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Biomedical subjects

D Ma

Publications and source records attributed to D Ma.

At least 55 records · Page 3Linked to original sources
PubMed2001

Effect of sarsasapogenin and its derivatives on the stimulus coupled responses of human neutrophils.

METHODS: The effects of three sapogenins (sarsasapogenin, tigogenin and hecogenin) on the stimulus-induced superoxide generation and protein tyrosyl phosphorylation in human neutrophils were investigated. RESULTS: When the cells were preincubated with sapogenin, three sapogenins dose-dependently suppressed the superoxide generations induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP) and phorbol 12-myristate 13-acetate (PMA), respectively. In both cases, their effects were in the order: sarsasapogenin>tigogenin>hecogenin. While sarsasapogenin suppressed the superoxide generation induced by arachidonic acid (AA) as well, the superoxide generation was scarcely suppressed by tigogenin and significantly enhanced by hecogenin. In parallel to their effects on the superoxide generation, the three sapogenins dose-dependently suppressed the fMLP-induced and PMA-induced tyrosyl phosphorylations of 45 kDa protein in neutrophils, respectively. CONCLUSIONS: Of the sapogenins tested, sarsasapogenin may have the most clinical use as it suppresses superoxide generation.

Arachidonic Acid↗
PubMed2001

Morphologic and molecular evidence for gap junctions and connexin 43 and 45 expression in annulus fibrosus cells from the human intervertebral disc.

Data are presented which provide evidence for gap junction formation and connexin (Cx) 43 and 45 gene expression in human intervertebral disc cells in vivo and in vitro. These findings in cells from the annulus are important in conjunction with the well-recognized loss of disc cells during aging and disc degeneration. As a result of this loss of cells, cell-cell communication, which we propose is an important, but as yet poorly understood, mechanism which links and coordinates cellular function throughout the entire population of disc cells, is also disrupted. These studies provide additional information on the fundamental cell biology of the disc cell and provide an additional framework for understanding aging, degeneration and potential repair of the human disc.

Aged↗
PubMed2001

Rapid preparation of short-lived alpha particle emitting radioimmunopharmaceuticals.

Alpha emitting radionuclides are of considerable interest for targeted radioimmunotherapy. Generator supplied 213Bi emitting 8.5 MeV alpha particles with a 45.6 min half-life has been conjugated to a monoclonal antibody (HuM195-CHX-A-DTPA) for targeted therapy of leukemia in a clinical trial. The clinical dose preparation of pharmaceutical formulation by a pair of skilled radiochemists took 25 min, which corresponds, to an overall decay loss of 30% of the initial 213Bi activity eluted from the generator. In order to allow more widespread and practical clinical use of targeted 213Bi alpha particle therapy, we developed a new procedure that is simpler, more rapid and adaptable to a hospital pharmacy. The new 10 min process includes a tandem elution and labeling, and an anion exchange column purification method that can be reproducibly used.

Alpha Particles↗
PubMed2001

Breakthrough of 225Ac and its radionuclide daughters from an 225Ac/213Bi generator: development of new methods, quantitative characterization, and implications for clinical use.

Bisumth-213, a short-lived alpha particle emitting radionuclide, is generated from the decay of 225Ac, which has a half-life of 10 days. The development of a clinical 225Ac/213Bi generator and the preparation of a 213Bi radiolabeled antibody for radioimmunotherapy of leukemia have been reported. The 225Ac decay scheme is complex; therefore a thorough understanding of the impact of both the parent 225Ac and its daughters on radiolabeling, purification, and quantification is necessary for optimal use of the generator system. This paper reports: (i) unique new methods to measure 221Fr, 213Bi, and 209Pb, the prominent daughters of 225Ac; and (ii) a quantitative evaluation of 225Ac/213Bi generator breakthrough and the radionuclidic purity of 213Bi labeled radiopharmaceutical dose formulations. A quantitative multi-dimensional proportional scanning method was employed to distinguish and measure specific daughter radionuclides. This method combines thin layer chromatography in two perpendicular directions with attenuated collimation as a function of time for data collection and analysis. Francium-221 and 213Bi eluted differentially from the generator, and 221Fr contributed minimally to unchelated 213Bi in the reaction and final products. Lead-209 was present in the reaction solution, but not strongly bound by the chelating moiety either (i) under the 213Bi labeling reaction conditions or (ii) following chelated 213Bi decay. As a consequence of incorporating several new procedures to the operation of the generator, 225Ac breakthrough in the final product was further reduced and represented a trivial contaminant in the final drug formulations.

