Clinical Relevance and Role of Neuronal AT1 Receptors in ADAM17-Mediated ACE2 Shedding in Neurogenic Hypertension.

RATIONALE: Neurogenic hypertension is characterized by an increase in sympathetic activity and often resistance to drug treatments. We previously reported that it is also associated with a reduction of angiotensin-converting enzyme type 2 (ACE2) and an increase in a disintegrin and metalloprotease 17 (ADAM17) activity in experimental hypertension. In addition, while multiple cells within the central nervous system have been involved in the development of neurogenic hypertension, the contribution of ADAM17 has not been investigated. OBJECTIVE: To assess the clinical relevance of this ADAM17-mediated ACE2 shedding in hypertensive patients and further identify the cell types and signaling pathways involved in this process. METHODS AND RESULTS: Using a mass spectrometry-based assay, we identified ACE2 as the main enzyme converting angiotensin II into angiotensin-(1-7) in human cerebrospinal fluid. We also observed an increase in ACE2 activity in the cerebrospinal fluid of hypertensive patients, which was correlated with systolic blood pressure. Moreover, the increased level of tumor necrosis factor-α in those cerebrospinal fluid samples confirmed that ADAM17 was upregulated in the brain of hypertensive patients. To further assess the interaction between brain renin-angiotensin system and ADAM17, we generated mice lacking angiotensin II type 1 receptors specifically on neurons. Our data reveal that despite expression on astrocytes and other cells types in the brain, ADAM17 upregulation during deoxycorticosterone acetate-salt hypertension occurs selectively on neurons, and neuronal angiotensin II type 1 receptors are indispensable to this process. Mechanistically, reactive oxygen species and extracellular signal-regulated kinase were found to mediate ADAM17 activation. CONCLUSIONS: Our data demonstrate that angiotensin II type 1 receptors promote ADAM17-mediated ACE2 shedding in the brain of hypertensive patients, leading to a loss in compensatory activity during neurogenic hypertension.

The Effects of Agrin Isoforms on Diabetic Neuropathic Pain in a Rat Streptozotocin Model.

BACKGROUND: Diabetes mellitus affects 9.3% of the US population and increases risks of surgery and complications. Diabetic neuropathic pain (DNP), one of the main consequences of diabetes mellitus, is extremely difficult to treat. Current medications yield limited benefits and/or have severe adverse effects. Therefore, new, effective treatment is needed. METHODS: Streptozotocin at 55 mg/kg was injected intraperitoneally in rats to induce diabetes mellitus. Diabetic rats exhibiting neuropathic pain underwent intrathecal injection of purified agrin proteins at various doses and were then tested for tactile allodynia to evaluate whether DNP was inhibited. The agrin effects were also analyzed with patch-clamp recording on spinal cord slices. RESULTS: Fifty-kilo Dalton agrin (Agr50) at 0.2 and 2 ng suppressed DNP when given intrathecally, while 25- and 75-kDa agrin (Agr25, Agr75) had little effect. The suppressive effect of Agr50 lasted 4 hours after a single bolus injection. The difference in effects of Agr50 on mean withdrawal threshold (4.6 ± 2.2 g before treatment to 26 ± 0 g after treatment) compared with that of Agr25 (4.9 ± 2.0 g to 4.9 ± 2.0 g) and Agr75 (5.3 ± 2.3 g to 9.2 ± 2.5 g) was highly significant (P < .01). On spinal cord slices, Agr50 increased spontaneous GABAergic current activities, suggesting increased spontaneous inhibitory postsynaptic currents and action potential firing rate from GABA neurons, whereas Agr25 and Agr75 had no such effect. CONCLUSIONS: Agr50 had a potent suppressive effect on DNP and increased spontaneous inhibitory postsynaptic currents and action potential firing rate from GABA neurons. Therefore, Agr50 may provide a potential therapy for DNP.

Clinical, radiological, and laboratory factors associated with mortality and functional outcomes in pediatric patients presenting with intracranial gunshot wounds.

