Biomedical subjects

H Shimada

Publications and source records attributed to H Shimada.

At least 667 records · Page 37Linked to original sources

PubMed1991

Aldosterone synthase cytochrome P-450 expressed in the adrenals of patients with primary aldosteronism.

A human cytochrome P-450 with aldosterone synthase activity was purified from the mitochondria of an aldosterone-producing adenoma. It was recognized by an anti-bovine cytochrome P-450(11 beta) IgG and by a specific antibody raised against a portion of the CYP11B2 gene product, one of the two putative proteins encoded by human cytochrome P-450(11 beta)-related genes (Mornet, E., Dupont, J., Vitek, A., and White, P. C. (1989) J. Biol. Chem. 264, 20961-20967). A similar and probably the same aldosterone synthase cytochrome P-450 was detected in the adrenal of a patient with idiopathic hyperaldosteronism. These aldosterone synthases were distinguishable from cytochrome P-450(11 beta), the product of another cytochrome P-450(11 beta)-related gene, i.e. CYP11B1, by their catalytic, molecular, and immunological properties and also by their localization. The latter enzyme was unable to produce aldosterone and did not react with the specific antibody against the CYP11B2 gene product. It was present both in tumor and non-tumor portions of the adrenals carrying the adenoma and in normal adrenal cortex. On the other hand, aldosterone synthase cytochrome P-450 localized in the tumor portions of the adrenals or in the adrenal of a patient with idiopathic hyperaldosteronism. Thus aldosterone synthase cytochrome P-450, a distinct species from cytochrome P-450(11 beta), is responsible for the biosynthesis of aldosterone in the human, at least in patients suffering from primary aldosteronism.

Adenoma↗

PubMed1991

Inhibition of tumor invasion of smooth muscle cell layers by recombinant human metalloproteinase inhibitor.

Matrix metalloproteinases secreted by tumor cells play an important role in the proteolytic degradation of the extracellular matrix during invasion. In a previous study, we showed that the degradation of extra-cellular matrices by human HT 1080 fibrosarcoma cells is suppressed by endothelial cells. The identification of inhibitors of metalloproteinases secreted by endothelial cells led us to postulate that these inhibitors were responsible for the suppressive effect (Cancer Res., 46: 3580-3586, 1986). In the present study, we have investigated the inhibitory activity of one of these inhibitors designated metalloproteinase inhibitor (MI)/tissue inhibitor of metalloproteinases (TIMP)-2 on the degradation and invasion of rat smooth muscle cell matrices by two invasive tumor cell lines, the c-Ha-ras-1 transfected rat embryo cell line 4R and the HT 1080 human fibrosarcoma cell line. The inhibitor was obtained in recombinant form from the culture medium of Chinese hamster ovary cells transfected with a human MI complementary DNA. Recombinant MI/TIMP-2 inhibited several matrix metalloproteinases identified in the culture medium of the tumor cell lines including interstitial collagenase. Mr 72,000 gelatinase (type IV collagenase), and Mr 92,000 gelatinase. Approximately 70% inhibition of the degradation of smooth muscle cell matrices was observed when the recombinant inhibitor was present along with cultured cells at a concentration of 10 micrograms/ml. Similarly, inhibition of the penetration of a multilayer of growing smooth muscle cells and their surrounding matrix was demonstrated. The inhibitor had no effect on cell growth or attachment. Thus, recombinant MI/TIMP-2, like TIMP, is a potent inhibitor of tumor invasion. Since both inhibitors are secreted by endothelial cells (J. Biol. Chem., 264: 17445-17453, 1989), they may play an important role in protecting large blood vessels from invasion.

Cell Adhesion↗

PubMed1991

Fine structural features of the chloroplast genome: comparison of the sequenced chloroplast genomes.

The entire nucleotide sequences of the rice, tobacco and liverwort chloroplast genomes have been determined. We compared all the chloroplast genes, open reading frames and spacer regions in the plastid genomes of these three species in order to elucidate general structural features of the chloroplast genome. Analyses of homology, GC content and codon usage of the genes enabled us to classify them into two groups: photosynthesis genes and genetic system genes. Based on comparisons of homology, GC content and codon usage, unidentified ORFs can also be assigned to each of these groups such that it is possible to speculate about the functions of products which may be produced by these ORFs. The spacer regions and intron sequences were compared and found to have no obvious homology between rice and liverwort or between tobacco and liverwort.

