Search PubMed⌕ Search

Biomedical subjects

M Yamane

Publications and source records attributed to M Yamane.

At least 163 records · Page 9Linked to original sources
PubMed1982

Microdetermination of 1-Methylheptyl gamma-bromoacetoacetate in human blood.

One of the authors reported previously on the presence of 1-methylheptyl gamma-bromoacetoacetate (MHBAA) in human cerebrospinal fluid. In this work, a microdetermination of MHBAA in human blood plasma was developed. The sulfhydryl group of 5-(dimethylamino)-1-naphthalene-sulfonyl L-cysteine (DANSYL L-cysteine) reacted with Br at the gamma-position of MHBAA to form a thioether bond, and a fluorescent derivative was obtained. The fluorescent derivative was separated by TLC. Quantitative determination of MHBAA was done by the radiodilution method combined with fluorometry. It was shown that MHBAA exists in human blood plasma at a concentration of several hundred pmol per ml.

Acetoacetates↗
PubMed1982

Fractography of cast gypsum.

A fractographical study of dental cast gypsum was made in order to correlate the mechanical properties with the microstructure. Wet specimens fractured under tensile stress showed intercrystalline fracture and the tensile strength depended on the porosity present. Thus, it was assumed that tensile strength was dependent on the contact area between individual gypsum crystals and changes in porosity approximated to changes in contact area. Strength differences among specimens of a given W/P ratio, therefore, can be related to differences in intercrystalline contact areas. These theoretical considerations suggest that the classification of dental die stone and dental stone into high and low strength types based on strength properties only would be more practical and less confusing than at present.

Calcium Sulfate↗
PubMed1982

[Thermal behavior of phosphate-bonded investment. Part 1. Thermal behavior of MgNH4PO4.6H2O (author's transl)].

Thermal behavior of MgNH4PO4.6H2O was investigated by means of TG-DTA and X-ray diffraction. Two endothermic peaks (90 degrees C and 230 degrees C) and a exothermic peak (660 degrees C) were observed in a micro-DTA curve. Weight loss occurred at two stages corresponding to the two endothermic peaks. Values of weight loss were about 38% and 53%, respectively, at the end of each stage. These values were nearly equal to theoretical weight losses in the formation of Mg2P2O7 from MgNH4PO4.6H2O via MgNH4PO4.H2O. The intermediate, MgNH4PO4.H2O was identified by X-ray diffraction. The second weight loss continued till about 600 degrees C. The product during the second stage was amorphous and Mg2P2O7 began to crystallize above about 600 degrees C. The exothermic peak was thought to correspond to the crystallization. On the other hand, the first endothermic peak separated into two peaks in a macro-DTA curve. The first corresponded to removal of crystal water from MgNH4PO4.6H2O and the second to evaporation of the condensed water. Moreover the exothermic peak also separated into two peaks and the peak temperatures lowered. It was considered that the crystallization was affected by the atmosphere.

Dental Casting Investment↗
PubMed1982

[Thermal behavior of phosphate-bonded investment. Part 2. Reactions in the systems of MgO-MgNH4PO4.6H2O and MgO-NH4H2PO4 (author's transl)].

Reaction process in the equimolar mixtures of MgO-MgNH4PO4.6H2O and MgO-NH4H2PO4 were investigated by TG-DTA and X-ray diffraction. In the MgO-MgNH4PO4.6H2O system, MgNH4PO4.6H2O was changed by heating in the following way. The formation of MgNH4PO4.H2O by dehydration about 100 degrees C and of amorphous Mg2P2O7 by dehydration and removal of NH3 above 200 degrees C and the crystallization of Mg2P2O7 above 600 degrees C. A part of the amorphous Mg2P2O7 reacted with MgO to form Mg3(PO4)2 above 600 degrees C. The crystallized Mg2P2O7 also reacted with MgO to form Mg3(PO4)2 at higher temperature. In the MgO-NH4H2PO4 system, MgNH4PO4.H2O was formed by the reaction between them, which was corresponded to an exothermic peak about 140 degrees C in the DTA curve. MgNH4PO4.H2O, an unknown phase Y and an amorphous phase were formed at 200 degrees C. The crystalline phases almost disappeared and another unknown phase X appeared at 300 degrees C. The phase X also disappeared and Mg(PO3)2 appeared at 400 degrees C. In the TG-DTA curve for this system, an exothermic peak, which was corresponded to crystallization of Mg(PO3)2, was observed about 550 degrees C and the decomposition of NH4H2PO4 ceased after the crystallization. Mg(PO3)2 reacted with MgO to form Mg2P2O7 at higher temperature.

