Rheumatoid disease of the CNS with meningeal vasculitis presenting with a seizure.
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Arthritis, Rheumatoid↗
Biomedical subjects
H Weinberg
Publications and source records attributed to H Weinberg.
Group process and group phenomena on the Internet.
This article identifies group processes and group phenomena in discussion lists on the Internet and examines the differences and similarities with the processes in small and large groups. Group dynamics and phenomena, such as boundaries, cohesion, transference, scapegoating, and the leader's role are addressed. Large group features, such as alienation, vulnerability, and the vast amount of issues discussed in parallel are described. There are similarities between the discussion list and small groups on issues of cohesion and group norms, and in the psychological mechanisms of transference and scapegoating. There are differences regarding the contract, boundaries, leaving the group, and extra-group socialization. Although many of the phenomena described resemble a large group, a discussion list on the Internet maintains the illusion of being a small group and frequently acts like one. While a virtual therapy group would be somewhat different from a real group, it could nonetheless be useful.
Group Processes↗
CC130 pilot fatigue during re-supply missions to former Yugoslavia.
PURPOSE: Deployment of troops in foreign theaters requires a massive airlift capability. The fatigue encountered in such operations can be severe enough to pose a flight safety hazard. The current study documents sleep and the effect of fatigue on aircrew performance during re-supply missions in support of Canadian troops in Bosnia in 1996. METHODS: Ten routine re-supply missions from Trenton, Canada, to Zagreb, Croatia, were studied and involved 9 pilots and 9 co-pilots. To document their sleep hygiene, all pilots wore wrist actigraphs from approximately 5 d prior to the mission, until the mission was completed. Psychomotor performance was tested during the actual flights. Three psychomotor trials during the outbound transatlantic leg (Trenton to Lyneham, UK) were employed, one trial on the Lyneham-Zagreb-Lyneham leg, and three trials on the return transatlantic leg from Lyneham to Trenton. RESULTS: The amount of daily sleep during the 3-d period prior to the mission steadily decreased from an average of 8 h 40 min per day to 6 h 30 min (p < 0.001). During the missions, the worst night of sleep occurred during the second night overseas. During both transatlantic legs, there were significant decrements in the subjective ratings of alertness (p < 0.001), and increases in physical (p < 0.001) and mental fatigue (p < 0.001). Performance on the logical reasoning task as well as the multitask showed probable fatigue effects during the outbound leg of the missions. CONCLUSIONS: Our transport pilots showed a pattern of progressively decreasing sleep. Self-rated scores for alertness, mental and physical fatigue, indicate a deterioration of alertness, and an increase in fatigue throughout the long transatlantic flights.
Adult↗
Melatonin and zopiclone as pharmacologic aids to facilitate crew rest.
PURPOSE: In response to mission imperatives, transport aircrews must often sleep at inappropriate circadian times resulting in inadequate sleep. This study was undertaken to determine whether either melatonin or zopiclone could facilitate early circadian sleep, and to assess whether either of these medications would result in a psychomotor performance decrement which would preclude their use in aircrew. METHOD: Thirteen subjects from DCIEM completed a double-blind cross-over protocol. All subjects were assessed for psychomotor performance during 3 drug conditions (placebo, 10 mg melatonin, and 7.5 mg zopiclone), which were separated by one week. Each of these conditions involved 2 nights of sleep, back-to-back, with the first night being a normal circadian control sleep (23:00 h bedtime, arising at 06:45 h), and the second night being an early circadian drug sleep (drugs at 16:45 h, 17:00 h bedtime, arising at 23:45 h). All subjects were tested for psychomotor performance, on both nights of each of the 3 drug conditions, pre- and post-sleep. Further, during the early circadian drug night, all subjects were tested every hour after arising at 23:45 h (24:00 h until 07:00 h. At the beginning of each psychomotor test session, subjects were asked for their subjective levels of sleepiness and fatigue. RESULTS: Relative to placebo (339.5 min) the subjects slept more on melatonin (370.2 min, p < 0.01), and zopiclone (373.3 min, p < 0.01). Performance in serial reaction time (SRT) task (p < 0.001), logical reasoning task (LRT) (p < 0.001), serial subtraction task (SST) (p < 0.02), and Multitask (MT) (p < 0.03) were impaired for all 3 drug conditions immediately on awakening, compared with pre-sleep performance, as a result of a sleep-inertia effect. With respect to the subjective data, sleep inertia effects were evident for sleepiness (p < 0.001), mental fatigue (p < 0.002), and physical fatigue (p < 0.05). For SRT, LRT, and SST, performance recovered to pre-sleep levels within 1.25 h of awakening, and for MT recovery occurred 2.25 h after awakening. There were no differences in performance or subjective measures between placebo, melatonin and zopiclone. CONCLUSIONS: Both zopiclone and melatonin improved sleep relative to placebo. After sleep inertia, performance recovered to pre-sleep levels for all tasks and was sustained at that level throughout the balance of the testing period. There was no impact of melatonin or zopiclone on performance measures compared with placebo.
