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Biomedical subjects

J Pan

Publications and source records attributed to J Pan.

At least 145 records · Page 8Linked to original sources
PubMed1999

Cytochemical energy-filtering transmission electron microscopy of mitochondrial free radical formation in paraquat cytotoxicity.

The generation of oxygen free radicals was investigated using cytochemistry and its energy-filtering transmission electron microscopy in reference to the toxic mediator for the herbicide paraquat. When isolated intact mitochondria from rat livers were incubated in a medium containing paraquat and NADH, a mitochondrial NADH-quinone oxidoreductase activity generated superoxide anions to cause the destruction of mitochondria which resulted in cell death. The superoxide anions were immediately converted into hydrogen peroxide, which then formed cerium perhydroxide deposits in the presence of cerium ions and precipitated on the outer surface of the mitochondrial outer membrane. This localization was also specifically identified by energy spectral imaging and image-electron energy loss spectral analyses. Precipitation reaction was scavenged by the addition of either cytochrome c or catalase and inhibited by dicoumarol (an inhibitor of NAD(P)H-quinone oxidoreductases). These cytochemical energy-filtering transmission electron microscopic results indicated that paraquat generated free radicals from the outer membrane of mitochondria.

Animals↗
PubMed1999

Structural injury of osteosarcoma mitochondria by a novel antitumour agent, 2-methylfuranonaphthoquinone.

The effect of the novel anticancer 2-methylnaphtho[2,3-b]furan-4,9-dione (FNQ3) on human osteosarcoma cell lines (HuO9 and HuO9N2) was investigated. The IC50 values of FNQ3 were 5.95 microM for HuO9 and 3.86 microM for HuO9N2, while that for normal fibroblasts (WI-38 cell line) was 35.8 microM. The selectivity in antitumour activity which was estimated from the IC50 ratio of normal fibroblasts to tumour cells was 6.0 and 9.3 fold for HuO9 and HuO9N2, respectively. FNQ3 at 23.6 microM selectively injured mitochondria of HuO9 cells starting at 36 h and HuO9N2 cells at 24 h, whereas WI-38 cells were unaffected even after 72 h. These results demonstrated that FNQ3 was selectively toxic to the mitochondria of osteosarcoma cells similar to carcinoma cells (Pan et al. (1997) J. Electron Microsc. 46: 181), in comparison to normal cells.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Anti-cord factor (trehalose 6,6'dimycolate) IgG antibody in tuberculosis patients recognizes mycolic acid subclasses.

The detection of anti-cord factor (trehalose 6,6'-dimycolate) IgG antibody in active (smear-and/or culture-positive) and inactive (smear-and culture-negative) tuberculosis patients is a useful serodiagnostic tool that can be used for early clinical diagnosis of the disease. We estimated the titers of anticord factor IgG antibody in the sera of tuberculosis patients, and compared them with those of Mycobacterium avium-infected patients. Most of the serum samples obtained from the tuberculosis patients were highly reactive against M. tuberculosis (MTB) cord factor isolated from M. tuberculosis H37Rv, a human-type mycobacterial strain, whereas they were less reactive against M. avium (MAC) cord factor. Similarly, most of the serum samples of the MAC-infected patients were highly reactive against MAC cord factor and less reactive against MTB cord factor. These results suggest that anti-cord factor IgG antibody recognizes the mycolic acid subclasses as an epitope which comprises cord factor, since MTB and MAC cord factor differ in mycolic acid subclasses and molecular species composition. To clarify the exact antigenic epitope in cord factor and to find out a more sensitive and specific diagnostic test antigen, we examined the reactivity of patients' sera to glycolipids containing trehalose (cord factor and sulfolipid) obtained from various mycobacterial species. Furthermore, the reactivity of human antisera to various mycolic acid subclasses (alpha-, methoxy and keto mycolic acids) of MTB cord factor was compared. We found that anti-cord factor IgG antibody in the sera of human tuberculosis patients most strikingly recognized methoxy mycolic acid in the cord factor of M. tuberculosis, whereas it recognized alpha- and keto mycolic acids weakly. Pre-absorption studies of antibody with MTB cord factor or methoxy mycolic acid methyl ester showed that anti-cord factor antibody was absorbed partially, but consistently. This is the first report describing that the specific subclass of mycolic acid from mycobacteria is antigenic in the humoral immune system of human tuberculosis infection.

