Workforce strategies during the first wave of the COVID-19 pandemic: a retrospective online survey at intensive care units in Germany.

BACKGROUND: As the COVID-19 pandemic swept across the globe at the beginning of 2020, healthcare systems were forced to rapidly adapt and expand to meet the sudden surge in demand for intensive care services. This study is the first systematic analysis of the strategies employed by German hospitals to recruit personnel and expand bed capacities during the first wave of the pandemic, and to evaluate the effectiveness of those recruitment measures. METHODS: 152 German hospitals with intensive care capacities were selected and invited to participate in an online-based retrospective survey. Factors like the geographic distribution, individual COVID burden and level of care were considered for inclusion in the sample. The data were analyzed descriptively. RESULTS: A total of 41 hospitals participated in the survey. The additional demand for intensive care beds was met primarily by activating intensive care beds that were previously considered as non-operational in existing intensive care units (81% of respondents) and by upgrading recovery rooms (73%). The physician staffing requirements were met at approximately 75%, while the nursing staffing requirements were only met by about 45%. Staffing needs were met through reallocations/transfers (85%), staff recruitment from parental leave or retirement (49%), increased hours worked by internal staff (49%), new staff hiring (44%) and increased use of temporary staff (32%). Staff reallocations/transfers to critical care within a hospital were rated as the most effective measure. In this context, specialized personnel mostly from anesthesiology departments were appointed to intensive care medicine. CONCLUSIONS: Despite multiple recruitment efforts, the pandemic has exacerbated the nursing staff shortage. The reallocation of existing staff within hospitals was a key element in covering the staffing needs. However, additional measures and efforts are required in order to ensure that critically ill patients can be cared for without compromise. The results of this study may have important implications for healthcare providers and policymakers, offering an evidence-based foundation for responding to future public health emergencies with agility, efficiency, and success.

Thoracic Epidural Analgesia Is Not Associated With Improved Survival After Pancreatic Surgery: Long-Term Follow-Up of the Randomized Controlled PAKMAN Trial.

BACKGROUND: Perioperative thoracic epidural analgesia (EDA) and patient-controlled intravenous analgesia (PCIA) are common forms of analgesia after pancreatic surgery. Current guidelines recommend EDA over PCIA, and evidence suggests that EDA may improve long-term survival after surgery, especially in cancer patients. The aim of this study was to determine whether perioperative EDA is associated with an improved patient prognosis compared to PCIA in pancreatic surgery. METHODS: The PAKMAN trial was an adaptive, pragmatic, international, multicenter, randomized controlled superiority trial conducted from June 2015 to October 2017. Three to five years after index surgery a long-term follow-up was performed from October 2020 to April 2021. RESULTS: For long-term follow-up of survival, 109 patients with EDA were compared to 111 patients with PCIA after partial pancreatoduodenectomy (PD). Long-term follow-up of quality of life (QoL) and pain assessment was available for 40 patients with EDA and 45 patients with PCIA (questionnaire response rate: 94%). Survival analysis revealed that EDA, when compared to PCIA, was not associated with improved overall survival (OS, HR, 1.176, 95% HR-CI, 0.809-1.710, P = .397, n = 220). Likewise, recurrence-free survival did not differ between groups (HR, 1.116, 95% HR-CI, 0.817-1.664, P = .397, n = 220). OS subgroup analysis including only patients with malignancies showed no significant difference between EDA and PCIA (HR, 1.369, 95% HR-CI, 0.932-2.011, P = .109, n = 179). Similar long-term effects on QoL and pain severity were observed in both groups (EDA: n = 40, PCIA: n = 45). CONCLUSIONS: Results from this long-term follow-up of the PAKMAN randomized controlled trial do not support favoring EDA over PCIA in pancreatic surgery. Until further evidence is available, EDA and PCIA should be considered similar regarding long-term survival.

Peripheral temperature dysregulation associated with functionally altered NaV1.8 channels.

