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Biomedical subjects

T Tanimura

Publications and source records attributed to T Tanimura.

At least 55 records · Page 3Linked to original sources
PubMed1992

The effect of mixed live vaccines of Newcastle disease and infectious bronchitis on the chicken respiratory tract.

The effect of mixed live vaccines of Newcastle disease (ND) and infectious bronchitis (IB) on specific pathogen-free chickens aged 7 days was investigated. The chickens were inoculated intranasally with mixed live vaccines with and without Escherichia coli, or with E. coli alone. "Vaccine 1" consisted of ND virus strain B1 and IB virus strain ON; "vaccine 2" consisted of ND virus strain B1 and IB virus strain H120. The tracheas of chickens inoculated with the vaccines and E. coli and with the vaccines alone showed multiplication of E. coli and histological lesions (loss of cilia, degeneration and hyperplasia in epithelial cells and cellular infiltration of subepithelial tissues). In the tracheas of chickens inoculated with vaccines and E. coli, multiplication of E. coli was greater than in chickens given vaccine alone. There were no histological lesions, and only mild, transient multiplication of E. coli in chickens inoculated with E. coli alone. The results suggest that these mixed live vaccines, especially vaccine 2, play a role in inducing or enhancing colibacillosis in the chicken.

Animals↗
PubMed1992

Regulation of Drosophila neural development by a putative secreted protein.

The Drosophila strawberry (sty) locus was isolated by P-element insertion mutagenesis in a screen for mutations affecting eye development. Analysis of the mutant phenotype and the putative expression pattern of the sty gene suggested that it has multiple functions. Mutations in the sty gene lead to irregular spacing of ommatidia, an increase in the number of photoreceptor cells, as well as abnormal axonal projections to the lamina and disrupted structure of the optic lobes in the adult fly. The sty mutation also causes abnormal head involution, a change in a number of sensilla in the antennomaxillary complex in the embryonic stage and abnormal morphogenesis of the maxillary palp and wings in later stages. We examined the presumptive expression of the sty gene during development by histochemical staining for lacZ expression from enhancer trap elements inserted within the sty gene. During embryogenesis, expression of lacZ showed a segmental pattern in the ectoderm and in the nervous system. In the eye imaginal discs, lacZ was expressed in photoreceptor cells beginning a few rows posterior to the morphogenetic furrow. The lacZ was also expressed in the wing disc. In the adult, lacZ was expressed in the retina and lamina. We cloned the sty gene by P-element tagging and found that it encodes a putative secreted protein containing a cysteine-rich region similar to the epidermal growth factor (EGF) repeat. On the basis of the loss of functional phenotype, the expression pattern and the predicted structure of its product, we propose that sty encodes a diffusible protein acting as a signal involved in lateral inhibition within the developing nervous system and also as a factor involved either directly or indirectly in axonal guidance and optic lobe development.

Animals↗
PubMed1992

Mutants with delayed cell death of the ptilinal head muscles in Drosophila.

The emergence of adult Drosophila melanogaster from the puparium is followed by the programmed degeneration of a number of muscle groups. We have isolated two X-linked mutants that delay the programmed death of at least some of these muscles. During eclosion, the fly makes use of a membranous sac, the ptilinum, which is later retracted into the head capsule. Six of the eight sets of muscles involved in the retraction then undergo degeneration. The muscle fibers initially show a gradual atrophy and then degenerate rapidly through fragmentation followed by absorption. In wild-type flies, this degeneration is obvious by 12 h after eclosion due to the loss of the birefringence of the muscles. Through mutagenesis with ethyl methanesulfonate, we isolated four mutants whose birefringence of the doomed muscles was retained even at 12 h. Mutants were genetically classified into two complementation groups; mcd-1 and mcd-2 (mcd: muscle cell death). The muscles of the mcd-1 mutants degenerate more slowly than that of the wild-type flies; the fibers enter the fragmentation step but are then not rapidly absorbed. In the mcd-2 mutants, the fibers atrophy more slowly than that in the wild-type flies and fail to undergo fragmentation. The difference in the process of the muscle death between the mcd-1 and the mcd-2 mutants suggests that at least two genes act on different steps in the process of muscle cell death.

Animals↗
PubMed1991

Studies of variant palatal rugae in normal and corticosteroid-treated mouse embryos.

