Assessment of the Factors Influencing the Recording Performance of Circumneural Electrodes

The quality of recorded peripheral nerve signals is decisive for their application in therapies. The electroneurogram can be recorded via implantable circumeural electrodes that are wrapped around the peripheral nerve. The shape and amplitude of the signal recorded by the electrode are influenced by the design and contact configuration of the electrode. In this paper, the impact of the number of contacts, contact size and electrical insulation to the outside is investigated to predict the single fiber action potential based on the measured impedance data.

Definition of occult hypoperfusion in trauma: A systematic literature review

INTRODUCTION

Occult hypoperfusion (OH) entails inadequate tissue oxygenation in the presence of normal vital signs. Numerous studies have demonstrated that this phenomenon is associated with impaired outcome and increased mortality, however definitions of OH differ between studies. The aim of the current study was to identify and evaluate the published definitions of the term `occult hypoperfusion` in trauma (tOH).

MATERIAL & METHODS

A review of literature was performed using the Medline database. The following MeSH terms have been used: occult hypoperfusion, severe trauma, polytrauma, resuscitation. Clinical studies on OH were included and utilized definitions have been compared. A predefined data-interpretation process was applied to create an integrative definition for tOH.

RESULTS

A total of 43 publications used the term OH. A definition of OH was provided in 16 manuscripts. A pooled mean number of participants of 729 (SD: 1158) was found per study. The majority of manuscripts combine multiple parameters for inadequate tissue oxygenation and normal vital signs to define OH in trauma. In 12 manuscripts, specific cut-off values for hemodynamic parameters (SBP/PR/UP) and in 11/16 papers exact metabolic thresholds (lactate/B.E) were defined. The following definition best integrates definitions in current literature: Lactate > 2 mmol/l or BE <-3 mmol/l (to define inadequate oxygenation) plus SBP > 90 mmHg and PR < 120 bpm (to define normal macroperfusion).

CONCLUSIONS

The current systematic review demonstrates that definitions of occult hypoperfusion in trauma differ in the literature. The following comprehensive definition for (tOH) is proposed: Lactate > 2 mmol/l or BE <-3 mmol/l plus SBP > 90 mmHg and PR < 120 bpm. This recommendation appears to represent current literature on tOH and may improve the identification of trauma patients at risk for OH and related complicated courses. Further validation studies are required to demonstrate the clinical role of tOH and the proposed definition.

Screening chimeric GAA variants in preclinical study results in hematopoietic stem cell gene therapy candidate vectors for Pompe disease

Pompe disease is a rare genetic neuromuscular disorder caused by acid α-glucosidase (GAA) deficiency resulting in lysosomal glycogen accumulation and progressive myopathy. Enzyme replacement therapy, the current standard of care, penetrates poorly into the skeletal muscles and the peripheral and central nervous system (CNS), risks recombinant enzyme immunogenicity, and requires high doses and frequent infusions. Lentiviral vector-mediated hematopoietic stem and progenitor cell (HSPC) gene therapy was investigated in a Pompe mouse model using a clinically relevant promoter driving nine engineered GAA coding sequences incorporating distinct peptide tags and codon optimizations. Vectors solely including glycosylation-independent lysosomal targeting tags enhanced secretion and improved reduction of glycogen, myofiber, and CNS vacuolation in key tissues, although GAA enzyme activity and protein was consistently lower compared with native GAA. Genetically modified microglial cells in brains were detected at low levels but provided robust phenotypic correction. Furthermore, an amino acid substitution introduced in the tag reduced insulin receptor-mediated signaling with no evidence of an effect on blood glucose levels in Pompe mice. This study demonstrated the therapeutic potential of lentiviral HSPC gene therapy exploiting optimized GAA tagged coding sequences to reverse Pompe disease pathology in a preclinical mouse model, providing promising vector candidates for further investigation.

Stress related growth after severe trauma: Investigating long-term psychiatric outcomes and coping mechanisms 20+ years after injury

Objective

There is limited research on the long-term psychiatric outcomes of severely injured patients. Those studies existing, focus on the negativ effects like post-traumatic stress disorder, anxiety and depression. Yet, also psychiatric improvements can be noticed in patients after severe trauma, mainly focused on stress related growth. In our study we investigated coping mechanisms in multiply injured patients at least 20 years after trauma.

Methods

631 patients, who suffered a severe injury between 1971 and 1990 were contacted 20 or more years later. All patients were 3 to 60 years of age when injured and were attended to at the same institution. 36 questions inspired by the stress related growth scale (SRGS) and the post-traumatic growth inventory (PGI) were enquired via a questionnaire. Questions touched on 5 specific topics relating to growth: 1) relationships to others, 2) personal strengths, 3) appreciation of life, 4) new possibilities and 5) spiritual change. Each question quantified improvements in specific areas: Possible answers were „None at all“, „some“ and „a great deal“.

Results

A total of 338 patients returned the questionnaire and could be included in our study. Gender distribution was 114 females (33,8%) to 223 males (66,8%). 96,5% of patients reported improvements regarding at least one of the 36 questions. Approximately a third of patients noticed distinct improvements regarding their relationship to others (29,2%) and their appreciation of life (36,2%). Furthermore, 32,5% of patients registered overall positive attitudes towards new possibilities. Referring to spiritual changes, only 20,5% of patients reported positive changes, while 55,7% reported no changes at all. Regarding personal strengths, 23,4% indicated overall positive changes compared with 35% indicating no changes at all.

Statistical analysis showed women to adapt significantly better (p &lt; 0,01) in every aspect besides spiritual changes. Furthermore, we noticed weak positive correlations between positive changes and age at injury (r = 0.26) as well as injury severity (r = 0.152). We saw, however no correlation with general health.

