and -67A/C, were found in a heterozygous state in two subjects, and two subjects were heterozygous for putative missense mutations, S109N (326G > A) and A328V (983C>T). The two missense mutations were not found in 106 normal chromosomes from nondiabetic subjects. It was not possible to test for co-segregation of these mutations with diabetes and thus, it is unclear whether or not these mutations can cause MODY. The results of our study suggest that mutations in HNF3B are not a common cause of MODY in Japanese subjects.

Adult↗
PubMed2000

Association of postprandial hypertriglyceridemia and carotid intima-media thickness in patients with type 2 diabetes.

OBJECTIVE: Serum triglyceride levels are important in the development of atherosclerosis. Although triglyceride levels are generally increased in the postprandial periods, the association between postprandial triglyceride (pTG) levels and atherosclerosis has not been investigated in diabetic patients. To investigate the role of pTG levels in atherosclerosis, we examined the correlation between pTG levels and carotid intimal-medial thickness (IMT). RESEARCH DESIGN AND METHODS: Carotid IMT was measured by ultrasonography in 61 patients with type 2 diabetes. Plasma glucose (PG), insulin, total cholesterol, triglycerides, and HDL cholesterol levels were measured after overnight fasting and 4 h after a meal. RESULTS: Carotid IMT of the patients with fasting hypertriglyceridemia was greater than that of the patients with normal fasting triglyceride (fTG) levels (0.85+/-0.12 vs. 0.76+/-0.14 mm; P = 0.02). The carotid IMT was increased in the patients with pTG levels >2.27 mmol/l. The normo-normo (NN) and normo-hyper (NH) groups consisted of patients with normal fTG levels but with pTG levels <2.27 and >2.27 mmol/l, respectively. Patients with both hypertriglyceridemia and pTG levels >2.27 mmol/l formed the hyper-hyper (HH) group. Carotid IMT was significantly increased in the NH (0.86+/-0.13 mm) and HH (0.85+/-0.12 mm) groups compared with the NN group (0.73+/-0.13 mm; P<0.01). Although postprandial PG, pTG, and fasting LDL cholesterol levels were all independently correlated with carotid IMT, pTG levels had the strongest statistical influence (P = 0.002). CONCLUSIONS: Postprandial hypertriglyceridemia despite normal fTG levels may be an independent risk factor for early atherosclerosis in type 2 diabetes.

Adult↗
PubMed2000

[Insulin sensitizer and urate metabolism].

Gout patients often have various characteristics of insulin resistance (IR) syndrome such as glucose intolerance, hyperlipidemia, hypertension and obesity. In addition, epidemiological data suggest that hyperuricemia is associated with higher rates of death due to cardiovascular and cerebrovascular disorders. However, it has not conclusively been shown whether the association between hyperuricemia and increased death rate is secondary to the association between IR and death or hyperuricemia itself is an independent risk of death. It is of interest to examine the effects of insulin sensitizer which was developed recently on serum urate concentration because it may provide a new idea as to the mechanism of the association between IR, hyperuricemia and vascular disorders. In the present paper, we discuss the relevance of IR to hyperuricemia and gout, and show the data of urate and glucose metabolism obtained from control subjects or the patients with hyperuricemia, gout or type 2 diabetes.

Chromans↗
PubMed2000

[Troglitazone for treatment of polycystic ovary syndrome].

Polycystic ovary syndrome(PCOS) is characterized by clinical symptoms such as menstrual dysfunction, unovulatory infertility, masculinization, obesity, polycystic ovary by ultrasound, and endocrine abnormalities such as hyperandrogenism, and elevated LH to FSH ratio. Recent reports suggest that insulin resistance plays an important role in the pathogenesis of PCOS, and several insulin sensitizing agents have been used for the treatment of PCOS. Troglitazone, one of the thiazolidinediones, improves not only insulin sensitivity but also hyperandrogenism and ovulatory function. Troglitazone appears to be useful in treating women with PCOS. Further investigations are needed to assess the effectiveness and safety.