The voltage-gated sodium channel NaV1.8 is prominently expressed in the soma and axons of small-caliber sensory neurons, and pathogenic variants of the corresponding gene SCN10A are associated with peripheral pain and autonomic dysfunction. While most disease-associated SCN10A variants confer gain-of-function properties to NaV1.8, resulting in hyperexcitability of sensory neurons, a few affect afferent excitability through a loss-of-function mechanism. Using whole-exome sequencing, we here identify a rare heterozygous SCN10A missense variant resulting in alteration p.V1287I in NaV1.8 in a patient with a 15-year history of progressively worsening temperature dysregulation in the distal extremities, particularly in the feet. Further symptoms include increasingly intensifying tingling and numbness in the fingers and increased sweating. To assess the impact of p.V1287I on channel function, we performed voltage-clamp recordings demonstrating that the alteration confers loss- and gain-of-function characteristics to NaV1.8 characterized by a right-shifted voltage dependence of channel activation and inactivation. Current-clamp recordings from transfected mouse dorsal root ganglion neurons further revealed that NaV1.8-V1287I channels broaden the action potentials of sensory neurons and increase their firing rates in response to depolarizing current stimulations, indicating a gain-of-function mechanism of the variant at the cellular level in a heterozygous setting. The data support the hypothesis that the properties of NaV1.8 p.V1287I are causative for the patient's symptoms and that nonpainful peripheral paresthesias should be considered part of the clinical spectrum of NaV1.8-associated disorders.

Electrophysiological Properties of Induced Pluripotent Stem Cell-Derived Midbrain Dopaminergic Neurons Correlate With Expression of Tyrosine Hydroxylase.

Induced pluripotent stem cell (iPSC)-based generation of tyrosine hydroxylase-positive (TH+) dopaminergic neurons (DNs) is a powerful method for creating patient-specific in vitro models to elucidate mechanisms underlying Parkinson's disease (PD) at the cellular and molecular level and to perform drug screening. However, currently available differentiation paradigms result in highly heterogeneous cell populations, often yielding a disappointing fraction (<50%) of the PD-relevant TH+ DNs. To facilitate the targeted analysis of this cell population and to characterize their electrophysiological properties, we employed CRISPR/Cas9 technology and generated an mCherry-based human TH reporter iPSC line. Subsequently, reporter iPSCs were subjected to dopaminergic differentiation using either a "floor plate protocol" generating DNs directly from iPSCs or an alternative method involving iPSC-derived neuronal precursors (NPC-derived DNs). To identify the strategy with the highest conversion efficiency to mature neurons, both cultures were examined for a period of 8 weeks after triggering neuronal differentiation by means of immunochemistry and single-cell electrophysiology. We confirmed that mCherry expression correlated with the expression of endogenous TH and that genetic editing did neither affect the differentiation process nor the endogenous TH expression in iPSC- and NPC-derived DNs. Although both cultures yielded identical proportions of TH+ cells (≈30%), whole-cell patch-clamp experiments revealed that iPSC-derived DNs gave rise to larger currents mediated by voltage-gated sodium and potassium channels, showed a higher degree of synaptic activity, and fired trains of mature spontaneous action potentials more frequently compared to NPC-derived DNs already after 2 weeks in differentiation. Moreover, spontaneous action potential firing was more frequently detected in TH+ neurons compared to the TH- cells, providing direct evidence that these two neuronal subpopulations exhibit different intrinsic electrophysiological properties. In summary, the data reveal substantial differences in the electrophysiological properties of iPSC-derived TH+ and TH- neuronal cell populations and that the "floor plate protocol" is particularly efficient in generating electrophysiologically mature TH+ DNs, which are the most vulnerable neuronal subtype in PD.

Isolation and transfection of myenteric neurons from mice for patch-clamp applications.

The enteric nervous system (ENS) is a complex neuronal network organized in ganglionated plexuses that extend along the entire length of the gastrointestinal tract. Largely independent of the central nervous system, the ENS coordinates motility and peristalsis of the digestive tract, regulates secretion and absorption, and is involved in immunological processes. Electrophysiological methods such as the patch-clamp technique are particularly suitable to study the function of neurons as well as the biophysical parameters of the underlying ion channels under both physiological and pathophysiological conditions. However, application of the patch-clamp method to ENS neurons remained difficult because they are embedded in substantial tissue layers that limit access to and targeted manipulation of these cells. Here, we present a robust step-by-step protocol that involves isolation of ENS neurons from adult mice, culturing of the cells, their transfection with plasmid DNA, and subsequent electrophysiological characterization of individual neurons in current-clamp and voltage-clamp recordings. With this protocol, ENS neurons can be prepared, transfected, and electrophysiologically characterized within 72 h. Using isolated ENS neurons, we demonstrate the feasibility of the approach by functional overexpression of recombinant voltage-gated NaV1.9 mutant channels associated with hereditary sensory and autonomic neuropathy type 7 (HSAN-7), a disorder characterized by congenital analgesia and severe constipation that can require parenteral nutrition. Although our focus is on the electrophysiological evaluation of isolated ENS neurons, the presented methodology is also useful to analyze molecules other than sodium channels or to apply alternative downstream assays including calcium imaging, proteomic and nucleic acid approaches, or immunochemistry.

