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Biomedical subjects

H Kurihara

Publications and source records attributed to H Kurihara.

At least 199 records · Page 11Linked to original sources
PubMed1997

Molecular cloning and characterization of the gene encoding 53 kD outer membrane protein of Porphyromonas gingivalis.

The pga53 gene which encoded the antigenic 53 kD outer membrane protein (Ag53) was isolated from a genomic DNA library of Porphyromonas gingivalis FDC381 by using an Ag53-immunized rabbit serum. Determination of its complete nucleotide sequence revealed that the precursor of Ag53 had a 50 amino-acid putative signal sequence and the mature protein of 448 amino acids. The deduced amino acid sequence after a 50 amino-acid putative signal sequence was in complete agreement with the first 20 N-terminal amino acids of purified Ag53. Analysis of the deduced amino acid sequence revealed the presence of a highly hydrophilic proline-rich region at the C-terminal of Ag53. The deduced amino acid sequence showed 29.9% homology with that of a 72 kD cell-surface protein in P. gingivalis. Southern hybridization revealed that pga53 was specific to several P. gingivalis strains and that P. gingivalis strains which did not possess Ag53 had genes homologous to pga53.

Amino Acid Sequence↗
PubMed1996

Chemonucleolytic effects of chondroitinase ABC on normal rabbit intervertebral discs. Course of action up to 10 days postinjection and minimum effective dose.

STUDY DESIGN: This study demonstrated the chemonucleolytic effects of chondroitinase ABC and its histologic and biochemical background. OBJECTIVES: To determine the course of chondroitinase ABC action on normal rabbit discs, and to find its minimum effective dosage. SUMMARY OF BACKGROUND DATA: No previous study has assessed the chemonucleolytic action of chondroitinase ABC in a time- and dose-dependent manner. This study also investigated the biochemical causes of radiologic and histologic changes in the discs. METHODS: Rabbits were injected with 4 U of pharmaceutical-grade chondroitinase ABC intradiscally. They were radiologically and histologically observed, and biochemical analyses of the discs were conducted on days 1, 3, 5, 7, and 10 postinjection in the time course study. Different doses of chondroitinase ABC were injected, and radiologic observations and water content of the discs were measured in the dose-finding study. RESULTS: The time course study revealed that the chondroitin sulfate content of discs significantly decreased from day 1 postinjection until the end of the experimental period. The weight and water content of the nucleus pulposus decreased on day 3, and disc space narrowing was observed from the day after injection. The dose-finding study showed that a dose of 0.0002 U/disc still induced disc space narrowing and a decrease in water content. CONCLUSIONS: Chondroitinase ABC is estimated to have a chemonucleolytic effect at least by day 3 postinjection at a dose level of 0.0002 U/disc or higher in rabbits.

Animals↗
PubMed1996

Behavioral and adrenocortical responses to stress in neonates and the stabilizing effects of maternal heartbeat on them.

Adrenocortical response to stress in neonates was assessed by estimating salivary concentrations of cortisol, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulfate (DHEA-S). Behavioral responses to stress were also scored clinically, according to the method of Lewis and Thomas [15]. The modulation of these measures by hearing maternal heartbeat was also evaluated. Levels of cortisol and DHEA in saliva in neonates correlated well with those of serum showing significant variation in painful stress. Hearing the maternal heartbeat significantly reduced the grade of variation, but the recorded sound of the Japanese drum with the same rhythm showed no significant effect. Scores of the behavioral response to stress also decreased significantly in neonates who were presented with the maternal heartbeat in comparison with those hearing no sound or the beat of a Japanese drum.

Circadian Rhythm↗
PubMed1996

Endothelin-1 is involved in mechanical stress-induced cardiomyocyte hypertrophy.

