901
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Wick MJ, Minnerath SR, Lin X, Elde R, Law PY, Loh HH. Isolation of a novel cDNA encoding a putative membrane receptor with high homology to the cloned mu, delta, and kappa opioid receptors. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1994; 27:37-44. [PMID: 7877452 DOI: 10.1016/0169-328x(94)90181-3] [Citation(s) in RCA: 193] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
A rat brain cDNA library was screened for clones homologous to the recently cloned mouse delta-opioid receptor (DOR-1). Among the clones isolated was Hyp 8-1, a clone with a unique nucleotide sequence capable of encoding a putative protein which is 57-58% identical to the amino acid sequences of the cloned delta, mu and kappa opioid receptors, indicating a close relationship of Hyp 8-1 with the opioid receptor family. Several cDNAs representing possible splice variants of Hyp 8-1 were also isolated. Binding studies of COS-7 cells transfected with clone Hyp 8-1 failed to demonstrate specific binding with several 3H-opioid ligands. In situ hybridization studies indicate that the mRNA for Hyp 8-1 is distributed discretely throughout the rat brain, in an overall pattern which is different from that of several other G-protein-coupled seven transmembrane receptors. Thus, it is likely that the Hyp 8-1 cDNA encodes a novel peptide receptor.
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MESH Headings
- Amino Acid Sequence
- Animals
- Base Sequence
- Blotting, Northern
- Brain Chemistry
- Chlorocebus aethiops
- Cloning, Molecular
- Consensus Sequence
- DNA, Complementary/genetics
- Ganglia, Spinal/chemistry
- Ligands
- Male
- Mice
- Molecular Sequence Data
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid/classification
- Receptors, Opioid/genetics
- Receptors, Opioid, delta/genetics
- Receptors, Opioid, kappa/genetics
- Receptors, Opioid, mu/genetics
- Sequence Alignment
- Sequence Homology
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902
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Lin X, Murchison HA, Nagarajan V, Parson WW, Allen JP, Williams JC. Specific alteration of the oxidation potential of the electron donor in reaction centers from Rhodobacter sphaeroides. Proc Natl Acad Sci U S A 1994; 91:10265-9. [PMID: 7937938 PMCID: PMC45000 DOI: 10.1073/pnas.91.22.10265] [Citation(s) in RCA: 188] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The effects of multiple changes in hydrogen bond interactions between the electron donor, a bacteriochlorophyll dimer, and histidine residues in the reaction center from Rhodobacter sphaeroides have been investigated. Site-directed mutations were designed to add or remove hydrogen bonds between the 2-acetyl groups of the dimer and histidine residues at the symmetry-related sites His-L168 and Phe-M197, and between the 9-keto groups and Leu-L131 and Leu-M160. The addition of a hydrogen bond was correlated with an increase in the dimer midpoint potential. Measurements on double and triple mutants showed that changes in the midpoint potential due to alterations at the individual sites were additive. Midpoint potentials ranging from 410 to 765 mV, compared with 505 mV for wild type, were achieved by various combinations of mutations. The optical absorption spectra of the reaction centers showed relatively minor changes in the position of the donor absorption band, indicating that the addition of hydrogen bonds to histidines primarily destabilized the oxidized state of the donor and had little effect on the excited state relative to the ground state. Despite the change in energy of the charge-separated states by up to 260 meV, the mutant reaction centers were still capable of electron transfer to the primary quinone. The increase in midpoint potential was correlated with an increase in the rate of charge recombination from the primary quinone, and a fit of these data using the Marcus equation indicated that the reorganization energy for this reaction is approximately 400 meV higher than the change in free energy in wild type. The mutants were still capable of photosynthetic growth, although at reduced rates relative to the wild type. These results suggest a role for protein-cofactor interactions--in particular, histidine-donor interactions--in establishing the redox potentials needed for electron transfer in biological systems.
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903
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Lin X, Sun Z. [Construction of human glioma cDNA library]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1994; 25:241-4. [PMID: 7896236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Total RNA from a human glioma was extracted by acid guanidinium-thiocyanate-chloroform one step method, and poly(A+)RNA was separated by affinity chromatography on oligo (dT) cellulose. The cDNA was synthesized by using poly (A+) RNA as template, the length of cDNA being 0.2-5 kb. The glioma cDNA inserts could be cloned into lambda gt11 vector, the resulting recombinant DNA was packaged in vitro. The cDNA library of 1.12 x 10(5) pfu/ml was obtained, and the cloning efficiency was 4.8 x 10(3)/ng cDNA. This library might contribute an important basis to study of the structure and function of human glioma genes.
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904
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Lin X, Costa M. Transformation of human osteoblasts to anchorage-independent growth by insoluble nickel particles. ENVIRONMENTAL HEALTH PERSPECTIVES 1994; 102 Suppl 3:289-92. [PMID: 7843117 PMCID: PMC1567414 DOI: 10.1289/ehp.94102s3289] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Nickel compounds are well established by epidemiologic studies as human carcinogens. Although the carcinogenicity of nickel compounds has been studied in experimental animals and in a variety of cultured mammalian cells, there are only sporadic reports of nickel-induced transformation of human cells. In attempts to study the mechanisms of nickel-induced carcinogenesis in human cells, an immortalized human osteoblastic cell line (HOS) that could not grow in soft agar or form tumors in athymic nude mouse was repeatedly treated with a water-soluble nickel compound (NiCl2) or a less water-soluble nickel compound crystalline (NiS). After three rounds of NiS treatment, there was an increase in anchorage-independent (AI) colony formation. This was not found in untreated or NiCl2-treated cells. Ten AI colonies obtained from NiS-treated cells were isolated. All of these clones showed changes in cell morphology, including the appearance of uniform polygon shape, growth in multilayers, and heavy staining with Giemsa. Most of these clones were retested for their ability to grow in soft agar and showed growth efficiencies of 5 to 50%. It has been shown by other investigators that aggregate growth is well correlated with tumorigenic potential in viral or chemical transformants of HOS cells. Four of seven tested NiS-transformed clones were able to form large aggregates compared to their untransformed counterparts, and continued to proliferate in aggregate form when they were plated on 0.9% agar. Current investigations focus on the molecular and genetic changes induced by nickel compounds in these human cells.
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905
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Abstract
Recently, protein engineering has been used to interconvert homodimeric and homologous single-chain aspartic proteases, with some success. The independent folding of the domains of these proteases has also permitted the engineering of domain-rearranged protease zymogens and the use of individual domains as probes for structural denaturation. In addition, site-directed mutagenesis has provided insights into the catalytic mechanism and specificity of this family of proteases.
