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Biomedical subjects

M Takehana

Publications and source records attributed to M Takehana.

At least 37 records · Page 2Linked to original sources
PubMed1994

Production of overmodified type I procollagen in a case of osteogenesis imperfecta.

Collagen synthesis in cultured skin fibroblasts from a patient with osteogenesis imperfecta was studied. Approximately 2 fold accumulation of collagen in the cell layer was found. The slower mobility of pro alpha 1 (I) and pro alpha 2 (I) as well as alpha 1 and alpha 2 (I) polypeptide on sodium dodecylsulfate-polyacrylamide gel electrophoresis was detected, indicating that abnormal posttranslational modification could be present in type I procollagen in patient fibroblasts. The degrees of hydroxylation and subsequent glycosylation of lysine residues in the affected collagen were elevated 1.5 and 1.4 fold, respectively. There were no significant changes in the relative content of type III to type I collagen nor the incorporation of mannose into the carboxyterminal propeptide of pro alpha 1 (I) and pro alpha 2 (I). These results indicate that the patient produces an over-modified type I procollagen which is responsible for the clinical features and has a collagen abnormality already reported in type II osteogenesis imperfecta.

Cells, Cultured↗
PubMed1994

Possible role of metallothionein in the cellular defense mechanism against UVB irradiation in neonatal human skin fibroblasts.

The role of metallothionein (MT) in protecting skin cells against UVB irradiation was investigated. Fibroblast strains from normal adult (HS-K) and neonatal (NB1RGB) human skins as well as keratinocyte strains from human skin (SV40-HSK) and newborn Balb/c mouse skin (Pam 212) were exposed to UVB irradiation. The sensitivity of HS-K and NB1RGB cells to UVB irradiation was similar; those of SV40-HSK and Pam 212 cells were two- and six-fold as sensitive to UVB irradiation as HS-K cells, respectively. The HS-K cells contained the greatest cellular reduced form of glutathione (GSH) levels compared to the three other skin cells: the levels were 13-, 7- and 6-fold of those in NB1RGB, SV40-HSK and Pam 212 cells, respectively. These results indicated that the sensitivity of skin cells to UVB irradiation was not always associated with their endogenous GSH levels. In particular, despite the fact that NB1RGB cells contained a relatively small amount of GSH, they were less sensitive to UVB irradiation. NB1RGB cells contained 4-30 times more MT than those in other skin cells examined. The sulfhydryl residues of MT molecules in the NB1RGB cells were estimated to be mostly unoccupied by metals, suggesting they act in a similar way to those of GSH. Moreover, NB1RGB cells in which the MT content was elevated by dexamethasone (1 microM) or Zn2+ (7 micrograms/mL) treatment were more resistant to UVB irradiation than nontreated ones. These results suggest that, at least in neonatal human skin fibroblasts, MT may play a role in protection against UVB irradiation.

Animals↗
PubMed1994

The relationship between properties of antipsychotic drugs and cataract formation.

It has been reported that antipsychotic drugs such as phenothiazine derivatives, dibenzyl derivatives and others with calmodulin antagonism induce cataracts, which are generically called phenothiazine-induced cataracts. In the ophthalmologic field, the mechanism of cataractogenesis by such drugs is a problem urgently requiring a solution. This paper reports the relationship between the properties of such drugs and cataract formation. In this experiment, phenothiazine derivatives (chlorpromazine, trifluoperazine, prochlorperazine and perphenazine), dibenzyl derivatives (imipramine and amitriptyline), and other drugs (cyproheptadine and calmidazolium) were investigated. As a result, it was clarified that phenothiazine derivatives and calmidazolium have high lipophilicity, strong inhibition activity against phosphodiesterase, and a large permeability constant, and that those drugs induce high levels of Ca2+ accumulation in the lens. It was also revealed that those drugs were distributed only at the peripheral region of the lens after they had penetrated into the lens. From these findings, we inferred that the cataract formation may be caused by lens protein aggregation followed by the inactivation of calmodulin-dependent Ca-ATPase and subsequent Ca2+ accumulation in the lens. Furthermore, we have been convinced that it is necessary to lower at least the lipophilicity of these drugs to suppress the side effect of antipsychotic drugs inducing cataractic formation.