Chromans↗
PubMed2000

Negative effects of chronic inflammatory periodontal disease on diabetes mellitus.

Periodontal disease is the result of a complex interplay of bacterial infection and host responses, and is often modified by various systemic diseases such as diabetes mellitus. Such diseases are capable of affecting the periodontium and/or the treatment of periodontal disease. However, recent research has changed our concept of how periodontal disease should be treated. Here we present several concerns directed towards the periodontal therapy of patients with diabetes mellitus based on our studies. When treating periodontitis patients who have diabetes mellitus it is important to consider the type of diabetes. Patients with non-insulin dependent diabetes mellitus can be further classified according to the degree of insulin resistance, since recent epidemiological studies have suggested that successful anti-microbial therapy might result in improved insulin resistance in highly insulin resistant patients. Because the major contributing factor for insulin resistance is currently considered to be the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha), and because periodontal surgery may cause transient bacteremia which may up-regulate the serum TNF-alpha level, which in turn suppresses insulin action, patients should be strictly treated non-surgically and their serum TNF-alpha levels should be periodically monitored. On the other hand, diabetic patients positive for serum anti-glutamate decarboxylase auto-antibody should be examined for the source of this antibody, since 1) gingival and periodontal ligament fibroblasts were found to express glutamate decarboxylase, and 2) some otherwise healthy periodontitis patients develop anti-glutamate decarboxylase antibody. Thus, chronic periodontitis may influence the level of this antibody which is widely used as a predictive marker for slowly progressive insulin dependent diabetes mellitus. Not only is periodontal disease thereby affected by systemic diseases, but carefully managed periodontal therapy may also have a positive effect on the general health of patients with systemic diseases.

Anti-Bacterial Agents↗
PubMed1999

Börjeson-Forssman-Lehmann syndrome in a woman with skewed X-chromosome inactivation.

Börjeson-Forssman-Lehmann (BFL) syndrome is an X-linked recessive disorder characterized by minor facial anomalies, obesity, epilepsy, and severe mental retardation. The phenotype of male patients is usually severe, whereas that of carriers is less severe, suggesting X-linked incompletely recessive inheritance. A recent linkage study mapped the BFL syndrome gene to Xq26-q27. The etiology of the condition in female patients with full manifestations is not known, although nonrandom X-chromosome inactivation has been considered. We recently developed an assay for X-inactivation studies based on the methylation-specific polymerase chain reaction (PCR) technique. Using the methylation-specific PCR assay, a woman with typical findings of this syndrome was shown to have an extremely skewed X-inactivation pattern. This finding suggests that the full manifestations of the BFL syndrome in carriers may be caused by skewed X inactivation with a high proportion of cells in which the X chromosome with a normal gene be inactivated, leaving the X chromosome with a mutant gene active.

Adult↗
PubMed1999

Inhibitory effects of activin-A on osteoblast differentiation during cultures of fetal rat calvarial cells.

Activin-A is a member of the transforming growth factor-beta (TGF-beta) superfamily and is expressed by osteoblasts. However, the role of activin-A on osteoblasts is not clearly understood. We examined the effects of activin-A on osteoblast proliferation or differentiation, and mineralization by the osteoblasts in the first subcultures of fetal rat osteoblasts obtained from calvarial bones. Exogenous activin-A led to impaired formation of bone nodules in a dose-dependent manner, although it did not influence cell proliferation using an MTT assay. This inhibitory effect depended upon the time at which activin-A was added to the culture media, and the effect was most significant when addition took place at the early phase of the culture. In addition, exogenous activin-A inhibited gene expression of type I procollagen, alkaline phosphatase, osteonectin, and osteopontin in the cultured cells using Northern blot analysis. The peak of osteocalcin mRNA was delayed. Gene expression for TGF-beta was not influenced by exogenous activin-A. The betaA subunit (activin-A) mRNA was detected during the early phase of this culture. These results indicate that activin-A inhibited early differentiation of the fetal rat calvarial cells, or osteoblasts.

