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Biomedical subjects

T Yagi

Publications and source records attributed to T Yagi.

At least 577 records · Page 32Linked to original sources
PubMed1986

Cervico-vestibular interaction in eye movements.

The cervico-vestibular interaction was investigated in normal subjects and patients with unilateral labyrinthine dysfunction using neck vibratory stimulation and caloric stimulation. There is a functional interaction between sensory inputs from the neck proprioceptors and the peripheral labyrinth in the patients with unilateral labyrinthine dysfunction. However, this interaction was not observed in normal subjects. This result indicates that the role of the cervical sensory inputs in normal subjects and the patients is different. That is, inputs from the neck proprioceptors have little effect on the control of eye movements in normal subjects, whereas the neck inputs are quite important for the control of eye movements in patients with unilateral labyrinthine dysfunction.

Afferent Pathways↗
PubMed1986

Pyruvate dehydrogenase and the path of lactate degradation in Desulfovibrio vulgaris Miyazaki F.

Pyruvate dehydrogenase from Desulfovibrio vulgaris Miyazaki F was partially purified from the soluble fraction of the bacterial sonicate, and characterized. The enzyme catalyzes oxidative decarboxylation of pyruvate to produce acetyl-CoA, in contrast to statements in current review articles in which acetyl phosphate is indicated to be a direct decomposition product of pyruvate in sulfate-reducing bacteria. The established reaction stoichiometry is: pyruvate + CoA + FMN----acetyl-CoA + CO2 + FMNH2. The Km values are 2.9 mM for pyruvate, 32 microM for CoA and 6.7 mumol for FMN. Participation of thiamine diphosphate in the enzymic process was not proven. 2-Oxobutyrate, but not 2-oxoglutarate, can substitute for pyruvate. The three flavin compounds, FMN, FAD, and flavodoxin, as well as clostridial ferredoxin, serve as electron carriers for the enzyme. Thus the enzyme is a kind of pyruvate synthase [EC 1.2.7.1], but acts in the direction of pyruvate degradation in the growing cells. The rate of cytochrome C3 reduction is extremely low, but in the presence of flavodoxin as an electron mediator, the reduction rate of cytochrome C3 becomes faster than the reduction rate of flavodoxin alone. It seems that the physiological electron acceptor for this enzyme is flavodoxin, which might be complexed with cytochrome C3 to produce a very efficient electron transfer system in the cell. The soluble fraction of D. vulgaris cells has been proved to contain, in addition to the pyruvate dehydrogenase, lactate dehydrogenase (Ogata, M., Arihara, K., & Yagi, T. (1981) J. Biochem. 89, 1423-1431), phosphate acetyltransferase and acetate kinase, i.e., all the enzymes necessary to convert lactate to acetate, producing ATP by substrate level phosphorylation.

Acetyl Coenzyme A↗
PubMed1986

Crystallographic study of cytochrome c553 from Desulfovibrio vulgaris Miyazaki.

Cytochrome c553 from the sulfate-reducing bacterium, Desulfovibrio vulgaris Miyazaki, has been crystallized. The combination of microdialysis and vapor diffusion allowed successful crystallization. The crystals were of good quality, and useful data were obtained that extended to the nominal resolution of 1.3 A. The space group is P4(3)2(1)2 with cell dimensions of a = b = 42.7 A, c = 103.4 A. More than twenty heavy-atom reagents were screened with the isomorphous replacement technique, and only the mersalyl derivative could be used for the phase determination. The single isomorphous replacement method combined with the anomalous scattering effect of the Hg-atom in mersalyl and the Fe-atom of the heme group was used for the phase determination.

Crystallization↗
PubMed1986

Interaction between the soma and the axon terminal of retinal horizontal cells in Cyprinus carpio.

Intracellular recordings were made from the monophasic horizontal cells of the carp retina which are known to respond with a sustained hyperpolarization to all visible monochromatic light. The receptive field of each subcellular structure, the soma and the axon terminal, was determined using a long narrow slit of light. Somata and axon terminals showed receptive fields that encompassed almost the entire retina. This observation suggests that each aggregate of the subcellular parts forms a synctial structure. However, with increasing distance from the slit, the response peak decayed more steeply in somata than in axon terminals. The spatial decline of the peak consisted of two exponential functions in somata, while a single exponential function in axon terminals. The length constant of the axon terminal was similar to the larger length constant revealed in the soma. This finding suggests an electrical communication at work between the soma and the axon terminal. A quantitative account was made in light of a discrete resistive network model which consists of a pair of syncytia coupled through connecting axons; one represents the contiguous layer of somata and the other the contiguous layer of axon terminals. Relevant response properties computed from the model analysis were in satisfactory agreement with experimental data. It was concluded that the soma and the axon terminal of the horizontal cell are electrically connected in the cyprinid retina.

Animals↗
PubMed1986

Pure-tone audiometry of patients with auditory brainstem response abnormalities.

To determine the pure-tone thresholds of patients with brainstem disorders, pure-tone audiometry was done on 22 patients with partial auditory brainstem response wave disappearance (including wave I response, wave I-III response, and wave I-IV response). This group of patients was selected since partial wave disappearance indicates pathology of the auditory nerve and/or the brainstem auditory pathway. The pure-tone threshold of these patients was essentially normal or very mildly impaired, except for patients with an acoustic tumor or an other cerebellopontine angle tumor.

