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Biomedical subjects

C J Li

Publications and source records attributed to C J Li.

At least 55 records · Page 3Linked to original sources
PubMed1998

A new lysine derivative and new 3-bromopyrrole carboxylic acid derivative from two marine sponges.

A novel lysine derivative, 1, has been isolated from the marine sponge Axinyssa terpnis, in addition to 4alpha-isocyanogorgon-11-ene and related compounds (2-4). From the marine sponge Axinella carteri, the new 3-bromopyrrole carboxylic acid derivative, 5, was obtained along with the known compounds aldisin (6) and 2-bromoaldisin (7). Both sponges were collected from Chuuk Atoll, Federated States of Micronesia. The compounds were characterized by spectroscopic and chemical methods.

Animals↗
PubMed1998

Apoptosis in non-proliferating cells: implications for viral infection and tumourigenesis.

To date much attention has been focused on regulation of apoptosis in proliferating cells. However, recent evidence shows that regulation of apoptosis in quiescent tissue plays an important role in homeostasis of the organism. This review examines the implications of apoptosis of quiescent cells for both tumourigenesis and viral infection such as HIV. In this article we propose a dual role for cellular activation in the homeostasis regulation. In this model cellular mitogens not only activate quiescent cells into the active cell cycle, but under certain conditions, loss of quiescence may result in apoptosis. The loss of quiescence-associated apoptosis may play a significant role in tumourigenesis and viral infections.

Journal Article↗
PubMed1998

[Studies on the mechanism of alpha-MSH in reducing IL-1 beta-induced fever].

The effect of alpha-melanocyte-stimulating hormone (alpha-MSH) on IL-1 beta-induced fever and release of hypothalamic cAMP was observed in the present work. The results showed that alpha-MSH markedly suppressed febrile response (P < 0.05) and decreased the cAMP content in hypothalamus in response to icv injection of IL-1 beta (P < 0.01). The cAMP content of the medium in which the hypothalamic was incubated for 40 min in the presence of IL-1 beta was significantly increased (P < 0.01). However, this increase action could be prevented by a pretreatment with alpha-MSH. The results indicate that the inhibitory effect of alpha-MSH on the enhanced synthesis and release of cAMP in hypothalamus exposed to IL-1 beta might be one of the mechanisms of suppressing fever induced by IL-1 beta.

Analgesics, Non-Narcotic↗
PubMed1997

Human immunodeficiency virus type 1 TAT protein activates B lymphocytes.

HIV-1 infection causes B cell hyperactivation. Tat protein, a potent virus-encoded transactivator, has the potential to activate B cells based on its pleiotropic biological properties: (1) Tat regulates cellular gene expression; (2) Tat modulates growth of various cell types; and (3) Tat is released from infected T cells and acts on bystander uninfected cells in a paracrine fashion. To test a possible activating effect of Tat on B cells, we examined the effect of purified Tat on the expression of Fas, an activation marker, in B cells in primary culture. Flow cytometric analysis demonstrated that treatment of peripheral blood mononuclear cells with Tat, at concentrations in the range of extracellular Tat as determined in vivo, up-regulated Fas expression in B cells. Reverse transcriptase-PCR further demonstrated that Tat induced Fas expression in B cells at the mRNA level. These results indicate that exogenous Tat alone can activate B cells, suggesting that Tat may contribute to B cell hyperactivation during the early stage of HIV-1 infection and activation-induced B cell death mediated by Fas during the late stage of HIV-1 infection.

B-Lymphocytes↗
PubMed1997

Tat protein induces self-perpetuating permissivity for productive HIV-1 infection.

We report that human immunodeficiency virus type 1 (HIV-1) has evolved a self-perpetuating mechanism to actively generate cells permissive for productive and cytopathic infection. Only activated T cells can be productively infected, which leads to their rapid depletion (2 x 10(9)/day in an infected individual). Establishment of productive HIV-1 infection therefore requires continual activations from the large pool of quiescent T cells. Tat protein, which is secreted by infected cells, activated uninfected quiescent T cells in vitro and in vivo. These Tat-activated uninfected cells became highly permissive for productive HIV-1 infection. Activation of primary T cells by Tat protein involved integrin receptors and was associated with activation of mitogen-activated protein kinases, including ERK1 and JNK kinase. Accordingly, these primary T cells progressed from G0 to the late G1 phase of the cell cycle.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1997

Changes in the 3-dimensional distribution of mitochondria during meiotic divisions of mouse oocytes.

