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Biomedical subjects

S C Shen

Publications and source records attributed to S C Shen.

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

Taxol-induced p34cdc2 kinase activation and apoptosis inhibited by 12-O-tetradecanoylphorbol-13-acetate in human breast MCF-7 carcinoma cells.

The p34cdc2 kinase is a highly regulated serine-threonine kinase that, when complexed with cyclins A and B, controls cell entry into mitosis. Recently, premature activation of p34cdc2 was shown to be required for apoptosis induced by a wide variety of agents. Here, we show that Taxol induced p34cdc2 kinase activity with a peak at 6 h in human breast carcinoma MCF-7 cells. We subsequently observed that the activation of CPP32/Yama protease as well as the cleavage of its substrate poly(ADP-ribose) polymerase occurred 9 h after Taxol treatment. Olomoucine, a potent p34cdc2 inhibitor, effectively prevented Taxol-induced p34cdc2 kinase activation and subsequent apoptosis. Furthermore, the treatment of cells with cyclin B1-specific antisense oligonucleotide also blocked Taxol-induced apoptosis, suggesting that cyclin B1-associated p34cdc2 kinase plays an important role in the induction of apoptosis by Taxol. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a protein kinase C activator, was found to exert strong protection against Taxol-induced cell death in MCF-7 cells. TPA inhibited Taxol-mediated activation of p34cdc2 kinase by preventing the dephosphorylation of the Tyr-15 residue on p34cdc2 without altering the levels of Cdc2 and cyclin B1. In contrast, the ability of Taxol to enhance tubulin polymerization was not inhibited by TPA. These findings suggest that modulation of protein kinase C signaling can protect against Taxol-induced cell death by inhibiting p34cdc2 kinase activation.

Antineoplastic Agents, Phytogenic↗
PubMed1997

Production of biologically active recombinant tilapia insulin-like growth factor-II polypeptides in Escherichia coli cells and characterization of the genomic structure of the coding region.

Insulin-like growth factor-II (IGF-II) is a fetal growth factor in humans, but has not been clearly identified in fish up to now. For a detailed understanding of the physiological response of fish IGF-II, the first step was to clone tilapia IGF-II cDNA from the brain cDNA library, coding the region of genomic DNA, and also expressing tilapia IGF-II polypeptides from Escherichia coli. Tilapia cDNA sequences total 1,977 bp, and predicted nucleotide sequences and amino acid sequences of tilapia share 77.9% and 90.7% homology identity with rainbow trout IGF-II, respectively. The genomic structure of the tilapia prepro-IGF-II coding region is very difficult to sequence in mammals and birds. The cloned tilapia IGF-II gene coding region appears much more complex than in other vertebrates. In tilapia IGF-II, the first coding exon I encoding part of the signal peptide sequence is 25 amino acids shorter than the first coding exon of mammals and birds. The other 23 amino acids of the signal peptide, and the first amino acids of the B domain and C domain are encoded by tilapia coding exon 2. The C, A, and D domains, and the first 20 amino acids of the E peptide are encoded by tilapia coding exon 3. The other E peptides and the 3' untranslated region (UTR) region are encoded by tilapia coding exon 4. These data show that the IGF-II genes have significantly differing structures in vertebrate evolution, and there are differences of interrupting introns in the IGF-I genomic structure compared with mammals. To obtain recombinant biologically active polypeptides, tilapia IGF-II B-C-A-D domains were amplified using the polymerase chain reaction (PCR), then ligated with glutathione S-transferase (GST, pGEX-2T vector). Tilapia recombinant IGF-II protein was purified and characterized in E. coli. The fusion protein was also digested with thrombin and appeared as a recombinant IGF-II polypeptide single band with a molecular mass of 7 kD. The recombinant tilapia IGF-II protein biological function was measured by stimulation of [3H]thymidine incorporation. The assay concentration was set up from 0 to 120 nM to stimulate tilapia ovary cell line (TO-2) significantly to uptake thymidine. The results suggest that the recombinant IGF-II protein was dose dependent.

Amino Acid Sequence↗
PubMed1994

[Combined color Doppler and pulsed Doppler in the diagnosis of small hepatocellular carcinomas].

