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Biomedical subjects

Y Tamada

Publications and source records attributed to Y Tamada.

At least 19 recordsLinked to original sources
PubMed1997

SJA6017, a newly synthesized peptide aldehyde inhibitor of calpain: amelioration of cataract in cultured rat lenses.

The purposes of this experiment were to: (1), characterize the peptide aldehyde SJA6017, N-(4-fluorophenylsulfonyl)-L-valyl-L-leucinal, a newly synthesized inhibitor of calpain, and (2) test the effect of SJA6017 in preventing calcium ionophore-induced cataract in cultured rat lenses. In vitro, SJA6017 strongly inhibited purified m-calpain from porcine kidney. Casein zymography confirmed that SJA6017 reversibly bound to the active site of m-calpain. SJA6017 was also confirmed to be a cell-permeable inhibitor in Molt-4 cells. In cultured lenses, SJA6017 reduced nuclear opacity and proteolysis of crystallins and alpha-spectrin caused by calcium ionophore A23187. These results suggested that SJA6017 is a reversible and cell-permeable calpain inhibitor which may possess great efficacy against calcium-induced models of cataract.

Animals↗
PubMed1997

Direct retinal projections to GRP neurons in the suprachiasmatic nucleus of the rat.

The retinal projections to gastrin-releasing peptide (GRP)-expressing neurons in the rat suprachiasmatic nucleus (SCN) were investigated by double immunofluorescence and immunoelectron microscopy. Optic nerve terminals labeled by cholera toxin B subunit (CTb) which was transported from the retinal ganglion cells were intermingled with GRP-immunoreactive cell bodies and processes in the ventrolateral portion of the SCN. Ultrastructural analysis revealed that CTb-immunoreactive retinal terminals made synaptic contacts with GRP-immunoreactive dendritic processes. These results demonstrated that photic information is directly input from the optic nerve to GRP neurons in the SCN and these GRP neurons may be involved in circadian entrainment by light.

Animals↗
PubMed1997

Induction of NGFI-A gene expression in the rat suprachiasmatic nucleus by photic stimulation.

Photic induction of NGFI-A gene expression was investigated in the rat suprachiasmatic nucleus (SCN) using in situ hybridization histochemistry. Following light exposure for 30 min, NGFI-A mRNA appeared in the ventral portion of the rostral SCN, in the ventrolateral and in part of the dorsomedial portion at the middle level, and in the lateral portion of the caudal SCN. The distribution of NGFI-A mRNA was wider than that of c-fos mRNA which was confined to the ventrolateral portion at the middle level of the SCN. By double labeling in situ hybridization, approximately half of NGFI-A mRNA-positive cells in the SCN were shown to coexpress vasoactive intestinal peptide (VIP) mRNA, while 16% of cells positive for c-fos mRNA coexpressed VIP mRNA. These findings indicate that the broadness of NGFI-A mRNA and c-fos mRNA expression after photic stimulation are different. NGFI-A gene induced in these cells of the SCN including VIP neurons may be involved in circadian entrainment by light.

Animals↗
PubMed1997

Involvement of two basic residues (Lys-270 and Arg-276) of human liver 3 alpha-hydroxysteroid dehydrogenase in NADP(H) binding and activation by sulphobromophthalein: site-directed mutagenesis and kinetic analysis.