Machine learning identifies ICU outcome predictors in a multicenter COVID-19 cohort.

BACKGROUND: Intensive Care Resources are heavily utilized during the COVID-19 pandemic. However, risk stratification and prediction of SARS-CoV-2 patient clinical outcomes upon ICU admission remain inadequate. This study aimed to develop a machine learning model, based on retrospective & prospective clinical data, to stratify patient risk and predict ICU survival and outcomes. METHODS: A Germany-wide electronic registry was established to pseudonymously collect admission, therapeutic and discharge information of SARS-CoV-2 ICU patients retrospectively and prospectively. Machine learning approaches were evaluated for the accuracy and interpretability of predictions. The Explainable Boosting Machine approach was selected as the most suitable method. Individual, non-linear shape functions for predictive parameters and parameter interactions are reported. RESULTS: 1039 patients were included in the Explainable Boosting Machine model, 596 patients retrospectively collected, and 443 patients prospectively collected. The model for prediction of general ICU outcome was shown to be more reliable to predict "survival". Age, inflammatory and thrombotic activity, and severity of ARDS at ICU admission were shown to be predictive of ICU survival. Patients' age, pulmonary dysfunction and transfer from an external institution were predictors for ECMO therapy. The interaction of patient age with D-dimer levels on admission and creatinine levels with SOFA score without GCS were predictors for renal replacement therapy. CONCLUSIONS: Using Explainable Boosting Machine analysis, we confirmed and weighed previously reported and identified novel predictors for outcome in critically ill COVID-19 patients. Using this strategy, predictive modeling of COVID-19 ICU patient outcomes can be performed overcoming the limitations of linear regression models. Trial registration "ClinicalTrials" (clinicaltrials.gov) under NCT04455451.

Gastrointestinal Complications After Pancreatoduodenectomy With Epidural vs Patient-Controlled Intravenous Analgesia: A Randomized Clinical Trial.

Importance: Morbidity is still high in pancreatic surgery, driven mainly by gastrointestinal complications such as pancreatic fistula. Perioperative thoracic epidural analgesia (EDA) and patient-controlled intravenous analgesia (PCIA) are frequently used for pain control after pancreatic surgery. Evidence from a post hoc analysis suggests that PCIA is associated with fewer gastrointestinal complications. Objective: To determine whether postoperative PCIA decreases the occurrence of gastrointestinal complications after pancreatic surgery compared with EDA. Design, Setting, and Participants: In this adaptive, pragmatic, international, multicenter, superiority randomized clinical trial conducted from June 30, 2015, to October 1, 2017, 371 patients at 9 European pancreatic surgery centers who were scheduled for elective pancreatoduodenectomy were randomized to receive PCIA (n = 185) or EDA (n = 186); 248 patients (124 in each group) were analyzed. Data were analyzed from February 22 to April 25, 2019, using modified intention to treat and per protocol. Interventions: Patients in the PCIA group received general anesthesia and postoperative PCIA with intravenous opioids with the help of a patient-controlled analgesia device. In the EDA group, patients received general anesthesia and intraoperative and postoperative EDA. Main Outcomes and Measures: The primary end point was a composite of pancreatic fistula, bile leakage, delayed gastric emptying, gastrointestinal bleeding, or postoperative ileus within 30 days after surgery. Secondary end points included 30-day mortality, other complications, postoperative pain levels, intraoperative or postoperative use of vasopressor therapy, and fluid substitution. Results: Among the 248 patients analyzed (147 men; mean [SD] age, 64.9 [10.7] years), the primary composite end point did not differ between the PCIA group (61 [49.2%]) and EDA group (57 [46.0%]) (odds ratio, 1.17; 95% CI, 0.71-1.95 P = .54). Neither individual components of the primary end point nor 30-day mortality, postoperative pain levels, or intraoperative and postoperative substitution of fluids differed significantly between groups. Patients receiving EDA gained more weight by postoperative day 4 than patients receiving PCIA (mean [SD], 4.6 [3.8] vs 3.4 [3.6] kg; P = .03) and received more vasopressors (46 [37.1%] vs 31 [25.0%]; P = .04). Failure of EDA occurred in 23 patients (18.5%). Conclusions and Relevance: This study found that the choice between PCIA and EDA for pain control after pancreatic surgery should not be based on concerns regarding gastrointestinal complications because the 2 procedures are comparable with regard to effectiveness and safety. However, EDA was associated with several shortcomings. Trial Registration: German Clinical Trials Register: DRKS00007784.

