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Biomedical subjects

C P Liu

Publications and source records attributed to C P Liu.

At least 19 recordsLinked to original sources
PubMed2006

Screening and analysis of bioactive compounds in traditional Chinese medicines using cell extract and gas chromatography-mass spectrometry.

As the cost of drug development is always many times more than that of drug discovery, predictive methods aiding in the screening of bioavailable drug candidates are of profound significance. In this paper, a novel method for screening bioactive compounds from traditional Chinese medicines (TCMs) was developed by using living cell extract and gas chromatography (GC)-mass spectrometer (MS). The method was validated by using elemene emulsion injection (EEI), a typical TCM with known active compound, to interact with murine ascites hepatocarcinoma cell strain with high metastatic potential (HCa-F). Finally, the method was applied to screen the bioactive compounds from multi-component zedoary turmeric oil and glucose injection (ZTOGI). After HCa-F cells was incubated in ZTOGI, ethyl acetate (EtOAc) was used to extract the compounds in the cells for GC-MS analysis. Fourteen compounds were detected in the desorption eluate of HCa-F cell extract of ZTOGI, and further identified by MS. Curzerene and beta-elemene were found to be two major bioactive compounds in ZTOGI. These results show that the method developed may be applied to quickly screen the potential bioactive components in TCMs interacting with the target cells.

Animals↗
PubMed2006

Effect of buffer species on the thermally induced aggregation of interferon-tau.

It is now becoming apparent that a common pathway of protein aggregation involves the unimolecular structural rearrangement from the native state to a slightly expanded aggregation-competent species. It is the goal of this study to understand the aggregation and the effects of buffer on the stability of IFN-tau. In this study, the thermally-induced aggregation of interferon-tau (IFN-tau) is described. By monitoring the aggregation rate in the presence of increasing amounts of sucrose, the relative change in surface area (Deltas) for conversion to the aggregation-competent state can be determined. Under conditions of pH 7 and in 20 mM buffer, the protein displays different aggregation rates depending on the nature of the buffer species. The protein aggregates mostly quickly in phosphate buffer, slower in the presence of Tris and slowest in the presence of histidine. The largest value for Deltas occurs for the histidine-containing samples, where aggregation proceeds via a slightly expanded aggregation competent state with a surface area increase of 7.6%. Furthermore, it appears that histidine binds to the native state of IFN-tau, thereby stabilizing the native state and retarding aggregation. Measurement of the second virial coefficient, B(22), for different formulations indicates that inclusion of histidine has only a small effect on repulsion between protein molecules, suggesting that colloidal stabilization is not the dominant mechanism for stabilization of IFN-tau. This study represents the first detailed biophysical study of specific buffer-induced stabilization, resulting in shifting the equilibrium towards the native state and away form the expanded aggregation-competent species.

Animals↗
PubMed2005

Solution behavior of a novel type 1 interferon, interferon-tau.

Interferon-tau (IFN-tau) is a novel cytokine that appears during fetal development of mammals. It is currently being investigated for treatment of viral infections and autoimmune diseases. In order to develop a commercial product, a stable formulation will need to be identified. In this study, the solution behavior of IFN-tau was studied using a variety of biophysical methods. The overall structure of IFN-tau is well defined, with the polypeptide chain folding into a four-helix bundle structure, much like other type 1 interferons. However, its solution behavior has not been characterized. The globular structure has a free energy of unfolding of approximately 4 kcal/mole at room temperature. IFN-tau was found to remain monomeric upon increasing the protein concentration, even up to 60 mg/mL. The overall structure of IFN-tau is maintained across a pH range of 2-8, but is significantly altered in the presence of nonaqueous solvents. However, IFN-tau appears to refold efficiently when diluted into an aqueous medium from a nonaqueous solution. This behavior allows the protein to be formulated in low water content formulations suitable for use in capsules.

Animals↗
PubMed2005

Intrahepatic cholestasis as a paraneoplastic syndrome associated with pheochromocytoma.

Pheochromocytoma is a rare tumor of chromaffin cells that secrete catecholamines and several cytokines. The clinical manifestations are protean and may include hypertension, weight loss, sweating, palpitation, headache, anxiety, tremor, nausea, vomiting, and hypercalcemia. The tumor can mimic many unrelated diseases, leading to significant delay and difficulty in diagnosis. We report a case of a 37-yr-old male admitted with jaundice, dark urine, fever, and signs of a systemic inflammatory response. Abdominal computed tomography revealed a heterogeneously enhancing tumor between the pancreatic tail and left kidney. There was no evidence of obstruction to bile flow, neoplastic involvement of the liver or bile ducts, or infectious etiology. The tumor was removed and found to be a pheochromocytoma. Immunohistochemical analysis revealed the presence of interleukin-1beta in the tumor cells. After surgery, the jaundice resolved without further treatment, leading us to the conclusion that it was a paraneoplastic phenomenon possibly related to interleukin-1beta production. We suggest that occult pheochromocytoma should be added to the differential diagnosis of unexplained intrahepatic cholestasis.

