Characterizing the presentation, management, and clinical outcomes of patients with intradural spinal chordomas: a systematic review.

OBJECTIVE: Chordomas are locally aggressive neoplasms of the spine or skull base that arise from embryonic remnants of the notochord. Intradural chordomas represent a rare subset of these neoplasms, and few studies have described intradural chordomas in the spine. This review evaluates the presentation, management, and outcomes of intradural spinal chordomas. METHODS: A systematic review of PubMed/MEDLINE, EMBASE, Cochrane Library, Scopus, and Web of Science was performed. Studies describing at least 1 case of intradural chordomas anywhere in the spine were included. Extracted details included presenting symptoms, radiological findings, treatment course, follow-up, and disease progression. RESULTS: Thirty-one studies, with a total of 41 patients, were included in this review. Seventy-six percent (31/41) of patients had primary intradural tumors, whereas 24% (10/41) presented with metastasis. The most common signs and symptoms were pain (n = 27, 66%); motor deficits (n = 20, 49%); sensory deficits (n = 17, 42%); and gait disturbance (n = 10, 24%). The most common treatment for intradural chordoma was resection and postoperative radiotherapy. Sixty-six percent (19/29) of patients reported improvement or complete resolution of symptoms after surgery. The recurrence rate was 37% (10/27), and the complication rate was 25% (6/24). The median progression-free survival was 24 months (range 4-72 months). Four patient deaths were reported. The median follow-up time was 12 months (range 13 days-84 months). CONCLUSIONS: Treatment of intradural spinal chordomas primarily involves resection and radiotherapy. A significant challenge and complication in management is spinal tumor seeding after resection, with 9 studies proposing seeding as a mechanism of tumor metastasis in 11 cases. Factors such as tumor size, Ki-67 positivity, and distant metastasis may correlate with worse outcomes and demonstrate potential as prognostic indicators for intradural spinal chordomas. Further research is needed to improve understanding of this tumor and develop optimal treatment paradigms for these patients.

Oncologic and Functional Outcomes After Stereotactic Body Radiation Therapy for High-Grade Malignant Spinal Cord Compression.

Purpose: Although surgical decompression is the gold standard for metastatic epidural spinal cord compression (MESCC) from solid tumors, not all patients are candidates or undergo successful surgical Bilsky downgrading. We report oncologic and functional outcomes for patients treated with stereotactic body radiation therapy (SBRT) to high-grade MESCC. Methods and Materials: Patients with Bilsky grade 2 to 3 MESCC from solid tumor metastases treated with SBRT at a single institution from 2009 to 2020 were retrospectively reviewed. Patients who received upfront surgery before SBRT were included only if postsurgical Bilsky grade remained ≥2. Neurologic examinations, magnetic resonance imaging, pain assessments, and analgesic usage were assessed every 3 to 4 months post-SBRT. Cumulative incidence of local recurrence was calculated with death as a competing risk, and overall survival was estimated by Kaplan-Meier. Results: One hundred forty-three patients were included. The cumulative incidence of local recurrence was 5.1%, 7.5%, and 14.1% at 6, 12, and 24 months, respectively. At first post-SBRT imaging, 16.2% of patients with initial Bilsky grade 2 improved to grade 1, and 53.8% of patients were stable. Five of 13 patients (38.4%) with initial Bilsky grade 3 improved to grade 1 to 2. Pain response at 3 and 6 months post-SBRT was complete in 45.4% and 55.7%, partial in 26.9% and 13.1%, stable in 24.1% and 27.9%, and worse in 3.7% and 3.3% of patients, respectively. At 3 and 6 months after SBRT, 17.8% and 25.0% of patients had improved ambulatory status and 79.7% and 72.4% had stable status. Conclusions: We report the largest series to date of patients with high-grade MESCC treated with SBRT. The excellent local control and functional outcomes suggest SBRT is a reasonable approach in inoperable patients or cases unable to be successfully surgically downgraded.

Association of Neighborhood Socioeconomic Deprivation With Utilization and Costs of Anterior Cervical Discectomy and Fusion.