A human liver 3 alpha-hydroxysteroid dehydrogenase isoenzyme, a member of the aldo-keto reductase family, shows a marked preference for NADP(H) over NAD(H), and is activated by sulphobromophthalein, which increases the Km values for both NADP(H) and substrates. Here we report kinetic alterations in binding of the coenzymes and the activator to the enzyme caused by site-directed mutagenesis of Lys-270 and Arg-276, which are strictly conserved among the aldo-keto reductase family of enzymes. The mutated enzymes, K270M and R276M, showed increases in the Km for NADP+ of 22- and 290-fold respectively; the Km for alcohol substrate and the kca1 of the NADP(-)-linked reaction were also elevated, by 9- and 5-fold respectively. No kinetic constant of the NAD(+)-linked reaction was altered by more than 3-fold. Calculation of the free-energy changes showed that the 2'-phosphate group of NADP+ contributes 16.3 kJ/mol (3.9 kcal/mol) of binding energy to its interaction with the wildtype enzyme, and the mutagenesis to K270M and R276M destabilized the binding energy of NADP+ by 6.3 and 13.0 kJ/mol (1.5 and 3.1 kcal/mol) respectively. In addition, the mutations attenuated enzyme activation by sulphobromophthalein, which bound to the mutant enzymes as an inhibitor. The inhibition for the R276M mutant was competitive with respect to NADP+ and non-competitive with respect to the substrate, whereas that for the K270M mutant was mixed-type, showing activation at coenzyme concentrations greater than 20 x Km. These results suggest that the two basic residues in the 3 alpha-hydroxysteroid dehydrogenase isoenzyme play crucial roles in binding both the negatively charged 2'-phosphate group of NADP+ and the sulphonic groups of sulphobromophthalein.

3-Hydroxysteroid Dehydrogenases↗
PubMed1997

Loss of day-night differences in VIP mRNA levels in the suprachiasmatic nucleus of aged rats.

Age-related decreases in circadian oscillating activity are speculated to be one of the causes of psychiatric symptoms. To explore the effects of aging on vasoactive intestinal peptide (VIP) synthesis in the suprachiasmatic nucleus (SCN), we investigated the changes in VIP mRNA levels in aged rats compared with young-adult rats under a light/dark cycle using in situ hybridization combined with microcomputer-based imaging analysis. In the young-adult rats, total signals of VIP mRNA in the light-phase showed a significant decrease compared with those on the dark-phase. The VIP signal level in the aged rats was markedly lower than that in young-adults in both light and dark phases. Moreover, in the aged rats, there were no significant differences in VIP mRNA level between the light and dark phases. These results suggest that gene expression of VIP neurons, a main component of the circadian oscillating system, becomes disturbed in the aged rat brain.

Aging↗
PubMed1997

Calpain-induced light scattering by crystallins from three rodent species.

The purpose of the present investigation was to compare in vitro light scattering in the soluble proteins from rodent lenses after hydrolysis by the calcium-activated protease, m-calpain (EC 3.4.22.17). Light scattering was measured in solutions of lens proteins from mice, rats, and guinea pigs after activation of endogenous m-calpain or after addition of purified m-calpain. We found for the first time that, in addition to rat, crystallins from another rodent lens, young mouse, were susceptible to calpain-induced light scattering. As in rats, aging of mouse lens prevented calpain-induced light scattering. Although crystallins from guinea pig lens were also partially hydrolysed by calpain, appreciable light scattering did not occur. Limited proteolysis may cause common changes in the biophysical properties of mouse and rat crystallins to decrease their solubility. Discovery of the nature of these biophysical changes may help our understanding as to why crystallins precipitate under cataractous conditions.

Aging↗
PubMed1997

Linear focal elastosis: a review of three cases in young Japanese men.

Linear focal elastosis in three young Japanese men is described. The lesions are asymptomatic palpable yellow strialike bands extending horizontally across the middle and lower parts of the back. They are histologically composed of many fine wavy bundles of elastic fibers separating the dermal collagen bundles. Electron microscopy demonstrates numerous elongated and fragmented elastic fibers.

Adolescent↗
PubMed1997

Pitted keratolysis: clinical manifestations in 53 cases.

Pitted keratolysis (PK) has been reported to be more common among bare-footed people living in tropical regions. It is now known that the disease is not limited to the tropics but has a world-wide distribution. However, no study has previously been performed analysing the clinical manifestations of the disease in temperate countries. A survey of 53 patients revealed several distinctive clinical features. Hyperhidrosis is the most frequently observed symptom of this condition. Malodour and sliminess of the skin are also distinctive features, evident in 88.7% and 69.8% of the cases, respectively. The most common sites of onset of PK are the pressure-bearing areas, such as the ventral aspect of the toe, the ball of the foot and the heel. The next most common site is a friction area, the interface of the toes. Lesions are rarely seen on the non-pressure-bearing locations. Some of the primary lesions originate as a small defect along the plantar furrow, which gradually grows into the characteristics crateriform pit. Several clinical features are helpful in diagnosing PK.

