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Biomedical subjects

Q Su

Publications and source records attributed to Q Su.

At least 109 records · Page 6Linked to original sources
PubMed1995

[Expression of c-myc, c-erbB-2, insulin-like growth factor II andepidermal growth factor receptor in hepatitis B, cirrhosis and hepatocellular carcinoma].

In order to get a better understanding of expressions of multiple oncogenes and their possible roles in human hepatocarcinogenesis, 379 cases of liver tissues were investigated immunohistochemically. EGF receptors were immunolocalized mainly in the sinusoidal endothelial cells. They might not take part in the development of hepatocellular carcinoma (HCC), c-myc protein was showed to be expressed in cancer cells and the hepatocytes in the so-called "large-cell dysplasia" and in ductular metaplasia (DM). Its expression was also observed in some zone II hepatocytes of hepatic accini in 21% of normal liver tissues, which indicated that c-myc expression might also be related to the proliferation of mature hepatocytes. The positivity rate of c-erbB-2 product was shown to be highest among the oncogenic genes examined in this study. The positivity was observed in small polygonal liver cells (SPLCs) and the hepatocytes were observed in SCD and in DM. The expression level of c-erbB-2 oncogene in HCC cells was higher significantly than in normal hepatocytes, but lower than in SPLCs, the hepatocytes in SCD and in DM. We suggest that c-erbB-2 gene activation may play an important role not only in HCC genesis, but also in DM. Insulin-like growth factor II (IGF II), an oncofetal hepatocellular growth factor, was immunolocalized in the cancer cells, SPLCs and the hepatocytes in SCD, which indicated that activation and hyperexpression of IGF II gene might be responsible for the prominent proliferation of SPLCs and SCD, a crucial step in malignant transformation of hepatocytes.(ABSTRACT TRUNCATED AT 250 WORDS)

Carcinoma, Hepatocellular↗
PubMed1995

[Expression of c-erbB-2 protein and EGF receptor in hepatitis B, cirrhosis and hepatocellular carcinoma].

The expressions of c-erbB-2 oncogene and epidermal growth factor receptor (EGFR) were investigated immunohistochemically in specimens from 184 cases of hepatitis B, cirrhosis and hepatocellular carcinoma (HCC) and 29 normal liver specimens. EGFR was expressed in 36% (48/134) of the hepatocellular carcinoma and chronic liver disorder specimens and it was immunolocalized mainly in the sinusoidal endothelial cells. No significant difference was found between EGFR expression in HCC and in benign chronic liver disorders. These results indicate that EGFR may have some role in the proliferation of the sinusoidal epithelial cells in chronic liver disease. Low level c-erbB-2 expression was observed in 5/29 (17%) of normal liver specimens. In chronic hepatitis B and liver cirrhosis, its expression was found in all specimens. c-erbB-2 protein was immunolocalized mainly in small polygonal liver cells (SPLCs) and hepatocytes in small-cell dysplasia (SCD) and in ductular metaplasia (DM); c-erbB-2 expression in HCC cells was found to be weaker than in SPLCs, the hepatocytes in SCD and in DM. These results indicate that activated c-erbB-2 oncogene may have a role in human HCC genesis through promoting the development of SCD from SPLC proliferation and the progression of SCD. The close relation between the expression of c-erbB-2 and HBxAg imply that the activation of c-erbB-2 in human liver tissues may be related to HBV X gene.

Carcinoma, Hepatocellular↗
PubMed1994

Metal chelates as reversible stains for detection of electroblotted proteins: application to protein microsequencing and immunoblotting.

Coomassie brilliant blue and Ponceau red have traditionally been used to stain electroblotted proteins, since they are compatible with existing N-terminal and internal protein microsequencing as well as with immunoblotting procedures. With recent improvements in sequencing and immunoblotting technology, detection of significantly smaller amounts of protein has become necessary. Metal complexes were evaluated as alternatives to conventional stains. Electroblotted proteins were detected by blocking nonspecific sites with polyvinylpyrrolidone-40 followed by incubation in metal chelate solutions at acidic pH values. Two of the most promising metal chelate stains were the Ferrozine/ferrous complex and the ferrocyanide/ferric complex. Both stained a wide variety of proteins and peptides quantitatively. Dot blots and 1D and 2D electroblots were successfully stained using iron chelates. When these two stains were utilized in combination, they were of equivalent sensitivity to colloidal gold stain. The reversibility of the metal chelate stains was substantiated by incubating stained membranes at neutral to basic pH in the presence of 20 mM ethylenediaminetetraacetic acid to rapidly elute the complexes from the bound proteins. The chelate stains were determined to be fully compatible with immunoblotting, N-terminal, and in situ internal protein microsequencing.

Amino Acid Sequence↗
PubMed1994

Substrate- and species-specific processing enzymes for chloroplast precursor proteins.