Mitochondrial reorganization during meiotic maturation and parthenogenetic activation was studied in mouse oocytes using a laser scanning confocal microscope and a transmission electron microscope. Mitochondria were mainly distributed perinuclearly in the germinal vesicle (GV) stage oocytes and were dispersed throughout ooplasm after germinal vesicle breakdown (GVBD), except for a slightly higher occurrence in one hemisphere of oocytes, from which the first polar body (PbI) would become extruded. Mitochondria reaggregated around the metaphae II (MII) spindle and pronuclear region after alcohol activatation at the MII stage. The mitochondrial distribution may correspond to the Ca(2+) changes during meiotic maturation and parthenogenetic activation.

Journal Article↗
PubMed1997

Acetaldehyde-modified and 4-hydroxynonenal-modified proteins in the livers of rats with alcoholic liver disease.

Liver proteins form adducts with acetaldehyde and are modified by products of lipid peroxidation in alcohol-fed animals. It has been hypothesized that the formation of these modified liver proteins may contribute to liver injury in alcoholic liver disease. The present work was performed to determine the extent of protein modification in rats with experimental alcoholic liver disease. Rats were fed ethanol intragastrically with medium chain triglycerides (MCTs), palm oil, corn oil, or fish oil. The group fed MCTs and ethanol showed no liver injury, rats fed palm oil and ethanol showed only fatty liver, rats fed corn oil and ethanol showed fatty liver with moderate necrosis and inflammation, and rats fed fish oil and ethanol showed fatty liver with severe necrosis and inflammation. Antibodies were raised by using keyhole limpet hemocyanin modified in vitro by 4-hydroxynonenal (4-HNE) or acetaldehyde as immunogens. When liver extracts were examined by Western blot analysis, the intensities of the acetaldehyde-modified protein band (37 kd) in the alcohol-fed animals were significantly different among the ethanol-treated groups and correlated with plasma acetaldehyde concentrations. It was strongest in rats fed fish oil and ethanol, followed by rats fed palm oil and ethanol and rats fed corn oil and ethanol, whereas rats fed MCTs and ethanol showed the weakest intensity. The 37-kd protein-adetaldehyde adduct was located mainly in the pericentral region of the liver. No acetaldehyde adduct was detected in the control rats that were pair-fed with isocaloric amounts of dextrose. Western blot analysis using the anti-4-HNE antibody showed four distinctive bands (48, 45, 40, and 38 kd) in the liver extracts of alcohol-fed rats. Control animals showed only a weak 38-kd band. Although the intensities of the 48-, 40-, and 38-kd bands were similar among the different ethanol-treated groups, the intensity of the 45-kd band decreased from MCTs and ethanol > palm oil and ethanol > or = corn oil and ethanol > fish oil and ethanol. The data indicate that the degree of liver protein modification by acetaldehyde correlates well with the severity of liver injury in ethanol-fed rats, whereas modification by the lipid peroxidation product 4-HNE shows no correlation with the severity of liver injury.

Acetaldehyde↗
PubMed1997

Topotecan inhibits human immunodeficiency virus type 1 infection through a topoisomerase-independent mechanism in a cell line with altered topoisomerase I.

Topotecan (TPT), a known inhibitor of topoisomerase I, has previously been shown to inhibit the replication of several viruses. The mechanism of inhibition was proposed to be the inhibition of topoisomerase I. We report that TPT decreased replication of human immunodeficiency virus type 1 (HIV-1) in CPT-K5, a cell line with a topoisomerase I mutation. TPT inhibited production of HIV-1 RNA and p24 in CPT-K5 and wild-type cells equally effectively. The antiviral effects of TPT were observed not only in the topoisomerase-mutated CPT-K5 line but also in peripheral blood mononuclear cells (PBMC) acutely infected with clinical isolates and in OM10.1 cells latently infected with HIV and activated by tumor necrosis factor alpha. Little toxicity from TPT was noted in HIV-1-infected PBMC and in CPT-K5 and OM10.1 cells as measured by cell growth and proliferation assays. These observations suggest that TPT targets factors in virus replication other than cellular topoisomerase I and inhibits cytokine-mediated activation in latently infected cells by means other than cytotoxicity. These results suggest a potential for TPT and for other camptothecins in anti-HIV therapy alone and in combination with other antiretroviral drugs.

