Search PubMed⌕ Search

Biomedical subjects

D H Zhang

Publications and source records attributed to D H Zhang.

At least 37 records · Page 2Linked to original sources
PubMed1998

Corpuscles of Stannius and stanniocalcin-like immunoreactivity in the white sucker (Catostomus commersoni): evidence for a new cell-type.

The distribution of stanniocalcin immunoreactivity was examined in the corpuscles of Stannius of the white sucker (Catostomus commersoni) by using a chum salmon stanniocalcin antiserum, Western blotting, and light and electron microscopy. The white sucker possesses at least two stanniocalcin-immunoreactive corpuscles in the most posterior portions of the kidneys. Immunocytochemistry and ultrastructure revealed two cell-types in the corpuscle parenchyma, only one of which was immunoreactive. The nonimmunoreactive cells contained dense-cored vesicles and long processes that extended between the immunoreactive cells and terminated at perivascular spaces. When corpuscle extracts were subjected to electrophoresis and Western blotting, three nonreduced stanniocalcin-like immunoreactive bands (approximately 56, 61, and 64 kDa) were observed. However, in the presence of a reductant, a diffuse band migrating in the range of 28 to 32 kDa was noted. The results of this study on the white sucker demonstrate the presence of a dimeric stanniocalcin-like molecule and present evidence of a previously uncharacterized cell-type in the corpuscles of Stannius.

Animals↗
PubMed1997

Transcription factor GATA-3 is differentially expressed in murine Th1 and Th2 cells and controls Th2-specific expression of the interleukin-5 gene.

Interleukin-5 (IL-5), which is produced by CD4(+) T helper 2 (Th2) cells, but not by Th1 cells, plays a key role in the development of eosinophilia in asthma. Despite increasing evidence that the outcome of many diseases is determined by the ratio of the two subsets of CD4(+) T helper cells, Th1 and Th2, the molecular basis for Th1- and Th2-specific gene expression remains to be elucidated. We previously established a critical role for the transcription factor GATA-3 in IL-5 promoter activation in EL-4 cells, which express both Th1- and Th2-type cytokines. Our studies reported here demonstrate that GATA-3 is critical for expression of the IL-5 gene in bona fide Th2 cells. Whereas mutations in the GATA-3 site abolished antigen- or cAMP-stimulated IL-5 promoter activation in Th2 cells, ectopic expression of GATA-3 in Th1 cells or in a non-lymphoid, non-IL-5-producing cell line activated the IL-5 promoter. During the differentiation of naive CD4(+) T cells isolated from T cell receptor transgenic mice, GATA-3 gene expression was up-regulated in developing Th2 cells, but was down-regulated in Th1 cells, and antigen- or cAMP-activated Th2 cells (but not Th1 cells) expressed the GATA-3 protein. Thus, GATA-3 may play an important role in the balance between Th1 and Th2 subsets in immune responses. Inhibition of GATA-3 activity has therapeutic potential in the treatment of asthma and other hypereosinophilic diseases.

Animals↗
PubMed1997

Selective up-regulation of cytokine-induced RANTES gene expression in lung epithelial cells by overexpression of IkappaBR.

We previously reported the cloning of a cDNA for IkappaBR (for IkappaB-related) from human lung alveolar epithelial cells. IkappaBR is related to the IkappaB proteins that function as regulators of the NF-kappaB family of transcription factors. Here, we investigated the consequence of IkappaBR overexpression on the expression of NF-kappaB-regulated chemokine genes in lung alveolar epithelial cells. Chemokines play an important role in many inflammatory diseases such as asthma and AIDS. Overexpression of IkappaBR in the lung cells resulted in a rapid 50-100-fold greater production of the RANTES (regulated upon activation, normal T expressed and presumably secreted) protein upon cytokine-induction compared with control cells. IkappaBR overexpression, however, did not enhance interleukin-8 or MIP-1alpha gene expression, despite the fact that the expression of all three chemokine genes are regulated by NF-kappaB. The up-regulation of RANTES gene expression resulting from overexpression of IkappaBR correlated with increased amounts of a unique RANTES-kappaB binding activity and decreased binding of p50 homodimers. Previous studies have shown that p50 homodimers function as repressors of certain kappaB sites. Our studies suggest that IkappaBR can aid activation of select NF-kappaB-regulated genes by sequestering p50 homodimers.

