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Biomedical subjects

T Onaya

Publications and source records attributed to T Onaya.

At least 91 records · Page 5Linked to original sources
PubMed1994

Effects of 1 alpha-hydroxyvitamin D3 on lumbar bone mineral density and vertebral fractures in patients with postmenopausal osteoporosis.

The effects of 1 alpha-hydroxyvitamin D3 [1 alpha(OH)D3] on bone mineral density, fracture incidence, and bone metabolism were evaluated by a double-blind, placebo-controlled study. Eighty postmenopausal osteoporotic Japanese women (71.9 +/- 7.3 years, mean +/- SD) were randomly assigned to 1 microgram of 1 alpha(OH)D3 daily or inactive placebo for 1 year. All patients were given supplemental calcium (300 mg of elemental calcium daily). Lumbar (L2-L4) bone mineral density (BMD) determined by dual energy X-ray absorptiometry increased 0.65% with 1 alpha(OH)D3 treatment and decreased 1.14% with placebo (P = 0.037). BMD in both the femoral neck and Ward's triangle did not yield any significant differences between the two groups, whereas trochanter BMD in the 1 alpha(OH)D3-treated group increased 4.20% and decreased 2.37% with placebo (P = 0.055). X-ray analysis demonstrated that new vertebral fractures occurred in two patients with 1 alpha(OH)D3 and in seven patients with placebo. The vertebral fracture rate in the treated group was significantly less (75/1000 patient years) than in the control group (277/1000 patient years; P = 0.029). Hypercalcemia (12.1 mg/100 ml) occurred in one patient receiving 1 alpha(OH)D3; however, the serum calcium level in this patient promptly decreased to the reference range after cessation of the treatment. There were no significant changes in serum creatinine level in either group. A significant increase in urinary excretion of calcium was found but there was no significant change in urinary excretion of hydroxyproline in the treated group. The serum level of bone-derived alkaline phosphatase activity significantly decreased by -26 +/- 26 (mU/ml) after the treatment (P = 0.003).(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMed1994

Variant forms of glucokinase gene in Japanese patients with late-onset type 2 diabetes.

We have applied the technique of single-strand conformation polymorphism analysis to detect mutations of the glucokinase gene in 50 Japanese patients with late-onset type 2 diabetes and in 50 normal Japanese subjects. Out of the 50 patients with late-onset type 2 diabetes, we observed three kinds of variant patterns: one in exon 1b, one in exon 4, and one in exon 5. The incidence of these patterns was one in exon 1b, two in exon 4 and one in exon 5. Direct sequencing of exon 1b and exon 5 revealed mutations in intron areas at the 12th nucleotide downstream from the 5' splice points in two cases. Direct sequencing of exon 4 revealed a heterozygous silent mutation, CCC[Pro]-->CCG[Pro] at codon 145. In contrast, 50 normal Japanese subjects showed no variant patterns in any exons. Our results showed that although 8% (4 out of 50) of Japanese patients with late-onset type 2 diabetes have variant forms of the glucokinase gene, none is expected to cause apparent qualitative changes in glucokinase. We think that the frequency of mutations of the glucokinase gene which could cause qualitative change is very low in Japanese patients with late-onset type 2 diabetes.

Base Sequence↗
PubMed1994

Disruption of the first extracellular loop of thyrotropin receptor prevents ligand binding.

In order to understand the function of the first extracellular loop of the human thyrotropin receptor (hTSHR), each of two peptides of nine amino acids was inserted into the first extracellular loop of hTSHR. hTSHR cDNA was subcloned into the eukaryotic expression vector, pRc/CMV (hTSHR/pRc/CMV). B-hTSHR/pRc/CMV, a mutant hTSHR cDNA which encodes a hydrophilic peptide insert (AGTTRRVAI) and C-hTSHR/pRc/CMV which encodes a hydrophobic peptide insert (ATVLVVPMI) between +486 Ileu and +487 Asp of hTSHR were transfected into Chinese hamster ovary cells to generate the B-1 and C-6 cell lines, respectively. Neither thyrotropin (TSH) nor thyroid stimulating antibody (TSAb) stimulated cAMP production by B-1 or C-6 cells. An 125I-TSH binding assay showed that neither cell line bound TSH. Our data demonstrated that these mutations impaired both TSH binding and cAMP production. This evidence suggests that the first extracellular loop of hTSHR may have a crucial role in the TSH- and TSAb-dependent signal transduction.

