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Biomedical subjects

M Chiba

Publications and source records attributed to M Chiba.

At least 271 records · Page 15Linked to original sources
PubMed1990

Concentrations of essential elements after repeated administrations of tin and selenium.

To study effects of simultaneous administration of tin (Sn) and selenium (Se) on concentrations of several essential elements, mice were injected with either SnCl2 (ip) or Na2SeO3 (sc), alone or both compounds at a daily dose of 5 mumol/kg each for 12 consecutive days. Mice were sacrificed at 20 h after the last injection and concentrations of Sn, Se, Na, Ca, Zn, P, Fe, K, and Mg in the liver, kidney, spleen, pancreas, testis, seminal vesicle, lung, femoral muscle, and femoral bone were determined. In the control mice, Sn and Se concentrations were the highest in bone (0.69 micrograms Sn and 6.93 micrograms Se/g dry wt). Administered Sn was found to accumulate in all organs except the testis. Among the essential elements determined, Na was the most affected in terms of concentration in the organs and Mg was the least affected element in these organs. Among the organs tested, each elemental concentration in the pancreas was most affected. Simultaneous injections of Sn and Se appeared to keep the correlation coefficients between elements similar to those found in the control mice.

Animals↗
PubMed1990

In vitro measurement of regional differences in the mechanical properties of the periodontal ligament in the rat mandibular incisor.

Mechanical testing was performed in various regions of the ligament at a velocity of intrusive loading of 5 mm/min. The perimeters of the lingual cementum and socket wall and the sectional area of the ligament were measured radiographically. Load-deformation curves were transformed into stress-strain curves using the area and width of the lingual part of the ligament. The mechanical properties of the ligament differed markedly along the long axis of the incisor; mechanical measures from the load-deformation and stress-strain curves decreased gradually from the incisal towards the basal regions. It is suggested that these regional differences in mechanical properties were much more marked than those in teeth of limited growth or in other connective tissues, and that the nature of the collagen fibres, together with surrounding cells, ground substance and blood vessels, may be important in determining such differences.

Animals↗
PubMed1990

Drug-induced, photosensitive, erythema multiforme-like eruption: possible role for cell adhesion molecules in a flare induced by Rhus dermatitis.

Drug-induced, photosensitive erythema multiforme has not been reported, although drugs and sunlight are listed among precipitating factors in erythema multiforme. We describe a case of a drug-induced erythema multiforme-like eruption in a photodistribution that was reproduced by clinical challenge with the drug and sunlight. On contact with Rhus verniciflua, the Japanese lacquer tree, the patient had a flare of the eruption, which was limited to the areas previously exposed to sun. Immunohistochemical studies suggested that the keratinocytes in the skin that retain teh photoactivated substances may facilitate epidermal invasion of lymphocytes by persistent expression of intercellular adhesion molecule-1.

Adult↗
PubMed1990

Measurement of the force required to extract the mandibular first molar from its socket in the dissected jaw of growing young rats.

Age-related changes in the mechanical strength of the periodontal ligament have been examined by measuring the force required to extract the mandibular first molar from its socket at an extension rate of 5 mm/min in the dissected jaws of growing young rats from 3 to 32 weeks of age. Almost linear increase in the ultimate loads was found from 3 to 8 weeks of age. However the values from 8 to 32 weeks of age did not show any significant differences. Close correlations were found between the ultimate loads and the weights of animals, mandibles and extracted teeth and between the load and length of the tooth from 3 to 8 weeks of age. It is supposed that a mechanical equilibrium has been established within the periodontal ligament in association with various external and internal factors such as root elongation, alveolar bone growth, turnover and maturation of periodontal ligament and occlusal activity, at about 8 weeks of age in the rat mandibular first molar.

Aging↗
PubMed1990

Mechanical properties of the periodontal ligament in the incisor teeth of rats from 6 to 24 months of age.

Mechanical properties of the periodontal ligament of the incisor have been examined in sections of the mandibles of rats from 6 to 24 months of age. Mechanical measures estimated from the load-deformation and stress-strain curves did not show age-related changes, although the body and mandible weights increased gradually during the experimental period. It is suggested that qualitative and quantitative changes in the supporting tissues/unit area of the ligament are minor at a restricted region examined.

