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Biomedical subjects

M Sekikawa

Publications and source records attributed to M Sekikawa.

At least 19 recordsLinked to original sources
PubMed2006

Sensory innervation of temporomandibular joint disk.

PURPOSE: To investigate the nerve endings of the adult temporomandibular joint disk, in particular the presence and configuration of the sensory nerve endings by silver staining and electron microscopy. METHODS: 20 cadaveric temporomandibular joints impregnated with silver stain were studied using an optical microscope; 2 other joints were studied using a transmission electron microscope. RESULTS: Free nerve endings were found in the disk parenchyma of all joints. Golgi-Mazzoni corpuscles, Ruffini corpuscles, and articular corpuscles were also observed as sensory nerve end organs. Myelinated and nonmyelinated nerve fibres were visualised in the disk parenchyma using the transmission electron microscope. CONCLUSION: Free nerve endings and sensory nerve end organs are present in the disk parenchyma of the human temporomandibular joint and are associated with sensation and proprioception, just as they are in the acetabular labrum, glenoid labrum, triangular fibrocartilage complex, and meniscus.

Adult↗
PubMed2001

Effects of diets enriched in n-6 or n-3 fatty acids on cholesterol metabolism in older rats chronically fed a cholesterol-enriched diet.

Hypocholesterolemic effects in older animals after long-term feeding are unknown. Therefore, aged rats (24 wk of age) fed a conventional diet were shifted to diets containing 10% perilla oil [PEO; oleic acid + linoleic acid + alpha-linolenic acid; n-6/n-3, 0.3; polyunsaturated fatty acid/saturated fatty acid (P/S), 9.6], borage oil [oleic acid + linoleic acid + alpha-linolenic acid; n-6/n-3, 15.1; P/S, 5.3], evening primrose oil (EPO; linoleic acid + gamma-linolenic acid; P/S, 10.5), mixed oil (MIO; oleic acid + linoleic acid + gamma-linolenic acid + alpha-linolenic acid; n-6/n-3, 1.7; P/S, 6.7), or palm oil (PLO; palmitic acid + oleic acid + linoleic acid; n-6/n-3, 25.3; P/S, 0.2) with 0.5% cholesterol for 15 wk in this experiment. There were no significant differences in the food intake and body weight gain among the groups. The liver weight in the PEO (n-6/n-3, 0.3) group was significantly higher than those of other groups in aged rats. The serum total cholesterol and very low density lipoprotein (VLDL) + intermediate density lipoprotein (IDL) + low density lipoprotein (LDL)-cholesterol concentrations of the PLO (25.3) group were consistently higher than those in the other groups. The serum high density lipoprotein cholesterol concentrations of the PEO (0.3) and EPO groups were significantly lower than in the other groups at the end of the 15-wk feeding period. The liver cholesterol concentration of the PLO (25.3) group was significantly higher than those of other groups. There were no significant differences in the hepatic LDL receptor mRNA level among the groups. Hepatic apolipoprotein (apo) B mRNA levels were not affected by the experimental conditions. The fecal neutral steroid excretion of the PLO (25.3) group tended to be low compared to the other groups. The results of this study demonstrate that both n-6 fatty acid and n-3 fatty acids such as gamma-linolenic acid and alpha-linolenic acid inhibit the increase of serum total cholesterol and VLDL + IDL + LDL-cholesterol concentrations of aged rats in the presence of excess cholesterol in the diet compared with dietary saturated fatty acid.

Aging↗
PubMed2001

Investigation of gene expressions related to cholesterol metabolism in rats fed diets enriched in n-6 or n-3 fatty acid with a cholesterol after long-term feeding using quantitative-competitive RT-PCR analysis.

