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Biomedical subjects

H Kato

Publications and source records attributed to H Kato.

At least 181 records · Page 10Linked to original sources
PubMed2001

Effect of thermal treatment on apatite-forming ability of NaOH-treated tantalum metal.

The prerequisite for an artificial material to bond to living bone is the formation of bonelike apatite on its surface in the body. This apatite can be reproduced on its surface even in an acellular simulated body fluid with ion concentrations nearly equal to those of the human blood plasma. The present authors previously showed that the tantalum metal subjected to a NaOH treatment to form a sodium tantalate hydrogel layer on its surface forms the bonelike apatite on its surface in SBF in a short period. The gel layer as-formed on the metal is, however, not resistant against abrasion, and hence thus-treated metal is not useful for clinical applications. In the present study, effects of thermal treatment on the mechanical properties and apatite-forming ability of the NaOH-treated tantalum metal were investigated. The sodium tantalate gel on the NaOH-treated tantalum was dehydrated to convert into amorphous sodium tantalate by a thermal treatment at 300 degrees C in air environment and into crystalline sodium tantalates by the thermal treatment at 500 degrees C. Resistivity of the gel layer against both peeling-off and scratching was significantly improved by the thermal treatment at 300 degrees C. The high apatite-forming ability of the sodium tantalate hydrogel was a little decreased by the thermal treatment at 300 degrees C, but appreciably decreased by the thermal treatment at 500 degrees C. It is believed that the tantalum metal subjected to the 0.5 M-NaOH treatment and the subsequent thermal treatment at 300 degrees C is useful as implants in dental and orthopaedic fields, since it shows high bioactivity as well as high fracture toughness.

Journal Article↗
PubMed2001

The effect of amino acid spacers on the antigenicity of dimeric peptide--inducing cross-reacting antibodies to a cell surface protein antigen of Streptococcus mutans.

In the course of developing a synthetic peptide vaccine for dental caries, we identified a unique 13-mer peptide named PAc(365-377), TYEAALKQYEADL, as a minimum peptide inducing cross-inhibiting antibodies to a cell surface protein antigen (PAc) of Streptococcus mutans. However, the peptide could hardly induce the production of antibody in the absence of adjuvant. Thus using this peptide as a unit peptide, tandem constructs of dimeric unit peptide with or without spacer amino acid residues were synthesized, and their antigenicities were examined in B10.D2 mice. Significant augmentation of antigenicity was obtained in all of the dimeric unit peptides with spacers, especially for lysine spacers. In addition, analysis for cross-reactivity of anti-construct antibodies against a set of double valine-substituted analogues of the unit peptide revealed that the di-lysine spacer might be more effective in inducing the cross-reacting antibodies to rPAc.

Adjuvants, Immunologic↗
PubMed2001

Effect of aging on bone formation induced by recombinant human bone morphogenetic protein-2 combined with fibrous collagen membranes at subperiosteal sites.

This study was designed to examine the effect of aging on bone formation induced by recombinant human bone morphogenetic protein-2 (rhBMP-2) combined with a fibrous collagen membrane (FCM). Implantation was done subperiosteally in bilateral palatal grooves in 34 male Wistar rats divided into three age groups: a 10-week-old group (10w group), a 30-week-old group (30w group) and a 70-week-old group (70w group). RhBMP-2-combined FCMs were implanted on the left palatal grooves as BMP-implanted sites (BMP site), while rhBMP-2 was not implanted on the right palatal grooves as control sites. The rats were sacrificed 6 weeks after implantation, and histometric evaluations were performed. New bone formation was observed in every site of each age group and the new bone was almost completely continuous with the original bone. The new bone volume (NBV) of the BMP site was significantly higher than that of the control site in each age group. The NBV of both the control and BMP sites were highest in the 10w group and lowest in the 70w group. The disparity of NBV between the control and BMP sites, which indicated the response to implanted BMP excluding the effect of skeletal growth and surgical stimulation, did not significantly differ among the age groups. These results indicate that rhBMP-2-combined FCM has the ability to induce new bone formation continuous with original bone even in senescent rats. Furthermore, it appeared that, in the case of palatal subperiosteal implantation, the responsiveness to implanted BMP was independent of age, although the total volume of newly formed bone declined with aging.

