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Biomedical subjects

K Hara

Publications and source records attributed to K Hara.

At least 217 records · Page 12Linked to original sources
PubMed1999

Identification of a photoreceptor cell-specific nuclear receptor.

Nuclear receptors comprise a large and expanding family of transcription factors involved in diverse aspects of animal physiology and development, the functions of which can be modulated in a spatial and temporal manner by access to small lipophilic ligands and/or the specificity of their own localized expression. Here we report the identification of a human nuclear receptor that reveals a unique proximal box (CNGCSG) in the DNA-binding domain. The conservation of this feature in its nematode counterpart suggests the requirement for this type of P box in the genetic cascades mediated by nuclear receptors in a wide variety of animal species. The expression of this receptor, PNR (photoreceptor-specific nuclear receptor), appears strongly restricted in the retina, exclusively in photoreceptor cells. In human cell lines, PNR expression was observed in Y79 retinoblastoma along with other photoreceptor marker genes such as CRX. Among vertebrate receptors, PNR shares structural kinship with an orphan receptor TLX, and despite distinct differences in the DNA binding domain, PNR is able to recognize a subset of TLX target sequences in vitro. Analyses of the human PNR gene revealed its chromosomal position as 15q24, a site that has recently been reported as a susceptible region for retinal degeneration. These data support a role for PNR in the regulation of signalling pathways intrinsic to the photoreceptor cell function.

Amino Acid Sequence↗
PubMed1999

Oxidative stress in newborn infants with and without asphyxia as measured by plasma antioxidants and free fatty acids.

A rapid perfusion of oxygen in infants at birth may cause an increase of oxidative stress. To assess this possibility, we measured levels of blood plasma antioxidants and free fatty acids in 20 normal infants at 0, 1, 3, and 5 days after birth. Plasma levels of the most reactive antioxidant, ascorbic acid, decreased daily to equilibrium values at days 3 and 5. Percentages of oxidized form of coenzyme Q-10 (%CoQ-10) in total coenzyme Q, another good marker of oxidative stress, in infants (25-31%) were significantly higher than those in healthy young adults (4.5%). Plasma levels of total free fatty acids (FFA) in normal infants were highest at day 1 and decreased rapidly thereafter. The content of polyunsaturated fatty acids (PUFA) in total FFA was lowest at day 1 and then increased. Since PUFA are susceptible to oxidation, these changes in FFA composition suggest that oxidative stress is most evident at the initial day of neonatal life. Furthermore, it appears that mono-unsaturated fatty acids such as oleic and palmitoleic acids increase in response to the oxidative loss of PUFA. Similar changes in plasma antioxidants, FFA levels, and FFA compositions were observed in 9 infants with asphyxia. Values of %CoQ-10 in infants with asphyxia were significantly greater than those in normal infants, suggesting that infants with asphyxia have elevated oxidative stress.

Adult↗
PubMed1999

Structural requirement of leucine for activation of p70 S6 kinase.

The addition of leucine induced activation of p70S6k in amino acid-depleted H4IIE cells. Whereas the activation of p70S6k by leucine was transient, the complete amino acid stimulated p70S6k more persistently. The effect of leucine on p70S6k was sensitive to rapamycin, but less sensitive to wortmannin. Using various amino acids and derivatives of leucine, we found that the chirality, the structure of the four branched hydrocarbons, and the primary amine are required for the ability of leucine to stimulate p70S6k, indicating that the structural requirement of leucine to induce p70S6k activation is very strict and precise. In addition, some leucine derivatives exhibited the ability to stimulate p70S6k and the other derivatives acted as inhibitors against the leucine-induced activation of p70S6k.

Amino Acids↗
PubMed1999

Alpha4 protein as a common regulator of type 2A-related serine/threonine protein phosphatases.

