The electromotor system of the electric eel investigated with horseradish peroxidase as a retrograde tracer

The electromotor system of the electric eel, Electrophorus electricus, was studied by injection of horseradish peroxidase as a retrograde tracer. The electromotor neurons, which innervate the electrocytes, comprise a midline nucleus, largely dorsal to the spinal canal. Spinal motoneurons lie ventrolaterally. The electromotor and skeletal motor neuron populations correspond to the acetylcholinesterase-negative and -positive cells previously described. The medullary relay neurons were labeled following HRP injection into the spinal cord at a level where electromotor neurons occurred, but not after injection into the cord in the abdominal region rostral to these cells. Other medullary neurons, presumably bulbospinal motor fibers, were labeled after both levels of spinal cord injection. The results suggest that these axosomatic synapses, which are electrically transmitting but morphologically mixed, take up retrograde tracers in a manner similar to chemical synapses and that tracer uptake is at least largely at terminal regions.     

Expert systems and the clinical laboratory information system

Many of the tasks of the clinical laboratory involve the application of knowledge and experience to patient-specific problems. Expert systems that have ready access to patient data and expert knowledge have the potential to support many laboratory processes, especially those that involve the repetitive and reasonably predictable application of knowledge. Quality assurance and utilization improvement efforts requiring constant vigilance and surveillance of an array of laboratory processes especially may benefit. Expert system technologies, trends of their use in the clinical laboratory, their role in the total testing process, and their potential for influencing physician use of the laboratory through timely feedback are discussed.     

Psychological change during residence in a rehabilitation centre for female drug misusers. Part II. Children of drug misusers

This study examined psychological changes in children of female drug misusers who were living with their mothers in a residential rehabilitation centre. The results suggest that the childrens' behaviour and cognitive skills were not adversely affected, and that there were many benefits for drug addicted mothers retaining custody of their children whilst undergoing a rehabilitation programme. The implications of the possible detrimental effects of a mother failing to complete her rehabilitation programme on her children are discussed.     

Growth of axons into developing muscles of the chick forelimb is preceded by cells that stain with Schwann cell antibodies

A study has been made of the development of limb and muscle nerves in relation to the first appearance of Schwann cells in the flexor digitorum profundus (fdp) and flexor carpi ulnaris (fcu) muscles of the avian forelimb. Schwann cells were identified by immunofluorescent techniques with antibodies to the glycoprotein HNK-1. Myotubes and nerves were identified by using antibodies to myosin and to neurofilament, respectively. At stage 24/25 the brachialis longus inferior (Bli n) and superior (Bls n) nerve trunks within proximal regions of the forelimb were surrounded by Schwann cells. These cells extended in a column for a distance of approximately 100 microns beyond the growing ends of nerves. At stage 26 both interosseus nerve (in n) and the medial-ulnar nerve (m-u n) had formed from the Bli n; each of these branches was surrounded by Schwann cells, which again extended approximately 100 microns beyond the growing ends of the nerves. By stage 26/27 the fdp and fcu muscles were clearly delineated by groups of myotubes. No nerves were detected within these groups; however, Schwann cells were observed between the myotubes. At stage 27 axons had left the in n and m-u n and grown into the fdp and fcu muscles, respectively. These axons were surrounded by Schwann cells. The present observations show that Schwann cells are located ahead of the main limb and muscle nerves as they grow into the fdp and fcu muscles of the limb. It is possible that these Schwann cells play a role in guiding nerves to their correct muscles in the developing chick forelimb.     

The influence of wear paths produced by hip replacement patients during normal walking on wear rates

Variation in wear paths is known to greatly affect wear rates in vitro, with multidirectional paths producing much greater wear than unidirectional paths. This study investigated the relationship between multidirectional motion at the hip joint, as measured by aspect ratio, sliding distance, and wear rate for 164 hip replacements. Kinematic input from three‐dimensional gait analysis was used to determine the wear paths. Activity cycles were determined for a subgroup of 100 patients using a pedometer study, and the relationship between annual sliding distance and wear rate was analyzed. Poor correlations were found between both aspect ratio and sliding distance and wear rate for the larger group and between annual sliding distance and wear rate for the subgroup. However, patients who experienced a wear rate <0.08 mm/year showed a strong positive correlation between the combination of sliding distance, activity levels, and aspect ratio and wear rate (adjusted r² = 55.4%). This group may represent those patients who experience conditions that most closely match those that prevail in simulator and laboratory tests. Although the shape of wear paths, their sliding distance, and the number of articulation cycles at the hip joint affect wear rates in simulator studies, this relationship was not seen in this clinical study. Other factors such as lubrication, loading conditions and roughness of the femoral head may influence the wear rate. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1210–1217, 2008     

Myocardial imaging with Cc-99m pyrophosphate in patients on adriamycin treatment for neoplasia.

