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Biomedical subjects

A M Ziada

Publications and source records attributed to A M Ziada.

8 recordsLinked to original sources
PubMed2001

Impact of different variables on the outcome of patients with clinically confined prostate carcinoma: prediction of pathologic stage and biochemical failure using an artificial neural network.

BACKGROUND: The advent of advanced computing techniques has provided the opportunity to analyze clinical data using artificial intelligence techniques. This study was designed to determine whether a neural network could be developed using preoperative prognostic indicators to predict the pathologic stage and time of biochemical failure for patients who undergo radical prostatectomy. METHODS: The preoperative information included TNM stage, prostate size, prostate specific antigen (PSA) level, biopsy results (Gleason score and percentage of positive biopsy), as well as patient age. All 309 patients underwent radical prostatectomy at the University of Colorado Health Sciences Center. The data from all patients were used to train a multilayer perceptron artificial neural network. The failure rate was defined as a rise in the PSA level > 0.2 ng/mL. The biochemical failure rate in the data base used was 14.2%. Univariate and multivariate analyses were performed to validate the results. RESULTS: The neural network statistics for the validation set showed a sensitivity and specificity of 79% and 81%, respectively, for the prediction of pathologic stage with an overall accuracy of 80% compared with an overall accuracy of 67% using the multivariate regression analysis. The sensitivity and specificity for the prediction of failure were 67% and 85%, respectively, demonstrating a high confidence in predicting failure. The overall accuracy rates for the artificial neural network and the multivariate analysis were similar. CONCLUSIONS: Neural networks can offer a convenient vehicle for clinicians to assess the preoperative risk of disease progression for patients who are about to undergo radical prostatectomy. Continued investigation of this approach with larger data sets seems warranted.

Adult↗
PubMed2001

Changes in serum concentration of antioxidants following treadmill exercise testing in patients with suspected ischaemic heart disease.

Twenty-four subjects with suspected ischaemic heart disease underwent a treadmill exercise stress test (TEST). Nine individuals developed ischaemia as defined by standard criteria. Total plasma antioxidant status (TPAS), and serum concentrations of vitamin E were measured pre-TEST, and 0, 1, 2, 4, 8 and 24 h following the treadmill test. Mean serum vitamin E concentrations fell by 33% in the group as a whole (from 9.53 +/- 0.92 mg/L pre-TEST to 6.39 +/- 1.06 mg/L immediately post stress test, P < 0.02) and rose to baseline over the subsequent 24 h. The levels of serum vitamin E fell by 34% in the group of patients who had a positive TEST, and 32% in those who did not develop ischaemia during the TEST. Serum cholesterol concentrations also fell significantly during the TEST. In the total group serum cholesterol fell by 6.5% (P = 0.0052), and in the subgroup who were positive for ischaemia the fall in serum cholesterol was 10.3% (P = 0.004). The reduction in serum cholesterol was 4.1% in the subgroup who did not develop ischaemia (P > 0.05). Mean total plasma antioxidant status showed no significant temporal change for the group as a whole, although there was a nonsignificant decrease immediately post-TEST in the ischaemic group and a slight rise at 8 h in the group negative for ischaemia.

Adult↗
PubMed1999

Advanced prostate cancer.

Both the definition and therapy of advanced prostate cancer is challenging. The advanced prostate cancer session at "The 8th International Prostate Cancer Update" had discussions which tried to answer the questions of management of these patients who either present with advanced disease or fail any form of therapy for clinically confined prostate cancer. This article provides an overview of therapeutic options: monotherapy and minimal androgen blockade options versus maximal androgen blockade, adjuvant therapy, intermittent therapy and timing of therapy as well as chemotherapy when all these measures fail. The impact of these therapies on progression as well as quality of life is reviewed.

Journal Article↗
PubMed1998

Securing urethral catheters in patients undergoing urethrovesical anastomosis.

OBJECTIVE: Securing urethral catheters for the optimal healing of and prevention of extravasation at the urethrovesical anastomosis. METHOD: This article describes the technique that we use to help secure Foley catheters or replace them if necessary. CONCLUSION: In the rare patients where disruption of the anastomosis or loss of the catheter prematurely takes place, the nylon suture can be used to replace the catheter without jeopardizing the anastomotic line.

Anastomosis, Surgical↗
PubMed1984

The effect of long-term vasodilatation on capillary growth and performance in rabbit heart and skeletal muscle.

