Phan Nguyen - Academia.edu (original) (raw)
Papers by Phan Nguyen
Biomedical …, 2004
Optophoresis is a non-invasive cell analysis technique that is based on the interaction of live w... more Optophoresis is a non-invasive cell analysis technique that is based on the interaction of live whole cells with optical gradient ®elds, typically generated by a near-infrared laser. The magnitude of the interaction depends upon the intrinsic physical properties of the cells, such as their refractive index, composition, size, and morphology. Time-of-¯ight (TOF) optophoresis is an implementation of this technique in a micro¯uidic environment. It measures cell travel times through a ®xed distance with and without irradiation from a laser beam. The magnitude of the optical force from the laser, and therefore the change in transit time introduced by the presence of the infrared laser provides a signature for the cell. By accumulating such measurements for a population of cells (typically 200±300 cells per population), different cell types, drug treatments, or biological states can be compared quantitatively without the need for external labels or markers. An integrated TOF system has been constructed and characterized. The system typically uses square capillaries with 50±100 mm internal diameter and uses a syringe-pump-based¯ow system that generates initial bulk¯ow velocities between 200 and 600 mm/sec. Using this TOF technique, we have been able to consistently detect signi®cant differences between normal skin and melanoma cell lines, CCD-1037 and A375, respectively. We have also been able to measure consistent differences in a cell differentiation model (HL60 cell line with DMSO treatment). These early results indicate the potential biological sensitivity of the TOF measurement technique for cellular analysis and cancer diagnostic applications.
Journal of bronchology & interventional pulmonology, 2010
Background and Objectives: Autofluorescence (AF) techniques improve the diagnostic yield of white... more Background and Objectives: Autofluorescence (AF) techniques improve the diagnostic yield of white light inspection for preneoplastic lesions in the bronchus and head and neck region. Although highly sensitive, AF has poor specificity, particularly in situations where there have been earlier biopsies or treatments such as radiotherapy. Narrow band imaging (NBI) is a newer imaging technique that enhances the early abnormal angiogenesis seen in preneoplastic lesions. NBI has higher specificity when compared with AF. We aimed to combine these imaging modalities, using AF as an effective screening tool and NBI to confirm AF findings. We also used computer-assisted image analysis techniques to give objective confirmation to our visual inspection.
Respirology, 2014
There is widespread adoption of FDG-PET/CT in staging of lung cancer, but no universally accepted... more There is widespread adoption of FDG-PET/CT in staging of lung cancer, but no universally accepted criteria for classifying thoracic nodes as malignant. Previous studies show high negative predictive values, but reporting criteria and positive predictive values varies. Using Endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) results as gold standard, we evaluated objective FDG-PET/CT criteria for interpreting mediastinal and hilar nodes and compared this to expert visual interpretation (EVI). Methods: A retrospective review of all patients with lung cancer who had both FDG-PET/CT and EBUS-TBNA from 2008 to 2010 was performed. Scan interpretation was blinded to histology. Patients from 2008/ 2009 were used for the prediction set.The validation set analysed patients from 2010. Objective FDG-PET/CT criteria were SUVmax lymph node (SUVmaxLN), ratio SUVmaxLN/SUVmax primary lung malignancy, ratio SUVmaxLN/SUVaverage liver, ratio SUVmaxLN/ SUVmax liver and ratio SUVmaxLN/SUVmax blood pool. A nuclear medicine physician reviewed all scans and classified nodal stations as benign or malignant. Results: Eighty-seven malignant lymph nodes and 41 benign nodes were in the prediction set. All objective FDG-PET/CT criteria analysed were significantly higher in the malignant group (P < 0.0001). EVI correctly classified 122/128 nodes (95.3%). Thirty-four malignant nodes and 19 benign nodes were in the validation set. The new proposed cut-off values of the objective criteria from the prediction set correctly classified 44/53 (83.0%) nodes: 28/34 (82.4%) malignant nodes and 16/19 (84.2%) benign nodes. EVI had 91% accuracy: 33/34 (97.1%) malignant nodes and 15/19 (79.0%) benign nodes.