Conclusion

20 years after severe trauma, patients report improvements in their relationship with others, appreciation of life and attitude towards new possibilities. Such coping mechanisms, as results of stress related growth, should be identified and fostered in clinical practice.

Correction of pathology in mice displaying Gaucher disease type 1 by a clinically-applicable lentiviral vector

Gaucher disease type 1 (GD1) is an inherited lysosomal disorder with multisystemic effects in patients. Hallmark symptoms include hepatosplenomegaly, cytopenias, and bone disease with varying degrees of severity. Mutations in a single gene, glucosidase beta acid 1 (GBA1), are the underlying cause for the disorder, resulting in insufficient activity of the enzyme glucocerebrosidase, which in turn leads to a progressive accumulation of the lipid component glucocerebroside. In this study, we treat mice with signs consistent with GD1, with hematopoietic stem/progenitor cells transduced with a lentiviral vector containing an RNA transcript that, after reverse transcription, results in codon-optimized cDNA that, upon its integration into the genome encodes for functional human glucocerebrosidase. Five months after gene transfer, a highly significant reduction in glucocerebroside accumulation with subsequent reversal of hepatosplenomegaly, restoration of blood parameters, and a tendency of increased bone mass and density was evident in vector-treated mice compared to non-treated controls. Furthermore, histopathology revealed a prominent reduction of Gaucher cell infiltration after gene therapy. The vector displayed an oligoclonal distribution pattern but with no sign of vector-induced clonal dominance and a typical lentiviral vector integration profile. Cumulatively, our findings support the initiation of the first clinical trial for GD1 using the lentiviral vector described here.

Cardiac Depression in Pigs after Multiple Trauma - Characterization of Posttraumatic Structural and Functional Alterations

The purpose of this study was to define the relationship between cardiac depression and morphological and immunological alterations in cardiac tissue after multiple trauma. However, the mechanistic basis of depressed cardiac function after trauma is still elusive. In a porcine polytrauma model including blunt chest trauma, liver laceration, femur fracture and haemorrhage serial trans-thoracic echocardiography was performed and correlated with cellular cardiac injury as well as with the occurrence of extracellular histones in serum. Postmortem analysis of heart tissue was performed 72 h after trauma. Ejection fraction and shortening fraction of the left ventricle were significantly impaired between 4 and 27 h after trauma. H-FABP, troponin I and extracellular histones were elevated early after trauma and returned to baseline after 24 and 48 h, respectively. Furthermore, increased nitrotyrosine and Il-1β generation and apoptosis were identified in cardiac tissue after trauma. Main structural findings revealed alteration of connexin 43 (Cx43) and co-translocation of Cx43 and zonula occludens 1 to the cytosol, reduction of α-actinin and increase of desmin in cardiomyocytes after trauma. The cellular and subcellular events demonstrated in this report may for the first time explain molecular mechanisms associated with cardiac dysfunction after multiple trauma.

Update on the role of endothelial cells in trauma

PURPOSE

This review gives an overview of physiological processes, mainly regarding vascular endothelial cells and their important role in hemostasis, information processing, and communication during trauma. An insight is given into molecules and cells involved in the first innate immune response through to the behavior of endothelial cells in developing trauma. The goal of this review is to show the overlap of crucial factors related to the endothelium and the development of trauma.

METHODS

A systemic literature search was performed using Google scholar and PubMed.

RESULTS

The results of the literature search showed that the endothelium, especially the vascular endothelium, is involved in various cellular and subcellular pathways of activation, suppression, and transfer of information. A variety of molecules and cells are orchestrated, subsequently the endothelium gets in contact with a traumatizing event.

CONCLUSION

The endothelium is one of the first barriers that comes into contact with exo- and endogenous trauma-related signals and is a pivotal point in activating subsequent pathways and cascades by transfer of information.

Impact of pelvic fractures on the early clinical outcomes of severely injured trauma patients

BACKGROUND

Pelvic fractures contribute to morbidity and mortality following injury. We sought to study the impact of pelvic fractures on the clinical course and outcomes of trauma patients with a pelvic fracture in comparison to patients with similar injury severity without pelvic fracture to identify potential parameters to track patients' clinical course post-injury.

METHODS

A cohort of 206 consecutive blunt trauma survivors, studied over a 5-year period in a level I trauma center of which 75 patients (36.4%) had a pelvic fracture, was included in the study. To perform a retrospective cohort study with matched controls, 60 patients of the pelvic fracture group [(PF), 41 males and 19 females; age: 40 ± 17; injury severity score (ISS): 26.6 ± 9.3] were compared to 60 patients without pelvic fracture (non-PF) trauma as controls (41 males and 19 females; age: 40 ± 13; ISS: 26.9 ± 7.7), both with matching age (±5 years), sex, and ISS (±5 points).

RESULTS

Statistically significant differences were observed in Intensive Care Unit (ICU) length of stay (LOS), total LOS, and Marshall MOD score between PF and non-PF groups, respectively. Acid-base markers such as pH, lactate, LDH, and base deficit were all significantly altered in PF compared to non-PF cohort upon admission. Moreover, our analysis showed significant differences in inflammatory biomarkers (Prolactin, CRP, and IL-6), and clinical parameters (CPK, Hgb, Platelets count, and WBC) over the 7-day clinical course in patients with PF when compared to non-PF cohort.

CONCLUSION

In this matched cohort, patients with pelvic fractures exhibited biochemical and physiological alterations upon admission. Furthermore, our results suggest that pelvic fracture affects the clinical outcomes in severely injured patients, independently of injury severity, mechanism of injury, age or gender.