Adrenal Gland Neoplasms↗
PubMed2003

Performance characteristics of selected immunoassays for preliminary test of 3,4-methylenedioxymethamphetamine, methamphetamine, and related drugs in urine specimens.

Eight commercially available immunoassays for amphetamines (DRI Amphetamines, CEDIA DAU Amphetamines-Semiquantitative, EMIT d.a.u. Monoclonal Amphetamine/Methamphetamine, Synchron CX Systems AMPH, TDx/TDxFLx Amphetamine/Methamphetamine II, CEDIA Amphetamines/Ecstasy, COBAS INTEGRA Amphetamines, and Abuscreen((R)) OnLine HS Amphetamine/MDMA) are evaluated for their effectiveness in serving as the preliminary test methodology for the analysis of 3,4-methylenedioxymethamphetamine/3,4-methylenedioxyamphetamine (MDMA/MDA) and methamphetamine/amphetamine (MA/AM). Standard solutions (in urine matrix) of MDMA, MDA, MA, and AM are used to determine these immunoassays' reactivities (or cross-reactivities) toward these compounds of interest. Case specimens containing MDMA/MDA and MA/AM are also used to study the correlations of the apparent immunoassay MDMA (or MA) concentrations and the gas chromatographic-mass spectrometric concentrations of these compounds. Data resulting from this study suggest that CEDIA Amphetamines/Ecstasy can best predict the concentrations of MDMA and MA in case specimens and can also detect the presence of MDMA at low levels, whereas Abuscreen OnLine HS Amphetamine/MDMA can detect both MDMA and MA at low concentrations.

Gas Chromatography-Mass Spectrometry↗
PubMed2002

Left ventricular 4D echocardiogram motion and shape analysis.

The article describes the methodology and the processes of modeling the function and the motion of left ventricle using transesophageal echocardiograph. The parameters can be used in studying the functionality of left ventricle, the status of abnormality of myocardial, and the geometric and morphological of left ventricle in shape analysis. The parameters describes the motion of left ventricle are the left ventricular (LV) floating long axis, the morphological parameters. The LV morphological parameters describe the wall motion, the LV chamber cavity variation, the effective R-ratio of endomyocardial chamber of LV, the area surface curvature, and the global surface curvature circularity. The parameters such as stroke volume, ejection fraction used in evaluation of LV functions are also extracted.

Echocardiography, Four-Dimensional↗
PubMed2001

Effect of oleamide on Ca(2+) signaling in human bladder cancer cells.

The effect of oleamide, a sleep-inducing endogenous lipid in animal models, on intracellular free levels of Ca(2+) ([Ca(2+)](i)) in non-excitable and excitable cells was examined by using fura-2 as a fluorescent dye. [Ca(2+)](i) in pheochromocytoma cells, renal tubular cells, osteoblast-like cells, and bladder cancer cells were increased on stimulation of 50 microM oleamide. The response in human bladder cancer cells (T24) was the greatest and was further explored. Oleamide (10-100 microM) increased [Ca(2+)](i) in a concentration-dependent fashion with an EC(50) of 50 microM. The [Ca(2+)](i) signal comprised an initial rise and a sustained plateau and was reduced by removing extracellular Ca(2+) by 85 +/- 5%. After pre-treatment with 10-100 microM oleamide in Ca(2+)-free medium, addition of 3 mM Ca(2+) increased [Ca(2+)](i) in a manner dependent on the concentration of oleamide. The [Ca(2+)](i) increase induced by 50 microM oleamide was reduced by 100 microM La(3+) by 40%, but was not altered by 10 microM nifedipine, 10 microM verapamil, and 50 microM Ni(2+). In Ca(2+)-free medium, pre-treatment with thapsigargin (1 microM), an endoplasmic reticulum Ca(2+) pump inhibitor, abolished 50 microM oleamide-induced [Ca(2+)](i) increases; conversely, pretreatment with 50 microM oleamide reduced 1 microM thapsigargin-induced [Ca(2+)](i) increases by 50 +/- 3%. Suppression of the activity of phospholipase C with 2 microM U73122 failed to alter 50 microM oleamide-induced Ca(2+) release. Linoleamide (10-100 microM), another sleep-inducing lipid with a structure similar to that of oleamide, also induced an increase in [Ca(2+)](i). Together, it was shown that oleamide induced significant [Ca(2+)](i) increases in cells by a phospholipase C-independent release of Ca(2+) from thapsigargin-sensitive stores and by inducing Ca(2+) entry.

