Biomedical subjects

W Cao

Publications and source records attributed to W Cao.

At least 91 records · Page 5Linked to original sources

PubMed1999

[Genetic polymorphisms of serum orosomucoid in Han population in Nanjing of China].

OBJECTIVE: To determine the genetic polymorphisms of serum orosomucoid (ORM) in Han population in Nanjing of China and provide genetic data for studying the individual variance in the plasma protein binding of weak alkaline drugs. METHODS: The desialylated sera from 220 unrelated subjects were analyzed by isoelectric focusing on polyacrylamide gels followed by immunoblotting. RESULTS: The band patterns of ORM showed that the polymorphism of the structural locus ORM1 was controlled by three codominant autosomal alleles, ORM1*F1, ORM1*F2 and ORM1*S, which presented five phenotypes, ORM1 F1(47.27%), ORM1 S(5.46%), ORM1 F1F2 (3.18%), ORM1 F1S(43.64%), and ORM1 F2S(0.45%). The allele frequencies were: ORM1*F1=0.7068, ORM1*F2=0.0182, ORM1*S=0.2750. CONCLUSION: The ORM1 locus is polymorphic and the ORM2 locus is monomorphic in sera from the Han people in Nanjing of China.

Alleles↗

PubMed1999

[The relationship between apolipoprotein E gene polymorphism and coronary heart disease and arteriosclerotic cerebral infarction].

OBJECTIVE: To detect the relationship between ApoE gene polymorphism and coronary heart disease(CHD), arteriosclerotic cerebral infarction(ACI). METHODS: Exon 4 of ApoE gene was analyzed in normal group(87 cases), CHD group(78 cases) and ACI group(55 cases) by a combination of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct AgNO(3) staining technique. RESULTS: Between the control group and CHD group, ACI group, chi(2) test showed no significant difference in genotype of E3/E3 (P>0.5, P>0.1, respectively); while mu test showed no significant difference in allele epsilon(2)(P>0.25, P>0.1, respectively), epsilon(4)(P>0.1, P>0.25, respectively) of ApoE. CONCLUSION: No relationship between ApoE gene polymorphism and CHD and ACI was noted in this study.

Apolipoproteins E↗

PubMed1999

[Effects of microwave baking on the immunological cells in primary lymphedema patients].

OBJECTIVE: To elucidate the effects of microwave on the immunological cells in primary lymphedema. METHODS: The immunological cells including lymphocytes in the affected limb skin and peripheral blood of 10 patients with primary lower limb lymphedema were analysed using ABC and APAAP immunohistochemical methods before and after microwave baking and bandaging treatment. RESULTS: It is demonstrated that in the peripheral blood of the patients there was an increase of CD8+ T lymphocytes as well as a decrease of CD4+ T lymphocytes and the ratio of CD4/CD8. It was found that there was significant perivascular infiltration of mononuclear cells (most were monocytes and macrophages) in the skin of the affected limb. CONCLUSION: Microwave modulates the systemic immunological imbalance by its heating and complex biological effects on primary lymphedema patients through reversing the ratio of CD4/CD8 to normal level by increasing CD4+ T lymphocytes and decreasing CD8+ T lymphocytes. It can also decrease the perivascular T-lymphocyte infiltration of the affected dermis and enhance the phagocytic capabilities by promoting the proteolytic activities of macrophages, finally resulting in edema resolution.

Adolescent↗

PubMed1999

Effects of microwave heating on systemic and local infiltrating lymphocytes in patients with chronic limb lymphedema.