Fourteen- and 15-day mouse embryos treated with triamcinolone on day 11 of gestation were examined for the presence of variant rugae. Nontreated mouse embryos served as controls. Variant rugae found were classified into five types. All five types of variations (bifurcation, division, supernumerary, shortness and cross) were observed in triamcinolone-treated embryos, and shortness was most frequently seen. Supernumerary, bifurcation and division were ranked next, following by cross. Variant, rugae, except the cross, were also observed in non-treated embryos in low frequencies, but more than one-half of them were the bifurcation of the second ruga. Divided rugae ranked next, and supernumerary and shortness were found occasionally. Except for the bifurcated and supernumerary rugae, the greater part of the variant rugae were found in the fifth and fourth ruga in the triamcinolone-treated groups and in the fifth ruga in the nontreated groups. As the incidence of variant rugae in the triamcinolone-treated embryos was significantly higher than that in the nontreated, it was regarded as one of the changes induced by the corticoid. Based on the characteristic features of the rugal region, it is speculated that the formation of variant rugae is associated with the disturbance of normal epithelial-mesenchymal interaction which may be controlled by the nerve fibers appearing at the time of rugal formation. The relationship between the increased appearance of variant rugae and the failure of palatal shelf elevation was examined, but no direct evidence was obtained.

Abnormalities, Drug-Induced↗
PubMed1990

Discontinuity of primary and secondary neural tube in spina bifida induced by retinoic acid in mice.

This report shows by light microscopy the appearance of secondary neurulation separated from primary neurulation and its developmental fate in the spinal cord of mice exposed to retinoic acid in utero. The embryos and fetuses were derived from pregnant mice (ICR strain) given 60, 40, or 0 mg/kg of retinoic acid in olive oil on day 8 of gestation orally and killed 1, 2, or 10 days later. Separation of the primary neural fold from the secondary neural tube was seen in 9- and 10-day-old embryos: the caudal part of the neuroepithelium of the primary neural fold was disarranged with non-closed posterior neuropore, and underneath it the secondary neural tissue extended caudally with abnormal notochord. At term, fetuses showed spina bifida, including myeloschisis, myelocele, and diplomyelia (diastematomyelia) with abnormal distribution of ganglionic cells. These cord lesions were located between the third lumbar and second coccygeal levels. The former two cord anomalies were associated with diplomyelia and split the dorsal and ventral portions of the spinal cord with an overlapping zone between the third lumbar and third sacral levels. These findings suggest that the separation from primary neurulation is due to the lesions in both primary neural folds and notochord induced by retinoic acid and that the spinal cord caudal to the third lumbar level originates from both neuroectoderm and mesenchyme-like cells while that caudal to the third sacral level originates from mesenchyme-like cells only.

Abnormalities, Drug-Induced↗
PubMed1989

Simultaneous determination of biogenic amines, their precursors and metabolites in a single brain of the cricket using high-performance liquid chromatography with amperometric detection.

An analytical procedure has been developed for the simultaneous determination of biogenic amines, their precursors and metabolites by high-performance liquid chromatography with amperometric electrochemical detection. Following careful adjustment of various factors involved in the separation efficiency, reversed-phase chromatography with an ion-pairing technique gave simultaneous separation of nineteen biogenic amines and related substances. Peak identification was confirmed by comparison with hydrodynamic voltammograms. The method was sensitive enough to detect each substance in the picomole range. The procedure was applied to quantitate the amount of biogenic amines in a single brain of the cricket.

Animals↗
PubMed1989

Aberrant differentiation of neuroepithelial cells in developing mouse brains subsequent to retinoic acid exposure in utero.

