Biomedical subjects

T Sagara

Publications and source records attributed to T Sagara.

At least 19 recordsLinked to original sources

PubMed2006

Effects of temperature gradient correction of carbon dioxide absorbent on carbon dioxide absorption.

BACKGROUND: The effects of temperature gradients in CO(2) absorbents on water content and CO(2) absorption are not clear. We constructed a novel temperature gradient correction (TGC) canister, and investigated the effects of temperature gradient correction on the water content and longevity (time to exhaustion) of CO(2) absorbent using a simulated anaesthesia circuit. METHODS: Experiments were divided into two groups according to the type of canister used: the TGC canister (n=6) or the conventional canister (n=6). One kilogram of fresh CO(2) absorbent was placed into the canister. The anaesthetic ventilator was connected to a 3 litre bag and 300 ml min(-1) of CO(2) was introduced. Oxygen (500 ml min(-1)) was used as fresh gas. The anaesthetic ventilator was set at a ventilatory frequency of 12 bpm, and tidal volume was adjusted to 700 ml. RESULTS: Before the experiment, the water content of the fresh CO(2) absorbent in the conventional canister and TGC canister was 16.1 (0.9)% and 15.7 (1.1)%, respectively. After the experiment, the water content of CO(2) absorbent near the upper outer rim of the canister increased to 32.4 (0.7)% in the conventional canister, but increased to only 20.6 (1.3)% in the TGC canister (P<0.01). The longevity of CO(2) absorbent in the conventional canister and TGC canister was 434 (9) min and 563 (13) min (P<0.01). CONCLUSIONS: Temperature gradient correction prevented a local excessive increase in water content and improved the longevity of CO(2) absorbent.

Absorption↗

PubMed2004

Successful case of adult ABO-incompatible liver transplantation: beneficial effects of intrahepatic artery infusion therapy: a case report.

BACKGROUND: In Japan ABO-incompatible liver transplantation has been done on >100 occasions up to 2003. However, <30% are cases involving adults. The difficultly of ABO-incompatible liver transplantation is associated with the high frequency of humoral rejection and local disseminated intravascular coagulation (DIC), leading to many postoperative complications. We report a successful case of adult ABO-incompatible liver transplantation with the use of an intrahepatic artery infusion. METHODS: A 36-year-old man with Wilson disease, underwent living donor liver transplantation from an ABO-incompatible donor. The immunosuppressive therapy included multiple perioperative plasmaphereses, splenectomy, and treatment with tacrolimus, methylprednisolone, and cyclophosphamide. The dose and blood level of tacrolimus were the same as in ABO-compatible cases. In addition to these therapies, we administered an intrahepatic arterial infusion with prostaglandin (PG) E1 alone. RESULTS: After perioperative plasmapheresis and cyclophosphamide, antidonor blood group antibody titers remained undiluted and without vascular complications throughout the postoperative course, but there was a tendency for bleeding that continued for 10 days after transplantation. On postoperative day 10, a reexploration was performed for intraabdominal bleeding. During another operation on postoperative day 59 a biloma was found and drained. The patient has now survived for 120 days after transplantation with normal liver function. CONCLUSIONS: Beneficial effect of intrahepatic artery infusion with PGE1 seems to be useful in adult ABO-incompatible liver transplantation.

ABO Blood-Group System↗

PubMed2002

Translational heating of D(2) molecules thermally desorbed from Si(100) and Ge(100) surfaces.

The translational energies of D(2) molecules thermally desorbed from the Si(100) and Ge(100) surfaces under a heating rate of 6 K/s have been measured. In contrast to the previous laser desorption study, results show a considerable translational heating; the observed translational temperature is about 3 times higher than the desorption temperature for both surfaces. This fact indicates that energy barriers for adsorption are present even in the desorption pathway. Detailed balance is applicable to the adsorption and desorption dynamics of hydrogen on the Si(100) surface.

