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Biomedical subjects

T Tang

Publications and source records attributed to T Tang.

At least 37 records · Page 2Linked to original sources
PubMed2000

[Clinical investigation of effects of bizhongxiao decoction (BZX) on rheumatoid arthritis on active phase].

Ninety-six patients with rheumatoid arthritis(RA) on active phase were divided into BZX-treated group(BZXG) and methotrexate-treated group(MTXG). The results showed that after 1-month treatment, symptoms and signs, such as joint tenderness, arthralgia, arthroncus, of patients in BZXG improved notably(P < 0.01 or P < 0.05), while those of patients in MTXG did not improve, there was significant difference between these two groups(P < 0.01 or P < 0.05). After 3-month treatment, these symptoms and signs improved in both groups(P < 0.01 or P < 0.05), but BZX had a better effect than MTX. ESR, CRP, RF, C3, IgG, IgA and IgM decreased significantly in both groups after treatment(P < 0.01 or P < 0.05), ESR, CRP in BZXG decreased more and faster than those in MTXG. In BZXG the obviously efficient rat was 70%, the total efficacy rate was 94%, while in MTXG was 52% and 87% respectively. It is indicated that BZX can improve symptoms and signs of patients with RA, has better and faster effects on acute phase reaction than MTX; and it has anti-immunologic effects similar to MTX, and has no obvious side effect.

Adolescent↗
PubMed2000

Electrokinetic control of fluid flow in native poly(dimethylsiloxane) capillary electrophoresis devices.

Capillary zone electrophoresis (CZE) devices fabricated in poly(dimethylsiloxane) (PDMS) require continuous voltage control of all intersecting channels in the fluidic network in order to avoid catastrophic leakage at the intersections. This contrasts with the behavior of similar flow channel designs fabricated in glass substrates. When the injection plugs are shaped by voltage control and leakage from side channels is controlled by the application of pushback voltages during separation, fluorescein samples give 64 200 theoretical plates (7000 V separation voltage, E = 1340 V/cm). Native PDMS devices exhibit stable retention times (+/- 8.6% RSD) over a period of five days when filled with water. Contact angles were unchanged (+/- 1.9% RSD) over a period of 16 weeks of dry storage, in contrast to the known behavior of plasma-oxidized PDMS surfaces. Electroosmotic flow (EOF) was observed in the direction of the cathode for the buffer systems studied (phosphate, pH 3-10.5), in the presence or absence of hydrophobic ions such as tetrabutylammonium or dodecyl sulfate. Electroosmotic mobilities of 1.49 x 10(-5) and 5.84 x 10(-4) cm2/Vs were observed on average at pH 3 and 10.5, respectively, the variation strongly suggesting that silica fillers in the polymer dominate the zeta potential of the material. Hydrophobic compounds such as dodecyl sulfate and BODIPY 493/503 adsorbed strongly to the PDMS, indicating the hydrophobicity of the channel walls is clearly problematic for CZE analysis of hydrophobic analytes. A method to stack multiple channel layers in PDMS is also described.

Animals↗
PubMed2000

The relative frequencies of HLA-DRB1*01 alleles in the major US populations.

The frequencies of alleles in the HLA-DRB1*01 family were determined in each of five US populations from a database of 82,979 individuals. Individuals typed as DR1 (or DRB1*01) comprised between 7.6%-21.3% of the individuals in each population group. Fifty-nine DR1 individuals were randomly selected from each group and subjected to high-resolution DNA typing by polymerase chain reaction using sequence-specific oligonucleotide probes. DRB1*0101 was the most common allele in the Caucasian, Asian/Pacific Islander, and Native American groups while the DRB1*0102 allele was found in the majority of African Americans and Hispanics. DRB1*0103 was present at a similar frequency in all populations. DRB1*0104, DRB1*0105, and DRB1*0106 alleles were not observed.

Alleles↗
PubMed2000

[Drug resistance of acute promyelocytic leukemia (APL) to all-trans retinoic acid (ATRA) and its reversion].

