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C C Li

Publications and source records attributed to C C Li.

At least 19 recordsLinked to original sources
PubMed1996

Multiple transcription factors are required for activation of human interleukin 9 gene in T cells.

The genetic elements and regulatory mechanisms responsible for human interleukin 9 (IL-9) gene expression in a human T cell leukemia virus type I-transformed human T cell line, C5MJ2, were investigated. We demonstrated that IL-9 gene expression is controlled, at least in part, by transcriptional activation. Transient expression of the luciferase reporter gene linked to serially deleted sequences of the 5'-flanking region of the IL-9 gene has revealed several positive and negative regulatory elements involved in the basal and inducible expression of the IL-9 gene in C5MJ2 cells. An AP-1 site at -146 to -140 was shown to be involved in the expression of the IL-9 gene. A proximal region between -46 and -80 was identified as the minimum sequence for the basal and inducible expression of the IL-9 gene in C5MJ2 cells. Within this region, an NF-kappaB site at -59 to -50 and its adjacent 20-base pair upstream sequence were demonstrated to play a critical role for the IL-9 promoter activity. DNA-protein binding studies indicated that NF-kappaB, c-Jun, and potentially novel proteins (around 35 kDa) can bind to this important sequence. Mutations at different sites within this proximal promoter region abolished the promoter activity as well as the DNA binding. Taken together, these results suggest that the cooperation of different transcription factors is essential for IL-9 gene expression in T cells.

Base Sequence↗
PubMed1995

DNA profile match probabilities in a subdivided population: when can subdivision be ignored?

Li and Chakravarti [Li, C.C. & Chakravarti, A. (1994) Hum. Hered. 44, 100-109] compared the probability (MO) of a random match between the two DNA profiles of a pair of individuals drawn from a random-mating population to the probability (MF) of the match between a pair of random individuals drawn from a subdivided population. The level of heterogeneity in this subdivided population is measured by the parameter F, where there is no subdivision when F = 0 and increasing values of F indicate increasing subdivisions. Li and Chakravarti concluded that it is conservative to use the match probability MO, which is derived under the assumption that the two individuals are drawn from a homogeneous random-mating population without subdivision. However, MO may not be always greater than MF, even for biologically reasonable values of F. We explore here those mathematical conditions under which MO is less than MF, and we find that MO is not conservative mainly when there is an allele with a much higher frequency than all the other alleles. When empirical data for both variable number of tandem repeat (VNTR) and short tandem repeat (STR) systems are evaluated, we find that in the majority of cases MO represents a conservative probability of a match, and so the subdivision of human populations may usually be ignored for a random match, although not, of course, for relatives. Loci for which MO is not conservative should be avoided for forensic inference.

Alleles↗
PubMed1995

Inactivation of NF-kappa B inhibitor I kappa B alpha: ubiquitin-dependent proteolysis and its degradation product.

In most cells, the inactive dimeric NF-kappa B complexes are retained in the cytoplasm by binding to a group of inhibitory proteins. I kappa B. In response to extracellular stimuli, I kappa B is rapidly phosphorylated and degraded, thus, liberating the active NF-kappa B. To investigate the mechanisms involved, we have developed a cell-free system to study the degradation of the prototype I kappa B protein, I kappa B alpha. In this in vitro assay, ubiquitin, proteasome-containing S100 fraction and ATP are required for the proteolysis of I kappa B alpha. Both bound and free forms of I kappa B alpha isolated from intact cells can be degraded through this pathway. We also identified polyubiquitinated I kappa B alpha molecules and N-terminal truncated I kappa B alpha degradation product(s) both in vivo and in vitro. We conclude that the inactivation of I kappa B alpha occurs through a series of processes including phosphorylation, ATP-dependent ubiquitin conjugation and proteasome-mediated proteolysis.

Adenosine Triphosphate↗
PubMed1995

Detection of p53 mutations in B cell non-Hodgkin's lymphoma cell lines.