Antibodies, Bacterial↗
PubMed1999

Production and partial characterization of anti-cord factor (trehalose-6,6'-dimycolate) IgG antibody in rabbits recognizing mycolic acid subclasses of Mycobacterium tuberculosis or Mycobacterium avium.

An ELISA with cord factor (trehalose-6,6'-dimycolate) is useful for the serodiagnosis of tuberculosis. To clarify the exact antigenic epitope in cord factor, recognized by a rabbit anti-cord factor IgG antibody, and to ascertain the most sensitive and specific diagnostic test antigen, rabbits were immunized with two kinds of cord factors isolated from Mycobacterium tuberculosis or Mycobacterium avium and the reactivities of the sera were tested against cord factors or the component mycolic acid methyl esters by ELISA. The serum from rabbits immunized with M. tuberculosis cord factor was highly reactive against M. tuberculosis cord factor, but less reactive against M. avium cord factor. In contrast, the serum from rabbits immunized with M. avium cord factor was highly reactive against M. avium cord factor but less reactive against M. tuberculosis cord factor. Moreover, the serum from rabbits immunized with M. tuberculosis cord factor reacted against mycolic acid methyl esters, especially methoxy mycolic acid methyl ester. On the other hand, the serum from rabbits immunized with M. tuberculosis cord factor was less reactive against trehalose-6-monomycolate and not reactive against sulfolipid (2,3,6,6'-tetraacyl trehalose 2'-sulfate). From these results, it was concluded that the anti-cord factor IgG antibody, produced experimentally in rabbits, recognized the differences in the cord factor structures, i.e. the hydrophobic moiety rather than the carbohydrate moiety. It was also noted that the serum from rabbits immunized with M. tuberculosis cord factor was highly reactive against methoxy mycolic acid as an epitope. This paper is the first to describe how the anti-cord factor IgG antibody can recognize the mycolic acid subclasses, which differ according to the species of mycobacteria.

Animals↗
PubMed1999

Dimeric RFX proteins contribute to the activity and lineage specificity of the interleukin-5 receptor alpha promoter through activation and repression domains.

Interleukin-5 (IL-5) plays a central role in the differentiation, proliferation, and functional activation of eosinophils. The specific action of IL-5 on eosinophils and hematopoietically related basophils is regulated by the restricted expression of IL-5 receptor alpha (IL-5Ralpha), a subunit of high-affinity IL-5R, on these cells. We have previously identified an enhancer-like cis element in the IL-5Ralpha promoter that is important for both full promoter function and lineage-specific activity. Here, we demonstrate by yeast one-hybrid screening that RFX2 protein specifically binds to this cis element. RFX2 belongs to the RFX DNA-binding protein family, the biological role of which remains obscure. Using an electrophoretic mobility shift assay, we further show that RFX1, RFX2, and RFX3 homodimers and heterodimers specifically bind to the cis element of the IL-5Ralpha promoter. The mRNA expression of RFX1, RFX2, and RFX3 was detected ubiquitously, but in transient-transfection assays, multimerized RFX binding sites in front of a basal promoter efficiently functioned in a tissue- and lineage-specific manner. To further investigate RFX functions on transcription, full-length and deletion mutants of RFX1 were targeted to DNA through fusion to the GAL4 DNA binding domain. Tissue- and lineage-specific transcriptional activation with the full-length RFX1 fusion plasmid on a reporter controlled by GAL4 binding sites was observed. Distinct activation and repression domains within the RFX1 protein were further mapped. Our findings suggest that RFX proteins are transcription factors that contribute to the activity and lineage specificity of the IL-5Ralpha promoter by directly binding to a target cis element and cooperating with other tissue- and lineage-specific cofactors.

