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Biomedical subjects

T Kuroda

Publications and source records attributed to T Kuroda.

At least 307 records · Page 17Linked to original sources
PubMed1992

New bronchodilators. II. 3H-imidazo[4,5-c]quinolin-4(5H)-ones.

A series of novel 3-substituted imidazo[4,5-c]quinolin-4(5H)-ones (2a-w) was prepared by the reaction of imidazo[4,5-c]quinolin-4(5H)-ones (6) with several electrophiles under basic conditions. The bronchodilatory activity of these compounds was evaluated on the basis of their protective effects against antigen-induced contraction (the Schultz-Dale reaction) of guinea-pig trachea (in vitro) and antigen inhalation-induced bronchospasm in passively sensitized guinea-pigs (in vivo). Although correlations between in vitro and in vivo activities were not clear, short alkyl chains such as the methyl and ethyl groups at the 3-position were important for potent activity, especially in vivo. Substituents at the 5-position were more tolerant of the activity than those at the 3-position. 5-Ethyl-3-methyl-3H-imidazo[4,5-c]quinolin-4(5H)-one (21) exhibits the most potent bronchodilatory activity among our tested compounds and is at least 5-fold more active than theophylline in vivo.

Animals↗
PubMed1992

Thyrotoxicosis with low serum total T3 level in patients with destructive thyroiditis and non-thyroidal illness.

The serum total T3 level, evaluated in 687 patients with thyrotoxicosis diagnosed by an elevated serum free T4 level and suppressed serum TSH level, was found to be high in 98.1% and normal in 1.9% of 592 patients with Graves' hyperthyroidism, and high in 75.8%, normal in 21.1% and low in 3.2% of 95 patients with destructive thyroiditis. Non-thyroidal illness was found in about a third of the patients with thyrotoxicosis and a normal serum total T3 level. The serum total T3 level was low with elevated serum thyroglobulin and reverse T3 levels in three patients with severe non-thyroidal illness, in whom the thyroidal radioactive iodine uptake was suppressed and the thyrotoxicosis resolved spontaneously with a normalization of the serum total T3 level after recovery from the destructive thyroiditis and non-thyroidal illness. It is therefore concluded that thyrotoxicosis with a low serum total T3 level, partially due to associated non-thyroidal illness, is more frequently found in patients with destructive thyroiditis than in those with Graves' hyperthyroidism.

Adult↗
PubMed1992

Reversible primary hypothyroidism and elevated serum iodine level in patients with renal dysfunction.

Recovery of thyroid function in patients with both thyroid and renal dysfunction was studied. Among 245 patients with primary hypothyroidism (serum TSH greater than 10 mU/l), 36 had mild to severe renal dysfunction (serum urea nitrogen greater than 7.1 mmol/l and creatinine greater than 106 mumol/l). Of these 36 patients, recovery of the thyroid function after iodine restriction was observed in 30 (83%), in whom an elevated serum non-hormonal iodine level (median 236, range 67-15,591 micrograms/l, N = 19) and a high thyroidal radioactive iodine uptake (51.5 +/- 29.3% at 24 h, N = 26) were observed. The perchlorate discharge test was positive in 7 of 13 patients examined, suggesting an iodide organification defect rather than an atrophic or destructive change in the thyroid. Antithyroid antibodies were negative in 22 patients (73%) and an almost normal thyroid gland or colloid goitre was confirmed histologically in 8 of them. After a 13.2 mg potassium iodide loading test, 24 h urinary excretion of iodine was about 60% in normal controls, but only 10% in a different group of six euthyroid patients with renal dysfunction. These findings suggest that impaired renal handling of iodine rather than autoimmune mechanism may have a significant role in the pathogenesis of reversible hypothyroidism found in patients with renal dysfunction, probably through a prolonged Wolff-Chaikoff effect.

Adult↗
PubMed1992

The corrosion behavior of Nd2Fe14B and SmCo5 magnets.