We have developed a method to quantitate hepatic apolipoprotein (apo) B, LDL receptor, 3-hydroxy-3-methylglutary coenzyme A reductase (HMG-CoA reductase) and cholesterol 7alpha-hydroxylase mRNA expression in rats fed a cholesterol-enriched diet after long-term feeding using competitive RT-RCR. Rats (8 wk of age) fed a conventional diet were shifted to diets containing 10% perilla oil (PEO, oleic acid+linoleic acid+alpha-linolenic acid), borage oil (BRO, oleic acid+linoleic acid+gamma-linolenic acid), evening primrose oil (EPO, linoleic acid+gamma-linolenic acid), mixed oil (MIO, oleic acid+linoleic acid+gamma-linolenic acid+alpha-linolenic acid), or palm oil (PLO, palmitic acid+oleic acid+linoleic acid) with 0.5% cholesterol for 15 wk. There were no significant differences in the food intake and body weight gain among the groups. The liver weight in the PEO and PLO groups was significantly higher than other groups. The serum total cholesterol and very low density lipoprotein (VLDL)+intermediate density lipoprotein (IDL)+low density lipoprotein (LDL)-cholesterol concentrations were consistently higher in PLO group than in the other groups. The serum high density lipoprotein cholesterol concentration was significantly lower in the PEO group than in the other groups. The liver cholesterol concentration group was significantly higher in the PEO than in the other groups. There were no significant differences in the hepatic LDL receptor mRNA level among the groups. Hepatic apo B, HMG-CoA reductase and cholesterol 7alpha-hydroxylase mRNA levels were not affected by the experimental conditions. However, hepatic cholesterol 7alpha-hydroxylase mRNA level in the PEO and MIO groups tended to be higher than in the other groups. The fecal cholesterol extraction was significantly higher in the MIO and PLO groups than in the PEO and EPO groups and the total bile acid extraction was significantly higher in the PEO and MIO groups than in the PLO group. The results of this study demonstrated that both n-6 fatty acid and n-3 fatty acids such as gamma-linolenic acid and alpha-linolenic acid lowered serum total cholesterol and VLDL+IDL+LDL-cholesterol concentrations of rats in the presence of excess cholesterol in the diet compared with dietary saturated fatty acid.

Animals↗
PubMed1999

Comparative hypocholesterolemic effects of five animal oils in cholesterol-fed rats.

The hypocholesterolemic efficacy of various animal oils was compared in rats given a cholesterol-enriched diet. After acclimatization for one week, male F344 DuCrj rats (8 weeks of age) that had been fed with a conventional diet were assigned to diets containing 5% of oil from emu (Dromaius), Japanese Sika deer (Cervus nippon yesoensis, Heude), sardine, beef tallow, or lard with 0.5% cholesterol for 6 weeks. After this feeding period, the concentrations of serum total cholesterol and of very-low-density lipoprotein + intermediate-density lipoprotein + low-density lipoprotein-cholesterol in the sardine oil group were significantly lower than those in the other groups. The serum high-density lipoprotein-cholesterol concentration in the Japanese Sika deer oil group was significantly higher than that in the other groups. The atherosclerotic index and liver cholesterol concentration in the sardine oil and Japanese Sika deer oil groups were significantly lower than those in the other groups. The fecal cholesterol excretion by the Japanese Sika deer oil group was significantly higher than that of the other groups, except for the sardine oil group, and the fecal bile acid excretion by the sardine oil group was significantly higher than that of the other groups, except for the lard group. These results suggest that Japanese Sika deer oil reduced the atherosclerotic index and liver cholesterol concentration in the presence of excess cholesterol in the diet as well as sardine oil did by increasing the excretion of cholesterol from the intestines of rats.

Animals↗
PubMed1990

A quantitative investigation of irregular cuspules in human maxillary permanent molars.

The frequency of occurrence of anomalous cusps or tubercles on human upper first molars was investigated in seven racial populations using moiré contourography, which permits the three-dimensional measurement of minute cusps. Tubercles on the mesial marginal ridge were more frequently found in Mongoloid populations (Japanese and Eskimo) than in others. The frequency of the protoconule was high in Eskimos and Negroids (Bantu and San). The lingual paracone tubercle (mesial cusp) showed a particularly high frequency in Australian aborigines. The metaconule was rare or absent in all of the populations. Caucasoid groups (Dutch White and Asiatic Indian) showed generally low frequencies of all these abnormal tubercles, especially the distal accessory cusp (C5). Racial differences in the frequencies of occurrence may offer a key to understanding the adaptive significance of these traits and human microevolution. Confusion in nomenclature for upper molar tubercles is also discussed.

Asian People↗
PubMed1990

Retrovirus-mediated gene transfer into mouse cerebellar primary culture and its application to the neural transplantation.