The combined studies by using color Doppler (CD) and pulsed Doppler (PD) technique in 56 patients with 71 solid hepatic lesions smaller than 3 cm in diameter were carried out. The detecting rates of arterial signals in small hepatocellular carcinomas (sHCC) group, hepatic cavernous hemangiomas (HCH) group and others group were 86.9%, 37% and 33% respectively. Whereas, the average value of resistance index (RI) in sHCC group was very higher than that in other groups. By using combined CD and PD space-taking lesions of the liver are tentatively diagnosed as sHCC under conditions of color flow, arterial signals, and a RI of more than 50%. The specificity (96%) and accuracy (90%) of the diagnosis superior to the conventional US (P < 0.005).

Carcinoma, Hepatocellular↗
PubMed1994

Partial hepatectomy for hepatocellular carcinoma in a patient with hemophilia: a case report.

We describe successful partial hepatectomy for hepatocellular carcinoma (HCC) in a 43-year-old man with severe factor VIII deficiency (hemophilia A). Tumor size and plasma alpha-fetoprotein (AFP) decreased spontaneously prior to surgery. HCC was found in the anterior superior segment of the liver, with invasion of the diaphragm. A limited partial resection of the liver and diaphragm was performed. The administration of factor VIII during and immediately after surgery resulted in no postoperative bleeding complications. Macroscopic findings revealed hemorrhage and necrosis throughout the intrahepatic portion of the tumor. Viable HCC cells were recognized histologically in the intrahepatic tumor and infiltrating the diaphragm. In patients with hemophilia there is a tendency for HCC to hemorrhage, which may obscure the diagnosis. Appropriate administration of factor VIII permits the safe resection of HCC in hemophilia A.

Adult↗
PubMed1993

The ability of polymorphonuclear leukocytes to produce active oxygen in a model of peritonitis in rats.

To elucidate the mechanism of enhancing survival in peritonitis rats treated with lentinan, a fully purified beta-1,3-glucan, we measured the active oxygen-producing ability of polymorphonuclear leukocytes (PMNs). Four groups of rats (group I, fecal peritonitis control; II, rats receiving 3 mg/kg lentinan intraperitoneally at the same time as peritonitis induction; III, rats receiving 1 mg/kg gentamicin intramuscularly; and IV, rats receiving combined lentinan-gentamicin treatment) were used. The survival period was significantly longer in group IV than in the other three groups. The ability of ascitic PMNs to produce active oxygen (superoxide, H2O2, myeloperoxidase) was significantly more than that of blood PMNs in each group at 20 h after peritonitis induction. The increase in active oxygen production in ascitic PMNs was higher in group IV compared with that in the other three groups. The concentration of lentinan in the blood was high at 24 h after administering lentinan intraperitoneally to both the normal and peritonitis rats. In the in vitro study, the superoxide production in normal rat blood PMNs was significantly higher in the presence of cytokines (IL-1 beta, IL-6, TNF-alpha) without dose-dependence but was not higher for the lentinan group than in the control. This study therefore suggests that lentinan activated the peritoneal macrophage secretory activity and produced cytokines which thus enhanced the ability of PMNs to produce active oxygen, which possesses a bactericidal ability in PMNs.

Animals↗
PubMed1992

The complete nucleotide sequence of the Crossostoma lacustre mitochondrial genome: conservation and variations among vertebrates.

The complete mitochondrial (mt) genome of Crossostoma lacustre, a freshwater loach from mountain stream of Taiwan, has been cloned and sequenced. This fish mt genome, consisting of 16558 base-pairs, encodes genes for 13 proteins, two rRNAs, and 22 tRNAs, in addition to a regulatory sequence for replication and transcription (D-loop), is similar to those of the other vertebrates in both the order and orientation of these genes. The protein-coding and ribosomal RNA genes are highly homologous both in size and composition, to their counterparts in mammals, birds, amphibians, and invertebrates, and using essentially the same set of codons, including both the initiation and termination signals, and the tRNAs. Differences do exist, however, in the lengths and sequences of the D-loop regions, and in space between genes, which account for the variations in total lengths of the genomes. Our observations provide evidence for the first time for the conservation of genetic information in the fish mitochondrial genome, especially among the vertebrates.

