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H Imai

Publications and source records attributed to H Imai.

At least 19 recordsLinked to original sources
PubMed2006

Calcium phosphate formation on titanium by low-voltage electrolytic treatments.

Electrochemical treatments are expected to be effective for the coating of calcium phosphate ceramics to a titanium substrate. In the present study, two types of chronoamperometry with a step potential and a cyclic wave potential at low voltage (up to 2.0 V) and low current density were performed in Hanks' solution to modify the surface characteristics of titanium. Titanium oxide film formed by self-passivation, that formed as reconstructed film during electrochemical treatments, and a calcium phosphate layer precipitated through treatments were characterised by X-ray photoelectron spectroscopy. The thickness and compositions of the surface films and layers were quantified from the XPS results. Calcium phosphate formation during immersion in Hanks' solution for 1.0 Ms was evaluated by scanning electron microscopy with energy-dispersive X-ray spectrometry. The results confirmed that the electrolytic treatments in this study were effective to accelerate calcium phosphate formation on titanium in Hanks' solution in spite of their lower voltage than conventional methods. The results also suggested that the hydroxyl group in the surface oxide film might contribute to the formation of calcium phosphate. This technique is a promising process for the treatment of thin titanium materials.

Calcium Phosphates↗
PubMed2006

Different transitions of multifocal electroretinogram recordings between patients with age-related macular degeneration and polypoidal choroidal vasculopathy after photodynamic therapy.

AIM: To compare and evaluate the transitions in retinal function after photodynamic therapy (PDT) between age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) using multifocal electroretinograms (mfERGs). METHODS: 10 eyes with choroidal neovascularisation (CNV) secondary to AMD and 11 eyes with CNV secondary to PCV were included in the study. mfERGs were recorded before PDT, and 1 week and 3 months after PDT. mfERG recordings were acquired by a Veris system (V.3.1.3) using a 103 hexagon stimulus. The first-order kernel was used to calculate amplitudes and latencies. Mean amplitudes and latencies from two central rings rated 0-4 degrees of visual angle were analysed and compared with each disease. RESULTS: In AMD, the mean first negative peak (N1) amplitudes tended to decrease, and the mean first positive peak (N1P1) amplitudes reduced to significant levels (p = 0.047) 1 week after PDT. 3 months after PDT, there were no significant differences in the mean N1 and N1P1 amplitudes compared with pre-PDT values. In PCV, there were no significant changes in the mean N1 and N1P1 amplitudes 1 week after treatment. However, 3 months after PDT, mean amplitudes showed significant increases in N1 (p = 0.008) and N1P1 (p = 0.006) amplitudes compared with pre-PDT values. CONCLUSIONS: mfERG recording transitions are different between patients with AMD and those with PCV. In patients with AMD, these results may show transient impairments in retinal function 1 week after PDT, but in those with PCV, the efficacy of PDT is superior to the impairment after PDT.

Aged↗
PubMed2006

Apoptosis-independent poor morphology of bovine embryos produced by multiple ovulation.

In multiple ovulation and embryo transfer (MOET) programmes in cattle, a considerable number of morphologically poor-quality embryos continue to be produced; this is one of the limiting factors of the technique. Apoptosis has often been implicated in developmental arrest and fragmentation; these are regarded as poor traits of embryonic quality in mammalian pre-implantation embryos. In the present study, apoptosis was assessed in morphologically poor-quality embryos in comparison with good-quality embryos that were recovered from a MOET programme. Retarded embryos (two to 16 cell stage), morulae with severe fragmentation and morphologically good-quality morulae recovered from superstimulated cows at day 7 post-insemination were subjected to TdT-mediated dUTP nick-end labelling (TUNEL) and Hoechst staining. Cell nuclei that showed both TUNEL staining and apoptotic morphology were considered to be apoptotic. Apoptotic index (AI) was calculated as the percentage of apoptotic cells per embryo. Fifteen of 17 retarded embryos and 10 of 15 morphologically poor-quality morulae did not show signs of apoptosis. The mean AIs in the morphologically poor-quality embryos (two to 16 cell stage, 2.2%; poor morulae, 1.3%) were as low as that in the good-quality embryos (2.9%). These results suggest that another mode of developmental arrest and/or fragmentation that is independent of apoptosis occurs in morphologically poor-quality embryos recovered from MOET programmes.

Animals↗
PubMed2006

Expression of beta-defensin-2 in human gingival epithelial cells in response to challenge with Porphyromonas gingivalis in vitro.

