Biomedical subjects

M Tomioka

Publications and source records attributed to M Tomioka.

At least 19 recordsLinked to original sources

PubMed2005

Tyrosinase induction and inactivation in normal cultured human melanocytes by endothelin-1.

Since endothelin was found to be expressed in epithelial cells as well as in vascular endothelial cells, the functional regulation of melanocytes with endothelin has been actively investigated. In particular, it has been suggested that endothelin may influence pigmentation and depigmentation, which are mediated by melanocytes. In the present study, we investigated the regulation of melanocyte function and tyrosinase expression by endothelin from the point of view of tyrosinase protein expression and enzyme activity. The influence of endothelins on melanocyte function was assessed. Melanocytes showed a dose-dependent increase in cell proliferation with the addition of endothelin-1. When the confluence of melanocytes was cultured with endothelin-1 for 72 h, tyrosinase activity in melanocytes was significantly and dose-dependently decreased. In contrast, there was no significant change with endothelin-3. However, tyrosinase protein expression of melanocytes was significantly and dose-dependently increased by endothelin-1, but endothelin-3 had no effect. Both the suppression of enzyme activity and the enhanced protein expression were regulated by the ETA receptor antagonist, BQ123. In view of these observations, we conclude that endothelin-1-induced tyrosinase is mediated by ETA receptors. However, the reason for the decrease in the specific activity of tyrosinase remains unknown, and our results suggest that another mechanism underlying the activation of tyrosinase is present in addition to the inductive action of endothelin-1 on tyrosinase.

Cell Proliferation↗

PubMed2004

Widespread crystalline inclusions affecting podocytes, tubular cells and interstitial histiocytes in the myeloma kidney.

Numerous crystalline inclusions were observed in glomerular and tubular epithelial cells in a 46-year-old female patient with multiple myeloma and renal dysfunction. On light microscopy, epithelial cells were filled with homogenous materials and were remarkably swollen. Infiltrations of histiocytes with expanded cytoplasm were also seen in the interstitium of the kidney and bone marrow. On electron microscopy, cytoplasmic inclusions had crystalline structure showing rhomboid and oval shapes. Immunofluorescence study revealed that these cells were positive for IgG-kappa. The combination chemotherapy followed by autologous stem cell transplantation led to a partial resolution of her renal dysfunction, continued by a slight reduction in the number of crystalline-containing podocytes at the second renal biopsy. Crystal inclusions in the kidney are rarely found and cause renal impairment in multiple myeloma.

Bone Marrow Cells↗

PubMed2001

A novel traceless resin-bound guanidinylating reagent for secondary amines to prepare N,N-disubstituted guanidines.

[reaction: see text]. We report the development of a solid support-linked guanidinylating reagent. This reagent consists of a urethane-protected triflyl guanidine attached to the resin via a carbamate linker. It allows for rapid synthesis of guanidines from a variety of amines. It provides access to N-alkyl/aryl- or N,N-dialkylguanidines under mild conditions. Cleavage with 50% TFA produces target molecules in high yields and purity. The ability to guanidinylate secondary amines is a significant feature of this guanidinylating reagent.

Amines↗

PubMed2001

Alpha-tocopherol affects the urinary and biliary excretion of 2,7,8-trimethyl-2 (2'-carboxyethyl)-6-hydroxychroman, gamma-tocopherol metabolite, in rats.

