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Biomedical subjects

Y Kameda

Publications and source records attributed to Y Kameda.

At least 163 records · Page 9Linked to original sources
PubMed1986

Age associated increase of C cell follicles in guinea pig thyroid glands.

The effect of aging on the formation of C cell follicles was examined in the thyroid gland of guinea pigs at various ages ranging from 1 to 29 months. The C cell follicles were demonstrated with the immunoperoxidase methods by using anticalcitonin and antisomatostatin antisera and with PAS reaction. They were already detected in 1-month-old guinea pigs but in low number. Thyroid glands from 1- to 14-month-old animals contained only a small number of C cell follicles and did not reveal the age-related increase. In aged guinea pigs (20- to 29-month-old), a dramatic increase of C cell follicles was found, about 13 times as high as the number of other age groups. The C cell follicles through all age groups were present in large clusters of C cells. In the aged guinea pigs, nodular large aggregates of C cells regarded as C cell hyperplasia occurred and numerous C cell follicles were formed in the large cell aggregates. Thus, the conspicuous increase of C cell follicles in aged animals was associated with a proliferative abnormality of C cells. The C cells forming follicles showed moderate to weak immunoreactivity for calcitonin, whereas they showed very intense immunoreactivity for somatostatin. In addition, the colloidlike and flocculent materials stored in the follicular lumina, which were consistently PAS-positive, were weakly immunoreactive to somatostatin but nonreactive to calcitonin.

Aging↗
PubMed1986

Localization of immunoreactive keratins in cyst epithelium of chick ultimobranchial glands.

The cyst structures of chick ultimobranchial glands were studied by electron microscopy and immunocytochemistry to characterize the type of intermediate-sized filaments present in the cells lining cyst lumina. Electron microscopy showed that the majority of the lumen-bordering cells contained extensive meshworks of intermediate-sized (7-11 nm) filaments, many of which were arranged in bundles. Apical regions of C cells directly bordering on cyst lumina were also filled with thinner (5-6 nm) filaments. Immunoperoxidase staining showed that the majority of cyst epithelial cells were stained intensely with anti-keratin antiserum, but not with anti-neurofilament antiserum, which is a specific marker for neuronal differentiation. The cyst epithelium also showed moderate-to-weak immunoreactivity for actin. Subsequently, the differentiation and maturation of cyst structures related to intermediate filament expression were studied. In 18-day-old chick embryos, keratin immunoreactivity began to appear in the cell clusters destined to form cysts and in the primordial cysts with small cavities. At this time, fine networks of intermediate filaments were already detected in the cells lining the cystic cavities. At 1 day after hatching, the cysts became a consistent feature of ultimobranchial glands. Intermediate filaments associated in bundles were observed, and the intensity of immunostaining for keratins increased. Thereafter, with progressive enlargement of cysts, numbers of intermediate filaments and intensity of keratin immunoreactivity gradually increased with age. Thus, the data indicate that in cyst epithelium keratin filaments are highly organized and may confer the structural strength necessary for cells lining cyst lumina.

Animals↗
PubMed1986

An ultrastructural study of the cysts in chicken ultimobranchial glands, with special reference to C-cells.

The ultimobranchial glands of the chicken were examined by electron microscopy and immunocytochemistry using a calcitonin antiserum. Electron microscopy confirmed the presence of C-cells, containing numerous secretory granules storing calcitonin, in the luminal lining of cyst-like structures found in these glands. These cells were furnished with prominent microvillar projections at their luminal surface, and the cytoplasm of the apical region was filled with fibril material. Furthermore, the cells contained prominent junctional complexes and desmosomes at their apico-lateral surfaces. In these C-cells, secretory granules were concentrated near the lumen and some were attached to the apical cell membrane. The luminal content of the cysts had a colloid-like and flocculent appearance, and was frequently seen attached to the cytoplasmic projections or apical cell membrane of the C-cells. Since the cysts progressively increase in volume and number with age, it is suggested that they may partly play a role in the storage of excess or unneeded hormonal products.

