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Biomedical subjects

C C Shih

Publications and source records attributed to C C Shih.

At least 37 records · Page 2Linked to original sources
PubMed1999

Differential expression of peroxiredoxin subtypes in human brain cell types.

The peroxiredoxin (Prx) protein is expressed widely in animal tissues and serves an antioxidant function associated with removal of cellular peroxides. We have cloned two Prx genes and observed differential expression of Prx-I and Prx-II (formerly NKEF-A and NKEF-B) in purified rat brain cell cultures (Sarafian et al. [1998] Mol. Chem. Neuropathol. 34:39-51). We have examined regional and cell-type-specific expression of Prx-I and Prx-II in paraffin sections of human brain using immunohistochemical methods. These studies revealed a clear segregation of expression of these two gene products in different brain cell types. In the cerebral cortex, cerebellum, basal ganglia, substantia nigra, and spinal cord, Prx-I was expressed primarily in astrocytes, while Prx-II was expressed exclusively in neurons. Prx-I was also prominently expressed in ependymal cells and subependymal matrix of substantia nigra and basal ganglia. Prx-II was not expressed at uniform density in all neurons. In general, small neurons such as cerebellar granule neurons displayed little or no staining, while large neurons, such as hippocampal pyramidal and Purkinje neurons were heavily stained. The absence of expression of Prx-I in neurons and the selective expression of Prx-II in large neurons suggest that these antioxidant enzymes serve distinct functional roles that may reflect the different functions and biochemical activities of these cell types. Restricted expression of these genes may also contribute to the selective vulnerability of these cells to a wide variety of neuropathologic conditions.

Adult↗
PubMed1999

Sequential changes in heart rate variability after coronary artery bypass grafting.

Heart rate variability (HRV) decreased soon after coronary artery bypass grafting and returned to the preoperative level within 2 months; however, HRV did not exceed the preoperative level, even 6 months after coronary artery bypass grafting. Although myocardial ischemia can be improved by coronary artery bypass grafting, HRV did not benefit from coronary artery bypass grafting within 6 months.

Adult↗
PubMed1999

Monoclonal anti-androgen receptor antibodies: production, characterization and potential diagnostic applications.

Several monoclonal antibodies (mAbs) and novel mAb-based assays for the androgen receptors (AR) have been developed. Large amounts of the recombinant human AR protein produced by a baculovirus expression system were used as an antigen to produce mAbs. Twenty-nine AR-specific mAbs were first confirmed by Western blot analysis and were then characterized for their immunoglobulin isotypes, epitopes, and epitope localization in AR. Novel assays using flow cytometry and sandwich enzyme-linked immunosorbent assays (ELISA) were established to detect AR-expressing cells and to quantify soluble AR protein, respectively. Using immunostaining, we identified several anti-AR mAbs exclusively recognizing AR within the nuclei of the prostate cancer cell line LNCaP and of prostate tissues in both frozen and paraffin-embedded sections, whereas other mAbs could detect AR in both nuclear and cytoplasmic compartments. Interestingly, certain mAbs, such as G122-25 and G122-77, could distinguish the androgen-bound AR from the unoccupied AR. In sum, many purified AR protein and anti-AR mAbs, together with the assays developed, could be powerful tools for the study of functional AR and for the diagnosis of prostatic cancers.

Animals↗
PubMed1999

Diaschisis in chronic viral encephalitis with Koshevnikov syndrome.

The authors report a 61-year-old man with chronic viral encephalitis and Koshevnikov syndrome occurring 42 months after initial symptom of right hemiparesis. Serial computed tomography of the brain showed changes in the attenuation of the left temporal lobe lesion over time. Magnetic resonance images of the brain showed enlargement of left temporoparietooccipital lobes with cortical gyral enhancement on T1-weighted images following intravenous administration of gadolinium-DTPA. 99mTc-HMPAO single-photon emission computerized tomography showed increased radioactivity and hyperperfusion in the left temporoparietal region with paradoxically decreased local tissue perfusion at the contralateral right hemisphere. Follow-up magnetic resonance images of the brain 4 years later showed atrophy of bilateral cerebral hemispheres. We postulate that a "transcallosal diaschisis" with subsequent degeneration is a possible mechanism. A brain biopsy from the left temporal lobe lesion showed pictures compatible with viral encephalitis probably herpes simplex encephalitis.