Rare earth magnets have corrosive problems associated with their use in prostheses in various fields including orthodontics. The purpose of this study is to investigate the corrosion behavior of an Nd2Fe14B magnet and a SmCo5 magnet in an oral environment. The relations among the attractive force changes, the released elements, the weight changes and the anodic polarization measurements of the magnets were examined under immersions in 1% NaCl, 1% lactic acid, 0.05% HCl, 0.1% Na2S and Greenwood's artificial saliva at 37 degrees C for forty-two days. The results showed that the rare earth magnets underwent high corrosive assaults and large attractive force reductions by the immersions in 1% lactic acid and 0.05% HCl. The problem of corrosion of the magnets could be overcome by sealing them within laser-welded stainless steel capsules.

Corrosion↗
PubMed1992

[High accuracy measuring device for dental cast--using device with flat laser beam].

A new system has been developed for measuring the surface morphology of the occlusal material. The main characteristic of the system is utilizing a flat laser beam to produce high accuracy measuring and to enable measuring 200 points at the same time on a line of 30 mm in length. It takes 8 to 10 minutes to digitize the whole morphology of a dental cast. The system has a central processing unit that assembles a series of digitized points into a data file of the dental morphology. It is also able to recognize the graphical image of the numerically reconstructed morphology on the CRT. Application of this measuring system enables the approach to the qualitative and quantitative evaluation of the spatial relationship between the opposing teeth at near the occlusal contact.

Dental Casting Technique↗
PubMed1992

Signal transduction in glycosaminoglycan (GAG) synthesis by cultured chondrocytes and its inhibition by inflammatory cell-derived hydrogen peroxide.

Signal transduction in glycosaminoglycan (GAG) synthesis by chondrocytes has been studied. The activity of various subspecies of protein kinase C (PKC) in chondrocytes derived from rodent costal cartilage and bovine articular cartilage has been determined and the role of PKC in GAG synthesis as well as the possible interactions of PKC with calcium- or cyclic AMP (cAMP)-dependent systems in the synthesis of GAG. To investigate GAG synthesis in inflammatory conditions, the effects of hydrogen peroxide on PKC activity of the chondrocytes and PKC-mediated GAG synthesis have been studied. 12-O-Tetradecanoylphorbol-13-acetate (TPA), an activator of PKC, increased GAG synthesis in a dose-dependent fashion. This suggests that PKC up-regulates the synthesis of GAG in cultured chondrocytes. This increase was not significantly affected by simultaneous addition of the calcium ionophore, ionomycin, or dibutyryl cAMP (db-cAMP), a cAMP analogue. Ionomycin and db-cAMP, when used alone, did not significantly alter GAG synthesis by chondrocytes. Thus there appears to be no interaction between PKC and calcium- or cAMP-mediated systems in GAG synthesis. The increase in GAG synthesis induced by TPA was significantly (P less than 0.01) reduced by simultaneous addition of hydrogen peroxide (10(-6) M), without affecting cell viability. The activity of PKC in chondrocytes pretreated with 10(-6) M hydrogen peroxide was also significantly inhibited. Thus hydrogen peroxide which is generated by inflammatory cells may be important in suppression of GAG synthesis in inflammatory conditions.

Animals↗
PubMed1992

[Familial cavernous angioma of the central nervous system--report of a family and review of literature].

In this paper we reported a familially occurred cavernous angiomas (CA) of the central nervous system (CNS). Case 1 was a 14-year-old female with an initial symptom of transient motor and sensory disorders of the right upper extremity. On examination she had a cutaneous angioma and no neurological deficit. CT and MRI revealed two lesions in the brain. These lesions were removed surgically and were diagnosed histologically as CA. Case 2 was a 45-year-old female, the mother of case 1, with a long standing headache. She had a cutaneous angioma and no neurological deficit. CT and MRI revealed a CA in the brain and a one in the cervical cord. Case 3 was an 11-year-old female, the cousin of case 1, with an initial symptom of left hemiparesis. On examination, she had a cutaneous angioma and left hemiparesis. CT revealed two lesions in the brain. These lesions were removed surgically and were diagnosed histologically as CA. Familial CA of the CNS is relatively rare and the reported cases were 24 families consisted of 70 cases. We analyzed the reported cases to clarify the specificities of the familial cases. In the familial cases, CAs were apt to be multiple and were located more frequently in the posterior fossa than in the non-familial cases. In some familial cases, the vascular anomalies of the CNS other than CA or CA of the skin or retina were also revealed. Because of high incidence (89%) of the hemorrhage from the histologically verified CA, operation should be carried out even in the cases of CA with mild or no symptom, if the lesion is accessible surgically.