STUDY DESIGN: A retrospective analysis. OBJECTIVE: The aim of our study was to analyze the association of Area Deprivation Index (ADI) with the utilization and costs of elective anterior cervical discectomy and fusion (ACDF) surgery. SUMMARY OF BACKGROUND DATA: ADI, a comprehensive neighborhood-level measure of socioeconomic disadvantage, has been shown to be associated with worse perioperative outcomes in a variety of surgical settings. MATERIALS AND METHODS: The Maryland Health Services Cost Review Commission Database was queried to identify patients who underwent primary elective ACDF between 2013 and 2020 in the state. Patients were stratified into tertiles by ADI, from least disadvantaged (ADI1) to most disadvantaged (ADI3). The primary endpoints were ACDF utilization rates per 100,000 adults and episode-of-care total costs. Univariable and multivariable regression analyses were performed. RESULTS: A total of 13,362 patients (4984 inpatient and 8378 outpatient) underwent primary ACDF during the study period. In our study, there were 2,401 (17.97%) patients residing in ADI1 neighborhoods (least deprived), 5974 (44.71%) in ADI2, and 4987 (37.32%) in ADI3 (most deprived). Factors associated with increased surgical utilization were increasing ADI, outpatient surgical setting, non-Hispanic ethnicity, current tobacco use, and diagnoses of obesity and gastroesophageal reflux disease. Factors associated with lower surgical utilization were: non-white race, rurality, Medicare/Medicaid insurance status, and diagnoses of cervical disk herniation or myelopathy. Factors associated with higher costs of care were increasing ADI, older age, Black/African American race, Medicare or Medicaid insurance, former tobacco use, and diagnoses of ischemic heart disease and cervical myelopathy. Factors associated with lower costs of care were outpatient surgical setting, female sex, and diagnoses of gastroesophageal reflux disease and cervical disk herniation. CONCLUSIONS: Neighborhood socioeconomic deprivation is associated with increased episode-of-care costs in patients undergoing ACDF surgery. Interestingly, we found greater utilization of ACDF surgery among patients with higher ADI. LEVEL OF EVIDENCE: 3.

Predicting 30-day mortality after surgery for metastatic disease of the spine: the H2-FAILS score.

PURPOSE: Scoring systems for metastatic spine disease focus on predicting long- to medium-term mortality or a combination of perioperative morbidity and mortality. However, accurate prediction of perioperative mortality alone may be the most important factor when considering surgical intervention. We aimed to develop and evaluate a new tool, the H2-FAILS score, to predict 30-day mortality after surgery for metastatic spine disease. METHODS: Using the National Surgical Quality Improvement Program database, we identified 1195 adults who underwent surgery for metastatic spine disease from 2010 to 2018. Incidence of 30-day mortality was 8.7% (n = 104). Independent predictors of 30-day mortality were used to derive the H2-FAILS score. H2-FAILS is an acronym for: Heart failure (2 points), Functional dependence, Albumin deficiency, International normalized ratio elevation, Leukocytosis, and Smoking (1 point each). Discrimination was assessed using area under the receiver operating characteristic curve (AUC). The H2-FAILS score was compared with the American Society of Anesthesiologists Physical Status Classification (ASA Class), the 5-item modified Frailty Index (mFI-5), and the New England Spinal Metastasis Score (NESMS). Internal validation was performed using bootstrapping. Alpha = 0.05. RESULTS: Predicted 30-day mortality was 1.8% for an H2-FAILS score of 0 and 78% for a score of 6. AUC of the H2-FAILS was 0.77 (95% confidence interval: 0.72-0.81), which was higher than the mFI-5 (AUC 0.58, p < 0.001), ASA Class (AUC 0.63, p < 0.001), and NESMS (AUC 0.70, p = 0.004). Internal validation showed an optimism-corrected AUC of 0.76. CONCLUSIONS: The H2-FAILS score accurately predicts 30-day mortality after surgery for spinal metastasis. LEVEL OF EVIDENCE: Prognostic level III.

Inter-neuronal signaling mediated by small extracellular vesicles: wireless communication?

