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Biomedical subjects

X Q Chen

Publications and source records attributed to X Q Chen.

At least 19 recordsLinked to original sources
PubMed2006

Cytotoxicity of Marchantia convoluta leaf extracts to human liver and lung cancer cells.

The cytotoxicity of three extracts (petroleum ether, ethyl acetate and n-butanol) from a plant used in folk medicine, Marchantia convoluta, to human non-small cell lung carcinoma (H1299) and liver carcinoma (HepG2) cell lines was tested. After 72-h incubation of lung and liver cancer cell cultures with varying concentrations of extracts (15 to 200 microg/mL), cytotoxicity was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and reported in terms of cell viability. The extracts that showed a significant cytotoxicity were subjected to gas chromatography-mass spectrometry analysis to identify the components. The ethyl acetate, but not the petroleum ether or n-butanol extract, had a significant cytotoxicity against lung and liver carcinoma cells with IC50 values of 100 and 30 microg/mL, respectively. A high concentration of ethyl acetate extract (100 microg/mL) rapidly reduced the number of H1299 cells. At lower concentrations of ethyl acetate extract (15, 30, and 40 microg/mL), the numbers of HepG2 cells started to decrease markedly. Gas chromatography-mass spectrometry analysis of the ethyl acetate extract revealed the presence of several compounds such as phytol (23.42%), 1,2,4-tripropylbenzene (13.09%), 9-cedranone (12.75%), ledene oxide (7.22%), caryophyllene (1.82%), and caryophyllene oxide (1.15%). HPLC analysis result showed that there were no flavonoids in ethyl acetate extract, but flavonoids are abundant in n-butanol extract. Further studies are needed regarding the identification, toxicity, and mechanism of action of active compounds.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Application of an effective method in predicting breakthrough curves of fixed-bed adsorption onto resin adsorbent.

Removal of many organic pollutants including phenolic compounds from industrial wastewater can always be achieved by fixed-bed adsorption onto the polymeric resin adsorbent, and the relevant breakthrough curves would provide much valuable information to help to design a fixed-bed adsorption process in field application. In the present study, a model developed based on the constant-pattern wave approach theory and the Freundlich model was adopted to describe the breakthrough curves of phenol and p-nitrophenol adsorption onto a macroreticular resin adsorbent NDA-100 from aqueous solution. Column experiments were performed at different conditions to verify the model and the results proved that the model would describe the breakthrough curves well. Effect of the operation parameters on breakthrough curves was also discussed to get helpful information in choosing the adsorption process.

Adsorption↗
PubMed2005

The role of high-frequency jet ventilation in the treatment of Cheyne-Stokes respiration in patients with chronic heart failure.

BACKGROUND: Cheyne-Stokes respiration with central sleep apnea (CSR-CSA) is common in patients with severe cardiac failure. Various modes of positive airway pressure have been suggested as treatments. The authors hypothesized that high frequency jet ventilation (HFJV) can improve central sleep apnea in patients with chronic heart failure. METHODS: Eleven subjects with stable, optimally treated chronic heart failure and Cheyne-Stokes respiration were tested untreated and on four treatment nights in random order: nasal oxygen (4 L/min), continuous positive airway pressure (CPAP) (mean 9.3 cm H(2)O), bilevel positive airway pressure (BiPAP)(mean 12.0/5.3 cm H(2)O), or HFJV(60 approximately 80 breaths per minute) during polysomnography (EMBLA, Flaga, Reykjavik, Iceland). RESULTS: The apnea-hypopnea index (AHI) declined from 30.9 +/- 8.3/h in untreated night to 23.6 +/- 6.6/h oxygen night and 18.5 +/- 5.0/h CPAP, 14.3 +/- 3.9/h BiPAP, and 20.1 +/- 4.1/h HFJV (all P < 0.001 versus control). There was no significant difference between the AHI of HFJV and that of CPAP (P = 0.541). Arousal index decreased from 31.4+/-13.2/h untreated to 25.0 +/- 7.1/h oxygen and 13.6 +/- 4.7/h CPAP, to 13.7 +/- 4.9/h BiPAP and 14.4 +/- 4.7/h HFJV. HFJV had the similar effect to the other therapeutic groups in arousal index (P > 0.05). There were large increases in slow-wave and rapid eye movement (REM) sleep with HFJV. All subjects preferred HFJV to CPAP. CONCLUSIONS: One night of therapy with HFJV improved nocturnal breathing pattern and sleep quality in patients with Cheyne-Stokes respiration in chronic heart failure. HFJV therapy for sleep and breathing were the same as those during a nasal CPAP night. A long-term study of the effect of HFJV on cardiovascular function is needed.