Base Composition↗

PubMed1991

Rapid isolation of a rice waxy sequence: a simple PCR method for the analysis of recombinant plasmids from intact Escherichia coli cells.

Polymerase chain reaction (PCR) is an efficient method for obtaining a desired nt sequence if both required primers can hybridize to the target DNA molecule specifically. A rapid and simple PCR-based method for analyzing plasmids using intact cells was established. An attempt to target a rice waxy sequence by PCR using homologous primers was also carried out. In three cases, specific fragments were amplified and their nucleotide sequences were determined. However, the cloned rice waxy gene contained base substitution mutations. The cumulative frequency of mutation after 30 polymerization cycles was estimated to be one in 500 bp.

Base Sequence↗

PubMed1991

Bone sarcomas as second malignant neoplasms following childhood cancer.

This study explores the relationship between histologic variants of bone sarcomas and previous therapy in patients in whom an unrelated malignant neoplasm had been diagnosed during childhood. Sarcomas of bone were the most common second malignant neoplasm (SMN) reported to the Late Effects Study Group, a 13-institution consortium consisting of pediatric oncology centers from western Europe, Canada, and the United States. The authors attempted to relate the histologic subtypes of the 91 bone tumors to clinical factors such as previous therapy and genetic predisposition because morphologic variants have been shown to have biologic significance in other tumors and may have etiologic import. The literature concerning the subtypes of bone tumors, clinical and experimental, is also reviewed. The authors also investigated the effect of several factors on the time interval from the first diagnosis to the SMN (i.e., the bone sarcoma). Anthracyclines significantly shortened the interval by about 3 years. The primary diagnosis also significantly affected the interval, with leukemia/lymphomas having the shortest interval and retinoblastoma the longest. The authors could not demonstrate any significant relationship between morphologic characteristics of the osteosarcoma and predisposing conditions. However, lesions diagnosed as chondrosarcoma and malignant fibrous histiocytoma occurred almost exclusively in patients who had received radiation therapy to the site in which the SMN developed.

Age Factors↗

PubMed1991

JC virus detection by in situ hybridization in brain tissue from elderly patients.

Brains from 10 patients aged 68 to 96 years at time of death were studied for JC viral DNA and common papovaviral capsid protein. In situ hybridization of JC viral DNA was performed by affinity cytochemistry using a biotinylated fragment of JC viral DNA. Immunohistochemistry was performed on brain tissue by the avidin DH-biotinylated horseradish peroxidase technique using polyclonal antibody raised against the papovaviral capsid protein. Viral protein and DNA were detected in 4 of 10 patients. JC virus may be present in the brains of aged patients more frequently than previously suspected.

Adult↗

PubMed1991

The histopathology of the liver in older patients with hepatitis B virus surface antigenaemia.

The histopathology of the liver and the detectability of intrahepatic hepatitis B virus (HBV) markers were studied in 34 autopsy cases in elderly patients (mean age 73.9 years, range 60-91 years) who had had a history of positive HBV surface antigenaemia prior to death. Seven of 14 persistent HBV carrier cases (group A) in which long-lasting HBV surface antigen (HBsAg) carriage in the sera had been confirmed by sequential assays, and 5 out of 15 HBV-infected people (group C, single assay) showed significant primary liver damages including chronic hepatitis, toxic hepatitis, liver cirrhosis and hepatocellular carcinoma. In 5 cases (group B), one of which was type B liver cirrhosis, HBsAg became negative and HBsAb appeared during the follow-up period (up to 33 months). Among confirmed HBV carriers, HBsAg and HBV core antigen were most frequently found in the liver of cirrhotic cases with and without hepatocellular carcinoma (5 of 6), whereas these were rarely detected in those with non-specific changes or slight hepatitic activity (1 of 7). All 5 cases in group B were negative for histological HBV-related antigens and the findings in group C were variously interpreted. Post-mortem cases of the aged HBV carriers who survived their mean life expectancy represent an important population in which to study the natural history of HBV carriers.

Aged↗

PubMed1991

The prevalence of anti-HCV antibodies in hemodialysis patients.

The prevalence of antibodies to hepatitis C virus (anti-HCV) was assessed in 489 hemodialysis patients and 152 members of the staff of dialysis units, using an Ortho HCV Ab ELISA Test. Of the 489 patients, 100 (20.4%) had anti-HCV, a significantly greater rate than was found in either staff members (0.7%, P less than 0.01) or local healthy blood donors (1.1%, P less than 0.001). Anti-HCV positivity was apparently related to the duration of hemodialysis.

