Rb-mediated chromatin structure regulation and transcriptional repression.
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Animals↗
Biomedical subjects
H S Zhang
Publications and source records attributed to H S Zhang.
Spectrofluorimetric determination of thiols by use of N[P-(2-benzoxazolyl)phenyl]maleimide.
The weak fluorescence of N-[P-(2-benzoxazolyl)phenyl]maleimide (BOPM) can be greatly enhanced by thiol-containing compounds. A sensitive and simple spectrofluorimetric method based on the use of BOPM has been developed for the determination of thiols such as cysteine (Cys) and reduced glutathione (GSH). Calibration plots were linear in the concentration range from 0 to 1.6 x 10(-7) mol L(-1) for Cys and 0 to 1.7 x 10(-7) mol L(-1) for GSH. The detection limits (3a) were 2.36 x 10(-10) mol L(-1) for Cys and 1.49 x 10(-10) mol L(-1) for GSH. Many other amino acids (present at 100-fold greater concentrations) did not interfere with the determination. The proposed method has been used for the determination of Cys in protein hydrolysate and cystine electrolyte or GSH in serum, with recoveries of 95.4-103.7%.
Journal Article↗
A spectrofluorimetric method for cysteine and glutathione using the fluorescence system of Zn(II)-8-hydroxyquinoline-5-sulphonic acid complex.
The addition of thiol compounds to the fluorescence system of Zn(II)-8-hydroxyquinoline-5-sulphonic acid complex (Zn(II)-HQS) in H3BO3-Na2B4O7 buffer (pH 8.50) solution led to immediate fluorescence inhibition, which was proportional to their amounts. Based on this finding, a novel spectrofluorimetric method for the determination of cysteine (Cys) and reduced glutathione (GSH) has been developed. The detection limits were 17 ng ml(-1) and 0.6 microg ml(-1), respectively. Most amino acids had no interference at high concentrations. The proposed method has been applied to the determination of Cys in protein hydrolysate and cystine electrolyte, and GSH in human blood serum with recoveries of 95.6-104.5%.
Cysteine↗
N-hydroxysuccinimidyl-fluorescein-O-acetate for precolumn fluorescence derivatization of amino acids and oligopeptides in liquid chromatography.
A new fluorescent derivatizing reagent, N-hydroxysuccinimidyl-fluorescein-O-acetate, is used for the high-performance liquid chromatographic analysis of amino acids and oligopeptides. This reagent has the advantages of high-detection sensitivity in the visible region, specifically with amino groups, mild derivatization conditions, and little interference induced. The fluorescence properties of the reagent and its derivatives with amino acids and oligopeptides are studied. The conditions of the derivatization are investigated in detail. In the mobile phase of methanol-water (42:58, v/v) containing a 10 mM pH 5.0 citric acid-Na2HPO4 buffer, six amino acids and oligopeptides are separated in 20 min with fluorescence detection at excitation and emission wavelengths of 492 and 513 nm, respectively, with the detection limits for injected standards ranging from 0.64 to 12 fmol.
Amino Acids↗
N-hydroxysuccinimidyl fluorescein-O-acetate as a fluorescent derivatizing reagent for catecholamines in liquid chromatography.
A new amine-reactive derivatizing reagent, N-hydroxysuccinimidyl fluorescein-O-acetate (SIFA), was developed for catecholamine (CA) analysis in liquid chromatography. The reactivity of this reagent with the CAs norepinephrine (NE), epinephrine (E), and dopamine (DA) was investigated in detail. In aqueous methanol containing 32 mmol/L pH 9.0 H3BO3-Na2B4O7 buffer, SIFA reacted with NE, E, and DA under mild conditions. The derivatives were separated in 20 min on a C18 column with a mobile phase of methanol/water (38:62, v/v) containing 10 mmol/L pH 5.0 H3cit-Na2HPO4 buffer. At lambda(ex)/lambda(em) = 490/516 nm, the detection limits were 3.2, 12, and 56 fmol, respectively, with a signal-to-noise ratio of 3, which were comparable to those using 1,2-diphenylethylenediamine as the derivatizing reagent for CA analysis. Amino acids, aliphatic amines, and alcohols had no obvious interference with the determination. The proposed method has been applied to the determination of CAs in human urine, with recoveries of 95.3-103.9%.
Calibration↗
Exit from G1 and S phase of the cell cycle is regulated by repressor complexes containing HDAC-Rb-hSWI/SNF and Rb-hSWI/SNF.
