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Biomedical subjects

K Takada

Publications and source records attributed to K Takada.

At least 811 records · Page 45Linked to original sources
PubMed1985

Experimental morphological studies on the functional role of the pulpal nerves in dentinogenesis.

The role of the pulpal nerves in the dentinogenesis of the rat dentition was studied experimentally by means of a time marker of lead acetate and by electron microscope after the individual dissection of the trigeminal and cervical sympathetic nerves or both. Following trigeminectomy, the longitudinal growth of the denervated incisor decreased. Contrary to this, following cervical sympathectomy, the longitudinal growth of the denervated incisor and molar increased 10-5%, and the collagen fibers increased predominantly in the pulpal tissue. The sympathetic nerves seem to play an important part in controlling the differentiation of the odontoblasts, inhibiting the maturation of the growth center of the apical pulp in the continuously developing teeth.

Animals↗
PubMed1985

High performance liquid chromatographic determination of cyclosporin A in body fluids.

A sensitive, specific and reproducible high performance liquid chromatographic assay method for the determination of a new immunosuppressant, cyclosporin A (CsA), in the biological samples such as human blood, rat plasma and rat lymph has been developed. CsA was extracted with diethyl ether followed by being cleaned up with liquid-liquid extraction procedure using carbon tetrachloride-methanol system, and was chromatographed on a microparticulate CN column with UV detection at 212 nm. The lower detection limit is 100 ng/ml in human blood (from 1.0 ml) and 500 ng/ml in the rat plasma or lymph (from 0.2 ml). This method is sensitive enough for monitoring CsA concentrations in the renal transplant patients in the therapeutic dose range, and is also applicable to the determination of CsA in the rat plasma and lymph samples for the purpose of pharmacokinetic evaluation of several CsA dosage forms in the rats.

Animals↗
PubMed1985

Structural and functional adaptation of the pulpal nerve fibers in the rat incisor.

Special fine structure of the pulpal nerve fibers adapted to the continuously growing incisor was studied on 20 rats (25-d-old-males) electron microscopically and was compared with that of the molars of limited growth. The incisal pulp was innervated by 2 kinds of the nerve fibers derived from the cervical sympathetic and the trigeminal ganglia: polyaxonal unmyelinated and monoaxonal myelinated. In the apical pulp, however, the pulpal nerve fibers were unmyelinated, showing 3 different profiles in the fine structure: 1. polyaxonal, 2. polyaxonal with dial plate-like profile and 3. monoaxonal. The monoaxonal unmyelinated fiber reflected the transverse profile of the unmyelinated part of the myelinated axon derived from the trigeminal ganglion. It can be concluded that the pulpal nerve fibers derived from the trigeminal ganglion maintain the immatured nature in the apical proliferating pulp to adapt to the continuous growth of the incisor.

Animals↗
PubMed1984

Large cell carcinoma of the lung associated with marked eosinophilia. A case report.

A case of large cell carcinoma of the lung which produced eosinophil colony stimulating factor and eosinophil chemotactic factor was reported. A 52-year-old Japanese man with a tumor in the left upper lobe of the lung underwent left pneumonectomy. Marked eosinophilia persisted especially after recurrence, with a maximum peripheral leukocyte count of 161,000/mm3, of which 78% consisted of eosinophils. The patient died of pulmonary insufficiency 18 months after surgery. At autopsy, metastatic tumor tissues and almost all organs were markedly infiltrated with eosinophils, especially the spleen, and there was marked proliferation of eosinophils in the bone marrow. Eosinophil colony stimulating factor production by the transplanted tumor in a nude mouse was confirmed by use of a human bone marrow culture assay system. Eosinophil chemotactic factor production by metastatic tumor tissue also was proved by a modified micro-filter technique.

Biological Assay↗
PubMed1984

Differentiation of cultured epidermal keratinocytes related to sterol metabolism and its retardation by chemical carcinogens.