To develop a procedure for the transplantation of genetically modified brain primary cells, we transplanted cultured mouse cerebellar cells infected with recombinant retroviruses into the cerebella of adult mice and examined the expression of introduced gene-products in the host cerebellum after transplantation. After infection of cultured cerebellar cells with recombinant retroviruses harboring chloramphenicol acetyltransferase (CAT) gene, we selected only virus-infected cells for transplantation by culturing the cells in medium containing G418 for 3 weeks. CAT was continuously expressed in the cultured cerebellar cells during the 3-week incubation, but by immunoblotting analysis with antiglial fibrillar acidic protein (GFAP) or antineurofilament protein (NFP) antiserum the population of cultured cerebellar cells was found to change during the incubation. Immunocytochemical analyses using anti-CAT antiserum demonstrated that the transplanted cell mass containing CAT-positive cells was detectable in the cerebellum up to 3 weeks, but not 3 months after the transplantation of G418-selected cells into the cerebella of 7-week-old mice.

Animals↗
PubMed1990

X-ray crystallography of incisor enamel from red kangaroo.

X-ray powder diffraction of red kangaroo (Macropus rufus) dental enamel, with a relative density greater than 2.60, showed a longer a-axis length of the apatite unit cell, a = 9.462 A, a shorter c-axis length, c = 6.877 A, and a smaller crystallite size, ca. 185 A, than those of human dental enamel. The a-axis of red kangaroo dental enamel was one of the longest among the values reported previously, whereas the c-axis was one of the shortest. The crystallite size was almost equal to that of dentin crystallites. It is suggested that the chemical composition of the dental enamel apatite of the red kangaroo is markedly substituted, resulting in lattice distortion.

Animals↗
PubMed1990

Variability of palatal dimensions in South Australian twins.

Estimates of genetic contributions to variability in three palatal dimensions were obtained from a sample of 70 pairs of South Australian twins aged between 11 and 26 years. Palatal width and length were measured directly from dental models, while palatal height was assessed indirectly from moiré contourographs. For each of the three palatal variables there was evidence of significant genetic variance, with heritability estimates for palatal width and height generally exceeding those for palatal length. Furthermore, palatal height measurements displayed greatest relative variability and strongest correlation between monozygous twins (r = 0.95), suggesting that this dimension could be useful as an additional comparative feature in forensic odontological investigations.

Adolescent↗
PubMed1989

Quantitative investigation on irregular cusps in lower permanent molars.

The frequency of occurrence of anomalous cusps or tubercles on human lower first molars was investigated in three racial populations: Japanese, Australian Aboriginals and Dutch white. The technique used was moiŕe contourography, which permits the three-dimensional measurement of minute cusps. Four tubercles investigated were 6th cusp, 7th cusp, deflecting wrinkle and transverse ridge. The frequencies of four traits were all highest in Australian Aboriginals among three, especially those of 6th cusp and deflecting wrinkle were significantly higher than other two populations. Japanese and Dutch showed comparatively low frequencies of four traits, but the 6th cusp in the former occurred significantly higher than that in the latter. There was no significant differences of the frequency in all the traits between sexes. It was suggested that high frequency of these traits in Australian Aboriginals demonstrates the primitive morphology of the lower molar of this population.

Asian People↗
PubMed1989

[Three-dimensional measurement of the maxillary first molar in Australian whites].

The occlusal surfaces of upper first molars of Australian Whites were measured in three dimensions with the aid of moiré contourography. The dental casts had been collected from Australian White twins who were considered to be of European stock and the casts housed in the Department of Dentistry, The University of Adelaide, South Australia. In the present study, our first aim was to describe the three-dimensional features of occlusal surfaces of molars in Australian whites. One cast was selected from each monozygotic twin pair at random. A total of 24 males and 15 females were photographed. The results obtained in the present study were compared with those of other human populations previously reported. Cusp height of Australian Whites showed intermediate mean values among 8 populations, but mean intercuspal distances were smaller. This feature, such as small size of occlusal surface but relatively high cusps, also found in Dutch and Asiatic Indian. Mean cusp heights in this population of showed similar values between sexes. Mean differences were insignificant as in Asiatic Indian, Australian Aboriginals, and Bantu unlike the Mongoloid, Japanese and Eskimo populations, where there were significant sex differences in cusp heights. This sexual dimorphism in cusp height among human populations is discussed phylogenetically and functionally.

Australia↗
PubMed1989

[Metrical study on teeth and mandible in Macaca fuscata fuscata. 2. Principal component analysis].