Adult↗
Spatiotemporal analysis of neuromagnetic events underlying the emergence of coordinative instabilities.
A full-head 143-channel superconducting quantum interference device was used to study changes occurring in the magnetic activity of the human brain during performance of an auditory-motor coordination task in which the rate of coordination was systematically increased. Previous research using the same task paradigm demonstrated that spontaneous switches in timing behavior that arise with higher coordination rates are accompanied by qualitative changes in spatiotemporal brain activity measured by electro- and magnetoencephalography. Here we show how these patterns can be decomposed into basic physiological events, i.e., evoked brain responses to acoustic tones and self-initiated finger movements. The frequency dependence of the amplitudes of these component responses may shed new light onto why spontaneous timing transitions occur in the first place.
Evoked Potentials, Auditory↗
Accelerated flap prefabrication with vascular endothelial growth factor.
Vascular endothelial growth factor (VEGF) is a potent promoter of angiogenesis that has been shown to enhance revascularization of ischemic tissues, including skin flaps. This study was designed to investigate the value of a single topical application of recombinant human VEGF to accelerate flap viability in a rat model of a non-ischemic prefabricated flap. Prefabricated flaps were created in 48 Sprague-Dawley rats. An autologous tail artery loop was anastomosed to the femoral artery and vein, and implanted subcutaneously in the lower abdomen. Flaps were divided into two groups of 24 each. At the time of loop implantation the control group received 0.9 percent NaCl or a 16 percent vol/wet polyvinyl alcohol (PVA) solution: the treatment group received VEGF in 0.9 percent NaCl or VEGF in PVA. The PVA gel was used to facilitate topical application In each group, 3- x 4-cm flaps nurtured by the tail artery pedicle were elevated and resutured into place after 3, 4, and 5 weeks. The percentage of surviving skin of each flap was determined by planimetry 7 days after flap elevation. Mean skin survival areas at 3, 4, and 5 weeks were control group 0 percent. 8 percent and 17.5 percent; and VEGIF-treated group, 6 percent, 40 percent, and 66.7 percent respectively VEGF significantly improved flap survival by 5 weeks (p = 0.02). These results suggest that VEGF can accelerate maturation of prefabricated flaps. This approach could expand the application of flap prefabrication as a resource for reconstructive surgery.
Animals↗
Electrophysiological indices of persistent post-concussion symptoms.
UNLABELLED: Mild head injuries (MHI) including concussion were once considered transient alterations of function that resulted in no long-term structural or functional effects. This opinion has changed somewhat in recent years, based on the scientific evidence and popular cases in the media that suggest MHI can result in damage that can, in some cases, lead to long-term cognitive sequelae. PURPOSE AND METHODS: An EP/ERP assessment battery is presented as a method for detecting changes in brain function that form the organic basis of persistent post-concussion symptoms (PCS). The primary focus of the paper was directed towards using this battery to determine whether or not brain function in individuals with persistent PCS was different than responses of individuals that comprised a nomative database. RESULTS: Visual and auditory ERPs and visual EPs were beyond a 2.5 standard deviation normal limit in young and older groups of individuals with persistent post-concussion symptoms. CONCLUSIONS: Evidence of changes in brain function in individuals with persistent post-concussion symptoms is consistent with the position that the post-concussion syndrome has a substantial biological, as opposed to a psychological, basis.