The catalytic activity of the C subunit of serine/threonine phosphatase 2A is regulated by the association with A (PR65) and B subunits. It has been reported that the alpha4 protein, a yeast homolog of the Tap42 protein, binds the C subunit of serine/threonine phosphatase 2A and protein phosphatase 2A-related protein phosphatases such as protein phosphatase 4 and protein phosphatase 6. In the present study, we showed that alpha4 binds these three phosphatases and the association of alpha4 reduces the activities of these phosphatases in vitro. In contrast, PR65 binds to the C subunit of serine/threonine phosphatase 2A but not to protein phosphatase 4 and protein phosphatase 6. These results suggest that the alpha4 protein is a common regulator of the C subunit of serine/threonine phosphatase 2A and protein phosphatase 2A-related protein phosphatases.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Regulation of translational effectors by amino acid and mammalian target of rapamycin signaling pathways. Possible involvement of autophagy in cultured hepatoma cells.

Amino acid deprivation of Chinese hamster ovary cells overexpressing human insulin receptors results in deactivation of p70 S6 kinase (p70) and dephosphorylation of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), which become unresponsive to insulin; readdition of amino acids restores these responses in a rapamycin-sensitive manner, suggesting that amino acids and mammalian target of rapamycin signal through common effectors. Contrarily, withdrawal of medium amino acids from the hepatoma cell line H4IIE does not abolish the ability of insulin to stimulate p70 and 4E-BP1. The addition of 3-methyladenine (3MA) to H4IIE cells deprived of amino acids inhibited the increment in protein degradation caused by amino acid withdrawal nearly completely at 10 mM and also strongly inhibited the ability of insulin to stimulate p70 and 4E-BP1 at 10 mM. Treatment of H4IIE cells with 3MA did not alter the ability of insulin to activate tyrosine phosphorylation, phosphoinositide 3-kinase, or mitogen-activated protein kinase. In conclusion, the ability of H4IIE cells to maintain the insulin responsiveness of the mammalian target of rapamycin-dependent signaling pathways impinging on p70 and 4E-BP1 without exogenous amino acids reflects the generation of amino acids endogenously through a 3MA-sensitive process, presumably autophagy, a major mechanism of facultative protein degradation in liver.

Amino Acids↗
PubMed1999

Effects of imidapril on NOS expression and myocardial remodelling in failing heart of Dahl salt-sensitive hypertensive rats.

OBJECTIVES: To elucidate the relationship between renin-angiotensin system and nitric oxide in hypertensive heart failure, we evaluated the effects of long-term treatment with imidapril, angiotensin-converting enzyme inhibitor, on endothelial-cell nitric oxide synthase (eNOS) and inducible NOS (iNOS) expression in the left ventricle (LV) and its relation to myocardial remodelling in failing heart of Dahl salt-sensitive hypertensive rats (DS) fed a high-salt diet. METHODS: In DS rats fed an 8% NaCl diet after the age of 6 weeks, a stage of concentric left ventricular hypertrophy at 11 weeks (DSLVH) was followed by a distinct stage of fatal left ventricular failure with chamber dilatation at 18 weeks (DSCHF). Imidapril (DSCHF-I, n = 7, 1 mg/kg/day, subdepressor dose) or vehicle (DSCHF-V, n = 7) were given from DSLVH to DSCHF stage for 7 weeks, and age-matched (18 weeks) Dahl salt-resistant rats fed the same diet were served as control group (DR-C, n = 7). RESULTS: Markedly increased left ventricular end-diastolic diameter and reduced fractional shortening in DSCHF-V was significantly ameliorated in DSCHF-I using transthoracic echocardiography. The level of eNOS mRNA and protein in the LV was significantly suppressed in DSCHF-V compared with DR-C, and significantly increased in DSCHF-I compared with DR-C and DSCHF-V. The iNOS mRNA and protein and the fibrosis factor expression of type I collagen mRNA were significantly increased in DSCHF-V compared with DR-C, and significantly decreased in DSCHF-I compared with DSCHF-V. DSCHF-V demonstrated a significant increase in wall-to-lumen ratio, perivascular fibrosis, and myocardial fibrosis. These changes in the microvasculature were improved significantly by imidapril. CONCLUSIONS: Subdepressor dose of imidapril may ameliorate the endothelial damage not only by inhibiting production of angiotensin II but also by promoting eNOS and inhibiting iNOS mRNA and protein expression in the LV, and this increased eNOS mRNA and protein level may have a role in the improvement of congestive heart failure and myocardial remodelling.

