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S Y Kao

Publications and source records attributed to S Y Kao.

At least 19 recordsLinked to original sources
PubMed2003

Aspergillosis of the temporomandibular joint following irradiation of the parotid region: a case report.

We report a case of aspergillosis in the right temporomandibular joint (TMJ) with a history of parotid carcinoma and post-irradiation otitis. Previous treatment attempts with surgery and antibiotics were unsuccessful. Radical debridement of the glenoid fossae, supplemented with amphotericin B and adjunct hyperbaric oxygen (HBO) therapy, was provided to resolve the symptoms. This case report highlights the need to be aware of the possibility of invasive mycosis in immunocompromised patients.

Aged↗
PubMed2001

p53-independent induction of apoptosis by the HTLV-I tax protein following UV irradiation.

Human T cell leukemia virus type 1 (HTLV-1) encodes a transforming protein, Tax. Tax is a promiscuous viral transactivator involved in both cell growth and death control. We have previously shown that Tax sensitizes cells to apoptosis induced by DNA-damaging agents and this report further characterizes the Tax-mediated apoptosis pathway. We found that Tax-mediated apoptosis in response to UV irradiation was inhibited by Bcl-2 and Bcl-X(L) overexpression and by treatment with the caspase inhibitor z-VAd-FMK. Since Tax has been shown to functionally inactivate the apoptosis regulator p53, the effect of Tax on apoptosis in the absence of p53 was examined. In these studies, Tax sensitized p53-negative cells to apoptose, suggesting that Tax can mediate a p53-independent form of apoptosis. In addition, cells expressing both Tax and p53 displayed higher levels of apoptosis than cells expressing either protein alone, suggesting that the apoptosis-inducing activities of Tax and p53 are not completely overlapping. These observations demonstrate that Tax can utilize a p53-independent mechanism to induce apoptotic cell death following UV irradiation.

Amino Acid Chloromethyl Ketones↗
PubMed2001

Accumulation of mitochondrial DNA deletions in human oral tissues -- effects of betel quid chewing and oral cancer.

Accumulation of mitochondrial DNA (mtDNA) mutations in human tissues has been associated with intrinsic aging and environmental insult. Recently, mtDNA mutations have been detected in various tumors, including head and neck tumors. However, the factors affecting the occurrence and accumulation of mtDNA deletions in tumor tissues are poorly understood. In Taiwan, betel quid chewing is a major risk factor for oral cancer. Using polymerase chain reaction (PCR) techniques, we examined large-scale deletions of mtDNA in 53 pairs of tumor and non-tumor oral tissues from the patients with or without betel quid chewing history. The results revealed that irrespective of the history of betel quid chewing, the incidences of the 4977bp deletion and other deletions of mtDNA were lower in the tumor portion as compared with the non-tumor portion. The average proportions of the 4977bp deleted mtDNA in the tumor tissues of the betel quid chewers and non-betel quid chewers were 13- and 5-fold, respectively, lower than those in the corresponding non-tumor tissues. Moreover, the average proportion of 4977bp deleted mtDNA was significantly higher (P<0.05) in the non-tumor oral tissues of the patients with betel quid chewing history than that of the patients without the history of betel quid chewing. These results suggest that betel quid chewing may increase mtDNA mutation in human oral tissues and that accumulation of mtDNA deletions and subsequent cytoplasmic segregation of these mutations during cell division could be an important contributor to the early phase of oral carcinogenesis.

Areca↗
PubMed2001

In vitro cellular response of retinoic acid treated human oral cancer cell lines.