OBJECTIVES: To observe the characteristics of lymphocyte phenotypes in systemic and local skin and to evaluate the effects of microwave heating and bandaging treatment on chronic limb lymphedema. METHODS: Totally 27 patients with lymphedema and 10 normal subjects were examined with alkaline phosphatase-anti-alkaline phosphatase (APAAP) and avidin-biotin-peroxidase (ABC) immunohistochemistry for the observation of systemic lymphocyte phenotypes and inflammatory cell infiltration of skin tissues. RESULTS: In the peripheral blood of patients with chronic limb lymphedema, the number of CD4 T lymphocytes and the ratio of CD4/CD8 decreased, while the number of CD8 T lymphocytes increased. Obvious dermal perivascular infiltration of T lymphocytes was also observed. After two courses of microwave heating and bandaging treatment, the number of CD4 T lymphocytes augmented and the decreased CD4/CD8 ratio returned to normal, and the number of CD8 T lymphocytes reduced. The perivascular T lymphocyte infiltration in the dermis resolved and the number of macrophages elevated. CONCLUSION: Microwave heating and bandaging treatment can regulate the imbalance of systemic and local immunity in patients with chronic lymphedema.

Adolescent↗

PubMed1999

[Multiple tumor suppressor 1/p16 gene alterations in human esophageal squamous-cell carcinoma: clinical significance and regional difference].

OBJECTIVE: To further understand multiple tumor suppressor 1/p16 (mts1/p16) gene alterations in squamous-cell esophageal carcinoma (EC) in relation to its biologic behavior and regional difference. METHODS: Samples of human EC from 92 patients residing in Zhejiang province and in Linxian, Henan province were analyzed for the expression, mutation and deletion of the multiple tumor suppressor gene (mts1/p16) by immunohistochemical staining, polymerase chain reaction and single strand conformation polymorphism. RESULTS: mts1/p16 expression at protein level was demonstrated in 44 cases (47.8%). Gene deletion was detected in 22 cases (23.9%) and point mutation in 5 cases (5.4%). Expression of mst1/p16 showed significant correlation with pathologic staging, lymph node status and survival. However, deletion of mst1/p16 did not show correlation with the clinico-pathologic parameters. EC patients in stage T2 from Linxian had significantly lower rate of mst1/p16 protein expression compared to those from Zhejiang province at the same time period. Moreover, there was close association between gene alterations (mutation + deletion) and frequency of lymph node metastasis in Zhejiang EC patients. No such association was observed in EC patients from Linxian. CONCLUSION: msts1/p16 gene alteration is a common genetic event in the carcinogenesis and progression of human esophageal cancer. EC patients from two different regions present differential alterations in mst1/p16 gene.

Carcinoma, Squamous Cell↗

PubMed1999

[Role of glutathione S-transferase pi in tumor drug resistance].

OBJECTIVE: To establish the cytologic expressing system for the glutathione S-transferase pi (GST-pi) cDNA. METHODS: The pSV-GT, a recombinant plasmid containing rat GST-pi cDNA and the pSV-neo, a vector plasmid, were transfected the HeLa cells respectively and then G418 resistant colonies were isolated. The degree of the expression of GST-pi mRNA in the resultant cell lines was estimated by in situ hybridization using Digoxin-labelled probe cDNA. Cytotoxicity of variant anticancer drugs on the transfected cells were estimated by MTT assays. RESULTS: Two subclones, HeLa/pSV-GT, and HeLa/pSV-neo, which transfected respectively by pSV-GT and pSV-neo, were established. HeLa/pSV-GT expressed significantly high degree of the GST-pi mRNA, where as both the HeLa/pSV-neo and the HeLa cell lines showed the similar but negligible degree of the GST-pi mRNA expression. Moreover, HeLa/pSV-GT cells were insensitive to adriamycin, mitomycin C, and cisplatinum as compared to HeLa/pSV-neo. Concentrations of adriamycin producing 50% inhibition (IC50) to HeLa/pSV-GT was 70.13 micrograms/ml, highly elevated 6.78-fold of that of HeLa/pSV-neo, to which IC50 was 10.34 micrograms/ml.IC50 of mitomycin and cisplatinum to HeLa/pSV-GT were 10.95 and 16.52 micrograms/ml respectively, slightly but significantly higher than those to HeLa/pSV-neo, which were 7.48 and 13.70 micrograms/ml. But the cytotoxicity of vincristine on the two cell lines were not significantly different. CONCLUSIONS: These findings suggeste that HeLa/pSV-GT cell line, after being transfected with GST-pi cDNA, acquired drug-resistance property and the overexpression of GST-pi mRNA may contribute to the multidrug resistance of HeLa/pSV-GT cells. This cell line, as a stable cytogenetic system, will contribute more for the observation of GST-pi and drug resistance.

