Biomedical subjects

R Nishimura

Publications and source records attributed to R Nishimura.

At least 163 records · Page 9Linked to original sources

PubMed1994

Restoration of oral function after maxillectomy with osseous integrated implant retained maxillary obturators.

This study assesses the success rate of osseous integrated implantation in assisting the prosthetic obturation of maxillectomy defects. Twenty-three patients received a total of 85 osseous integrated implants used for retaining maxillary obturators between 1985 and 1993. Defects include 13 radical maxillectomies, 5 premaxillary resections, 4 subtotal maxillectomies, and 1 soft-palate resection. Thirteen patients (50 implants) received a radiation dose ranging from 5,040 to 7,940 cGy. Implants can be placed at the time of ablation or subsequently. Efforts were made to spare uninvolved segments of the maxilla, especially premaxillary segments and tuberosities, at the time of ablation. Following a 6-month period of integration, implants were uncovered and utilized in prosthetic rehabilitation. Specific implant sites reveal variable success rates, with the anterior maxilla being 86% successful compared with the posterior maxilla being 57% successful. Radiation reduces the success rate from 80% to 55%, although it does not eliminate a patient from being a candidate for implantation. Prosthetic rehabilitation of large maxillary defects can be greatly facilitated with the use of osseous integrated implants in the remaining midfacial skeleton.

Alveolar Bone Loss↗

PubMed1994

A new function for a phosphotyrosine phosphatase: linking GRB2-Sos to a receptor tyrosine kinase.

Autophosphorylated growth factor receptors provide binding sites for the src homology 2 domains of intracellular signaling molecules. In response to epidermal growth factor (EGF), the activated EGF receptor binds to a complex containing the signaling protein GRB2 and the Ras guanine nucleotide-releasing factor Sos, leading to activation of the Ras signaling pathway. We have investigated whether the platelet-derived growth factor (PDGF) receptor binds GRB2-Sos. In contrast with the EGF receptor, the GRB2 does not bind to the PDGF receptor directly. Instead, PDGF stimulation induces the formation of a complex containing GRB2; 70-, 80-, and 110-kDa tyrosine-phosphorylated proteins; and the PDGF receptor. Moreover, GRB2 binds directly to the 70-kDa protein but not to the PDGF receptor. Using a panel of PDGF beta-receptor mutants with altered tyrosine phosphorylation sites, we identified Tyr-1009 in the PDGF receptor as required for GRB2 binding. Binding is inhibited by a phosphopeptide containing a YXNX motif. The protein tyrosine phosphatase Syp/PTP1D/SHPTP2/PTP2C is approximately 70 kDa, binds to the PDGF receptor via Tyr-1009, and contains several YXNX sequences. We found that the 70-kDa protein that binds to the PDGF receptor and to GRB2 comigrates with Syp and is recognized by anti-Syp antibodies. Furthermore, both GRB2 and Sos coimmunoprecipitate with Syp from lysates of PDGF-stimulated cells, and GRB2 binds directly to tyrosine-phosphorylated Syp in vitro. These results indicate that GRB2 interacts with different growth factor receptors by different mechanisms and the cytoplasmic phosphotyrosine phosphatase Syp acts as an adapter between the PDGF receptor and the GRB2-Sos complex.

3T3 Cells↗

PubMed1994

Antagonistic effects of antipamezole on medetomidine-midazolam induced sedation in dogs.

Antagonistic effect of atipamezole (80 micrograms/kg) on medetomidine (20 micrograms/kg)-midazolam (0.3 mg/kg) induced sedation was evaluated in dogs. Atipamezole effectively reversed sedation and significantly shortened arousal time and total recovery time without apparent side effects. Atipamezole also effectively reversed changes in heart rate, respiratory rate and body temperature produced by medetomidine-midazolam. The possible use of atipamezole as a reversal agent might enhance the value and availability of medetomidine-midazolam for a chemical restraint agent in dogs.

Adrenergic alpha-Agonists↗

PubMed1994

Histopathological findings of the digits in dairy cows in Japan.

Two hundred and thirty-nine digits of 45 Holstein dairy cows, which were raised in typical Japanese dairy farms and received poor hoof management, were randomly obtained in the slaughterhouses and examined histopathologically. The findings were classified into 5 grades on the basis of the severity of circulatory disturbances and of keratogenesis. The lesions from Grade 1 to 5 were considered as manifestations of serial lesions indicating that subclinical laminitis advanced to other hoof lesions. The incidence of Grade 2, regarded as subclinical laminitis, reached approximately 50% of digits examined. The lesions classified as Grades 3 (23.9%) and 4 (5.4%) were mainly characterized by circulatory disturbances, which were similar to those of chronic laminitis in the previous reports. The incidence of Grade 5, characterized by sole ulcer, was 5.4%. It is suggested that a considerable number of daily cows in Japan suffered from subclinical laminitis, which may be the cause of recent high incidence of hoof diseases in dairy cows.