In this study, we investigated a change in the excretory content of 2,7,8-trimethyl-2(2'-carboxyethyl)-6-hydroxychroman (gamma-CEHC), a gamma-tocopherol (gamma-Toc) metabolite, in rat urine and bile by using a new high-performance liquid chromatography-electrochemical detection (HPLC-ECD) method. In this determination, CEHC [alpha- and gamma-CEHC, where alpha-CEHC = 2,5,7,8-tetramethyl-2(2'-carboxyethyl)-6-hydroxychroman] in the biological specimens were treated with 3 N methanolic HCl to hydrolyze conjugates and to promote esterification. The methylated samples were extracted by n-hexane/water (1:2). The analyses of the methyl esters of alpha-CEHC and gamma-CEHC were performed by an HPLC-ECD using an ODS-3 column at 35 degrees C. The mobile phase was acetonitrile/water (45:55, vol/vol) containing 50 mM sodium perchlorate. After rat urine and bile samples, respectively, were methylated as described above, methylated biliary metabolites were identified by liquid chromatography-mass spectrometry as methyl esters of gamma-CEHC. Furthermore, we examined the differences in the excretion of gamma-CEHC between rat urine and bile after an oral administration of gamma-Toc or alpha- + gamma-Toc by the above HPLC method. In the gamma-Toc group, each vitamin E-deficient rat was given 0.5 mL of a stripped corn oil preparation containing 10 mg of gamma-Toc. In the alpha- + gamma-Toc group, the rat was given 10 mg of alpha-Toc and 10 mg of gamma-Toc. The content of gamma-CEHC in rat urine from the alpha- + gamma-Toc group was increased more in comparison to the gamma-Toc group at 18-36 h after oral administration. Moreover, the content of gamma-CEHC in rat bile in the alpha- + gamma-Toc group was increased more in comparison to the gamma-Toc group at 6-18 h after oral administration. Therefore, we have suggested that gamma-CEHC was shifted mainly to urinary excretion after gamma-CEHC had been excreted into the bile. Furthermore, we assume that alpha-Toc may affect the metabolism of gamma-Toc to gamma-CEHC in the body.

Animals↗

PubMed2001

[Troubles inherent to long-term home parenteral nutrition (HPN) and the use of technologies to improve communication between medical institutions and patients].

The continuous advance of technology has contributed to the improvement of the quality of life of patients under long-term home parenteral nutrition (HPN). But the longer the patient stays home, the higher the risk of many kinds of troubles. We designed an HPN system in June 1999, which uses E-mail for patients and to contact with each other (including the patient's family) and to prevent troubles from worsening. We describe the case of a patient which shows the efficacy and usefulness of our system, which makes use of the Internet, video mail, voice mail and electric medical records.

Aged↗

PubMed2000

Molecular cloning and expression of aminopeptidase A isoforms from rat hippocampus.

The full-length cDNA encoding aminopeptidase A (APAL) was cloned from a rat hippocampus cDNA library. A short variant aminopeptidase A (APAS), produced by deletion, was also cloned. In the case of APAL, the longest open reading frame encodes 945 amino acid residues with a calculated molecular mass of 108 kDa, and the deduced amino acid sequence shows 76, 86 and 78% identity with its human, murine and porcine counterparts, respectively. Rat aminopeptidase A mRNAs were detected in the kidney, liver, heart and brain by Northern blot analysis. When overexpressed in COS-1 cells, APAL shows apparent aminopeptidase A activity, whereas APAS does not.

Amino Acid Sequence↗

PubMed2000

Impaired Kupffer cell function and effect of immunotherapy in obstructive jaundice.

BACKGROUND: Obstructive jaundice is frequently associated with septic complications. This study examined the influence of biliary obstruction on bacterial clearance and translocation. The study focused on the phagocytic and killing activities of Kupffer cells and the preventive effect on bacterial translocation of OK-432, which is a hemolytic streptococcal preparation developed as a biological response modifier. METHODS: To study the mechanism of sepsis in obstructive jaundice, two groups of Wistar rats were examined: rats subjected to common bile duct ligation (CBDL) and rats subjected to a sham operation. Bacterial clearance, organ distribution, hepatic blood flow, and phagocytic function of Kupffer cells were examined. To evaluate the effect of OK-432 on bacterial translocation, rats were divided into three groups: sham operation + phosphate-buffered saline (PBS), CBDL + PBS, and CBDL + OK-432. RESULTS: In this study, clearance of Escherichia coli. from the peripheral blood in CBDL rats was decreased significantly compared with that in sham-operated rats. Significant decreases in E.coli trapped in the liver and in hepatic blood flow were observed in CBDL rats compared with sham-operated rats. Phagocytic activity and superoxide production of Kupffer cells isolated from CBDL rats were significantly lower than in sham-operated rats. The incidence of bacterial translocation in CBDL rats was increased significantly, and oral administration of OK-432 prevented it. CONCLUSION: The results suggest that susceptibility to infection in obstructive jaundice is due to impaired phagocytic function of Kupffer cells. Furthermore, obstructive jaundice promotes bacterial translocation, and OK-432 may be useful in preventing this translocation.

