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Biomedical subjects

K Fang

Publications and source records attributed to K Fang.

At least 19 recordsLinked to original sources
PubMed2005

Etoposide (VP-16) sensitizes p53-deficient human non-small cell lung cancer cells to caspase-7-mediated apoptosis.

Human non-small-cell-lung-cancer (NSCLC) cells of (p)53-null genotype were exposed to low-dosage topoisomearse II inhibitor etoposide (VP-16). The cellular proliferation rate could be effectively inhibited by VP-16 in dose-dependent manner. The effective drug concentration for growth inhibition could be as low as 0.5 microM and the apoptotic phenotype became evident 48 h later. In H1299 cells, VP-16-induced cytotoxic effect was demonstrated associated with apoptosis that disappeared when restored with wild-type p53. Cell cycle analysis revealed that, upon VP-16 induction, cell death began with growth arrest by accumulating cells at the G(2)-M phase. The cells at sub-G(1) phase increased at the expense of those at G(2)-M transition state. To assess the regulation of cell cycle modulators, western blot analysis of H1299 cell lysates showed the release of apoptosis initiator, cytochrome c and apaf-1 hours following drug induction. The cleavage of downstream effectors, procaspase-9 and procaspase-7, but not procaspase-3, was accompanied with proteolysis of poly-(ADP-ribose) polymerase (PARP). VP-16-activated procaspase-7 cleavage was abrogated in cells with ectopically expressed p53. On the other hand, the inhibited procaspase-7 fragmentation by caspase-specific inhibitor reversed apoptotic phenotype caused by drug induction. Thus, VP-16-induced apoptotic cell death was contributed by caspase-7 activation in(p)53-deficient human NSCLC cells.

Apoptosis↗
PubMed2005

The suppressed proliferation and premature senescence by ganciclovir in p53-mutated human non-small-lung cancer cells acquiring herpes simplex virus-thymidine kinase cDNA.

The concerted actions of molecular networks determine how cells undergo proliferation, death or aging. Here we show that the highly invasive, tumorigenic human non-small-cell-lung cancer (NSCLC) cells carrying mutated p53 alleles were transfected with herpes simplex virus-thymidine kinase (HSV-tk) cDNA and the selected clone was susceptible to exogenous ganciclovir (GCV). The work further indicated that, in the stable HSV-tk transfectants, GCV suppressed cell proliferation by inducing G(2)/M cell cycle arrest and premature senescence and the potency can be amplified through bystander effect. The growth suppression of the established tumor xenografts in nude mice can be successfully targeted by GCV. These data showed that the GCV-suppressed tumor cell proliferation can be coordinated by cell cycle arrest and cellular senescence in HSV-tk transfectant lacking wild-type p53.

Animals↗
PubMed2005

Familial atrophia maculosa varioliformis cutis: case report and pedigree analysis.

Atrophia maculosa varioliformis cutis (AVMC) was first described in 1918, as a rarely reported form of idiopathic macular atrophy on the cheeks. Nineteen patients have been reported in the past 86 years. Recently we diagnosed a 25-year-old woman as AMVC and investigated her family history. We collected the clinical data of the pedigree and presumed that AVMV is in a autosomal dominant inheritance.

Adolescent↗
PubMed2004

Genetic testing in spinocerebellar ataxia in Taiwan: expansions of trinucleotide repeats in SCA8 and SCA17 are associated with typical Parkinson's disease.

DNA tests in normal subjects and patients with ataxia and Parkinson's disease (PD) were carried out to assess the frequency of spinocerebellar ataxia (SCA) and to document the distribution of SCA mutations underlying ethnic Chinese in Taiwan. MJD/SCA3 (46%) was the most common autosomal dominant SCA in the Taiwanese cohort, followed by SCA6 (18%) and SCA1 (3%). No expansions of SCA types 2, 10, 12, or dentatorubropallidoluysian atrophy (DRPLA) were detected. The clinical phenotypes of these affected SCA patients were very heterogeneous. All of them showed clinical symptoms of cerebellar ataxia, with or without other associated features. The frequencies of large normal alleles are closely associated with the prevalence of SCA1, SCA2, MJD/SCA3, SCA6, and DRPLA among Taiwanese, Japanese, and Caucasians. Interestingly, abnormal expansions of SCA8 and SCA17 genes were detected in patients with PD. The clinical presentation for these patients is typical of idiopathic PD with the following characteristics: late onset of disease, resting tremor in the limbs, rigidity, bradykinesia, and a good response to levodopa. This study appears to be the first report describing the PD phenotype in association with an expanded allele in the TATA-binding protein gene and suggests that SCA8 may also be a cause of typical PD.

Age of Onset↗
PubMed2004

Multicentric reticulohistiocytosis with generalized systemic involvement.