Animals↗
PubMed1994

The effect of prostaglandin E1.alpha CD on vibratory threshold determined with the SMV-5 vibrometer in patients with diabetic neuropathy.

We studied the effect of prostaglandin E1.alpha CD (PGE1) on diabetic peripheral neuropathy by evaluating subjective symptoms and vibration sensation using a new vibrometer (SMV-5). Patients with diabetic neuropathy (n = 38) were divided into three groups; group A received no drugs (control), group B was treated with 1500 micrograms/day of oral methyl vitamin B12 (VB12) for four weeks, and group C received 1.2 micrograms/kg/day PGE1 intravenously for four weeks. There was a close relationship between symptom scores and vibratory threshold (VT). The effect of PGE1 on subjective symptoms and VT were compared with those in groups A and B. Patients who received PGE1 showed a significant improvement rate in pain and hypesthesia compared to patients in groups A and B, and in numbness compared to group A. During the study period, there was no significant change in VT in groups A and B, whereas VT was significantly improved at styloid process (P < 0.05) and at medial malleolus (P < 0.001) in group C. Our results confirmed that PGE1 significantly improved both subjective symptoms and VT, indicating that PGE1 therapy may be useful in diabetic neuropathy.

Administration, Oral↗
PubMed1994

Change in bone mineral density in patients with hyperthyroidism after attainment of euthyroidism by dual energy X-ray absorptiometry.

Because of the previous controversial findings in studies of bone mineral density in patients with hyperthyroidism with older methodologies, we assessed bone mineral density in 15 Japanese patients with Graves' disease (8 males and 7 females) before and after treatment using dual energy X-ray absorptiometry (DEXA). Bone mineral density of the lumbar vertebrae and the femur, and thyroid function, and several metabolic parameters were measured before treatment and again after patients achieved a euthyroid state following treatment with methimazole for 4 to 20 months (mean 10.6 months). The bone mineral density of patients was calculated as the percentage of the mean value (%BMD) in an age- and sex-matched control group, and correlations between the changes in bone mineral density and metabolic parameters before and after treatment were investigated. The %BMD of vertebrae in patients with Graves' disease before treatment was 89.7% of that found in the normal population. When patients became euthyroid after treatment, %BMD increased significantly to 94.9%, although it still remained below the control level. TSH receptor antibody, osteocalcin, and alkaline phosphatase were elevated before treatment, but decreased significantly after treatment. The change between pre- and posttreatment TSH receptor antibody was negatively correlated with the change in bone mineral density. In conclusion, these findings suggest that bone mineral density is decreased in patients with Graves' disease and that successful treatment of hyperthyroidism results in a significant increase in bone mineral density within a short period of time. Furthermore, TSH receptor antibody is a useful marker of changes in bone metabolism in this group of patients.

Absorptiometry, Photon↗
PubMed1994

Treatment of malignancy-associated hypercalcemia with YM175, a new bisphosphonate: elevated threshold for parathyroid hormone secretion in hypercalcemic patients.

The effect of a new third generation bisphosphonate, YM175 (cycloheptylamino-methylene bisphosphonate), on serum calcium (Ca) and intact PTH levels was examined in 79 malignancy-associated hypercalcemia patients with serum Ca levels higher than 2.75 mmol/L. A single infusion of 2.5, 5, and 10 mg YM175 reduced serum Ca levels in a dose-dependent manner. YM175 was about 6 times more potent than 3-amino-hydroxypropylidene-1,1-bisphosphonate. Among 23 patients treated with 10 mg YM175, serum Ca decreased by more than 0.5 mmol/L in 20 patients and was normalized in 11 patients. Serum intact PTH was subnormal in all of these patients before treatment and remained subnormal in 12 patients (suppressed PTH group), but was elevated to normal or high levels after treatment in the remaining 11 patients (responsive PTH group). Serum Ca was significantly higher throughout the study period in the suppressed PTH group, and mean serum Ca at the nadir did not decrease below 2.90 mmol/L in this group. However, the rate or magnitude of reduction in serum Ca was not different in the two groups. Polynomial regression analysis revealed that the threshold of serum Ca for PTH secretion was elevated to 2.75 mmol/L in the responsive PTH group, whereas it was about the upper limit of normal when both groups were combined (2.59 mmol/L). Furthermore, in the responsive PTH group, the threshold for PTH secretion during the decreasing serum Ca phase (days 4 and 6) was higher than that during the increasing serum Ca phase (days 10 and 14). The changes in the threshold for PTH secretion were also observed in patients treated with lower doses of YM175. These results demonstrate that YM175 is one of the most potent currently available bisphosphonates, and that the threshold for PTH secretion is elevated in at least some malignancy-associated hypercalcemia patients. In addition, there appears to be a difference in the threshold for PTH secretion between the decreasing and increasing serum Ca phases similar to the previously reported hysteresis phenomenon.

