Biomedical subjects

H Ohno

Publications and source records attributed to H Ohno.

At least 109 records · Page 6Linked to original sources

PubMed2000

The effect of hybrid layer thickness on bond strength: demineralized dentin zone of the hybrid layer.

OBJECTIVES: The purpose of this study was to evaluate the correlation between hybrid layer thickness and bond strength using specimens acid-conditioned for varying lengths of time. METHODS: The dentin surfaces of human premolars, sectioned to remove the enamel from the labial surface, were conditioned with 35.0% phosphoric acid of an adhesive resin system (Scotchbond Multi-Purpose; 3M) for 15 (as directed by the manufacturer), 60, 120, or 180 s (experimental acid-conditioning times). The bonded specimens were then sectioned perpendicular to the adhesive interface to measure the hybrid layer thickness by SEM. The specimens for the micro-tensile test were sectioned perpendicular to the adhesive interface and trimmed to an hourglass-shape. Then, the micro-tensile test was performed at a crosshead speed of 1.0 mm/min. The bond strengths and hybrid layer thickness were statistically compared with Student's t-test (p < 0.05). All fractured surfaces were also observed by SEM. RESULTS: Significant differences between the groups exposed to acid for 15 and 60 s, and those exposed for 120 and 180 s were observed in hybrid layer thickness and bond strength (p < 0.05). SEM observation of the fractured surfaces revealed that a demineralized dentin zone without resin impregnation remained within the hybrid layer. SIGNIFICANCE: A demineralized dentin zone was formed in the bond structures after prolonged acid-conditioning, resulting in low bond strength. The shrinkage of the hybrid layer due to desiccation during the SEM examination process provided evidence of the presence of the demineralized dentin zone within the hybrid layer.

Acid Etching, Dental↗

PubMed2000

Effect of Pd or Au addition on age-hardening in AgMn-based alloys.

OBJECTIVE: The objective of this research was to characterize the age-hardening behavior of AgMn alloys modified with Au or Pd. These alloys are being studied as possible alternatives to Type III dental alloys. METHODS: The age-hardening reactions in Ag-37 at % Mn alloys with 5 at% Au or Pd were investigated by optical microscopy, electrical resistivity, X-ray diffraction and hardness tests. RESULTS: Optical microscopy showed no grain boundary precipitates formed after overaging. The maximum hardness reached by aging in all alloys is about 260 (Hv) and identical to that of traditional AgPdCu dental alloys. The precipitation reactions were retarded with the addition of 5 at% Au or Pd. X-ray diffraction studies suggest a fine precipitate, alpha-Mn, is dispersed within the grain interior. The activation energy for the precipitation reaction is 114 kJ/mol for the AgMn and AgMnAu alloys. This value is about one-half of the activation energy for volume diffusion of manganese in AgMn alloys. SIGNIFICANCE: The age-hardenable AgMn-based alloys modified with Au or Pd can achieve hardness values comparable to those of traditional AgPdCu alloys. Provided the in vivo corrosion resistance of these alloys is adequate, they show promise as a Cu-free alternative material for cast restorations.

Chemical Precipitation↗

PubMed2000

Fulminant hepatitis B following bone marrow transplantation in an HBsAg-negative, HBsAb-positive recipient; reactivation of dormant virus during the immunosuppressive period.

It is widely accepted that seroconversion of HBsAg to HBsAb indicates clearance of hepatitis B virus. We describe a 50-year-old man with chronic myelocytic leukemia who developed lethal hepatitis B 22 months after allo-BMT. He had been negative for HBsAg and positive for HBsAb before BMT. Hepatitis B virus latently existing in the liver cells before BMT proliferated during the immunosuppressed period causing fatal hepatitis. Recipients with positive HBsAb should be considered to have the potential for active hepatitis B to emerge after BMT. Bone Marrow Transplantation (2000) 25, 105-108.

Bone Marrow Transplantation↗

PubMed2000

Intrapulmonary concentrations of inflammatory cytokines in a mouse model of chronic respiratory infection caused by Pseudomonas aeruginosa.