Animals↗
PubMed1992

Characterization of a Gy4 glycinin gene from soybean Glycine max cv. forrest.

The glycinin gene family encoding the glycinin subunits in soybean plants is composed of at least five gene members. A genomic clone lambda S312 containing the Gy4 gene from a genomic library of cv. Forrest was isolated and partially characterized. The organization of this gene was found to be similar to that of a null allele from cv. Raiden, but different from the Gy4 gene from cv. Dare. The complete nucleotide sequence of this gene has been determined. It is 2599 bp long consisting of four exons and three introns. Comparing the DNA sequences between this gene and the gene from Dare and a null allele from Raiden, the difference found in the coding region was 5'-GCAGTGCAAG-3' (nt 824 to 833) in the former case versus 5'-TGGAGTTGCAATT-3' (nt 1314 to 1326) in the latter case in the exon 2 domain, resulting in three amino acid differences and one amino acid absence. Some other differences were also found in the non-coding region. The coding sequence and 5'-flanking region of the Gy4 gene, when compared with that of other legumin genes as well as group 1 glycinin subunit genes, revealed some interesting features: (1) a transposable element-like sequence was found in the hypervariable region (HVR) of the exon 3 domain, which was lacking in the legumin and the glycinin group 1 genes; (2) in the 5'-flanking region from nt -145 to -1, two high-homology sequences were found: one from nt -141 to nt -132, the other from nt -118 to nt -92 which includes the 'legumin box' and the RY repeat element.

Amino Acid Sequence↗
PubMed1986

Oxygen sensitivity of the nifLA promoter of Klebsiella pneumoniae.

Oxygen sensitivity of the nifLA promoter of Klebsiella pneumoniae has been demonstrated. Studies on the oxygen regulation of nifB-lacZ and nifH-lacZ fusions in the presence of the nifLA operon, which contains either an intact or a deleted nifL gene, indicate that possibly both the nifL promoter and the nifL product are responsible for nif repression by oxygen.

Genes, Bacterial↗
PubMed1986

Temperature sensitivity of a nifA-like gene in Enterobacter cloacae.

Nitrogen fixation (nif) genes of Enterobacter cloacae, a rhizosphere diazotroph of rice plants, were identified by using cloned Klebsiella pneumoniae nif gene fragments as probes for molecular hybridization. The product of a nifA-like gene of E. cloacae appeared less temperature sensitive than the K. pneumoniae nifA gene product. This result correlates with the fact that E. cloacae can fix nitrogen at 39 degrees C, while K. pneumoniae cannot.

Bacterial Proteins↗
PubMed1986

Fatal massive hepatic necrosis: a probable hypersensitivity reaction to sulfasalazine.

Sulfasalazine (salicylazosulfapyridine) is a commonly prescribed oral medication for inflammatory bowel disease. We report a case of a 15-yr-old boy with ulcerative colitis who developed a generalized hypersensitivity reaction with a serum sickness-like syndrome and severe hepatotoxicity while taking sulfasalazine, perphenazine, and amitriptyline. The injury to the liver persisted for 5 months after withdrawal of the drugs, and the patient died of terminal hepatic failure with massive hepatic necrosis. Severe hepatic toxicity to sulfasalazine is uncommon, but it can be fatal.

Adolescent↗
PubMed1985

Mutational analysis of the Klebsiella pneumoniae nitrogenase promoter: sequences essential for positive control by nifA and ntrC (glnG) products.

ntr (nitrogen regulated) and nif (nitrogen fixation) promoters are structurally similar to each other but bear no resemblance to canonic Escherichia coli promoters. ntr promoters are normally activated by the ntrC (glnG) product, but they can also be activated by the ntrC-related Klebsiella pneumoniae nifA product. In contrast, nif promoters of K. pneumoniae such as the nitrogenase (nifH) promoter can only be nifA activated. In this paper, we report the isolation and characterization of 28 mutants of the K. pneumoniae nifH promoter. Class A mutants no longer respond to nifA-mediated transcription, and class B mutants can now respond to ntrC-mediated activation. These two classes of mutants define sequences important to nifA- and ntrC-mediated transcription. Most surprising is that a single base change is sufficient to convert a nifA-activated promoter into an ntrC-activated one.

