Biomedical subjects

Robert C Duncan

Publications and source records attributed to Robert C Duncan.

6 recordsLinked to original sources

PubMed2004

The application of gene expression microarray technology to kinetoplastid research.

Protozoan parasites in the order Kinetoplastida cause severe disease primarily in tropical and subtropical areas. Vaccines to control these diseases have shown some promise, but none are in active clinical use. Drug treatments are available for all of the acute infections, but the emergence of resistance and an unresponsive chronic phase are current problems. Rapid advances in genomic technology open the possibility of discovering new genes that can contribute to vaccine initiatives or serve as targets for development of new drugs. The DNA microarray is a genomic technology, which is being applied to new gene discovery in kinetoplastid parasites. Both cDNA and genomic microarrays for Leishmania major have identified a number of new genes that are expressed in a stage-specific fashion and preliminary results from a L. donovani genomic microarray also demonstrated new gene discovery. A microarray of Trypanosoma brucei genomic fragments identified new genes whose expression differs between the insect borne stage and the human infectious stage of the parasite. The next few years, building on this foundational work, should witness the most exciting stage as microarrays are applied to questions such as the basis of drug resistance, post kala azar dermal leishmaniasis, the regulation of differentiation to infectious stages, linking coordinately regulated pathways of genes and development of genetically defined parasites that may have potential as live attenuated vaccines.

Animals↗

PubMed2003

Evaluation of the prognostic potential of hyaluronic acid and hyaluronidase (HYAL1) for prostate cancer.

Despite the development of nomograms designed to evaluate the prognosis of a patient with prostate cancer (CaP), the information has been limited to prostate-specific antigen (PSA), clinical stage, Gleason score, and tumor volume estimates. To improve our ability to predict prognosis, information regarding the molecular properties of CaP is needed. Hyaluronic acid (HA) is a glycosaminoglycan that promotes tumor metastasis. Hyaluronidase (HAase) is an enzyme that degrades HA into angiogenic fragments. We recently showed that in CaP tissues, whereas HA is localized mostly in the tumor-associated stroma, HYAL1 type HAase is exclusively localized in CaP cells (Lokeshwar et al. J. Biol. Chem., 276: 11922-11932, 2001). We evaluated the prognostic potential of HA and HYAL1 in CaP by immunohistochemistry. Archival CaP specimens were obtained from patients who underwent radical retropubic prostatectomy for clinically localized CaP. Group 1 (n = 25) included patients who showed biochemical recurrence (PSA >0.4 ng/ml; mean recurrence: 21.3 months). Group 2 included patients with no clinical or biochemical recurrence (n = 45; mean follow-up: 80.9 months). For HA and HYAL1 staining, a biotinylated HA-binding protein and an anti-HYAL1 antibody were used. The staining was evaluated on the basis of intensity (0 to 3+) and as dense or sparse (for HA staining only) and then grouped as low grade and high grade. In CaP specimens, HYAL1 was exclusively expressed in tumor cells. Although the stroma was stained positive for HA, 40% of tumor cells also expressed HA. HA, HYAL1, and combined HA-HYAL1 staining predicted progression with 96%, 84%, and 88% sensitivity, 55.5%, 80%, and 84.4% specificity, and 70%, 81.4%, and 85.7% accuracy, respectively. In the univariate analysis, preoperative PSA, Gleason sum, stage, margin, seminal vesicle, extra-prostatic extension (EPE), HA, HYAL1, and HA-HYAL1 were significant in predicting progression (P < 0.05). However, in the multiple logistic regression analysis, only EPE [odds ratio (OR) = 33.483; P = 0.002), HYAL1 (OR = 12.42; P = 0.009), HA-HYAL1 (OR = 18.048; P = 0.0033), and margin (OR = 26.948; P = 0.006)] were significant. Thus, in this 5-year follow-up study, HYAL1, together with EPE and margin, was found to be an independent prognostic indicator.

Adult↗

PubMed2003

Factors affecting late survival after surgical remodeling of left ventricular aneurysms.

OBJECTIVES: Surgical remodeling of the left ventricle has involved various techniques of volume reduction. This study evaluates factors that influence long-term survival results with 3 operative methods. METHODS: From 1979 to 2000, 157 patients (134 men, mean age 61 years) underwent operations for class III or IV congestive heart failure, angina, ventricular tachyarrhythmia, and sudden death after anteroseptal myocardial infarction. The preoperative ejection fraction was 28% +/- 0.9% (mean +/- standard error), and the pulmonary artery occlusive pressure was 15 +/- 0.07 mm Hg. Cardiogenic shock was present in 26 patients (16%), and an intra-aortic balloon pump was used in 48 patients (30%). The type of procedure depended on the extent of endocardial disease and was aimed at maintaining the ellipsoid shape of the left ventricle cavity. In group I patients (n = 65), radical aneurysm resection and linear closure were performed. In group II patients (n = 70), septal dyskinesis was reinforced with a patch (septoplasty). In group III patients (n = 22), ventriculotomy closure was performed with an intracavitary oval patch. RESULTS: Hospital mortality was 16% (25/157) and was similar among the groups. Actuarial survival up to 18 years was better with a preoperative ejection fraction of 26% or greater (P =.004) and a pulmonary artery occlusive pressure of 17 mm Hg or less (P =.05). Survival was worse in patients who had intra-aortic balloon pump support (P =.03). Five-year survival for all patients in group III was higher than for patients in group II (67% vs 47%, P =.04). CONCLUSIONS: Factors that improved long-term survival after left ventricular surgical remodeling were intraventricular patch repair, preoperative ejection fraction of 26% or greater, and pulmonary artery occlusive pressure of 17 mm Hg or less without the need for balloon pump assist.

