Development and fine structure of murine Purkinje cells in dissociated cerebellar cultures: dendritic differentiation, synaptic maturation, and formation of cell-class specific features

Cerebellar Purkinje cells (PC) display a highly distinctive form of polarity. We have cultured murine PCs from dissociated E16 cerebellar anlagen for 1 week to investigate the early stages of neuronal compartmentalization and synaptic interactions, features which are important for the establishment of neuronal polarity. To unequivocally identify the PCs we utilized light and electron microscopic immunocytochemistry with an anti-serum to the cell class-specific marker L7/pcp2 gene product. The PCs typically show a single, long axon, numerous short appendages classified as filopodia and protospines, and a small number of protodendrites. The nucleus is positioned asymmetrically in both the horizontal and vertical axes of the soma. The Golgi apparatus, coated and uncoated vesicles, and mitochondria are prominent ultrastructural features, while the endoplasmic reticulum is highly fragmented. The cell body receives rudimentary synapses on its smooth surfaces and appendages and no consistent morphological differences were detected between these elementary contacts. The axon is clearly identifiable; it emanates from either the cell body or a protodendrite, bifurcates at predominantly right angles, forms beaded collaterals, and terminates with relatively large growth cones. The varicosities of the PC axon contain pleomorphic synaptic vesicles and form rudimentary synapses primarily with the dendritic shafts of immunonegative neurons. The protodendrites are short, quickly tapering and sparsely branched; they emit numerous filopodia and immature spines and terminate with small growth cones. Rudimentary synapses are received on the proximal dendritic shafts and filopodia, and more mature synapses occur frequently on protospines. With few exceptions, PCs lie atop an astrocytic bed layer and glial processes are apposed to the various aspects of the PC body left free by the afferent axons. By contrast, PC processes are largely free of glial sheaths. We conclude that the "stellate stage" of PC development in situ is replicated rather faithfully in culture and that PCs have established polarity and have begun to form intercellular contacts by 1 week in vitro. Moreover, the PCs are already morphologically distinct from other cell types in the 1 week cultures, although they have yet to develop the differentiated features that distinguish mature PCs.     

Trick or treat?: uneven understanding of mind and emotion and executive dysfunction in "hard-to-manage" preschoolers

It is widely recognised that impaired social relations are characteristic of school-aged children with behavioural disorders, and predict a poor long-term outcome (Parker & Asher, 1987). However, little is known about the early antecedents of social impairment in behaviourally disturbed children. The aim of the present study was to explore three areas of potential dysfunction in younger children: theory of mind, emotion understanding, and executive function. Forty preschoolers, rated by their parents on the Strengths and Difficulties Questionnaire (Goodman, 1994) as "hard to manage" (H2M) were compared with a control group on a set of: (1) theory of mind tasks (including an emotion prediction task involving either a nice or a nasty surprise); (2) emotion understanding stories (that required affective perspective-taking skills as well as situational understanding); and (3) simple executive function tasks (adapted for preschoolers, and tapping inhibitory control, attentional set-shifting, and working memory). Small but significant group differences were found in all three cognitive domains. In particular, hard-to-manage preschoolers showed poor understanding of emotion and executive control, poor prediction or recall of a false belief, and better understanding of the belief-dependency of emotion in the context of a trick than a treat. Moreover, executive function was associated with performance on the theory of mind tasks for the hard-to-manage group alone, suggesting both direct and indirect links between executive dysfunction and disruptive behaviour.     

RasGRP, a Ras guanyl nucleotide- releasing protein with calcium- and diacylglycerol-binding motifs

RasGRP, a guanyl nucleotide-releasing protein for the small guanosine triphosphatase Ras, was characterized. Besides the catalytic domain, RasGRP has an atypical pair of "EF hands" that bind calcium and a diacylglycerol (DAG)-binding domain. RasGRP activated Ras and caused transformation in fibroblasts. A DAG analog caused sustained activation of Ras-Erk signaling and changes in cell morphology. Signaling was associated with partitioning of RasGRP protein into the membrane fraction. Sustained ligand-induced signaling and membrane partitioning were absent when the DAG-binding domain was deleted. RasGRP is expressed in the nervous system, where it may couple changes in DAG and possibly calcium concentrations to Ras activation.     

Hepatectomy with hypothermic perfusion of the liver

Whereas most liver resections can be performed within 60 min, the period of vascular clamping and resulting ischemia may prove too short to allow complex major liver resections (MLR) especially on diseased livers. To overcome this problem, cooling of the liver with 4 degrees C preservations solution routinely used in liver transplantation may be used in three different approaches to MLR: I "In situ": the liver remains in the abdomen and integrity of afferent and efferent vessels is conserved. II "Ex situ-in vivo": the liver exteriorized from the abdomen by transecting all hepatic veins, remains connected to the porta hepatis. III "Ex vivo": the liver being removed from the abdomen, the MLR is performed extracorporeally. Of 15 MLR reported here, 11 were performed "in situ" and 4 "ex situ-in vivo"/Nowadays, the liver surgeon's "toolbox" must contain hypothermic liver perfusion. In carefully selected cases, these techniques allow MLR on diseases livers or mandating complex vascular procedures.     

