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PubMed2006

Ballistic fractures during the 2003 Gulf conflict--early prognosis and high complication rate.

BACKGROUND: Ballistic fractures are devastating injuries often necessitating extensive reconstructive surgery or amputation, particularly if associated with high-energy transfer wounds. Infective complications are common, particularly in the austere environment encountered in war. We present the management and early outcome of these injuries with reference to the mechanism of injury and bony injury. METHOD: Data on ballistic fractures was collected prospectively during the 'war-fighting' phase of the 2003 Gulf Conflict, between 19th March and 20th May. Fractures were scored using the Red Cross Fracture classification and early outcome analysed. RESULTS: Thirty-nine patients, with 50 ballistic fractures, were treated by British military surgeons. Patients were predominantly Iraqi (90%) and 50 per cent of ballistic fractures were caused by bullets. Seventeen upper limb fractures and 33 lower limb fractures were sustained. There were seven traumatic amputations, and a further 2 limbs were amputated primarily. Methods of primary stabilisation for the remaining 41 fractures were: external fixation (22%), POP (14.5%), K-wires (14.5%) traction (10%), and no stabilisation (39%). Seven individuals were evacuated early after primary surgery, hence 43 ballistic fractures were available for follow-up. 13/43 (30%) of wounds became infected, 5/43 (11.5%) were deep infections necessitating surgical drainage. There were 4 late amputations (9.5%), 3 of which had initially been managed by external fixation. Infection occurred significantly more often in gunshot fractures (10/21, 48%), wounds closed primarily against the principles of war surgery (415, 80%) and intra-articular fractures (3/3, 100%) (p=0.022, 0.024 and 0.023 respectively). Differing methods of stabilisation had no bearing on the rate of postoperative infection. CONCLUSION: Ballistic fractures remain a challenge for trauma surgeons in times of war and still have a poor prognosis. Further work is required to determine the optimal treatment of these injuries during conflicts. In addition, there still seems to be a continued need to re-learn the principles of war surgery in order to minimise complications and optimise functional recovery.

Amputation, Traumatic↗

PubMedDate not supplied

Using self-organizing maps to identify potential halo white dwarfs.

We present the results of an unsupervised classification of the disk and halo white dwarf populations in the solar neighborhood. The classification is done by merging the results of detailed Monte Carlo (MC) simulations, which reproduce very well the characteristics of the white dwarf populations in the solar neighborhood, with a catalogue of real stars. The resulting composite catalogue is analyzed using a competitive learning algorithm. In particular we have used the so-called self-organized map. The MC simulated stars are used as tracers and help in identifying the resulting clusters. The results of such an strategy turn out to be quite satisfactory, suggesting that this approach can provide an useful framework for analyzing large databases of white dwarfs with well determined kinematical, spatial and photometric properties once they become available in the next decade. Moreover, the results are of astrophysical interest as well, since a straightforward interpretation of several recent astronomical observations, like the detected microlensing events in the direction of the Magellanic Clouds, the possible detection of high proper motion white dwarfs in the Hubble Deep Field and the discovery of high velocity white dwarfs in the solar neighborhood, suggests that a fraction of the baryonic dark matter component of our galaxy could be in the form of old and dim halo white dwarfs.

Artificial Intelligence↗

PubMed1997

Human brain functional imaging with reflectance CWS.

Continuous Wave Spectroscopy (CWS) has been used in human subjects to detect brain function by observation of brain oxygenation and blood volume changes. In this research, we have developed a device for imaging brain oxygenation and blood volume with multiple sources and detectors in an area of 10 x 12 cm. Twelve, 1 watt tungsten bulbs were used as a light source, together with 8 detectors consisting of silicon-photodiodes with band-pass filters at 760 and 850 nms. The detectors were placed on a model system of the human head, providing 16 source-detector combinations with 4 cm separation. Eight to 16 seconds were required to image a brain function. Models using resin and a black object which have similar optical characteristics to a brain were studied. The model study showed that we can detect changes in absorption as deep as 2 cm from the surface. Human subjects with relatively thin hair, who volunteered for this study, were asked to tap fingers and rest, or to observe light flashing and darkness alternatively for 10 to 20 minutes while the images were being taken. In the finger tapping, the blood volume increased in a small, 1-2 cm area, while in the light stimulation, a much larger area was affected with a greater increased blood volume. Oxygenation occurred also in the area where blood volume increased. We concluded that the CWS can be used to image the location of brain activity by means of blood volume increase and oxygenation. In addition, brain disfunction and diseases, such as learning disability and brain hematoma may be detected with this imaging device.