Aging↗
PubMed1990

Isolation, characterization, and localization of heparin-binding growth factors in the heart.

Acidic and basic fibroblast growth factors (aFGF and bFGF) are angiogenic polypeptide mitogens for cells of mesodermal and neuroectodermal origin. In this report we describe the purification from several normal human hearts (including a very fresh, nonischemic sample) of heparin-binding, acid-, heat- and trypsin-sensitive 14-18-kD peptides that crossreact with antisera against aFGF and bFGF. Further evidence includes (a) prevention of mitogenicity by protamine and by anti-bFGF, (b) displacement of 125I-bFGF from cell membranes, and (c) stimulation of capillary endothelial cell migration. Specific immunohistochemistry localized bFGF to endothelial cells and, surprisingly, to cardiac myocytes, with almost no immunoreactivity in smooth muscle cells. These peptides may function in cardiac embryogenesis, hypertrophy, atherogenesis, angiogenesis, and wound healing, and may also have endocrine, neurotropic, or vasomotor functions.

Aged↗
PubMed1990

Increased cardiovascular responses to norepinephrine in patients with hypertrophic cardiomyopathy.

Sympathetic nerve-adrenergic receptor systems have been implicated in the pathogenesis of hypertrophic cardiomyopathy (HCM). We studied plasma norepinephrine (NE) levels during exercise and cardiovascular responses to NE in 26 patients with nonobstructive HCM and 26 age- and sex-matched controls. There were no differences in the plasma NE levels at rest (201 +/- 84 vs 233 +/- 100 pg/ml) or in the slope of the log NE-heart rate relationship during exercise between the HCM patient and control groups. When NE was infused intravenously, with increasing doses to 0.20 microgram/kg/min, HCM patients displayed significantly greater increases in mean blood pressure (29 +/- 7 vs 14 +/- 5%, p less than 0.001) and peripheral vascular resistance (39 +/- 7 vs 26 +/- 7%, p less than 0.001) than controls. Although the fractional shortening decreased during NE infusion in controls, it was unaffected in HCM patients, despite a greater elevation of systolic pressure. The responses of left ventricular contractility, estimated by a ratio of systolic blood pressure to end-systolic dimension, were significantly greater in patients with HCM (31 +/- 7 vs 13 +/- 6%, p less than 0.001). These observations indicate that vasoconstrictive responses of the peripheral arteries and inotropic responses of the left ventricular muscle to NE were augmented in patients with HCM, while sympathetic nervous activity remained unchanged. Accordingly, we propose that increased activity of the cardiovascular adrenergic receptor systems, rather than enhanced sympathetic nervous function, may be related to the development of abnormal hypertrophy in HCM.

Adult↗
PubMed1990

HLA antigens on colorectal adenoma and cancer cells.

HLA-DR and -ABC antigens on adenoma and cancer cells of the colon and rectum were investigated. Fifteen specimens of adenomas from 15 patients with sporadic colorectal adenoma, seven specimens of adenomas from seven patients with familial polyposis coli (FPC), and 10 specimens of cancers from 10 patients with colorectal cancer were obtained. Normal colonic mucosa far from the lesions, taken from 15 patients with sporadic adenoma or cancer, served as normal control mucosa. HLA antigens were identified using an immunoperoxidase staining method. Epithelia of all normal control mucosa (n = 15) expressed HLA-ABC antigens, but not HLA-DR antigens. HLA-DR antigens were expressed on 47% (7/15) of sporadic adenomas, 71% (5/7) of adenomas in FPC, and 100% (10/10) of cancers. The extent of HLA-DR expression on adenoma and cancer cells became broader with more severe dysplasia in adenoma, and increased undifferentiation in cancer. It also became broader with increasing mononuclear cell infiltration in both adenomas and cancers. HLA-DR antigens on adenoma and cancer cells appeared to be related to the neoplastic transformation of the epithelia, and to the mononuclear cell infiltration. Partial disappearance of HLA-ABC antigens on adenoma and cancer cells was observed in a few specimens of both adenomas and cancers.