Journal Article↗

PubMed2001

Molecular bilayer-based superstructures of a fullerene-carrying ammonium amphiphile: structure and electrochemistry.

The synthesis of a water-soluble C60-carrying single-chain ammonium amphiphile, 10- (N-methyl-2-fulleropyrrolidyl)decyltrimethylammonium bromide (1) as well as the characterization of aqueous solutions and cast films of 1 are described. X-ray diffraction study suggests that cast films of 1 form a multilayer structure based on biomembrane-like molecular bilayers. Electron microscopy has revealed that 1 produces both fibrous and disk-like aggregates with 10-12 nm of thickness through self-organization of 1 in aqueous solution. Differential scanning calorimetry, dynamic light scattering, FTIR, and UV-visible absorption studies were also carried out to characterize aqueous solutions and cast films of 1. Electrochemistry for an aqueous solution and for cast films of just 1 and 1 incorporated in lipid films on electrodes was conducted. It was found that films of just 1 and of 1/lipid cast on electrodes showed electron transfer reactions leading to the generation of the fullerene dianion or trianion. In contrast, electrochemistry of aqueous solution of 1 at a bare electrode gives a cathodic current near -0.5 to -0.6 V against SCE; however, an anodic current for the solution did not appear.

Carbon↗

PubMed2001

Increased matrix metalloproteinases 1, 2, and 3 in the monkey uveoscleral outflow pathway after topical prostaglandin F(2 alpha)-isopropyl ester treatment.

OBJECTIVE: To investigate the effects of topical prostaglandin F(2 alpha)--isopropyl ester (PGF(2 alpha)-IE) administration on immunoreactivity of matrix metalloproteinases (MMPs) 1, 2, and 3 within the anterior segment tissues of monkey eyes. METHODS: Eight eyes from 4 cynomolgus monkeys were evaluated. One eye from each monkey was treated with 2 mg of PGF(2 alpha)-IE twice daily for 5 days, and intraocular pressure reduction was measured. After fixation and processing, deparaffinized sections of anterior segments were immunostained using antibodies to MMP-1 (interstitial collagenase), MMP-2 (gelatinase A), or MMP-3 (stromelysin-1). Optical density along 2 line segments overlying the iris root, ciliary muscle, and adjacent sclera and perpendicular to their long axes was measured using imaging densitometry. RESULTS: Compared with the contralateral vehicle-treated eyes, statistically significant increases in optical density scores were observed in the iris root, ciliary muscle, and adjacent sclera for all 3 MMPs (P<.01). In these tissues, MMP-1 immunoreactivity was increased by a mean +/- SD of 89% +/- 16%, 61% +/- 8%, and 66% +/- 57%, respectively; MMP-2 immunoreactivity by 129% +/- 53%, 82% +/- 27%, and 267% +/- 210%, respectively; and MMP-3 immunoreactivity by 207% +/- 84%, 83% +/- 49%, and 726% +/- 500%, respectively. CONCLUSIONS: Treatment of monkey eyes with PGF(2 alpha)-IE induces elevation of MMP-1, MMP-2, and MMP-3 in tissues of the uveoscleral outflow pathway. These increases suggest that MMPs might play an important role in the increased uveoscleral outflow observed with topical prostaglandin treatment. CLINICAL RELEVANCE: Immunoreactivity of MMPs in tissues of the monkey uveoscleral outflow pathway is increased after topical treatment with PGF(2 alpha)-IE. This response also might be involved in the intraocular pressure--lowering effect of other prostanoids used to treat glaucoma.

Administration, Topical↗

PubMed2001

Reduced TIGR/myocilin protein in the monkey ciliary muscle after topical prostaglandin F(2alpha) treatment.