OBJECTIVE: Firearm injuries are now the leading cause of death in children and young adults younger than 25 years of age in the US. Current management of these injuries is extrapolated from adult blunt and penetrating traumatic brain injury guidelines. The objectives of this study were to investigate and analyze the clinical, radiological, and laboratory factors associated with mortality and functional outcomes in pediatric patients presenting with intracranial gunshot wounds (GSWs). METHODS: Medical records were screened for all patients younger than 21 years of age with an intracranial GSW who presented to the University Medical Center in New Orleans, Louisiana, from 2012 to 2022. Demographics and radiological, clinical, and laboratory data were extracted, and chi-square and Fisher's exact tests were used to evaluate individual association with mortality and functional outcome. Odds ratios were calculated from the cross tabulations for categorical variables and univariate binary logistic regression models for continuous variables. Multivariate binary logistic regression was used to adjust for effects of covariates and isolate the contributions of predictor variables for mortality and functional outcome. RESULTS: Ninety-six patients (82 male, 14 female) had a median age of 18 (interquartile range [IQR] 15-20) years. The 30-day inpatient, 60-day, and 6-month mortality rates among these patients were 53.1%, 0%, and 2.4%, respectively. Those who died were more likely to have an initial Glasgow Coma Scale score ≤ 8 (p < 0.001), bilateral fixed pupils (p < 0.001), transventricular trajectory (p < 0.001), deep nuclear/third ventricle involvement (p = 0.004), bihemispheric trajectory (p = 0.025), injury to ≥ 3 lobes (p = 0.015), parietal lobe involvement (p = 0.023), base deficit < -5 mEq/L (p = 0.013), international normalized ratio (INR) > 1.5 (p = 0.007), and a St. Louis Scale (SLS) score ≥ 5 (p < 0.001). The survivors with favorable functional outcome were more likely to have lower median SLS scores (p = 0.016) and injury to < 3 lobes (p < 0.001). In a multivariate analysis, bilaterally fixed nonreactive pupils were positively associated with mortality and negatively associated with favorable functional outcome, whereas the Injury Severity Score (ISS) and injury to ≥ 3 lobes were negatively associated with favorable functional outcome only. CONCLUSIONS: This is one of the largest series of pediatric intracranial GSWs to date. The authors identified certain clinical (bilateral fixed pupils, SLS score ≥ 5, ISS > 16), laboratory (INR > 1.5, base deficit < -5 mEq/L), and radiological (transventricular trajectory, deep nuclear/third ventricle involvement, parietal lobe involvement) factors that were associated with death and poor functional outcome in this pediatric cohort.

Neurofilament Light (NF-L) Chain Protein from a Highly Polymerized Structural Component of the Neuronal Cytoskeleton to a Neurodegenerative Disease Biomarker in the Periphery.

Neurofilaments (NFs) are critical scaffolding components of the axoskeleton of healthy neurons interacting directly with multiple synaptic-phosphoproteins to support and coordinate neuronal cell shape, cytoarchitecture, synaptogenesis and neurotransmission. While neuronal presynaptic proteins such as synapsin-2 (SYN II) degrade rapidly via the ubiquitin-proteasome pathway, a considerably more stable neurofilament light (NF-L) chain protein turns over much more slowly, and in several neurological diseases is accompanied by a pathological shift from an intracellular neuronal cytoplasmic location into various biofluid compartments. NF-L has been found to be significantly elevated in peripheral biofluids in multiple neurodegenerative disorders, however it is not as widely appreciated that NF-L expression within neurons undergoing inflammatory neurodegeneration exhibit a significant down-regulation in these neuron-specific intermediate-filament components. Down-regulated NF-L in neurons correlates well with the observed axonal and neuronal atrophy, neurite deterioration and synaptic disorganization in tissues affected by Alzheimer's disease (AD) and other progressive, age-related neurological diseases. This Review paper: (i) will briefly assess the remarkably high number of neurological disorders that exhibit NF-L depolymerization, liberation from neuron-specific compartments, mobilization and enrichment into pathological biofluids; (ii) will evaluate how NF-L exhibits compartmentalization effects in age-related neurological disorders; (iii) will review how the shift of NF-L compartmentalization from within the neuronal cytoskeleton into peripheral biofluids may be a diagnostic biomarker for neuronal-decline in all cause dementia most useful in distinguishing between closely related neurological disorders; and (iv) will review emerging evidence that deficits in plasma membrane barrier integrity, pathological transport and/or vesicle-mediated trafficking dysfunction of NF-L may contribute to neuronal decline, with specific reference to AD wherever possible.

