Biomedical subjects

Q Tang

Publications and source records attributed to Q Tang.

At least 55 records · Page 3Linked to original sources

PubMed2000

[The sensitivity to apoptosis is enhanced in U937-ASPI-3K cells which stably express antisense ATM/PI-3K].

OBJECTIVE: To analyse the characteristics of apoptosis sensitivity in U937-ASPI-3K cells which is stably expressing anti-sense ATM/PI-3K. METHOD: Annexin V-PI apoptosis detection kid and flow cytometry were used to determine apoptosis rate, Western blot to the expression level of cytochrome C protein and Bcl-2 protein. RESULTS: U937-ASPI-3K cells had a lowered threshold for triggering apoptosis in response to low dose irradiation. Cell apoptosis rate was 28% and (53.0 +/- 5.4)%, respectively, at 8 and 48 hours after 1.5 Gy (137)Cs irradiation, while in U937-pZEOSV2 (+) control group it was 4.2% and (11.0 +/- 3.3)%, respectively. Cytosolic cytochrome C protein band was gradually intensified in U937-ASPI-3K in 4 - 8 h after irradiation, but was not detected in control group. Bcl-2 protein gradually decreased in U937-ASPI-3K in 4 - 8 h after irradiation, but didn't change obviously in control group. CONCLUSION: Cell line U937-ASPI-3K acquired a phenotype with a lowered threshold for triggering apoptosis. It demonstrated that selective inactivation of ATM gene might be of considerable value in tumor treatment.

Apoptosis↗

PubMed2000

[Effects of YMB injection on hemorheology in rats].

This study was designed to elucidate the mechanism of YMB Injection on anti-CAD therapy. Fufang Danshen Injection was used as positive control and saline was taken as negative control to study the effects of traditional medicine YMB Injection on hemorheological parameters in normal rats and hypostasis rats. The results showed YMB Injection had no effect on hemorheological parameters of normal rats, but it could effectively decrease whole blood viscosity and whole blood reduction viscosity of hypostasis rats. The data implied that YMB Injection could decrease blood viscosity and hence improve blood supply of the graft in anti-CAD therapy.

Animals↗

PubMed2000

[An adenosine triphosphate bioluminescence assay for detecting the number of living cells].

The method for detecting the number of living cells was studied. Using an adenosine triphosphate (ATP) bioluminescence assay, the present authors reported a perfect linear relationship between lg ATP concentrations and lg luminescence counts (r = 0.9963) as well as a relationship between lg number of cells and lg ATP luminescence counts (r = 0.9922). The detectable cells ranged from 10(2) to 10(6) cells/ml, the coefficients of variation 1-3%. This method is simple, accurate and sensitive and has a high reproducibility.

Adenosine Triphosphate↗

PubMed2000

[An evaluation of adenosine triphosphate bioluminescence assay for tumor in vitro chemosensitivity testing].

This study was aimed at the feasibility of using ATP-bioluminescence assay for tumor in vitro chemosensitivity testing. With the use of this assay, the authors determined dose-response curve in mouse fibroma cell line L929 treated with chemotherapeutic agents, and investigated the different in vitro responses of 6 ovarian carcinomas (5 from fresh tumor tissues, 1 from ascites) treated with etopside, cis-plating, 5-fluorouracil and adriamycin. The results showed that the coefficients of variation for triplicate assays ranged from 1.2% to 15.8% which means high reproducibility of the assay. The single cell suspension (including < 30 cells clusters) could be separated from tissue fragments by means of enzyme cocktail (collagenase, Dnase, pronase). The viable cells were over 90%. This study demonstrates that ATP-bioluminescence assay is a sensitive, reliable and efficient method for tumor chemosensitivity testing. In this connection, the correlation between in vitro drug sensitivity and in vivo patient response is worth further studying.

Adenosine Triphosphate↗

PubMed1999

A new mechanism of neurodegeneration: a proinflammatory cytokine inhibits receptor signaling by a survival peptide.

