The primary motor cortex (M1) is thought to control movements of different body parts from somatotopically organized cortical territories. Electrical stimulation suggests, however, that territories controlling different fingers overlap. Such overlap might be artifactual or else might indicate that activation of M1 to produce a finger movement occurs over a more widespread cortical area than usually assumed. These possibilities were distinguished in monkeys moving different fingers. Recordings showed that single M1 neurons were active with movements of different fingers. Neuronal populations active with movements of different fingers overlapped extensively. Control of any finger movement thus appears to utilize a population of neurons distributed throughout the M1 hand area rather than a somatotopically segregated population.

Abstract. Treatment planning for high precision radiotherapy of head and neck (H&N) cancer patients requires accurate delineation of many structures and lymph node regions. Manual contouring is tedious and suffers from large inter-and intra-rater variability. To reduce manual labor, we have developed a fully automated, atlas-based method for H&N CT image segmentation that employs a novel hierarchical atlas registration approach. This registration strategy makes use of object shape information in the atlas to help improve the registration efficiency and robustness while still being able to account for large inter-subject shape differences. Validation results showed that our method provides accurate segmentation for many structures despite difficulties presented by real clinical data. Comparison of two different atlas selection strategies is also reported.

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Spleen cells obtained from mice immunized with partially purified human coagulation Factor V were fused with NS-1 mouse myeloma cells, and hybrids were selected. Culture media were screened for anti-Factor V activity, and an antibodypositive clone was obtained and passaged as an ascites tumor in mice. The ascitic fluid from the hybridoma-bearing mouse could be diluted 1:106 before losing reactivity in an anti-Factor V radioimmunoassay. When immobilized on agarose, the monoclonal antibody quantitatively removed Factor V activity from human plasma. Factor V activity could be eluted with 1.2 M NaCI at pH 6.5. Homogeneous Factor V was isolated by chromatography of barium citrate-adsorbed, polyethylene glycol 6000 precipitated plasma on the antibody column followed by chromatography on phenyl-Sepharose. The isolated Factor V exhibited a single band upon gel electrophoresis in sodium dodecyl sulfate with an apparent Mr comparable to that of bovine Factor V (330,000). Upon exposure to thrombin, the activity of Factor V increased 53-fold -when measured in Factor V-deficient plasma. This increased activity was associated with discrete proteolytic cleavages of the parent molecule.Blood coagulation Factor V as a functional entity was first described in 1947 by Owren (1). Studies by Owren (2), Ware and Seegers (3), and Murphy and Seegers (4) identified Factor V as one of the components essential for the rapid conversion of prothrombin to the blood clotting enzyme thrombin. Subsequent work indicated that Factor V functions as a cofactor, in concert with phospholipid (or platelets) and Ca2+, to promote the proteolytic activation of prothrombin by Factor Xa (5-12). In addition, several studies (2,6,8,(13)(14)(15)(16)(17) indicated that Factor V itselfis converted by thrombin to the more active form, Factor Va.Our knowledge concerning the function and molecular properties of Factor V expanded after the isolation of the bovine protein (18,19). Bovine Factor V is a high molecular weight (Mr = 330,000), single-chain precursor of Factor Va (18). Once activated by thrombin-catalyzed proteolytic cleavage (19,20), Factor Va enhances (in the presence of Ca2' and phospholipid) the activity ofFactor Xa toward prothrombin by at least 4 orders of magnitude (21,22). Studies of Factor V binding properties with regard to Ca2+ (23), phospholipid (24), and platelets (25) have indicated that Factor Va not only greatly augments rates of prothrombin activation but also can be viewed as a plateletbound receptor for Factor Xa in vivo (25,26).Although bovine Factor V has been characterized reasonably well, the properties of human Factor V have not been elucidated. In our hands, even when substantially modified, procedures that readily permit the isolation of the bovine protein do not yield electrophoretically homogeneous, undegraded human Factor V. Consequently, efforts were undertaken, using partially purified human Factor V, to generate a monoclonal hybridoma antibody for use as a tool in studying the human protein. An antibody was produce...

The efficacy of [14C]glucose molecules labeled in various positions as tracers of regional cerebral glucose utilization (rCMRGlc) was examined in rats. Arteriovenous differences of different [14C]-glucose species and 14CO2 were measured across brain to determine the relative rates of 14CO2 loss. As anticipated, 14CO2 evolution decreased in the order: [U-14C]glucose greater than [2-14C]glucose greater than [1-14C]glucose greater than [6-14C]glucose. Release of 14CO2 from [6-14C]glucose was undetectable at 5 min and barely detectable at 10 min, and release from [1-14C]glucose, which includes the pentose phosphate pathway, was only slightly greater. rCMRGlc was measured with [1-14C]-,[2-14C]-, or [6-14C]glucose in 5-min experiments. The results of [1-14C]- and [6-14C]glucose were indistinguishable; no difference due to the activity of the pentose phosphate pathway was found. Both [1-14C]- and [6-14C]-glucose gave values similar to, but on the whole slightly higher than, [2-14C]glucose. It was concluded that when knowledge of total rCMRGlc is required, [6-14C]glucose is the labeled substrate of choice. When the experimental objective is measurement of energy metabolism, use of [1-14C]glucose avoids inclusion of the nonenergy-yielding pentose phosphate pathway.