Animals↗
PubMed1993

Presence of the factor that inhibits collagen synthesis and stimulates cell proliferation in developing embryonic chick skin extracts.

The effects were studied of the extracts prepared from 10- and 18-day developing chick skins on collagen synthesis and proliferation of the monolayered fibroblasts established from 10-day skin. Cell proliferation was stimulated by both 10- and 18-day skin extracts at the concentration of 3.5 micrograms/ml. Collagen synthesis was suppressed by the treatment of extracts prepared from both 10- and 18-day skins at the concentration of 3.5 micrograms/ml, to a greater extent in 18-day extract. The results indicate that skin extracts possess factors exhibiting both a stimulating effect on cell proliferation and an inhibitory effect on collagen synthesis.

Animals↗
PubMed1993

Glutathione isopropyl ester (YM737) inhibits the progression of X-ray-induced cataract in rats.

The effect of glutathione (GSH) isopropyl ester on the progression of X-ray-induced cataract was investigated in rats. Intraperitoneal administration of 20 mg/kg GSH isopropyl ester, three times weekly, 1 day after a single irradiation dose delayed the progression of X-ray-induced cataracts significantly. The amount of non-protein SH groups and the Na+/K+ ratio in the lenses of drug-treated rats were maintained at the normal levels even 27 weeks after irradiation. Posttreatment with the drug resulted in a significantly lower level of malondialdehyde in the irradiated lenses than in the nontreated lenses. When 500 mg/kg GSH-isopropyl ester was administered by i.p. injection to normal rats, the GSH-ester was detected in plasma and aqueous humor after 15 min. In the lenses of the GSH-isopropyl ester-injected rats, the GSH level was 120% of that in the non-treated rats after 4 h, suggesting that GSH-isopropyl ester is transported from the aqueous humor to the lens and there converted to GSH after about 4 h. Our observations lead us to conclude that the delay of X-ray-induced lens opacity progression is due to maintenance of normal lenticular GSH levels achieved by post-irradiation administration of GSH-isopropyl ester. However, continuous administration of 100 mg/kg after irradiation had no effect on the progression of cataracts induced by X-rays.

Animals↗
PubMed1992

Effects of 2-mercaptopropionylglycine on the development of X-ray-induced cataract in rats.

The effect of 2-mercaptopropionylglycine on the development of cataract induced by a single dose of X-ray (10 Gy) was investigated in rats. Intraperitoneal injection of 20 mg/kg, three times weekly starting 1 day after irradiation delayed the development of X-ray-induced cataracts significantly. The amounts of non-protein SH groups, malondialdehyde and the Na+/K+ ratio, in the lenses of rats post-treated with the drug were significantly maintained at normal levels even at 27 weeks after irradiation. On the other hand, a single administration of 250 mg/kg of the compound, 30 min prior to irradiation had no effect on cataract progression induced by X-ray.

Animals↗
PubMed1990

Hereditary cataract of the Nakano mouse.

The Nakano mouse is a hereditary cataract model whose most characteristic change is a deficiency in lens Na+,K(+)-ATPase. Consequently, there is a change in lenticular sodium and potassium ion levels just before cataract formation. The amounts of calcium ion also change suddenly in the lens, with accumulated levels higher than any other type of cataract. Other biochemical changes coincide with the development of lens opacity, including decreases in the levels of reduced glutathione, ATP, biosynthetic activity of proteoglycans in epithelial cells, and the permeability of gap junction channels in fiber cells. The decrease in the activity of Na+,K(+)-ATPase results in changes in a number of key metabolic parameters, resulting in the eventual opacification of the Nakano mouse lens at approximately 30 days of age.

Animals↗
PubMed1987

Cleavage from the N-terminal region of beta Bp crystallin during aging of the human lens.