We have recently shown that mechanical stress induces cardiomyocyte hypertrophy partly through the enhanced secretion of angiotensin II (ATII). Endothelin-1 (ET-1) has been reported to be a potent growth factor for a variety of cells, including cardiomyocytes. In this study, we examined the role of ET-1 in mechanical stress-induced cardiac hypertrophy by using cultured cardiomyocytes of neonatal rats. ET-1 (10(-8) approximately 10(-7) M) maximally induced the activation of both Raf-1 kinase and mitogen-activated protein (MAP) kinases at 4 and 8 min, respectively, followed by an increase in protein synthesis at 24 h. All of these hypertrophic responses were completely blocked by pretreatment with BQ123, an antagonist selective for the ET-1 type A receptor subtype, but not by BQ788, an ET-1 type B receptor-specific antagonist. BQ123 also suppressed stretch-induced activation of MAP kinases and an increase in phenylalanine uptake by approximately 60 and 50%, respectively, but BQ788 did not. ET-1 was constitutively secreted from cultured cardiomyocytes, and a significant increase in ET-1 concentration was observed in the culture medium of cardiomyocytes after stretching for 10 min. After 24 h, an approximately 3-fold increase in ET-1 concentration was observed in the conditioned medium of stretched cardiomyocytes compared with that of unstretched cardiomyocytes. ET-1 mRNA levels were also increased at 30 min after stretching. Moreover, ET-1 and ATII synergistically activated Raf-1 kinase and MAP kinases in cultured cardiomyocytes. In conclusion, mechanical stretching stimulates secretion and production of ET-1 in cultured cardiomyocytes, and vasoconstrictive peptides such as ATII and ET-1 may play an important role in mechanical stress-induced cardiac hypertrophy.

Animals↗
PubMed1996

The crystal structure of ribonuclease Rh from Rhizopus niveus at 2.0 A resolution.

The three-dimensional structure of ribonuclease Rh (RNase Rh), a new class of microbial ribonuclease from Rhizopus niveus, has been determined at 2.0 A resolution. The overall structure of RNase Rh is completely different from those of other previously studied RNases, such as RNase A from bovine pancreas and RNase T1 from Aspergillus oryzae. In the structure of RNase Rh, two histidine residues (His46 and His109) and one glutamic acid residue (Glu105), which were predicted to be critical to the activity from the chemical modification and mutagenesis experiments, are found to be located close together, constructing the active site. The indole ring of Trp49 plays an important role in preserving the active site structure by its stacking interactions with the imidazole ring of His 109, and by hydrogen bonding with the carboxyl group of Glu105. There exists a hydrophobic pocket around the active site, which contains the aromatic side-chain of Trp49 and Tyr57. The results of mutagenesis studies suggest that this pocket is the base binding site of the substrate.

Amino Acid Sequence↗
PubMed1996

Sequence analysis, chromosomal location, and developmental expression of the mouse preproendothelin-1 gene.

Recent studies have designated endothelins (ETs) as morphogenetic factors in embryonic development. In the present study, we cloned and characterized the mouse preproendothelin-1 (preproET-1) gene (Edn1) and examined its expression in reference to development. Edn1 comprises five exons, and the open reading frame encodes the 202-amino-acid preproET-1. The sequences and structural organization of Edn1 are highly homologous to those of other species, especially in the terminal 200-bp sequence of the 3'-noncoding region. Interspecific backcross mapping located Edn1 in the central region of chromosomal 13, where a mouse mutation, congenital hydrocephalus (ch), is also mapped. The highest expression of Edn1 mRNA is detected in the lung in adult mice, whereas Edn1 is predominantly expressed in the epithelium and mesenchyme of the pharyngeal arches and in the endothelium of the large arteries. Edn1 expression and ET-1 peptide levels in the lung progressively increased during the perinatal stage, whereas the expression of Edn3, a gene encoding ET-3, reciprocally decreases. These results suggest that Edn1 expression is developmentally regulated in different tissues and organs in mice in a spatial- and temporal-specific manner.

Amino Acid Sequence↗
PubMed1996

Thrombotic occlusion of the coronary artery associated with accidental detachment of undeployed Palmaz-Schatz stent.

We describe a case of coronary stenting in which accidental detachment of the Palmaz-Schatz stent induced thrombotic occlusion of the coronary artery. This case suggests that careful consideration of the risk involving coronary occlusion is mandatory on deciding the therapeutic strategy of the cases in which the unexpanded coronary stent cannot be retrieved following successful deployment.