We describe a 33-year-old woman with a 2-year history of rheumatoid arthritis-like joint changes and a 1-year history of papulonodules on the fingers, ears, oral mucosa, forearm, elbows and thighs, and erythematous plaques on the buttocks. Six months after the onset of the cutaneous lesions she had dyspnoea, 3 months later she developed a husky sound. Biopsies from the nodules on the ear and left forearm revealed multinucleated giant cells with eosinophilic 'ground-glass' cytoplasm. Bronchoscopy revealed that there were nodules in the bronchus. A biopsy taken from a nodule from the bronchus was consistent with multicentric reticulohistiocytosis. Fibrostic laryngoscopy showed a mass 1.5 x 2.0 cm(2) in size on the left aryepiglottic fold and posterior commissure. Magnetic resonance imaging revealed a large pleural effusion and pericardiac effusion. Ultrasound revealed splenomegaly and peritoneal fluid. Combination therapy with prednisone, cyclophosphamide and methotrexate significantly improved cutaneous and joint symptoms. The huge cutaneous erythematous plaques and the generalized systemic involvement make this case interesting.

Adult↗
PubMed2003

Establishment of cell lines from a tropical grouper, Epinephelus awoara (Temminck & Schlegel), and their susceptibility to grouper irido- and nodaviruses.

Four tropical marine fish cell lines have been established from the eye, fin, heart and swim bladder of grouper, Epinephelus awoara (Temminck & Schlegel). Optimum media and temperature conditions for maximum growth were standardized. The eye and swim bladder cells were mostly epithelial, but the fin and heart cells were mostly fibroblastic. The viability of cells was 95% after 1 year of storage in liquid nitrogen (-196 degrees C). Besides these four cell lines, previously established grouper brain, kidney and liver cell lines were also used for a viral susceptibility study which showed that all the cell lines were sensitive to grouper iridovirus, whereas only brain, fin and liver cell lines were susceptible to the yellow grouper nervous necrosis virus (a nodavirus). Electron microscopy studies of the grouper irido- and nodaviruses in ultrathin sections of infected cells showed an abundance of viral particles in the cytoplasm of the virus-infected cells indicating the effective replication of these two viruses. It is suggested that these cell lines can be used for the isolation of putative fish specific viruses and provide a valuable tool to study the mechanisms of host-pathogen interactions. Furthermore, these cell lines upon transfection, using pEGFP-C1 and pEGFP-aMT2.5 (ayu metallothionein promoter), produced significant fluorescent signals indicating their utility for exogenous studies.

Animals↗
PubMed2001

S-Nitrosylation of mitochondrial caspases.

Caspase-3 is a cysteine protease located in both the cytoplasm and mitochondrial intermembrane space that is a central effector of many apoptotic pathways. In resting cells, a subset of caspase-3 zymogens is S-nitrosylated at the active site cysteine, inhibiting enzyme activity. During Fas-induced apoptosis, caspases are denitrosylated, allowing the catalytic site to function. In the current studies, we sought to identify the subpopulation of caspases that is regulated by S-nitrosylation. We report that the majority of mitochondrial, but not cytoplasmic, caspase-3 zymogens contain this inhibitory modification. In addition, the majority of mitochondrial caspase-9 is S-nitrosylated. These studies suggest that S-nitrosylation plays an important role in regulating mitochondrial caspase function and that the S-nitrosylation state of a given protein depends on its subcellular localization.

Caspase 3↗
PubMed2001

High-performance liquid chromatographic analysis for a non-chromophore-containing phosphatidyl inositol analog, 1-((1-O-octadecyl-2-O-methyl-sn-glycero)phospho)-1D-3-deoxy-myo-inositol, using indirect UV detection.

Phosphatidylinositide-3-kinase (PI3 kinase) is an important constituent of growth factor regulation. It is also involved in oncogene signaling pathways. An ether-containing phosphatidyl inositol(PI) analog, OMDPI, 1-[(1-O-octadecyl-2-O-methyl-sn-glycero)-phospho]-1D-3-deoxy-myo-inositol, is a potent inhibitor of this pathway and may be clinically useful in the treatment of a variety of neoplasms. OMDPI is currently being investigated as an anti-tumor agent by the National Cancer Institute, NIH. OMDPI, a non-chromophore-containing PI analog, is not directly adaptable to the commonly used UV detection of HPLC. This paper reports the development and validation of an HPLC assay for OMDPI based on indirect UV detection, in which a UV-absorbing ion-pair reagent (the probe), protriptyline, is added to the mobile phase to induce a signal for the compound. The method is sensitive (limit of detection <5 microl of 1 microg/ml or 5 ng), precise (R.S.D.<2.5%), linear (r2=0.9995) and accurate (error<0.7%). It is superior to refractive index detection and evaporative light scattering detection in either sensitivity or linearity and does not require special equipment.

