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Abstract
Capillary isoelectric focusing is a useful analytical technique for characterization of protein mixtures and determination of protein isoelectric points. It is particularly useful in separation of protein glycoforms (Fig. 5), characterizing protein microheterogeneity (Fig. 6), and resolution of charge variants (Fig. 7). The capillary focusing process is analogous to conventional isoelectric focusing in gels, while the requirement for zone mobilization is unique to the capillary format with on-tube detection. A variety of mobilization methods have been described, and the selection of the mobilization method for a particular application depends on the capillary type, the instrument configuration, and the type of proteins to be analyzed. Capillary IEF is generally successful for proteins with a molecular weight up to about 150,000 that exhibit good solubility in aqueous buffers, but may be unsatisfactory for large or hydrophobic proteins. Because of precipitation and variation in mobilization efficiencies, use of internal standards is recommended in most applications. Capillary IEF can be compared to conventional gel IEF in terms of sample throughput and sensitivity. Conventional gels require approximately 4-6 hr to cast, run, and stain the gel, depending on whether silver or Coomassie staining is used. A typical gel contains 10 sample lanes, yielding a throughput of 25-35 min/sample. Capillary IEF separations (including focusing and mobilization) are typically 15-20 min. The mass sensitivity of conventional gel IEF is 36-47 ng for Coomassie staining and 0.5-1.2 ng for silver staining. In capillary IEF, sensitivity will depend on the volume of sample injected; assuming a capillary with a volume of 100 nl is completely filled with sample prior to focusing, the limit of detection will be approximately 1 microgram/ml or 0.1 ng injected. Thus capillary IEF compares favorably with conventional gel IEF in terms of detectivity and analysis time, and has the additional benefit of complete automation of the process including separation and data reduction.
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602
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Zhu M, Babbitt WR, Jefferson CM. Continuous coherent transient optical processing in a solid. OPTICS LETTERS 1995; 20:2514. [PMID: 19865270 DOI: 10.1364/ol.20.002514] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
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603
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Liu YL, Feng XP, Zhu M. [Inhibitory effect of green tea polyphenols varnish on oral main cariogenic bacteria.]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 1995; 4:198-200. [PMID: 16538358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
This study observed the bacteriostatic effect of green tea polyphenols varnish,found green tea polyphenols varnish had significant inhibitory action on Streptococcus mutans,Streptococcus sobrinus and Lactobacilli.growth test showed the growth inhibitory rate of S.mutans and S.sobrinus was positive proportion with the concentration of green tea polyphenols varnish,demonstrated green tea polyphenols varnish possess certain anticariogenic effect.
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604
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Duan L, Zhu M, Bagasra O, Pomerantz RJ. Intracellular immunization against HIV-1 infection of human T lymphocytes: utility of anti-rev single-chain variable fragments. Hum Gene Ther 1995; 6:1561-73. [PMID: 8664381 DOI: 10.1089/hum.1995.6.12-1561] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Genetic therapy offers a potentially promising approach with which to combat human immunodeficiency virus type 1 (HIV-1) infections. Several modalities, using protein- and RNA-based systems, have recently been shown to inhibit HIV-1 replication. A single-chain variable fragment (SFv), constructed from the cDNA of a monoclonal antibody to the HIV-1 regulatory protein Rev, has been demonstrated to potently inhibit HIV-1 replication, when expressed intracellularly in an epithelial cell-line (HeLa-CD4). Murine retroviral shuttle vectors, which express the anti-Rev SFv moiety, have now been constructed. HIV-1 infection was dramatically inhibited in human T-lymphocytic cell-lines, CEM and Sup-T1, transduced with these anti-Rev SFv-expressing vectors. This resistance to high levels of HIV-1 expression was demonstrated in both mixed populations and clones of these cells. Of further potential clinical significance, HIV-1 infection was also potently inhibited in human peripheral blood mononuclear cells (PBMC), transduced with retroviral vectors expressing the anti-Rev SFv molecule. These data suggest that intracellular expression of anti-Rev SFvs, or related approaches, may be utilized as genetic therapy, or intracellular immunization, for HIV-1 infections in vivo.