Adult↗
PubMed1996

Surgical results of tympanoplasty with hokudai-shaped partial and total ossicular replacement prostheses.

The surgical results of tympanoplasty using a ceramic partial ossicular replacement prosthesis (PORP) or a ceramic total ossicular replacement prosthesis (TORP) were analyzed. The present study included 25 ears in 22 patients who underwent tympanoplasty between December 1986 and September 1994 and were followed up for more than 6 months postoperatively. Because the ceramic prosthesis was extruded from 2 of the 25 ears, the surgical results in the other 23 ears were analyzed, Surgical results were assessed according to a criterion that permits comparison with data from around the world. The criterion considers a postoperative airbone gap within 20 dB as a success. According to this criterion, the success rate was 90.9% for PORP, 50.0% for TORP, and 69.6% in total. These results are comparable with those found at other centers.

Adolescent↗
PubMed1996

Thyroplasty type I with ceramic shim.

To prevent side effects from a silicone shim in Isshiki thyroplasty type I, we used a ceramic shim in 10 patients with unilateral recurrent laryngeal nerve paralysis. No published reports have described the use of ceramic in this type of surgery. According to the degree of glottic insufficiency, ceramic shims of various heights were inserted into the fenestration made in the thyroid ala. All patients experienced subjective improvement of voice postoperatively. Laryngoscopies in most cases showed that glottic insufficiency improved postoperatively. In the postoperative examination, the maximum phonation time improved an average of 3.7 s, and the mean flow rate improved an average of 331 ml/s. We have analyzed the relationship of these improvements to the degree of glottic insufficiency and have compared our results with those of other investigators.

Adult↗
PubMed1996

Impaired ventilatory responses to hypoxia and hypercapnia in mutant mice deficient in endothelin-1.

We studied respiratory functions in mutant mice deficient in endothelin-1 (ET-1) generated by gene targeting. In conscious adult mice heterozygous for ET-1 gene mutation (ET+/- heterozygous mice), arterial PO2 was significantly lower, PCO2 tended to be higher, and pH tended to be lower than in wild-type littermates. When these conscious mice breathed room air, respiratory minute volume and rate, determined by body plethysmography, were not significantly different between the two groups. However, when ET+/- heterozygous mice were subjected to systemic hypoxia (1:1 air-N2) or hypercapnia (5% CO2-95% O2), increases in respiratory minute volume were significantly attenuated. In conscious newborn ET-/- homozygous mice delivered by cesarean section and tracheotomized, ventilatory responses to systemic hypoxia and hypercapnia, regularly observed in newborn wild-type mice, were almost totally absent. In urethan-anesthetized adult ET+/- heterozygous mice, increases in phrenic nerve discharges in response to hypoxia and hypercapnia were significantly attenuated. Our results demonstrate that ventilatory responses to hypoxia and hypercapnia are impaired in ET-1-deficient mice and suggest that endogenous ET-1 participates in the physiological control of ventilation.

Animals↗
PubMed1996

Glucose-mediated alteration of cellular function in human periodontal ligament cells.

Because diabetic patients are easily led to manifest severe periodontitis, we wanted to determine whether various glucose levels interfere with normal cellular function. Human periodontal ligament (PDL) cells were cultured in glucose-free medium, or in medium containing either 1100 mg/L of glucose (normal-glucose medium) or 4500 mg/L of glucose (high-glucose medium). Cells cultured in glucose-free medium changed their morphology from spindle-shaped to round, and incorporated trypan blue in a time-dependent manner. The incorporation rate was much faster in cells with shorter cell cycles than in those with longer cycles, suggesting the involvement of cell-cycle progression in cell death. However, fragmented DNA, which suggests apoptotic cell death, was not observed in these cells. We reasoned that initial cell rounding and detachment from the culture plate might be due to the conformational changes in cell-surface receptors to fibronectin, a major extracellular matrix for fibroblasts. Western blot analysis revealed that cells cultured in glucose-free medium lost their fibronectin receptor in a time-dependent manner. In addition, fibronectin receptor expression was much higher in cells cultured in high-glucose medium than in cells cultured in normal-glucose medium. Furthermore, the over-expression of the fibronectin receptor resulted in a suppressed chemotactic response of these cells to platelet-derived growth factor. On the basis of these data, it was hypothesized that a high glucose level induced over-expression of these receptors. This might be the mechanism by which a high glucose level compromises wound healing in diabetic patients and, at least in part, might be the reason diabetic patients are subject to severe periodontal destruction.

