Biomedical subjects

H Sakai

Publications and source records attributed to H Sakai.

At least 199 records · Page 11Linked to original sources

PubMed2000

Long-term prognosis of parathyroid function after successful percutaneous ethanol injection therapy (PEIT) guided by color Doppler flow mapping in chronic dialysis patients.

Secondary hyperparathyroidism (2 HPT) is a representative disease of dialysis osteopathy, with the lesion that makes fibrous osteitis and the parathyroid hyperplasia by the hyper secretion of parathyroid hormone (PTH). This research examines the usefulness of selective percutaneous ethanol injection therapy (PEIT) of parathyroid glands in order to treat and control for 2 HPT. PEIT was performed in 46 patients resistant to calcitriol pulse therapy and all glands larger than 5 mm in diameter were destroyed by ethanol guided by power Doppler flow mapping. Serum intact-PTH (iPTH) levels fell from 633.3 +/- 359.9 to 226.3 +/- 204.7 pg/mL at three weeks and were maintained at 289.9 +/- 222.4 pg/mL at one year after PEIT. Total alkaline phosphatase activity fell from 384.9 +/- 160.1 to 234.0 +/- 110.5 IU/L at one year after PEIT. In 19 patients, i-PTH levels fell into relative hypoparathyroidism (iPTH < 160 pg/mL) at three weeks after PEIT: however, they recovered at one year after PEIT (191.1 +/- 29.6 pg/mL). In total, parathyroid function was maintained at optimal range (160 < iPTH < 360 pg/mL) in 80.4% of patients at one year after PEIT with appropriate medical therapy. As for the complications, recurrent nerve palsy was observed in only one patient, but was reversible. In conclusion, selective PEIT appears to be able to control appropriate parathyroid function and to be the method of choice to treat 2 HPT prior to parathyroidectomy.

Adult↗

PubMed2000

Effect of anti-inflammatory agents on corneal wound-healing process after surface excimer laser keratectomy.

PURPOSE: To investigate the effect of anti-inflammatory agents on conjunctival inflammation and corneal haze formation after excimer laser keratectomy. SETTING: Department of Ophthalmology, University of Tokyo Faculty of Medicine, Tokyo, Japan. METHODS: After excimer laser keratectomy was performed in 21 rabbits (42 eyes), saline, betamethasone 0.1%, or diclofenac 0.1% was topically applied 6 times a day for 4 weeks and then 3 times a day for 8 weeks. The degree of conjunctival inflammation was determined 1, 2, 3, and 7 days after the keratectomy. The degree of corneal haze was quantitatively measured using a digital analyzer before and once a week after the keratectomy. The expression of type IV collagen in the corneas at baseline and 4 and 12 weeks after the keratectomy was examined immunohistochemically. RESULTS: Compared with saline, betamethasone and diclofenac significantly decreased early-phase conjunctival inflammation. Betamethasone significantly inhibited corneal haze formation compared with saline at 3 to 5 and 8 to 12 weeks. Diclofenac did not inhibit corneal haze formation significantly. Although betamethasone tended to be more effective in inhibiting corneal haze formation and deposition of type IV collagen than diclofenac, there was no statistical difference between the 2 anti-inflammatory agents. CONCLUSION: Topically applied betamethasone effectively suppressed corneal haze formation after excimer laser keratectomy. Diclofenac was not statistically effective in inhibiting corneal haze formation.

Animals↗

PubMed2000

Transcription of the insecticidal crystal protein genes of Bacillus thuringiensis.

Production of a large amount of insecticidal crystal proteins encoded on large plasmids is largely dependent upon the mother cell, Bacillus thuringiensis (B. thuringiensis, also Bt), specific transcription systems attributable to sporulation. In the middle stages of sporulation, cry4A is most actively transcribed from the promoter cry4A-P1. The proximal transcriptional start point of cry4A, which is under the control of the promoter P1, is used in Bacillus subtilis (B. subtilis) in the middle stage of sporulation. The nucleotide sequence that determines the cry4A-P1 promoter is homologous to the consensus sequence for the promoter of sigma E-specific genes in B. subtilis, and to those promoters of the insecticidal protein genes that are efficiently transcribed in vitro with the RNA polymerase E sigma 35 isolated from B. thuringiensis. The sigma factor sigma 35 of B. thuringiensis is highly homologous and functionally equivalent to sigma E of B. subtilis. These results suggest that the cry4A transcription from P1 is under the control of sigma E in B. subtilis, and under the control of sigma 35 in B. thuringiensis.

