Search PubMed⌕ Search

Biomedical subjects

S Tajima

Publications and source records attributed to S Tajima.

At least 343 records · Page 19Linked to original sources
PubMed1991

Mechanisms of stimulation of collagen synthesis during chick embryonic skin development.

To study how collagen synthesis is regulated in developing chick embryonic skin, hydroxyproline synthesis, incorporation of proline, and translational activity and content of collagen mRNA in 12-, 15-, and 18-day skins were determined and compared with each other. Hydroxyproline synthesis in the 18-day skins was markedly increased over that in the 12-day skins, whereas proline incorporation was moderately increased. The increase in collagen synthesis from day 15 to 18 was accompanied by increases in both the translational activity and the content of type I procollagen mRNA, with a selective increase in the lower-molecular-weight species of pro alpha 1 (I) collagen mRNA. In contrast, the stimulation of collagen synthesis from day 12 to day 15 did not parallel the levels of type I procollagen mRNA. These results suggest that the stimulation of collagen synthesis is regulated by collagen mRNA levels only in the later stage of development (from day 15 to day 18). Both the collagen synthesis and type I procollagen mRNA levels in the fibroblasts isolated on each corresponding day were constant. The difference in collagen synthesis under two different culture conditions suggests that cell-matrix interaction and/or some serum factors, including several growth factors, are essential for the marked stimulation of collagen synthesis observed in 12- to 18-day skin.

Actins↗
PubMed1991

Secretion of a unique collagen by spontaneously transformed murine keratinocytes (PAM cells) in vitro.

A spontaneously transformed murine keratinocyte cell line (PAM cell) was found to secrete two nondisulfide-linked collagenous polypeptides with apparent molecular weight (MW) 190-kd and 120-kd. Pulse-chase experiments indicated that the 190-kd polypeptide was secreted into the culture medium in 2 h and processed to the 120-kd collagen component within 4 h. This process was inhibited by EDTA. The 120-kd polypeptide was sensitive to pepsin, and a 50-kd fragment was produced by a mild pepsin treatment at 4 degrees C. A cyanogen bromide peptide map of the 120-kd polypeptide was distinct from that of types I, II, III, IV, and V collagens. These properties indicate similarities to the type VIII-related collagen produced by human astrocytoma cells. The secretion of the collagen rapidly reached a maximum level on the first day of culture and subsequently declined with cell proliferation. An accelerated processing to the 120-kd polypeptide was observed under culture conditions of high cell density. Similar collagens were also found to be produced by normal human keratinocytes. These results indicate that the 120-kd polypeptide is a potentially functional protein that may participate in the formation of the extracellular matrix of keratinocytes.

Animals↗
PubMed1991

Primary localized cutaneous nodular amyloidosis: case report and biochemical analysis of amyloid.

We report a patient with scalp lesions of primary localized cutaneous nodular amyloidosis. The extensive examination revealed no systemic involvement. Analysis of glycosaminoglycans (GAGs) in amyloid deposits showed a twofold increase as compared with normal skin, which was due to the increase in dermatan sulfate. Local disorders of GAG metabolism may be related to the amyloid fibril formation. Amyloid fibrils were purified and identified electron-microscopically, which consisted of two major 12,000- and 13,000-dalton and minor 29,000- and 48,000-dalton peptides. Western blotting analysis showed a minor 29,000-dalton peptide reactive with antibodies against both kappa and lambda light chains of immunoglobulin. There is a possibility that some components of amyloid in some cases of primary localized cutaneous nodular amyloidosis may consist of both kappa and lambda immunoglobulin light chains.

Amyloidosis↗
PubMed1991

Angiotensin II stimulates collagen synthesis in cultured vascular smooth muscle cells.

The aim of the present study was to investigate whether angiotensin II, by increasing extracellular matrix synthesis, contributed to the vascular wall thickening observed in hypertension. Thus, we examined the direct effects of angiotensin II on collagen and fibronectin synthesis in cultured rat vascular smooth muscle cells by measuring 3H-proline incorporation. Angiotensin II, in a concentration of 10 mumol/l, increased collagen synthesis in a dose-dependent manner up to 1.8-fold. This increase occurred within 24 h after the addition of angiotensin II and the time required to reach maximum stimulation was approximately 48 h. This increase was receptor-mediated and correlated with an increase in its specific messenger RNA. A closer study of the collagen increase demonstrated a relatively greater increase in type V collagen than type I or type III collagen. Fibronectin synthesis was also increased 1.5-fold with 10 mumol/l angiotensin II. These data suggest that angiotensin II induces vascular wall thickening by acting directly on smooth muscle cells and enhancing the production of extracellular matrix proteins.

Angiotensin II↗
PubMed1990

Preferential inhibition of elastin synthesis by epidermal growth factor in chick aortic smooth muscle cells.

Epidermal growth factor inhibits elastin synthesis in chick aortic smooth muscle cells. The inhibitory effect was dose-dependent with a ninety percent reduction at 100 ng/ml and time-dependent with at least 6h lag phase for the expression of the effect. In contrast, collagen synthesis remained constant. The degree of inhibition in elastin synthesis was parallel to the decrease in the steady-state levels of elastin mRNA. These results indicated that epidermal growth factor specifically inhibits elastin synthesis and will be a useful suppressor for elastogenesis under pathological conditions.

Animals↗
PubMed1990

Increased survival length of experimental flap by calcium antagonist nifedipine.

The effect of a calcium antagonist (nifedipine) on flap survival was examined. A flap measuring 15 mm wide x 70 mm long was designed on the central region of the back of rats. The base of the flap was located 20 mm cranial from the root of the tail in each rat. The effect of the drug was evaluated on the basis of the difference between the dye distance and survival length. It was found that nifedipine extended the survival length of the flap. There were no significant differences in increased survival length between nifedipine and intravenously administered prostaglandin E1. There was no dose-dependent change on the effect of nifedipine. Increased survival length was demonstrated even at its usual clinical dosage. It was anticipated that there is a possibility of clinical application of this drug.