PURPOSE: Mutations in the trabecular meshwork inducible glucocorticoid response (TIGR) gene, also known as myocilin, have recently been linked to some forms of glaucoma. Recent studies have shown that TIGR protein also is expressed in the ciliary muscle. Because uveoscleral outflow, which traverses the ciliary muscle, is increased by prostaglandins (PGs), the present study assessed whether topical PGs alter the amount of TIGR protein within the ciliary muscle. METHODS: Vehicle was topically applied to one eye, and 2 microg PGF(2alpha)-isopropyl ester (PGF(2alpha)-IE) was applied to the other eye of cynomolgus monkeys twice daily for 5 days. Pressure reductions of 5 mm Hg in the PGF(2alpha)-IE-treated eyes were confirmed. The eyes were then fixed and paraffin sections were cut from each eye. The distribution of TIGR protein in the ciliary muscle was determined by confocal scanning laser microscopy. Additional sections were immunostained with a polyclonal antibody to recombinant TIGR protein or with a polyclonal antibody to a synthetic peptide corresponding to the leucine zipper region within the TIGR protein. Staining intensity in the ciliary muscle was assessed by measuring optical density (OD) along two line segments overlying the ciliary muscle, by using a high-resolution imaging densitometer. RESULTS: TIGR protein immunoreactivity was observed in ciliary muscle fibers throughout the ciliary muscle. Extracellular TIGR immunoreactivity colocalized with collagen type IV immunoreactivity. Intracellular staining also was present. Immunoreactivity was less intense in the sections from the PGF(2alpha)-IE-treated eyes compared with the vehicle-treated eyes. This was reflected in the reduction of mean OD scores in each monkey. Overall, the reduction of mean OD scores in the treated eyes was 42.1% +/- 9.9% (P < 0.005) with the anti-recombinant TIGR antibody and 27.3% +/- 10.4% with the anti-TIGR peptide antibody (P < 0.005). CONCLUSIONS: TIGR protein immunoreactivity was present both intracellularly and extracellularly in the ciliary muscle of the cynomolgus monkey. This suggests that extracellular TIGR protein is in contact with aqueous humor in the uveoscleral outflow pathway. Moreover, IOP-lowering topical PGF(2alpha)-IE treatment decreases the amount of TIGR protein in the ciliary muscle.

Administration, Topical↗

PubMed2000

Regulation of connexin phosphorylation and cell-cell coupling in trabecular meshwork cells.

PURPOSE: To investigate the expression of functional gap junctions and the effect of protein kinase C (PKC) on such junctions in confluent cultures of bovine trabecular meshwork (TM) cells. METHODS: Expression of the gap junction protein connexin43 in TM cells was examined by immunofluorescence microscopy. Intercellular communication by gap junctions was assessed by observing the diffusion of fluorescent dye from an individual cell injected with lucifer yellow. The phosphorylation of connexin43 was evaluated by immunoblot analysis with a monoclonal antibody to this protein. RESULTS: Immunofluorescence staining revealed that connexin43 was localized to sites of contact between adjacent TM cells. Exposure of cells to the PKC activator phorbol 12-myristate 13-acetate (PMA; 10 nM, 1 hour) had no marked effect on the pattern of connexin43 immunofluorescence. Injection of a TM cell with lucifer yellow resulted in the spread of the dye into neighboring cells. Dye coupling was inhibited by PMA in a dose- and time-dependent manner, and this inhibition was prevented by pretreatment of cells with the PKC inhibitor bisindolylmaleimide I. Immunoblot analysis of control TM cell lysates yielded connexin43 bands corresponding to the nonphosphorylated protein (43 kDa) and three phosphorylated forms (47, 48, and 49 kDa). Cells exposed to PMA (10 nM, 1 hour) yielded an additional band corresponding to a 44-kDa form of phosphorylated connexin43 and showed a decrease in the intensity of the band corresponding to the nonphosphorylated protein and an increase in the intensity of the 47-kDa band. CONCLUSIONS: TM cells communicate with each other through gap junctions, and the communication is inhibited by PKC, probably, at least in part, through phosphorylation of connexin43.