Amino Acid Sequence↗

PubMed2000

Differential involvement of matrix vesicles during the initial and appositional mineralization processes in bone, dentin, and cementum.

The distribution of matrix vesicles and its role in biological mineralization were examined in bone and dental hard tissues of the rat after daily administrations of 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP), a potent inhibitor of mineralization, for 7 or 14 days. Newly formed, nonmineralized matrices of the HEBP-affected bone and mesodermal dental hard tissues other than circumpulpal dentin contained numerous mineral-filled matrix vesicles (MV), randomly distributed throughout the collagenous matrix. The distribution density of the mineral-filled MV in the HEBP-affected matrices of calvaria, metaphyseal trabecular bone, alveolar bone, and cellular cementum ranged from 60 to 70 per 100 microm(2), and no statistically significant differences were noted among the values. In the HEBP-affected dentin, however, MV were located only in the nonmineralized matrix of mantle dentin and totally absent in the circumpulpal dentin layers. Instead, the HEBP-affected circumpulpal dentin contained a dense meshwork of noncollagenous matrix enriched with calcium and phosphorus. Comparable meshwork structures were undetectable in nonmineralized matrices of the other hard tissues affected by HEBP. These observations suggest that a certain population of MV (60-70 per 100 microm(2)) is involved in the process of appositional mineralization in most of the mesodermal hard tissues, in addition to their well-known role in initial mineral induction in these tissues. Circumpulpal dentin appears to be an exception, where MV are not required for the appositional mineralization process. Exclusive localization of dentin phosphoproteins in circumpulpal dentin layers must take place to facilitate appositional mineralization at the calcification front, in the absence of MV.

Animals↗

PubMed2000

Biotransformation of (-)-dihydromyrcenyl acetate using the plant parasitic fungus Glomerella cingulata as a biocatalyst.

The microbial transformation of (-)-dihydromyrcenyl acetate was investigated using the plant parasitic fungus Glomerella cingulata. As a result, (-)-dihydromyrcenyl acetate was converted to dihydromyrcenol, 3,7-dihydroxy-3,7-dimethyl-1-octene-7-carboxylate, 3,7-dihydroxy-3,7-dimethyl-1-octene, 3,7-dimethyloctane-1,2, 7-triol-7-carboxylate, and 3,7-dimethyloctane-1,2,7-triol. In addition, microbial transformation of dihydromyrcenol by G. cingulata was carried out. The metabolic pathway of (-)-dihydromyrcenyl acetate is discussed.

Acetates↗

PubMed2000

Arsenic accumulation in three species of sea turtles.

Arsenic in the liver, kidney and muscle of three species of sea turtles, e.g., green turtles (Chelonia mydas), loggerhead turtles (Caretta caretta) and hawksbill turtles (Eretmochelys imbricata), were determined using HG-AAS, followed by arsenic speciation analysis using HPLC-ICP-MS. The order of arsenic concentration in tissues was muscle > kidney > liver. Unexpectedly, the arsenic concentrations in the hawksbill turtles feeding mainly on sponges were higher than the two other turtles primarily eating algae and mollusk which accumulate a large amount of arsenic. Especially, the muscles of the hawksbill turtles contained remarkably high arsenic concentrations averaging 153 mg kg(-1) dry weight with the range of 23.1-205 mg kg(-1) (n = 4), even in comparison with the data from other organisms. The arsenic concentrations in the tissues of the green turtles were significantly decreased with standard carapace length as an indicator of growth. In arsenic compounds, arsenobetaine was mostly detected in the tissues of all the turtles. Besides arsenobetaine, a small amount of dimethylarsinic acid was also observed in the hawksbill turtles.

Animals↗

PubMed2000

Nuclear factor-kappaB and caspases co-operatively regulate the activation and apoptosis of human macrophages.