Activins↗
PubMed1999

Axonal trajectories of the nucleus reticularis gigantocellularis neurons in the C2-C3 segments in cats.

Axonal trajectories in the C2-C3 segments of the nucleus reticularis gigantocellularis neurons projecting to the lower cervical cord (C-RSNs) and excited monosynaptically from cortico- and tectofugal fibers were studied by mapping thresholds of antidromic excitation and intra-axonal staining in cats. The C-RSNs descended in various sites of the spinal funiculi, and the projection area of individual cells varied with the funicular location of the stem axon. C-RSNs descending in the ventrolateral funiculus (inRSNs) projected mainly to lamina VIII-IX, those descending in the lateral funiculus (IRSNs) mainly to laminae VI-VIII, and those descending in the contralateral funiculus (coRSNs) chiefly to laminae VIII-IX on that side. It is suggested that inRSNs and coRSNs mediate disynaptic effects from cortico- and tectofugal fibers to dorsal neck motoneurons bilaterally.

Animals↗
PubMed1999

Lymphangioma presenting as a dumbbell tumor in the epidural space of the lumbar spine.

STUDY DESIGN: A case report. OBJECTIVES: To report and discuss a case of lymphangioma presenting as a dumbbell-shaped tumor in the epidural space of the lumbar spine. SUMMARY OF BACKGROUND DATA: Dumbbell tumor of the spine is not uncommon. Although the pathogenesis of such tumors varies widely, lymphangioma has not been reported previously, to these authors' knowledge. METHODS: A 56-year-old woman with pain in the lower back and left leg was examined by plain radiographs and magnetic resonance imaging before surgery. Treatment consisted of the usual technique of surgical resection of the tumor. Histopathologic study of the resected material confirmed the diagnosis. Postoperative follow-up assessment was performed by magnetic resonance imaging. RESULTS: Magnetic resonance imaging demonstrated a dumbbell tumor in the epidural canal area of the lumbar spine. Histopathologic diagnosis of the resected tumor was cavernous lymphangioma. CONCLUSION: To the authors' knowledge, this is the first reported case of lymphangioma presenting as a spinal dumbbell tumor. Further observation is recommended because of the possibility of local recurrence.

Diagnosis, Differential↗
PubMed1999

Present state of dental health knowledge, attitudes/behaviour and perceived oral health of Japanese employees.

The aim of this survey was to assess the present state of dental health knowledge, attitudes/behaviour and perceived oral health of Japanese employees. A 60-item questionnaire was used in a dental health project in the work place. The subjects comprised 77,845 employees, 76 per cent of whom reported delaying a dental visit until they had toothache, with about 60 per cent delaying even when they discovered a decayed tooth. The majority did not regard decayed teeth as a disease and only a minority reported regular dental visits. About three quarters reported bleeding gums on brushing, although more than half had never been taught professionally how to clean their teeth and less than 5 per cent flossed daily. More than half believed that false teeth were inevitable in old age, and that their teeth were getting worse despite daily brushing. About 70 per cent of the employees thought that it was impossible to prevent gum disease with toothbrushing alone, and nearly half believed a toothpaste with fluoride was effective in preventing periodontal disease. Reorientation of oral health care in Japan, therefore, is urgently needed and dental services have to be provided for the implementation of systematic oral health promotion for employees in the workplace.

Adolescent↗
PubMed1999

Evaluation of blood flow within the subchondral bone of the femoral head: use of the laser speckle method at surgery for osteonecrosis.