Adolescent↗
PubMed1997

Apoptotic cell death of neutrophils in development of skin lesions of patients with anaphylactoid purpura.

The participation of apoptotic cell death of neutrophils in the development of skin lesions of patients with anaphylactoid purpura was examined by the in situ specific labeling of fragmented DNA. In the early stage of the skin lesions, there were few positively stained nuclei in infiltrating cells. The number of positive cells increased markedly in the fully developed stage of the lesions. A number of neutrophils were stained positively. Finally, a few fragmented nuclei were still positive in the late stage of the lesions. It was therefore suggested that fragmentation of neutrophils in the skin lesions from the patients might be due to apoptosis. Inducible nitric oxide synthase and nitrotyrosine were detected in infiltrates, and interleukin-8 was also detected in vascular endothelial cells in those skin lesions. The roles of nitric oxide and interleukin-8 in the apoptosis of neutrophils are discussed.

Adolescent↗
PubMed1997

Enhancement of interleukin-1 alpha mediated autocrine growth of cultured human keratinocytes by sho-saiko-to.

We investigated the effects of Sho-saiko-to, the most commonly used herbal medicine in Japan, on the production of interleukin (IL)-1 alpha by cultured human epidermal keratinocytes. IL-1 alpha production was significantly promoted by treatment with 100 or 500 micrograms/ml Sho-saiko-to for 24 or 48 hr. Expression of IL-1 alpha receptors was the most markedly upregulated after treatment with 500 micrograms/ml Sho-saiko-to for 24 hr and with 100 or 500 micrograms/ml for 48 hr; these cells showed the characteristics of multilayered differentiated keratinocytes. The presence of an anti-IL-1 alpha antibody during the treatment with 500 micrograms/ml of Sho-saiko-to for 24 or 48 hr or with 100 micrograms/ml for 48 hr significantly down-regulated the synthesis by the keratinocytes and induced damages in them. Keratinocytes treated with Sho-saiko-to might produce IL-1 alpha and express IL-1 alpha receptors. IL-1 alpha may regulate the proliferation and differentiation of keratinocytes after Sho-saiko-to treatment. These findings suggest that Sho-saiko-to enhances the autocrine growth mediated by IL-1 alpha.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1996

Selective increase in astrocytic elements in the rat dentate gyrus after chronic toluene exposure studied by GFAP immunocytochemistry and electron microscopy.

Using glial fibrillary acidic protein (GFAP) immunohistochemistry, and electron microscopy, we examined changes in the features of astrocytes in the dentate gyrus of the hippocampal formation after high-dose chronic toluene inhalation (2000 ppm, 4 h/day) for 1 month. In toluene-treated rats, the numbers of GFAP-immunoreactive (IR) astrocytes were not changed, whereas the area and intensity of GFAP-IR processes were increased markedly in the dentate gyrus. In addition, dense, thick and highly-stained GFAP-IR processes appeared entering into the granular cell layer, compared with those of controls. At the electron microscopic level, numerous astrocytic processes with high electron density intervened between the granular cells. These results suggest that high-dose of chronic toluene exposure induces morphological changes in astrocytes in the dentate gyrus of the hippocampal formation.

Administration, Inhalation↗
PubMed1996

Relationship of human liver dihydrodiol dehydrogenases to hepatic bile-acid-binding protein and an oxidoreductase of human colon cells.