Adult↗

PubMed1991

Effect of sugars in the preservation solution on liver storage in rats.

We have performed 128 rat liver transplants in order to examine the effect of sugars in preservation solutions on cold storage of rat livers. Glucose (Mw. 180), sucrose (Mw. 348), and raffinose (Mw. 594) were tested. Rat livers were preserved at 4 degrees C for 12, 16, 18, and 24 h in standard Eurocollins solution (EC solution) (solution A) or in one of three modified EC solutions in which 194 mM/liter glucose in standard EC solution was replaced by 140 mM/liter of glucose (solution B), sucrose (solution C), or raffinose (solution D). The osmolarity of the modified solutions (solution B-D) was 320 mOsm/liter. Using standard EC solution (solution A), the 1-week survival rate of rats receiving livers preserved for 12, 16, 18, or 24 h was 6/8, 4/8, 1/8, and 0/4, respectively. With solution B, in which 194 mM/liter glucose was replaced by 140 mM/liter glucose, 1 week survivors following transplantation of livers preserved for 12, 16, 18 or 24 h were 4/8, 3/8, 2/8 and 0/4, respectively. Solution C, which was identical to solution A except for the replacement of 194 mM/liter glucose by 140 mM/liter sucrose, gave the following 1-week survival rates: 5/8 for 12 h, 5/8 for 16 h, 2/8 for 18 h, and 0/4 for 24 hours preservation, respectively. Using solution D, which differed from A in the replacement of glucose by 140 mM/liter raffinose, the 1-week survival rates of rats grafted with livers preserved for 12, 16, 18, and 24 h were 6/8, 5/8, 3/8 and 0/4, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Comparative effects of N,N-disubstituted dithiocarbamates on excretion and distribution of cadmium in mice.

Sodium N-benzyl-D-glucamine dithiocarbamate (BGD), sodium N-p-hydroxymethylbenzyl-D-glucamine dithiocarbamate (HBGD), sodium N-p-carboxybenzyl-D-glucamine dithiocarbamate (CBGD) and sodium N-p-methoxybenzyl-D-glucamine dithiocarbamate (MeOBGD) were evaluated for their efficacy in the distribution and excretion of cadmium in mice exposed to cadmium. Mice were injected i.p. with 109CdCl2 (1 mg Cd/kg and 74 kBq of 109Cd/animal) and 30 min or 24 h later, they were injected with chelating agents (400 mumol/kg). At 30 min after treatment with cadmium, these chelating agents all significantly enhanced the biliary excretion of cadmium, and HBGD and CBGD significantly increased the urinary excretion of the metal. At 24 h after cadmium injection, BGD, HBGD, and MeOBGD significantly increased the biliary excretion of cadmium and HBGD was the most effective on the biliary excretion of the metal. These chelating agents were effective in mobilizing cadmium from the liver at 30 min after cadmium treatment. At 24 h after cadmium treatment, HBGD and MeOBGD effectively depressed cadmium content in the liver and only HBGD among these chelating agents significantly reduced the cadmium content in the kidney. In another experiment, mice were injected i.p. with 109CdCl2 and three days later, they were injected with chelating agents every other day for 2 weeks. HBGD was the most effective on the fecal and urinary excretions of cadmium. The hepatic cadmium content was decreased after HBGD or MeOBGD injection. The injection of HBGD caused a much greater decrease in renal cadmium content than did BGD, CBGD, or MeOBGD. The results of this study indicated that the injection of HBGD to mice pretreated with cadmium can remove cadmium from the body, mainly through fecal excretion, without redistribution of cadmium to other tissues such as the brain, testes, and heart, more effectively than that of BGD, CBGD, or MeOBGD.

Animals↗

PubMed1991

Protective effects of dextran sulfate and polyvinyl sulfate against acute toxicity of paraquat in mice.

