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Biomedical subjects

L C Chiu

Publications and source records attributed to L C Chiu.

At least 19 recordsLinked to original sources
PubMed2001

Induction of apoptosis by a ribosome-inactivating protein from Agrostemma githago is associated with down-regulation of anti-apoptotic bcl-2 protein expression.

Agrostin is a type 1 ribosome-inactivating protein (RIP) isolated from the seeds of Agrostemma githago. 3[H]-thymidine incorporation in human leukemic HL-60 cells was significantly reduced after incubation with agrostin showing that the RIP was inhibitory on the cell proliferation. Results from flow cytometric studies illustrated that apoptosis was induced by agrostin, which was associated with activation of endonucleases and DNA fragmentation of the leukemic cells. Anti-apoptotic bcl-2 protein level was also reduced by agrostin showing that the associated apoptotic pathway might involve down-regulation of the intracellular bcl-2 protein level.

Annexins↗
PubMed2001

Eicosapentaenoic acid modulates cyclin expression and arrests cell cycle progression in human leukemic K-562 cells.

Eicosapentaenoic acid (EPA) is a polyunsaturated fatty acid (20:5omega3) found primarily in aquatic organisms. We have shown previously that EPA inhibits the growth but is not toxic to human leukemic K-562 cells. In this study, the anti-proliferative effect of EPA on the leukemic cells was further determined and its impacts on cell cycle progression and cyclin expression were investigated. EPA inhibited proliferation of K-562 cells, which was associated with accumulation of G0/G1 cells and down-regulation of cyclin E expression. Cyclin B1-expressing cells were also reduced showing that down-regulation of cyclin expression might be important in the anti-proliferation of EPA.

Apoptosis↗
PubMed2000

The binding characteristics and intracellular localization of temoporfin (mTHPC) in myeloid leukemia cells: phototoxicity and mitochondrial damage .

The state of aggregation of the photosensitizer meso-tetrahydroxyphenylchlorin (mTHPC) in both cell free and intracellular environment was elucidated by comparing its absorption and excitation spectra. In methanol, mTHPC existed as monomers and strongly fluoresced. In aqueous solutions such as phosphate-buffered saline (PBS), mTHPC formed nonfluorescent aggregates. Some portion of mTHPC monomerized in the presence of 10% fetal calf serum PBS. In murine myeloid leukemia M1 and WEHI-3B (JCS) cells, cytoplasmic mTHPC were monomeric. By using organelle-specific fluorescent probes, it was found that mTHPC localized preferentially at the mitochondria and the perinuclear region. Photodynamic treatment of mTHPC-sensitized leukemia cells caused rapid appearance of the apoptogenic protein cytochrome c in the cytosol. Results from flow cytometric analysis showed that the release of cytochrome c was especially pronounced in JCS cells, and well correlated with the extent of apoptotic cell death as reported earlier. Electron microscopy revealed the loss of integrity of the mitochondrial membrane and the appearance of chromatin condensation as early as 1 h after light irradiation. We conclude that rapid release of cytochrome c from photodamaged mitochondria is responsible for the mTHPC-induced apoptosis in the myeloid leukemia JCS and M1 cells.

Animals↗
PubMed2000

Induction of apoptosis by dietary polyunsaturated fatty acids in human leukemic cells is not associated with DNA fragmentation.

Apoptosis is important in anticancer strategy. In this study, bivariate annexin V/PI flow cytometry showed that dietary polyunsaturated fatty acids, arachidonic acid (AA) and eicosapentaenoic acid (EPA), induced apoptosis in human leukemic HL-60 but not K-562 cells. Results from DNA-PI flow cytometry and TUNEL flow cytometry illustrated that neither AA nor EPA induced DNA fragmentation in the leukemic cells. These findings suggested that the AA- and EPA-induced apoptosis might not associate with endonucleases activation, and DNA fragmentation could not be used as a sole criterion to identify apoptotic cells.

Apoptosis↗
PubMed1999

Induction of apoptosis in HL-60 cells by eicosapentaenoic acid (EPA) is associated with downregulation of bcl-2 expression.

Dietary polyunsaturated fatty acids (PUFAs) have been reported as a potential group of natural products which modulate tumor cell growth. In present study, eicosapentaenoic acid (EPA) was found to inhibit proliferation of human leukemic HL-60 and K-562 cells in vitro. EPA arrested cell cycle progression at G0/G1 phase, and induced necrosis in both HL-60 and K-562 cells. However, EPA induced apoptosis only in HL-60 but not K-562 cells. Also, bcl-2 protein expression was downregulated in much greater extent than that of bax showing that depression of bcl-2 might be an important step during the EPA-induced apoptosis in HL-60 cells.

Apoptosis↗
PubMed1998

Magnetic resonance angiography in the diagnosis of thoracic venous obstruction.