Conventional inter-neuronal communication conceptualizes the wired method of chemical synapses that physically connect pre-and post-synaptic neurons. In contrast, recent studies indicate that neurons also utilize synapse-independent, hence "wireless" broadcasting-type communications via small extracellular vesicles (EVs). Small EVs including exosomes are secreted vesicles released by cells and contain a variety of signaling molecules including mRNAs, miRNAs, lipids, and proteins. Small EVs are subsequently absorbed by local recipient cells via either membrane fusion or endocytic processes. Therefore, small EVs enable cells to exchange a "packet" of active biomolecules for communication purposes. It is now well established that central neurons also secrete and uptake small EVs, especially exosomes, a type of small EVs that are derived from the intraluminal vesicles of multivesicular bodies. Specific molecules carried by neuronal small EVs are shown to affect a variety of neuronal functions including axon guidance, synapse formation, synapse elimination, neuronal firing, and potentiation. Therefore, this type of volume transmission mediated by small EVs is thought to play important roles not only in activity-dependent changes in neuronal function but also in the maintenance and homeostatic control of local circuitry. In this review, we summarize recent discoveries, catalog neuronal small EV-specific biomolecules, and discuss the potential scope of small EV-mediated inter-neuronal signaling.

Early Amnestic Mild Cognitive Impairment Is Associated with Reduced Total Cerebral Blood Flow with no Brain Tissue Loss.

BACKGROUND: Lower cerebral blood flow (CBF) and excessive brain atrophy are linked to Alzheimer's disease (AD). It is still undetermined whether reduced CBF precedes or follows brain tissue loss. OBJECTIVE: We compared total CBF (tCBF), global cerebral perfusion (GCP), and volumes of AD-prone regions between cognitively normal (CN) and early amnestic mild cognitive impairment (aMCI) and tested their associations with cognitive performance to assess their predictive value for differentiation between CN and early aMCI. METHODS: A total of 74 participants (mean age 69.9±6.2 years, 47 females) were classified into two groups: 50 CN and 24 aMCI, of whom 88% were early aMCI. tCBF, GCP, and global and regional brain volumetry were measured using phase-contrast and T1-weighted MRI. Neuropsychological tests tapping global cognition and four cognitive domains (memory, executive function, language, and visuospatial) were administered. Comparisons and associations were investigated using analyses of covariance (ANCOVA) and linear regression analyses, respectively. RESULTS: Women had significantly higher GCP than men. Both, tCBF and GCP were significantly reduced in aMCI compared with CN, while differences in volumes of cerebral gray matter, white matter, and AD-prone regions were not significant. tCBF and GCP were significantly associated with global cognition (standardized beta (stß) = 0.324 and stß= 0.326) and with memory scores (stß≥0.297 and stß≥0.264) across all participants. Associations of tCBF and GCP with memory scores were also significant in CN (stß= 0.327 and stß= 0.284) and in aMCI (stß= 0.627 and stß= 0.485). CONCLUSION: Reduced tCBF and GCP are sensitive biomarkers of early aMCI that likely precede brain tissue loss.

Rapid GPR183-mediated recruitment of eosinophils to the lung after Mycobacterium tuberculosis infection.

Influx of eosinophils into the lungs is typically associated with type II responses during allergy and fungal and parasitic infections. However, we previously reported that eosinophils accumulate in lung lesions during type I inflammatory responses to Mycobacterium tuberculosis (Mtb) in humans, macaques, and mice, in which they support host resistance. Here we show eosinophils migrate into the lungs of macaques and mice as early as one week after Mtb exposure. In mice this influx is CCR3 independent and instead requires cell-intrinsic expression of the oxysterol receptor GPR183, which is highly expressed on human and macaque eosinophils. Murine eosinophils interact directly with bacilli-laden alveolar macrophages, which upregulate the oxysterol-synthesizing enzyme Ch25h, and eosinophil recruitment is impaired in Ch25h-deficient mice. Our findings show that eosinophils are among the earliest cells from circulation to sense and respond to Mtb infection of alveolar macrophages and reveal a role for GPR183 in the migration of eosinophils into lung tissue.

Hydrostatic Pressure Controls Angiogenesis Through Endothelial YAP1 During Lung Regeneration.