Adolescent↗

PubMed1989

Right hemisphere contribution to lexical access in an aphasic with deep dyslexia.

Three hemifield tachistoscopic studies of a right-handed patient with acquired Broca's aphasia and deep dyslexia, but with intact visual fields, are presented to support the hypothesis of right hemisphere (RH) participation in deep dyslexic reading. A systematic comparison of this deep dyslexic with the disconnected RHs of two patients with complete cerebral commissurotomy disclosed a similar, but not identical, pattern of abilities. The results demonstrate partial reliance on the RH for accessing the meaning of single words, but not for phonological encoding in this patient.

Adult↗

PubMed1984

Effect of alcohol on recall and recognition as functions of processing levels.

Other investigators have suggested that the memory impairments found in alcohol intoxication represent the failure to process information to sufficient depth, i.e., an encoding deficit. The present study employed different processing levels (semantic, phonemic and graphemic) in intentional-learning experiments to examine the effects of two different doses of alcohol on verbal free recall and recognition. Alcohol significantly impaired both recall and recognition. Guiding processing at information input with semantic orienting tasks and at retrieval with recognition testing improved the retention performance of both intoxicated subjects and controls administered a placebo. However, neither procedure corrected the relative decrement associated with the higher of the two doses of alcohol. Alcohol intoxication had no effect on the speed or accuracy of the initial encoding of items at any processing level. The results offer no support for the view that the verbal-retention deficits associated with alcohol intoxication are related either to the spontaneous failure to undertake deep semantic processing or to the inability to do so.

Adult↗

PubMed1998

Exercise Rolling Deep September 1997: a nurse's perspective.

The integration of the RNST with Med Squadron was the main objective of Exercise Rolling Deep. This objective was achieved most effectively and clearly indicated that should we be required to attend an operational deployment the teams are now much better prepared. The opportunity to experiment with the new surgical equipment was most useful and the experience of living in second line field conditions were both interesting and eye-opening! Med Squadron made a particular effort to make the exercise taxing but enjoyable which was appreciated by us all. In conclusion, the most poignant message felt by many was how valuable the senior and more experienced members of the team are. Appreciation must be expressed to those certain few who put so much effort into making the exercise such a valuable learning experience. All-in-all however, a highly beneficial exercise to have been allowed to experience--roll on Norway!

Education, Continuing↗

PubMed2000

Trajectory encoding in the hippocampus and entorhinal cortex.

We recorded from single neurons in the hippocampus and entorhinal cortex (EC) of rats to investigate the role of these structures in navigation and memory representation. Our results revealed two novel phenomena: first, many cells in CA1 and the EC fired at significantly different rates when the animal was in the same position depending on where the animal had come from or where it was going. Second, cells in deep layers of the EC, the targets of hippocampal outputs, appeared to represent the similarities between locations on spatially distinct trajectories through the environment. Our findings suggest that the hippocampus represents the animal's position in the context of a trajectory through space and that the EC represents regularities across different trajectories that could allow for generalization across experiences.

Algorithms↗

PubMed1990

Functional reorganization of primary somatosensory cortex in adult owl monkeys after behaviorally controlled tactile stimulation.