The aims of this study were to evaluate the diagnostic value of orthogonal magnetic resonance angiography (MRA) and to compare the results of MRA with those of digital subtraction venography (DSV) in thoracic venous diseases. Ten normal volunteers were evaluated using two-dimensional time-of-flight MRA in three orthogonal planes to determine the image quality of each venous segment. Twelve consecutive patients suspected of having thoracic venous disease were studied with both MRA and DSV. In the normal subjects, the plane perpendicular to the target vein provided the most consistent visualization. Using three orthogonal MRA images, a diagnostic-quality image was obtained in 175 (83%) of 210 venous segments in normal volunteers. In patients with thoracic venous obstructive disease, MRA was more effective than DSV in detecting total (84 vs 54), patent (56 vs 36), stenotic (13 vs 10), and obstructive (15 vs 8) venous segments, poststenotic or postobstructive veins (15 vs 10), thrombosis of the internal jugular vein (7 vs 2), intraluminal thrombus (5 vs 3), and azygos veins (12 vs 2). Using venous segments visible on DVS (n = 54) as the standard, the sensitivity and specificity of MRA were 94% and 100%, respectively, in detecting venous patency, and 100% and 98% in detecting complete venous obstruction. In the shoulder region, the sensitivity and specificity of MRA were 93% and 100%, respectively, in detecting venous patency, and 100% and 97% in detecting venous obstruction. We conclude that MRA with three orthogonal planes can provide relatively complete and reliable venous mapping, without the need for contrast medium.

Adult↗
PubMed1996

2-D time-of-flight (TOF) MRA of thrombophlebitis of upper extremity and subclavian veins. A case report.

In this report, the authors present a case of segmental thrombosis of left subclavian vein that was inaccessible to conventional venography and inconclusive in magnetic resonance techniques (spin echo, gradient echo) but was clearly demonstrated by two-dimensional time-of-flight magnetic resonance angiography (2D TOF MRA). This technique is very sensitive to detect slow flow or partial occlusion of the vessels and is of great help in solving the problem of axillary-subclavian venous obstruction or thrombophlebitis.

Adult↗
PubMed1994

Effect of polysaccharide peptide (PSP) on glutathione and protection against paracetamol-induced hepatotoxicity in the rat.

The protective effects of polysaccharide peptide (PSP), isolated from Coriolus versicolor COV-1, on paracetamol-induced hepatotoxicity was investigated in this study. The effect of PSP on hepatic glutathione status was also studied. PSP (300 mg/kg, i.p.) caused a 40% depletion of hepatic reduced glutathione (GSH) with a concomitant 50% increase in oxidized glutathione (GSSG), thus producing a 3-fold increase in the GSSG/GSH ratio. The PSP-induced GSH depletion itself had no hepatotoxic effects. PSP protected against paracetamol-induced hepatotoxicity by decreasing the paracetamol-induced elevation of serum glutamic-pyruvic transaminase (SGPT) activity from 511 +/- 71 U/ml to 187 +/- 58 U/ml (controls without paracetamol 105 +/- 4 U/ml) and serum glutamic-oxaloacetic transaminase (SGOT) activity from 462 +/- 63 to 152 +/- 48 U/ml (controls without paracetamol 54 +/- 6 U/ml). PSP did not reverse the depletion of total glutathione (GSH+GSSG) by the toxic dose of paracetamol. The GSSG/GSH ratio, which is a measure of oxidative stress, was significantly (p < 0.05) decreased when PSP was coadministered with paracetamol. PSP dose-dependently decreased the covalent binding of [14C]-paracetamol to microsomal proteins in vitro. When PSP was given to rats subchronically for 7 days (300 mg/kg/day, i.p.), the subsequent microsomes obtained also showed a 25% decrease in covalent binding to [14C]-paracetamol, suggesting that PSP interacted with the microsomal proteins rather than the chemically reactive metabolite of paracetamol. The changes in the binding affinity and capacity of the microsomal proteins by PSP may be related to its ability to alter the redox potential as indicated by the effects of PSP on the GSSG/GSH status.

Acetaminophen↗
PubMed1993

Evaluation of hip disorders by radiography, radionuclide scanning and magnetic resonance imaging.

Thirty-six hips were studied because of significant hip pain. Radiography of the hip and bone scintigraphy showed subtle changes. Magnetic resonance imaging (MRI) was performed using a 1.5 Tesla superconductive unit. All MRI findings were confirmed by surgical or pathologic results. Twenty-nine hips had a single lesion, including: infection (one), fracture (eight), avascular necrosis of the femur(two), or contralateral hip (four), transient osteoporosis (six), osteoporosis (one), post-irradiation myositis (one), metastasis (four), and synovitis (two). Twenty-six lesions (89.6%) appeared normal on the radiographs of the hip, while three lesions (10.4%) showed only osteoporotic change. Another seven hips had more than one lesion, including: avascular necrosis and fracture (four), fracture foci (two), and metastasis and fracture (two). Radiography of the hip showed either a negative finding or detected only a single lesion, missing other important pathologic foci. MRI is extremely sensitive to alterations in the bone marrow that may represent pathology occult to plain radiography and bone scintigraphy of the hips. For diagnosis and treatment planning, MRI of the hips should be performed early in patients with persistent pain and negative radiography findings.