We investigated the role of inflammatory cytokines in a mouse model of chronic Pseudomonas aeruginosa infection mimicking diffuse panbronchiolitis (DPB), and determined the effects of clarithromycin therapy on the production of these cytokines. The concentrations of IL-1beta, IL-2, IL-4, IL-5, interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) were measured serially in the lungs of mice with experimentally induced chronic respiratory P. aeruginosa infection until 60 days after inoculation. The concentrations of these cytokines during the course of the disease were significantly higher than baseline (before inoculation, P<0.01 for all cytokines). Clarithromycin significantly inhibited the production of IL-1beta and TNF-alpha in the lung (P<0.01). The same treatment also reduced the levels of other cytokines, albeit insignificantly. Treatment with anti-TNF-alpha antibody significantly reduced the number of pulmonary lymphocytes and concentration of IL-1beta in the lung (P<0.01), but did not change the number of viable bacteria. Our findings resemble those detected in bronchoalveolar lavage fluid of patients with DPB and indicate that inflammatory cytokines play an important role in chronic P. aeruginosa lung infection. Our results also show that macrolides modulated the production of these cytokines, ultimately reducing lymphocyte accumulation in the lung. Our data suggest that anti-TNF-alpha antibody might be a useful new strategy for the treatment of chronic respiratory P. aeruginosa infection.

Animals↗

PubMed2000

Effects of ageing on generation of ED2high major histocompatibility complex class II+ macrophages during cold stress.

The effects of cold stress (5 degrees C, 24 h) were investigated on the function and surface phenotype of peritoneal cells in the monocyte/macrophage lineage from young (8-10-week-old) and old (22-24-month-old) rats. The role of glucocorticoid (GC) in the immunomodulation by cold stress was also examined. The proportion of cells with a high density of ED2 (ED2high cells), expressing major histocompatibility complex (MHC) class II molecules, was significantly increased in peritoneal cells during cold stress in young, but not in old, rats. Antigen-presenting function was significantly higher in ED2high cells than in cells with a low density of ED2 (ED2low cells), thereby indicating that ED2high cells are at a functionally high level. While serum corticosterone concentration in old rats increased markedly after 3 h of cold stress, that in young rats did not vary substantially, and was followed by a significant decrease in both groups of rats after 24 h of cold stress. Administration of dexamethasone to young rats completely inhibited the increase of ED2high cells caused by cold stress. Meanwhile, the proportion of ED2high cells in young rats was significantly increased by adrenalectomy. Furthermore, nuclear translocation of a large amount of the GC receptor was observed in ED2low cells. These results suggest that cold stress enhances immune function in young rats, but not in old rats, and that the generation of ED2high cells are partly regulated by circulating GC level.

Adrenalectomy↗

PubMed2000

Comparison of muscle oxygen consumption measured by near infrared continuous wave spectroscopy during supramaximal and intermittent pedalling exercise.

The two purposes of the present study were 1) to determine the oxygen consumption in working skeletal muscle from the oxygenation measured by near-infrared continuous-wave spectroscopy (NIRcws) with the arterial occlusion method during the resting condition, INT(VT), and INT(MAX) and 2) to examine whether the decline rate of oxygenation is related to maximal oxygen uptake. Eight healthy males (aged 19.8 +/- 0.4 yr, height 166.9 +/- 17.4 cm, weight 62.1 +/- 2.5 kg, and maximal oxygen uptake [VO2max] 55.9 +/- 1.9 ml/kg x min(-1)) took part in this study. The oxygenation was measured by NIRcws during the Wingate anaerobic test (WAnT) and two intermittent pedalling exercises of VT (INT(VT)) and maximal (INT(MAX)) work intensity. The decline rates of oxygenation obtained during the resting condition, INT(VT), and INT(MAX) with arterial occlusion were 0.43 +/- 0.05%/sec, 4.94 +/- 0.31%/sec, and 8.16 +/- 0.38%/sec, respectively, and that during the WAnT without arterial occlusion was 8.73 +/- 0.49%/sec. The decline rate of oxygenation during the WAnTwas significantly (p < 0.0001) related to maximal oxygen uptake (VO2max). These findings indicate that O2 is utilized from the early phase, even during a supramaximal pedalling exercise, and that the oxidative metabolic capacity may be a factor contributing to supramaximal exercises. Therefore the arterial occlusion method with NIRcws is suitable for the evaluation of the muscle O2 consumption during exercise noninvasively.