BACKGROUND: The purpose of this study is to identify the cellular response ofretinoic acid-treated human oral cancer cell lines. METHODS: Seven human oral cancer cell lines KB, SCC4, SCC9, SCC15, SCC25, OEC-M1, OC1 and OC2 were used for cell culture experiments. Direct cell number counting method was utilized to evaluate cellular response of these human oral cancer cells at the presence or absence of all-trans RA at 1 mM. RESULTS: Through 7-day observation, the cell population of SCC9, SCC15 and SCC25 of RA-treated groups decreased when compared with the non RA-treated groups. These three cell lines were further verified using [3H] thymidine incorporation DNA synthesis assay. KB, SCC4, OC1, OC2 and OEC-M1 cell lines did not show growth inhibition at the presence of RA at 1 mM. CONCLUSIONS: The molecular event of how SCC9, SCC15 and SCC25 are inhibited by RA and how KB, OC1, OC2 and OECM1 are resistant to RA can be further explored on the basis of this study.

Carcinoma, Squamous Cell↗
PubMed2000

Suppression of DNA repair by human T cell leukemia virus type 1 Tax is rescued by a functional p53 signaling pathway.

The Tax protein of human T cell leukemia virus type 1 is a viral transactivator and transforming protein. Tax is known to suppress cellular nucleotide excision repair (NER), and this activity has been proposed to play an important role in Tax transformation. In this study we have investigated the mechanism by which Tax suppresses NER with specific focus on the previously characterized ability of Tax to inhibit p53 function. Suppression of NER by Tax was rescued by overexpression of wild-type p53; however, a p53 transactivation-incompetent mutant did not restore NER activity. The cyclin-dependent kinase inhibitor p21, a major transcriptional target of p53, plays an important role in regulating DNA replication and repair. Overexpression of p21 reversed Tax-induced suppression of NER; however, a p21 C-terminal mutant that lacks the proliferating cell nuclear antigen binding domain did not restore NER activity. Thus, p53 and its downstream effector p21 can inhibit Tax-mediated suppression of DNA repair. These results imply that the inactivation of p53 function by Tax contributes to Tax suppression of DNA repair.

Animals↗
PubMed2000

Suppression of DNA repair by HTLV type 1 Tax correlates with Tax trans-activation of proliferating cell nuclear antigen gene expression.

The human T cell leukemia virus type 1 (HTLV-1) viral oncoprotein Tax acts as a transcriptional trans-activator affecting viral as well as cellular gene expression. To understand how Tax induces transformation, the consequences of its ability to alter expression of cellular genes must be examined. We have previously demonstrated that Tax activates expression of the cellular gene, proliferating cell nuclear antigen (PCNA), and that Tax suppresses DNA repair. In this study we tested the ability of previously described Tax mutants to activate PCNA gene expression and their ability to interfere with DNA repair. The results revealed a strong correlation between Tax trans-activation of PCNA gene expression and its ability to inhibit DNA repair via the nucleotide excision repair (NER) pathway. Thus, a consequence of activated PCNA gene expression appears to be reduced DNA repair capacity. These effects of Tax are likely to play important roles in its transforming activity.

Animals↗
PubMed2000

HTLV-1 Tax protein sensitizes cells to apoptotic cell death induced by DNA damaging agents.

Transient HTLV-1 Tax expression suppresses cellular nucleotide excision repair, and this effect correlates with Tax transactivation of the proliferating cell nuclear antigen promoter. The inability to repair DNA damage typically induces apoptotic cell death. Therefore, we investigated the effect of Tax-mediated suppression of DNA repair on apoptosis in stable Tax-expressing cells. Constitutive Tax expression reduced cellular nucleotide excision repair activity compared with parental and control cells. Tax-expressing cells were also more sensitive to apoptosis induced by DNA damaging agents than control cells. Even though Tax-expressing cells displayed reduced DNA repair, they showed increased DNA replication following UV damage. These results suggest that Tax suppresses the cell's ability to repair DNA damage and stimulates DNA replication even in the presence of damage. The inability to repair DNA damage is likely to stimulate apoptotic cell death in the majority of Tax-expressing cells while the ability to promote DNA replication may also allow the survival of a small population of cells. We propose that together these effects contribute to the monoclonal nature and low efficiency of HTLV-1 transformation.

Animals↗
PubMed2000

Comparison of quantitative cytomegalovirus (CMV) PCR in plasma and CMV antigenemia assay: clinical utility of the prototype AMPLICOR CMV MONITOR test in transplant recipients.

