Sugar recognition specificities of class III (OsChib1a) and class I (OsChia1cDeltaChBD) chitinases from rice, Oryza sativa L., were investigated by analyzing (1)H- and (13)C-nuclear magnetic ...resonance spectra of the enzymatic products from partially N-acetylated chitosans. The reducing end residue of the enzymatic products obtained by the class III enzyme was found to be exclusively acetylated, whereas both acetylated and deacetylated units were found at the nearest neighbor to the reducing end residue. Both acetylated and deacetylated units were also found at the nonreducing end residue and its nearest neighbor of the class III enzyme products. Thus, only subsite (-1) among the contiguous subsites (-2) to (+2) of the class III enzyme was found to be specific to an acetylated residue. For the class I enzyme, the reducing end residue was preferentially acetylated, although the specificity was not absolute. The nearest neighbor to the acetylated reducing end residue was specifically acetylated. Moreover, the nonreducing end residue produced by the class I enzyme was exclusively acetylated, although there was a low but significant preference for deacetylated units at the nearest neighbor to the nonreducing end. These results suggest that the three contiguous subsites (-2), (-1), and (+1) of the class I enzyme are specific to three consecutive GlcNAc residues of the substrate. In rice plants, the target of the class I enzyme might be a consecutive GlcNAc sequence probably in the cell wall of fungal pathogen, whereas the class III enzyme might act toward an endogenous complex carbohydrate containing GlcNAc residue.
The purpose of the present study was to use event-related potentials (ERP) to clarify the effect of magnetic stimulation on cognitive processing. A figure eight-shaped flat repetitive transcranial ...magnetic stimulation (rTMS) coil was used to stimulate either the region over the left or the right dorsolateral prefrontal cortex, which is considered to be the origin of the P300 component. Stimulus frequencies were 1.00, 0.75 and 0.50 Hz rTMS. The strength of the magnetic stimulation was set at 80% of the motor threshold for each participant. The auditory oddball task was used to elicit P300s before and shortly after rTMS, and comprised a sequence of sounds containing standard (1 kHz pure tone, 80% of trials) and deviant (2 kHz pure tone, 20% of trials) stimuli. We found that a 1.00 Hz rTMS pulse train over the left dorsolateral prefrontal cortex increased P300 latencies by 8.50 ms at Fz, 12.85 ms at Cz, and 11.25 ms at Pz. In contrast, neither 0.75 and 0.50 Hz rTMS pulse trains over the left dorsolateral prefrontal cortex nor 1.00, 0.75 and 0.50 Hz rTMS pulse trains over the right dorsolateral prefrontal cortex altered P300 latencies. These results indicate that rTMS frequency affects cognitive processing. Thus, we suggest that the effects of rTMS vary according to the activity of excitatory and inhibitory neurons in the cerebral cortex.
The effect of corosolic acid (CA) on blood glucose was studied in KK-Ay mice, an animal model of type 2 diabetes. CA (10 mg/kg) reduced the blood glucose (p<0.05) of KK-Ay mice 4 h after single oral ...administration when compared with the control group. However, CA did not change the plasma insulin. The muscle facilitative glucose transporter isoform 4 (GLUT4) translocation from low-density microsomal membrane to plasma membrane was significantly increased in the orally CA-treated mice when compared with that of the controls (p<0.05). These results suggest that the hypoglycemic effect of CA is derived, at least in part, from an increase in GLUT4 translocation in muscle. Therefore, it may be that CA has beneficial effects on hyperglycemia in type 2 diabetes.
Rat hepatic mitochondrial function, including oxidative phosphorylation, fatty acid oxidative capacity, kinetic parameters of carnitine palmitoyltransferase I (CPT I), and sensitivity of CPT I to ...malonyl-CoA inhibition were studied in vitro in isolated mitochondria following Escherichia coli lipopolysaccharide (LPS). The hepatic mitochondrial CPT I in LPS-treated rats showed a lower apparent maximum velocity (Vmax) for palmitoyl-CoA and Ki for malonyl-CoA without changes in apparent Km for palmitoyl-CoA. The rate of oxygen consumption or end-product formation of palmitoyl-L-carnitine and octanoate was not altered, but the rate of CPT I-dependent palmitoyl-CoA (plus L-carnitine) oxidation was reduced by LPS, when acetyl-CoA produced via beta-oxidation was directed toward citrate. When acetyl-CoA was directed to acetoacetate, the oxygen consumption rates of palmitoyl-L-carnitine and palmitoyl-CoA (plus L-carnitine) were decreased by LPS, although mitochondrial 3-hydroxy-3-methylglutaryl-CoA synthase activity was not altered. These results indicate that hepatic mitochondria isolated from LPS-treated rats show lower ketogenic and long-chain acyl-CoA oxidative capacity than those of fasted controls, and inhibition of ketogenesis is elicited at a site distal to CPT I in addition to reduction in CPT I activity.