Atrophy↗
PubMed1998

Computed tomography in the determination of surgical emergency for symptomatic abdominal aortic aneurysm.

BACKGROUND: What is the best surgical timing for symptomatic AAA? Surely, the answer depends on accurate and prompt diagnosis of 'rupture or not'. Abdominal CT is one of the reliable and familiar diagnostic tools. We will present our own CT classification method for symptomatic AAA which is used as the guideline for 'emergency or not'. METHODS: From January 1989 to January 1995, 52 patients with symptomatic AAA received diagnostic CT scan for quick disease differentiation and determination of surgical emergency. The findings were classified into four categories. Category I included 26 patients with intact aorta; Category II included four patients with contained retroperitoneal abdominal aortic leakage; Category III included 14 patients with contained massive retroperitoneal hematoma; and Category IV included eight patients with retroperitoneal or intraperitoneal active bleeding. RESULTS: Compared with the standard diagnosis of rupture via laparotomy, CT is an excellent tool, showing 88% sensitivity and 88% specificity. This is better than sonography, which has a high false-positive rate of 33% and low specificity of 62%. Hospital mortality was distinctive with 4.3% in Category I, none in Category II, 25% in Category III and 87.5% in Category IV. CONCLUSIONS: In our experience, CT scan is a better diagnostic tool than sonography for symptomatic AAA. Even the delay imposed by obtaining a preoperative CT scan in patients with possible ruptured aneurysm does not adversely affect the patient's outcome. The information obtained significantly aids not only preoperative but also intraoperative management.

Aged↗
PubMed1998

Minimally-invasive, direct coronary artery bypass grafting.

BACKGROUND: Minimally-invasive, direct vision coronary artery bypass grafting (MIDCAB) is a new surgical technique performed via limited thoracotomy in a beating heart without cardiopulmonary bypass. METHODS: From June 1996 to December 1996, MIDCAB was performed in 12 patients (all male, average age, 65.9 years). In 11 patients with left anterior descending coronary artery lesions, thoracotomy was performed via the left, fourth intercostal space and the pericardium was incised to identify the target site. About 8 cm of the left internal mammary artery was harvested. Bilateral anterolateral thoractomy was performed in one patient with left anterior descending and right coronary artery lesions. Anastomosis was performed under direct vision in the beating heart without cardiopulmonary bypass. RESULTS: MIDCAB was performed successfully without morbidity. The patients' average stay in the intensive care unit was 1.8 days. No patient had any early cardiac event requiring additional surgery or percutaneous transluminal coronary angioplasty. Postoperatively, all patients were asymptomatic and their recovery was uneventful. CONCLUSIONS: Our initial experience indicates that MIDCAB offers good results and is a treatment option for selected patients with left anterior descending and/or right coronary artery lesions.

Aged↗
PubMed1997

Surgical repair of Ebstein's anomaly.

