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L Ji

Publications and source records attributed to L Ji.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Sulfonylurea receptor gene polymorphism is associated with non-insulin dependent diabetes mellitus in Chinese population].

OBJECTIVE: To test the role of Sulfonylurea receptor gene(SUR) in the pathogenesis of NIDDM in Chinese population. METHODS: We studied the polymorphisms of the SUR gene in intron 24 and exon 22 by polymerase chain reaction(PCR) and appropriate restriction enzyme (PCR-RFLP) in 86 NIDDM patients with at least two first degree diabetic relatives and 148 normal control subjects. RESULTS: The frequency of "c" allele of intron 24 in NIDDM patients was significantly increased as compared with that in the control subjects (68.02% vs. 55.41, P = 0.007), and the frequency of the "cc" genotype of intron 24 in the NIDDM group was also significantly higher than that in the control group (41.86% vs. 27.7%, P = 0.013, OR = 4.39, CI: 1.52-12.66). The polymorphism of exon 22 described in the Caucasian population was not detected. CONCLUSION: The association of the polymorphism of SUR gene with NIDDM in different races suggests that the SUR gene or nearby gene may play an important role in the genetic susceptibility of NIDDM.

ATP-Binding Cassette Transporters↗
PubMed1997

A packaging system for SV40 vectors without viral coding sequences.

SV40 vectors have been used as expression vectors for mammalian cells since the early 1980s. More recently, they have been used as gene transfer vectors in mice and in human peripheral blood cells. Here we described a system for packaging SV40 vectors without viral coding sequences. Recombinant adenovirus-expressing SV40 capsids can effectively package plasmids that contain the SV40 replication origin. The final yield of infectious SV40 vector is about 3 x 10(5), with a SV40 to adenoviral vector ratio of about 1000:1. Helper adenoviruses can be effectively heat-inactivated with no effect on the infectivity of SV40 vectors.

Adenoviridae↗
PubMed1997

Developmentally regulated O-acetylated sialoglycans in the central nervous system revealed by a new monoclonal antibody 493D4 recognizing a wide range of O-acetylated glycoconjugates.

We have previously detected an alkali-labile and developmentally regulated antigen in rat embryonic cerebral cortex, which may be 9-O-acetylsialylated GT3 ganglioside (Hirabayashi Y, Hirota M, Suzuki Y, Matsumoto M, Obata K, Ando S (1989) Neurosci Lett 106:193-98). In this study we established a mouse monoclonal antibody, 493D4, that recognizes 9-O-acetyl GT3 ganglioside, but not non-O-acetyl gangliosides. This antibody also reacted with 9-O-acetyl GD3 to a much lesser extent. By using this antibody, we found that O-acetyl GT3 as well as O-acetyl GD3 were expressed strongly in fetal murine cerebral cortex and decreased to an undetectable level after birth. With the assistance of TLC-immunostaining using 493D4 together with Q-Sepharose column chromatography, O-acetyl gangliosides of bovine brain were purified and the structural analysis showed the presence of O-acetyl GD3, O-acetyl LD1, O-acetyl GD2 and O-acetyl GD1b in the adult brain as extremely minor components. Interestingly, the antibody 493D4 could detect O-acetyl sialoglycoproteins in rat brain tissues. One of the major immunoreactive proteins was shown to be synaptophysin, an integral membrane protein specifically present in synaptic vesicles. This monoclonal antibody was therefore useful for sensitive detection of both O-acetylated gangliosides and glycoproteins with O-acetylated sialic acids.

Acetylation↗
PubMed1997

Calmodulin-dependent protein kinase II mediates signal transduction in apoptosis.

