Biomedical subjects

S Jin

Publications and source records attributed to S Jin.

At least 145 records · Page 8Linked to original sources

PubMed1998

Formation of postsynaptic-like membranes during differentiation of embryonic stem cells in vitro.

To analyze the formation of neuromuscular junctions, mouse pluripotent embryonic stem (ES) cells were differentiated via embryoid bodies into skeletal muscle and neuronal cells. The developmentally controlled expression of skeletal muscle-specific genes coding for myf5, myogenin, myoD and myf6, alpha 1 subunit of the L-type calcium channel, cell adhesion molecule M-cadherin, and neuron-specific genes encoding the 68-, 160-, and 200-kDa neurofilament proteins, synaptic vesicle protein synaptophysin, brain-specific proteoglycan neurocan, and microtubule-associated protein tau was demonstrated by RT-PCR analysis. In addition, genes specifically expressed at neuromuscular junctions, the gamma- and epsilon-subunits of the nicotinic acetylcholine receptor (AChR) and the extracellular matrix protein S-laminin, were found. At the terminal differentiation stage characterized by the formation of multinucleated spontaneously contracting myotubes, the myogenic regulatory gene myf6 and the AChR epsilon-subunit gene, both specifically expressed in mature adult skeletal muscle, were found to be coexpressed. Only the terminally differentiated myotubes showed a clustering of nicotinic acetylcholine receptors (AChR) and a colocalization with agrin and synaptophysin. The formation of AChRs was also demonstrated on a functional level by using the patch clamp technique. Taken together, our results showed that during ES cell differentiation in vitro neuron- and muscle-specific genes are expressed in a developmentally controlled manner, resulting in the formation of postsynaptic-like membranes. Thus, the embryonic stem cell differentiation model will be helpful for studying cellular interactions at neuromuscular junctions by "loss of function" analysis in vitro.

Agrin↗

PubMed1998

The effects of physical and psychological well-being on suicidal ideation.

This study examines a theoretical model of suicidal ideation with physical symptoms (physical well-being) and self-esteem (psychological well-being) as two competitive predicting variables. The national sample of 1,433 cases was drawn in the People's Republic of China in March 1 995. Results indicate that both suicidal ideation and attempt rates are lower in the Chinese population than in other populations studied, and as found in the West, Chinese women are more likely to think about and to attempt suicide than Chinese men. LISREL analysis of the model shows that psychological well-being (self-esteem) is a much stronger predictor of suicidal ideation than physical well-being (physical symptoms), especially when depression is introduced as an intervening variable in the model.

Adult↗

PubMed1998

Synthesis and surface characterization of functionalized polylactide copolymer microparticles.

Microparticles of poly(lactide) (PLac) and its copolymers with the amino acids, serine (P(Lac-Ser)), and aspartic acid (P(Lac-Asp)), respectively, were synthesized using the solvent evaporation microemulsion technique. Poly(vinyl alcohol) (PVA) was added as a non-ionic surfactant to stabilize the particles. The particle sizes are in the range of 200 nm. The surface of the particles was characterized by FTIR transmission spectroscopy under evacuation at room temperature and at 200 degrees C. Hydroxy groups originating from PVA exist on the surfaces of the particles and they were observed at 3506 cm(-1). Free hydroxy groups originating from the serine residue pendant to the copolymer P(Lac-Ser) backbone were observed at 3396 cm(-1). Also, free carboxylic acid groups pendant to the copolymer P(Lac-Asp) backbone, originating from the aspartic acid residue, were observed at 3387 cm(-1). The appearance of the free hydroxy or carboxylic acid groups in the IR spectra also showed that these hydrophilic functional groups moved to the surface of the particles in the process of microemulsion.

Biocompatible Materials↗

PubMed1998

Differential etoposide sensitivity of cells deficient in the Ku and DNA-PKcs components of the DNA-dependent protein kinase.