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906
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Peloquin JM, Williams JC, Lin X, Alden RG, Taguchi AK, Allen JP, Woodbury NW. Time-dependent thermodynamics during early electron transfer in reaction centers from Rhodobacter sphaeroides. Biochemistry 1994; 33:8089-100. [PMID: 8025115 DOI: 10.1021/bi00192a014] [Citation(s) in RCA: 118] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The temperature dependence of fluorescence on the picosecond to nanosecond time scale from the reaction centers of Rhodobacter sphaeroides strain R-26 and two mutants with elevated P/P+ midpoint potentials has been measured with picosecond time resolution. In all three samples, the kinetics of the fluorescence decay is complex and can only be well described with four or more exponential decay terms spanning the picosecond to nanosecond time range. Multiexponential fits are needed at all temperatures between 295 and 20 K. The complex decay kinetics are explained in terms of a dynamic solvation model in which the charge-separated state is stabilized after formation by protein conformational changes. Many of these motions have not had time to occur on the time scale of initial electron transfer and/or are frozen out at low temperature. This results in a time- and temperature-dependent enthalpy change between the excited singlet state and the charge-separated state that is the dominant term in the free energy difference between these states. Long-lived fluorescence is still observed even at 20 K, particularly for the high-potential mutants. This implies that the driving force for electron transfer on the nanosecond time scale at low temperature is less than 200 cm-1 (25 meV) in R-26 reaction centers and even smaller on the picosecond time scale or in the high-potential mutants.(ABSTRACT TRUNCATED AT 250 WORDS)
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907
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Woodbury NW, Peloquin JM, Alden RG, Lin X, Lin S, Taguchi AK, Williams JC, Allen JP. Relationship between thermodynamics and mechanism during photoinduced charge separation in reaction centers from Rhodobacter sphaeroides. Biochemistry 1994; 33:8101-12. [PMID: 8025116 DOI: 10.1021/bi00192a015] [Citation(s) in RCA: 83] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Detailed fast transient absorption measurements have been performed at low temperature on reaction centers from Rhodobacter sphaeroides strain R-26 and on a double mutant, [LH(L131) + LH-(M160)], in which the P/P+ oxidation potential is roughly 140 mV (1100 cm-1) above that of wild-type reaction centers. In both samples, the decay of the excited singlet state of the initial electron donor is not well described by a single-exponential decay term. This is particularly true for reaction centers from the double mutant where at least three exponential kinetic components are required to describe the decay, with time constants ranging from a few picoseconds to hundreds of picoseconds. However, singular value decomposition analysis of the time-dependent absorption change spectra indicates the presence of only two spectrally distinct states in reaction centers from both R-26 and the double mutant. Thus, the complex decay of P* at low temperature does not appear to be due to formation of either the state P+BA- as a distinct intermediate in electron transfer or P+BB- as an equilibrated side product of electron transfer. Instead, the decay kinetics are modeled by assuming dynamic solvation of the charge-separated state, as was done for the long-lived fluorescence decay in the accompanying paper [Peloquin, J. M., Williams, J. C., Lin, X., Alden, R. G., Taguchi, A. K. W., Allen, J.P., & Woodbury, N. W. (1994) Biochemistry 33, 8089-8100]. The results of assuming a static distribution of electron-transfer rates at early times followed by dynamic solvation of the charge-separated states on longer time scales are also presented. Regardless of which model is used to describe the early time kinetics of excited-state decay, the time-dependent excited-state population on the 100-ps or longer time scale is best described in terms of thermal repopulation of P* from the charge-separated state, even at 20 K. This results in a time- and temperature-dependent driving force estimated for initial electron transfer of less than 200 cm-1 on all time scales from picoseconds to nanoseconds. Assuming a nonzero internal reorganization energy associated with charge separation, the small driving force does not appear to be consistent with the lack of temperature dependence of electron transfer and the fact that a mutant with a P/P+ oxidation potential 140 mV (1100 cm-1) higher than wild type is still able to undergo electron transfer, even at low temperature.(ABSTRACT TRUNCATED AT 400 WORDS)
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908
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Siscovick DS, Raghunathan TE, Psaty BM, Koepsell TD, Wicklund KG, Lin X, Cobb L, Rautaharju PM, Copass MK, Wagner EH. Diuretic therapy for hypertension and the risk of primary cardiac arrest. N Engl J Med 1994; 330:1852-7. [PMID: 8196728 DOI: 10.1056/nejm199406303302603] [Citation(s) in RCA: 304] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
BACKGROUND The results of trials of the primary prevention of coronary heart disease have suggested that treating hypertension with high doses of thiazide diuretic drugs might increase the risk of sudden death from cardiac causes. In contrast, treatment with low doses of thiazide reduces the risk of coronary heart disease. METHODS To examine the association between thiazide treatment for hypertension and the occurrence of primary cardiac arrest, we conducted a population-based case-control study among enrollees of a health maintenance organization. The case patients were 114 persons with hypertension who had a primary cardiac arrest from 1977 through 1990. The control patients were a stratified random sample of 535 persons with hypertension. The patients' treatment was assessed with the use of a computerized pharmacy data base. Records of their ambulatory care were reviewed to determine other clinical characteristics. RESULTS The risk of primary cardiac arrest among patients receiving combined thiazide and potassium-sparing diuretic therapy was lower than that among patients treated with a thiazide without potassium-sparing therapy (odds ratio, 0.3; 95 percent confidence interval, 0.1 to 0.7). As compared with low-dose thiazide therapy (25 mg daily), moderate-dose therapy (50 mg daily) was associated with a moderate increase in risk (odds ratio, 1.7; 95 percent confidence interval, 0.7 to 4.5), and high-dose therapy (100 mg daily) was associated with a larger increase in risk (odds ratio, 3.6; 95 percent confidence interval, 1.2 to 10.8) (P value for trend, 0.02). The addition of a potassium-sparing drug to low-dose thiazide therapy was associated with a reduced risk of cardiac arrest (odds ratio, 0.4; 95 percent confidence interval, 0.1 to 1.5). CONCLUSIONS Both the dose of thiazide drugs and the addition of potassium-sparing drugs influence the risk of primary cardiac arrest. These results may explain the differences in the effect of antihypertensive therapy on mortality from coronary heart disease in previous clinical trials.
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909
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Liu W, Dotson DG, Lin X, Mullen JJ, Gonzalez-Garay ML, Lu Q, Putkey JA. The presence but not the sequence of the N-terminal peptide in cardiac TnC is important for function. FEBS Lett 1994; 347:152-6. [PMID: 8033994 DOI: 10.1016/0014-5793(94)00526-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The most diverged region of the primary amino acid sequence between cardiac (cTnC) and fast skeletal troponin C is the N-terminal ten amino acids. We report here that major changes in the primary sequence of this region in cTnC had a minimal effect on the ability of the mutant proteins to recover maximal activity in TnC-extracted cardiac and fast skeletal muscle myofibrils. However, deletion of the N-terminal nine amino acids resulted in a 60% decrease in maximal Ca(2+)-dependent ATPase activity with only a small change in the pCa50 of activation. Deletion of the N-terminal peptide did not appear to appreciably affect the Ca(2+)-binding properties of cTnC, but it did alter the interaction with hydrophobic fluorescent probes. Thus, the presence but not the sequence, of the N-terminal extension is important for the maximal activity of cTnC. The N-terminal helix may function in a relatively non-specific manner to prevent unfavorable interactions between domains in cTnC or between cTnC and other troponin subunits.
