[Long-term follow-up of mitomycin C in trabeculectomy].
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Biomedical subjects
Publications and source records attributed to B Jiang.
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Efforts have been made to characterize the mechanical properties of carbon nanotubes. Previous work has concentrated on the tubes' longitudinal properties, and studies of their radial properties have lagged behind. We have used a scanning probe microscope with an indentation/scratch function to investigate the radial compression of multiwalled carbon nanotubes under an asymmetric stress. In particular, we have determined the radial compressive elastic modulus at different compression levels and have estimated the compressive strength to be well beyond 5.3 GPa.
The inhibitory effects of Chinonin, a natural antioxidant extracted from a Chinese medicine, on apoptotic and necrotic cell death of cardiomyocytes in hypoxia-reoxygenation process were observed in this study. The possible mechanisms of Chinonin on scavenging reactive oxygen species and regulating apoptotic related genes bcl-2 and p53 were also investigated. Neonatal rat cardiomyocytes were subjected to 24-h hypoxia and 4-h reoxygenation. Cell death was evaluated by DNA electrophoresis on agarose gel, cell death ELISA and annexin-V-FLUOS/propidium iodide (PI) double staining cytometry. Hypoxia caused the increase of apoptotic rates and the release of lactate dehydrogenase (LDH), while reoxygenation not only further increased the apoptotic rates and leakage of LDH, but also induced necrosis of cardiomyocytes. In addition, hypoxia increased the levels of NO(2)(-)/NO(3)(-) and thiobarbituric acid reacted substances (TBARS), while reoxygenation decreased NO(2)(-)/NO(3)(-), but further increased TBARS in the cultured media. Moreover, hypoxia up-regulated the expression levels of bcl-2 and p53 proteins, while reoxygenation down-regulated bcl-2 and further up-regulated p53. Chinonin significantly decreased the rates of apoptotic and necrotic cardiomyocytes, and inhibited the leakage of LDH. It also diminished NO(2)(-)/NO(3)(-) and TBARS, down-regulated the expression level of p53 protein, and up-regulated bcl-2 protein, respectively. The results suggest that Chinonin has preventive effects against apoptotic and necrotic cell death and its protective mechanisms are related to the antioxidant properties of scavenging nitric oxide and oxygen free radicals, and the modulating effects on the expression levels of bcl-2 and p53 proteins.
A new diterpenoid was isolated from the leaves of Isodon lophanthoides, together with two known diterpenoids, lophanic acid and 8(17),12,14-labdatriene-19-oic acid. The structure of the new compound was determined to be 11 beta-hydroxyisopimara-8,15-diene-3-one (1) on the basis of spectroscopic evidence.
A new ent-kaurane diterpenoid, phyllostachysin C (1), together with five known compounds, sculponeatins B and C, nodosin, ursolic acid and 2 alpha-hydroxyursolic acid, were isolated from the leaves of Isodon phyllostachys. The structure of 1 was elucidated on the basis of its spectral properties.
Five caffeoylquinic acids and esters (1-5), including a new compound, 3,5-dicaffeoylquinic acid butyl ester (5), were isolated from the flowers and buds of Lonicera japonica and their structures were determined by NMR spectral analysis.
Nine phenolic compounds, including a new one, were isolated from 70% acetone extract of Craspedolobium schochii. The new compound was identified as 3-(3,4-dimethoxy-2-hydroxyphenyl)-7-hydroxy-coumarin (1) on the basis of spectroscopic evidence.
Activation of phosphatidylinositol 3-kinase (PI 3-kinase) or of Akt induces myoblast differentiation. Activation of p38 MAP kinase also triggers myogenic differentiation. The current paper shows that PI 3-kinase and p38 MAP kinase signalling are activated by two separate pathways during myogenic differentiation; both are required for muscle differentiation. p38-induced myogenic differentiation can be inhibited by the PI 3-kinase inhibitor LY294002 without affecting p38 activity. Similarly, a constitutively active form of Akt, myristylated c-Akt (Myr-Akt), induces myogenic differentiation that is inhibited by the p38 inhibitor SB203580. An analysis of the two forms of p38, p38 and p38beta, shows that the activity of both is required for myogenic differentiation. These data suggest that PI 3-kinase and p38 signalling are essential and parallel pathways for myogenic differentiation. They may either affect different downstream targets required for myogenesis or they may converge on shared targets that require input from both signalling pathways.
2,4-Bis(3'-indolyl)thiazoles, 3,5-bis(3'-indolyl)-2(1H)pyrazinone and 3,6-bis(3'-indolyl)pyrazine were synthesized and evaluated for cytotoxic activity against diverse human cancer cell lines by the National Cancer Institute. These compounds demonstrated significant inhibitory effects in the growth of a range of cancer cell lines. 2,4-Bis(3'-indolyl)thiazole displayed selective cytotoxicity against certain leukemia cell lines with GI50 values in the low micromolar range while the substituted derivatives showed a broad spectrum of cytotoxic activity. 3,5-Bis(3'-indolyl)-2(1H)pyrazinone and 3,6-bis[3'-(N-methyl-indolyl)]pyrazine possessed strong inhibitory activity against a wide range of human tumor cell lines. The mechanism of action remained unknown. The results suggested that 2,4-bis(3'-indolyl)thiazoles, 3,5-bis(3'-indolyl)-2(1H)pyrazinone and 3,6-bis[3'-(N-methyl-indolyl)] pyrazine offer potential as lead compounds for the discovery of anticancer agents.