Characterization of blunt chest trauma in a long-term porcine model of severe multiple trauma

Chest trauma has a significant relevance on outcome after severe trauma. Clinically, impaired lung function typically occurs within 72 hours after trauma. However, the underlying pathophysiological mechanisms are still not fully elucidated. Therefore, we aimed to establish an experimental long-term model to investigate physiological, morphologic and inflammatory changes, after severe trauma. Male pigs (sus scrofa) sustained severe trauma (including unilateral chest trauma, femur fracture, liver laceration and hemorrhagic shock). Additionally, non-injured animals served as sham controls. Chest trauma resulted in severe lung damage on both CT and histological analyses. Furthermore, severe inflammation with a systemic increase of IL-6 (p = 0.0305) and a local increase of IL-8 in BAL (p = 0.0009) was observed. The pO₂/FiO₂ ratio in trauma animals decreased over the observation period (p < 0.0001) but not in the sham group (p = 0.2967). Electrical Impedance Tomography (EIT) revealed differences between the traumatized and healthy lung (p < 0.0001). In conclusion, a clinically relevant, long-term model of blunt chest trauma with concomitant injuries has been developed. This reproducible model allows to examine local and systemic consequences of trauma and is valid for investigation of potential diagnostic or therapeutic options. In this context, EIT might represent a radiation-free method for bedside diagnostics.

Measuring information transfer in a soft robotic arm

Soft robots can exhibit diverse behaviors with simple types of actuation by partially outsourcing control to the morphological and material properties of their soft bodies, which is made possible by the tight coupling between control, body, and environment. In this paper, we present a method that will quantitatively characterize these diverse spatiotemporal dynamics of a soft body based on the information-theoretic approach. In particular, soft bodies have the ability to propagate the effect of actuation through the entire body, with a certain time delay, due to their elasticity. Our goal is to capture this delayed interaction in a quantitative manner based on a measure called momentary information transfer. We extend this measure to soft robotic applications and demonstrate its power using a physical soft robotic platform inspired by the octopus. Our approach is illustrated in two ways. First, we statistically characterize the delayed actuation propagation through the body as a strength of information transfer. Second, we capture this information propagation directly as local information dynamics. As a result, we show that our approach can successfully characterize the spatiotemporal dynamics of the soft robotic platform, explicitly visualizing how information transfers through the entire body with delays. Further extension scenarios of our approach are discussed for soft robotic applications in general.

Impact of haemorrhagic shock intensity on the dynamic of alarmins release in porcine poly-trauma animal model

PURPOSE

Traumatic insults result in an altered inflammatory response, in which alarmins release has a central role. The impact of haemorrhagic shock intensity on the long-term kinetics of alarmins is not yet fully elucidated. We investigated these aspects in a combined trauma (chest, abdominal, and extremities injury) porcine model with different severities and durations of haemorrhagic shock.

METHODS

After induction of combined trauma (tibia fracture, lung contusion, and liver laceration), haemorrhagic shock was induced at different intensities: moderate haemorrhage (MH; n = 15): mean arterial pressure (MAP) <30 ± 5 mmHg [maximum loss of total blood volume (TBVmax): 45 %] for 90 min, and severe haemorrhage (SH; n = 10): MAP <25 ± 5 mmHg (TBVmax 50 %) for 120 min. Resuscitation was performed using a standardized crystalloid infusion protocol. Animals were mechanically ventilated and underwent ICU-monitoring for 48 h (MH) and 48.5 h (SH). Blood samples were collected over the clinical time course, and systemic levels of serum alarmins [High-Mobility Group Protein B-1 (HMGB-1) and Heat Shock Protein 70 (HSP70)] were measured using an ELISA kit.

RESULTS

Heart rate, systemic blood pressure, lactate, and base excess were significantly altered as a function of haemorrhagic shock in both trauma groups (MH and SH). Systemic HMGB-1 levels were significantly elevated in both trauma groups when compared to the sham group. Haemorrhagic shock severity and duration were positively correlated with HMGB-1 levels and compared to baseline values, concentrations remained significantly increased in SH when compared to MH. On the other hand, we observed a significant decrease in the systemic HSP70 levels of trauma groups (MH, and SH) when compared to the sham group, which was significantly decreased compared to baseline values in SH over the entire time course.

CONCLUSION

Our data show that haemorrhagic shock duration and severity affect the systemic levels of HMGB-1 and HSP70. This early alarmins release after trauma can be used to guide the treatment strategies (e.g. surgical procedures) of polytrauma patients.

Exploiting short-term memory in soft body dynamics as a computational resource

Soft materials are not only highly deformable, but they also possess rich and diverse body dynamics. Soft body dynamics exhibit a variety of properties, including nonlinearity, elasticity and potentially infinitely many degrees of freedom. Here, we demonstrate that such soft body dynamics can be employed to conduct certain types of computation. Using body dynamics generated from a soft silicone arm, we show that they can be exploited to emulate functions that require memory and to embed robust closed-loop control into the arm. Our results suggest that soft body dynamics have a short-term memory and can serve as a computational resource. This finding paves the way towards exploiting passive body dynamics for control of a large class of underactuated systems.

Assessment of coincidence and defect sizes in Bankart and Hill-Sachs lesions after anterior shoulder dislocation: a radiological study

OBJECTIVE

Bankart and Hill-Sachs lesions are often associated with anterior shoulder dislocation. The MRI technique is sensitive in diagnosing both injuries. The aim of this study was to investigate Bankart and Hill-Sachs lesions with MRI to determine the correlation in occurrence and defect sizes of these lesions.

METHODS

Between 2006 and 2013, 446 patients were diagnosed with an anterior shoulder dislocation and 105 of these patients were eligible for inclusion in the study. All patients were examined using MRI. Bankart lesions were classified as cartilaginous or bony lesions. Hill-Sachs lesions were graded I-III using a modified Calandra classification.