OBJECTIVE: To study the mechanism of drug resistance of APL to ATRA and the methods of reversion. METHODS: ATRA-resistant HL60 cell line and bone marrow (BM) leukemia cells from recurrent APL patients who did not respond to ATRA treatment were used in this study. Multiple drug resistance gene (mdr1) expression was determined by RT-PCR and flow cytometry. Cell proliferation and differentiation were assessed by MTT uptake and NBT reduction respectively. RESULTS: The response of ATRA-resistant HL60 and APL cells from recurrent patients to the differentiation inducing activity of ATRA was significantly reduced, and ATRA had little effect on cell proliferation. Expression of mdr-1 was nagative in ATRA-resistant HL60 cells. It was negative in resistant APL cells even after ATRA treatment. Arsenic trioxide and homoharringtonine (HHT) could inhibit proliferation of HL60 and ATRA-resistant HL60 cells, indicating no cross-resistance with ATRA. Interferon alpha (IFN-alpha) and PGE1 could significantly inhibit proliferation of ATRA-resistant HL60 cells and restore cell differentiation induced by ATRA. CONCLUSION: Drug resistance of APL to ATRA is not related to mdr-1. It can be reversed by IFN-alpha. There is no cross-resistance between HHT or arsenic trioxide and ATRA.

Alprostadil↗
PubMed2000

[Epidemiological survey and analysis on bronchial asthma in Guangdong Province].

OBJECTIVE: To survey asthma prevalence and risk factors of asthma in Guangdong and then to provide a basic consideration for research and preventive and therapeutic poliaes for control of asthma. METHODS: Using uniform scheme, procedures and questionnaire, performing stratified-cluster-disproportional-random-sampling survey for the population in six areas: Santou, Shenzhen, Zhanjiang, Shaoguan, Fushan and Guangzhou; quantitative sample the prevalence rate quantitated is 1.5% (P = 0.015, q = 0.985), a sampling number stratified = 178 x 0.985/0.015 = 11,689, if the whole province were stratified into six areas, a total of 70,134 persons were supposed to be investigated, in this survey 71,867 subjects were actually examined; all the original data were inputted into soft discs in the same form of data base structure variable definition table, and then were statistically analyzed with spas 8.0 for windows on P III/450 computer, all the prevalence rates were compared by chi 2 test. RESULTS: In this survey 676 asthmatics were found, the overall prevalence rate was 0.94%, the ratio of male to female was 1.38:1; the rate of adults was 0.99% and that of children was 0.73%, three groups with higher prevalence were children of preschool period (age < 7 years, 1.03%), young period (age 18-25 years, 1.00%) and senile period (age 66-75 years, 2.99%); the rate of city (Fushan, 1.38%) was higher than that of rural area (Zhanjiang, 0.47%); the rate of old district (1.70%) was higher than that of the new district (0.23%) in Guangzhou and the rate of historic city (Fushan, 1.38%) was higher than that of the newly developed city (Shenzhen, 0.64%); risk factors found among 676 asthmatics, persons keeping pets (cat, dog, fowl, bird) in home were reported by 46.0% (311/676), those keeping cat was 43.1% (134/311), particularly those keeping cat and both cat and dog accounted for 61.7% (192/311). Persons often exposed to side-stream smoke were reported by 54.7%. Asthmatics with allergic rhinititis were reported by 38.2%. The attack contributed to change temperature or to inhale cold air was 41.6% respectively. CONCLUSION: This survey had basically reflected the distribution, Frequency and intensity of asthma, the overall prevalence rate was 0.94% from which it would be estimated that there could be 670,000 asthmatics in Guangdong; the relative data will provide basis for research work concerned and mass prevention and treatment of asthma.

Adolescent↗
PubMed2000

[Effects of recombinant human growth hormone on cortical bone of ovariectomized rats].

OBJECTIVE: To study the effects of recombinant human growth hormone on cortical bone of middle femur and vertebra of variectomized rats. METHODS: Forty 6 month-old SD rats received low or high dose of growth hormone subcutaneously 3 months after ovariectomy for 8 weeks. Bone density and biomechanical strength of the femur were measured, and the thickness of cortical bone of the middle femur and L(2) vertebra was observed. The results were compared with those in estrogen group. RESULTS: Growth hormone increased the thickness of cortical bone and biomechanical strength and bone density. Estrogen therapy showed no effects on bone density and biomechanical strength of cortical bone. CONCLUSION: Recombinant human growth hormone can prevent bone loss from cortical bone of ovariectomized rat.

