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Biomedical subjects

M Mogi

Publications and source records attributed to M Mogi.

At least 109 records · Page 6Linked to original sources
PubMed1989

[Evaluation of super-elasticity characteristics of orthodontic Ni-Ti alloy wire].

Mechanical properties of orthodontic Ni-Ti alloy wires, especially their super-elasticity characteristics, were investigated in order to use them effectively in the clinics. In this study, twenty commercial orthodontic Ni-Ti wires were tested and two parameters were devised for the load-deflection curve and introduced to evaluate the practical mechanical properties, one being the "super-elastic index: SEI" for super-elasticity, and the other being the "E-load" for the load in the super-elastic region. There was a "flat area" in the load-deflection curve of the super-elastic type of Ni-Ti alloy wires, whose SEI was above seventy and a continuous force could be used through the wide range of deflection. The load of the work-hardened type of Ni-Ti wires, SEI below thirty, was nearly proportional to the deflection. And the middle type showed intermediate properties of the two. The E-load values of the super-elastic type wires are thought to indicate the load level in the super-elastic region. The quantitative evaluation of the super-elasticity characteristics of the orthodontic Ni-Ti wires became possible by the introduction of these parameters.

Dental Alloys↗
PubMed1989

[Mechanical properties and phase transformation of super-elastic Ni-Ti alloy wires. Part 1: Relation between super-elasticity and phase transformation].

The relationship between mechanical properties and thermal behavior of super-elastic Ni-Ti alloy orthodontic wires was investigated in order to use them effectively in clinics. Three types of super-elastic Ni-Ti alloy orthodontic wires, SENTALLOY-BLUE(SB), YELLOW(SY) and RED(SR), were used. Two parameters were introduced from the load-deflection curves in three point bending test to evaluate their mechanical properties. One was the super-elastic index (SEI) for super-elasticity, and the other was the E-load for the load in the super-elastic region. Their thermal behavior in the course of the transformation analyzed with DSC, and compared with the mechanical properties. The specimens heat-treated at 500 degrees C for 30 min were also examined. The differences in mechanical properties of the super-elastic Ni-Ti alloy orthodontic wires used in this study were thought to be more affected by the height of the thermic peak and the form of the DSC curves than the transformation temperature. The higher the thermic peak, the higher tended to be the SEI and the lower E-load. To the contrary, the lower thermic peak, the higher was the E-load and the lower was the SEI, and the continuous force could not be achieved. The remaining work-hardened structure was thought to influence these differences.

Dental Alloys↗
PubMed1989

[Mechanical properties and phase transformation of super-elastic Ni-Ti alloy wires. Part 2: Changes of properties through heat treatment].

Three types of super-elastic Ni-Ti alloy orthodontic wires, SENTALLOY-BLUE (SB), YELLOW (SY) and RED (SR), on the change of properties were studied especially the reversible change of the load level, using three point bending test and DSC. The heat treatment at 440 degrees C caused the largest reduction in mechanical properties of SB and SY, and the 400 degrees C treatment did that of SR. The load level of SR was less changeable than those of SB and SY by the difference of heat treatment temperature. Mechanical properties of SY were almost reversible by the alternate heat treatment at 440 degrees C and 510 degrees C. Then the 440 degrees C-heat treatment increased the transformation temperature, and the 510 degrees C-heat treatment decreased them. The variation of the mechanical properties completely corresponded to the change in transformation temperature. The variation appears to result from some internal structure changes. Changes in mechanical properties are observed by heat treatment at 360, 400 and 480 degrees C, but the reversibilities were not so clear. The change of the properties of super-elastic wires are influenced by the kind of wire and the heat treatment condition. The reversible change in the mechanical properties seems to have many advantages over super-elastic Ni-Ti alloy orthodontic wires.

Dental Alloys↗
PubMed1989

Scale pattern variations of Aedes aegypti in Chiang Mai, northern Thailand.

Abdominal tergal scale pattern variations of Aedes aegypti were studied in Chiang Mai, northern Thailand for specimens reared from eggs laid in ovitraps set monthly both indoors and outdoors in urban and rural areas. The populations predominantly consisted of the dark type form, regardless of macrohabitats (urban vs. rural), microhabitats (indoor vs. outdoor) or seasons (dry vs. rainy). Among 6,003 specimens, no individuals had pale-scales continuing from the tergal base to its apex on the third tergum and posteriorly.