Aging↗
PubMed2001

Changes of serum melatonin level and its relationship to feto-placental unit during pregnancy.

Serum melatonin concentrations were studied in normal pregnant women and in women with several types of pathologic pregnancies, e.g., twins, preeclampsia or intrauterine growth retardation (IUGR). Blood samples were collected from the maternal antecubital vein at 14:00 hr (daytime) and 02:00 hr (nighttime) during pregnancy, and also from the umbilical vein and artery immediately after delivery. Serum melatonin concentrations were measured by radioimmunoassay. Daytime serum melatonin levels in normal (single fetus; singleton) pregnancies were low. While the levels showed an increasing tendency toward the end of pregnancy, no statistically significant changes occurred. On the other hand, the nighttime serum melatonin levels increased after 24 weeks of gestation, with significantly (P < 0.01) high levels after 32 weeks; these values decreased to non-pregnant levels on the 2nd day of puerperium. Nighttime serum melatonin levels were significantly (P < 0.05) higher in twin pregnancies after 28 weeks of gestation than in singleton pregnancies, whereas the patients with severe preeclampsia showed significantly (P < 0.05) lower serum melatonin levels than the mild preeclampsia or the normal pregnant women after 32 weeks of gestation. Melatonin concentrations in umbilical vessels showed a higher tendency in neonates who were born during at night compared with the other neonates; moreover, those in the umbilical artery were generally higher than those in the umbilical vein. The present results indicate that in humans, the maternal serum melatonin levels show a diurnal rhythm, which increases until the end of pregnancy, reflecting some pathologic states of the feto-placental unit. Fetuses may produce melatonin with a circadian rhythm.

Adult↗
PubMed2001

Periodontal healing after replantation of intentionally rotated teeth with healthy and denuded root surfaces.

The purpose of the study was to evaluate periodontal healing after replantation of intentionally rotated teeth with healthy and denuded root surfaces. Ten teeth with hopeless prognoses because of extensive alveolar bone loss and deep pockets extending to the apexes only on one or two surfaces, but with a healthy periodontal apparatus on the other surfaces, were selected. A mucogingival flap was elevated and the teeth were extracted carefully so as not to damage the healthy remnant of the periodontal membrane remaining on the root surfaces. Thorough extra-oral debridement was performed on the contaminated root surface and the remnant was carefully conserved. Retrofilling was also done to eliminate an endodontic cause of attachment loss. The teeth were horizontally rotated and then replanted so that the healthy root would face the connective tissue at the initially periodontally involved sites, and the root planed surfaces, which had been periodontally involved, would face the surfaces of the alveolar sockets at initially healthy sites. The teeth were splinted with adjacent teeth. Clinical parameters and radiographic examination were performed pre-operatively, and at 3 or 6 months, 1, 2, and 3 years postoperatively. One tooth was extracted 1.5 years postoperatively due to reduced support and the treatment strategy of the patient. The other nine teeth were well maintained without any discomfort for the whole maintenance period of 3 years. In all teeth, areas that previously had no pocketing but were now against denuded root surfaces maintained the previous pocket depth readings. In areas where a deep pocket was present but now had a root surface with healthy periodontium, a distinct decrease of mean pocket depth was observed at the first reexamination 3 months postoperatively. The mean radiographic alveolar bone level increased from 0.3% to 45.3% in 2 years and was thereafter maintained for the entire observation period. Loss of periodontal space and possible root resorption were observed in only one case without other ankylotic symptoms. These results suggest that the healing without ankylosis of an extensive denuded root surface may occur by mechanisms other than the maintenance of a viable periodontal ligament on the root surface.

Adult↗
PubMed2001

Periodontal healing after bonding treatment of vertical root fracture.