Camptothecin↗
PubMed1997

[Treatment of integrated traditional and Western medicine in recurrent spontaneous abortion of immune abnormality type].

UNLABELLED: Immune abnormality type of recurrent spontaneous abortion (RSA) is an important etiological type, major findings of that are the abnormal increases in auto and/or allo-antibodies of anti-zona pellucida, antiphospholipid and anti-ABO blood group. In the present study, to assess the clinical values of integrated traditional and Western medicine and its therapeutic mechanisms in treating immune abnormality type of RSA. METHODS: Aborters were treated by Zhibai Dihuang Pills for anti-zona pellucida antibodies, and clear evil Heat, remove Dampness, replenish blood and activate circulation by Chinese medicinal herbs recipe for anti-phospholipid and anti-ABO group antibodies. RESULTS: After they had been treated by these recipe, 92.3% of them became pregnant with normal delivery. It was found in dynamic investigation that level of the antibodies turned to decrease gradually during the treatment, and that of anti-phospholipid and anti-ABO group antibodies increased again at beginning of pregnancy and then decreased gradually with continuing pregnancy. CONCLUSION: Chinese herbs recipe could be used to treat RSA of the immune abnormality type by way of decreasing the elevated levels of auto and/or allo-antibodies.

ABO Blood-Group System↗
PubMed1996

Nonprotein amino acids from seeds of Cycas circinalis and Phaseolus vulgaris.

Our chemical studies on Cycas circinalis seeds from Guam has provided two new nonprotein amino acids, N-(3'-one-5'-methyl)-hexylalanine and leucine betaine. N-methylisoleucine, previously reported as a component of naturally occurring peptides, has been isolated as a free amino acid from the seeds of Phaseolus vulgaris (pinto bean), together with S-methylcysteine, pipecolic acid and a dipeptide, gamma-glutamyl-leucine.

Alanine↗
PubMed1996

An unusual cycloartane triterpenoid from Cimicifuga foetida.

A new cycloartane triterpenoid glycoside has been isolated from the rhizomes of Cimicifuge foetida L. The spectroscopic characteristics of the new compound are different from previously described cycloartane triterpenoids because of the loss of the 24-isopropyl group as well as the presence of a 11 beta-OH group. Based on spectroscopic evidence, including a series of 2D-NMR analyses, the structure of the new triterpene is assigned as 24-des-isopropyl-7-ene-23-one-9,19; 16,24-dicycloart-3 beta,11 beta,16 alpha,24 alpha-tetraol 3-O-beta-D-xylopryanoside, named here as neocimiside. The structure of the aglycone of neocimiside was confirmed by X-ray analysis.

China↗
PubMed1995

A DNase from the trypanosomatid Crithidia fasciculata.

We have purified to homogeneity a DNase from a Crithidia fasciculata crude mitochondrial lysate. The enzyme is present in two forms, either as a 32 kDa polypeptide or as a multimer containing the 32 kDa polypeptide in association with a 56 kDa polypeptide. Native molecular weight measurements indicate that these forms are a monomer and possibly an alpha 2 beta 2 tetramer, respectively. The monomeric and multimeric forms of the enzyme are similar in their catalytic activities. Both digest double-stranded DNA about twice as efficiently as single-stranded DNA. They introduce single-strand breaks into a supercoiled plasmid but do not efficiently make double-strand breaks. They degrade a linearized plasmid more efficiently than a nickel plasmid. Both enzymes degrade a 5'-32P-labeled double-stranded oligonucleotide to completion, with the 5'-terminal nucleotide ultimately being released as a 5'-mononucleotide. One difference between the monomeric and multimeric forms of the enzyme, demonstrated by a band shift assay, is that the multimeric form binds tightly to double-stranded DNA, possibly aggregating it.