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910
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Lin X, Dowjat WK, Costa M. Nickel-induced transformation of human cells causes loss of the phosphorylation of the retinoblastoma protein. Cancer Res 1994; 54:2751-4. [PMID: 8168106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The retinoblastoma (Rb) protein (pRb) has been studied in various crystalline NiS-transformed cell clones derived from the human osteoblast cell line, HOS TE-85. The parental HOS cells were not able to proliferate in soft agar medium, but they acquired this property following treatment with crystalline NiS. The pRb was found only in the hypophosphorylated form in 8 of 9 nickel-transformed clones examined, whereas in the parental cells the pRb appeared in both phosphorylated and unphosphorylated forms. Neither Rb gene expression nor its phosphorylation was affected by acute nickel treatments of HOS cells. The nickel-transformed HOS clones expressed the major regulators of Rb phosphorylation, cyclin E and cdk-2, at levels similar to those of the parental cells. In coimmunoprecipitation assays with cell lysates from the transformed clones that exhibited the hypophosphorylated form of pRb, the Rb protein failed to form a complex with simian virus 40 large T-antigen, indicating a lack of functional activity. When a plasmid containing the normal Rb gene was transfected into these nickel-transformed cells, it restored the Rb phosphorylation pattern observed in parental cells and the cells acquired a normal phenotype (i.e., they were no longer able to grow in soft agar). This suggested that a mutation was induced in nickel-transformed cells that affected the ability of the Rb protein to be phosphorylated and function normally, and this mutation allowed the human nickel-transformed cells to acquire anchorage-independent growth.
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911
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Bulleit RF, Cui H, Wang J, Lin X. NMDA receptor activation in differentiating cerebellar cell cultures regulates the expression of a new POU gene, Cns-1. J Neurosci 1994; 14:1584-95. [PMID: 7907365 PMCID: PMC6577559] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
POU/homeobox genes encode transcription regulatory proteins that are important in defining cellular phenotypes. Expression of these genes may be critical for to the regulation of CNS cellular differentiation. We have identified a cDNA corresponding to a new member of the POU/homeobox gene family. Expression of RNA encoded by this new gene occurs predominantly in the CNS. Thus, this new gene was designated Cns-1. Cns-1 transcripts are expressed in differentiating cells cultured from the early postnatal cerebellum. Treatment of these cultured cells with NMDA results in an increase in the level of Cns-1 RNA. This increase is blocked by simultaneous treatment with the specific NMDA receptor antagonist amino-5-phosphonovaleric acid. Continued activation of the NMDA receptor allows maintenance of this new steady state level of Cns-1 mRNA for at least 5 d in these cultured cells. A transcription runoff assay suggests that this increase in the level of RNA is due, at least in part, to an increase in transcription from the Cns-1 gene. The NMDA-induced increase in Cns-1 mRNA was reduced by pretreatment with calcium chelators EGTA or 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) tetrakis(acetoxymethyl). These studies suggest that specific activation of the NMDA receptor in cultures of differentiating cerebellar cells increases Cns-1 gene expression and that calcium entry through the NMDA channel may be required for this response. This change in Cns-1 expression may modify phenotypic characteristics of these cultured cells.
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912
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Huang YS, Cantrill RC, DeMarco A, Campbell L, Lin X, Horrobin DF, Mills DE. Differences in the metabolism of 18:2n-6 and 18:3n-6 by the liver and kidney may explain the anti-hypertensive effect of 18:3n-6. BIOCHEMICAL MEDICINE AND METABOLIC BIOLOGY 1994; 51:27-34. [PMID: 7910749 DOI: 10.1006/bmmb.1994.1003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The present study examined the in vitro and in vivo metabolism of 18:2n-6 and 18:3n-6 by kidney and liver in the male adult spontaneously hypertensive (SHR) and normotensive (WKY) rats. In liver and kidney slices incubated for 1 h with either [1-14C]18:2n-6 or [1-14C]18:3n-6 (60 microM), substantial amounts of radioactivity were incorporated into triacylglycerol and phospholipid fractions. Approximately 15% of the radiolabeled 18:2n-6 was converted into 18:3n-6 in liver slices but no conversion was found in kidney slices. When incubated with radiolabeled 18:3n-6, over 40% of the radioactivity was metabolized mainly to 20:4n-6 in liver slices, but evenly to 20:3n-6 and 20:4n-6 in kidney slices. There were no differences between the results from SHR and those from WKY. In WKY rats given an oral bolus of radiolabeled 18:3n-6, most of the radioactivity was recovered in the liver and significantly less in the kidney. In both tissues, the radioactivity was associated initially only with 18:3n-6 and later with its elongation product, 20:3n-6. These findings indicated that the kidney, although unable to metabolize 18:2n-6, could metabolize 18:3n-6 taken up from the circulation. The effectiveness of 18:3n-6, compared to 18:2n-6, as an anti-hypertensive agent may result from the provision of a post-delta 6-desaturation metabolite which can be directly converted to blood pressure-regulating eicosanoids in the kidney.
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913
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Lin X, Chen G, Li J. [Hepatic ultrasonographic imaging and serum amino acid levels in cured schistosomiasis cases]. ZHONGGUO JI SHENG CHONG XUE YU JI SHENG CHONG BING ZA ZHI = CHINESE JOURNAL OF PARASITOLOGY & PARASITIC DISEASES 1994; 12:143-146. [PMID: 7955167] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Ultrasonography (B mode) of liver and serum amino-acid levels were studied in 15 cases of schistosomiasis japonica who had been cured for more than 5-15 years. Typical B-ultrasonic images of hepatic fibrosis due to schistosomiasis were found in all patients which could be classified into three types, namely, the spotty type (I), the tortoise-shell type (II) and the net-patchy type (III) according to the patterns of echogenic bands. Moderate to marked echogenic thickening of portal vein wall, and dilation of portal and splenic veins were revealed in patients with type II and III images. Free amino acids in sera were determined by using HPLC-AAAS. The result revealed that the concentration of 8 nonessential and 3 essential amino acids (threonine, valine, tryptophan) were significantly decreased in the 15 patients. The ratio of aromatic to aliphatic amino acid was markedly elevated in 3 patients of type III. The serum amino acid imbalance was attributed to the severe hepatic damage and impaired liver function.
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914
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Lin X, Ridley BA, Walega J, Hübler GF, McKeen SA, Hsie EY, Trainer M, Fehsenfeld FC, Liu SC. Parameterization of subgrid scale convective cloud transport in a mesoscale regional chemistry model. ACTA ACUST UNITED AC 1994. [DOI: 10.1029/94jd02398] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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915
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Odle J, Lin X, Wieland TM, van Kempen TA. Emulsification and fatty acid chain length affect the kinetics of [14C]-medium-chain triacylglycerol utilization by neonatal piglets. J Nutr 1994; 124:84-93. [PMID: 8283298 DOI: 10.1093/jn/124.1.84] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
In vivo oxidation kinetics of medium-chain triglycerides (MCT) composed of [1-14C]hexanoate (tri-6:0) or [1-14C]octanoate (tri-8:0) were compared after being fed to day-old piglets (1.4 kg; n = 4/treatment). Animals were fitted with arterial and oro-gastric catheters and placed into respiration chambers held at 35 degrees C. The radiolabeled MCT were fed in equimolar amounts (6.5 mmol/kg0.75), in either nonemulsified form or as 30% (v/v) emulsions, using polyoxyethylene sorbitan monooleate as an emulsifier. Expired CO2 was quantified and specific radioactivity (Bq/mumol) determined at 20-min intervals over 24 h, and serial blood samples were drawn for measurement of plasma hexanoate and octanoate by HPLC. The rate [mumol/(h.kg0.75)] and extent (mmol/kg0.75) of MCT oxidative utilization (i.e., composite of digestion, absorption and oxidation) were calculated from the kinetics of 14CO2 expiration. Emulsification increased both the rate and extent of MCT oxidative utilization by > 20% regardless of fatty acid chain length (P < 0.05). Maximal MCT oxidation rates occurred at 3.5 h after feeding and were sufficient to meet up to 48% of the piglets' energy expenditure. The maximal rate of tri-6:0 oxidative utilization exceeded that of tri-8:0 by 37% (P < 0.05), but the extent of utilization was not affected by fatty acid chain length. Plasma medium-chain fatty acid concentrations were in agreement with these observations, being higher in pigs fed emulsified MCT than in pigs fed nonemulsified MCT (P < 0.05) and being higher in pigs fed tri-6:0 than in animals fed tri-8:0 (P < 0.05). Collectively, these data demonstrate that newborn piglets can effectively digest, absorb and oxidize MCT, that utilization is improved with emulsification, and that tri-6:0 is utilized more rapidly than tri-8:0.