Base Sequence↗
PubMed1997

Repression of interleukin-6 gene expression by 17 beta-estradiol: inhibition of the DNA-binding activity of the transcription factors NF-IL6 and NF-kappa B by the estrogen receptor.

The cytokine interleukin-6 (IL-6), a key mediator of immune and acute phase responses of the liver, has also been implicated in uterine functions. Estrogens are potent repressors of IL-6 production by uterine stromal cells. In the endometrial adenocarcinoma cell line Ishikawa, phorbol ester-induced activation of the IL-6 promoter was inhibited to basal levels by 17 beta-estradiol (E2) in a wild-type receptor-dependent fashion. Although tamoxifen has been shown to have estrogenic effects on the endometrium, it did not inhibit induction of the IL-6 promoter. We previously showed that inhibition of IL-6 gene expression by E2 does not involve high-affinity binding of the estrogen receptor (ER) to IL-6 DNA. We now report that the ER can directly interact with the transcription factors NF-IL6 and NF-kappa B and can inhibit their ability to bind DNA which might be the molecular basis for repression of IL-6 gene expression by estrogens.

Adenocarcinoma↗
PubMed1997

[Study on the incidence of thyroid disease in Dun Hua District of Chang Bai mountain area, Jilin Province].

Dun Hua is a district where endemic goiter has been prevalent. Residents commenced to eat iodined salt ten years ago. We studied 469 people in this district and discovered that the incidence of endemic goiter had somehow come down but still kept 10.4%. However, the incidence of thyroid cancer went up to 1.9% with the incidence of thyroiditis 0.85%. Pathological characteristic of endemic goiter frequently appeared adenoniatoid feature with some atypical hyperplasia follicles which facilitates the cancerization in the fibrigenic part. Reasons accounted for the endemic goiter occurrance might not only relate to the insufficient intake of iodined salt but also to the increase of iodine excretion from the body. The increase of iodine excretion may be related to the factors as varieties of subsidiary food and vegetables as well as personal habitualness on food and drinks.

Adolescent↗
PubMed1995

Activation of the interleukin-5 promoter by cAMP in murine EL-4 cells requires the GATA-3 and CLE0 elements.

Interleukin-5 (IL-5) plays a central role in the growth and differentiation of eosinophils and contributes to several disease states including asthma. Accumulating evidence suggests a role for cAMP as an immunomodulator; agents that increase intracellular cAMP levels have been shown to inhibit production of cytokines predominantly produced by T helper (Th) 1 cells such as IL-2 and interferon gamma (IFN-gamma). In contrast, the production of IL-5, predominantly produced by Th2 cells, is actually enhanced by these agents. In this report, we have performed transient transfection experiments with IL-5 promoter-reporter gene constructs, DNase I footprinting assays, and electrophoretic mobility shift assays to investigate the key regulatory regions necessary for activation of the IL-5 promoter by dibutyryl cAMP and phorbol esters in the mouse thymoma line EL-4. Taken together, our data demonstrate the critical importance of two sequences within the IL-5 5'-flanking region for activation by these agents in EL-4 cells: one, a highly conserved 15-base pair element present in genes expressed by Th2 cells, called the conserved lymphokine element 0 (CLE0; located between -53 and -39 in the IL-5 promoter), and the other, two overlapping binding sites for the transcription factor GATA-3 (but not GATA-4) between -70 and -59. Taken together, our data suggest that activation via the unique sequence combination GATA/CLE0 results in selective expression of the IL-5 gene in response to elevated levels of intracellular cAMP.

Animals↗
PubMed1995

Cloning of a differentially expressed I kappa B-related protein.