Blotting, Western↗
PubMed1996

Multiple roles for endothelin in melanocyte development: regulation of progenitor number and stimulation of differentiation.

Melanocytes in the skin are derived from the embryonic neural crest. Recently, mutations in endothelin 3 and the endothelin receptor B genes have been shown to result in gross pigment defects, indicating that this signalling pathway is required for melanocyte development. We have examined the effects of endothelins on melanocyte progenitors in cultures of mouse neural crest. Firstly, they stimulate an increase in progenitor number and act synergistically with another factor, Steel factor, in the survival and proliferation of the progenitors. These findings are consistent with findings from mice with natural mutations in the endothelin receptor B gene, which show an early loss of melanocyte progenitors. Secondly, endothelins induce differentiation of the progenitors into fully mature pigmented melanocytes. This finding is consistent with the expression of endothelins in the skin of mice at the initiation of pigmentation. The melanocytes generated in endothelin-treated cultures also become responsive to alpha melanocyte-stimulating hormone, which then acts to regulate the activity of the pigmentation pathway. These findings indicate two key roles for endothelin in melanocyte development: regulation of expansion of the progenitor pool and differentiation of progenitors into mature melanocytes.

Cell Count↗
PubMed1996

Novel 5-hydroxytryptamine (5-HT3) receptor antagonists. III. Pharmacological evaluations and molecular modeling studies of optically active 4,5,6,7-tetrahydro-1H-benzimidazole derivatives.

The R- and S-enantiomers of the 4,5,6,7-tetrahydro-1H-benzimidazole derivatives 3-8 were prepared by optical resolution. Each R-isomer, except for 3, was almost two orders of magnitude more potent than its S-isomer as a 5-hydroxytrptamine (5-HT3) receptor antagonist, as judged from they effect on the von Bezold-Jarisch reflex (B. J. reflex) in rats, the contraction of isolated guinea-pig colon and the receptor-binding affinity. The (--)-(R)-5-[(1-methyl-1H-indol-3-yl)carbonyl] derivative 6R.HCl (ramosetron = YM060) and (--)-(R)-5-[(1-indolinyl)carbonyl] derivative 4R.HCl (YM114 = KAE-393) given p.o. were hundreds of times more potent than 1 (ondansetron) and 2 (granisetron) in their inhibitory effects on cisplatin-induced emesis in ferrets and restraint stress-induced increases in fecal pellet output in rats. Three-dimensional molecular modeling studies suggested that the 'chiral selection' of the enantiomers might be influenced by the steric repulsion between the aromatic ring part and the conformationally restricted 4,5,6,7-tetrahydro-1H-benzimidazole ring in "equatorial-twist" conformation. In our pharmacophore model for the 5-HT3 receptor antagonist, a basic center exists at the left side of the aromatic-carbonyl plane when viewing from the aromatic part with the carbonyl oxygen atom upwards, whereas the "handedness" is ambiguous in the previously proposed model.

Animals↗
PubMed1996

Digalactosyldiacylglycerol suppression of inhibition by sulfoquinovosyldiacylglycerol of alpha-glucosidase.

Digalactosyldiacylglycerol (DGDG) suppressed the inhibition by sulfoquinovosyldiacylglycerol (SQDG) of an alpha-glucosidase reaction. Suppressing was considered to be an apparent decrease in inhibitory activity of SQDG ascribed to direct interaction between SQDG and DGDG. This suppression was presumed to be caused by less access of SQDG to the enzyme because SQDG and DGDG formed mixed micelles.

Drug Interactions↗
PubMed1996

Immunological, genetic, and microbiological study of family members manifesting early-onset periodontitis.