Background: Fatty acid ethyl esters (FAEEs) are nonoxidative ethanol metabolites that have been i... more Background: Fatty acid ethyl esters (FAEEs) are nonoxidative ethanol metabolites that have been implicated as mediators of alcohol-induced organ damage. FAEEs are detectable in the blood after ethanol ingestion, and on that basis have been proposed as markers of ethanol intake. Because blood is not always available at autopsy, in this study we quantified FAEEs in human liver and adipose tissue as potential postmortem markers of premortem ethanol intake. Methods: Twenty-four sets of samples were collected at the Massachusetts State Medical Examiner's Office, and 7 sets of samples were obtained from the Pathology Department of Massachusetts General Hospital. Samples of liver and adipose tissue were collected at autopsy, and FAEEs were isolated and quantified from these organs as mass per gram of wet weight. Postmortem analysis of blood involved assessment for ethanol and other drugs. Results: The study shows a substantial difference in FAEE concentrations in liver and adipose tissue of patients with detectable blood ethanol at the time of autopsy vs those with no detectable blood ethanol, who were either chronic alcoholics or social drinkers. In addition, a specific FAEE, ethyl arachidonate, was found at concentrations >200 pmol/g almost exclusively in the liver and adipose tissue of individuals with detectable blood ethanol at the time of death, providing an additional FAEE-related marker for prior ethanol intake. Conclusions: The mass of FAEEs in liver and adipose tissue and the presence of ethyl arachidonate can serve as postmortem markers of premortem ethanol intake when no blood sample can be obtained.
Head & Neck, 2013
Background. The purpose of this study was to evaluate combined autofluorescence (AF) and narrow b... more Background. The purpose of this study was to evaluate combined autofluorescence (AF) and narrow band imaging (NBI) for detection of mucosal lesions additional to known primary head and neck cancers and to determine impact on management.
Biomedical …, 2004
Optophoresis is a non-invasive cell analysis technique that is based on the interaction of live w... more Optophoresis is a non-invasive cell analysis technique that is based on the interaction of live whole cells with optical gradient ®elds, typically generated by a near-infrared laser. The magnitude of the interaction depends upon the intrinsic physical properties of the cells, such as their refractive index, composition, size, and morphology. Time-of-¯ight (TOF) optophoresis is an implementation of this technique in a micro¯uidic environment. It measures cell travel times through a ®xed distance with and without irradiation from a laser beam. The magnitude of the optical force from the laser, and therefore the change in transit time introduced by the presence of the infrared laser provides a signature for the cell. By accumulating such measurements for a population of cells (typically 200±300 cells per population), different cell types, drug treatments, or biological states can be compared quantitatively without the need for external labels or markers. An integrated TOF system has been constructed and characterized. The system typically uses square capillaries with 50±100 mm internal diameter and uses a syringe-pump-based¯ow system that generates initial bulk¯ow velocities between 200 and 600 mm/sec. Using this TOF technique, we have been able to consistently detect signi®cant differences between normal skin and melanoma cell lines, CCD-1037 and A375, respectively. We have also been able to measure consistent differences in a cell differentiation model (HL60 cell line with DMSO treatment). These early results indicate the potential biological sensitivity of the TOF measurement technique for cellular analysis and cancer diagnostic applications.
Journal of bronchology & interventional pulmonology, 2010
Background and Objectives: Autofluorescence (AF) techniques improve the diagnostic yield of white... more Background and Objectives: Autofluorescence (AF) techniques improve the diagnostic yield of white light inspection for preneoplastic lesions in the bronchus and head and neck region. Although highly sensitive, AF has poor specificity, particularly in situations where there have been earlier biopsies or treatments such as radiotherapy. Narrow band imaging (NBI) is a newer imaging technique that enhances the early abnormal angiogenesis seen in preneoplastic lesions. NBI has higher specificity when compared with AF. We aimed to combine these imaging modalities, using AF as an effective screening tool and NBI to confirm AF findings. We also used computer-assisted image analysis techniques to give objective confirmation to our visual inspection.