Accumulating evidence suggests that macrophages function as major effector cells in the pathological process of various human diseases. We examined here the role of nuclear factor-kappaB (NF-kappaB) and caspases in the regulation of activation and apoptosis of macrophages. Activation of the human monoblastic leukaemia cell line, U937, by phorbol 12-myristate 13-acetate (PMA) increased the expression of CD14/CD86, and cytokine production. PMA stimulation also increased the expression of both pro-caspase-8 and pro-caspase-3 in U937, but not apoptosis or intracellular caspase-3 activity. PMA also increased the expression of X-chromosome-linked inhibitor of apoptosis protein (XIAP) in U937, suggesting an inhibitory action for XIAP on the caspase cascade in PMA-stimulated U937. Electrophoretic mobility shift assay (EMSA) showed a significant increase of nuclear NF-kappaB activity in PMA-stimulated U937. When a potent NF-kappaB inhibitor, pyrrolidine dithiocarbamate (PDTC), was added to U937 cell culture in the presence of PMA, apoptosis was triggered by activation of caspase-3, which was induced by caspase-8 activation. XIAP expression was markedly suppressed in PMA-treated U937 in the presence of PDTC. The inhibitors of caspase-8 and caspase-3 mostly inhibited apoptosis of U937 treated with PMA in the presence of PDTC. Furthermore, a phenotype of U937 treated with PMA and PDTC in the presence of caspase inhibitor was almost identical to that of unstimulated U937. Our results suggest that the signalling pathways involved in the activation and apoptosis of human macrophages could be co-operatively regulated by the use of NF-kappaB and caspase inhibitors, thus enabling the control of macrophage function and number.

Apoptosis↗

PubMed2000

Arabidopsis ARR1 and ARR2 response regulators operate as transcriptional activators.

The genes coding for the response regulators ARR1 and ARR2 have previously been identified by in silico screening of an expression sequence tag database and subsequent cloning from both Arabidopsis cDNA and genomic libraries. Their structures, in which the N-terminal signal receiver domain is followed by the output domain, are characteristic of typical bacterial response regulators of the two-component regulatory systems that control responses to a variety of environmental stimuli. Here we present evidence that these response regulators actually work as transcription factors. ARR1 and ARR2 were localized in the nuclei of plant cells regardless of the presence or absence of their signal receiver domain. Their middle segments, which faintly resemble the mammalian oncogene product Myb, were capable of binding double-stranded DNA in a sequence-specific manner in vitro. Their C-terminal halves functioned as transactivation domains in plant cells when combined with the DNA-binding domain of yeast GAL4. They thus possess all the essential components of a transcriptional activator. Both ARR1 and ARR2 promoted expression of a reporter gene in plant cells through their own target sequence. Truncation of their N-terminal signal receiver domain led to an increase in transactivation. An as yet unidentified phospho-relay signal may modulate the capability for transactivation and/or DNA binding through the signal receiver domain.

Arabidopsis↗

PubMed2000

Comprehensive gene expression profile of the adult human renal cortex: analysis by cDNA array hybridization.

BACKGROUND: Profiling of gene expression in healthy and diseased renal tissue is important for elucidating the pathogenesis of renal diseases. Comprehensive information about the genes expressed in renal tissue is unavailable. The recently developed cDNA array hybridization methodology allows simultaneous monitoring of thousands of genes expressed renal tissue. METHODS: Complex [alpha-33P]-labeled cDNA probes were prepared from histopathologically uninvolved remnants of nine renal tissues obtained by nephrectomy. Each probe was hybridized to a high-density array of 18,326 paired target genes. The radioactive hybridization signals by phosphorimager screens were quantitated by special software. Bioinformatics from public genomic databases were used to assign a chromosomal location of each expressed transcript and gene function. Cluster analysis was used to arrange genes according to the similarity in pattern of gene expression. RESULTS: A total of 7563 different gene transcripts was detected in the nine tissue samples. Approximately 870 of these genes were full-length mRNA human transcripts (HT), and the remaining 6693 were expressed sequence tags (ESTs). The full-length transcripts were classified by function of the gene product and were listed with information of their chromosomal positions. To allow a comparison between gene expression in clinical and experimental studies, the mouse genes with known similar function to the human counterpart were included in the bioinformatics analysis. Cluster analysis of 502 full-length genes that are expressed in four or more renal tissues revealed more than 110 genes that are highly expressed in all the renal specimens. CONCLUSIONS: The presented data constitute a comprehensive preliminary transcriptional map of the adult human renal cortex. The information may serve as a resource for speeding up the discovery of genes underlying human renal disease. The integrated listing of the full-length expressed human and mouse genes is available through e-mail (Abdalla_Rifai@Brown.edu).