Antineoplastic Agents↗

PubMed1998

Identification of alpha-dystroglycan as a receptor for lymphocytic choriomeningitis virus and Lassa fever virus.

A peripheral membrane protein that is interactive with lymphocytic choriomeningitis virus (LCMV) was purified from cells permissive to infection. Tryptic peptides from this protein were determined to be alpha-dystroglycan (alpha-DG). Several strains of LCMV and other arenaviruses, including Lassa fever virus (LFV), Oliveros, and Mobala, bound to purified alpha-DG protein. Soluble alpha-DG blocked both LCMV and LFV infection. Cells bearing a null mutation of the gene encoding DG were resistant to LCMV infection, and reconstitution of DG expression in null mutant cells restored susceptibility to LCMV infection. Thus, alpha-DG is a cellular receptor for both LCMV and LFV.

Amino Acid Sequence↗

PubMed1998

Identification of TaqI endonuclease active site residues by Fe2+-mediated oxidative cleavage.

Metal cofactors (Mg2+ and Mn2+) modulate both specific DNA binding and strand cleavage in the TaqI endonuclease (Cao, W., Mayer, A. N., and Barany, F. (1995) Biochemistry 34, 2276-2283). This work attempts to establish the structural basis of TaqI-DNA-metal2+ interactions using an affinity cleavage technique. The protein was cleaved by localized hydroxyl radicals generated by oxidizing Fe2+ within the metal binding sites. Cleavage fragments were separated by SDS-polyacrylamide gel electrophoresis, and cleavage sites were determined using micropeptide sequencing. Eleven amino acid residues in the vicinity of cleavage sites were selected for site-directed mutagenesis. The negative charge at Asp137 is essential for DNA cleavage but not required for sequence specific binding. Mutations at Asp142 abolish both specific binding and catalysis, except for D142E, which converts TaqI into a completely Mn2+-dependent endonuclease. The positive charge at Lys158 appears to be important for both specific binding and catalysis. Mutations at other sites affect binding and/or catalysis to different degrees, except Trp113 and Glu135, which appear to be nonessential for the TaqI enzyme activity. The critical residues for TaqI function are distinct from the PDX14-20(E/D)XK catalytic motif elucidated from other endonucleases.

Amino Acid Sequence↗

PubMed1998

CBFbeta-SMMHC, expressed in M4eo acute myeloid leukemia, reduces p53 induction and slows apoptosis in hematopoietic cells exposed to DNA-damaging agents.

CBFbeta-SMMHC is expressed in M4Eo acute myeloid leukemia (AML) as a result of inv(16), but how it contributes to leukemogenesis is unknown. p53 mutations are rare in de novo AML, but they are common in many malignancies. Expression of CBFbeta-SMMHC in Ba/F3 cells reduced p53 induction in response to ionizing radiation or etoposide 3- to 4-fold. However, p53 induction was normal in Ba/F3 cells expressing a CBFbeta-SMMHC variant that does not interfere with DNA binding by CBF, indicating that a CBF genetic target regulates p53 induction. The p53 gene may be regulated by CBF, because p53 mRNA levels were reduced by CBFbeta-SMMHC. Reduced p53 induction was not caused by slowed cell proliferation, a consequence of CBFbeta-SMMHC expression, because p53 was induced similarly in control cultures and in cultures propagated in 10-fold less interleukin-3 (IL-3). CBFbeta-SMMHC did not slow apoptosis resulting from IL-3 withdrawal, where p53 induction is minimal, but slowed apoptosis in Ba/F3 cells exposed to 10 Gy of ionizing radiation or 3 to 8 microgram/mL etoposide, providing 2-fold protection at 6 or 18 hours. Inhibition of apoptosis was temporary, because all the cells exposed to these doses ultimately died, and clonal survival assays performed using 0. 04 microgram/mL etoposide did not show protection by CBFbeta-SMMHC. p21 levels were increased in cells subjected to DNA damage, regardless of CBFbeta-SMMHC expression and attenuated p53 induction. Bcl-2, bcl-xL, bcl-xS, and bax levels were unaffected by CBFbeta-SMMHC. Attenuated p53 induction may contribute to leukemogenesis by CBFbeta-SMMHC by slowing apoptosis via a p21-independent mechanism.