Adult↗

PubMed2000

Detection of telomerase activity in biopsy specimens for diagnosis of biliary tract cancers.

BACKGROUND: Telomerase activity is detectable in more than 85% of primary cancers. We determined telomerase activity in biopsy specimens obtained from biliary tract cancers to evaluate the clinical application of telomerase activity detection in combination with p53 immunostaining and routine histologic examination. METHODS: Biopsy specimens obtained during percutaneous transhepatic cholangioscopy from 13 patients with cholangiocarcinoma, 3 patients with gallbladder carcinoma, and 4 patients with intrahepatic bile duct stones were evaluated by routine histologic examination, p53 immunostaining, and telomerase activity. Semiquantitative determination of telomerase activity was performed using a fluorescence-based telomeric repeat amplification protocol. RESULTS: Thirteen of 16 specimens of malignant tissue had detectable telomerase activity, whereas no specimen of nonmalignant tissue had detectable telomerase activity. A p53 overexpression was recognized by immunostaining in 9 of 16 samples with cancers. Combining both telomerase activity and p53 overexpression resulted in the detection of all cancer with a sensitivity of 100%. There were no false-positive results by either modality (specificity 100%). CONCLUSIONS: The detection of telomerase activity in biopsy specimens and p53 overexpression in combination with routine histologic examination may improve the diagnosis of biliary tract cancers. (Gastrointest Endosc 2000;52:380-6).

Aged↗

PubMed2000

Extracellular superoxide dismutase in tissues from obese (ob/ob) mice.

We have examined the protein content and gene expression of three superoxide dismutase (SOD) isoenzymes in eight tissues from obese ob/ob mice, particularly placing the focus on extracellular-SOD (EC-SOD) in the white adipose tissue (WAT). Obesity significantly increased EC-SOD level in liver, kidney, testis, gastrocnemius muscle, WAT, brown adipose tissue (BAT), and plasma, but significantly decreased the isoenzyme level in lung. Tumor necrosis factor-alpha and interleukin-1beta contents in WAT were significantly higher in obese mice than in lean control mice. Immunohistochemically, both WAT and BAT from obese mice could be stained deeply with anti-mouse EC-SOD antibody compared with those from lean mice. Each primary culture per se almost time-dependently enhanced EC-SOD production, and overtly expressed its mRNA. The loss of heparin-binding affinity of EC-SOD type C with high affinity for heparin occurred in kidney of obese mice. These results suggest that the physiological importance of this SOD isoenzyme in WAT may be a compensatory adaptation to oxidative stress.

Adipose Tissue↗

PubMed2000

Combination therapy for chronic Pseudomonas aeruginosa respiratory infection associated with biofilm formation.

There had been no reports of investigations into biofilms in chronic respiratory infection in vivo. Recently, we established a new murine model of chronic respiratory infection with Pseudomonas aeruginosa. In the present study, we examined the bacteriological effect of combined clarithromycin and levofloxacin against chronic respiratory infection with P. aeruginosa. Scanning electron micrograph of the surface of the catheter intubated in mouse bronchus for 7 days demonstrated in vivo formation of a biofilm containing blood cells, complex fibrous structures and bacteria. Treatment with either clarithromycin alone or levofloxacin alone had no statistical effect on the number of viable bacteria in lung. The combined use of both drugs resulted in a significant decrease in the number of viable bacteria. The present experiment demonstrates that the newly established murine model was useful to investigate the treatment of biofilm-associated chronic respiratory infection with P. aeruginosa, and combination therapy with clarithromycin and levofloxacin was effective in biofilm-associated chronic respiratory infection.

Animals↗

PubMed2000

Swimming training prevents generation of suppressor macrophages during acute cold stress.