Adenoma↗
PubMed1990

[Expression of gamma-glutamyl transpeptidase related to the tumor differentiation on squamous cell carcinoma of human skin].

gamma-Glutamyl transpeptidase (gamma-GTP) has been noticed as one of the useful markers for malignant transformation of the skin. But the role and mechanism of the induction of gamma-GTP in skin carcinogenesis had not yet been studied. In this report, the authors studied the relationship between gamma-GTP activity and tumor differentiation in squamous cell carcinoma of human skin (SCC). Ten cases of SCC were examined on intensity and localization of the activity of gamma-GTP histochemically by the method of Rutenberg. gamma-GTP activity was found to be more intense in well differentiated SCC than in poorly differentiated SCC. On the other hand, localization pattern of gamma-GTP activity in SCC was not always related to the tumor grade. We concluded that expression of gamma-GTP activity in SCC may reflects the modulating cell differentiation rather than cell proliferation in malignant transformation of the skin. And some of the typical cases were presented.

Aged↗
PubMed1990

[A comparison of growth and development of the dental arch, alveolar process, and palate in the lateral segment determined with reference to dental age and chronological age, particularly on the period of premolar eruption].

The purpose of this study is to observe and compare growth and development in the dental arch, the alveolar process, and the palate in reference to dental age, which is based on tooth emergence, and chronological age. Subjects consisted of serial dental casts taken at two-month intervals from 40 children (20 males and 20 females) with normal occlusion in permanent dentition. In terms of dental age, observations were made for a total of two years, one year before and one year after the tooth emergence of first premolar and second premolar. In terms of chronological age, observations were made for a total of two years, one year before and one year after the average age of tooth emergence of first premolars and second premolars in this sample of children. Results and Conclusions. Comparisons between growth changes in the dental arch, the alveolar process, and the palate on dental and chronological age showed some regions in which growth patterns were similar and others in which growth patterns were different. The differences between both growth patterns from two ages were classified into two groups according to the tooth which caused the difference: those produced by the tooth used as a standard for dental age and those produced by teeth other than that used as a dental-age standard. 1) Differences resulting from the influence of the tooth used as a dental-age standard In regions of the tooth used as a dental-age standard, differences occurred in growth patterns on both kinds of age in practically all measured items. In regions adjacent to that of the tooth used as a dental-age standard, the differences were observed in growth patterns of the alveolar process and the palate but not in those of the dental arch. The differences were the most pronounced in the regions of dental-age-standard teeth than in the adjacent regions. The majority of the differences caused by teeth used as standards for dental age were thought to have been the results from the influence of eruption. No growth-pattern differences were observable in regions more than two teeth away from the tooth used as a dental-age standard. 2) Differences resulting from the influences of teeth other than that used as a dental-age standard Using the emergence time of a certain tooth as a dental-age standard, the emergence times of other teeth lead to be come together in some degree.(ABSTRACT TRUNCATED AT 400 WORDS)

Alveolar Process↗
PubMed1990

Alteration of plasma sex hormone levels associated with old age and its effect on hepatic drug metabolism in rats.

A mechanism of age-associated alterations in plasma sex hormone levels as well as their effect on drug metabolizing enzyme activities were studied using male and female Fischer 344 rats of ages ranging between 3 and 30 months. Plasma testosterone levels as well as the activity of the rate limiting enzyme required for testosterone production in testes, androstenedione 17 beta-oxido-reductase, decreased with senescence in parallel with the alteration of drug metabolism whereas activity of hepatic microsomal androstenedione 5 alpha-reductase, the testosterone metabolizing enzyme, increased with age. The profile of drug metabolizing activities with imipramine, diazepam, hexobarbital, lidocaine, p-nitroanisole and androstenedione as substrates in old (27-month-old) male rats was almost identical to that in young or old female rats, indicating that neonatal androgenic imprinting of drug metabolism in male rats was erased in senescence. Castration of adult (9-month-old) male rats caused a decrease in drug metabolism, but did not result in complete feminization of the profiles of drug metabolism as was observed in old male rats, indicating that neonatally imprinted male pattern of drug metabolism was still retained in the absence of testosterone in adult male rats. Testosterone administration restored completely male-level activities in castrated adult rats, but caused only a partial recovery in old male rats. It is proposed that senescence associated feminization of the drug-metabolizing ability of the male rat liver may be in part due to the decrease in testosterone levels in old age and in part to the loss of neonatal imprinting.

Aging↗
PubMed1989

Evaluation of the involvement of a male specific cytochrome P-450 isozyme in senescence-associated decline of hepatic drug metabolism in male rats.