Improve hip fracture outcome in the elderly patient (iHOPE): a study protocol for a pragmatic, multicentre randomised controlled trial to test the efficacy of spinal versus general anaesthesia.

INTRODUCTION: Hip fracture surgery is associated with high in-hospital and 30-day mortality rates and serious adverse patient outcomes. Evidence from randomised controlled trials regarding effectiveness of spinal versus general anaesthesia on patient-centred outcomes after hip fracture surgery is sparse. METHODS AND ANALYSIS: The iHOPE study is a pragmatic national, multicentre, randomised controlled, open-label clinical trial with a two-arm parallel group design. In total, 1032 patients with hip fracture (>65 years) will be randomised in an intended 1:1 allocation ratio to receive spinal anaesthesia (n=516) or general anaesthesia (n=516). Outcome assessment will occur in a blinded manner after hospital discharge and inhospital. The primary endpoint will be assessed by telephone interview and comprises the time to the first occurring event of the binary composite outcome of all-cause mortality or new-onset serious cardiac and pulmonary complications within 30 postoperative days. In-hospital secondary endpoints, assessed via in-person interviews and medical record review, include mortality, perioperative adverse events, delirium, satisfaction, walking independently, length of hospital stay and discharge destination. Telephone interviews will be performed for long-term endpoints (all-cause mortality, independence in walking, chronic pain, ability to return home cognitive function and overall health and disability) at postoperative day 30±3, 180±45 and 365±60. ETHICS AND DISSEMINATION: iHOPE has been approved by the leading Ethics Committee of the Medical Faculty of the RWTH Aachen University on 14 March 2018 (EK 022/18). Approval from all other involved local Ethical Committees was subsequently requested and obtained. Study started in April 2018 with a total recruitment period of 24 months. iHOPE will be disseminated via presentations at national and international scientific meetings or conferences and publication in peer-reviewed international scientific journals. TRIAL REGISTRATION NUMBER: DRKS00013644; Pre-results.

Etomidate and propylene glycol activate nociceptive TRP ion channels.

BACKGROUND: Etomidate is a preferred drug for the induction of general anesthesia in cardiovascular risk patients. As with propofol and other perioperatively used anesthetics, the application of aqueous etomidate formulations causes an intensive burning pain upon injection. Such algogenic properties of etomidate have been attributed to the solubilizer propylene glycol which represents 35% of the solution administered clinically. The aim of this study was to investigate the underlying molecular mechanisms which lead to injection pain of aqueous etomidate formulations. RESULTS: Activation of the nociceptive transient receptor potential (TRP) ion channels TRPA1 and TRPV1 was studied in a transfected HEK293t cell line by whole-cell voltage clamp recordings of induced inward ion currents. Calcium influx in sensory neurons of wild-type and trp knockout mice was ratiometrically measured by Fura2-AM staining. Stimulated calcitonin gene-related peptide release from mouse sciatic nerves was detected by enzyme immunoassay. Painfulness of different etomidate formulations was tested in a translational human pain model. Etomidate as well as propylene glycol proved to be effective agonists of TRPA1 and TRPV1 ion channels at clinically relevant concentrations. Etomidate consistently activated TRPA1, but there was also evidence for a contribution of TRPV1 in dependence of drug concentration ranges and species specificities. Distinct N-terminal cysteine and lysine residues seemed to mediate gating of TRPA1, although the electrophile scavenger N-acetyl-L-cysteine did not prevent its activation by etomidate. Propylene glycol-induced activation of TRPA1 and TRPV1 appeared independent of the concomitant high osmolarity. Intradermal injections of etomidate as well as propylene glycol evoked severe burning pain in the human pain model that was absent with emulsification of etomidate. CONCLUSIONS: Data in our study provided evidence that pain upon injection of clinical aqueous etomidate formulations is not an unspecific effect of hyperosmolarity but rather due to a specific action mediated by activated nociceptive TRPA1 and TRPV1 ion channels in sensory neurons.

