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Biomedical subjects

S Kurata

Publications and source records attributed to S Kurata.

At least 127 records · Page 7Linked to original sources
PubMed1991

Epidermal growth factor inhibits transcription of type I collagen genes and production of type I collagen in cultured human skin fibroblasts in the presence and absence of L-ascorbic acid 2-phosphate, a long-acting vitamin C derivative.

Recombinant human epidermal growth factor (EGF, 2-10 ng/ml) stimulated growth and production of non-collagenous proteins, but inhibited production of collagen by 60% in cultured human skin fibroblasts. Type analysis of the collagen produced indicated that inhibition of the collagen production observed was mainly a reflection of a reduction in type I collagen. The accumulation of pro alpha 1(I) and pro alpha 2(I) mRNAs and the transcriptional activity of these genes were determined in human skin fibroblasts in order to investigate site(s) of regulation of type I collagen production by human EGF in the absence and presence of L-ascorbic acid 2-phosphate (Asc 2-P), a long-acting vitamin C derivative. Human EGF (10 ng/ml) used alone reduced the steady state levels of mRNAs for pro alpha 1(I) and pro alpha 2(I) chains and transcriptional activity of these genes in vitro by 45%. Asc 2-P (0.2 mM) alone, on the other hand, raised production of type I collagen and the steady state levels of mRNAs for pro alpha 1(I) and pro alpha 2(I) collagen chains as well as stimulated transcriptional activity of these genes. Human EGF attenuated these stimulative effects of Asc 2-P. These results indicate that human EGF regulates type I collagen synthesis at the transcriptional level in cultured fibroblasts in the presence and absence of Asc 2-P. The possibility that human EGF plays a role as a regulator of type I collagen genes in vivo was discussed.

Ascorbic Acid↗
PubMed1991

Participation of a 200-kDa hemocyte membrane protein in the dissociation of the fat body at the metamorphosis of Sarcophaga.

Three monoclonal antibodies were raised against a 200-kDa protein specifically expressed on the surface of hemocytes when Sarcophaga larvae pupated. One of these antibodies significantly inhibited dissociation of the fat body in the presence of pupal hemocytes, indicating that the 200-kDa protein is essential for dissociation of the fat body by the hemocytes. When the hemocytes were treated with a mixture of the monoclonal antibodies, they were found to secrete a significant amount of chymotrypsin-like proteinase. Moreover, the number of hemocytes expressing the 200-kDa protein increased significantly after puparium formation. These results suggested that some signal is transferred to the hemocytes via the 200-kDa protein when they interact with the basement membrane of the fat body and that this induces their secretion of a chymotrypsin-like proteinase essential for decomposition of the fat body.

Animals↗
PubMed1991

Intranuclear androgen concentrations in facial skin.

The concentrations of 5 alpha-dihydrotestosterone (DHT) and testosterone were measured by radioimmunoassay (RIA) in the crude nuclear and cytoplasmic fractions of facial skin containing large sebaceous glands. The data obtained were compared with those obtained with specimens from non-target areas. The intranuclear levels of DHT and testosterone in facial skin were 0.03 +/- 0.3 pg/micrograms DNA and 0.35 +/- 0.03 pg/micrograms DNA, respectively levels in genital skin. By contrast, both androgens were below detection by RIA in non-target skin. There was no significant difference between men and women with respect to the intranuclear androgen levels in facial skin. These findings support the view that the sebaceous gland is a typical androgen target organ irrespective of sex.

Axilla↗
PubMed1991

Characterization of 5 alpha-reductase in cultured human dermal papilla cells from beard and occipital scalp hair.

In order to gain a deeper insight into the role of 5 alpha-reductase in the growth of beards in men, we studied some kinetic properties of the enzyme in cell homogenates of cultured human dermal papilla cells from beard and occipital scalp hair. When cell homogenates were incubated with [3H]-testosterone, the 5 alpha-reductase of beard dermal papilla cells exhibited an optimum activity at pH 5.5, whereas the enzyme of dermal papilla cells from occipital scalp hair showed a broad and low plateau between pH 6.0 and 9.0, without a sharp peak. The apparent Michaelis constant of 5 alpha-reductase was 3.3 x 10(-7) M in dermal papilla cells from beard and 2.4 x 10(-5) M in those cells from occipital scalp hair. The apparent Km of 5 alpha-reductase for NADPH was 2.8 x 10(-5) M and 7.6 x 10(-4) M in beard and occipital scalp hair dermal papilla cells, respectively. There were no significant differences in the substrate specificity between these two types of cells. The 5 alpha-reductase activity was recovered mainly in the nuclear fraction of beard dermal papilla cells. By contrast, it was widely distributed among the individual subcellular fractions of dermal papilla cells from occipital scalp hair. These results strongly suggest that these two kinds of dermal papilla cells have different types of 5 alpha-reductase, and that the enzyme in beard dermal papilla cells is similar in characteristics to that in the androgen target organs such as prostate.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1991

Spindle cell hemangioendothelioma: report of three cases.