Animals↗
PubMed1999

Cardiomyocytes can be generated from marrow stromal cells in vitro.

We have isolated a cardiomyogenic cell line (CMG) from murine bone marrow stromal cells. Stromal cells were immortalized, treated with 5-azacytidine, and spontaneously beating cells were repeatedly screened. The cells showed a fibroblast-like morphology, but the morphology changed after 5-azacytidine treatment in approximately 30% of the cells; they connected with adjoining cells after one week, formed myotube-like structures, began spontaneously beating after two weeks, and beat synchronously after three weeks. They expressed atrial natriuretic peptide and brain natriuretic peptide and were stained with anti-myosin, anti-desmin, and anti-actinin antibodies. Electron microscopy revealed a cardiomyocyte-like ultrastructure, including typical sarcomeres, a centrally positioned nucleus, and atrial granules. These cells had several types of action potentials, such as sinus node-like and ventricular cell-like action potentials. All cells had a long action potential duration or plateau, a relatively shallow resting membrane potential, and a pacemaker-like late diastolic slow depolarization. Analysis of the isoform of contractile protein genes, such as myosin heavy chain, myosin light chain, and alpha-actin, indicated that their muscle phenotype was similar to that of fetal ventricular cardiomyocytes. These cells expressed Nkx2.5/Csx, GATA4, TEF-1, and MEF-2C mRNA before 5-azacytidine treatment and expressed MEF-2A and MEF-2D after treatment. This new cell line provides a powerful model for the study of cardiomyocyte differentiation.

Action Potentials↗
PubMed1999

Combination of all-trans retinoic acid with butyric acid and its prodrugs markedly enhancing differentiation of human acute promyelocytic leukemia NB4 cells.

OBJECTIVE: To use NB4, an authentic human acute promyelocytic leukemia cell line, as well as the marrow cells from patients with acute promyelocytic leukemia (APL), containing the PML/RAR alpha fusion gene and fused protein to examine the growth inhibition and cytodifferentiation induced by all-trans retinoic acid (ATRA), butyric acid (BA) and its prodrug tributyrin (TB) either as a single agent or in combinations. METHODS: NB4 and APL cells were cultured in presence of ATRA, BA and TB respectively either as a single agent or in combinations at various concentration ratio. Cell growth was measured and myeloid differentiation was determined by morphology and the percentage of positive nitroblue tetrazolium reduction (NBT) on consecutive days over the whole process of culture. RESULTS: NB4 cells can be induced by ATRA alone and synergistically induced by the combinations of BA or TB with ATRA to differentiate. The synergy was reflected by a remarkable decrease in the effective concentration of ATRA required in the combinations in comparison with it as a sole agent. The combinations also shortened the time for the cells to reach the same level of maturation as that needed for ATRA alone. The potentiation on ATRA-induced differentiation of NB4 cells seemed depending on an appropriate concentration ratio of each inducer in the combinations and the time of action. A preliminary result of in vitro induction of primarily cultured leukemic cells from APL patients by the combined inducers was promising. CONCLUSION: The combinations of ATRA with BA or TB at an appropriate ratio may improve the clinical outcome of differentiation therapy for APL patients.

Butyric Acid↗
PubMed1999

[Factor V Leiden and PTG20210A gene mutation in patients with venous thrombosis and healthy blood donors].

OBJECTIVE: To evaluate the incidence of factor V Leiden and prothrombin gene G20210A mutation in patients with venous thrombosis and healthy volunteers. METHODS: Factor V Leiden and prothrombin gene G20210A mutation were analysed in 97 cases of venous thrombosis and 100 healthy volunteers with the methods of one-step PCR-RFLP. RESULTS: PCR products for the factor V gene (175 bp) and for the prothrombin gene (118 bp) were identified to 157 bp and 98 bp fragments by electrophoresis after Taq I treatment. No factor V Leiden and prothrombin gene G20210A mutation were found in either group. CONCLUSION: The low incidence of factor V Leiden and prothrombin gene G20210A mutation suggest that they are not the major genetic risk factors for thrombophilia in the Chinese.