Vertical root fractures lead to advanced periodontal breakdown with deep periodontal pockets and vertical bone defects. The purpose of this study is to evaluate clinically the periodontal healing of root fracture treatment using adhesive resin cement. In 22 patients, 23 teeth with vertical root fractures were treated with 4-META/MMA-TBB resin cement. Eleven fractured roots were bonded through the root canal (group A) and 12 fractured roots were bonded extra-orally and replanted (group B). All teeth were then restored with full cast crowns (n=20) or coping (n=3). Mean probing depth was 6.6 mm at pre-treatment and 4.4 mm 6 months after the treatment in group A, and 7.4 mm and 4.6 mm, respectively, in group B. Bleeding scores were 100% at pre-treatment and 36.4% after 6 months in group A and 91.7% and 8.3%, respectively in group B. Radiographic bone level was 56.8% at pretreatment and 59.1% after 6 months in group A, and 18.8% and 29.2%, respectively, in group B. Two roots of group A and three roots of group B were extracted due to refracture, deterioration of periodontal inflammation, mobility, and luxation. The remaining roots (n=18) presented no discomfort to the patients and there was no deterioration of periodontal conditions over a mean period of 33 months (range 14-74 months) in group A and over a mean period of 22 months (range 6-48 months) in group B. There was no ankylosed teeth nor was any root resorption detected. The results suggested that the treatment of vertical root fracture using 4-META/MMA-TBB resin has good prognostic possibilities.

Adult↗
PubMed2001

Contribution of Na+/Ca2+ exchanger to the regulation of myogenic tone in isolated rat small arteries.

The contribution of the Na+/Ca2+ exchanger to the myogenic vascular tone was examined in rat isolated skeletal muscle small arteries (ASK) with pronounced myogenic tone and mesenteric small arteries (AMS) with little myogenic tone. Myogenic tone was assessed by the vascular inner diameter at transmural pressures of 40 and 100 mmHg. To depress the Na+/Ca2+ exchanger, the extracellular Na+ concentration ([Na+]o) was lowered from 143 to 1.2 mM by substituting choline-Cl for NaCl. The ASK developed significant myogenic tone and constricted further in low [Na+]o. Nifedipine (1 microM) reduced both myogenic tone and low [Na+]o-induced contraction. Because the membrane potential of ASK was not changed by low [Na+]o (-35 +/- 2 mV at 143 mM [Na+]o, -37 +/- 3 mV at 1.2 mM [Na+]o), depolarization-induced Ca2+ influx was not a cause of the low [Na+]o-induced contraction. The AMS did not develop significant myogenic tone. Although low [Na+]o also constricted AMS, the magnitude of constriction was significantly weaker than that in ASK (17 +/- 4 vs. 47 +/- 6%, P < 0.01, at 58 mM Na+). With Bay K 8644, AMS developed myogenic tone, and low [Na+]o-induced constriction was significantly increased. In conclusion, Na+/Ca2+ exchanger may play an important role in regulating myogenic tone, likely via mediating Ca2+-extrusion.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed2001

Other primary cancers occurring after treatment of superficial oesophageal cancer.

BACKGROUND: Recent advances in endoscopic diagnosis and treatment have led to better prognosis for patients with superficial oesophageal cancer. The incidence of subsequent other primary cancer (SOPC) has become a new problem for patients who survive after treatment of superficial oesophageal cancer. METHODS: Between 1966 and 1998, 368 patients with superficial oesophageal cancer, histologically confirmed as squamous cell carcinoma after resection, were reviewed for the presence of SOPC. RESULTS: Among the 368 patients, 43 developed SOPC. The most frequent sites of SOPC were the stomach (11 patients) and hypopharynx (11). Subsequent cancers of the stomach and hypopharynx developed significantly more frequently in heavy smokers. The 5-year cumulative occurrence rate of subsequent cancers within the fields of endoscopy of the upper gastrointestinal tract (stomach, hypopharynx and residual oesophagus) was 15 per cent. CONCLUSION: Gastric and hypopharyngeal cancers were frequently found after resection of superficial oesophageal cancer. A history of heavy smoking at the time of initial resection may be a risk factor. To make an early diagnosis of subsequent cancers, follow-up observation by upper gastrointestinal endoscopy is important after treatment of oesophageal cancer.