We have cloned a cDNA corresponding to a novel gene from a human epithelial cell line by subtractive hybridization and polymerase chain reaction techniques. This gene is expressed at the message level and at the protein level in a lung alveolar type II-like epithelial cell line but not in lung fibroblasts. In adult human tissues, the mRNA for this gene was detected only in the heart and the skeletal muscle, but not in the brain, placenta, whole lung, liver, or kidney. We have named this gene I kappa BR (for I kappa B-related) since its 52-kDa protein product has significant homology to the I kappa B family of proteins which function as inhibitory cytoplasmic retention proteins for the vertebrate rel/NF-kappa B transcription factors. Although the important role of NF-kappa B in gene activation in cells of the immune system is now well established, a similar role in other cell types or in vertebrate development is less clear. The deduced amino acid sequence of I kappa BR has the most significant homology to the Drosophila protein Cactus which inhibits the function of the NF-kappa B-like protein Dorsal. In electrophoretic mobility shift experiments, I kappa BR inhibited the ability of the p50:p65 NF-kappa B heterodimer to bind DNA. The DNA binding ability of the p50 homodimer but not the p65 homodimer was drastically inhibited by I kappa BR. In transfection experiments, overexpression of I kappa BR significantly inhibited NF-kappa B-dependent transcription from the Ig kappa enhancer. This new member of the I kappa B family of proteins, I kappa BR, may play an important role in regulation of NF-kappa B function in epithelial cells.

Amino Acid Sequence↗
PubMed1995

Localization and biodistribution of conjugate ATG-Dex-DNR in nude mice as models for human leukemia.

131I-labelled anti-thymoglobuline (ATG), 131I-labelled immunoconjugate ATG-Dex-DNR and 131I-labelled Ts-MoAb as control antibody, respectively, were injected by intraperitoneal (i.p.) administration into nude mice used as models for human T-cell leukemia. SPECT imaging was performed from day 1 to day 8 following i.p. injection. The results showed that radioimmunoimaging of human tumor xenografts was clearest day 3 after injection in both of ATG and ATG-Dex-DNR groups, whereas it's not the case in Ts-MoAb group. Nude mice were killed 8th day after injection with antibody or conjugate. The tumor, as well as different dissected normal organs including heart, liver, lungs, kidney, femur and intestine, were harvested, weighed precisely, and radioiodine-counted. T/NT ratios in experimental group was greater than 1.0 (ranged from 1.246-7.865), and in control group they were less than 1.0 (ranged from 0.263-0.757, except for tumor/femur ratio). Our results indicated that ATG and ATG-Dex-DNR had specific affinity to cell line of T-cell leukemia CEM.

Animals↗
PubMed1993

[Pleural mesothelioma: a clinicopathologic study of 42 cases].

Forty two cases of pleural mesothelioma were reported. Macroscopic findings showed that 10 were localized and 32 diffuse. Histological diagnosis revealed 4 benign fibrous tumors and 38 malignant mesothelioma (epithelial type in 25, sarcomatous in 6, and mixed in 7). The main clinical manifestations of malignant mesothelioma were chest pain and dyspnea. The most frequent chest radiographic signs were nodular pleural thickening, irregular thickening of interlobar fissures, a dominant mass and pleural effusion. This disease was usually misdiagnosed as tuberculous pleurisy, lung cancer and metastatic pleural tumors. X-ray examination and CT scan were helpful in the diagnosis of the disease. Thoracoscopy is currently a suitable diagnostic method for pleural mesothelioma. Surgical management and chemotherapy were carried out in 31 cases. 3-year survival rate in 38 patients with malignant mesothelioma was 8.8%. Resection was considered as the treatment of choice for localized mesothelioma. Thoracoscopic talc poudrage followed by chemotherapy was used for on diffuse malignant mesothelioma with pleural effusion to improve survival and prevent recurrent effusion. The histologic type, stage and treatment were identified as significant prognostic factors.

Adolescent↗
PubMed1993

[Thoracoscopy in pleural mesothelioma].