Adolescent↗
PubMed1999

[The expression and regulation of heme oxygenase-1 in asthmatic guinea pigs].

OBJECTIVE: To explore the expression and pathogenic mechanism of heme oxygenase-1(HO-1) in asthma. METHODS: Two groups of guinea pigs (10 in each) were treated with the specific stimulator(hemin) and inhibitor(Sn-PP) of HO-1 respectively. Their effects on the levels of HO-1 activity, COHb, cGMP and IgE in serum or blood and lung tissues were compared with each other. Acute asthmatic group (AAG), dexamethasone-prevented group(DPG), stable asthmatic group, ovalbumin-sensitized group and normal control group(NCG) were also included. Lung tissues of tested animals were pathologically observed and immunohistochemically stained. RESULTS: In the AAG and hemin stimulated group, the levels of COHb, cGMP and IgE were significantly increased with higher levels of activity and expression of HO-1 protein compared with the NCG (t = 4.575-10.188, P < 0.01). In DPG and Sn-PP inhibited groups, however, all measured parameters were markedly reduced compared with the AAG(P < 0.01). The other groups were normal. CONCLUSIONS: The increased production and activity of HO-1 resulted in increases of endogenous CO and cGMP and promoted inflammation and immunoreaction in asthma.

Animals↗
PubMed1999

[The effects of nitric oxide and endothelia levels on plasma in patients with chronic heart failure].

OBJECTIVE: To study the effects of prostaglandin E1 on plasma nitric oxide (NO) and endothelin (ET) levels in patients with chronic heart failure. METHODS: Pulmonary artery pressure (PAP), pulmonary arterial and venous plasma ET and angiotensin converting enzyme (ACE) levels were determined in patients with chronic heart failure (CHF) and the effects of prostaglandin E1 (PGE1) were evaluated. RESULTS: (1) Pulmonary hypertension was present in patients with CHF. Plasma NO and ET levels in the pulmonary artery were higher than those in the pulmonary vein (P < 0.05), the levels in the latter was in turn higher than those in normal subjects (P < 0.05). (2) Plasma ACE levels showed a similar change, (3) The increase of plasma ET was more than the increase of NO in patients with CHF, thus, NO/ET ratio was decreased in CHF (P < 0.05). (4) PGE1 caused significant decrease in PAP but increase in cardial index. It decreased plasma NO, ET, ACE, and increased NO/ET ratio (P < 0.05). These effects became more apparent with the increase of PGE1 level. CONCLUSION: NO and NO/ET ratio might be involved in CHF by causing pulmonary hypertension and local vascular endothelium perturbation. PGE1 could inhibit these effects and play an important role in the prevention and treatment of CHF.

Adolescent↗
PubMed1999

[Genetic polymorphism and susceptibility to occupational chronic manganism: a case-control study].

OBJECTIVE: In a case-control study, the possible genetic factors relevance to occupational chronic manganism were investigated. METHODS: Forty-nine manganisms who were welders and ferromanganese smelters occupationally exposed to manganese dust and fume from three metallurgical industries, and fifty unrelated healthy control subjects who were working same workshops were recruited. The subjects were matched for sex, age, cigarette and alcohol intake. The manganese exposure duration was also matched in this case-control study. Genetic polymorphism of cytochrome P450 2D6L (CYP2D6L) gene and NAD(P)H: quinone oxidreductase (NQO1) genes from all subjects were investigated. The mutations of CYP2D6L gene located exon 6 were analyzed by a polymerase chain reaction (PCR)-based DNA amplification combined with Hha I restriction fragment length polymorphism (RFLP). The substitution of 609(C-T) at exon 6 of DT-diaphroase gene was analyzed by PCR combined Hinf I RFLP. RESULTS: The frequency of polymorphic allels, a mutation of CYP2D6, was significantly lower in patients with manganism (16.3%) than that of the controls (29.0%). A significant association was also found between the homozygote variant of CYP2D6L gene and occupational manganism. These results suggest that the CYP2D6 gene might be one of the susceptibility genes for Mn-induced neurotoxicity. The allele and genotype frequencies of NQO1 gene were similar in the manganism cases and control subjects. CONCLUSION: It is possible that CYP2D6 gene may be a valuable susceptibility biomarker responded to Mn-induced central nervous system disorders in workers exposed to manganese.

