Machine learning approach to identify malaria risk in travelers using real-world evidence

Background

Pre-travel consultation and chemoprophylaxis measures for malaria are a key component in the prevention of imported malaria in travelers. In this study we report a predictive tool for assessing personalized malaria risk in travelers based on the analysis of electronic medical records from travel consultations. The tool aims to guide physicians in the recommendation of appropriate prophylaxis prior to their trip. We also provide best-practice recommendations for pre-processing noisy and highly sparse real world evidence data.

Methods

We leveraged a large EMR dataset, containing demographic information about travelers and their destination. The data has been previously preprocessed using various strategies to handle missing and unbalanced data. We compared multiple machine learning approaches to assess the risk of malaria acquisition in travelers during their travels. Additionally, a feature importance analysis was performed using SHAP (SHapley Additive Explanations) values to identify patterns associated with malaria risk.

Results

Our study revealed that our XGB models achieved high predictive capacity (AUC >0.80). The most significant features predicting malaria infection during travel included travel destinations with low malaria risk, vaccination history, number of countries visited, age, and trip duration. Remarkably, we were able to obtain a reduced model with only five features. When comparing this model with a population of travelers recommended for malaria chemoprophylaxis, we observed that it was deemed necessary in only 40% of these travelers. This suggests that 60% received chemoprophylaxis despite having a low personalized risk of malaria.

Conclusion

We have developed an algorithmic tool that utilizes a concise survey to generate a personalized travel risk assessment, effectively minimizing the prescription of unnecessary malaria chemoprophylaxis. Through the identification of patterns linked to predictions, our model significantly enhances the efficacy of pre-travel consultations.

MALrisk: a machne-learning based tool to predict imported malaria in returned travellers with fever

BACKGROUND

Early diagnosis is key to reducing the morbi-mortality associated with P. falciparum malaria among international travellers. However, access to microbiological tests can be challenging for some healthcare settings. Artificial Intelligence could improve the management of febrile travellers.

METHODS

Data from a multicentric prospective study of febrile travellers was obtained to build a machine-learning model to predict malaria cases among travellers presenting with fever. Demographic characteristics, clinical and laboratory variables were leveraged as features. Eleven machine-learning classification models were evaluated by 50-fold cross-validation in a Training set. Then, the model with the best performance, defined by the Area Under the Curve (AUC), was chosen for parameter optimization and evaluation in the Test set. Finally, a reduced model was elaborated with those features that contributed most to the model.

RESULTS

Out of eleven machine-learning models, XGBoost presented the best performance (mean AUC of 0.98 and a mean F1 score of 0.78). A reduced model (MALrisk) was developed using only six features: Africa as a travel destination, platelet count, rash, respiratory symptoms, hyperbilirubinemia and chemoprophylaxis intake. MALrisk predicted malaria cases with 100% (95%CI 96-100) sensitivity and 72% (95%CI 68-75) specificity.

CONCLUSIONS

The MALrisk can aid in the timely identification of malaria in non-endemic settings, allowing the initiation of empiric antimalarials and reinforcing the need for urgent transfer in healthcare facilities with no access to malaria diagnostic tests. This resource could be easily scalable to a digital application and could reduce the morbidity associated with late diagnosis.

Sociodemographic, lifestyle, and environmental determinants of vitamin D levels in pregnant women in Spain

INTRODUCTION

Vitamin D deficiency (<20 ng/mL circulating levels) is a worldwide public health concern and pregnant women are especially vulnerable, affecting the health of the mother and the fetus. This study aims to evaluate the sociodemographic, lifestyle, and environmental determinants associated with circulating vitamin D levels in Spanish pregnant women.

METHODS

We used data from the Spanish INMA ("Infancia y Medio Ambiente") prospective birth cohort study from the regions of Gipuzkoa, Sabadell, and Valencia. 25-hydroxyvitamin D3 (25(OH)D3) was measured in plasma collected in the first trimester of pregnancy. Information on 108 determinants was gathered: 13 sociodemographic, 48 lifestyle including diet, smoking and physical activity, and 47 environmental variables, representing the urban and the chemical exposome. Association of the determinants with maternal 25(OH)D3 levels was estimated in single- and multiple-exposure models. Machine learning techniques were used to predict 25(OH)D3 levels below sufficiency (30 ng/mL).

RESULTS

The prevalence of < 30 ng/mL 25(OH)D3 levels was 51 %. In the single-exposure analysis, older age, higher socioeconomic status, taking vitamin D, B12 and other sup*plementation, and higher humidity, atmospheric pressure and UV rays were associated with higher levels of 25(OH)D3 (IQR increase of age: 1.2 [95 % CI: 0.6, 1.8] ng/mL 25(OH)D3). In the multiple-exposures model, most of these associations remained and others were revealed. Higher body mass index, PM2.5 and high deprivation area were associated with lower 25(OH)D3 levels (i.e., Quartile 4 of PM2.5 vs Q1: -3.6 [95 % CI: -5.6, -1.5] ng/mL of 25(OH)D3). History of allergy and asthma, being multiparous, intake of vegetable fat, vitamin B6, alcohol consumption and molybdenum were associated with higher levels. The machine learning classification model confirmed some of these associations.

CONCLUSIONS

This comprehensive study shows that younger age, higher body mass index, higher deprived areas, higher air pollution and lower UV rays and humidity are associated with lower 25(OH)D3 levels.

Long term outcomes of robotic-assisted abdominal wall reconstruction: a single surgeon experience

INTRODUCTION

Robotic abdominal wall reconstruction (RAWR) is one of the most significant advances in the management of complex abdominal wall hernias. The objective of this study was to evaluate long term outcomes in a cohort of patients that underwent complex RAWR in a single center.