Animals↗
PubMed2001

The chaperone activity of trigger factor is distinct from its isomerase activity during co-expression with adenylate kinase in Escherichia coli.

To investigate the molecular chaperone function of trigger factor (TF) and its relationship with isomerase activity in vivo, the assisted folding of adenylate kinase (AK) by TF in Escherichia coli was examined by measuring the amounts of soluble AK produced during co-expression. When the mutant of chicken AK, P17G, is expressed in plasmid pBVAK, 95% of the protein is found in inclusion bodies. Co-expression of AK with TF was achieved using a plasmid pBVAT that allowed expression of TF and AK in the same plasmid under separate control. Co-expression with TF resulted in an increase in the amount of soluble AK, with a higher increase when TF was expressed at higher levels in the cell. Co-expression of AK with the two TF mutants, Y221G and F233Y, in which peptidyl-prolyl cis/trans isomerase activity was 1% of wild-type, gave the same results as wild-type TF. This provides in vivo evidence that the molecular chaperone activity of TF is distinct from its isomerase activity.

Adenylate Kinase↗
PubMed2001

Mechanism of bifonazole-induced [Ca2+]i increases in MDCK renal tubular cells.

The effect of the antifungal drug bifonazole on Ca2+ homeostasis in Madin Darby canine kidney (MDCK) cells was investigated. Cell suspensions were loaded with the Ca2+-sensitive dye fura-2, and the fluorescence changes were measured with a spectrofluorophotometer. At concentrations between 10-80 microM bifonazole increased cytosolic free Ca2+ levels ([Ca2+]i) in a concentration-dependent manner. The Ca2+ signals were partly inhibited by removing extracellular Ca2+. Bifonazole (40 microM) released Ca2+ from the store sensitive to 1 microM thapsigargin, an endopolasmic reticulum Ca2+ pump inhibitor. Bifonazole (40 microM) per se induced capacitative Ca2+ entry while reduced 1 microM thapsigargin-induced capacitative Ca2+ entry. Inositol 1,4,5-trisphosphate may be involved in bifonazole-induced Ca2+ release because inhibiting phospholipase C with 2 microM U73122 partly reduced the bifonazole response. Together, bifonazole increased [Ca2+]i in renal tubular cells by inducing intracellular Ca2+ release and extracellular Ca2+ influx.

Adenosine Triphosphate↗
PubMed2001

Clomiphene, an ovulation-inducing agent, causes [Ca2+]i increases in human osteoblast-like cells.

The effect of clomiphene, an ovulation-inducing agent, on cytosolic free Ca2+ levels ([Ca2+]i) in MG63 human osteosarcoma cells was explored by using fura-2 as a Ca2+ indicator. Clomiphene at concentrations between 5-75 microM increased [Ca2+]i in a concentration-dependent manner with an EC50 of 50 microM. The [Ca2+]i signal consisted of an initial rise and a sustained phase. Ca2+ removal reduced the Ca2+ signal by 40+/-10%. The [Ca2+]i increase induced by 50 microM clomiphene was inhibited by 80+/-5% by 10 microM nifedipine, but was insensitive to 50 microM La3+ or 10 microM verapamil. In Ca2+-free medium, pretreatment with 50 microM brefeldin A (to disrupt the Golgi complex Ca2+ store), 1 microM thapsigargin (to inhibit the endoplasmic reticulum Ca2+ pump), and carbonylcyanide m-chlorophenylhydrazone (CCCP; to uncouple mitochondria) inhibited 51+/-3% of 50 microM clomiphene-induced Ca2+ release; conversely, pretreatment with 50 microM clomiphene abolished the [Ca2+]i increase induced by thapsigargin, CCCP, and brefeldin A. The Ca2+ release-induced by 50 pM clomiphene was unchanged by inhibition of phospholipase C with 2 microM 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122). Collectively, the results suggest that clomiphene increased [Ca2+]i, in osteoblast-like cells, by releasing intracellular Ca2+ in a phospholipase C-independent manner and by causing nifedipine-sensitive Ca2+ influx.

Calcium↗
PubMed2001

Anapole moment and other constraints on the strangeness conserving Hadronic weak interaction.