The present studies describe a new function for calmodulin-dependent protein kinase II (CaM-KII) in signal transduction leading to apoptosis. Both tumor necrosis factor alpha (TNF) and UV light rapidly stimulated Ca2+-independent activity of CaM-KII in the monocytic leukemia, U937. Two mechanistically different inhibitors of CaM-KII blocked activation of CaM-KII and prevented DNA fragmentation and death. Activation of CaM-KII during apoptosis and inhibition of DNA fragmentation by the two CaM-KII inhibitors were reproduced in several other lines including KGla, HL-60, and YAC-1. However, K562, which is relatively resistant to apoptosis induced by either TNF or UV light, did not activate CaM-KII in response to these stimuli. A variant derived from U937 that is resistant to TNF- or UV light-induced apoptosis also lacked a CaM-KII response. Activation of Cam-KII was blocked by two protease inhibitors, VAD-fmk and TPCK, but not by other inhibitors of serine proteases. Both inhibitors of CaM-KII and the protease inhibitors blocked activation of AP24, a serine protease originally isolated from apoptotic cells that induces DNA fragmentation in nuclei. Our evidence supports a model in which proteolytic activity functions upstream of CaM-KII. This kinase then leads to activation of AP24, which transmits signals to the nucleus to initiate DNA fragmentation.

Apoptosis↗
PubMed1997

DNA measurement of overlapping cell nuclei in thick tissue sections.

The paper describes an improved image analysis procedure for measuring the DNA content of cell nuclei in thick sections of liver tissue by absorption densitometry. Whereas previous methods only permitted the analysis of isolated nuclei, the new technique enables both isolated and overlapping nuclei to be measured. A 3D segmentation procedure determines whether each object is an isolated nucleus or a pair of overlapping nuclei; in the latter case the combined optical density is redistributed to the individual nuclei. A selection procedure ensures that only complete nuclei are measured. The method has been tested on specially-prepared Feulgen-stained 20micro sections of normal liver tissue. The overall distribution of the nuclear DNA measurements shows well-defined diploid and tetraploid peaks, with coefficient of variations of less than 10%. Similar distributions were obtained from both the isolated nuclei and overlapped nuclei sub-populations.

Cell Nucleus↗
PubMed1997

New susceptibility locus for NIDDM is localized to human chromosome 20q.

To test the hypothesis that a gene (or genes) in the "MODY1 region" of the long arm of chromosome 20 contributes to the development of NIDDM, we conducted linkage studies in 29 extended Caucasian families in which many members were affected with NIDDM. A total of 498 individuals, including 159 NIDDM patients with an average age at diagnosis of 47 years, were genotyped for eight highly polymorphic microsatellite markers spanning a 31-cM region on chromosome 20q12-13.1. Using affected sib-pair analysis, we obtained evidence suggesting linkage between NIDDM and markers D20S119, D20S178, and D20S197 (allele sharing identical-by-descent [IBD], 0.56 for all three; P = 0.005, P = 0.009, and P = 0.004, respectively). Multipoint nonparametric linkage (NPL) analysis also showed evidence for linkage of NIDDM with the same three markers. The evidence for linkage was much stronger (allele sharing IBD by affected sibpairs, 0.64 [P < 0.0001]; maximum NPL score, 3.3 [P = 0.009]) in the 14 families whose average age at diagnosis of NIDDM was above the median (47 years) for all families. In these 14 families, one particular allele of the microsatellite D20S197 was transmitted from heterozygous parents to NIDDM offspring more frequently than expected (P < 0.01). This indicates that the marker allele and the disease allele are in linkage disequilibrium, implying that they are in close proximity. Consequently, the recently identified MODY1 gene (hepatocyte nuclear factor 4) is an unlikely candidate gene for NIDDM in our families, since it is located about 8 cM centromeric of D20S197. In conclusion, we have identified a new region on chromosome 20q that contains one or more NIDDM genes distinct from the recently identified MODY1 gene.

Adult↗
PubMed1997

[GC-MS analysis of constituents of essential oils from stems of Ephedra sinica Stapf, E. intermedia Schrenk et C.A. Mey. and E. equisetina Bge].