Animals↗
PubMed2000

Maintaining updated DNA-based HLA assignments in the National Marrow Donor Program Bone Marrow Registry.

The National Marrow Donor Program (NMDP) has instituted an approach to address the impact of new alleles on the DNA-based HLA assignments obtained during volunteer donor typing. This approach was applied to the DRB typing results from 371,187 donors received from 14 laboratories in 1999. Samples were tested with a standardized set of sequence specific oligonucleotide reagents and the positive and negative hybridization results transmitted electronically to the NMDP. A software program interpreted the primary data into HLA assignments and rejected assignments which did not produce a result at the specified level of resolution. Comparison of the HLA assignments derived by the NMDP software to the assignments made by the laboratories using several local software prograins showed 90.5% of the assignments to be identical. Differences in assignments were explained by varying levels of typing resolution, variation in the inclusion of the second expressed DRB loci, disparity arising when alternative assignments were summarized, and failure to submit correct information. When the primary data collected in 1999 were interpreted into HLA assignments using the set of alleles defined in July 2000, 74% of the HLA-DRB assignments were altered by the description of new alleles, justifying the development of this software.

Base Sequence↗
PubMed1999

Mitogen-activated protein kinase mediates erythropoietin-induced phosphorylation of the TAL1/SCL transcription factor in murine proerythroblasts.

Ectopic expression of the basic helix-loop-helix transcription factor TAL1 (or SCL) is the most frequent gain-of-function mutation in T-cell acute lymphoblastic leukaemia. Gene-knockout studies in mice have demonstrated that TAL1 is required for embryonic and adult haematopoiesis, and considerable evidence suggests it also has important functions in terminal erythroid differentiation. We reported previously that TAL1 phosphorylation is stimulated by erythropoietin in splenic proerythroblasts isolated from mice infected with the anaemia-inducing strain of Friend virus and show here the signalling pathway responsible. Erythropoietin was found to stimulate nuclear mitogen-activated protein kinase activity in addition to TAL1 protein phosphorylation, both of which were quantitatively inhibited by the mitogen-activated protein kinase kinase inhibitor PD 098059 and the phosphatidylinositol 3-kinase inhibitor wortmannin. Tryptic phosphopeptide analysis of radiolabelled TAL1 immunoprecipitated from nuclear extracts of Friend virus-induced proerythroblasts revealed that phosphorylation of Ser(122), shown previously to be a substrate for the mitogen-activated protein kinase ERK1 (extracellular signal-regulated protein kinase) in vitro, was specifically, although not exclusively, increased by erythropoietin and inhibited by wortmannin and PD 098059. These results are consistent with an erythropoietin-stimulated signalling pathway in which there is direct activation of a mitogen-activated protein kinase kinase by phosphatidylinositol 3-kinase and identify TAL1 as one of its nuclear targets. These data suggest, in addition, a specific mechanism by which the principal regulator of erythroid differentiation could enhance TAL1 function, in addition to increasing its expression.

Androstadienes↗
PubMed1999

Cytokine-activated endothelial cells delay neutrophil apoptosis in vitro and in vivo. A role for granulocyte/macrophage colony-stimulating factor.

The activation of endothelium is important in recruiting neutrophils to sites of inflammation and in modulating their function. We demonstrate that conditioned medium from cultured, activated endothelial cells acts to significantly delay the constitutive apoptosis of neutrophils, resulting in their enhanced survival and increased phagocytic function. The antiapoptotic activity is, in part, attributable to granulocyte/macrophage colony-stimulating factor (GM-CSF) secreted by activated endothelial cells. The in vivo relevance of these findings was investigated in a cytokine-induced model of acute meningitis in mice. Peripheral blood neutrophils (PBNs) from mice with meningitis exhibited a delay in apoptosis compared with untreated mice. Furthermore, neutrophils recovered from the inflamed cerebrospinal fluid (CSF) exhibited enhanced survival compared with neutrophils isolated from the peripheral blood of the same animals. In unchallenged GM-CSF-deficient mice, the apoptosis of circulating PBNs was similar to wild-type animals; however, after cytokine-induced meningitis, the delay in neutrophil apoptosis typically observed in wild-type mice was attenuated. In contrast, the apoptosis of neutrophils recovered from the CSF of mice of both genotypes was comparable. Taken together, these studies suggest that neutrophil apoptosis is regulated during an inflammatory response, in both intravascular and extravascular compartments. GM-CSF released by activated endothelium can act to increase neutrophil survival and function in the peripheral blood, whereas other factor(s) appear to perform this function in the extravascular space.

