Translational evidence for two distinct patterns of neuroaxonal injury in sepsis: a longitudinal, prospective translational study.

BACKGROUND: Brain homeostasis deteriorates in sepsis, giving rise to a mostly reversible sepsis-associated encephalopathy (SAE). Some survivors experience chronic cognitive dysfunction thought to be caused by permanent brain injury. In this study, we investigated neuroaxonal pathology in sepsis. METHODS: We conducted a longitudinal, prospective translational study involving (1) experimental sepsis in an animal model; (2) postmortem studies of brain from patients with sepsis; and (3) a prospective, longitudinal human sepsis cohort study at university laboratory and intensive care units (ICUs). Thirteen ICU patients with septic shock, five ICU patients who died as a result of sepsis, fourteen fluid-resuscitated Wistar rats with fecal peritonitis, eleven sham-operated rats, and three human and four rat control subjects were included. Immunohistologic and protein biomarker analysis were performed on rat brain tissue at baseline and 24, 48, and 72 h after sepsis induction and in sham-treated rats. Immunohistochemistry was performed on human brain tissue from sepsis nonsurvivors and in control patients without sepsis. The clinical diagnostics of SAE comprised longitudinal clinical data collection and magnetic resonance imaging (MRI) and electroencephalographic assessments. Statistical analyses were performed using SAS software (version 9.4; SAS Institute, Inc., Cary, NC, USA). Because of non-Gaussian distribution, the nonparametric Wilcoxon test general linear models and the Spearman correlation coefficient were used. RESULTS: In postmortem rat and human brain samples, neurofilament phosphoform, ß-amyloid precursor protein, ß-tubulin, and H&E stains distinguished scattered ischemic lesions from diffuse neuroaxonal injury in septic animals, which were absent in controls. These two patterns of neuroaxonal damage were consistently found in septic but not control human postmortem brains. In experimental sepsis, the time from sepsis onset correlated with tissue neurofilament levels (R = 0.53, p = 0.045) but not glial fibrillary acidic protein. Of 13 patients with sepsis who had clinical features of SAE, MRI detected diffuse axonal injury in 9 and ischemia in 3 patients. CONCLUSIONS: Ischemic and diffuse neuroaxonal injury to the brain in experimental sepsis, human postmortem brains, and in vivo MRI suggest these two distinct lesion types to be relevant. Future studies should be focused on body fluid biomarkers to detect and monitor brain injury in sepsis. The relationship of neurofilament levels with time from sepsis onset may be of prognostic value. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02442986 . Registered on May 13, 2015.

Serial Measurements of Refractive Index, Glucose and Protein to Assess Gastric Liquid Nutrient Transport-A Proof-of-Principal Study.

Delayed gastric emptying contributes to complications as aspiration or malnutrition. Among patients suffering from acute neurological diseases, motility disorders are prevalent but poorly understood. Thus, methods to measure gastric emptying are required to allow for appropriate adaptions of individual enteral nutrition algorithms. For enterally fed patients repetitive concentration measurements of gastric content have been proposed to assess gastric emptying. This approach can be used to calculate the gastric residual volume (GRV) and transport of nutrition formula (NF), but it has not yet been implemented in clinical routine. The aim of this study was to investigate whether refractometry or other likewise straightforward analytical approaches produce the best results under in vitro conditions mimicking the gastric milieu. We measured NF in different known concentrations, either diluted in water or in simulated gastric fluid (SGF), with each of the following methods: refractometer, handheld glucose meter, and Bradford protein assay. Then, in enterally fed patients suffering from acute neurological disease, we calculated GRVs and nutrition transport and tested possible associations with clinical parameters. In water dilution experiments, NF concentrations could be assessed with the readout parameters of all three methods. Refractometry yielded the most precise results over the broadest range of concentrations and was biased least by the presence of SGF (detection range for Fresubin original fibre, given as volume concentration/normalized error of regression slope after incubation with water or SGF: 0-100 vs. 0-100%/0.5 vs. 3.9%; glucose-measurement: 5-100 vs. 25-100%/7.9 vs. 6.1%; Bradford-assay: 0-100 vs. 0-100%/7.8 vs. 15.7%). Out of 28 enterally fed patients, we calculated significant slower nutrition transport in patients with higher blood glucose (Rho -0.391; p = 0.039) and in patients who received high-dose sufentanil (Rho -0.514; p = 0.005). Also, the calculated nutrition transport could distinguish patients with and without feeding intolerance (Median 6 vs. 17 ml/h; Mann-Whitney test: p = 0.002). The results of our study prove that serial refractometry is a suitable and cost-effective method to assess gastric emptying and to enhance research on gastrointestinal complications of stroke.

Stereotactically Injected Kv1.2 and CASPR2 Antisera Cause Differential Effects on CA1 Synaptic and Cellular Excitability, but Both Enhance the Vulnerability to Pro-epileptic Conditions.