Animals↗
PubMed1995

Induction of apoptosis by beta-lapachone in human prostate cancer cells.

beta-Lapachone, a plant product, has been shown to be a novel inhibitor of DNA topoisomerase I, with a mode of action different from camptothecin and a chemical structure distinct from those of current anti-cancer drugs. We observed that beta-lapachone, at concentrations of less than 8 microM, induces cell death with characteristics of apoptosis in human prostate cancer cell lines. This effect of beta-lapachone was also observed in a human promyelocytic leukemia cell line (HL-60). beta-Lapachone-induced apoptosis is independent of p53 expression, and ectopic overexpression of bcl-2 did not confer significant resistance to beta-lapachone. Among other human carcinoma and adenoma cell lines tested, human breast and ovary carcinoma showed sensitivity to the cytotoxic effect of beta-lapachone without manifesting signs of apoptosis. These results suggest that beta-lapachone is a potential compound to be added to cancer chemotherapy, particularly for prostate cancer.

Apoptosis↗
PubMed1995

Reciprocal modulations between p53 and Tat of human immunodeficiency virus type 1.

Infection by human immunodeficiency virus type 1 (HIV-1) causes acquired immunodeficiency syndrome (AIDS) after a long clinical latency. This disease is associated with a spectrum of cancers. Here we report that wild-type p53 is a potent suppressor of Tat, a major transactivator of HIV-1. Reciprocally, Tat inhibits the transcription of p53. Downregulation of p53 by upregulated tat may be important for the establishment of productive viral infection in a cell and also may be involved in the development of AIDS-related malignancies.

Base Sequence↗
PubMed1995

Induction of apoptosis in uninfected lymphocytes by HIV-1 Tat protein.

Infection by human immunodeficiency virus-type 1 (HIV-1) is typified by the progressive depletion of CD4 T lymphocytes and deterioration of immune function in most patients. A central unresolved issue in acquired immunodeficiency syndrome (AIDS) pathogenesis is the mechanism underlying this T cell depletion. HIV-1 Tat protein was shown to induce cell death by apoptosis in a T cell line and in cultured peripheral blood mononuclear cells from uninfected donors. This Tat-induced apoptosis was inhibitable by growth factors and was associated with enhanced activation of cyclin-dependent kinases.

Apoptosis↗
PubMed1995

[The study on the mechanism of EGF inducing the in vitro meiotic maturation resumption of mouse oocytes].

The effect and mechanism of EGF and progesterone on the meiotic maturation resumption were studied. The results showed that progesterone regulated the action of EGF. The inhibitor of 3 beta-HSD, the key enzyme of progesterone synthesis, Epostane could not only prevent the effect of EGF, but inhibit the progesterone production promoted by EGF in cultured ovary granulosa cells as well. On the other hand, heparin could lessen the function of EGF and progesterone, which implies that calcium participated the effect of EGF and progesterone. Fura-2 was used to indicate the changes of intracellular calcium level in single cumulus cell. It is found that a calcium wave appeared in cumulus cell when EGF or progesterone acted. But Ca2+ level returned to normal immediately after progesterone was added, and Ca2+ in the cumulus cell still remained higher level after EGF acted. This results indicated that calcium in cumulus cell adjusted the action of EGF and progesterone.

Animals↗
PubMed1995

[Treatment of immunological infertility with Chinese medicinal herbs of ziyin jianghuo].

According to the microcosmic Syndrome Differentiation, immunological infertility is recognised as Kidney Yin Deficiency-Hyperactivity of Fire Syndrome. Zhibai Dihuang Pills, a recipe of Chinese medicinal herbs, was used to treat the infertile couples with antisperm and/or antizona pellucida antibodies in their blood serum. It was found that after the treatment, the antibodies were converted to negativeness in 81.3% of immunological infertile couples. All 8 cases of successful pregnancy occurred in 1-9 months after antibodies negative conversion and the negative status was maintained throughout the course of pregnancy.

Autoantibodies↗