Adolescent↗
PubMed1991

[The relationship between TSH response to TRH and GH response to dopaminergic agents in patients with acromegaly].

The role of dopaminergic agents (DA) in the regulation of growth hormone (GH) secretion was investigated in patients with untreated acromegaly. TRH (0.5 mg iv), bromocriptine (Br) (2.5 mg orally) or L-Dopa (500 mg orally) loading tests were performed, and serum levels of TSH, GH and prolactin (PRL) were measured. Patients were defined as responders to TRH when peak TSH level after TRH test was higher than 5 microU/ml. Br or L-Dopa was considered to be effective when serum GH or PRL levels were suppressed more than 50% of the basal value. The patients were classified into large adenoma group with suprasellar extension or cisternal herniation (L group, n = 7) and intrasellar small adenoma group (S group, n = 11) which was further divided into TRH responder (Sr group, n = 4) and TRH non-responder with suppressed TSH (Ss group, n = 7). Br was effective in 7 or 100% of 7 patients in the Ss group but only in one or 25% of 4 patients in the Sr group. Br was also effective in 5 or 71% of 7 patients in the L group, although most of them were responders to TRH. Percent inhibition of serum GH levels by Br was significantly higher in the Ss group (82.3 +/- 12.3%, p less than 0.001) and in the L group (64.7 +/- 20.5%, p less than 0.05) compared with that in the Sr group (29.3 +/- 21.6%). Suppression of serum GH level by L-Dopa was also observed in the Ss group. In contrast to the difference in the response of GH, serum PRL level was equally suppressed by Br or L-Dopa in each group. Suppression of TSH by administration of exogenous T4 had no effect on the GH suppression effect of Br in the Sr group. Considering the dual effects of DA to enhance growth hormone-releasing hormone (GHRH) secretion in the hypothalamus and to suppress GH secretion in the pituitary gland, these findings suggest that the paradoxical effect of DA to suppress serum GH level is observed when the hypothalamo-pituitary axis is disturbed mechanically by large adenoma in the L group or functionally in the Ss group probably due to enhanced secretion of somatostatin which suppresses TSH secretion and impairs the effect of GHRH.

Acromegaly↗
PubMed1991

Cytokine enhancement of monocyte/synovial cell attachment to the surface of cartilage: a possible trigger of pannus formation in arthritis.

When rheumatoid articular cartilage samples were incubated with normal peripheral blood monocytes and cultured synovial cells in the presence of recombinant human interleukin-1 (IL-1) in vitro, large numbers of monocytes were seen to be attached to the articular surface. Significant numbers of monocytes invaded the cartilage tissue when the rheumatoid cartilage samples were pre-incubated with 10 U/ml of IL-1. Considerable numbers of monocytes were also attached to normal cartilage when these were pre-incubated with IL-1. It is of interest that recombinant human gamma interferon (gamma-IFN) did not enhance monocyte attachment. However, there was a significantly greater attachment of monocytes to rheumatoid than to normal cartilage. When normal cartilage was exposed to collagenase and then incubated with monocytes or synovial cells in the presence of 10 U/ml of IL-1, large numbers of cells were attached to the natural cartilage surface but not to the cut surface. These phenomena were much more intense when the rheumatoid cartilage was pre-incubated with collagenase. These results indicate that increased levels of IL-1 in the rheumatoid joint may play an important role in joint destruction by stimulation of pannus formation by inducing synovial cell attachment to the articular surface.

Arthritis, Rheumatoid↗
PubMed1991

Refined determination of breakpoints of the translocation t(1;7) associated with signs of HMC syndrome.

High-resolution band analysis was performed in order to precisely determine the breakpoints of a de novo chromosome translocation, t(1;7), which is associated with clinical signs of HMC syndrome (McKusick's #239800). The breakpoints were found to be at 1q31.2 and 7p15.1-p15.3, respectively. The finding of the translocation in this case might not be coincidental, but rather suggestive of the gene locus responsible for the development of HMC syndrome at either site of the breakpoints.