Standard analyses of low-energy NN and nuclear parity-violating observables have been based on a pi-, rho-, and omega-exchange model capable of describing all five independent s-p partial waves. Here a parallel analysis is performed for the one-body, exchange-current, and nuclear polarization contributions to the anapole moments of 133Cs and 205Tl. The resulting constraints are not consistent, though there remains some degree of uncertainty in the nuclear structure analysis of the atomic moments.

Journal Article↗
PubMed2001

High-angle annular dark-field imaging of self-assembled Ge islands on Si(0 0 1).

Low-resolution high-angle annular dark-field (HAADF) imaging is applied to the study of coherent Ge islands on a Si(0 0 1) substrate. Experimental HAADF images reveal a complicated pattern for a coherent Ge island under (0 0 1) zone axis conditions due to strain-induced interband scattering between different Bloch-wave branches. This complicated pattern varies with objective aperture size and defocus because of the effect from the depth of field. This suggests that the strain field of a coherent Ge island can be mapped out in 3 dimensions using HAADF imaging. When samples are tilted away from dynamical conditions, image contrast agrees with the predictions from atomic number variation (Z contrast). Therefore, quantitatively compositional analysis is feasible under kinematical imaging conditions when strain contrast is suppressed. Simulations using multi-beam Bloch-wave theory agree well with the experimental images on the complicated strain-induced and through-focus images.

Journal Article↗
PubMed2001

Nordihydroguaiaretic acid elevates osteoblastic intracellular Ca2+.

Nordihydroguaiaretic acid (NDGA) is widely used as a pharmacological tool to inhibit lipoxygenases; however, recent evidence suggests that it increases renal intracellular [Ca2+]i via novel mechanisms. Here the effect of NDGA on Ca2+ signaling in MG63 osteoblastic cells was explored using fura-2 as a Ca2+ indicator. NDGA (2-50 microM) increased [Ca2+]i in a concentration-dependent manner. The signal comprised an initial rise and an elevated phase over a time period of 4 min. Removing extracellular Ca2+ reduced 2-50 microM NDGA-induced signals by 62+/-2%. After incubation with 50 microM NDGA in Ca2+-free medium for several minutes, addition of 3 mM CaCl2 induced an increase in [Ca2+]i. NDGA (50 microM)-induced [Ca2+]i increases were not changed by pretreatment with 10 microM of verapamil, diltiazem, nifedipine, nimodipine and nicardipine. In Ca2+-free medium, pretreatment with the endoplasmic reticulum Ca2+ pump inhibitor thapsigargin (1 microM) inhibited 50 microM NDGA-induced [Ca2+]i increases by 69+/-3%. Inhibition of phospholipase C with 2 microM U73122 had little effect on 50 microM NDGA-induced Ca2+ release. Several other lipoxygenase inhibitors had no effect on basal [Ca2+]i. At a concentration that did not increase basal [Ca2+]i, NDGA (1 microM) did not alter 10 microM ATP- or 1 microM thapsigargin-induced [Ca2+]i increases. Alteration of protein kinase C activity with 1 nM phorbol 12-myristate 13-acetate or 2 microM GF 109203X did not affect 50 microM NDGA-induced [Ca2+]i increases. Together, the results show that NDGA increased [Ca2+]i in osteoblasts in a lipoxygenase-independent manner, by releasing stored Ca2+ in a fashion independent of phospholipase C activity, and by causing Ca2+ influx.

Calcium↗
PubMed2001

Real-time 3-dimensional echocardiographic evaluation of left ventricular volume: correlation with magnetic resonance imaging--a validation study.

BACKGROUND: The purpose of our study was to validate the ability of real-time 3-dimensional echocardiography (RT3D) to measure cardiac volume. METHODS: We studied 25 patients with various cardiac disorders who had a regular heart rhythm and a good precordial echocardiographic window. Each patient underwent complete transthoracic echocardiography (TTE), RT3D, and magnetic resonance imaging (MRI) studies. Left ventricular dimension was calculated from slices of the whole left ventricle obtained by 7 different equidistant azimuth tilts. Planimetry of the endocardial (for volume data) and epicardium (for mass data) surface was performed for each azimuth tilt. The left ventricular end-diastolic volume (LVEDV) and the left ventricular end-systolic volume (LVESV) were calculated. The cardiac mass data were derived with the formula (Epicardial volume - LVEDV) x 1.055. The parameters of LVEDV, LVESV, stroke volume, ejection fraction, and cardiac mass were compared with those derived from MRI. RESULTS: No statistically significant differences were found between the data from RT3D and MRI (P > or =.05). Good correlations were found between these two methods for left ventricle volume and mass measurements (r from 0.92 to 0.99). However, a weaker correlation was found with larger chamber sizes because extrapolation was necessary for the volume of myocardial segments that were not covered by the small sector angle. CONCLUSIONS: For data acquisition, RT3D is faster than either TTE or MRI. It is also better than MRI for measuring cardiac volume and mass. To improve results with larger cardiac chamber sizes, enlargement of the sector angle will be necessary.

