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Biomedical subjects

Masahiro Goto

Publications and source records attributed to Masahiro Goto.

At least 19 recordsLinked to original sources
PubMed2006

Extractive solubilization, structural change, and functional conversion of cytochrome c in ionic liquids via crown ether complexation.

This article reports on the extraction behavior of heme proteins from an aqueous phase into ionic liquids (ILs) with dicyclohexano-18-crown-6 (DCH18C6), and the structure-function relationship of cytochrome c (Cyt-c) dissolved in ILs. We have found that DCH18C6 enables transfer of Lys-rich proteins into ILs via supramolecular complexation. The hydrophobicity and functional groups of ILs have a great influence on protein partitioning, and a hydroxyl group-containing IL with DCH18C6 is capable of the quantitative partitioning of Cyt-c. On the other hand, protein transfer using conventional organic solvents is negligibly small. UV-visible, CD, and resonance Raman spectroscopic characterizations indicate that the sixth ligand Met 80 in the heme group of the Cyt-c-DCH18C6 complex in IL is replaced by other amino acid residues of the peptide chain and that a non-natural, six-coordinate, low-spin ferric heme structure is induced in IL. Solubilization of Cyt-c in IL causes the environmental change of the heme vicinity of Cyt-c, which triggers the functional conversion of Cyt-c from an electron-transfer protein to peroxidase. The Cyt-c-DCH18C6 complex in IL provides remarkably high peroxidase activity compared with native Cyt-c, because of enhancement of the affinity for H2O2.

Catalysis↗
PubMed2006

Inhibitiory effects of gold(III) ions on ribonuclease and deoxyribonuclease.

Inhibitory effects of gold(III) ions (Au(III)) on ribonuclease A (RNase A) and deoxyribonuclease I (DNase I) were investigated at neutral pH. RNase A was completely inhibited by 3 molar equivalents of Au(III) ions. DNase I was inhibited by 10 molar equivalents of Au(III) ions. Stoichiometric analyses suggest that Au(III) ions were coordinated to RNase A molecules. The Au(III)-inhibited RNase A and DNase I were renatured to exhibit 80% and 60% of their intrinsic activity, when the bound Au(III) ions were eliminated from the nucleases by addition of thiourea, which forms a strong complex with gold ions. This suggests that RNase A and DNase I were not oxidized to lose their activity, but reversibly complexed with Au(III) ions to lose their activity. Au(III) ions were probably considered to be bound to histidine and methionine residues in the nucleases, resulting in the inhibition of their activity. CD spectra revealed that the Au(III)-induced inhibition caused a conformational change in RNase A molecules and that the addition of thiourea induced refolding of the Au(III)-inhibited RNase A.

Circular Dichroism↗
PubMed2006

Homogeneous enzymatic reactions in ionic liquids with poly(ethylene glycol)-modified subtilisin.

Subtilisin Carlsberg was covalently modified with comb-shaped poly(ethylene glycol) (PM13). PM13-modified subtilisin (PM13-Sub) was readily solubilized in three different ionic liquids (ILs), i.e., [Emim][Tf2N], [C2OC1mim][Tf2N] and [C2OHmim][Tf2N]. Analysis of homogeneous enzymatic reactions in the ILs revealed that PM13-Sub exhibited excellent catalytic performance while the native enzyme suspended in ILs showed no activity. Hydrophobicity of ILs slightly affected enzyme activity, and the relatively hydrophobic IL [Emim][Tf2N] was the preferred medium for enzymatic reactions, similar to enzymatic reactions in conventional organic solvents. Enzyme activity was much higher in [Emim][Tf2N] than in conventional organic solvents, and excellent activity was associated with unique properties of ILs such as hydrophobicity and high polarity. Furthermore, PM13-Sub showed good stability in [Emim][Tf2N], and maintained 80% of its initial activity after 60 h.

Bacillus subtilis↗
PubMed2006

Increasing the catalytic performance of a whole cell biocatalyst harboring a cytochrome p450cam system by stabilization of an electron transfer component.

Catalytic activity of a recombinant Escherichia coli whole cell biocatalyst harboring a cytochrome P450cam monooxygenase system from Pseudomonas putida coupled with enzymatic co-factor regeneration was investigated. About 0.7 micromol camphor was hydroxylated per mg dry cells at 4 degrees C in 50 mM Tris/HCl buffer (pH 7.4) when utilizing a stable putidaredoxin (Pdx) mutant, C73S/C85S-Pdx (Cys73Ser, Cys85Ser double mutant), instead of wild-type Pdx, which was about two-fold improvement in the substrate conversion. Ten-micromole camphor was completely hydroxylated at 20 degrees C in 6 h by 15 mg dry cell weight of whole cell biocatalyst including C73S/C85S-Pdx. Thus, modulation of protein-protein interaction in multicomponent enzymatic catalysis in whole cells is important.