The major "male specific" species of cytochrome P-450 (P-450ml) was purified and an antibody against it used to evaluate the involvement of this isozyme in alterations of drug metabolism in senescence. P-450ml exhibited strikingly high imipramine (IM) N-demethylase activity while it showed no IM 2-hydroxylation, which is an alternate pathway of IM metabolism in rat liver microsomes. The antibody to P-450ml inhibited 80% of imipramine N-demethylation in young male rats. In old male rats, which have been shown to have lower IM N-demethylase activity, a 60% inhibition was observed. The inhibitable portion of this activity in old male rats is about one third of that in young rats, but the remaining portion not inhibited by this antibody is almost identical in young and old rats. IM 2-hydroxylation on the other hand was not inhibited by this antibody at all. It also inhibited about 30% of diazepam(DZ) N-demethylation in young rats but showed no inhibition in old rats, resulting in the loss of the age difference in the remaining portion. DZ 3-hydroxylation was not inhibited by this antibody, in spite of the fact that it showed a markedly higher activity in young male than in young female rats with a subsequent reduction in old age in male rats. This study provides the first direct evidence that differences in the amount of the major male specific P-450 isozyme (P-450ml) are responsible for the age- and sex-associated differences in some of the drug metabolizing activities. It also became apparent that P-450ml may not be the only isozyme responsible for these differences.

Aging↗
PubMed1989

Common sites for recombination and cleavage mediated by bacteriophage T4 DNA topoisomerase in vitro.

We have previously shown that purified T4 DNA topoisomerase promotes illegitimate recombination between two lambda DNA molecules, or between lambda and plasmid DNA in vitro (Ikeda, H. (1986) Proc. Natl. Acad. Sci. U. S. A. 83, 922-926). Since the recombinant DNA contains a duplication or deletion, it is inferred that the cross-overs take place between nonhomologous sequences of lambda DNA. In this paper, we have examined the sequences of the recombination junctions produced by the recombination between two lambda DNA molecules mediated by T4 DNA topoisomerase. We have shown that there is either no homology or there are 1-5-base pair homologies between the parental DNAs in seven combinations of lambda recombination sites, indicating that homology is not essential for the recombination. Next, we have shown an association of the recombination sites with the topoisomerase cleavage sites, indicating that a capacity of the topoisomerase to make a transient double-stranded break in DNA plays a role in the illegitimate recombination. A consensus sequence for T4 topoisomerase cleavage sites, RNAY decreases NNNNRTNY, was deduced. The cleavage experiment showed that T4 topoisomerase-mediated cleavage takes place in a 4-base pair staggered fashion and produces 5'-protruding ends.

Base Sequence↗
PubMed1989

Colonic lymphoid cell subsets and epithelial HLA-DR antigens in familial polyposis coli.

Although there has been some evidence suggesting that immunological mechanisms are involved in the pathophysiology of familial polyposis coli (FPC), there has not been any report as to whether there is any abnormality of lymphoid cell subsets as background, whether polyps (adenomas) show different lymphoid cell subsets from the normal mucosa, or whether HLA-DR antigens are expressed on the epithelia of adenomas. Lymphoid cell subsets (CD5, CD4, CD8, IgA1, IgA2, IgM, IgD, IgG, and IgE positive cells) in the lamina propria, and HLA-DR antigens on the epithelia were studied in 7 patients with FPC. From each patient, 2 specimens were obtained from both the normal (non-polypoid) area and the polyp. Normal colonic mucosa, taken from 15 patients with conventional polyps or colorectal cancer, served as the normal control mucosa. Lymphoid cell subsets and HLA-DR antigens were identified by indirect immunoperoxidase staining using mouse anti-human monoclonal antibodies. In the normal area of FPC, lymphoid cell subsets were similar to those of normal control mucosa except for an increase in IgD positive (IgD+) cells. However, definite alterations were observed in the polyp. There were significant increases in the number of CD4+ and IgG+ cells, and in the sum of five classes of Ig+ cells compared to the normal area or normal control mucosa. HLA-DR antigens were not expressed in the normal control mucosa or in the normal areas, and only on the epithelia of the polyp in 5 out of 7 specimens (71%). These results clearly demonstrate that immunological reactions are involved in FPC polyps.

Adenomatous Polyposis Coli↗