Audiometry↗
PubMed1986

Biological, functional and morphological characteristics of human bone and soft tissue tumors in nude mice.

Since 1975, we have performed experiments on transplantation of bone and soft tissue tumors obtained, from 115 patients into nude mouse. In the present study, we analyzed biological, functional and morphological characteristics of the tumors transplanted in nude mice. The incidence of tumor take in the initial transplantation was 55.6% (40 of 72 cases) for malignant bone tumors, 42.9% (15 of 35 cases) for malignant soft tissue tumors and 0% for benign bone and soft tissue tumors. In particular, the incidence of tumor take was high for osteosarcoma (60%, 36 of 60 cases) and for rhabdomyosarcoma (70%, 7 of 10 cases). There were 22 tumors transplanted serially for more than 5 passages. The mean survival time for mice with serially transplantable bone and soft tissue tumors was 76.0 days and mean tumor growth index was 0.25. Serum LDH levels were as high as more than 5,000 Wrób. U for 8 of 12 lines tested. Serum ALP levels were normal for all tumors other than osteosarcoma. In mice transplanted with osteosarcoma, serum ALP levels were higher than 10 KAU for 8 of 13 lines tested. Pulmonary metastasis was seen in 5 of 9 osteosarcomas examined. For many of serially transplantable tumors, tumorigenicity was observed in nude mice by various transplantation routes including the subcutaneous, intraperitoneal and intravenous routes via the tail vain. Serially transplantable osteosarcomas were morphologically classified into three groups based on osteoid formation; those in which osteoid formation disappeared immediately, those in which osteoid formation decreased gradually, and those in which osteoid formation was unchanged or even increased. Osteoid was found for 6 of 13 lines examined. For 4 of the 6 tumors zone phenomenon was maintained during passages. For 2 lines among those in which osteoid disappeared, histological type was changed into quite another type from the original type of the tumor.

Animals↗
PubMed1986

Transplantation of human osteosarcoma into nude mouse--correlation between experiment results and prognosis of patients.

We have made experiments on transplantation of human osteosarcoma into nude mice, and investigated the correlation between experiment results and prognosis of donor patients. Tumor take was observed in 36 of 60 cases (60%) in the initial transplantation, 23 cases (38.3%) in the second passage and 16 cases in the serial transfer of three passages or more. Clinical prognosis was classified into three categories and analyzed. As to the correlation between positive or negative tumor take in the 2nd passage and presence or absence of metastasis, there was a significant relationship was found between tumor take and metastasis. Then, in mice with serially transplantable tumor, the correlation between experiment results and postmetastatic prognosis was investigated. In cases with low tumor growth index, persistence of zone formation and low alkaline phosphatase level, postmetastatic prognosis was good with statistical significance. Consequently, these experiments are highly useful for prediction of clinical prognosis.

Adolescent↗
PubMed1986

[Complications following total knee replacement].

Complications of total knee replacement were studied by following up 218 cases operated in our clinic. The average follow-up time ranged from 24 months to 101 months (mean 44.3 months). The three most serious types of complication were: significant loosening in 8 knees; deep infection in 5 knees; and fracture in 7 knees. Patellar dislocation and extension mechanism rupture were found in 13 knees, restriction of ROM and instability in 20 knees, and other complications in 7 knees. The incidence of complications in the rheumatic group tended to be greater than that in the osteoarthritic group. The incidence of complications was significantly higher in the severely deteriorated group than in the not severely deteriorated group; and the incidence of complications in the group treated in combination with Anametric, Total Condylar and GUEPAR prosthesis was also significantly higher than in the group treated with the Kinematic Knee Prosthesis. Though 32 reoperations were performed in 23 knees, functional prognosis was not good in most cases.

Adult↗
PubMed1986

Steroid-induced osteonecrosis of the femoral condyle--a clinical study of eighteen knees in ten patients.

Clinical feature of rarely occurring steroid-induced osteonecrosis of the femoral condyle was analyzed in 10 patients. Patients' ages at onset ranged from 19 years to 43 years. The patients consisted of 2 cases affected unilaterally and 8 cases affected bilaterally. In two knees lesion developed in the medial condyle, but it involved the lateral condyle of 11 knees or both the medial and lateral condyles of 5 knees. Mean period from the start of steroid therapy to manifestation of lesion was 79 months and mean total dose was 29.0 g. Subjectively, knee pain was not so severe and ADL was not so limited in most cases. Radiographically, lesions which were located solely in anterior area or posterior condyle belonged to the initial or moderate stage. However, the majority of those lesions which were located mainly in the central area was medium or large in size belonged to the advanced stages.

Adult↗
PubMed1986

Subluxation of the patella. Investigation by computerized tomography.

