Biomedical subjects

Minoru Saito

Publications and source records attributed to Minoru Saito.

13 recordsLinked to original sources

PubMed2005

Design, synthesis, and enzymatic property of a sulfur-substituted analogue of trigalacturonic acid.

A sulfur-substituted analogue of trigalacturonic acid (3) was synthesized. The synthesis features the application of 3-cyano-3-(tert-butyldimethylsilyl)oxypropylthioether (CSP) as a novel protective group for thiols. This analogue was designed with the expectation that it would be a stable analogous substrate for endo-polygalacturonase isolated from Stereum purpureum based on computer modeling experiments. Surface plasmon resonance experiments revealed that 3 forms a stable complex with the target enzyme.

Carbohydrate Sequence↗

PubMed2005

A free energy calculation study of the effect of H-->F substitution on binding affinity in ligand-antibody interactions.

Changes in binding affinity to catalytic antibody 6D9 of chloramphenicol phosphonate derivatives (CPDs) containing H or F were investigated by performing free energy calculations based on molecular dynamics simulations. We calculated the binding free energy, enthalpy, and entropy changes (DeltaDeltaG, DeltaDeltaH, and -TDeltaDeltaS) attributable to H-->F substitution by comparing results for CPDs containing a trifluoroacetylamino group (CPD-F) or an acetylamino group (CPD-H). The calculated DeltaDeltaG, DeltaDeltaH, and -TDeltaDeltaS values were -2.9, -6.3, and 3.5 kcal mol(-1) and close to experimental values observed for a series of similar ligands, chloramphenicol phosphonates with F and H (-1.4, -3.5, and 2.1 kcal mol(-1)). Therefore, CPD-F binds more strongly to 6D9 than does CPD-H. To clarify the origin of the large difference in DeltaDeltaG, we apportioned the calculated values of DeltaDeltaG and DeltaG for the associated and dissociated states into contributions from various atomic interactions. We found that the H-->F substitution increased the binding affinity mainly by decreasing the hydration free energy and not by increasing favorable interactions with the antibody. The decreased hydration free energy of the ligand was mainly due to unfavorable coulombic interactions between the trifluoroacetylamino group and solvent waters, which increased the free energy of the dissociated state (by about 3.7 kcal mol(-1)). Also, the trifluoroacetylamino group slightly increased the free energy level of the associated state (about 0.8 kcal mol(-1)) because favorable van der Waals interactions compensated for unfavorable coulombic interactions with antibody atoms. In addition, the enthalpy and entropy changes, DeltaDeltaH and -TDeltaDeltaS (computationally -6.3 and 3.5 kcal mol(-1)), originated mainly from a decrease in hydration free energy in the dissociated state. The CPD-F and CPD-H ligands had substantially different structures in the dissociated and complexed states.

Antibodies↗

PubMed2005

Proteome analysis of gelatin-bound urinary proteins from patients with bladder cancers.

OBJECTIVES: Proteome analysis with protein separation by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and mass spectrometric measurement is utilized for comprehensive identification of proteins in various biological samples. However, this technique has not been widely applied for the analysis of body fluid for clinical assessments, because large amounts of proteins in fluid such as albumin and globulin hinder the detection of small amounts of proteins with high clinical values. The aim of the present study is to develop a method of proteomic analysis for urine of patients with bladder cancers. MATERIALS AND METHODS: Urine samples collected from 40 patients with bladder cancers, 32 healthy volunteers, and 7 old volunteers with benign prostate hypertrophy were treated with gelatin-beads as a group-specific affinity carrier. The gelatin-bound proteins were subjected to the proteome analysis. RESULTS: Various amounts of matrix metalloproteinase-2 (MMP-2), -9 (MMP-9), fibronectin (FN), and their fragments were identified on 2-D PAGE gels from cancer-bearing patients, but not from normal individuals. Importantly, not only total amounts of these proteins, but also patterns of their distributions on the gels were well matched with the extent of invasion diagnosed with histopathological examinations. Thus, the score including such qualitative patterning of these proteins predicts pathological stages of the cancer. CONCLUSION: The proteomic analysis with gelatin-affinity purification of urine samples is useful not only for the diagnosis of bladder cancers, but also for estimating the extent of tumor invasion.