Carcinoma, Squamous Cell↗
PubMed2001

Influenza virus RNA polymerase PA subunit is a novel serine protease with Ser624 at the active site.

BACKGROUND: Influenza virus RNA polymerase is a multifunctional enzyme that catalyses both transcription and replication of the RNA genome. The function of the influenza virus RNA polymerase PA subunit in viral replication is poorly understood, although the enzyme is known to be required for cRNA --> vRNA synthesis. The protease related activity of PA has been discussed ever since protease-inducing activity was demonstrated in transfection experiments. RESULTS: PA protein was highly purified from insect cells infected with the recombinant baculovirus carrying PA cDNA, and a novel chymotrypsin-type serine protease activity was identified with the synthetic peptide, Suc-LLVY-MCA, in the PA protein. [3H]DFP was crosslinked with PA and a mutational analysis revealed that serine624 was as an active site for the protease activity. CONCLUSIONS: These results constitute the demonstration of protease activity in PA subunit of the influenza virus RNA polymerase complexes.

Amino Acid Sequence↗
PubMed2001

Improved bonding of adhesive resin to sintered porcelain with the combination of acid etching and a two-liquid silane conditioner.

This study determined the bond strengths of adhesive resins joined to a feldspathic porcelain (VMK 68) for the purpose of developing the most durable surface preparation for the porcelain. Three porcelain surfaces-ground, air-abraded with alumina, and etched with hydrofluoric acid-were prepared. A two-liquid porcelain conditioner that contained both 4-methacryloyloxyethyl trimellitate anhydride (4-META) and a silane coupler (Porcelain Liner M) was used as the priming agent. Each of the two liquid components of the conditioner was also used individually in order to examine the effects of the respective chemical ingredients on adhesive bonding. Two methyl methacrylate (MMA)-based resins initiated with tri-n-butylborane (TBB) either with or without 4-META (MMA-TBB and 4-META/MMA-TBB resins) were used as the luting agents. Shear bond strengths were determined both before and after thermocycling. Shear testing results indicated that thermocycling was effective for disclosing poor bonding systems, and that both mechanical and chemical retention were indispensable for bonding the porcelain. Of the combinations assessed, etching with hydrofluoric acid followed by two-liquid priming with the Porcelain Liner M material generated the most durable bond strength (33.3 MPa) for the porcelain bonded with the 4-META/MMA-TBB resin (Super-Bond C&B).

Acid Etching, Dental↗
PubMed2001

3beta-hydroxy-delta5 -C27-steroid dehydrogenase deficiency: diagnosis and treatment.

The aim of this study was to evaluate the effects of bile acid treatment and to obtain further information about the pathway of bile acid biosynthesis in a patient with 3beta-hydroxy-delta5-C27-steroid dehydrogenase/isomerase (3beta-HSD) deficiency by gas chromatography-mass spectrometry. Results showed that at 2 months of age, 3beta-hydroxy-5-cholen-24-oic acid (3.0 micromol/mmol Cr, 7.9%) was detected in the urine in essentially the same relative amount as 3beta,7alpha-dihydroxy- and 3beta,7alpha,12alpha-trihydroxy-5-cholen-24-oic acids (3.7 micromol/mmol Cr, 9.8%) during ursodeoxycholic acid treatment combined with prednisolone. As a result, diagnosis was delayed until 18 months of age. One month later with substitution of chenodeoxycholic acid treatment, urinary 3beta,7alpha-dihydroxy- and 3beta,7alpha,12alpha-trihydroxy-5-cholen-24-oic acids decreased significantly, and subsequent improvement of liver dysfunction was accelerated. Chenodeoxycholic acid treatment is useful in 3beta-HSD deficiency. However, in the diagnosis of this disease in early life, it should be noted that the acidic pathway may be the major route for bile acid biosynthesis in the neonatal period. Diagnosis of 3beta-HSD deficiency may have been delayed by administration of ursodeoxycholic acid, resulting in prolonged diagnostic investigation in this child with cholestasis. Further, use of prednisolone may have been contraindicated.