Pulmonary artery (PA) pressure increases during lung growth after unilateral pneumonectomy (PNX). Mechanosensitive transcriptional co-activator, yes-associated protein (YAP1), in endothelial cells (ECs) is necessary for angiogenesis during post-PNX lung growth. We investigate whether increases in PA pressure following PNX control-angiogenesis through YAP1. When hydrostatic pressure is applied to human pulmonary arterial ECs (HPAECs), the expression of YAP1, transcription factor TEAD1, and angiogenic factor receptor Tie2 increases, while these effects are inhibited when HPAECs are treated with YAP1 siRNA or YAP1S94A mutant that fails to bind to TEAD1. Hydrostatic pressure also stimulates DNA synthesis, cell migration, and EC sprouting in HPAECs, while YAP1 knockdown or YAP1S94A mutant inhibits the effects. Gene enrichment analysis reveals that the levels of genes involved in extracellular matrix (ECM), cell adhesion, regeneration, or angiogenesis are altered in post-PNX mouse lung ECs, which interact with YAP1. Exosomes are known to promote tissue regeneration. Proteomics analysis reveals that exosomes isolated from conditioned media of post-PNX mouse lung ECs contain the higher levels of ECM and cell-adhesion proteins compared to those from sham-operated mouse lung ECs. Recruitment of host lung ECs and blood vessel formation are stimulated in the fibrin gel containing exosomes isolated from post-PNX mouse lung ECs or pressurized ECs, while YAP1 knockdown inhibits the effects. These results suggest that increases in PA pressure stimulate angiogenesis through YAP1 during regenerative lung growth.

Innovative Biofouling Control for Membrane Bioreactors in Cold Regions by Inducing Environmental Adaptation in Quorum-Quenching Bacteria.

Bacterial quorum quenching (QQ), whose mechanism involves the degradation of quorum-sensing signal molecules, is an effective strategy for controlling biofouling in membrane bioreactors (MBRs). However, MBRs operated at low temperatures, either due to cold climates or seasonal variations, exhibit severe deterioration in QQ efficiency. In this study, a modified culture method for Rhodococcus sp. BH4, a QQ bacterium, was developed to induce environmental adaptation in cold regions. BH4-L, which was prepared by the modified culture method, showed enhancement in QQ efficiency at low temperatures. The higher QQ efficiency obtained by employing BH4-L at 10 °C (compared with that obtained by employing BH4 at 10 °C) was attributed to the higher live/dead cell ratio in the BH4-L-entrapping beads. When BH4-L-entrapping beads were applied to lab-scale MBRs operated at low temperatures, membrane biofouling in MBRs at low temperatures was successfully mitigated because BH4-L could substantially reduce the concentration of signal molecules (N-acyl homoserine lactones) in the biocake. Employing BH4-L in QQ-MBRs could offer a novel solution to the problem of severe membrane biofouling in MBRs in cold regions.

S-SCAM inhibits Axin-dependent synaptic function of GSK3ß in a sex-dependent manner.

S-SCAM/MAGI-2 gene duplication is associated with schizophrenia (SCZ). S-SCAM overexpression in the forebrain induces SCZ-like phenotypes in a transgenic (Tg) mouse model. Interestingly, S-SCAM Tg mice show male-specific impairments in synaptic plasticity and working memory. However, mechanisms underlying the sex-specific deficits remain unknown. Here we report that S-SCAM Tg mice have male-specific deficits in synaptic GSK3ß functions, as shown by reduced synaptic protein levels and increased inhibitory phosphorylation of GSK3ß. This GSK3ß hyper-phosphorylation was associated with increased CaMKII activities. Notably, synaptic levels of Axin1, to which GSK3ß binds in competition with S-SCAM, were also reduced in male S-SCAM Tg mice. We demonstrated that Axin-binding is required for the S-SCAM overexpression-induced synaptic GSK3ß reduction. Axin stabilization using XAV939 rescued the GSK3ß deficits and restored the temporal activation of GSK3ß during long-term depression in S-SCAM overexpressing neurons. Interestingly, synaptic Axin2 levels were increased in female S-SCAM Tg mice. Female sex hormone 17ß-estradiol increased Axin2 expression and increased synaptic GSK3ß levels in S-SCAM overexpressing neurons. These results reveal the role of S-SCAM in controlling Axin-dependent synaptic localization of GSK3ß. Moreover, our studies point out the pathological relevance of GSK3ß hypofunction found in humans and contribute to understanding the molecular underpinnings of sex differences in SCZ.

Structural Basal Ganglia Correlates of Subjective Fatigue in Middle-Aged and Older Adults.