Biomarkers, Tumor↗

PubMed2004

Acute effect of corticosterone on N-methyl-D-aspartate receptor-mediated Ca2+ elevation in mouse hippocampal slices.

We examined the rapid effects of corticosterone (CORT) on N-methyl-D-aspartate (NMDA) receptor-mediated Ca2+ signals in adult mouse hippocampal slices by using Ca2+ imaging technique. Application of NMDA caused a transient elevation of intracellular Ca2+ concentration followed by a decay to a plateau within 150s. The 30min preincubation of CORT induced a significant decrease of the peak amplitude of NMDA-induced Ca2+ elevation in the CA1 region. The rapid effect of CORT was induced at a stress-induced level (0.4-10microM). Because the membrane non-permeable bovine serum albumin-conjugated CORT also induced a similar rapid effect, the rapid effect of CORT might be induced via putative surface CORT receptors. In contrast, CORT induced no significant effects on NMDA-induced Ca2+ elevation in the dentate gyrus. In the CA3 region, CORT effects were not evaluated, because the marked elevation of NMDA-induced Ca2+ signals was not observed there.

Animals↗

PubMed2004

Mutational and structural-based analyses of the osmolyte effect on protein stability.

It is known that several naturally occurring substances known as osmolytes increase the conformational stability of proteins. Bolen and co-worker proposed the osmophobic theory, which asserts the osmolyte effect occurs because of an unfavorable interaction of osmolytes mainly with the protein backbone, based on the results on the transfer Gibbs energy of amino acids (Deltag) [Bolen and Baskakov (2001) J. Mol. Biol. 310, 955-963]. In this paper, we report the effect of sarcosine on the conformational stability (DeltaG) of RNase Sa (96 residues and one disulfide bond) and four mutant proteins. The thermal denaturation curves for RNase Sa in sarcosine fitted a two-state model on nonlinear least-squares analysis. All the RNase Sa proteins were stabilized by sarcosine. For example, the increase in stability of the wild-type protein in 4 M sarcosine due to the osmolyte effect (Delta(o)DeltaG) is 3.2 kcal/mol. Mutational analysis of the osmolyte effect indicated that the changed Delta(o)DeltaG values upon mutation (Delta(m)Delta(o)DeltaG), as estimated from the Deltag values, are similar to the experimental values. Structural-based analysis of the osmolyte effect was also performed using model denatured structures: (a) a fully extended model (single chain) with no disulfide bond, (b) two-part, unfolded models (two chains) with a disulfide bond constructed through molecular dynamic (MD) simulation, and (c) a two-part, folded model (two chains). The two-part, unfolded models were expected to be more suitable as denatured structures. The Delta(o)DeltaG values calculated using the two-part, unfolded models were more consistent with experimental values than those calculated using the fully extended and two-part, folded models. This suggests that MD simulation is useful for testing denatured structures. These results indicate that the osmophobic theory can explain the osmolyte effect on protein stability.

Circular Dichroism↗

PubMed2004

[Gymnema sylvestre leaf extract: a 52-week dietary toxicity study in Wistar rats].

A 52-week study of oral-repeated-dose toxicity for the extraction powder of Gymnema sylvestre (GS), Indian-native genus, Metaplexis japonica, was conducted in both genders of Wistar rats. The rats were administered a graded dose of GS at 0.01, 0.10 and 1.00% of basal powder diet, along with a group fed solely with the basal powder diet without GS, for 52 weeks. General conditions were recorded daily. Body weights and food consumptions were recorded weekly up to 12 weeks, and thereafter at longer intervals. At 26 weeks, for an intermediate examination, and 52 weeks, for the final examination, animals were subjected to hematology, serum chemistry, and pathological examination. None of the animals died in the period up to 52 weeks. No exposure-related changes in body-weight, in the food consumption, in the hematological examinations, or in the serum biochemical examinations were recognized. No histopathological alterations were seen. Thus, it was concluded that there was no toxic effect in rats treated with GS at up to 1.00% in the diet for 52 weeks. The no-observable-effect level from this study is 1.00% GS, i.e., 504 mg/kg/day for male and 563 mg/kg/day for female as mean daily intake, for 52 weeks.

