Biomedical subjects

J G Montalvo

Publications and source records attributed to J G Montalvo.

12 recordsLinked to original sources

PubMed1987

The reliability of cytopathologists' classifications of bronchial epithelial atypias from Kodachrome slides.

The accuracy of computerized cell image analysis techniques for classification of atypical cells is determined by comparing computer-generated classifications with those made by cytopathologists. This measure of accuracy depends not only on the reliability of the computer classifications but also on the reliability of the cytopathologists' classifications. This study reports on the observed reliability of cytopathologists' classifications of squamous epithelial atypias in sputum across cytopathologists and two different classification times. Results indicated the percentage agreement among cytopathologists and computerized cell image analysis techniques. It is recommended that, in the future, all analyses of computerized classification schemes by interpreted in light of the consistency of the cytopathologists' classifications.

Diagnosis, Computer-Assisted↗

PubMed1982

Analysis of phosphate in serum with the phosphate redox electrode system.

A phosphate redox electrode system (PRES) was designed, constructed, and evaluated for analysis of inorganic phosphate in serum. This system is based on the observed phosphate ion potential of a chemically treated iron wire in a turbulent flow-through cell at constant oxygen tension. We analyzed 110 clinical samples by this technique and with the Technicon SMAC. Of the specimens analyzed, 32% contained abnormal phosphate concentrations. Each was assayed two to four times with the PRES and once with the SMAC. The PRES assay rate was 60 samples/h. Mean phosphorus concentrations (and SEM) were: PRES, range of values for replicate data sets, 30.5-31.0 (0.5-1.1) mg/L; SMAC, 30.8 (1.0) mg/L. Results for the PRES (y) correlated well with those by the SMAC: r = 0.968 to 0.980, estimated slope = 0.99 to 1.03, and estimated intercept = -1.1 to 0.1 mg/L. Differences in results by the two methods were not statistically significant.

Electrochemistry↗

PubMed1979

Total elemental content passive personal monitors.

The development of specific passive personal monitors for each volatile form of an element should ultimately lead to a common monitor which can detect any or all forms of that element. Such a device is presented here as a total elemental content passive personal monitor and depends upon diffusion to bring gaseous pollutants into its collecting matrices. The goal of this paper is to show how to compute and limit the ambient concentration error attributed to molecular diffusion approximations for such monitors. The error depends upon the value for the weighted diffusion coefficient used to convert the mass of element collected to ambient concentration. A computed average diffusion coefficient tends to be nonideal, because the relative concentrations of the volatile forms of an element entering the monitor are variable during the work day. Since it is not possible to calculate an exact diffusion coefficient, a finite error will exist between monitor and ambient concentration values. It is shown that total organic chlorine at a vinyl chloride plant can be estimated by use of an average diffusion coefficient without imparting significant error.

Air↗

PubMed1978

Continuous monitoring of urea levels during hemodialysis.

An ammonium ion-specific electrode system is evaluated for analysis of blood urea nitrogen from serum, plasma ultrafiltrate, or hemodialyzer dialysate fluid. The electrode shows a high sensitivity over clinically useful concentration ranges. Free serum ammonia, volatile amines, or urea ammonia after hydrolysis can be measured. In a double blind study excellent correlation was found for 187 blood urea nitrogen samples measured with the electrode with standard auto-analyzer techniques. Continuous monitoring of urea in dialysate fluid is described. Urea clearances were measured from dialysate effluent from an in vitro dialysis using conventional equipment. These values show excellent correlation to those from stnadard analysis methods. A continuous urea sensor for on-line hemodialysis application which can provide quantification of therapy is described.

Ammonia↗

PubMed1978

Continuous monitoring of urea and inorganic phosphate during hemodialysis: II. Clinical trials.

Ion-selective eletrodes have been used to monitor urea and inorganic phosphate removal during dialysis. The dialysate outlow concentrations from a single pass beside controller were used to compute instantaneous serum concentrations. The urea data are in agreement with a single pool reservoir model; the inorganic phosphate removal was not log-linear, indicating rate limiting intracompartmental transfer. The procedure can be applied to the computation of urea generation rates and thus provide information on the protein catabolism rates of the patient; in addition, the monitor provides continuous checks on the dialyzer performance.

Autoanalysis↗

PubMed1973