Mutagenesis of the NaChBac sodium channel discloses a functional role for a conserved S6 asparagine.

Asparagine is conserved in the S6 transmembrane segments of all voltage-gated sodium, calcium, and TRP channels identified to date. A broad spectrum of channelopathies including cardiac arrhythmias, epilepsy, muscle diseases, and pain disorders is associated with its mutation. To investigate its effects on sodium channel functional properties, we mutated the simple prokaryotic sodium channel NaChBac. Electrophysiological characterization of the N225D mutant reveals that this conservative substitution shifts the voltage-dependence of inactivation by 25 mV to more hyperpolarized potentials. The mutant also displays greater thermostability, as determined by synchrotron radiation circular dichroism spectroscopy studies of purified channels. Based on our analyses of high-resolution structures of NaChBac homologues, we suggest that the side-chain amine group of asparagine 225 forms one or more hydrogen bonds with different channel elements and that these interactions are important for normal channel function. The N225D mutation eliminates these hydrogen bonds and the structural consequences involve an enhanced channel inactivation.

Telemedizin: Chancen in der Schmerztherapie.

Pain is generally undertreated and there is a need to differentiate and improve access to appropriate pain care. The growing Field of telehealth offers a novel opportunity for pain care, exploiting mainly communicative and pharmacological therapeutic principles. Rationale for telemedicine for the management of chronic pain are the potential to overcome timely, economical, and structural barriers for the access to specialized pain care as well as the general open mindedness of physicians and patients towards this technology. The general usability and effectiveness of telemedicine in pain care has been described. The most prominent applications of telemedicine in pain care are store-and-forward applications and direct consultations. Smartphone applications are easily accessible and inexpensive. The quality and effectiveness of smartphone applications has not been evaluated thoroughly due to a lack of regulatory objectives. Estimations of the cost-effectiveness of telemedicine in pain care are limited due to a lack of data regarding long-term outcome and healthcare utilization after treatment. Telemedicine offers new approaches to improve pain care for the treatment of acute postoperative pain as well. Future challenges will be to start a collaborative effort between developers and health-care professionals to implement evidence-based clinical protocols into telemedicine applications and to evaluate the effectiveness and safety of existing telemedicine programmes.

[Tools for junior scientists support from medical societies: survey amongst members organized in the Association of the Scientific Medical Societies (AWMF)]. / Förderung des wissenschaftlichen Nachwuchses durch medizinische Fachgesellschaften - Umfrage unter den Mitgliedsgesellschaften der Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften e.V. (AWMF).

INTRODUCTION: A decreasing number of young physicians go for an academic career. The most frequently cited reasons are deficient structures and a lack of perspectives. The German Research Foundation warned against supply gaps in the medical sciences and in 2010 published recommendations for the improvement of professional development at all levels of medical education. A systematic survey of existing support tools and their dissemination among the medical societies has not yet been conducted. METHOD: Network members of the AWMF were contacted by e-mail and asked to answer 59 questions regarding the support of junior scientists in their respective societies. RESULTS: 28 out of 147 societies replied to the questionnaire. Most of the societies offer at least one of the following tools (multiple responses; selective topics): award for oral presentations (n=27), free attendance at conferences (n=15), financial research funding (n=19), assessment of any funding application (n=10), mentoring (n=6), support of students working on their doctoral thesis (n=26), support of studies abroad (n=16), training course on statistics/ laboratory methods (n=17), support with clinical studies (n=22). DISCUSSION: Here, we present our survey findings on established support tools for junior scientists for the first time. Apart from the medical schools, several medical-scientific societies have also started to provide tools of support for their junior scientists. However, to ensure that long-term perspectives and attractive conditions are provided in the field of medical science for junior scientists, broader support and interdisciplinary exchange of established tools are needed.

Pattern of Functional TTX-Resistant Sodium Channels Reveals a Developmental Stage of Human iPSC- and ESC-Derived Nociceptors.

