Biomedical subjects

H Sonoda

Publications and source records attributed to H Sonoda.

At least 19 recordsLinked to original sources

PubMed2004

An in vitro investigation of microtensile bond strengths of two dentine adhesives to caries-affected dentine.

OBJECTIVES: To compare the micro-tensile bond strengths of two different adhesive systems (ABF (Clearfil Protect Bond), Kuraray Medical Inc., Tokyo, Japan) and Prime & Bond NT (PBNT, Dentsply, Konstanz, Germany) bonded to caries-affected dentine retained after chemo-mechanical caries removal using Carisolv gel, with that retained after excavation using conventional hand instrumentation. METHOD: Twenty, adult, human extracted carious teeth were used in this split tooth study with bur-cut cavities in sound dentine acting as controls. After clinical caries excavation, the occlusal cavities in each experimental group were restored with either bonding system plus composite. Matchstick-shaped samples through the bond interfaces were sectioned and microtensile bond strengths recorded. Scanning electron microscopy (SEM) was used to ascertain the mode of failure at the restoration-dentine interface. RESULTS: Statistical analysis of the bond strength data showed that for the ABF group, there was no difference in bond strengths between the controls and Carisolv group but these values were significantly higher than those for the hand-excavated samples. PBNT samples showed no significant differences in any of the three test groups, with wider ranging data sets. SEM analysis indicated a variety of failures at the interface including cohesive failures within the caries-affected dentine itself. CONCLUSIONS: From the data generated by this study it could be concluded that microtensile bond strengths of PBNT/composite restorations to caries-affected dentine in clinical cavities were statistically comparable to those to sound dentine. In the ABF/composite restored group (self-etched), the use of conventional hand excavation appeared to weaken the bond strength to the remaining caries-affected dentine. However, the use of Carisolv gel excavation did not compromise bond strengths to caries-affected dentine in either group tested.

Adhesiveness↗

PubMed2002

The effects of tibial component inclination on bone stress after unicompartmental knee arthroplasty.

Unlike the case with total knee arthroplasty, the femorotibial angle (FTA) after unicompartmental knee arthroplasty (UKA) does not directly depend on the inclination of the tibial component when the height of the joint line is maintained. This study analyzed the effects of the inclination of the tibial component in the coronal plane on the contact pressure of the implant-bone surface and the stresses on the proximal tibia. A two-dimensional, coronal plane model of the proximal tibia was subjected to finite-element analysis. Sixteen patterns of finite-element models of equal FTA were developed in which the inclination of tibial components ranged from 5 degrees valgus to 10 degrees varus in increments of 1 degrees. Stress concentration at the proximal medial diaphyseal cortex gradually increased as the inclination changed from valgus to varus. Maximum contact pressure on the metal-bone interface similarly changed and shifted from the lateral edge to the medial edge of the implant as the inclination changed to varus. It was found that even without changing FTA, the inclination of the tibial component might affect stress concentration and contact pressure in the proximal tibia after UKA. The results suggested that slight valgus inclination of the tibial component might be preferable to varus and even to 0 degrees (square) inclination so far as the stress distribution is concerned.

Arthroplasty, Replacement, Knee↗

PubMed2001

Small-diameter compliant arterial graft prosthesis: Design concept of coaxial double tubular graft and its fabrication.

To minimize compliance mismatch between native artery and arterial graft prosthesis over the entire pressure regions, we proposed a coaxial double tubular artificial graft which consists of an enhanced compliant inner tube and a less compliant outer tube, both of which were fabricated using well-controlled multiply micropored segmented polyurethane (SPU) films. Double tubular grafts were coaxially assembled by inserting the inner tube into the outer tube. First, the pressure-diameter (P-D) relationship of canine common carotid arteries, which exhibited a "J" curve, was determined as a targeted artery. Two determinant variables, the pressure-induced distensibility of each tube and the intertubular space distance, were defined and formulated in several models of coaxial double tubular SPU grafts, which had various intertubular space distances, micropore densities, and wall thicknesses. The distensibility of the inner tube determined the distensibility in the low-pressure regions, which was adjusted using wall thickness and microporosity. Thinner films with higher porosities resulted in a high pressure-induced distensibility. On the other hand, a low pressure-induced distensibility in the high-pressure regions was realized using an outer tube with a thicker wall and lower microporosity. The transition point from low- to high-pressure regions was determined by the intertubular distance using the theoretical values. On the basis of these results, we presented a prototype model of a coaxial double tubular graft that exhibited well-matched compliance with canine carotid artery.