1. Multiple microelectrode maps of the hand representation within and across the borders of cortical area 3b were obtained before, immediately after, or several weeks after a period of behaviorally controlled hand use. Owl monkeys were conditioned in a task that produced cutaneous stimulation of a limited sector of skin on the distal phalanges of one or more fingers. 2. Analysis of microelectrode mapping experiment data revealed that 1) stimulated skin surfaces were represented over expanded cortical areas. 2) Most of the cutaneous receptive fields recorded within these expanded cortical representational zones were unusually small. 3) The internal topography of representation of the stimulated and immediately surrounding skin surfaces differed greatly from that recorded in control experiments. Representational discontinuities emerged in this map region, and "hypercolumn" distances in this map sector were grossly abnormal. 4) Borders between the representations of individual digits and digit segments commonly shifted. 5) The functionally defined rostral border of area 3b shifted farther rostralward, manifesting either an expansion of the cutaneous area 3b fingertip representation into cortical field 3a or an emergence of a cutaneous input zone in the caudal aspect of this normally predominantly deep-receptor representational field. 6) Significant lateralward translocations of the borders between the representations of the hand and face were recorded in all cases. 7) The absolute locations--and in some cases the areas or magnifications--of representations of many skin surfaces not directly involved in the trained behavior also changed significantly. However, the most striking areal, positional, and topographic changes were related to the representations of the behaviorally stimulated skin in every studied monkey. 3. These experiments demonstrate that functional cortical remodeling of the S1 koniocortical field, area 3b, results from behavioral manipulations in normal adult owl monkeys. We hypothesize that these studies manifest operation of the basic adaptive cortical process(es) underlying cortical contributions to perception and learning.

Animals↗

PubMed2003

Classification of clear-cell sarcoma as a subtype of melanoma by genomic profiling.

PURPOSE: To develop a genome-based classification scheme for clear-cell sarcoma (CCS), also known as melanoma of soft parts (MSP), which would have implications for diagnosis and treatment. This tumor displays characteristic features of soft tissue sarcoma (STS), including deep soft tissue primary location and a characteristic translocation, t(12;22)(q13;q12), involving EWS and ATF1 genes. CCS/MSP also has typical melanoma features, including immunoreactivity for S100 and HMB45, pigmentation, MITF-M expression, and a propensity for regional lymph node metastases. MATERIALS AND METHODS: RNA samples from 21 cell lines and 60 pathologically confirmed cases of STS, melanoma, and CCS/MSP were examined using the U95A GeneChip (Affymetrix, Santa Clara, CA). Hierarchical cluster analysis, principal component analysis, and support vector machine (SVM) analysis exploited genomic correlations within the data to classify CCS/MSP. RESULTS: Unsupervised analyses demonstrated a clear distinction between STS and melanoma and, furthermore, showed that CCS/MSP cluster with the melanomas as a distinct group. A supervised SVM learning approach further validated this finding and provided a user-independent approach to diagnosis. Genes of interest that discriminate CCS/MSP included those encoding melanocyte differentiation antigens, MITF, SOX10, ERBB3, and FGFR1. CONCLUSION: Gene expression profiles support the classification of CCS/MSP as a distinct genomic subtype of melanoma. Analysis of these gene profiles using the SVM may be an important diagnostic tool. Genomic analysis identified potential targets for the development of therapeutic strategies in the treatment of this disease.

Algorithms↗

PubMed1996

Relations among memory performance, mental workload and cardiovascular responses.

The levels of processing paradigm has been a powerful research framework in the study of memory for close to a quarter century. However, an objective index of depth of processing is still lacking. Two experiments using lists of words, presented to male subjects, wee performed to compare the effects of depth of processing, rate of presentation, and task incentive on recognition memory performance, self-reported workload, and cardiovascular responding. Memory performance results from the two experiments demonstrated higher recognition levels associated with deeper processing and slower presentation rates. Deeply encoded items were associated with faster recognition latencies. Self-reported workload levels were higher for deeper processing and faster presentation rates. Cardiovascular responses were generally amplified with the addition of a task incentive. Increased blood pressure was associated with faster presentation rates. Increased heart rate and decreased T-wave amplitude (i.e., increased sympathetic activity) were uniquely associated with the deep encoding of information presented at the fastest rate. This particular encoding condition was associated with increased recognition levels. Deeply encoded items were associated with increased suppression of heart rate variability during recognition. This combination of behavioral and cardiovascular measures may provide the basis for an objective index of depth of processing.

Adult↗

PubMed2005

Diet as a factor in behavioral radiation protection following exposure to heavy particles.