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916
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Abstract
The applicability and usefulness of k0-based reactor neutron activation analysis (NAA) in the life sciences is evaluated from the following examples: 1. Instrumental NAA of NIST SRM 1633a coal fly ash, as a quality assessment; 2. Radiochemical NAA of Versieck's reference human serum, and--herewith associated--the development of practical correction procedures for neutron-induced reaction interferences and of improved methods to evaluate the detection efficiency and the correction for true coincidence; and 3. Determination of the lanthanides in plant leaves and lichens near a Portuguese coal-fired power station, which led to the introduction of the Westcott formalism and to the use of a low-energy photon detector. As concluded, k0-based NAA is at present capable of tackling a large variety of analytical problems when it comes to the multielement determination in environmental and biological matrices.
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917
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Mignot E, Lin X, Hesla PE, Dement WC, Guilleminault C, Grumet FC. A novel HLA DR17,DQ1 (DQA1-0102/DQB1-0602 positive) haplotype predisposing to narcolepsy in Caucasians. Sleep 1993; 16:764-5. [PMID: 8165393 DOI: 10.1093/sleep/16.8.764] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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918
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Lin X, Hethcote HW, van den Driessche P. An epidemiological model for HIV/AIDS with proportional recruitment. Math Biosci 1993; 118:181-95. [PMID: 8305827 DOI: 10.1016/0025-5564(93)90051-b] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
A model for HIV transmission is formulated for a homosexual population of varying size, with recruitment into the susceptible class proportional to the active population size and with stages of progression to AIDS. Analysis of this model includes identifying the threshold that determines whether the disease dies out or proportions remain endemic and establishing criteria that determine whether the population size decays asymptotically exponentially to zero or grows asymptotically exponentially to infinity. In an analogous heterosexual model, the conservation of heterosexual contacts is shown to imply that this two-sex model reduces to the one-sex model.
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919
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Lin X, Zhong G. [Clinical analysis of 160 cases with the magnetic foreign bodies in the posterior segment of the eye]. YAN KE XUE BAO = EYE SCIENCE 1993; 9:219-21. [PMID: 7957862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
One hundred and sixty cases of magnetic foreign bodies in the posterior segment of the eye are reported. Most of the foreign bodies are small (61.2% are less than 2mm) and near the wall of the eye (73.7% are less than 2mm). 110 cases were successfully operated in conventional way and just 20 cases needed to have vitrectomy. The result of the operation depends on the damage of the eye, location of the foreign body and the complication of the operation. In 77.6% of the cases, the wound was on the cornea or limbus. That is one of the important factors to affect the patients' postoperation vision.
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920
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Ren T, Lin X, Nuttall AL. Polarized-light intravital microscopy for study of cochlear microcirculation. Microvasc Res 1993; 46:383-93. [PMID: 8121321 DOI: 10.1006/mvre.1993.1061] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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921
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Huang YS, Wainwright PE, Mills DE, Lin X, Horrobin DF. Effects of maternal dietary n-3 and n-6 fatty acids (pre- and post-delta 6 desaturation) on tissue glycerophospholipid fatty acid compositions in dams and suckling mice. PROCEEDINGS OF THE SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE. SOCIETY FOR EXPERIMENTAL BIOLOGY AND MEDICINE (NEW YORK, N.Y.) 1993; 204:54-64. [PMID: 8372097 DOI: 10.3181/00379727-204-43634] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The present study examined the effects of supplementation of either 18:3n-3 or a mixture of its post-delta 6-desaturation metabolites, 20:5n-3/22:6n-3, in combination with either 18:2n-6 or its immediate delta 6-desaturation product, 18:3n-6, in the maternal diet (n-3 to n-6 ratio at 0.25) on brain, liver, heart, and kidney glycerophospholipid fatty acid composition in dams (B6D2F1 mice) and their 12-day-old suckling pups. As expected, n-3 and n-6 fatty acids competed for incorporation into tissue glycerophospholipids in both dams and their suckling pups. Feeding a 20:5n-3/22:6n-3 as compared with an 18:3n-3 rich diet increased the tissue levels of 20:5n-3 and 22:5n-3, whereas it decreased those of 20:3n-6 and 20:4n-6. Replacing 18:2n-6 with 18:3n-6 in the maternal diet increased significantly the levels of 18:3n-6, 20:3n-6, and 20:4n-6, whereas it reduced those of 20:5n-3. However, the effects of maternal dietary fats on tissue fatty acid compositions in pups were qualitatively similar to but quantitatively smaller than those in dams. The discrepancy might be due to differences in the composition of fatty acids taken up and synthesized by the dams and that transferred to the pups.
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922
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Lin X, Hume RI, Nuttall AL. Voltage-dependent block by neomycin of the ATP-induced whole cell current of guinea-pig outer hair cells. J Neurophysiol 1993; 70:1593-605. [PMID: 7506758 DOI: 10.1152/jn.1993.70.4.1593] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
1. The effects of externally applied ATP and neomycin on whole cell currents of isolated guinea pig cochlear outer hair cells (OHCs) were studied using the whole cell voltage-clamp technique. In OCHs held at -70 mV, ATP activated a large inward current. In the presence of neomycin, the ATP-induced whole cell current activated along a relatively unaltered time course, but the current then decreased to a reduced steady level. The neomycin inhibition of the ATP-induced current was dose dependent. The half-inhibitory concentration (IC50) of neomycin measured at steady state was estimated to be 90 microM. 2. Neomycin inhibition of the ATP response could not be reversed by increasing the concentration of ATP, indicating that the effect was noncompetitive. The inhibition was voltage dependent and was greatly reduced when OHCs were held at positive potentials. 3. Cells treated with 100 microM ATP gave maximal current responses. Addition of neomycin substantially increased membrane current noise of the 100 microM ATP responses. When neomycin concentration was varied from 10 to 500 microM, the current noise level peaked between 50 and 100 microM. The noise increase was observed at negative holding potentials but not at positive potentials. 4. The neomycin-induced whole cell current noise was used to estimate the size of the underlying elementary current. The ATP-induced single channel current of OHCs at -70 mV was estimated to be approximately 0.3 pA. The number of ATP-activated channels in a single OHC was estimated to be in the range of a few thousand. 5. The characteristics of the neomycin inhibition of ATP-induced currents were consistent with an open channel blocking mechanism. Analysis of the voltage dependence of the steady state neomycin inhibition suggested a neomycin binding site at an electrical distance of 0.3 from the extracellular side.
