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Biomedical subjects

C M Chen

Publications and source records attributed to C M Chen.

At least 91 records · Page 5Linked to original sources
PubMed2000

Anti-aging effects of the traditional Chinese medicine bu-zhong-yi-qi-tang in mice.

Among the "alternative medicines," which may ably supplement modern Western medicine in the treatment of certain diseases, the holistic approach and mild nature of the majority of Traditional Chinese Medicine (TCM) may make it particularly suitable for the treatment of diseases associated with old age, as the general health of elderly patients is already compromised. The TCM formulation of bu-zhong-yi-qi-tang (B.Z.Y.Q.T.), prescribed mainly for the improvement of circulation and in particular that to the gastroenteric regions, may have anti-aging effects. In the present study, possible anti-aging effects of B.Z.Y.Q.T. were studied using normal (ICR) mice and the Dull, P/8 and R/1 strains of the Senescence Accelerated Mouse (S.A.M.). Following repeated oral administrations of B.Z.Y.Q.T. at 250 and 500 mg/kg the test mice were assessed for (1) endurance (2) learning and memory (3) neuromuscular coordination and (4) changes in the levels of monoamines in the brain. The results indicated that B.Z.Y.Q.T. improved endurance in all strains in a dose-dependent manner. At the higher dose of 500 mg/kg, it improved memory in the R/1 and P/8 S.A.M. mice. In prolonged rota-rod tests, which assessed both motor coordination and endurance, B.Z.Y.Q.T. significantly improved performance in the P/8 S.A.M. mice. Elevated dopamine and noradrenaline were observed in cortical tissues of the S.A.M./Dull and ICR mice respectively with the high dose of 500 mg/Kg, B.Z.Y.Q.T. Taken together, the results indicated that B.Z.Y.Q.T. appeared to exert anti-aging effects in mice and elevation in certain monoamines in brain cortical tissues. How and whether the monoamines changes after B.Z.Y.Q.T. treatment might be related to the behavioral effects await further investigation.

Aging↗
PubMed2000

An adaptive snake model for ultrasound image segmentation: modified trimmed mean filter, ramp integration and adaptive weighting parameters.

The snake model is a widely-used approach to finding the boundary of the object of interest in an ultrasound image. However, due to the speckles, the weak edges and the tissue-related textures in an ultrasound image, conventional snake models usually cannot obtain the desired boundary satisfactorily. In this paper, we propose a new adaptive snake model for ultrasound image segmentation. The proposed snake model is composed of three major techniques, namely, the modified trimmed mean (MTM) filtering, ramp integration and adaptive weighting parameters. With the advantages of the mean and median filters, the MTM filter is employed to alleviate the speckle interference in the segmentation process. The weak edge enhancement by ramp integration attempts to capture the slowly varying edges, which are hard to capture by conventional snake models. The adaptive weighting parameter allows weighting of each energy term to change adaptively during the deformation process. The proposed snake model has been verified on the phantom and clinical ultrasound images. The experimental results showed that the proposed snake model achieves a reasonable performance with an initial contour placed 10 to 20 pixels away from the desired boundary. The mean minimal distances from the derived boundary to the desired boundary have been shown to be less than 3.5 (for CNR > or = 0.5) and 2.5 pixels, respectively, for the phantom and ultrasound images.

Algorithms↗
PubMed2000

Acridone alkaloids from the root bark of Severinia buxifolia in Hainan.

Eight new acridone alkaloids, buxifoliadines-A--H together with nine known acridone compounds, were isolated and characterized from the root bark of Severinia buxifolia which was collected in Hainan province, China. Their structures were determined by spectroscopic methods. The relationship between acridone alkaloids with collecting area is discussed. The 13C-NMR spectra of the prenyl substituents at C-2 and/or C-4 of N-unsubstituted acridone alkaloids are also discussed.

Acridines↗
PubMed2000

Clinical and epidemiological implications of swine hepatitis E virus infection.

In nonendemic areas, most patients with acute hepatitis E were infected through traveling to endemic areas. However, some patients did not have a history of foreign travel before infection. Furthermore, high seroprevalence rates of antibody to hepatitis E virus (anti-HEV) were found in the general adult population in some countries without any recorded outbreak of hepatitis E. The significance of anti-HEV assay in these subjects remains obscure. To study if swine might be a source of HEV infection, HEV was tested in sera of 235 pigs in Taiwan, and from 5 patients with acute HEV infection who either denied or did not provide any foreign travel history. Three (1.3%) pigs had detectable swine HEV RNA. The swine and human HEV strains from Taiwan formed a monophyletic group, distinct from three previously reported groups: the United States human and swine HEV strains, the Mexico strain, and the largest group composed of the Asian and the African strains. The identity of nucleotide sequences was 84-95% between swine and human HEV strains in Taiwan, and 72-79% between Taiwan strains and those from different areas. The predicted amino acid sequence of a Taiwan swine HEV strain within the peptide 3-2 used in commercial anti-HEV assay showed a high identity (91-94%) with those of other human and swine HEV strains. Swine may be a reservoir of HEV and subclinical swine HEV infection may occur. Cross-reactivity of current anti-HEV assay may account for the high prevalence rate of anti-HEV in the general population in nonendemic areas.