Animals↗

PubMed2001

[Dental treatment in the north area of Ishigaki Island in Okinawa].

Dental treatment and oral health care were performed on inhabitants in the north area of Ishigaki Island in Okinawa. There are no dentists in the area at present. One hundred sixty-six patients received treatment taking 528 man-days, during the period from November 9 to December 8, 2000. The area has 2 primary schools and 1 junior high school. The average DMFT of the children in the primary schools was 1.31, and in the junior high school it was 4.98. Compared with Japanese national survey data, the children in the area had a higher DMFT. Among the treatment procedures, the rate of conservative treatment was 62%, most of which was composite resin filling. Preventive measures for dental disease were offered to the inhabitants by means of topical fluoride application or oral health education. The period of this promotion was too short to perform complete dental treatment and to prevent caries and periodontal disease. It seems that primary prevention and higher dental hygiene education are needed for inhabitants in no-dentist areas, because the inhabitants do not have access to dental service easily.

Community Dentistry↗

PubMed2000

Monkey pulpal response and microtensile bond strength beneath a one-application resin bonding system in vivo.

OBJECTIVES: The aim of this in vivo study was to investigate the biocompatibility and microtensile bond strength of a one-application resin bonding system. METHODS: Class V cavities were prepared on the facial surfaces of 36 intact monkey teeth, and the cavities were restored with an experimental one-application resin bonding system (TOF-1; Tokuyama Corp., Tokuyama, Japan) and a hybrid resin composite (PALFIQUE ESTELITE; Tokuyama Corp., Tokuyama, Japan). Histopathological changes of the restored teeth were evaluated at 3, 30 and 90 days after operation (N = 10). Microtensile bond tests were performed at 3 and 90 days after operation (N = 10). RESULTS: Only two of 30 pulps showed a slight inflammatory cell infiltration. There were no statistically significant differences in the incidence of slight inflammatory cell infiltration among time periods. Bacterial penetration along the cavity walls could not be detected in any specimen. The mean microtensile bond strength at 3 days after operation was 20.6 MPa, and that at 90 days was 14.9 MPa. Differences in bond strengths between the 3 day specimen and the 90 day specimen were statistically significant (p < 0.05). CONCLUSIONS: The one-application resin bonding system exhibited acceptable biologic compatibility to the monkey pulp. Although there were statistically significant differences in bond strengths between the 3 day specimen and the 90 day specimen, this material provided a hermetic seal, eliminating bacterial microleakage.

Acid Etching, Dental↗

PubMed2000

Analgesic mechanisms of ketamine in the presence and absence of peripheral inflammation.

BACKGROUND: The studies on the mechanisms of ketamine antinociception have led to conflicting results. In this study, the authors investigated the contribution of supraspinal monoaminergic descending inhibitory system to ketamine analgesia for acute nociception and inflammation-induced hyperalgesia. METHODS: Male Sprague-Dawley rats were used. The paw withdrawal latencies to radiant heat stimuli were measured to assess the thermal nociceptive threshold. The analgesic effects of intrathecal or intraperitoneal ketamine were examined in the rats that received unilateral intraplantar carrageenan and in those that were untreated. In addition, it was examined whether pretreatment with intrathecal yohimbine or methysergide inhibited the analgesic effects of ketamine. Using an intrathecal microdialysis method, noradrenaline and 5-hydroxytryptamine concentrations in lumbar cerebrospinal fluid were measured after intraperitoneal ketamine in both saline- and carrageenan-treated rats. RESULTS: In the untreated rats, intraperitoneal but not intrathecal ketamine produced antinociceptive effects in a dose-dependent manner. Pretreatment with intrathecal yohimbine or methysergide inhibited these antinociceptive effects. Intraplantar carrageenan significantly reduced paw withdrawal latencies on the injected paw but not on the contralateral paw. Both intraperitoneal and intrathecal ketamine reversed the shortened paw withdrawal latencies on the injected side in a dose-dependent manner without any effects on the contralateral side. Neither yohimbine nor methysergide inhibited these antihyperalgesic effects. In analyses of monoamines, the magnitude of increase in monoamines after intraperitoneal ketamine was significantly smaller in the carrageenan-treated rats than in the saline-treated rats. CONCLUSION: These results demonstrated that ketamine produced antinociceptive effects through an activation of the monoaminergic descending inhibitory system, whereas, in a unilateral peripheral inflammation-induced hyperalgesic state, the monoaminergic system did not contribute to the antihyperalgesic effects of ketamine. The mechanisms of the antinociceptive and antihyperalgesic properties of ketamine are different.