Actinium↗
PubMed2001

In vitro and in vivo characterization of 67Ga(3+) complexes with cis,cis-1,3,5-triamino-cyclohexane-N,N',N"-triacetic acid derivatives.

The aim of this study was to investigate the in vitro and in vivo performance of a 67Ga complex with cis,cis-1,3,5-triaminocyclohexane-N,N',N"-triacetic acid (tachta) as a potential ligand for use as a Ga(III) radiopharmaceutical for PET imaging. The radiolabeling procedure, electrophoretic properties, lipophilicity, acid stability, human serum stability and biodistribution in mice of 67Ga(tachta) were investigated. The 67Ga(tachta) complex forms at 10(-3) M tachta concentration at 40 degrees C in 100% yield; it is neutral, non-lipophilic, 90% stable at pH = 4 and 5 and 100% stable at pH = 6, for at least 8 d. Serum stability experiments demonstrated that at 5 hr 67Ga(tachta) exists in serum as a free complex. At 24 hr, 30% of 67Ga(tachta) is reversibly bound to transferrin-albumin fraction of serum, and that this percentage remains unchanged for a period of 4 d. Biodistribution in mice showed that 67Ga(tachta) rapidly clears via the kidneys from the body with less than 10% of injected activity left in the body at 3 hours and only 6% remaining after 24 hr. The complex also cleared rapidly from all of the major organs, with bone showing some slightly increased (1.15% ID/g) 24 hr accumulation, in comparison with the 3 hr time point. Based upon these data, 67Ga(tachta) may be considered as a candidate for developing new Ga(III) radiopharmaceuticals for PET.

Animals↗
PubMed2001

Expression of cardiotoxin-2 gene. Cloning, characterization and deletion analysis of the promoter.

This report is the first study of the regulation of expression of a toxin gene and it also demonstrates the novel finding that the cardiotoxin (CTX)-2 gene from Naja sputatrix is expressed in the venom gland as well as in other tissues in the snake, such as liver, heart and muscle. The venom gland produces a 500-bp (spliced) CTX-2 mRNA as the final transcript. However, the liver produces two types of CTX-2 mRNA, of which the unspliced transcript (1 kb) is predominant; the 500 bp spliced transcript is the minor species. This differential expression of the CTX gene has been attributed to the usage of alternative promoter consisting of independent TATA boxes and corresponding transcription initiation sites. Among the several transcription factors that have been identified by a search of the TFIID database, the participation of two glucocorticoid elements in the expression of the CTX gene has been demonstrated by promoter deletion analysis. Putative binding sites for SP-1, C/EBP, CACCC-binding factor and at least two unknown binding factors have also been identified by DNase I footprinting of the promoter.

Amino Acid Sequence↗
PubMed2001

Recent advances in the discovery of protein kinase C modulators based on the structures of natural protein kinase C activators.

The natural products teleocidins, phorbol esters, asplysiatoxin, ingenol esters, and bryostatins are all potent protein kinase C (PKC) activators. The fact that they act at the same site of PKC implied that these structurally diverse molecules might contain the common structural elements. Several pharmacophores for these compounds have been proposed based on the molecular modeling studied and experimental results. In order to prove these hypotheses various simplified analogues of these compounds are designed, synthesized, and evaluated as new PKC activators. Some of the simplified analogues demonstrated much high potency to activate PKC, which not only gives some insights how these PKC activators bind with PKC, but also provides the new leads to develop the therapeutic tools to treat the diseases related by PKC.

Animals↗
PubMed2001

The role of hypertension-related gene in aortic vascular smooth muscle cells from mice and rats.

OBJECTIVE: To study the role of hypertension-related gene (HRG-1) in cardiovascular disease. METHODS: The expression of HRG-1 was analyzed with RT-PCR and Northern blotting. Vascular smooth muscle cell (VSMC) proliferation was measured with 3H-TdR incorporation and was confirmed with histological analysis. RESULTS: Northern blot analysis showed that HRG-1 mRNA was expressed not only in VSMC, but also in various rat tissues (heart, brain, lung, kidney, and liver). In addition, the expression of HRG-1 mRNA in heart, brain, kidney and liver of spontaneously hypertensive rat (SHR) was lower than that in the same tissues of Wistar-Kyotorat (WKY). Semi-quantitative RT-PCR and histological analysis showed that the expression of HRG-1 mRNA in ApoE-knockout mice and in animal models of restenosis was decreased and neointimal formation was observed in both models. ET, AII, and IL-1 stimulating VSMC proliferation reduced the expression of HRG-1 mRNA of VSMC. Atrial natriuretic factor (ANF), calcitonin gene-related peptide and adrenomedullin, inhibited VSMC proliferation and elevated the expression of HRG-1 mRNA. These effects could be blocked or attenuated by their corresponding antagonists or antibodies. CONCLUSION: HRG-1 is a gene related to VSMC proliferation. It may play an important role in several occlusive cardiovascular diseases including atherosclerosis, restenosis and hypertension.