Camphor↗
PubMed2006

Electrochemical extraction of proteins by reverse micelle formation.

The transfer of proteins by the anionic surfactant bis(2-ethylhexyl) sulfosuccinate (AOT) at a polarized 1,2-dichloroethane/water (DCE/W) interface was investigated by means of ion-transfer voltammetry. When the tetrapentylammonium salt of AOT was added to the DCE phase, the facilitated transfer of certain proteins, including cytochrome c (Cyt c), ribonuclease A, and protamine, could be controlled electrochemically, and a well-defined anodic wave for the transfer was obtained. At low pH values (e.g., pH 3.4), the anodic wave was usually well-separated from the wave for the formation of protein-free (i.e., unfilled) reverse micelles. The anodic wave for the protein transfer was analyzed by applying the theory for facilitated transfer of ions by charged ligands and then supplying information regarding the number of AOT anions reacting with one protein molecule and the total charge carried by the protein transfer. However, controlled-potential electrolyses performed for the transfer of Cyt c, which is red, revealed that the protein-AOT complexes were unstable in DCE and liable to aggregate at the interface when the pH of the W phase was 3.4. At pH 7.0, when formation of unfilled reverse micelles occurred simultaneously, the protein-AOT complexes appeared to be stabilized, probably via fusion with unfilled reverse micelles.

Animals↗
PubMed2006

Masking oligonucleotides improve sensitivity of mutation detection based on guanine quenching.

Guanine quenching of a fluorescence-labeled DNA probe is a powerful tool for detecting a mutation in a targeted site of a DNA strand. However, a different guanine adjacent to a targeted site can interfere with detection of a point mutation, resulting in unsatisfactory sensitivity. In the current study, we developed a simple method to improve sensitivity of the guanine quenching method using a masking DNA oligonucleotide. The simple addition of a masking DNA oligonucleotide was found to mask the interference of a different guanine in a target oligonucleotide on fluorescence and to enhance difference in the quenching ratio between wild-type and mutant oligonucleotides. Based on this strategy, we succeeded in discriminating various mutations from the wild-type YMDD motif of the hepatitis B virus DNA polymerase gene using guanine quenching with a masking oligonucleotide.

DNA Mutational Analysis↗
PubMed2006

Oral delivery of diclofenac sodium using a novel solid-in-oil suspension.

The present work reports on a new pharmaceutical formulation for oral delivery of diclofenac sodium (DFNa), a non-steroidal anti-inflammatory drug (NSAID). Although DFNa itself is water-soluble at neutral pH, it was readily suspended in soybean oil via complex formation with an edible lipophilic surfactant and a matrix protein. The resulting solid-in-oil (S/O) suspension containing stably encapsulated DFNa in an oil phase markedly reduced the risks for gastrointestinal ulcers upon oral administration even at the LD(50) level in rats (ca. 50 mg/kg DFNa). In addition, plasma concentration of DFNa upon administration of an S/O suspension was comparable with that of the aqueous counterpart at the same DFNa dose. These results indicate the potential use of S/O suspensions as novel oil-based pharmaceutical formulations for oral delivery of water-soluble drugs without causing severe mucitis.

Administration, Oral↗
PubMed2006

A recombinant Escherichia coli whole cell biocatalyst harboring a cytochrome P450cam monooxygenase system coupled with enzymatic cofactor regeneration.

A cytochrome P450cam monooxygenase (P450cam) system from the soil bacterium Pseudomonas putida requires electron transfer among three different proteins and a cofactor, nicotinamide adenine dinucleotide (NADH), for oxygenation of its natural substrate, camphor. Herein, we report a facile way to significantly enhance the catalytic efficiency of the P450cam system by the coupling of its native electron transfer system with enzymatic NADH regeneration catalyzed by glycerol dehydrogenase (GLD) in Escherichia coli whole cell biocatalysts. Recombinant E. coli harboring the P450cam system, but lacking GLD, exhibited little activity for camphor hydroxylation. In contrast, coexpression of GLD with the proteinaceous electron transfer components of P450cam resulted in about tenfold improvement in the substrate conversion, implying that the whole cell biocatalyst utilized molecular oxygen, endogenous NADH, and glycerol in the cell for catalysis. The addition of glycerol to the reaction media further promoted camphor hydroxylation, suggesting that exogenous glycerol is also available for GLD in the host cell and actively participates in the catalytic cycle. These results clearly show the utility of GLD towards functional reconstruction of the native P450cam system. The present approach may also be useful for E. coli whole cell biocatalysts with the other NADH-dependent oxygenases and oxidoreductases.