PURPOSE: Acute cold stress induces suppressor macrophages expressing large numbers of receptors to Fc portion of immunoglobulin G (MAC-1+ Fc gammaRII/IIIbright cells), resulting in suppression of splenocyte mitogenesis. The generation of MAC-1+ Fc gammaRII/IIIbright cells is partly mediated by increased glucocorticoid levels during acute cold stress. The aim of the current study was to investigate the effect of swimming training on the generation of the MAC-1+ Fc gammaRII/IIIbright suppressor macrophages by acute cold stress. METHODS: The trained mice underwent a 6-wk endurance swimming training (5 times/wk) in water at 35-36 degrees C for 90 min. The swimming training significantly increased brown adipose tissue mass, suggesting improved cold tolerance. Actually, when the swimming-trained mice were exposed to 5 degrees C for 3 h (acute cold stress), the rectal temperature was not decreased. The proportion of MAC-1+ Fc gammaRII/IIIbright cells in peritoneal exudate cells from swimming-trained mice was significantly lower than that from control mice. In addition, the proportion of MAC-1+ Fc gammaRII/IIIbright cells in peritoneal exudate cell population from swimming-trained mice was unaffected by the acute cold stress. The swimming training significantly attenuated the increases in serum corticosterone levels in response to acute cold stress. These results suggested that swimming training not only improves cold tolerance but also inhibits the generation of suppressor macrophages under acute cold stress as well as under normal conditions.

Acclimatization↗

PubMed2000

Effects of swimming training on three superoxide dismutase isoenzymes in mouse tissues.

The purpose of the present study was to investigate the effects of swimming training on the changes in three superoxide dismutase (SOD) isoenzymes in mice. The trained mice underwent a 6-wk swimming program (1 h/day, 5 days/wk) in water at 35-36 degrees C. Immunoreactive extracellular SOD (EC-SOD), copper- and zinc-containing SOD (CuZn-SOD), and manganese-containing SOD (Mn-SOD) contents and their mRNA abundance were determined in serum, heart, lung, liver, kidney, and gastrocnemius muscle. EC-SOD content in liver and kidney was significantly increased with training. After training, CuZn-SOD content rose significantly only in kidney but decreased significantly in heart, lung, and liver. Mn-SOD content showed a significant increase in lung, kidney, and skeletal muscle but a significant decrease in liver. In most tissues, however, the changes in SOD isoenzyme contents were not concomitant with those in their mRNA levels. The results obtained thus suggest that, except for kidney, the responses in mouse tissues of three SOD isoenzymes (protein levels and mRNA abundance) to swimming training are different and that kidney may be one of the most sensitive organs to adapt to oxidative stress during physical training, although the mechanism remains vague.

Animals↗

PubMed2000

Malignant neurofibroma of the urinary bladder.

Malignant neurofibroma of the urinary bladder is a very rare entity and usually associated with von Recklinghausen's disease. We present the first case of sporadic malignant neurofibroma of the urinary bladder and a review of the literature.

Aged↗

PubMed2000

Delayed neutrophil elastase inhibition prevents subsequent progression of acute lung injury induced by endotoxin inhalation in hamsters.

To define the role of neutrophil elastase (NE) in the progression of acute lung injury (ALI), we examined the effects of post-treatment with a specific NE inhibitor, sivelestat sodium hydrate (sivelestat), on ALI induced by endotoxin (ET) inhalation in hamsters. Inhalation of ET (300 microg/ml, 30 min) in conscious hamsters increased inflammatory cell count, protein concentration, and hemorrhage in bronchoalveolar lavage fluid (BALF) that peaked 24 h after ET inhalation. These changes were significant 2 h after ET inhalation and paralleled the increase in NE activity in BALF. When intravenously infused from 2 to 24 h post-ET inhalation, sivelestat (0.03 to 3 mg/kg/h) dose-dependently attenuated changes in these BALF parameters at 24 h post-ET inhalation in a manner dependent on the inhibition of NE activity in BALF. Histopathological analysis also indicated that sivelestat prevented the progression of lung inflammation such as alveolar neutrophil infiltration and hemorrhage. In contrast, dexamethasone (3 mg/kg, intravenously) was not effective in this model when administered 2 h after ET inhalation, although it was highly effective when applied before ET. We conclude that delayed inhibition of NE activity with sivelestat prevents subsequent progression of ALI in hamsters after ET inhalation. Thus NE may play an important role in the progression of ALI.