We present evidence that Rb forms a repressor containing histone deacetylase (HDAC) and the hSWI/SNF nucleosome remodeling complex, which inhibits transcription of genes for cyclins E and A and arrests cells in the G1 phase of the cell cycle. Phosphorylation of Rb by cyclin D/cdk4 disrupts association with HDAC, relieving repression of the cyclin E gene and G1 arrest. However, the Rb-hSWI/SNF complex persists and is sufficient to maintain repression of the cyclin A and cdc2 genes, inhibiting exit from S phase. HDAC-Rb-hSWI/SNF and Rb-hSWI/SNF then appear to maintain the order of cyclin E and A expression during the cell cycle, which in turn regulates exit from G1 and from S phase, respectively.
Binding Sites↗
[Studies of gene regulation of de novo biosynthetic pathway of purine in Salmonella typhimurium. X. Isolation of purR(am) mutants and preliminary studies of amino acid substitution].
Starting from a super-repressed mutant of purR, 3-18, 439 independent candidates of purR- mutants were isolated by using NCE selecting plate with lactose as sole carbon source. Among these mutants. 11 amber mutants were detected by introducing a tRNA suppressor gene. Cotransduction analysis proved that the amber mutation sites of 11 amber mutants all located on purR. Amino acid substitution experiments were performed with three tRNA suppressors, supD, supE and supF, for each purR(am). The results showed that the same amino acid substitution occurred in different site of PurR protein could result in varied effects on purR function; different amino acid substitution occurred at the same position of PurR protein also could produced varied effects on purR function.
Bacterial Proteins↗
Active transcriptional repression by the Rb-E2F complex mediates G1 arrest triggered by p16INK4a, TGFbeta, and contact inhibition.
Rb inhibits progression from G1 to S phase of the cell cycle. It associates with a number of cellular proteins; however, the nature of these interactions and their relative significance in cell cycle regulation are still unclear. We present evidence that Rb must normally interact with the E2F family of transcription factors to arrest cells in G1, and that this arrest results from active transcriptional repression by the Rb-E2F complex, not from inactivation of E2F. Thus, a major role of E2F in cell cycle regulation is assembly of this repressor complex. We demonstrate that active repression by Rb-E2F mediates the G1 arrest triggered by TGFbeta, p16INK4a, and contact inhibition.
Animals↗
The molecular characterization of the major polar tube protein gene from Encephalitozoon hellem, a microsporidian parasite of humans.
The microsporidia are obligate intracellular protozoan parasites of increasing importance as human pathogens, which are characterized by a small resistant spore with a single polar filament that coils around the sporoplasm. When stimulated, the polar filament rapidly everts out of the spore to form a hollow polar tube through which the sporoplasm passes, thus serving as a unique mechanism of transmission. A genomic library of the human microsporidium Encephalitozoon hellem was screened using a polyclonal rabbit antibody (anti-PTP Eh55) produced to the major HPLC purified polar tube protein (PTP) of E. hellem. This antibody localized to intrasporal polar filaments and extrasporal polar tubes of E. hellem by immunogold electron microscopy confirming the polar tube specificity of the antibody. A total of 14 anti-PTP Eh55 reactive genomic clones were identified and purified. A PTP gene was identified consisting of 1362 bp coding for 453 amino acids. The N-terminus of the translated protein consists of aputative N-terminal signal sequence of 22 amino acids, which when cleaved results in a mature protein of 431 amino acids with a predicted molecular mass of 43 kDa. The protein has a high proline content (14.6%) and contains a central domain of six alternating tandem repeats of 20 amino acids. After ligation of the gene into a glutathione S-transferase (GST) expression vector, a fusion protein was produced that reacted by immunoblotting with the polar tube specific anti-PTP Eh55. The gene was present as a single copy in the genome and there was no homology with other known genes. As the polar tube is a critical structure for the transmission of this organism to a new host cell, further study of PTPs may lead to the development of new therapeutic strategies and diagnostic tests.
Amino Acid Sequence↗
Expression of potential target antigens for immunotherapy on primary and metastatic prostate cancers.