Adult↗
PubMed2000

Treatment of acetabular fractures: 10-year experience.

BACKGROUND: Acetabular fracture is a controversial and difficult fracture to manage. We retrospectively evaluated the outcome of the traditional management of acetabular fractures. METHODS: From 1987 to 1996, 112 cases of acetabular fracture presented at the Taipei Veterans General Hospital and were managed surgically in 73 cases and nonsurgically in 39 cases. The follow-up period was 90 (36-140) months. RESULTS: In the nonsurgically managed group, congruent reduction was achieved in 29 cases (74.3%) and good to excellent functional results were achieved in 25 cases (64.1%). In the surgically managed group, congruent reduction was achieved in 60 cases (82.2%) and good to excellent functional results were achieved in 57 cases (74.3%). In 51 (45.5%) cases, early or late complications developed after management, including one femoral artery perforation, one screw penetration, three wound infections, one iatrogenic sciatic nerve injury, one deep vein thrombosis, 21 heterotopic ossifications, two chondrolyses, three avascular necroses of the femoral head and 18 cases of symptomatic traumatic arthritis. CONCLUSIONS: The functional results correlated well with the final congruity of the joints and the severity of the complications.

Acetabulum↗
PubMed2000

Locoregional recurrence in patients with one to three positive axillary nodes after mastectomy without adjuvant radiotherapy.

PURPOSE: To retrospectively assess the risk of locoregional recurrence (LRR) and analyze the prognostic factors of this pattern of failure in patients with breast cancer and one to three positive axillary lymph nodes treated with modified radical mastectomy (MRM) without adjuvant radiotherapy. METHODS: From April 1991 through December 1997, 649 patients received a diagnosis of invasive breast cancer, and 545 were treated with MRM. Eighty-one of these patients who were found to have one to three positive axillary nodes and had a minimum follow-up of 2 years were included in this study. None of the 81 patients received adjuvant radiation therapy after mastectomy; 43 patients received adjuvant chemotherapy; and 60 patients received adjuvant hormone therapy. The median duration of follow-up was 39 months. RESULTS: Thirteen patients had LRR during follow-up, all within 2 years after mastectomy. The 3-year LRR rate was 14%. The 3-year rates of distant metastasis for patients with and without LRR were 48% and 14% (p = 0.03), respectively. The 3-year survival rates for patients with and without LRR were 73% and 87% (p = 0.01), respectively. In univariate analysis, age (p = 0.01), estrogen receptor (ER) status (p = 0.02), and the addition of hormone therapy (p < 0.001) were significant risk factors for LRR; in multivariate analysis, negative ER status (p = 0.02) was the only statistically significant risk factor. The 3-year LRR rates for ER-negative patients and those with positive or unknown ER status were 31% and 11%, respectively. CONCLUSIONS: LRR after mastectomy is a substantial clinical problem, despite the use of adjuvant chemotherapy and/or hormone therapy. Further randomized trials of postmastectomy radiotherapy for patients with one to three positive axillary nodes and specific risk factors are urgently needed to determine its potential benefit in locoregional control and survival, especially for young and ER-negative patients.

Adult↗
PubMed1999

Production and design of more effective avian replication-incompetent retroviral vectors.

Retroviral vectors have been invaluable tools for studies of development in vertebrates. Their use has been somewhat constrained, however, by the low viral titers typically obtained with replication-incompetent vectors, particularly of the avian type. We have addressed this problem in several ways. We optimized the transient production of avian replication-incompetent viruses in a series of cell lines. One of the optimal cell lines was the mammalian line 293T, which was surprising in light of previous reports that avian viral replication was not supported by mammalian cells. We also greatly increased the efficiency of viral infection. Pseudotyping with the vesicular stomatitus virus G (VSV-G) protein led to an over 350-fold increase in the efficiency of infection in ovo relative to infection with virus particles bearing an avian retroviral envelope protein. To further increase the utility of the system, we developed new Rous sarcoma virus (RSV)-based replication-incompetent vectors, designed to express a histochemical marker gene, human placental alkaline phosphatase, as well as an additional gene. These modified retroviral vectors and the VSV-G pseudotyping technique constitute significant improvements that allow for expanded use of avian replication-incompetent viral vectors in ovo.