The amount of 5 beta-cholest-7-en-3 beta-ol of mouse dorsal skin was increased after parturition until 10 days of age, reaching a maximum 5 beta-cholest-7-en-3 beta-ol/5-cholesten-3 beta-ol ratio of 0.43. [2-14C]Acetate was incorporated almost exclusively into 5-cholesten-3 beta-ol in the basal cell culture of epidermal keratinocytes. However, when the concentration of calcium was changed from 0.07 to 1.9 mM to induce terminal differentiation of keratinocytes, a definite amount of radioactive acetate was incorporated into 5 beta-cholest-7-en-3 beta-ol. The extent of the incorporation was increased at least until 72 h after changing medium, and the ratio of radioactive 5 beta-cholest-7-en-3 beta-ol/radioactive 5-cholesten-3 beta-ol was constantly increased in this period, indicating that the accumulation of 5 beta-cholest-7-en-3 beta-ol in the cell is concomitant with the differentiation of the cell. Pretreatment with chemical carcinogens such as 7,12-dimethylbenz[a]anthracene and 20-methylcholanthrene inhibited the incorporation of radioactive acetate into 5 beta-cholest-7-en-3 beta-ol in the high calcium medium at least for the initial 24 h. After that, the incorporation was gradually restored to the normal level. Pretreatment with a tumor promoter, such as 12-O-tetradecanoyl-phorbol 13-acetate, however, did not inhibit the incorporation. Thus, sterol metabolism is suggested to be a useful indicator for differentiation of epidermal keratinocytes.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1984

Induction of Epstein-Barr virus antigens by tumor promoters for epidermal and nonepidermal tissues.

Fifteen established tumor promoters belonging to different chemical groups were tested for their ability to induce Epstein-Barr virus (EBV)-specific early antigens (EA) in EBV-genome-positive nonproducer Raji cells. Saccharin (a promoter in urinary bladder carcinogenesis), DDT (a promoter in liver carcinogenesis), anthralin and iodoacetic acid (promoters in skin carcinogenesis) gave a significant induction with a maximum of induced cells of 20% (8 mg/ml), 0.8% (20 micrograms/ml), 0.8% (100 ng/ml) and 0.7% (0.4 micrograms/ml), respectively. In addition, after combined application with a noninducing dose (0.2 ng/ml) of 12-O-tetradecanoyl-phorbol-13-acetate (TPA), seven additional tumor promoters induced 0.3-2.1% EA-positive cells two days after treatment. The results indicate that in addition to mouse skin tumor promoters such as diterpene esters, several compounds reported to possess tumor-promoting activity in other types of tissue induce EBV. The data suggest that EBV induction is an effect commonly exerted by this group of compounds which should be very useful in screening for environmental tumor promoters.

Animals↗
PubMed1984

Novel peptides with orally active and long-lasting antihypertensive activity.

A series of N-(P-substituted phosphinoyl)peptides were synthesized and their antihypertensive activities were tested in spontaneously hypertensive rats (SHR). Among them, N-(dibenzyloxyphosphinoyl)-L-Ala-L-Pro-L-Pro-OH showed the most potent and long-lasting antihypertensive activity in SHR when administered orally. Although the inhibitory activity of this peptide against the angiotensin-converting enzyme was about one-hundredth of that of Captopril, the antihypertensive activity in SHR was significantly higher and longer-lasting than that of Enalapril which has been reported to be the most potent agent among similar converting enzyme inhibitors.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1984

Cross-linking of cell surface immunoglobulins induces Epstein-Barr virus in Burkitt lymphoma lines.