Animals↗
PubMed1990

Partial cDNA cloning of the 230-kD mouse bullous pemphigoid antigen by use of a human monoclonal anti-basement membrane zone antibody.

A cDNA clone with the coding sequence for the 230-kD bullous pemphioid (BP) antigen was isolated from a mouse cDNA expression library by using an anti-basement membrane zone human monoclonal antibody (MoAb-5E). The lambda gt11 cDNA expression library was constructed from poly(A)+RNA from the mouse epidermal cell line, Pam cells, by random priming. 1.5 X 10(5) recombinant clones were screened by immunostaining with MoAb-5E and one positive clone (BPM1) was obtained. All of the ten BP sera but none of the five normal or seven pemphigus sera tested reacted with the fusion protein produced by BPM1. The size of the cDNA was 3.2 kb. Northern blot analysis indicated that BPM1 cDNA hybridized to a mRNA of about 9 kb, which is large enough to encode for a 230-kD protein. DNA sequencing demonstrated a 2,991-bp open reading frame encoding a peptide of 115 kD. Sequence comparison between mouse and human cDNA clones revealed that the 230-kD BP antigen was well conserved during evolution except for the carboxyl terminus. Highly conserved and hydrophilic regions in the molecule were considered to be good candidates for antigenic determinants. This cDNA clone will be useful not only for diagnosis of BP, e.g., enzyme-linked immunosorbent assay using recombinant proteins or synthetic peptides as antigens, but also for pathophysiologic study in which mouse models of BP might be used.

Amino Acid Sequence↗
PubMed1990

Hyperlipoproteinemia as a risk factor for ischemic heart disease.

We analyzed serum lipoproteins and apolipoprotein E (apo E) from 199 patients in CCU, having ischemic heart disease, and from 211 healthy subjects. It was suggested that serum lipoprotein abnormalities, especially elevated low density lipoprotein (LDL) levels, are closely related to atherogenesis in relatively young patients and subjects with severe coronary lesions. The frequency of apo E-4 was higher and that of E-2 was lower in the CCU group than in the control group. Apo E mutants, E-7 (Glu244----Lys, Glu245----Lys) and E-5 (Glu3 (Glu3----Lys), were also frequent in the CCU group. Apo E isoproteins have higher pI in the order E-2, E-3, E-4, and we observed that LDL-cholesterol levels increased in the same order. The apo E mutants, E-5 and E-7, are also more basic than E-4. These findings suggest that basic apo Es were associated with the development of atherosclerosis. The prevalence of familial hypercholesterolemia (FH) in the CCU group was more than 10 times higher than the reported frequency of FH heterozygotes in normal population. The persistence of marked hypercholesterolemia from infancy probably makes FH patients susceptible to atherosclerosis. Based on the analysis of LDL-receptor protein synthesis, various types of mutations were observed even in phenotypically homozygous FH patients. FH homozygotes were divided into 2 groups, a receptor-negative group and a receptor-defective group. We found a great difference in the frequency of coronary heart disease depending on whether even a small number of receptors were present or not.

Apolipoproteins E↗
PubMed1990

[Comparisons of effects of vitamin D3 metabolites on mineralization: utilization of incisor dentin in parathyroidectomized rats].

The rat incisor is continuously growing throughout the animal's life recording the state of mineralization within its dentin at all times. Therefore, it was assumed that the incisor dentin was suitable material for studying the effects of various drugs on such mineralization. The present study set out to examine the effects of vitamin D3 metabolites on the remineralization of dentin and the serum calcium level in parathyroidectomized (PTX) rats. Male Wistar rats weighing about 200-250 g were parathyroidectomized. Each rat was given daily 12 g of a synthetic diet containing 0.1% Ca and 0.4% P (normal P) or 0.06% P (P deficient) without vitamin D. Exp. I: Three groups of rats given a normal P diet were orally administered vehicle, 25 (OH) D3 (50 IU/rat) or 1,25 (OH)2D3 (5 IU/rat) for 5 days from the 28th day after PTX, respectively. Exp. II: Two groups of rats given a normal P diet or a P deficient diet were further divided into 4 sub-groups and intramuscularly administered 0, 5,000, 10,000 or 20,000 IU of vitamin D3 on the 9th day after PTX, respectively. The active vitamin D3, 1,25 (OH)2D3 restored the mineralization of the dentin which had been suppressed following PTX, and elevated the serum calcium level to about 9 mg/dl. However, the 25 (OH) D3 neither restored the mineralization of the dentin nor elevated the serum calcium level in the PTX rats. At doses below 1,000 IU, vitamin D3 could not restore the mineralization of the dentin. However, at massive doses above 5,000 IU, the mineralization was restored in proportion to the dose. The serum calcium levels also increased in proportion to the dose. It is assumed that the increase of the serum calcium level was mainly due to the enhancement of calcium absorption from the intestine by vitamin D3. Both remineralization of the incisor dentin and increase of the serum calcium level were more marked in groups of rats given a P deficient diet than in those given a normal P diet. In all cases in the present experiments, the degree of mineralization of the dentin seemed to correspond with the degree of elevation of the serum calcium levels. These results suggest that the remineralization of the dentin in the PTX rats was attributable to the effect of the vitamin D3 metabolites on serum calcium regulation. Relative biological activities of 1,25 (OH)2D3, 25 (OH) D3 and vitamin D3 on the remineralization of dentin were estimated to be 1, less than 0.02 and less than 0.001, respectively.

Animals↗