METHODS

This was a longitudinal retrospective review of a cohort of 56 patients who underwent complex RAWR at least 24 months prior by a single surgeon at a tertiary care institution. All patients underwent bilateral retro-rectus release (rRRR) with or without robotic transversus abdominis release (rTAR). Data collected include demographics, hernia details, operative and technical details. The prospective analysis included a post-procedure visit of at least 24 months from the index procedure with a physical examination and quality of life survey using the Carolinas Comfort Scale (CCS). Patients with reported symptoms concerning for hernia recurrence underwent radiographic imaging. Descriptive statistics (mean ± standard deviation or median) were calculated for continuous variables. Chi-square or Fisher's exact test as deemed appropriate for categorical variables, and analysis of variance or the Kruskal-Wallis test for continuous data, were performed among the separate operative groups. A total score for the CCS was calculated and analyzed in accordance with the user guidelines.

RESULTS

One-hundred and-forty patients met the inclusion criteria. Fifty-six patients consented to participate in the study. Mean age was 60.2 years. Mean BMI was 34.0. Ninety percent of patients had at least one comorbidity and 52% of patients were scored ASA 3 or higher. Fifty-nine percent were initial incisional hernias, 19.6% were recurrent incisional hernias and 8.9% were recurrent ventral hernias. The mean defect width was 9 cm for rTAR and 5 cm for rRRR. The mean implanted mesh size was 945.0 cm² for rTAR and 362.5 cm² for rRRR. The mean length of follow-up was 28.1 months. Fifty-seven percent of patients underwent post-op imaging at an average follow-up of 23.5 months. Recurrence rate was 3.6% for all groups. There were no recurrences in patients that underwent solely bilateral rRRR. Two patients (7.7%) that underwent rTAR procedures were found with recurrence. Average time to recurrence was 23 months. Quality of life survey demonstrated an overall CCS score of 6.63 ± 13.95 at 24 months with 12 (21.4%) patients reporting mesh sensation, 20 (35.7%) reporting pain, and 13 (23.2%) reporting movement limitation.

CONCLUSION

Our study contributes to the paucity of literature describing long term outcomes of RAWR. Robotic techniques offer durable repairs with acceptable quality of life metrics.

Strong off-target antibody reactivity to malarial antigens induced by RTS,S/AS01E vaccination is associated with protection

The RTS,S/AS01E vaccine targets the circumsporozoite protein (CSP) of the Plasmodium falciparum (P. falciparum) parasite. Protein microarrays were used to measure levels of IgG against 1000 P. falciparum antigens in 2138 infants (age 6–12 weeks) and children (age 5–17 months) from 6 African sites of the phase III trial, sampled before and at 4 longitudinal visits after vaccination. One month postvaccination, IgG responses to 17% of all probed antigens showed differences between RTS,S/AS01E and comparator vaccination groups, whereas no prevaccination differences were found. A small subset of antigens presented IgG levels reaching 4- to 8-fold increases in the RTS,S/AS01E group, comparable in magnitude to anti-CSP IgG levels (~11-fold increase). They were strongly cross-correlated and correlated with anti-CSP levels, waning similarly over time and reincreasing with the booster dose. Such an intriguing phenomenon may be due to cross-reactivity of anti-CSP antibodies with these antigens. RTS,S/AS01E vaccinees with strong off-target IgG responses had an estimated lower clinical malaria incidence after adjusting for age group, site, and postvaccination anti-CSP levels. RTS,S/AS01E-induced IgG may bind strongly not only to CSP, but also to unrelated malaria antigens, and this seems to either confer, or at least be a marker of, increased protection from clinical malaria.

Projection to Latent Spaces Disentangles Pathological Effects on Brain Morphology in the Asymptomatic Phase of Alzheimer's Disease

Alzheimer's disease (AD) continuum is defined as a cascade of several neuropathological processes that can be measured using biomarkers, such as cerebrospinal fluid (CSF) levels of Aβ, p-tau, and t-tau. In parallel, brain anatomy can be characterized through imaging techniques, such as magnetic resonance imaging (MRI). In this work we relate both sets of measurements and seek associations between biomarkers and the brain structure that can be indicative of AD progression. The goal is to uncover underlying multivariate effects of AD pathology on regional brain morphological information. For this purpose, we used the projection to latent structures (PLS) method. Using PLS, we found a low dimensional latent space that best describes the covariance between both sets of measurements on the same subjects. Possible confounder effects (age and sex) on brain morphology are included in the model and regressed out using an orthogonal PLS model. We looked for statistically significant correlations between brain morphology and CSF biomarkers that explain part of the volumetric variance at each region-of-interest (ROI). Furthermore, we used a clustering technique to discover a small set of CSF-related patterns describing the AD continuum. We applied this technique to the study of subjects in the whole AD continuum, from the pre-clinical asymptomatic stages all the way through to the symptomatic groups. Subsequent analyses involved splitting the course of the disease into diagnostic categories: cognitively unimpaired subjects (CU), mild cognitively impaired subjects (MCI), and subjects with dementia (AD-dementia), where all symptoms were due to AD.

Abstract 28: Identification of multisite real-world patient cohorts to enable immunotherapy utilization and safety assessment