RESULTS

The co-occurrence of injuries was high [odds ratio (OR) = 11.47; 95% confidence interval (CI) = 3.60-36.52; p < 0.001]. Patients older than 29 years more often presented with a bilateral injury (OR = 16.29; 95% CI = 2.71-97.73; p = 0.002). A correlation between a Bankart lesion and the grade of a Hill-Sachs lesion was found (ρ = 0.34; 95% CI = 0.16-0.49; p < 0.001). Bankart lesions co-occurred more often with large Hill-Sachs lesions (O  = 1.24; 95% CI = 1.02-1.52; p = 0.033).

CONCLUSION

If either lesion is diagnosed, the patient is 11 times more likely to have suffered the associated injury. The size of a Hill-Sachs lesion determines the co-occurrence of cartilaginous or bony Bankart lesions. Age plays a role in determining the type of Bankart lesion as well as the co-occurrence of Bankart and Hill-Sachs lesions.

ADVANCES IN KNOWLEDGE

This study is the first to demonstrate the use of high-quality MRI in a reasonably large sample of patients, a positive correlation of Bankart and Hill-Sachs lesions in anterior shoulder dislocations and an association between the defect sizes.

The long-term clinical outcome after pelvic ring injuries

We report the functional and socioeconomic long-term outcome of patients with pelvic ring injuries.

We identified 109 patients treated at a Level I trauma centre between 1973 and 1990 with multiple blunt orthopaedic injuries including an injury to the pelvic ring, with an Injury Severity Score (ISS) of ≥ 16. These patients were invited for clinical review at a minimum of ten years after the initial injury, at which point functional results, general health scores and socioeconomic factors were assessed.

In all 33 isolated anterior (group A), 33 isolated posterior (group P) and 43 combined anterior/posterior pelvic ring injuries (group A/P) were included. The mean age of the patients at injury was 28.8 years (5 to 55) and the mean ISS was 22.7 (16 to 44).

At review the mean Short-Form 12 physical component score for the A/P group was 38.71 (22.12 to 56.56) and the mean Hannover Score for Polytrauma Outcome subjective score was 67.27 (12.48 to 147.42), being significantly worse compared with the other two groups (p = 0.004 and p = 0.024, respectively). A total of 42 patients (39%) had a limp and 12 (11%) required crutches. Car or public transport usage was restricted in 16 patients (15%). Overall patients in groups P and A/P had a worse outcome. The long-term outcome of patients with posterior or combined anterior/posterior pelvic ring injuries is poorer than of those with an isolated anterior injury.

Cite this article: Bone Joint J 2013;95-B:548–53.

Are individual differences of attachment predicting bereavement outcome after perinatal loss? A prospective cohort study

OBJECTIVE

The purpose of this study was to examine the influence of attachment, social support and the quality of the current partnership on the outcome of bereavement after perinatal loss.

METHODS

In a prospective cohort design 33 women after perinatal loss were approached on admission to hospital and reassessed four weeks, four months and nine months later. The initial assessment included the Adult Attachment Interview and self-report questionnaires for social support and quality of the current partnership. Bereavement outcome was assessed using measures of grief (MTS), depression and anxiety (HADS), psychological distress (BSI), somatisation (BSI-SOM) and symptoms of PTSD (PDS).

RESULTS

All measures of outcome showed a significant improvement over time. Standardized effect sizes between the initial assessment and nine month follow-up ranged between .36 for anxiety (HADS) and 1.02 for grief (MTS). Social support, quality of the partnership and secure attachment correlated inversely, and insecure preoccupied attachment correlated positively with the outcome measures. Preoccupied attachment was included as a predictor in two multivariate statistical models of non-linear regression analysis, one with somatisation (adjusted R2=.698, P=.016), the other with posttraumatic stress symptoms at nine month follow-up (adjusted R2=.416, P=.002) as target variable. Initial assessment scores of psychological distress predicted the course of the respective measure during follow-up (adjusted R2=.432, P=.014).

CONCLUSION

Attachment, social support and the quality of the current partnership have an impact on the course of bereavement after perinatal loss. Secondary prevention after the event may focus on these factors in order to offer specific counselling and support.

Slip speed feedback for grip force control

Grasp stability in the human hand has been resolved by means of an intricate network of mechanoreceptors integrating numerous cues about mechanical events, through an ontogenetic grasp practice. An engineered prosthetic interface introduces considerable perturbation risks in grasping, calling for feedback modalities that address the underlying slip phenomenon. In this study, we propose an enhanced slip feedback modality, with potential for myoelectric-based prosthetic applications, that relays information regarding slip events, particularly slip occurrence and slip speed. The proposed feedback modality, implemented using electrotactile stimulation, was evaluated in psychophysical studies of slip control in a simplified setup. The obtained results were compared with vision and a binary slip feedback that transmits on-off information about slip detection. The slip control efficiency of the slip speed display is comparable to that obtained with vision feedback, and it clearly outperforms the efficiency of the on-off slip modality in such tasks. These results suggest that the proposed tactile feedback is a promising sensory method for the restoration of stable grasp in prosthetic applications.

[A false aneurysm as a rare complication of knee arthroscopy]

We present the rare case of a false aneurysm of the genus lat which occurred after knee arthroscopy. Apart from a pulse-synchronic swelling in close proximity to the former anterolateral portal there were no complaints and no pain. The diagnostic and therapeutic strategies - in this case performed with coiling of the involved vessel - are presented and discussed.

[Gender-specific evaluation of student's career planning during medical study in terms of orthopaedic trauma]

BACKGROUND

Due to recent changes in the medical licencing act as well as to the introduction of a new model-course programme for medical studies, careers in medicine have become increasingly more attractive. However, there is still a dramatic shortage in younger generation physicians, especially within the surgical fields. The goal of this cross-sectional study was the gender-specific assessment of the ideal career wishes of students during medical school, with a focus being placed in orthopaedic trauma surgery.