Management of cerebrospinal fluid leak from cervical gunshot wounds with external ventricular drainage: a small case series.

Historically, the surgical management of gunshot wounds to the spine has been controversial. Repair of a persistent cerebrospinal fluid (CSF) leak is a generally agreed upon indication. The management of such CSF leaks typically involves lumbar drainage or direct surgical repair. Here, the authors report two cases of CSF diversion with an external ventricular drain (EVD) in patients with cervical gunshot wounds. Both patients had spinal canal obliteration or physiologic myelographic block at or below the level of injury. To the best of the author's knowledge, these are the first two reports of successful EVD treatment of persistent CSF leaks related cervical gunshot wounds. The authors also propose a CSF treatment algorithm for cervical gunshot wounds that includes EVD.

The Impact of Drug and Alcohol Intoxication on Glasgow Coma Scale Assessment in Patients with Traumatic Brain Injury.

BACKGROUND: The effect of intoxicating substances on assessment of Glasgow Coma Scale (GCS) in the trauma setting has not been completely elucidated. METHODS: A trauma registry was queried for patients with blunt head trauma in 2013-2017. Initial GCS score and toxicology screening from the database were reviewed. Next recorded GCS score from the neurosurgery evaluation and change in GCS score (ΔGCS) were compared. RESULTS: We reviewed 468 patients. In 217 (46.4%) patients, no toxic substances were found, whereas >1 toxic substance was found in 104 (22.2%) patients. Alcohol level above the legal limit was found in 109 (23.3%) patients, marijuana was found in 105 (22.4%) patients, benzodiazepines were found in 94 (20.1%) patients, opiates were found in 48 (10.3%) patients, and cocaine was found in 41 (8.8%) patients. Mean change in GCS score was significantly higher in impaired patients compared with patients with a negative screening test (1.74 ± 2.4 vs. 0.75 ± 2.7, P < 0.001); this is despite both groups having a similar initial GCS score (6.23 ± 3.86 in impaired group vs. 6.47 ± 3.52 in sober group, P = 0.677). Initial GCS score was 3 in 187 patients, of whom 150 had a positive toxicology screen. Change in GCS score was significantly higher in the impaired group (2.75 ± 2.7 vs. 1.19 ± 1.8, P < 0.001). CONCLUSIONS: Intoxicating substances can confound GCS assessment in trauma patients. This can have effects on patient care as well as performance metrics and predictive analytics. These patients should be screened, and intoxicating substances should be reversed or allowed to wear off before GCS score is recorded for benchmarking or quality reporting.

Change in Policy Allowing Overlapping Surgery Decreases Length of Stay in an Academic, Safety-Net Hospital.

BACKGROUND: The practice of surgeons running overlapping operating rooms has recently come under scrutiny. OBJECTIVE: To examine the impact of hospital policy allowing overlapping rooms in the case of patients admitted to a tertiary care, safety-net hospital for urgent neurosurgical procedures. METHODS: The neurosurgery service at the hospital being studied transitioned from routinely allowing 1 room per day (period 1) to overlapping rooms (period 2), with the second room being staffed by the same attending surgeon. Patients undergoing neurosurgical intervention in each period were retrospectively compared. Demographics, indication, case type, complications, outcomes, and total charges were tracked. RESULTS: There were 59 urgent cases in period 1 and 63 in period 2. In the case of these patients, the length of stay was significantly decreased in period 2 (13.09 d vs 19.52; P = .006). The time from admission to surgery (wait time) was also significantly decreased in period 2 (5.12 d vs 7.00; P = .04). Total charges also trended towards less in period 2 (${\$}$150 942 vs ${\$}$200 075; P = .05). Surgical complications were no different between the groups (16.9% vs 14.3%; P = .59), but medical complications were significantly decreased in period 2 (14.3% vs 30.5%; P = .009). Significantly more patients were discharged to home in period 2 (69.8% vs 42.4%; P = .003). CONCLUSION: As a matter of policy, allowing overlapping rooms significantly reduces the length of stay in the case of a vulnerable population in need of urgent surgery at a single safety-net academic institution. This may be due to a reduction in medical complications in these patients.