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605
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Shi NN, Zhu M, Chen J, Stratford R, Wilson TM, Antoniw JF, Foulds IJ, MacFarlane SA, Adams MJ. Molecular characterisation of UK isolates of barley yellow mosaic bymovirus. Virus Res 1995; 38:193-204. [PMID: 8578858 DOI: 10.1016/0168-1702(95)00057-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Several isolates of barley yellow mosaic virus (BaYMV) from different sites in the UK, including some that were virulent on European resistant winter barley cultivars (resistance-breaking strain: BaYMV-2) and some that were not, were examined by RT-PCR, restriction mapping and sequencing of selected parts of the virus genome. Nucleotide and predicted amino acid sequences were determined for the 5'-terminal region, part of the NIa coding region and the coat protein coding region on RNA 1 and an area at the N-terminus of the 70-kDa protein coding region on RNA 2. The sequences differed from those previously reported for a BaYMV isolate from Japan and for two German isolates, one of which was of the BaYMV-2 strain. There were no strain-specific amino acid differences and the few, non-consecutive, nucleotide differences detected were probably not significant and were insufficient to develop a rapid diagnostic test to distinguish BaYMV-2 from other isolates. Restriction mapping of RNA 2 cDNA again showed no consistent strain-related differences. The differences previously reported between the two German isolates are probably not strain-related.
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606
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Zaharakis KE, Haar RR, Woitke O, Zhu M, Tanis JA, Badnell NR. Recombination in Kr34++H2 collisions. PHYSICAL REVIEW. A, ATOMIC, MOLECULAR, AND OPTICAL PHYSICS 1995; 52:2910-2914. [PMID: 9912575 DOI: 10.1103/physreva.52.2910] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
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607
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Heilig CW, Concepcion LA, Riser BL, Freytag SO, Zhu M, Cortes P. Overexpression of glucose transporters in rat mesangial cells cultured in a normal glucose milieu mimics the diabetic phenotype. J Clin Invest 1995; 96:1802-14. [PMID: 7560072 PMCID: PMC185817 DOI: 10.1172/jci118226] [Citation(s) in RCA: 183] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
An environment of high glucose concentration stimulates the synthesis of extracellular matrix (ECM) in mesangial cell (MC) cultures. This may result from a similar increase in intracellular glucose concentration. We theorized that increased uptake, rather than glucose concentration per se is the major determinant of exaggerated ECM formation. To test this, we compared the effects of 35 mM glucose on ECM synthesis in normal MCs with those of 8 mM glucose in the same cells overexpressing the glucose transporter GLUT1 (MCGT1). Increasing medium glucose from 8 to 35 mM caused normal MCs to increase total collagen synthesis and catabolism, with a net 81-90% increase in accumulation. MCs transduced with the human GLUT1 gene (MCGT1) grown in 8 mM glucose had a 10-fold greater GLUT1 protein expression and a 1.9, 2.1, and 2.5-fold increase in cell myo-inositol, lactate production, and cell sorbitol content, respectively, as compared to control MCs transduced with bacterial beta-galactosidase (MCLacZ). MCGT1 also demonstrated increased glucose uptake (5-fold) and increased net utilization (43-fold), and greater synthesis of individual ECM components than MCLacZ. In addition, total collagen synthesis and catabolism were also enhanced with a net collagen accumulation 111-118% greater than controls. Thus, glucose transport activity is an important modulator of ECM formation by MCs; the presence of high extracellular glucose concentrations is not necessarily required for the stimulation of matrix synthesis.