MATERIALS AND METHODS

During the winter semester of 2010/2011 an online questionnaire (www.surveymonkey.com) was created for students enrolled in their 3rd to 12th semester (n=887). The questionnaire consisted of 50 questions [Likert scale (LS); 5 = agree, 1 = disagree] along with 10 free response questions. The scope of these questions ranged from personal career goals, within the context of their learning environment, to general life goals and planning. With regard to career choice, a differentiation was made between students' ideal career choices/subjects (IS), which were based solely on personal affinity, and so-called reality-based subjects (RS), which students considered more practical and to which they were more likely to apply in the future.

RESULTS

The response rate was 36,4% (n=323, 23,4 years, 6.3 semesters, 226 [70.0%] female [f] and 97 [30.0%] male [m]). A total of 206 students (63.8%; m=55.7% vs. f=66.7%; p=0.047) were able to pinpoint an IS, this percentage increased with increasing semester number (p=0.048). Overall, 29.1% of students indicated that their IS lay in the field of orthopaedic trauma, while 20.0% of men and 19.1% of women saw it as a realistic career path (RS). Throughout the course of their studies, from the 3rd semester to their practical year, a declining tendency was observed regarding the agreement between ideal and realistic career paths. Particularly evident was a decreasing interest in the field of orthopaedic trauma, beginning around the 9th semester and during the practical year, especially among the female student population. The reason for this shift seems multifactorial, ranging from concerns about family planning as well as the work load in a male-dominated field. By the time students enter their practical year, 13.5% of women and 15.4% of men were still certain in their choice to pursue a career in orthopaedic trauma (RS).

CONCLUSIONS

It seems that there is great interest in the fields of orthopaedic trauma among both female and male students in the middle portion of their studies. Women, especially, tend to prefer a specialisation in this operative field early in the course of their studies. However, this pool of potential successors decreases dramatically with time, due to personal experiences garnered on the wards, expectations regarding career paths (male-dominated, long hours) as well as concerns about family planning. The most dramatic shift seems to occur during the practical year.

[Evaluation of microcirculatory disorders in shock patients]

The microcirculatory status depicts an indicator of organ perfusion in hemodynamic shock. Distribution pattern of microcirculatory disturbances reflects the underlying cause of shock: In septic shock, organ perfusion is severely impaired via arteriolo-venous shunting with shutting up small vessel perfusion; however, cardiogenic shock is characterized by a global impairment of microcirculation, involving all vascular beds. Hence, a differentiated evaluation of microcirculatory disturbances not only supports an early diagnosis of an imminent multiorgan dysfunction syndrome (MODS), but also allows a more accurate evaluation of severity of hemodynamic compromise in critical care medicine. Bedside sidestream darkfield (SDF) technique offers the opportunity to describe the microcirculatory status quo semiquantitatively and to evaluate the effect of novel therapeutic approaches on microcirculation. Further technical improvements of this technique may open new fields of diagnostic and therapeutic applications in intensive care medicine by supporting an early diagnosing of MODS, evaluating prognosis, and optimizing therapeutic measures .

Autonomic regulation during mild therapeutic hypothermia in cardiopulmonary resuscitated patients

OBJECTIVE

We investigated whether there are differences in autonomic cardiovascular regulation in resuscitated patients undergoing therapeutic hypothermia (TH) in relation to the clinical outcome.

METHOD

Between 2005 and 2007, 18 consecutive resuscitated patients were enrolled. ECG and blood pressure data were recorded for 48 h during hypothermia and warming up to a body core temperature of 36°C. Autonomic regulation was assessed by applying time, frequency, and non-linear dynamics domain methods from heart rate and blood pressure variability (HRV/BPV) analyses.

RESULTS

Nine patients survived with good neurological recovery, and nine patients died during the ICU stay. In both groups, we found a decreased HRV presented by standard deviation of R-R intervals (sdNN) below 50 ms(2) at each time of measurement. Immediately after recovery to a body core temperature of 36°C, a significant higher HRV was found in survivors compared to non-survivors by means of indices sdNN (40.2 ± 19.5 vs. 10.9 ± 4.1 ms(2), P = 0.01), R-R intervals distribution histogram [shannon] (3.7 ± 0.6 vs. 2.2 ± 0.4, P = 0.008), very low frequency band [VLF] (152.2 ± 99.3 vs. 3.4 ± 1.9, P = 0.001) and the variance of the time series of R-R intervals [Wsdvar] (1.16 ± 0.52 vs. 0.29 ± 0.25, P = 0.02) . A decreased spontaneous BPV was found only among survivors comparing blood pressure characteristics within stable hypothermia to the initial state before hypothermia.

CONCLUSION

Resuscitated patients show a significantly reduced HRV before, during and after TH. Compared to survivors, the non-survivors show a further and significantly decrease of HRV immediately after hypothermia.

Mice lacking Tbk1 activity exhibit immune cell infiltrates in multiple tissues and increased susceptibility to LPS-induced lethality