The laser speckle method is a new form of tissue flowmetry that can analyze the interference pattern that appears when tissue is illuminated with a laser beam. During surgery for 100 cases of osteonecrosis of the femoral head, we measured the blood flow within the subchondral bone using this method. We compared the flow maps (two-dimensional distribution of the microcirculation) obtained this way with the necrotic area estimated by the preoperative magnetic resonance images and with the collapse seen during surgery. The laser speckle method was able to distinguish between the ischemic areas and the normal areas in 92 femoral heads, including five hips for which neither the magnetic resonance images nor the collapse observed during surgery demonstrated a distinct margin surrounding the necrotic area. We concluded that the laser speckle method is useful for defining the margin around a necrotic area.

Adult↗
PubMed1999

Assessment of subchondral bone blood flow in the rabbit femoral condyle using the laser speckle method.

The laser speckle method is a new form of flowmetry that can obtain a two-dimensional distribution of blood flow in tissue. This method is a noncontact, simple, and rapid technique that may aid in the diagnosis of osteonecrosis. We investigated whether the subchondral bone blood flow within the femoral condyles of rabbits could be measured by the laser speckle method. The hydrogen washout method was chosen as a comparison technique because of its ability to allow repetitive measurements of blood flow in various conditions in one rabbit and because of its reliability, which already has been established. We simultaneously measured the bone blood flow in 20 femoral condyles of 10 rabbits with the laser speckle and hydrogen washout methods and found a significant correlation between the blood flow levels with use of these two methods. For the clinical application of the laser speckle method, we also investigated the influence of cartilage thickness on the measurements and the depth in the bone to which blood flow could be measured with this method. A cartilage thickness of 0.2 mm did not influence the measurement of the bone blood flow, and the depth in the bone to which the laser speckle method could be used was approximately 2 mm.

Animals↗
PubMed1999

Inhibition of endochondral ossification during fracture repair in experimental hypothyroid rats.

Using a rat fracture model, we investigated the effects of a decrease in serum levels of thyroid hormone on the fracture-repair process. Rats were divided into the following groups: (a) controls, (b) those treated with methimazole for the duration of the experiment, and (c) those treated with methimazole and L-thyroxine, receiving both for the same duration. Three weeks after the initiation of pharmacologic treatment, closed femoral fractures were produced. The formation of cartilage tissue in the fracture callus in all rats was not obviously different on day 7 after fracture. In the rats treated with methimazole, differentiation from proliferating to hypertrophic chondrocytes in the fracture callus was less advanced and vascular invasion was clearly inhibited on day 12. Gene expression of alkaline phosphatase and osteocalcin in the callus was significantly lower in these rats than in the controls on days 10, 12, and 14. The mechanical properties of the fracture callus were also significantly weaker in these animals than in the controls on day 21, resulting in impaired fracture repair. These results demonstrate that hypothyroidism inhibits endochondral ossification, resulting in an impaired fracture-repair process. L-thyroxine replacement in the rats treated with methimazole caused the impaired repair process to revert to normal. These results indicate that thyroid hormone is one of the critical systemic factors for fracture repair.

Alkaline Phosphatase↗
PubMed1999

Radiological assessment of the position of the tibial tuberosity by means of a marking wire in knees with patellofemoral arthritis.

OBJECTIVE: To assess the usefulness of a new axial radiographic technique in knees with patellofemoral arthritis (PF-OA). DESIGN AND PATIENTS: After a marking wire had been attached to the skin on the tibial tuberosity so that the wire matched the width of the patellar tendon, an axial radiograph was taken at 30 degrees of flexion in 16 normal knees and 14 PF-OA knees in which computed tomographic analysis had revealed a laterally positioned tibial tuberosity at 30 degrees of flexion. The distance of the marking wire from the lateral condyle and from the patellar groove was compared between the two groups. RESULTS: The marking wire was located significantly laterally in PF-OA knees compared with normal knees. CONCLUSION: An axial radiograph with a marking wire on the tibial tuberosity is useful for assessing the position of the tibial tuberosity in PF-OA knees.

Aged↗