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Biomedical subjects

Y Yuasa

Publications and source records attributed to Y Yuasa.

124 records · Page 7Linked to original sources
PubMed1977

Diminished vascular reactivity to a cold stress in azotemic patients.

The integrity of the neurovascular reflex arc to a cold stimulus was evaluated by the determination of the response of the limb blood flow in fifteen azotemic patients. Seven of these patients became hypotensive during the course of renal failure despite comparable hemodialysis therapy. They showed a constant low blood pressure (mean blood pressure below 90 mmHg). The reactivity index (defined as the relative change at the 15th second of stimulus) was 15.9 +/- 14.4% for these hypotensive patients, and 35.7 +/- 12.0% for the remaining eight normotensive ones, while that of healthy subjects was 48.7 +/- 8.7%. The greatly diminished reactivity of the hypotensive patients could not be explained by humoral or hormonal factors. The dysfunction of somatic nerves of the vascular geometry could not be responsible for the difference. A dysfunction of adrenergic control of blood pressure was, therefore, strongly suggested.

Adult↗
PubMed1976

Mouse strain resistant to N-, B-, and NB-tropic murine leukemia viruses.

Mouse strain G was studied for its susceptibility to various strains of murine leukemia and sarcoma viruses. Both N- and NB-tropic Friend leukemia viruses neither induced splenomegaly nor grew efficiently in strain G mice. Using the XC test, cultured embryo cells were found to be resistant, but not absolutely, to all the tested viruses, N-tropic AKR virus, N- and NB-tropic Friend leukemia viruses, NB-tropic Rauscher leukemia virus, B-tropic WN1802B virus, NB-tropic Moloney leukemia and sarcoma viruses, and N-tropic Kirsten sarcoma virus, although the resistance to Moloney leukemia and sarcoma viruses is sometimes not as strong as that for other viruses. Thus, the strain G mice are unique among mouse strains because they show resistance that is not related to the N-B tropism of murine leukemia viruses.

AKR murine leukemia virus↗
PubMed1975

Effect of protease inhibitors on focus formation by murine sarcoma virus.

The effect of six protease inhibitors, isolated from various species of actinomycetes, on focus formation by murine sarcoma virus was examined. Pepstatin was the only inhibitor. The treatment of cells with pepstatin at various times possibly retards the early stage of infection with murine sarcoma virus.

Animals↗
PubMed1975

Development of a 3T3-like line from an embryo culture of an inbred strain of Syrian golden hamster.

An embryo culture of an inbred strain of Syrian hamster developed into a permanent cell line under the "3T3" 3 X 10-5 cells/60-mm dish. The resulting cell line had properties very similar to those of the mouse 3T3 series and was named HAMS 3T3. The cell showed density-dependent inhibition of division with a saturation density of 1.0 to 1.2 x 10-6 cells/60-mm dish or 4.5 to 5.5 x 10-4 cells/sq cm. Addition of fresh medium containing 5 or 10% fetal calf serum to a confluent culture induced DNA synthesis in 18 hr with subsequent cell division. Cells were hyperdiploid with a mode of 45 chromosomes (80% of the cells). When cells at the 60th passage were injected into the skin or cheek pouch of an inbred hamster of the same strain as that from which they were derived, they produced a benign tumor that regressed after 3 weeks. Morphological transformation was obtained by infection with the Moloney strain of murine sarcoma virus.

Animals↗
PubMedDate not supplied

Ha-ras oncogenes are activated by somatic alterations in human urinary tract tumours.

DNA-mediated gene transfer (transfection) studies using NIH 3T3 cells as recipients have demonstrated the presence of transforming genes (oncogenes) in diverse human tumours. A large proportion of oncogenes so far detected by DNA transfection are related to the Ha-ras onc gene of Harvey (and BALB) murine sarcoma viruses (MSV), Ki-ras, the oncogene of Kirsten MSV, and a third member of the ras gene family, N-ras. Individual tumours of many different organs have been associated with the activation of members of the ras gene family. We now present the first systematic survey of human urinary tract tumours processed immediately after surgery, as well as normal tissues from the same patients, to detect the presence of such genes. We demonstrate activation of Ha-ras as an oncogene in around 10% of randomly selected urinary tract tumours as well as direct evidence that oncogene activation is the result of a somatic event which is selected for within the tumour cell population.

Cell Line↗
PubMedDate not supplied

Trial patterns for selection of major connectors.

A method for selecting the individually suitable form and location of major connectors for partially edentulous patients is described. Light-polymerized resin patterns are alternately placed in the patient's mouth, and the most suitable location and the form of the major connector are selected. This trial pattern method makes it possible to better address the problems posed by difficult removable partial denture patients.

Dental Clasps↗
PubMedDate not supplied

An investigation of preferable taper and thickness ratios for cast circumferential clasp arms using finite element analysis.

This study used a two-dimensional finite element method to investigate the preferred design for a cast circumferential clasp. Finite element models of the clasp arm with the constant flexibility were constructed, the stress was calculated, and the effects of taper and cross-sectional shape on stress were evaluated. The clasp arm with the taper of 0.8 showed less stress than those with other tapers, and the thinner and wider arms showed less stress than those with other cross-sectional dimensions. These results suggest that the use of the preformed clasp-pattern with a taper of 0.8 is preferable for reducing fatigue and/or permanent deformation of the clasp arm.

Chromium Alloys↗
PubMedDate not supplied

Finite element and Weibull analysis to estimate failure risk in resin-bonded retainers.

Three-dimensional finite element analysis and Weibull analysis were used to evaluate the effect of the thickness and the rigidity of the retainers on the risk of failure of an anterior resin-bonded prosthesis. Retainer thickness ranged from 0.4 to 1.4 mm. The physical properties of metals similar to Ni-Cr and type IV gold alloys were used. A concentrated load (100 N) was applied to the incisal edge of the finite element analysis modeled pontic, and the data of other loads (150 to 500 N in 50-N increments) were calculated from the data of 100 N. Subsequent Weibull analysis revealed that failure probability diminished when there was an increase in metal thickness at loads of 300 to 350 N, particularly for the retainer made of a type IV gold alloy. The reduction in failure probability caused by increasing the thickness of the metal was greater when type IV gold alloy was used than when Ni-Cr alloy was used. This investigation suggests that the longevity of resin-bonded retainers can be prolonged by thickening the retainers, rather than using more rigid metals.

Chromium Alloys↗