Aedes↗
PubMed1988

Inactivation of tyrosine hydroxylase in rat striatum by 1-methyl-4-phenylpyridinium ion (MPP+).

We report that 1-methyl-4-phenylpyridinium ion (MPP+), the active metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), inactivated tyrosine hydroxylase (TH) when MPP+ was directly infused into the striatum. We examined both in vitro TH activity and TH content measured by an enzyme immunoassay in the rat striatum after MPP+ was administered by an in vivo brain microdialysis probe. MPP+ caused the inhibition of TH activity but did not influence TH content in the ipsilateral striatum. These results indicate that MPP+ may cause an acute inactivation of TH after continuous exposure at the high concentrations.

1-Methyl-4-phenylpyridinium↗
PubMed1988

Homospecific activity (activity per enzyme protein) of tyrosine hydroxylase increases in parkinsonian brain.

Tyrosine hydroxylase (TH) contents in the caudate nucleus, putamen, and substantia nigra from control and parkinsonism brains were measured for the first time by a sandwich enzyme immunoassay. Both the TH protein content and TH activity (Vmax) were decreased in parallel in the parkinsonian brains as compared with those of the control brains. In contrast, TH "homospecific activity" (activity per enzyme protein) was significantly increased in the parkinsonian brains. The results indicate that the decrease of TH activity in parkinsonian brains is due to the decrease of TH protein content as a result of cell death. The increase in the "homospecific activity" of residual TH in parkinsonian brain suggests such molecular changes in TH molecules as result in a compensatory increase in TH activity.

Brain Chemistry↗
PubMed1988

Lung and cervical lymph-node metastasis after cortisone enhancement in hamster cheek-pouch carcinogenesis.

The administration of hydrocortisone after excision of DMBA-induced tumours in hamster cheek pouch produced cervical lymph-node metastases in 9 out of 13 animals (69 per cent), and resulted in lung metastasis in 1 animal. In the control group, which received no cortisone but had tumours cut from the pouch, 4 out of 9 animals had cervical lymph-node metastases (44 per cent).

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1988

The super-elastic Japanese NiTi alloy wire for use in orthodontics. Part III. Studies on the Japanese NiTi alloy coil springs.

Closed and open Japanese nickel titanium (NiTi) alloy coil springs were fabricated from the Japanese NiTi alloy wire. The closed coil springs were subjected to a tensile test and the open coil springs were subjected to a compression test to evaluate the mechanical properties. At the same time, a test with the commercially available steel coil springs also was done. It was clearly established that the Japanese NiTi alloy coil springs exhibited superior springback and super-elastic properties similar to the properties of the Japanese NiTi alloy arch wires. In addition, it was shown that the load value of super-elastic activity can be effectively controlled by changing the diameter of the wire, the size of lumen, the martensite transformation temperature, and the pitch of the open coil spring. The most important characteristic of the Japanese NiTi alloy coil springs is the ability to exert a very long range of constant light, continuous force. It is possible to use this coil selectively to obtain optimal tooth movement.

Dental Alloys↗
PubMed1988

Ovitrap surveys of dengue vector mosquitoes in Chiang Mai, northern Thailand: seasonal shifts in relative abundance of Aedes albopictus and Ae. aegypti.

Aedes aegypti (L.) and Aedes albopictus (Skuse) were surveyed using ovitraps in residential areas in Chiang Mai, northern Thailand. Egg populations (both species inclusive) remained low in the dry season, but increased/decreased exponentially during the first/latter half of the rainy season, respectively. This seasonal pattern was similar to the seasonal distribution of dengue haemorrhagic fever cases in the area. During the dry season (November-March) Ae.aegypti was dominant in urban and indoor ovitraps. With onset of the rainy season in April, relative abundance of Ae.albopictus increased in rural and outdoor ovitraps. Ae.albopictus displaced Ae.aegypti in the latter half of the rainy season in the rural area. Possible mechanisms to account for this seasonal decline of Ae.aegypti and reciprocal fluctuations in relative abundance of Ae.albopictus are discussed in relation to food availability for larvae in container habitats.