BACKGROUND: Ebstein's anomaly represents a congenital structural deformity of the tricuspid valve associated with a wide spectrum of morphologic and physiologic abnormalities. Valvuloplasty and tricuspid valve replacement are the main surgical treatments. Plication of the atrialized right ventricle and valvuloplasty of the tricuspid valve can achieve satisfactory clinical results. Two surgical techniques, known as Danielson's and Quaegebeur's methods, are often used clinically. This study was conducted to compare the postoperative results between both methods in treatment of Ebstein's anomaly. METHODS: Valvuloplasty of tricuspid valve and the plication of atrialized right ventricle were performed in 8 out of 17 patients with Ebstein's anomaly in our hospital from January 1986 to August 1996. Danielson's method was used in six of eight patients, and Quaegebeur's method was used in the remaining two patients. There were three males and five females, aged from 8 months to 61 years (mean: 14.1 years). RESULTS: All patients achieved clinical improvement in cardiothoracic ratio and heart functional class. Cardiac arrhythmia was the likely cause of death in two patients treated by Danielson's method, and one patient developed complete atrioventricular (A-V) block postoperatively. By Quaegebeur's method, all patients survived, but a permanent pacemaker was implanted for both patients due to their preoperative complete A-V block. CONCLUSIONS: Both methods achieved satisfactory postoperative results. However, Quaegebeur's method seems to be more effective because it provided a simultaneous reconstruction of both tricuspid valve and right ventricle without the need for additional excision of the right atrium.

Adolescent↗
PubMed1996

Suppression of glioblastoma angiogenicity and tumorigenicity by inhibition of endogenous expression of vascular endothelial growth factor.

The development of new capillary networks from the normal microvasculature of the host appears to be required for growth of solid tumors. Tumor cells influence this process by producing both inhibitors and positive effectors of angiogenesis. Among the latter, the vascular endothelial growth factor (VEGF) has assumed prime candidacy as a major positive physiological effector. Here, we have directly tested this hypothesis in the brain tumor, glioblastoma multiforme, one of the most highly vascularized human cancers. We introduced an antisense VEGF expression construct into glioblastoma cells and found that (i) VEGF mRNA and protein levels were markedly reduced, (ii) the modified cells did not secrete sufficient factors so as to be chemoattractive for primary human microvascular endothelial cells, (iii) the modified cells were not able to sustain tumor growth in immunodeficient animals, and (iv) the density of in vivo blood vessel formation was reduced in direct relation to the reduction of VEGF secretion and tumor formation. Moreover, revertant cells that recovered the ability to secrete VEGF regained each of these tumorigenic properties. These results suggest that VEGF plays a major angiogenic role in glioblastoma.

Animals↗
PubMed1996

Cross-linking characteristics of biological tissues fixed with monofunctional or multifunctional epoxy compounds.

The cross-linking characteristics of biological tissues fixed by various epoxy compounds with different chemical structures (i.e. number of epoxide functional groups and backbone length) were investigated. Generally speaking, the tissues fixed with monofunctional fixatives were more pliable than those fixed with multifunctional fixatives. The fixation indices of the fixed tissues did not seem to be affected by the chemical structures of the fixatives. However, the number of functional groups and backbone length of the fixatives did play an important role in influencing the denaturation temperatures of the fixed tissues. In general, the denaturation temperatures of the multifunctional fixed tissues were higher than those of the monofunctional fixed tissues. Among the monofunctional fixed tissues, it was found that increasing the backbone length of the fixative decreased the denaturation temperature of the fixed tissue. This effect was present until the backbone length of the fixative became large enough.

Animals↗
PubMed1996

Evaluation of an epoxy-fixed biological patch with ionically bound heparin as a pericardial substitute.

In an attempt to develop an improved pericardial substitute, we undertook the development of an epoxy-fixed biological patch with ionically bound heparin. The study was to evaluate the cross-linking characteristics of this newly developed biological patch using its glutaraldehyde-fixed counterpart as a control. In addition, the feasibility of using this newly developed biological patch as a pericardial substitute was assessed in a canine model. In the study, it was observed that the epoxy-fixed biological patch appeared more similar to the native pericardium in colour and was more pliable than its glutaraldehyde-fixed counterpart. Also, both the epoxy- and glutaraldehyde-fixed biological patches had significant increases in fixation index and denaturation temperature as compared to the fresh one (p < 0.05). In the canine study, the epoxy-fixed biological patch with ionically bound heparin was found to have significantly less adhesion formation than those currently used clinically (p < 0.05).

Analysis of Variance↗
PubMed1996

Bacteremia due to Citrobacter species: significance of primary intraabdominal infection.