Adult↗
PubMed1994

Isolation of a cDNA whose expression is markedly increased in malignantly transformed FRTL cells and neoplastic human thyroid tissues.

We have cloned a cDNA whose mRNA levels are increased in malignantly transformed rat thyroid FRTL cells (FRTL-Tc cells). We constructed a cDNA library from FRTL-Tc cells in lambda gt10 and screened the cDNAs by differential plaque filter hybridization. Twenty-five thousand clones were screened and one cDNA (C140) was selected which corresponded to a mRNA whose expression was 5.8 times higher in FRTL-Tc cells than in FRTL cells. A 0.8 kb specific C140 mRNA was detected by Northern blot analysis of FRTL-Tc and FRTL mRNAs. The C140 cDNA was sequenced and found to encode a protein of 227 amino acids. We have found that C140 mRNA is conserved in human thyroid cells, but it is encoded by a smaller 0.7 kb transcript. C140 mRNA was highly expressed in neoplastic thyroid tissues and weakly in normal thyroid tissues in the same patients. Additionally, we found that C140 mRNA was also increased in the thyroid tissue of a patient with Graves' disease. These results suggest that C140 expression might be higher in rapidly growing thyroid cells than in normal cells, and might provide a new aspect for the study of thyroid tumours.

Amino Acid Sequence↗
PubMed1994

Desensitization and internalization of a thyrotrophin receptor lacking the cytoplasmic carboxy-terminal region.

To understand the functional significance of the carboxy-terminal half of the intracellular region of the human TSH receptor (hTSHR), a mutant hTSHR lacking amino acids from the carboxy-terminal to His726 was constructed. Wild type hTSHR cDNA and truncated hTSHR cDNA were subcloned into a eukaryotic expression vector, pRc/CMV, and transfected into Chinese hamster ovary cells to obtain cell lines which stably expressed hTSHRs at high levels. This allowed us to observe highly efficient coupling of hTSHR and adenylyl cyclase as well as desensitization and internalization of hTSHR. Despite the differences in potential phosphorylation sites and internalization signals, dose-dependent stimulation of adenylyl cyclase by TSH, TSH-dependent desensitization and the rate of hTSHR internalization were similar for wild type and truncated hTSHRs. We conclude that the carboxy-terminal half of the intracellular region of hTSHR does not have a major functional role in TSH-dependent signal transduction.

Amino Acid Sequence↗
PubMed1994

[Thyroid stimulating activity of human TSH-R peptide antibody].

We have synthesized a TSH-R peptide (N-peptide) corresponding to the unique N-terminal segment (#29-57) and immunized it into rabbits. We found that the N-peptide antibody possessed thyroid stimulating antibody (TSAb) activity but lacked TSH-binding inhibitor immunoglobulin (TBII) activity. We then produced rabbit antibodies against the peptides corresponding to the mid-region (#172-202, C-peptide), the region near the transmembrane domain (#341-370, P-peptide), and the extracellular loops (#648-662, E1-peptide; #561-580, E2-peptide; #648-662, E3-peptide). All these peptide-antibodies showed also TSAb activities. These results suggest that the domains responsible for TSAb might span the entire extracellular components of the receptor and that even the extracellular loops are the candidates for the epitope against autoantibodies from Graves' patients.

Animals↗
PubMed1994

[Thyrotropin receptor peptide antibody with thyroid stimulating activity induces an experimental hyperthyroidism in rabbits].