Base Sequence↗
PubMed1983

An open reading frame upstream from the nifH gene of Klebsiella pneumoniae.

An open reading frame upstream from nifHDK operon of Klebsiella pneumoniae had been described. The orientation of this open reading frame is opposite to that of nifHDK and sequence homology was found between the open reading frame promoter and the promoter of nifHDK operon. A recombinant plasmid carrying the promoter region of the open reading frame fused to the beta-galactosidase gene was constructed. Strains of E.coli were transformed with the plasmid containing this open reading frame promoter-lacZ fusion or co-transformed with it and a plasmid carrying the nifA gene. An appreciable activity of beta-galactosidase was found in strains which received both plasmids, indicating that the promoter of the open reading frame can be activated by the product of nifA gene. Thus, the open reading frame found between nifHDK operon and nifJ behaves just like other nif genes of K.pneumoniae in requiring the product of nifA as the positive effector for expression.

Amino Acid Sequence↗
PubMed1983

Benign glandular inclusions in lymph nodes, endosalpingiosis, and salpingitis isthmica nodosa in a young girl with clear cell adenocarcinoma of the cervix.

A 12-year-old girl underwent radical surgery for clear cell adenocarcinoma of the endocervix. Bilaterally dilated fallopian tubes with hyperplastic mucosal folds and salpingitis isthmica nodosa were found in association with benign glandular inclusions in a para-aortic lymph node and in the serosa of pelvic organs. Changes in the müllerian-derived epithelium appear to be a common denominator of these unusual lesions in this young girl. A primary growth disturbance of the cells of the müllerian system, which was conditioned during embryonic development and manifested itself later in life in response to appropriate stimuli associated with menarche, is postulated as the underlying abnormality.

Adenocarcinoma↗
PubMed1982

Intragenic complementation by the nifJ-coded protein of Klebsiella pneumoniae.

A single mutation, nifC1005 (Jin et al. Sci. Sin. 23:108-118, 1980), located between nifH and nifJ in the nif cluster of Klebsiella pneumoniae, genetically complemented mutations in each of the 17 known nif genes. This suggested that the mutation is located in a new nif gene. We showed by complementation analyses that only 3 of 12 nifJ mutations tested were complemented by nifC1005. Nitrogenase activity in cell extracts of the mutant with nifC1005 as well as NifJ- mutants was stimulated by the addition of the iron-molybdenum cofactor or nitrogenase component I. The molecular weight of the native NifJ protein is approximately 257,000--a dimer of identical subunits. Some nifC-/nifJ- or nifJ-/nifJ- merodiploids produced active but unstable nifJ proteins. Fine-structure mapping placed the nifC1005 allele within the nifJ gene bounded on both sides by well-characterized nifJ mutations. This indicates that the nifC1005 does not define a separate gene from nifJ. The data are consistent with the occurrence of intragenic complementation between two defective nifJ polypeptides. This explains the isolated examples of genetic complementation between the nifC1005 mutation and certain nifJ mutations.

Bacterial Proteins↗
PubMed1981

Lymphomatoid granulomatosis-like lesions in a child with leukemia in remission.

This case report describes an eight year old leukemic child who was in remission for four and one-half years and showed hypogammaglobulinemia and deficient leukocyte chemotaxis and migration. She developed pulmonary lesions with laryngeal and tracheobronchial disease and died from pulmonary hemorrhage. The lesions found at autopsy were lymphomatoid granulomatosis-like, but were atypical in their anatomic distribution, behavior, and histologic features.

Child, Preschool↗
PubMed1980

A study of the cellularity and ultrastructure of congenital mesoblastic nephroma.

This study reported 10 cases of congenital mesoblastic nephroma (CMN) from Children's Hospital of Pittsburgh: five were the typical fibromatous lesion, two were the cellular variant, and three had both components. Six cases occurred in infants less than one week of age. The degree of cellularity had no correlation with patient or tumor size. Three- to 10-year follow-ups of nine patients showed neither local recurrence nor metastasis. One infant died of generalized bleeding post nephrectomy. Ultrastructural study of seven cases showed mesenchymal cells with varying degrees of fibroblastic and/or myofibroblastic differentiation.

Culture Techniques↗