TBK1 is critical for immunity against microbial pathogens that activate TLR4- and TLR3-dependent signaling pathways. To address the role of TBK1 in inflammation, mice were generated that harbor two copies of a mutant Tbk1 allele. This Tbk1(Δ) allele encodes a truncated Tbk1(Δ) protein that is catalytically inactive and expressed at very low levels. Upon LPS stimulation, macrophages from Tbk1(Δ/Δ) mice produce normal levels of proinflammatory cytokines (e.g., TNF-α), but IFN-β and RANTES expression and IRF3 DNA-binding activity are ablated. Three-month-old Tbk1(Δ/Δ) mice exhibit mononuclear and granulomatous cell infiltrates in multiple organs and inflammatory cell infiltrates in their skin, and they harbor a 2-fold greater amount of circulating monocytes than their Tbk1(+/+) and Tbk1(+/Δ) littermates. Skin from 2-week-old Tbk1(Δ/Δ) mice is characterized by reactive changes, including hyperkeratosis, hyperplasia, necrosis, inflammatory cell infiltrates, and edema. In response to LPS challenge, 3-month-old Tbk1(Δ/Δ) mice die more quickly and in greater numbers than their Tbk1(+/+) and Tbk1(+/Δ) counterparts. This lethality is accompanied by an overproduction of several proinflammatory cytokines in the serum of Tbk1(Δ/Δ) mice, including TNF-α, GM-CSF, IL-6, and KC. This overproduction of serum cytokines in Tbk1(Δ/Δ) mice following LPS challenge and their increased susceptibility to LPS-induced lethality may result from the reactions of their larger circulating monocyte compartment and their greater numbers of extravasated immune cells.

Assessing agonistic potential of a candidate therapeutic anti-IL21R antibody

Background

Selective neutralization of the IL21/IL21R signaling pathway is a promising approach for the treatment of a variety of autoimmune diseases. Ab-01 is a human neutralizing anti-IL21R antibody. In order to ensure that the activities of Ab-01 are restricted to neutralization even under in vitro cross-linking and in vivo conditions, a comprehensive assessment of agonistic potential of Ab-01 was undertaken.

Methods

In vitro antibody cross-linking and cell culture protocols reported for studies with a human agonistic antibody, TGN1412, were followed for Ab-01. rhIL21, the agonist ligand of the targeted receptor, and cross-linked anti-CD28 were used as positive controls for signal transduction. In vivo agonistic potential of Ab-01 was assessed by measuring expression levels of cytokine storm-associated and IL21 pathway genes in blood of cynomolgus monkeys before and after IV administration of Ab-01.

Results

Using a comprehensive set of assays that detected multiple activation signals in the presence of the positive control agonists, in vitro Ab-01-dependent activation was not detected in either PBMCs or the rhIL21-responsive cell line Daudi. Furthermore, no difference in gene expression levels was detected in blood before and after in vivo Ab-01 dosing of cynomolgus monkeys.

Conclusions

Despite efforts to intentionally force an agonistic signal from Ab-01, none could be detected.

In vitro investigation of biomechanical changes of the hip after Salter pelvic osteotomy

BACKGROUND

Salter innominate osteotomy of the pelvis is widely used to improve the coverage of the femoral head in developmental dysplasia of the hip, but the biomechanical and geometric changes after this osteotomy are not well understood.

METHODS

A CT dataset of an 8-year-old child with severe dysplasia of both hips was used to create a polyamide model of the left hemipelvis and proximal femur. The hemipelvis was mounted to a holding device and the proximal femur attached to a sensor guided industrial robot. The robot was programmed to apply joint forces and torques based on single-leg stance. Two major muscles were represented by wires connected to hydraulic cylinders; muscle forces were adjusted to balance the joint moments. Resulting joint forces were measured using a pressure measuring sensor before and after Salter osteotomy of the hip. Geometric changes were recorded using a three-dimensional ultrasound measurement system.

FINDINGS

The preoperative hip joint resultant force was 583N (270% body weight), while after the operation a mean force of 266N (120% body weight) was measured. Postoperative muscle forces were roughly half the preoperative values. The hip joint was translated medially and caudally. Postoperatively, the length of gluteus medius and maximus muscles increased.

INTERPRETATION

The preoperative value of the resultant hip joint force is comparable to values reported in the literature. The results suggest that Salter innominate osteotomy leads to a reduction of hip joint and muscle forces in addition to increasing joint contact area.

[Early evaluation of neurological prognosis and therapy after cardiopulmonary resuscitation: current opportunities and clinical implications]

The developments of cardiopulmonary resuscitation and intensive care medicine have made possible survival after cardiac arrest. However, only 10-30% of patients with initially successful resuscitation later reach a state without severe neurological impairment. Ethical and socioeconomic reasons therefore make early prognosis important for certain patients. There are no reliable parameters for predictions of good clinical outcome. If clinical information is consistent with severe hypoxic brain damage, cortical somatosensory evoked potentials are absent, and neuron-specific enolase values exceed 33-65 microg/l, recovery of consciousness can be excluded. The same result can be predicted if brain imaging shows severe hypoxemic changes or if a myoclonic status occurs on the first day. In summary, the prognosis in patients with cerebral anoxy and cardiopulmonary resuscitation remains poor. Treatment with hypothermia for 24 h is recommended.

Long-QT-Syndrom als Differenzialdiagnose einer Grand-Mal-Epilepsie

A 24-year-old female with a history of epileptic seizures was admitted after prolonged cardiac resuscitation. The clinical course together with additional examinations led to the diagnosis of severe hypoxic cerebral damage, with poor prognosis for neurological outcome. In her initial ECG, as in the ECGs of several family members, QT prolongation was diagnosed. Meticulous history taking and ensuing genetic analysis led to the diagnosis of familial long QT syndrome (LQTS) with a mutation in the LQT-2 gene (HERG). In retrospect, the previous seizure episodes have to be considered cardiac syncopes. Two family members had previously died suddenly, and ECG and genetic analysis revealed that a total of eight family members were affected. These relatives were prophylactically treated with beta blockers or supplied with automated implantable cardioverter defibrillating devices. The literature concerning LQTS, diagnosis and prognosis of cerebral hypoxic damage, and differentiation between seizures and cardiac syncopes is discussed.