Aluminum in neurological disease - a 36 year multicenter study.

Aluminum is a ubiquitous neurotoxin highly enriched in our biosphere, and has been implicated in the etiology and pathology of multiple neurological diseases that involve inflammatory neural degeneration, behavioral impairment and cognitive decline. Over the last 36 years our group has analyzed the aluminum content of the temporal lobe neocortex of 511 high quality coded human brain samples from 18 diverse neurological and neurodegenerative disorders, including 2 groups of age-matched controls. Brodmann anatomical areas including the inferior, medial and superior temporal gyrus (A20-A22) were selected for analysis: (i) because of their essential functions in massive neural information processing operations including cognition and memory formation; and (ii) because subareas of these anatomical regions are unique to humans and are amongst the earliest areas affected by progressive neurodegenerative disorders such as Alzheimer's disease (AD). Coded brain tissue samples were analyzed using the analytical technique of: (i) Zeeman-type electrothermal atomic absorption spectrophotometry (ETAAS) combined with (ii) an experimental multi-elemental analysis using the advanced photon source (APS) ultra-bright storage ring-generated hard X-ray beam (7 GeV) and fluorescence raster scanning (XRFR) spectroscopy device at the Argonne National Laboratory, US Department of Energy, University of Chicago IL, USA. These data represent the largest study of aluminum concentration in the brains of human neurological and neurodegenerative disease ever undertaken. Neurological diseases examined were AD (N=186), ataxia Friedreich's type (AFT; N=6), amyotrophic lateral sclerosis (ALS; N=16), autism spectrum disorder (ASD; N=26), dialysis dementia syndrome (DDS; N=27), Down's syndrome (DS; trisomy21; N=24), Huntington's chorea (HC; N=15), multiple infarct dementia (MID; N=19), multiple sclerosis (MS; N=23), Parkinson's disease (PD; N=27), prion disease (PrD; N=11) including bovine spongiform encephalopathy (BSE; 'mad cow disease'), Creutzfeldt-Jakob disease (CJD) and Gerstmann-Straussler-Sheinker syndrome (GSS), progressive multifocal leukoencephalopathy (PML; N=11), progressive supranuclear palsy (PSP; N=24), schizophrenia (SCZ; N=21), a young control group (YCG; N=22) and an aged control group (ACG; N=53). Amongst these 18 common neurological conditions and controls we report a statistically significant trend for aluminum to be increased only in AD, DS and DDS compared to age- and gender-matched brains from the same anatomical region. The results continue to suggest that aluminum's association with AD, DDS and DS brain tissues may contribute to the neuropathology of these neurological diseases but appear not to be a significant factor in other common disorders of the human central nervous system (CNS).

Upregulation of beta-amyloid precursor protein expression in glioblastoma multiforme.

Glioma and glioblastoma multiforme constitute rapidly proliferating glial cell tumors whose pathogenic mechanisms are not well understood. This study examined proinflammatory and neurodegenerative gene expression in five American Tissue Culture Collection glioma and glioblastoma multiforme tumor cell lines and in 14 glioma and glioblastoma samples obtained from human brain biopsy. Expression of the low-abundance cyclooxygenase-1 and the high-abundance cytoskeletal element beta-actin were found not to significantly change in any cells or tissues studied and were used as internal controls. In contrast, proinflammatory cyclooxygenase-2, cytosolic phospholipase A2, IL-1beta, and beta-amyloid precursor protein expression levels were found to be significantly upregulated. These studies suggest that glioma and glioblastoma exhibit robust upregulation of proinflammatory and neurodegenerative genetic markers that may contribute to the pathobiology, phenotype, and proliferation of glial cell growth.