Polyclonal antisera have been made to synthetic peptides that correspond to the N-terminal (residues 1-12) and C-terminal (residues 195-204) sequences of bovine beta Bp crystallin. Both anti-beta Bp1-12 and anti-beta Bp195-204 recognize specifically the beta Bp component of bovine lens. In the young human lens, anti-beta Bp195-204 recognizes predominantly the 26,000 MW form of beta Bp, while in older lenses this same antiserum recognizes mainly the 22,000 MW in vivo proteolysis product. In contrast, during aging of the normal human lens anti-beta Bp1-12 recognizes only decreasing amounts of the 26,000 MW form of beta Bp, with no binding to the 22,000 MW form of this polypeptide. These results suggest that during aging of the normal human lens, the N-terminus of beta Bp is the preferred site of in vivo proteolysis.

Adolescent↗
PubMed1987

Influence of calmodulin antagonists on Ca2+ transport in the lens.

Attempts were made to elucidate the relation between lens opacification resulting from inhibition of Ca2+ transport and high calcium accumulation in the lens. Mouse lenses were incubated with naphthalenesulfonamide compounds (W-5, W-7, W-12 and W-13) which act as calmodulin antagonists. When lens Ca2+-ATPase activity was inhibited by those calmodulin antagonists, an accumulation of calcium in the lens was observed. This phenomenon depended on the chemical structure of calmodulin antagonist. In lenses treated with W-7, more than 97% of excess calcium was bound. Insoluble protein increased from 8.5 to 17% of the total protein and the degree of lens opacification increased to 85.1%. These results suggested that dysfunction of the Ca-pump system leads to calcium accumulation, thus in turn inducing protein denaturation which in turn is followed by lens opacification.

Animals↗
PubMed1987

Quantitation of membrane-associated crystallins from aging and cataractous human lenses.

Membrane from individual cataractous and normal human lenses has been prepared by discontinuous sucrose gradient centrifugation. A sensitive solid-phase radioimmunoassay has been developed to quantitate the levels of alpha, beta, and gamma crystallins associated with membrane obtained from each sucrose gradient interface. The results of this analysis demonstrate significant levels of all three crystallins associated with purified membrane. Although the relative percentage of each membrane-associated crystallin does not change during aging and/or cataractogenesis of the human lens, membrane from cataractous lenses in characterized by greater total amounts of crystallins associated with purified membrane obtained from denser interfaces of the discontinuous sucrose gradient.

Adolescent↗
PubMed1986

Covalent change of major intrinsic polypeptide (MIP26K) of lens membrane during human senile cataractogenesis.

Polyclonal antisera have been made against synthetic peptides corresponding to the C-terminal octapeptide and N-terminal nonapeptide of bovine MIP26K. Western blot analysis demonstrated significant binding of the C-terminal antiserum to MIP26K of both normal and cataractous human lens. In contrast, the N-terminal antiserum bound to MIP26K of normal lenses, but failed to bind to MIP26K of 7 out of 10 cataractous lenses studied. These results demonstrate for the first time, a covalent change in MIP26K during human cataractogenesis, and strongly suggest that the location of this change is in the N-terminal region of the polypeptide.

Aged↗
PubMed1986

Major intrinsic polypeptide (MIP26K) from human lens membrane: characterization of low-molecular-weight forms in the aging human lens.

Antisera made against a C-terminal octapeptide of bovine MIP26K and against an N-terminal nonapeptide from the same protein have been used to determine the location of age-dependent cleavage sites of MIP26K in the human lens. Neither the C-terminal antiserum (anti-MIP26K256-263) nor the N-terminal antiserum (anti-MIP26K1-9) binds to the 22,000 MW form of MIP26K, suggesting cleavage from both the N- and C-terminus during lens aging. Anti-MIP26K256-263, but not anti-MIP26K1-9, binds to 20,000 and 15,000 MW forms of MIP26K, demonstrating that age-dependent production of these forms occurs by cleavage from the N-terminal side of the molecule. Together, these results show that age-dependent processing of MIP26K in the human lens occurs from both ends of the molecule, with cleavage from the N-terminal end being mainly responsible for production of the lower-molecular-weight 20,000 and 15,000 MW components.

Adolescent↗
PubMed1986

Covalent changes in MIP26K during aging of the human lens membrane.