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608
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Green NS, Rabinowitz JL, Zhu M, Kobrin BJ, Scharff MD. Immunoglobulin variable region hypermutation in hybrids derived from a pre-B- and a myeloma cell line. Proc Natl Acad Sci U S A 1995; 92:6304-8. [PMID: 7603987 PMCID: PMC41506 DOI: 10.1073/pnas.92.14.6304] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Somatic mutation of the variable (V) regions of immunoglobulin genes occurs in vivo at rates that have been estimated to be between 10(-3) and 10(-4) per bp per generation. To study this process in vitro, the 18.81 pre-B-cell line and hybrids derived by fusing 18.81 to the NSO myeloma fusion partner were transfected with a mu heavy-chain construct containing a nonsense mutation in the V region (Vn) or the constant region (Cn). Mutation was quantitated by reversion analysis using the ELISA spot assay to detect single cells secreting IgM. Fluctuation analysis revealed that V-region mutations spontaneously occurred in 18.81 cells at an average rate of 5.8 x 10(-6) per bp per cell generation and in selected 18.81-NSO hybrids at greatly increased rates of 1.6 x 10(-3) to 5.8 x 10(-4) per bp per generation. The Vn construct also reverted frequently in transgenic mice, indicating that it contained sufficient information to mutate at high rates both in vivo and in vitro. Sequence analysis of reverted genes revealed that reversion was due to point mutations. Since the rates and nature of the mutations that are occurring in these transfected genes are similar to those reported in vivo, it should be possible to use this system to identify the cis-acting sequences and trans-acting factors that are responsible for V-region somatic hypermutation.
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609
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Yu Y, Ma Y, Xia T, Ma S, Zhu M, Wan F, Wang Y. [Action of Rhodobrum roserm Limpr on changes of red cell aggregation and yield-shear stress in dogs with acute experimental coronary occlusion]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1995; 20:429-31, 449. [PMID: 7576145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Following acute occlusion of the left anterior descending coronary artery in dogs, significant increases were observed in the red cell aggregation index, yield-shear stress and red cell electrophoretic time in blood drained from ischemic area. When transfusion was performed with Rhodobrum roseum solution from the right femoral vein, significant rises of the above-said items were observed.
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610
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Zhu M, Spink DC, Yan B, Bank S, DeCaprio AP. Inhibition of 2,5-hexanedione-induced protein cross-linking by biological thiols: chemical mechanisms and toxicological implications. Chem Res Toxicol 1995; 8:764-71. [PMID: 7548760 DOI: 10.1021/tx00047a017] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
n-Hexane is metabolized to the gamma-diketone 2,5-hexanedione (2,5-HD), a derivative that covalently binds to lysine residues in neurofilament (NF) protein to yield 2,5-dimethylpyrrole adducts. Studies comparing the pyrrole-forming potential and neurotoxic potency of gamma-diketones have demonstrated that pyrrolylation is an absolute requirement in the neuropathogenesis. Autoxidative cross-linking of pyrrolylated NF proteins occurs and is proposed as a second required event. In the present study, the role of nucleophilic thiols and amines in the pyrrole-mediated cross-linking reaction was investigated. When pyrrolylated ribonuclease was incubated with N-acetyllysine, N-acetylcysteine, or glutathione in physiologic buffer (pH 7.4) under air, pyrrole-to-pyrrole cross-linking was inhibited only by the thiol-containing compounds. Stable thiol--pyrrole conjugates containing a bridge from the pyrrole ring at C-3 to the sulfur atom of the thiol were characterized by thermospray LC/MS and 1H-NMR spectroscopy. In contrast to low-molecular-mass thiols, SDS--PAGE studies indicated that, under the same incubation conditions, free thiols present in proteins did not undergo reaction with pyrrole adducts to form cross-links. Further experiments using a low-molecular-mass pyrrole derivative indicated that glutathione may also able to suppress pyrrole dimerization without conjugate formation, possibly via inhibition of a free radical-dependent mechanism. The results suggest the following: (1) 2,5-HD-induced protein cross-linking is mediated primarily by pyrrole-to-pyrrole bridging under physiologic conditions, and (2) glutathione and other low-molecular-mass thiols may inhibit the pyrrole dimerization reaction by two distinct pathways. These findings have significant implications for the mechanism of gamma-diketone neuropathy.