Animals↗
PubMed1986

Synthesis and alpha-D-glucosidase inhibitory activity of N-substituted valiolamine derivatives as potential oral antidiabetic agents.

Various kinds of N-substituted valiolamine derivatives, including compounds 23a, 24a, and 34a, which are structurally analogous to the key pseudodisaccharides (25a and 26a) of naturally occurring oligosaccharide alpha-D-glucosidase inhibitors, have been synthesized and estimated by the measure of inhibitory activity against porcine sucrase and maltase. The N-substituted valiolamine derivatives evaluated in this study have been found to be more potent than the corresponding N-substituted valienamine derivatives as well as the parent valiolamine. It is noteworthy that even simple N-substituted valiolamine derivatives such as N-[2-hydroxy-1-(hydroxymethyl)ethyl]-, N-[(1R,2R)-2-hydroxycyclohexyl]-, and N-[(R)-(-)-beta-hydroxyphenethyl]valiolamine (6, 8a, and 9a) have the stronger alpha-D-glucosidase inhibitory activity against porcine intestinal maltase and sucrase than naturally occurring oligosaccharide alpha-D-glucosidase inhibitors.

Animals↗
PubMed1986

Purification and properties of glucoside 3-dehydrogenase from Flavobacterium saccharophilum.

A membrane-bound glucoside 3-dehydrogenase [EC 1.1.99.13], which oxidizes validoxylamine A to the 3-keto derivative, was solubilized from the membrane fraction of Flavobacterium saccharophilum by Triton X-100 and purified about 280-fold with an overall yield of 30% from the membrane fraction by column chromatography on DEAE- and CM-Sepharose CL-6B and gel filtration on Sephacryl S-300. The purified enzyme exhibited a single protein band on disc gel electrophoresis, and FAD was shown to be the prosthetic group. The enzyme had a molecular weight of 270,000 as determined by gel filtration on Sephacryl S-300 and consisted of 4 identical subunits each with a molecular weight of 66,000. The enzyme reacted with various artificial electron acceptors such as 2,6-dichlorophenolindophenol (DCIP), phenazine methosulfate, and ferricyanide. The optimum pH for DCIP reductase activity was 6.0. The enzyme was inhibited by Hg2+ and p-chloromercuribenzoate. D-Glucose and methyl-alpha- and beta-D-glucoside showed the highest susceptibility to the enzyme, and were converted to the corresponding 3-keto sugars.

Carbohydrate Dehydrogenases↗
PubMed1986

Chemical modification by diethylpyrocarbonate of an essential histidine residue in 3-ketovalidoxylamine A C-N lyase.

3-Ketovalidoxylamine A C-N lyase of Flavobacterium saccharophilum is a monomeric protein with a molecular weight of 36,000. Amino acid analysis revealed that the enzyme contains 5 histidine residues and no cysteine residue. The enzyme was inactivated by diethylpyrocarbonate (DEP) following pseudo-first order kinetics. Upon treatment of the inactivated enzyme with hydroxylamine, the enzyme activity was completely restored. The difference absorption spectrum of the modified versus native enzyme exhibited a prominent peak around 240 nm, but there was no absorbance change above 270 nm. The pH-dependence of inactivation suggested the involvement of an amino acid residue having a pKa of 6.8. These results indicate that the inactivation is due to the modification of histidine residues. Substrates of the lyase, p-nitrophenyl-3-ketovalidamine, p-nitrophenyl-alpha-D-3-ketoglucoside, and methyl-alpha-D-3-ketoglucoside, protected the enzyme against the inactivation, suggesting that the modification occurred at or near the active site. Although several histidine residues were modified by DEP, a plot of log (reciprocal of the half-time of inactivation) versus log (concentration of DEP) suggested that one histidine residue has an essential role in catalysis.