Human pluripotent stem cells (hPSCs) offer the opportunity to generate neuronal cells, including nociceptors. Using a chemical-based approach, we generated nociceptive sensory neurons from HUES6 embryonic stem cells and retrovirally reprogrammed induced hPSCs derived from fibroblasts. The nociceptive neurons expressed respective markers and showed tetrodotoxin-sensitive (TTXs) and -resistant (TTXr) voltage-gated sodium currents in patch-clamp experiments. In contrast to their counterparts from rodent dorsal root ganglia, TTXr currents of hPSC-derived nociceptors unexpectedly displayed a significantly more hyperpolarized voltage dependence of activation and fast inactivation. This apparent discrepancy is most likely due to a substantial expression of the developmentally important sodium channel NAV1.5. In view of the obstacles to recapitulate neuropathic pain in animal models, our data advance hPSC-derived nociceptors as a better model to study developmental and pathogenetic processes in human nociceptive neurons and to develop more specific small molecules to attenuate pain.

Inherited pain: sodium channel Nav1.7 A1632T mutation causes erythromelalgia due to a shift of fast inactivation.

Inherited erythromelalgia (IEM) causes debilitating episodic neuropathic pain characterized by burning in the extremities. Inherited "paroxysmal extreme pain disorder" (PEPD) differs in its clinical picture and affects proximal body areas like the rectal, ocular, or jaw regions. Both pain syndromes have been linked to mutations in the voltage-gated sodium channel Nav1.7. Electrophysiological characterization shows that IEM-causing mutations generally enhance activation, whereas mutations leading to PEPD alter fast inactivation. Previously, an A1632E mutation of a patient with overlapping symptoms of IEM and PEPD was reported (Estacion, M., Dib-Hajj, S. D., Benke, P. J., Te Morsche, R. H., Eastman, E. M., Macala, L. J., Drenth, J. P., and Waxman, S. G. (2008) NaV1.7 Gain-of-function mutations as a continuum. A1632E displays physiological changes associated with erythromelalgia and paroxysmal extreme pain disorder mutations and produces symptoms of both disorders. J. Neurosci. 28, 11079-11088), displaying a shift of both activation and fast inactivation. Here, we characterize a new mutation of Nav1.7, A1632T, found in a patient suffering from IEM. Although transfection of A1632T in sensory neurons resulted in hyperexcitability and spontaneous firing of dorsal root ganglia (DRG) neurons, whole-cell patch clamp of transfected HEK cells revealed that Nav1.7 activation was unaltered by the A1632T mutation but that steady-state fast inactivation was shifted to more depolarized potentials. This is a characteristic normally attributed to PEPD-causing mutations. In contrast to the IEM/PEPD crossover mutation A1632E, A1632T failed to slow current decay (i.e. open-state inactivation) and did not increase resurgent currents, which have been suggested to contribute to high-frequency firing in physiological and pathological conditions. Reduced fast inactivation without increased resurgent currents induces symptoms of IEM, not PEPD, in the new Nav1.7 mutation, A1632T. Therefore, persistent and resurgent currents are likely to determine whether a mutation in Nav1.7 leads to IEM or PEPD.

Evaluating predictive modeling algorithms to assess patient eligibility for clinical trials from routine data.

BACKGROUND: The necessity to translate eligibility criteria from free text into decision rules that are compatible with data from the electronic health record (EHR) constitutes the main challenge when developing and deploying clinical trial recruitment support systems. Recruitment decisions based on case-based reasoning, i.e. using past cases rather than explicit rules, could dispense with the need for translating eligibility criteria and could also be implemented largely independently from the terminology of the EHR's database. We evaluated the feasibility of predictive modeling to assess the eligibility of patients for clinical trials and report on a prototype's performance for different system configurations. METHODS: The prototype worked by using existing basic patient data of manually assessed eligible and ineligible patients to induce prediction models. Performance was measured retrospectively for three clinical trials by plotting receiver operating characteristic curves and comparing the area under the curve (ROC-AUC) for different prediction algorithms, different sizes of the learning set and different numbers and aggregation levels of the patient attributes. RESULTS: Random forests were generally among the best performing models with a maximum ROC-AUC of 0.81 (CI: 0.72-0.88) for trial A, 0.96 (CI: 0.95-0.97) for trial B and 0.99 (CI: 0.98-0.99) for trial C. The full potential of this algorithm was reached after learning from approximately 200 manually screened patients (eligible and ineligible). Neither block- nor category-level aggregation of diagnosis and procedure codes influenced the algorithms' performance substantially. CONCLUSIONS: Our results indicate that predictive modeling is a feasible approach to support patient recruitment into clinical trials. Its major advantages over the commonly applied rule-based systems are its independency from the concrete representation of eligibility criteria and EHR data and its potential for automation.

