Biomedical subjects

Y Y Yau

Publications and source records attributed to Y Y Yau.

5 recordsLinked to original sources

PubMed2006

Relationship between pretreatment level of plasma Epstein-Barr virus DNA, tumor burden, and metabolic activity in advanced nasopharyngeal carcinoma.

PURPOSE: Plasma Epstein-Barr virus DNA (pEBV DNA) is an important prognostic marker in nasopharyngeal carcinoma (NPC). This study tested the hypotheses that pEBV DNA reflects tumor burden and metabolic activity by evaluating its relationship with tumor volume and 18F-fluorodeoxyglucose (18F-FDG) uptake in NPC. METHODS AND MATERIALS: Pre-treatment pEBV DNA analysis, 18F-FDG positron emission tomography-computed tomography scan (PET-CT) and magnetic resonance imaging (MRI) of the head and neck were performed in 57 patients. Net volume (cm3) of the primary tumor (T(vol)) and regional nodes (N(vol)) were quantified on MRI. 18F-FDG uptake was expressed as the maximum standardized uptake value (SUV(max)) at the primary tumor (T(suv)) and regional nodes (N(suv)). Lesions with SUV(max) > or = 2.5 were considered malignant. Relationship between SUV(max), natural logarithm (log) of pEBV DNA, and square root (sq) of MRI volumes was analyzed using the Wilcoxon test. A linear regression model was constructed to test for any interaction between variables and disease stage. RESULTS: Log-pEBV DNA showed significant correlation with sq-T(vol) (r = 0.393), sq-N(vol) (r = 0.452), total tumor volume (sq-Total(vol) = T(vol) + N(vol), r = 0.554), T(suv) (r = 0.276), N(suv) (r = 0.434), and total SUV(max) (Total(suv) = T(suv) + N(suv), r = 0.457). Likewise, sq-T(vol) was correlated to T(suv) (r = 0.426), and sq-N(vol) with N(suv) (r = 0.651). Regression analysis showed that only log-pEBV DNA was significantly associated with sq-Total(vol) (p < 0.001; parameter estimate = 8.844; 95% confidence interval = 3.986-13.703), whereas Sq-T(vol) was significantly associated with T(suv) (p = 0.002; parameter estimate = 3.923; 95% confidence interval = 1.498-6.348). CONCLUSION: This study supports the hypothesis that cell-free plasma EBV DNA is a marker of tumor burden in EBV-related NPC.

Adult↗

PubMed2004

Advances in imaging of the solitary pulmonary nodule.

OBJECTIVE: To review the radiological management of a solitary pulmonary nodule. DATA SOURCES: MEDLINE literature search (1958-2002). STUDY SELECTION: All review articles and original articles. Key words for the literature search were 'solitary pulmonary nodule' and 'imaging'. DATA EXTRACTION: All relevant information and data. DATA SYNTHESIS: The solitary pulmonary nodule remains a perennial problem in radiological practice, particularly with current trends using low-dose computed tomography to screen for lung cancer. Determining the likelihood of malignancy forms the basis of the radiological approach of a solitary pulmonary nodule. Several factors that influence risk analysis include morphological and enhancement characteristics of the solitary pulmonary nodule on imaging, stability of the nodule, age of patient, smoking history, and history of malignant disease. Other ancillary procedures and imaging techniques that assist in the evaluation of a solitary pulmonary nodule include fluorodeoxyglucose positron-emission tomography, technetium Tc 99m depreotide imaging, bronchoscopy with bronchioloalveolar lavage and biopsy, image-guided transthoracic needle aspiration biopsy, video-assisted thorascopic surgery, and thoracotomy. CONCLUSIONS: The success of any radiological management of a solitary pulmonary nodule rests on careful clinical evaluation and risk stratification for malignancy before the implementation of appropriate imaging techniques.

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PubMed2001

Administration of G--CSF plus dexamethasone produces greater granulocyte concentrate yields while causing no more donor toxicity than G--CSF alone.

BACKGROUND: G-CSF with or without dexamethasone is becoming the standard agent for mobilizing granulocytes for transfusion. The purpose of this study was to determine if the toxicities of G--CSF with or without dexamethasone are offset by greater collection yields and to define the minimum interval that should separate sequential collections. STUDY DESIGN AND METHODS: Twenty donors were studied on three occasions. They were given either dexamethasone (8 mg, by mouth) plus a placebo injection, G--CSF (5 microg/kg, given subcutaneously) plus placebo capsules, or G--CSF plus dexamethasone. Granulocytes were collected by apheresis. A donor symptom survey was administered, and cell counts and blood chemistries were assessed before collection and 1, 2, 7, 14, 21, 28, and 35 days after collection. RESULTS: More granulocytes were collected when G--CSF was given than when dexamethasone was given (41.1 +/- 20.4 x 10(9) vs. 21.0 +/- 10.0 x 10(9); p<0.001), but the use of G--CSF plus dexamethasone produced the greatest yields (67.1 +/- 22.0 x 10(9); p<0.002). When the donors were given dexamethasone alone, 58 percent experienced at least one symptom, compared to 85 percent of those given G--CSF and 75 percent of those given G--CSF plus dexamethasone. In all three regimens, platelet counts fell 19 percent to 24 percent after collection and remained below baseline for 7 to 14 days. Granulocyte counts returned to baseline within 3 to 7 days, but, in all three regimens, a mild granulocytopenia occurred 21 days after collection. With each of the regimens, blood chemistries changed, but the changes were mild and most returned to baseline within 7 days; however, changes in albumin, bilirubin, and AST persisted until 28 days after collection. CONCLUSION: These results support the use of G--CSF plus dexamethasone in granulocyte donors. G--CSF plus dexamethasone resulted in greater granulocyte yields than either agent alone and was associated with donor symptoms and changes in blood cell counts and chemistries similar to those seen with G--CSF alone or dexamethasone alone. Granulocytes can be safely collected a second time after a 7-day interval; however, for regular donors, it may be best to separate collections by 4 weeks.

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PubMed1995

Technical note: maxillofacial biomodelling--preliminary result.

A new technique of manufacturing three-dimensional (3D) hard tissue biomodels is described. The models, derived from computed tomography data, were constructed by a computer-controlled manufacturing device known as stereolithography apparatus (SLA). Selected cases of patients with facial deformities were presented to illustrate clinical applications of the SLA biomodelling. Physical demonstration of the bony internal anatomy in these patients promoted better conceptualization of the disease process, allowing optimal input into the management decision, pre-operative planning and choice of surgical technique with a consequent reduction in operating time and potential reduction in peri-operative morbidity. Limitations of the solid modelling technique include cost, a lengthy production time which renders it unsuitable for emergency cases, and radiation exposure of the patient. With wider use and further technological development, these drawbacks will be minimized. The 3D SLA biomodels may in future become an adjunct, not only to maxillofacial surgery, but also to other medical specialties.

Adult↗

PubMed1994

Maxillofacial biomodelling.

The authors report the clinical applications of biomodelling with the stereolithography apparatus, a computer-controlled manufacturing technique that builds anatomically accurate skeletal models from sectional radiological data. Reference to several individual cases demonstrates how pre-operative 3-D modelling can refine the accuracy of diagnostic information, facilitate preoperative planning and surgical technique, and reduce operating time.

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