Adrenergic alpha-Antagonists↗

PubMed1999

HRad17 colocalizes with NHP2L1 in the nucleolus and redistributes after UV irradiation.

The rad17 gene of Schizosaccharomyces pombe plays an important role as a checkpoint protein following DNA damage and during DNA replication. The human homologue of S. pombe rad17, Hrad17, was recently identified, but its function has not yet been established. Using the yeast two-hybrid system, we determined that HRad17 can interact with a nucleolar protein, NHP2L1. This interaction was also demonstrated biochemically, in human cells. Immunofluorescence studies revealed that HRad17 and NHP2L1 colocalize to the nucleolus, and immunogold labeling further resolved the location of NHP2L1 to the dense fibrillar component of the nucleolus. Interestingly, the localization of HRad17 in the nucleolus was altered in response to UV irradiation. These results provide some insight into the DNA damage and replication checkpoint mechanisms of HRad17.

Amino Acid Sequence↗

PubMed1999

Cloning and characterization of psu1(+), a new essential fission yeast gene involved in cell wall synthesis.

We have isolated a new gene, psu1(+), from the fission yeast Schizosaccharomyces pombe. The predicted amino acid sequences shows that this protein has striking homology to the SUN family of the budding yeast, hence designated Psu1 (S. pombe homologue of the SUN family). Disruption of the psu1(+) gene revealed that it is essential for growth, and the null phenotype showed the swelling of cells followed by eventual lysis. We introduced psu1(+) gene in the disruptant strain and repressed it giving resistance to 1, 3-beta-glucanase digestion. Our results suggest that Psu1 plays an essential role in cell wall synthesis in S. pombe.

Amino Acid Sequence↗

PubMed1999

Suppression of oncogenic transformation by hypothemycin associated with accelerated cyclin D1 degradation through ubiquitin-proteasome pathway.

Hypothemycin was originally isolated as an antifungal metabolite of Hypomyces trichothecoides. Here we report that treatment on v-K-ras-transformed NIH3T3 cells (DT cells) with hypothemycin caused drastic decrease in amount of cyclin D1 protein with concomitant prolongation of G1 phase in their cell cycle. Analysis using hypothemycin-resistant mutant of Schizosaccharomyces pombe (S. pombe) was carried out to show that S. pombe rhp6+ (homologue of Saccharomyces cerevisiae RAD6) and mammalian ubiquitin-conjugating enzyme 2 (ubc2) are the targets of hypothemycin or its downstream molecules in ubiquitin-conjugation process. Furthermore, in the presence of lactacystin, a specific inhibitor for proteasome, hypothemycin greatly enhanced the accumulation of multi-ubiquitinated form of cyclin D1 in DT cells. Therefore, it is indicated that hypothemycin facilitates ubiquitinating process of cyclin D1. In terms of malignant phenotype, hypothemycin inhibited anchorage-independent growth and reverted the morphology of DT cells. On the contrary, their morphology still remained transformed in the additional presence of lactacystin. Our results suggest that cyclin D1 is a key molecule working downstream in ras-signaling and that the transformation can be inhibited by the compound which can activate ubiquitin-proteasome pathway including degradation of cyclin D1.

3T3 Cells↗

PubMed1999

[Descending aorta perfusion through median sternotomy in primary repair of aortic interruption complex].

Circulatory arrest is frequently used in aortic arch reconstruction in pediatric cardiac surgery. However, risks of postoperative acute renal failure and neurological deficit can not be ignored. We performed primary repair of aortic interruption in one-month old girl. After commencing extracorporeal circulation with bicaval venous cannulae and with arterial cannulae into the pulmonary trunk and the innominate artery, the descending aorta was cannulated just superior to the diaphragm. The cannula in the pulmonary trunk was then removed. Arch reconstruction and closure of the ventricular septal defect were performed with continuous perfusion to the brain and the lower body. The extracorporeal circulation time and the aortic cross-clamp time were 117 min and 21 min, respectively. Postoperative renal function was excellent, and there was no finding of neurological deficit. Cannulation of the descending aorta is a simple and useful technique with safety, in arch reconstruction in infants.