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611
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Okauchi N, Mizuno A, Zhu M, Ishida K, Sano T, Noma Y, Shima K. Effects of obesity and inheritance on the development of non-insulin-dependent diabetes mellitus in Otsuka-Long-Evans-Tokushima fatty rats. Diabetes Res Clin Pract 1995; 29:1-10. [PMID: 8593753 DOI: 10.1016/0168-8227(95)01114-s] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We studied whether obesity or inheritance was the more important factor in the development of non-insulin-dependent diabetes mellitus (NIDDM) using female Otsuka-Long-Evans-Tokushima Fatty rats (OLETF) possessing one of the diabetic genes, ODB-1, and male Long-Evans-Tokushima-Otsuka rats (LETO) possessing no ODB-1, neither of which were diabetic when bred normally. Diabetes-resistant male LETO rats and female OLETF rats (4 weeks old) were assigned to three groups of 6 rats each, respectively; two groups in which obesity was induced by high calorie 'cafeteria' diet (D), or ventromedial hypothalamus lesions (V) with normal chow diet and a control group fed on normal chow (C). Six male OLETF rats were used as NIDDM positive controls. The mean daily energy intakes of obese male LETO and female OLETF rats were higher than those of the respective C groups. At 27 weeks of age, the average body weights of the obese LETO and female OLETF rats were significantly higher than those of the respective C groups and similar to that of the male OLETF group. Abdominal fat deposits of the obese groups were significantly higher than those of the respective C groups. At 28 weeks of age, the cumulative incidence of diabetes mellitus in obese LETO rats was 0% in group D and 17% in group V, while that of obese female OLETF rats in groups D and V were 100%. At 29 weeks of age, the plasma immunoreactive insulin (IRI) responses to glucose in obese female OLETF rats, groups D and V, were higher than that in group C. In obese LETO rats, insulin-stimulated glucose disposal in vivo was similar to that in group C, but in obese female OLETF rats, it was reduced to 41% in group D and 37% in group V of that in group C. Sections of islets of the pancreas of obese LETO rats appeared histologically normal, whereas those of obese female OLETF rats showed enlarged multilobulated fibrotic islets. These results demonstrate that obesity is necessary, but not sufficient alone for the development of NIDDM in these rat models.
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612
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Zhu M, Rabinowitz JL, Green NS, Kobrin BJ, Scharff MD. A well-differentiated B-cell line is permissive for somatic mutation of a transfected immunoglobulin heavy-chain gene. Proc Natl Acad Sci U S A 1995; 92:2810-4. [PMID: 7708729 PMCID: PMC42308 DOI: 10.1073/pnas.92.7.2810] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
pSV2neo plasmids containing an IgM heavy-chain gene with nonsense mutations in either the variable (V) or the constant (C) region were transfected into four differentiated mouse plasma cell lines: S107 and the NSO fusion partner (myeloma cell lines) and 2C3 and 36.65 (hybridoma cell lines). The frequencies of reversion of the nonsense mutations in multiple independent transfectants were determined with the spot ELISA and rates of reversion were calculated by fluctuation analysis. Mutations in both V and C regions were confirmed by sequence analyses. In the S107 cell line, spontaneous point mutations occurred in the V region at a rate of approximately 5 x 10(-5)/bp per cell generation, > 400-fold higher than the rate of V-region mutation in the NSO cell line and considerably higher than the rates in 2C3 and 36.65 hybridoma cell lines. These studies suggest that S107 is a relatively permissive cell line in which V-region mutations can occur constitutively, even though it represents a late stage of B-cell differentiation. Further, the results show that the construct used contains sufficient information in its flanking and coding sequences to allow a relatively high rate of V-region mutation, at least in the S107 cell line.