Animals↗

PubMed2000

Interaction of peptides derived from RecA with single-stranded oligonucleotides containing 5-formyl-2'-deoxyuridine.

We report the first example of chemical cross-linking of 5-formyl-2'-deoxyuridine containing oligonucleotides with oligopeptides through a Schiff base formation. Twenty amino acid residue peptides investigated here were derived from the DNA binding site of RecA protein. We have demonstrated that the lysine residue placed at the 6th or 8th position from the N-terminus of the peptide directly contacts with DNA.

Amino Acid Sequence↗

PubMed1999

Surviving and proliferating faculty of fibroblasts cultured under no-serum and poor nutritional conditions. The basic study on hybridation of cultured cells with an artificial matrix.

BACKGROUND: In this study, we measured survival periods of fibroblasts cultured under conditions providing minimal nutrition. This investigation aims to develop the high affinity hybrid artificial organs on tissues or organs finally. METHODS: Dermal fibroblasts were inoculated on 96-well multiplate according to routine technique. The medium of these cells maintained for 24 hours replaced the new DME medium containing 10% FBS (group 1) or without FBS (group 2) and then cultured for 10 days without medium change. The surviving cell numbers were measured using MTS assay. RESULTS: Surviving cell numbers of both groups decreased progressively during the 10-day assay period. Overall 25-40% of the fibroblasts survived for at least 10 days. It decreased significantly, however, in group 2 from day 2 through day 4 as compared to group 1. In contrast, the cell number decreased in group 1 to a greater extent than in group 2 after day 6. When the cells that survived until day 10 were then cultured with fresh DME medium containing 10% FBS for 3 more days, the cell numbers returned to 50-100% of the initial level CONCLUSIONS: These results suggest that fibroblasts cell function is maintained under poor nutritional conditions, i.e., without serum, possibly via an autocrine or paracrine mechanism. These data could contribute much to the research of hybrid artificial organs, including an artificial trachea, in which hybridization of cultured cells with artificial matrices remains to be a basic process, and has to serve in bloodless postimplantation period.

Cell Count↗

PubMed1998

Changes in endothelin-1, 6-keto-PG-F1 alpha, and TX-B2 in random pattern flaps.

In this study we investigated kinetic changes in the ratio of endothelin-1 (ET-1) and eicosanoids (6-keto-PG-F1 alpha TX-B2) in 20 x 60 mm random pattern flaps from rats. The ET-1 content of regions A (20 mm from the peripheral end) and B (20-40 mm) 6 h after surgery tended to decrease slightly compared to the ET-1 content immediately after surgery. The ET-1 content of region C (20 mm from the flap base) 6 h postoperatively increased significantly compared to that immediately after surgery. The ET-1 content of region C 6 h after surgery was significantly higher compared to that of regions A and B, which were obtained simultaneously. The ratios of eicosanoids in the three regions 6 h after surgery were significantly lower than those immediately after operation. However, the ratio in region A was higher than that in region C, showing that there was a difference in distribution in the flap between ET-1 and eicosanoids. The administration of an ETA receptor antagonist, FR-139317, extended the survival length of the flap. These results suggest that ET-1 can regulate the microcirculation in a flap directly and/or indirectly.

6-Ketoprostaglandin F1 alpha↗

PubMed1997

Differential effects of granulocyte/macrophage colony-stimulating factor (GM-CSF) in enhancing macrophage resistance to Legionella pneumophila vs Candida albicans.

