Renal stone analysis: LITHOS, an expert system for evaluation of X-ray diffractograms of urinary calculi

An expert system for evaluation of X-ray diffraction patterns of urinary calculi is described and evaluated. The software was developed using the PERSONAL CONSULTANT expert system shell from Texas Instruments.     

The effect of immunoscintigraphy with monoclonal antibodies on assays of hormones and tumor markers. This is not the end of the matter!

The use of monoclonal antibodies in medicine for in-vivo diagnostic methods and for therapeutic purposes will increase in the future. Although monoclonal antibodies possess a high specificity, the animal origin of these antibodies remains a problem. Repeated administration of animal monoclonal antibodies (in vivo) may induce the formation of human antibodies against these monoclonal antibodies. Because animal monoclonal antibodies are also used in laboratory assays (in vitro), the presence of human antibodies against these animal monoclonal antibodies may cause spuriously elevated or depressed results of these assays. The clinician should be alert to this possibility. A case history is presented to demonstrate the problem.     

Malignant fibrous histiocytoma of the right ventricle and pulmonary artery. Apropos of a case. Review of the literature]

The authors report a case of malignant cardiac fibrohistiocytoma involving the right ventricular infundibulum and the pulmonary artery and responsible for a pseudo-thromboembolic right heart failure syndrome. Following discovery of the tumour mass on ultrasonography and catheterisation, wide excision of the pulmonary artery, pulmonary valve and the roof of the infundibulum as far as the middle part of the ventricle was performed under cardio-pulmonary by-pass. Reconstruction was performed with a valveless woven Dacron tube. The postoperative course was uncomplicated and the patient was still alive after 18 months. Histology revealed malignant fibrohistiocytoma. The authors also present a review of the literature of these rare tumours of the right-sided cavities (5 cases reported).     

Assay-specific artificial neural networks for five different PSA assays and populations with PSA 2–10 ng/ml in 4,480 men

Use of percent free PSA (%fPSA) and artificial neural networks (ANNs) can eliminate unnecessary prostate biopsies. In a total of 4,480 patients from five centers with PSA concentrations in the range of 2–10 ng/ml an IMMULITE PSA-based ANN (iANN) was compared with other PSA assay-adapted ANNs (nANNs) to investigate the impact of different PSA assays. ANN data were generated with PSA, fPSA (assays from Abbott, Beckman, DPC, Roche or Wallac), age, prostate volume, and DRE status. In 15 different ROC analyses, the area under the curve (AUC) in the PSA ranges 2–4, 2–10, and 4–10 ng/ml for the nANN was always significantly larger than the AUC for %fPSA or PSA. The nANN and logistic regression models mostly also performed better than the iANN. Therefore, for each patient population, PSA assay-specific ANNs should be used to optimize the ANN outcome in order to reduce the number of unnecessary biopsies.     

Discordant performance of assays for free and total prostate-specific antigen in relation to the early detection of prostate cancer.

OBJECTIVE: To assess the value of applying rigid threshold values in interpreting prostate specific antigen (PSA) results, by selecting and comparing five current methods for measuring free and total PSA. MATERIALS AND METHODS: Samples taken from an ongoing screening study for prostate cancer (total PSA by Tandem-E assay, 17 334 participants; biopsy criterion a PSA of 3.0 microg/L, 4 464 men) from men with a total PSA of 1.0-6.0 microg/L were measured for free and total PSA using the Access, Immulite, Elecsys and Prostatus analysis kits, in two patient groups, i.e. with prostate cancer or no evidence of disease. RESULTS: Both patient groups had equal means for total PSA but not for free PSA. In all, 360 samples from men with cancer and 96 from men with no evidence of disease were analysed. All methods applied to both groups deviated statistically significantly from the Tandem-E result for total PSA, except for the Access kit. There was a close correlation among all the methods (correlation coefficients of 0.89-0.97). There were very discordant results for the combination of the Tandem-E vs Prostatus (8% difference), representing 315 participants at a threshold of 3.0 microg/L. For free PSA (free/total PSA) the situation was worse, with extreme differences of 32% and 36% for both patient groups (Elecsys vs Access). CONCLUSIONS: Depending on the threshold value applied as an indication for biopsy, when using the total PSA alone or combined with the free/total PSA, care is needed in interpreting patient groups because of the discordance among PSA assays.     

Myocardial infarct of effort with normal coronaries. Study of in vivo platelet activation

Platelet activation may play a part in causing myocardium infarction with angiographically normal coronary arteries. We investigated this possibility by performing ergometric stress testing in a series of 9 patients (Group A) who had suffered myocardial infarction after a violent effort with angiographically documented coronary insufficiency responsible for a stable effort angina (Group B) and 11 healthy subjects (Group C). Blood samples were taken separately before exercise, at the peak of exercise, and during the recovery period. Platelet morphology, a sensitive indication of the degree of platelet activation, was studied by phase contrast microscopy after immediate fixation of the blood. The percentage of non-discoidal platelets presenting with one or several spicules was measured. At the same time, the plasma concentrations of platelet factor 4 (PF4) and beta-thromboglobulin (beta-TG) were measured. At rest, there was no difference in platelet morphology or specific platelet proteins between the 3 groups. At the peak effort, there was a significant increase of the number of morphologically modified platelets in Groups A and B but not in healthy subjects. This platelet activation could not be linked to the presence of myocardial ischaemia because it was found both in patients with a negative maximal exercise stress test (Group A). Finally, no increase of the plasma concentrations of the platelet protein was observed in any of the groups.     

Protease inhibitors and ectasia in coronary atherosclerosis

The possibility of elastase contributing to degradation of the arterial wall in atherosclerosis and to the formation of ectasia has prompted us to assay the main protease inhibitors, alpha 1-antitrypsin and alpha 2-macroglobulin, in patients with angiographic coronary disease with and without coronary ectasia. Serum concentrations of these two proteins were measured by immunonephelometry in 203 patients admitted for coronary arteriography. The results obtained were analyzed according to the presence of atheromatous lesions and their severity and to the presence or absence of ectasia. There was no correlation between the values observed and the presence or severity of coronary atherosclerosis, but the concentration of alpha 1-antitrypsin was significantly higher in patients with coronary ectasia (247.2 +/- 40.5 mg/ml) than in patients without ectasia (213.5 +/- 36.6 mg/100 ml; p less than 0.001). This study shows that coronary ectasia is associated with disturbances in the protease-antiprotease system, which may be consecutive to initial changes in elastase activity. Our results support the theory that elastase and protease inhibitors play a specific role in some atheromatous processes.