Acute Disease↗

PubMed1998

The core binding factor (CBF) alpha interaction domain and the smooth muscle myosin heavy chain (SMMHC) segment of CBFbeta-SMMHC are both required to slow cell proliferation.

We have expressed several variants of core binding factor beta (CBFbeta)-smooth muscle myosin heavy chain (SMMHC) from the metallothionein promoter in Ba/F3 cells. Deletion of amino acids 2-11 from the CBFbeta segment, required for interaction with CBFalpha, prevented CBFbeta-SMMHC from inhibiting CBF DNA binding and cell cycle progression. Deletion of 283 carboxyl-terminal residues from the SMMHC domain, required for multimerization, also inactivated CBFbeta-SMMHC. Nuclear expression of CBFbeta(Delta2-11)-SMMHC was decreased relative to CBFbeta-SMMHC. CBFbeta(Delta2-11)-SMMHC linked to a nuclear localization signal still did not slow cell growth. The ability of each CBFbeta-SMMHC variant to inhibit CBF DNA binding and cell proliferation correlated with its ability to inhibit transactivation by an AML1-VP16 fusion protein. Thus, CBFbeta-SMMHC slows cell cycle progression from G1 to S phase by inhibiting CBF DNA binding and transactivation.

Bone Marrow Cells↗

PubMed1998

[Relationship between methylenetetrahydrofolate reductase gene polymorphism and coronary heart disease].

OBJECTIVE: This study inquired into the relationship between methylenetetrahydrofolate reductase (MTHFR) gene polymorphism and coronary heart disease. METHODS: By polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP), MTHFR 677C-->T mutation was detected in 79 healthy controls and 69 patients with coronary heart disease. RESULTS: The frequency of MTHFR variant V677 of patients was significantly higher than that of healthy controls (P<0.01). CONCLUSION: This study demonstrated that MTHFR gene V677 mutation was probably one of the genetic risk factors of coronary heart disease and this provided a new basis for exploring the relevant pathogenesis.

Coronary Disease↗

PubMed1998

A serine/arginine-rich domain in the human U1 70k protein is necessary and sufficient for ASF/SF2 binding.

Critical protein-protein interactions among pre-mRNA splicing factors determine splicing efficiency and specificity. The serine/arginine proteins, a family of factors characterized by the presence of an RNA recognition motif and an arginine/serine domain, are essential for constitutive splicing and required for some alternative splicing decisions. ASF/SF2, SC35, and other members of the serine/arginine family, interact with the 70k protein of the U1 small nuclear ribonucleoprotein. The binding of this protein with ASF/SF2 is thought to enhance recognition of the 5' splice site of pre-mRNAs by the U1 small nuclear ribonucleoprotein. It has been clearly documented that the arginine/serine domain of ASF/SF2 is responsible for binding to the U1 70k protein. In this manuscript we characterize the segment in the human U1 70k protein that is both necessary and sufficient for ASF/SF2 binding. A domain within this segment, which begins with Arg240 and ends with Asp270, was shown to bind specifically to the arginine/serine domain of ASF/SF2 using a yeast two-hybrid system and a far Western assay. Mutational analysis of this segment suggested that several arginines are critical for the interaction with ASF/SF2 and for phosphorylation by SRPK1. Inspection of the sequence of the Arg248 to Asp270 region suggested this as an arginine/serine-like domain in U1 70k protein, and the data presented in this manuscript strongly support this view. Inspection of the human U1 70k protein sequence, comparison with homologues in other animal species, and mutational analysis indicated the importance of the sequence Arg-Arg-Arg-Ser-Arg-Ser-Arg-Asp, which is found repeated twice in the region from Arg248 to Asp270 in the human protein.