It has been reported that granulocyte/macrophage colony-stimulating factor (GM-CSF), one of the hemopoietic growth factors which regulates the function of phagocytic cells, is a potent activator of cultured macrophages and induces antimicrobial activities as well as differentiation of precursor cells. In this study, we examined the ability of recombinant murine GM-CSF to activate mouse peritoneal macrophages to restrict the growth of two different microorganisms, Candida albicans and Legionella pneumophila, both of which are important opportunistic pathogens in an immunocompromised host. Treatment of thioglycollate-elicited BDF1 mouse macrophages with GM-CSF for 24 hr enhanced the anti-C. albicans activity of the macrophages in terms of inhibiting growth of the fungi. Reactive oxygen (H2O2) and IL-1 production by the macrophages were also enhanced by treatment with GM-CSF. However, no enhancement of anti-L. pneumophila activity of macrophages obtained from either susceptible A/J or resistant BDF1 mice to L. pneumophila infection after treatment with up to 1000 units/ml GM-CSF was observed under the same conditions. When the treatment time was extended to 72 hr. GM-CSF was still unable to induce anti-L. pneumophila activity. As a control study, treatment with recombinant IFN-gamma enhanced both anti-Candida and anti-Legionella activity in cultured macrophages under the same conditions used in the GM-CSF study. Measurement of cellular iron content revealed the low iron content in IFN-gamma-treated macrophages, but no decrease of iron in GM-CSF-treated macrophages compared with the control group, indicating a possible involvement of iron as a key factor in anti-L. pneumophila activity. Thus, the results of the study show that GM-CSF activation of elicited peritoneal macrophages is selective with regard to the type of antimicrobial activity induced.

Animals↗

PubMed1997

Physiological roles of endothelium-derived nitric oxide in the epigastric island flaps of rabbits.

Nitric oxide (NO), identified as the mediator of endothelium-dependent relaxation of vascular smooth muscle, is known to cause a number of inflammatory conditions, especially in ischemia/reperfusion injury. This experimental study, using a rabbit epigastric island flap, was designed to investigate whether skin flap ischemia followed by reperfusion-influenced serum NO and c-GMP concentrations in the flap. In addition, we also investigated the premedicated effects of the NO synthase inhibitor and heparin on serum NO and c-GMP concentrations in skin flap ischemia/reperfusion. Serum NO concentration after 15, 30, 45, and 60 minutes of ischemia followed by reperfusion significantly increased compared with that in nonischemic control and elevated flaps. On the contrary, serum NO concentration was suppressed in L-NAME or aminoguanidine pretreated animals with ischemic group. Administration of heparin increased the serum NO concentration in elevated flaps, but suppressed it in ischemic flaps followed by reperfusion. The changes in serum c-GMP and NO concentrations were related in all of the experimental groups. These results suggest that NO may be derived from vascular endothelial cells and dilate peripheral vessels in compensation for ischemia.

Animals↗

PubMed1996

Apoptosis induction resulting from proteasome inhibition.

Proteases are known to be involved in the apoptotic pathway. We report here that benzyloxycarbonyl (Z)-Leu-Leu-leucinal(ZLLLal), a leupeptin analogue, can induce apoptosis in MOLT-4 and L5178Y cells. ZLLLal is a cell-permeant inhibitor of proteasome. Among the protease inhibitors tested, only calpain inhibitor I (acetyl-Leu-Leu-norleucinal) and ZLLLal caused a marked induction of apoptosis in MOLT-4 cells. In contrast Z-Leu-leucinal, a specific inhibitor of calpain, did not induce apoptosis. When MOLT-4 cells were incubated in the presence of ZLLLal, p53 accumulated in the cells. These results strongly suggest that inhibition of proteasome induces p53-dependent apoptosis and that proteasome can protect cell from apoptosis.

Animals↗

PubMed1996

Differential inhibition of calpain and proteasome activities by peptidyl aldehydes of di-leucine and tri-leucine.