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923
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Lin X, Tang J, Koelsch G, Monod M, Foundling S. Recombinant canditropsin, an extracellular aspartic protease from yeast Candida tropicalis. Escherichia coli expression, purification, zymogen activation, and enzymic properties. J Biol Chem 1993; 268:20143-7. [PMID: 8376373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
A cDNA fragment which encodes the zymogen of canditropsin, the extracellular aspartic protease from the yeast Candida tropicalis (Togni,G., Sanglard, D., Falchetto, R., and Monod, M. (1991) FEBS Lett. 286, 181-185) was cloned into a T7 expression vector for the synthesis of the recombinant zymogen in Escherichia coli. Recombinant canditropsinogen (Ctg), which was expressed as inclusion bodies in the cytosol of E. coli, was refolded by dialysis from an 8 M urea solution and purified to homogeneity using chromatographies on Sephacryl S-300 and on MonoQ columns. The purified Ctg was converted into canditropsin by either acid activation or trypsin conversion. The specificity of the resulting recombinant canditropsin toward polypeptide substrates is significantly different from other aspartic proteases. Canditropsin hydrolyzes oxidized insulin B chain between Ala-Leu and many other minor cleavage sites. Canditropsin also hydrolyzes keratin and collagen, which are components of connective tissues known to be hydrolyzed by canditropsin during Candida infections. Canditropsin was strongly inhibited by the universal aspartic protease inhibitor pepstatin (Ki = 1.75 x 10(-8) M) and inactivated by two aspartic protease inactivators, DAN and EPNP. Canditropsin is weakly inhibited by leupeptin and antipain, with an apparent Ki of 1.74 x 10(-4)M and 1.5 x 10(-5) M, respectively.
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924
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Lin X, Tang J, Koelsch G, Monod M, Foundling S. Recombinant canditropsin, an extracellular aspartic protease from yeast Candida tropicalis. Escherichia coli expression, purification, zymogen activation, and enzymic properties. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(20)80705-4] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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925
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Lin X, Shu X, Sun Z, Zhao J, Sun Z. [A study on P21(ras) in human lung cancer and body fluid of cancer patients]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1993; 24:233-6. [PMID: 8288186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The McAb of anti-P21(ras) has been used to screen 9 cases of human lung cancer tissues, 18 cases of samples and 2 cases of hydrothorax samples of lung cancer patients by means of PAGE-immunoblots. The expression of ras gene was found in 8 cases of human lung cancer among which the expression of 4 cases was higher than that of normal control. P21(ras) has not been detected in serum and hydrothorax samples of cancer patients. The present study indicated that there was P21(ras) in human lung cancer and normal control and the expression level of ras gene in lung cancer was related to the differentiation of cancer.
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926
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Lin X, Loy JA, Sussman F, Tang J. Conformational instability of the N- and C-terminal lobes of porcine pepsin in neutral and alkaline solutions. Protein Sci 1993; 2:1383-90. [PMID: 8401224 PMCID: PMC2142452 DOI: 10.1002/pro.5560020903] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Pepsin contains, in a single chain, two conformationally homologous lobes that are thought to have been evolutionarily derived by gene duplication and fusion. We have demonstrated that the individual recombinant lobes are capable of independent folding and reconstitution into a two-chain pepsin or a two-chain pepsinogen (Lin, X., et al., 1992, J. Biol. Chem. 267, 17257-17263). Pepsin spontaneously inactivates in neutral or alkaline solutions. We have shown in this study that the enzymic activity of the alkaline-inactivated pepsin was regenerated by the addition of the recombinant N-terminal lobe but not by the C-terminal lobe. These results indicate that alkaline inactivation of pepsin is due to a selective denaturation of its N-terminal lobe. A complex between recombinant N-terminal lobe of pepsinogen and alkaline-denatured pepsin has been isolated. This complex is structurally similar to a two-chain pepsinogen, but it contains an extension of a denatured pepsin N-terminal lobe. Acidification of the complex is accompanied by a cleavage in the pro region and proteolysis of the denatured N-terminal lobe. The structural components that are responsible for the alkaline instability of the N-terminal lobe are likely to be carboxyl groups with abnormally high pKa values. The electrostatic potentials of 23 net carboxyl groups in the N-terminal domain (as compared to 19 in the C-terminal domain) of pepsin were calculated based on the energetics of interacting charges in the tertiary structure of the domain. The groups most probably causing the alkaline denaturation are Asp11, Asp159, Glu4, Glu13, and Asp118.(ABSTRACT TRUNCATED AT 250 WORDS)
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927
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Lin X, Dashti A, Schinazi RF, Tang J. Intracellular diversion of glycoprotein GP160 of human immunodeficiency virus to lysosomes as a strategy of AIDS gene therapy. FASEB J 1993; 7:1070-80. [PMID: 8370478 DOI: 10.1096/fasebj.7.11.8370478] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A potential gene therapy strategy against human immunodeficiency virus (HIV-1) is to disrupt the intracellular transport of viral proteins. We report here the binding and transporting of HIV-1 glycoprotein gp160 to lysosomes as a result of the expression of fusion genes consisting of soluble CD4 and lysosome targeting domains. The effective lysosome targeting domain tested includes a lysosomal protease zymogen, procathepsin D, and the COOH-terminal domains of three lysosome membrane proteins: lamp-1, lamp-2, and lysosomal acid phosphatase. We demonstrated that cell fusion (syncytium), caused by the transport of gp160 to the surface of HeLa-CD4+ cells, was completely abolished by the expression of these fusion genes. The lysosomal localization of gp160 in HeLa cells coexpressing CD4-fusion genes was also established. From pulse-chase experiments, we observed that gp160 and the fusion proteins were degraded, as expected of lysosomal activities. Additionally, T lymphoblastoid cells transiently and permanently expressing these fusion genes strongly retarded the propagation of human immunodeficiency virus type 1. Thus, these fusion genes can deprive HIV of newly synthesized envelope protein gp160 for the assembly of new virions and are potentially useful in gene therapy against AIDS.
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928
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Molkentin J, Gregersen PK, Lin X, Zhu N, Wang Y, Wang Y, Chen S, Chen S, Baxter-Lowe LA, Silver J. Molecular analysis of HLA-DR beta and DQ beta polymorphism in Chinese with rheumatoid arthritis. Ann Rheum Dis 1993; 52:610-2. [PMID: 8215626 PMCID: PMC1005121 DOI: 10.1136/ard.52.8.610] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
OBJECTIVES Several studies have suggested that genetic predisposition to rheumatoid arthritis may be related to the presence of specific polymorphic HLA sequences that are often associated with HLA-DR4 haplotypes. This study was performed to determine if an association exists between Chinese with rheumatoid arthritis and a particular HLA-DR beta or DQ beta subtype. METHODS This study used the polymerase chain reaction to amplify HLA-DR beta and DQ beta genes, and oligonucleotide probe hybridisation to examine the association of certain polymorphic sequences with rheumatoid arthritis in 23 Chinese patients from Shanghai. RESULTS An HLA-DR4 associated sequence was significantly increased in the Chinese patients (43%) compared with healthy controls (14%) from the same location (relative risk = 4.6, 95% confidence limits 1.1 to 19.3). Analysis of the third hyperpolymorphic region of DR4 positive samples was performed to detect polymorphic sequences associated with Dw4, Dw10, Dw13, Dw14, Dw15, and KT2 cellular specificities. Examination of this region showed that 91% of patients had sequences encoding amino acids QRRAA (associated with Dw14 and Dw15) or QKRAA (associated with Dw4) compared with 64% of the DR4 positive controls. CONCLUSIONS Rheumatoid arthritis in the Chinese is associated with HLA-DR4. There is a possible relationship between sequences within the third hyperpolymorphic region of the DRB allele and rheumatoid arthritis in the Chinese.