Aged↗
PubMed2001

Suppression of pulmonary antibacterial defenses mechanisms and lung damage in mice exposed to fluoride aerosol.

In endemic fluorosis areas in China associated with coal burning, indoor airborne fluoride pollution is severe. To determine the effects of fluoride aerosols on pulmonary antibacterial defense mechanisms and lung damage, mice were exposed to various concentrations of fluoride aerosol (2, 5, or 10 mg/m3) or filtered air (control) for 14 d, 4 h/d in an inhalation chamber. Bactericidal activity against Staphylococcus aureus in the lung and the number and profile of free pulmonary cells, protein content, and lactate dehydrogenase (LDH) activity in bronchoalveolar lavage (BAL) fluid were assessed. Urinary fluoride concentration, an indicator of fluoride exposure, increased in proportion to fluoride aerosol concentration in the chamber. Wet lung weight was significantly higher on d 14 in mice exposed to 10 mg/m3 than in controls. Pulmonary bactericidal activity against S. aureus was concentration-dependently suppressed at 5 and 10 mg/m3 fluoride. The number of alveolar macrophages (AMs) in the BAL fluid of the mice not bacterially challenged decreased significantly at 10 mg/m3 fluoride. The number of polymorphonuclear leukocytes and lymphocytes increased significantly at 10 mg/m3 fluoride exposure. The concentration of total protein (TP) and albumin in BAL supernatant increased significantly at 5 and 10 mg/m3 fluoride exposure, and LDH activity rose markedly at the higher fluoride concentration. Data indicate that fluoride inhalation produces pulmonary cellular alterations that are associated with a diminished ability to cope with infectious bacteria.

Aerosols↗
PubMed2001

Characteristic aroma components of British Farmhouse Cheddar cheese.

Aroma components responsible for aroma typical of British Farmhouse Cheddar cheese were studied by aroma extract dilution analysis. Cheese extracts were prepared by direct solvent extraction, high-vacuum transfer, and class fractionation. Most aroma-active components of acidic and neutral/basic fractions have been previously associated with Cheddar cheese flavor. p-Cresol was mainly responsible for a "cowy-barny" note, whereas an intense "soil-like" note was due to 2-isopropyl-3-methoxypyrazine. At much lower odor intensity, 2-isobutyl-3-methoxypyrazine contributed a "bell pepper-like" note. Additionally, within the same wedge of cheese, the concentrations of p-cresol and 2-isopropyl-3-methoxypyrazine were lower at the narrow end (center) than at the rind side. Direct addition of p-cresol (> or =100 ppb) or 2-isopropyl-3-methoxypyrazine (> or =3 ppb) in a mild domestic Cheddar cheese resulted in increases in intensities of cowy/phenolic and earthy/bell pepper aroma notes.

Animals↗
PubMed2001

Evaluation of diagnostic criteria for atopic dermatitis: validity of the criteria of Williams et al. in a hospital-based setting.