Defining the expression of tumor-associated antigens on primary and metastatic prostate cancer is the crucial first step in selecting appropriate targets for immune attack. In this study, the distribution of the tumor-associated antigens GM2, Tn, sTn, Thompson-Friedenreich antigen (TF), Globo H, Le(y), MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, MUC7, carcinoembryonic antigen, beta chain of human chorionic gonadotropin (hCG beta), HER2/neu, PSMA, and KSA on primary and metastatic prostate cancer and 16 types of normal tissues was compared by immunohistochemistry, using a panel of well-characterized monoclonal antibodies. Our results show that GM2, KSA, and MUC2 were strongly expressed on 8 or 9 of 9 metastatic prostate cancer biopsy specimens and, with PSMA, hCG beta, TF, Tn, and sTn, on 8 or more of 11 primary prostate cancer specimens. Tn, MUC1, and PSMA were expressed on 4-6 of 9 metastatic specimens. The remaining antigens were expressed on no more than three of nine metastatic specimens. Normal tissues were also tested with all antibodies. With regard to the eight antigens most widely expressed on prostate cancers, PSMA was not expressed significantly on any of the normal tissues except prostate epithelium. Tn, sTn, hCG beta, and MUC2 were detected on up to 3 of 10 types of normal epithelia. GM2, TF, MUC1, and KSA were more broadly distributed on normal epithelia, all primarily at the secretory borders. STn, KSA, and hCG beta were also detected in the testis, and GM2 was expressed on gray matter of brain. From the 30 antigens that we have screened, this study provides the basis for selecting GM2, TF, Tn, sTn, hCG beta, MUC1, MUC2, KSA, and PSMA as target antigens for specific immunotherapy of prostate cancer.
Amino Acid Sequence↗
Inhibition of the specific 3H-DL-Glu binding in the hippocampus of rat brain by lead.
The effect of Pb2+ on 3H-DL-Glutamate (3H-DL-Glu) binding in the membrane preparations from the hippocampus of rat brain was investigated with a view to explaining the cognitive and learning deficits produced by the heavy metal. The results indicated that Pb2+ (3.1-25.0 mumol.L-1) inhibited 3H-DL-Glu binding in a concentration-dependent manner. Scatchard analysis further revealed that at a concentration of 6.3 mumol.L-1 Pb2+ interfered with binding mainly through significantly decreasing the density of binding sites. This finding provided an important insight into Pb2(+)-induced impairments in learning and memory previously documented in children and in experimental animals chronically exposed to Pb2+.
Animals↗
Selection of tumor antigens as targets for immune attack using immunohistochemistry: protein antigens.
The relative expression of mucin antigens MUC1, MUC2, MUC3, MUC4, MUC5AC, MUC5B, and MUC7 and glycoprotein antigens KSA, carcinoembryonic antigen, prostate-specific membrane antigen (PSMA), HER-2/neu, and human chorionic gonadotropin-beta on different cancers and normal tissues is difficult to determine from available reports. We have compared the distribution of these antigens by immunohistology on a broad range of malignant and normal tissues. MUC1 expression was most intense in cancers of breast, lung, ovarian, and endometrial origin; MUC2 was most intense in cancers of colon and prostate origin; and MUC5AC was most intense in cancers of breast and gastric origin. MUC4 was intensely expressed in 50% of cancers of colon and pancreas origin, and MUC3, MUC5B, and MUC7 were expressed in a variety of epithelial cancers, but not so intensely. KSA was intensely and uniformly expressed on all epithelial cancers; carcinoembryonic antigen was expressed in most cancers of breast, lung, colon, pancreas, and gastric origin; and PSMA was expressed only in cancers of prostate origin. Human chorionic gonadotropin-beta was expressed on the majority of sarcomas and cancers of breast, lung, and pancreas origin, although intense staining was not seen. Staining on normal tissues was restricted to one or many normal epithelial tissues ranging from MUC3, MUC4, and PSMA, which were expressed only on epithelia of pancreas, stomach, and prostate origin, respectively, to MUC1 and KSA, which were expressed on most normal epithelia. Expression was restricted to the secretory borders of these epithelia while stroma and other normal tissues were completely negative. These results plus the results of the two previous papers (S. Zhang et al, Int. J. Cancer, 73: 42-49, 1997; S. Zhang et al., Int. J. Cancer, 73: 50-56, 1997) in this series provide the basis for selection of multiple cell surface antigens as targets for antibody-mediated attack against these cancers.
Antibodies, Monoclonal↗
Selection of tumor antigens as targets for immune attack using immunohistochemistry: I. Focus on gangliosides.