Animals↗

PubMed2000

In vivo degradation of resin-dentin bonds in humans over 1 to 3 years.

The longevity of resin restorations is currently an area of great interest in adhesive dentistry. However, no work has been conducted to investigate the durability of resin-dentin bond structures using human substrate in vivo. The purpose of this study was to investigate the degradation of the resin-dentin bond structures aged in an oral environment for 1, 2, or 3 years. Cavities were prepared in primary molars, and an adhesive resin system (Scotchbond Multi-Purpose) was applied to the cavity. After 1 to 3 years, following the eruption of the succedaneous permanent teeth, the resin-restored teeth were extracted. Immediately after extraction, those teeth were sectioned perpendicular to the adhesive interface and trimmed to produce an hourglass-shaped specimen. Then, a micro-tensile test was performed at a crosshead speed of 1.0 mm/min. The mean bond strengths were statistically compared with one-way ANOVA and Fisher's PLSD test (p < 0.05). Further, all fractured surfaces were observed by SEM, and the area fraction of failure mode was calculated by means of a digital analyzer on SEM photomicrographs. There were significant differences in tensile-bond strength among all 3 groups (p < 0.05), with mean values ranging from 28.3 +/- 11.3 MPa (control), to 15.2 +/- 4.4 MPa (1 to 2 years), to 9.1 +/- 5.1 MPa (2 to 3 years). Moreover, under fractographic analysis, the proportion of demineralized dentin at the fractured surface in specimens aged in an oral environment was greater than that in control specimens. Furthermore, degradation of resin composite and the depletion of collagen fibrils was observed among the specimens aged in an oral environment. Analysis of the results of this study indicated that the degradation of resin-dentin bond structures occurs after aging in the oral cavity.

Adhesives↗

PubMed2000

Molecular and clinical features of non-Burkitt's, diffuse large-cell lymphoma of B-cell type associated with the c-MYC/immunoglobulin heavy-chain fusion gene.

PURPOSE: t(8;14)(q24;q32) and/or c-MYC/immunoglobulin heavy-chain (IGH) fusion gene have been observed not only in Burkitt's lymphoma (BL) but also in a proportion of non-BL, diffuse large-cell lymphoma of B-cell type (DLCL). We explored molecular features of DLCL with c-MYC/IGH fusion and the impact of this genetic abnormality on clinical outcome of DLCL. PATIENTS AND METHODS: A total of 203 cases of non-BL DLCL were studied. Genomic DNA extracted from tumor tissues was subjected to long-distance polymerase chain reaction (LD-PCR) using oligonucleotide primers for exon 2 of c-MYC and for the four constant region genes of IGH. RESULTS: Twelve cases (5.9%) showed positive amplification; one had a c-MYC/Cmicro, nine had a c-MYC/Cgamma, and two had a c-MYC/Calpha fusion sequence. Restriction and sequence analysis of the LD-PCR products, ranging from 2.3 to 9.4 kb in size, showed that breakage in the 12 cases occurred within a 1.5-kb region that included exon 1 of c-MYC in combination with breakpoints at the switch regions of IGH (10 of 12). In 10 cases, Myc protein encoded by the fusion genes demonstrated mutations and/or deletions. Six cases had additional molecular lesions in BCL-2 or BCL-6 and/or p53 genes. The age range of the 12 patients was 44 to 86 years, with a median age of 65.5 years. Five patients had stage I/II disease, and seven had stage III/IV disease. Lactate dehydrogenase was elevated in nine of 11 subjects. Seven showed involvement of the gastrointestinal tract. All patients were treated by surgery and/or chemoradiotherapy; six died of the disease within 1 year, resulting in the poorest 1- and 2-year survival rates among DLCL subgroups. CONCLUSION: The c-MYC/IGH fusion gene of DLCL is identical to that of the sporadic type of BL (sBL). DLCL with c-MYC/IGH shares clinical features with sBL but is characterized further by an older age distribution.