Adult↗

PubMed2000

Cerebral tissue oxygen saturation during percutaneous cardiopulmonary support in a canine model of respiratory failure.

Percutaneous cardiopulmonary support (PCPS) has come to be applied for cardiopulmonary resuscitation and in the management of severe respiratory failure as well as severe heart failure. We investigated cerebral tissue oxygen saturation during PCPS in a canine model of respiratory failure using near-infrared spectroscopy. Animals were mechanically ventilated with 10% oxygen to make a respiratory failure model. Perfusion with PCPS was performed via the left femoral artery and switched to that via the right axillary artery. Cerebral tissue oxygen saturation was 54.2 +/- 3.4% during PCPS via the femoral artery and was 82.3 +/- 4.6% during PCPS via the axillary artery (p = 0.001). Hepatic tissue oxygen saturation was not significantly different. LV dP/dt max increased significantly after switching to the axillary blood supply (p = 0.001). Conventional PCPS may not have the capability of supporting cerebral circulation under severe respiratory failure without organic heart disease.

Analysis of Variance↗

PubMed2000

Eccentric roller type total artificial heart creating interatrial shunt.

Creating an interatrial shunt to achieve left-right flow balance and modification of the blood chambers to improve the basic performance of the device were performed in developing an eccentric roller type total artificial heart (ERTAH). Smaller blood chambers reduce friction loss and increase durability and energy efficiency. We changed the left blood chamber volume of 60 ml to 40 ml and the right blood chamber volume of 53 ml to 35 ml compared with previous types. Designs of inlet and outlet ports were modified to prevent backflow. In the mock circulatory system, redesigning the blood chambers resulted in a 20% increase in energy efficiency, about a two-fold increase of cardiac output and improved durability compared to the previous type. In an animal experiment, the ERTAH operated at a driving rate of 160 rpm with a left flow rate of 6.0 L/min and a right flow rate of 5.4 L/min. Interatrial shunt flow rate was 250-400 ml/min.

Animals↗

PubMed2000

Hematopoietic cell transplantation-related nephropathy in Japan.

To clarify the incidence and characteristics of hematopoietic cell transplantation (HCT)-related nephropathy (HCT-N) in Japan, we sent questionnaire letters to 188 hematologic divisions of 91 hospitals and analyzed the responses. Of 2,136 Japanese hematopoietic cell transplant recipients, 51 patients (2.4%) had HCT-N. The early-onset (</=30 days after HCT), middle-onset (31 to 120 days after HCT), and late-onset (>180 days after HCT) groups included 20, 16, and 15 patients, respectively. The early-onset group mainly consisted of patients with acute renal failure (ARF) and hemolytic uremic syndrome and/or thrombotic thrombocytopenic purpura. ARF was the dominant type in the middle-onset group. The main phenotype of the late-onset group was nephrotic syndrome, which correlated with chronic graft-versus-host disease (P=0.008). The total amounts of irradiation for patients with chronic renal failure and urinary abnormality were significantly greater than those for patients with ARF (P=0.004). The survival rate of the early-onset and middle-onset groups was 47.2%, whereas 87% of patients in the late-onset group survived (P=0.002). HCT-N is expected to become a serious and important problem in Japan because of the increasing number of HCTs from unrelated donors.

Adolescent↗

PubMed2000

Incidence of human papillomavirus 16 and 18 infection and p53 mutation in patients with oral squamous cell carcinoma in Japan.

The purpose of this study was to investigate the prevalence of human papillomaviruses (HPVs) 16 and 18 infection, and p53 mutation in oral squamous cell carcinomas (SCCs) in Japanese patients. Our results showed a higher incidence of HPV16 and 18 infections than previous studies because we combined the findings of a consensus polymerase chain reaction (PCR), restriction fragment length polymorphism by using the restriction enzyme digestion of the PCR products and Southern blot hybridization. Each HPV16 and 18 E6/E7 DNA was detected in 9 (20%) and 25 (54%) of 46 samples. The p53 mutation in the exons from 5 to 8 were detected in 20 out of 46 samples (43%) by a PCR-single strand conformation polymorphism analysis. There was a significant relationship between HPV16 and the p53 mutation (P =0.02) suggesting that HPV16 infection has a mutagenic effect in oral SCC. However, neither HPV infection nor p53 mutation influenced survival.