Adult↗
Electrophysiological evidence for the cumulative effects of concussion.
PURPOSE: A study was initiated with the intent of demonstrating the cumulative effects of concussion in junior hockey players using visual event-related potentials and post-concussion syndrome (PCS) self-reports. METHODS: Players were assessed at the beginning of the season (pre-injury) and at various times post-injury. RESULTS: The results suggest that players with three or more concussions differed significantly on the several cognitive PCS symptoms as well as for the latency of the P3 response compared to those with no concussion history. DISCUSSION: Event-related potentials are useful indices of the cumulative damage that can occur following multiple concussions. These measures correlate significantly with cognitive self-reports of PCS symptoms. CONCLUSIONS: This pattern of results is consistent with the position that each concussion potentially causes brain damage. Cumulative damage can be detected using electrophysiological measures of brain function.
Adolescent↗
Plastic surgical perspectives on vascular endothelial growth factor as gene therapy for angiogenesis.
The practice of plastic surgery has always remained at the frontier of medical science. Over the past few decades, this frontier has been marked by significant developments in the field of gene therapy. Gene therapy serves to replace, supplement, or manipulate a patient's genetic makeup to restore function that has been lost or to correct function that is aberrant. Recent technology may allow surgeons to augment the processes of wound healing and angiogenesis by transfecting genes encoding desirable proteins, such as vascular endothelial factor (VEGF), into ischemic tissues. VEGF is a vital growth factor in the development of blood vessels. Although its mechanisms of action are numerous, its sole function seems to be the augmentation of angiogenesis. VEGF is active in growth and development, in wound healing, and in various pathologic conditions, such as psoriasis and rheumatoid arthritis. The role of VEGF in the field of plastic surgery is just beginning to be explored; it may someday prove to be very rewarding.
Animals↗
Disinfection byproducts in drinking water: the analytical challenge.
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Chromatography, Gas↗
Staging arteriovenous fistula loops for lengthening of free-flap pedicles.
The authors investigated the optimal period of maturation following the creation of arteriovenous (AV) loops using polyterafluoroethylene (PTFE) in a white rat model, which were subsequently used to support free-tissue transfer The AV loops in Group 1 (n = 17) were allowed to mature for 3 days prior to creation of the flap, while those from Group 2 (n = 14) were allowed to mature for 5 days. Results were compared to those from a previous study in which the authors reported an 80 percent initial patency rate (n = 30) and a 67 percent viability rate, based on 12 patent loops after 7 days. In the present study, patency rates were 59 percent for the 3-day group and 79 percent for the 5-day group; viability rates were 50 and 64 percent, respectively. Considering both patent and nonpatent loops, the overall viability rates were 29 and 50 percent respectively. Maturation periods longer than 3 days for AV loops constructed from PTFE micrografts were determined to be preferable for subsequent free-tissue transfer.
Anastomosis, Surgical↗
Dynamic cortical activity in the human brain reveals motor equivalence.
That animals and humans can accomplish the same goal using different effectors and different goals using the same effectors attests to the remarkable flexibility of the central nervous system. This phenomenon has been termed 'motor equivalence', an example being the writing of a name with a pencil held between the toes or teeth. The idea of motor equivalence has reappeared because single-cell studies in monkeys have shown that parameters of voluntary movement (such as direction) may be specified in the brain, relegating muscle activation to spinal interneuronal systems. Using a novel experimental paradigms and a full-head SQUID (for superconducting quantum interference device) array to record magnetic fields corresponding to ongoing brain activity, we demonstrate: (1), a robust relationship between time-dependent activity in sensorimotor cortex and movement velocity, independent of explicit task requirements; and (2) neural activations that are specific to task demands alone. It appears, therefore, that signatures of motor equivalence in humans may be found in dynamic patterns of cortical activity.