Analysis of RNA from Alzheimer's Disease Post-mortem Brain Tissues.

Alzheimer's disease (AD) is a uniquely human, age-related central nervous system (CNS) disorder for which there is no adequate experimental model. While well over 100 transgenic murine models of AD (TgAD) have been developed that recapitulate many of the neuropathological features of AD, key pathological features of AD such as progressive neuronal atrophy, neuron cell loss, and neurofibrillary tangle (NFT) formation have not been observed in any TgAD model to date. To more completely analyze and understand the neuropathology, altered neuro-inflammatory and innate-immune signaling pathways, and the complex molecular-genetics and epigenetics of AD, it is therefore necessary to rigorously examine short post-mortem interval (PMI) human brain tissues to gain a deeper and more thorough insight into the neuropathological mechanisms that characterize the AD process. This perspective-methods paper will highlight some important recent findings on the utilization of short PMI tissues in sporadic (idiopathic; of unknown origin) AD research with focus on the extraction and quantification of RNA, and in particular microRNA (miRNA) and messenger RNA (mRNA) and analytical strategies, drawing on the authors' combined 125 years of laboratory experience into this investigative research area. We sincerely hope that new investigators in the field of "gene expression analysis in neurological disease" will benefit from the observations presented here and incorporate these recent findings and observations into their future experimental planning and design.

Molecular mechanisms of fenofibrate-induced metabolic catastrophe and glioblastoma cell death.

Fenofibrate (FF) is a common lipid-lowering drug and a potent agonist of the peroxisome proliferator-activated receptor alpha (PPARα). FF and several other agonists of PPARα have interesting anticancer properties, and our recent studies demonstrate that FF is very effective against tumor cells of neuroectodermal origin. In spite of these promising anticancer effects, the molecular mechanism(s) of FF-induced tumor cell toxicity remains to be elucidated. Here we report a novel PPARα-independent mechanism explaining FF's cytotoxicity in vitro and in an intracranial mouse model of glioblastoma. The mechanism involves accumulation of FF in the mitochondrial fraction, followed by immediate impairment of mitochondrial respiration at the level of complex I of the electron transport chain. This mitochondrial action sensitizes tested glioblastoma cells to the PPARα-dependent metabolic switch from glycolysis to fatty acid ß-oxidation. As a consequence, prolonged exposure to FF depletes intracellular ATP, activates the AMP-activated protein kinase-mammalian target of rapamycin-autophagy pathway, and results in extensive tumor cell death. Interestingly, autophagy activators attenuate and autophagy inhibitors enhance FF-induced glioblastoma cytotoxicity. Our results explain the molecular basis of FF-induced glioblastoma cytotoxicity and reveal a new supplemental therapeutic approach in which intracranial infusion of FF could selectively trigger metabolic catastrophe in glioblastoma cells.

Selective accumulation of aluminum in cerebral arteries in Alzheimer's disease (AD).

Once biologically available aluminum bypasses gastrointestinal and blood-brain barriers, this environmentally-abundant neurotoxin has an exceedingly high affinity for the large pyramidal neurons of the human brain hippocampus. This same anatomical region of the brain is also targeted by the earliest evidence of Alzheimer's disease (AD) neuropathology. The mechanism for the selective targeting and transport of aluminum into the hippocampus of the human brain is not well understood. In an effort to improve our understanding of a pathological aluminum entry system into the brain, this study examined the aluminum content of 8 arteries that supply blood to the hippocampus, including the aorta and several cerebral arteries. In contrast to age-matched controls, in AD patients we found a gradient of increasing aluminum concentration from the aorta to the posterior cerebral artery that supplies blood to the hippocampus. Primary cultures of human brain endothelial cells were found to have an extremely high affinity for aluminum when compared to other types of brain cells. Together, these results suggest for the first time that endothelial cells that line the cerebral vasculature may have biochemical attributes conducive to binding and targeting aluminum to selective anatomical regions of the brain, such as the hippocampus, with potential downstream pro-inflammatory and pathogenic consequences.