Visusverlust und akutes Nierenversagen bei einer 28-jährigen aktiven Reiterin

A 28-year old active sportswoman was admitted to hospital suffering from fever, menigeal irritation, acute myopia and progressive acute renal failure. Showing signs of polyserositis in combination with pulmonary granulomatous changes a collagenosis as well as an atypical pneumonia was excluded first. Due to the renal loss of function a renal biopsy was taken with the typical histological result of a hantavirus infection. This could be confirmed serologically in the following. With symptomatic treatment the patient had an uneventful complete recovery during the next four weeks.

[Standardization of invasive neuromodulatory procedures]

The Working Group on Neuromodulation of the German Association for the Study of Pain, composed of representatives from various scientific specialty societies, met on December 9, 2000, March 24, 2001, October 5, 2001, and December 8, 2001. As a result of these discussions grounded in current knowledge, the following guidelines were formulated for the standardization of invasive techniques of neuromodulation intended to serve as a systematic aid in decision-making and to provide recommendations for practice-oriented methods. The guidelines were based on both the clinical and practical experience of the group participants (see information box on the next page) as well as on the current scientific literature and guidance from the consensus report of the European Federation of IASP Chapters (EFIC) [23]. The guidelines serve the purpose of orientation and have no effect on either assumption of liability or discharge from liability. The guidelines were conceived for use by physicians in private practice,doctors in hospitals,and nonmedical personnel concerned with the care of chronic pain patients. The Working Group consists of unsalaried volunteers. The participants received no honorarium and were only reimbursed for normal travel expenses in accordance with customary directives. The guidelines will be revised should new scientific results become available, at the latest in 2 years. The plan exists to further develop the guidelines to stages II and III (AWMF). The Steering Committee of the DGSS appraised the guidelines and authorized the guidelines before publication.

[Rhabdomyolysis as a rare complication of theophylline poisoning]

CASE REPORT

A case of a 73-year-old male with theophylline overdose complicated by rhabdomyolysis is reported. After uncontrolled self-medication with an unknown number of theophylline slow release 350 mg tablets and furosemide 40 mg tablets he was admitted with unspecific clinical signs like tachyarrhythmia, vomiting and restlessness. Maximum theophylline concentration was 66.5 mg/l, other abnormal laboratory findings included hypokalemia (2.8 mmol/l) and hyponatremia (123 mmol/l). The maximum creatinkinase level was measured after admission (32.29 mumol/s/l) accompanied by a serum myoglobin level of 3,789 micrograms/l. Immediate treatment with oral activated charcoal and continuous veno-venous hemodialysis (CVVH) was instituted, together with intravenous potassium and sodium chloride substitution, forced diuresis and continuous administration of intravenous metoprolol. The theophylline, creatinkinase and myoglobin levels decreased rapidly and there was no second rise in theophylline found. The patient survived without sequelae.

CONCLUSION

Rhabdomyolysis is a rare complication of theophylline intoxication. In literature only a small number of cases are reported. Our results illustrate the necessity of a purposeful and fast management to successfully prevent renal failure or death. Some pathogenetic mechanisms of theophylline-induced rhabdomyolysis, epidemiologic data, risk factors and therapeutical principles will be demonstrated by a detailed literature survey.

Effect of intravenous magnesium on ventricular tachyarrhythmias associated with acute myocardial infarction

Ventricular ectopy and left ventricular dysfunction are important predictive factors for an unfavourable outcome following an acute myocardial infarction (MI). Tachyarrhythmias are a major cause of death subsequent to MI. Magnesium was postulated to have an antiarrhythmic effect after MI. Therefore we have investigated the influence of intravenous and oral magnesium (Mg) therapy on ventricular tachyarrhythmias. 67 patients with myocardial infarction (MI) diagnosed according to the WHO criteria of anamnesis, infarct-specific electrocardiogram (ECG), and enzymatic status were included in a prospective study. 23 patients (group 1) received 2 g Mg per day (= 82 mmol Mg/24 h) intravenously for the first 3 days followed by oral magnesium adipate administration of 3 x 2 coated tablets of magnesium 50 Apogepha (= 300 mg Mg/24 h or 12.34 mmol Mg/24 h, respectively) for the full duration of the study. 26 patients (group 2) received only i.v. magnesium for the first 3 days after admission (2 g Mg/24 h). The results of this treatment were compared to those of a control group of 18 MI patients without magnesium administration. All groups were identical with regard to other forms of treatment. The magnesium levels in serum and erythrocytes of all patients were measured at the following time points: days 0 (admission time), 1, 2, the day of discharge (about day 20) and after 12 weeks. The tachyarrhythmias were monitored by 24-h-continuous-electrocardiography on days 0, 1 and on the day before discharge (about day 20). The serum magnesium levels rose significantly during i.v. Mg-administration (1 and 2 day) but decreased in group 2 subsequently until the time of discharge from hospital. In contrast group 1 patients receiving oral as well as intravenous magnesium did not show this drop. The uptake of magnesium into the erythrocytes was less obvious. The erythrocyte magnesium concentration of the control group remained significantly low in serum and red blood cells. Significantly less ventricular premature beats and runs (< 5 ventricular premature beats and > 5 ventricular premature beats) compared to admission day were observed in both treated groups. These data suggest that the frequency of ventricular tachyarrhythmias is reduced by administration of intravenous magnesium and support an early high dose administration of intravenous magnesium in the wake of myocardial infarction.

[Coronary angiography and change in antioxidative status]

PATIENTS AND METHODS

In a prospective study in 53 patients with stable angina pectoris symptoms the antioxidant status (glutathione peroxidase, glutathione, superoxid dismutase, malondialdehyde and selenium in serum and whole blood) was determined before and 4 to 6 hours after coronary angiography. According to the results of the coronary angiography the patients were classified in a group with "severe" (n = 16) and another with "moderate" coronary alterations.

RESULTS

In both groups there was a significant reduction of selenium in serum and whole blood. The enzymes glutathione peroxidase and superoxide dismutase as well as glutathione and malondialdehyde changed only slightly.