Anti-human immunoglobulin (Ig) antibodies with single-chain specificities induced Epstein-Barr virus (EBV) in various Burkitt lymphoma lines when the corresponding Ig chain was expressed on the cell surface. The F(ab')2 fragments of IgG antibody were as potent as intact Ig, while the Fab and Fc fragments gave no induction, indicating that cross-linking of surface Ig was required for the induction. Simultaneously with EBV induction, anti-Ig inhibited the uptake of 3H-thymidine. This inhibition was also seen in EBV-genome-negative Burkitt lymphoma lines. In contrast, no effect on virus induction and cell growth was noted in lymphoblastoid lines of non-neoplastic origin. The possible relationship between cell differentiation and latency of EBV-carrier state is discussed.

Burkitt Lymphoma↗
PubMed1984

Associations between anterior temporal, masseter, and orbicularis oris muscle activity and craniofacial morphology in children.

In a sample of children with Class I (n = 18), Class II, Division 1 (n = 25) and Class II, Division 2 (n = 12) malocclusions, the relationship between jaw muscle activity and specific craniofacial variables has been quantified. Muscle data were obtained from the temporal, masseter, and orbicularis oris muscles at rest, in maximum intercuspation, and during clenching, jaw opening, and swallowing. Contrasts in means of the three skeletal groups identified differences in both the craniofacial and muscle variables. Orbicularis oris muscle amplitude was greater at rest and in maximum intercuspation in Class II, Division 2 subjects. Anterior temporal amplitude during clenching was significantly lower in Class II, Division 1 subjects. A principal component analysis reduced the data base, and three canonical correlations were identified at the 0.05 level of significance. Significant canonical correlations could not be found between the cephalometric data and clench, swallow, or jaw-opening tasks, which suggests no dependency between these factors. Two canonical correlations were found for the rest position data. A linear combination of masseter and orbicularis oris activity and incisor separation was correlated (r1 = 0.758) with a linear combination of mandibular unit length, upper and lower central incisor angulation, and SNOP. The second rest canonical correlation (r2 = 0.733) involved the anterior temporal muscle and a series of sixteen cephalometric variables. For the maximum intercuspation data, orbicularis oris amplitude was correlated with a linear combination of upper incisor angulation and SNOP variables (r1 = 0.727). The multivariate statistical analysis extracted a clinically significant association between orbicularis oris muscle activity and incisor position.

Cephalometry↗
PubMed1984

Canonical correlations between masticatory muscle orientation and dentoskeletal morphology in children.

In order to identify associations between the orientation of the superficial masseter and temporalis muscles and dentoskeletal morphology in a sample of fifty-five children with various malocclusions, eight muscle-orientation variables (relative to the occlusal plane) and twenty-three dentoskeletal variables were evaluated from lateral head films. The thirty-one measurements were reduced to six muscle-orientation and sixteen dentoskeletal variables by a principal component analysis. Three canonical correlations were identified between the muscle orientation and dentoskeletal variable groups at the 0.05 level of significance and canonical loadings were determined for each set of variables. The first canonical correlation (r1 = 0.931) represents a growth-related correlation factor between the masticatory muscle insertion positions relative to the occlusal plane and the dimensional and positional changes of craniofacial structures during growth. The second canonical correlation (r2 = 0.846) may account for an operational artifact in the geometric measurement process, and the third canonical correlation (r3 = 0.813) suggests an association between superficial masseter muscle orientation relative to the occlusal plane and mandibular form. This report confirms the usefulness of multivariate statistical methods to extract latent associations between muscle orientation and craniofacial morphology; the results obtained suggest a contribution from the geometric orientation of the masticatory muscles to the development and maintenance of the dentoskeletal system.

Adolescent↗
PubMed1984

Circannual changes in plasma aldosterone levels in Bufo japonicus formosus.

Plasma aldosterone levels of Bufo japonicus formosus captured in their natural environment were determined each month throughout 1 year by radioimmunoassay. Low values were recorded in winter and spring, and the maximum occurred in July or August. High summer levels of aldosterone and increases in live weight were correlated. This phenomenon could reflect the gluconeogenetic action of aldosterone. In females but not in males, relatively high levels of plasma aldosterone were also observed in autumn; the relatively high levels of estrogen during this season may stimulate interrenal activity. This could be important to provide additional energy for ovogenesis which occurs in the autumn. On the other hand, high levels of androgen in males may reduce interrenal activity. Aldosterone seems to play no direct role in emergence from water after aquatic breeding activity in spring, as plasma levels showed no significant change during this season.