Heightened expression of both a proinflammatory cytokine, tumor necrosis factor alpha (TNF-alpha), and a survival peptide, insulin-like growth factor I (IGF-I), occurs in diverse diseases of the central nervous system, including Alzheimer's disease, multiple sclerosis, the AIDS-dementia complex, and cerebral ischemia. Conventional roles for these two proteins are neuroprotection by IGF-I and neurotoxicity by TNF-alpha. Although the mechanisms of action for IGF-I and TNF-alpha in the central nervous system originally were established as disparate and unrelated, we hypothesized that the signaling pathways of these two cytokines may interact during neurodegeneration. Here we show that concentrations of TNF-alpha as low as 10 pg/ml markedly reduce the capacity of IGF-I to promote survival of primary murine cerebellar granule neurons. TNF-alpha suppresses IGF-I-induced tyrosine phosphorylation of insulin receptor substrate 2 (IRS-2) and inhibits IRS-2-precipitable phosphatidylinositol 3'-kinase activity. These experiments indicate that TNF-alpha promotes IGF-I receptor resistance in neurons and inhibits the ability of the IGF-I receptor to tyrosine-phosphorylate the IRS-2 docking molecule and to subsequently activate the critical downstream enzyme phosphatidylinositol 3'-kinase. This intracellular crosstalk between discrete cytokine receptors reveals a novel pathway that leads to neuronal degeneration whereby a proinflammatory cytokine inhibits receptor signaling by a survival peptide.

Animals↗

PubMed1999

Disrupted retinal development in the embryonic belly spot and tail mutant mouse.

The Belly spot and tail (Bst) semidominant mutation, mapped to mouse Chromosome 16, leads to developmental defects of the eye, skeleton, and coat pigmentation. In the eye, the mutant phenotype is characterized by the presence of retinal colobomas, a paucity of retinal ganglion cells, and axon misrouting. The severity of defects in the Bst/+ retina is variable among individuals and is often asymmetric. In order to determine the role of the Bst locus during retinal morphogenesis, we searched for the earliest observable defects in the developing eye. We examined the retinas of Bst/+ and +/+ littermates from embryonic day 9.5 (E9.5) through E13.5 and measured retinal size, cell density, cell death, mitotic index, and cell birth index. We have found that development of the Bst/+ retina is notably dilatory by as early as E10.5. The affected retinas are smaller than their wildtype counterparts, and optic fissure fusion is delayed. In the mutant, there is a marked lag in the exit of retinal cells from the mitotic cycle, even though there are no observable differences in the rate of cellular proliferation or cell death between the two groups. We hypothesize that Bst regulates retinal cell differentiation and that variability of structural defects in the mutant, such as those affecting optic fissure fusion, is a reflection of the extent of developmental delay brought about by the Bst mutation.

Animals↗

PubMed1999

High-affinity interaction of (des-Tyrosyl)dynorphin A(2-17) with NMDA receptors.

The opioid peptide dynorphin A elicits non-opioid receptor-mediated, neurotoxic response in vivo, which is blocked by pretreatment with MK-801, a noncompetitive N-methyl-D-aspartate receptor (NMDAR) antagonist. In the present study, we examined the possible direct interaction of dynorphin A on the NMDAR. A nonopioid dynorphin A analog, (125)I-(des-tyrosyl) dynorphin A(2-17), was used in radioligand binding analysis on rat cortical brain membranes. This radioligand exhibited a saturable, specific binding at high affinity with a K(d) value of 9.4+/-1.6 nM and maximal binding of 2.4+/-0.6 pmol/mg protein. This binding site was associated with the NMDAR complex because it was modulated by a number of NMDAR ligands. Transient expression of the rat NR1a/NR2A complex in human embryonic kidney 293 cells confirmed a coexpression of (125)I-(des-tyrosyl) dynorphin A(2-17), [(3)H]CGP39,653, and [(3)H]MK-801 binding. These data provide direct evidence of the presence of a high-affinity binding site for dynorphin A on the NMDAR. The modulatory effect of the various NMDAR-selective ligands on dynorphin A binding suggests that dynorphin A may bind preferentially to the closed/desensitized state of the NMDAR. The physiological role of dynorphin A binding to the NMDAR remains to be established.

2-Amino-5-phosphonovalerate↗

PubMed1999

[Relationship between methylation status of gamma-glutamyl transpeptidase (GGT) genes and abnormal expression of its enzyme proteins in tissues of human hepatomas].

OBJECTIVE: To explore the mechanism of expression and alteration of gamma-glutamyl transpeptidase (GGT) genes during the development of human hepatomas. METHODS: The total GGT protein and total RNA were purified in human hepatomas, adjacent paracancerous and distal cancerous tissues. The specific activities of total GGT, membrane-combine GGT and soluble GGT were investigated, the GGT gene of 5'-NC region was amplified by using a nest RT-PCR assay, and methylation status of GGT gene M3 site were analyzed in the present study. RESULTS: An increasing tendency (P < 0.05) of total RNA concentrations was found from cancer in distal cancerous tissues; the specific activities (U/g) of total GGT, membrane-combine GGT and soluble GGT were significantly higher (P < 0.05) in hepatomas than those in adjacent paracancerous or and that distal cancerous tissues; and the frequencies of amplified fragment and hypomethylated M3 site of GGT 5'-NC region genes were 100% and 75% in hepatomas, 85% and 55% in adjacent cancerous, and 75% and 50% in distal cancerous tissues, respectively. CONCLUSIONS: The present data suggest that the abnormal expression of GGT proteins in hepatomas was related to hypomethylation status of GGT genes, and that the fragment analysis of the GGT genes might be a sensitive assay to monitor the hepatic cell canceration.

