Manganese mercury thiocyanate (MMTC) glycol monomethyl ether
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Journal Article↗
Biomedical subjects
D Xu
Publications and source records attributed to D Xu.
Polymeric diaquatetra-mu;-thiocyanato-manganese(II)mercury(II) bis(N,N-dimethylacetamide) solvate.
In the title complex, ¿[MnHg(SCN)(4)(H(2)O)(2)].2C(4)H(9)NO¿(n), each Mn atom is octahedrally coordinated to four equatorial thiocyanate N atoms and two axial water O atoms. The Mn atom and two O atoms lie on a twofold axis. Two kinds of crystallographically independent Hg atoms (denoted Hg1 and Hg2) are tetrahedrally coordinated with four thiocyanate S atoms and each Hg atom lies on a -4 axis. N,N-Dimethylacetamide molecules are connected to coordinated water molecules through hydrogen bonds. Each pair of Mn and Hg atoms is bridged via one thiocyanate ion. An Mn(2)Hg1Hg2(SCN)(4) 16-membered ring is formed as a unit and the four metal atoms are in a chair-form tetrahedral arrangement. The units are linked with one another and form infinite two-dimensional networks.
Journal Article↗
Cubilin expression and posttranslational modification in the canine gastrointestinal tract.
Cubilin is an endocytic receptor of the apical brush border membrane that is essential for intrinsic factor-mediated cobalamin absorption in small intestine. However, cubilin is more highly expressed in kidney and yolk sac, and recent molecular characterization of the receptor has focused on these tissues. The aim of this investigation was to examine tissue-specific cubilin expression and posttranslational modifications with an emphasis on the gastrointestinal tract. Intrinsic factor-cobalamin binding activity, cubilin immunoreactivity, and cubilin mRNA levels were determined in multiple segments of canine gastrointestinal mucosa and other tissues. These aspects of cubilin expression varied in parallel, suggesting that the major determinant of regional cubilin expression in the gastrointestinal tract is modulation of cubilin mRNA. Cell fractionation indicated that ileal cubilin is not strongly membrane associated. An approximately 185-kDa brush border specific and two >400-kDa precursor forms of cubilin were identified. Asparagine-linked oligosaccharide modifications characterized by differential glycosidase digestion of affinity-purified cubilin from ileal mucosa and renal cortex differed, but ileal and renal intracellular cubilin comigrated on SDS-PAGE at approximately 400 kDa after oligosaccharide removal, thus reconciling previous conflicting size estimates of the cubilin polypeptide.
Animals↗
Interleukin-2: structural and biological relatedness to opioid peptides.
Interleukin (IL)-2 is not only an immunoregulatory factor, but also an analgesic molecule. There are distinct domains of immune and analgesic functions in the IL-2 molecule. The analgesic domain is located around the 45th Tyr residue of human IL-2 in tertiary structure. Antiopioid (beta-endorphin, Leu-enkephalin, Met-enkephalin and dynorphin A1-13) sera partially neutralized the analgesic activity of IL-2. Monoclonal antibody against the IL-2 receptor alpha subunit (Tac) could not block the analgesic activity of IL-2. There existed cross-reactivity between IL-2 and antiopioid sera by indirect ELISA. These studies show strong structural and biological similarities between IL-2 and opioid peptides. The tertiary structure around the 45th residue of IL-2 composes the analgesic domain that is similar to that of endogenous opioids. These results are consistent with the hypothesis that multiple domains of cytokines serve as the structural bases for the immunoregulatory and neuroregulatory effects of cytokines.
Analgesics↗
P-Glycoprotein inhibitor valspodar (PSC 833) increases the intracellular concentrations of daunorubicin in vivo in patients with P-glycoprotein-positive acute myeloid leukemia.