Currently, five classes of Immunotherapy (IT) agents are available for over 20 cancer types, including a powerful new class utilizing T cells genetically engineered to express a chimeric antigen receptor (CAR-T). Additional classes include bi-specific T-cell engagers (BiTEs), immune checkpoint inhibitors (ICIs), cancer vaccines, and oncolytic viruses. Despite promising antitumor activity, significant immune-related adverse events (irAE) have been reported. The most common CAR-T toxicity is cytokine release syndrome (CRS), and management typically includes supportive care and immunosuppression with corticosteroids or the IL-6 inhibitor tocilizumab. Documented CRS and tocilizumab use outside of CAR-T is rare, but recent evidence suggests that tocilizumab is emerging for management of other steroid-refractory irAE. Given the rapid evolution of this field, there remains a need to understand the utilization of IT and the pathophysiology of irAE in real-world settings. To identify cohorts of interest, a retrospective, multicenter review was conducted using Health Catalyst’s extended real-world data database, Touchstone, which includes &gt;300 sources of data and over 70 multipayer and geographically diverse provider clients. Cohorts were selected from representative provider networks, including large and specialty academic medical centers (AMCs), integrated delivery networks, accountable care organizations, and community hospitals in the US. A total of 10 clients’ de-identified electronic medical records were searched for presence of cancer-associated diagnosis codes. The cohort was then restricted by the presence of medication order or administration of any IT-class drug, and among these, first administration of tocilizumab within 21 days. Across ten provider networks containing data for ~5.6 million cancer patients, 9,029 patients were identified: CAR-T, 116 patients (0-102); BiTEs, 112 patients (0-64); ICIs, 8,402 patients (0-4520); cancer vaccines, 182 patients (0-143); and oncolytic viruses, 217 patients (0-214). As expected, CAR-T administration was limited to approved treatment centers. Among the other classes, an average of 26% of identified patients were from the community setting. Additionally, of the 116 patients receiving CAR-T therapy, 75 patients (64.7%) were administered tocilizumab within 21 days. Evidence of tocilizumab use outside of CAR-T irAE was also identified, occurring in 21 patients (0.3%) receiving another class of IT within AMCs, and did not occur at other provider types. Together this analysis identified several real-world IT patient cohorts comprising diverse populations from a range of provider types, with corresponding access to rich patient-level clinical, molecular, and financial real-world data (RWD) elements. Immediate downstream applications will involve developing integrated methods for the real-time identification of patients who may be at risk for adverse events and standardization of toxicity management guidelines.

Citation Format: Catherine Del Vecchio Fitz, Elizabeth Eldridge, Alyssa Antonopoulos, Paula Petrone, Will Caldwell, Ed Corbett, Amy Flaster, Holly Rimmasch, Adem Albayrak, Dale Sanders, Sadiqa Mahmood, Elia Stupka. Identification of multisite real-world patient cohorts to enable immunotherapy utilization and safety assessment [abstract]. In: Proceedings of the AACR Special Conference on Advancing Precision Medicine Drug Development: Incorporation of Real-World Data and Other Novel Strategies; Jan 9-12, 2020; San Diego, CA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(12_Suppl_1):Abstract nr 28.

Shared Latent Structures Between Imaging Features and Biomarkers in Early Stages of Alzheimer's Disease: A Predictive Study

Magnetic resonance imaging (MRI) provides high resolution brain morphological information and is used as a biomarker in neurodegenerative diseases. Population studies of brain morphology often seek to identify pathological structural changes related to different diagnostic categories (e.g.: controls, mild cognitive impairment or dementia) which normally describe highly heterogeneous groups with a single categorical variable. Instead, multiple biomarkers are used as a proxy for pathology and are more powerful in capturing structural variability. Hence, using the joint modeling of brain morphology and biomarkers, we aim at describing structural changes related to any brain condition by means of few underlying processes. In this regard, we use a multivariate approach based on Projection to Latent Structures in its regression variant (PLSR) to study structural changes related to aging and AD pathology. MRI volumetric and cortical thickness measurements are used for brain morphology and cerebrospinal fluid (CSF) biomarkers (t-tau, p-tau and amyloid-beta) are used as a proxy for AD pathology. By relating both sets of measurements, PLSR finds a low-dimensional latent space describing AD pathological effects on brain structure. The proposed framework allows us to separately model aging effects on brain morphology as a confounder variable orthogonal to the pathological effect. The predictive power of the associated latent spaces (i.e., the capacity of predicting biomarker values) is assessed in a cross-validation framework.

Therapeutic strategies in the treatment of Menière's disease: the Italian experience

PURPOSE

Ménière's disease (MD) is an inner ear disorder of unknown etiology, whose pathological substrate is the endolymphatic hydrops. Different treatments have been proposed; however, evidence of their effectiveness is lacking. The aim of this study was to evaluate by a questionnaire which medical and surgical treatments are used in Italy for the treatment of MD and to compare them with those proposed in other countries.

METHODS

An electronic questionnaire of 40 questions was formulated and sent to Italian otolaryngologist (ENT) divided into two groups: Group 1 ("generalists" 60.8%) and Group 2 ("neurotologist- NO" 39.2%).

RESULTS

One hundred and twenty five ENT replied. Treatment of the acute phase, apart from symptomatics, was based on diuretics that are prescribed by 83.5% of respondents, steroids, prescribed by 66.7%, and vasodilators, prescribed by 22%. In the intercritical phase, 87.2% of respondents recommended low-salt diet, 78.4% of respondents prescribed betahistine, and 52.8% diuretics. Statistical analysis did not show correlation neither with the declared specialization nor with the number of patients treated. In case of failure of medical treatment, IT gentamicin was suggested by 48.8% of the respondents and IT steroids by 40.8%. Statistical analysis showed that generalists prefer IT steroids and NO IT gentamicin (p 0.019). In case of failure of both medical treatment and IT treatment, vestibular neurectomy was indicated by 58.4% of the respondents, 6.4% indicated endolymphatic sac surgery, and 2.4% surgical labyrinthectomy.

CONCLUSION

In Italy, the treatment of MD stand on a gradual approach that starts from the dietary-behavioral changes and a pharmacological therapy based on betahistine. In refractory cases, IT treatment initially with steroids and, therefore, with gentamicin allows the control in vertigo in the majority of cases. In case of failure of IT treatment, VNS is the surgery of choice.

Multiplex immunohistochemistry accurately defines the immune context of metastatic melanoma

A prospective study explored the heterogeneous nature of metastatic melanoma using Multiplex immunohistochemistry (IHC) and flow cytometry (FACS). Multiplex IHC data quantitated immune subset number present intra-tumoral (IT) vs the tumor stroma, plus distance of immune subsets from the tumor margin (TM). In addition, mIHC showed a close association between the presence of IT CD8⁺ T cells and PDL1 expression in melanoma, which was more prevalent on macrophages than on melanoma cells. In contrast, FACS provided more detailed information regarding the T cell subset differentiation, their activation status and expression of immune checkpoint molecules. Interestingly, mIHC detected significantly higher Treg numbers than FACS and showed preferential CD4⁺ T cell distribution in the tumor stroma. Based on the mIHC and FACS data, we provide a model which defines metastatic melanoma immune context into four categories using the presence or absence of PDL1⁺ melanoma cells and/or macrophages, and their location within the tumor or on the periphery, combined with the presence or absence of IT CD8⁺ T cells. This model interprets melanoma immune context as a spectrum of tumor escape from immune control, and provides a snapshot upon which interpretation of checkpoint blockade inhibitor (CBI) therapy responses can be built.