Etoposides block cell division by interfering with the action of topoisomerase II, leaving enzyme-DNA double-strand breaks. We found that certain components of the trimeric DNA-dependent protein kinase influence cell survival following etoposide damage. Interestingly, either Ku70- or Ku80-deficient cell lines, but not mutant cell lines of the DNA-PK catalytic sub-unit (DNA-PKcs), were found to be hypersensitive to the effects of etoposide VP16. Ku70- and Ku80-deficient cells can be complemented to an etoposide resistant phenotype by introducing wildtype Ku70 or Ku80 cDNAs. Mutational analysis of introduced Ku70 cDNAs into murine embryonic stem cells deleted for Ku70 (-/-) showed that mutants where heterodimerization and DNA binding functions of Ku were disrupted, also blocked the restoration of etoposide resistance. In contrast with the differential etoposide sensitivity of DNA-PK mutants, both Ku- and DNA-PKcs-deficient cell lines showed G2 ionizing radiation-induced delays, a cell cycle phase where topoisomerase II function is critical. Thus, the topoisomerase II cleaved complexes may be an example of DNA lesions requiring the Ku heterodimer, but not DNA-PK for DNA repair.

Animals↗

PubMed1998

Insertion mutation of the form I cbbL gene encoding ribulose bisphosphate carboxylase/oxygenase (RuBisCO) in Thiobacillus neapolitanus results in expression of form II RuBisCO, loss of carboxysomes, and an increased CO2 requirement for growth.

It has been previously established that Thiobacillus neapolitanus fixes CO2 by using a form I ribulose bisphosphate carboxylase/oxygenase (RuBisCO), that much of the enzyme is sequestered into carboxysomes, and that the genes for the enzyme, cbbL and cbbS, are part of a putative carboxysome operon. In the present study, cbbL and cbbS were cloned and sequenced. Analysis of RNA showed that cbbL and cbbS are cotranscribed on a message approximately 2,000 nucleotides in size. The insertion of a kanamycin resistance cartridge into cbbL resulted in a premature termination of transcription; a polar mutant was generated. The mutant is able to fix CO2, but requires a CO2 supplement for growth. Separation of cellular proteins from both the wild type and the mutant on sucrose gradients and subsequent analysis of the RuBisCO activity in the collected fractions showed that the mutant assimilates CO2 by using a form II RuBisCO. This was confirmed by immunoblot analysis using antibodies raised against form I and form II RuBisCOs. The mutant does not possess carboxysomes. Smaller, empty inclusions are present, but biochemical analysis indicates that if they are carboxysome related, they are not functional, i.e., do not contain RuBisCO. Northern analysis showed that some of the shell components of the carboxysome are produced, which may explain the presence of these inclusions in the mutant.

Bacterial Proteins↗

PubMed1998

A novel serine/threonine protein kinase homologue of Pseudomonas aeruginosa is specifically inducible within the host infection site and is required for full virulence in neutropenic mice.

A genetic locus of Pseudomonas aeruginosa was identified that is highly and specifically inducible during infection of neutropenic mice. This locus, ppkA, encodes a protein that is highly homologous to eukaryote-type serine/threonine protein kinases. A ppkA null mutant strain shows reduced virulence in neutropenic mice compared to the wild type. Overexpression of the PpkA protein greatly inhibited the growth of Escherichia coli or P. aeruginosa. However, a single amino acid change at the catalytic site of the kinase domain eliminated the toxic effect of PpkA on bacterial cells, suggesting that the kinase domain of PpkA is functional within bacterial cells.

Amino Acid Sequence↗

PubMed1998

Detection and characterization of novel rotavirus strains in the United States.