Three cases of spindle cell hemangioendothelioma were studied. Two had multiple nodules and the third had a single, recurrent lesion in the dermis or subcutis of the distal extremities. The tumor initiated at the age of 3 months in one patient and at the ages of 11 or 12 years in the remaining two. Local recurrence after surgical excision was observed in all cases. Microscopically the tumors were composed of two components; cavernous blood spaces and a proliferation of spindle cells. Among these spindle cells, there were occasional epithelioid endothelial cells with intracytoplasmic lumina. Phleboliths were observed in two cases. Most of the endothelial cells lining the cavernous spaces were positive for factor VIII-associated antigen in all cases; the intracytoplasmic lumina were also positive in two cases. The spindle cells were negative for that antigen in all cases. However, they were positive for desmin in one case. Electronmicroscopically, the spindle cells resembled primitive mesenchymal cells.

Adolescent↗
PubMed1991

Recurrent malignant fibrous histiocytoma with expression of cytokeratin.

A case of locally recurrent malignant fibrous histiocytoma was documented in a 70-year-old man. He first noticed a subcutaneous nodule forty years previously. The tumor was surgically removed four times during the last four years with local recurrence on every occasion. In the recurrent tumors, the tumor cells almost completely replaced the whole dermis and invaded skeletal muscles. They were composed of pleomorphic spindle cells arranged in a storiform pattern and bizarre histiocytic cells, which were present principally in the deeper portions of the tumor. Both types of tumor cells showed marked nuclear atypicality. In the primary tumor, surrounding a large necrotic area, spindle-shaped cells were arranged in a storiform pattern. These tumor cells exhibited only mild nuclear atypia. The recurrent tumor was strongly positive for vimentin and alpha-1-antichymotrypsin. Most tumor cells were also weakly positive for KL1, a monoclonal antibody for keratin. A Western-blot analysis revealed the presence of two bands (62 and 69 Kd) reacting with KL1 in the fractions which were obtained from the tumor according to the method for keratin extraction.

Aged↗
PubMed1991

Primary localized amyloidosis in one family.

Primary localized amyloidosis was found in a family. A 66-year-old woman had suffered from hoarseness for 18 years. A biopsy specimen from the larynx showed amyloid deposits in the submucosal connective tissue. Her 40-year-old daughter noticed a subcutaneous nodule on her philtrum. Histologic examination showed the deposition of amyloid in the middle and lower dermis, which also encased the blood vessels and epidermal appendages. In both cases the amyloid deposits were positively stained with Congo red and the staining was resistant to potassium permanganate treatment. These amyloid deposits were strongly positive against the anti-amyloid antibody of the lambda light chain. These results indicate that the amyloid substance is derived from protein AL. There was no clinical or laboratory evidence of systemic amyloidosis or multiple myeloma in either patient.

Adult↗
PubMed1991

Estrogen delays entry of the yeast Saccharomyces cerevisiae into meiosis.

Estrogen has been suggested to influence the cell cycle of haploid yeast cells in the early G1 phase of mitosis, its effect possibly being mediated by control of the level of cAMP (TANAKA, S. et al. (1989). Cell, 57: 675-681). Therefore, we were interested in whether estrogen also affects the meiotic phase of diploid yeast cells. Accordingly, we measured the amounts of adenylate cyclase mRNA and intracellular cAMP, the proportions of dividing cells and 4n cells and the doubling times of diploid yeast cells during the presporulation stage in the presence and absence of estrogen. The amount of adenylate cyclase mRNA was found to decrease rapidly within 24 hours after inoculation of cells onto sporulation-promoting plates (YPA plates). The cAMP level of these cells also decreased rapidly. Mitotic cell division continued for 18 hours after cell inoculation, but about 24 hours after inoculation, the amount of cAMP per cell had decreased to a minimum and the cells began to enter meiosis. By contrast, when the cells were inoculated onto YPA plates in the presence of estrogen, their intracellular cAMP and adenylate cyclase mRNA levels became higher than those in control cultures without estrogen and cell division continued for 24 hours. But after 30 hours their intracellular cAMP level decreased to a minimum and they began to enter meiosis. These results show that estrogen delayed the entry of diploid yeast cells into meiosis on sporulation-promoting plates and suggest that its effect may be mediated by control of the level of cAMP.