Carcinoma, Hepatocellular↗

PubMed1999

[Component in diphtheria-pertussis-tetanus-hepatitis B vaccine].

OBJECTIVE: To study immunogenecity of yeast-derived recombinant hepatitis B (YHB) component in diphtheria-pertussis-tetanus-YHB vaccine (DPTw-YHB). METHODS: Immunogenecity of tetra-valent DTPw-YHB vaccine and mono-valent recombinant YHB vaccine, and that of the tetra-valent vaccine with varied YHB component were compared. The efficiency and stability of recombinant YHB in the tetra-valent vaccine stored at 2 - 8 degrees C for 18 months were determined. RESULTS: The efficiency of recombinant YHB in the tetra-valent vaccine enhanced significantly in mice, as compared with that of mono-valent recombinant YHB vaccine, with an average mouse ED(50) of 1:2.0 - 1:3.1. There was no significant difference in efficiency of the tetra-valent vaccine with varied recombinant YHB component. Recombinant YHBin the DPTw-YHB tetra-valent vaccine still kept good stability stored at 2 - 8 degrees C for 18 months. CONCLUSION: Recombinant YHB in the tetra-valent vaccine was more immunogenic than the mono-valent YHB vaccine. No interference and inhibition of DPTw to recombinant YHB was found, indicating good compatibility between DPTw and YHB.

Animals↗

PubMed1999

[Determination of triptolide in tripterygium preparations by gradient high performance liquid chromatography].

A gradient elution method was developed for the separation and determination of triptolide in Tripterygium wilfordii Hook preparations by high performance liquid chromatography (HPLC) using YWG column made in China. Methanol with 0.05 mol/L KH2PO4 was used as mobile phase, and the photodiode array detector was used at lambda = 218 nm. The sample of tripterygium oral preparation was extracted with ethanol and then by chloroform. The extract solution was evaporated and the residue was dissolved in 10 mL of ethanol as a sample solution. The spectrum was obtained by the subtraction of spectrum of ethanol from that of sample solution. In comparing with isocratic elution, the gradient operation used in this paper had higher resolution and sensitivity. The calibration curve was linear over the range of 1.32-21.10 mg/L (r = 0.9999). The average recovery of the method was 97.59%. The method was applied to separate and determine the triptolide in tripterygium tablets and the results indicated that the triptolide content by this method was less than that by isocratic and label-claimed one.

Chromatography, High Pressure Liquid↗

PubMed1998

Prevention by inhibitors of arachidonic acid cascade of liver carcinogenesis, cirrhosis and oxidative DNA damage caused by a choline-deficient, L-amino acid-defined diet in rats.

Effects of inhibitors of arachidonic acid (AA) cascade on the development of fatty liver, cirrhosis, glutathione S-transferase placental form (GST-P)-positive preneoplastic nodules, neoplastic nodules and generation of 8-hydroxydeoxyguanosine (8-OHdG), caused by a choline-deficient, L-amino acid-defined (CDAA) diet, were examined in Fischer 344 male rats by feeding CDAA diet supplemented with the inhibitors for 12 and 30 weeks. None of the inhibitors affected fatty liver. Among cyclooxygenase (COX) inhibitors, an irreversibly acting acetylsalicylic acid and a long-acting piroxicam, and to a much lesser extent the short-acting ibuprofen but not indomethacin, inhibited the development of cirrhosis, GST-P-positive and neoplastic nodules and generation of 8-OHdG. A phospholipase A2 inhibitor p-bromophenacylbromide (BPB) also exerted similar but lesser extent of inhibitory effects. Lipoxygenase inhibitors quercetin and nordihydroguiaretic acid inhibited GST-P-positive nodules but not cirrhosis or 8-OHdG. Present results suggest that perturbed AA cascade, particularly augmented COX pathway, might play key roles in the causation of liver lesions in the CDAA diet model.

8-Hydroxy-2'-Deoxyguanosine↗

PubMed1998

Partial TCR signals delivered by FcR-nonbinding anti-CD3 monoclonal antibodies differentially regulate individual Th subsets.