It has been presumed that N-terminal region of the TSH-R is important for TSH or TSH-R autoantibody binding to the receptor. We have synthesized human TSH-R peptide corresponding to the N-terminus of the extracellular domain, and immunized it into 8 rabbits. All these rabbits produced antibody against the peptide. Seven out of 8 antibodies showed thyroid stimulating antibody (TSAb) activity. We found that T3 and T4 concentrations in the sera of the immunized rabbits were significantly higher than those of the pre-immune sera, and increased time-dependently. These results suggest that anti-TSH-R peptide antibody with TSAb activity induced an increase in thyroid hormones in rabbits.

Animals↗
PubMed1994

[Thyrotropin receptor is expressed in non-thyroid tissues].

We have obtained TSH-R cDNA fragments from rat retro-orbital tissues and adipose tissue as well as FRTL5 cells by polymerase chain reaction methods. Nucleotide sequence of the non-thyroid cDNA was identical to that of the thyroid. Northern blot analysis has revealed that extremely high amount of TSH-R mRNA exist in the adipose tissue. TSH-R peptide antibody produced in rabbit, which stained recombinant TSH-R as 104 and 100 kDa proteins, also recognized the same M.W. bands in the adipose tissue and the retro-orbital tissues. These results suggest that TSH-R is expressed even in non-thyroid tissues.

Adipose Tissue↗
PubMed1993

Recombinant thyrotropin stimulates cAMP formation in CHO-K1 cells expressing recombinant chorionic gonadotropin receptor.

Using CHO-K1 cells expressing rat thyrotropin-receptor (CHO-rTSH-R cells) or rat chorionic gonadotropin-receptor (CHO-rCG-R cells), we have examined their reactivity or cross-reactivity to recombinant human thyrotropin (TSH) or human chorionic gonadotropin (hCG). TSH stimulated cAMP formation in CHO-rTSH-R cells dose-dependently, and the maximum response was obtained at 1 mIU/ml. hCG also increased cAMP in the cells from 10(4) mIU/ml, and the maximum stimulation was observed at 10(6) mIU/ml. 10(7) mIU of hCG had the same potency with 1 mIU of TSH to rTSH-R. On the other hand, 10(-1) mIU/ml of hCG increased cAMP content in CHO-rCG-R cells and reached the maximum level at 10(2) mIU/ml. TSH also showed the stimulatory activity to CHO-rCG-R cells. It increased cAMP formation in CHO-rCG-R cells dose-dependently from 10 mIU/ml to 10(3) mIU/ml. Thirty mIU of TSH was calculated to be equivalent to 1 mIU of hCG to CG-R. These results indicate that TSH and hCG cross-react each other with rTSH-R or rCG-R.

Animals↗
PubMed1993

Inositol 1,4,5-trisphosphate 3-kinase highest levels in the dendritic spines of cerebellar Purkinje cells and hippocampal CA1 pyramidal cells. A pre- and post-embedding immunoelectron microscopic study.

Inositol 1,4,5-trisphosphate 3-kinase (InsP3 3-kinase) plays a crucial role in calcium homeostasis by regulating InsP3 levels. We have reported the highest concentrations of InsP3 3-kinase in the dendrites of cerebellar Purkinje cells and hippocampal pyramidal cells of the CA1 sector of the Ammon's horn. We here investigate its subcellular localization by pre- and post-embedding immunoelectron microscopic study. In both populations of neurons, the major structure expressing a high level of InsP3 3-kinase is the dendritic spines.

Animals↗
PubMed1993

Thyrotropin receptor in non-thyroid tissues.

Thyrotropin receptor (TSH-R), the main target for the autoantibody in Graves' disease, has been thought to be a thyroid-specific protein. However, we successfully obtained the cDNA fragments of TSH-R from rat retro-orbital tissues and adipose tissues by using polymerase chain reaction methods. Sequencing has revealed that the nucleotide sequence of the cDNAs from these non-thyroid tissues was identical to that from the thyroid. TSH-R peptide antibody, which recognizes rat TSH-R, stained a 104 kDa protein from the retro-orbital tissues and the adipose tissues. The band was not detected with the antibody preabsorbed with the peptide. These results suggest that the message is translated to make a TSH-R protein even in these non-thyroid tissues.

Animals↗
PubMed1993

Bone mineral density measured by dual energy x-ray absorptiometry in patients with non-insulin-dependent diabetes mellitus.