Actins↗

PubMed1999

Topical prostaglandin F2alpha treatment reduces collagen types I, III, and IV in the monkey uveoscleral outflow pathway.

BACKGROUND: Topical prostaglandin F2alpha isopropyl ester increases uveoscleral outflow in monkeys and humans. OBJECTIVE: To investigate the effects of prostaglandin F2alpha isopropyl ester with topical administration on collagen types I, III, and IV within the anterior segment tissue of monkey eyes. METHODS: Eight eyes of 4 cynomolgus monkeys were evaluated. One eye of each monkey was treated with 2 microg of prostaglandin F2alpha isopropyl ester twice daily for 5 days, and intraocular pressure reduction was confirmed. These eyes were fixed in methacarn, and paraffin sections were immunostained using antibodies to collagen types I, II, or IV. To measure staining intensity, optical density (OD) was determined using 2-dimensional imaging densitometry. Mean OD scores along line segments placed over the ciliary muscle were determined. RESULTS: Mean+/-SD OD scores for collagen types I, III, and IV were less in the ciliary muscle of prostaglandin-treated eyes than in vehicle-treated eyes by 52%+/-7%, 45%+/-6%, and 45%+/-5%, respectively. In the sclera adjacent to the ciliary body, mean OD scores for collagen types I and III were less in prostaglandin-treated eyes, by 43%+/-32% and 45%+/-13%, respectively. The scleral stroma was minimally immunoreactive for collagen type IV. All differences were significant by the paired Student t test (P<.05). CONCLUSIONS: This study shows reduced collagen types I, III, and IV immunoreactivity in the ciliary muscle and adjacent sclera following topical prostaglandin F2alpha isopropyl ester treatment. These reductions may contribute to the increased uveoscleral outflow observed with topical prostaglandin treatment. CLINICAL RELEVANCE: The cellular mechanism by which certain prostaglandins lower intraocular pressure is not known. The present study provides immunohistochemical data demonstrating that intraocular pressure reduction that occurs with topical prostaglandin F2alpha is associated with a reduction of collagens within the uveoscleral outflow pathway.

Administration, Topical↗

PubMed1999

Relationship between shift work and onset of hypertension in a cohort of manual workers.

OBJECTIVES: This study investigated the possibility of a relationship between blood pressure level and rotating 3-shift work in a prospective follow-up of workers in a zipper and aluminum sash factory in Japan. METHODS: Altogether 1551 men aged 18-49 years were followed prospectively for 5 years, and the cumulative incidence of hypertension among 3-shift workers was compared with that of day workers. A multiple logistic analysis was used for adjusting for base-line characteristics such as age, body mass index, blood pressure, and drinking habit. RESULTS: In the younger age group, the relative risk of the rotating 3-shift workers during the observational period was increased compared with that of day workers after adjustment for the confounding factors. In the older group, the cumulative incidence of hypertension was not higher for workers who had continued shift work. However, a relatively high risk of hypertension was found for workers who converted from 3-shift work to day work when compared with those who remained on shift work and day work. CONCLUSIONS: It is suggested that there is an association between 3-shift work and blood pressure.

Adolescent↗

PubMed1999

Reduction of collagen type I in the ciliary muscle of inflamed monkey eyes.