Animals↗
PubMed2001

[An experimental study on subconjunctival interleukin-1 receptor antagonist for promotion of corneal transplant survival].

OBJECTIVE: To determine whether the subconjunctival application of interleukin-1 receptor antagonist (IL-1ra) can prolong the corneal graft survival in the rat model of orthotopic penetrating keratoplasty. METHODS: For all experiments, F344 corneas were transplanted into LOU (major histocompatibility-disparate) eyes. Experimental groups received subconjunctival injection of 50, 100 and 200 microg IL-1ra respectively, and the control group received the same volume of 0.9% normal saline instead for consecutive 2 weeks. All transplants were evaluated for 4 weeks after surgery for signs of rejection. RESULTS: The mean survival time (MST) of the grafts of the experimental groups was increased significantly (t = 0.00, P < 0.01) in comparison with the control group. The MST of the IL-1ra 200 microg group was increased significantly than that of the IL-1ra 50 microg group (t = 0.00, P < 0.01). Furthermore, the IL-1ra-treated grafts had significantly less corneal inflammation, infiltration, lower levels of opacity, edema, neovascularization and rejection index compared with the control group. CONCLUSIONS: Subconjunctival treatment of IL-1ra has a significantly positive effect on promoting corneal allograft survival. And its effect is dosage-dependent.

Animals↗
PubMed2001

[The diagnostic value of platelet glycoprotein-specific autoantibody detection in autoimmune thrombocytopenic purpura].

OBJECTIVE: To evaluate the clinical significance of platelet glycoprotein-specific autoantibody detection and platelet-associated IgG (PAIgG) measurement in the differential diagnosis between autoimmune thrombocytopenia and nonimmune thrombocytopenias. METHODS: Anti- GP II b/III a and anti-GP I b/IX autoantibodies were detected by a modified monoclonal antibody immobilization of platelet antigens assay (modified MAIPA), and PAIgG by competitive ELISA. RESULTS: Comparing with the measurement of PAIgG, the GP-specific autoantibody assay was less sensitive but much more specific for the diagnosis of autoimmune thrombocytopenia. CONCLUSION: The platelet GP-specific autoantibody detection is considerably better than PAIgG measurement in discriminating immune from nonimmune thrombocytopenia.

Adolescent↗
PubMed2001

[Prokaryotic expression of hepatitis C virus envelope 1 gene and application of the expressed product].

OBJECTIVE: To express the HCV E1 gene in E. coli cells and to demonstrate its clinical significance in detection of anti-HCV E1 antibodies. METHODS: The expression vector was constructed by ligation of HCV E1 sequence, which was amplified by RT-PCR methods from 50 microliters of HCV RNA positive serum using primers specific to the HCV E1 sequence, to the prokaryotic expression vector PMS-31b transfected POP2136 at 16 degrees C for 16 hours. The recombinant plasmid was screened out and characterized by restriction enzyme analysis. The bacteria containing the recombinant plasmid was induced at 42 degrees C for 4 hours, and the recombinant protein was visualized by SDS-PAGE. The specificity of the recombinant protein was determined by Western blot assay. After purification of the expressed protein, this protein was coated on the plate with the concentration of 2 micrograms/ml in pH 9.6 buffer at 4 degrees C for overnight, and the serum specimen was tested at the dilution of 1:20 by ELISA. RESULTS: There were 2 fragments could be seen on the SDS-PAGE after digestion of the RT-PCR product with Sma I. And there emerged one fragment of 356 bp after digesting the recombinant plasmid with Sma I and Xba I. A band of 30,000 could be seen on the SDS-PAGE after the induction of bacteria containing the recombinant plasmid pMS-E1 at 42 degrees C for 4 hours. The Western blot assay showed that the expressed band could react with the anti-HCV positive serum. The ELISA result indicated that there were 28.9% (26/90) anti-HCV positive serum were anti-HCV E1 positive, but 3.9% (3/76) were positive in the anti-HCV negative serum. CONCLUSION: The HCV E1 sequence from HCV RNA positive serum has been expressed in E. coli. The expression rate is about 17% of the total protein of the bacteria. This protein possessed good specificity and may be used in the diagnosis of HCV infection.