Inviscid melt-spun high-temperature alumina-magnesia fibres

Al₂O₃-MgO (AM) fibres containing 98.16 wt% Al₂O₃ and 1.84 wt% MgO, were produced via inviscid melt spinning. By using scanning electron microscopy it was found that the as-spun AM fibres were hollow and their surfaces were very rough. The X-ray diffraction pattern of the as-spun AM fibre showed -Al₂O₃ as a major phase and -Al₂O₃ as a minor phase. The DTA curve of the as-spun AM fibre showed a single endothermic peak representing the phase transformation of -Al₂O₃ to -Al₂O₃. This phase transformation was readily confirmed by analysing the X-ray diffraction pattern of heat-treated AM fibres.     

Why talk about mental states? The significance of children's conversations with friends, siblings, and mothers

Natural language data from 38 47-month-olds recorded at home in unstructured observations were analyzed and comparisons made of characteristics of mental state term use in child-friend, child-sibling, and child-mother dyads. Significantly more references to mental states were made by the children in conversations with siblings and friends than with mothers. Frequent use of mental state terms by both partners was related to cooperative interaction in both child-friend and child-sibling dyads and several associations were found with measures of language fluency, gender, and maternal education, although these varied across the 2 dyads. Children's use of mental state terms in conversations with siblings and friends was correlated with their performance on two false belief measures. Results highlight the importance of extending investigations into the social implications of the development of children's "theories of mind."     

Marine Geospatial Ecology Tools: An integrated framework for ecological geoprocessing with ArcGIS,Python, R,MATLAB, and C++

With the arrival of GPS, satellite remote sensing, and personal computers, the last two decades have witnessed rapid advances in the field of spatially-explicit marine ecological modeling. But with this innovation has come complexity. To keep up, ecologists must master multiple specialized software packages, such as ArcGIS for display and manipulation of geospatial data, R for statistical analysis, and MATLAB for matrix processing. This requires a costly investment of time and energy learning computer programming, a high hurdle for many ecologists. To provide easier access to advanced analytic methods, we developed Marine Geospatial Ecology Tools (MGET), an extensible collection of powerful, easy-to-use, open-source geoprocessing tools that ecologists can invoke from ArcGIS without resorting to computer programming. Internally, MGET integrates Python, R, MATLAB, and C++, bringing the power of these specialized platforms to tool developers without requiring developers to orchestrate the interoperability between them.In this paper, we describe MGET’s software architecture and the tools in the collection. Next, we present an example application: a habitat model for Atlantic spotted dolphin (Stenella frontalis) that predicts dolphin presence using a statistical model fitted with oceanographic predictor variables. We conclude by discussing the lessons we learned engineering a highly integrated tool framework.     

The continuing dilemma concerning medical versus surgical management of patients with acute type B dissections

In the free-running circadian rhythms of 14 human subjects (4 females, 10 males) who lived singly in an isolation unit without temporal clues, locomotor activity was recorded by means of contact plates installed below the carpet in the main room. During sleep, movements in bed were picked up by spring contacts attached to the mattress. In all subjects, the hourly means of locomotion during wakefulness (alpha) were negatively correlated with the duration of alpha to such an extent that the total amount of locomotion per cycle remained constant when alpha varied from 14 to 23 hr. The hourly values of movements in bed were independent of the duration of sleep (rho), so that the total number of movements was almost proportional to rho. The "homeostatic control" of locomotion during wake time is considered as a means to conserve energy when the duration of wakefulness increases.     

Nonmitogenic anti-CD3F(ab')2 fragments inhibit lethal murine graft-versus-host disease induced across the major histocompatibility barrier

We have investigated the in vivo administration of nonmitogenic anti-CD3F(ab')2 fragments for the prevention of lethal graft-vs-host disease (GVHD) in irradiated recipients of fully allogeneic bone marrow cells plus splenocyte (BMS) inocula. Recipients of anti-CD3F(ab')2 fragments administered for 1 mo post-bone marrow transplantation (BMT) had 100% survival without clinical or histopathological evidence of GVHD. Controls given saline injections succumbed by 39 days post-BMT. Similar results were obtained in groups of recipient mice given BMS in which T cells were depleted by in vitro anti-Thy-1.2 plus C' treatment. Further studies were undertaken to define mechanistic differences in the two approaches. Using Ly-5 congenic sources of donor bone marrow and spleen, we determined that anti-CD3F(ab')2 fragments induced TCR modulation and T cell depletion. Mature splenic-derived CD4+ cells were depleted to a greater extent than CD8+ cells. Early post-BMT, recipients receiving injections with control saline had the highest number of CD4+ and CD8+ cells (which may cause GVHD) followed by recipients of anti-CD3F(ab')2 fragments, with the fewest CD8+ cells observed in the anti-Thy-1.2 + C' treated group. CD3+CD4-CD8- cells (which may suppress GVHD generation) were present in higher numbers early post-BMT in recipients given anti-CD3F(ab')2 fragments as compared to recipients given anti-Thy-1.2 + C'-treated BMS. In long term survivors, a mononuclear T cell containing infiltrate without evidence of destruction was observed in sites of GVHD (lung and liver), consistent with a "Quilty" effect, which was not observed in either of the other two groups. Although survivors were tolerant of donor skin grafts and rejected third party grafts, recipients given anti-CD3F(ab')2 fragments but not anti-Thy-1.2 + C'-treated BMS had vigorous anti-host proliferative responses. These results demonstrate that although in vitro anti-Thy-1.2 + C' treatment of BMS (which is highly depletionary) and in vivo administration of anti-CD3F(ab')2 fragments (which is modulatory and less depletionary) are both effective strategies for GVHD, the cellular events involved in achieving GVHD prevention are indeed different.