Adenylyl Cyclases↗
PubMed1991

Influences of gonadal and adrenal androgens on the side glands of Suncus murinus.

In order to know the contribution of adrenal and gonadal androgens to the development of the side gland of Suncus murinus, we studied the effects of gonadectomy and adrenalectomy on gland thickness and the plasma levels of testosterone, androstenedione (delta 4-dione) and dehydroepiandrosterone (DHA). In males, castration decreased gland thickness to 71% of the control. The plasma levels of delta 4-dione and testosterone were also decreased from 4.16 +/- 0.50 and 0.65 +/- 0.10 ng/ml to 1.44 +/- 0.17 and 0.12 +/- 0.02 ng/ml, respectively. Adrenalectomy following castration caused no notable additional decrease in gland thickness, although the plasma levels of delta 4-dione and DHA were further decreased by this treatment. In females, ovariectomy affected neither gland thickness nor plasma androgen levels, except for a peculiar rise in the plasma concentration of delta 4-dione. In contrast, adrenalectomy in addition to ovariectomy decreased gland thickness to 63% of the control and the plasma concentrations of delta 4-dione and DHA from 1.43 +/- 0.26 and 0.43 +/- 0.05 ng/ml to 0.37 +/- 0.11 and 0.10 +/- 0.04 ng/ml, respectively. Therefore, testicular androgens are required for the male side gland to fully develop, whereas in the female adrenal androgens are important for the maintenance of sebaceous gland activity and delta 4-dione is quantitatively more important than DHA. One hour after the intraperitoneal administration of [3H]delta 4-dione, dihydrotestosterone was found to be the major androgen bound to nuclei of the side gland. Thus, the side gland can utilize delta 4-dione as a precursor of a more active androgen.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenal Glands↗
PubMed1990

Intranuclear androgen and cytosolic receptor concentrations in the axillary skin of osmidrosis.

5 alpha-Dihydrotestosterone (DHT) and testosterone were measured by radioimmunoassay in the crude nuclear and cytoplasmic fractions of the axillary skin of both male and female patients with osmidrosis and the levels compared with those of nongenital skin. The intranuclear levels of DHT were 1.44 +/- 0.22 and 1.77 +/- 0.38 pg/micrograms DNA in men and women, respectively. Those of testosterone were about 10% of DHT levels. In the skin of nontarget regions nuclear DHT was much scarcer or undetectable. Cytosolic androgen receptors in isolated apocrine glands were also measured using 3H-R1881 as a ligand. Typical androgen receptors were present in all of eight patients (KD = 1.32 +/- 0.24 X 10(-9)M, Bmax = 10.3 +/- 0.51 fmol/mg protein). Neither the intranuclear androgen concentrations nor the cytosolic androgen receptor levels were significantly different between the two sexes. These data indicate clearly that the apocrine gland of patients with osmidrosis is a typical androgen target organ, irrespective of sex, and suggest that nuclear DHT in the axillary skin of women is derived from not only testosterone but also other precursors, especially in consideration of the very low serum concentrations of testosterone in females.

Adolescent↗
PubMed1990

Transcriptional activation of the heme oxygenase gene by TPA in mouse M1 cells during their differentiation to macrophage.

The activation of the heme oxygenase (HO), fos, and AP-1 genes was determined at intervals after treatment of M1 cells (derived from mouse myeloleukemia) with heme or 12-O-tetradecanoylphorbol 13-acetate (TPA). On treatment with heme, M1 cells did not differentiate into macrophage but their HO gene was activated and showed maximum transcriptional activity after treatment with heme for 2 h. In contrast, on treatment with TPA, these cells adhered to the culture flasks within 5 h and differentiated into macrophage-like cells. Moreover, the sequential activation of the fos, AP-1, and HO genes was observed during this period, with the maximal transcriptional activities after TPA treatment for 0.5, 1, and 1.5 h, respectively. Thus, the HO gene was activated by treatment with either heme or TPA, and the latter activation was associated with activations of the fos and AP-1 genes. As the rat HO gene is known to have a TPA-sensitive element in its promoter region, this gene was suggested to be activated by a fos-AP-1 complex protein.

Animals↗
PubMed1990

5 alpha-reductase activity in cultured human dermal papilla cells from beard compared with reticular dermal fibroblasts.