3-Hydroxysteroid Dehydrogenases↗
PubMed2001

Epidemiology of Helicobacter pylori infection in children: a serologic study of the Kyushu region in Japan.

BACKGROUND: The prevalence of Helicobacter pylori infection in children varies as a function of socioeconomic development, with low rates in developed countries and high rates in developing countries. The prevalence of H. pylori infection in Japanese children is unknown. METHODS: The present study examined the effect of living conditions on the prevalence of H. pylori infection in children. We determined the prevalence of H. pylori infection in healthy children of the Kyushu region in Japan and compared it with the prevalence in institutionalized children with severe neurologic illness. Serum concentrations of anti-H. pylori IgG antibody were measured by an enzyme-linked immunosorbent assay in 336 healthy children and 56 patients with severe neurologic impairment. An antibody concentration > 50 units/mL was taken as evidence of infection. RESULTS: The prevalence of H. pylori seropositivity in healthy children increased with age (P < 0.0001) and was 29% in children 15-19 years of age. This value is slightly higher than prevalences reported in developed countries (5-15%), but is lower than in developing countries (30-60%). Seropositivity did not vary with respect to gender, water supply or location of housing. Helicobacter pylori seropositivity was more prevalent among institutionalized children aged 5-19 years than their healthy counterparts (P < 0.005). CONCLUSIONS: The intermediate prevalence of H. pylori seropositivity in healthy children between that measured in developed and developing countries is consistent with the socioeconomic 'westernization' of Japan.

Adolescent↗
PubMed2001

Re-treatment for immune globulin-resistant Kawasaki disease: a comparative study of additional immune globulin and steroid pulse therapy.

BACKGROUND: We compared the efficacy and safety of additional intravenous immune globulin (IVIG) therapy with steroid pulse therapy in patients with IVIG-resistant Kawasaki disease. METHODS: Two-hundred and sixty-two consecutive patients had been treated with a single dose of IVIG (2 g/kg) and aspirin (30 mg/kg per day). Thirty-five patients (13.4%) were not clinical responders to the initial IVIG treatment. They received an additional IVIG treatment (1 g/kg) within 48 h after the initial treatment. Seventeen patients (6.5%) did not respond to the additional IVIG treatment. We randomly divided these patients into two groups: group 1 consisted of eight patients who were treated with a single additional dose of IVIG (1 g/kg), while group 2 consisted of nine patients who were treated with steroid pulse therapy. RESULTS: The IVIG-resistant patients had a high incidence of coronary artery lesions (CAL; 48.6%). Five patients (62.5%) in group 1 had CAL, including two patients who each had a giant aneurysm and three patients who each had a small aneurysm. Seven patients (77.8%) in group 2 had CAL, including two patients who each had a giant aneurysm, two patients who each had a small coronary aneurysm and three patients who each showed transient dilatation during steroid pulse therapy. There was no significant difference in the incidence of CAL between the two groups. The duration of high fever in group 2 (1.4~0.7 days) was significantly shorter than in group 1 (4.8~3.4 days; P<0.05). The medical costs for the treatment of patients in group 2 (113, 012 yen +/- 22,084) were significantly lower than those for group 1 (144,194 yen +/- 12,914; P<0.05). CONCLUSIONS: Steroid pulse therapy may be useful in the treatment of patients with IVIG-resistant Kawasaki disease who experience prolonged fever. However, transient dilatation of the coronary artery is observed during steroid pulse therapy, so careful echocardiographic examination should be performed for those patients receiving steroid pulse therapy for the sake of early detection of coronary artery abnormalities.

Anti-Inflammatory Agents↗
PubMed2001

Catheter closure of moderate to large sized patent ductus arteriosus using the simultaneous double or triple coil technique.