Antibodies, Viral↗
PubMed2001

[Detection of TTV DNA and TTV IgG in 328 serum samples].

OBJECTIVE: To investigate the prevalence of TT virus(TTV) in a variety of populations in China. METHODS: TTV DNA and anti TTV IgG were simultaneously tested by PCR and ELISA. RESULTS: The positive rate of TTV DNA in the samples of 81 normal subjects, 92 blood donors, 123 hepatitis A-G patients and 32 hepatitis non A-G patients were 2.5%, 2.2%, 19.5% and 28.1%, respectively; and anti-TTV IgG was 1.2%, 3.7%, 26.8% and 34.4%, respectively. There were significant differences between the normal and the blood donor group and the hepatitis group; and among multi-infectious cases, the infection rate of TTV with HBV was as high as 75.0%. CONCLUSION: The investigation indicated that TTV infection was very popular in different groups. Some of the normal and blood donor groups infected with TTV could become healthy carries of virus. And the hepatitis patients were the high risk group. In addition, TTV may be transmitted via other pathways besides blood.

Adult↗
PubMed2001

[Clinical diagnosis and treatment of acquired immunodeficiency syndrome complicated by tuberculosis].

OBJECTIVE: To explore the clinical characteristics and method of therapy of acquired immunodeficiency syndrome (AIDS) patients complicated by tuberculosis. METHOD: 10 cases suffered from AIDS complicated by tuberculosis from 1995 to 2000 were analyzed. RESULTS: (1) Clinical type: of the 10 cases, hematogenous disseminated tuberculosis with cerebral tuberculosis in 3, tuberculous lymphadenitis in 4 (in which one was in mesentery, one in mediastinum and neck, 2 in neck), primary pulmonary tuberculosis in 3, with other opportunistic infections, such as Pneumocystis carinii pneumonia (PCP). (2) Immunological and tuberculin test: in all 10 cases, CD4+ cells were (2 - 87) x 10(6)/L, of them 7 cases CD4+ cells less than 50 x 10(6)/L, mean CD4+ (33 +/- 13) x 10(6)/L. Tuberculin tests were negative. (3) TREATMENT: 5 cases were treated with anti-tuberculosis and highly active anti-retrovirus treatment (HAART), the others were treated with anti-tuberculosis only. Six months later, comparing with anti-tuberculosis, CD4+ cells in patients of anti-tuberculosis with HAART increased significantly (P < 0.05, respectively). CONCLUSIONS: The decrease of CD4+ cell might be important in AIDS with tuberculosis. Tuberculin test is not a good way of diagnosing AIDS with tuberculosis. Among AIDS complicated by tuberculosis, hematogenous disseminated tuberculosis and extra-pulmonary tuberculosis are common and usually combined with other various opportunistic infections, clinical manifestations are complex and treatment should be prolonged. This combined treatment can shorten treating time and improve the prognosis of AIDS with tuberculosis.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Down-regulation of reduced folate carrier gene (RFC1) expression after exposure to methotrexate in ZR-75-1 breast cancer cells.

Methotrexate (MTX) is administered in intervals of one week or longer in the treatment of cancer and autoimmune disease. Early studies suggested that daily MTX administration was associated with decreased effectiveness and increased toxicity, leading to schedules of administration that include periodic intervals of rest during chronic MTX therapy. We hypothesized that these observations may be the result of the down-regulation of the reduced folate carrier, the major route of cellular uptake of both MTX and the endogenous folates, after MTX exposure. We exposed folate-depleted ZR-75-1 breast cancer cells to low-dose MTX in the presence of hypoxanthine, adenosine and thymidine. After 72 h, the initial rate of MTX uptake had decreased to 22% of the Day 0 value. Western blot analysis showed down-regulation of RFC1 protein expression, and Northern blot analysis showed a corresponding decrease in RFC1 RNA levels. Using an RT-PCR assay, we found that levels of RNA transcripts containing each of the three RFC1 5' noncoding exons were decreased after exposure to MTX, suggesting that MTX exposure causes transcriptional down-regulation of RFC1. Promoter-reporter construct assays demonstrated decreased activity of RFC1 promoter elements upstream of these exons after MTX exposure. Preexposure of the ZR-75-1 cells to 5-azacytidine, a DNA methylation inhibitor, further decreased MTX uptake rather than reverse the inhibition of RFC1 activity, indicating that RFC1 down-regulation after MTX exposure is not the result of methylation of the RFC1 promoter. In summary, these studies demonstrate that MTX exposure can down-regulate RFC1 expression and activity. These acute, inducible, epigenetic changes in RFC1 expression may ultimately be molded into the more permanent genetic changes that result in the transport-mediated MTX resistance that have been observed in MTX-resistant cell lines.