PURPOSE: To investigate in monkey ciliary muscle the relationship between the extent of anterior segment inflammation and alterations of collagen type I as determined by quantitative imaging densitometry. METHODS: Anterior segment inflammation was induced in one eye of five cynomolgus monkey by cannulation of the anterior chamber, by anterior chamber injection of bovine serum albumin, or by disruption of the iris and anterior lens capsule with a needle. Increases in inflammatory cells were scored in hematoxylin and eosin-stained sections. Parallel eye sections were immunostained for collagen type I and developed using diaminobenzidine. Optical density (OD) was measured along two line segments overlying the immunostained ciliary muscle using two-dimensional imaging densitometry. To assess antibody labeling of ciliary muscle structures, additional sections were double-immunostained using antibodies to collagen type I and calponin and examined by confocal microscopy. RESULTS: In each of the inflamed eyes, hematoxylin and eosin-stained sections showed signs of chronic inflammation including lymphocytes and macrophages dispersed among ciliary muscle fibers and in the iris. Double label confocal microscopy showed collagen type I immunoreactivity in the interstitial extracellular matrix between bundles of ciliary smooth muscle fibers. Collagen type I OD scores in each of the inflamed eyes were less by 16% to 55%, compared with the contralateral control eyes. The mean of the OD scores for all inflamed eyes was 39%+/-7% less than the mean of the control eye scores (mean +/- SEM, P < 0.001). Regression analysis showed a close correlation between inflammatory cell scores in the treated eyes and the reduction of OD scores (r = 0.94, P = 0.02). CONCLUSIONS: These results indicate that the density of collagen type I in the extracellular matrix (ECM) of monkey ciliary muscle is reduced during anterior segment inflammation and support the view that reduction of ciliary muscle ECM may contribute to increased uveoscleral outflow facility during anterior segment inflammation.

Animals↗

PubMed1999

Matrix metalloproteinase-1 localization in the normal human uveoscleral outflow pathway.

PURPOSE: To determine the distribution of matrix metalloproteinase-1 (MMP-1) in the uveoscleral outflow pathway and other anterior segment tissues of normal human eyes. METHODS: Normal human eyes were fixed in methacarn and sectioned and immunostained using a specific polyclonal antibody to MMP-1. Immunoreactivity was visualized using diaminobenzidine. To compare the staining intensity in various tissues, the mean optical density within the ciliary body, mid-iris stroma, iris root, uveal trabecular meshwork, cornea, and sclera was determined using imaging densitometry. To determine the cellular distribution of MMP-1 in ciliary muscle, additional sections were double-immunostained using antibodies to MMP-1 and calponin. These sections were examined by confocal laser scanning microscopy. Specificity of the antibody to MMP-1 in ocular tissues was confirmed by western blot analysis with uveal tract homogenates. RESULTS: Moderate-to-strong MMP-1 immunoreactivity was observed in ciliary muscle, iris, sclera, corneal endothelium, and ciliary nonpigmented epithelium. Lighter immunoreactivity was observed in corneal epithelium, blood vessels, trabecular meshwork, Schlemm's canal, and associated collector channels. Confocal microscopy showed that ciliary muscle MMP-1 was primarily inside ciliary muscle cells. Densitometry showed that net optical density was approximately fivefold greater in ciliary muscle, iris root, and sclera than in trabecular meshwork. CONCLUSIONS: MMP-1 was prominently identified in regions of the anterior segment of normal human eyes associated with the uveoscleral outflow pathway and in the iris, corneal endothelium, and ciliary nonpigmented epithelium. These data support the hypothesis that MMP-1 activity is involved in regulating uveoscleral outflow facility.

Aged↗

PubMed1998

Cloning and expression of the gene encoding flavodoxin from Desulfovibrio vulgaris (Miyazaki F).

The gene encoding a flavodoxin of Desulfovibrio vulgaris (Miyazaki F) was cloned, and overexpressed in Escherichia coli. A 1.6-kbp DNA fragment, isolated from D. vulgaris (Miyazaki F) by double digestion with SalI and EcoRI, contained the flavodoxin gene and its regulatory region. An expression system for the flavodoxin gene under control of the T7 promoter was constructed in E. coli. The purified protein was soluble and exhibited a characteristic visible absorption spectrum. HPLC analysis of the recombinant flavodoxin revealed the presence of an identical FMN to that found in the native D. vulgaris flavodoxin, and its dissociation constant with FMN was determined to be 0.38 nM. In vitro H2 reduction analysis indicated that the recombinant flavodoxin is active, and its redox potential was determined to be E1 = -434 and E2 = -151 mV using methyl viologen and 2-hydroxy-1,4-naphthoquinone, respectively. Its redox behavior was also examined with the recombinant flavodoxin adsorbed onto a graphite electrode. The mutant, A16E, was also produced, which revealed the feature of a conserved Glu residue at the surface of the molecule.