The essential oils from the dried stems of Ephedra sinica, E. intermedia and E. equisetina were analyzed by GC-MS qualitatively and GC quantitatively. One hundred and twenty-seven constituents were identified, l-alpha-terpineol (31.64%) in E. sinica, 1,4-cineole (12.80%) in E. intermedia and hexadecanoic acid (26.22%) in E. equisetina being the main constituents.

Cycadopsida↗
PubMed1997

[Pharmacognostical identification of Anoectochilus roxburghii].

This paper reported the pharmacognostical identification on characters, microscopic characteristics and TLC of the Anoectochilus roxburghii (Wall.) Lindl., and compared with different resouce samples. The results may provide reference for its identification.

Chromatography, Thin Layer↗
PubMed1997

[Detection of hepatitis A virus in environmental samples by coupled reverse transcription and polymerase chain reaction].

A direct reverse transcription coupled with polymerase chain reaction (RT-PCR) was used to detect HAV-seeded sea water, coastal sediment and Arca subcrenata, HAV strain treated by different kind of disinfection, and naturally occurring HAV in Arca subcrenata. The results showed that HAV could be detected in HAV-seeded sea water, coastal sediment and Arca subcrenata. HAV could also be detected in HAV strain disinfected by phenol, suggesting that inactive HAV could also show positive PCR. Only Arca subcrenata collected from Shanghai in 1988 showed positive result by RCR, but negative by immunofluorescence at the same time. This result demonstrated that HAV was not infectious owing to long time storage. The author's method has the advantage of involving fewer manipulations.

China↗
PubMed1996

CREB proteins function as positive regulators of the translocated bcl-2 allele in t(14;18) lymphomas.

The translocated and normal bcl-2 alleles in the DHL-4 cell line with the t(14;18) translocation were separated by pulsed field electrophoresis. An in vivo footprint over a cAMP response element (CRE) in the bcl-2 5'-flanking sequence was identified on the translocated allele. Electrophoretic mobility shift assays with the bcl-2 CRE demonstrated complexes with mobilities identical to those with a consensus CRE. UV cross-linking experiments revealed that proteins with molecular masses of 34, 43, and 67 kDa bound to the bcl-2 CRE site. Electrophoretic mobility shift assay with an antibody specific to the phosphorylated cAMP response-binding protein (CREB) demonstrated that phosphorylated CREB was present in DHL-4 cells. Treatment with phorbol 12-myristate 13-acetate (PMA) led to an increase in both the amount of phosphorylated CREB and the bcl-2 promoter activity. The response to PMA was dependent on an intact CRE site. The activity of the bcl-2 promoter was increased 20-fold in a construct with the immunoglobulin heavy chain enhancers, and mutation of the CRE site abolished most of the induction. The addition of PMA increased the activity of the bcl-2-immunoglobulin enhancer construct by 3.5-fold. Access to the CRE site is blocked in the silent normal bcl-2 allele, while CREB proteins bind to the site on the translocated allele. We conclude that the CRE site functions as a positive regulatory site for the translocated bcl-2 allele in t(14;18) lymphomas.

Alleles↗
PubMed1996

[Quality standard of tanre kesou granules].

A TLC method was used in the identification of the following chemical consitituents of medicinal herbs in Tanre Kesou Granules: Radix Scutellariae, Bulbus Fritillariae Thunbergii, Pericarpium Citri Reticulatae and Fructus Aurantii Immaturus. The sample was purified through acidification with hydrochloric acid and extraction with ethyl acetatethe. The contents of baicalin in the preparation and Radix Scutellariae were determined by means of HPLC and TLC-densitometry. These methods fit for quality control of the preparation containing baicalin.

Anti-Infective Agents↗
PubMed1996

Characteristics of harringtonine-resistant human leukemia HL60 cell.