Aorta, Thoracic↗

PubMed1999

Light and scanning electron microscopy of the inner surfaces of resins used in direct pulp capping.

PURPOSE: To investigate with the scanning electron microscopy (SEM) the inner surface of the resin restorative used as a direct pulp capping. MATERIALS AND METHODS: Class V cavities were prepared on the facial surfaces of 90 intact monkey teeth, and the pulps were intentionally exposed with a carbide bur through the cavity floor. Each exposed pulp was capped with one of three commercially available adhesive resin systems (BondWell LC, GC; Imperva Bond, Shofu; Clearfil Liner Bond II, Kuraray). The cavities were restored with an adhesive resin and a hybrid resin-based composite. Histopathological changes of the mechanically exposed pulp were evaluated at 3, 30 and 60 days postoperatively. The interface between the resin and pulp tissues on the inner surface of the resin restorative was observed by SEM. RESULTS: Bacterial penetration along the cavity walls and pulp tissue could not be detected in any specimen. Slight inflammatory cell infiltration was the main initial reaction, while dentin bridge formation was the major long-term reaction in all groups. The resin surface adjacent to the etched cavity floor contained numerous resin tags corresponding to the dentin tubules. Remnants of pulpo-dentin complex, such as fragments of blood clots, pulpal cell, and dentin were also seen scattered along the inner resin surface.

Animals↗

PubMed1998

Use of bronchopulmonary lavage for eliminating inhaled fume particles from a patient with arc welder's lung.

A 42-year-old man, who had worked as a welder for 20 years, was admitted to our hospital complaining of a dry cough. A chest radiograph showed diffuse small nodular shadows and chest computed tomography revealed small patchy opacities. A transbronchial lung biopsy specimen showed welding fume particles mainly located in alveolar space with mild fibrosis of alveolar septa. In order to prevent further fibrosis, bronchopulmonary lavage (BPL) was performed to eliminate the fume particles. The amount of iron particles derived from the total lavage fluid was 911.7 mg.

Adult↗

PubMed1998

[Suppressive effects of ketamine on neuropathic pain].

We previously reported that ketamine analgesia in acute pain was produced by the activation of the monoaminergic descending inhibitory system. Recent studies have confirmed that the NMDA receptor antagonists attenuate the hyperalgesia in neuropathic pain. In this study, we investigated the suppressive effects of a clinically available NMDA antagonist, ketamine, and the mechanisms of its effects on neuropathic pain in rats with peripheral mononeuropathy. A unilateral chronic constriction injury (CCI) model was introduced by loose ligation of the sciatic nerve of the rats. The CCI rats showed hyperalgesia to thermal and mechanical pressure stimuli on the injured side of their hind paws. Intraperitoneal (IP) ketamine (25 or 50 mg.kg-1) and intrathecal (IT) ketamine (25-500 micrograms) reversed, dose-dependently, both thermal and mechanical hyperalgesia. Pretreatment with IT yohimbine (alpha-2 adrenergic antagonist) or IT methysergide (serotonergic antagonist) did not show the suppressive effects of IP ketamine (50 mg.kg-1) on hyperalgesia. Concentrations of norepinephrine (NE) and serotonin (5HT) in the spinal dorsal horn were measured using high performance liquid chromatography. The CCI rats showed increased NE and 5HT concentrations on both ligated and unligated sides of spinal dorsal horn, compared with shamoperated rats. IP ketamine (50 mg.kg-1) in the CCI rats did not boost the spinal NE or 5HT levels. These results indicate that the anti-hyperalgesic effect of ketamine is derived from a direct action on the spinal cord, but not from the activation of monoaminergic descending inhibitory systems.

Acute Disease↗

PubMed1998

[Positive end-expiratory pressure facilitates washout of nitrous oxide in patients with obstructive pulmonary disease].