Amino Acid Sequence↗

PubMed1998

Cloning and thermostability of TaqI endonuclease isoschizomers from Thermus species SM32 and Thermus filiformis Tok6A1.

Two TaqI endonuclease (hereafter referred to as TaqI) isoschizomer genes, tsp32IR from Thermus species SM32 of Azores and tfiTok6A1I from T. filiformis Tok6A1 of New Zealand, were cloned in Escherichia coli. The overexpressed enzymes were partly purified and their thermostability was determined. In the medium-salt buffer, Tsp32IR, TfiTok6A1I and one previously cloned TaqI isoschizomer (TthHB8I) were more thermostable than TaqI. Tsp32IR remained partly active up to 90 degreesC in the low-salt buffer. Six amino acid residues that are identical in the three high thermostability isoschizomers (Tsp32IR, TfiTok6A1I and TthHB8I) but differ in TaqI might provide added rigidity for thermostabilization. These include four proline residues located in or near loop regions, and one alanine and one arginine located at helix regions in the predicted TaqI endonuclease secondary structure. The possible role of these residues in thermostabilization was evaluated by mutagenizing the TaqI enzyme. Mutants generated at these six positions were less thermostable than wild-type TaqI. The results suggest that the surrounding sequence or structural context might be as important as the mutation itself.

Amino Acid Sequence↗

PubMed1998

Direct quantitation of HIV by flow cytometry using branched DNA signal amplification.

Adaptation of the branched DNA signal amplification technology to flow cytometry has resulted in a quantitative nuclei-acid assay with significant advantages over the microwell-based format. In this assay, microbeads, rather than microwell plates, are derivatized with nucleic-acid capture probes and the derivatized beads are used to capture single nucleic-acid targets, which then capture fluorescent reporter probes via branched DNA. The assay detects DNA or RNA targets, has a current lower sensitivity limit of 500 human immunodeficiency virus (HIV) RNA molecules and responds linearly to target level from 500 to at least 50,000 molecules. Since microbeads can easily interrogate large volumes, viral lysis and genomic RNA capture can proceed in one step from comparatively large volumes, and sample preparation is greatly simplified compared to the microwell-format bDNA assay.

Cell Line↗

PubMed1998

Leukotriene D4-induced contraction of cat esophageal and lower esophageal sphincter circular smooth muscle.

BACKGROUND & AIMS: In esophageal circular muscle, acetylcholine activates phosphatidylcholine-specific phospholipases C and D and phospholipase A2, producing diacylglycerol and arachidonic acid, which cause contraction by interacting synergistically to activate protein kinase C. In a model of acute esophagitis, leukotriene D4 (LTD4) contributes to acetylcholine-induced contraction. We examined intracellular signaling in LTD4-induced contraction. METHODS: Esophageal and lower esophageal sphincter (LES) cells, isolated by enzymatic digestion, were contracted by LTD4 in the absence or presence of inhibitors. Permeabilization by saponin allowed use of G-protein antibodies and heparin. RESULTS: Esophageal contraction was inhibited by pertussis toxin, Gi3 antibodies, D609 (phosphatidylcholine-specific phospholipase C inhibitor), propranolol (phospholipase D pathway inhibitor), and chelerythrine (protein kinase C antagonist) but not W7 (calmodulin antagonist). LES contraction was unaffected by pertussis toxin. It was inhibited by Gq antibodies, U-73122 (phosphatidylinositol-specific phospholipase C inhibitor), heparin (inositol 1,4,5-trisphosphate inhibitor), and W7 and reduced by D609. CONCLUSIONS: In the esophagus, LTD4 activates a protein kinase C-dependent pathway through pertussis toxin-sensitive Gi3 proteins and phosphatidylcholine-specific phospholipase. In the LES, LTD4 activates a calmodulin-dependent pathway through pertussis toxin-insensitive Gq proteins and phosphatidylinositol-specific phospholipase C. The intracellular pathways activated by LTD4 in the esophagus and the LES are similar to those activated by acetylcholine and other agonists.