Hydrolytic mechanisms of family 18 chitinases from rice (Oryza sativa L) and Bacillus circulans WL-12 were comparatively studied by a combination of HPLC analysis of the reaction products and ...theoretical calculation of reaction time-courses. All of the enzymes tested produced (β-anomers from chitin hexasaccharide (GlcNAc)6, indicating that they catalyze the hydrolysis through a retaining mechanism. The rice chitinases hydrolyzed predominantly the fourth and fifth glycosidic linkages from the nonreduc-ing end of (GlcNAc)6, whereas B. circulans chitinase Al hydrolyzed the second linkage from the nonreducing end. In addition, the Bacillus enzyme efficiently catalyzed trans-glycosylation, producing significant amounts of chitin oligomers larger than the initial substrate, but the rice chitinases did not. The time-courses of (GlcNAc)6 degradation obtained by HPLC were analyzed by theoretical calculation, and the subsite structures of the rice chitinases were identified to be(−4)(−3)(−2)(−l)(+l)(+2). From the HPLC profile of the reaction products previously reported Terwisscha van Scheltinga et al (1995) Biochemistry 34,15619-15623, family 18 chitinase from rubber tree (Hevea brasiliensis) was estimated to have the same type of subsite structure. Theoretical analysis of the reaction time-course for the Bacillus enzyme revealed that the enzyme has (−2)(−l) (+l)(+2)(+3)(+4)-type subsite structure, which is identical to that of fungal chitinase from Coccidioides immitis Fukamizo et al (2001) Biochemistry 40, 2448–2454. The Bacillus enzyme also resembled the fungal chitinase in its transglycosylation activity. Minor structural differences between plant and microbial enzymes appear to result in such functional variations, even though all of these chitinases are classified into the identical family of glycosyl hydrolases.
The precursor of matrix metalloproteinase 9 (pro-MMP-9) forms a complex with the tissue inhibitor of metalloproteinases (TIMP)-1 through the C-terminal domain of each molecule, and the N-terminal ...domain of TIMP-1 in the complex interacts and inhibits active MMPs. We have reported that a catalytic amount of MMP-3 (stromelysin 1) activates pro-MMP-9 (Ogata, Y., Enghild, J. J., and Nagase, H.(1992) J. Biol. Chem. 267, 3581-3584). To activate pro-MMP-9 in the complex, however, an excess molar amount of MMP-3 is required to saturate the TIMP-1 in the complex. The aim of this study was to test the hypothesis that the requirement for excess MMP-3 can be circumvented by specific destruction of TIMP-1 by non-target proteinases. We have tested trypsin, plasmin, cathepsin G, neutrophil elastase, and chymotrypsin as possible inactivators of TIMP-1 and found that neutrophil elastase inactivates TIMP-1 in the complex without significant destruction of pro-MMP-9. Once TIMP-1 is inactivated, pro-MMP-9 can be readily activated by a catalytic amount of MMP-3. These results suggest that neutrophil elastase may participate in connective tissue destruction at the inflammatory sites not only by its direct action on matrix macromolecules but also by rendering pro-MMP-9 in the pro-MMP-9·TIMP-1 complex activable by MMP-3 as well as activating pro-MMP-3.
The addition of Ag
2O up to 20 wt.% could reinforce its mechanical strength and led us to grow the
c-axis-oriented single-domain Sm123 superconductors up to a diameter of 36 mm. The trapped field at ...77 K reached 2.1 T and increased to 9 T at 25 K. The maximum trapped field is found to be limited by fracture due to the magnetic stress, which causes the crack to initiate from the region under the seed crystal near the center of the sample with its subsequent propagation through voids. The amount of voids can be substantially reduced when the oxygen partial pressure is increased at the early stage of the melt-processing. The Ba/Sm substitution effect degrades the superconducting performance and lowers the superconducting transition temperature to 80 K only near the central region. The trapped field after drilling a hole through the center of the sample was measured. Its potential use is suggested in practical application.
We developed a new fluorene-based chromophore for a degradation-recoverable polydimethylsiloxane (PDMS) dye laser. The chromophore has dimethylsiloxane chains to enhance its solubility in the PDMS ...matrix. The spectroscopic and mobile characteristics were evaluated, and the attaching of the siloxane/silyl chains improved solubility in PDMS without influencing the laser property. It extended the durability by a factor of 20 for shots in an index-type Bragg grating/PDMS complex laser waveguide compared with a similar fluorene-based chromophore in PMMA laser waveguides. This molecular diffusion not only increased durability but also provided detailed information about dye degradation in waveguides.
Background/Aims: The emergence of lamivudine-resistant hepatitis B virus (HBV) was reported in patients with prolonged lamivudine administration. There was no report of the existence of ...tyrosine–methionine–aspartate–aspartate (YMDD) mutant in non-lamivudine treated chronic hepatitis B patients. In the present study, we developed a sensitive assay and applied it to the detection of YMDD mutant.
Methods: We developed peptide nucleic acid (PNA) mediated polymerase chain reaction clamping for detecting mutations in a YMDD motif of the hepatitis B virus DNA polymerase gene. We studied YMDD mutants in a patient with HBV DNA breakthrough longitudinally and in non-lamivudine treated patients (36 patients).
Results: We could detect as little as 0.01–0.001% of mutant viruses coexisting in 10
5–10
9 copies of wild-type viruses using this assay. YMDD mutant was detected 7 months before clinical breakthrough, which was 6 months earlier than using the conventional restriction fragment length polymorphism assay. YMDD mutants were also detected in four of 18 anti-HBe antibody positive untreated chronic hepatitis type B: YMDD+tyrosine-valine-aspartate-aspartate (YVDD) in two patients and YMDD+tyrosine-isoleucine-aspartate-aspartate (YIDD) in two patients, however, none in HBe antigen positive patients.
Conclusions: We developed a highly sensitive assay for detecting YMDD mutants. This is an effective procedure for monitoring patients during or before lamivudine treatment and can provide more insights into the therapeutic strategies for chronic hepatitis B patients.
Spontaneous regression is sometimes seen in malignant skin tumours. We report a 68‐year‐old woman whose Bowen's disease showed spontaneous complete regression. Prominent infiltration of T cells and ...increased vascularity were found in the upper dermis of the regressed lesion. Strong expression of Fas (APO‐1/CD95) antigen, an apoptosis‐related tumour necrosis factor receptor family protein, in the primary lesion and faint expression following regression suggest the involvement of Fas‐mediated apoptosis in the spontaneous complete regression of our patient's Bowen's disease.
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