Technetium-99m pyrophosphate was utilized for myocardial imaging in 15 patients on adriamycin treatment for neoplasia. We have noted abnormal accumulation of the pyrophosphate in several patients, particularly in those in whom the so-called poor-risk factors were operative, namely prior radiation, cyclophosphamide therapy, and ischemic heart disease.     

Stimulation of wound healing by positively charged dextran beads depends upon clustering of beads and cells in close proximity to the wound.

We have previously shown that positively charged dextran (DEAE A25) increases wound breaking strength in linear incisions in rats and nonhuman primates at days 10-14 postwounding. In this article, we examined the cellular responses to different types of charged dextran beads (DEAE A50 and Cytodex-1) in culture studies and in rat incisional wounds. We show that Cytodex 1 and DEAE A50 beads also increased wound breaking strength in a rat linear incisional model. However, the increase was approximately 30-40% less than that observed in wounds treated with DEAE A25 beads. The main distinction between the three types of beads was the presence of bead clusters observed in tissue sections. Wounds treated with DEAE A25 beads formed distinct clusters while both Cytodex 1 and DEAE A50 beads clustered to a lesser extent or failed to cluster at all. We propose that the different types of charged dextran beads improve healing by promoting cell adhesion and encouraging proliferation in close proximity to the wound. We also hypothesize that the 30-40% improvement in wound breaking strength seen with DEAE A25 beads compared to other types of charged dextran beads (DEAE A50 and Cytodex-1) originates from the unique characteristic of DEAE A25 beads in forming cell-bead aggregates adjacent to the wounded area. This clustering, in turn, affects the distribution of cells infiltrating the wounded area (such as macrophages) during the healing process and, as a consequence, alters the distribution of matrix molecules and growth factors secreted by these cells.     

Central nervous system serotonin and personality as variables contributing to excessive alcohol consumption in non-human primates.

Non-human primates will readily consume an alcohol solution for its reinforcing effects when such a solution is palatable, with some subjects consuming alcohol to excess. In this review, we discuss variables that contribute to high alcohol consumption and the behaviours that are correlated with it in a non-human primate model. Developmental and behavioural correlates of central nervous system (CNS) serotonergic activity, as measured by concentrations of the serotonin metabolite 5-hydroxyindol-3-ylacetic acid (5-HIAA) in the cerebrospinal fluid (CSF), were used to investigate neurogenetic influences on alcohol consumption, as well as personality traits that characterize excessive alcohol intake. Inter-individual differences in CSF 5-HIAA concentrations were shown to have trait-like qualities, and with stable inter-individual differences across time and settings. Research has shown numerous similarities between human and non-human primates with respect to Type I- and II-like alcohol abuse and their associated behaviours. In the present series of studies, features characteristic of Type I alcohol misuse, such as high levels of anxiety, hypothalamic-pituitary-adrenal output, and situational stress predicted high alcohol intake. Primates with low CSF 5-HIAA concentrations also exhibited behaviours characteristic of Type II alcohol abuse. Principal among the traits that these subjects exhibited were deficits in impulse control. For example, subjects with low CSF 5-HIAA concentrations engaged in spontaneous behaviours that bring reinforcement but placed them at risk, such as entering food baited traps, jumping from dangerous heights to get from one tree to another, and consuming large amounts of alcohol. They can be characterized by other Type II-like deficits, such as impaired social competence, social alienation, and unrestrained, violent aggression. Non-human primates with low CSF 5-HIAA concentrations also exhibited high intrinsic tolerance following modest intakes of alcohol, and high rates of aggression during intoxication. High preferences for sweet solutions were shown to predict excessive alcohol consumption. Maternal and paternal genetic influences played major roles in producing low CNS serotonin function and excessive alcohol consumption. These genetic influences on serotonin function were exacerbated by early rearing experiences, particularly parental deprivation.