Camphor↗
PubMed2006

Crown ether-mediated extraction and functional conversion of cytochrome C in ionic liquids.

We report that a macrocyclic ligand enables transfer of a protein from an aqueous phase to ionic liquids. The extraction behavior of heme protein cytochrome c (Cyt-c) from an aqueous phase into ionic liquids was investigated with crown ethers. A hydroxyl-group-containing ionic liquid with dicyclohexano-18-crown-6 was found to be capable of quantitative partitioning of Cyt-c, whereas the protein transfer using conventional organic solvents was negligibly small. Furthermore, we clarified that Cyt-c solubilized in ionic liquids caused a structural transformation of Cyt-c, which triggers its functional conversion from an electron-transfer protein to peroxidase.

Animals↗
PubMed2006

Preventing elderly suicide through primary care by community-based screening for depression in rural Japan.

Depression is a major cause of suicide among the elderly. Few previous community-based interventions against depression have reduced the suicide rate. This study aims to evaluate outcomes of a community-based program to prevent suicide among the elderly using a quasi-experimental design with a neighboring reference group. The program, including depression screening with follow-up and health education through primary care and public health nursing, was implemented for 10 years in Matsudai town, a rural area of Japan (population 6,015; suicide rate per 10(5) [65-year-olds] for males 290.6, and for females 361.3). Changes in the suicide risk were estimated by the incidence rate ratio (IRR). The female risk of completing suicide in the intervention area was reduced by 70% (age-adjusted IRR: 0.30; 95% CI: 0.14-0.67), while there was no change in the risk for males in the intervention area nor for males or females in the reference area (Kawanishi town: population 9,425; elderly suicide rate for males 212.2, females 151.9). A ratio of the female IRR in the intervention area to that in its prefecture was also estimated at 0.45 (95% CI: 0.19-0.97), showing that the reduction of suicide risk in the intervention area was greater than the historical trend. A community intervention against suicide using management of depression with nonpsychiatric, primary health care would be effective for elderly females, but not males.

Aged↗
PubMed2006

Outcomes of community-based screening for depression and suicide prevention among Japanese elders.

PURPOSE: In this study we evaluate outcomes of a community-based program to prevent suicide among elderly individuals aged 65 and older. DESIGN AND METHODS: We used a quasi-experimental design with intervention and referent municipalities. The program included a 7-year implementation of depression screening with follow-up by general practitioners and a 10-year implementation of public education conducted in Yasuzuka (population 4,940; elderly suicide rate for women, 275/100,000; for men, 323/100,000). We estimated changes in the risk of completing suicide before and after the 10-year implementation by the incidence-rate ratio (IRR). RESULTS: The risk for women in the intervention area was reduced by 64% (age-adjusted IRR=0.36; 95% confidence interval=0.14-0.93), whereas there was no significant change in the risk for men in the intervention area and either men or women in the referent municipalities. A ratio of the IRR for women aged 65 to 74 in the intervention area to that in its prefecture was estimated at 0.23 (90% confidence interval=0.05-0.99), showing that the risk reduction was greater than the secular trend. IMPLICATIONS: The management of depression by use of community resources involving public health and primary care physicians is effective in the prevention of suicide for elderly women but uncertain for men.

Aged↗
PubMed2006

Countertransference to psychiatric patients in a clinical setting: development of the Feeling Checklist-Japanese version.