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929
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Wieland TM, Lin X, Odle J. Utilization of medium-chain triglycerides by neonatal pigs: effects of emulsification and dose delivered. J Anim Sci 1993; 71:1863-8. [PMID: 8349513 DOI: 10.2527/1993.7171863x] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Four trials were conducted using 86, 24-h-old pigs to evaluate the utilization of medium-chain triglycerides (MCT). Effects of emulsification and amount of MCT fed were examined. After a 4-h period during which feed was withheld, pigs were force-fed MCT (containing 75% octanoate and 25% decanoate), marking time 0 of the experiment. Blood samples were obtained at 1 and 2 h for subsequent medium-chain fatty acid (MCFA) analysis. In Trials 1 (six pigs/treatment) and 2 (four pigs/treatment) the response to three emulsifying agents was compared to a nonemulsified (NE) control. Twenty milliliters of a 30% (vol/vol) emulsion of MCT or 6 mL of NE MCT was administered. Concentrations of MCFA at 1 h in pigs receiving a Tween 80 (polyoxy-ethylene [20] sorbitan monooleate) emulsion were 3- to 19-fold higher than concentrations in animals administered a gum arabic/gum tragacanth emulsion, a lecithin emulsion, or NE MCT. Trials 3 (eight pigs/treatment) and 4 (six pigs/treatment) were conducted to determine the plasma MCFA concentrations resulting from feeding increasing levels of NE (3, 6, 9, or 12 mL of MCT) or emulsified MCT oil (2, 4, 6, or 8 mL in a 30% Tween 80 emulsion). Plasma octanoate concentrations measured at 1 h increased linearly (P < .05) with increasing MCT dosage through 9 mL of NE and 6 mL of emulsified MCT. A transient narcosis was observed in 8 of 12 animals that received 6 or 8 mL of emulsified MCT and was most pronounced 1 to 2 h after feeding, which roughly corresponded to peak plasma MCFA concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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930
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Wieland TM, Lin X, Odle J. Emulsification and fatty-acid chain length affect the utilization of medium-chain triglycerides by neonatal pigs. J Anim Sci 1993; 71:1869-74. [PMID: 8349514 DOI: 10.2527/1993.7171869x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Three experiments were conducted using 52 pigs between 22 and 35 h of birth to determine the effects of emulsification and fatty-acid chain length on utilization of medium-chain triglycerides (MCT). After a 4-h period during which feed was withheld, pigs were force-fed 6 mL of nonemulsified (NE) MCT or 20 mL of a 30% (vol/vol) Tween 80-(polyoxy-ethylene [20] sorbitan monooleate) MCT emulsion, marking time 0, and serial blood samples were drawn throughout 8 h for analysis of medium-chain fatty acid (MCFA) concentrations by HPLC. In Exp. 1, pigs received either NE or emulsified Tri-C4, -C5, -C6, or -C7. The emulsified treatments were discontinued due to deaths caused by coma resulting from high concentrations (up to 12 mM) of plasma MCFA. Concentrations in pigs fed emulsified MCT were 2.5-fold higher than those in pigs fed NE MCT. In pigs fed NE MCT, concentrations of even-chain-length MCFA were higher than those of odd-chain-length MCFA (P < .001), with a tendency for C6 to be higher than C4 (P < .1). In Exp. 2 and 3, pigs received an equimolar mixture of MCT in either emulsified or NE form. In Exp. 2, the mixture contained Tri-C4 through Tri-C7; whereas, in Exp. 3 the mixture contained Tri-C4, -C6, -C8, and -C10. A three-way interaction (emulsion x fatty acid x sample time; P < .05) was observed in both experiments.(ABSTRACT TRUNCATED AT 250 WORDS)
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931
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Lin X, Candlish JK, Thai AC. Superoxide production by neutrophils from diabetics and normal subjects in response to glucose and galactose. Exp Mol Pathol 1993; 58:229-36. [PMID: 8390941 DOI: 10.1006/exmp.1993.1020] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Glucose added to the medium was found to enhance superoxide production by isolated circulating neutrophils from both diabetic and normal subjects, but quantitatively the enhancement decreased from 4 to 50 mmole/liter. Galactose up to 50 mmole/liter had no effect on superoxide production in cells from the control subjects, but appeared to depress it in those from diabetics. No correlations were found between indices of the degree of hyperglycemia (plasma glucose and hemoglobin A1c) and the magnitude of the respiratory burst in cells from diabetics. When the isolated cells from normal and diabetic subjects were restored to a medium containing glucose at the original concentration in plasma at phlebotomy, the rate of superoxide production was approximately doubled in every case and there was no significant difference between diabetic and normal cells. Preincubation of cells for 1 hr in the presence of 0-50 mmole/liter glucose or galactose prior to activation had no significantly depressant effect on the respiratory burst except at 50 mmole/liter glucose in diabetic cells. It is concluded that circulating neutrophils from the diabetic population under the conditions studied are just as competent as control cells in their ability to sustain superoxide production over a wide range of energy availability.
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932
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Newkome GR, Weis CD, Lin X, Fronczek FR. 5,5-Bis(4-cyano-2-oxabutyl)-1,9-dicyano-3,7-dioxanonane. Acta Crystallogr C 1993. [DOI: 10.1107/s0108270192012307] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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933
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Zhao HW, Shen Z, Zhou B, Lin X, Ye M. [Studies on percutaneous absorption of ruyi jinhuang san patcher with radioisotope tracer]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1993; 18:219-23, 254. [PMID: 8216787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Berberine is one of the active ingredients in Ruyi Jinhuang San Patcher. With 3H-berberine as the tracer, a radio-labelled method was used for determining percutaneous rate and drug concentration of berberine in plasma in vivo and in vitro. A study on the percutaneous rate of different technological plasters and various animal skins was also carried out.
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934
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Dravid VP, Lin X, Wang Y, Wang XK, Yee A, Ketterson JB, Chang RP. Buckytubes and Derivatives: Their Growth and Implications for Buckyball Formation. Science 1993; 259:1601-4. [PMID: 17733027 DOI: 10.1126/science.259.5101.1601] [Citation(s) in RCA: 162] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Transmission electron microscopy (TEM) observations of graphite tubules (buckytubes) and their derivatives have revealed not only the previously reported buckytube geometries but also additional shapes of the buckytube derivatives. Detailed cross-sectional TEM images reveal the cylindrical cross section of buckytubes and the growth pattern of buckytubes as well as their derivatives. These observations of frozen growth stages of buckytubes and derivatives suggest a helical growth mechanism analogous to that of crystal growth via screw dislocations. The helicacy of buckytubes is analyzed by electron diffraction whereas the anisotropy of electronic structure is revealed by momentum transfer resolved electron energy loss spectrometry. Based on the TEM observations, it is proposed that buckytubes act as precursors to closed-shell fullerene (buckyball) formation and the possible steps in buckyball formation are outlined. In arc evaporation experiments in which residue rods (containing various amounts of buckytubes) were used as the starting anode for fullerene production, the amount of buckytubes in the rod was correlated with fullerene yield.