PURPOSE: The aim of the present study was to evaluate the effect of the cyclosporine derivative valspodar (PSC 833; Amdray, Novartis Pharma, Basel, Switzerland) on the concentration of daunorubicin (dnr) in leukemic blast cells in vivo during treatment. PATIENTS AND METHODS: Ten patients with acute myeloid leukemia (AML) were included. Leukemic cells from seven of the patients were P-glycoprotein (Pgp)-positive. dnr 100 mg/m(2) was given as a continuous infusion over 72 hours. After 24 hours, a loading dose of valspodar was given, followed by a 36-hour infusion of 10 mg/kg per 24 hours. Blood samples were drawn at regular intervals, and concentrations of dnr and its main metabolite, daunorubicinol, in plasma and isolated leukemic cells were determined by high-pressure liquid chromatography. RESULTS: The mean dnr concentrations in leukemic cells 24 hours after the start of infusion (before valspodar) were 18.8 micromol/L in Pgp-negative samples and 13.5 micromol/L in Pgp-positive samples. After 8 hours of valspodar infusion, these values were 25.8 and 24.0 micromol/L, respectively. The effect of valspodar was evaluated from the ratio of the area under the curve (AUC) for dnr concentration versus time in leukemic cells to the AUC for dnr concentration against time in the plasma. For the seven patients with Pgp-positive leukemia, the mean ratio increased by 52%, from 545 on day 1 to 830 on day 2 (P<.05) when valspodar was given. In the three patients with Pgp-negative leukemia, no significant difference was observed. CONCLUSION: These results strongly suggest that valspodar, by interacting with Pgp, can increase the cellular uptake of dnr in leukemic blasts in vivo.
ATP Binding Cassette Transporter, Subfamily B, Mem↗
Computational tools for protein modeling.
Protein modeling is playing a more and more important role in protein and peptide sciences due to improvements in modeling methods, advances in computer technology, and the huge amount of biological data becoming available. Modeling tools can often predict the structure and shed some light on the function and its underlying mechanism. They can also provide insight to design experiments and suggest possible leads for drug design. This review attempts to provide a comprehensive introduction to major computer programs, especially on-line servers, for protein modeling. The review covers the following aspects: (1) protein sequence comparison, including sequence alignment/search, sequence-based protein family classification, domain parsing, and phylogenetic classification; (2) sequence annotation, including annotation/prediction of hydrophobic profiles, transmembrane regions, active sites, signaling sites, and secondary structures; (3) protein structure analysis, including visualization, geometry analysis, structure comparison/classification, dynamics, and electrostatics; (4) three-dimensional structure prediction, including homology modeling, fold recognition using threading, ab initio prediction, and docking. We will address what a user can expect from the computer tools in terms of their strengths and limitations. We will also discuss the major challenges and the future trends in the field. A collection of the links of tools can be found at http://compbio.ornl.gov/structure/resource/.
Algorithms↗
Heterogeneity of isolated mononuclear cells from patients with acute myeloid leukemia affects cellular accumulation and efflux of daunorubicin.
BACKGROUND AND OBJECTIVE: Pharmacologic studies on blasts from patients with leukemia are generally performed on density gradient isolated blood or bone marrow cells. Thereby, cellular drug accumulation and efflux are determined as mean values of the entire cell population. The objective of the present study was to characterize the heterogeneity in the accumulation and efflux of daunorubicin in various subpopulations of mononuclear cells isolated from patients with acute myeloid leukemia (AML). DESIGN AND METHODS: Mononuclear cells from 33 patients with AML were isolated from peripheral blood by density gradient centrifugation on Lymphoprep (1. 077 g/mL). Cellular accumulation of fluorescent daunorubicin was determined by flow cytometry after incubation of the cells at +37C for 1 hour. Thereafter, the cells were washed and reincubated in drug-free medium. Kinetics of drug efflux were determined by frequent determination of cellular fluorescence during 30 min. Daunorubicin accumulation and efflux were compared in the total isolated mononuclear cell population and in the various blast cell populations gated on FSC/SSC according to the results of immunophenotyping. RESULTS: In 8 of these 33 (24%) patient samples, two distinct blast cell populations could be identified. In 7 out of 8 these cases the more immature blasts had a lower drug accumulation and in 6 out of the 8 cases also a higher efflux rate than the differentiating cell population. Cyclosporin A increased daunorubicin accumulation and reduced efflux in the immature blast population. In the differentiating cell population cyclosporin A increased both the accumulation and the efflux. In patients with a single blast cell population, the gated blast cells had a significantly lower drug accumulation but also a lower drug efflux rate than the total cell population. INTERPRETATION AND CONCLUSIONS: The results imply that drug transport studies on cells isolated from patients with AML give somewhat different results depending on the cell population studied. Some, but not all, of these differences in daunorubicin accumulation and efflux as well as in the effect of cyclo-sporin A can be explained by a heterogenous expression of the mdr1-gene. The observed heterogeneity may be of special relevance with regard to drug resistance. The presence of even a small resistant cell clone may jeopardize the effect of the chemotherapy due to expansion resulting in relapse of disease.