Adult↗

PubMed2000

Elevation of mRNA levels of tissue-type plasminogen activator and urokinase-type plasminogen activator in hippocampus and cerebral cortex following middle cerebral artery occlusion in rats.

Tissue-type plasminogen activator (tPA) and urokinase-type plasminogen activator (uPA) have been used for thrombolitic therapy. In contrast, it is suggested that these compounds might be involved in neuronal cell damage. The activation and the function of tPA and uPA are less understood in ischemic brain tissue. Therefore, changes in tPA and uPA mRNA in rat brain tissue after MCA occlusion and in the neuronal cell line, PC12 cells, during the hypoxic stimulation were examined. Permanent middle cerebral artery (MCA) occlusion was induced by advancing a filament into the internal carotid artery in 36 adult male Sprague-Dawley rats. The ischemic cerebral cortex and contralateral cortex of MCA area, and bilateral hippocampus were collected at 0 (controls), 1, 3, 6, 12 and 24 h after occlusion. Hypoxia was induced in PC12 cells with a multigas incubator (set to 1% O2). The quantitative reverse transcription-polymerase chain reaction acted as a measurement of alteration in mRNA levels. The mRNA levels of tPA and uPA were significantly increased after MCA occlusion in the ischemic cerebral cortex. The magnitude of the increase in tPA and uPA mRNA in 24 h after occlusion was twice the value in sham-operated rat (0 h). The increases of tPA mRNA were time-dependent in insult and contralateral hippocampus. The increase of uPA mRNA was also seen in the hippocampus bilaterally, although the increase was more significant on the ipsilateral side. In PC12 cells, necrotic (approximately 35%) and apoptotic cells (approximately 65%) could be distinguished by hypoxic stimulus for 24 h, and the mRNA for tPA was significantly increased for 6 h-12 h, while the mRNA for uPA was not detected at any point in the study. Our results suggest that focal ischemia might result in the activation of these proteases not only in the insult but also in the contralateral brain tissue.

Animals↗

PubMed2000

p53 knockout mice (-/-) are more susceptible than (+/-) or (+/+) mice to N-methyl-N-nitrosourea stomach carcinogenesis.

Mutations of the p53 tumor suppressor gene constitute one of the most frequent molecular changes in a wide variety of human cancers. Mice deficient in p53 have recently attracted attention for their potential to identify chemical genotoxins. In this study we have investigated the susceptibility of p53 nullizygote (-/-), heterozygote (+/-) and wild-type (+/+) mice to N:-methyl-N:-nitrosourea (MNU) gastric carcinogenesis. p53 knockout mice were treated with 30 p.p.m. MNU in the drinking water 1 week on and 1 week off and killed after 5 weeks. The numbers of pepsinogen-altered pyloric glands (PAPG), putative preneoplastic lesions, were 1.8, 1.7 and 22.6 in p53 (+/+), (+/-) and (-/-) mice, respectively. In a 15 week experiment, adenomas were found in 0 of 19 (+/+) (0%), 2 of 21 (+/-) (9.5%) and 6 of 10 (-/-) (60.0%) animals. Also, one well-differentiated adenocarcinoma was observed in a p53 (-/-) mouse. After 40 weeks treatment with 120 or 30 p.p.m. MNU there was no significant difference in the incidence of gastric tumors between p53 (+/+) and (+/-) mice. However, mortality from carcinogen-induced lymphomas, leukemias and sarcomas was very much greater in the latter group. Homozygous knockout animals could not be maintained long term. PCR-single strand conformation polymorphism analysis of exons 5-8 of the p53 gene of DNA extracts from 68 gastric tumors consisting of 16 and 20 30 p.p.m. MNU-treated p53 (+/+) and (+/-) mice and 14 and 18 120 p.p.m. MNU-treated p53 (+/+) and (+/-) mice demonstrated no mutations. These results suggest that p53 may not be a direct target of MNU but rather play an important role as a gatekeeper in mouse stomach carcinogenesis induced by this direct acting agent.