Brain↗
A MEG analysis of the P300 in visual discrimination tasks.
Based on recent research that indicated that P300 scalp topography varies as a function of task and/or information to be processed, this study examined scalp-recorded magnetic fields correlated with the P300 by means of whole-head magnetoencephalography. Subjects performed two discrimination tasks, in which targets, defined on either object or spatial characteristics of the same visual stimuli, had to be discriminated. Based on the across-subject root mean square (RMS) functions a sequence of 4 components could be identified in both tasks, N1m, P3m, and two later components, which, based on their estimated neuronal sources, were classified as representing motor processes during and following the manual responses to target stimuli. Reliable between-task differences in source localization were obtained for the P3m component, but not for the other components. Inferior-medial sources were found for the P3m evoked by both spatial and object targets, with these sources being located about 3.5 cm more anterior for object targets. These results suggest that different neuronal sources, possibly located in subcortical regions in the vicinity of the thalamus, contribute to the P3m evoked by target stimuli defined by either object or spatial stimulus characteristics.
Adult↗
Neural network classifications and correlation analysis of EEG and MEG activity accompanying spontaneous reversals of the Necker cube.
It has recently been suggested that reentrant connections are essential in systems that process complex information [A. Damasio, H. Damasio, Cortical systems for the retrieval of concrete knowledge: the convergence zone framework, in: C. Koch, J.L. Davis (Eds.), Large Scale Neuronal Theories of the Brain, The MIT Press, Cambridge, 1995, pp. 61-74; G. Edelman, The Remembered Present, Basic Books, New York, 1989; M.I. Posner, M. Rothbart, Constructing neuronal theories of mind, in: C. Koch, J.L. Davis (Eds.), Large Scale Neuronal Theories of the Brain, The MIT Press, Cambridge, 1995, pp. 183-199; C. von der Malsburg, W. Schneider, A neuronal cocktail party processor, Biol. Cybem., 54 (1986) 29-40]. Reentry is not feedback, but parallel signalling in the time domain between spatially distributed maps, similar to a process of correlation between distributed systems. Accordingly, it was expected that during spontaneous reversals of the Necker cube, complex patterns of correlations between distributed systems would be present in the cortex. The present study included EEG (n=4) and MEG recordings (n=5). Two experimental questions were posed: (1) Can distributed cortical patterns present during perceptual reversals be classified differently using a generalised regression neural network (GRNN) compared to processing of a two-dimensional figure? (2) Does correlated cortical activity increase significantly during perception of a Necker cube reversal? One-second duration single trials of EEG and MEG data were analysed using the GRNN. Electrode/sensor pairings based on cortico-cortical connections were selected to assess correlated activity in each condition. The GRNN significantly classified single trials recorded during Necker cube reversals as different from single trials recorded during perception of a two-dimensional figure for both EEG and MEG. In addition, correlated cortical activity increased significantly in the Necker cube reversal condition for EEG and MEG compared to the perception of a non-reversing stimulus. Coherent MEG activity observed over occipital, parietal and temporal regions is believed to represent neural systems related to the perception of Necker cube reversals.
Adolescent↗
Effect of time on the viability of ischemic skin flaps treated with vascular endothelial growth factor (VEGF) cDNA.
This study examined the efficacy of gene therapy on wound healing. The authors investigated whether delivery of the gene encoding a particular cytokine, known to be important in angiogenesis, could affect ischemic skin flaps. Anterior abdominal skin flaps, based solely on the epigastric artery and vein, were created in the Sprague-Dawley rat model. At the time of elevation, the arterial pedicle supplying each flap was infused either with the gene for vascular endothelial growth factor (VEGF) or physiologic saline alone. The flaps were resutured into place and observed for a period of either 4 or 3 days, at which time the pedicle was ligated. Twenty minutes following ligation, blood flow in the flaps was measured by dye fluorescence. Tissue viability of the flaps was subsequently measured by planimetry after a period of 7 days. Flaps that received the VEGF gene and were ligated at 4 days had an average dye fluorescence index (DFI) of 31.1 following ligation, and 93.9 percent viable tissue after 7 days. Flaps that received saline alone, and were ligated following a similar interval, had an average DFI of 14.0 and 31.9 percent viable tissue. Among the subjects that were ligated at 3 days, only a single, gene-infused flap had any noticeable viable tissue after 7 days. The DFI of these groups was 11.0 for the gene-infused group and 22.1 for the saline-infused group. The results suggest that delivery of the gene for VEGF can improve the survival of ischemic skin flaps, but that the effect of gene therapy is not limitless.