Major risks associated with radiation exposures on deep space missions include carcinogenesis due to heavy-particle exposure of cancer-prone tissues and performance decrements due to neurological damage produced by heavy particles. Because exposure to heavy particles can cause oxidative stress, it is possible that antioxidants can be used to mitigate these risks (and possibly some health risks of microgravity). To assess the capacity of antioxidant diets to mitigate the effects of exposure to heavy particles, rats were maintained on antioxidant diets containing 2% blueberry or strawberry extract or a control diet for 8 weeks prior to exposure to 1.5 or 2.0 Gy of accelerated iron particles at Brookhaven National Laboratory. Following irradiation rats were tested on a series of behavioral tasks: amphetamine-induced taste aversion learning, operant responding and spatial learning and memory. The results indicated that the performance of the irradiated rats maintained on the antioxidant diets was, in general, significantly better than that of the control animals, although the effectiveness of the diets ameliorating the radiation-induced deterioration in performance varied as a function of both the specific diet and the specific endpoint. In addition, animals fed antioxidant diets prior to exposure showed reduced heavy particle-induced tumorigenesis one year after exposure compared to the animals fed the control diet. These results suggest that antioxidant diets have the potential to serve as part of a system designed to provide protection to astronauts against the effects of heavy particles on exploratory missions outside the magnetic field of the earth.

Aging↗

PubMed2004

Prediction of neuropsychological impairment in multiple sclerosis: comparison of conventional magnetic resonance imaging measures of atrophy and lesion burden.

BACKGROUND: Cognition and magnetic resonance imaging correlations are well established in patients with multiple sclerosis (MS), but it is unclear whether lesion burden or atrophy accounts for most of the predictive variance. These indices have been directly compared in only a few studies. No such study included measurement of the third ventricle, which was strongly predictive of neuropsychological competence in the early literature. Furthermore, few studies accounted for the influence of age, premorbid intelligence, or depression. OBJECTIVE: To determine if conventional measures of lesion burden or atrophy predict cognitive dysfunction in MS while accounting for age, premorbid intelligence, and depression. METHODS: We studied 37 patients with MS and 27 controls matched according to demographic variables. Correlations between neuropsychological tests and the following magnetic resonance imaging indices were considered: T1 hypointense lesion volume, fluid-attenuated inversion recovery hyperintense lesion volume, third ventricle width, bicaudate ratio, and brain parenchymal fraction. Regression models predicting neuropsychological performance controlled for the effects of age, premorbid intelligence, and depression. We included only those tests discriminating patients with MS from controls. RESULTS: In each regression model, third ventricle width was the sole magnetic resonance imaging measure retained. When this variable was removed from consideration, brain parenchymal fraction was retained in all analyses. CONCLUSIONS: Brain atrophy accounts for more variance than lesion burden in predicting cognitive impairment in MS, and central atrophy in particular is strongly associated with neuropsychological morbidity. This finding may be explained in part by atrophy of the thalamus, a deep gray matter structure that mediates cognitive function via cortical and subcortical pathways. Enthusiasm for the clinical utility of third ventricle width is tempered by modest intraobserver and interobserver reliability.

Adult↗

PubMed1999

Mid-term results of endoscopic perforator vein interruption for chronic venous insufficiency: lessons learned from the North American subfascial endoscopic perforator surgery registry. The North American Study Group.

PURPOSE: The safety, feasibility, and early efficacy of subfascial endoscopic perforator surgery (SEPS) for the treatment of chronic venous insufficiency were established in a preliminary report. The long-term clinical outcome and the late complications after SEPS are as yet undetermined. METHODS: The North American Subfascial Endoscopic Perforator Surgery registry collected information on 148 SEPS procedures that were performed in 17 centers in the United States and Canada between August 1, 1993, and February 15, 1996. The data analysis in this study focused on mid-term outcome in 146 patients. RESULTS: One hundred forty-six patients (79 men and 67 women; mean age, 56 years; range, 27 to 87 years) underwent SEPS. One hundred and one patients (69%) had active ulcers (class 6), and 21 (14%) had healed ulcers (class 5). One hundred and three patients (71%) underwent concomitant venous procedures (stripping, 70; high ligation, 17; varicosity avulsion alone, 16). There were no deaths or pulmonary embolisms. One deep venous thrombosis occurred at 2 months. The follow-up periods averaged 24 months (range, 1 to 53 months). Cumulative ulcer healing at 1 year was 88% (median time to healing, 54 days). Concomitant ablation of superficial reflux and lack of deep venous obstruction predicted ulcer healing (P <.05). Clinical score improved from 8.93 to 3.98 at the last follow-up (P <. 0001). Cumulative ulcer recurrence at 1 year was 16% and at 2 years was 28% (standard error, < 10%). Post-thrombotic limbs had a higher 2-year cumulative recurrence rate (46%) than did those limbs with primary valvular incompetence (20%; P <.05). Twenty-eight of the 122 patients (23%) who had class 5 or class 6 ulcers before surgery had an active ulcer at the last follow-up examination. CONCLUSIONS: The interruption of perforators with ablation of superficial reflux is effective in decreasing the symptoms of chronic venous insufficiency and rapidly healing ulcers. Recurrence or new ulcer development, however, is still significant, particularly in post-thrombotic limbs. The reevaluation of the indications for SEPS is warranted because operations in patients without previous deep vein thrombosis are successful but operations in those patients with deep vein thrombosis are less successful. Operations on patients with deep vein occlusion have poor outcomes.