Administration, Oral↗

PubMed2003

Free energy calculations for the relative binding affinity between DNA and lambda-repressor.

The change in the binding free energy between DNA and lambda-repressor resulting from a base substitution, thymine (T)-->deoxyuracil (abbreviated as U), was evaluated by the free energy perturbation method on the basis of molecular dynamics simulations for the DNA-lambda-repressor complex in water with all degrees of freedom and including long-range Coulomb interactions. The binding free energy change that we calculated (1.47 +/- 0.40 kcal/mol) was in good agreement with an experimental value (1.8 kcal/mol). We clarified why the small difference between T and U (CH(3) in T is replaced with H in U) caused such a significant change in the binding free energy: The substitution of CH(3) in T with H in U lowered the dissociated-state free energy level due to the gain of the hydration free energy. Furthermore, the T-->U substitution raised the free energy level in the associated state due to the loss of the favored van der Waals (vdW) interactions with the lambda-repressor amino acid residues. In other words, the amino acid residues of lambda-repressor can recognize the CH(3) in T through the vdW interactions with the CH(3). This recognition is enhanced in a water environment, because the hydrophobic CH(3) prefers the amino acid residues of lambda-repressor to water molecules.

Binding Sites↗

PubMed2003

Imaging of L-glutamate fluxes in mouse brain slices based on an enzyme-based membrane combined with a difference-image analysis.

A time-resolved imaging method for visualizing L-glutamate release in mammalian brain slices is proposed by using an enzyme membrane combined with a difference-image analysis. The enzyme membrane is composed of L-glutamate oxidase and horseradish peroxidase incorporated into a bovine serum albumin matrix. L-Glutamate triggers an enzyme-coupling reaction to convert a redox substrate (DA-64) to Bindschedler's Green, which gives a green color signal. The difference-image analysis is based on calculating slopes of a signal versus time (t) plot in the time range from (t - 40 s) to (t + 40 s) for visualizing L-glutamate release in terms of its flux (in mol min(-1) cm(-2)). The method was applied to a time-resolved imaging of hippocampal distribution of ischemia-induced L-glutamate release in mouse brain slices. The image of L-glutamate distribution showed that the level and time courses of L-glutamate fluxes were neuronal region-dependent. The maximum flux of L-glutamate at CA1 was observed at 7.7 min after ischemia. The flux at 7.7 min increased in the order of CA1 approximately CA3 > DG. The time course of the L-glutamate flux in the CA1 region was biphasic and that in the DG region was modestly biphasic. In the CA3 region, such biphasic release of L-glutamate was not seen. The ischemia-induced L-glutamate flux was accelerated when Mg2+ was omitted from an extracellular solution. The present enzyme membrane-based approach provides a useful method for visualizing distribution of L-glutamate release in the brain slices during ischemia.

Amino Acid Oxidoreductases↗

PubMed2003

Presynaptic K+ channel modulation is a crucial ionic basis of neuronal damage induced by ischemia in rat hippocampal CA1 pyramidal neurons.

The ischemia-induced synaptic potentiation (ISP) during and/or after brain ischemia has been suggested to be one of the crucial factors responsible for irreversible neuronal damage of hippocampal CA1 pyramidal neurons. However, the presynaptic modulation mechanism that leads to neuronal damage during and/or after ischemia was still unknown. By combining electrophysiological methods and infra-red differential interference contrast (IR-DIC) imaging procedures, we showed for the first time that ISP is the result of extraordinary presynaptic depolarization in association with the suppression of 4-aminopyridine (4-AP) sensitive K(+) channels at the presynaptic sites. Furthermore, we also showed that the 4-AP sensitive presynaptic K(+) channels played a crucial role in inducing neuronal damage at a very acute phase of ischemia-induced neuronal damage and would be a therapeutic target against the neuronal damage after brain ischemia.

4-Aminopyridine↗

PubMed2003

[High-dose chemotherapy with autologous peripheral blood stem cell transplantation for the treatment of multiple myeloma refractory to conventional chemotherapy].