HtrA1 activation is driven by an allosteric mechanism of inter-monomer communication

The human protease family HtrA is responsible for preventing protein misfolding and mislocalization, and a key player in several cellular processes. Among these, HtrA1 is implicated in several cancers, cerebrovascular disease and age-related macular degeneration. Currently, HtrA1 activation is not fully characterized and relevant for drug-targeting this protease. Our work provides a mechanistic step-by-step description of HtrA1 activation and regulation. We report that the HtrA1 trimer is regulated by an allosteric mechanism by which monomers relay the activation signal to each other, in a PDZ-domain independent fashion. Notably, we show that inhibitor binding is precluded if HtrA1 monomers cannot communicate with each other. Our study establishes how HtrA1 trimerization plays a fundamental role in proteolytic activity. Moreover, it offers a structural explanation for HtrA1-defective pathologies as well as mechanistic insights into the degradation of complex extracellular fibrils such as tubulin, amyloid beta and tau that belong to the repertoire of HtrA1.

Penetrating cardiac injuries: predictive model for outcomes based on 2016 patients from the National Trauma Data Bank

BACKGROUND

Penetrating cardiac injuries are uncommon and lethal. The objectives of this study are to examine the national profile of cardiac injuries, identify independent predictors of outcome, generate, compare and validate previous predictive models for outcomes. We hypothesized that National Trauma Data Bank (NTDB) given its large number of patients, would validate these models.

METHODS

The NTDB was queried for data on cardiac injuries, using survival as the main outcome measure. Statistical analysis was performed utilizing univariate and stepwise logistic regression. The stepwise logistic regression model was then compared with other predictive models of outcome.

RESULTS

There were 2016 patients with penetrating cardiac injuries identified from 1,310,720 patients. Incidence: 0.16%. Mechanism of injury: GSWs-1264 (63%), SWs-716 (36%), Shotgun/impalement-19/16 (1%). Mean RTS 1.75, mean ISS 27 ± 23. Overall survival 675 (33%). 830 patients (41%) underwent ED thoracotomy, 47 survived (6%). Survival stratified by mechanism: GSWs 114/1264 (10%), SWs 564/717 (76%). Predictors of outcome for mortality-univariate analysis: vital signs, RTS, ISS, GCS: Field CPR, ED intubation, ED thoracotomy and aortic cross-clamping (p < 0.001). Stepwise logistic regression identified cardiac GSW's (p < 0.001; AOR 26.85; 95% CI 17.21-41.89), field CPR (p = 0.003; AOR 3.65; 95% CI 1.53-8.69), the absence of spontaneous ventilation (p = 0.008; AOR 1.08, 95% CI 1.02-1.14), the presence of an associated abdominal GSW (p = 0.009; AOR 2.58, 95% CI 1.26-5.26) need for ED airway (p = 0.0003 AOR 1386.30; 95% CI 126.0-15251.71) and aortic cross-clamping (p = 0.0003 AOR 0.18; 95% CI 0.11-0.28) as independent predictors for mortality. Overall predictive power of model-93%.

CONCLUSION

Predictors of outcome were identified. Overall survival rates are lower than prospective studies report. Predictive model from NTDB generated larger number of strong independent predictors of outcomes, correlated and validated previous predictive models.

Predictors of outcome in 101 patients requiring emergent thoracotomy for penetrating pulmonary injuries

BACKGROUND

Operative interventions are uncommonly required for penetrating pulmonary injuries. Similarly, because their incidence is low, few series appear sporadically in the literature. Objectives of this study are to identify predictors of outcome for patients requiring emergent thoracotomy for penetrating pulmonary injuries and evaluate the use of tissue sparing versus resective techniques for their management.

STUDY DESIGN

This is a retrospective 169-month study of all patients with penetrating pulmonary injuries requiring thoracotomy. The main outcome measures are: physiologic parameters, AAST-OIS injury grade, surgical procedures and mortality. Statistical analysis includes univariate and stepwise logistic regression.

RESULTS

101 patients required thoracotomy for penetrating pulmonary injuries. Mechanism of injury includes: gunshot wounds (GSW)-73 (72%), stab wounds (SW)-28 (33%). Mean systolic BP 97 ± 47, mean HR 92 ± 47, and mean admission pH 7.22 ± 0.17. Mean RTS 6.25 ± 2.7, mean ISS 36 ± 22. The mean estimated blood loss (EBL) was 5277 ± 4955 mls. Predictors of outcome are: admission pH (p = 0.0014), admission base deficit (p < 0.0001), packed red blood cells (PRBCs) transfused (p = 0.023), whole blood transfused (p < 0.01). A total of 143 procedures were required in 101 patients: tissue sparing 114 (80%) versus resective procedures 29 (20%). Only pneumonectomy (p = 0.024) predicted outcome. Overall survival 64/101-64%. American Association for the Surgery of Trauma-Organ Injury Scale (AAST-OIS) injury grades I-III versus IV-VI predicts survival (p < 0.001). Stepwise logistic regression identified AAST-OIS injury grades IV-VI (p = 0.007; OR 6.38 [95% CI 1.64-24.78]), intraoperative dysrhythmias (p = 0.003; OR 17.38 [95% CI 2.59-116.49]) and associated cardiac injuries (p = 0.02; OR 8.74 [95% CI 1.37-55.79]) as independent predictors of outcome.