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613
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Okauchi N, Mizuno A, Yoshimoto S, Zhu M, Sano T, Shima K. Is caloric restriction effective in preventing diabetes mellitus in the Otsuka Long Evans Tokushima fatty rat, a model of spontaneous non-insulin-dependent diabetes mellitus? Diabetes Res Clin Pract 1995; 27:97-106. [PMID: 7607057 DOI: 10.1016/0168-8227(95)01029-d] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Studies were made on the effectiveness of caloric restriction in preventing the development of diabetes mellitus in a model rat (Otsuka-Long-Evans-Tokushima Fatty; OLETF) with non-insulin-dependent diabetes mellitus (NIDDM). Groups of 8 male OLETF rats aged 5 weeks were supplied with rat chow ad libitum (100% group) and 85% and 70% of the amount of food consumed by the 100% group (85% and 70% groups, respectively). The average weights of the 100%, 85% and 70% groups were 617, 536 and 450 g at 19 weeks of age and their abdominal fat deposits were 50, 38 and 21 g, respectively, at 22 weeks of age when they were killed. At 20 weeks of age, the cumulative incidences of diabetes mellitus in the 100%, 85% and 70% groups were 67%, 13% and zero, respectively. The plasma immunoreactive insulin (IRI) levels 60 and 120 min after oral glucose administration were significantly lower in the 70% group than in the other groups. In vivo insulin-stimulated glucose uptake measured by a euglycemic clamp technique, was significantly higher in the 70% group than in the 100% group. There was no significant difference in the glucose transporter 4 protein levels of skeletal muscles in the three groups, but the highest ratio of glucose transporter 4 in the plasma membrane to that in intracellular membranes was observed in the 70% group. Morphological studies on the pancreas of rats in the 100% group showed enlarged multilobulated fibrotic islets, whereas sections of islets of rats in the other groups appeared normal, though slightly enlarged. These results demonstrate that caloric restriction is effective in preventing NIDDM in diabetes-prone rats, probably due to increased insulin sensitivity.
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614
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Zhu M, Fecht HJ. Softening effect in nanocrystalline FeCu supersaturated solid solutions. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/0965-9773(95)00210-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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615
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Liang JP, Zhu M, Ogami T, Tatsumi H. [Applied DNA-DNA hybridization in determination of oral Streptococcus.]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 1994; 3:158-9. [PMID: 16538316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Quantitative measurement of DNA-DNA hybridization is a new technique for determination of unknown bacteria.It is more valuable how to identify strains which is rare difference on phenotypic characteristics.It is important to resolve bactericial taxionmy and identify new strain.Four strain of Streptiococcus are determined by hybridization of DNA.Some technique problems are discussed.Such as purification,precision of DNA and temperature as well as time of DNA hybridization and standard of judgment.
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616
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Grinnell F, Zhu M. Identification of neutrophil elastase as the proteinase in burn wound fluid responsible for degradation of fibronectin. J Invest Dermatol 1994; 103:155-61. [PMID: 8040604 DOI: 10.1111/1523-1747.ep12392625] [Citation(s) in RCA: 75] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
To identify proteinases responsible for fibronectin degradation in the wound environment we studied wound fluid obtained from burn patients. Immunoblotting experiments showed that extensive degradation of fibronectin had occurred in some burn wound fluid samples, in which case intact fibronectin molecules were undetectable, and the largest fibronectin fragment was 116 kDa. The 116-kDa fragment as well as a smaller 90-kDa fragment contained the fibronectin cell binding domain. These burn-fluid samples degraded freshly added fibronectin. Activity of the fibronectin-degrading enzyme was blocked by a broad-spectrum serine proteinase inhibitor or by specific neutrophil elastase inhibitors but not by metalloproteinase inhibitors or inhibitors of trypsin-like or chymotrypsin-like serine proteinases. Enzyme activity also was neutralized by antibodies against human neutrophil elastase. Incubation of fibronectin with burn wound fluid or purified human neutrophil elastase generated similar fibronectin-degradation products. Finally, direct assay of burn-wound-fluid samples with a synthetic elastase substrate showed a correlation between fluid-phase elastase activity and fibronectin degradation. Based on these findings, we conclude that burn-wound-fluid elastase is responsible for extensive fibronectin degradation. Acute elevation of elastase did not appear to hinder normal wound repair.