Chromatography, High Pressure Liquid↗
PubMed2001

New biotransformation products of nemadectins.

Selected nemadectins (formerly LL-F28249 series) have been fed to a panel of microorganisms with the aim of generating new derivatives. In addition to products resulting from the oxidation of the terminal methyl group (C-29), a unique phosphorylated nemadectin was isolated. The phosphate group was determined to be at C-23 by HMBC between phosphorus and H-23. Milbemycin or nemadectin derivatives with natural substituents involving the 23-hydroxyl group were hitherto unknown.

Animals↗
PubMed2000

Stability-indicating LC assay of and impurity identification in homoharringtonine samples.

Homoharringtonine (HHT) is a potent myelosuppressive agent and has antitumor activity. Recent studies suggest that it inhibits tumor growth by inducing apoptosis. HHT is an ester of the alkaloid cephalotaxine. It is isolated from genus Cephalotaxus. At least ten HHT analogs have been identified from cephalotaxus extracts. High performance liquid chromatography (HPLC) separations of the cephalotaxine alkaloids in plant extracts have been reported, they have not been validated as specific and stability-indicating for HHT. Due to the complexity of the alkaloid extracts, it is conceivable that additional analogs may still be unresolved from HHT. This paper presents an improved and validated HPLC assay for HHT. The assay is stability-indicating, precise (R.S.D. < 1%), linear (r2 = 0.9999), and accurate (error < 1%). The assay reveals three congeners present as impurities in HHT samples. Two are new and have not been previously reported. Identities of the impurities and forced decomposition products, elucidated with their HPLC retention and spectral data, are also presented.

Antineoplastic Agents, Phytogenic↗
PubMed2000

Elevated nitric oxide metabolite levels in chronic sinusitis.

Decreased exhaled nitric oxide (NO) is found in chronic sinusitis. NO metabolites (nitrates, nitrites, and S-nitrosothiols) were measured in sinus lavages with a rabbit model of chronic sinusitis. NO metabolite levels (mean +/- SD) were 3.0+/-1.6 micromol/L in uninfected rabbits, 10.7+/-11.4 micromol/L in infected animals, and 7.6+/-5.4 micromol/L in postantrostomy recovering animals. Infected sinuses had elevated levels of NO metabolites that were statistically significant (P<0.01) when compared with uninfected sinuses. Mucociliary transport velocity was measured in uninfected (16.0+/-5.7 mm/minute), infected (5.2+/-1.3 mm/minute), and recovery phases (3.0 mm/minute). Endoscopic appearance, light and electron microscopy, and bacterial cultures improved during recovery. Elevated levels of NO metabolites were found during chronic sinusitis and began to return to normal levels during recovery. The possible link between NO in epithelial autotoxicity and host defense mechanisms warrants further investigation.

Animals↗
PubMed2000

S-nitrosoglutathione breakdown prevents airway smooth muscle relaxation in the guinea pig.

Airway levels of the endogenous bronchodilator S-nitrosoglutathione (GSNO) are low in children with near-fatal asthma. We hypothesized that GSNO could be broken down in the lung and that this catabolism could inhibit airway smooth muscle relaxation. In our experiments, GSNO was broken down by guinea pig lung homogenates, particularly after ovalbumin sensitization (OS). Two lung protein fractions had catabolic activity. One was NADPH dependent and was more active after OS. The other was NADPH independent and was partially inhibited by aurothioglucose. Guinea pig lung tissue protein fractions with GSNO catabolic activity inhibited GSNO-mediated guinea pig tracheal ring relaxation. The relaxant effect of GSNO was partially restored by aurothioglucose. These observations suggest that catabolism of GSNO in the guinea pig 1) is mediated by lung proteins, 2) is partially upregulated after OS, and 3) may contribute to increased airway smooth muscle tone. We speculate that enzymatic breakdown of GSNO in the lung could contribute to asthma pathophysiology by inhibiting the beneficial effects of GSNO, including its effect on airway smooth muscle tone.

Animals↗
PubMed2000

Endogenous airway acidification. Implications for asthma pathophysiology.