Adult↗

PubMed2004

The meaning of caring as described by nurses caring for a person who acts provokingly: an interview study.

Nurses working with people with learning disabilities are sometimes exposed to provoking behaviour such as unpredictable and violent actions, spitting and sexual harassment. Eight nurses at a group dwelling in Sweden were interviewed about their experiences when caring for a person who acts provokingly. Narrative interviews were conducted and interpreted using a method inspired by Ricoeur. Three themes were formulated which describe nurses' feelings of being tormented, disrupted and helpless. Nurses describe themselves as being deeply humiliated by physical violence, spittle, sexual invective and actions on the part of the patient. They respond more to being spat on and the sexual invective than to the patient's physical violence. The frequent humiliations could be seen as a symbolic language connected to defilement and 'evil' and therefore as having a deep symbolic meaning for the nurses. These results were interpreted and reflected on in the light of a theoretical framework from an affliction perspective in order to achieve a deeper understanding of the text. This paper shows that an affliction perspective is important when searching for the meaning of caring for a patient who acts provokingly. The study indicates that the goal in a provoking care situation must be to see the provoking patient, as he appears to the nurses in order to glimpse the goodness concealed behind the provoking facade.

Adaptation, Psychological↗

PubMed1983

Effect of ACTH, epinephrine, beta-endorphin, naloxone, and of the combination of naloxone or beta-endorphin with ACTH or epinephrine on memory consolidation.

The effect on retention of the post-training intraperitoneal administration of ACTH1-24 (0.2 or 2.0 micrograms/kg), epinephrine HCl (5.0 or 50.0 micrograms/kg), human beta-endorphin (0.1 or 1.0 microgram/kg), naloxone (0.4 mg/kg), and of the combination of naloxone or beta-endorphin with ACTH or epinephrine was studied in two different but closely related step-down inhibitory avoidance tasks in rats: task 1 (5 cm high 25 X 25 cm platform; 0.5 mA continuous footshock) and task 2 (7 X 25 cm platform, 0.3 mA discontinuous footshock). In task 1, saline control animals showed good retention in a test session carried out 24 hr later; beta-endorphin, ACTH and epinephrine caused amnesia; beta-endorphin potentiated the amnesic effect of ACTH and epinephrine; and naloxone caused memory facilitation and reversed the amnesic effect of ACTH and epinephrine. In task 2, control animals showed poor retention; beta-endorphin caused amnesia at the dose of 0.1 but not 1.0 microgram/kg; the other three drugs caused memory facilitation; naloxone potentiated the facilitatory effect of ACTH and epinephrine; and beta-endorphin reversed it and transformed it into a deep amnesia. These findings suggest that an opioid-mediated amnesic mechanism modulates the effect of ACTH and epinephrine on memory consolidation, either by dampening that effect when training parameters tend to make it facilitatory, or by enhancing it when training conditions tend to make it amnesic. On the basis of these and previous data it seems likely that the amnesic effect of ACTH and epinephrine could be mediated by endogenous beta-endorphin release.

Adrenocorticotropic Hormone↗

PubMed1996

Quantitative assessment of procedural competence. A prospective study of training in endoscopic retrograde cholangiopancreatography.