This study was designed to investigate the relationship between nitrous oxide elimination and each value of pulmonary function tests: percent vital capacity, air way resistance and percent of forced expiratory pressure (FEV1.0%) in patients undergoing general anesthesia. Furthermore, the effect of positive end-expiratory pressure (PEEP) on nitrous oxide elimination was studied. Thirty nine patients, anesthetized by oxygen, nitrous oxide and sevoflurane, were allocated randomly to one of two groups; one, with PEEP 10 cmH2O during nitrous oxide elimination and the other, without. After discontinuation of nitrous oxide, the concentration of nitrous oxide was measured at 15 sec intervals under controlled ventilation with 100% oxygen-sevoflurane. There was a significant correlation between nitrous oxide washout time and FEV1.0% (P < 0.05). Patients were further divided into two subgroups: FEV1.0% of over 70% (normal FEV) and that of less than 70% (low FEV). In the normal FEV group, the washout time was unaffected by PEEP. In the low FEV group, the washout times, with and without PEEP, were 7.07 +/- 0.93 min and 9.13 +/- 2.32 min, respectively. The difference was significant (P < 0.05). These results suggest that patients with chronic obstructive lung disease are at risk of delay in nitrous oxide elimination. This delay was found to be preventable with PEEP.

Aged↗

PubMed1998

[Propofol anesthesia for a patient with Arnold-Chiari deformity].

We gave anesthesia for the suboccipital decompression in a 25-yr-old female patient with Arnold-Chiari deformity. The induction and maintenance of anesthesia were performed with fentanyl, continuous infusion of propofol 10-3 mg.kg-1.h-1 and inhalation of nitrous oxide and oxygen, and the operation was performed without any complication. Postoperative course of the patient was also uneventful except a short-term pneumonia. Propofol is more advantageous compared with volatile anesthetics for decreasing intracranial pressure. This suggests that propofol is a suitable anesthetic agent for a patient with Arnold-Chiari deformity.

Adult↗

PubMed1997

[Preoperative flurbiprofen provides pain relief after laparoscopic cholecystectomy].

In a single-blind randomized prospective study, postoperative pain was assessed in 60 patients undergoing elective laparoscopic cholecystectomy with three types of anesthesia: standardized general anesthesia (control group), preoperative 50 mg flurbiprofen as an addition to the same method of general anesthesia (flurbiprofen group), and conventional combined epidural and general anesthesia with epidural administration of 0.25% bupivacaine 5-8 ml and 0.1-0.2 mg buprenorphine after surgery (epidural group). After the operation we found that the average time from the end of surgery to the first request for an analgesic was 3.9 h, 22.7 h and 43.7 h in the control, flurbiprofen and epidural group, respectively. Substantially it was longer in the flurbiprofen and epidural group than in the control group (P < 0.01 and < 0.001, respectively). Patients in the control group requested analgesics for a longer period of time after the initial request compared with patients in the other groups. Our results indicate that postoperative pain can be reduced when flurbiprofen is added to general anesthesia before surgery, although use of flurbiprofen was not as effective as the conventional combined epidural and general anesthesia used for treating pain after laparoscopic cholecystectomy.

Adult↗

PubMed1996

Oxamflatin: a novel compound which reverses malignant phenotype to normal one via induction of JunD.

In the course of screening for inhibitors of tumorigenic phenotype of K-ras-transformed NIH3T3 cells (DT cells), we found a novel compound, oxamflatin, an aromatic sulfonamide hydroxamate derivative, which induces flat phenotype in these cells and suppresses their anchorage-independent growth. In contrast to DT cells, in v-raf-transformed NIH3T3 cells, no change in their morphology and no specific inhibition of their anchorage-independent growth was observed. Interestingly, oxamflatin was effective to NIH3T3 cells transformed by constitutively activated mutant of MEK, indicating the possibility that oncogene-induced morphological change is not necessarily induced by common signaling pathway such as MAP kinase cascade. In oxamflatin-treated DT cells, the expression of transcription factor junD was highly augmented, resulting in trans-activation of fibronectin gene by junD via cyclic AMP responsive element in its promoter. This behavior of junD was confirmed to correlate well with partial blocking of malignant phenotype in DT cells. Thus, oxamflatin can be categorized as the first reagent which induces genes whose products can interfere with oncogene-dependent transformation.

3T3 Cells↗

PubMed1996

Developmental characteristics of topographic EEG in school-age children using an autoregressive model.

Developmental characteristics of the resting EEG were investigated in 47 school-age children using statistical analysis. Total and component EEG power were statistically analyzed between the subject groups from 7 to 14 year-old using our autoregressive pattern discrimination system. In early school-age children, significant topographic differences were seen in theta waves, while in late school-age children, the differences were found in alpha waves in the frontal and occipital regions, and in beta waves in the frontal region.

Adolescent↗