Animals↗
PubMed1999

Protection of cardiomyocytes by pinacidil during metabolic inhibition and hyperkalemia.

The objective of this study is to understand the mechanism underlying the cardioprotective effects of pinacidil, an ATP-sensitive K+ channel (K(ATP)) opener. We examined the effects of 10 microM pinacidil in cultured chicken cardiomyocytes. Pinacidil caused a concentration-dependent delay in metabolic inhibition-induced increase in intracellular calcium concentration ([Ca2+]i) and creatine phosphokinase release, and this action was antagonized by glyburide, a K(ATP) blocker. Neither verapamil, an L-type Ca2+ channel blocker, nor bepridil, a Na+-Ca2+ exchange inhibitor, affected the time course of increase in [Ca2+]i induced by metabolic inhibition. Pinacidil did not have an effect on the amplitude of K+-induced increase in [Ca2+]i, but accelerated the rate of decline following peak stimulation. In contrast, glyburide reduced the amplitude of K+-induced increase in [Ca2+]i and prolonged the rate of decline. These results provide direct evidence that pinacidil protects cardiomyocytes from metabolic inhibition-induced injury by cyanide (CN) through a delay in the onset of increase in [Ca2+]i, rather than by inhibition of the L-type Ca2+-channels or by alteration of Na+-Ca2+ exchange.

Adenosine Triphosphate↗
PubMed1999

Relative HLA-DRB1*13 allele frequencies and DRB3 associations of unrelated individuals from five US populations.

The frequencies of 30 HLA-DRB1*13 alleles and 15 DRB3 alleles were determined for the 5 major U.S. ethnic populations: Caucasians, African Americans, Asian/Pacific Islanders, Hispanics, and Native Americans. A random sampling (163) of DRB1*13-positive individuals from each self-described ethnic group was selected out of a pool of 82,979 unrelated individuals, providing at least an 80% probability of detecting a rare allele that occurred at 1%. These 815 samples were subjected to allele-level SSOP typing and/or DNA sequencing which identified 11 different DRB1*13 alleles. DRB1*1301 and DRB1*1302 were the most common alleles seen in the five major ethnic groups while DRB1*1304 was not detected among Caucasians and DRB1*1305 was not detected among African Americans. DRB1*13 allele diversity was surprisingly more limited among African Americans compared to both Caucasians and Asian/Pacific Islanders. To determine the extent of DRB1*13-DRB3 associations, 504 of these samples expressing only one DRB3-associated DRB1 allele were subjected to PCR-SSOP typing and 14 DRB1*13-DRB3 haplotypes were detected. The distribution revealed that African Americans were significantly different from Caucasians, Asian/Pacific Islanders, and Hispanics. Allele frequency studies such as this further support previous findings that the distribution of HLA types can differ significantly among different ethnic populations.

Alleles↗
PubMed1999

[Biomechanical evaluation of five fixation techniques for the lower cervical spine].

OBJECTIVE: This study biomechanically investigated the three-dimensional motion stability of five reconstruction methods in the cervical spine, in order to provide the biomechanical basis for the clinical selection of fixation methods. METHODS: With eight adult cervical spine fresh specimens, the three-column injury was produced at C(4 - 5) level. The spinal constructs, reconstructed by various techniques including anterior titanium locking screw plate (TLSP), posterior interspinous wiring (IW), combined fixation with the TLSP and IW (TLSP + IW), Roy-Camille plate (RP), and transpedicular screw plate (TP), were tested under six loading modes-flexion, extension, right/left lateral bending, and right/left axial rotation. RESULTS: The three-dimensional motion stability of either TLSP or IW was less than that of intact cervical spine. The TLSP + IW and RP provided increased stability compared with the intact spine. The stabilizing capabilities of transpedicular screw plate fixation was the best in all loading modes. CONCLUSIONS: In three-column instability of cervical spine injury, exclusive use of the anterior plate or the posterior interspinous wiring was not supported by the results. The stabilizing capabilities provided by combined anterior and posterior instrumentation and posterior plate were good. The three-column fixation for the cervical spine using transpedicular screw plate fixation offers increased stability significantly over that of other conventional cervical fixation systems.