CONCLUSIONS

Predictors of outcome for penetrating pulmonary injuries requiring thoracotomy are identified and must be taken into account in their operative management. Tissue sparing techniques-stapled pulmonary tractotomy is once again validated, and it remains effective as the mainstay for their management; however, only pneumonectomy predicts outcome. AAST-OIS injury grades IV-VI predict outcome with higher injury grades requiring resective procedures.

Isolated transverse process fractures: insignificant injury or marker of complex injury pattern?

INTRODUCTION

This study investigates the incidence of isolated transverse process fractures (ITPFx) amongst vertebral fractures in trauma patients, and specific-associated injury patterns present in patients with ITPFx.

MATERIALS AND METHODS

A retrospective, 4-year review of our Level 1 Trauma Center registry was performed. Patients with blunt spinal column fractures were identified. Data collected included patient demographics, Injury Severity Score (ISS), type of imaging obtained, and concomitant injuries, including rib and pelvic fractures, liver, spleen, and kidney injury (SOI).

RESULTS

Of the 10,186 patients admitted during the study period, 881 (8.6%) suffered blunt thoraco-abdominal trauma resulting in vertebral fractures; 214/881 (24%) had ITPFx. All patients (10,186) underwent dedicated spinal multi-detector CT (MDCT) imaging; 26/214 (12.1%) patients had MRI. In all 26 patients, the MRI confirmed the CT findings. 202/214 (94.4%) had associated injuries: rib and pelvic fractures, 45.5 and 20.2%, respectively, and splenic, liver and kidney injury with an incidence of 13.8, 10.9, and 9.4%, respectively. A higher incidence of rib fractures was associated with ITPFx at the T1-4 levels, whereas ITPFx at the level of L5 were associated with pelvic fractures and SOI. Multiple logistic regression analysis identified T1-4 and L5 fractures as predictors of rib fractures and pelvic fractures independent of ISS, with OR: 2.55 (95% CI: 1.12-5.82) and 6.81 (95% CI: 3.14-14.78), respectively.

CONCLUSIONS

Based on the results of this study, we conclude that: (1) the use of MDCT imaging has increased the rate of identification of ITPFx; (2) dedicated spinal MDCT reconstruction and MRI may not be necessary to diagnose isolated thoracic and lumbar ITPFx; and (3) ITPFx of the thoracic spine and lower lumbar spine are markers of associated rib fractures and pelvic ring fractures, respectively, as well as of solid organ injuries.

An evaluation of combat application tourniquets on training military personnel: changes in application times and success rates in three successive phases

INTRODUCTION

Haemorrhage from the injured extremity is a significant cause of preventable death in military settings. This study evaluated the effect of training on the efficacy of the combat application tourniquet (CAT) and to define standards for military personnel.

METHOD

Participants from a training tank battalion were randomised. Data collected included age, body mass index, mean arterial pressure, hand dominance, femoral artery diameter and skin thickness. The study involved tourniquet application times (AT) and application success rates in basic, after-training and eyes-closed phases. Doppler ultrasound was used to identify the presence or absence of popliteal, radial and ulnar artery pulses.

RESULTS

A total of 102 trainees participated. In the after-training phase, the left and right upper extremity ATs were 35 ± 13.1 s, and 34.8 ± 13.5 s and the right and left lower extremity ATs were 20.6 ± 6.0 s and 20.5 ± 5.5 s, respectively. The overall tourniquet success rates in three successive study phases were 69.6%, 82.4% and 91.2%, respectively. A negative significant relationship was found between extremity circumference and tourniquet success.

DISCUSSION

The results show that the efficacy of CAT application increases with training. Further studies are required to investigate the reasons underlying application failures. This single group prospective randomised study involves level of evidence 4.

Contemporary wars and their contributions to vascular injury management

INTRODUCTION

Man's inhumanity for man still knows no boundaries, as we continue as a species as a whole to engage in war. According to Kohn's Dictionary of Wars [1], of over 3,700 years of recorded history, there have been a total of 3,010 wars. One is hard pressed to actually find a period of time in which here has not been an active conflict in the globe. The world has experienced two world wars: WWI (1914-1918) and WWII (1939-1945). The total number of military casualties in WWI was over 37 million, while WWII so far, has been the deadliest military conflict in history with over 60 million people killed accounting for slightly over 2.5% of the world's population.

MATERIAL AND METHODS

The purpose of this study is to review contemporary wars and their contributions to vascular injury management. It is precisely wartime contributions that have led to the more precise identification and management of these injuries resulting in countless lives and extremities saved. However, surgeons dealing with vascular injuries have faced a tough and arduous road. Their journey was initiated by surgical mavericks which undaunted, pressed on against all odds guided by William Stewart Halsted's classic statement in 1912: "One of the chief fascinations in surgery is the management of wounded vessels."

CONCLUSION

Contemporary wars of the XX-XXI centuries gave birth, defined and advanced the field of vascular injury management.

Popliteal vessel injuries: complex anatomy, difficult problems and surgical challenges

The incidence of popliteal vessel injuries is low, even in busy urban trauma centers. As a result of this fact, few trauma centers and trauma surgeons have developed extensive experience in the management of these injuries. Popliteal vessel injuries in both civilian and military arenas incur significant morbidity. These injuries present a difficult challenge, and, although the overall incidence of these injuries remains low, the sequelae can be devastating. Successful outcomes for limb salvage and survival result from early recognition and rapid surgical intervention by a multidisciplinary approach with a great participation of different surgical specialties. From the historical perspective, anatomy, incidence and associated injuries, to the clinical presentation, diagnosis, management, and morbidity and mortality, the aim of this article is to review the various aspects of these complex injuries.