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617
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Zhu M, Spink DC, Yan B, Bank S, DeCaprio AP. Formation and structure of cross-linking and monomeric pyrrole autoxidation products in 2,5-hexanedione-treated amino acids, peptides, and protein. Chem Res Toxicol 1994; 7:551-8. [PMID: 7981420 DOI: 10.1021/tx00040a011] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
2,5-Hexanedione (2,5-HD) is the neurotoxic gamma-diketone metabolite of the industrial solvent n-hexane. Substantial evidence indicates that 2,5-HD reacts with neurofilament protein lysine epsilon-amines to yield 2,5-dimethylpyrrole adducts and that this reaction is critical to the mechanism of toxicity. Alkylpyrroles are susceptible to autoxidative dimerization, a process that has also been suggested as an obligatory step in 2,5-HD neuropathy. In the present study, we characterized pyrrole autoxidation products of a 2,5-HD-treated lysine analogue and of a model, lysine-containing dipeptide and examined mechanistic aspects of pyrrole-mediated protein cross-linking. Incubation of 2,5-HD with N alpha-acetyllysine or the dipeptide N alpha-acetylglycyllysine methyl ester in physiological buffer (pH 7.4) under oxidative conditions resulted in time-dependent formation of the N epsilon-pyrrole derivative and two major pyrrole autoxidation products, as demonstrated by HPLC, on-line thermospray MS, and UV photodiode array detection. An autoxidative pyrrole dimer containing a methylene bridge between C-2 of one pyrrole ring and C-3 of a second ring was characterized by thermospray MS and 1H-NMR spectroscopy. 13C-NMR spectroscopy provided evidence for an identical pyrrole-to-pyrrole bridge in autoxidized, pyrrolylated ribonuclease (RNase). MS analysis also revealed a second major product--a stable, oxygen-containing monomeric pyrrole derivative. This product exhibited a UV absorbance maximum (lambda max = 355 nm) consistent with extended conjugation. Polymerization of pyrrolylated acetyllysine was accelerated by persulfate, a free-radical initiator, and inhibited by ascorbate, an antioxidant.(ABSTRACT TRUNCATED AT 250 WORDS)
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618
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Zhu M, Qi M, He A, Sui H, Liu W. Transmission electron microscopy on the process of mechanical alloying in NiTi binary systems. ACTA ACUST UNITED AC 1994. [DOI: 10.1016/0956-7151(94)90014-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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619
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Zhou Z, Zhu M, Wu X, Qian D. Chain transfer grafting of butyl acrylate onto poly(vinyl chloride) in emulsion. POLYMER 1994. [DOI: 10.1016/0032-3861(94)90325-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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620
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Abstract
A quantitative serial sectioning technique and a video-imaging procedure were used to obtain precise (20-microns voxels, in a 5 mm x 6 mm x 7 mm test volume) digital images of lumbar vertebral cancellous bone specimens. Conventional stereological image analyses were performed on this data to determine multiplanar (bulk) and surface planar variations in cancellous structural properties. Based upon an error analysis of subgroups of the complete serial planar images, our findings suggest that, for a plane resolution of 20 microns, sectioning at an increment < or = 100 microns along an axis is necessary to obtain accurate data of bulk structural properties of cancellous bone. Planar structural variations obtained from the serial sections of cancellous bone revealed a high degree of complexity and heterogeneity of the bone architecture. Bone area centers deviated from the section centroid and showed a helical variation along the primary or superior--inferior loading axis of samples. In comparison with the base planes (perpendicular to the superior-inferior axis), the lateral planes (parallel to the superior-inferior axis) of spine samples showed smaller mean values of structural indices and a more oriented structure. This structural anisotropy may be related to the functional mechanical anisotropy of the samples.
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621
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Zhu M, Hirayama K, Kapatos G. Regulation of tetrahydrobiopterin biosynthesis in cultured dopamine neurons by depolarization and cAMP. J Biol Chem 1994; 269:11825-9. [PMID: 7512954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Primary cultures containing embryonic rat brain mesencephalic or hypothalamic dopamine neurons were used to examine the effects of membrane depolarization and elevations of cAMP levels on tetrahydrobiopterin cofactor content. Initial studies showed that 24-h incubations with 8-bromo-cAMP or isobutyl methylxanthine increased cofactor levels in either culture system, whereas the stimulatory effects of forskolin or depolarization of membrane potential were only observed in cultures of hypothalamus. 8-Bromo-cAMP was found to increase cofactor content in a concentration-dependent manner, with increases observed up to 5 mM. The time course of the effect of 8-bromo-cAMP was biphasic. Over the short term, an increase of 50% in cofactor content at 2 and 5 h was detected. Over the long term, by 24-48 h, cofactor levels increased by between 100% and 300%. Studies of cofactor turnover indicated that the long-term increase was due to stimulation of tetrahydrobiopterin biosynthesis with no alteration in degradation rate. Inhibitors of gene transcription and translation prevented the long- but not short-term increase in cofactor content. Levels of GTP cyclohydrolase I mRNA were increased 7-10-fold following 5 h of incubation with 8-bromo-cAMP. Tetrahydrobiopterin biosynthesis within cultured dopamine neurons of the hypothalamus and mesencephalon thus appears to be regulated by a cAMP-dependent mechanism involving enhanced gene expression of enzyme(s) involved in cofactor biosynthesis.