From 1982 to 1994, 45 patients (1.22 episodes per 10,000 discharged patients) were treated for citrobacter bacteremia at National Taiwan University Hospital (Taipei). All patients had at least one underlying disease. Citrobacter bacteremia most commonly occurred in patients with malignancies (48.9%) or hepatobiliary stones (22.2%). Intraabdominal tumors comprised the majority (59.1%) of malignancies. Bacteremia commonly originated from sites such as the abdominal cavity (51.1%), urinary tract (20%), and lung (11.1%). Polymicrobial bacteremia was diagnosed in 15 patients (33.3%); for nine (60%) of these patients, the source of the infection was intraabdominal. Prior treatment with a third-generation cephalosporin was significantly associated (P < .01) with the development of multidrug resistance among the isolates. The mortality associated with citrobacter bacteremia was 17.8%. Poor prognostic factors included pneumonia, altered mental status on presentation, hypothermia, oliguria, septic shock, deterioration in mental status, hyperbilirubinemia, azotemia, and thrombocytopenia. Combination therapy, as compared with other regimens, improved the outcome of citrobacter bacteremia.

Adolescent↗
PubMed1996

Role of platelet-endothelial cell adhesion molecule (PECAM) in platelet adhesion/aggregation over injured but not denuded endothelium in vivo and ex vivo.

BACKGROUND AND PURPOSE: We previously demonstrated that a monoclonal antibody (MoAb) with anti-CD31, anti-platelet-endothelial cell adhesion molecule (PECAM)-like properties delayed platelet adhesion/aggregation at a site of minor endothelial injury. To our knowledge, this was the first in vivo demonstration of an effect of anti-CD31. There was no exposure of collagen or basal lamina at the injured site, and the modulation of adhesion/aggregation at such sites has not received much study. The present investigation attempted to replicate the first with the use of a different MoAb, definitely characterized as anti-PECAM. In addition, an ex vivo investigation was performed to see whether the in vivo action of anti-PECAM could have been caused by an effect of the MoAb on the platelets rather than on the endothelium. METHODS: A helium-neon laser, in the presence of intravascular Evans blue, was used to injure the endothelium of arterioles on the surface of the mouse brain. Intravital microscopy was used to determine the number of seconds required for the light to initiate the first recognizable platelet aggregate forming at the injured site. Mice injected with vehicle were compared with mice injected with 2 mg/kg anti-PECAM through the tail vein. The injection was 10 minutes before challenge with the laser. Additional studies were performed of aggregation produced in vitro by arachidonate and by ADP added to platelet-rich plasma (PRP) prepared from blood taken from MoAb-treated and vehicle-treated mice. RESULTS: Aggregation latency was significantly prolonged (P<.02) by anti-PECAM (121+/-59 versus 65+/-26 seconds in controls; n=10 each). Aggregation ex vivo was not affected. CONCLUSIONS: PECAM is an important modulator of platelet adhesion/aggregation at sites of minor endothelial damage in brain arterioles. The data are consistent with the hypothesis that PECAM sites on the endothelium are involved and may be exposed by the injury to promote adhesion/aggregation. Since the endothelial cell layer is intact at these sites, mechanisms such as this offer important alternatives to the more commonly studied pathways of platelet activation, which require exposure of collagen and are not applicable in this model.

Adenosine Diphosphate↗
PubMed1995

The expression of prostatic acid phosphatase is transcriptionally regulated in human prostate carcinoma cells.