Analysis of Variance↗
PubMed1999

Cleavage specificity of a myofibril-bound serine proteinase from carp (Cyprinus carpio) muscle.

Previously, we reported the purification and characterization of a myofibril-bound serine proteinase (MBP) from carp muscle (Osatomi K, Sasai H, Cao M-J, Hara K, Ishihara T. Comp Biochem Physiol 1997;116B:159-66). In the present study, the N-terminal amino acid sequence of the enzyme was determined, which showed high identity with those of other trypsin-like serine proteases. The cleavage specificity of MBP for dibasic and monobasic residues was investigated using various fluorogenic substrates and peptides. Analyses of the cleaved peptide products showed that the enzyme hydrolyzed peptides both at monobasic and dibasic amino acid residues. Monobasic amino acid residues were hydrolyzed at the carboxyl side; dibasic residues were cleaved either at the carboxyl side of the pair or between the two basic residues and the enzyme showed a cleavage preference for the Arg-Arg pair. Unexpectedly, MBP hydrolyzed lysyl-bradykinin and methionyl-lysyl-bradykinin at the carboxyl side of Gly fairly specifically and efficiently displaying a unique cleavage. Because MBP also degraded protein substrates such as casein and myofibrillar proteins, the substrate specificity of MBP appeared not to be strictly specific.

Amino Acid Sequence↗
PubMed1999

Benidipine stimulates nitric oxide synthase and improves coronary circulation in hypertensive rats.

We evaluated the effects of long-term treatment with benidipine, a long-acting calcium antagonist, on endothelial cell-type nitric oxide synthase (eNOS) activity and eNOS mRNA expression in the left ventricle (LV) and its relation to coronary flow reserve, and microvascular remodeling in renovascular hypertensive rats (RHR: 2K-1C Goldblatt). Benidipine (5 mg/kg/day) was given to RHR (B-RHR, n = 11) for 6 weeks. Vehicle-treated RHR (U-RHR, n = 11) and age-matched sham-operated rats (ShC, n = 11) served as control group. Coronary flow reserve was measured in conscious rats using colored microspheres. Fifty-micrometer slices of the LV were incubated with L-arginine to measure nitrite production using the Griess method and eNOS mRNA expression was determined by reverse transcription-polymerase chain reaction. An increased blood pressure in RHR was significantly decreased by benidipine. Nitrite production and eNOS mRNA expression in the LV of U-RHR was significantly lower than that of ShC. This suppression of nitrite production and eNOS mRNA expression was significantly reversed in B-RHR. U-RHR demonstrated a significant decrease in coronary flow reserve and capillary density, and a significant increase in wall-to-lumen ratio, perivascular fibrosis, myocardial fibrosis, and myocyte cross-sectional area. These impaired factors were improved significantly by benidipine. These findings suggest that benidipine therapy may increase nitrite production and eNOS mRNA expression not only by lessening the endothelial damage by the reduction of blood pressure levels, but also by the stimulation of NOS activity and eNOS mRNA, and this increased NOS activity and eNOS mRNA expression may play a role in the amelioration of coronary flow reserve and microvascular remodeling.

Animals↗
PubMed1999

Activation of cyclin D1-related kinase in human lung adenocarcinoma.

Cyclin D1 gene amplification is an important event in many cancers, but it is rarely found in non-small-cell lung cancer (NSCLC). This study was conducted in an attempt to clarify any other mechanisms related to cyclin D1 involvement in the malignant transformation of NSCLC, and we clearly showed for the first time that cyclin D1-related kinases are activated in NSCLC, especially in adenocarcinoma but not in squamous cell carcinoma. The results of this study strongly suggest that enhanced cyclin D1-related kinase activity could contribute to a progression of adenocarcinoma in NSCLC.