Aldosterone↗
PubMed1984

Cortical dysplasia in congenital muscular dystrophy with central nervous system involvement (Fukuyama type).

We report five cases of congenital muscular dystrophy with central nervous system involvement of the Fukuyama type (FCMD) in which cerebral cortical dysplasia was not uniform even in the same brain. We have categorized the dysplasia into three major patterns, each with a predictable topography despite individual variations. Cerebellar micropolygyria was localized to the dorsal halves of each hemisphere. Aberrant fascicles of myelinated nerve fibers, closely associated with micropolygyria, were found in the subarachnoid space of the dorsal cerebellar surface in all but one case. We discuss the characteristics of the cortical dysplasia of FCMD, particularly in relation to that of Walker's lissencephaly, pathogenesis, and the relationship between lesions of the central nervous system and skeletal muscle.

Brain Diseases↗
PubMed1984

The immunosuppressive mode of action of mizoribine.

Mizoribine (MIZ) suppressed the mitogen response and mixed lymphocyte reaction (MLR) significantly at doses of 100 micrograms/ml and 10 micrograms/ml in a dose-response analysis. The 50% inhibition dose (ID50) was between 10 micrograms/ml and 1.0 microgram/ml, both in the mitogen response and MLR. In a kinetic study of the MLR, the degree of suppression with MIZ at a given dosage was essentially the same as the degree of suppression observed in the dose-response analysis when MIZ was added to MLR cultures from day 0 to day 4. In addition, MLR was more susceptible to the suppressive activity of MIZ at 100 micrograms/ml when MIZ was added near the peak of lymphocyte proliferation. This experiment also showed that MLR suppression induced by MIZ at 10 micrograms/ml was reversible and MLR activity had completely recovered 6-8 hr after its removal. MIZ had no inhibitory action on MLR-derived cytotoxic cells or the effector phase of cell mediated lymphocytotoxicity. These results clearly demonstrate that MIZ suppresses lymphoproliferation, but has no effect on the recognition phase or effector phase of cytotoxic lymphocytes.

Dose-Response Relationship, Immunologic↗
PubMed1984

Mode of inhibitory action of a bacteriocin produced by Streptococcus mutans C3603.

The basis for the lethal activity of a bacteriocin produced by Streptococcus mutans C3603 (serotype c) was studied. Bacteriocin C3603 was found to adsorb to cells of representative strains of the seven serotypes of S. mutans. S. mutans BHT (serotype b) was used to study the adsorption and the lethal properties of bacteriocin C3603. The adsorption of bacteriocin to cells of S. mutans BHT was inhibited by treatment of cells with protease and beta-glucosidase and by such ligands as poly-L-lysine, poly-L-arginine, L-aspartic acid, L-glutamic acid, glutathione, oxidized glutathione, poly-L-aspartic acid, and poly-L-glutamic acid. The adsorption to cells was also inhibited by oligosaccharides and glucosamine. Mixtures of anionic and cationic amino acids or polyamino acids did not greatly enhance or antagonize the inhibition of adsorption of bacteriocin C3603 to cells. Sodium hydroxide extracts of cell walls and cell wall-membranes contained carbohydrates and proteins; however, only proteins were found to bind to bacteriocin or to a bacteriocin affinity column. The sodium hydroxide extracts contained about 35 protein bands as determined by sodium dodecyl sulfate-polyacrylamide disc gel electrophoresis. Bacteriocin C3603 was found to immediately inhibit the synthesis of proteins, DNA, and RNA of cells and to slowly release DNA from cells of S. mutans BHT.

Adsorption↗