BACKGROUND: Surveys of the prevalence of atopic dermatitis (AD) have been carried out world-wide, but the results vary widely. The differences probably result from the use of different diagnostic criteria. Williams et al. proposed minimum, simplified, diagnostic criteria that require no invasive test and are easy to use. Pilot studies in European countries showed their suitability for implementation both in hospitals and in the community, and their high sensitivity and specificity. OBJECTIVES: To evaluate the potential practical value of the criteria of Williams et al. in the Chinese population. METHODS: The criteria of Hanifin and Rajka (gold standard), Williams et al. and Kang and Tian were applied and compared in 111 patients with AD and 121 control subjects with other skin diseases in three out-patient centres in China. RESULTS: The criteria of Williams et al. showed a similar diagnostic efficiency to that of the gold standard, with the sensitivity, specificity and kappa value reaching 95.50%, 97.52% and 0.93, respectively. No significant difference was found between the criteria of Williams et al. and those of Kang and Tian (chi2 = 0.69, P > 0.05). 'Onset under the age of 2 years', a criterion of Williams et al. could be used in subjects of any age. CONCLUSIONS: The diagnostic efficiency of the criteria of Williams et al. was basically similar to those of Hanifin and Rajka and of Kang and Tian in our out-patient settings. However, those of Williams et al. were easier to apply and required no invasive tests.

Adolescent↗
PubMed2000

Similar potency of the enantiomers of huperzine A in inhibition of [(3)H]dizocilpine (MK-801) binding in rat cerebral cortex.

The inhibition of huperzine A, a potential therapeutic agent to treat Alzheimer's disease, on rat cortical acetylcholinesterase was found to be highly stereospecific. In the present study the effect of the enantiomers of huperzine A on [(3)H]dizocilpine (MK-801) binding to synaptic membrane of rat cerebral cortex was compared. The natural (-)-huperzine A and the synthetic (+)-huperzine A inhibited the specific binding of [(3)H]MK-801 with a similar potency. The IC(50) values were 65+/-7 and 82+/-12 microM (n=5 for each enantiomer, P=0.248), respectively. The result indicates that huperzine A inhibits N-methyl-D-aspartate (NMDA) receptor in rat cerebral cortex without stereoselectivity.

Alkaloids↗
PubMed2000

[The vitronectin anchors on placenta tissue of hypertensive pregnancy].

Using immunohistochemistry staining and Western-blot techniques, we detected the distribution and content of vitronectin antigen in placenta tissue of one case of hypertensive pregnancy in order to explore pathogenesis of the development of hypertensive pregnancy. The results were that vitronectin expressions on hypertensive pregnant placenta were obviously higher than those on normal placenta, which suggests that fibrin deposition on placenta tissue was associated with suppression of fibrinolysis.

Female↗
PubMed2000

Hypoxia influences enkephalin release in rats.

To investigate hypoxia effects on leucine-enkephalin (L-ENK) levels of median eminence (ME) of hypothalamus in rats, and the possible glucocorticoid involvement in modulation. Hypoxia was stimulated in a hypobaric chamber. L-ENK levels were measured by specific radioimmunoassay during acute, and a comparison of L-ENK alteration was taken for bilateral adrenalectomy (ADX) with or without a replacement of dexamethasone (DEX). Acute hypoxia 10.8% O2 for 30 min and 2 h markedly enhanced L-ENK levels of ME from 23.99+/-7.25 in control to 51.26+/-16.96 (P<0.01) and 53.29+/-26.10 ng/mg protein (p<0.01), and acute hypoxia at 8.2% O2 significantly increased L-ENK of ME to 36.76+/-15.25 (p<0.05) and 32.09+/-3.58 ng/mg protein (p<0.05). The increased L-ENK was returned to normoxic level when hypoxia (10.8% O2) exposure lasted for 24 h. After ADX, 10.8% O2 hypoxia induced a sharp decline of L-ENK in the ME, but this decline was completely reversed by treatment with DEX (500 microg/rat, i.p.). Acute hypoxia increases L-ENK level of hypothalamic ME in rats, which may present a reduced and/or inhibited release of L-ENK, acting through a fast negative feedback mechanism of acute hypoxia activated high circulating glucocorticoid level.

Acute Disease↗
PubMed2000

Hypoxia influences somatostatin release in rats.