Animals↗
PubMed1999

Induction of cell death by tumour necrosis factor (TNF) receptor 2, CD40 and CD30: a role for TNF-R1 activation by endogenous membrane-anchored TNF.

Several members of the tumour necrosis factor receptor (TNF-R) superfamily can induce cell death. For TNF-R1, Fas/APO-1, DR3, DR6, TRAIL-R1 and TRAIL-R2, a conserved 'death domain' in the intracellular region couples these receptors to activation of caspases. However, it is not yet known how TNF receptor family members lacking a death domain, such as TNF-R2, CD40, LT-betaR, CD27 or CD30, execute their death-inducing capability. Here we demonstrate in different cellular systems that cytotoxic effects induced by TNF-R2, CD40 and CD30 are mediated by endogenous production of TNF and autotropic or paratropic activation of TNF-R1. In addition, stimulation of TNF-R2 and CD40 synergistically enhances TNF-R1-induced cytotoxicity. These findings describe a novel pro-apoptotic mechanism induced by some members of the TNF-R family.

Animals↗
PubMed1999

Use of a fluorescence plate reader for measuring kinetic parameters with inner filter effect correction.

A general method is presented here for the determination of the Km, kcat, and kcat/Km of fluorescence resonance energy transfer (FRET) substrates using a fluorescence plate reader. A simple empirical method for correcting for the inner filter effect is shown to enable accurate and undistorted measurements of these very important kinetic parameters. Inner filter effect corrected rates of hydrolysis of a FRET peptide substrate by hepatitis C virus (HCV) NS3 protease at various substrate concentrations enabled measurement of a Km value of 4.4 +/- 0.3 microM and kcat/Km value of 96,500 +/- 5800 M-1 s-1. These values are very close to the HPLC-determined Km value of 4.6 +/- 0.7 microM and kcat/Km value of 92,600 +/- 14,000 M-1 s-1. We demonstrate that the inner filter effect correction of microtiter plate reader velocities enables rapid measurement of Ki and Ki' values and kinetic inhibition mechanisms for HCV NS3 protease inhibitors.

Filtration↗
PubMed1999

Analysis of saponins from black bean by electrospray ionization and fast atom bombardment tandem mass spectrometry.

Saponins from black bean (Vigna mungo L. Hepper) were analyzed using positive and negative ion fast atom bombardment mass spectrometry (FAB-MS) and liquid chromatography/mass spectrometry. Methanol was used to extract the saponins from defatted black bean, which was partially purified by extraction with n-butanol, and the extract was dialyzed with 3000 M(r) cut-off tubing. The dialyzate was analyzed using mass spectrometry. According to FAB-MS/MS, mixtures from black bean contain soyasaponin I as the predominant saponin. In addition, MS/MS analysis was performed in which the structures of saponins of black bean cotyledon were determined to be soyasaponin I, soyasaponin II, soyasaponin V, 3-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-galactopyranosyl-(1 --> 2)-beta-D-glucuronopyranosyl]complogenin (saponin A) and 3-O-[alpha-L-rhamnopyranosyl-(1 --> 2)-beta-D-glucopyranosyl-(1 --> 2)-beta-D-glucopyranosyl]oleanolic acid (saponin B). For the black bean shell and the root of black bean sprout, analysis confirmed the saponins of soyasaponin I, soyasaponin II, soyasaponin V, saponin A, saponin B, acetylsoyasaponin A(4) and soyasaponin beta(g). Moreover, all the studied saponins were found in the stem and leaves of the black bean sprouts, except soyasaponin beta(g) and acetylsoyasaponin A(4), respectively.

Carbohydrate Sequence↗
PubMed1999

Gender determination in single bovine blastomeres by polymerase chain reaction amplification of sex-specific polymorphic fragments in the amelogenin gene.

A sensitive technique for the sexing of bovine embryos was developed using polymerase chain reaction (PCR) amplification of the bovine amelogenin (bAML) gene on the X- and Y-chromosomes of Holstein dairy cattle. Cloning and DNA sequencing showed a 45.1% homology between the fifth intron of the bAML-X and bAML-Y gene with multiple deletions. A pair of sex-specific primers was designed to allow amplification of a single fragment of 467-bp from the X-chromosome of female cattle and two fragments of 467-bp and 341-bp from the X- and Y-chromosomes of male cattle. The primers were successfully applied to bovine sexing from single blastomeres isolated from day-6 to day-7 cow embryos by direct cell lysis and PCR. Our protocol of embryo sexing should be applicable to the diagnosis of defective genes in vitro in human embryos and in other domestic or recreational animals.