BACKGROUND AND OBJECTIVE: Human beta-defensin-2 (hBD-2) is an antimicrobial peptide that is produced by epithelial cells after stimulation with microorganisms and inflammatory mediators. Compared with gram-positive bacteria, gram-negative bacteria, which are typically detected in the periodontal pockets in periodontitis, elicit a stronger antibacterial peptide response of hBD-2 by epithelial cells. The purpose of this study was to investigate the expression of hBD-2 and relationships between it and inflammatory mediators in human gingival epithelial cells (HGEC) in response to challenge with Porphyromonas gingivalis in vitro. MATERIAL AND METHODS: mRNA expression of hBD-2 in HGEC stimulated with or without P. gingivalis was assessed using a semiquantitative reverse transcription-polymerase chain reaction. Primary cultured HGEC were activated by live P. gingivalis, and inflammatory cytokine production was examined using an enzyme-linked immunosorbent assay. RESULTS: The level of hBD-2 mRNA in HGEC treated with P. gingivalis increased with exposure time. After 48 h, the mRNA in P. gingivalis was significantly increased compared with that in control HGEC. The interleukin-8 production rate was much greater in stimulated HGEC than in the control HGEC, almost always showing a significant difference after 3 h. The production of interleukin-1beta was not increased as much as that of interleukin-8. CONCLUSION: These findings suggest that the expression of hBD-2 in HGEC is P. gingivalis-dependently induced and is likely to be connected with the initial stage of the inflammatory response.

Cells, Cultured↗
PubMed2006

Abilities of cumulus and granulosa cells to enhance the developmental competence of bovine oocytes during in vitro maturation period are promoted by midkine; a possible implication of its apoptosis suppressing effects.

We previously reported that when midkine (MK), a heparin-binding growth differentiation factor was used in in vitro maturation (IVM) culture of bovine cumulus-enclosed oocytes (CEOs), their developmental competence to the blastocyst stage after in vitro fertilization (IVF) was enhanced and the effect of MK might be mediated by its action upon mural granulosa cells and cumulus cells that closely surround the oocyte. In the present study, when denuded oocytes (DOs) were matured in IVM medium with or without MK (200 ng/ml) in the presence or absence of isolated cumulus cell masses and subjected to IVF, the enhancing effects of MK on the developmental competence of DOs to the blastocyst stage after IVF were exerted only in the presence of cumulus cells. In addition, we prepared the conditioned media of granulosa cells cultured with or without 200 ng MK/ml (CMMK+ or CMMK- respectively) and examined their effects on the IVM of DOs in terms of their developmental competence to the blastocyst stage after IVF. The supplementation of CMMK+ into IVM medium at 40% (v/v) significantly enhanced the blastocyst development compared with the no additive control and the CMMK- supplemented groups. Furthermore, the effects of MK during IVM of bovine CEOs on the cumulus cell apoptosis were investigated. CEOs were cultured up to 24 h in IVM medium without (control) or with 200 ng MK/ml. The genomic DNA was extracted from CEOs at 0, 6, 12, 18 and 24 h of IVM and subjected to ligation-mediated PCR (LM-PCR) to detect the apoptotic internucleosomal DNA fragmentation. DNA fragmentation was scarcely detected at the start of IVM, whereas it increased time-dependently as the IVM culture progressed. The degree of the fragmentation was significantly lower in the MK-treatment group compared with the control group at 18 and 24 h of IVM. The apoptosis-suppressing effect of MK on cumulus cells was further confirmed in situ by using TUNEL on CEOs. In conclusion, data from the present study further confirmed that MK enhances the developmental competence of bovine oocytes via cumulus and granulosa cells. It was also demonstrated that MK suppresses the apoptosis that occurs in cumulus cells during the period of IVM of bovine CEOs. The putative soluble factor(s) from cumulus cells was suggested from the experiment using CMMK+ . MK may promote the production of such factors in part by its anti-apoptotic effects on cumulus cells.

Animals↗
PubMed2006

Analysis of the NPHP genes in two Japanese patients with suspected sporadic juvenile or adolescent nephronophthisis.

