Characterization of Calpain and Caspase-6-Generated Glial Fibrillary Acidic Protein Breakdown Products Following Traumatic Brain Injury and Astroglial Cell Injury.

Glial fibrillary acidic protein (GFAP) is the major intermediate filament III protein of astroglia cells which is upregulated in traumatic brain injury (TBI). Here we reported that GFAP is truncated at both the C- and N-terminals by cytosolic protease calpain to GFAP breakdown products (GBDP) of 46-40K then 38K following pro-necrotic (A23187) and pro-apoptotic (staurosporine) challenges to primary cultured astroglia or neuron-glia mixed cells. In addition, with another pro-apoptotic challenge (EDTA) where caspases are activated but not calpain, GFAP was fragmented internally, generating a C-terminal GBDP of 20 kDa. Following controlled cortical impact in mice, GBDP of 46-40K and 38K were formed from day 3 to 28 post-injury. Purified GFAP protein treated with calpain-1 and -2 generates (i) major N-terminal cleavage sites at A-56*A-61 and (ii) major C-terminal cleavage sites at T-383*Q-388, producing a limit fragment of 38K. Caspase-6 treated GFAP was cleaved at D-78/R-79 and D-225/A-226, where GFAP was relatively resistant to caspase-3. We also derived a GBDP-38K N-terminal-specific antibody which only labels injured astroglia cell body in both cultured astroglia and mouse cortex and hippocampus after TBI. As a clinical translation, we observed that CSF samples collected from severe human TBI have elevated levels of GBDP-38K as well as two C-terminally released GFAP peptides (DGEVIKES and DGEVIKE). Thus, in addition to intact GFAP, both the GBDP-38K as well as unique GFAP released C-terminal proteolytic peptides species might have the potential in tracking brain injury progression.

The diagnostic values of UCH-L1 in traumatic brain injury: A meta-analysis.

Traumatic brain injury (TBI) is a major health concern. The purpose of this study is to identify the diagnostic accuracy of ubiquitin C-terminal hydrolase-L1 (UCH-L1)-a protein biomarker-in comparison with CT-scan findings post-TBI. Accordingly, we conducted a systematic review of eligible studies and assessed the risk of bias according to the QUADAS-2 checklist. A total of 13 reports from 10 original studies were included. Based on our analysis, serum UCH-L1 has a high accuracy in predicting CT findings in mild to moderate TBI. Based on the QUADAS-2 checklist, this result has a high risk of bias affecting its applicability. The plasma level of UCH-L1 has moderate accuracy in predicting CT findings when assessed in all GCS levels. This result has a low risk of bias and low concerns regarding applicability. Pooled analysis suggests that the plasma/serum UCH-L1 level has high accuracy in predicting CT findings in a wide range of GCS in patients with TBI. This result has a high risk of bias and high concern about its applicability. The heterogeneity in approaching TBI biomarker interferes with drawing a definitive conclusion. Therefore, although UCH-L1 is a promising blood-based diagnostic biomarker for TBI, but due to differences in reported diagnostic accuracy, further studies are needed to recommend UCH-L1 as an alternative to CT scanning.

Degree of Uncertainty in Reporting Imaging Findings for Necrotizing Enterocolitis: A Secondary Analysis from a Pilot Randomized Diagnostic Trial.

Diagnosis of necrotizing enterocolitis (NEC) relies heavily on imaging, but uncertainty in the language used in imaging reports can result in ambiguity, miscommunication, and potential diagnostic errors. To determine the degree of uncertainty in reporting imaging findings for NEC, we conducted a secondary analysis of the data from a previously completed pilot diagnostic randomized controlled trial (2019-2020). The study population comprised sixteen preterm infants with suspected NEC randomized to abdominal radiographs (AXRs) or AXR + bowel ultrasound (BUS). The level of uncertainty was determined using a four-point Likert scale. Overall, we reviewed radiology reports of 113 AXR and 24 BUS from sixteen preterm infants with NEC concern. The BUS reports showed less uncertainty for reporting pneumatosis, portal venous gas, and free air compared to AXR reports (pneumatosis: 1 [1-1.75) vs. 3 [2-3], p < 0.0001; portal venous gas: 1 [1-1] vs. 1 [1-1], p = 0.02; free air: 1 [1-1] vs. 2 [1-3], p < 0.0001). In conclusion, we found that BUS reports have a lower degree of uncertainty in reporting imaging findings of NEC compared to AXR reports. Whether the lower degree of uncertainty of BUS reports positively impacts clinical decision making in infants with possible NEC remains unknown.

Temporal Profile and Severity Correlation of a Panel of Rat Spinal Cord Injury Protein Biomarkers.

In the USA, there are approximately 12,000 new cases of spinal cord injury (SCI) each year and some 1.2 million people living with paralysis due to SCI. Seven percent of them are paralyzed due to an accident or injury occurring while serving in the military. Here, we report a systematic study on protein biomarker candidates in a rat SCI model with either moderate or severe injury. Tissue, cerebrospinal fluid (CSF), and serum samples were obtained at 4 h, 24 h, and 7 days post-injury. The candidate biomarkers included axonal injury markers αII-spectrin breakdown products (SBDP150/145/120), neuronal cell body injury marker ubiquitin C-terminal hydrolase-L1 (UCH-L1), astrogliosis/astroglial injury markers S100 calcium-binding protein-ß (S100ß), glial fibrillary acidic protein (GFAP) and GFAP breakdown products (GBDPs), demyelination marker myelin basic protein (MBP), axonal injury marker phosphorylated neurofilament-H (pNF-H), and neuroinflammation marker interleukin-6 (IL-6). SBDP150/145, UCH-L1, GFAP, and S100ß were found as acute biomarkers with significantly elevated levels within 24 h. GBDP44, GBDP38, and pNF-H are acute and subacute biomarkers that were found to have increased at 4 h, 24 h, and 7 days. MBP and SBDP120 were considered subacute biomarkers which were only detectable at 7 days post-injury. These results not only allow us to gain important insight into the patho-mechanisms of SCI but also showcase the possibility of using some of the protein biomarkers to track injury severity and disease progression and resolution. These biomarkers can potentially serve as tools that assist therapy development and clinical trials.