Biomedical subjects

John Gillespie

Publications and source records attributed to John Gillespie.

7 recordsLinked to original sources

PubMed2006

Carbon nanotube amplification strategies for highly sensitive immunodetection of cancer biomarkers.

We describe herein the combination of electrochemical immunosensors using single-wall carbon nanotube (SWNT) forest platforms with multi-label secondary antibody-nanotube bioconjugates for highly sensitive detection of a cancer biomarker in serum and tissue lysates. Greatly amplified sensitivity was attained by using bioconjugates featuring horseradish peroxidase (HRP) labels and secondary antibodies (Ab(2)) linked to carbon nanotubes (CNT) at high HRP/Ab(2) ratio. This approach provided a detection limit of 4 pg mL(-)(1) (100 amol mL(-)(1)), for prostate specific antigen (PSA) in 10 microL of undiluted calf serum, a mass detection limit of 40 fg. Accurate detection of PSA in human serum samples was demonstrated by comparison to standard ELISA assays. PSA was quantitatively measured in prostate tissue samples for which PSA could not be differentiated by the gold standard immunohistochemical staining method. These easily fabricated SWNT immunosensors show excellent promise for clinical screening of cancer biomarkers and point-of-care diagnostics.

Biomarkers, Tumor↗

PubMed2006

Outbreak in Alberta of community-acquired (USA300) methicillin-resistant Staphylococcus aureus in people with a history of drug use, homelessness or incarceration.

BACKGROUND: The USA300 strain of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) can cause severe infection and is increasingly recognized as a cause of community outbreaks. In 2004, an outbreak was identified in the Calgary Health Region (CHR). METHODS: MRSA isolates were identified with standard methods at a central regional laboratory and typed via pulsed-field gel electrophoresis (PFGE). Isolates were tested by PCR for mecA, Panton-Valentine leukocidin (PVL), SCCmec, and spa genes. Cases were defined as such if a clinical isolate of the USA300 strain was noted between January 1 and September 30, 2004, and the patient had lived or traveled in CHR within 2 years before symptom onset. Demographic, clinical and risk data on all such cases were collected from several sources for statistical analysis. A case was defined as high-risk if the patient had a history of drug use, homelessness or incarceration. RESULTS: Of 40 isolates with the USA300 PFGE pattern, all tested positive for PVL, SCCmec type IVa and spa type 008. Almost all infections (39/40, 98%) involved skin and soft tissues, except for 1 death from necrotizing hemorrhagic pneumonia; a notable proportion (38%) required hospital admission or intravenous antimicrobial therapy. The outbreak centred on the high-risk population in CHR (70%; risk ratio 169.4, 95% confidence interval 86.1-333.0). INTERPRETATION: People with histories of illicit drug use, homelessness or recent incarceration were at highest risk for infection with CA-MRSA. The emergence and spread of this virulent strain has important implications for treatment and public health in Canada.

Alberta↗

PubMed2006

Development and application of a high-performance liquid chromatography method using monolithic columns for the analysis of ecstasy tablets.

A rapid and selective HPLC method using monolithic columns was developed for the separation and quantification of the principal amphetamines in ecstasy tablets. Three monolithic (Chromolith RP18e) columns of different lengths (25, 50 and 100 mm) were assessed. Validation studies including linearity, selectivity, precision, accuracy and limit of detection and quantification were carried out using the Chromolith SpeedROD, RP-18e, 50 mm x 4.6 mm column. Column backpressure and van Deemter plots demonstrated that monolithic columns provide higher efficiency at higher flow rates when compared to particulate columns without the loss of peak resolution. Application of the monolithic column to a large number of ecstasy tablets seized in Ireland ensured its suitability for the routine analysis of ecstasy tablets.

3,4-Methylenedioxyamphetamine↗

PubMed2004

Heterogeneous gene methylation patterns among pre-invasive and cancerous lesions of the prostate: a histopathologic study of whole mount prostate specimens.

BACKGROUND: Gene methylation may contribute to prostate carcinogenesis through the silencing of gene transcription. We report on the methylation status of several genes shown to be silenced at different stages of progression using whole mount prostate specimens and laser capture microdissection. This is the first study to evaluate gene methylation patterns across multiple pre-cancerous and invasive cancer foci from the same prostate gland. METHODS: Real-time PCR was used to evaluate methylation of five genes (GSTP1, RASSF1A, RAR beta 2, CD44, and EDNRB) across normal epithelium, high-grade prostatic intraepithelial neoplasia (HGPIN), and multiple tumor foci from each of 11 prostate cancer patients. RESULTS: Gene methylation was not found in normal epithelium. To our knowledge, this is the first report of RASSF1A and RAR beta 2 methylation in HGPIN lesions (30% prevalence for each gene). In addition, RASSF1A, RAR beta 2, and GSTP1 methylation was highly prevalent in tumor foci (>75% for all three genes). Methylation of CD44 and EDNRB was observed in 41 and 38% of tumors but was not present in HGPIN. CONCLUSIONS: These data suggest that genes may be methylated at different points in the histopathologic progression of prostate cancer and these differences can be found in various histologic foci from the same gland.