High-dose chemotherapy with autologous peripheral blood stem cell transplantation was administered to five patients with refractory myeloma. To collect peripheral blood stem cells, apheresis was done by administering doxorubicin 40 mg/m2 on the first day, and etoposide 60 mg/m2 on the first, second, and third days, followed by G-CSF administration to harvest cells. The high-dose chemotherapy consisted of melphalan 60 mg/m2 administered for 4 days and infusion of mononuclear cells. No serious side effects were observed during the clinical course. After transplantation, complete or partial responses were achieved. APBSCT is considered to be a useful method because it had an antitumor effect against multiple myeloma that is refractory to conventional chemotherapy, as well as against multiple myeloma that is sensitive to chemotherapy, and it can be safely performed.

Adult↗

PubMed2002

Cerebrovascular disorders and genetic polymorphisms: mitochondrial DNA5178C is predominant in cerebrovascular disorders.

We studied polymorphisms of mitochondrial DNA 5178cytosine/adenine (mt5178C/A) and angiotensin I-converting enzyme (ACE) genes (DCP1) in 127 cerebrovascular disorder (CVD) patients and 294 age-matched normal controls to clarify the genetic background of Japanese patients with CVD. Mt5178C was predominant in CVD patients compared with controls (P<0.01). The frequency of DCP1 insertion (I) and deletion (D) alleles showed no significant difference between the CVD patients and controls or between each CVD subgroup. Although the number of CVD patients in the present study was too small to make a final conclusion, mt5178C might be one of the genetic factors to be considered in Japanese patients with CVD.

Aged↗

PubMed2002

Genetic and enzymatic analyses of metalloprotease (aureolysin) from Staphylococcus aureus isolated from domestic animals.

The gene (aur) encoding the metalloprotease (aureolysin) of Staphylococcus aureus from domestic animals was analyzed by polymerase chain reaction (PCR), PCR-restriction fragment length polymorphism (PCR-RFLP) and sequencing. The aur gene was detected in all 74 isolates from cows, pigs and chickens by PCR amplification and was classified into types I and II by PCR-RFLP patterns. The type II aur gene was contained in 36 (94.7%) of 38 protease-positive isolates as judged by skim milk agar plate culture, while type I was contained in 28 (77.8%) of 36 protease-negative isolates. The deduced amino acid sequences of aureolysins from type I and II isolates were almost identical with those of the published data. Subsequently, the two aureolysins were purified from the culture supernatants of type I and II isolates. The molecular weights of purified type I and II aureolysins were both estimated at 34kDa by SDS-polyacrylamide gel electrophoresis. These aureolysins had maximum proteolytic activity at 30-50 degrees C and pH 7.0-8.0. Their activity was inhibited by metal- and zinc-specific inhibitors, such as EDTA, EGTA and 1,10-phenanthroline. Specific activity (activity/protein) of type II aureolysin was two times higher than that of type I. These results indicated that the aur gene is highly conserved with two allelic forms (types I and II) among bovine, porcine and avian isolates of S. aureus.

Amino Acid Sequence↗

PubMed2002

[Kooroo color: 90-day dietary toxicity study in F344 rats].

A subchronic toxicity study on kooroo color was conducted using F344 rats of both genders. Kooroo color is an extract of yam root, Dioscorea matudai Hayata, of which the major components are known to be flavonoid pigments. Use of kooroo as a food color is permitted by the Food Sanitation Law in Japan, but the chronic toxicity has not been evaluated in the literature. Rats were fed the product of kooroo color (PKC) at doses of 0.5%, 1.50%, and 5.0% in basal powder diet, while control groups received PKC-free basal diet, for ninety days. A vehicle control given propylene glycol (PG) alone, at the same dosage that the 5.0% group received, was included, because PKC used in this study contained ca. 80 percent PG, used as an extractant during the manufacturing processes. Daily observation of general behavior, and weekly measurement of body weight as well as food consumption were performed. Hematological, serum biochemical and anatomopathological examinations were conducted at the end of administration. No abnormalities ascribable to the treatment with PKC or PG were noted in any examination in this study. Hence, dietary intake of 5.0% of PKC, i.e., 2,993 mg/kg/day for males, and 3,376 mg/kg/day for females, as a mean daily intake for 90 days, had no observable adverse effect in F344 rats. Therefore, kooroo color has no significant general toxicity, and its toxicity, if any, is of a very low order.

Animals↗