Adult↗

PubMed2003

Magnetars.

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Criminology↗

PubMed2002

Bladder tumor markers for monitoring recurrence and screening comparison of hyaluronic acid-hyaluronidase and BTA-Stat tests.

BACKGROUND: One of the goals of a noninvasive test for bladder carcinoma screening would be to reduce surveillance cystoscopies among patients with a history of bladder carcinoma. In addition, an accurate bladder carcinoma marker could be used to screen a high-risk population. The authors examined the efficacy of the hyaluronic acid-hyaluronidase (HA-HAase) and BTA-Stat tests to detect and predict bladder carcinoma recurrence and tested their specificity for bladder carcinoma screening. METHODS: Over a four year period, the authors prospectively collected 225 urine specimens from 70 bladder carcinoma patients and analyzed them by the HA-HAase test. Tumors were identified during 178 visits, and in 47 specimens there was no evidence of disease (NED). Twenty six of these 70 patients were randomly selected to have the BTA-Stat test (111 surveillance visits). In a separate study, 401 former Department of Energy (DOE) workers, who are likely to be at a higher risk for bladder carcinoma, were screened by the HA-HAase and BTA-Stat urine tests. RESULTS: The HA-HAase test had an approximately 91.0% sensitivity, 70% specificity, 87% accuracy, 92% positive predictive value (PPV), and 67% negative predictive value (NPV) in the 70 bladder carcinoma patients. There were 14 false-positives; however, 6 of these had recurred in approximately 5 months. Only 4 out of 33 NED cases recurred in that time period (chi-square = 5.43; degrees of freedom [DF] = 1; P = 0.0198). Thus, a false-positive HA-HAase test carried a significant risk of recurrence within five months (relative risk [RR] = 3.5; odds ratio [OR] = 5.44). In a direct comparison, the HA-HAase and BTA-Stat had 94% and 61% sensitivity, 63% and 74% specificity, 87% and 64% accuracy, 89% and 88% PPV, and 77% and 38% NPV, respectively. While 6 of the 10 false-positive on the HA-HAase test recurred in 5 months (chi-square = 9.6; DF = 1; P = 0.004), only 1 of the 7 false-positives on the BTA-Stat test recurred in that time period (chi-square = 0.096; DF = 1; P = 0.756). The RR and OR for the HA-HAase test were 10.2 and 24, and for the BTA-Stat, 1.4 and 1.5, respectively. In the DOE worker screening study, the HA-HAase and BTA-Stat had 14% (56 out of 401) and 16.7% (67 out of 401) positive rates, respectively. Sixty three percent of the positives on the BTA-Stat test, but only 25% of the positives on the HA-HAase test, had benign urologic conditions. None of the biomarker positive cases with clinical follow-up (n = 29) had evidence of bladder carcinoma. CONCLUSIONS: The HA-HAase test is efficient and superior to the BTA-Stat for detecting and predicting bladder carcinoma recurrence. Noninvasive tests with low false positive rates could be used for bladder carcinoma screening in high-risk populations (e.g., those with occupational exposure to carcinogens or smokers).

Biomarkers, Tumor↗

PubMed2002

Digitized electrocardiograms recorded with bipolar right-infraclavicular leads compared to electrocardiograms recorded with unipolar chest V leads and bipolar lead II.

This article presents a method for the evaluation of cardiac depolarizations in a relatively short time with a minimum number of electrodes. With the negative electrode attached to the right infraclavicular region, voltage variations on the chest surface exhibit larger excursions than do the usual unipolar leads. Peak voltages of the PQRST waveforms measured on 12 normal patients by both methods were similar in polarity but were statistically significantly higher in the right infraclavicular leads. Data are presented on 21 normal patients, which show that digitized signals allow for an expanded time-scale leading to higher resolution of rate of change and onset and offset times. The digitized signals also more clearly define notches that distort the QRS complex. In 55 cardiac patients, the 12-lead unipolar electrocardiograms were visually compared to digitized electrocardiograms recorded by using the bipolar right infraclavicular leads. The authors suggest that RIC leads would be most useful in the design of a pocket-sized digitizing bipolar-lead electrocardiograph.

Aged↗