Subluxation of the patella may produce pain and instability in young people. However its classification, diagnosis and treatment are controversial. We have used computerized tomography (CT) to measure the amount of lateral shift of the patella and the angle of tilt to the femur in patients with subluxation. The mean lateral shift was 31.4% and the angle of tilt 31.8 degrees. These values are significantly greater than those obtained from conventional axial radiographs or in arthrographic axial views. We have obtained interesting evidence that the rate of lateral shift apparently increased on voluntary contraction of the quadriceps muscle (Q-contracted). With the quadriceps contracted, the mean rate of the lateral shift in the affected knees showed a significant increase (+27.7%) compared to that in normal knees (+14.0%). We have reviewed 40 knees treated by operative realignment with a mean follow-up of 27 months. The mean rates of lateral shift measured from CT-image in the knees before operation improved significantly to the normal range at follow-up, both with the quadriceps relaxed and contracted. The results evaluated by Insall's criteria were "excellent" in 13 knees; "good" in 22; "fair" in 3 and "poor" in 2. The satisfactory group (those with excellent and good results) revealed an improvement in lateral shift when the quadriceps was contracted, while the unsatisfactory group (fair and poor results) did not.

Adolescent↗
PubMed1986

Tibial torsion in patients with medial-type osteoarthritic knee.

Computed tomography measurements of tibial torsion were evaluated in 85 patients with medial-type osteoarthritic knees and in 24 normal adults. Although there were no differences in the degrees of femoral torsion or knee joint rotation, external tibial torsion was observed to have a mean value of 11.3 degrees, significantly smaller than the 23.5 degrees observed in the normal adults (p less than 0.01). The more advanced the osteoarthritic stage, the greater was the reduction in external tibial torsion. Reduction of external torsion of the tibia was most severe at the proximal tibial metaphysis.

Adult↗
PubMed1985

[The dynamic property of glucagon secretion in response to blood glucose--analysis with the aid of the control theory using an artificial endocrine pancreas].

The precise dynamic property of glucagon secretion in response to glucose concentration has not yet been elucidated, since in in vitro studies using pancreatic islets, the co-existence of pancreatic B cells modifies the mode of glucagon secretion, and in vivo studies, the exogenous insulin administration greatly affects pancreatic A cell function. In this study, to clarify the dynamic property of glucagon secretion in response to glucose concentration and the ability of glucagon to raise hepatic glucose production, an artificial endocrine pancreas was employed as a research tool. Our originally developed artificial endocrine pancreas prepared the glucagon and/or glucose infusion algorithm as the counterregulatory system. The principle of glucagon and glucose infusion algorithm is set as the proportional plus derivative modes of action to blood glucose concentration with time delay constant, as follows; Gn.I.R.(t) = Gp[BGp - BG(t - tau)] + Gd[-delta BG(t - tau)] + Gc G.I.R.(t) = Cp[BGp - BG(t - tau)] + Cd[-delta BG(t - tau)] where Gn.I.R.(t) and G.I.R.(t) are glucagon infusion rate and glucose infusion rate, respectively. BGp is the projected value of blood glucose concentration, and BG(t) and delta BG are blood glucose concentrations and the rate of change in blood glucose concentration at time t respectively. Gp and Gd are coefficients for glucagon infusion, and Cp and Cd are those for glucose infusion. Gc is the constant for basal glucagon supplementation. tau(min) is the time delay constant for glucagon and glucose infusion. In a depancreatized dog, the blood glucose concentration was maintained at the normoglycemic level with intraportal insulin infusion using this artificial endocrine pancreas for at least one hour, then hypoglycemia was induced by iv bolus insulin injection (0.1 U/kg). Glucagon was infused intraportally or glucose was infused into the peripheral vein when the counterregulatory system was operated according to each of these algorithm by variously changing the parameters. In the intraportal glucagon infusion algorithm, with the optimal parameters based on proportional plus derivative modes of action with a 10-min time delay (Gp/Gd/Gc/tau = 0.2/0.4/0.6/10), both the blood glucose response curves and plasma glucagon profiles simulated those seen in normal dogs. On the other hand, glucagon infusion based only on the proportional action failed to simulate the blood glucose response and plasma glucagon profile of normal dogs. When glucose was infused on the basis of the proportional action with a 20-min time delay (Cp/Cd/tau - 0.2/0/20), the insulin-induced hypoglycemia in depancreatized dogs could be restored to normoglycemia in the sa

Animals↗
PubMed1985

Endogenous ADP ribosylation of high mobility group proteins 1 and 2 and histone H1 following DNA damage in intact cells.

Endogenous ADP ribosylation of nonhistone high-mobility group (HMG) proteins and histone H1 was studied in cultured mouse mammary tumor cells following treatment with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). MNNG treatment of cells caused a rapid and transient increase in ADP ribosylation of histone H1 and HMG 1 and 2, whereas (ADP-ribose)n on HMG 14 and 17 was not affected. 3-Aminobenzamide, an inhibitor of (ADP-ribose)n synthetase, prevented the increase in ADP ribosylation of histone H1 and HMG 1 and 2. This inhibitor enhanced the cell-killing effect of MNNG, but had no significant effect on the removal of methylated purines. The preferential increase in ADP ribosylation of HMG 1 and 2 and histone H1 may be necessary for cell recovery from DNA damage.

Adenosine Diphosphate Ribose↗