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935
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Poisson JP, Huang YS, Mills DE, de Antueno RJ, Redden PR, Lin X, Narce M, Horrobin DF. Effect of salt-loading and spontaneous hypertension on in vitro metabolism of [1-14C]linoleic and [2-14C]dihomo-gamma-linolenic acids. BIOCHEMICAL MEDICINE AND METABOLIC BIOLOGY 1993; 49:57-66. [PMID: 8382502 DOI: 10.1006/bmmb.1993.1006] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The present study compared the effect of spontaneous hypertension and salt-loading on in vitro metabolism of 18:2n-6 (linoleic acid) and 20:3n-6 (dihomo-gamma-linolenic acid). Ten weanling spontaneously hypertensive rats (SHR) and 10 normotensive Wistar-Kyoto rats (WKY) maintained on a rodent lab chow were given tap water with (n = 5) or without (n = 5) addition of 1% NaCl for 4 weeks. Thereafter, animals were killed and liver microsomes were prepared. Aliquots of microsomes suspended in the phosphate-sucrose buffer containing MgCl2, ATP, CoA, and NADPH were incubated with 0.3 microCi of [1-14C]-18:2n-6 or [2-14C]-20:3n-6 at 37 degrees C for 15 min. The activity of delta 6- and delta 5-desaturases, and the distribution of radioactivity in different lipid fractions and in phospholipid fatty acids were determined. Results showed that both spontaneous hypertension and salt-loading suppressed the desaturation of radiolabeled 18:2n-6 and of 20:3n-6. Incubation of microsomes with [1-14C]-18:2n-6 resulted in 29% of radioactivity being associated with phospholipid fraction, of which 3% was associated with 18:3n-6. Incubation with radiolabeled 20:3n-6 resulted in 30% of the radioactivity being incorporated into phospholipids, of which 50% was associated with 20:4n-6 (arachidonic acid). Salt-loading suppressed the incorporation of radiolabeled fatty acids into phospholipids, more so in SHR than in WKY. Thus, salt-loading not only suppressed the desaturation of 18:2n-6 and 20:3n-6, but also interfered with the acylation of n-6 fatty acids into the phospholipid fraction.
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936
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Zhong WZ, Hong HC, Lu ZP, Zhao TD, Hua SK, Tang DY, Zhao QL, Zeng WR, Lin X. Morphology of BBO Crystals and their Inclusions. CRYSTAL RESEARCH AND TECHNOLOGY 1993. [DOI: 10.1002/crat.2170280618] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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937
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Lin X, Wang Z, Gu L, Deuel TF. Functional analysis of the human platelet-derived growth factor A-chain promoter region. J Biol Chem 1992; 267:25614-9. [PMID: 1460057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The platelet-derived growth factor (PDGF) A-chain gene is a developmentally regulated gene that is expressed in high levels in a limited number of normal and transformed cell lines and in cells stimulated by cytokines, including PDGF itself. We have now analyzed potential regulatory elements in 3.6 kilobase pairs (kb) of the 5'-flanking sequences of the human PDGF A-chain gene using reporter gene constructs and transient transfection analyses. The region between base pairs (bp) -618 and +392 (relative to the transcription initiation site) is sufficient for optimal promoter activity. A highly G + C region containing three contiguous Sp1 binding sites between bp -150 and -33 contributes over 80% of promotor activity. DNase I footprinting analyses indicates that Sp1 binds to and protects over 57 bp of this G + C region. A functional serum response element is located within bp -477 and -468 and positively regulates induction of PDGF A by PDGF. A negative regulatory (silencer) element is located from -1.9 to -0.9 kb. The results suggest that the major constitutive expression of the PDGF A-chain gene requires a highly G + C-rich region containing three Sp1 binding sites and that induction of the PDGF A-chain gene by PDGF is mediated by a SRE located at bp -477 to -468.
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938
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Sugiyama M, Tsuzuki K, Lin X, Costa M. Potentiation of sodium chromate(VI)-induced chromosomal aberrations and mutation by vitamin B2 in Chinese hamster V79 cells. Mutat Res 1992; 283:211-4. [PMID: 1383790 DOI: 10.1016/0165-7992(92)90109-u] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The effect of vitamin B2, which is capable of reducing chromium(VI) to chromium(V), on chromosomal aberrations and mutation caused by Na2CrO4 was investigated in Chinese hamster V79 cells. Pretreatment with 200 microM vitamin B2 (riboflavin) for 24 h prior to exposure to Na2CrO4 (2.5-5 microM) resulted in an increase of metal-induced chromosomal aberrations and mutation at the HGPRT locus. These and other previous studies suggest that vitamin B2 enhances the clastogenic and mutagenic action of chromate compounds, through its ability to directly reduce chromium(VI) in cells.
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939
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Mignot E, Lin X, Kalil J, George C, Singh S, Billiard M, Montplaisir J, Arrigoni J, Guilleminault C, Dement WC. DQB1-0602 (DQw1) is not present in most nonDR2 Caucasian narcoleptics. Sleep 1992; 15:415-22. [PMID: 1455124 DOI: 10.1093/sleep/15.5.415] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Human narcolepsy is a genetically determined disorder of sleep strongly associated with the human leucocyte antigens (HLA) DR2 and DQw1. In black narcoleptic patients, susceptibility for narcolepsy is more closely related to a specific gene subtype of DQw1, DQB1-0602, than to DR2. About 30% of black narcoleptic patients are nonDR2, but all carry the HLA DQB1-0602 gene. In the present study, we have tested caucasian nonDR2 cataplectic patients (6 sporadic cases and 7 familial cases from 3 multiplex families) for the presence of the HLA DQB1-0602 and DQA1-0102 (DQw1) using a specific polymerase chain reaction (PCR)-oligotyping technique. None of the patients was DQB1-0602 or DQA1-0102 positive, thus proving that, in caucasians, DQB1-0602 and DQA1-0102 (DQw1) are not prerequisites for the diagnosis of narcolepsy. Further studies with more patients are warranted to exclude the possibility that a few caucasian patients carry rare haplotypes with DQB1-0602 independently of DR2.
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940
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Lin X, Watson JC. cDNA Sequence of PsPK5, a Protein Kinase Homolog from Pisum sativum L. PLANT PHYSIOLOGY 1992; 100:1072-4. [PMID: 16653022 PMCID: PMC1075671 DOI: 10.1104/pp.100.2.1072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
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941
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Lin X, Zhuang Z, Costa M. Analysis of residual amino acid--DNA crosslinks induced in intact cells by nickel and chromium compounds. Carcinogenesis 1992; 13:1763-8. [PMID: 1423835 DOI: 10.1093/carcin/13.10.1763] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Chinese hamster ovary cells were incubated with radioactive amino acids, the DNA was isolated by standard proteinase K/phenol/chloroform extraction and residual amino acids complexed to the DNA were examined as an index of metal induced DNA-protein crosslinks. Using this method, both chromate and nickel caused residual histidine and cysteine to be complexed with the DNA isolated from metal-treated cells. In the case of chromate, a number of amino acids were studied and Tyr, Thr and Cys were found to be complexed to DNA at a level (above the untreated control) that was statistically significant. Stability studies indicated that some of the chromate-induced DNA-protein complexes were mediated by direct participation of chromium(III), whereas others that were resistant to dissociation by EDTA and mercaptoethanol did not seem to involve direct chromium(III) participation. A significant portion of the cysteine complexed to DNA by chromate was believed to involve glutathione since treatment of cells with cycloheximide did not decrease chromate-induced cysteine-DNA crosslinks. In the case of nickel, most of the stable DNA-protein crosslinks did not involve direct metal participation and were probably oxidatively mediated by Ni(II)/Ni(III) redox cycling. These findings present new methodology for analysis of DNA-protein crosslinks by examination of residual amino acids associated with the DNA. This method should be highly sensitive and will yield important information about the mechanism of metal-induced DNA-protein crosslinks.