Chemotography for multi-target SAR analysis in the context of biological pathways

The increasing amount of chemogenomics data, that is, activity measurements of many compounds across a variety of biological targets, allows for better understanding of pharmacology in a broad biological context. Rather than assessing activity at individual biological targets, today understanding of compound interaction with complex biological systems and molecular pathways is often sought in phenotypic screens. This perspective poses novel challenges to structure-activity relationship (SAR) assessment. Today, the bottleneck of drug discovery lies in the understanding of SAR of rich datasets that go beyond single targets in the context of biological pathways, potential off-targets, and complex selectivity profiles. To aid in the understanding and interpretation of such complex SAR, we introduce Chemotography (chemotype chromatography), which encodes chemical space using a color spectrum by combining clustering and multidimensional scaling. Rich biological data in our approach were visualized using spatial dimensions traditionally reserved for chemical space. This allowed us to analyze SAR in the context of target hierarchies and phylogenetic trees, two-target activity scatter plots, and biological pathways. Chemotography, in combination with the Kyoto Encyclopedia of Genes and Genomes (KEGG), also allowed us to extract pathway-relevant SAR from the ChEMBL database. We identified chemotypes showing polypharmacology and selectivity-conferring scaffolds, even in cases where individual compounds have not been tested against all relevant targets. In addition, we analyzed SAR in ChEMBL across the entire Kinome, going beyond individual compounds. Our method combines the strengths of chemical space visualization for SAR analysis and graphical representation of complex biological data. Chemotography is a new paradigm for chemogenomic data visualization and its versatile applications presented here may allow for improved assessment of SAR in biological context, such as phenotypic assay hit lists.

Subclavian vessel injuries: difficult anatomy and difficult territory

INTRODUCTION

Thoracic and thoracic related vascular injuries represent complex challenges to the trauma surgeon. Subclavian vessel injuries, in particular, are uncommon and highly lethal. Regardless of the mechanism, such injuries can result in significant morbidity and mortality.

MATERIALS AND METHODS

Systematic review of the literature, with emphasis on the diagnosis, treatment and outcomes of these injuries, incorporating the authors' experience.

CONCLUSIONS

These injuries are associated with significant morbidity and mortality. Patients who survive transport are subject to potentially debilitating injury and possibly death. Management of these injuries varies, depending on hemodynamic stability, mechanism of injury, and associated injuries. Despite significant advancements, mortality due to subclavian vessel injury remains high.

Penetrating carotid artery: uncommon complex and lethal injuries

Carotid arterial injuries are the most difficult and certainly the most immediately life-threatening injuries found in penetrating neck trauma. Their propensity to bleed actively and potentially occludes the airway and makes surgical intervention very challenging. Their potential for causing fatal neurological outcomes demands that trauma surgeons exercise excellent judgment in the approach to their definitive management. The purpose of this article is to review the diagnosis and management of these injuries.

Three-dimensional endoanal ultrasonography of external anal sphincter defects in patients with faecal incontinence: correlation with symptoms and manometry

AIM

Anal sphincter anatomy on two-dimensional endoanal -ultrasonography (EUS) does not always correlate with the clinical data. The purpose of this study was to determine whether three-dimensional (3D) measurements yield a better correlation.

METHOD

The study group included consecutive patients who underwent 3D EUS for faecal incontinence over a 2-year period. The medical charts were reviewed for Cleveland Clinic Foundation Fecal Incontinence (CCF-FI) score and manometric pressures. Endoanal ultrasonographic images were reviewed for the presence of an external anal sphincter (EAS) defect and its extent, as determined by the radial angle, length in the sagittal plane and percentage volume deficit. Correlational analyses were performed between the clinical and imaging data.

RESULTS

Sixty-one patients of median age 53 years (range 15-82) were evaluated. Thirty-two patients had either a complete (17) or partial (15) EAS defect, and 29 patients had an intact sphincter. The CCF-FI scores were similar in patients with and without an EAS defect (12.5 ± 5.6 and 11.4 ± 5.5, respectively). The intact-sphincter group had a significantly greater EAS length (3 ± 0.4 vs 2 ± 0.62 cm, P = 0.02) and higher mean maximal squeeze pressure (MMSP; 99.7 ± 52.6 vs 66.9 ± 52.9 mmHg, P = 0.009). There were no statistically significant correlations between MMSP, CCF-FI score and EAS status on 3D EUS. Mean percentage volume of the defect was similar in patients with complete and partial tears (14.5 ± 5.5 and 17.5 ± 7.2%, P = 0.25) and showed no correlation with physiological tests or symptom scores.

CONCLUSION

Improvements in external anal sphincter imaging have not yielded a better association with the clinical findings. The lack of clinical differences between patients with different EAS tears may reflect their similar volumetric defects.

A multiscale approach to sampling nascent peptide chains in the ribosomal exit tunnel

We present a new multiscale method that combines all-atom molecular dynamics with coarse-grained sampling, towards the aim of bridging two levels of physiology: the atomic scale of protein side chains and small molecules, and the huge scale of macromolecular complexes like the ribosome. Our approach uses all-atom simulations of peptide (or other ligand) fragments to calculate local 3D spatial potentials of mean force (PMF). The individual fragment PMFs are then used as a potential for a coarse-grained chain representation of the entire molecule. Conformational space and sequence space are sampled efficiently using generalized ensemble Monte Carlo. Here, we apply this method to the study of nascent polypeptides inside the cavity of the ribosome exit tunnel. We show how the method can be used to explore the accessible conformational and sequence space of nascent polypeptide chains near the ribosome peptidyl transfer center (PTC), with the eventual aim of understanding the basis of specificity for co-translational regulation. The method has many potential applications to predicting binding specificity and design, and is sufficiently general to allow even greater separation of scales in future work.