The activity of 5 alpha-reductase was assessed in cultured human beard dermal papilla cells and reticular dermal fibroblasts to elucidate the mechanism of androgen action in promoting the growth of beards in men. The monolayer was incubated with 50 nM of [1,2-3H]-testosterone. Steroids were extracted from the medium and analyzed by thin layer chromatography. The major metabolite in the beard dermal papilla cells was dihydrotestosterone (DHT), the most potent androgen in the androgen target tissue. By contrast, the amount of DHT formed was similar to that of androstenedione in reticular dermal fibroblasts. The 5 alpha-reductase activity in beard dermal papilla cells was three to five times as high as that in the reticular dermal fibroblasts from the same skin sample. The apparant Michaelis constant of 5 alpha-reductase in the beard dermal papilla cells was 1.0 X 10(-6) M, which was virtually equivalent to that of genital skin fibroblasts, typical androgen target cells. It was 4.0 X 10(-5) M in reticular dermal fibroblasts. By contrast, the activities of 5 alpha-reductase in dermal papilla cells from occipital scalp hair follicles were similar to those of reticular dermal fibroblasts of the same skin samples. These results strongly suggest that the beard dermal papilla cell is an androgen target cell, and that DHT plays a role in the growth of beards in men.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed1990

[Tooth tapping frequency of young and elderly subjects].

Tooth tapping frequency was measured in young (21-29 years) and elderly (61-67 years) subjects. They were asked to continue the maximal frequent tapping during 1 min., and their mandibular movement were measured with a Mandibular Kinesiograph. The results are as follows: 1. Each phase of closing, occluding, opening and cycle was prolonged at the terminal of the 1 min. tapping. That is, tapping frequency decreased. Young subjects had 4.6 Hz tapping frequency and 2.7 Hz for elderly subjects. 2. Although the opening phase per cycle and the closing were not changed in spite of the tapping continuity, the occluding one increased at the terminal of the 1 min. tapping. 3. No difference existed between the young subjects and elderly in the maximal velocity of the mandibular movement at the opening and closing. Opening velocity was larger than closing velocity at the young subjects.

Adult↗
PubMed1990

[Effect of 3-mercaptopropyltrimethoxysilane coupling agent on stainless steel and silica surface].

Mixed silanes, 3-mercaptopropyltrimethoxysilane and 3-methacryloxypropyltrimethoxysilane, were used as a primer for adhesion of poly(methyl methacrylate) to stainless steel and glass plate. The tensile bond strength of the resin to those substrates was measured after immersion in water at 37 degrees C for 3 days. The mean bond strengths of the resin to the stainless steel and to the glass plate were 23 and 17 MPa, respectively. In addition, cohesional fracture of the resin occurred in both cases. The mixture of the silanes was highly adhesive for the stainless steel and the glass plate surface treatment.

Adhesiveness↗
PubMed1990

The influence of molecular weight distribution of poly(acrylic acid) on tensile bond strength of polycarboxylate cement.

The influence of the weight average molecular weight and the molecular weight distribution of poly(acrylic acid) on the tensile bond strength of polycarboxylate cement was studied. The bond strength of the cement significantly affected not only the mean molecular weight but also the distribution. The tensile bond strength of the cement prepared from an aqueous solution of poly(acrylic acid), which had a mean molecular weight above 100,000 and a narrow molecular weight distribution, was excellently high.

Acrylic Resins↗
PubMed1990

[Effect of temperature during polymerization on mechanical properties of acrylic resin].

Mechanical properties of heat curing acrylic resin obtained by polymerization for long period of heating at a temperature lower than conventional temperatures were examined. The mechanical properties of the resin were lower than those of the resin cured at 100 degrees C. The results of high performance liquid chromatography and differential scanning calorimetry suggested that the poor mechanical properties were due to significant amounts of residue monomer and benzoyl peroxide in the resin, but is not to changes molecular weight.

Acrylic Resins↗
PubMed1989

Estrogen can regulate the cell cycle in the early G1 phase of yeast by increasing the amount of adenylate cyclase mRNA.

The effects of beta-estradiol (estrogen; a minor component of yeast cells) on S. cerevisiae cells in the G0 and G1 phases were examined. Results showed that estrogen stimulated the recovery of growth from G0 arrest induced by nutrient limitation or ts mutation of cdc35 (adenylate cyclase) in the early G1 phase, and inhibited entry into the resting G0 phase by increasing the intracellular cAMP level. However, estrogen had no effect on late G1 arrest induced by the alpha factor or ts mutation of cdc36. Estrogen was found to lead to higher steady-state levels of adenylate cyclase mRNA but not to affect the expression of the RAS1 and RAS2 genes, although these can also alter the intracellular cAMP level. These results suggest that estrogen influences the cell cycle of yeast in the early G1 phase by controlling the level of cAMP through the increase of adenylate cyclase mRNA.

Adenylyl Cyclases↗