BACKGROUND: Endoscopic retrograde cholangiopancreatography (ERCP) is a technically demanding procedure that can cause substantial complications. Competence in performing ERCP and the learning curve for achieving competence are poorly understood. OBJECTIVE: To evaluate the number of supervised ERCPs that physicians must do to achieve procedural competence. Competence was defined as a 0.8 probability of successfully completing specific technical components of ERCP and an overall grading of competence as judged by the attending physician. DESIGN: Prospective study. SETTING: University training program for gastroenterologists. PARTICIPANTS: 17 gastroenterology fellows at various stages of training. MEASURES: Experienced therapeutic endoscopists prospectively graded gastroenterology fellows during 1796 consecutive ERCPs. Fellows were graded on their overall level of competence for the procedure and on specific technical components of ERCP. RESULTS: Grading data were available for 1450 ERCPs (81%). The number of ERCPs done before adequate skill was achieved was 160 for cholangiography, 140 for pancreatography, 160 for deep cannulation of the pancreatic duct, 120 for stone extraction, and 60 for stent insertion. Fellows achieved overall competence after completing 180 to 200 ERCPs. The predicted probability of overall competence was 0.8 after 137 ERCPs and 0.9 after 185 ERCPs. CONCLUSIONS: At least 180 ERCPs were required before these gastroenterology fellows could be considered competent in ERCP. This number is much greater than that previously recommended, and these findings have substantial implications for training guidelines and issues of competence and certification in ERCP. The methods used to define and evaluate competence in ERCP could also be used to assess competence in other medical procedures.

Cholangiopancreatography, Endoscopic Retrograde↗

PubMed1994

[The laryngeal mask as an instrument].

The laryngeal mask (LM) was developed by A. Brain to overcome the disadvantages of the face mask (impractical) and the tracheal tube (invasive). Today this new instrument is applied on a broad scale in Great Britain and with growing interest in continental Europe. The laryngeal mask comes in five sizes to fit five different age groups. The blindly applied technique of positioning the LM can be easily learned. Spontaneous or artificial ventilation is possible if the LM is in the correct position. Mechanical ventilation may lead to the insufflation of air into the stomach. Therefore, ventilatory peak pressure should not exceed 20-25 cm H2O and ventilation must be closely monitored. The risk of aspiration can be avoided by the proper selection of patients. The LM may be used with different anaesthetic techniques; muscle relaxant drugs are not mandatory. The authors have applied this mask more than 300 times, and this new instrument obviously has potential for different clinical indications. The LM may be applied for short surgical interventions in all age groups except premature infants. Complications such as regurgitation, aspiration and laryngospasm can be avoided by the awareness of the anaesthetist and by an adjusted deep plane of anaesthesia. Apart from anaesthesia, the LM can be used for bronchoscopy in children, for difficult intubations and as a preliminary airway in cases of resuscitation. Two studies performed in Great Britain have evaluated the LM for resuscitation. The investigations should be confirmed in German-speaking countries.

Humans↗

PubMed2000

The impact of deep brain stimulation on executive function in Parkinson's disease.

Deep brain stimulation (DBS) of the subthalamic nucleus (STN) or the internal segment of the globus pallidus (GPi) improves Parkinson's disease and increases frontal blood flow. We assessed the effects of bilateral DBS on executive function in Parkinson's disease patients, seven with electrodes implanted in the STN and six in the GPi. Patients were assessed off medication with stimulators off, on and off again. The groups showed differential change with stimulation on the Reitan Trail-Making test (TMT B) (STN more improved) and on some measures of random number generation and Wisconsin Card Sorting (STN improved, GPi worse with stimulation). Across the groups, stimulation speeded up responding (Stroop control trial, TMT A) and improved performance on paced serial addition and missing digit tests. Conversely, conditional associative learning became more errorful with stimulation across the two groups. In general, change in performance with stimulation was significant for the STN but not the GPi group. These results support two opposite predictions. In support of current models of Parkinson's disease, 'releasing the brake' on frontal function with DBS improved aspects of executive function. Conversely, disruption of basal ganglia outflow during DBS impaired performance on tests requiring changing behaviour in novel contexts as predicted by Marsden and Obeso in 1994.

Association Learning↗