19 patients suspected pleural mesothelioma were performed thoracoscopy. The overall diagnostic rate was 94.7% (18/19 cases). The macroscopic findings of 18 cases presented solitary, well circumscribed, smooth, rounded masses in 2 localized cases and multiple, clear, yellowish-white and "grape-like" granulations or malignant pleural thickening in 16 diffuse cases. Biopsy was taken in 18 cases under direct vision. The histological diagnosis showed 2 benign fibromatous mesothelioma and 16 malignant mesothelioma. Pleural mesothelioma was easily misdiagnosed as primary lung cancer, tuberculous pleurisy and metastatic pleural tumor. The diagnostic accuracy by cytological study of pleural effusions and needle biopsy of pleura both were low. Thoracoscopy is currently a suitable diagnostic method for pleural mesothelioma. The resection was considered as a proper treatment of choice for localized pleural mesothelioma. We recommend that thoracoscopic talc poudrage followed by chemotherapy on diffuse malignant mesothelioma with pleural effusion could be used to improve the survival rate and to prevent the recurrent effusion.

Adult↗
PubMed1992

Growth hormone secretory status in patients with Turner syndrome.

The growth hormone (GH) secretory capacities in patients with Turner syndrome aged 5.1-15.9 years and those with constitutional short stature (CSS) aged 5.2-14.2 years were evaluated by pharmacological and physiological means. The GH response to hypoglycemia in the patients with Turner syndrome was lower than that in the patients with CSS. However, the GH response to arginine was not significantly different between the two patient groups. For the physiological test, the integrated concentration of GH (ICGH), the number of episodic peaks and their mean height were evaluated using blood obtained from the patients every 20 minutes for a period of 24 hours. The ICGH and the mean height of the episodic peaks in the patients with Turner syndrome were significantly lower than those in the CSS patients during the night but not during the day. Negative correlation between the bone age and the night-time values of ICGH was observed in the patients with Turner syndrome. Such correlation was not observed in the CSS patients. The patients with CSS showed a significant day-night difference in the ICGH and the mean height of the episodic peaks, but the patients with Turner syndrome did not show any significant day-night difference in either the ICGH or the mean height of episodic peaks. In conclusion, the GH secretory capacity in patients with Turner syndrome is lower than that in CSS patients.

Adolescent↗
PubMed1992

[The use of thoracoscopy in the diagnosis and treatment of chest diseases].

The procedure and results of thoracoscopy by using a fiberoptic bronchoscope and rigid cold-light thoracoscope in 76 cases with chest diseases of unknown causes were reported. The positive diagnostic rate was 89.5% (68/76). The histologic diagnosis following thoracoscopic biopsy in 65 patients was compared with the findings at follow-up, the results showed the sensitivity being 87.7%, specificity 100% and diagnostic accuracy 89.2%. 3 cases with persistent or recurrent spontaneous pneumothorax were cured by Nd-YAG laser transendoscopically. 5 patients with malignant pleural effusion were treated with intrapleural talcum powder under thoracoscopic control, 4 of them obtained complete pleurodesis. There were only minor complications: transient fever in 40 cases and local subcutaneous emphysema in 7. It was concluded that thoracoscopy is simple, safe, reliable and practical in the diagnosis and treatment of chest diseases. It should be popularized clinically.

Adolescent↗
PubMed1992

Functional compartments in the portal system. An experimental study.

The pressure of the portal trunk, the left gastric vein, the left and right gastroepiploic veins, the mesenteric vein and the abdominal aorta was measured experimentally at the same time in 10 normal dogs. The levels of the raised pressure in the different compartments with their outflow tracts obstructed respectively were observed and the potentials of the functional barriers between these compartments were quantitatively evaluated. The findings showed that the average power of the functional barriers was 45.1 +/- 5.7% between the different compartments in the gastrosplenic area and 74.3% in the mesenteric region. The weakness of the functional barriers' capacity limiting the collateral diversion between the lesser and greater splanchnic systems may be one of the causes making the distal splenorenal shunt lose its selectivity.

Animals↗
PubMed1992

[Bronchial carcinoid. A clinical, roentgenological and pathological study of 17 cases].