The correlation between the prototype AMPLICOR CMV MONITOR test (Roche Molecular Systems), a quantitative PCR assay, and the cytomegalovirus (CMV) pp65 antigenemia assay was evaluated in transplant recipients. Sequential blood specimens were collected on 29 patients (491 specimens), the leukocyte fraction was tested by CMV antigenemia, and quantitative PCR was performed on plasma specimens. None of the 15 patients (242 specimens) who were antigenemia negative were positive for CMV DNA by PCR, and none of these patients developed active CMV disease. There were 14 antigenemia-positive patients, 8 of whom developed active CMV disease. In all patients, there was a good association between the antigenemia and PCR assays. Ganciclovir-resistant virus was isolated from three patients with active CMV disease. These three patients had persistently elevated levels of antigenemia and CMV DNA by PCR when resistance to ganciclovir developed. This standardized, quantitative CMV PCR assay on plasma has clinical utility for the diagnosis of active disease and in monitoring the response to antiviral therapy in transplant recipients.

Adolescent↗
PubMed1999

Disruption of nucleotide excision repair by the human T-cell leukemia virus type 1 Tax protein.

The Tax protein of human T-cell leukemia virus type 1 (HTLV-1) is a transcriptional transactivator and viral oncogene. Since cellular transformation has been frequently linked to alterations in genome stability, we investigated the effect of Tax on nucleotide excision repair (NER), a prominent cellular DNA repair pathway. Cells expressing Tax exhibited a reduced capacity for NER as measured by unscheduled DNA synthesis and host cell reactivation assays. The cellular proliferating cell nuclear antigen (PCNA) gene product regulates DNA replication and repair pathways, including NER. Since Tax activates transcription of the PCNA promoter, we investigated whether this activity contributes to the reduction of NER. Tax increased endogenous PCNA protein expression, and analysis of Tax mutant proteins demonstrated that the reduction in NER correlated with Tax transactivation of PCNA gene expression. Direct overexpression of PCNA also reduced NER. We propose that overexpression of PCNA, and disruption of NER induced by Tax, predisposes cells to accumulate DNA damage and contributes to HTLV-1 transformation.

DNA Repair↗
PubMed1999

Using three-dimensional-computerized tomography as a diagnostic tool for temporo-mandibular joint ankylosis: a case report.

Roentgenographic examination has long been a useful diagnostic tool for temporo-mandibular joint (TMJ) disease. The methods include TMJ tomography, panoramic radiography and computerized tomography (CT) scan with or without injection of contrast media. Recently, three-dimensional CT (3D-CT), reconstructed from the two-dimensional image of a CT scan to simulate the soft tissue or bony structure of the real target, was proposed. In this report, a case of TMJ ankylosis due to traumatic injury is presented. 3D-CT was employed as one of the presurgical roentgenographic diagnostic tools. The conventional radiographic examination including panoramic radiography and tomography showed lesions in both sides of the mandible. CT scanning further suggested that the right-sided lesion was more severe than that on the left. With 3D-CT image reconstruction the size and extent of the lesions were clearly observable. The decision was made to proceed with an initial surgical approach on the right side. With condylectomy and condylar replacement using an autogenous costochondral graft on the right side, the range of mouth opening improved significantly. In this case report, 3D-CT demonstrates its advantages as a tool for the correct and precise diagnosis of TMJ ankylosis.

Ankylosis↗
PubMed1999

Coronal approach for the replacement of the condylar head in bilateral temporomandibular joint ankylosis: report of three cases.

Limitation of mouth opening has long been the chief complaint for patients who suffer from temporomandibular joint (TMJ) ankylosis. For surgical treatment of this disease, several ways have been employed for access to the condylar fossa, including the preauricular, postauricular, perimeatal, endaural and Risdon approaches. In this article, we report three patients with bilateral TMJ ankylosis who underwent replacement of both condylar heads using the bicoronal approach. The advantages demonstrated with this surgical technique are ease of access to the condylar head, ideal surgical exposure field, utility of temporalis muscle and fascia and minimal risk of facial paralysis.