Anti-CD3 mAbs with low FcR affinity prolong graft survival in the absence of the cytokine-mediated toxicity observed with conventional anti-CD3 treatment. Previous studies have shown that FcR-nonbinding anti-CD3 mAbs suppress immune responses, at least in part, by delivering a partial signal resulting in Th1 unresponsiveness. In this study, the biochemical and functional consequences of FcR-nonbinding anti-CD3 treatment for various activated T cell populations were examined. In contrast to Th1 cells, FcR-nonbinding anti-CD3-treated Th2 cells secreted IL-4 and proliferated. Furthermore, Th2 cells cultured with the mAb were not rendered unresponsive. Mixed "Th0" populations responded to FcR-nonbinding anti-CD3 by producing IL-4, and showed a selective decrease in IL-2 production following preculture with the mAb. The stimulation of IL-4-producing cells did not reflect a more complete TCR signal, since similar defects in zeta, ZAP-70, and MAP kinase phosphorylation were observed in Th1 and Th2 cells. Despite the proximal signaling defects, FcR-nonbinding anti-CD3 induced nuclear translocation of NF-ATc. Thus, Abs that deliver partial TCR signals may promote development of a Th2 phenotype during the course of an immune response via selective effects on different Th subsets.

Animals↗

PubMed1998

Disruption of the heme iron-proximal histidine bond requires unfolding of deoxymyoglobin.

The unfolding behavior of 10 different distal heme pocket mutants of sperm whale deoxymyoglobin (deoxyMb) has been investigated. The effects of distal histidine (His 64) replacement were the primary focus; however, mutations at Leu 29, Val 68, and Ile 107 were also examined. Formation of the spectroscopically distinguishable heme intermediate (I') of deoxyMb was tracked as a function of pH and guanidinium chloride (GdmCl) concentration. The appearance of this intermediate signals cleavage of the iron-proximal histidine (His 93) bond. The key observations are as follows. (1) None of the distal heme pocket mutations investigated alter the nature of the heme intermediates that are formed under low pH unfolding conditions. (2) Unfolding of deoxyMb at high concentrations of GdmCl proceeds through the same heme intermediates that occur under low pH conditions. (3) The rate of the iron-histidine bond cleavage in an acidic medium is dramatically slowed when large hydrophobic residues (Leu and Phe) replace the distal histidine, whereas there is little correlation between the polarity of the residue at position 64 and the rate of denaturation by GdmCl. (4) However, apolar residues at position 64 enhance significantly the equilibrium resistance of deoxyMb to iron-histidine bond cleavage under both low pH and high GdmCl unfolding conditions. There is a direct correlation between the equilibrium pH and GdmCl values for maximum intermediate formation and the stabilities of the corresponding apoproteins. Collectively, these observations suggest that substantial unfolding of deoxyMb is required for Fe(II)-His 93 bond cleavage. Unlike the situation for aquometMb, heme loss from deoxyMb is not driven by protonation of the proximal histidine ligand. Instead, the process is mediated by more global unfolding of the protein that leads to solvation of the prosthetic group.

Acids↗

PubMed1998

[Immunologic and clinical study of paraneoplastic limbic encephalitis].

OBJECTIVE: To probe into the pathogenic mechanisms of paraneoplastic limbic encephalitis (PLE) in patients with small cell lung carcinoma (SCLC). METHODS: The indirect immunoperoxidase method and Western blot analysis were used for detecting anti-Hu antibodies in 16 PLE patients associated with SCLC. Autopsy and pathological study were performed on two cases. RESULTS: Eight patients (50%) had anti-Hu antibodies (anti-Hu+) whereas eight patients (50%) no detectable antineuronal antibodies (anti-Hu-). The clinical and laboratory features of PLE and time to diagnosis of SCLC were similar in the anti-Hu+ and anti-Hu- groups. Involvement of other areas of the nervous system in seven (87.5%) patients of the anti-Hu+ group but in only one (12.5)% of the anti-Hu- group (P = 0.012). CONCLUSIONS: The presence of this characteristic neurological disorder strongly suggested that with an accompanying SCLC, existence of anti-Hu autoantibody was in favour of an autoimmune mechanism participating in PLE.

Antibodies, Antinuclear↗

PubMed1998

[Determination of chemical constituents of the volatile oil from Curcuma longa by gas chromatography-mass spectrometry].