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622
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Zhu M, Keller TS, Spengler DM. Effects of specimen load-bearing and free surface layers on the compressive mechanical properties of cellular materials. J Biomech 1994; 27:57-66. [PMID: 8106536 DOI: 10.1016/0021-9290(94)90032-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The influence of load-bearing surface layers on Young's modulus was determined for cancellous bone and polyurethane foam specimens of three different heights cut from each material: 16, 9, and 5 mm for bone specimens (cross-sectional area A = 81 mm2) ranging in density from 0.04 to 0.32 g cm-3; 20, 10, and 5 mm for foam specimens (A = 100 mm2) ranging in density from 0.064 to 0.64 g cm-3. The compressive elastic modulus of the 5 mm bone specimens was significantly smaller (42%) than that of the 16 mm bone specimens. A similar change in elastic modulus was also observed for the foam specimens, but the height effect diminished in a relatively linear manner as the foam density increased. For a height change from 20 to 5 mm, the foam modulus difference ranged from a 41% decrease for the lowest density specimens (p = 0.064 g cm-3) to an insignificant change (< 1.8%) for the highest foam density specimens (p = 0.64 g cm-3). The specimen height effect on elastic modulus was hypothesized to result from a higher deformation (compliance) of the cellular materials in the load-bearing or contacting surface layer than in the bulk. A mathematical formula was derived to predict the variation in measured elastic modulus (E) caused by the contacting surface layer modulus (Ecs) to bulk modulus (Eb) ratio (Y = Ecs/Eb) and contacting surface layer height (hcs) to sample height (h) ratio (t = hcs/h): E/Eb = Y/[Y(1-t)+t]. Predicted differences in the measured modulus associated with graduated specimen heights were verified experimentally by regional strain measurements of the foam and bone samples using an optical microscope. The influence of free-surface layers was also determined for the foam specimens with cross-sectional areas 1.21 and 10 times the load-bearing area of a load platen, but the measured differences were small (< 10%) compared to that of the load-bearing surface layer influence. In future compressive mechanical testing of cellular materials, specimens < 10 mm in height should be avoided, particularly specimens with low bulk density or high porosity.
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623
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Yan R, Zhu M, Zhong J. [Effects of "moist burn ointment--mei bao" on production of IL-2 in burn rats and its clinical problems]. ZHONGHUA ZHENG XING SHAO SHANG WAI KE ZA ZHI = ZHONGHUA ZHENG XING SHAO SHANG WAIKF [I.E. WAIKE] ZAZHI = CHINESE JOURNAL OF PLASTIC SURGERY AND BURNS 1994; 10:15-8. [PMID: 8087682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Since "Mei Bao" has been used in clinical treatment of burn wounds, there is a diversity of opinions concerning its effect. We carried out a series of experiments to observe its therapeutic effect, bacteriostatic property, and its effect on production of IL-2 in thermally injured rats. These results indicate that obvious infection occurred after its use on burn wounds and healing is delayed. Hyperplastic scars accompanying with deformity appeared after healing. The cost of treatment is high. There is no improvement in immune reaction, and no bacteriostatic property is observed.
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624
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Cui LS, Chen YL, Qi M, Zhu M, Yang DZ. Phase transition of NiTi intermetallic compound induced by ball milling and subsequent heat treatment. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf00278011] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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625
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Qi M, Zhu M, Yang DZ. On the supersaturated solution in the Fe-Cu binary system induced by high energy ball milling. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf00701439] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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