BACKGROUND: Mutations in 3 genes (NPHP1, NPHP3 and NPHP4) have been identified in patients with juvenile or adolescent nephronophthisis (NPHP) without extrarenal involvement, mainly in patients from western countries. In this study, we analyzed mutations in the NPHP genes of 2 Japanese patients with suspected sporadic juvenile or adolescent NPHP without extrarenal involvement. METHODS: A renal biopsy was performed in the 2 patients. Genomic DNA was prepared from peripheral blood mononuclear cells of the patients and their family members. The above NPHP genes were examined by deletion analysis or direct automated sequencing of polymerase chain reaction-amplified DNA products. RESULTS: Histological findings in the patients were compatible with those of NPHP. In 1 patient, we identified a novel deletion mutation including about half of exons of the NPHP1 gene. In another patient, there was no mutation in the NPHP genes examined. CONCLUSIONS: We found a novel NPHP1 deletion in 1 patient. To our knowledge, this is the second Japanese NPHP case in which genetic diagnosis was made.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Coupled charge-spin dynamics of the magnetoresistive pyrochlore TI2Mn2O7 probed using ultrafast midinfrared spectroscopy.

Optical-pump midinfrared probe spectroscopy is used to investigate coupled charge-spin dynamics in the magnetoresistive pyrochlore TI(2)Mn(2)O(7). We find that the temporal persistence of the photoexcited carrier density is strongly influenced by spin disorder above and below the ferromagnetic Curie temperature. Our results are consistent with a picture whereby spin disorder leads to spatial segregation of the initially excited Tl 6s-O 2p electron-hole pairs, effectively reducing the probability for recombination. This further implies that colossal magnetoresistance in these materials may be driven primarily by Mn t(2g) spin disorder.

Journal Article↗
PubMed2005

Cytokines participate in neuronal death induced by trimethyltin in the rat hippocampus via type II glucocorticoid receptors.

We investigated the role of IL-1alpha and IL-1beta expressed in the reactive gliosis following hippocampal damage induced by trimethyltin (TMT). IL-1alpha immunoreactivity was expressed earlier in small glial cells on day 4 post-TMT, while IL-1beta expression was obvious in large swollen glial cells on day 14 post-TMT. Both IL-1alpha and IL-1beta immunoreactivities were double-labeled with astrocyte marker, vimentin, but not with a microglia marker, OX-42. The expression of both IL-1alpha/beta was enhanced by adrenalectomy (ADX) prior to TMT administration. Corticosterone (CORT) or dexamethasone (DEX) supplementation not only cancelled effects of ADX, but also partially reversed TMT-induced enhancement of IL-1alpha/beta expressions. These changes coincided with TMT-induced neuronal death in CA3 pyramidal cells of the hippocampus. It is suggested that IL-1alpha/beta expressed in reactive astrocytes participate in TMT neurotoxicity via type II glucocorticoid receptors.

Adrenalectomy↗
PubMed2005

Identification of metabolites of [14C]zonampanel, an a-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor antagonist, following intravenous infusion in healthy volunteers.

This study determined the pharmacokinetics, metabolism and excretion of an a-amino-3-hydroxy-5-methylisoxazole-4-propionate receptor antagonist zonampanel monohydrate (YM872) after intravenous infusion of [14C]YM872 at 1 mg kg-1 h-1 for 2 h to four healthy male volunteers. Mean pharmacokinetic parameters of unchanged YM872 were 0.78 h for terminal half-life, 25.9 l h-1 for total clearance, 22.9 l h-1 for renal clearance, and 15.6 l for volume of distribution at steady-state. Urinary excretion of radioactivity accounted for 94.9% of the dose, and faecal excretion for only 0.5% of the dose. Measurement of YM872 concentrations by a high-performance liquid chromatography (HPLC)-ultraviolet method and radiometric HPLC metabolite profiling revealed that almost all of [14C]YM872 was excreted unchanged in the urine and that unchanged [14C]YM872 was the major circulating [14C] component in the plasma. Two minor metabolites, H1 and H2, detected in the urine and identified as the same chemical structures as those of the rat urinary metabolites, have a hydroxyamino group and an amino group, respectively, which were probably formed by reduction of the nitro group of YM872. These results show that virtually all of the administered YM872 remains unchanged, with urinary excretion representing the major elimination pathway. The high renal clearance implies tubular secretion of this drug.

Adolescent↗
PubMed2004

Effects of a synthetic progestogen, altrenogest, on oestrus synchronisation and fertility in miniature pigs.