BACKGROUND: Although the clinical experience with transcatheter closure of the patent ductus arteriosus using the coils has grown rapidly, one important complication of this procedure using the conventional Gianturco coil was the migration of coils into peripheral vessels. This is especially for patients with a relatively larger size ductus and the risk for such complications could be increased. In this situation, the detachable coil may have some technical benefits to perform coil occlusion and reduce the incidence of complications. METHODS: We describe the clinical efficacy of a simultaneous double or triple coil occlusion technique using the Cook detachable coil or bioptome delivered 0.052 inch Gianturco coil to close the ductus arteriosus. This was performed in patients whose ductus diameter was greater than 3.0 mm. RESULTS: From February 1995 to December 2000, 118 patients with patent ductus arteriosus were treated by coil occlusion using Cook detachable coils, of whom 58 patients whose minimum diameter of ductus > or = 3.0 mm were reviewed. All patients had successful placement of coils. According to the evaluation by color flow mapping, a trivial shunt was observed in 17 patients (29%) within 24 h after the procedure. In 11 out of 17 patients, a residual shunt was not detected 1 month after the procedure. At 6 months after the procedure, the residual shunt was detected only in three patients. CONCLUSIONS: Although this study did not calculate the statistical significance between detachable and non-detachable coils in term of occlusion rate, our institutional experience suggests that the simultaneous double or triple coil technique using the detachable or 0.052 inch Gianturco coils can reduce the prevalence of coil migration or complications.

Adolescent↗
PubMed2001

Guidelines for catheter intervention in coronary artery lesion in Kawasaki disease.

The Research Committee of Ministry of Health, Labour and Welfare 'Study of treatment and long-term management in Kawasaki disease' reported the guidelines for catheter intervention in coronary artery lesion in Kawasaki disease in this paper. The contents include: (i) background and natural history of coronary artery lesion in Kawasaki disease; (ii) indication of catheter intervention; (iii) types of procedure, and their indication and care; (iv) institute and backup system; (v) the management after procedure, evaluation and follow up; and (vi) prospects, especially in relation to bypass surgery.

Angioplasty, Balloon, Coronary↗
PubMed2001

Prostatic adenocarcinoma with marked neuroendocrine differentiation.

A case is presented of prostatic cancer with marked neuroendocrine differentiation. Double-labeled immunohistochemical staining was performed with prostate-specific antigen and Chromogranin A. Both antibodies were localized to some of the cancer cells with Paneth cell-like features. Furthermore, most of the cancer cells were positively stained with luminal cell marker CAM 5.2, suggesting that neuroendocrine cells originated from the prostatic luminal cells.

Adenocarcinoma↗
PubMed2001

The serous-lined tunnel principle for urinary reconstruction: a more rational method.

OBJECTIVE: To examine the feasibility of using the serous-lined-tunnel principle for orthotopic neobladder, continent cutaneous diversion and ureteric replacement by an intestinal segment. Patients and methods We created: (i) an orthotopic ileal neobladder using the serous-lined technique for antirefluxing ureteric implantation in 16 patients; (ii) a continent ileal pouch, adopting the principle for continent-valve construction and for ureteric implantation, in 10 patients (another patient with a failed continent valve underwent revision using an adaptation of this principle; and (iii) by applying the same principle an ileal ureter with a proximal antirefluxing mechanism was constructed in two patients (with lower ureteric cancer), and total replacement of the ureter by a tubular segment of the colon in association with a continent transverse colon pouch in one irradiated patient. RESULTS: In all, 52 ureters implanted into ileal neobladders or continent pouches functioned well, with neither obstruction nor reflux; 11 continent valves functioned well with no incontinence. Two patients with ileal ureters showed no ileo-ureteric reflux and had less hydronephrosis than before surgery. The tubularized ureter provided a unidirectional flow into the pouch. Conclusion Ureteric reimplantation and continent valve formation achieved by adopting the serous-lined tunnel principle provided satisfactory results. The versatility of the principle is apparent in the present experience and the creative application of the serous-lined tunnel principle should be possible in urinary reconstruction.

Adolescent↗