Adult↗
PubMed1998

Effects of Ca2+ channel blockers on Ca2+ loading induced by metabolic inhibition and hyperkalemia in cardiomyocytes.

The effects of the L-type (nifedipine and verapamil) and the T-type (mibefradil) Ca2+ channel blockers on the increase in intracellular Ca2+ concentration ([Ca2+]i) induced by NaCN metabolic inhibition and hyperkalemia were examined in chicken cardiomyocytes using fluorescence imaging with Fura-2. NaCN induced a slow and sustained rise in [Ca2+]i, which was not affected by pretreating the cells for 5 min with nifedipine, verapamil, or mibefradil at 100 nM or 10 microM. Pretreatment of the cells with 10 microM nifedipine, verapamil, or mibefradil for 5 min remarkably inhibited the K+-induced increase in [Ca2+]i. These inhibitory effects diminished after 48-h pretreatment with nifedipine or verapamil but not with mibefradil. Ryanodine also induces an increase in [Ca2+]i, and this effect was enhanced by 48-h pretreatment of the cells with 10 microM verapamil but not with 10 microM mibefradil. We conclude that the NaCN-induced increase in [Ca2+]i is independent of the Ca2+ influx though the L-type or T-type Ca2+ channels. Chronic inhibition of the L-type Ca2+ channels but not T-type channels may enhance the ryanodine receptor-mediated Ca2+ release, which may be responsible for the development of tolerance to their inhibitory effects on K+-induced increase in [Ca2+]i.

Animals↗
PubMed1998

Antibodies affecting ion channel function in acquired neuromyotonia, in seropositive and seronegative myasthenia gravis, and in antibody-mediated arthrogryposis multiplex congenita.

A new autoimmune disease affecting the neuromuscular junction has been defined. Acquired neuromyotonia is associated with antibodies to voltage-gated potassium channels that act, at least in part, by reducing potassium channel function with resulting neuronal hyperactivity. This condition is quite frequently associated with thymoma and, in many cases, antibodies to acetylcholine receptors are present as well as antibodies to VGKC. Improvements in techniques and the availability of cloned DNA and recombinant forms of the AChR subunits have led to new observations concerning the specificity and roles of antibodies in myasthenia gravis. The transfection of a cell line with the epsilon subunit means that we can now accurately compare antibodies reactive with adult and fetal human AChR. This may help to determine the relationship between AChR subunit expression in different tissues and the induction of antibodies that bind specifically to the two forms, as well as to clarify the role of antibodies to fetal or adult AChR in causing ocular muscle symptoms. Serum antibodies from a few mothers with obstetric histories of recurrent arthrogryposis multiplex congenita in their babies specifically inhibit the function of fetal AChR. These observations not only explain the cause of some cases of arthrogryposis multiplex congenita, but also suggest that other fetal-specific antibodies might be responsible for other fetal or neonatal conditions. An animal model has been established to enable us to investigate the role of maternal serum factors in causing such disorders. Seronegative MG has been the subject of many studies from our laboratory over the last ten years. The transience of the effects of SNMG plasmas on AChR function strongly suggests that the plasma antibodies do not bind directly to the AChR, but inhibit function by some indirect mechanism. They do not appear to act via the cAMP-dependent protein kinase pathway, and studies are in progress to investigate the involvement of other second messenger systems.

Adult↗
PubMed1998

Imprinting at the mouse Ins2 locus: evidence for cis- and trans-allelic interactions.