Groups of six, six and eight miniature gilts, respectively, received 5, 10 or 15 mg/day of altrenogest for 18 days, and the numbers of corpora lutea and residual follicles were counted approximately 14 days after the treatment by an exploratory laparotomy. They were compared with the numbers in a control group of eight gilts which were examined six to eight days after oestrus. The interval between the last dose of altrenogest and the onset of oestrus increased with the dose of altrenogest, and was significantly longer after the treatments with 10 or 15 mg/day than after 5 mg/day (P < 0.01). Significantly more corpora lutea were observed in the gilts receiving 5 or 10 mg/day of altrenogest than in the control gilts (P < 0.1). Groups of six, seven and six miniature gilts that had respectively received 5, 10 or 15 mg/day of altrenogest were artificially inseminated; four, six and five of the gilts in these groups farrowed, and their mean (sd) litter sizes were 5.5 (2.4), 6.8 (1.2) and 5.0 (2.3), respectively. All six of a group of control gilts farrowed and their mean litter size was 5.8 (1.2).

Animals↗
PubMed2004

Cytokines participate in neuronal death induced by trimethyltin in the rat hippocampus via type II glucocorticoid receptors.

We investigated the role of IL-1alpha and IL-1beta expressed in the reactive gliosis following hippocampal damage induced by trimethyltin (TMT). IL-1alpha immunoreactivity was expressed earlier in small glial cells on day 4 post-TMT, while IL-1beta expression was obvious in large swollen glial cells on day 14 post-TMT. Both IL-1alpha and IL-1beta immunoreactivities were double-labeled with astrocyte marker, vimentin, but not with a microglia marker, OX-42. The expression of both IL-1alpha/beta was enhanced by adrenalectomy (ADX) prior to TMT administration. Corticosterone (CORT) or dexamethasone (DEX) supplementation not only cancelled effects of ADX, but also partially reversed TMT-induced enhancement of IL-1alpha/beta expressions. These changes coincided with TMT-induced neuronal death in CA3 pyramidal cells of the hippocampus. It is suggested that IL-1alpha/beta expressed in reactive astrocytes participate in TMT neurotoxicity via type II glucocorticoid receptors.

Adrenalectomy↗
PubMed2004

Glutathione S-transferase (GST) M1, T1 and N-acetyltransferase 2 (NAT2) polymorphisms and urothelial cancer risk with tobacco smoking.

The objective of this study was to examine the association between the genetic polymorphism of glutathione S-transferase (GST) M1, T1 and N-acetyltransferase 2 (NAT2) genes and urothelial cancer risk in relation to smoking status. In this study, 325 Japanese patients with urothelial transitional cell carcinoma and 325 healthy controls were compared for frequencies of GSTM1, T1 and NAT2 genotypes. The frequencies of GSTM1 null genotype and NAT2 slow genotype were significantly higher in the cases than in the controls (adjusted odds ratio (OR) 1.37, 95% confidence interval (CI) 1.01-1.87, adjusted OR 3.09, 95% CI 1.69-5.63, individually). Furthermore, the risk of GSTM1 null genotype and NAT2 slow genotype was higher among smokers (adjusted OR 1.48, 95% CI 1.01-2.15, adjusted OR 4.28, 95% CI 1.96-9.36, individually). The regression analysis of cancer risk as a function of the amount of smoking showed that the susceptibility of people who had GSTM1 null genotype increased from 45 pack-years, while the susceptibility of people with NAT2 intermediate or slow genotype increased rapidly from 25 pack-years, compared with non-smokers. A multiplicative interaction between NAT2 intermediate or slow genotype and pack-years of smoking was found (P<0.001), but GSTM1 null genotype was not (P=0.06). Our results indicate that the GSTM1 null genotype and NAT2 intermediate or slow genotype are associated with an increased risk of urothelial cancer in relation to smoking amounts. Furthermore, the interaction between NAT2 intermediate or slow genotype and pack-years of smoking has a strong impact on urothelial cancer.

Aged↗
PubMed2004

Burnout and work environments of public health nurses involved in mental health care.

