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Biomedical subjects

H Hamano

Publications and source records attributed to H Hamano.

At least 19 recordsLinked to original sources
PubMed2005

Reduction of osteocalcin expression in aged human dental pulp.

AIM: To investigate the expression of osteocalcin mRNA in young and in aged human dental pulp tissue to determine the characteristics of osteocalcin expression. METHODOLOGY: Human dental pulp tissues of the third molars were obtained from healthy young (17-23 years) and aged (>50 years) subjects, and total RNA was extracted. Osteocalcin mRNA expression was determined by RT-PCR and by quantitative real-time RT-PCR (QRT-PCR). The threshold cycle (Ct) value, which reflects the amount of PCR, was calculated and the difference between the value in young and aged pulp was statistically analysed. RESULTS: Osteocalcin mRNA was detected in all samples of human dental pulp tissue homogenates by RT-PCR analysis. Osteocalcin mRNA was expressed in young adult dental pulp but was decreased in aged human dental pulp. QRT-PCR analysis also showed a reduced expression of osteocalcin mRNA in aged human pulp. Expression of osteocalcin in young human pulp was significantly higher (about sixfold) than in aged pulp (P<0.01, Mann-Whitney U-test). CONCLUSION: Reduction of osteocalcin expression may be associated with the loss of viability in human dental pulp tissue, and may be a characteristic of aged human dental pulps.

Adolescent↗
PubMed2004

Reduction of connexin 43 expression in aged human dental pulp.

AIM: To investigate the expression of connexin 43 (CX43) mRNA in young and old human dental pulp tissues to determine the characteristics of CX43 expression. METHODOLOGY: Samples were obtained from human dental pulp of healthy young (17-23 years) and aged (>50 years) subjects. CX43 expression was determined by RT-PCR and by quantitative real-time RT-PCR (QRT-PCR). The threshold cycle (Ct) value, which reflects the amount of PCR, was calculated and the difference between value in the young pulp and that in the aged pulp was statistically analysed. RESULTS: RT-PCR analysis of human dental pulp tissue detected CX43 mRNA in all the samples. CX43 was abundantly expressed in young adult dental pulp, but expression of CX43 mRNA was dramatically decreased in aged human dental pulp. QRT-PCR analysis also showed the reduced expression of CX43 in aged pulp, and expression of CX43 in young pulp was significantly higher (about 10-fold, P < 0.01, Mann-Whitney U-test). CONCLUSION: Reduction of CX43 expression may be associated with the loss of viability in human dental pulp, and is considered as one characteristic of aged pulp.

Adolescent↗
PubMed2001

High serum IgG4 concentrations in patients with sclerosing pancreatitis.

BACKGROUND: Sclerosing pancreatitis is a unique form of pancreatitis that is characterized by irregular narrowing of the main pancreatic duct, lymphoplasmacytic inflammation of the pancreas, and hypergammaglobulinemia and that responds to glucocorticoid treatment. Preliminary studies suggested that serum IgG4 concentrations are elevated in this disease but not in other diseases of the pancreas or biliary tract. METHODS: We measured serum IgG4 concentrations using single radial immunodiffusion and an enzyme-linked immunosorbent assay in 20 patients with sclerosing pancreatitis, 20 age- and sex-matched normal subjects, and 154 patients with pancreatic cancer, ordinary chronic pancreatitis, primary biliary cirrhosis, primary sclerosing cholangitis, or Sjögren's syndrome. Serum concentrations of immune complexes and the IgG4 subclass of immune complexes were determined by means of an enzyme-linked immunosorbent assay with monoclonal rheumatoid factor. RESULTS: The median serum IgG4 concentration in the patients with sclerosing pancreatitis was 663 mg per deciliter (5th and 95th percentiles, 136 and 1150), as compared with 51 mg per deciliter (5th and 95th percentiles, 15 and 128) in normal subjects (P<0.001). The serum IgG4 concentrations in the other groups of patients were similar to those in the normal subjects. In patients with sclerosing pancreatitis, serum concentrations of immune complexes and the IgG4 subclass of immune complexes were significantly higher before glucocorticoid therapy than after four weeks of such therapy. Glucocorticoid therapy induced clinical remissions and significantly decreased serum concentrations of IgG4, immune complexes, and the IgG4 subclass of immune complexes. CONCLUSIONS: Patients with sclerosing pancreatitis have high serum IgG4 concentrations, providing a useful means of distinguishing this disorder from other diseases of the pancreas or biliary tract.