Adenocarcinoma↗
PubMed1999

Differential expression of costimulatory molecules in chronic inflammatory periodontal disease tissue.

Although B cell activation and subsequent immunoglobulin production are the immunopathological features of chronic inflammatory periodontal disease, in situ expression of costimulatory molecules in humoral immunity has not been investigated. In the present study we examined the expression of CD40, CD40 ligand (CD40L), CD80, CD86, CD28 and cytolytic T lymphocyte-associated antigen-4 (CTLA-4) on lymphocytes immunohistochemically. Cryostat sections were prepared from the gingival tissue samples of 14 patients with moderate to advanced adult periodontitis. In vitro kinetics of the expression of CD40L and CTLA-4 by peripheral blood T cells and that of CD80 and CD86 by peripheral blood B cells were also investigated by flow cytometry. Positive percentage expression of CD40L, CD28 and CTLA-4, and CD40, CD80 and CD86 was calculated for the number of CD3+ and CD19+ cells, respectively. Flow cytometric analysis demonstrated that the expression of CD40L and CTLA-4 on T cells, and CD80 and CD86 on B cells of peripheral blood was up-regulated upon activation. While most T cells and B cells expressed CD28, and CD80 and CD86, respectively, in gingival tissues, the expression of CD40L and CTLA-4 was lower but highly variable between specimens. Furthermore, these two molecules seemed to be expressed reciprocally in the lesion. As both CD40L and CTLA-4 expression are induced transiently by stimulation, variability in the expression of the molecules may reflect immunological activities and participation in the regulation of B cell activation of the lesion.

Abatacept↗
PubMed1999

Relevance of Fc gamma RIIIa-158V-F polymorphism to recurrence of adult periodontitis in Japanese patients.

The immunoglobulin receptor Fc gamma RIIIa (CD16) is distributed on natural killer (NK) cells, macrophages, and gamma delta T cells, and is polymorphic. Fc gamma RIIIa-158V has a higher affinity for both monomeric and immune complexed IgG1, IgG3, and IgG4 than IIIa-158F. We determined Fc gamma RIIIa-158V/F genotypes of Japanese patients with adult periodontitis. A significant over-representation of Fc gamma RIIIa-158F was found in patients with recurrence, compared with patients without recurrence, making Fc gamma RIIIA a candidate gene for recurrence risk of adult periodontitis.

Adult↗
PubMed1999

Difficulty in writing Japanese semantic characters in a 9-year-old boy with Williams syndrome.

A 9-year-old boy diagnosed as having Williams syndrome was evaluated using psychological test batteries in order to clarify his ability in language and visual cognition. The subject had difficulty in writing some of the Japanese semantic characters (called Kanji) which he could otherwise read and understand. Although he could write the small components of which the Kanji characters were composed, he could not locate these correctly. This phenomenon is considered to be very similar to the difficulty in copying a figure observed clinically. The Kaufmann Assessment Batteries for Children clearly revealed that the boy had difficulty with the sub-test of spatial memory compared to his average score for simultaneous processing. This result is considered to be closely related to the difficulty in copying figures or writing Kanji characters. On the Illinois Test of Psycholinguistic Abilities, the present authors found that the subject's vocabulary was relatively good, although semantic and pragmatic problems remained. Clarifying the strong and weak points of the abilities of such patients will help to determine the most appropriate mode of education for them.

Apraxia, Ideomotor↗
PubMed1999

A multiparametric analysis of occlusal and periodontal jaw reflex characteristics in adult skeletal mandibular protrusion before and after orthognathic surgery.