Respirology, 2014
There is widespread adoption of FDG-PET/CT in staging of lung cancer, but no universally accepted... more There is widespread adoption of FDG-PET/CT in staging of lung cancer, but no universally accepted criteria for classifying thoracic nodes as malignant. Previous studies show high negative predictive values, but reporting criteria and positive predictive values varies. Using Endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) results as gold standard, we evaluated objective FDG-PET/CT criteria for interpreting mediastinal and hilar nodes and compared this to expert visual interpretation (EVI). Methods: A retrospective review of all patients with lung cancer who had both FDG-PET/CT and EBUS-TBNA from 2008 to 2010 was performed. Scan interpretation was blinded to histology. Patients from 2008/ 2009 were used for the prediction set.The validation set analysed patients from 2010. Objective FDG-PET/CT criteria were SUVmax lymph node (SUVmaxLN), ratio SUVmaxLN/SUVmax primary lung malignancy, ratio SUVmaxLN/SUVaverage liver, ratio SUVmaxLN/ SUVmax liver and ratio SUVmaxLN/SUVmax blood pool. A nuclear medicine physician reviewed all scans and classified nodal stations as benign or malignant. Results: Eighty-seven malignant lymph nodes and 41 benign nodes were in the prediction set. All objective FDG-PET/CT criteria analysed were significantly higher in the malignant group (P < 0.0001). EVI correctly classified 122/128 nodes (95.3%). Thirty-four malignant nodes and 19 benign nodes were in the validation set. The new proposed cut-off values of the objective criteria from the prediction set correctly classified 44/53 (83.0%) nodes: 28/34 (82.4%) malignant nodes and 16/19 (84.2%) benign nodes. EVI had 91% accuracy: 33/34 (97.1%) malignant nodes and 15/19 (79.0%) benign nodes.
Background: Fatty acid ethyl esters (FAEEs) are nonoxidative ethanol metabolites that have been i... more Background: Fatty acid ethyl esters (FAEEs) are nonoxidative ethanol metabolites that have been implicated as mediators of alcohol-induced organ damage. FAEEs are detectable in the blood after ethanol ingestion, and on that basis have been proposed as markers of ethanol intake. Because blood is not always available at autopsy, in this study we quantified FAEEs in human liver and adipose tissue as potential postmortem markers of premortem ethanol intake. Methods: Twenty-four sets of samples were collected at the Massachusetts State Medical Examiner's Office, and 7 sets of samples were obtained from the Pathology Department of Massachusetts General Hospital. Samples of liver and adipose tissue were collected at autopsy, and FAEEs were isolated and quantified from these organs as mass per gram of wet weight. Postmortem analysis of blood involved assessment for ethanol and other drugs. Results: The study shows a substantial difference in FAEE concentrations in liver and adipose tissue of patients with detectable blood ethanol at the time of autopsy vs those with no detectable blood ethanol, who were either chronic alcoholics or social drinkers. In addition, a specific FAEE, ethyl arachidonate, was found at concentrations >200 pmol/g almost exclusively in the liver and adipose tissue of individuals with detectable blood ethanol at the time of death, providing an additional FAEE-related marker for prior ethanol intake. Conclusions: The mass of FAEEs in liver and adipose tissue and the presence of ethyl arachidonate can serve as postmortem markers of premortem ethanol intake when no blood sample can be obtained.
Head & Neck, 2013
Background. The purpose of this study was to evaluate combined autofluorescence (AF) and narrow b... more Background. The purpose of this study was to evaluate combined autofluorescence (AF) and narrow band imaging (NBI) for detection of mucosal lesions additional to known primary head and neck cancers and to determine impact on management.