Survival of human lymphoblastoid cells after DNA damage measured by growth in microtiter wells.

Survival of cells in suspension culture after treatment with damaging agents is usually measured by extrapolation from growth curves or by growth of colonies in soft agar. We have developed a survival assay which measures the ability of small numbers of cells to initiate microscopic cultures in wells of microtiter plates without agar or feeder layers. Suitable human lymphoblastoid lines were obtained by selection of rapidly growing cultures from microtiter wells in which < 200 cells were inoculated in 0.

Technetium-99m stannous pyrophosphate myocardial scintigrams in pericardial disease.

Technetium-99m stannous pyrophosphate (99mTc-PYP) myocardial scintigrams were obtained in 35 acute pericarditis and in three chronic constrictive pericarditis patients. Thirteen of 35 acute pericarditis patients (37%) and one of three chronic constrictive pericarditis patients (33%) had abnormal scintigrams (a diffuse pattern in eight patients and a regional pattern in six patients). Of the 17 acute pericarditis patients with classic ST-segment changes of acute pericarditis, 10 (56%) had abnormal scintigrams compared to three of 17 patients (18%) without these ECG changes (P less than 0.

An evaluation of commercial radioisotope methods for the determination of folate and vitamin B12.

Five commercial kits for the determination of folate and six kits for the determination of vitamin B12 were investigated. Their performance has been compared with microbiological methods for the two vitamins and with a non-commercial radioisotopic method for B12. The results show the importance of the determination of the reference range for an individual laboratory for each method.

Inhibition of monocyte esterase activity by organophosphate insecticides.

Organophosphate insecticides, such as Vapona, Naled, and Rabon, are highly potent inhibitors of an enzyme found in human monocytes. The enzyme, a specific monocyte esterase, could be inhibited by Vapona in blood samples via airborne contamination at levels easily achieved from commercial slow-release insecticide strips. Fifty percent inhibition (I50)--as measured on the Hemalog D (Technicon Corp.

Automation of the indirect fluorescent-antibody test for toxoplasmosis.

The feasibility of automating the decision-making tasks of the medical technician in the determination of the results of the indirect fluorescent-antibody test for toxoplasmosis was investigated. Two approaches were studied: (i) macroscopic measurement of fluorescence from a large number of organisms (full-field illumination measurements), and (ii) microscopic measurements of fluorescence and morphology of individual parasites (pattern recognition). The macroscopic approach was studied utilizing an argon-ion laser in incident illumination with a Leitz Ortholux microscope and a phototube mounted so as to measure green fluorescence.