Dental Casting Investment↗
PubMed1981

Pontine reticular unit responses to pelvic nerve and colonic mechanical stimulation in the dog.

The role of pontine reticula units (PRU) responding to afferent impulses from the distal colon and anal mucosa was studied in dogs. The 465 PRU were classified into 4 groups on the basis of the pattern of discharge in response to afferent stimulation (AS) of rectal branches (RB) of the pelvic nerve: Group I (G-I) responded with a short burst (latency, 36 +/- 16 msec); G-II responded with an early short burst (latency, 41 +/- 21 msec), followed by a late long-lasting train of spikes (latency, 187 +/- 110 msec); and G-III responded with a long-lasting train of spikes (latency, 189 +/- 130 msec). G-IV had spontaneous discharges which were temporally inhibited by AS. G-II and G-III PRU showed remarkable facilitation similar to that of the long latency reflex discharges of RB. G-I PRU showed habituation. Most of G-II and G-III PRU discharged simultaneously with the reflex discharges of RB; these cause the contractions of defecation in the distal colon. In each group, 6.4 +/- 14.8% of PRU were reticulospinal units with descending axons running beyond the 1st lumbar segment of the spinal cord. It was concluded that the pontine defecation reflex center plays an essential role in defecating activity.

Afferent Pathways↗
PubMed1981

Decomposition of gypsum bonded investments.

Decomposition of gypsum bonded investments was investigated by means of TG-DTA and X-ray diffraction. The decomposition began at about 900 degrees C and led to the formation of CaSiO3 as a major product and Ca2SiO4 as a minor one. CaO was not formed during the decomposition of any of the investments. The decomposition process followed Jander's equation, [1-(1-alpha)1/3]2 = kt, and the Ca2+ ion diffusion in CaSiO3 was concluded to be a rate-determining step.

Calcium Sulfate↗
PubMed1980

Age-hardening of dental Ag-Pd-Cu-Au alloys.

Age-hardening mechanisms of dental Ag-Pd-Cu-Au alloys were investigated by means of electron microscopic observations. Hardening was due to the precipitation of the L10 type CuPd-ordered platelet in the grain interior and to the discontinuous precipitation at the grain boundary. The characteristics of age-hardening curves were determined by rates of continuous and discontinuous precipitation.

Copper↗
PubMed1979

Influence of surgery for ischemic heart disease on early postoperative left ventricular function.

The pre- and postoperative systolic time intervals, hemodynamics and serum catecholamines were studied in 30 patients with successful myocardial revascularization surgery or left ventricular aneurysmectomy and the influence of the surgery on the left ventricular function was evaluated. 1. Significant depression of left ventricular performance was recognized in the group of patients with left ventricular aneurysm as compared to the patients with angina pectoris with or without previous myocardial infarction before the operation. 2. At 2 hours after the operation, signigicant decrease of ET/PEP, cardiac index and stroke work index and marked elevation of systemic vascular resistance were seen in the group of patients with aortocoronary bypass surgery who had previous myocardial infarction and with left ventricular aneurysmectomy as compared to the group of patients without previous myocardial infarction. 3. At 2 hours after the operation, ET/PEP seemed to reflect the left ventricular stroke work and the depression of the left ventricular function was mainly affected by the elevation of systemic vascular resistance due to the hypersecrection of serum catecholamines. 4. Reduction of systemic vascular resistance by vasodilator brought an improvement of EG/PEP, cardiac index and stroke work index.

Cardiac Output↗
PubMed1979

[A study of the ageing process in dental Ag-Pd-Cu-Au alloys by anisothermal annealing method (author's transl)].

The ageing processes in dental Ag-Pd-Cu-Au alloy were investigated by means of electrical resistivity measurements during anisothermal annealing. The main results obtained are as follows; (1) There are two obvious precipitation processes (stage I and stage II) during anisothermal annealing after quenching from above critical temperature. And the apparent difference in stage I attribute to solution treatment temperature. (2) Stage I occured at lower temperature, is one ageing process by the migration and annihilation of quenched-in excess vacancies. Another is stage II at higher temperature by the diffusion of equilibrium vacancies.

Copper↗