AIM: To study the mechanisms of the resistance to harringtonine (Har) in the HL60 cells. METHODS: Growth inhibition, karyotype analysis, flow cytometry, Western blotting and polymerase chain reaction. RESULTS: The Har-resistant HL60 cell line, named HR20, showed cross resistance to homoharringtonine, doxorubicin, daunorubicin, vincristine, and colchicine. The growth doubling time and the cell numbers in G1 phase were increased. The accumulation of cellular daunorubicin in the resistant cells was obviously reduced, but distinctly increased by tetrandrine and verapamil. The numbers of telocentromeric chromosome increased and the chromosomal aberration more occured in the resistant cells. The resistant cells overexpressed multidrug resistant mdr-1 gene and P-glycoprotein 150 kDa. CONCLUSION: The Har-resistant HL60 cell strain belonged to a multidrug resistance strain, overexpressing mdr-1 gene and P-glycoprotein.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1995

Tumor necrosis factor alpha increases tyrosine phosphorylation of a 23-kDa nuclear protein in U937 cells through ceramide signaling pathway.

In many tumor cell lines, tumor necrosis factor alpha (TNF alpha) causes profound alterations in nucleus including chromatin condensation and DNA fragmentation. However the mechanism is largely unknown. Here we demonstrate that TNF alpha treatment of U937 cells increased tyrosine phosphorylation of a 23-kDa nuclear protein (P23) maximally by 13-fold, which occurred after 2.5 h treatment concomitantly with occurrence of DNA fragmentation. Tyrosine kinase inhibitor, herbimycin A, inhibited either tyrosine phosphorylation of P23 or DNA fragmentation, suggesting that the P23 phosphoprotein may be involved in the TNF alpha-induced changes in nucleus. Increase of intracellular Cer level by hydrolysis of cell surface SM with bacterial sphingomyelinase or addition of either C2-Cer or natural Cer also resulted in increase of P23 tyrosine phosphorylation, which was detectable at 1.5 h treatment and reached maximum after 2 h treatment, indicating that P23 phosphoprotein may be a downstream effector of Cer signaling pathway. Our data provide further evidence that Cer signaling pathway may mediate signal transduction of TNF alpha.

Benzoquinones↗
PubMed1995

Inhibition of tumor necrosis factor alpha- and ceramide-induced internucleosomal DNA fragmentation by herbimycin A in U937 cells.

In many tumor cell lines, tumor necrosis factor alpha (TNF alpha) causes apoptosis with characteristic internucleosomal DNA fragmentation. However, the mechanism is largely unknown. Here we examined the involvement of protein tyrosine kinases by using their inhibitors. Among various tyrosine kinase inhibitors tested, only herbimycin A was found to inhibit internucleosomal DNA fragmentation but not apoptotic morphological changes and cell death induced by TNF alpha in U937 cells. Herbimycin A was able to block DNA fragmentation when it was added to the cell culture as late as 1.5 h after TNF alpha treatment. These results demonstrate that herbimycin A selectively inhibits a later event involved in the process of apoptois that results in internucleosomal DNA fragmentation. Sphingomyelinase and ceramide (Cer) induced internucleosomal DNA fragmentation was also inhibited by herbimycin A, supporting the hypothesis that Cer may be a novel second messenger mediating the cytotoxic effect of TNF alpha.

Apoptosis↗
PubMed1995

The transcription factor, Nm23H2, binds to and activates the translocated c-myc allele in Burkitt's lymphoma.

We have identified an in vivo footprint over the PuF site on the translocated c-myc allele in Burkitt's lymphoma cells. The PuF site on the silent normal c-myc allele was unoccupied. We demonstrated by electrophoretic mobility shift assay, electrophoretic mobility shift assay with antibody, UV cross-linking followed by SDS-gel electrophoresis, and Western analysis that Nm23H2 in B cell nuclear extracts bound to the c-myc PuF site. Transfection experiments with c-myc promoter constructs in both DHL-9 and Raji cells revealed that the PuF site functioned as a positive regulatory element in B cells with a drop in activity with mutation of this site. Access to this site is blocked in the normal silent c-myc allele; these data suggest that the Nm23H2 protein is involved in deregulation of the translocated c-myc allele in Burkitt's lymphoma cells.

Alleles↗