Aedes↗
PubMed1988

Effects of systemic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine to mice on tyrosine hydroxylase, L-3,4-dihydroxyphenylalanine decarboxylase, dopamine beta-hydroxylase, and monoamine oxidase activities in the striatum and hypothalamus.

The effects of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) (30 mg/kg subcutaneously per day for 8 days) to C57BL/6N mice were studied on tyrosine hydroxylase (TH), L-3,4-dihydroxyphenylalanine decarboxylase (DDC), and monoamine oxidase (MAO) activities in the striatum, and TH, DDC, dopamine-beta-hydroxylase (DBH), and MAO activities in the hypothalamus. Treatment with MPTP led to a large decrease in TH activity and a parallel decrease in DDC activity in the striatum, as compared with the saline controls. In contrast, MPTP administration did not cause a decrease of the activities of TH, DDC, and DBH in the hypothalamus. There was also no reduction in MAO activities of striatum and hypothalamus. These data indicate that MPTP administration to mice results in specific degeneration of the dopaminergic nigrostriatal pathway and that DDC in the mouse striatum may mainly be localized in the dopaminergic neurons with TH.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1987

Effects of repeated systemic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on striatal tyrosine hydroxylase activity in vitro and tyrosine hydroxylase content.

We examined both in vitro tyrosine hydroxylase (TH) activity and TH content determined by a new enzyme immunoassay in the mouse striatum after repeated systemic injection of MPTP. Repeated systemic administration of MPTP to mice (30 mg/kg per day, subcutaneously for 8 days) caused an approximately 65% decrease of both TH activity and TH content in the striatum. The intensity of immunohistochemical staining of TH protein in the striatum was also reduced in MPTP-treated mice. These results indicate that the reduction of TH activity in vitro after the repeated administration of MPTP is due to reduction of TH protein as a result of nerve degeneration.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1987

Determination of isofloxythepin in biological fluids by gas chromatography-mass spectrometry.

A method for the determination of isofloxythepin in biological fluids by gas chromatography-mass spectrometry is described. Isofloxythepin was readily converted into the trimethylsilyl ether by treatment with N,O-bis(trimethylsilyl)trifluoroacetamide. This derivative was separated on a 5% OV-101 column and determined, employing newly prepared isofloxythepin-d7 as an internal standard. Clean-up of isofloxythepin in blood and urine was efficiently achieved by back-extraction with hexane or hexane-toluene (9:1) under acidic and basic conditions, while isofloxythepin glucuronide in biological fluids was isolated by ion-exchange chromatography on Dowex 50W-X4 resin. The detection limit of isofloxythepin by this method was 50 pg. The blood and urine levels of isofloxythepin after oral administration of the drug to dogs were monitored by the proposed method.

Animals↗
PubMed1987

Regional lymph node metastasis created by partial excision of carcinomas induced in hamster cheek pouch with 9,10-dimethyl-1,2-benzanthracene.

The feasibility of using the hamster cheek pouch/dimethyl-benzanthracene (DMBA) system as an experimental model of lymphatic metastasis was investigated. Forty male Syrian golden hamsters treated with DMBA were divided into two equal groups--one with surgical excision of their tumors and a control group without tumor excision. In the excision group, the animals received three applications/week to the left cheek pouch of 0.3% DMBA in acetone for 14 weeks. Following a three-week observation period, the tumors in the pouch were excised at their base, and the animals were killed after four weeks of further observation. In the control group, the animals were treated for 14 weeks in a manner similar to that used for the excision group, left for seven weeks without treatment, and then killed. Cheek pouches with tumors and cervical lymph nodes were processed for histological examination. All of the animals, both with and without metastasis, had borne squamous cell carcinomas (SCC) in their treated cheek pouches. Histologically, seven out of 16 animals in the excision group showed metastatic deposits of SCC confined to the left cervical lymph nodes, while in the control group, metastasis was not found in any of the 19 animals with SCC in their cheek pouches. The results demonstrate that surgical excision of the hamster cheek pouch carcinoma is efficient in producing unequivocal lymph node metastasis.

9,10-Dimethyl-1,2-benzanthracene↗