Origin of cuneate projections to the anterior and posterior lobes of the rat cerebellum

The present study was carried out to analyze the topography of projections from external cuneate nucleus to the anterior and posterior lobes of the cerebellum and to investigate whether projections to the two lobes come from different cuneocerebellar neurons or from branching axons of the same cells. We used retrograde double-labeling techniques to estimate the incidence of cuneocerebellar neurons projecting to both anterior and posterior lobes via axon collaterals. Cells sending their axons to the lobus anterior were about twice the number of those projecting to the posterior lobe. The double-labeled cells were about 1/7 of all labeled neurons and were located mainly in the more lateral half of the nucleus. Therefore, the two lobes of the cerebelum are likely to receive common information from these cells, but different information from the separate populations of cuneocerebellar neurons that project only to one lobe or the other.     

Distributed neural networks for controlling human locomotion: Lessons from normal and SCI subjects

The control of human locomotion engages various brain structures and numerous muscles. Even though the hypothetical central pattern generator (CPG) and sensory feedback can sustain the basic locomotor rhythm, the resultant motor output is highly adaptable and context-dependent. Indeed, while the temporal architecture of the locomotor output (basic EMG components) is relatively conserved across subjects and conditions, the spatial architecture (muscle activations) shows considerable non-linear changes with walking speed, level of body unloading or the direction of progression. Even so, leg kinematics are remarkably similar in all cases. Spinal cord injured (SCI) patients may learn new motor patterns with training rather than re-activate normal motor patterns, and such locomotor improvements may not transfer to untrained tasks. Redundancy in the neuromuscular system or malfunctioning of injured ‘elements’ may often result in motor equivalent compensatory solutions. Injured pathways can partially recover while uninjured pathways can augment or modify their activity. As a result, the reconstructed spatiotemporal maps of motor neuron activity in SCI patients might be quite different from those of healthy subjects but they nevertheless achieve nearly normal foot kinematics. Kinematics training may thus provide a more successful rehabilitation than training based on reconstructing normal muscle activation patterns. Taken together, recent data support the idea of plasticity and distributed networks for controlling human locomotion. A new generation of robotic devices takes advantage of this by providing the opportunity for patients to generate and correct limb movements rather than just adapting muscle activation to the fixed kinematic template imposed by a gait orthosis.     

Adverse reactions associated with autologous blood transfusion: evaluation and incidence at a large academic hospital

BACKGROUND: It is acknowledged that autologous blood is the safest for the patient to receive. However, it is generally not appreciated that transfusion reactions to autologous blood may occur, despite the fact that it is the patient's own blood. STUDY DESIGN AND METHODS: A retrospective review of all transfusion reactions reported to a hospital transfusion service from 1991 through 1996 was performed, and all reactions to autologous blood were further investigated. RESULTS: Reported adverse reactions to autologous blood composed 2.1 percent of all transfusion reactions investigated in the hospital, involving 0.16 percent (15/9,353) of all transfused preoperatively donated autologous red cell units and 0.027 percent (5/18,506) of all intraoperatively salvaged units. Further investigation revealed that 60 percent (12/20) of these adverse reactions were felt to be clinically important and directly attributable to the autologous blood transfusion. Adverse reactions included febrile nonhemolytic (5) and allergic (4) reactions, an acute hemolytic transfusion reaction secondary to a clerical error (1 intraoperatively salvaged unit), and other nonsignificant adverse reactions (2). Eight adverse reactions were determined these reactions to be unrelated to the autologous transfusion. CONCLUSION: Despite the fact that the blood given is the patient's own blood, transfusion reactions to autologous blood do occur. As it is for allogeneic transfusion, any suspected adverse reaction to autologous blood transfusion should be investigated.     

Provisional restoration options in implant dentistr

Unlike their use in conventional crown and bridge, provisional restorations during implant therapy have been underutilized. Provisional restorations should be used to evaluate aesthetic, phonetic and occlusal function prior to delivery of the final implant restorations, while preserving and/or enhancing the condition of the peri-implant and gingival tissues. Provisional restorations are useful as a communication tool between members of the treatment team which, in most cases, consists of the restorative clinician, implant surgeons, laboratory technicians, and the patient. This article describes and discusses the various options for provisionalization in implant dentistry. Clinicians should be aware of the different types of provisional restorations and the indications for their use when planning implant retained restorations.     

Protective immunity in the rat model of congenital toxoplasmosis and the potential of excreted-secreted antigens as vaccine components

Toxoplasma infection is a major cause of severe foetal pathology both in humans and in domestic animals, particularly sheep. We have previously reported the development of an experimental model to study congenital toxoplasmosis in the rat. Here we demonstrate that, as in humans, total protection against congenital toxoplasmosis can be achieved regardless of the strain of Toxoplasma gondii used to infect rats, or when initial and challenge infections were carried out with different strains. Chronic infection is associated with a highly specific immunity that involves both B-and T-cell responses beginning at day 10 postinfection. The antibody isotype analysis revealed that whereas immunoglobulin (Ig)G2b is the major elicited isotype, no IgG1 antibodies are detected. T cell proliferation was assayed using crude Toxoplasma extracts or excretory-secretory antigens (ESA). The analysis of T cell supernatants showed the specific secretion of both interleukin-2 and interferon-gamma by activated T cells. Immunization of rats before pregnancy with either crude Toxoplasma extracts or with ESA elicited a B cell response that included antibodies of the IgG1 isotype and conferred on the newborns high levels of protection. Preliminary experiments of immunization using two HPLC-purified ESA, GRA2 and GRA5, conferred, a significant protection although to a lesser extent. This experimental model represents an attractive model for the identification of future vaccine candidates against congenital toxoplasmosis.     

Anatomical evidence for multiple sources of action potentials in the afferent fibers of muscle spindles

Probable sites of origin for action potentials were identified in the distal portions of afferent fibers in neuromuscular spindles of cats and frogs (both primary and secondary afferents were examined in cats). In every case, each of the several terminal heminodes reacted with a ferric ferrocyanide cytochemical stain, indicating that these might all be initiators of action potentials.The staining results imply that in spindles the frequency response of afferent action potentials may result from competition among multiple encoders, rather than from integration of all the terminals by a single encoder.