CONCLUSION

These results can be the cause of an increase of the formation of free radicals during coronary reperfusion (PTCA, implantation of stents in the group with "severe" coronary alterations) but could also be seen as a sign of formation of radicals by the method itself (in patients with "moderate" coronary alterations). Further investigations are indicated. Furthermore the amelioration of the antioxidant status of the organism by scavenger substances (vitamins A, B, C and selenium) should be discussed.

[Serum level-adjusted dosage of once-daily aminoglycoside therapy in critical illness: results of a prospective study]

OBJECTIVE

In critically ill patients, the adjustment of target peak and trough levels of tobramycin was investigated because aminoglycoside pharmacokinetics can be changed by multiple influences. Sufficient but not too high peak serum concentrations and low trough levels, however, should be achieved to ensure a therapeutic effect and to minimize toxicity.

METHODS

70 critically ill patients of 51 +/- 18 years were monitored daily during their aminoglycoside treatment on the intensive care unit targeting a peak of about 12 micrograms/ml 30 minutes after infusion and a trough level below 1 to 2 micrograms/ml. Dose recommendations were given daily, taking into consideration serum levels, dose predictions (Bayesian method, ABBOTTBASE), creatinine clearance and clinical findings. Creatinine clearance was estimated according to the Cockcroft-Gault-formula as well as directly by the urine collection method.

RESULTS

The standardized initial dose of 400 mg tobramycin led to average peak serum levels of 14.2 +/- 3.9 micrograms/ml in the patients with an apparent distribution volume of 0.345 +/- 0.074 L/kg. In 95% of the patients, the initial peak was higher than 8.5 micrograms/ml; levels higher than 20 micrograms/ml were observed in 7%, extremely low concentrations (below 5 micrograms/ml) in 2%. With individually adjusted doses between 160 and 560 mg, a mean peak of 11.5 +/- 2.7 micrograms/ml was measured subsequently. The levels amounted to 96 +/- 23% of the predicted values, deviations greater than 50% occurred in 5%. The target trough level was achieved in 99%, in less than 3% the dosing interval was extended up to 72 hours. A tobramycin clearance below 80 ml/min/1.73 m2 was associated with average 80% and 33% higher creatinine clearance values according to the Cockcroft-method and the direct method, respectively.

CONCLUSION

Target peak and trough aminoglycoside levels are adjustable even in critically ill patients. Reduced tobramycin clearance can be associated with normal creatinine clearance. Assuming an exact methodology, a reduced "direct" creatinine clearance, however, indicates a reduced drug clearance.

Representation in natural and artificial agents: an embodied cognitive science perspective

The goal of the present paper is to provide an embodied cognitive science view on representation. Using the fundamental task of category learning, we will demonstrate that this perspective enables us to shed new light on many pertinent issues and opens up new prospects for investigation. The main focus of this paper is on the prerequisites to acquire representations of objects in the real world. We suggest that the main prerequisite is embodiment which allows an agent--human, animal or robot--to manipulate its sensory input such that invariances are generated. These invariances, in turn, are the basis of representation formation. In other words, the paper does not focus on representations per se, but rather discusses the various processes involved in order to make learning and representation acquisition possible. The argument structure is as follows. First we introduce two new perspectives on representation, namely frame-of-reference, and complete agent. Then we elaborate the complete agent perspective and focus in particular on embodiment and situatedness. We argue that embodiment has two main aspects, a dynamic and an information theoretic one. Focusing on the latter, there are a number of implications: Representation can only be understood if the embedding of the neural substrate in the physical agent is known, which includes morphology (shape), positioning and nature of sensors. Because an autonomous mobile agent in the real world is exposed to a continuously changing high-dimensional stream of sensory stimulation, if it is to learn category distinctions, it first needs a focus of attention mechanism, and then it must have a way to reduce the dimensionality of this high-dimensional sensory stream. Learning is very hard because the invariances are typically not found in the sensory data directly--the classical problem of object constancy: it is a so-called type 2 problem. Rather than trying to improve the learning algorithms--which is the standard approach--the embodied cognitive science view suggests a different approach which focuses on the nature of the data: the agent is not passively exposed to a given data distribution, but, by exploiting its body and through the interaction with the environment, it can actually generate the data. More specifically, it can generate correlated data that has the property that it can be easily learned. This learnability is due to redundancies resulting from the appropriate interactions with the environment. Through such interactions, the former type 2 problem is transformed into a type 1 problem, thus reducing the complexity of the learning task by orders of magnitude. By observing the frame-of-reference problem we will discuss to what extent these invariances are reflected--represented--in the "neural substrate", i.e. the internal mechanisms of the agent. It is concluded, that representation is not a concept that can be studied in the abstract, but should be elaborated in the context of concrete agent-environment interactions. These ideas are all illustrated with examples of natural agents and artificial agents. In particular, we will present a suite of experiments on simulated and real-world artificial agents instantiating the main arguments.

The evaluation of fee for service and managed care from the viewpoint of people with disabilities in the USA

In the literature on managed health care there is little presented from the viewpoint of people with disabilities, but this study looks at what is found. Using a sample of 258 persons with disabilities in Massachusetts obtained through a mail survey, no statistically significant differences between the two groups (fee for service or managed care) on a series of relevant variables was found. An evaluation of their health insurance and their primary care physician was asked for and several regression models of the relevant variables related to these two evaluations were tested. It seems that accessibility of the primary care physicians's office and the physician's level of understanding of the person's disability are related in a statistically significant way to their rating of their health insurance. Also it appears that the ease of obtaining an appointment and the physician's level of understanding of the person's disability are related in a statistically significant way to the evaluation of their primary care physician. The major policy implication of these findings is that managed care may not be the disaster which many foresee it to be.