The expression of prostatic acid phosphatase (PAcP) in three human prostate carcinoma cell lines including LNCaP, DU 145 and PC-3, was studied to explore its potential role as a marker in the progression of prostate cancer. Although Southern blot analysis suggested the presence of PAcP gene in all three prostate carcinoma cell lines, the Northern blot analysis and the reverse transcriptase-polymerase chain reaction (RT-PCR) assay showed that PAcP mRNA can be detected only in LNCaP cells. As one of the major differences between LNCaP cells and PC-3 as well as DU 145 cells is the androgen-sensitivity of LNCaP cells, we then focused on the influence of PAcP expression by the presence of androgen receptor (AR) in human AR cDNA-transfected PC-3 cells and high passages of LNCaP cells. The results demonstrated that the transfection of human AR cDNA into PC-3 cells did not have any detectable effect on the expression of PAcP. Further, in LNCaP cells, while the level of PAcP mRNA diminished upon passage, the AR mRNA level remained approximately the same. Together, these data suggested that the differential expression of PAcP in different prostate carcinoma cells including high passages of LNCaP cells may occur at the transcriptional level and may have little linkage to the expression of AR.

Acid Phosphatase↗
PubMed1995

Computed tomography and magnetic resonance imaging of diffuse pigmented villonodular synovitis: report of a case.

We describe the computed tomographic (CT) and magnetic resonance imaging (MRI) features of a surgically proven case of diffuse pigmented villonodular synovitis (PVNS) of the knee in a 34-year-old woman. A complex mass consisting of solid and multicystic components was clearly demonstrated by CT and MRI. The solid part showed homogeneous hypodense attenuation relative to adjacent muscles on CT scans, but it showed inhomogeneous signal intensity on spin echo T1- and T2-weighted images (WI). The solid component enhanced homogeneously on CT scans but heterogeneously on MR images. Multiseptated enhancement of the cystic component on both CT and MR images were displayed. All of the above features were better demonstrated on MRI. Multiple marked hypointense round and patchy areas, and also a few areas isointense to subcutaneous fat within the lesion were also found on T1WI, proton density WI and T2WI. These characteristic MRI features of PVNS correlated well with its histologic structures: depositions of hemosiderin and fat in the proliferative synovial villi and bloody cystic content. These features may help to distinguish PVNS from other disease entities arising from the synovium.

Adult↗
PubMed1995

MRI appearance of spinal lesions: metastatic tumors or infections?

Three patients with pathologically verified spinal osteomyelitis and another three with metastatic tumors of the spine were investigated. MRI of th spine of four patients showed several unusual findings. The preservation of intervertebral discs and endplates did not predict accurately the diagnosis of either infections or tumors. The "pepper and salt" appearing feature may also occur in a metastatic tumor. Plain radiographs, CT, and radioisotope bone scans were less sensitive than MRI to disclose the lesions. In cases of osteomyelitis, the systemic sources of infections were frequently not found, and the responsible microorganisms could not be identified even from the surgical specimens of two patients. However, mycobacterium tuberculosis was found in the surgical specimen of a patient with cervical spinal lesion whose MRI was indistinguishable from a metastatic tumor. Surgicopathological diagnosis was therefore crucial and mandatory in these instances.

Adult↗
PubMed1992

Characterization of human androgen receptor overexpressed in the baculovirus system.

An essential step in the process of understanding the structure and function of the human androgen receptor (hAR) involves the production of large quantities of the hAR. For this purpose, the full-length hAR has been overproduced in insect cells by using a baculovirus genetic expression system. The recombinant hAR is produced in Sf21 insect cells at approximately 7 pmol/mg of protein (1 x 10(6) AR molecules per cell), which is 70-150 times greater than levels detected in androgen target tissues. Androgen can bind to the baculovirus-expressed hAR with high affinity (Kd = 0.46 nM), and the specificity of hormone binding in baculovirus-expressed hAR is essentially identical to that of bona fide hAR. An anti-AR monoclonal antibody can recognize the baculovirus-expressed hAR at approximately 100 kDa upon Western blot analysis. Sucrose gradient analysis shows that baculovirus-expressed hAR complexes sediment at 4 S in a high salt medium and these complexes can interact with anti-AR monoclonal antibody to form complexes that sediment at 8-10 S. Therefore, production of recombinant hAR from the baculovirus expression system will provide an alternative source of biologically active hAR for studies on the molecular mechanisms of androgen action.

Androgens↗