Amelogenin↗
PubMed1999

Relaxant effects of quercetin methyl ether derivatives in isolated guinea pig trachea and their structure-activity relationships.

In the present study, we attempted to compare quercetin methyl ethers and to look for the structure-activity relationships, which may be helpful for synthesizing more active compounds for the treatment of asthma. Four present and two previously studied quercetin methyl ethers concentration-dependently relaxed histamine (30 microM), carbachol (0.2 microM) and KCl (30 mM) induced precontraction. According to their IC25 values to histamine-induced precontraction, the potency order was quercetin 3,3',4,'5,7-pentamethyl ether (QPME), quercetin 3-methyl ether > quercetin, quercetin 3,4',7-trimethyl ether (ayanin) > quercetin 4'-methyl ether (tamarixetin), quercetin 3,3',4',7,-tetramethyl ether (QTME). Therefore, the methylation at 3, at 5, and at both 3 and 7 positions of the A or/and C ring of quercetin nucleus may increase their tracheal relaxant activity. However, the methylation at the 3' and at the 4' position of the B ring of quercetin nucleus may decrease their tracheal relaxant activity.

Animals↗
PubMed1999

Detection of methyl ethyl ketone in urine using headspace solid phase microextraction and gas chromatography.

Headspace solid-phase microextraction coupled with gas chromatography/flame ionization detection was developed to measure urinary methyl ethyl ketone (MEK). A fused silica fiber coated with 75 microns carboxen/polydimethylsiloxane was used to extract urinary MEK. The optimal extraction conditions were obtained when temperature was 50 degrees C, extraction time was 15 minutes, and ammonium sulfate concentration was 0.5 g/mL. The optimal desorption temperature and time were 200 degrees C and 5 minutes, respectively. The concentration range of calibration curves was 27 to 8000 ng/mL of MEK. The within-day and between-day pooled coefficients of variation (9 concentrations, triplicate samples) were 5.4% and 8.8%, respectively. The limit of detection and limit of quantitation were 4.2 ng/mL and 21.6 ng/mL, respectively. The recovery (+/- standard deviation) of MEK was 100.2% +/- 8.6% (n = 3). MEK in urine was stable for at least 1 month when stored at -20 degrees C. This method proved to be applicable for the analysis of urinary MEK of exposed workers in a plastic material printing plant. We concluded that this new method is sensitive, inexpensive, simple, and reliable for measuring the occupational exposure of MEK.

Adult↗
PubMed1999

Theory for the bending anisotropy of lipid membranes and tubule formation.

We study the spontaneous symmetry breaking of the bending rigidity of lipid membranes in two principal directions by a Landau mean-field theory. When the temperature is below the tilting temperature (T(c)), the coupling between molecular orientation and membrane local curvature square leads to an increase of the bending rigidity in the tilting direction and therefore a spontaneous symmetry breaking in two principal directions. The asymmetry (Delta) of the bending rigidity undergoes a continuous change upon cooling and grows as T(c)-T for T<T(c). We discuss this anisotropical effect on the tilt structure of the ripple phase P(beta(')) of a nearly flat membrane and the sphere-to-tubule transition in a dilute solution of lipids. The transition between the spherical vesicle phase and the tubular phase is predicted to be first order.

Anisotropy↗
PubMed1999

DNA cleavage activities of Staphylococcus aureus gyrase and topoisomerase IV stimulated by quinolones and 2-pyridones.

We have cloned Staphylococcus aureus DNA gyrase and topoisomerase IV and expressed them in Escherichia coli as polyhistidine-tagged proteins to facilitate purification and eliminate contamination by host enzymes. The enzyme preparations had specific activities similar to previously reported values. Potassium glutamate (K-Glu) stimulated the drug-induced DNA cleavage activity and was optimal between 100 and 200 mM for gyrase and peaked at 100 mM for topoisomerase IV. Higher concentrations of K-Glu inhibited the cleavage activities of both enzymes. Using a common buffer system containing 100 mM K-Glu, we tested the enzyme-mediated DNA cleavage activities of both gyrase and topoisomerase IV with oxolinic acid, norfloxacin, ciprofloxacin, trovafloxacin, clinafloxacin, and the 2-pyridone ABT-719. As expected, all drugs tested demonstrated greater potency against topoisomerase IV than against gyrase. In addition, cleavage activity was found to correlate well with antibacterial activity.

Anti-Bacterial Agents↗