Countertransference is an important dimension of the therapeutic alliance between care providers and patients. The Feeling Checklist (FC) is a self-report questionnaire for the assessment of countertransference by hospital staff toward patients. The FC was translated from English into Japanese and its factor structure, reliability, and validity in the Japanese version (FC-J) were examined. A total of 281 Japanese psychiatric nurses were tested with the FC-J. All nurses were primarily involved in provision of psychiatric care. Principal-component factor analysis with varimax rotation was performed to identify the potential components of the FC-J. In a factor analysis of the FC-J, seven factors were extracted. The five subscales that were determined and labeled included Reject, Distance, Helpfulness, Closeness, and Involvement, which collectively accounted for 56.0% of the variance. Cronbach's alpha, a measure of internal consistency, for individual subscales was 0.833 for Reject, 0.763 for Distance, 0.768 for Helpfulness, 0.617 for Closeness, and 0.663 for Involvement. Notably, there was a significant correlation between the FC-J and the Nurse Attitude Scale (P < 0.0001). Moreover, one-way anova was performed with each FC-J subscale to examine differences among psychiatric diagnoses in the study sample. A significant difference was found for Involvement (P < 0.001), with the total score on Involvement being the highest in the personality disorder group. These results are considered to verify the reliability and validity of the FC-J as a scale to measure countertransference among Japanese care providers. The use of this scale allows individual care providers to recognize and be cognizant of their own countertransference objectively and thereby contributes to improve the relationship between patients and care providers.

Adult↗
PubMed2006

In humans, early cortisol biosynthesis provides a mechanism to safeguard female sexual development.

In humans, sexual differentiation of the external genitalia is established at 7-12 weeks post conception (wpc). During this period, maintaining the appropriate intrauterine hormone environment is critical. In contrast to other species, this regulation extends to the human fetal adrenal cortex, as evidenced by the virilization that is associated with various forms of congenital adrenal hyperplasia. The mechanism underlying these clinical findings has remained elusive. Here we show that the human fetal adrenal cortex synthesized cortisol much earlier than previously documented, an effect associated with transient expression of the orphan nuclear receptor nerve growth factor IB-like (NGFI-B) and its regulatory target, the steroidogenic enzyme type 2 3beta-hydroxysteroid dehydrogenase (HSD3B2). This cortisol biosynthesis was maximal at 8-9 wpc under the regulation of ACTH. Negative feedback was apparent at the anterior pituitary corticotrophs. ACTH also stimulated the adrenal gland to secrete androstenedione and testosterone. In concert, these data promote a distinctive mechanism for normal human development whereby cortisol production, determined by transient NGFI-B and HSD3B2 expression, provides feedback at the anterior pituitary to modulate androgen biosynthesis and safeguard normal female sexual differentiation.

3-Hydroxysteroid Dehydrogenases↗
PubMed2006

[Principles of managing chemotherapy-induced nausea and vomiting].

Chemotherapy-induced nausea and vomiting (emesis) can significantly affect a patient's quality of life, leading to poor compliance with further chemotherapy treatment. For patients treated with emetogenic chemotherapy, it is very important to prevent nausea and vomiting completely. The incidence and severity of nausea and/or vomiting in patients receiving chemotherapy are affected by numerous factors, including: 1) the specific chemotherapeutic agents used; 2) their dosage; 3) the schedule and route of administration; and 4) individual patient variability. Approximately 70 to 80% of all cancer patients receiving chemotherapy experience emesis, whereas 10% to 44% experience anticipatory emesis. The following general principles are recommended. 1) A 5-HT3 receptor antagonist should be administered prior to each day's 1st dose of moderately or highly emetogenic chemotherapy. 2) Dexamethasone should be administered once daily either orally or intravenously for every day of moderately or highly-emetogenic chemotherapy and for 2-3 days after chemotherapy for regimens that are likely to cause significant delayed-emesis. 3) The most effective way to treat anticipatory nausea and/or vomiting is to prevent it by using optimal antiemetic therapy during every cycle of treatment.

Antiemetics↗
PubMed2006

[A case of gastric cancer with multiple liver metastases resistant to TS-1 responding to chemotherapy with paclitaxel plus doxifluridine].

A 74-year-old man was revealed to have type 3 gastric cancer with synchronous multiple liver metastases. Despite treatment with TS-1 (120 mg/body), an increase in tumor size was demonstrated by computer tomography and endoscopy. We tried a course of a combination chemotherapy consisting of paclitaxel (PTX) plus doxifluridine (5'-DFUR ) to reduce the tumor. 5'-DFUR (600 mg/m(2)) was administered day 1 to 14 followed by 7 days'rest as one course. PTX (80 mg/m(2)) was infused on days 1 and 8. After 5 courses, the tumor markers decreased markedly, and computer tomography and endoscopy revealed remarkable tumor reduction which was thought to show a partial response. After 13 courses we discontinued this chemotherapy, so increase of the tumor marker was remarkable. This case suggests that PTX/5'-DFUR protocol is effective for clinical management of gastric cancer resistant to TS-1.

Adenocarcinoma↗