Metrical investigation on teeth and mandible together was performed to understand the morphological relationship between these two components in Macaca fuscata fuscata. Measurements are 9 items from the mandible, 2 items from dental arch, and 8 mesiodistal diameters from teeth. Correlation matrix composed of 19 items, in total, was examined in males and females, respectively. Significant correlation coefficients were frequently seen among mandibular measurements and also among tooth measurements, but rarely seen between mandibular and tooth measurements. The only exception was a mesiodistal diameter of P3 which has a few significant correlations with mandibular measurements. Principal component analysis was also carried out based on the correlation matrix of 19 measurements. The first component was a size factor in which factor loadings were all positive. The second component was thought to be a factor of the mandibular size in which factor loadings were highly positive on the mandibular measurements and contrarily low on the dental measurements. It is concluded that there is no obvious correlation between general sizes of the mandible and the teeth in Macaca fuscata fuscata.

Animals↗
PubMed1988

A novel enhancement of SV40 enhancer activity by treatment of mouse neuroblastoma N18TG2 with protein kinase inhibitor H-7.

To determine the role of protein phosphorylation in transcription regulation, we have treated mouse neuroblastoma N18TG2 cells with the protein kinase inhibitor H-7 and tested its effect on transcription. After the preculture and transfection in the presence of H-7, the cell preparation was divided in half and cultured with and without H-7. The level of CAT expression of pSV2-CAT was found to be higher in the cells cultured in the absence of H-7 than in those cultured in the presence of H-7. This difference was observed only after pretreatment of the cells with H-7, suggesting that withdrawal of H-7 from the culture medium after preculture with H-7 gave an enhancing effect on CAT expression. This phenomenon was also observed with transformants that expressed the CAT gene of pSV2-CAT stably. The 72 base-pair (bp) repeat of SV40 DNA was responsible for this difference in CAT expression. A similar effect of H-7 on the SV40 enhancer activity was observed in mouse neuroblastoma x rat glioma hybrid NG108-15 cells, but not in rat glioma C6-BU-1 cells.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1988

Comparative study of the upper molar occlusal table morphology among seven human populations.

Three-dimensional morphology of the occlusal table of the upper first molars was compared in seven racial populations. Materials were moiré contourograms collected by ourselves over 5 years. Intercuspal distances and cuspal heights were comparatively studied in this analysis. When the populations were arranged in the order of these sizes, their arrangements based on intercuspal distances and cuspal heights were quite different from each other. When intercuspal distances were scaled by protocone-paracone distance, the distances connecting distal cusps were significantly smaller in Mongoloids (Japanese and Eskimo) than in Caucasoids (Dutch and Asiatic Indian), which suggests a reduction tendency of distal cusps in Mongoloids. This tendency was intermediate in Negroids and Australoid. Principal coordinate analysis was carried out on the basis of a similarity matrix including both intercuspal distances and cuspal heights. The result suggested that the three-dimensional shape of the occlusal table was distinguishable in four representative racial populations.

Adolescent↗
PubMed1988

Principal component analysis of intercusp distances on the lower first molars of three human populations.

The distances between the five main cusps of lower first molars were measured on moiré photographs of casts obtained from Japanese, Dutch and Australian Aboriginal children. Principal component analysis of the intercusp distances, log transformed and standardized so that average tooth size was held constant, revealed three sources of shape variation in cusp topography. All populations were similar for scores on component 1 which was concerned with variations in the position of the hypoconulid. The Dutch had lowest scores on component 2 indicating small buccolingual distances compared with mesiodistal, whereas the Australian Aboriginals had the lowest mean score on component 3, expressing the distances between metaconid, entoconid and hypoconulid.

Asian People↗
PubMed1988

Cusp height relationships between the upper and lower molars in Japanese subjects.

Relationships of cusp height between the upper and lower first molars and between the deciduous second molars in Japanese subjects were analyzed with the aid of moiré contourography. In permanent molars, the height of the hypoconid had a mean value similar to that of the upper trigonal cusps, indicating that upper and lower functional cusps of the same height occlude with each other. In deciduous second molars, however, hypoconid heights were significantly smaller than trigonal cusp heights. Such differences in cusp height between permanent and deciduous dentition may be related to the function and phylogeny of tooth or jaw movements.

Child↗