Secondary use of routinely collected patient data in a clinical trial: an evaluation of the effects on patient recruitment and data acquisition.

PURPOSE: Clinical trials are time-consuming and require constant focus on data quality. Finding sufficient time for a trial is a challenging task for involved physicians, especially when it is conducted in parallel to patient care. From the point of view of medical informatics, the growing amount of electronically available patient data allows to support two key activities: the recruitment of patients into the study and the documentation of trial data. METHODS: The project was carried out at one site of a European multicenter study. The study protocol required eligibility assessment for 510 patients in one week and the documentation of 46-186 data elements per patient. A database query based on routine data from patient care was set up to identify eligible patients and its results were compared to those of manual recruitment. Additionally, routine data was used to pre-populate the paper-based case report forms and the time necessary to fill in the remaining data elements was compared to completely manual data collection. RESULTS: Even though manual recruitment of 327 patients already achieved high sensitivity (88%) and specificity (87%), the subsequent electronic report helped to include 42 (14%) additional patients and identified 21 (7%) patients, who were incorrectly included. Pre-populating the case report forms decreased the time required for documentation from a median of 255 to 30s. CONCLUSIONS: Reuse of routine data can help to improve the quality of patient recruitment and may reduce the time needed for data acquisition. These benefits can exceed the efforts required for development and implementation of the corresponding electronic support systems.

Methylglyoxal modification of Nav1.8 facilitates nociceptive neuron firing and causes hyperalgesia in diabetic neuropathy.

This study establishes a mechanism for metabolic hyperalgesia based on the glycolytic metabolite methylglyoxal. We found that concentrations of plasma methylglyoxal above 600 nM discriminate between diabetes-affected individuals with pain and those without pain. Methylglyoxal depolarizes sensory neurons and induces post-translational modifications of the voltage-gated sodium channel Na(v)1.8, which are associated with increased electrical excitability and facilitated firing of nociceptive neurons, whereas it promotes the slow inactivation of Na(v)1.7. In mice, treatment with methylglyoxal reduces nerve conduction velocity, facilitates neurosecretion of calcitonin gene-related peptide, increases cyclooxygenase-2 (COX-2) expression and evokes thermal and mechanical hyperalgesia. This hyperalgesia is reflected by increased blood flow in brain regions that are involved in pain processing. We also found similar changes in streptozotocin-induced and genetic mouse models of diabetes but not in Na(v)1.8 knockout (Scn10(-/-)) mice. Several strategies that include a methylglyoxal scavenger are effective in reducing methylglyoxal- and diabetes-induced hyperalgesia. This previously undescribed concept of metabolically driven hyperalgesia provides a new basis for the design of therapeutic interventions for painful diabetic neuropathy.

Local anesthetic-like inhibition of voltage-gated Na(+) channels by the partial µ-opioid receptor agonist buprenorphine.

BACKGROUND: Opioids induce analgesia mainly by inhibiting synaptic transmission via G protein-coupled opioid receptors. In addition to analgesia, buprenorphine induces a pronounced antihyperalgesia and is an effective adjuvant to local anesthetics. These properties only partially apply to other opioids, and thus targets other than opioid receptors are likely to be employed. Here we asked if buprenorphine inhibits voltage-gated Na(+) channels. METHODS: Na(+) currents were examined by whole cell patch clamp recordings on different recombinant Na(+) channel α-subunits. The effect of buprenorphine on unmyelinated mouse C-fibers was examined with the skin-nerve preparation. Data are presented as mean ± SEM. RESULTS: Buprenorphine induced a concentration-dependent tonic (IC(50) 33 ± 2 µM) and use-dependent block of endogenous Na(+) channels in ND7/23 cells. This block was state-dependent and displayed slow on and off characteristics. The effect of buprenorphine was reduced on local anesthetic insensitive Nav1.4-mutant constructs and was more pronounced on the inactivation-deficient Nav1.4-WCW mutant. Neuronal (Nav1.3, Nav1.7, and Nav1.8), cardiac (Nav1.5), and skeletal muscle (Nav1.4) α-subunits displayed small differences in tonic block, but similar degrees of use-dependent block. According to our patch clamp data, buprenorphine blocked electrically evoked action potentials in C-fiber nerve terminals. Buprenorphine was more potent than other opioids, including morphine (IC(50) 378 ± 20 µM), fentanyl (IC(50) 95 ± 5 µM), sufentanil (IC(50) 111 ± 6 µM), remifenatil (IC(50) 612 ± 17 µM), and tramadol (IC(50) 194 ± 9 µM). CONCLUSIONS: Buprenorphine is a potent local anesthetic and blocks voltage-gated Na(+) channels via the local anesthetic binding site. This property is likely to be relevant when buprenorphine is used for pain treatment and for local anesthesia.