The mouse gene encoding preproinsulin 2 (Ins2) is located on the distal end of chromosome 7 in a region of several hundred kilobases that contains several imprinted genes. The exclusive expression of the Ins2 paternal allele in the visceral yolk sac during the last part of gestation indicates that Ins2 also is imprinted. However, in other tissues in which Ins2 is expressed, both alleles are active at all developmental stages. Taking advantage of two mouse strains carrying different null mutations introduced at the Ins2 locus via homologous recombination in ES cells, we examined whether genes inserted at the Ins2 locus become imprinted and have the same restricted pattern of monoallelic expression. In the first null allele, Ins2 was replaced by LacZ, under the control of the endogenous Ins2 promoter, and a Neo cassette with its own promoter was inserted 3' to LacZ (Zneo allele). In the second null allele, Ins2 and its promoter were replaced by the same Neo cassette (Neo allele). Expression of the maternally and paternally inherited genes was monitored by RT-PCR performed on various reciprocal crosses involving the two mutants and the wildtype alleles. In (Zneo x wildtype) F1 embryos, the pattern of LacZ expression was similar to that of Ins2; i.e., LacZ is expressed in the yolk sac only when paternally inherited, while its expression in the embryo proper is independent of its paternal or maternal origin. For both of the mutant alleles, Neo was transcribed only when paternally inherited, in the yolk sac as well as in the embryo. Unexpectedly, we found that LacZ transcription on the maternal chromosome varied depending on the nature of the allele on the paternal chromosome. While fully expressed in the embryo when the paternal chromosome carries the wildtype allele, the maternally inherited LacZ is extinguished when the paternal allele is the Neo allele. The major conclusion from our results is that individual genes introduced into an imprinted chromosomal domain can become imprinted, indicating the influence of long-range cis-acting effects. In addition, our data suggest that the two parental alleles may "communicate" with each other and influence the transcription at the locus.

Animals↗
PubMed1998

Multisite pacing as a supplemental treatment of congestive heart failure: preliminary results of the Medtronic Inc. InSync Study.

This report describes the initial results of the "InSync" study, a European and Canadian multicenter trial that examines the safety and efficacy of a multisite pacemaker (Medtronic InSync) and of left ventricular pacing leads (Medtronic 2187 and 2188) implanted via a cardiac vein as a supplemental treatment of refractory congestive heart failure. Over a 10-month period, the system was implanted successfully in 68 of the 81 (84%) patients who had been enrolled in the study. The 68 patients were, on average, 66 +/- 10 years old, had a mean left ventricular ejection fraction (LVEF) = 21% +/- 9%, and 63% were in NYHA functional Class III and 37% were in Class IV. No system implant related complication occurred. During follow-up, 7 of 10 patients who exited the study had died, 4 suddenly. There was a clinical benefit among surviving patients, which was corroborated by a significant improvement in NYHA functional class and in the Minnesota Living with Heart Failure Quality of Life Questionnaire Score (MLS) and by a longer distance covered during a 6-minute walk test. This clinical improvement was associated with a significant narrowing of the paced QRS complex during biventricular pacing, a significant decrease in the interventricular mechanical delay, and a trend towards an increase in the duration of ventricular filling. These encouraging preliminary results confirm the feasibility and reliability of this new multisite pacing system in the management of dilated cardiomyopathy and support the continuation of further evaluations of this complementary treatment of refractory congestive heart failure.

Aged↗
PubMed1998

Molecular cloning and characterization of a mouse gene with homology to the Duffy-antigen receptor for chemokines.

The Duffy antigen receptor for chemokines (DARC) is a receptor for both CXC and CC chemokines. We have cloned a mouse gene with a predicted amino acid sequence homology of approximately 63% to human DARC and localized this gene to mouse chromosome 1 between the Xmv41 and D1Mit166 loci. We further demonstrated that, like the human gene, the mouse gene exhibits a single intron of 462 bp which interrupts the open reading frame between the codons for the seventh and eighth amino acid residues. Northern blot analyses revealed that putative mDARC mRNA is highly expressed in adult mouse spleen and skeletal muscle and in whole embryos between embryonic days 8.5 to 12. Northern blot analysis of hemangiosarcomas which develop spontaneously in the spleen of the Eker rat reveal expression of mRNAs which hybridize with both DARC and CXCR2 probes, suggesting a potential role of these receptors in the angiogenesis associated with tumor formation.

Amino Acid Sequence↗