We recently established a rotavirus strain surveillance system in the United States to monitor the prevalent G serotypes before and after the anticipated implementation of a vaccination program against rotavirus and to identify the emergence of uncommon strains. In this study, we examined 348 rotavirus strains obtained in 1996 to 1997 from children with diarrhea in 10 U.S. cities. Strains were characterized for P and G types, subgroups, and electropherotypes by using a combination of monoclonal antibody immunoassay, reverse transcription-PCR, and hybridization. The four strains most commonly found worldwide comprised 83% of the isolates (P[8]G1, 66.4%; P[4]G2, 8.3%; P[8]G3, 6.9%; P[8]G4, 1.4%), but 9.2% were unusual strains (P[6]G9, 5.5%; P[8]G9, 1.7%; P[6]G1, 1.4%; and P[4]G1 and P[8]G2, 0. 3% each). Strains not typeable for P or G type accounted for 5.5% of the total, while 2.3% of the strains had more than one G type (mixed infections). All P[6]G9 strains tested had short electropherotypes and subgroup I specificity and were detected in 4 of 10 cities, while P[8]G9 strains had long electropherotypes and subgroup II VP6 antigens. Both sequence analysis of the VP7 open reading frame (about 94 to 95% amino acid identity with the VP7 gene of G9 prototype strain WI61) and binding to a G9-specific monoclonal antibody strongly suggest that U.S. G9 strains belong to serotype G9. The high detection rates of unusual rotaviruses with G9 (7.2%) or P[6] (6.9%) specificity in multiple U.S. cities suggest the emergence of new strains or inadequate diagnosis in the past. The epidemiologic importance of these strains remains to be determined.

Antibodies, Monoclonal↗

PubMed1998

Update on Pneumocystis carinii f. sp. hominis typing based on nucleotide sequence variations in internal transcribed spacer regions of rRNA genes.

Pneumocystis carinii f. sp. hominis isolates from 207 clinical specimens from nine countries were typed based on nucleotide sequence variations in the internal transcribed spacer regions I and II (ITS1 and ITS2, respectively) of rRNA genes. The number of ITS1 nucleotides has been revised from the previously reported 157 bp to 161 bp. Likewise, the number of ITS2 nucleotides has been changed from 177 to 192 bp. The number of ITS1 sequence types has increased from 2 to 15, and that of ITS2 has increased from 3 to 14. The 15 ITS1 sequence types are designated types A through O, and the 14 ITS2 types are named types a through n. A total of 59 types of P. carinii f. sp. hominis were found in this study.

Base Sequence↗

PubMed1998

Inactivation of DNA-dependent protein kinase by protein kinase Cdelta: implications for apoptosis.

Protein kinase Cdelta (PKCdelta) is proteolytically cleaved and activated at the onset of apoptosis induced by DNA-damaging agents, tumor necrosis factor, and anti-Fas antibody. A role for PKCdelta in apoptosis is supported by the finding that overexpression of the catalytic fragment of PKCdelta (PKCdelta CF) in cells is associated with the appearance of certain characteristics of apoptosis. However, the functional relationship between PKCdelta cleavage and induction of apoptosis is unknown. The present studies demonstrate that PKCdelta associates constitutively with the DNA-dependent protein kinase catalytic subunit (DNA-PKcs). The results show that PKCdelta CF phosphorylates DNA-PKcs in vitro. Interaction of DNA-PKcs with PKCdelta CF inhibits the function of DNA-PKcs to form complexes with DNA and to phosphorylate its downstream target, p53. The results also demonstrate that cells deficient in DNA-PK are resistant to apoptosis induced by overexpressing PKCdelta CF. These findings support the hypothesis that functional interactions between PKCdelta and DNA-PK contribute to DNA damage-induced apoptosis.

Apoptosis↗

PubMed1998

Transcriptional regulation of the MDR1 gene by histone acetyltransferase and deacetylase is mediated by NF-Y.