Animals↗

PubMed2000

Regulation of SUP expression identifies multiple regulators involved in arabidopsis floral meristem development.

During the course of flower development, floral homeotic genes are expressed in defined concentric regions of floral meristems called whorls. The SUPERMAN (SUP, also called FLO10) gene, which encodes a C2H2-type zinc finger protein, is involved in maintenance of the stamen/carpel whorl boundary (the boundary between whorl 3 and whorl 4) in Arabidopsis. Here, we show that the regulation of SUP expression in floral meristems is complex, consisting of two distinct phases, initiation and maintenance. The floral meristem identity gene LEAFY (LFY) plays a role in the initiation phase through at least two pathways, which differ from each other in the involvement of two homeotic genes, APETALA3 (AP3) and PISTILLATA (PI). AP3, PI, and another homeotic gene, AGAMOUS (AG), are further required for SUP expression in the later maintenance phase. Aside from these genes, there are other as yet unidentified genes that control both the temporal and spatial patterns of SUP expression in whorl 3 floral meristems. SUP appears to act transiently, probably functioning to trigger a genetic circuit that creates the correct position of the whorl 3/whorl 4 boundary.

AGAMOUS Protein, Arabidopsis↗

PubMed2000

Resistance to Friend murine leukemia virus infection conferred by the Fv-4 gene is recessive but appears dominant from the effect of the immune system.

Fv-4 is a mouse gene that dominantly confers resistance to infection with Friend murine leukemia virus (F-MuLV) (S. Suzuki, Jpn. J. Exp. Med. 45:473-478, 1975). However, the resistance caused by Fv-4 is recessive in nude mice, which suggests that immunological effects play important roles in this resistance in vivo (K. Higo, Y. Kubo, Y. Iwatani, T. Ono, M. Maeda, H. Hiai, T. Masuda, K. Kuribayashi, F. Zhang, T. Lamin, A. Adachi, and A. Ishimoto, J. Virol. 71:750-754, 1997). To determine the immunological effect on the resistance in vivo, we infected immunologically immature newborn mice homozygous (Fv-4(r/r)) and heterozygous (Fv-4(r/-)) for Fv-4. Although the Fv-4(r/r) mice showed complete resistance to F-MuLV whether infected neonatally or as adolescents, the Fv-4(r/-) mice showed high sensitivity to viral proliferation and disease induction when infected as newborns but complete resistance when infected as adolescent mice. To confirm the immunological effect on the resistance in adolescent mice with the Fv-4(r/r) and Fv-4(r/-) genotypes, we examined the effect of an immunosuppressant drug, FK506, on the resistance. The mice with the Fv-4(r/r) genotype treated with FK506 still showed resistance, but the mice with the Fv-4(r/-) genotype became highly sensitive to F-MuLV infection. Flow cytometric analysis to detect the Fv-4 gene product showed that the Fv-4 gene product was expressed on the cells from newborn and adolescent mice. The Fv-4 gene product was also detected on the cells from the FK506-treated mice as well as on those from untreated mice. However, a quantitative difference in the gene product between the cells with the Fv-4(r/r) and Fv-4(r/-) genotypes was detected by indirect staining for flow cytometry. These results show that the resistance to F-MuLV infection conferred by the Fv-4 gene is originally recessive, but it looks dominant in adolescent mice mainly because of the effect of the immune system.

Animals↗

PubMed2000

Mechanisms of human papillomavirus E2-mediated repression of viral oncogene expression and cervical cancer cell growth inhibition.

The papillomavirus E2 gene product plays a pivotal role in viral replication. E2 has multiple functions, including (i) transcriptional activation and repression of viral promoters and (ii) the enhancement of viral DNA replication. It was previously reported that E2 suppressed the growth of papillomavirus-positive cervical carcinoma cell lines. In the present study, we investigated the mechanisms of E2 growth inhibition. We found that the transcriptional activation function of E2 is required for inhibition of the growth of HeLa cells as well as for transcriptional repression of the viral E6/E7 promoter. It had been previously postulated that transcriptional repression of the E6/E7 promoter results from E2 binding its cognate sites proximal to the E6/E7 promoter and displacing other cellular transcriptional factors. In this study, we report a requirement for the transcription activation function for the binding of E2 to transcriptionally active templates.

Cell Division↗