Using different precursors of chloroplast proteins and stromal extracts from both Chlamydomonas reinhardii and pea chloroplasts, we analysed the specificity of stroma-localized processing peptidases. By gel filtration of a stromal extract from isolated Chlamydomonas chloroplasts, fractions could be separated containing enzymic activities for processing the precursors of the small subunit of ribulose-1,5-bisphosphate carboxylase (pSS) and of the protein OEE1 from the photosynthetic water-splitting complex (pOEE1). The enzymes differed not only in molecular size, but also in their sensitivity to inhibitors and in their pH optima. Obviously, in the stroma of Chlamydomonas chloroplasts different peptidases exist for processing of pSS and pOEE1, the latter being converted into an intermediate-sized form, iOEE1, which was found to be further processed to mature OEE1 by a thylakoid-associated protease. To study the species-specificity of the stromal peptidases, stromal extracts from Chlamydomonas and pea chloroplasts were incubated with pSS from either of these organisms. In the heterologous combinations, the precursors were partly hydrolysed, but not to the correct size. In importation assays, pSS from pea (but also the precursor of the ribosomal protein L12 from spinach) could not enter into chloroplasts from Chlamydomonas. In contrast, the algal pSS was imported into chloroplasts from pea, although it was not processed to mature SS. Our results indicate that the importation machinery and the pSS-processing enzymes in higher plants and green algae have different specificities and that in Chlamydomonas several stromal peptidases for different precursor proteins exist.

Animals↗
PubMed1994

Expression of insulin-like growth factor II in hepatitis B, cirrhosis and hepatocellular carcinoma: its relationship with hepatitis B virus antigen expression.

Expression of insulin-like growth factor II in two human hepatocellular carcinoma cell lines and in hepatitis B, cirrhosis and hepatocellular carcinoma in 419 cases were investigated, and its relationship with the expression of hepatitis B virus X gene was studied by means of immunohistochemical and electron microscopic techniques. The results demonstrated that hepatocellular carcinoma cells (SMMC 7721 and QGY 7703) in culture could express insulin-like growth factor II. Expression seemed to be regulated by cell density, which was suggested as the molecular basis of the contact inhibition of cell proliferation. In tissue sections, cells with high expression of insulin-like growth factor II were observed not only in hepatocellular carcinoma (93%) but also in 95% of the pericancerous liver tissues, 72% of cirrhotic livers, 64% of chronic active hepatitis and 37% of chronic persistent hepatitis. In most cases of hepatocellular carcinoma, insulin-like growth factor II was localized in the cytoplasm of the cancer cells. In the benign liver disorders, four types of cells that highly expressed insulin-like growth factor II were observed: (a) a kind of small liver cell we named the small polygonal liver cell; (b) multinuclear giant hepatocytes; (c) hepatocytes in most of hyperplastic and neoplastic nodules, small hepatocyte nodules and some of regenerative nodules; and (d) some proliferating ductular cells. Even more interestingly, insulin-like growth factor II expression was shown to be closely related to the expression of hepatitis B virus X gene product. We suggest that the activation of insulin-like growth factor II gene and its overexpression may be a crucial step in the processes of hepatitis B virus-associated hepatocarcinogenesis and that the X gene product may activate the insulin-like growth factor II gene through a transactivation mechanism. In addition, we studied the characteristics of small polygonal liver cells, and the roles they may play in the regeneration and carcinogenesis of hepatitis B virus-infected liver are discussed.

Carcinoma, Hepatocellular↗
PubMed1994

[Comparative study of the expression of IGF-2 and HBxAg in human hepatocellular carcinoma and liver cirrhosis].

60 Cases of hepatocellular carcinoma (HCC) and 47 cases of liver cirrhosis (LC) were examined with immunocytochemistry methods using antibodies against IGF-2 and HBxAg on paraffin embedded sections. 32 HCC and 37 LC were found to be positive to HBxAg, in which the positive rates of IGF-2 were 100% (32/32) and 94.6% (35/37) respectively. 28 HCC and 10 LC were found to be HBxAg negative, IGF-2 was positive in 23 HCC (82.1%) and 6 LC (60%). The positive expression rates of IGF-2 in the HBxAg positive tissues were significantly higher than those in the HBxAg negative tissues (P < 0.05). There were three types of IGF-2 distribution in HCC and LC: (1) perinucleus; (2) diffuse in cytoplasm; (3) in nucleus. Small polygonal liver cells (SPLC) were found in the liver tissue surrounding the tumor or cirrhosis, the SPLC were positive to both IGF-2 and HBxAg. The positive rates of IGF-2 in SPLC were 86.4% (38/44) in HBxAg positive group and 40.5% (15/37) in the HBxAg negative group. The above findings suggest that IGF-2 plays an important role in abnormal proliferation of HCC and SPLC. The relation of IGF-2 and HBxAg and the nature of SPLC were also discussed.