Adult↗
PubMed2000

Estrogen-induced resistance to osteoblast apoptosis is associated with increased hsp27 expression.

Estrogen has been shown to protect osteoblastic cells from apoptosis. Similarly, estrogen treatment preceding heat shock elevates heat shock protein 27 (hsp27) expression and increases thermoresistance in the murine estrogen receptor-transformed SMER14 osteoblastic cell line. Forced expression of hsp27 expression in other cell lines limits apoptosis. The purpose of this study was to examine the effects of estrogen on staurosporine-induced apoptosis in the context of hsp27 expression. Cell viability was measured by the MTT assay. Early apoptotic events were examined by fluorescent microscopy by using FITC-conjugated Annexin V staining. TUNEL labeling was used to compare the number of apoptotic nuclei following staurosporine treatment of estrogen pretreated or untreated cells. Estrogen treatment increased SMER14 cell viability, but not ROS17/2.8 cell viability, in the presence of staurosporine. Estrogen treatment also reduced annexin V staining and DNA fragmentation. Similar treatment increased SMER14 cell hsp27 levels. The concurrent reduction in induced apoptosis suggests a possible estrogenic mechanism for increasing and/or maintaining the number of viable osteoblasts in bone.

Apoptosis↗
PubMed2000

5-[4-(3,3-Dimethylbutoxycarbonyl)phenyl]-4-pentynoic acid and its derivatives inhibit ionotropic gamma-aminobutyric acid receptors by binding to the 4'-ethynyl-4-n-propylbicycloorthobenzoate site.

Acyclic noncompetitive antagonists of ionotropic gamma-aminobutyric acid (GABA) receptors, bearing an ester or ether linkage, were designed, synthesized, and assayed for their inhibition of the specific binding of [3H]4'-ethynyl-4-n-propylbicycloorthobenzoate (EBOB), a radiolabeled noncompetitive antagonist, to rat brain and housefly head membranes. 5-[4-(3,3-Dimethylbutoxycarbonyl)phenyl]-4-pentynoic acid (DBCPP), a butyl benzoate analogue, was found to competitively inhibit the binding of [3H]EBOB in rat brain membranes, with an IC50 of 88 nM. The potency conferred by the p-substituent decreased in the order C(triple bond)C(CH2)2COOH > C(triple bond)C(CH2)2COOCH3 > C(triple bond) CH > Br. Pentyl phenyl ethers were equally potent compared with butyl benzoates, while phenyl pentanoates and benzyl butyl ethers were less pont. These compounds were generally less active in housefly head membranes than in rat brain membranes. The introduction of an isopropyl group into the 1-position of the 3,3-dimethylbutyl group of a butyl benzoate and two benzyl butyl ethers caused an increase in potency in housefly GABA receptors, whereas this modification at the corresponding position of other compounds led to an unchanged or decreased potency. In the case of rat receptors, this modification resulted in a decrease in potency except for a phenyl pentanoate. To confirm that DBCPP interferes with GABA receptor function, we performed whole-cell patch clamp experiments with rat dorsal root ganglion neurons in the primary culture. Repeated co-applications of GABA and DBCPP suppressed GABA-induced whole-cell currents with an IC50 of 0.54 microM and a Hill coefficient of 0.7. These findings indicate that DBCPP and its derivatives inhibit ionotropic GABA receptors by binding to the EBOB site and that there might be structural difference in the noncompetitive antagonist-binding site between rat and housefly GABA receptors.

Animals↗
PubMed2000

Mitochondrial neurogastrointestinal encephalomyopathy: an autosomal recessive disorder due to thymidine phosphorylase mutations.

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder defined clinically by severe gastrointestinal dysmotility; cachexia; ptosis, ophthalmoparesis, or both; peripheral neuropathy; leukoencephalopathy; and mitochondrial abnormalities. The disease is caused by mutations in the thymidine phosphorylase (TP) gene. TP protein catalyzes phosphorolysis of thymidine to thymine and deoxyribose 1-phosphate. We identified 21 probands (35 patients) who fulfilled our clinical criteria for MNGIE. MNGIE has clinically homogeneous features but varies in age at onset and rate of progression. Gastrointestinal dysmotility is the most prominent manifestation, with recurrent diarrhea, borborygmi, and intestinal pseudo-obstruction. Patients usually die in early adulthood (mean, 37.6 years; range, 26-58 years). Cerebral leukodystrophy is characteristic. Mitochondrial DNA (mtDNA) has depletion, multiple deletions, or both. We have identified 16 TP mutations. Homozygous or compound heterozygous mutations were present in all patients tested. Leukocyte TP activity was reduced drastically in all patients tested, 0.009 +/- 0.021 micromol/hr/mg (mean +/- SD; n = 16), compared with controls, 0.67 +/- 0.21 micromol/hr/mg (n = 19). MNGIE is a recognizable clinical syndrome caused by mutations in thymidine phosphorylase. Severe reduction of TP activity in leukocytes is diagnostic. Altered mitochondrial nucleoside and nucleotide pools may impair mtDNA replication, repair, or both.

