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Biomedical subjects

Y Yamada

Publications and source records attributed to Y Yamada.

At least 235 records · Page 13Linked to original sources
PubMed2001

Removal of carious dentin by Er:YAG laser irradiation with and without carisolv.

OBJECTIVE: The purpose of this study was to investigate the effectiveness of caries removal by using an Er:YAG laser irradiation with and without Carisolv, in vitro. BACKGROUND DATA: Effective ablation of dental hard tissues using Er:YAG laser has been reported and its application to caries removal has been expected. METHODS: Five extracted human teeth were selected for Carisolv and burr treatment. One-half of the lesion was treated with the Carisolv and then removed. The other half was removed using burr treatment. Fifty teeth were subjected to Er:YAG laser treatment with and without Carisolv. First, Carisolv was applied on one-half of each carious lesions for 1 min and followed by the Er:YAG laser irradiation at 60-140 mJ, 2 Hz for another 1 min; the other half was treated with Er:YAG laser only. The cavity was carefully assessed by DIAGNOdent. Each lesion was photographed before and after treatment, and the treated cavity was observed by microscopy and with scanning electron microscope (SEM). RESULTS: Our results revealed that application of Carisolv followed by Er:YAG laser irradiation at 100-140 mJ pulse energy effectively removed dentin caries. From the SEM study, it was found that the cavity surface treated with the laser revealed various patterns of microirregularity, often accompanied by microfissure propagation. There was also no smear layer. CONCLUSIONS: It was revealed that Er:YAG laser and Carisolv could provide an alternative technique for caries removal for conventional mechanical drilling and cutting.

Dental Caries↗
PubMed2001

A study on acquired acid resistance of enamel and dentin irradiated by Er,Cr:YSGG laser.

OBJECTIVE: This investigation was performed to evaluate the acid resistance of lased enamel and dentin by Er,Cr:YSGG laser to artificial caries-like lesions by spectrophotometry, and the ultrastructure of lased areas was investigated by scanning electron microscopy (SEM) in vitro. BACKGROUND DATA: In recent years, many studies have been performed to evaluate the effects of Er,Cr:YSGG laser on dental hard tissues. However, there have been only a few studies to determine if this laser is suitable for caries preventive treatments. METHODS: An Er,Cr:YSGG laser was used to irradiate the enamel or dentin samples from 30 extracted human molars at 6 W (67.9 J/cm2) or 5 W (56.6 J/cm2) pulse energy, respectively, with or without water mist. Samples were subjected to 2 microl of 0.1 M lactic acid solution (pH 4.8) for 24 h at 36 degrees C. The parts per million (ppm) of calcium ion (Ca2+) dissolved in each solution was determined by atomic absorption spectrophotometery, and the morphological changes were investigated by SEM. RESULTS: The lowest mean Ca2+ ppm was recorded in the lased samples. SEM observation showed that the lased areas were melted and seemed to be thermally degenerated. After acid demineralization, the thermally degenerated enamel or dentin surfaces were almost unchanged. CONCLUSIONS: The results of this study suggested that Er,Cr:YSGG laser irradiation with and without water mist appears to be effective for increasing acid resistance.

Dental Enamel↗
PubMed2001

Effect of pulsed Nd:YAG laser irradiation on acid demineralization of enamel and dentin.

OBJECTIVE: The purpose of this study was to investigate the effect of Nd:YAG laser irradiation on the acid demineralization of enamel and dentin by spectrophotometry. A mechanism of acquired acid resistance is also proposed. SUMMARY BACKGROUND DATA: The ability of Nd:YAG laser irradiation to the enhanced resistance to artificial caries formation is still controversial. METHODS: A pulsed Nd:YAG laser at 1.064-micron wavelength was used to irradiate the human enamel and dentin samples from 20 extracted human molars at the parameters of 1, 2, and 3 W and 20 pps for a total of 9 sec after painting with black ink. Samples were then subjected to 2 microliters of 0.1 M lactic acid solution (pH 4.8) for 24 h at 36 degrees C. The parts per million (ppm) of calcium ion (Ca2+) dissolved in each solution was determined by atomic absorption spectrophotometry and the morphological changes were also investigated by scanning electron microscopy (SEM). RESULTS: The lowest mean Ca2+ ppm was recorded in the samples irradiated at 3 W, in those by irradiated at 2 W and 1 W. The unlased samples showed the highest Ca2+ ppm. SEM observation showed that in the lased areas, the smear layer was partially melted and the underlying primary enamel or dentin seemed to be thermally degenerated. CONCLUSIONS: The results of this study suggested that melted smear layer and underlying enamel or dentin degenerated thermally by the heat treatment of Nd:YAG laser might play a major role to enhance resistance to artificial caries-like formation.

Calcium↗
PubMed2001

Analysis of surface roughness of enamel and dentin after Er,Cr:YSGG laser irradiation.