Understanding the distribution of tumor-associated antigens on cancers and normal tissues is essential for selection of targets for cancer immunotherapy. Seven carbohydrate antigens, potential targets for immunotherapy, were studied using a panel of well-characterized MAbs by immunohistochemistry on cryostat-cut tissue sections of 13 types of cancers and 18 normal tissues. GD2 and GD3 were present on most cancers of neuroectodermal origin and GD2 was also present on B cell lymphomas. 9-O-acetyl-GD3 was detected only on melanoma while fucosyl GM1 was detected only on small cell lung cancers (SCLC). Surprisingly, GM2 was strongly expressed on all tested tumors, including cancers of neuroectodermal origin and cancers of epithelial origin. Polysialic acid was primarily expressed on SCLC and neuroblastomas. Globo H was present on most cancers of epithelial origin. These antigens were also identified in normal tissues. Fucosyl GM1 was not expressed significantly on any of the normal tissues analyzed. GD3, GD2, GM2 and polysialic acid were detected in normal brain to varying degrees. GM2 and Globo H were expressed on the luminal surface of epithelia of a variety of organs. The unexpected expression of GM2 on a broad range of cancers and normal epithelial tissues was confirmed by loss after methanol fixation and by immune thin layer chromatography.
Animals↗
Selection of tumor antigens as targets for immune attack using immunohistochemistry: II. Blood group-related antigens.
Blood group-related antigens have been attractive targets for immunotherapy of cancer since their initial identification as cancer-related antigens. However, available information on the relative expression of most of these antigens on human malignant and normal tissues has been insufficient for selecting optimal antigens and tumors for immune attack. In this study, the distribution of the blood group-related antigens TF, Tn, sTn, Le(a), sialyl Le(a), Le(b), Le(x), sialyl Le(x), polyfucosyl Le(x) and Le(y) on 13 types of cancer and 16 normal tissues was compared. Our results show that sTn is strongly expressed on cancers of breast, colon, stomach, ovary, prostate and uterus; Tn on prostate cancer; TF on cancers of breast, colon, ovary, prostate and uterus; Le(y) on the cancers of colon, lung, pancreas and ovary; Le(a) and Le(x) on gastric cancer; and sialyl Le(a) and sialyl Le(x) on colon cancer. The complete absence of these antigens on cancers of neuroectodermal or mesodermal origin including melanoma, sarcoma, neuroblastoma and B cell lymphoma is as striking as their widespread presence on tumors of epithelial origin. Normal tissues were also tested. Tn and Le(b) were only detected on gastric and ovarian epithelia; sTn on Leydig cells of testis in addition to gastric and ovarian epithelia; Le(x) and sialyl Le(x) on polymorphonuclear leukocytes; and TF, Le(a), sialyl Le(a), Le(x), sialyl Le(x), polyfucosyl Le(x) and Le(y) on epithelia from a variety of tissues.
Animals↗
Clinical features and comprehensive treatment of late stage radiation skin injuries.
105 patients with late stage radiation skin injury were treated from 1970 to 1986, using drugs combined with surgical intervention according to the clinical features of the injury. Drug therapy consisted of topical application of urea, antibiotics, trypsin and elastase, and systematic use of alpha 2-Macroglobulin. Of 62 patients receiving medication, 55 (88.7%) were completely or basically treated and 7 failed. Of 51 lesions of 43 patients receiving surgical treatment, 47 healed by first intention. In 4 patients, necrosis of partial and/or peripheral skin flaps healed after renewed repair.
Adolescent↗
[Citation analysis of Acta Pharmacologica Sinica 1984-1989].
Citation analysis was made bibliometrically on the collection and dispersion of the references in Acta Pharmacologica Sinica 1984-1989. Core periodicals were sorted out: 31 in foreign languages and 6 in Chinese. Suggestions are proposed to the information services.
Bibliometrics↗
[Burn mortality and multiple organ failures].
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Adolescent↗
[Particle induced X-ray emission for trace element analysis of hairs from patients with cancer].
In this paper, trace element analysis of the hairs from the patients with nasopharyngeal carcinoma (NPC) and osteoma was made using particle induced X-ray emission (PIXE) technique in order to obtain some information on the correlation between trace element and these two tumors. The hair samples of 34 NPC patients were each collected before and three months after radiotherapy (60Co) (group 1). The hair specimens from 34 osteoma patients were collected preoperatively and postoperatively. For comparison, 65 hair samples were collected from 40 normal subjects (group 2) and 25 NPC patients, who had received radiotherapy (60Co) five years before without any recrudescence (group 3). The trace element analysis of all specimens was made by PIXE. The results show that there is a significant difference between groups 1 and 2 (P less than 0.01) but no difference is found between groups 2 and 3 for Mn, Cu, Zn, As etc. content in the hairs. Cu and Zn content in the hairs of the osteoma patients is much lower than that of the normal subjects (P less than 0.01) while for K, Ti and Mn content, the former is higher than the latter. The above experimental results are discussed in detail.
Hair↗