Animals↗

PubMed1994

Morphological analysis of cervical vertebrae in ataxic foals.

Morphological differences between cervical vertebrae were statistically analyzed in ataxic foals to clarify abnormal structural factors in the pathogenesis of this problem. At first, multiple regression analysis and cluster analysis were performed with 28 variables in C3-C7 of 39 control foals without lameness. As a result, there were no sex differences in the growth of all cervical vertebral sites, and the most suitable categorization of the age of the foals was 3 clusters of 8 months old or younger, 9-12 months old and 13 months old or older in any sites in the cervical vertebrae. Twenty-eight ataxic and 19 control foals at the age of 13 months or older were then used for discriminant analysis with 20 variables. As a result, 1-7 variables on C3-C7 were selected for sufficient discrimination, in which the heights of the cranial and caudal orifices of the spinal canal, longitudinal length of the vertebral head and height of the vertebral fossa strongly contributed to the discrimination of all the cervical vertebrae. In addition, the widths and longitudinal diameters of the articular processes on articular surfaces strongly contributed to the discrimination of the caudal region of the neck. In conclusion, it was suggested that the lesion in the cervical spinal cord observed in ataxic foals was caused by morphological abnormalities including osteochondrosis and subsequent degenerative joint disease in the cervical vertebrae.

Animals↗

PubMed1994

Efficacy of the new radiographic measurement method for cervical vertebral instability in wobbling foals.

Cervical myelography and survey radiography was performed on 12 light breed wobbling foals and a new radiographic measurement method was applied for more accurate diagnosis of cervical vertebral instability. Ratios of stenosis of the spinal canal on survey radiography and myelography using relative values in an individual foal were defined on radiograms of lateral flexed position of mid-cervical region, and coincidence between the ratios and histopathological lesions in the cervical spinal cord was investigated. Five of 6 foals had ratios of stenosis on myelography more than 40% at the intervertebral sites where the most severe histopathological lesions were observed. Four of 6 foals had ratios of stenosis on survey radiography more than 40% at the intervertebral sites where the most severe histopathological lesions were observed. Four of 6 foals had ratios of stenosis on survey radiography more than 40% at the intervertebral sites where the most severe histopathological lesions were observed. False-positive diagnosis of CVI was observed in 1 out of 6 foals without histopathological lesion when both ratios of stenosis on myelography and survey radiography were applied. Although the standard value of 40% should be further investigated, the new radiographic measurement method in this study is very useful in clinical diagnosis of cervical vertebral instability in wobbling foals, and the presence of lesions in the cervical spinal cord and their sites by survey radiography may be estimated more accurately.

Animals↗

PubMed1994

Relationships between radiography of cervical vertebrae and histopathology of the cervical cord in wobbling 19 foals.

Nineteen wobbling foals (17 males and 2 females) showing lameness of hindlimbs at 6 to 21 months of age were investigated radiographically and histopathologically. Minimum sagittal diameter (MSD), minimum flexion diameter (MFD) and minimum dural sagittal diameter (MDD) were measured on plain radiograms or myelograms taken at neutral and flexed positions as indicators of narrowed vertebral canal. After necropsy, the cervical spines and the spinal cord were examined macroscopically and respectively the relationships between radiographic findings and the corresponding morphological lesions were evaluated. Radiographically, lower values than each minimum reference limits were recorded in 14 foals in MSD, 5 foals in MFD and 6 foals in MDD, respectively. According to the histopathologic examination, the disappearance of axons and myelin sheaths, vacuolated spongy degeneration and appearance of macrophages were recognized symmetrically in the white matter of the cervical cord. These lesions were centrally located at the spinal cord radiographically demonstrated as compressed sites in 12 out of 17 foals examined. Macroscopically, asymmetrical overgrowth of one side of the process, encroachment of articular processes into the intervertebral foramina and proliferation of bone around articular facets were observed in the articular processes of bone specimens in the caudal neck of 6 foals. In conclusion, the equine incoordination might mainly be caused by the cervical stenotic myelopathy resulting from cervical vertebral malformation, and therefore the cervical vertebral radiography, especially myelography, is quite very important and effective for the diagnosis of wobbling foals.

Animals↗

PubMed1994

Cardiopulmonary effects of medetomidine-midazolam and medetomidine-midazolam- atipamezole in laboratory pigs.

