Neural network analysis of clinicopathological factors in urological disease: a critical evaluation of available techniques.
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Biomedical subjects
Publications and source records attributed to R Finne.
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OBJECTIVES: To assess whether an artificial neural network (multilayer perceptron, MLP) and logistic regression (LR) could eliminate more false-positive prostate-specific antigen (PSA) results than the proportion of free PSA in a prostate cancer screening. METHODS: MLP and LR models were constructed on the basis of data on total PSA, the proportion of free PSA, digital rectal examination (DRE), and prostate volume from 656 consecutive men (aged 55 to 67 years) with total serum PSA concentrations of 4 to 10 ng/mL in the randomized population-based prostate cancer screening study in Finland. The MLP and LR models were validated using the "leave-one-out" method. RESULTS: Of the 656 men, 23% had prostate cancer and 77% had either normal prostatic histology or a benign disease. At a 95% sensitivity level, 19% of the false-positive PSA results could be eliminated by using the proportion of free PSA versus 24% with the LR model and 33% with the MLP model (P < 0.001). At 80% to 99% sensitivity levels, the accuracy of the MLP and LR models was significantly higher than that of the proportion of free PSA. At 89% to 99% sensitivities, the accuracy of the MLP was higher than that of LR (P </= 0.001). CONCLUSIONS: At clinically relevant sensitivity levels, the MLP and LR models based on total PSA, the proportion of free PSA, DRE, and prostate volume could reduce the number of unnecessary biopsies significantly better than the proportion of free PSA alone in men with total PSA levels in the range 4 to 10 ng/mL.
We report a case of inflammatory cap polyposis of the colon, a rare syndrome, affecting the rectosigmoid. It was observed in a context of mucous diarrhea. Endoscopic and radiological features consisted of elevated and umbilicated nodular lesions. Histology revealed polypoid lesions containing elongated crypts with superficial abrasions, covered by inflammatory and fibrinoid material. Etiopathogenesis of this new syndrome is unknown.
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In a first step, midazolam 0.1 mg/kg, midazolam 0.05 mg/kg and diazepam 0.15 mg/kg administered intravenously were blindly evaluated as a sedating preparation in 3 groups of each 30 patients undergoing gastroscopy. Although amnesia is better with midazolam 0.1 mg/kg, the induced sedation is protracted, which is not to be wished in ambulatory patients. On the other side, diazepam 0.15 mg/kg was locally less well tolerated. Taking into consideration the efficacy and the general and local tolerance, the dose of midazolam 0.05 mg/kg seems the best compromise. In a second step, the specific benzodiazepine antagonist flumazenil was blindly evaluated at two intravenous doses, 1 mg and 0.5 mg, against placebo for reversal of midazolam (0.1 mg/kg) induced sedation in gastroscopy patients. 1 mg of flumazenil (and to a lesser degree 0.5 mg) suppresses the sedation and amnesia induced by midazolam and normalizes attention and sensori-motor functions. However a certain degree of resedation can reappear 45-60 min. after the administration of flumazenil. Though this phenomenon did not alter the tests measuring attention and sensorimotor functions and the recovery of memory (contrary to placebo), it incites to be cautious when the drug is given to ambulatory patients.