Novel hen egg phosvitin phosphopeptides (PPP) with molecular masses of 1-3 kDa were prepared from tryptic hydrolysis following partial alkaline dephosphorylation. The phosvitin treated with various NaOH concentrations (0.05-0.4 N) resulted in different dephosphorylated proteins ranging from 17.5 to 96.3% of phosphate retention. The protein was digested into 10-20 amino acid peptides with trypsin. Calcium-binding properties of PPP were compared with those of commercial casein phosphopeptides in vitro. The PPP with 35% phosphate retention is shown to be effective for enhancing calcium binding capacity and inhibiting the formation of insoluble calcium phosphate. The results provide potential novel functional oilgophosphopeptides as nutraceuticals.
Three new 7,20:14,20-diepoxy-ent-kaurane diterpenoids, xerophilusins A-C (1-3), together with a known one, macrocalin B (4), were isolated from the leaves of Isodon xerophilus. Their structures were elucidated on the basis of their spectral properties and X-ray crystallographic analysis. Compounds 1, 2, and 4 showed significant cytotoxic activity against K562, HL-60, and MKN-28 cells.
The terminal nucleotide sequences of group C Cowden rotavirus gene segments 1-4 were determined. When compared with the published sequences, we found 14 to 29 additional nt at the 5' ends of the four reported gene sequences. For the 3' ends, we observed an additional 16 nt in gene 2 and 14 fewer nt in gene 4.
We report a study on resonance enhanced multiphoton ionization photoelectron spectroscopy (REMPI-PES) involving the fast predissociative A state of ammonia, using nano- and femtosecond lasers. The multiphoton scheme involves (1 + 1), (2 + 2), (2 + 2) + 1 and (2 + 2) + 2 photon processes. We have found a progression of stretching vibrations v1 in the PE spectrum when pumping NH3 A v2 = 0, 1 and 3 as intermediate states. The stretching vibration intensity distributions in the photoelectron spectrum are calculated by using the Chebychev method of the wavepacket propagation. The femtosecond spectrum shows a similar feature to the nanosecond spectrum. However, high laser power also causes band broadening and shifting effect as well as above threshold multiphoton ionization.
Colebroside A (1), a new diglucoside of fatty acid ester of glycerin, was isolated from the aerial parts of Clerodendrum colebrookianum Walp., along with nine known compounds (2-10). Their structures were elucidated by spectroscopic and chemical methods. Compounds 2, 3, 4, 5, 7, 8, 9 and 10 have been obtained from this plant for the first time.
The nucleotide sequences of internal transcribed spacer (ITS) regions of rRNA genes of 24 isolates of Histoplasma capsulatum were examined. The results indicate that the sequences of ITS regions in different isolates are not identical. Sequence variations were found at 20 positions in the 496 bp that were sequenced. Ten different sequence patterns, designated types A through H, were observed when the sequences from the 24 isolates were aligned. Twelve isolates from Indianapolis were classified into four different types. Two isolates from New York belonged to type G. Three isolates from different cities were type F. The remaining six isolates were of different types.
The activation of Nef-associated kinase (NAK) by Nef from human and simian immunodeficiency viruses is critical for efficient viral replication and pathogenesis. This induction occurs via the guanine nucleotide exchange factor Vav and the small GTPases Rac1 and Cdc42. In this study, we identified NAK as p21-activated kinase 1 (PAK1). PAK1 bound to Nef in vitro and in vivo. Moreover, the induction of cytoskeletal rearrangements such as the formation of trichopodia, the activation of Jun N-terminal kinase, and the increase of viral production were blocked by an inhibitory peptide that targets the kinase activity of PAK1 (PAK1 83-149). These results identify NAK as PAK1 and emphasize the central role its kinase activity plays in cytoskeletal rearrangements and cellular signaling by Nef.
OBJECTIVE: The brain modulates the immune system in an asymmetrical way, as shown by the association between paw preference and immune response in the mouse. We predicted that the production of cytokines, which are one of the molecular pathways for brain-immune interactions, should be linked to lateralization in a strain-dependent manner. METHODS: We therefore measured plasma levels of interleukin (IL)-1beta and IL-6 after an intraperitoneal injection of lipopolysaccharide (LPS) in two strains of mice (C3H and BALB/c) that were selected for their different profiles of cytokine production. RESULTS: Plasma levels of IL-1beta and IL-6 increased after LPS injection in both strains and this increase was dependent on paw preference in BALB/c but not in C3H mice. Increased levels of IL-1beta were observed in left-pawed and ambidextrous but not in right-pawed mice. For IL-6, the LPS-induced increase was higher in ambidextrous than in left- and right-pawed animals. CONCLUSION: Cytokines may represent one of the factors responsible for interindividual differences in brain-immune interactions.
We have reported previously that N-acetyl-L-cysteine facilitated interleukin-1beta-induced nitric oxide synthase (iNOS) expression in rat vascular smooth muscle cells. The present study compares the effect of N-acetyl-L-cysteine with other antioxidants and tested the possibility that N-acetyl-L-cysteine potentiates iNOS induction by a mechanism involving activation of p44/42 mitogen-activated protein kinases (MAPKs). The effect of N-acetyl-L-cysteine on potentiating interleukin-1beta-induced nitrite production and iNOS expression was mimicked either by the enantiomers, L-cysteine and D-cysteine, or by a non-thiol-containing antioxidant, L-ascorbic acid. Interleukin-1beta activated p44/42 MAPK, and this activation was enhanced in the presence of N-acetyl-L-cysteine. Inhibition of p44/42 MAPK phosphorylation by the selective inhibitor PD98059 clearly inhibited iNOS expression induced by interleukin-1beta either in the absence or in the presence of N-acetyl-L-cysteine. These observations, combined with previous results, indicate that p44/42 MAPK activation is required for interleukin-1beta induction of iNOS and that N-acetyl-L-cysteine may act as a reducing agent and facilitate interleukin-1beta-induced iNOS expression through a reduction/oxidation-related mechanism involving potentiation of cytokine activation of the p44/42 MAPK signaling pathway.