Production of finely graded forces in humans: effects of simulated weightlessness by water immersion.

We have shown before that subjects exposed to a changed gravitoinertial environment produce exaggerated manual forces. From the observed pattern of findings, we argued that initial forces were exaggerated because of abnormal vestibular activity and peak forces because of degraded proprioceptive feedback. If so, only peak but not initial forces should be affected by water immersion, an environment that influences proprioceptive feedback but not vestibular activity. The present study was undertaken to scrutinize this prediction. Twelve subjects sat in a chair once immersed in water and once on dry land, while producing pre-trained isometric forces with a joystick. In a control experiment, subjects performed a four-choice reaction-time task. During the joystick task, produced initial forces were comparable in water and on land, while peak (+24%) and end forces (+22%) were significantly higher in water, as was their reaction time (+6%). During the control task, reaction time was comparable in water and on land. Our findings corroborate the above notion that initial forces increase when the vestibular system is stimulated (gravitoinertial change, visual field motion, but not water immersion), while peak forces increase when proprioceptive feedback is degraded (probably all three scenarios) and are not corrected until response end. Our findings further confirm the absence of cognitive slowing in simple-choice reaction tasks under shallow-water immersion conditions.

Referral to treatment: improving client-treatment match through process analysis.

This paper presents an expedient procedure for assessing referral counselor knowledge of the effectiveness of various treatment programs for different client types. Among the advantages of this technique are timely results, ease of application, and usefulness for process and formative evaluation. An empirical example using data from a drug abuse referral program is included to demonstrate one application of the technique. The discussion includes additional examples where the technique would have potential utility.

Monoclonal antibodies to E92, an endothelial cell surface antigen.

Two hybridoma-derived monoclonal antibodies have been developed that react with an antigen of molecular weight 92,000 daltons on the surface of human endothelial cells. Cultured human umbilical vein endothelial cells were used for immunization, but the antigen is present on arterial, venous and capillary endothelium, as determined by biotin-avidin immunoperoxidase staining of tissue sections. With this technique, other cell types in the tissues which were examined were not reactive, except for scattered fibroblasts and histiomonocytic cells, trophoblastic cells of the placenta, and benign immature mesenchymal cells in a renal cystadenocarcinoma. By cytofluorography, the antibodies were found to be unreactive with granulocytes, T lymphocytes, B lymphocytes, and the majority of monocytes. Fibroblasts were reactive with the antibodies, but the fluorescence tracings indicated a lower density of antigen on these cells than on endothelial cells. Immunoreactivity of fibroblasts could be decreased by treatment of the cells with thrombin, trypsin, or neuraminidase, whereas these enzymes did not affect the immunoreactivity of endothelial cells. The reactive antigen (E92) does not appear to be any of several previously described endothelial cell proteins, because of its molecular weight and its absence on other cell types. The presence of E92 on trophoblastic cells of the placenta and immature mesenchymal cells, as well as fibroblasts and endothelial cells, may indicate that it is a primitive antigen of mesodermal tissue that is lost by most cell types during differentiation.