From the standpoint of host-parasite interactions, family studies help us understand the host defensive factors and the molecular mechanisms involved in the periodontal immune response. In this study, we report the immunological profile of host-defensive functions, human leukocyte antigen (HLA) phenotypes, and the microflora of a mother (rapidly progressive periodontitis), an older son (periodontally healthy), a younger son (localized juvenile periodontitis), and a daughter (localized juvenile periodontitis). We examined the peripheral neutrophil functions, phenotypic and functional analysis of peripheral lymphocytes, serum immunoglobulin G (IgG) antibody titers against periodontopathic bacteria, serological type of HLA class II antigens, and bacterial flora in all periodontal pockets. The results showed that Actinobacillus actinomycetemcomitans was dominant in the pockets of all subjects. The mother and two sons showed a depressed neutrophil chemotaxis to N-formyl-methionyl-leucyl-phenylalanine. All subjects except the older son exhibited low T4/T8 ratios. The mother and daughter had raised levels of IgG titers to Porphyromonas gingivalis. All subjects had HLA phenotypes of DRw52 and DQ1 in common. We found that the family members had similar disorders in certain defensive functions. This family has been a model for our understanding of the host defensive factors in the development of early-onset periodontitis.

Adolescent↗
PubMed1996

Host defensive functions in a family manifesting early-onset periodontitis.

Family case studies help us identify host risk factors in periodontal disease. In this study we examine a family consisting of a mother (40 years old, with rapidly progressive periodontitis), her elder daughter (14 years old, with localized juvenile periodontitis), and younger daughter (13 years old, with simple gingivitis). We examined 1) the peripheral neutrophil functions (chemotactic migration, phagocytosis, superoxide production); 2) lymphocyte functions (proliferative activity and cytokine productivity of T cells, immunoglobulin [Ig] M productivity of B cells when stimulated with pokeweed mitogen); 3) phenotypic analyses of peripheral lymphocyte subpopulations; 4) serum IgG antibody titers against periodontopathic bacteria; and 5) serological type of HLA class II. All the subjects exhibited high T4/T8 ratios due to high percentage of CD4-positive cells, showed high IgG titers to Actinobacillus actinomycetemcomitans, and had a HLA DQw1 in common. The mother showed a slight deficiency of neutrophil chemotactic migration to N-formyl methyonyl leucyl phenylalanin (fMLP), raised interleukin-2 productivity of T cell, and high levels of IgG titers to Porphyromonus gingivalis and Fusobacterium nucleatum. Both daughters showed weak T cell proliferative response to anti-CD3 monoclonal antibody and low IgM productivity. Low lymphocyte responsiveness may be involved in the pathogenesis of periodontal disease of these daughters; therefore, the lymphocyte dysfunctions shown should be considered in relation to the progression of periodontal disease.

Adolescent↗
PubMed1996

HLA Class II genotypes associated with early-onset periodontitis: DQB1 molecule primarily confers susceptibility to the disease.

DNA typing was performed on 24 Japanese patients with early-onset periodontitis (EOP) using the PCR-RFLP method to investigate an association of the susceptibility to EOP with the particular HLA class II alleles (HLA-DRB1, -DQA1, and -DQB1). DRB1*1401, DRB1*1501, DQB1*0503, and DQB1*0602 were found more frequently ("susceptible") in the EOP patients than in healthy controls. In contrast, DRB1*0405 and DQB1*0401 were found less frequently ("resistant") in EOP patients. All patients carrying DQB1*0602 had an atypical BamHI site in the intron upstream of the third exon of the DQB1 gene, which in our previous studies appeared to be a susceptible marker for EOP. A comparative analysis of the amino acid sequences of these susceptible and resistant HLA-DRB1 and DQB1 alleles elucidated some differences in antigen-derived peptide binding sites related to the susceptible or resistant alleles. Especially, DQB1*0503 and DQB1*0602 alleles carrying aspartic acid at position 57 and glycine at position 70 are increased significantly in EOP. Since amino acid residues at positions 57 and 70 on the DQB1 molecule are supposed to be involved in antigen binding, amino acid substitutions at these positions may affect the immune responsiveness to the periodontopathic antigen. Our results suggest that the DQB1 molecule plays a crucial role in the pathogenesis of EOP and that the susceptibility to EOP may be determined by the binding ability between the peptide and HLA-DQ antigens.

Adult↗