Abnormalities, Multiple↗
PubMed1991

Effects of growth factors on mucosal scar fibroblasts in culture--a possible role of growth factors in scar formation.

Various growth factors are known to play important roles in wound healing, especially in an early inflammatory phase. However, their roles in subsequent scar formation phase are relatively unexplored. The aim of this study is to investigate the mechanisms of regulation in scar formation by these factors. Scar fibroblasts (SF) were obtained from immature scar tissue made at rat hard palate 1 month after excision and normal fibroblasts (NF) were obtained from the palatal mucosa of untreated control animals. SF showed a longer doubling time, and increased level of protein synthesis when compared to NF. Platelet-derived growth factor (PDGF) and epidermal growth factor (EGF) stimulated [3H]-thymidine uptake less effectively in SF than in NF. In both cells, transforming growth factor-beta 1 (TGF-beta 1) inhibited EGF-induced stimulation of [3H]-thymidine uptake, but had no effects when it was added alone. TGF-beta 1 increased collagen synthesis more effectively in SF than in NF. These data indicate that the growth factors may play key roles in regulating proliferation and metabolic activity of fibroblasts during scar formation.

Animals↗
PubMed1991

Submucosal dissection of the esophagus: a case report.

A 38-year-old male was admitted to our hospital complaining of dysphagia, sore throat and fever. An upper GI series revealed a "double-barrelled" esophagus. Endoscopic examination of the esophagus showed multiple ulcers and mucosal bridges resulting from laceration of the submucosal layer. An acute ulcer of the stomach was also found. Fasting and total parenteral nutrition for several weeks failed to bring about any changes in the endoscopic findings. As treatment, the mucosal bridges throughout the esophagus were divided with a diathermy knife under endoscopic control. Soon after the procedure, the patient's symptoms disappeared completely, and the massive dissection of the esophagus had improved except for slight depressions.

Adult↗
PubMed1991

H1 histone stimulates limited proteolysis of protein kinase C subspecies by calpain II.

Limited proteolysis of protein kinase C (PKC) subspecies with Ca2(+)-dependent neutral protease II (calpain II) was remarkably stimulated by basic polypeptides, such as H1 histone and poly-L-lysine. This stimulatory effect was observed for proteolysis of the active form of PKC, which was associated with phospholipid and diacylglycerol. The inactive form of PKC was far less susceptible to proteolysis, both in the presence and absence of the basic polypeptides. The basic polypeptides did not appear to interact with calpain II, but made the PKC molecule more susceptible to proteolysis. The relative rates of cleavage of type I (gamma), II (beta), and III (alpha) PKC were 2:2:1. The available evidence suggests that, like calpain I, calpain II may also contribute to the down-regulation or depletion of PKC.

Animals↗
PubMed1991

The critical period for mullerian duct regression in the dog embryo.

The embryonic period during which Mullerian duct regression and Mullerian Inhibiting Substance (MIS) secretion occur was determined in canine embryos removed from timed pregnancies (32, 36, 37, 39, 42, and 46 days gestation). Sex chromosomes of each embryo were identified in metaphase spreads prepared from fibroblast cultures. Testicular differentiation, defined by seminiferous tubule formation and the presence of Sertoli cells and Leydig cells, and the degree of Mullerian duct regression were determined by careful morphologic analysis of histologic sections of canine embryonic gonads (n = 20) and Mullerian ducts (n = 20). MIS was detected immunohistochemically in embryonic testes using avidin-biotin complex enhancement of a specific rabbit polyclonal anti-MIS antibody. Testicular differentiation was observed at 36 days gestation. The earliest evidence of Mullerian duct regression in male embryos was observed at 36 days gestation, and regression was completed by 46 days gestation. Positive staining for MIS was present in testes from 36 to 46 days (n = 9). Staining was absent in the undifferentiated testis (n = 1) at 32 days gestation and in ovaries at all ages tested (n = 10). Thus, MIS is normally present throughout the critical period for Mullerian duct regression in the embryonic male dog.

Animals↗