Recent studies have shown that the histone-modifying enzymes histone acetyltransferase (HAT) and histone deacetylase (HDAC) are involved in transcriptional activation and repression, respectively. However, little is known about the endogenous genes that are regulated by these enzymes or how specificity is achieved. In the present report, we demonstrate that HAT and HDAC activities modulate transcription of the P-glycoprotein-encoding gene, MDR1. Incubation of human colon carcinoma SW620 cells in 100-ng/ml trichostatin A (TSA), a specific HDAC inhibitor, increased the steady-state level of MDR1 mRNA 20-fold. Furthermore, TSA treatment of cells transfected with a wild-type MDR1 promoter/luciferase construct resulted in a 10- to 15-fold induction of promoter activity. Deletion and point mutation analysis determined that an inverted CCAAT box was essential for this activation. Consistent with this observation, overexpression of p300/CREB binding protein-associated factor (P/CAF), a transcriptional coactivator with intrinsic HAT activity, activated the wild-type MDR1 promoter but not a promoter containing a mutation in the CCAAT box; deletion of the P/CAF HAT domain abolished activation. Gel shift and supershift analyses identified NF-Y as the CCAAT-box binding protein in these cells, and cotransfection of a dominant negative NF-Y expression vector decreased the activation of the MDR1 promoter by TSA. Moreover, NF-YA and P/CAF were shown to interact in vitro. This is the first report of a natural promoter that is modulated by HAT and HDAC activities in which the transcription factor mediating this regulation has been identified.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1998

Gene cloning and amino acid sequence analysis of triose-phosphate isomerase of Schistosoma japonicum Chinese strain.

A pair of primers was synthesized according to the DNA sequence of Schistosoma japonicum Philippine strain, and the mRNA of adult worms of S. japonicum Chinese strain was prepared. The gene of triose-phosphate isomerase of S. japonicum Chinese strain (SjC TPI) was successfully cloned from the mRNA through reverse transcription polymerase chain reaction (RT-PCR) technic with the primers. The DNA sequence of the gene showed that the open reading frame of encoding SjC TPI DNA includes 759bp, which has 84% homology to Sm TPI, 99.7% homology to SjP TPI. The analysis of deduced amino acid sequence of SjC TPI indicates that SjC TPI is 84.9% (214/252) identical with Sm TPI and 99.2% (250/252) with SjP TPI. The peptide-structure analysis presents 7 extra-surface, hydrophilic regions in the molecule of SjC TPI, the molecular weight of SjC TPI is 27,619. The isoelectric point is 7.38.

Amino Acid Sequence↗

PubMed1998

[The effect of tangential excision on the local IL-8 release and wound inflammatory response in deep-partial thickness burn].

OBJECTIVE: The aim of this study is to investigate the effect of tangential excision on the local IL-8 release and wound inflammatory response. METHODS: The tissue specimens, which were taken from 7 patients with deep partial thickness burn before and after operation, were both cultured and histopathologically examined. The level of IL-8 in the culture medium was assayed, meanwhile local inflammatory response of tissue samples was evaluated. RESULTS: The result showed that the level of IL-8 is much lower in the postoperation wounds, while in the non-operation wounds the neutrophil infiltration was marked, with enlargement in necrotic area and disappearance of skin appendages. CONCLUSION: The findings suggested that tangential excision could reduce the local production of IL-8 and decrease local inflammatory response, which is helpful to prevent the progressive necrosis of burn wound.

Adult↗

PubMed1998

[Impact of maternal income on the nutrients intake of preschool children--a case study in 8 provinces of China].

The data of this study are based on the project "China Health and Nutrition Survey" carried out in 8 provinces of China from 1989 to 1998 in collaboration with the University of North Carolina at Chapel Hill, USA. Totally, 1180 and 916 mother-child pairs aged 2-6 were investigated in 1991 and 1993 respectively. Descriptive and stratified analysis is applied to investigate the impact of maternal income on the nutrients intake of children. It is found that the nutrients intake of children in higher maternal income group is greater than that in lower maternal income group. After adjusting for family income, the results show that the more contribution of the mother's income to the family, the more nutrients intake of their children, especially in lower income families. It is illustrated that the income of mother may be more important for children's dietary status than that of other members of the family.

Animals↗

PubMed1998

[Telomerase activity in human primary endometrial carcinoma].

OBJECTIVE: To investigate the possible relationship between telomerase expression and progression of endometrial carcinoma. METHODS: Thirty-four primary endometrial carcinoma and 6 normal endometrial tissue specimens were examined by means of telomeric repeat amplification protocol (TRAP) assay for telomerase activity. RESULTS: Of 34 endometrial cancer specimens, 28 (82.4%) showed telomerase activity, whereas 1 of 6 (16.7%) benign endometrial tissues exhibited telomerase activity. CONCLUSION: Telomerase expression might contribute to the progression of endometrial carcinoma and could be used as its tumor marker.