The p53 tumor suppressor gene is frequently mutated within its evolutionarily conserved regions in a number of human cancers. Previous reports demonstrated mutations of this gene in both Burkitt's lymphoma and B cell chronic lymphocytic leukemia. However, dissimilar results were obtained in non-Hodgkin's lymphoma (NHL). In one study, no mutation was detected in 43 NHL tissues. A second study reported p53 mutations in eight (all with advanced stage disease) out of 48 tissues obtained from Japanese NHL patients. Using both immunoblotting and radio-immunoprecipitation, we detected mutant p53 proteins in nine out of 10 B cell lines established from NHL tissues. The mutations were confirmed by reverse transcription polymerase chain reaction-mediated single-strand conformational polymorphism (RT-PCR-SSCP) analysis in eight cell lines. The high frequency of p53 mutation in NHL B cell lines and the relatively low frequency of p53 mutations in fresh lymphoma tissue suggests that p53 gene alteration may play a role in lymphomagenesis and/or disease progression in a subset of B cell lymphomas and that the p53 mutation conveys a proliferative advantage on lymphoma cells that permits their in vitro growth.

B-Lymphocytes↗
PubMed1995

[Protective effects of Angelica sinensis injection on myocardial ischemia/reperfusion injury in rabbits].

The injection of aqueous extract of Angelica sinensis (AS), 50 mg/kg, 30 ml, were administered intravenously at a rate of 0.4 ml/min by an infusion pump 10 min before the left anterior descending coronary artery of rabbit was ligated, the LVP and +/- dp/dtmax of the rabbit heart injured by ischemia/reperfusion in vivo, were significantly higher than those in the control group (N.S. group, P < 0.05-0.01), and the level of malon-dialdehyde (MDA) and the activity of creatine phosphokinase (CPK) in the blood plasma were lower than those in the control group remarkably (P < 0.05-0.01). These results showed that AS exerted obvious protective effects on myocardial dysfunction and myocardial injury induced by ischemia/reperfusion.

Animals↗
PubMed1994

Phosphorylation of NF-KB1-p50 is involved in NF-kappa B activation and stable DNA binding.

We have previously shown that NF-kappa B/Rel family members are physically associated phosphoproteins, and p105 and p50 are hyperphosphorylated after NF-kappa B activation. In this report, we further studied the phosphorylation involved in NF-kappa B activation in Jurkat T cells responding to phorbol 12-myristate 13-acetate and phytohemagglutinin. Immediately following stimulation, p50 is hyperphosphorylated, and a phosphorylated form of p50 (pp50) is translocated from the cytoplasm to the nucleus. The kinetics of this nuclear translocation paralleled that of the appearance of an active kappa B DNA-binding complex. An at least 30-fold higher level of kappa B DNA binding was detected in pp50 than p50. The enhanced binding could be attributed to a much greater stability detected in the complex consisting of kappa B DNA and pp50, but not p50. These results suggest that phosphorylation of p50, and perhaps other family members as well, may be involved in the activation of NF-kappa B/Rel family transcription factors.

Base Sequence↗
PubMed1994

NF-kappa B/Rel family members are physically associated phosphoproteins.

We performed radioimmunoprecipitation followed by serial immunoblots to show that, in the unstimulated Jurkat T cell line, the NF-kappa B/Rel family proteins, p80-c-Rel, p105-NF-kappa B, p65-NF-kappa B, p50-NF-kappa B and p36-I kappa B alpha, can be detected as complexes using antisera against c-Rel, p105-NF-kappa B or p65-NF-kappa B. p36-I kappa B alpha and p105, both known inhibitors of NF-kappa B function, can physically associate with NF-kappa B/Rel family members, but not with each other. In vivo and in vitro phosphorylation experiments demonstrated that NF-kappa B/Rel family members, including p105, c-Rel, p50, p65 (for the first time for p50 and p65) and p36-I kappa B alpha are also phosphoproteins. Phosphoserine and phosphothreonine residues were identified in these proteins isolated from unstimulated Jurkat cells. Both unphosphorylated and hyperphosphorylated forms of p36-I kappa B alpha were found in the complexes, suggesting that hyperphosphorylated I kappa B alpha is still capable of associating with the NF-kappa B/Rel family members. After stimulation with phorbol 12-myristate 13-acetate and phytohaemagglutinin for 10 min, p105-NF-kappa B and p50-NF-kappa B, but not p36-I kappa B, were highly phosphorylated. Phosphopeptide mapping of p105 showed that phorbol ester/phytohaemagglutinin stimulation may change p105 phosphorylation qualitatively.

Animals↗
PubMed1994

Inhibition of L-type calcium-channel activity by thapsigargin and 2,5-t-butylhydroquinone, but not by cyclopiazonic acid.