OBJECTIVE: The purpose of this investigation was to compare the surface roughness of enamel and dentin following the Er,Cr:YSGG laser irradiation and acid etching. BACKGROUND DATA: Laser-roughened enamel or dentin surfaces have been expected to enhance restorative materials bond strength. MATERIALS AND METHODS: Er,Cr:YSGG laser irradiation was performed in one half of each polished enamel or dentin sample at 3 W (33.9 J/cm2, with air 70% and water 20%,) pulse energy for 6 sec. Then the other half was treated with 37% phosphoric acid for 30 sec. Surface roughness and morphological studies were performed. RESULTS: It was found that surface roughness was significantly increased with the laser system. Scanning electron microscopy analysis showed that irradiated surface produces a rough surface that was completely lacking of a smear layer; there was also no cracking of enamel or dentin. CONCLUSION: Er,Cr:YSGG laser irradiation could provide an effective and alternative method to the acid etch technique.

Acids↗
PubMed2001

Assessment of systemic adverse reactions induced by ophthalmic beta-adrenergic receptor antagonists.

To assess quantitatively the risks of ophthalmic beta-blocking agents for cardiovascular and respiratory adverse reactions, we analyzed the binding kinetics of beta-blocking agents to the beta-1 and beta-2 adrenoceptors. The relationship between the occupancies for beta-1 and beta-2 adrenoceptors and the effects on the exercise pulse rate or the forced expiratory volume in one second (FEV1) after topical administration of carteolol, befunolol, timolol and betaxolol was analyzed using a ternary complex model. The beta-1 and beta-2 receptor occupancies after ophthalmic administration were calculated to be quite high as well as those after oral administration. The maximum occupancies for beta-1 and beta-2 receptors after ordinary ophthalmic administration were 52% and 88% for carteolol, 52% and 61% for befunolol, 62% and 82% for timolol, and 44% and 3% for betaxolol, respectively. Concave relationships were obtained between a decrease in exercise pulse rate and the beta-1 receptor occupancy and between a decrease in FEV1 and beta-2 receptor occupancy, respectively. Nasolacrimal occlusion was estimated to decrease the exercise pulse rate and FEV1 by 65% and 50%, respectively. The beta-1 and beta-2 adrenoceptor occupancies were proved to be the most appropriate indicators for cardiac and pulmonary adverse reactions evoked by ophthalmic beta-blocking agents.

Administration, Oral↗
PubMed2001

Attenuation of haemodynamic responses to tracheal intubation by the styletscope.

Tracheal intubation often causes a haemodynamic response probably generated by direct laryngoscopy. The StyletScope is a new intubation device that does not require direct laryngoscopy. We prospectively measured haemodynamic changes after tracheal intubation using the StyletScope. The increase of heart rate was less during tracheal intubation with the StyletScope when compared with the Macintosh laryngoscope.

Adult↗
PubMed2001

Abnormal axonal inward rectifier in streptozocin-induced experimental diabetic neuropathy.

In order to explore the pathophysiology of diabetic neuropathy, we studied serial changes of axonal excitability in 20 adult Wistar rats with streptozocin-induced diabetes using the technique of threshold electrotonus (TE). After persistent hyperglycaemia had developed, rats were divided into two groups: nine were fed a diet containing aldose reductase inhibitor (Epalrestat 30 mg/kg/day) (ARI(+) group) and 11 were fed a diet without the inhibitor (ARI(-) group). Eight normal control rats of similar age (NC group) were also studied. We monitored membrane properties of motor axons in the tail for 3 months using TE to measure the changes in excitability induced by subthreshold polarizing currents while recording compound muscle action potentials (CMAPs) in the tail muscle. The ARI(-) group showed a significant increase in CMAP latency 1 month after streptozocin injection, and by 3 months there was significantly lower excitability after hyperpolarization for 100 ms compared with the NC group. A similar change in TE was reproduced by injection of caesium chloride, an inhibitor of inward rectification. By contrast, the ARI(+) group exhibited no significant change in TE or latency at 3 months, although they showed significant body weight loss and hyperglycaemia. These findings indicate that inward rectification is reduced in an experimental model, as in human diabetes, and that blocking the polyol pathway with an ARI prevents this reduction. Reduced inward rectification potentiates conduction block caused by activity-dependent hyperpolarization and may underlie the decreased vibratory sensation seen in the early stage of diabetic neuropathy.

Action Potentials↗
PubMed2001

Complete response achieved following administration of S-1 in a patient with adrenal gland metastasis of 5-FU-resistant gastric cancer: a case report.