Rabbit antisera have been made to the C-terminal octapeptide of bovine MIP26K (residues 256-263) and to an octapeptide near the C-terminus (residues 252-259). Use of these antisera in Western blot analysis of membrane from young vs old human lenses, and from cortex vs nucleus of old human lenses, suggest age-related covalent changes in the C-terminus of MIP26K. These age-related changes in anti-256-263 and anti-252-259 sera can be mimicked by treatment of lens membrane with carboxypeptidase Y, suggesting the loss of 1-8 amino acid residues from the C-terminus of the 26,000 dalton form of MIP26K during aging of the normal human lens.

Aging↗
PubMed1985

Major intrinsic polypeptide (MIP26K) from lens membrane: reconstitution into vesicles and inhibition of channel forming activity by peptide antiserum.

Bovine and human lens membrane, when reconstituted into lipid vesicles containing oxidized cytochrome C, will mediate the transmembrane passage of ascorbate into the vesicles, where the reduction of cytochrome C is measured spectrophotometrically. This channel forming activity is specifically inhibited by antiserum made against a synthetic octapeptide near the C-terminus of MIP26K. Together, these studies describe a direct and more sensitive assay system for measurement of channel-forming activity of MIP26K, and suggest that the C-terminus of this molecule may be particularly important in the regulation of channel formation.

Animals↗
PubMed1985

Biosynthesis of proteoglycans by lens epithelial cells of cataractous mouse (Nakano strain).

The capsules (with epithelial cells attached) of lenses from normal and cataractous mice (Nakano strain) were biosynthetically labeled in vitro with radioactive precursors. The labeled macromolecules were chromatographed on a Sepharose CL-4B column and analyzed by specific enzyme digestion. The incorporation of [3H]-proline and [3H]-glucosamine into macromolecules was comparable in the cataract and normal capsules, while that of [35S]-sulfate was reduced by 60% in the cataract capsules, indicating that the proteoglycan synthesis was specifically decreased in the cataract lens. Glycosaminoglycan analyses showed an increased synthesis of hyaluronic acid and decreased synthesis of heparan sulfate in the cataract capsules. It is possible that the alterations in the synthetic level and glycosaminoglycan components of proteoglycan affect the permeabilities of macromolecules to lens capsule and lead to cataract in Nakano mouse lens.

Animals↗
PubMed1984

Biochemical studies on the use of sodium hyaluronate in the anterior eye segment. I. Variation of protein and ascorbic acid concentration in rabbit aqueous humor.

To investigate the safety of the use of sodium hyaluronate in anterior segment surgery, the changes in protein, ascorbic acid and hyaluronate concentration in the aqueous humor, and intraocular pressure were followed after sodium hyaluronate was injected into the anterior chamber. When a 1% solution of sodium hyaluronate with a molecular weight of 800K was injected, the recovery patterns of protein and ascorbic acid concentration to normal levels were the same as the recovery patterns after injection of phosphate buffered saline which was the solvent for sodium hyaluronate. However, when a 1% solution of sodium hyaluronate with a molecular weight of 1640K or a 2% solution with a molecular weight of 800K was injected, it was observed that the recovery times of protein and ascorbic acid concentration to normal levels were longer than that required after injection of 1%, 800K sodium hyaluronate. Further, the recovery time of the aqueous humor components to normal levels was associated with the clearance time of sodium hyaluronate from the anterior chamber. The transient increase in intraocular pressure by injection of sodium hyaluronate was observed, but it disappeared in 12 hrs. The recovery time of intraocular pressure to normal level was independent of molecular weight and concentration of sodium hyaluronate tested.

Animals↗
PubMed1984

Activator of Ca2+-transport in the lens.

It has been hypothesized that an activator of Ca-ATPase co-exists with Ca-ATPase in the mouse lens. Though the Ca-ATPase activity could be measured from mouse lens homogenate, its activity could not be determined in individual soluble and insoluble fractions. The Ca-ATPase activity, however, could be detected when an activator of this enzyme such as calmodulin was added to the lens insoluble fraction. This enzyme in the lens insoluble fraction was activated also by addition of soluble fraction. The Ca-ATPase in homogenate was inhibited by chlorpromazine and N-(6-amino-hexyl)-5-chloro-1-naphthalenesulfonamide (W-7), which are calmodulin antagonists. When the mouse lens was incubated with W-7, the degree of the lens opacification increased in relation to W-7 concentration.

Animals↗