Thapsigargin (TG), 2,5-t-butylhydroquinone (tBHQ) and cyclopiazonic acid (CPA) all inhibit the initial Ca(2+)-response to thyrotropin-releasing hormone (TRH) by depleting intracellular Ca2+ pools sensitive to inositol 1,4,5-trisphosphate (IP3). Treatment of GH3 pituitary cells for 30 min with 5 nM TG, 500 nM tBHQ or 50 nM CPA completely eliminated the TRH-induced spike in intracellular free Ca2+ ([Ca2+]i). Higher concentrations of TG and tBHQ, but not CPA, were also found to inhibit strongly the activity of L-type calcium channels, as measured by the increase in [Ca2+]i or 45Ca2+ influx stimulated by depolarization. TG and tBHQ blocked high-K(+)-stimulated 45Ca2+ uptake, with IC50 values of 10 and 1 microM respectively. Maximal inhibition of L-channel activity was achieved 15-30 min after drug addition. Inhibition by tBHQ was reversible, whereas inhibition by TG was not. TG and CPA did not affect spontaneous [Ca2+]i oscillations when tested at concentrations adequate to deplete the IP3-sensitive Ca2+ pool. However, 20 microM TG and 10 microM tBHQ blocked [Ca2+]i oscillations completely. The effect of drugs on calcium currents was measured directly by using the patch-clamp technique. When added to the external bath, 10 microM CPA caused a sustained increase in the calcium-channel current amplitude over 8 min, 10 microM tBHQ caused a progressive inhibition, and 10 microM TG caused an enhancement followed by a sustained block of the calcium current over 8 min. In summary, CPA depletes IP3-sensitive Ca2+ stores and does not inhibit voltage-operated calcium channels. At sufficiently low concentrations, TG depletes IP3-sensitive stores without inhibiting L-channel activity, but, for tBHQ, inhibition of calcium channels occurs at concentrations close to those needed to block agonist mobilization of intracellular Ca2+.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1994

[Antitumor activity of thevetoside alone and in combination with chlormethine in vivo].

Thevetoside (TS) is one of the cardiac glycosides. A study of antitumor activity was carried out in 6 types of murine tumors in vivo, such as the ascitic tumors H22, EAC, P388, and solid tumors S180, U14, Lewis lung carcinoma, which were treated with i.p. TS 1.5 mg.kg-1.d-1 alone or in combination with chlormethine (Chl) 0.3, 0.5, or 1.0 mg.kg-1.d-1. TS only showed a remarkable inhibition on the growth of 3 types of solid tumors with inhibition rates of 48.7%-56.7%. The effect of the combination therapy was much pronounced than that of independent administration. The life span under combined therapy was increased 82.4% to > 122.1%. For solid tumors, the combined administration gave inhibition rates of 65.6%-72.5%.

Animals↗
PubMed1993

Differential expression of Rel family members in human T-cell leukemia virus type I-infected cells: transcriptional activation of c-rel by Tax protein.

The Tax protein of the human T-cell leukemia virus type I (HTLV-I) has been shown to induce nuclear expression of Rel family NF-kappa B-binding proteins. However, under different experimental conditions, different J. H. Kim, Y. Daitoku, and W. G. Greene, J. Virol. 65:6892-6899, 1991). In this study, using specific immunological reagents capable of distinguishing individual members of the Rel family proteins, we show that only c-Rel, not NF-kappa B p50 or p65, is induced in HTLV-I-infected cells. Preferential c-rel induction by HTLV-I infection was detected at the protein and RNA levels as well as in the nuclear NF-kappa B-binding form. Induced c-rel expression was also detected in cells stably transfected with tax cDNA, further correlating the c-rel induction with viral Tax expression. An increase in c-rel mRNA was detected within 3 h after induction of Tax expression, suggesting that this effect is at least partially regulated at the level of transcription. Furthermore, using a particle bombardment method for gene cotransfection, we show that Tax can transcriptionally activate the c-rel promoter in a T-cell line, Jurkat.

Base Sequence↗
PubMed1993

Detection of c-mos proto-oncogene expression in human cells.

Although the human c-mos proto-oncogene has been characterized for more than a decade, very little is known about its protein product and its expression in somatic cells. We generated three human c-mos-specific antisera and report here the detection of c-mos protein in a human neuroblastoma cell line, SK-N-BE2 (BE2). Both Western (immuno-) blot and immunoprecipitation analyses detected a p37 as the major form and p40 and p35 as minor forms of the c-mos protein. Using Northern blot analysis, 3.5- and 1.7-kb c-mos messages were detected. Using a highly sensitive method that combines reverse transcription and the polymerase chain reaction (RT-PCR), c-mos RNA was detected in all the human samples examined. With Western blot analysis, we further showed that c-mos proteins are expressed in cervical carcinoma-derived cell lines. This ubiquitous expression of low levels of c-mos suggests a fundamental role for the c-mos proto-oncogene.