A 62-year -old male patient who had undergone total extirpation of type 3 cancer of the greater curvature of the upper stomach body at another hospital received postoperative chemotherapy with 5-FU and methotrexate. The patient was subsequently treated with oral 5-FU. About 1 year later, a 4 cm tumor of the left adrenal gland was revealed by abdominal CT and diagnosed as gastric cancer metastasizing to the adrenal gland. The patient was referred to our hospital for close examination and treatment and admitted. After his informed consent had been obtained, the patient received one course (4-week administration and 2-week withdrawal) of S-1 at 50 mg/body x 2/day. Abdominal computed tomography performed after the end of the one course revealed that the tumor had become undetectable. This condition was still maintained at the end of two courses and judged to be complete response (CR) (in accordance with the WHO Efficacy Judgment Criteria). CR has continued to be maintained to the present time, even after seven courses. There has been no previous report of S-1 showing remarkable effectiveness in a patient with 5-FU-resistant gastric cancer metastasizing to the adrenal gland. We consider that the efficacy of S-1 for treatment of 5-FU-resistant gastric cancer should be verified.

Adrenal Gland Neoplasms↗
PubMed2001

Significance of prostate-specific antigen--alpha(1)-antichymotrypsin complex for diagnosis and staging of prostate cancer.

OBJECTIVE: To evaluate the clinical significance of measuring the prostate-specific antigen-alpha(1)-antichymotrypsin (PSA-ACT) for differentiating prostate cancer from benign prostate hypertrophy (BPH) and for the staging of prostate cancer. METHODS: Before treatment, total PSA (tPSA) and PSA-ACT were measured in 120 patients with prostate cancer and in 150 patients with BPH using immunofluorometric techniques with different monoclonal antibodies against PSA and ACT. Furthermore, the tPSA and PSA-ACT densities of the whole prostate (PSAD and ACTD, respectively) were calculated. RESULTS: tPSA, PSAD, PSA-ACT and ACTD levels in patients with prostate cancer paralleled the clinical stage and were significantly higher than those in patients with BPH. Furthermore, these four values were significantly higher in patients with pathologically extraprostatic disease than those with organ-confined disease. Receiver operating characteristics analysis among patients with PSA values of 4.1-10 ng/ml revealed that the areas under the curve for tPSA and ACTD were similar to those for PSA-ACT and ACTD, respectively and that no significant differences in the differentiation between prostate cancer and BPH were observed among these parameters. CONCLUSIONS: Measurement of PSA-ACT provides useful information for the clinical staging of prostate cancer and differential diagnosis between prostate cancer and BPH; however, compared with tPSA, PSA-ACT may not be significantly superior in the diagnosis and staging of prostate cancer.

Diagnosis, Differential↗
PubMed2001

Molecular cloning of delta-4, a new mouse and human Notch ligand.

Complementary DNAs encoding a previously unidentified mouse Notch ligand and its human ortholog were isolated. The new Notch ligand contains a signal sequence, a DSL domain, eight epidermal growth factor-like repeats, a transmembrane domain, and an intracellular region, all of which are characteristics of members of the Delta protein family. The new protein was therefore designated Delta-4. Several previously unidentified sequences in both the extracellular and intracellular regions were shown to be conserved among vertebrate Delta proteins. The tissue distribution of Delta-4 mRNA resembles that previously described for Notch-4 (Int-3) transcripts. However, in situ hybridization with mouse lung revealed that Delta-4 mRNA is abundant in squamous alveolar cells that neighbor endothelial cells; Notch-4 expression is largely restricted to the latter cell type. Soluble forms of the extracellular portion of Delta-4 inhibit the apparent proliferation of human aortic endothelial cells, but not human pulmonary arterial endothelial cells.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Lactate is correlated with the indocyanine green elimination rate in liver resection for cirrhotic patients.

UNLABELLED: The role of lactate in liver ischemia-reperfusion injury in cirrhosis has not been clarified. Fifty patients with hepatocellular carcinoma who underwent partial liver resection under Pringle's maneuver were included in this study. We performed the indocyanine green clearance test before the operation and three times during the surgery to calculate its elimination rate. Blood lactate and base excess were measured at the corresponding times. Systolic and diastolic systemic arterial pressure, heart rate, cardiac index, and esophageal temperature were monitored. Aminotransferase levels were recorded the day before the operation, 1 h after the operation, and on the first and third postoperative days. We calculated the increase or decrease in lactate levels during the preischemic, ischemic, and postischemic phases, and examined the correlation between these results and the changes in indocyanine green elimination rate and some clinical factors. The lactate levels increased before reperfusion and began to decrease after reperfusion. The lactate increase and decrease during the ischemic and postischemic phases correlated with the change in indocyanine green elimination rate (P < 0.0001 and P = 0.02 for the respective phases). The lactate increase during the preischemic phase correlated with the duration of the preischemic phase (P < 0.0001). In cirrhotic patients who undergo liver resection with Pringle's maneuver and who do not show postoperative liver failure, the blood lactate profile might be a reliable indicator of liver metabolic capacity during surgery. IMPLICATIONS: In cirrhotic patients who underwent liver resection with Pringle's maneuver, the lactate increase and decrease during the ischemic and postischemic phases correlated with the change in the indocyanine green elimination rate. The blood lactate profile might be a reliable indicator of liver metabolic capacity during surgery.