Adult↗
PubMed2001

Color encoding of the two-dimensional echocardiograms to analyze the echo texture of thickened mitral leaflets.

OBJECTIVE: The visual identification of different brightness of two-dimensional echocardiograms has natural limitations. The aim of this study was to perform a color-encoding technique on the echocardiograms and to evaluate whether the thickened mitral valve due to different etiologies may exhibit different colors and textures. DESIGN: Two-dimensional echocardiograms in parasternal long axis view in late diastole were digitized in 28 patients with thickened mitral valves and 14 age-matched control subjects. These 28 patients included 14 patients with mitral valve prolapse (MVP) and 14 patients with rheumatic change of mitral valve (RMV). The mean gray level of the anterior mitral valve and the skewness of the histogram of gray level distribution of the anterior mitral valve were studied in all cases. RESULTS: A significantly greater mean gray level of mitral valves in patients with RMV (114 +/- 20, p < 0.001) and lesser mean gray level in patients with MVP (49 +/- 12, p = 0.041) compared to that of control subjects (62 +/- 18) were noted. The mitral valves of the echocardiograms of patients with MVP tended to show a blue-to-green color, while those of RMV tended to show a yellow-to-orange color by this image processing system. Significant differences in skewness of the gray level distribution of mitral valves in control vs RMV (p = 0.001), control vs MVP (p = 0.005), and RMV vs MVP (p < 0.001) were also found. CONCLUSION: This study demonstrates that the thickened mitral valves due to MVP and RMV may exhibit different colors and textures. Digital image processing can provide additional information to conventional echocardiograms in characterizing different echo textures of the heart valves.

Adult↗
PubMed2001

Does inadequate exercise lower the accuracy of myocardial perfusion scintigraphy?

The predictive accuracy of exercise myocardial perfusion scintigraphy (EMPS) in detecting coronary artery disease (CAD) in patients who fail to achieve an adequate level of exercise is not clear. This investigation was carried out in order to compare the sensitivity, specificity and accuracy of EMPS in adequate exercise patients with those in inadequate exercise patients. We have retrospectively compared the results of EMPS with coronary angiography (CAG). One hundred and forty-eight patients with both tests within 6 weeks were included. Adequate exercise was defined as > or = 85% maximally predicted heart rate for age. The overall sensitivity and specificity of EMPS to detect CAD were 92.5% (74/80) and 75%, (51/68), respectively. The sensitivity and specificity in adequate exercise patients were 94.1% (32/34) and 67.6% (23/34), whereas those in inadequate exercise patients were 91.3% (42/46) and 82.4% (28/34). The accuracy was 80.9% (55/68) and 87.5% (70/80), respectively. Patients with inadequate exercise had lower sensitivity but higher specificity of EMPS for detecting CAD, and achieved a higher accuracy than those with adequate exercise.

Adult↗
PubMed2001

Effects of the antianginal drug fendiline on Ca2+ movement in hepatoma cells.

This study investigated the effect of the anti-anginal drug, fendiline, on intracellular free Ca2+ levels ([Ca2+]i) in HA/ 22 human hepatoma cells by using fura-2 as a fluorescent Ca2+ dye. Fendiline (1-100 microM) increased [Ca2+]i with an EC50 of 25 microM. Removal of extracellular Ca2+ reduced the [Ca2+]i signals by 51 +/- 5%. Fendiline (10 microM)-induced Ca2+ release was abolished by pretreatment with 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor). Inhibition of phospholipase C with 2 microM 1-(6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione (U73122) did not alter 10 microM fendiline-induced Ca2+ release. Several other calmodulin antagonists, such as phenoxybenzamine (100-200 microM), trifluoperazine (5-50 microM), and fluphenazine-N-chloroethane (2-100 microM), had no effect on [Ca2+]i. Together, it was found that fendiline increased [Ca2+]i in human hepatoma cells by discharging Ca2+ from the endoplasmic reticulum in an inositol 1,4,5-trisphosphate-independent manner and by inducing Ca2+ entry. This effect of fendiline does not appear to be via antagonism of calmodulin.

Calcium↗