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Lin Y, Fusek M, Lin X, Hartsuck JA, Kezdy FJ, Tang J. pH dependence of kinetic parameters of pepsin, rhizopuspepsin, and their active-site hydrogen bond mutants. J Biol Chem 1992; 267:18413-8. [PMID: 1526982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The pH dependence of the kinetic parameters of pepsin, rhizopuspepsin, and their active-site hydrogen bond mutants has been determined. These data have permitted the calculation of two active-site ionization constants in the free enzymes (pKe1 and pK32) and in the enzyme-substrate complexes (pKes1 and pKes2). The pKe1 of rhizopuspepsin (2.8) is near that of a normal carboxyl group and near the pKe1 of human immunodeficiency virus type 1 (HIV-1) protease (3.32) (Ido, E., Han, H. P., Kezdy, F. J., and Tang, J. (1991) J. Biol. Chem. 266, 24359-24366). The pKe1 of pepsin (1.57) is thus abnormally low. The pKe2 of rhizopuspepsin (4.44) is lower than that of pepsin (5.02) and HIV protease (6.80). The binding of substrate to rhizopuspepsin causes the lowering of pKes1 to 1.8 and the elevating of pKes2 to above 6. The pK alpha shifts due to substrate binding are much less pronounced in pepsin. Thus, the two enzyme-substrate complexes have similar pK alpha values. For both pepsin and rhizopuspepsin, the removal of hydrogen bonds to the active-site carboxyls by mutagenesis results in negligible changes in the four pK alpha values. The major alteration caused by these mutations is the decrease in kcat values, while there is little change in Km. These observations suggest that these hydrogen bonds to the active-site aspartyls contribute little to the pH-activity relationships of the aspartic proteases. The role of the active-site hydrogen bonds may well be to preserve the conformational rigidity of the catalytic apparatus.
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Huang YS, Lin X, Smith RS, Redden PR, Jenkins DK, Horrobin DF. Effect of dietary linoleic acid content on the distribution of triacylglycerol molecular species in rat adipose tissue. Lipids 1992; 27:711-5. [PMID: 1487970 DOI: 10.1007/bf02536030] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The present study examined the effect of varying dietary linoleate intake (0.01, 0.24, 2.4, 24, 80 or 160 g/kg diet) for 24 weeks on the distribution of triacylglycerol (TG) molecular species in rat epididymal adipose tissue. Adipose TG fractions were purified by thin-layer chromatography and separated into different molecular species by reverse-phase high-performance liquid chromatography. The identification of TG species was based on fatty acid composition, retention time and the theoretical carbon number. When the dietary 18:2n-6 content was equal to or less than 24 g/kg, no significant amounts of n-6 fatty acids (mainly 18:2n-6) were observed in adipose tissue TG despite the fact that the levels of 20:4n-6 in liver phospholipids increased significantly. There were 12 major molecular species in adipose tissue when the dietary 18:2n-6 content was less than 2.4 g/kg. When the dietary 18:2n-6 content reached 24 g/kg, an additional six TG species containing one, two or three molecules of 18:2n-6 were observed. The levels of TG molecules containing two or three 18:2n-6 residues were further increased when the diet contained very large amounts of linoleic acid (160 g/kg). Conversely, those TG species containing only one 18:2n-6 residue became less abundant. It is suggested that the accumulation of these linoleate-rich TG molecular species in adipose tissue, particularly di- and trilinoleoyl containing TG, is the result of an adequate or an excessive intake of linoleic acid.
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944
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Mao M, Yang J, Liu K, Yang G, Sun Z, Lin X. [Biochemical and immunological characterization of desmosomal proteins]. HUA XI YI KE DA XUE XUE BAO = JOURNAL OF WEST CHINA UNIVERSITY OF MEDICAL SCIENCES = HUAXI YIKE DAXUE XUEBAO 1992; 23:370-3. [PMID: 1304537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Desmosmoes were dissolved by incubation at 100 degrees C for 30 minutes in lysis buffer containing 9.5 M urea. SDS-PAGE revealed seven high molecular weight (> 67 kd) bands and some keratins. Seven of these were considered to be major bands. Bands 1 and 2 with M(r) values of 250 kd and 215 kd, called desmoplakins I and II. Polypeptide bands 3, 4a 4b, 5 and 6 had M(r) values of 165kd, 130kd, 115kd, 83kd and 75kd, respectively. 2-2.5mg of Desmoplakin I was obtained by a preparative electrophoresis; the purity reached 93.1%. The isoelectric pH range was between 6.8 and 7.2, and the amino acid compositions displayed a relatively high content of glycine. It was found that McAb Desmoplakin I recognized specifically the 250kd antigenic band by immunoblotting.
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Lin Y, Fusek M, Lin X, Hartsuck J, Kezdy F, Tang J. pH dependence of kinetic parameters of pepsin, rhizopuspepsin, and their active-site hydrogen bond mutants. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)36978-9] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Abstract
We have previously reported the isolation, characterization, and gene sequence of a new thermostable acid protease, thermopsin, from Sulfolobus acidocaldarius, a thermophilic archaebacterium. Thermopsin is similar to aspartic protease pepsin in specificity and pH dependence. However, it optimally catalyzes in the temperature range of 85 to 90 degrees C and it is not structurally related to pepsin. The current report describes the synthesis of recombinant thermopsin in E. coli and in insect cells. Several recombinant thermopsin fusion proteins were expressed as "inclusion bodies" in the cytosol of E. coli. Active thermopsin preparations were obtained by refolding from urea solutions. Recombinant thermopsin was also expressed in insect cells using a baculovirus expression system. The thermostability of recombinant thermopsin is similar to that of the native enzyme.
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Lin X, Guo S, Hou Q, Cui R, Kang Y. [The effects of dachengqi decoction, shaogan decoction, emodin and sennoside on the histamine level of intestinal mucosa in intestinally obstructed rats]. ZHONGGUO ZHONG YAO ZA ZHI = ZHONGGUO ZHONGYAO ZAZHI = CHINA JOURNAL OF CHINESE MATERIA MEDICA 1992; 17:427-9, 447. [PMID: 1445650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The experimental intestinal obstruction model was made by partly ligating the ileum in rat. The histamine levels of obstruction groups (8.14 +/- 2.28 micrograms/g) were obviously lower than those of control groups (P < 0.01). After administration of Dachengqi decoction, Shaogan decoction, emodin and sennoside, the levels of histamine were significantly higher than those of obstruction groups, but there were no significant differences as compared with control groups.
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Antonelli P, Bradbury R, Kazarinoff N, Lin X, Reichelt R. Large-scale starfish waves and reefal connectance. Ecol Modell 1992. [DOI: 10.1016/0304-3800(92)90017-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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949
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Matsuki K, Grumet FC, Lin X, Gelb M, Guilleminault C, Dement WC, Mignot E. DQ (rather than DR) gene marks susceptibility to narcolepsy. Lancet 1992; 339:1052. [PMID: 1349071 DOI: 10.1016/0140-6736(92)90571-j] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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950
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Antonelli P, Lin X, Bradbury R. On Hutchinson's competition equations and their homogenization: a higher-order principle of competitive exclusion. Ecol Modell 1992. [DOI: 10.1016/0304-3800(92)90038-g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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