Amino Acids↗
PubMed1986

Intra-cholecystic ectopic liver.

A 56-year-old Japanese woman who had an ectopic liver attached to the inner surface of the gallbladder is reported. The ectopic nodule measuring 1.2 X 0.5 X 0.8 cm was found incidentally when her gallbladder was resected because of cholelithiasis. Ectopic liver tissue in reported cases war located on the serosal surface, or in the wall of the gallbladder. This report described, to our knowledge, the first case of an ectopic liver nodule attached to the mucosal surface of the gallbladder with a thin pedicle.

Choristoma↗
PubMed1985

Alterations of immunoreactive somatostatin in thyroid C cells after induced hypercalcemia, hypocalcemia, and antithyroid drug treatment.

In order to elucidate the functional significance of somatostatin in thyroid C cells, the alterations of immunoreactive somatostatin in the cells were investigated under various experimental conditions, i.e., hypercalcemia, hypocalcemia, and antithyroid drug treatment. Guinea pigs and rabbits, in which almost all C cells reveal the intense immunoreaction for somatostatin in addition to calcitonin, were used as experimental animals. After chronically induced hypercalcemia, somatostatin immunoreactivity conspicuously diminished coinciding with the decrease of calcitonin; somatostatin as well as calcitonin was responsive to induced hypercalcemia. After hypocalcemic tetany induced by injection of Escherichia coli L-asparaginase, C cells exhibited very intense immunoreactions for both calcitonin and somatostatin. After chronic treatment of ethylenethiourea, immunoreaction of somatostatin in C cells was the same as that of calcitonin. That is, when immunoreactivity for calcitonin remained unchanged, immunoreactivity for somatostatin was also intensive. However, when immunoreaction of calcitonin became very weak, the reaction of somatostatin was also weak. Thus, in all experimental conditions examined the alterations of immunoreactive somatostatin in C cells completely coincided with those of calcitonin. It seems likely that somatostatin in thyroid C cells exerts the synergistic effect on calcitonin action.

Animals↗
PubMed1985

Purification and properties of 3-ketovalidoxylamine A C-N lyase from Flavobacterium saccharophilum.

3-Ketovalidoxylamine A C-N lyase was purified about 900-fold from the cell-free extract of Flavobacterium saccharophilum by ammonium sulfate fractionation, column chromatography on CM cellulose and gel filtration on Sephacryl S-200. The purified enzyme was homogeneous as judged by sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis. The molecular weight of the enzyme was estimated to be 36,000 by gel filtration on Sephacryl S-200 and by SDS polyacrylamide gel electrophoresis, indicating that the enzyme is a monomer. The optimum pH was found at 9.0. The enzyme activity was inhibited by EDTA or ethyleneglycol bis(beta-aminoethylether)-N,N'-tetraacetic acid and the inhibition was reversed by Ca2+ ion. The enzyme was able to eliminate p-nitroaniline or p-nitrophenol from p-nitrophenyl-3-ketovalidamine (IV) or p-nitrophenyl-alpha-D-3-ketoglucoside (VI), but not from p-nitrophenyl-1-epi-3-ketovalidamine or p-nitrophenyl-beta-D-3-ketoglucoside. Apparent Km values for IV and VI were 0.24 mM and 0.5 mM, respectively.

Bacterial Proteins↗
PubMed1985

Increased level of immunoreactive neuron-specific enolase in thyroid C cells from dogs and guinea pigs after chronic hypercalcemia.