Adult↗

PubMed2000

Thyroid hypertrophic effect of semotiadil fumarate, a new calcium antagonist, in rats.

We studied the effects of semotiadil fumarate (SF), a new calcium antagonist with a unique benzothiazine structure, on the thyroid gland and liver in rats and compared them with those of another calcium antagonist, nicardipine (NCD), a well-known thyroidal hypertrophic agent and microsomal enzyme inducer, phenobarbital (PB), and goitrogen propylthiouracil (PTU). In oral 2-week treatment, SF caused increases in hepatic microsomal protein levels, uridine diphosphate glucuronosyltransferase (UDPGT) activity and an increase in serum thyroid stimulating hormone (TSH) level together with decreases in serum thyroid hormone levels. These results suggest that SF accelerates peripheral disposition of thyroid hormones and subsequently stimulates secretion of TSH from the pituitary gland as a compensatory response. PB and NCD had similar effects on the thyroid gland and the liver. PTU showed obvious thyroid hyperplasia and an increase in relative liver weight. Drastic increase in TSH level was observed in the PTU-treated group together with significant decreases in serum thyroid hormone levels and an increase in hepatic UDPGT activity. Histopathologically, PTU depleted the colloids in follicles, suggesting the inhibition of thyroid hormone synthesis. SF, PB and NCD showed thyroidal hyperplasia, but the extent of the change was far more moderate than that induced by PTU. These results indicate that the effect of SF is similar to those of PB and thyroid hypertrophy seen in the oral 2-week treatment with SF, and may be caused by indirectly elevated TSH levels which resulted from the induction of hepatic UDPGT activity.

Animals↗

PubMed2000

The t(9;14)(p13;q32) translocation in B-cell non-Hodgkin's lymphoma.

t(9;14)(p13;q32) is a rare but recurring translocation found in a subset of B-cell non-Hodgkin's lymphoma (B-NHL). These lymphomas share clinical features with chronic lymphocytic leukemia and are further characterized by plasmacytoid differentiation of lymphoma cells. Molecular cloning of t(9;14)(p13;q32) revealed juxtaposition of the PAX5 to the immunoglobulin heavy chain gene (IGH), although breakpoints on both genes were variable. The PAX5 gene encodes the BSAP (B-cell-specific activator protein) transcription factor, which is expressed throughout the process of B-cell development except in terminally differentiated plasma cells. t(9;14)(p13;q32) consistently leaves the PAX5 coding region intact, most likely resulting in deregulated expression of the gene product due to the proximity of IGH. The majority cases of B-cell tumors expressed considerable levels of PAX5/BSAP irrespective of whether they exhibited t(9;14)(p13;q32), suggesting that quantitative differences in expression level alone may not account for the development of this particular subtype of B-NHL.

Amino Acid Sequence↗

PubMed2000

Corrosion characteristics of ferric and austenitic stainless steels for dental magnetic attachment.

The corrosion behaviors of four ferric stainless steels and two austenitic stainless steels were examined in a simulated physiological environment (0.9% NaCl solution) to obtain basic data for evaluating the appropriate composition of stainless steels for dental magnetic attachments. The corrosion resistance was evaluated by electrochemical techniques and the analysis of released metal ions by atomic absorption spectrophotometry. The surface of the stainless steels was analyzed by X-ray photoelectron spectroscopy (XPS). The breakdown potential of ferric stainless steels increased and the total amount of released metal ions decreased linearly with increases in the sum of the Cr and Mo contents. The corrosion rate of the ferric stainless steels increased 2 to 6 times when they were galvanically coupled with noble metal alloys but decreased when coupled with commercially pure Ti. For austenitic stainless steels, the breakdown potential of high N-bearing stainless steel was approximately 500 mV higher than that of SUS316L, which is currently used as a component in dental magnetic attachments. The enriched nitrogen at the alloy/passive film interface may be effective in improving the localized corrosion resistance.

Carbon↗