Activation of TRPA1 by membrane permeable local anesthetics.

BACKGROUND: Low concentrations of local anesthetics (LAs) suppress cellular excitability by inhibiting voltage-gated Na⁺ channels. In contrast, LAs at high concentrations can be excitatory and neurotoxic. We recently demonstrated that LA-evoked activation of sensory neurons is mediated by the capsaicin receptor TRPV1, and, to a lesser extent by the irritant receptor TRPA1. LA-induced activation and sensitization of TRPV1 involves a domain that is similar, but not identical to the vanilloid-binding domain. Additionally, activation of TRPV1 by LAs involves PLC and PI(4,5)P2-signalling. In the present study we aimed to characterize essential structural determinants for LA-evoked activation of TRPA1. RESULTS: Recombinant rodent and human TRPA1 were expressed in HEK293t cells and investigated by means of whole-cell patch clamp recordings. The LA lidocaine activates TRPA1 in a concentration-dependent manner. The membrane impermeable lidocaine-derivative QX-314 is inactive when applied extracellularly. Lidocaine-activated TRPA1-currents are blocked by the TRPA1-antagonist HC-030031. Lidocaine is also an inhibitor of TRPA1, an effect that is more obvious in rodent than in human TRPA1. This species-specific difference is linked to the pore region (transmembrane domain 5 and 6) as described for activation of TRPA1 by menthol. Unlike menthol-sensitivity however, lidocaine-sensitivity is not similarly determined by serine- and threonine-residues within TM5. Instead, intracellular cysteine residues known to be covalently bound by reactive TRPA1-agonists seem to mediate activation of TRPA1 by LAs. CONCLUSIONS: The structural determinants involved in activation of TRPA1 by LAs are disparate from those involved in activation by menthol or those involved in activation of TRPV1 by LAs.

TRPA1 and substance P mediate colitis in mice.

BACKGROUND & AIMS: The neuropeptides calcitonin gene-related peptide (CGRP) and substance P, and calcium channels, which control their release from extrinsic sensory neurons, have important roles in experimental colitis. We investigated the mechanisms of colitis in 2 different models, the involvement of the irritant receptor transient receptor potential of the ankyrin type-1 (TRPA1), and the effects of CGRP and substance P. METHODS: We used calcium-imaging, patch-clamp, and neuropeptide-release assays to evaluate the effects of 2,4,6-trinitrobenzene-sulfonic-acid (TNBS) and dextran-sulfate-sodium-salt on neurons. Colitis was induced in wild-type, knockout, and desensitized mice. RESULTS: TNBS induced TRPA1-dependent release of colonic substance P and CGRP, influx of Ca2+, and sustained ionic inward currents in colonic sensory neurons and transfected HEK293t cells. Analysis of mutant forms of TRPA1 revealed that TNBS bound covalently to cysteine (and lysine) residues in the cytoplasmic N-terminus. A stable sulfinic acid transformation of the cysteine-SH group, shown by mass spectrometry, might contribute to sustained sensitization of TRPA1. Mice with colitis had increased colonic neuropeptide release, mediated by TRPA1. Endogenous products of inflammatory lipid peroxidation also induced TRPA1-dependent release of colonic neuropeptides; levels of 4-hydroxy-trans-2-nonenal increased in each model of colitis. Colitis induction by TNBS or dextran-sulfate-sodium-salt was inhibited or reduced in TRPA1-/- mice and by 2-(1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydro-7H-purin-7-yl)-N-(4-isopro-pylphenyl)-acetamide, a pharmacologic inhibitor of TRPA1. Substance P had a proinflammatory effect that was dominant over CGRP, based on studies of knockout mice. Ablation of extrinsic sensory neurons prevented or attenuated TNBS-induced release of neuropeptides and both forms of colitis. CONCLUSIONS: Neuroimmune interactions control intestinal inflammation. Activation and sensitization of TRPA1 and release of substance P induce and maintain colitis in mice.