Adult↗
PubMed1998

Detection of cytomegalovirus in plasma and cerebrospinal fluid specimens from human immunodeficiency virus-infected patients by the AMPLICOR CMV test.

We have developed the AMPLICOR CMV Test, which is rapid and sensitive for the detection of cytomegalovirus (CMV) in plasma and cerebrospinal fluid (CSF) specimens. The test incorporated an internal control in the reaction mixture to monitor the amplification efficiency and the presence of inhibitors. The AMPLICOR CMV Test was very specific in detecting 12 clinical CMV isolates and four laboratory CMV strains tested. Cross-reactivity with 26 non-CMV pathogens was not observed. The AMPLICOR CMV Test requires only 50 microl of specimen (plasma or CSF) for processing. The performance of the AMPLICOR CMV Test was compared to those of the CMV antigenemia assay and the conventional tube culture method. Among 112 plasma specimens from 43 human immunodeficiency virus-infected patients, CMV was detected in 20 (18%) of the specimens by the AMPLICOR CMV Test, 21 (19%) of the specimens by the CMV antigenemia assay, and 10 (9%) of the specimens by culture. In CSF specimens from AIDS patients, CMV was detected in 10 of 58 (17%) specimens tested by the AMPLICOR CMV Test, 5 of 28 (18%) specimens tested by the antigen assay, and none of the 25 specimens tested by culture. While the performance of the AMPLICOR CMV Test in this study was comparable to that of the CMV antigen assay, processing of specimens by the AMPLICOR CMV Test was much simpler than that by the antigen assay; in addition, the antigen assay requires greater than 10(5) leukocytes from blood or 1 ml of CSF to perform the assay. Our study suggested that the AMPLICOR CMV Test could provide a rapid and sensitive assay for the detection of CMV in plasma and CSF specimens.

AIDS-Related Opportunistic Infections↗
PubMed1996

Prospective comparison of culture vs genome detection for diagnosis of enteroviral meningitis in childhood.

OBJECTIVE: To assess the sensitivity and specificity of a new polymerase chain reaction (PCR) assay with uninterrupted reverse transcription and complementary DNA amplification (RT-PCR) for the diagnosis of enteroviral (EV) meningitis in children. DESIGN: A prospective, cohort study. SETTINGS: Two medical centers: 1 university hospital and 1 children's hospital in San Diego County, California, during a 5-week period. PATIENTS: All pediatric patients younger than 16 years who underwent a lumbar puncture for evaluation of possible meningitis. MAIN OUTCOME MEASURES: The results of cerebrospinal fluid (CSF) RT-PCR were compared with viral cultures and clinical histories. RESULTS: During the 5-week period, 90 patients were entered into the study. Nonpolio EVs were cultured from 10% (9/90) of the patients from the following sites: CSF, 6.7% (6/90) of the patients; stool, 19% (4/21) of the patients; and throat swabs, 5.6% (1/18) of the patients. The EV genome was detected in the CSF by using RT-PCR in 7 of 9 EV culture-positive patients. The sensitivity and specificity of the CSF RT-PCR assay to detect EV meningitis were 77.8% and 100%, respectively. This compared with a sensitivity of 66.7% for detection of EV in CSF by viral culture alone. CONCLUSION: The new RT-PCR assay is a rapid and reliable method for the detection of EV infection in childhood.

Child↗
PubMed1995

Maxillary odontogenic carcinoma with distant metastasis to axillary skin, brain, and lung: case report.

We present a case of odontogenic carcinoma with ghost-cell keratinization of the right maxilla, with a history of 23 years after initial treatment. Within this period, multiple local recurrence, as well as metastasis to axilla, brain, and lung, was noted. Several attempts at resection of the primary lesion were unsuccessful at achieving local control, even when supplemented with chemotherapy and radiotherapy. Metastatic tumors were studied histologically, and their morphology coincided with that of the primary tumor. The medical history of the patient and pathologic findings of the tumor are reviewed.