Adenocarcinoma↗

PubMed1998

[Telomerase activity in liver cancer and the adjacent tissue].

OBJECTIVE: To investigate the possibility of using telomerase as a tumor marker for human primary hepatocellular carcinomas (HCC). METHODS: Human liver specimens, comprising 33 HCC and adjacent peritumoral tissues, 4 hepatic metastases and the adjacent peritumoral tissues, 6 benign liver lesions and 6 normal liver tissues, were examined for telomerase activity by TRAP assay based on PCR. RESULTS: Thirty of 33 HCC and 9 of 33 adjacent tissue specimens were positive for telomerase activity with a positive rate of 90.9% and 27.3%, respectively. Four hepatic metastatic cancer and 2 adjacent tissues were positive. Telomerase activity was negative in 6 nomal liver tissues and 5 of 6 benign liver lesions. There was no correlation between the clinical stage of HCC and their telomerase activity. CONCLUSION: Positive telomerase activity occurs in the majority of HCC examined. It can be used as a tumor marker in the diagnosis of HCC.

Biomarkers, Tumor↗

PubMed1998

[Study of telomerase activity in colorectal carcinomas].

OBJECTIVE: To investigate the telomerase activity in human colorectal carcinoma and tumor-adjacent tissue and to investigate the possibility of telomerase as tumor biological marker. METHODS: A total of 60 human colorectal tissue specimens, comprising 37 carcinomas, 3 benign lesions and 20 tumor-adjacent tissue specimens were examined for telomerase activity by telomeric repeat amplification protocol(TRAP) assay. RESULTS: No telomerase activity in 20 tumor-adjacent tissues and 3 benign lesions was detected. However, of 37 colorectal carcinoma specimens, 35 were positive for telomerase activity with a 94.6% positive rate. CONCLUSION: The data suggest that telomerase is a tumor specific gene marker, and may play an important role in early diagnosis and treatment of colorectal carcinomas.

Biomarkers, Tumor↗

PubMed1998

[Deletion of MTS1/p16 gene in human esophageal carcinoma].

OBJECTIVE: To investigate the alteration of MTS1/p16 gene in human esophageal carcinoma. METHODS: A total of 60 human esophageal tissue specimens, comprising 30 squamous-cell carcinomas and 30 tumor-adjacent tissue specimens, were examined for homozygous deletion of p16 gene by using Southern blot hybridization and PCR method. RESULTS: The results showed that no deletions were detected in 30 tumor-adjacent tissue samples. However, of 30 esophageal carcinoma specimens, 7 were found negative for p16 gene in Southern blot assay, and the deletion of the p16 gene in 5 samples were confirmed by PCR with a 16.7% p16 gene deletion rate. CONCLUSION: These data suggest that MTS1/p16 gene alterations may play a role in the progression of human esophageal carcinoma.

Blotting, Southern↗

PubMed1998

[Evaluation of penicilloyl proteins of allergic impurity in gene engineering drugs].

It is well known that penicillins are necessary for prevention of contamination during cell culture or fermentation in the production of gene engineering drugs. As penicillins are easily combined with proteins forming allergic impurities, the benzyl penicilloyl proteins in aqueous solution, an evaluation system should be established for control of the gene engineering drugs. An enzyme linked immunosorbent assay (ELISA) with high specificity and high sensitivity in vitro, by which the conjugated penicillins of 0.3 ppm in a sample could be detected and a passive cutaneous anaphylaxis (PCA) test, a classical method for evaluation of allergic reaction in vivo are integral parts of this system. Some domestic gene engineering drugs such as erythropoietin (EPO), G-CSF, GM-CSF and 125SerIL-2 are evaluated with this system. No matter whether the expression products was produced in secretion manner or in inclusion body, it was possible that some residues of allergic impurities may remain in the finished products if an unsuitable process of isolation and purification was used. The maximum absolute content of the conjugated penicillins in a sample was up to about one per thousand.

Animals↗