Base Sequence↗

PubMed1998

[The development of the Japanese version of the Maslach Burnout Inventory and the examination of the factor structure].

This article presents an evaluation of the factor structures of the Japanese version of the Maslach Burnout Inventory (MBI). The MBI is a widely used psychometric instrument for measuring 'burnout' developed by Maslach and her co-workers. The MBI consists of four subscales: Emotional Exhaustion, Personal Accomplishment, Depersonalization, and Involvement. The MBI was translated into Japanese along with a back-translation and was administered to a sample of 267 nurses. Various psychometric analyses showed that the Japanese version of the MBI has high reliability for the 22 items scored for the frequency dimension. The factor analysis using principal factoring with an oblique rotation resulted in three factor structures that had different implications from the MBI: Emotional Exhaustion/Depersonalization, Personal Accomplishment, and Physical Exhaustion. The correlationship between the MBI and the General Health Questionnaire (GHQ), measures of depression, showed that burnout was a unique phenomenon.

Adult↗

PubMed1997

Cloning and expression of the rubredoxin gene from Desulfovibrio vulgaris (Miyazaki F)--comparison of the primary structure of desulfoferrodoxin.

A gene encoding rubredoxin from Desulfovibrio vulgaris (Miyazaki F) was cloned and overexpressed in Escherichia coli. A 1.1-kilobase pair DNA fragment, isolated from D. vulgaris (Miyazaki F) by double digestion with SmaI and SalI, contained two genes, the rubredoxin gene (rub) and the desulfoferrodoxin gene (rbo) which was situated upstream of rub. The deduced amino acid sequence of desulfoferrodoxin was homologous to those from other strains and Cys residues that are responsible to bind irons were also conserved. The expression system for rub was constructed under the control of the T7 promoter in E. coli. The purified protein was soluble and had a characteristic visible absorption spectrum. Inductively coupled plasma-atomic emission analysis and electron paramagnetic resonance analysis of the recombinant rubredoxin revealed the presence of an iron ion in a distorted tetrahedral geometry that was the same as native D. vulgaris rubredoxin. In vitro NADH reduction analysis indicated that recombinant rubredoxin was active, and its redox potential was determined as -5 mV.

Amino Acid Sequence↗

PubMed1997

Apical tubules in marginal cells of the differentiating stria vascularis.

BACKGROUND: Apical tubules (ATs) in marginal cells (MCs) of the stria vascularis appear in limited stages of differentiation of the MCs, but their origin and roles remain uncertain. The present study was designed to solve the problem of whether the ATs are intracellular compartments derived from the Golgi apparatus (GA). METHODS: The cochleae of Wistar rats at ages of postnatal days 1, 3, and 5 were prepared for electron microscopy and cytochemistry using thiamine pyrophosphatase (TPPase) and coenzyme A phosphatase (CoA-Pase) as marker enzymes of trans Golgi cisterns and fluorescent labelled lectin, griffonia simplicifolia agglutinin-I (GS-1). RESULTS: The ATs appeared in the apical cytoplasm of the MCs between postnatal days 1 and 5. Reaction products of TPPase and CoA-Pase activities were localized in the trans-Golgi cisterns and the ATs, which were occasionally in a close apposition to the GA. The reaction was found along the apical plasma membrane of the MCs only in case of TPPase. Heavy reactions to GS-1 were seen in the supranuclear region as well as along the apical plasma membrane of the MCs. CONCLUSIONS: The present ultrastructural and cytochemical studies indicate that the ATs, which appear in the MCs at limited perinatal stages, originate from the trans-Golgi cisterns. These ATs may be involved in the apical plasma membrane supply for the differentiation of the MCs prior to the generation of EP.