All-trans-retinoic acid induced 2 types of disorganized neuroepithelium, localized and continuous, in the exencephaly of 9-day-old mouse embryos exposed to 60 or 40 mg/kg for 27 to 30 hr in utero. The localized effect appeared as a protuberance in the wall of the telencephalon and thick neural folds in the mesencephalon with the discontinuity of the apical terminal sheet. The continuous disorganization was seen from the olfactory placode to the myelencephalon with rosettes of cells and many dense bodies in the neuroepithelium. Ultrastructurally, cells in the localized disorganizations showed swelling of Golgi complexes, coated vesicles, and rough endoplasmic reticulum resulting in degeneration. The continuous disorganizations consisted of undifferentiated homogeneous cells in which the nuclei exhibited expansion of nucleolar granular portions and coagulated heterochromatin, and cytoplasm showed monosomal dispersion. In both types of disorganized neuroepithelium, junctional complexes were seen focally at the apical side or apical processes of the rosette, with few or no microfilament bundles. A layer of microfilaments at the base of the neuroepithelial cells in controls, just above the basal lamina, was not present in the monosome dispersed cytoplasm. In the neuroepithelium of controls, one phagosome was seen in the perinuclear region in 0.8% of the cells examined, whereas in the experimental neuroepithelium 2 or more phagosomes were seen in a cell, and phagocytosis occurred by pseudopods. These findings suggest that all-trans-retinoic acid induces not only cytotoxicity but also dedifferentiation in the neuroepithelial cells leading to more cell death, which activates the phagocytosis. These lesions in the neuroepithelium may be a cause of exencephaly.

Abnormalities, Drug-Induced↗
PubMed1989

Suppression of erythroid cell differentiation in mouse embryos exposed to retinoic acid in utero.

Differentiation of circulating erythrocytes was inhibited by all-trans-retinoic acid in 8- and 9-day-old mouse embryos exposed in utero on day 8 of gestation. Histochemical, light, and electron microscopic examinations revealed that all-trans-retinoic acid first decreased the numbers of polychromatic erythroblasts and then increased them. Simultaneously, immature erythroblasts proliferated, and differentiation of mature primitive erythrocytes was suppressed. Electron microscopy of these immature erythroblasts revealed monosomes rather than the usual polyribosomes in the cytoplasm. RNA histochemistry revealed a greater number of intermediate differentiating erythroblasts with pyronin-positive cytoplasm than those in the controls and revealed also a dose-dependent relationship between the number of polychromatic erythroblasts with positive pyronin staining and the controls. These findings suggest that all-trans-retinoic acid destroys the messenger RNA system, resulting in an inability to produce hemoglobin.

Animals↗
PubMed1989

Morphogenesis of the secondary palate in mouse embryos with special reference to the development of rugae.

Morphological studies of secondary palate formation, with special reference to the development of rugae, were carried out on Jcl:ICR mouse embryos. Three rugae were observed on the anterior part of the future oral surface of the vertically developing palatal shelves in 13-day embryos. Rugae increased in number as the development of the palatal shelves proceeded, and five to six prominent rugae were observed in 14-day embryos just prior to shelf elevation. The folding of these five to six rugae progressed in conjunction with the formation of a sharp, valley-like groove at the base of the anterior two-fifths of the vertical palatal shelves. As palatal shelves elevated, the groove disappeared gradually, and, accordingly, the folding of rugae loosened. In the groove region, the superficial epithelial cells were roundish, while the basal ones were elongated. Such characteristic features were no longer observed when the disappearance of the groove was completed. Eight rugae were observed on the future hard palate of 14-day embryos with already completed palatal fusion. An additional ruga was frequently found in 15-day embryos, and the pattern then was almost the same as that of an adult. Epithelial thickening and condensation at the rugae region, as well as mesenchymal condensation under the epithelium of the rugae, were confirmed in embryos both before and after elevation of the palatal shelves. There is a possibility that these structural characteristics observed in the epithelial and mesenchymal cells of the rugae and groove regions may be related to palatal shelf elevation.

Animals↗
PubMed1989

Alterations in migrating cranial neural crest cells in embryos of mice fed retinoic acid.

Alterations in migrating neural crest cells induced by all-trans retinoic acid (RA) were studied morphologically and immunohistochemically in the cranial portion of 8-day-old mouse embryos which were derived from dams given 60, 40 or 0 mg kg of RA and killed 2 to 8 h later. Additionally, the embryos exposed to 4 mg/kg of actinomycin D (AD) on day 8 of gestation for 5 h were examined similarly. Light microscopy revealed that RA was cytotoxic and caused the appearance of pleomorphic nuclei, extra-large nucleoli and cytoplasmic budding which replaced lamellipodia and spike-like projections. Electron microscopy revealed pleomorphic nuclei containing nucleoli with major granular portions frequently surrounded with heterochromatin, monosomes, and phagosomes. A monosomal distribution pattern was different from that seen in the neural crest cells exposed to AD. The latter showed incomplete polyribosomal dispersion with fewer nucleolar components. Fewer neural crest cells with choline acetyltransferase-like immunoreactivity were detected in RA- and AD-exposed embryos than in the controls. These findings suggest that excess RA inhibits acetylcholine synthesis of the migrating neural crest cells, in a manner different from AD, and that it enhances phagocytosis. These phenomena modify the characteristics of neural crest cells resulting in craniofacial malformations.