Animals↗
PubMed1991

Genetics of subdivided populations and its relationships with certain measures of association.

Unlike inbreeding, population subdivision affects different genotypes differently for multiple alleles, so that the simple relationship between inbreeding and subdivision for two alleles no longer holds for all genotypes. In this communication, the detailed effects of subdivision have been studied for three alleles with results easily generalized to any number of alleles. Then an average effect of subdivision is proposed. This average effect of subdivision is found to play the same role as the inbreeding coefficient for multiple alleles, so that the overall relationship between inbreeding and subdivision may be reestablished again. In the final section, we discuss the relationship of the genetic result with measures of association of square contingency tables arising from epidemiological, social studies, educational and psychological studies.

Alleles↗
PubMed1991

Classification of plasma cortisol patterns in normal subjects and in Cushing's syndrome.

The 24-h pattern of half-hourly sampled plasma cortisol in normal human subjects shows a 24-h (circadian) period, which may be variably distorted in patients who suffer from autonomous hypercortisolism (Cushing's syndrome). We have developed a pattern recognition system for computer classification of cortisol time series into the normal class and subclasses of Cushing's syndrome with different etiology ("pituitary" designating pituitary tumor, "adrenal" designating adrenal tumor, and "ectopic" designating tumor elsewhere). Discriminatory features were extracted from Fourier analysis and Karhunen-Loeve expansion coefficients of cortisol time series. Decision functions were trained by the LMSE algorithm and tested by the jack-knife test procedure on a data-base of 90 normal and patient patterns. The classification accuracy for normal, "pituitary," "adrenal," and "ectopic" classes was 100, 98.1, 98.3, and 100%, respectively. Hence this pattern recognition system may be useful as an aid in the differential diagnosis of Cushing's syndrome.

Algorithms↗
PubMed1991

p34cdc2 is physically associated with and phosphorylated by a cdc2-specific tyrosine kinase.

The mammalian homologue of the yeast cdc2 gene encodes a 34-kilodalton serine/threonine kinase that is a subunit of M phase-promoting factor. Recent studies have shown that p34cdc2 is also a major tyrosine-phosphorylated protein in HeLa cells and that its phosphotyrosine content is cell cycle regulated and related to its kinase activity. Here, we show that cdc2 is physically associated with and phosphorylated in vitro by a highly specific tyrosine kinase. Tyrosine phosphorylation of cdc2 in vitro occurs at tyrosine 15, the same site that is phosphorylated in vivo. The association between the two kinases takes place in the cytosolic compartment and involves cyclin B-associated cdc2. Evidence is presented that a substantial fraction of cytosolic cdc2 is hypophosphorylated, whereas nuclear cdc2 is hyperphosphorylated. Finally, we show that the tyrosine kinase associated with cdc2 may be a 67-kilodalton protein and is distinct from src, abl, fms, and other previously reported tyrosine kinases.

Amino Acid Sequence↗
PubMed1991

Method of path coefficients: a trademark of Sewall Wright.

This address is a tribute to a pioneer of population genetics, including human population genetics. The unique methodology employed by Sewall Wright in many genetic problems is the method of path coefficients. This essay traces the historical landmarks in the development of the path method and then shows how some of the conventional statistical results can be converted into expressions involving path coefficients. The construction of a path diagram to represent such statistical results is explained in terms of examples. In the last section an example of applying the path method to the problem of genetic linkage in a random mating population is given. I hope that, despite the ending of the Sewall Wright era, the path method will continue to serve the scientific world.

Genetics, Population↗
PubMed1990

Static anthropometry of civilian Chinese in Taiwan using computer-analyzed photography.

The purpose of this study was to establish a static anthropometric data bank for Chinese civilians in Taiwan using a computer-analyzed photographic method. Stratified random sampling was applied to decide the sampling site; sample size was established by considering standard errors in a pilot study. Then a photographic method was employed in addition to direct measurement of selected body dimensions. In all, 933 subjects were measured. The data were entered via a digitizer into a microcomputer for processing. The resulting anthropometric data bank was organized by age, sex, and occupational groupings. Comparisons with data from previous studies were made, and recommendations for further research presented.

Adolescent↗