Adult↗
PubMed1999

Corneal thickness measurements with the Topcon SP-2000P specular microscope and an ultrasound pachymeter.

OBJECTIVE: To compare the reproducibility of measurements obtained with a new pachymetry instrument, the Topcon specular microscope (Topcon SP-2000P; Topcon America Corp, Paramus, NJ), with those obtained by ultrasound pachymetry. METHODS: Corneal thickness was measured in 40 eyes of 40 patients 3 times each with the Topcon SP-2000P and an ultrasound pachymeter (DGH 500, DGH Technology Inc, Exton, Pa) by 2 separate investigators. Comparisons included average thickness as measured by each instrument, average thickness for each instrument as measured by each investigator, and differences in thickness due to corneal abnormalities. RESULTS: Mean corneal thickness measured by the Topcon instrument was significantly less (32 microm; P<.001) than the mean value obtained with the ultrasound pachymeter. Similarly, mean values obtained with the 2 instruments by the 2 investigators were significantly different (P<.001 and .008 for investigators 1 and 2, respectively), with the Topcon value less than the ultrasound value in both cases. Both instruments detected abnormalities in corneal thickness equally well. However, the measurements obtained with the Topcon instrument by the 2 investigators were more consistent (no significant difference [P=.32]) than those obtained with the ultrasound unit (difference was significant [P=.02]). CONCLUSIONS: The new noncontact Topcon specular microscope provides measurements of corneal thickness that are somewhat less than those of ultrasound pachymetry, but that seem to be more consistent from one operator to another, possibly as a result of the elimination of observer bias induced by probe placement required by the ultrasound unit. This consistency may be important in the comparison of measurements by different operators over time in patients being followed up after refractive surgery or other therapeutic interventions.

Cornea↗
PubMed1998

Down-regulation of TSC-22 (transforming growth factor beta-stimulated clone 22) markedly enhances the growth of a human salivary gland cancer cell line in vitro and in vivo.

We have recently isolated TSC-22 (transforming growth factor beta-stimulated clone 22) cDNA as a new anticancer drug (Vesnarinone)-inducible gene in a human salivary gland cancer cell line, TYS. We conducted the present study to examine whether up-regulation or down-regulation of TSC-22 can affect the growth of TYS cells in vitro and in vivo. We constructed an expression vector containing sense- or antisense-oriented human TSC-22 cDNA under the transcriptional control of the SR alpha promoter. We cotransfected TYS cells with the sense or antisense expression vector and pSV2neo and obtained more than 200 G418-resistant colonies in each sense or antisense transfectant. Approximately 80% of representative G418-resistant clones expressed the transcripts from transfected sense or antisense TSC-22 cDNA. To avoid the clonal heterogeneity of the cells, we mixed all of the G418-resistant colonies together in each sense or antisense transfectant and examined the expression of TSC-22 protein, in vitro growth, and the tumorigenicity in nude mice. The expression of TSC-22 protein was examined by solid-phase ELISA using a specific antibody against recombinant TSC-22 protein. The expression of TSC-22 protein was up-regulated in the sense transfectants and down-regulated in the antisense transfectants. Contrary to our expectation, up-regulation of TSC-22 protein did not affect both in vitro and in vivo growth of TYS cells. However, down-regulation of TSC-22 markedly enhanced the growth of TYS cells in vitro and in vivo. Furthermore, we examined the expression of TSC-22 mRNA in several human salivary gland tumors. The mRNA expression of TSC-22 in benign and malignant salivary gland tumors was significantly decreased when compared to that in tumor-free salivary glands (P < 0.05; one-way ANOVA), and in some salivary gland tumors, the expression of TSC-22 mRNA was not detectable by reverse transcription-PCR. These results suggest that down-regulation of TSC-22 may play a major role on salivary gland tumorigenesis.

Animals↗
PubMed1998

In vivo evaluation of hsp27 as an inhibitor of actin polymerization: hsp27 limits actin stress fiber and focal adhesion formation after heat shock.