Periodontal jaw reflex, duration of percussion sounds, tooth mobility, and time-moment analysis of occlusal contacts by the T-scan system were recorded in seven pre-orthognathic surgery patients and six post-orthognathic surgery patients over a 2-year period. The results showed that: (i) reflex response to the pressure applied to the upper right central incisor in the lingolabial direction varied, depending on the background jaw-clenching force (BCF) of the same-sided first molar. The BCF level required to elicit excitatory reflexes was only 0 kgf, and inhibitory reflexes were clearly elicited with a BCF of 1 kgf and beyond before orthognathic surgery. After orthognathic surgery BCF levels required to elicit excitatory reflexes were 0-4 kgf, and inhibitory reflexes were elicited with a BCF of 6 kgf and above; (ii) duration of percussion sounds determined via an occlusal sound analyser decreased in both the upper right central incisor and upper right first molar while tooth mobility measured by 'Periotest(R)' increased in the upper right central incisor, but did not change in the same-sided first molar after orthognathic surgery; (iii) the time moments of occlusal contacts were symmetrical toward the midsagittal axis of the occlusal plane after orthognathic surgery. The centre of the anterioposterior occlusal contacts did not differ between pre- and post-orthognathic surgery groups.

Adolescent↗
PubMed1999

Primary low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma with polypoid appearance. Polypoid gastric MALT lymphoma: A clinicopathologic study of eight cases.

In the current study, we report eight cases with primary low-grade gastric mucosa-associated lymphoid tissue (MALT) lymphoma endoscopically characterized by polypoid lesions in order to highlight their clinicopathologic significance. Four patients were male, their ages ranging from 40 to 78 years old. The resected specimens revealed a histology of low-grade MALT lymphoma characterized by dense lymphocytic infiltration predominantly in the submucosa and a relatively monotonous proliferation of centrocyte-like cells with reactive follicles and infrequent lymphoepithelial lesions. The tumor cells were of CD5-, CD10-, CD20+, BCL2+ and cycline D1- phenotype, and showed a monoclonal rearrangement of immunoglobulin heavy chain genes in the five of six cases examined. Interestingly, Helicobacter pylori (H. pylori) was detected in three (37.5%) of the eight patients, which was significantly lower than previous reports. Two of the H. pylori-positive cases initially underwent H. pylori eradication, but showed no change in their lymphomas after the cure of H. pylori infection. The clinicopathologic findings of the present cases appeared to closely resemble those of colorectal MALT lymphoma with a polypoid appearance and few association of H. pylori infection in their pathogenesis. These gastric polypoid cases may merit separate consideration because of the therapeutic problems they pose.

Adult↗
PubMed1999

Sugar-branched-cyclodextrins as injectable drug carriers in mice.

The purpose of this study was to investigate stable complexation of drug in blood by sugar-branched-beta-cyclodextrins (beta-CDs) such as glucose (glu)- or galactose (gal)-branched-beta-CDs and the pharmacokinetic disposition of drug in sugar-branched-beta-CD complex. Complexation of steroidal drugs in sugar-branched-beta-CDs and their replacement by cholesterol were measured. The complexes of dexamethasone/glucosyl-beta-CDs (dexamethasone/glu-beta-CD or dexamethasone/glu-glu-beta-CD) were not replaced by cholesterol, which is a representative endogenous compound, whereas the complex of dexamethasone/beta-CD was replaced by cholesterol. The same results were obtained in steroidal drugs such as hydrocortisone, triamcinolone, and prednisolone. Thus, the use of glu-beta-CD and glu-glu-beta-CD permitted the stable complexation of the drug in water. Stability constants of dexamethasone/glu-glu-beta-CD and dexamethasone/gal-glu-beta-CD complexes are the same, which means that the sugar moiety of the side chain in beta-CD has little effect on stability constants. After the dexamethasone/gal-glu-beta-CD complex or the dexamethasone/glu-glu-beta-CD complex (dexamethasone: 1 mg/body) was administered intravenously to mice, dexamethasone concentrations in liver tissue and blood were measured. The dexamethasone/gal-glu-beta-CD complex (66.1 +/- 1.7 micrograms as dexamethasone/gram of liver tissue) was distributed to liver tissue significantly more than the dexamethasone/glu-glu-beta-CD (beta-CD) complex (59.9 +/- 1.0 micrograms as dexamethasone/gram of liver) at 30 min after administration (p < .05). Sugar-branched-beta-CD gave a water-soluble and stable complex for dexamethasone and changed the disposition of dexamethasone. Sugar-branched-beta-CDs are potentially excellent carriers for a steroidal injectable formulation.