Animals↗
PubMed1988

Distribution of biogenic amines in the cricket central nervous system.

The distribution of biogenic amines, their precursors, and metabolites in the central nervous system (CNS) of the cricket was determined using HPLC with electrochemical detection. Three biogenic amines, octopamine (OA), dopamine (DA), and 5-hydroxytryptamine (5-HT); two precursors, tyramine and tryptophan; and two metabolites, synephrine and 5-hydroxyindole-3-acetic acid, were detected in all ganglia. In the brain, 5-HT occurred in the largest quantities followed by OA, while in other ganglia OA occurred in the largest quantities followed by 5-HT and DA. In all ganglia, the amount of OA was two to nine times greater than that of DA. The results are discussed in comparison with different insect species.

Animals↗
PubMed1988

Immunohistochemical localization by monoclonal antibodies of S-100 alpha and beta proteins in mixed tumours and adenomas of the skin.

A study using monoclonal antibodies was made to evaluate the immunohistochemical localization of S-100 protein subunits alpha and beta in a total of 41 mixed tumours and adenomas of sweat gland origin. Normal eccrine glands showed positive staining for S-100 alpha in the secretory portion and in epithelial cells located in the transitional area from the coiled duct to the intraepidermal duct, as well as granular deposition of S-100 beta at the luminal surface of the secretory coil and duct. The myoepithelial cells were negative for S-100 alpha and beta. In mixed tumours, the tumour cells were round or oval in shape and displayed markedly positive staining for S-100 alpha and slightly positive or negative staining for S-100 beta. S-100 alpha staining in clear cell tumours was typically more intense than in any other sweat gland tumour. It is possible that clear cell tumours may arise from the transitional area of sweat glands. Spindle cell tumours displayed on abundance of S-100 alpha subunits but little S-100 beta. Occasional spindle cells located in the outer layer of tubular structures within tumours gave positive S-100 alpha staining. This result was different from that seen in pleomorphic salivary adenomas. Cells having undergone chondroidal changes revealed a positive S-100 reaction.

Adenoma↗
PubMed1988

Long-term effects on male reproductive organs of prenatal exposure to ethinyl estradiol.

The effects of oral contraceptives on human offspring have not been established. This study shows the long-term effects of prenatal exposure to ethinyl estradiol, a common estrogenic component of oral contraceptives, on the testes and epididymides of aged mice. Five (83%) of the six aged male mice examined showed atrophy of seminiferous tubules, four (67%) had Leydig's cell hyperplasia, and one (17%) had precancerous changes in the epididymis. These phenomena may be results of decreases in testosterone content and its drastic conversion into estradiol-17 beta in the fetal testes at critical periods induced by ethinyl estradiol.

Aging↗
PubMed1988

Dependency on light and vitamin A derivatives of the biogenesis of 3-hydroxyretinal and visual pigment in the compound eyes of Drosophila melanogaster.

When the fruitfly, Drosophila melanogaster, was reared on media deficient in carotenoids and retinoids, the level of 3-hydroxyretinal (the chromophore of fly rhodopsin) in the retina decreased to less than 1% compared with normal flies. The level of 3-hydroxyretinal increased markedly in flies that were given a diet supplemented with retinoids or carotenoids. The retinas of flies fed on all-trans retinoids and maintained in the dark predominantly contained the all-trans form of 3-hydroxyretinal, and showed no increase in the level of either the 11-cis isomer or the visual pigment. Subsequent illumination of the flies converted substantial amounts of all-trans 3-hydroxyretinal to its 11-cis isomer. The action spectrum of the conversion by illumination showed the optimum wavelength to be approximately 420 nm, which is significantly greater than the absorption maximum of free, all-trans 3-hydroxyretinal. Flies that were fed on carotenoids showed a rapid increase of the levels of 11-cis 3-hydroxyretinal and of visual pigment in the absence of light.

Animals↗