Carcinoma, Hepatocellular↗
PubMed1994

[Molecular cloning of the adherence gene cluster from uropathogenic Escherichia coli and preparation of its antisera].

A genomic library of the uropathogenic E. coli J96 was constructed by using cosmid pHC79 as cloning vector. Two positive recombination cosmids which could express the adherence characters were acquired. From both cosmids a EcoRI fragment was subcloned into the vector pACYC184 by shot-gun method. Three colonies were found which exhibited MRHA and production of P Pili. One of them, pCT10/E. coli K-12 P678-54, was about 14.6 kb and was used to prepare the antisera. After absorption with pACYC184/E. coli K-12 P678-54 for three times, the antisera were revealed specific against the adherence gene cluster of uropathogenic E. coli by the SDS-PAGE and Western blotting of the P pilus crude extracts and the hemagglutination inhibition test.

Adhesins, Bacterial↗
PubMed1993

Partial purification and properties of enzymes involved in the processing of a chloroplast import protein from Chlamydomonas reinhardii.

Two stromal peptidases (SPP-1 and SPP-2) were partially purified from chloroplasts of Chlamydomonas reinhardii. They specifically processed in vitro the precursor of the small subunit of ribulose-1,5-bisphosphate carboxylase (pSS), which had been synthesized by using the cloned rbcS-2 gene of Chlamydomonas. SPP-1 shortened pSS to an intermediate-sized form (iSS), while SPP-2 cut pSS and iSS to the mature small subunit SS. N-terminal amino acid sequencing demonstrated that the reaction product obtained with SPP-2 had an N-terminus identical to natural SS, and that iSS derived from pSS by hydrolysis at the amino side of the methionine located within the transit sequence. By gel filtration, apparent molecular masses of 340 kDa and 90 kDa were determined for SPP-1 and SPP-2, respectively. The comparison of these molecular masses with the protein patterns obtained by SDS/PAGE of the partially purified enzymes suggested that at least SPP-1 was a multimeric protein. The enzymes differed also in their pH optima of about 8 (SPP-1) and 9 (SPP-2) and in their sensitivity to different inhibitors. However, both enzymes seem to be serine proteases as they were completely blocked by N-alpha-tosyl-L-lysinechloromethane or tosylphenylalaninechloromethane, respectively. Competition experiments, using either mature SS or a synthetic hexadecapeptide with 15 amino acids similar to the C-terminal end of the transit sequence of pSS, indicated that SPP-2 had some affinities not only to the transit sequence of pSS, but especially to sequences in the mature protein part. We conclude that SPP-2 in Chlamydomonas is the enzyme involved in import of pSS into chloroplasts and responsible for its processing by a one-step mechanism.

Amino Acid Sequence↗
PubMed1992

[The abnormal cytokeratin expression in HBV-caused hepatitis, early-cirrhotic and cirrhotic livers, its mechanism and significance].

An ABC immunohistochemical study of the expression of cytokeratin (CK19 and CK18) was carried out in 315 cases of HBV-caused hepatitis, early-cirrhotic and cirrhotic livers. It was shown that hepatocytes in 73% of chronic active hepatitis (CAH) (80/110) and 81% of early-cirrhotic and cirrhotic livers (117/144) expressed CK19 (the abnormal CK expression), which could be of help in differentiating CAH from chronic persistent hepatitis, subtype CAH (mild, moderate to severe type) and in determining the activity of early-cirrhotic and cirrhotic livers. The abnormal CK expression was shown to be closely related to the activity of liver disorders. The CK19 expression in hepatocytes had the closest relations with the piece-meal necrosis of hepatocytes, isolation of hepatocytes into groups by connective tissue, and fibrosis. It is suggested that CK19 expression may be one of the local reactions to the piece-meal necrosis of hepatocytes.

Chronic Disease↗
PubMed1992

[Microbiological production of 3-oxo-bisnorchola-1, 4-dien-22-oic acid from cholesterol by an Arthrobacter 82].

Among nineteen strains of Arthrobacter which showed to be able to decompose cholesterol in preliminary experiments, a strain of Arthrobacter 82 was selected for microbiological production of 3-oxo-bisnorchola-1,4-dien-22-oic-acid (BNC) from cholesterol. The yield is over of 50% weight percent concentration of 0.25% in the presence of cobalt sulfate. The main intermediate in such a conversion process is cholestenone. Lower glucose and higher corn steep liquor concentration were favorable for side chain degradation of cholestenone and more BNC could be produced. BNC was crystallized in acidic solution and obtained by centrifugation. The structure and characteristics of BNC has been identified by means of conventional physical, chemical and spectrometric techniques.

Arthrobacter↗