The role of hsp27 as an inhibitor of actin polymerization was considered in the context of the actin cytoskeleton and its relationship with focal adhesion formation. The aim of this study was to evaluate the potential effects of hsp27 on focal adhesion formation as a relevant biological consequence of actin stress fiber formation. When hsp27 was overexpressed in stably transfected cells, cell attachment was delayed and recovery of disrupted stress fibers and focal adhesions was limited. In ROS 17/2.8 cells, heat shock caused the reversible disruption of stress fibers and focal adhesions. The loss of stress fibers and focal adhesions was associated with reduced phosphotyrosine on the focal adhesion kinase (FAK). Microinjection of recombinant 6-His hsp27 and phosphorylated 6-His hsp27 was used to demonstrate that nonphosphorylated hsp27 prevented the recovery of stress fibers and focal adhesions. These results provide in vivo evidence that hsp27 acts as an inhibitor of actin polymerization that can alter cellular interactions with extracellular environments by perturbation of stress fibers, and subsequently focal adhesions.

Actin Cytoskeleton↗
PubMed1998

[Investigation of metal allergy to constituent elements of intraoral restoration materials].

Allergies caused by metals have been increasing. The number of patients visiting dentists with the chief complaint of metal allergy has also been increasing. From March 1994 to February 1997, 263 patients who complained of various symptoms visited our allergy clinic. Among them, 184 patients were suspected to have allergy caused by metals in dental restoration materials and were referred to the patch test. Among 165 patients', 128 were positives for metal allergy. Constituent elements of intraoral metals were analyzed in 107 of these 128 positive patients. The findings were as follows: 1. The most common five elements acting on the patients were Hg, Co, Ni, Cr, and Pd. 2. The most frequently used elements of dental restoration metal materials were Zn, Ag, Cu, Au, and Pd, and the alloy was Au-Ag-Pd alloy. 3. The highest tendency of coincidence between allergen and intraoral metals were observed among Co-Cr-Ni alloys and Pd, Ni, and Cr elements. 4. In case of palmoplantar pustulosis, allergen metals tended to be the same as intraoral metal elements.

Adolescent↗
PubMed1998

Active-MMP2 in cancer cell nests of oral cancer patients: correlation with lymph node metastasis.

We examined the gelatinolytic activity in human oral squamous-cell carcinoma tissues in order to evaluate the capability of intravasation and extravasation of cancer cells. By a microdissection-zymography, we demonstrated separately the gelatinolytic activities in cancer cell nests and stroma adjacent to the cancer cells. The gelatinolytic activities, such as pro-matrix metalloproteinase (MMP)9 and active-MMP2 in most of cancer cell nests were much higher than those of normal gingival epithelium. Moreover, the activities of active-MMP2 in cancer cell nests of metastatic cancers were significantly higher than those of non-metastatic cancers (p<0.05). These results suggest that active-MMP2 in cancer cells can be a predictive marker for metastasis formation in oral squamous-cell carcinoma patients.

Carcinoma, Squamous Cell↗
PubMed1998

Determination of oxygen tension on rabbit corneas under contact lenses.

PURPOSE: To determine oxygen tension (PO2) on rabbit corneas beneath rigid gas permeable (RGP), hydrogel, and silicone elastomer lenses under open- and closed-eye conditions and to demonstrate the relationship between PO2 and overnight corneal swelling response in the rabbit model. METHODS: An improved PO2 monitoring system (PO-2080) with a platinum-micro-wire-electrode was used to measure PO2. An ultrasonic pachymeter (DGH-2000) was used to measure corneal thickness after overnight wear. RESULTS: The relationship between PO2 and oxygen transmissibility (Dk/ L) of the contact lens was linear for Dk/L between 0 and 70 x 10(-9) (cm/ sec)(mLO2/mL x mmHg). For Dk/L greater than 70 x 10(-9), PO2 gradually reached a plateau at 120 mmHg for open-eye conditions and 20 mmHg for closed-eye conditions. PO2 was inversely related to the overnight corneal swelling, ranging from 5.1% swelling at PO2 113.5/17.5 mmHg (open/closed-eye) for a hyper Dk/L lens (125 x 10(-9)) to 15.1% swelling at PO2 10.4/5.1 mmHg for a low Dk/L lens (11.5 x 10(-9)). CONCLUSIONS: Polarographic determination of PO2 provides reliable information about the amount of oxygen available to the cornea under a lens for both open-eye and closed-eye conditions. The data demonstrate that it is not possible to achieve normal oxygen levels with contact lens wear, even when hyper Dk/L lenses are worn.

Animals↗