We previously isolated three monomeric dihydrodiol dehydrogenases, DD1, DD2 and DD4, from human liver, and cloned a cDNA (C9) thought to encode DD2, which is identical with those for human bile-acid-binding protein and an oxidoreductase of human colon carcinoma HT29 cells. In the present study we have provided evidence that the C9 cDNA clone encodes DD1, not DD2. A recombinant enzyme expressed from the cDNA in a bacterial system was purified, and its catalytic properties, bile-acid-binding ability and primary sequence were compared with those of the hepatic dihydrodiol dehydrogenases. The results show that DD1 encoded by C9 possesses prostaglandin F synthase activity but low affinity for lithocholic acid, whereas DD2, showing differences of six amino acid residues from the DD1 sequence, exhibited high-affinity binding for the bile acid. Refined relationship between dihydrodiol dehydrogenases and their related proteins of human tissues is proposed.

Amino Acid Sequence↗
PubMed1996

Activation of human liver 3 alpha-hydroxysteroid dehydrogenase by sulphobromophthalein.

Human liver contains at least two isoenzymes (DD2 and DD4) of 3 alpha-hydroxysteroid/dihydrodiol dehydrogenase. The NADP(H)-linked oxidoreductase activities of DD4 were activated more than 4-fold by sulphobromophthalein at concentrations above 20 microM and under physiological pH conditions. Sulphobromophthalein did not stimulate the activities of DD2 and human liver aldehyde reductase, which are functionally and/or structurally related to DD4. No stimulatory effect on the activity of DD4 was observed with other organic anions such as Indocyanine Green, haematin and Rose Bengal. The binding of sulphobromophthalein to DD4 was instantaneous and reversible, and was detected by fluorescence and ultrafiltration assays. The activation by sulphobromophthalein decreased the activation energy in the dehydrogenation reaction for the enzyme, and increased both kcat, and Km values for the coenzymes and substrates. Kinetic analyses with respect to concentrations of NADP+ and (S)-(+)-indan-1-ol indicated that sulphobromophthalein was a non-essential activator of mixed type showing a dissociation constant of 2.6 microM. Thus, the human 3 alpha-hydroxysteroid dehydrogenase isoenzyme has a binding site specific to sulphobromophthalein, and the hepatic metabolism mediated by this isoenzyme may be influenced when this drug is administered.

3-Hydroxysteroid Dehydrogenases↗
PubMed1996

Apoptotic cell death in formation of vesicular skin lesions in patients with acquired zinc deficiency.

We investigated the role of apoptotic cell death in the production of skin lesions in patients with acquired zinc deficiency. Nuclear condensation of keratinocytes was observed at an early stage of skin lesions in patients with zinc deficiency, especially around vesicular lesions. Nuclei of keratinocytes in perivesicular lesions of the epidermis were positively stained by the nick-end labeling specific for fragmented DNA. Lewis Y antigen was also expressed on perivesicular lesions. On the other hand, there were no such positively stained cells in hyperkeratotic skin lesions of the patients. Therefore, it was suggested that apoptotic cell death might play a role in the formation of vesicular skin lesions in patients with zinc deficiency, but not in the formation of hyperkeratotic skin lesions.

Adult↗
PubMed1996

Apoptotic cell death in the response of D-galactosamine-sensitized mice to lipopolysaccharide as an experimental endotoxic shock model.

The apoptotic cell death induced in D-galactosamine-sensitized mice by administration of lipopolysaccharide was characterized. Administration of lipopolysaccharide caused apoptotic cell death in livers of D-galactosamine-sensitized mice. Apoptotic cells were also detected in the kidney, thymus, spleen, and lymph node. Severe hepatic apoptosis in D-galactosamine-sensitized mice was reproduced by transfer of the sera from mice injected with D-galactosamine and lipopolysaccharide. The hepatocyte apoptosis induced by lipopolysaccharide was completely prevented by an anti-tumor necrosis factor alpha antibody but not by an anti-gamma interferon antibody. Administration of recombinant tumor necrosis factor into D-galactosamine-sensitized mice also caused hepatocyte apoptosis. Lipopolysaccharide-induced hepatocyte apoptosis in D-galactosamine-sensitized mice did not seem to be mediated by Fas antigen. It was suggested that lipopolysaccharide- induced hepatic injury and failure in D-galactosamine-sensitized mice was due to the apoptotic cell death of hepatocytes caused by tumor necrosis factor alpha released in the circulation.

Animals↗