Analysis of Variance↗
The advanced-stage therapy group.
Many authors describe a stage of maturity in the development of groups, but each highlights a different dimension. This article describes the characteristics of the advanced stage and the main axes along which it develops (internalization and containment, symbolization, self and self-other development, differentiation and individuation). It also offers a conceptual explanation for these developments and attempts to identify the conditions necessary for the emergence of this stage of maturity. An understanding of this stage and the conditions required for its development can be used by the group leader as a compass to help him or her navigate the group toward this objective.
Adult↗
Locally administered vascular endothelial growth factor cDNA increases survival of ischemic experimental skin flaps.
Microvascular surgery has emerged as an attractive area for recent advances in the field of gene therapy. The present study investigated the survival of ischemic, experimental skin flaps after treatment with the gene encoding vascular endothelial growth factor (VEGF). In 30 Sprague-Dawley rats, anterior abdominal skin flaps supplied by the epigastric artery and vein were created. Ten animals were treated with a mixture of liposomes and the cDNA encoding the 121-amino acid isoform of VEGF. Another 10 animals were treated with control plasmid DNA and liposome transfection medium; a third group of 10 animals was given physiologic saline. Each solution was injected directly into the femoral artery distal to the origin of the epigastric pedicle supplying the flap. Four days after injection, the pedicle was ligated and blood flow in the flap was approximated using dye fluorescence. Seven days later, the amount of viable tissue within the flap was measured by planimetry. After the animals were killed, specimens from both the operated and nonoperated sides of the abdomen were harvested for immunohistologic evidence of VEGF protein expression. Average dye fluorescence indices of the three groups (VEGF cDNA, control plasmid, and saline) 2 hours after pedicle ligation were 35.9, 23.9, and 53.9 percent, respectively (p < 0.05). Compared with the two control groups, flaps receiving VEGF cDNA had significantly greater tissue viability at the end of 7 days: 93.9 versus 28.1 percent for the control plasmid DNA group and 31.9 percent for the saline group (p < 0.05). Immunohistochemical staining documented increased deposition of VEGF protein in flaps that were infused with the VEGF cDNA versus saline alone (p < 0.05). The results indicated that the survival of ischemic tissues can be enhanced by administration of a cDNA encoding VEGF, a protein known to be important in the process of angiogenesis and wound healing.
Animals↗
Sensory feedback contributes to early movement-evoked fields during voluntary finger movements in humans.
Neuromagnetic field changes accompanying voluntary movement in humans ('movement-evoked fields' or MEFs) were recorded over the scalp using a whole-head MEG system during the performance of self-paced finger movements in order to determine the contribution of sensory feedback to the generation of these brain responses. It was found that cooling the subject's arm resulted in delays of 8 ms or more in the latency of the early movement-evoked field component (MEFI). These delays were attributed to increases in conduction times in the afferent pathways as confirmed by electrically evoked somatosensory responses and suggest a peripheral origin of the MEFI. In a second experiment, we demonstrated the effects of sensory input to the contralateral hand during a simple button pressing task in 4 subjects. The results indicated that responses over the hemisphere ipsilateral to the side of movement which resembled previously reported ipsilateral MEFs can be elicited by the spread of mechanical stimulation to opposite side of the body when a mechanical trigger is used. These experiments provide further evidence that early movement-evoked fields produced by unilateral finger movements are observed primarily over the contralateral somatosensory cortex and represent sensory feedback to the somatosensory cortex from the periphery.
Arm↗