Animals↗

PubMed1997

Preventive effect of 1-(2-tetrahydrofuryl)-5-fluorouracil in combination with uracil on colonic carcinogenesis induced by 1,2-dimethylhydrazine in rats.

Thymidylate synthetase (TS) and thymidine kinase (TK) are key enzymes in de novo and salvage pathways for pyrimidine nucleotide synthesis, respectively. A high incidence of colorectal adenocarcinomas with varied grades of cell differentiation can be induced by 1,2-dimethylhydrazine (DMH) in rats. The marked increases of TS and TK activities were found in the poorly and well-differentiated adenocarcinomas of the colon, respectively. Oral administration of 1-(2-tetrahydrofuryl)-5-fluorouracil in combination with uracil (UFT) markedly reduced the number and accumulated area of colonic carcinomas, and TS activity in the poorly differentiated adenocarcinomas. A potential balance between the de novo and the salvage pathways for pyrimidine nucleotide synthesis was suggested to be related with the histopathological grades of cell differentiation. Suppression of colonic TS activity by UFT administration reduced the colonic carcinogenesis and the potency of the poorly differentiated adenocarcinomas of the colon.

1,2-Dimethylhydrazine↗

PubMed1996

Regulation of the redox order of four hemes by pH in cytochrome c3 from D. vulgaris Miyazaki F.

The assignment of 1H-NMR signals of the heme methyl and propionate groups of cytochrome c3 of D. vulgaris Miyazaki F was performed. The heme assignment was revised for hemes 2 and 3 (sequential heme numbering). Namely, heme 4 is mainly reduced at first with hemes 1, 2 and 3 following it in this order. The p2H titration of heme methyl signals in four macroscopic oxidation states was performed in the p2H range of 5.2 to 9.0. While the heme methyl resonances in the fully oxidized state showed just small changes with p2H, most resonances in the intermediate oxidation states revealed clear p2H dependence. In particular, the methyl resonances of heme 1 shifted significantly in the acidic region. Then, the chemical shifts of beta-CH2 (next to the carboxyl group) of all propionate groups in the fully oxidized state were observed at various p2H in the range of 4.5 to 9.0. Only the propionate group at C-13 (IUPAC-IUB nomenclature) of heme 1 showed a clear change in this p2H range, its titration curve being similar to those of the methyl resonances of heme 1 in the intermediate oxidation states. pKa of the propionate group was 5.95 +/- 0.05. Analysis of the microscopic formal redox potentials was carried out for the observations at p2H 5.2, 7.1 and 9.0. The redox potentials of heme 1 showed the most remarkable p2H dependence, resulting in the change of the order of the redox potentials of four hemes. A significant change was also found in the interacting potential between hemes 1 and 2. In the light of the p2H-titration experiments, the propionate at C-13 of heme 1 was identified as the most plausible ionizable group responsible for the p2H dependence of microscopic redox potentials of heme 1 in the acidic region.

Cytochrome c Group↗

PubMed1996

Ligand recognition in mu opioid receptor: experimentally based modeling of mu opioid receptor binding sites and their testing by ligand docking.

For three-dimensional understanding of the mechanisms that control potency and selectivity of the ligand binding at the atomic level, we have analysed opioid receptor-ligand interaction based on the receptor's 3D model. As a first step, we have constructed molecular models for the multiple opioid receptor subtypes using bacteriorhodopsin as a template. The S-activated dihydromorphine derivatives should serve as powerful tools in mapping the three-dimensional structure of the mu opioid receptor, including the nature of the agonist-mediated conformational change that permits G protein-coupling to "second messenger' effector molecules, and in identifying specific ligand-binding contacts with the mu opioid receptor. The analyses of the interactions of some opioid ligands with the predicted ligand binding sites are consistent with the results of the affinity labeling experiments.

Affinity Labels↗