Adult↗
PubMed1999

[Changes of neurobehavioral functions in workers exposed to manganese].

The aim of this study was to assess the neurotoxic effects associated with the level of airborne manganese in the work place. A cumulative exposure index(CEI) was calculated for each subject. The neurobehavioral test battery, in terms of choosing reaction time, finger tapping, digit symbol, stylus in hole, Benton visual retention and Santa Ana dexterity was applied in the study. The manganese exposed workers had slower motor and response speed, poorer visuomotor coordination and steadiness. There was a dose-response relationship tendency between the cumulative exposure index and the behavioral function. Hence the neurobehavioral test may be a sensitive method in detecting early changes in motor and cognitive function among manganese-exposed workers. The study also demonstrates that the cumulative exposure of manganese about 1 mg/m3 per year may induce subclinical signs of intoxication.

Adult↗
PubMed1999

[GC-MS analysis of volatile constituents of rhizoma Heterosmilacis].

OBJECTIVE: To extract and analyze the volatile constituents from the dried rhizomes of Heterosmilax yunnanensis(A) and H. chinensis(B). METHODS: Qualitative and quantitative analysis were made by GC-MS and GC. RESULTS: Forty and forty-seven constituents were identified from A and B respectively, the identification rates being 74.85% and 81.26% respectively. CONCLUSION: The volatile constituents of A and B are almost the same, but slightly different in content.

Gas Chromatography-Mass Spectrometry↗
PubMed1999

[GC-MS analysis of essential oils from the roots of Saposhnikovia divaricata (Turcz.) Schischk, Libanotis laticalycina Shan et Sheh, Seseli yunnanense Franch. and Peucedanum dielsianum Fedde ex Wolff].

OBJECTIVE: To analyze the constituents of the essential oils from the roots of Saposhnikovia divaricata, Libanotis laticalycina, Seseli yunnanense and Peucedanum dielsianum. METHOD: GC-MS method was used. RESULT: 58 compounds were identified. CONCLUSION: To compare the constituents and their contents of 6 samples, 3 samples of S. divaricata growing in 3 places are similar, L. laticalycina, S. yunnanense and P. dielsianum are different from S. divaricata in varying degrees.

Alkynes↗
PubMed1999

[Surgical reduction and rigid internal fixation of midface fractures].

OBJECTIVE: To determine the cause, clinical characteristics and treatment of midface fractures. METHODS: A retrospective review of 98 patient records was conducted. Data regarding age, cause of fracture, anatomic site, treatment modalities and clinical results were reviewed. RESULTS: Of the 98 patients, 78.6% were male, with the peak incidence occurring in the age group from 21 to 40 years old. Of the fractures, 32.6% were due to traffic accidents, 24.5% to assaults, and 17.3% to accidental falls. Most patients (87.8%) were treated by open reduction surgery and rigid internal fixation. Only 12.2% of patients were treated by closed reduction fixation. Almost all of the patients regained normal face appearance and functional occlusion. CONCLUSION: Surgical reduction and rigid internal fixation of midface fractures is a satisfactory method of treatment.

Adolescent↗
PubMed1999

[Determination of metals in atmospheric particulates by atomic absorption spectrometric method (AAS) with CA-CN micropore membrane filters used for sampling].

A new sampling method of atmospheric particulates using 0.22 microm pore diameter micropore membrane filters was introduced. Copper, lead, zinc cadmium, manganese, iron, nickel and chromium in atmospheric particulates were determined by atomic absorption spectrometry. This sampling method has shown several advantages: easy, complete and fast digestion; low membrane blank; increased flexibility to surrounding temperature change; high elution recovery, standard addition recovery, precision and accuracy.

Metals↗