Normal mode partitioning of Langevin dynamics for biomolecules

We propose a novel normal mode multiple time stepping Langevin dynamics integrator called NML. The aim is to approximate the kinetics or thermodynamics of a biomolecule by a reduced model based on a normal mode decomposition of the dynamical space. Our basis set uses the eigenvectors of a mass reweighted Hessian matrix calculated with a biomolecular force field. This particular choice has the advantage of an ordering according to the eigenvalues, which have a physical meaning of being the square of the mode frequency. Low frequency eigenvalues correspond to more collective motions, whereas the highest frequency eigenvalues are the limiting factor for the stability of the integrator. In NML, the higher frequency modes are overdamped and relaxed near their energy minimum while respecting the subspace of low frequency dynamical modes. Our numerical results confirm that both sampling and rates are conserved for an implicitly solvated alanine dipeptide model, with only 30% of the modes propagated, when compared to the full model. For implicitly solvated systems, NML gives a twofold improvement in efficiency over plain Langevin dynamics for sampling a small 22 atom (alanine dipeptide) model and in excess of an order of magnitude for sampling an 882 atom (bovine pancreatic trypsin inhibitor) model, with good scaling with system size subject to the number of modes propagated. NML has been implemented in the open source software PROTOMOL.

Multidisciplinary approach for the management of complex hepatic injuries AAST-OIS grades IV-V: a prospective study

BACKGROUND

Complex hepatic injuries grades IV-V are highly lethal. The objective of this study is to assess the multidisciplinary approach for their management and to evaluate if survival could be improved with this approach.

STUDY DESIGN

Prospective 54-month study of all patients sustaining hepatic injuries grades IV-V managed operatively at a Level I Trauma Center.

MAIN OUTCOME MEASURE

survival.

STATISTICAL ANALYSIS

univariate and stepwise logistic regression.

RESULTS

Seventy-five patients sustained penetrating (47/63%) and blunt (28/37%) injuries. Seven (9%) patients underwent emergency department thoracotomy with a mortality of 100%. Out of the 75 patients, 52 (69%) sustained grade IV, and 23 (31%) grade V. The estimated blood loss was 3,539+/-3,040 ml. The overall survival was 69%, adjusted survival excluding patients requiring emergency department thoracotomy was 76%. Survival stratified to injury grade: grade IV 42/52-81%, grade V 10/23-43%. Mortality grade IV versus V injuries (p < 0.002; RR 2.94; 95% CI 1.52-5.70). Risk factors for mortality: packed red blood cells transfused in operating room (p=0.024), estimated blood loss (p < 0.001), dysryhthmia (p < 0.0001), acidosis (p = 0.051), hypothermia (p = 0.04). The benefit of angiography and angioembolization indicated: 12% mortality (2/17) among those that received it versus a 36% mortality (21/58) among those that did not (p = 0.074; RR 0.32; 95% CI 0.08-1.25). Stepwise logistic regression identified as significant independent predictors of outcome: estimated blood loss (p= 0.0017; RR 1.24; 95% CI 1.08-1.41) and number of packed red blood cells transfused in the operating room (p = 0.0358; RR 1.16; 95% CI 1.01-1.34).

CONCLUSIONS

The multidisciplinary approach to the management of these severe grades of injuries appears to improve survival in these highly lethal injuries. A prospective multi-institutional study is needed to validate this approach.

Emergency thoracotomy in trauma: rationale, risks, and realities

Emergency department thoracotomy (EDT) may serve as a life-saving tool when performed for the right indications, in selected patients, and in the hands of a trained surgeon. Critically injured patients 'in extremis' arrive at an increasing rate in the trauma bay, as an effect of improved pre-hospital trauma systems and rapid transport. Any patient in near, or full cardiovascular shock prompts the trauma surgeon to rapidly perform a thoracotomy. The EDT procedure is managed best by surgeons familiar with, and experienced in, penetrating cardiothoracic injuries. However, the geographical differences in trauma epidemiology lends no, or only scarce, experience with this procedure in most European trauma centres. Consequently, mandatory training is imperative for success. The rationale for performing an EDT is to: (I) resuscitate the agonal patient with penetrating cardiothoracic injuries; (II) release cardiac tamponade by evacuation of pericardial blood; (III) immediately control hemorrhage and repair cardiac or pulmonary injury; (IV) perform open cardiac massage; and (V) place a thoracic aortic cross-clamp to redistribute the remaining blood volume, and perfuse the carotids and coronary arteries. The prevalence rates of blood-borne viruses reported in critically injured patients in the USA (10-20%) exceed the prevalence in the Nordic countries (HIV prevalence < 1% in general population). However, risk is not negligible and mandated universal precautions are needed. The literature is rich in series describing the use of EDT, however, the best evidence is derived from a few prospective trials. EDT saves about one in every five patients with isolated penetrating cardiac injury, while > 98% die after blunt injury. Based on an updated review of the current available literature, this paper presents the current evidence regarding the rationale, risk, and outcomes for employing EDT in the field of trauma surgery.

Trauma in pregnancy: assessment and treatment

Women between the ages of 10 and 50 year-old have the potential for pregnancy; therefore this condition must be taken into consideration when a woman is examined in the Emergency Room after sustaining a traumatic event. Pregnancy produces significant physiologic and anatomic changes in every system of the female body. The evaluation of the traumatized pregnant patient, the approach, and the interpretation of the diagnostic tests results must be accompanied by the full knowledge of all changes that take place during pregnancy. In the same context, although the physician treating a pregnant trauma victim must remember that there are two patients, the treatment priorities are the same as for the non-pregnant trauma patient. The best initial treatment for the fetus is the optimum resuscitation of the mother. A thorough exam should take place to discover unique conditions that might be present in any pregnant patient such as blunt or penetrating injury to the uterus, placental abruption, amniotic fluid embolism, isoimmunization, and premature rupture of membranes. The obstetrician should be present at all times and be considered a part of the trauma team in the evaluation and treatment of a pregnant trauma patient.

Can conformational change be described by only a few normal modes?

We suggest a simple method to assess how many normal modes are needed to map a conformational change. By projecting the conformational change onto a subspace of the normal-mode vectors and using root mean square deviation as a test of accuracy, we find that the first 20 modes only contribute 50% or less of the total conformational change in four test cases (myosin, calmodulin, NtrC, and hemoglobin). In some allosteric systems, like the molecular switch NtrC, the conformational change is localized to a limited number of residues. We find that many more modes are necessary to accurately map this collective displacement. In addition, the normal-mode "spectra" can provide useful information about the details of the conformational change, especially when comparing structures with different bound ligands, in this case, calmodulin. Indeed, this approach presents normal-mode analysis as a useful basis in which to capture the mechanism of conformational change, and shows that the number of normal modes needed to capture the essential collective motions of atoms should be chosen according to the required accuracy.