The protective effects of sodium dextran sulfate (SDS) and potassium polyvinyl sulfate (PPS) against the acute toxicity of paraquat (PQ) in mice were studied. The survival rates of mice treated with SDS (2000 mg/kg) or PPS (2000 mg/kg) immediately after PQ ingestion (200 mg/kg) were 100% or 100%, respectively. When treated with SDS (2000 mg/kg) or PPS (2000 mg/kg) 15 or 30 min after PQ ingestion (200 mg/kg), the survival rates were 83% or 67% for SDS-treated groups and 67% or 33% for PPS-treated groups, respectively. Treatment with SDS (2000 mg/kg) or PPS (2000 mg/kg) immediately after oral administration of PQ (200 mg/kg) increased the fecal excretion of PQ, decreased the urinary excretion of PQ and decreased the contents of PQ in the lung, liver and kidney. Such effects of SDS and PPS were reduced in the treatment with these drugs at 15 min after PQ. The in situ small intestinal absorption of PQ was significantly reduced in the presence of SDS or PPS. The binding of PQ to SDS or PPS was determined by an ultrafiltration method. These results indicate that SDS and PPS inhibit the gastrointestinal absorption of PQ on the basis of the increased intestinal transit of PQ and the binding of PQ to the drugs resulting in the protective effectiveness of SDS and PPS on the acute toxicity of PQ.

Animals↗

PubMed1991

Comparative renal toxicity of metallothioneins with different cadmium/zinc ratios in rats.

The comparative renal toxicity of rats after injection of cadmium (Cd) and zinc (Zn)-metallothioneins (MTs) with different Cd/Zn ratios at the same dose of 200 micrograms MT-bound Cd/kg was studied. From determination of the urinary excretion of protein, aspartate aminotransferase (AST) and glucose, which are indices of Cd-induced renal damage, the extent of the renal toxicity of the MTs used here was in the order (1 Cd/0Zn)-MT = (2Cd/1Zn)-MT greater than (1Cd/2Zn)-MT greater than (1Cd/6Zn)-MT. The characterization of Cd, Zn and Cu in the urine after injection of MTs was examined using a Sephadex G-75 column. (1Cd/0Zn)-MT injection showed that Cd was present mainly in lower-molecular-weight fractions, with only small amounts of Cd in the MT fraction. Upon injection of other MTs, Cd was present mainly in the MT fraction and increased with decreasing Cd/Zn ratio. Zn was present mainly in lower-molecular-weight fractions and Cu mainly in the MT fraction, indicating the replacement of MT-bound Zn by Cu. The cumulative urinary excretion of Cd during 12 days after injection of MTs decreased with increasing Cd/Zn ratio. The Cd content of the kidney and liver increased with increasing Cd/Zn ratio. The results of this study indicate that in rats injected with MTs with different Cd/Zn ratios, the renal uptake of Cd increases with increasing Cd/Zn ratio, resulting in more severe renal damage.

Animals↗

PubMed1991

Potential application of shape memory plastic as elastic material in clinical orthodontics.

Polynorbornen, a shape memory plastic developed in Japan, has a glass transitional point of 35 degrees C. Once the environmental temperature exceeds the critical point, this plastic will begin to display an elastic property, then return to its original shape, if deformed. We examined whether the force generated during the elastic phase of polynorbornen could be used to displace human teeth. We found that the shape memory plastic wire of 1 mm in diameter stretched to two to three times of its original length at a temperature of 50 degrees C and a speed of 0.5 mm/sec would exert a relatively stable continuous light force of 119-156 g to move the teeth. This new material, compared with conventional elastic modules used in orthodontic therapy, exhibited a lesser degree of force degradation at a body temperature of 37 degrees C for a long period, and can be manufactured to near the tooth colour required. These advantages make feasible clinical application of the shape memory plastic in orthodontics.

Body Temperature↗

PubMed1991

Undifferentiated (embryonal) sarcoma of the liver. A tumor of uncertain histogenesis showing divergent differentiation.

Pathologic features of eight cases of undifferentiated (embryonal) sarcoma of the liver (USL) in childhood were studied. Light microscopic examination showed a diffuse growth of spindle cells with occasional polygonal cells and multinucleated giant cells and also revealed focal areas of storiform pattern in four tumors, cambium layer formation in one tumor, and alveolar arrangement in one tumor. Immunohistochemical study showed positive staining of proliferating cells for suggestive histiocytic markers (A1AT in 6/6, A1ACT in 5/6, lysozyme in 4/6, and KP1 in 4/6) and for muscle markers (desmin in 4/6 and HHF35 in 3/6). Ultrastructural examination demonstrated that the individual tumors were composed of a mixture of cells having fibroblastic, histiocytoid, fibrohistiocytoid, myofibroblastic, and undifferentiated (primitive mesenchymal) morphologies. Also identified were cells with definite myoblastic morphology in three tumors: leiomyoblastic in one and rhabdomyoblastic in two. In conclusion, the tumor cells in USL show phenotypical diversity comparable to those of malignant fibrous histiocytoma with or without additional rhabdomyosarcomatous or leiomyosarcomatous differentiation.