The impact of hypoxia on somatostatin (SS) secretion from the median eminence (ME) of the hypothalamus and the possible glucocorticosteroid involvement in modulating secretion, were investigated in adult male rats exposed to hypoxia. SS levels were measured by specific radioimmunoassay during acute and prolonged hypoxia as well as after bilateral adrenalectomy (ADX) with or without a replacement with dexamethasone (DEX). The results were as follows: (a) acute hypoxia (5 km altitude, 10.8% O(2)) for 2 and 24 h markedly increased SS content in ME, but acute severe hypoxia (7 km, 8.2% O(2) for 24 h) markedly decreased SS level in ME. (b) Chronic hypoxia (10.8% O(2)) from 5 to 25 days exposure did not significantly affect SS content of ME. (c) ADX alone increased SS content of ME and this increase was further enhanced after 2 h exposure to hypoxia. (d) The increased SS in ME of ADX rats was blocked by replacement with DEX (500 microg/rat i.p.). The data presented suggest that acute hypoxia stress may increase or decrease SS content of ME in rats, depending on the severity and duration of the hypoxia and that the stimulatory action of hypoxia on SS content of ME be may in part mediated by the increased corticosterone levels during hypoxia.

Acute Disease↗
PubMed2000

Microsatellite alterations and TP53 mutations in plasma DNA of small-cell lung cancer patients: follow-up study and prognostic significance.

BACKGROUND: Small-cell lung cancer (SCLC), one of the major types of lung cancer, is associated with many different somatic molecular genetic changes. These alterations, observed in tumor DNA, have also been identified in the plasma DNA of patients. We undertook the present study to make a prospective investigation into the correlation between abnormal plasma DNA and patient survival. PATIENTS AND METHODS: Thirty-five patients with SCLC were selected after histological diagnosis. Polymorphic markers (ACTBP2, UT762 and AR) were chosen for their reported high rate of alterations in SCLC and analyzed in tumor tissue, normal blood cells and plasma DNA. Furthermore, we looked for mutations of the TP53 gene in tumor and plasma DNA. RESULTS: In 25 patients (71%) at least one molecular change precisely matching that of the primary tumor was detected in the plasma DNA. No difference in survival was observed between patients with aberrant plasma DNA and patients without plasma DNA alterations. However, patients with microsatellite modifications and TP53 mutations concomitantly, showed a significant difference (P = 0.02) in survival compared with patients bearing only one of these molecular changes. In 15 cases it was possible to find a correlation either between tumor response and disappearance of abnormal plasma DNA, or tumor progression and persistence of plasma DNA alterations. CONCLUSIONS: Free plasma DNA with molecular alterations is present to a high degree in plasma DNA of SCLC patients and may have a role as a prognostic factor.

Adult↗
PubMed2000

Detection of microsatellite alterations in the DNA isolated from tumor cells and from plasma DNA of patients with lung cancer.

In this paper, we show that the same panel of three microsatellite markers is useful for the detection of alterations in the DNA of tumor cells and plasma from patients diagnosed with SCLC and NSCLC. In 31% of the SCLC patients, we detected a microsatellite alteration(s) or LOH in at least one locus. In the group of patients diagnosed with NSCLC, a microsatellite alteration or LOH was detected in at least one locus in 33% of the patients. In all but 2 patients, the identical alteration observed in the DNA from tumor cells was also detected in the DNA isolated from blood plasma. This work confirms the results described by other groups and it extends the diagnostic possibilities of finding tumor cell-specific DNA alterations also in the DNA freely circulating in plasma and serum of patients with cancer.

Adult↗
PubMed2000

Loss of heterozygosity at the ACTBP2 locus in lung cancer detected on Elchrom precast Spreadex gels.

One of the most important goals in the continuous struggle against cancer is early detection of the disease by a simple method that can be used in routine laboratory practice. According to several recent reports, early detection may be achieved by monitoring alterations at several microsatellite loci containing tri- and tetranucleotide repeats. The method relies on comparison of the intensity of allele bands in cancer tissue, plasma, and lymphocytes of a patient. Microsatellite instability is typically detected by labeling the DNA with a radioactive probe or a fluorescent dye followed by electrophoresis on 20-40-cm-long denaturing polyacrylamide gels. In this study, we show that loss of heterozygosity at the ACTBP2 locus in lung cancer patients can be detected using the Elchrom electrophoresis system and just 4-cm-long precast Spreadex gels.