Animals↗

PubMed1998

Role of the Ped gene and apoptosis genes in control of preimplantation development.

PURPOSE: The properties of the mouse Ped gene and the genes that mediate apoptosis in mediating preimplantation embryonic survival were reviewed. METHODS: Preimplantation mouse oocytes and embryos were evaluated microscopically and biochemically for rate of development, degree of fragmentation, and gene expression to correlate these characteristics with embryo mortality, Biochemical assays included PCR for DNA analysis, RT-PCR for mRNA analysis, immuno-PCR for protein analysis, and TUNEL assay for assessment of apoptosis. RESULTS: Using the mouse as a model system we have identified a gene that controls the rate of development, the Ped gene. The Ped gene product is a class Ib major histocompatibility complex protein called the Qa-2 antigen. Research to understand the molecular mechanisms of Ped gene action and to identify the human homologue of the Ped gene is under way. We have also shown using the mouse model, that fragmented embryos show the morphological and biochemical characteristics of apoptosis. Genes in the two major gene families that regulate apoptosis, the caspase and Bcl-2 families, are expressed in mouse oocytes and preimplantation embryos. CONCLUSIONS: Preimplantation embryonic survival depends on two major morphological parameters: rate of development and degree of fragmentation. A fast rate of development and a low degree of fragmentation lead to a better chance of producing live offspring. Both rate of development and degree of fragmentation are genetically controlled, the former by the Ped gene and the latter most likely by genes that mediate apoptosis. It seems probable that regulation of apoptosis will prove to be a major mechanism that mediates oocyte and preimplantation embryonic survival.

Animals↗

PubMed1998

Response of potatoes to nitrogen concentrations differ with nitrogen forms.

Two separate experiments were conducted to investigate plant growth and mineral composition of potatoes (Solanum tuberosum L.) at varied solution concentrations of nitrate (NO3-) and ammonium (NH4+). Each experiment evaluated five nitrogen (N) concentrations of 0.5, 2, 4, 8, and 12 mM, which were maintained with a non-recirculating nutrient film system in controlled environment. Plants were harvested on day 42 with NO3-; and day 35 with NH4+ after transplanting of tissue culture plantlets, and growth measurements were taken as leaf area, tuber number, and dry weights of different parts. With NO3-, plant growth was greatest and similar at 2, 4, and 8 mM of N whereas with NH4+, plant growth was best only at 2 and 4 mM of N. At 12 mM of N, plants exhibited interveinal ammonium toxicity with NH4+ nutrition, but healthy growth appearance with NO3- nutrition. With either N form, total N concentrations in tissues tended to increase with increased N concentrations, and tissue phosphorus (P) concentrations were reduced at 0.5 and 2 mM of N. Tissue concentrations of calcium (Ca), magnesium (Mg), and sulfur (S) changed only slightly at particular N concentrations, yet changed substantially with different N forms. The data indicate that the optimal ranges of N concentrations in both solution and tissues are wider and higher with NO3- than with NH4+ nutrition, and thus a careful control of NH4+ concentrations is necessary to minimize possible ammonium toxicity to potato plants.

Biomass↗

PubMed1998

Genetic regulation of egg and embryo survival.

In both mice and humans, 15-50% of embryos die during the preimplantation period from mechanisms that are largely unknown. Two major criteria predict preimplantation embryo quality, the rate of development and the degree of fragmentation. We review evidence that both of these criteria have a genetic basis. Rate of development and subsequent embryo survival are controlled by a gene, Ped, we discovered in the mouse. Although progress is being made in the search for the human homologue of the mouse Ped gene, it has not yet been identified. Fragmentation, observed in both mouse and human embryos, is probably the result of apoptosis. We analysed transcription of two genes that regulate apoptosis, bcl-2 and bax, and found that both are transcribed in mouse and human preimplantation embryos. Overall, the literature reviewed and new data presented in this paper support the concept that there is a genetic basis for preimplantation egg and embryo survival.

Animals↗