PURPOSE: We present a case of voltage-gated potassium channel (VGKC) complex antibody-positive limbic encephalitis (LE) harboring autoantibodies against Kv1.2. Since the patient responded well to immunotherapy, the autoantibodies were regarded as pathogenic. We aimed to characterize the pathophysiological role of this antibody in comparison to an antibody against the VGKC-associated protein contactin-associated protein-2 (CASPR2). METHODS: Stereotactic injection of patient sera (anti-Kv1.2-associated LE or anti-CASPR2 encephalopathy) and a control subject was performed into the hippocampus of the anesthetized rat in vivo, and hippocampal slices were prepared for electrophysiological purposes. Using extra- and intracellular techniques, synaptic transmission, long-term potentiation (LTP) and vulnerability to pro-epileptic conditions were analyzed. RESULTS: We observed that the slope of the field excitatory postsynaptic potential (fEPSP) was significantly increased at Schaffer collateral-CA1 synapses in anti-Kv1.2-treated and anti-CASPR2-treated rats, but not at medial perforant path-dentate gyrus synapses. The increase of the fEPSP slope in CA1 was accompanied by a decrease of the paired-pulse ratio in anti-Kv1.2, but not in anti-CASPR2 tissue, indicating presynaptic site of anti-Kv1.2. In addition, anti-Kv1.2 tissue showed enhanced LTP in CA1, but dentate gyrus LTP remained unaltered. Importantly, LTP in slices from anti-CASPR2-treated animals did not differ from control values. Intracellular recordings from CA1 neurons revealed that the resting membrane potential and a single action potential were not different between anti-Kv1.2 and control tissue. However, when the depolarization was prolonged, the number of action potentials elicited was reduced in anti-Kv1.2-treated tissue compared to both control and anti-CASPR2 tissue. In contrast, polyspike discharges induced by removal of Mg2+ occurred earlier and more frequently in both patient sera compared to control. CONCLUSION: Patient serum containing anti-Kv1.2 facilitates presynaptic transmitter release as well as postsynaptic depolarization at the Schaffer-collateral-CA1 synapse, but not in the dentate gyrus. As a consequence, both synaptic transmission and LTP in CA1 are facilitated and action potential firing is altered. In contrast, anti-CASPR2 leads to increased postsynaptic potentials, but without changing LTP or firing properties suggesting that anti-Kv1.2 and anti-CASPR2 differ in their cellular effects. Both patient sera alter susceptibility to epileptic conditions, but presumably by different mechanisms.

Correction: The prognostic value of neurofilament levels in patients with sepsis-associated encephalopathy - A prospective, pilot observational study.

[This corrects the article DOI: 10.1371/journal.pone.0211184.].

The prognostic value of neurofilament levels in patients with sepsis-associated encephalopathy - A prospective, pilot observational study.

Sepsis-associated encephalopathy (SAE) contributes to mortality and neurocognitive impairment of sepsis patients. Neurofilament (Nf) light (NfL) and heavy (NfH) chain levels as biomarkers for neuroaxonal injury were not evaluated in cerebrospinal fluid (CSF) and plasma of patients with sepsis-associated encephalopathy (SAE) before. We conducted a prospective, pilot observational study including 20 patients with septic shock and five patients without sepsis serving as controls. The assessment of SAE comprised a neuropsychiatric examination, electroencephalography (EEG), magnetic resonance imaging (MRI) and delirium screening methods including the confusion assessment method for the ICU (CAM-ICU) and the intensive care delirium screening checklist (ICDSC). CSF Nf measurements in sepsis patients and longitudinal plasma Nf measurements in all participants were performed on days 1, 3 and 7 after study inclusion. Plasma NfL levels increased in sepsis patients over time (p = 0.0063) and remained stable in patients without sepsis. Plasma NfL values were significantly higher in patients with SAE (p = 0.011), significantly correlated with the severity of SAE represented by ICDSC values (R = 0.534, p = 0.022) and correlated with a poorer functional outcome after 100 days (R = -0.535, p = 0.0003). High levels of CSF Nf were measured in SAE patients. CSF NfL levels were higher in non-survivors (p = 0.012) compared with survivors and correlated with days until death (R = -0.932, p<0.0001) and functional outcome after 100 days (R = -0.749, p<0.0001). The present study showed for the first time that Nf levels provide complementary prognostic information in SAE patients indicating a higher chance of death and poorer functional/cognitive outcome in survivors.

Clinical nutrition and gastrointestinal dysfunction in critically ill stroke patients.

Background Data on the epidemiology and risk factors of altered gastrointestinal motility (AGIM) is virtually lacking for patients suffering from non-traumatic neurologic diseases and stroke. This study investigated whether patterns of AGIM differ between patients with stroke and other severe acute brain diseases. Methods Clinical records of stroke and non-stroke patients treated at a neurological intensive care unit (ICU) were reviewed at day 1-5 and at day 10 after admission. The data was analyzed for the course of enteral/parenteral nutrition and for and for signs and symptoms of gastrointestinal dysfunction. The study included data of 76 patients, 57 with stroke (stroke group, SG) and 19 with other neurological diseases (non-stroke group, NSG). Results Basic demographic as well as clinical baseline characteristics and alimentation regime were similar in both groups. At least one sign of AGIM was seen in 33/57 (58%) SG and in 15/19 (79%) NSG patients (P = 0.099). Regurgitation was significantly more frequent among patients from the NSG (P < 0.05). Subjects from the NSG also spent a higher proportion of time with at least one symptom of AGIM present (P < 0.05). Conclusions For the first time, this study investigated the prevalence of AGIM in patients suffering from severe stroke. The prevalence of disturbed gastrointestinal function was found to be high in stroke patients, but was lower than in a group of non-stroke patients with similar general disease severity and baseline characteristics.