Airway concentrations of many reactive nitrogen and oxygen species are high in asthma. The stability and bioactivities of these species are pH-dependent; however, the pH of the airway during acute asthma has not previously been studied. As with gastric and urinary acidification, asthmatic airway acidification could be expected dramatically to alter the concentrations and bioactivities/cytotoxicities of endogenous nitrogen oxides. Here, we demonstrate that the pH of deaerated exhaled airway vapor condensate is over two log orders lower in patients with acute asthma (5.23 +/- 0.21, n = 22) than in control subjects (7.65 +/- 0.20, n = 19, p < 0. 001) and normalizes with corticosteroid therapy. Values are highly reproducible, unaffected by salivary or therapeutic artifact, and identical to samples taken directly from the lower airway. Further, at these low pH values, the endogenous airway compound, nitrite, is converted to nitric oxide (NO) in quantities sufficient largely to account for the concentrations of NO in asthmatic expired air, and eosinophils undergo accelerated necrosis. We speculate that airway pH may be an important determinant of expired NO concentration and airway inflammation, and suggest that regulation of airway pH has a previously unsuspected role in asthma pathophysiology.

Acid-Base Equilibrium↗
PubMed2000

[Quantitative analysis of 4(3)-quinazolinedione in 4 "daqingye", leave of Isatis indigotica, Baphicacanthus cusia, Polygonum tinctorium and Clerodendron cyrtophyllum].

Using 4(3)-quinazolinedione, the active constituent of "Daqingye", as the quality control criteria, 4 samples of the herbal drug collected from Isatis indigotica, Baphicacanthus cusia, Polygonum tinctorium and Clerodendron cyrtophyllum were comparetively analyzed by RP-HPLC. The results showed that the average 4(3)-quinazolinedione contents (microgram/g) were 30.7, 7.2, 4.4 and 27.5 respectively. This method was proved to be quick, simple and reproducible, and provided a reliable basis for the quality control and evaluation of Chinese Traditional Drug "Daqingye".

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed1999

Transfection of anti-sense complementary DNA of human epidermal-growth-factor receptor attenuates the proliferation of human non-small-cell-lung-cancer cells.

The proliferation of human non-small-cell-lung-cancer (NSCLC) cells is regulated by the epidermal-growth-factor-receptor (EGFR)-mediated autocrine loop that interacts with transforming growth factor-alpha (TGF-alpha) of autocrine or paracrine origin. We have shown that EGFR expression is elevated in the brain metastatic variant of human NSCLC cells H226Br, which thereby acquire their increased sensitivity toward exogenous TGF-alpha. To determine detailed cell-phenotype changes as a result of EGFR down-regulation, H226Br cells were transfected with a human EGFR-cDNA construct encompassing an N-terminal fragment (1.8 kb) in anti-sense orientation downstream of the cytomegalovirus (CMV) promoter. The EGFR transcript expressed in the 3'-5' direction is expected to neutralize EGFR mRNA and to reduce protein expression correspondingly. The established cell lines resistant to G418 were shown integrated with the transfected construct and their proliferation rates reduced as compared with the parental cells and with those transfected with vector alone. Down-regulated EGFR expression in cells with the anti-sense construct can be confirmed by Scatchard analysis and suppressed EGFR kinase activity. The restrained-growth phenotype is also demonstrated in the prolonged G2-M phase during the cell cycle, and correlated with impairment of cell proliferation. This finding suggests that EGFR over-expression is critical in maintaining the malignant phenotype of NSCLC cells, thereby providing a valuable biomarker and potential target prevention for lung-cancer-cell proliferation.

Carcinoma, Non-Small-Cell Lung↗
PubMed1999

Decreased levels of nitrosothiols in the lower airways of patients with cystic fibrosis and normal pulmonary function.

Airway S-nitrosothiols (SNOs) are naturally occurring bronchodilators. SNOs, nitrate, and nitrite were measured in bronchoalveolar lavage fluid of 23 patients with cystic fibrosis (CF) and mild pulmonary disease (aged 6-16 years) and 13 healthy children (aged 8-15 years). Concentrations of SNOs were decreased in the lower airways of patients with CF and mild pulmonary disease (median, range: 0, 0-320 nmol/L vs 80, 0-970 nmol/L) despite normal levels of the inert nitric oxide metabolites nitrate and nitrite (mean +/- SEM: 3.7 +/- 0.5 micromol/L vs 4.8 +/- 0.9 micromol/L). S-nitrosolation- mediated bioreactivities may be impaired by depletion of the CF airway SNO reservoir.

Adolescent↗
PubMed1999

Preparation and biological properties of biotinylated PhTX derivatives.

We report the synthesis of several highly functionalized biotinylated philanthotoxin (PhTX) analogues (7, 8, 10, 13-16) designed on the basis of earlier structure-activity relationship studies. Despite the extensive modifications, the binding to nicotinic acetylcholine receptor (nAChR) is in the low micromolar range according to an inhibition assay using 3H-thienylcyclohexyl-piperidine (TCP). A patch clamp functional assay gave comparable results. Compounds exemplified by 16, which consists of a biotinylated ligand linked to a bifunctional photoaffinity probe (BPP), represent a new type of probe which should find use in photo-crosslinking studies of ligand receptor interactions.

Animals↗