Cell Transformation, Neoplastic↗

PubMed2003

Identification of TDE2 gene and its expression in non-small cell lung cancer.

TDE2, a gene with sequence similarity to the mouse testicular tumor-differentially-expressed (Tde1/MUSTETU) gene, was identified by serial analysis of gene expression (SAGE) in nonsmall cell lung cancers (NSCLC). Here we characterized the TDE2 gene and determined its transcript levels in a panel of lung tumors, adjacent nonmalignant lung tissues and a variety of normal human tissues. In addition, we show that TDE2 is a potential transmembrane protein with 11 putative transmembrane helices. Using real-time quantitative PCR, we showed that TDE2 transcript levels were higher in NSCLC compared to nonmalignant samples. In nonpulmonary normal tissues, the level of TDE2 was the highest in bladder, kidney and muscle; moderate to low in stomach, liver, skin, placenta and ovary tissues; and undetectable in brain, spleen and heart. By in situ hybridization, we showed that 10 of 18 lung tumors and only 1 of 14 adjacent nonmalignant regions had high levels of TDE2 transcripts. Alternatively, only 2 of 18 tumors and 8 of 14 adjacent nonmalignant bronchiole epithelium regions demonstrated negative to low levels of TDE2 signals.

Amino Acid Sequence↗

PubMed2003

Signal pathway profiling of prostate cancer using reverse phase protein arrays.

Reverse phase protein arrays represent a new proteomics microarray technology with which to study the fluctuating state of the proteome in minute quantities of cells. The activation status of cell signaling pathways controls cellular fate and deregulation of these pathways underpins carcinogenesis. Changes in pathway activation that occur between early stage prostatic epithelial lesions, prostatic stroma and the extracellular matrix can be analyzed by obtaining pure populations of cell types by laser capture microdissection (LCM) and analyzing the relative states of several key phosphorylation points within the cellular circuitry. We have applied reverse phase protein array technology to analyze the status of key points in cell signaling involved in pro-survival, mitogenic, apoptotic and growth regulation pathways in the progression from normal prostate epithelium to invasive prostate cancer. Using multiplexed reverse phase protein arrays coupled with LCM, the states of signaling changes during disease progression from prostate cancer study sets were analyzed. Focused analysis of phospho-specific endpoints revealed changes in cellular signaling events through disease progression and between patients. We have used a new protein array technology to study specific molecular pathways believed to be important in cell survival and progression from normal epithelium to invasive carcinoma directly from human tissue specimens. With the advent of molecular targeted therapeutics, the identification, characterization and monitoring of the signaling events within actual human biopsies will be critical for patient-tailored therapy.

Antigens, Neoplasm↗

PubMed2002

Role of advanced 2 and 3-dimensional ultrasound for detecting prostate cancer.

PURPOSE: We explored the clinical usefulness of spectrum analysis and neural networks for classifying prostate tissue and identifying prostate cancer in patients undergoing transrectal ultrasound for diagnostic or therapeutic reasons. MATERIALS AND METHODS: Data on a cohort of 215 patients who underwent transrectal ultrasound guided prostate biopsies at Memorial-Sloan Kettering Cancer Center, New York, New York were included in this study. Radio frequency data necessary for 2 and 3-dimensional (D) computer reconstruction of the prostate were digitally recorded at transrectal ultrasound and prostate biopsy. The data were spectrally processed and 2-D tissue typing images were generated based on a pre-trained neural network classification. We used manually masked 2-D tissue images as building blocks for generating 3-D tissue images and the images were tissue type color coded using custom software. Radio frequency data on the study cohort were analyzed for cancer probability using the data set pre-trained by neural network methods and compared with conventional B-mode imaging. ROC curves were generated for the 2 methods using biopsy results as the gold standard. RESULTS: The mean area under the ROC curve plus or minus SEM for detecting prostate cancer for the conventional B-mode and neural network methods was 0.66 +/- 0.03 and 0.80 +/- 0.05, respectively. Sensitivity and specificity for detecting prostate cancer by the neural network method were significantly increased compared with conventional B-mode imaging. In addition, the 2 and 3-D prostate images provided excellent visual identification of areas with a higher likelihood of cancer. CONCLUSIONS: Spectrum analysis could significantly improve the detection and evaluation of prostate cancer. Routine real-time application of spectrum analysis may significantly decrease the number of false-negative biopsies and improve the detection of prostate cancer at transrectal ultrasound guided prostate biopsy. It may also provide improved identification of prostate cancer foci during therapeutic intervention, such as brachytherapy, external beam radiotherapy or cryotherapy. In addition, 2 and 3-D images with prostate cancer foci specifically identified can help surgical planning and may in the distant future be an additional reliable noninvasive method of selecting patients for prostate biopsy.

Area Under Curve↗