Acetabulum↗
PubMed1993

MR patterns of rotator cuff and labral lesions: comparison between low-field and high-field images.

Eighteen people (10 men, 8 women) were examined on a 0.3-T (low-field) imager with T1-weighted axial and coronal images and either axial or coronal T2-weighted images. Thirty-two people (22 men, 10 women) were examined on a 1.5-T (high-field) imager with axial T1-weighted images and coronal, sagittal dual-echo images. Rotator cuff lesions were diagnosed by the following findings: abnormal signal in the tendon, irregularity or discontinuity at the musculo-tendinous junction, or muscle abnormality. Glenoid labrum tears were considered if one or more of the following criteria were present: labral deformity of unusual size, focal defect, amputation or displacement with fluid, or capsular stripping. Comparison between the high-field and low-field MR images in the evaluation of rotator cuff lesions suggests that the high-field imager is better than the low-field imager in the differentiation of tendinitis from tears, in the confirmation of bursitis and in detection of subscapularis lesions. A higher contrast-to-noise ratio (CNR), less time consumption, and more section planes (especially, sagittal sections) appear to be the main reasons for this. As far as labral lesions are concerned, the performances of the high-field imagers and low-field imagers were almost equal. The artifact of greater chemical shift with a high-field imager would more or less, we assume, degrade the better CNR achievable in the diagnosis of labral lesions.

Adolescent↗
PubMed1992

Multiplanar gradient recalled images of the knee: comparison of different flip angles and echo times.

To determine the most appropriate combination of echo time (TE) and flip angle in gradient echo images of the knee, the authors used different TEs (10, 20 and 30 msec) and flip angles (10, 30, 50, 70, 90, 120 and 150 degrees) to perform a systematic study of MRI on 10 volunteer knees. Contrast-to-noise ratios of cartilage-fat, fluid-cartilage, fluid-fat and fluid-ligament were calculated and compared. Images with a 30-degree flip angle combined with 20 msec of TE were found to have the best contrast-to-noise ratios in both objective data analysis and subjective observation. Hyaline cartilage of the knee was hyperintense and was well delineated on this pulse sequence, appearing distinct in contrast to the intra-articular fluid. It is concluded that this T2-weighted gradient echo pulse sequence is an alternative to conventional spin echo T2-weighted imaging of the knee.

Echo-Planar Imaging↗
PubMed1989

Nuclear magnetic resonance study of obsessive-compulsive disorder.

Magnetic resonance imaging (MRI) of the brains of 32 patients who met the DSM-III criteria for obsessive-compulsive disorder and of 14 normal subjects frequently revealed abnormalities, but none was specific to obsessive-compulsive disorder. Spin-lattice relaxation time (T1) for right frontal white matter was prolonged in the patients compared to the control subjects, and the patients had greater right-minus-left T1 differences for frontal white matter. Right-minus-left T1 differences in the orbital frontal cortex were strongly correlated with symptom severity in the unmedicated patients and in the patients with family histories of obsessive-compulsive disorder.

Adult↗
PubMed1989

Pott's disease. A resurgent challenge to the thoracic surgeon.

Nineteen patients were treated at the Los Angeles County Harbor/UCLA Medical Center between 1971 and 1986 for tuberculosis of the spine. Fourteen were immigrants, a high-risk group. A high index of suspicion is required for Pott's disease, which occurs in fewer than 1 percent of patients with tuberculosis, often presents with nonspecific symptoms, and may result in permanent deformity or neurologic impairment. CT scan, the most useful diagnostic test, showed abnormal results in 11 of 11 patients. MRI, a newer modality, may provide even more information. Eight patients required operation in addition to antimicrobial therapy. Four had lesions between T3 and T10, where the spinal canal is narrow, of whom three (75 percent had neurologic involvement. All four underwent anterior approach (thoracotomy) for decompression, debridement, and spinal fusion. Fifteen had lesions between T11 and S2. Three (20 percent) had neurologic involvement but responded to medical treatment alone. Four underwent drainage of abscess or spinal fusion for deformity. Combined surgical and medical treatment gave excellent results in this series.

Adolescent↗
PubMed1987

Superior vena cava obstruction: a venographic classification.

Analysis of venacavograms in 27 patients with superior vena caval obstruction revealed the following four patterns of venous collateral return: type I, partial obstruction (up to 90% stenosis) of the superior vena cava with patency of the azygos vein; type II, near-complete to complete obstruction (90-100%) of the superior vena cava with patency and antegrade flow through the azygos vein and into the right atrium; type III, near-complete to complete obstruction (90-100%) of the superior vena cava with reversal of azygos blood flow; type IV, complete obstruction of the superior vena cava and one or more of the major caval tributaries, including the azygos system. These patterns correlate well with the patients' clinical courses and can be used to identify patients who are at risk of developing cerebral and airway compromise and therefore would benefit from superior vena cava bypass surgery.

Adult↗