Axilla↗
PubMed1995

Direct and uninterrupted RNA amplification of enteroviruses with colorimetric microwell detection.

BACKGROUND: Enteroviruses (EV) cause a broad spectrum of human diseases, of which aseptic meningitis is among the most common and most clinically vexing. While the clinical symptoms of meningitis caused by bacteria, fungi and viruses are similar, the diagnosis, therapy and outcome of disease caused by these agents vary greatly. In order to appropriately manage meningitis patients, rapid and reliable diagnosis of EV meningitis impacts significantly on patient management. OBJECTIVE: To develop a direct and uninterrupted RNA amplification of enteroviruses using rTth DNA polymerase. STUDY DESIGN: Purified coxsackievirus B6 RNA of various concentrations was amplified by rTth DNA polymerase-mediated amplification to determine analytic sensitivity. The specificity of the EV amplification was examined with a panel of nucleic acids from 36 EV serotypes, 15 non-EV pathogens and 10 coded clinical specimens of cerebrospinal fluid (CSF). RESULTS: All EV serotypes tested were detected successfully by this method at a sensitivity of 1 TCID(50) with the exception of echoviruses 1, 5, 22 and 23. Echovirus 5 was detected at 10 TCID(50), and echovirus 1 was detected at 100 TCID(50). Echoviruses 22 and 23 were not detectable at 100 TCID(50). Cross-reactivity of EV RT-PCR assay with 15 known non-EV meningitis pathogens has not been observed. Results of 10 CSF tested with this system correlated well with tissue culture. CONCLUSIONS: We have developed an EV amplification assay which has several important advantages over previously reported methods. This assay employs rTth DNA polymerase which possesses both reverse transcriptase and DNA polymerase activities, simplifying RNA reverse transcription and DNA amplification to an uninterrupted reaction. Additionally, potential carryover contamination and enhanced amplification specificity is provided by substituting dUTP for dTTP and adding uracil N-glycosylase (UNG) in the amplification reaction. Finally, the detection of amplified product is via a colorimetric, microwell format permitting the use of readily available instrumentation.

Journal Article↗
PubMed1995

Rapid decline in FEV1. A new risk factor for coronary heart disease mortality.

Coronary heart disease (CHD) is the leading cause of mortality in the United States. The present cohort study was conducted to determine whether rate of FEV1 loss independently predicts CHD mortality in apparently healthy men. White male Baltimore Longitudinal Study of Aging (BLSA) participants without CHD underwent clinical evaluation at 2-yr intervals; 883 had satisfactory pulmonary and lipid studies and returned for a least one visit. Cases were BLSA subjects without CHD on entry who died a "coronary death" (death from acute myocardial infarction, sudden death, or congestive heart failure in the presence of coronary artery disease). Forced expiratory maneuvers followed American Thoracic Society guidelines. Serum cholesterol, blood pressure, cigarette smoking, and body mass index were obtained from the BLSA database. There were 79 CHD deaths and 804 survivors during an average follow-up of 17.4 yr. After adjustment for age, initial FEV1% predicted, smoking status, hypertension, and cholesterol, a time-dependent proportional hazards model showed that cardiac mortality, but not all causes of mortality, generally increased with increasing quintile of FEV1 decline for the entire cohort (relative risk [RR] 2.92-5.13) and separately for the subset of never-smokers. Thus, excess CHD mortality follows a large decline in FEV1, independent of the initial FEV1% predicted, cigarette smoking, and other common CHD risk factors.

Adolescent↗
PubMed1994

Diagnosis of enteroviral meningitis by using PCR with a colorimetric microwell detection assay.

A 5-h, user-friendly PCR assay for the diagnosis of enteroviral meningitis was developed. Reverse transcription and amplification were performed in a one-step reaction using rTth polymerase. Carryover contamination was prevented with dUTP and uracil N-glycosylate. Detection was performed colorimetrically on a microwell titer plate. Sensitivity, specificity, positive predictive value, and negative predictive value were 94.7, 97.4, 94.7, and 97.4%, respectively.

Base Sequence↗