OBJECTIVE: Fatigue is among the most common complaints in community-dwelling older adults, yet its etiology is poorly understood. Based on models implicating frontostriatal pathways in fatigue pathogenesis, we hypothesized that smaller basal ganglia volume would be associated with higher levels of subjective fatigue and reduced set-shifting in middle-aged and older adults without dementia or other neurologic conditions. METHODS: Forty-eight non-demented middle-aged and older adults (Mage = 68.1, SD = 9.4; MMMSE = 27.3, SD = 1.9) completed the Fatigue Symptom Inventory, set-shifting measures, and structural MRI as part of a clinical evaluation for subjective cognitive complaints. Associations were examined cross-sectionally. RESULTS: Linear regression analyses showed that smaller normalized basal ganglia volumes were associated with more severe fatigue (ß = -.29, P = .041) and poorer Trail Making Test B-A (TMT B-A) performance (ß = .30, P = .033) controlling for depression, sleep quality, vascular risk factors, and global cognitive status. Putamen emerged as a key structure linked with both fatigue (r = -.43, P = .003) and TMT B-A (ß = .35, P = .021). The link between total basal ganglia volume and reduced TMT B-A was particularly strong in clinically fatigued patients. CONCLUSION: This study is among the first to show that reduced basal ganglia volume is an important neurostructural correlate of subjective fatigue in physically able middle-aged and older adults without neurological conditions. Findings suggest that fatigue and rapid set-shifting deficits may share common neural underpinnings involving the basal ganglia, and provide a framework for studying the neuropathogenesis and treatment of subjective fatigue.

Poor sleep accelerates hippocampal and posterior cingulate volume loss in cognitively normal healthy older adults.

Poor sleep quality is a known risk factor for Alzheimer's disease. This longitudinal imaging study aimed to determine the acceleration in the rates of tissue loss in cognitively critical brain regions due to poor sleep in healthy elderly individuals. Cognitively-normal healthy individuals, aged ≥60 years, reported Pittsburgh Sleep Quality Index (PSQI) and underwent baseline and 2-year follow-up magnetic resonance imaging brain scans. The links between self-reported sleep quality, rates of tissue loss in cognitively-critical brain regions, and white matter hyperintensity load were assessed. A total of 48 subjects were classified into normal (n = 23; PSQI score <5) and poor sleepers (n = 25; PSQI score ≥5). The two groups were not significantly different in terms of age, gender, years of education, ethnicity, handedness, body mass index, and cognitive performance. Compared to normal sleepers, poor sleepers exhibited much faster rates of volume loss, over threefold in the right hippocampus and fivefold in the right posterior cingulate over 2 years. In contrast, there were no significant differences in the rates of volume loss in the cerebral and cerebellar grey and white matter between the two groups. Rates of volume loss in the right posterior cingulate were negatively associated with global PSQI scores. Poor sleep significantly accelerates volume loss in the right hippocampus and the right posterior cingulate cortex. These findings demonstrate that self-reported sleep quality explains inter-individual differences in the rates of volume loss in cognitively-critical brain regions in healthy older adults and provide a strong impetus to offer sleep interventions to cognitively normal older adults who are poor sleepers.

The effects of genotype on inflammatory response in hippocampal progenitor cells: A computational approach.

Cell culture models are valuable tools to study biological mechanisms underlying health and disease in a controlled environment. Although their genotype influences their phenotype, subtle genetic variations in cell lines are rarely characterised and taken into account for in vitro studies. To investigate how the genetic makeup of a cell line might affect the cellular response to inflammation, we characterised the single nucleotide variants (SNPs) relevant to inflammation-related genes in an established hippocampal progenitor cell line (HPC0A07/03C) that is frequently used as an in vitro model for hippocampal neurogenesis (HN). SNPs were identified using a genotyping array, and genes associated with chronic inflammatory and neuroinflammatory response gene ontology terms were retrieved using the AmiGO application. SNPs associated with these genes were then extracted from the genotyping dataset, for which a literature search was conducted, yielding relevant research articles for a total of 17 SNPs. Of these variants, 10 were found to potentially affect hippocampal neurogenesis whereby a majority (n=7) is likely to reduce neurogenesis under inflammatory conditions. Taken together, the existing literature seems to suggest that all stages of hippocampal neurogenesis could be negatively affected due to the genetic makeup in HPC0A07/03C cells under inflammation. Additional experiments will be needed to validate these specific findings in a laboratory setting. However, this computational approach already confirms that in vitro studies in general should control for cell lines subtle genetic variations which could mask or exacerbate findings.

Poor sleep is associated with small hippocampal subfields in cognitively normal elderly individuals.