To explore membrane-permeable synthetic inhibitors that discriminate between endogenous calpain and proteasome in cells, we examined the inhibition of profiles against calpain and proteasome in vitro and in vivo of peptidyl aldehydes possessing di-leucine and tri-leucine. The tripeptide aldehyde benzyloxycarbonyl-leucyl-leucinal (ZLLLal) strongly inhibited calpain and proteasome activities in vitro. The concentration required for 50% inhibition (IC50) of the casein-degrading activity of calpain was 1.25 microM, and the IC50s for the succinyl-leucyl-leucyl-valyl-tyrosine-4-methylcoumaryl-7-amide (Suc-LLVY-MCA)- and benzyloxycarbonyl-leucyl-leucyl-leucine-4-methylcoumaryl -7-amide (ZLLL-MCA)-degrading activities of proteasome were 850 and 100 nM, respectively. On the other hand, the synthetic dipeptide aldehyde benzyloxycarbonyl-leucyl-leucinal (ZLLal) strongly inhibited the casein degrading activity of calpain (IC50 1.20 microM), but the inhibition of proteasome was weak (IC50S for SucLLVY-MCA- and ZLLL-MCA-degrading activities were 120 and 110 microM, respectively). Thus, while calpain was inhibited by similar concentrations of ZLLal and ZLLLal, the inhibitory potencies of ZLLLal against the ZLLL-MCA- and Suc-LLVY-MCA-degrading activities in proteasome were 1,100 and 140 times stronger than those of ZLLal, respectively. To evaluate the effectiveness of these inhibitors on intracellular proteasome, the induction of neurite outgrowth in PC12 cells caused by proteasome inhibition was examined. ZLLLal and ZLLal initiated neurite outgrowth with optimal concentrations of 20 nM and 10 microM, respectively, again showing a big difference in the effective concentrations for the proteasome inhibition as in vitro. As for the effect on intracellular calpain, the concentration of ZLLLal and ZLLal required for the inhibition of the autolytic activation of calpain in rabbit erythrocytes were 100 and 100 microM or more, respectively. The almost equal inhibitory potencies of ZLLLal and ZLLal were in agreement with the inhibition of calpain in vitro. These differential effects of inhibitors against calpain and proteasome are potentially useful for identifying the functions of calpain and proteasome in cell physiology and pathology.

Animals↗

PubMed1995

LPS inhibits the intracellular growth of Legionella pneumophila in thioglycolate elicited murine peritoneal macrophages by iron-dependent, tryptophan-independent, oxygen-independent, and arginine-independent mechanisms.

Thioglycolate-elicited murine macrophages from genetically susceptible A/J mice activated with lipopolysaccharide (LPS) and infected with Legionella pneumophila in vitro evince marked inhibition of intracellular growth of this bacterium. The mechanism of inhibition by LPS-activated macrophages in terms of replication of this intracellular pathogen is unclear. LPS activation of murine macrophages induced a downshift in transferrin receptor (TfR) expression and reduction in cellular iron content, and this was correlated with augmented intracellular growth of Legionella in the cells. When LPS-stimulated macrophages were first saturated with iron, partial reversion of L. pneumophila growth restriction was observed. However, an excess of exogenous L-tryptophan (Trp) did not reverse this growth inhibition, nor did supplementation of the macrophage culture medium with both iron and Trp. The antilegionella activity of the macrophages induced by LPS activation was independent of reactive oxygen intermediates (ROI), since the scavengers catalase, superoxide dismutase, mannitol, and thiourea had no effect on growth restriction. Likewise, notwithstanding the ability of LPS-activated macrophages to synthesize reactive nitrogen intermediates (RNI), which was inhibited by L-arginine analogs NG-monomethyl-L-arginine and L-aminoguanidine), as well as by incubation in arginine-free medium, their ability to inhibit the intracellular replication of L. pneumophila was not affected. Thus, we conclude that LPS-activated macrophages inhibit the intracellular growth of L. pneumophila partially by iron-dependent, Trp-independent, and ROI- and RNI-independent mechanisms. We also suggest that additional unknown mechanisms are involved, since complete reversion was not obtained.

Animals↗

PubMed1994

[A new method of high-dose intraarterial chemotherapy of the pancreas using direct hemoperfusion (DHP) under portal venous isolation (PVI)].