Actins↗
PubMed2000

Survival of Escherichia coli O157:H7 in buttermilk as affected by contamination point and storage temperature.

The effects of contamination point (during fermentation versus postfermentation) and storage temperature (5 and 12 degrees C) were determined for survival of Escherichia coli O157:H7 in fermented buttermilk. E. coli O157:H7 was recovered from buttermilk inoculated during fermentation for 22 days and in buttermilk inoculated postfermentation for 32 days. For storage temperatures of 5 and 12 degrees C, D-values were lower for E. coli O157:H7 inoculated during fermentation (2.5, 2.2 days) than postfermentation (5.6, 4.8 days) (P < 0.05). Developed acidity in inoculated buttermilks was not different from controls (P > 0.05). The extended recovery of viable enterohemorrhagic E. coli O157:H7 from both processing scenarios indicates that the presence of E. coli O157:H7 in buttermilk is not limited to postprocessing contamination.

Animals↗
PubMed2000

Telomerase RNA as a detection marker in the serum of breast cancer patients.

Tumor-derived circulating DNA has been found in the plasma of cancer patients. Alterations include decreased strand stability, mutations of oncogenes or of tumor suppressor genes, microsatellite alterations, and hypermethylation of several genes. RNA has also been found circulating in the plasma of normal subjects and cancer patients. Tyrosinase mRNA has been extracted from the serum of melanoma patients and subjected to RT-PCR. Moreover, the presence of cell-free EBV-associated RNA has been reported in the plasma of patients with nasopharyngeal carcinoma. Human telomerase comprises two RNA subunits, telomerase RNA template (hTR) and its catalytic component, telomerase reverse transcriptase protein (hTERT). Expression of these subunits correlates with telomerase activity. Using RT-PCR, we investigated whether these RNA subunits were present in the serum of 18 patients with breast cancer, 2 patients with benign breast disease, and 21 normal subjects. The presence of amplifiable RNA was confirmed in all tissue and serum samples using RT-PCR of glyceraldehyde-3-phosphate dehydrogenase RNA. hTR was found in 17 of 18 tumors (94%) and 5 of 18 serum samples (28%). hTERT was also detected in 17 of 18 tumors (94%) and in 4 of 16 available serum samples (25%). hTR and hTERT were undetectable in tissues and sera taken from 2 patients with benign disease and in the sera of 21 normal subjects. We conclude that RNA is detectable in the serum of breast cancer patients and that tumor-derived mRNA can be extracted and amplified using RT-PCR, even in patients with localized disease. This may have implications for cancer diagnosis and follow-up in the future.

Aged↗
PubMed1999

Comparison of the effects of cholinesterase inhibitors on [3H]MK-801 binding in rat cerebral cortex.

Huperzine A, a selective inhibitor of acetylcholinesterase, was recently demonstrated to exert an antagonist effect on N-methyl-D-aspartate (NMDA) receptor in rat cerebral cortex. In the present study, the effects of six cholinesterase inhibitors, e.g. huperzine A, huperzine B, tacrine, donepezil (E2020), physostigmine and galanthamine on [3H]dizocilpine (MK-801) binding to synaptic membrane of rat cerebral cortex were compared. Their IC50 values (mean +/- SD) were 36.9 +/- 12.1, 316.8 +/- 93.2, 33.2 +/- 3.7, 135.0 +/- 15.1, 50.4 +/- 7.4, and 3344 +/- 295 microM, respectively. The rank order of potency is tacrine approximately huperzine A > physostigmine > donepezil > huperzine B >> galanthamine. There is no correlation between their activities to inhibit [3H]MK-801 binding and to inhibit acetylcholinesterase (r = +0.563, P = 0.245). The results suggest that most cholinesterase inhibitors available exhibit an antagonist effect on NMDA receptor in rat cerebral cortex in addition to their inhibitory effect on acetylcholinesterase.

Alzheimer Disease↗