Recent studies demonstrated reduced hippocampal volumes in elderly healthy individuals who are cognitively normal but poor sleepers. The association between sleep quality and the pattern of volume loss across hippocampal subfields (HSs) is not well known. Thus, it is the focus of the present study. Sleep quality was self-assessed using the Pittsburgh Sleep Quality Index (PSQI). The HS volumes were measured using sub-millimetre in-plane resolution T2-weighted magnetic resonance imaging data. A total of 67 cognitively normal elderly individuals aged 60-83 years were classified into 30 normal sleepers with a PSQI <5 and 37 poor sleepers with a PSQI ≥5. The two groups were equivalent in age, gender distribution, ethnicity, education attainment, handedness and cognitive performance. Compared to normal sleepers, poor sleepers exhibited significantly lower normalised volumes in the left cornu ammonis field 1 (CA1), dentate gyrus (DG) and subiculum. In contrast, there were no significant differences in normalised grey and white matter volumes between the two groups. The global PSQI was negatively associated with the normalised volumes of the left CA1, DG and subiculum. Sleep duration was associated with the normalised volumes of the bilateral CA1, DG, left CA2 and subiculum. Verbal memory scores were associated with the left CA1 volume. In conclusion, poor sleep quality, especially insufficient sleep duration, was associated with volume loss in several HSs that are involved in specific learning and memory tasks. As the hippocampus does not regulate sleep, it is more likely that poor sleep leads to small hippocampi. Thus, based on this assumption, improving sleep quality of poor sleeper elderly individuals could benefit hippocampal health.

Appropriate Opioid Use After Spine Surgery: Psychobehavioral Barriers and Patient Knowledge.

OBJECTIVE: To identify spine patients' barriers to appropriate postoperative opioid use, comfort with naloxone, knowledge of safe opioid disposal practices, and associated factors. METHODS: We preoperatively surveyed 174 spine patients about psychobehavioral barriers to appropriate opioid use, comfort with naloxone, and knowledge about opioid disposal. Multivariable logistic regression identified factors associated with barriers and knowledge (α = 0.05). RESULTS: Common barriers were fear of addiction (71%) and concern about disease progression (43%). Most patients (78%) had neutral/low confidence in the ability of nonopioid medications to control pain; most (57%) felt neutral or uncomfortable with using naloxone; and most (86%) were familiar with safe disposal. Anxiety was associated with fear of distracting the physician (adjusted odds ratio [aOR], 3.8; 95% confidence interval [CI], 1.1-14) and with lower odds of knowing safe disposal methods (aOR, 0.18; 95% CI, 0.04-0.72). Opioid use during the preceding month was associated with comfort with naloxone (aOR, 4.9; 95% CI, 2.1-12). Patients with a higher educational level had lower odds of reporting fear of distracting the physician (aOR, 0.30; 95% CI, 0.09-0.97), and those with previous postoperative opioid use had lower odds of concern about disease progression (aOR, 0.25; 95% CI, 0.09-0.63) and with a belief in tolerating pain (aOR, 0.34; 95% CI, 0.12-0.95). CONCLUSIONS: Many spine patients report barriers to appropriate postoperative opioid use and are neutral or uncomfortable with naloxone. Some are unfamiliar with safe disposal. Associated factors include anxiety, lack of recent opioid use, and no previous postoperative use.

Comparison of Two Hair Removal Methods in Sprague-Dawley Rats (Rattus norvegicus).

Rats commonly undergo surgery for research purposes. However, the effects of different methods of hair removal on wound healing and surgical site infections (SSI) in rats has not been evaluated. The current study evaluated 2 hair removal methods, clipping with an electric clipper and using a depilatory agent, and their effect on wound healing and SSI. Swabs for bacterial culture were obtained on Day 0 just after hair removal, after aseptic skin preparation, and on Days 1 and 3 before conducting skin biopsies to assess bacterial load and recolonization. Full-thickness punch biopsies were taken for histopathologic evaluation on Days 0, 1, 3, 7, and 10. The surgical incisions were assigned an ASEPSIS score on Days 1 and 3. The data revealed that the bacterial load was significantly higher with the depilatory method as compared with the clipper method, but only on Day 1. The histopathologic evaluation found no significant difference in wound healing between the 2 methods. Although the ASEPSIS score was significantly higher for the clipping method than for the depilatory method on Day 1, both techniques were equivalent by Day 3. We conclude that both hair removal methods are safe and efficacious components of aseptic technique in rats.