Antimetabolites, Antineoplastic↗
PubMed2000

An alpha-particle emitting antibody ([213Bi]J591) for radioimmunotherapy of prostate cancer.

A novel alpha-particle emitting monoclonal antibody construct targeting the external domain of prostate-specific membrane antigen (PSMA) was prepared and evaluated in vitro and in vivo. The chelating agent, N-[2-amino-3-(p-isothiocyanatophen-yl)propyl]-trans-cyclohexane-1, 2-diamine-N,N',N',N'',N''-pentaacetic acid, was appended to J591 monoclonal antibody to stably bind the 213Bi radiometal ion. Bismuth-213 is a short-lived (t 1/2 = 46 min) radionuclide that emits high energy alpha-particles with an effective range of 0.07-0.10 mm that are ideally suited to treating single-celled neoplasms and micrometastatic carcinomas. The LNCaP prostate cancer cell line had an estimated 180,000 molecules of PSMA per cell; J591 bound to PSMA with a 3-nM affinity. After binding, the radiolabeled construct-antigen complex was rapidly internalized into the cell, carrying the radiometal inside. [213Bi]J591 was specifically cytotoxic to LNCaP. The LD50 value of [213Bi]J591 was 220 nCi/ml at a specific activity of 6.4 Ci/g. The potency and specificity of [213Bi]J591 directed against LNCaP spheroids, an in vitro model for micrometastatic cancer, also was investigated. [213Bi]J591 effectively stopped growth of LNCaP spheroids relative to an equivalent dose of the irrelevant control [213Bi]HuM195 or unlabeled J591. Cytotoxicity experiments in vivo were carried out in an athymic nude mouse model with an i.m. xenograft of LNCaP cells. [213Bi]J591 was able to significantly improve (P < 0.0031) median tumor-free survival (54 days) in these experiments relative to treatment with irrelevant control [213Bi]HuM195 (33 days), or no treatment (31 days). Prostate-specific antigen (PSA) was also specifically reduced in treated animals. At day 51, mean PSA values were 104 ng/ml +/- 54 ng/ml (n = 4, untreated animals), 66 ng/ml +/- 16 ng/ml (n = 6, animals treated with [213Bi]HuM195), and 28 ng/ml +/- 22 ng/ml (n = 6, animals treated with [213Bi]J591). The reduction of PSA levels in mice treated with [213Bi]J591 relative to mice treated with [213Bi]HuM195 and untreated control animals was significant with P < 0.007 and P < 0.0136, respectively. In conclusion, a novel [213Bi]-radiolabeled J591 has been constructed that selectively delivers alpha-particles to prostate cancer cells for potent and specific killing in vitro and in vivo.

Alpha Particles↗
PubMed2000

General route to 2,4,5-trisubstituted piperidines from enantiopure beta-amino esters. Total synthesis of pseudodistomin B triacetate and pseudodistomin F.

The Michael addition reaction of enantiopure beta-amino esters with methyl acrylate followed by Dieckmann condensation and enol silylation affords the enol ethers 6, which are hydrogenated with catalysis by Raney-Ni at 80 atm and 80 degrees C to provide 2,4, 5-trisubstituted piperidines with high diastereoselectivity. In this case Ni-H attacks the C-C double bond from the direction of the 2-alkyl group to provide the products in which 2,4,5-trisubstrited groups are all cis to each other. While hydrogenation of enol ether 13 without a N-Boc protecting group gives the product 15 in which the 4-hydroxy group and 5-ester moiety are trans to the 2-alkyl group. By using the diastereoselective hydrogenation products 9d and 9e as key intermediates, pseudodistomin B triacetate and pseudodistomin F are synthesized. The key steps for these transformations include Curtius rearrangement and Julia olefination.

Alkaloids↗