Acute Disease↗
A binuclear manganese(II) complex, decaaqua(mu-1,2,4,5-benzenetetracarboxylato-O1:O4)dimanganese(II) hydrate
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Journal Article↗
Inhibitory effect of PGE2 on EGF-induced MAP kinase activity and rabbit corneal epithelial proliferation.
PURPOSE: To determine in rabbit corneal epithelial cells in culture whether epidermal growth factor (EGF)-induced increases in prostaglandin (PG) E2 production inhibit both the extracellular signal-regulated kinase 2 (Erk-2), a mitogen-activated protein kinase (MAPK), cascade activation, and the mitogenic response to this growth factor. METHODS: Serum starvation for 24 to 36 hours was used to synchronize cultures of SV40-transformed rabbit corneal epithelial (RCE) cells. The effects of exogenous PGE2, inhibition of PGE2 synthesis, and modulation of protein kinase A (PKA) activity on EGF-induced Erk-2 activation were assessed by immunoprecipitation, kinase assays, and Western blot analysis. PGE2 synthesis was measured by using enzyme-linked immunosorbent assay. [3H]-Thymidine incorporation was used to measure RCE cell proliferation rates. RESULTS: EGF (5 ng/ml) significantly increased PGE2 production in a time-dependent manner up to 94%+/-8% after 3 hours. EGF-induced PGE2 production was suppressed by AACOCF3, a phospholipase A2 (cPLA2) inhibitor. EGF-induced Erk-2 activation reached a maximal level at 15 minutes, followed by a decline toward the control level after 3 hours. In the presence of either PGE2 (50 microg/ml) or 8-CPT-cAMP (100 microM), the EGF-induced Erk-2 activation was lessened. PKA was activated by applications of EGF or PGE2 and suppressed by AACOCF3. On the other hand, either inhibition of PGE2 production with AACOCF3 or H-89, a PKA inhibitor, enhanced EGF-induced Erk-2 activity. Raf-1 activity was stimulated by EGF to maximal activity at 5 minutes and returned toward its control level after 60 minutes. As with the dependence of Erk-2 activity on PKA activity, in the presence of H-89, the EGF-induced Raf-1 activation was significantly enhanced. DNA synthesis was increased 59%+/-5% (n = 4) after EGF stimulation, indicating a mitogenic effect of EGF in RCE cells. Inhibition of cPLA2 activity with AACOCF3 increased DNA synthesis in RCE cells by another 64% relative to the effect of EGF alone. In contrast, with either PGE2 or 8-CPT-cAMP present the mitogenic response to EGF was totally suppressed. CONCLUSIONS: EGF-induced increases in PGE2 production dampened the mitogenic response to this growth factor. This suppression appears to be a consequence of PGE2-elicited increases in PKA activity, which leads to inhibition of EGF-induced activation of MAPK cascades at the level of Raf-1 and further affects downstream events including Erk-2. These results indicate that the mitogenic response to EGF in vivo in the proliferating basal cell layer may be dependent on the level of its PKA activity.
Animals↗
[Detection of DNA strand breakage in human spermatozoa by use of single-cell gel electropheresis].
OBJECTIVE: To establish the single-cell gel electropherosis (SCGE) protocol for detection of DNA strand breakage in human spermatozoa. METHODS: The slides on which sperm cells and agarose were layered were immersed in a cold lysing solution of pH10 to lyse the sperm cells. Sperm nuclei were then pretreated with 10 mmol/L of DTT for 1 h, 10 microg/ml of RNase A for 4 h and 200 microg/ml of proteinase K for 15 h. Lastly, electrophoresis was performed in electrophoresis running buffer(pH10) at 12V (0.46V/cm) and 100 mA for 1 h. Sperm nuclei were stained with 15 microg/ml of EtBr for 5 min. The percentage of comet cells was counted. The in vitro hydrogen peroxide-induced DNA damage in human spermatozoa was measured with SCGE established by this laboratory. RESULTS: The comet sperm cells in human spermatozoa ranged from 2% to 38%. There was a significant variance on the percentage of comet cells between different subjects. Hydrogen peroxide increased the percentage of comet sperm in a dose- and time-dependent manner. CONCLUSION: SCGE may be used to detect DNA strand breakage in human spermatozoa. Hydrogen peroxide-induced DNA damage in human sperm cells was detected successfully using SCGE protocol established by this laboratory.