Surgical resection for pancreatic cancer is severely limited by the extent of the disease at the time of diagnosis. Chemotherapy has been the treatment of choice for unresectable cases. We developed a new method of intraarterial chemotherapy for pancreatic body and tail cancers using direct hemoperfusion (DHP) under portal venous isolation (PVI). Adriamycin (ADR, 3 mg/kg) was infused into the splenic arteries of mongrel dogs for 5 min after clamping off blood flow to the stomach and the duodenum. In group A (n = 5), this was simply done, and in group B (n = 5) the portal venous blood was isolated by clamping at the porta hepatis and pumped through the DHP circuit to the jugular vein for 20 min from the start of drug infusion. The peak systemic level (microgram/ml) of group B (0.78 +/- 0.03) was significantly reduced by PVI.DHP as compared to that of group A (3.49 +/- 1.15, P < 0.01). The pancreatic tissue levels (microgram/g. tissue) 30 min after drug infusion of group A (61.2 +/- 13.4) were slightly lower than those in group B (88.9 +/- 27.8), although not statistically significant. However, tissue levels of group B in the liver (27.3 +/- 9.2) and heart (1.8 +/- 0.8) were significantly lower than those of group A (liver; 52.3 +/- 18.5, heart; 4.9 +/- 0.6, P < 0.05). In conclusion, PVI.DHP achieved a significant reduction in systemic drug exposure during intraarterial chemotherapy. Therefore, we consider that this system will allow dose escalation of ADR during intraarterial chemotherapy for pancreatic body and tail cancers.

Animals↗

PubMed1993

[Effect of combined use of CR1505 with UFT for the tumor growth of the subcutaneously transplanted pancreatic cancer in the Syrian golden hamsters].

We studied on the effect of combined use of CR1505 with UFT for the subcutaneously transplanted pancreatic cancer induced by BOP (N-nitrosobis (2-oxopropyl) amine) in the Syrian golden hamsters. The tumor growth in the group treated with both CR1505 and UFT was significantly inhibited compared with that in the group treated with only CR1505 or UFT. Labelling index judged by BrdU immunohistochemistry in the group with the combined use was significantly lower than that in the group with the single use. The differences of the body weights and blood analysis were not obscured in the both groups. Moreover, the concentrations of 5-FU and FT207 in tumors were not different between them. These results suggest that a new therapy of the combined use with CR1505 and UFT for the pancreatic cancer should be effective.

Animals↗

PubMed1992

Optimal site and amount of splenic tissue for autotransplantation.

Clinical and basic studies have documented a high susceptibility to pneumococcal infection in asplenic humans and animals. It has been suggested that autotransplantation of splenic tissue might be a method of providing host resistance when total splenectomy is necessary. However, the effect of splenic autograft has remained controversial. This study was performed to evaluate the most effective site and amount of splenic autograft using rats. Rats were divided into five groups for the purpose of determining the site of splenic autotransplantation: splenectomy, sham operation, implantation into the omental pouch, intraperitoneal implantation, and intramuscular implantation. For determining the amount for autotransplantation, the rats were divided into seven groups: splenectomy, sham operation, and implantations of 25, 50, 100, 200, or 300 mg of splenic tissue. All animals were challenged with Streptococcus pneumoniae type 6, 16 weeks after surgery. Howell-Jolly bodies appeared postsplenectomy, but disappeared in the implanted rats 16 weeks after the operation. Histologically, the implanted tissue was indistinguishable from that of a normal spleen. Pneumococcal clearance from the bloodstream and survival rate were significantly higher in rats implanted in the omental pouch as compared with splenectomized rats. Intraperitoneal and intramuscular implanted rats did not show a significant difference from the splenectomized rats. More than 50% of splenic tissue for autograft showed a significant increase in pneumococcal clearance and survival rate as compared with that of splenectomized rats. It was suggested that the most effective site of autotransplantation is the omental pouch and approximately 50% of the whole spleen would be necessary for prevention from sepsis.

Animals↗