The cardiopulmonary effects of medetomidine (40 micrograms/kg)-midazolam (0.2 mg/kg) and medetomidine (40 micrograms/kg)-midazolam (0.2 mg/kg)-atipamezole (160 micrograms/kg) were evaluated in laboratory pigs. The intramuscular administration of medetomidine-midazolam caused a pressor response, characterized by a rapid increase in arterial and pulmonary arterial pressure mediated mainly through systemic and pulmonary vasoconstriction. These pressures decreased after reaching a peak 5 to 10 min after the administration of sedatives, but maintained higher values than the base-line. However, all these changes caused by medetomidine-midazolam were within the physiological fluctuation. In addition, this combination did not induce bradycardia, subsequent hypotension or a significant decrease in cardiac output, which were generally observed with alpha 2-adrenoceptor agonists, and caused fewer changes in the respiratory system. The administration of atipamezole resulted in a marked transient decrease in vascular resistance, and caused a decrease in blood pressure and increases in cardiac output and heart rate. However, these changes were relatively small and sustained for a short time. Thus the combination of medetomidine-midazolam and atipamezole have minimal cardiopulmonary effects and might be used safely in laboratory pigs.

Adrenergic alpha-Agonists↗

PubMed1994

Plasma concentrations of substances suspected as uremic toxins in experimentally induced and spontaneous uremic dogs.

Plasma concentrations of four substances, a pyridine derivative (S7a), uric acid (UA), hippuric acid (HA) and kynurenic acid (KA), suspected as uremic toxins in dogs were determined in dogs with experimentally induced uremia by the ligations of renal arteries, spontaneous uremic dog patients and normal dogs. In experimentally induced uremic dogs, plasma concentrations of S7a, HA and KA showed continuous increase after the ligation of renal arteries together with a significant correlation to plasma creatinine concentration (Cre). Plasma UA concentration increased rapidly, but it showed a varying fluctuation without showing any correlation to Cre. Plasma concentrations of S7a, UA, HA and KA in spontaneous uremic dogs were almost within the ranges of those of experimentally induced uremic dogs.

Animals↗

PubMed1994

Effects of medetomidine-midazolam on plasma glucose and insulin concentrations in laboratory pigs.

Effects of medetomidine (40 micrograms/kg)-midazolam (0.2 mg/kg) on plasma glucose and insulin concentrations were evaluated in laboratory pigs. Intramuscular injection of medetomidine-midazolam induced a gradual hyperglycemic response associated with hypoinsulinemia which was much smaller than that by 80 micrograms/kg of medetomidine alone and was almost within a physiological fluctuation. These mild responses induced by medetomidine-midazolam were antagonized by use of an alpha 2-adrenoreceptor antagonist atipamezole (160 micrograms/kg), therefore those changes were thought to be mainly attributed to the effect of medetomidine on alpha 2-adrenoreceptors. A combination of medetomidine at a low dose and midazolam reduces undesirable effects, while providing more profound sedation than medetomidine alone in laboratory pigs.

Adrenergic alpha-Agonists↗

PubMed1994

20 alpha-hydroxysteroid dehydrogenase activity in canine spontaneous neoplasms.

20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD) activities in 57 neoplastic tissues surgically removed from dogs were measured. Forty-eight of 57 tumor samples were shown to possess 20 alpha-HSD activity. These tissues were histopathologically classified into 22 benign and 26 malignant tumors. Among these tumors, mixed tumor types demonstrated the higher 20 alpha-HSD activity than epithelial and non-epithelial types, and malignant tumors of each tissue type showed slightly but not significantly higher 20 alpha-HSD activities comparing with the corresponding benign ones. Comparing with the activity of normal tissues examined, the corresponding tumor tissues showed significantly higher 20 alpha-HSD activities. Thus, 20 alpha-HSD activity was found in neoplastic tissues at a considerable high rate and the activity seemed to be higher in pathologically malignant tumors.

20-Hydroxysteroid Dehydrogenases↗

PubMed1994

Computed tomography on renal masses in dogs and cats.

Computed tomography (CT) was performed on renal tumors (Wilms' tumor and renal cell carcinoma) and renal cysts in dogs and cats. CT images in renal tumors were well correlated with macroscopic findings, and contrast CT images were quite useful in differentiating tumoral regions from non-tumoral ones. On renal cysts, intravenous pyelography and ultrasonography were as effective as CT images in morphological diagnosis, but CT was considered to be superior for evaluating three-dimensional (3-D) relationships in complicated lesions.

Animals↗

PubMed1994

Comparison of sedative effects induced by medetomidine, medetomidine-midazolam and medetomidine-butorphanol in dogs.

Sedative effects of combinations of medetomidine at 20 micrograms/kg--midazolam at 0.3 mg/kg (Me-Mi) and medetomidine at 20 micrograms/kg--butorphanol at 0.1 mg/kg (Me-B) were evaluated comparing with those of medetomidine alone (20, 40 and 80 mu/kg). All dogs given Me-Mi or Me-B were smoothly and rapidly induced to more profound and longer sedation than those by medetomidine alone. Especially, Me-Mi produced desirable sedation with moderate reflex depression, analgesia, excellent muscle relaxation and immobilization without further side effects. This potent effect of this combination seemed to be induced by a synergistic interaction between medetomidine and midazolam. This combination is available and valuable as a chemical restraint agent in dogs for various diagnostic or therapeutic procedures accompanied by light pain.