DNA Damage↗
[ABO genotyping by PCR-direct sequencing method].
OBJECTIVE: To analyze the sequence difference between human A, B, and O alleles and establish the method of ABO genotyping by PCR direct sequencing. METHODS: PCR-direct sequencing technique was used to analyze two regions of cDNA from A transferase gene, 233-433 and 660-788. RESULTS: Two nucleotide substitutions at 258th and 297th were found in 233-433 region, and a nucleotide substitution at 700th was found in 660-788 region. At 258th, the nucleotide was guanine in A and B alleles, and adenine in O allele. At 297th, the nucleotide was adenine in A allele, and guanine in B allele. As this position, O allele was subdivided into two types, O(A) and O(G). At 700th, the nucleotide was guanine in A and O alleles, and adenine in B allele. Therefore, 8 genotypes, AA, AO(A), AB, BB, BO(G), O(A) O(A), O(G) O(G) and O(A) O(G), could be clearly determined by only analyzing the 233-433 region. The other two genotypes, AO(G) and BO(A), could be further distinguished by analyzing the 660-788 region. CONCLUSION: The technique of PCR-direct sequencing provides an effective and new method for ABO genotyping further.
ABO Blood-Group System↗
[Study on family aggregation of esophageal cancer in Linzhou city].
OBJECTIVE: To investigate family aggregation of esophageal cancer (EC) in Linzhou city, a high risk area for EC. METHODS: A hospital based case-control study were conducted, which included relatives of 118 EC cases and 168 controls. EC incidences in relatives of cases and controls were compared by chi 2 test and risk ratio (RR) was calculated. Heritability (h2) was estimated using the Falconer method. RESULTS: EC incidence of case relatives was significantly higher than that in control relatives. The RR was 3.15 (2.15-4.61) in the first degree relatives and 1.87 (1.26-2.79) in the second degree relatives. The heritability was (53.39 +/- 5.93)% for the first degree relatives and (50.21 +/- 10.75)% for the second degree relatives, while the weighted h2 was (52.26 +/- 3.82)%. CONCLUSION: The genetic factor plays an important role the occurrence of EC in Linzhou city; however, environmental factors should not be ignored.
Adult↗
[Expression, purification and identification of human IFN-alpha 2 b/HBV Pre S2 fusion protein].
OBJECTIVE: To express a fusion protein of human interferon-a2b and HBV Pre S2 in E.coli for the purpose of investigating anti-HBV immunomodulatory protein. METHODS: Human interferon-a2b and HBV Pre S2 encoding genes were amplified from plasmid templates through PCR, then fused and cloned into plasmid pBV220 through engineering technique to generate expression plasmid pBV-IFN-Pre S2. The plasmid was transfected into E. coli to produce fusion protein. RP-HPLC and ion-exchange chromatography were employed to purify fusion protein. RESULTS: 27 kDa fusion protein was expressed up to 15% of total bacterial protein in E. coli. After purification, the purity of fusion protein reached 95% of total protein. Anti-viral assay showed that IFN-Pre S2 protein induced a VSV-resistant activity of 1.25 x 10(8) lU/mg protein in Wish cell line, similar to the bioactivity of original recombinant human IFN-alpha 2b. ELISA data showed that IFN-Pre S2 protein had antigenicities of both human IFN-alpha 2b and HBV Pre S2. In addition, fusion protein showed the feature of binding to polymeric human serum albumin (PHSA). CONCLUSIONS: The bifunctional fusion protein was efficiently expressed in E. coli. The work provided initial evidence for studying PHSA-receptor-targeting IFN-alpha 2b,which might have potential application for the treatment of HBV infection.
Amino Acid Sequence↗
[Biological characteristics and occurrence regularity of Phassus excrescens Bulter].
The biological characterisitics and occurrence regularity of Phassus excrescens were studied from 1997 to 2000 in the eastern part of Heilongjiang Province and Jilin Province. In this area, most of its individuals took two years to finish one generation, and over-wintered two times with eggs and larvae, respectively. At the end of June or the first ten days of July, larvae transferred to damage Fraxinus mandshurica. Feeding with artificial diet indoor, the larvae finished 6 instars before pupation. In artificial Manchurican ash forest, the larva mainly damaged the truck basal(below 20 cm) or truck of 2 to 20 years old Fraxinus mandshurica. The occurrence amount of this species was closely related to the forest age and the stand structure. Usually, pure artificial Fraxinus mandshurica stands and Fraxinus mandshurica-Pinus koraiensis mixed stands were damaged seriously, while Fraxinus mandshurica-Larix mixed forests were damaged lightly.