Immunocytochemical localization of neuron-specific enolase (NSE) in thyroid C cells was investigated in various mammalian species. In bovine thyroid glands most of the C cells were weakly immunoreactive to anti-NSE antiserum. In other mammalian species, including dogs, guinea pigs, rabbits, cats, pigs, rats, hamsters, mice, and monkeys, some C cells or only a few C cells were weakly immunoreactive to the antiserum. It seems that normal C cells contain NSE in small amounts only or are devoid of NSE. After chronically induced hypercalcemia, C cells revealed hypertrophic and hyperplastic features. Whereas immunoreactive calcitonin was markedly decreased, marked increase of immunoreactive NSE was observed in C cells of both dogs and guinea pigs; almost all C cells were filled with reaction product for NSE. After administration of ethylenethiourea for a period of 3-8 months, C cells revealed a marked decrease of secretory granules and appearance of vesicular inclusions of various sizes, which were immunoreactive to the calcitonin antiserum, indicating a disturbance of calcitonin synthesis. No immunoreactivity for NSE was observed in C cells from dogs and guinea pigs so treated. In rabbits showing hypocalcemic tetany, calcitonin immunoreactivity was very intense and NSE immunoreactivity was faint to negative in the C cells. Thus, the level of NSE in C cells was clearly connected with the functional activity of the cells.

Animals↗
PubMed1985

Dental survey in Nigeria. Part 2. Biting force of Nigerian.

The biting force of 855 Nigerian children and adults from the age of 3 to 60 was recorded in the Joint Dental Epidemiological Survey in Nigeria in 1981. The biting force of the Nigerian rural group (245 males and 178 females) was significantly greater than those of the Nigerian urban group (227 males and 203 females) and the Japanese males and females.

Adolescent↗
PubMed1984

Ontogeny of immunoreactive somatostatin in thyroid C cells from dogs and guniea pigs.

The development of immunoreactive somatostatin in thyroid C cells of dogs and guinea pigs from early fetuses to adults was investigated by the use of immunoperoxidase histochemistry and radioimmunoassay. The time of appearance and developmental patterns of immunoreactive somatostatin in the C cells were completely different in both species. In guinea pig thyroids, the somatostatin immunoreactivity appeared later than the calcitonin immunoreactivity and the number of somatostatin-positive cells was very small during fetal periods. The somatostatin immunoreactivity rapidly increased during neonatal periods. A large population of the somatostatin cells and a high concentration of somatostatin immunoreactivity were observed in mature animals. On the other hand, in dog fetuses somatostatin immunoreactivity appeared very early, at the same time as the calcitonin immunoreactivity. The largest population of somatostatin cells was found at the stage when the primordial follicles were vigorously formed throughout whole thyroid parenchyma. At this stage almost all of calcitonin-positive cells were also somatostatin-positive. The somatostatin cells progressively decreased as the development proceeded, in contrast to the calcitonin cells which increased with gestational age. In postnatal dogs only a few C cells revealed the immunoreaction for somatostatin, and the concentration of somatostatin was very low. These findings suggest that the function of somatostatin in dog thyroid C cells may be different from that in guinea pig C cells.

Animals↗
PubMed1984

Development of immunoreactive somatostatin in C-cell complexes in the thyroid gland of the dog.

In connection with our previous finding that an intense immunoreaction to somatostatin transiently appears in thyroid C cells of the dog during early fetal periods, the present study investigated C-cell complexes in thyroid glands from early fetuses to adults in an attempt to clarify whether the transient appearance of immunoreactivity to somatostatin is dependent on the degree of differentiation of C cells. C-cell complexes retain their fetal characteristics; even in the complexes of postnatal dogs, there are numerous undifferentiated cells, immature C cells and primitive follicular cells, which are not yet organized into follicles. Neither the degree of differentiation of C cells nor that of other constituent elements of the complexes affected the developmental pattern of somatostatin immunoreactivity in C cells. The C cells located in complexes displayed the same pattern of developmental changes in immunoreactivity to somatostatin as the cells in thyroid parenchyma. In the C-cell complexes of early fetal dogs a very intense immunoreactivity for somatostatin was observed; almost all calcitonin-positive cells were also somatostatin positive. The immunoreactivity to somatostatin progressively decreased with age. In the postnatal complexes the number of somatostatin-positive cells was very small compared with that of calcitonin-positive cells.

Animals↗