Because of the previous controversial findings in diabetic patients with older methodologies, we assessed bone mineral density (BMD) in 78 patients (38 males and 40 females) with non-insulin-dependent diabetes mellitus using dual energy x-ray absorptiometry (DEXA). BMD was measured in lumbar vertebrae (L2-4). The BMD of each patient was calculated as the percentage of the mean value (%BMD) obtained from a healthy control group matched for sex and age. The %BMD of the patients with diabetes was about 100% for females and 96% for males, as compared with BMD of normal controls. The %BMD of the patients with diabetes was significantly correlated with body mass index and urinary C peptide level, and inversely correlated with age and duration of diabetes within 20 years. No relationships were found between %BMD and serum calcium, phosphorus, or glycosylated hemoglobin A1C levels. These observations suggest that metabolic abnormalities associated with diabetes mellitus alter the BMD, and that such factors as duration of the disease and deficit in insulin secretion are risk factors for decreased BMD.

Absorptiometry, Photon↗
PubMed1993

Bone mineral density in patients with hyperthyroidism measured by dual energy X-ray absorptiometry.

OBJECTIVE: We assessed the changes of bone mass in patients with hyperthyroidism by measuring bone mineral density using a new method, dual energy X-ray absorptiometry. DESIGN: The values of bone mineral density in patients with hyperthyroidism were compared with data obtained from the controls, and we assessed the correlation analysis between bone mineral density and several metabolic parameters. PATIENTS: We studied 52 Japanese patients with hyperthyroidism (20 males, 32 females). Healthy normal subjects served to establish the mean bone mineral density in the healthy Japanese population (Shiraki et al. 1991). MEASUREMENT: Bone mineral density was assessed by the measurement of lumbar vertebrae and femur by dual energy X-ray absorptiometry. The bone mineral density of vertebrae for each patient was calculated as the percentage of the mean value (% bone mineral density) obtained from an age and sex-matched control group. Blood was drawn to measure the levels of serum calcium, phosphorus, creatinine, alkaline phosphatase, free T3, free T4, TSH, TSH receptor antibody, parathyroid hormone, and serum osteocalcin. RESULTS: The percentage bone mineral density of vertebrae in patients was 92.6 as compared with that of normal controls, and was inversely correlated with serum TSH receptor antibody, osteocalcin, and alkaline phosphatase. CONCLUSIONS: These findings suggest that bone mineral density is decreased in patients with hyperthyroidism and that TSH receptor antibody, osteocalcin, and alkaline phosphatase are sensitive markers of bone metabolism alterations in hyperthyroidism.

Absorptiometry, Photon↗
PubMed1993

Cyclic adenosine 3',5'-monophosphate enhances sodium, potassium-adenosine triphosphatase activity in the sciatic nerve of streptozotocin-induced diabetic rats.

We have investigated the relationship between cAMP and sodium,potassium-ATPase (Na+,K(+)-ATPase) activity in the sciatic nerves of rats treated with cilostazol, a potent phosphodiesterase inhibitor; iloprost, a stable prostacyclin analog; or (Bu)2cAMP, a cAMP analog, which increase cAMP content by different mechanisms. In in vivo studies, administration of cilostazol (20 mg/kg BW.day), iloprost (4 micrograms/kg BW.day), or (Bu)2cAMP (4 mg/kg BW.day) for 4 weeks restored decreased cAMP content and Na+,K(+)-ATPase activity in the sciatic nerves of diabetic rats and further improved motor nerve conduction velocities without alteration of myo-inositol contents. There was a positive correlation between cAMP contents and Na+,K(+)-ATPase activities in the sciatic nerves. In in vitro experiments, cAMP accumulation and Na+,K(+)-ATPase activity in the desheathed sciatic nerve blocks obtained from both normal and diabetic rats were significantly increased by incubation with cilostazol, iloprost, or (Bu)2cAMP. In addition, cAMP accumulation and Na+,K(+)-ATPase activities in endoneurial preparations incubated in both normal and high glucose buffer were also significantly increased by cilostazol, iloprost, and (Bu)2cAMP. These results strongly suggest that there is a close relationship between cAMP content and Na+,K(+)-ATPase activity in rat sciatic nerves. Therefore, cAMP content may play an important role in the development of diabetic neuropathy by modulating Na+,K(+)-ATPase activity in the peripheral nerves.

1-Methyl-3-isobutylxanthine↗