AIMS: (1) To examine whether prevalence of burnout is higher among community psychiatric nurses working under recently introduced job specific work systems than among public health nurses (PHNs) engaged in other public health services. (2) To identify work environment factors potentially contributing to burnout. METHODS: Two groups were examined. The psychiatric group comprised 525 PHNs primarily engaged in public mental health services at public health centres (PHCs) that had adopted the job specific work system. The control group comprised 525 PHNs primarily engaged in other health services. Pines' Burnout Scale was used to measure burnout. Respondents were classified by burnout score into three groups: A (mentally stable, no burnout); B (positive signs, risk of burnout); and C (burnout present, action required). Groups B and C were considered representative of "burnout". A questionnaire was also prepared to investigate systems for supporting PHNs working at PHCs and to define emergency mental health service factors contributing to burnout. RESULTS: Final respondents comprised 785 PHNs. Prevalence of burnout was significantly higher in the psychiatric group (59.2%) than in the control group (51.5%). Responses indicating lack of job control and increased annual frequency of emergency overtime services were significantly correlated with prevalence of burnout in the psychiatric group, but not in the control group. CONCLUSIONS: Prevalence of burnout is significantly higher for community psychiatric nurses than for PHNs engaged in other services. Overwork in emergency services and lack of job control appear to represent work environment factors contributing to burnout.

Adult↗
PubMed2004

A nonsense mutation (R220X) in the alpha-galactosidase A gene causes typical Fabry disease in both genders.

BACKGROUND: Fabry disease is an X-linked recessive disorder resulting from a deficiency of lysosomal alpha-galactosidase A (alpha-Gal A). Chronic renal failure is an important cause of death in patients with Fabry disease. We report on patients with Fabry disease (a hemizygous male and his mother) due to a nonsense mutation (R220X) in the alpha-Gal A gene. METHODS: The proband, a 41-year-old man, and his 71-year-old mother presented with renal and cardiac manifestations of Fabry disease. Histological examination and molecular analysis of the alpha-Gal A gene were performed. RESULTS: Typical histological findings of Fabry disease were observed in a renal biopsy specimen from the proband and in renal and myocardial necropsy specimens from the mother. Sequencing of a full-length alpha-Gal A cDNA from the proband indicated a C-T transition at codon 220, resulting in substitution of the predictable termination for arginine (R220X). Examination of genomic alpha-Gal A DNA revealed that the proband was a hemizygote and the mother was a heterozygous carrier for the mutation. CONCLUSION: This is the first detailed report of family members with Fabry disease due to a nonsense mutation (R220X) in the alpha-Gal A gene. Our study indicates that this mutation causes the typical disease in both genders.

Adult↗
PubMed2003

In situ hybridization and immunohistochemistry of versican, aggrecan and link protein, and histochemistry of hyaluronan in the developing mouse limb bud cartilage.

We investigated the expression pattern of versican, aggrecan, link protein and hyaluronan in the developing limb bud cartilage of the fetal mouse using in situ hybridization and/or immunohistochemistry. Versican mRNA and immunostaining were detected in the mesenchymal cell condensation of the future digital bone at E13. Versican mRNA expression rapidly disappeared from the tibial cartilage, as cartilage formation progressed during E13-15, but the immunostaining was gradually replaced by aggrecan immunostaining from the diaphysis. Immunostaining for both molecules thus had a 'nega-posi' pattern and consequently versican immunostaining was still detected at the epiphyseal end at E15. This result indicated that versican functions as a temporary framework in newly formed cartilage matrix. An aggrecan-positive region within the cartilage invariably had intense hyaluronan staining, whereas a versican-positive region also had affinity for hyaluronan within the cartilage, but not in the mesenchymal cell condensation. Therefore, the presence of versican aggregates was not confirmed in the developing limb bud cartilage. Furthermore, although link protein was more closely related with aggrecan than versican during limb bud cartilage formation, there was a discrepancy between the expression of aggrecan and link protein in tibial cartilage at E15. In particular, only a link protein-positive region was present in the marginal area of the metaphysis and the epiphysis at this stage. This finding may indicate a novel role for link protein.

Aggrecans↗
PubMed2003

Amyloid A-type renal amyloidosis in a patient with sarcoidosis: report of a case and review of the literature.

A 53-year-old man developed chronic renal failure during a protracted course of sarcoidosis. A renal biopsy showed Congo red-positive homogenous deposits in the subendothelial space of glomerular capillary walls and arterial walls. On electron microscopy, amyloid fibrils were observed in the deposits. Immunohistochemistry showed positive staining for amyloid A (AA) protein. Treatment with prednisolone resulted in poor response, followed by progressive deterioration of renal function requiring hemodialysis. To our knowledge, there are 5 cases with histologically proven renal amyloidosis accompanied by sarcoidosis. Prognosis in these patients is extremely poor. AA-type amyloidosis should be considered as a rare renal complication in the setting of long-standing sarcoidosis.

Amyloidosis↗