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A sensitive and nondestructive radiometric method has been applied to the detection of metabolism of Mycobacterium lepraemurium, as a model for the study of the metabolism and substrate requirements of M. leprae. The method is based on the measurement of the 14CO2produced through the bacterial conversion of [U-14C]acetate or [U-14C]glycerol by 7 � 109bacteria suspended in 10 ml of either a simple buffer system (K-36) or a complex medium (NC-5). Metabolism of the bacilli was easily detected within 3 days after inoculation and was measured daily. NC-5 medium supported metabolism of M. lepraemuriumfor several weeks longer than the simple K-36 buffer. The radiometric technique shows promise as a rapid and efficient system for evaluating the metabolism of mycobacteria without introducing any changes in the physiologic state of the organisms, studying their metabolic pathways, determining conditions potentially favorable for multiplication of these organisms in vitro, and studying their susceptibility to inhibition by drugs.

Streptococcal and salmonella antisera inhibited carbohydrate metabolism for groups A, B, C, and D streptococci and group E salmonella, as measured by the formation of [14C]dioxide from [14C]glucose metabolism. For salmonella, the inhibition was type specific since group E salmonella were inhibited only by salmonella E antisera and not by anti-salmonella A or C1. For streptococci, quantitative differences were demonstrated, but major cross-reactivity was observed. At high concentrations, the antisera were bactericidal; at more dilute concentrations, for both salmonella and streptococci, carbohydrate metabolism was suppressed, but subculture on chocolate agar showed abundant growth. Cross-reacting antibodies could be absorbed by incubation with either antigen, e.g., streptococcal antisera versus heat-killed salmonella. The results suggest that the radiometric technique can be more sensitive than either capillary flocculation or visual detection of bacterial growth for detecting the inhibition of streptococci and salmonella by specific antibodies. The use of specific antisera may prove useful for bacterial species identification in an automated system for detection of bacterial growth.

Changes in erythron and RE cell function were examined in the marrow of the rabbit after 250-5000 R of localized irradiation by comparing the amount of 59Fe and 99mTc sulfur colloid concentrated in the irradiated tibiofibula to that in the unirradiated control. At all levels of irradiation, there was immediate and severe loss of erythron function while RE cell activity remained nearly intact. Erythron function showed prompt partial recovery to a maximum level at approximately 8 days but with doses greater than 1000 R there was a secondary decline to 20 per cent of normal during the next 8 weeks. After 15 days, RE cell function had decreased to the same level as the erythron and subsequently fell in parallel with it. After 15 months, the marrow showed a secondary recovery of both RE cell and erythron function to 50 and 66 per cent of normal. The results of these experiments suggest that radiocolloid photoscans of the marrow showing decreased or absent RE cell activity will reflect a similar degree of erythropoietic damage if the studies are obtained weeks or months following radiation therapy.

Radionuclide ventriculography is a safe and effective method for evaluating cerebrospinal fluid (CSF) dynamics. Seventy radionuclide ventriculograms from 47 patients were reviewed. The patients were primarily adults with acquired disorders, such as intracerebral neoplasm, meningeal infection, and low pressure hydrocephalus. Proper interpretation depended on an understanding of ventricular anatomy and the usual sequence of CSF flow. Important applications were assessment of CSF shunts, determination of the distribution of intrathecally administered drugs, evaluation of the functional status of hydrocephalus, and assessment of the progression of neoplastic invasion of the ventricular system.

The occurrence of vaginal bleeding during the third trimester of pregnancy presents a challenging problem in obstetrical diagnosis and management. If placenta praevia is the cause of bleeding, close medical observation is necessary and the majority of patients will be delivered by cesarean section prior to term. If placenta praevia is present, vaginal examination may cause sufficient hemorrhage that immediate delivery of the infant is necessary. A method for the accurate diagnosis of placenta praevia, without vaginal examination, when vaginal bleeding first occurs, therefore would be of great importance.Procedures to estimate the size and position of the placenta such as soft-tissue radiography, injection of radiopaque dye into the vascular bed of the placenta, or surface counting of the trace amounts of radioisotopes (usually iodinated I 131 serum albumin or sodium chromate Cr 51-tagged red blood cells) in the placental blood pool are clinically useful. Too often, however, these procedures

With the use of Tc99m-labeled albumin, the placenta was readily visualized by radioisotope photoscanning in 16 patients in the third trimester of pregnancy. Because of the precise localization of the placenta, this method shows promise of improving the diagnosis of placenta previa and management of third trimester bleeding.