Animals↗
PubMed1999

The non-NMDA glutamate receptor antagonist CNQX augments lidocaine antinociception through a spinal action in rats.

UNLABELLED: Non-NMDA glutamate receptor antagonists produce antinociceptive effects, but the antinociceptive interaction between non-NMDA glutamate receptor antagonists and local anesthetics has not been demonstrated. We designed this study to evaluate the antinociceptive effects of a non-NMDA glutamate receptor antagonist and its interaction with lidocaine in rats. Intrathecal catheters were implanted at the L4-5 level in rats. The tail flick (TF) and colorectal distension (CD) tests were used to assess somatic and visceral antinociceptive effects, respectively. The TF latency and CD threshold were measured before and for 180 min after the intrathecal administration of lidocaine (20-100 micrograms), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) (0.4-4.0 micrograms), a combination of CNQX (0.2-0.6 microgram) and lidocaine (10-30 micrograms), or isotonic sodium chloride solution. The TF latency and CD threshold were converted to the percent maximal possible effect (%MPE). To determine synergistic interaction, isobolographic analysis was used. Lidocaine or CNQX increased %MPEs in both the TF and CD tests. The coadministration of CNQX 0.4 microgram and lidocaine 20 micrograms, which had no effect by alone, significantly increased %MPEs in the TF and CD tests for 30 min and 10 min, respectively. Isobolographic analysis revealed the synergistic antinociception of CNQX and lidocaine in the TF test. Motor impairment was not observed after that combination. We conclude that CNQX and lidocaine produce synergistic analgesia on somatic and visceral pain at the spinal level. IMPLICATIONS: We investigated the antinociceptive effects of 6-cyano-7-nitroquinoxaline-2,3-dione and its interaction with lidocaine at the spinal level in rats. Intrathecal 6-cyano-7-nitroquinoxaline-2,3-dione produced both somatic and visceral antinociception, and its coadministration with lidocaine showed synergistic antinociceptive effects.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1999

The interaction of antinociceptive effects of morphine and GABA receptor agonists within the rat spinal cord.

UNLABELLED: Previous reports indicate that there may be an interaction between gamma-aminobutyric acid receptors and opioid receptors systems within the spinal cord, the antinociceptive effects of which have not been elucidated. We examined the effects of intrathecally coadministered morphine and muscimol or baclofen on somatic and visceral antinociception in rats. The tail flick (TF) test and colorectal distension (CD) test were used to assess somatic and visceral antinociceptive effects, respectively. Motor function was also assessed. The measurements were performed for 180 min after the intrathecal administration of morphine (0.1-10 micrograms), muscimol (0.2-10 micrograms), baclofen (0.03-1 microgram), combination of morphine and muscimol or baclofen, or saline. Morphine, muscimol, or baclofen increased both TF latency and CD threshold in a dose-dependent fashion. Although morphine 0.1 microgram, muscimol 0.2 microgram, or baclofen 0.03 microgram alone did not significantly increase TF latency and CD threshold, the combination of morphine 0.1 microgram and muscimol 0.2 microgram or baclofen 0.03 microgram significantly increased both TF latency and CD threshold. The coadministration of muscimol or baclofen increased the antinociceptive effects of morphine in intensity and duration. None of the rats showed motor dysfunction after the coadministration of morphine and muscimol 0.2 microgram, although muscimol produced motor paralysis of the lower limbs in a dose-dependent fashion. Those results suggest a clinical relevance of the coadministration of mu-opioids and GABA receptor agonists for pain control. IMPLICATIONS: We examined the antinociceptive interaction between morphine and muscimol or baclofen at the spinal level in rats. Intrathecal muscimol or baclofen potentiated both somatic and visceral antinociceptive effects of morphine.

Analgesics, Opioid↗