Adult↗
PubMed2001

Osteonecrosis of the femoral head after allogeneic bone marrow transplantation.

A comparative retrospective analysis of 100 consecutive patients after bone marrow transplantation was performed with magnetic resonance imaging in addition to plain radiography for the development of osteonecrosis of the femoral head. The incidence and risk factors for osteonecrosis of the femoral head were identified, comparing various parameters concerning bone marrow transplantation between the groups with and without evidence of osteonecrosis. Nineteen (19%) of 100 patients had osteonecrosis of the femoral head develop. Four factors were found to be statistically significantly different between patients who had osteonecrosis develop and those who did not: younger age at the time of bone marrow transplantation, chronic graft-versus-host disease, cumulative dose of steroid, and intravenous pulse therapy with methylprednisolone. It was concluded that a low rate of complications and low dose steroid administration would reduce the incidence of osteonecrosis after bone marrow transplantation.

Adolescent↗
PubMed2001

Association of polymorphisms of the transforming growth factor-beta1 gene with genetic susceptibility to osteoporosis.

Osteoporosis exhibits a substantial genetic component. Although polymorphisms of a variety of genes have been associated with bone mineral density and genetic susceptibility to osteoporosis, the genes responsible for these traits have not been definitively identified. We have shown that a T869-->C polymorphism of the transforming growth factor-beta1 gene, which results in a Leu-->Pro substitution at amino acid 10, is associated with bone mineral density in Japanese adolescents and postmenopausal women, with genetic susceptibility to both osteoporosis and vertebral fracture, and with the outcome of treatment for osteoporosis with active vitamin D. We have also shown that a C-509-->T polymorphism in the promoter region of this gene is associated with both bone mineral density and the prevalence of osteoporosis in postmenopausal women. In addition, analysis of combined genotypes for both the C-509-->T and T869-->C polymorphisms revealed that bone mineral density decreases and the susceptibility to osteoporosis increases with the number of T alleles. Thus, combined genotyping of the C-509-->T and T869-->C polymorphisms may prove beneficial in the prevention of osteoporosis in postmenopausal Japanese women. I review here the association of transforming growth factor-beta1 gene polymorphisms with genetic susceptibility to osteoporosis, which has provided insight into the function of transforming growth factor-beta1 as well as into the role of genetic factors in the development of osteoporosis.

Adolescent↗
PubMed2001

Asaia siamensis sp. nov., an acetic acid bacterium in the alpha-proteobacteria.

Five bacterial strains were isolated from tropical flowers collected in Thailand and Indonesia by the enrichment culture approach for acetic acid bacteria. Phylogenetic analysis based on 16S rRNA gene sequences showed that the isolates were located within the cluster of the genus Asaia. The isolates constituted a group separate from Asaia bogorensis on the basis of DNA relatedness values. Their DNA G+C contents were 58.6-59.7 mol%, with a range of 1.1 mol%, which were slightly lower than that of A. bogorensis (59.3-61.0 mol%), the type species of the genus Asaia. The isolates had morphological, physiological and biochemical characteristics similar to A. bogorensis strains, but the isolates did not produce acid from dulcitol. On the basis of the results obtained, the name Asaia siamensis sp. nov. is proposed for these isolates. Strain S60-1T, isolated from a flower of crown flower (dok rak, Calotropis gigantea) collected in Bangkok, Thailand, was designated the type strain ( = NRIC 0323T = JCM 10715T = IFO 16457T).

Acetobacteraceae↗
PubMed2001

Development of a magnetic sensing device for tooth displacement under orthodontic forces.

We have developed a system for measuring tooth displacement from orthodontic force. Eight small magnetic sensors and a magnet are combined to measure three-dimensional displacement. Sensors, arranged cubically in the three planes of space, are placed in the mouth and fixed to the posterior teeth by a splint. A magnet is placed in the center of the eight sensors and attached to a front tooth that is subjected to orthodontic force. Sensors detect the magnet's movement as target tooth displacement. The system was designed to achieve displacement resolution of 1 microm. The mean percentage of measurement errors was determined to be less than 1% in a 600-cubic-microm volume from calibration. The system was tested clinically on human teeth. Although the oral environment, with high temperature and humidity, was not agreeable with the sensors, this system was stable and accurate enough for quantitative measurement of tooth displacement. The advantage of this system is the ability to detect tooth trajectories by decomposing displacement into translation and rotation and to determine the position of the center of rotation from these parameters.

Calibration↗