Actins↗

PubMed1991

Differential expression of beta amyloid protein precursor (APP) and tau mRNA in the aged human brain: individual variability and correlation between APP-751 and four-repeat tau.

We investigated the relationship between the differential expression of beta amyloid protein precursor (APP) and tau mRNA, and the extent of beta and tau deposition in three regions from each of the 38 aged brains obtained from consecutive autopsied cases. Remarkable variabilities were noted in the ratios of APP-770/-751/-695 and four-repeat tau among elderly individuals. There was no consistent alteration in the APP differential expression among beta plaque (-), (+), and (++(-) ) groups. Also, no differences in the four-repeat tau ratios were noted among tangle (-), (+), and (++) groups. Despite these great individual variabilities, APP-751 was found to be well-correlated with four-repeat tau. It is possible that APP-751 and four-repeat tau are increasing during aging, while APP-695 and three-repeat tau are decreasing.

Aged↗

PubMed1991

Paired twisted filaments in human pinealocytes.

Paired twisted filaments (PTF) have been confirmed and described ultrastructurally in the normal human pineal gland for the first time. The PTF showed a peculiar double helical structure, measuring 12 to 25 nm in maximal helix width with a half-periodicity of 30 to 35 nm (periodicity of the constrictions). Each filament was about 10 nm wide. The PTF formed parallel aggregates in the perikaryotic cytoplasm of the pinealocytes. In 8 of 12 autopsied middle-aged to elderly individuals, the PTF were present in a small proportion of pinealocytes. The identity of the PTF remains unclear in terms of their apparent similarity to the paired helical filaments observed previously in aged rats. However, the age distribution of individuals with PTF suggests that the intermediate filaments of human pinealocytes are more susceptible to early deterioration during aging than those of other cerebral neurons.

Actin Cytoskeleton↗

PubMed1991

Does the variability of casual blood pressure contribute to progressive subcortical vascular encephalopathy of Binswanger's type?

Our hypothesis was that progressive subcortical vascular encephalopathy of Binswanger's type (PSVE) in the elderly can be induced by repeated hypotension or greater variability of blood pressure in hypertensives, regardless of antihypertensive therapy. We retrospectively studied PSVE blood pressure, and compared them with those in atherothrombotic cerebral infarction (ACI) or in hypertensive cerebral hemorrhage (HCH). During the last seven years prior to death, neither the annual variability nor the annual mean value of systolic or mean arterial blood pressures in PSVE was different from that in ACI or in HCH. The present study did not support our hypothesis.

Aged↗

PubMed1991

Mobilization of renal and hepatic cadmium by dithiocarbamates in rats.

Sodium N-benzyl-D-glucamine dithiocarbamate (BGD), sodium N-p-hydroxymethylbenzyl-D-glucamine dithiocarbamate (HBGD), sodium N-p-carboxybenzyl-D-glucamine dithiocarbamate (CBGD), and sodium N-p-methoxybenzyl-D-glucamine dithiocarbamate (MeOBGD) were evaluated for their efficacy in the distribution and excretion of cadmium in rats exposed to cadmium. Rats were injected intraperitoneally with 109CdCl2 (1 mg Cd/kg and 74 kBq of 109Cd/one animal) and 30 min or 24 h later, they were injected with chelating agents (400 mumol/kg). At both 30 min and 24 h after treatment with cadmium, these chelating agents all significantly enhanced the biliary excretion of cadmium. At 24 h after cadmium injection, BGD and MeOBGD were the most effective on the biliary excretion of the metal. These chelating agents were effective in mobilizing cadmium from the liver at 30 min after cadmium treatment. At 24 h after cadmium treatment, BGD and MeOBGD significantly depressed cadmium content in the liver. In another experiment, rats were injected intraperitoneally with 109CdCl2 and 3 d later, they were injected with BGD, HBGD, or MeOBGD every other day for 2 weeks. The fecal excretion of cadmium was significantly increased by these chelating agents and MeOBGD was the most effective. The hepatic and renal cadmium contents were significantly decreased after BGD, HBGD or MeOBGD injection. The injection of MeOBGD to rats pretreated with cadmium was more effective than that of BGD, HBGD, or CBGD in removing cadmium from the liver. HBGD injection was more effective in decreasing the cadmium content in the kidney. The treatment with these chelating agents did not cause the redistribution of cadmium to brain, testes, and heart.

Animals↗