Reliable variables in the exsanguinated patient which indicate damage control and predict outcome

BACKGROUND

Exsanguination as a syndrome is ill defined. The objectives of this study were to investigate the relationship between survival and patient characteristics--vital signs, factors relating to injury and treatment; determine if threshold levels of pH, temperature, and highest estimated blood loss can predict survival; and identify predictive factors for survival and to initiate damage control.

MATERIAL AND METHODS

A retrospective 6-year study was conducted, 1993 to 1998. In all, 548 patients met one or more criteria: (1) estimated blood loss > or =2,000 mL during trauma operation; (2) required > or =1,500 mL packed red blood cells (PRBC) during resuscitation; or (3) diagnosis of exsanguination. Analysis was made in two phases: (1) death versus survival in emergency department (ED); (2) death versus survival in operating room (OR). Statistical methods were Fisher's exact test, Student's t test, and logistic regression.

RESULTS

For 548 patients, mean Revised Trauma Score 4.38, mean Injury Severity Score 32. Penetrating injuries 82% versus blunt injuries 18%. Vital statistics in emergency department: mean blood pressure 63 mm Hg, heart rate 78 beats per minute. Mean OR pH 7.15 and temperature 34.3 degrees C. Mortality was 379 of 548 (69%). Predictive factors for mortality (means): pH < or =7.2, temperature <34 degrees C, OR blood replacement >4,000 mL, total OR fluid replacement >10,000 mL, estimated blood loss >15 mL/minute (P <0.001). Analysis 1: death versus survival in ED, logistic regression. Independent risk factors for survival: penetrating trauma, spontaneous ventilation, and no ED thoracotomy (P <0.001; probability of survival 0.99613). Analysis 2: death versus survival in OR, logistic regression. Independent risk factors for survival: ISS < or =20, spontaneous ventilation in ED, OR PRBC replacement <4,000 mL, no ED or OR thoracotomy, absence of abdominal vascular injury (P <0.001, max R(2) 0.55, concordance 89%).

CONCLUSIONS

Survival rates can be predicted in exsanguinating patients. "Damage control" should be performed using these criteria. Knowledge of these patterns can be valuable in treatment selection.

Abdominal vascular injuries: injuries to the aorta

This article discusses injuries to the abdominal aorta at its supra- and infrarenal positions, focusing on the surgical approaches to abdominal aorta injuries and renal vascular pedicles. The controversy regarding the use of bioprosthetic materials and the coLlective experience with these injuries as reported in the literature are reviewed. Primary renal artery repair versus nephrectomy also is examined.

Renal vascular injuries

Even today, most renal vascular injuries result in loss of renal function. Kidney salvage is not possible because of late diagnosis and the presence of severe associated injuries. Physical exam and basic laboratory tests are not sensitive; thus, a high index of suspicion is required. Repair should be attempted for all solitary kidneys and for patients sustaining bilateral injuries. All viable kidneys should be revascularized in order to increase the chances of obtaining adequate functional renal tissue. In the event that revascularization is not feasible, nephrectomy can be performed at a later time, if hypertension develops. In some cases, delayed return of function is possible, but in most cases the kidney will atrophy without producing hypertension. Most importantly, maintaining a high index of suspicion, prompt diagnostic evaluation, and judicious treatment can optimize outcome lowering the significant morbidity and mortality of renal vascular injuries.

Elements of cognitive rehabilitation after right hemisphere stroke

There are two basic approaches to cognitive training: (1) impairment training and (2) task specific training. Impairment training addresses impairments common to a number of tasks and attempts to offer a general benefit to all of the tasks at once. Task specific training focuses on the impairments that arise in a single task and attempts to improve performance on that task. Impairment training of spatial disorders following right hemisphere stroke has shown some success when curricula are properly designed. The success, however, is quite limited because of normal cognitive constraints and those occurring after brain damage. Task specific training in conjunction with the combined application of various cognitive principles appears more promising, but as yet, only a few studies exist. The neurologic factors are likely to be the same factors that influence recovery. The factors that influence trainability are lesion topography (size and location of the focus plus premorbid atrophy), lesion chronicity, and the presence of additional cognitive impairments (anosognosia, confusion, and abulia). Other interventions that may be beneficial, even for training resistant patients, include behavior modification, cognitive prostheses, and drugs.

Two-mirror wave-front-dividing interferometer for infrared synchrotron radiation

We describe what is to our knowledge the first instrument specifically designed for use with infrared synchrotron radiation that takes advantage of the spatial coherence of this radiation. Beam splitting is achieved by wave-front division. We show data taken with the instrument over the wavelength region from 10 to 1000 microm (1-mm wavelengths) and discuss the advantages of this instrument over a conventional one.

Controlled trial of methylprednisolone pulses and low dose oral prednisone for the minimal change nephrotic syndrome

In a multicentre, randomised, prospective trial 89 patients (67 children and 22 adults) with the minimal change nephrotic syndrome were treated with three intravenous pulses of methylprednisolone followed by low dose oral prednisone for six months (group given methylprednisolone) or with high dose oral prednisone for four weeks followed by low dose oral prednisone for five months (control group). Five patients in the group given methylprednisolone and one in the control group did not respond initially. The time to response was shorter in children treated with methylprednisolone. No significant differences between the two groups were observed in the number of patients who relapsed or number of relapses per patient per year. Patients given methylprednisolone tended to relapse earlier than patients in the control group. Side effects related to treatment were significantly fewer in the group given methylprednisolone than in the control group. These data suggest that a short course of methylprednisolone pulses followed by low dose oral prednisone is only marginally less effective than a regimen of high dose oral steroids but can improve the ratio of risk to benefit associated with treatment of the minimal change nephrotic syndrome.