Animals↗
[Therapeutic effect of 5-fluorocytosine on cytosine deaminase gene transduced Wilms' tumor xenograft in nude mice].
OBJECTIVE: To study the effect of 5-fluorocytosine (5-FC) as prodrug in the treatment of Wilms' tumor xenografts transduced with cytosine deaminase (CD) gene. METHODS: An in vivo model of a poorly differentiated Wilms' tumor transplanted in nude mice was established. Expression adenoviral-vector of CD gene (Ad/CMV-CD) or lac gene (Ad/CMV-lac) was transduced to the tumor xenografts by intratumoral injections. Expression of the transduced genes were confirmed by RT-PCR. Mice with Wilms' tumor xenograft were treated with 5-FC (500 mg.kg-1.d-1 x 10 d). Tumor growth was monitored. RESULTS: The growth of tumor xenografts transduced with lac gene grew as quick as the untransduced ones. In contrast, the growth of the tumor xenografts transduced with CD gene was significantly inhibited as compared to untransduced and lac gene transduced xenografts. The average rate of inhibition was 65% according to the tumor weight at 8 wk. Cell necrosis was observed in the CD gene transduced tumors. CONCLUSION: Intratumoral cytosine deaminase gene transduction followed by systemic 5-fluorocytosine is effective in the treatment of Wilms' tumor.
Animals↗
[Relationship between blast crisis of chronic myeloid leukemias and abnormality of p16 and calcitonin genes].
OBJECTIVE: To study the relationship between homozygous deletions of p16 gene and calcitonin hypermethylation and chronic myeloid leukemia (CML) blast crisis. METHODS: Semiquantitative multiplex polymerase chain reaction (PCR) was used to detect homozygous deletions of p16 gene and semiquantitative PCR to detect calcitonin gene hypermethylation in 53 CML patients. RESULTS: In 53 CML patients, homozygous deletion of p16 gene was found in none of them in chronic phase, while in 6.3% (1/16) of them in myeloid blast crisis, 66.7% (8/12) in lymphoid blast crisis, and 2/5 (40%) in mixed cell blast crisis. Calcitonin gene hypermethylation was found in 10% (2/20), 68.8%(11/16), 16.7%(2/12), and 40% (2/5), respectively. CONCLUSION: There is intimate relationship between homozygous deletions of p16 gene and CML in lymphoid blast crisis, between calcitonin gene hypermethylation and CML in myeloid blast crisis. Moreover, abnormality of both genes may be associated with mixed cell blast crisis in CML patients. Simultaneous detection of the two genes help early pickup CML patients in blast crisis.
Adult↗
[Influence of safflower injection on hemorheology of patients of chronic cor pulmonale during acute attack].
OBJECTIVE: To study the effect of safflower injection (SI) on hemorheology and fibrinolytic system in treating patients of chronic cor pulmonale during acute attack. METHODS: Sixty patients were divided into two groups, 30 in each group. Both groups were treated with conventional therapy including anti-inflammatory, relieving cough and reducing sputum, cardial, diuretic and continuous low-flow oxygen inhalation. For the SI group, additional two courses of SI injection was given intravenously for 10 days as one course with an interval of 5 days between courses. The clinical therapeutic effect in the two groups and effect of treatment on hemorheology and fibrinolytic function were observed. RESULTS: The total effective rate in the SI group was 86.7% and that in the control group was 63.3%, the difference between the two groups was significant (P < 0.05). After treatment, in the SI group, the high- and low-shear whole blood viscosity, plasma viscosity, erythrocyte agglutination index, hematocrit and fibrinogen lowered obviously, as compared with before treatment (P < 0.01 or P < 0.05), and the improvement in hemorrheologic property was better than that in the control group significantly (P < 0.05). The blood activities of anti-thrombin III, plasminogen and tectotype profibrinolytic activating factor were all higher than those in the control group (P < 0.05, P < 0.01). And SI showed more potent effect in improving anti-coagulation and fibrinolytic function of patients than that of the control (P < 0.05). CONCLUSION: SI is an effective drug for treatment of hypercoagulability status in acute stage of chronic cor pulmonale, and is worthy of clinical application.
Aged↗