Role of the spinal canal compliance in regulating posture-related cerebrospinal fluid hydrodynamics in humans.

Mechanical compliance of a compartment is defined by the change in its volume with respect to a change in the inside pressure. The compliance of the spinal canal regulates the intracranial pressure (ICP) under postural changes. Understanding how gravity affects ICP is beneficial for poorly understood cerebrospinal fluid (CSF)-related disorders. The aim of this study was to evaluate postural effects on cranial hemo- and hydrodynamics. This was a prospective study, which included 10 healthy volunteers (three males, seven females, mean ± standard deviation age: 29 ± 7 years). Cine gradient-echo phase-contrast sequence acquired at 0.5 T, "GE double-doughnut" scanner was used. Spinal contribution to overall craniospinal compliance (CSC), craniospinal CSF stroke volume (SV), magnetic resonance (MR)-derived ICP (MR-ICP), and total cerebral blood flow (TCBF) were measured in supine and upright postures using automated blood and CSF flows quantification. Statistical tests performed were two-sided Student's t-test, Cohen's d, and Pearson correlation coefficient. MR-ICP and the craniospinal CSF SV were significantly correlated with the spinal contribution to the overall CSC (r = 0.83, p < 0.05) and (r = 0.62, p < 0.05), respectively. Cranial contribution to CSC increased from 44.5% ± 16% in supine to 74.9% ± 8.4% in upright posture. The average MR-ICP dropped from 9.9 ± 3.4 mmHg in supine to -3.5 ± 1.5 mmHg. The CSF SV was over 2.5 times higher in the supine position (0.55 ± 0.14 ml) than in the upright position (0.21 ± 0.13 ml). In contrast, TCBF was slightly higher in the supine posture (822 ± 152 ml/min) than in the upright posture (761 ± 139 ml/min), although not statistically significant (p = 0.16). The spinal-canal compliance contribution to CSC is larger than the cranial contribution in the supine posture and smaller in the upright posture. Thereby, the spinal canal plays a role in modulating ICP upon postural changes. The lower pressure craniospinal CSF system was more affected by postural changes than the higher-pressure cerebral vascular system. Craniospinal hydrodynamics is affected by gravity and is likely to be altered by its absence in space. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY STAGE: 2.

Bedside tracheostomy for a COVID-19 cohort.

The use of tracheostomy in ventilator dependent COVID-19 patients is novel because of the recent and rapid spread of this pandemic with risk of transmission of infection to healthcare workers. This case-series of mechanically ventilated COVID-19 patients indicates that percutaneous tracheostomy performed at bedside with careful precautions and limited modification of standard technique was effective in promoting weaning from mechanical ventilation with few complications and no transmission of COVID-19 infection to the procedural healthcare workers.

Machine learning-based estimation of cognitive performance using regional brain MRI markers: the Northern Manhattan Study.

High dimensional neuroimaging datasets and machine learning have been used to estimate and predict domain-specific cognition, but comparisons with simpler models composed of easy-to-measure variables are limited. Regularization methods in particular may help identify regions-of-interest related to domain-specific cognition. Using data from the Northern Manhattan Study, a cohort study of mostly Hispanic older adults, we compared three models estimating domain-specific cognitive performance: sociodemographics and APOE ε4 allele status (basic model), the basic model and MRI markers, and a model with only MRI markers. We used several machine learning methods to fit our regression models: elastic net, support vector regression, random forest, and principal components regression. Model performance was assessed with the RMSE, MAE, and R2 statistics using 5-fold cross-validation. To assess whether prediction models with imaging biomarkers were more predictive than prediction models built with randomly generated biomarkers, we refit the elastic net models using 1000 datasets with random biomarkers and compared the distribution of the RMSE and R2 in models using these random biomarkers to the RMSE and R2 from observed models. Basic models explained ~ 31-38% of the variance in domain-specific cognition. Addition of MRI markers did not improve estimation. However, elastic net models with only MRI markers performed significantly better than random MRI markers (one-sided P < .05) and yielded regions-of-interest consistent with previous literature and others not previously explored. Therefore, structural brain MRI markers may be more useful for etiological than predictive modeling.