The study of chemical constituents of the volatile oil from Curcuma longa is reported. The volatile oil was extracted by steam distillation. Fifteen components in the oil were separated and identified by gas chromatography-mass spectrometry(GC/MS). The results were elucidated based on the NBS standard mass spectral data. The total ion current chromatogram showed their mass fraction by normalization method. alpha-curcumene, alpha-zingiberene, 1,8-cineole and zerumbone, which had been reported before were found in Curcuma longa volatile oil, but 1-(3-cyclopentylpropyl)-2,4-dimethylbenzene, beta-sesquiphellandrene, germacrene etc identified simultaneously in the oil had never been reported. The major chemical constituent of the volatile oil from Curcuma longa is alpha-curcumene.

Curcuma↗

PubMed1997

Effects of electroosmotic flow on zone mobilization in capillary isoelectric focusing.

The electroosmotic mobilization of focused protein zones in a fused-silica capillary is investigated using a mixture of model proteins, including alpha-chymotrypsinogen A (bovine pancreas), myoglobin (horse heart) and carbonic anhydrase II (bovine erythrocytes). The presence of carrier ampholytes in the entire capillary and the adsorption of carrier ampholytes onto the capillary wall almost eliminate the electroosmotic flow in the fused-silica capillary, obviating the need for polymer additives such as methylcellulose and hydroxypropylmethylcellulose. In fact, the electroosmotic displacement of focused protein zones can only be achieved by injecting a mixture of proteins and ampholytes as a plug at the inlet of a capillary that has been pre-filled with the catholyte. Various approaches for protein mobilization in the uncoated capillary completely filled with carrier ampholytes are studied. The addition of methylcellulose to the sample mixture of carrier ampholytes and protein analytes serves as an anticonvective medium during the gravity mobilization step and contributes to the reduction of protein adsorption onto the capillary wall.

Animals↗

PubMed1997

T cell receptor-gamma/delta cells protect mice from herpes simplex virus type 1-induced lethal encephalitis.

Increased numbers of T cell receptor (TCR)-gamma/delta cells have been observed in animal models of influenza and sendai virus infections, as well as in patients infected with human immunodeficiency virus and herpes simplex virus type 1 (HSV-1). However, a direct role for TCR-gamma/delta cells in protective immunity for pathogenic viral infection has not been demonstrated. To define the role of TCR-gamma/delta cells in anti-HSV-1 immunity, TCR-alpha-/- mice treated with anti- TCR-gamma/delta monoclonal antibodies or TCR-gamma/delta x TCR-alpha/beta double-deficient mice were infected with HSV-1 by footpad or ocular routes of infection. In both models of HSV-1 infection, TCR-gamma/delta cells limited severe HSV-1-induced epithelial lesions and greatly reduced mortality by preventing the development of lethal viral encephalitis. The observed protection resulted from TCR-gamma/delta cell-mediated arrest of both viral replication and neurovirulence. The demonstration that TCR-gamma/delta cells play an important protective role in murine HSV-1 infections supports their potential contribution to the immune responses in human HSV-1 infection. Thus, this study demonstrates that TCR-gamma/delta cells may play an important regulatory role in human HSV-1 infections.

Animals↗

PubMed1997

Spontaneous occurrence of early region 1A reiteration mutants of type 5 adenovirus in persistently infected human T-lymphocytes.

Mutants of type 5 adenovirus (Ad5) with reiterated DNA sequences in the E1a region appeared in a human T-lymphocyte cell line, Molt-4, persistently infected with H5sub304, a deletion/substitution mutant that has a wild-type phenotype in viral replication. Endonuclease analyses and DNA sequencing revealed DNA reiteration in each mutant. In the four representative mutants investigated, the DNA reiterations all started within a six-base-pair consensus sequence, G(or C)CTGTG, located in the second exon of the E1a region (at nt 1333, 1367, or 1419). There was not any DNA homology between the breakpoints in the second exon and the inserting sequences (starting at nt 532, 710, or 792). Northern analyses suggested that the reiterated splicing sites of the representative mutants were all used in RNA splicing, and the closest donor and recipient joints were used most frequently. These observations imply that during persistent infection Ad5 underwent spontaneous mutations by sequence-specific breakage and nonhomologous end-end joining recombination events. These E1a reiteration mutants could be propagated in HeLa, A549, and KB cells; they were genetically stable; and they killed CREF cells at a strikingly high frequency. Preliminary observations tend to correlate this CREF cell killing with the accumulation of the early viral proteins and/or viral DNA in the infected cells. This degree of cell damage was not observed in Ad5wt or H5sub304 infection of CREF cells. The observed E1a reiterations provide a model to gain insight into understanding the evolutionary events of some, if not all, adenovirus types during many years of symbiotic, persistent relationship in human tonsils and adenoids and possibly other lymphoid organs.

Adenovirus E1A Proteins↗