The long-term effect of adenosine and of a new xanthine derivative, 1-(5-oxohexyl)-3-methyl-7-propylxanthine (HWA 285) on capillary density was studied in rabbits. Doses of both agents were established in acute experiments such that they would produce a prolonged increase in coronary and skeletal muscle blood flows without significantly affecting blood pressure or cardiac output. These doses were then chronically administered (3 to 5 weeks) by continuous intravenous infusion from portable infusion pumps carried by the rabbits. Control animals were infused with saline. Long-term administration of adenosine and HWA 285 was well tolerated by the animals. In the acute experiments, adenosine (42 mumol.h-1 iv) reduced the heart rate and produced an increase in coronary blood flow (studied using 15 micrometers radioactive microspheres) and conductance of 38% and 65% respectively, with increases in skeletal muscle of 65% and 92%. Blood pressure, cardiac output and cardiac minute work were not affected. HWA 285 (57 mumol.h-1) slightly but significantly increased blood pressure, but did not affect heart rate, cardiac output or minute work. Coronary and skeletal muscle blood flow were increased by 41% and 72%, with conductance increases of 33% and 62% respectively. The number of all capillaries present was studied in the heart and skeletal muscle using histochemical staining for alkaline phosphatase. Myocardial capillary density (capillaries per mm2, means +/- SE) was 3092 +/- 97 in the adenosine infused group and 2870 +/- 153 in the HWA 285 infused group compared with 2426 +/- 93 in the controls, ie an increase of 27% (p less than 0.001) and 18% (p less than 0.02) respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine↗
PubMedDate not supplied

Changes in serum concentrations of markers of myocardial injury following treadmill exercise testing in patients with suspected ischaemic heart disease.

BACKGROUND: The treadmill exercise test (TEST) is frequently used in patients with suspected ischaemic heart disease to establish a diagnosis and estimate future risk. However, its predictive value is poor. We aimed to investigate whether measurement of biochemical markers of myocardial injury could improve the diagnostic value of the procedure. MATERIAL AND METHODS: Twenty-four subjects with suspected acute coronary syndrome underwent a treadmill exercise stress test. Of these 13 had had a previous myocardial infarction and two had a past history of coronary artery bypass grafting. Nine subjects were found to be positive for coronary ischaemia during the treadmill test. Serum cardiac markers (total creatine kinase [CK], CK-MB, Troponin I and Troponin T) were measured pre-TEST, and 0, 1, 2, 4, 8 and 24 hours following the treadmill test. RESULTS: Total CK remained within the reference range for all subjects and showed no significant rise. However, mean serum concentrations of CK-MB were significantly higher than pre-test values at 2 hours (p < 0.03) following treadmill exercise testing in subjects who had a positive exercise stress test, but not in those with a negative test. In the subjects with a positive stress test, CK-MB levels returned to pre-Test value by 24 hours. Levels of neither serum troponin I, nor troponin T altered significantly at any point. CONCLUSION: The measurement of CK-MB, but not cardiac troponins may add to the diagnostic utility of the TEST.

Angina Pectoris↗
PubMedDate not supplied

Angiogenesis in the heart and skeletal muscle.

Capillary growth was induced in rabbits's hearts by long-term transvenous bradycardial pacing for 24h/day without any hypertrophy. Capillary density was up to 70% higher than in hearts of comparable size from control rabbits when pacing was applied for at least 14 days. When applied for a month to hearts made hypertrophic by aortic valve lesion, capillary density was higher by 62 +/- 17% than in hearts of control animals of similar body weight. Capillary growth was also induced in skeletal muscles by long-term electrical stimulation (8h/d) at 10 Hz after only 4 days, and after 7 days by stimulation with intermittent tetanic contractions. As the former type increased blood flow more than the latter we tried to find out whether mechanical factors connected with increased flow can stimulate capillary growth. Long-term administration of adenosine and xanthine derivative (HWA 285, Hoechst, Werk Albert, Wiesbaden) increased blood flow in the heart and skeletal muscles and induced capillary growth in both. Prazosin increased flow in muscles but not in the heart and induced capillary growth in muscles only. Limitation of flow to contracting muscles prevented growth of capillaries. Extracts of stimulated muscles had no angiogenic factor while extracts of paced hearts did. Thus capillary growth in skeletal muscle may be due to mechanical factors connected with increased blood flow while the presence of AF may be more important in the heart.

Angiogenesis Inducing Agents↗