17 cases with bronchial carcinoid were reported. 16 cases of them were proved pathologically after pulmonary resection, and the remaining one was confirmed histopathologically through bronchoscopic biopsy. 64.7% was under 40 years of age. The main clinical manifestations were cough, hemoptysis, fever and repeated pneumonitis. In one patient, the carcinoid was associated with Cushing's syndrome. Chest roentgenograms showed lesions centrally located in 12 cases, and peripherally located in 5 cases. Histological examination revealed 15 typical and 2 atypical carcinoid tumors. This disease was usually misdiagnosed as lung cancer, tuberculoma and benign tumors. Chest X-ray examination and fiberoptic bronchoscopic biopsy are helpful to the diagnosis of the disease. Pulmonary resection was performed in 16 cases. Two patients had hilar lymph node metastases, one of them had also involvement of pericardium. There was no operative mortality. In the follow-up study, the disease-free actuarial survival following pulmonary resection was 92.9% at 5 years. 2 patients died. One died of respiratory failure 4 months after pneumonectomy, the other died of pericardium involvement of carcinoid 8 months after operation. Resection is the only effective treatment for bronchial carcinoid.

Adolescent↗
PubMed1990

Preparation of AHTG-DNR conjugates and their antitumor effect in vitro.

100%, 75%, 50%, 25% and 12.5% oxidized dextran T10 (Dex T10) were used as intermediate carriers for conjugating drug daunorubicin (DNR) and antibody anti-human thymocytic globulin (AHTG), to form different immunoconjugates, AHTG:Dex:DNR. It was demonstrated that the conjugate with 25% oxidized Dex T10 as intermediate carrier linked more DNR molecules than the others. The degree of its substitution was 10-11 moles of DNR per mole of AHTG. Moreover, because the amount to reducing agent sodium borohydride (NaBH4), required for the reduction reaction, was relatively small, its damaging effect on AHTG and DNR was lessened accordingly. The antitumor effect of AHTG:Dex:DNR in vitro was tested by using 24-h cytotoxicity assay, with CEM as target cell. Cytotoxic effect of the conjugate was proven and the LD50 was 10.68 micrograms/ml. However, it showed only slight cytotoxic effect on non-target cell K562. When 10 min cytotoxicity assay was performed to show the specific tumor-killing effect of the conjugate, it revealed an obvious cytotoxic activity toward CEM, with the LD50 being 14.79 micrograms/ml, but hardly toward K562. These results suggest that AHTG:Dex:DNR possesses specific cytotoxic effect.

Antilymphocyte Serum↗
PubMed1990

Regulation of anaphase chromosome motion in Tradescantia stamen hair cells by calcium and related signaling agents.

Several lines of evidence support the idea that increases in the intracellular free calcium concentration [( Ca2+]i) regulate chromosome motion. To directly test this we have iontophoretically injected Ca2+ or related signaling agents into Tradescantia stamen hair cells during anaphase and measured their effect on chromosome motion and on the Ca2+ levels. Ca2+ at (+)1 nA for 10 s (approximately 1 microM) causes a transient (20 s) twofold increase in the rate of chromosome motion, while at higher levels it slows or completely stops motion. Ca2+ buffers, EGTA, and 5,5'-dibromo-1,2- bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, which transiently suppress the ion level, also momentarily stop motion. Injection of K+, Cl-, or Mg2+, as controls, have no effect on motion. The injection of GTP gamma S, and to a lesser extent GTP, enhances motion similarly to a low level of Ca2+. However, inositol 1,4,5-trisphosphate, ATP gamma S, ATP, and GDP beta S have no effect. Measurement of the [Ca2+]i with indo-1 reveals that the direct injections of Ca2+ produce the expected increases. GTP gamma S, on the other hand, causes only a small [Ca2+]i rise, which by itself is insufficient to increase the rate of chromosome motion. Further studies reveal that any negative ion injection, presumably through hyperpolarization of the membrane potential, generates a similar small pulse of Ca2+, yet these agents have no effect on motion. Two major conclusions from these studies are as follows. (a) Increased [Ca2+]i can enhance the rate of motion, if administered in a narrow physiological window around 1 microM; concentrations above 1 microM or below the physiological resting level will slow or stop chromosomes. (b) GTP gamma S enhances motion by a mechanism that does not cause a sustained uniform rise of [Ca2+]i in the spindle; this effect may be mediated through very localized [Ca2+]i changes or Ca2(+)-independent effectors.

Adenine Nucleotides↗