Animals↗

PubMed1993

Nck associates with the SH2 domain-docking protein IRS-1 in insulin-stimulated cells.

Nck, an oncogenic protein composed of one SH2 and three SH3 domains, is a common target for various cell surface receptors. Nck is thought to function as an adaptor protein to couple cell surface receptors to downstream effector molecules that regulate cellular responses induced by receptor activation. In this report, we show that Nck forms a stable complex in vivo with IRS-1 in insulin-stimulated cells. The interaction between IRS-1 and Nck is mediated by the binding of the SH2 domain of Nck to tyrosine-phosphorylated IRS-1. Although Nck associates with IRS-1, Nck phosphorylation is not affected by insulin stimulation. Furthermore, in vitro and in vivo studies show that the SH2 domains of Nck, GRB2, and p85 bind distinct phosphotyrosine residues in IRS-1. After insulin stimulation all three signaling molecules can be found complexed to a single IRS-1 molecule. These findings provide further evidence that, in response to insulin stimulation, IRS-1 acts as an SH2 docking protein that coordinates the regulation of various different signaling pathways activated by the insulin receptor.

Adaptor Proteins, Signal Transducing↗

PubMed1993

Charge isomers of urinary bikunin (trypsin inhibitor).

It was observed that the purified urinary bikunin (trypsin inhibitor) consisted of four major isomers with different electric charges which could be separated by HPLC using a Mono Q column. These isomers revealed the same antitrypsin activity and did not show any differences in the apparent molecular weight by SDS-PAGE, amino-acid composition, N-terminal amino-acid sequence (1-40) and C-terminal amino acid (Leu). The contents of sialic acid and uronic acid were also identical among these isomers. However, analysis of chondroitin sulfate revealed all the glycosaminoglycan chains of these isomers were undersulfated, comprising nonsulfated and 4-sulfated disaccharide units, and 4-sulfated disaccharide unit ratio varied among these isomers. After the chondroitin ABC lyase digestion, all the isomers were eluted at the same position on a Mono Q column chromatography. These results indicated that charge isomers of urinary bikunin was attributed to the difference on sulfation ratio in a glycosaminoglycan chain.

Amino Acids↗

PubMed1993

Liquid chromatography-mass spectrometry for the determination of medetomidine and other anaesthetics in plasma.

A liquid chromatographic-atmospheric pressure chemical ionization mass spectrometric method is presented for the simultaneous determination of medetomidine and other anaesthetic drugs in solutions and dog plasma. The drugs examined were flumazenil, butorphanol, atropine, ketamine, xylazine, medetomidine, atipamezole and midazolam. The separation was carried out on a reversed-phase column using methanol-0.1 M ammonium acetate (3:2) as eluent.

Anesthetics↗

PubMed1993

Thoracic vertebral bone metastasis from uterine leiomyosarcoma.

We report a patient with solitary thoracic vertebral bone metastasis (Th 8) from uterine leiomyosarcoma. The vertebral metastatic lesion was treated surgically, and vertebral body replacement with ceramic prosthesis and anterior spinal stabilization were performed. Such aggressive surgical intervention for solitary vertebral bone metastasis may contribute to the improvement of prognosis and maintenance of general quality of life in the patient.

Female↗

PubMed1993

Correlation of sequential magnetic resonance imaging of experimental brain ischemia with histologic changes in gerbils.

RATIONAL AND OBJECTIVES: To characterize Gd-DTPA-enhanced T1-weighted images (Gd-T1WI) in the acute phase of cerebral ischemia, sequential magnetic resonance images of 84 Mongolian gerbils with occlusion of the left common carotid artery were evaluated. METHODS: Twelve gerbils were used for each group, among which the occlusion time (5-180 minutes, permanent) varied. Histopathologic changes developing within the first 2 weeks were compared with patterns on T2-weighted images and Gd-T1WI on a 7.05-Tesla system. RESULTS: Although T2-weighted images and Gd-T1WI both demonstrated abnormal findings as early as 3 hours after occlusion, Gd-T1WI demonstrated more definite abnormalities with shorter occlusion than T2-weighted images (especially when there were only mild histologic changes). The earliest changes were an abnormal enhancement around and within the lateral ventricles in temporary occlusions; this was not demonstrated in permanent occlusions. CONCLUSIONS: Magnetic resonance images using Gd-DTPA demonstrated abnormal permeability within 3 hours after occlusion, and the pattern is correlated with intensity of ischemia.

Animals↗