Detection of diffuse glomerular lesions in rats: II. Comparison of indium-111 cationic small macromolecules with technetium-99m DTPA.

Dextrans with average molecular weights of 5,000, 10,000, and 17,500 and inulin were rendered cationic by amination with 2-bromoethylamine hydrobromide. After limited coupling with DTPA cyclic dianhydride, they were labeled with 111In. A good correlation was found between their early renal uptake quantitated by camera-computer techniques and their renal clearance from multiple plasma samples in rats with glomerular damage induced by puromycin aminonucleoside and controls. However, there was poor correlation between the early renal uptake of these agents and the clearance of simultaneously injected [99mTc]DTPA. The 2-hr organ distribution and urinary excretion of these agents were compared with the corresponding values of DTPA. The differences in clearance between rats with glomerular damage and controls were greater with aminated dextran (mol wt 5,000) than with DTPA, confirming previous work with infusions of nonradioactive charged dextrans and neutral inulin. The cationic dextrans appear to reflect the presence or absence of the normal anionic charge of the glomerular membrane as well as changes in filtration rate. Aminated inulin did not differentiate between controls and rats with glomerular disease any better than DTPA, probably because the number of amino groups conjugated was insufficient to produce the charge effect.

Locus of reaction time change in schizophrenics and normal subjects.

Simple reaction time (RT) obtained from trials presented in isotemporal series (preparatory intervals of the same duration) were partitioned into premyographic and myographic time components for 20 schizophrenic and 20 normal subjects according to a previously developed procedure. This procedure allowed for an examination of the relative contributions made by these RT components to: a) overall mean reaction time; and b) the crossover pattern of responding as first observed by David Shakow. In addition, a within-subject comparison of the traditional press-release motor task and an alternative press-only motor task was made. Differential predictions were made as to the effect of the task manipulation from: a) the loss of major set; and b) the reactive inhibition interpretational positions. It was found that the schizophrenics' crossover pattern of responding was specific to the press-release task. Furthermore, it was apparent that both premyographic and myographic components of the RT interval contributed to: a) their overall longer mean RTs, as well as b) their increased magnitude of crossover. The results were seen as supporting the view that inhibitory processes triggered by the increased levels of arousal during the isotemporal series are responsible for the schizophrenics' crossover pattern of responding on the press-release task. It was noted that the loss of major set explanation need not be seen as incompatible with a reactive inhibition explanation of the crossover effect.

Differences in muscle activity before, during, and after responding in a simple reaction time task: schizophrenics vs. normals.

Schizophrenics and normals were presented with a series of simple reaction time (RT) trials. Electromyographic techniques were used to partition RT into peripheral and central components. It was observed that contrary to the previously held assumption of "neuromuscular sameness," schizophrenics displayed a qualitatively different pattern of muscle activity in their motor responding. Differences of the observed sort could account, in part, for differences previously thought to be due solely to central dysfunction.

A re-examination of the relationship between locus of control and voluntary heart rate change.

The present study was an attempt to resolve some of the inconsistencies and discrepancies in previous studies examining the relationship between Rotter's locus control construct and voluntary heart rate (HR) change. Twelve internals and 12 externals received two sessions (one week apart) of bidirectional HR control trials with or without feedback. Internals, relative to externals, were better able to increase their HR and showed more improved performance with feedback. Neither group was able to lower their HR significantly during any decrease phase of either session. It was suggested that (a) HR slowing may involve different psychophysiological processes than HR speeding, and/or (b) HR slowing may have been perceived to be a task involving chance rather than skill, in which case no difference between groups would be expected in light of the locus of control literature.

On the cogency of the ppi-pi effect.

The present paper discusses briefly the incompatibility between the propositions that (1) the preceding preparatory interval moderates the reaction time of the subsequent trial, and (2) and inability to maintain task-relevant vigilance is the cause of the schizophrenic's peculiar response patterns in reaction time experiments.

Induction of tumors by a guinea pig herpesvirus-transformed hamster cell line.

Syrian hamster embryo cells that had been transformed in vitro by guinea pig herpes-like virus (GPHLV) were found to be oncogenic when inoculated into hamster sc or ip. Of 71 animals inoculated, 30 showed tumors at the site of inoculation. Tumors appeared 4-23 weeks after inoculation of the transformed cells at passage 37 or higher. Inbred and randombred hamsters of all ages were susceptible. Upon microscopic examination the tumors were characterized as fibrosarcomas. The cultured hamster tumor cells were easily transplanted into hamsters, but produced no evidence of tumors when inoculated into guinea pigs. Infectious GPHLV was not isolated from the tumor cells, but GPHLV-specific surface antigens were detected in tumor cells by immunofluorescence of GPHLV antiserum produced in rabbits. Sera from tumor-bearing hamsters did not contain GPHLV-neutralizing antibodies, but sera from 4 of 23 hamsters bearing primary tumors and 12 of 41 bearing transplanted tumors produced nuclear fluorescence in cells infected with GPHLV, thus establishing the relationship between the guinea pig herpesvirus and the hamster tumors.

Mediastinal histoplasmosis with abscess.

A mediastinal mass of clinically undetermined nature was found at autopsy to be an enormous abcess due to secondary infection in granulamatous caseating mediastinal nodes caused by Hitosplasma capsulatum. Other complications of mediastinal histoplasmosis are briefly reviewed.