Exercise and Recovery Following Mild-to-Moderate Traumatic Brain Injury in the Community Setting.

Introduction The recommendations on return to exercise post-traumatic brain injury (TBI) remain debatable. As recent as 10 years ago, the conventional recovery modality for a mild TBI was to reduce neurostimulating activity and encourage rest until the symptoms subsided. However, emerging literature has challenged this notion, stating that returning to exercise early in the course of mild TBI recovery may be beneficial to the recovery timeline. This study surveys Hawaii's diverse population to identify trends in exercise and recovery for TBI patients to shape recommendations on return to exercise. Methods A single-center retrospective chart review of the patients with mild-to-moderate TBI was selected from a patient database at an outpatient neurology clinic between January 2020 and January 2022. The variables collected include demographics, the etiology of injury, and symptoms at diagnosis. Self-generated phone surveys were completed to evaluate exercise patterns post-TBI. Results The patients who recovered within two years displayed similar exercise patterns to the patients who took more than two years to recover. Exercise frequency, intensity, and duration did not differ significantly (p=0.75, p=0.51, and p=0.80, respectively; n=100). Hiking and walking were more common in the long recovery (LR) group (p=0.02), likely reflecting advanced age compared to the short recovery (SR) group (50 versus 39 years, p<0.01). Additionally, no correlation exists between exercise intensity and worsening symptoms (p=0.920), suggesting that the patients exhibit exercise patterns suitable for sub-symptomatic recovery. Conclusion Return to exercise does not appear to be a predictor for mild-to-moderate TBI recovery. The patients appear to self-regulate an exercise regimen that will not exacerbate their symptoms or recovery time; thus, it may be suitable to recommend return to exercise as tolerated. These, and other findings in the literature, suggest that patients should be encouraged to return to exercise shortly after a mild TBI so long as the exercise does not exacerbate their symptoms.

Barriers to Alzheimer Disease Clinical Trial Participation in a Minority Population.

BACKGROUND: Alzheimer disease (AD), the most common neurodegenerative disorder in the United States, disproportionately burdens minority populations. OBJECTIVE: To explore barriers to AD clinical trial participation by Asian and Native Hawaiian patients diagnosed with AD or mild cognitive impairment. METHOD: We surveyed 187 patients with a Mini-Mental State Examination score ≥14 between January 2022 and June 2022. The score cutoff for clinical trial eligibility was set by the institution. Individuals also completed a 15-question telephone survey that assessed demographics, barriers to clinical trial participation, and clinical trial improvement methods. RESULTS: Forty-nine patients responded, with a response rate of 26%. Asian and Native Hawaiian patients were less likely than White patients to participate in AD trials. The main barrier to participation was a lack of information about AD trials. Providing additional information regarding AD trials to patients and family members were listed as the top two reasons patients would consider participating in a clinical trial. CONCLUSION: Insufficient information about AD clinical trials is the primary barrier to participation among Asian and Native Hawaiian patients, followed by difficulty coordinating transportation and, in the case of Asians, the time required for clinical trials. Increased outreach, education, and assistance with logistics in these populations should be pursued to improve rates of participation in clinical trials.

Correlation Between Intracranial Calcification and Extracranial Stenosis of the Internal Carotid Artery.

Intracranial artery calcification is a marker of vascular atherosclerosis and has a high prevalence worldwide. Both atherosclerosis of the internal carotid artery at the carotid sinus in the neck and intracranial calcification have been associated with ischemic stroke. The relationship between the two has not been well studied. The present study investigated how carotid sinus narrowing could relate to calcification located in the distal intracranial artery at the cavernous carotid. We examined a population not selected for cerebral disease. This retrospective study contained 179 subjects aged 18 years and older from the Hawaii Diagnostic Radiology database. Extracranial internal carotid artery stenosis was determined using the absolute diameter, North American Symptomatic Carotid Endarterectomy Trial, and common carotid artery methods. Calcification was scored using the modified Woodcock method. A positive correlation between intracranial calcification and extracranial carotid stenosis was found using all three methods. Individuals with intracranial calcification were more likely to be older, have a smaller internal carotid artery diameter, and have a greater percent stenosis at the internal carotid artery than those without intracranial artery calcification (p<0.001 for all). These results may help refocus interest in calcification in studies of cerebral vasculature and its correlation with extracranial carotid stenosis.

Consequences of PDGFRα+ fibroblast reduction in adult murine hearts.

Fibroblasts produce the majority of collagen in the heart and are thought to regulate extracellular matrix (ECM) turnover. Although fibrosis accompanies many cardiac pathologies and is generally deleterious, the role of fibroblasts in maintaining the basal ECM network and in fibrosis in vivo is poorly understood. We genetically ablated fibroblasts in mice to evaluate the impact on homeostasis of adult ECM and cardiac function after injury. Fibroblast-ablated mice demonstrated a substantive reduction in cardiac fibroblasts, but fibrillar collagen and the ECM proteome were not overtly altered when evaluated by quantitative mass spectrometry and N-terminomics. However, the distribution and quantity of collagen VI, microfibrillar collagen that forms an open network with the basement membrane, was reduced. In fibroblast-ablated mice, cardiac function was better preserved following angiotensin II/phenylephrine (AngII/PE)-induced fibrosis and myocardial infarction (MI). Analysis of cardiomyocyte function demonstrated altered sarcomere shortening and slowed calcium decline in both uninjured and AngII/PE-infused fibroblast-ablated mice. After MI, the residual resident fibroblasts responded to injury, albeit with reduced proliferation and numbers immediately after injury. These results indicate that the adult mouse heart tolerates a significant degree of fibroblast loss with a potentially beneficial impact on cardiac function after injury. The cardioprotective effect of controlled fibroblast reduction may have therapeutic value in heart disease.

Regulation of extracellular matrix composition by fibroblasts during perinatal cardiac maturation.

BACKGROUND: Cardiac fibroblasts are the main non-myocyte population responsible for extracellular matrix (ECM) production. During perinatal development, fibroblast expansion coincides with the transition from hyperplastic to hypertrophic myocardial growth. Therefore, we investigated the consequences of fibroblast loss at the time of cardiomyocyte maturation by depleting fibroblasts in the perinatal mouse. METHODS AND RESULTS: We evaluated the microenvironment of the perinatal heart in the absence of fibroblasts and the potential functional impact of fibroblast loss in regulation of cardiomyocyte cell cycle arrest and binucleation. Cre-mediated expression of diphtheria toxin A in PDGFRα expressing cells immediately after birth eliminated 70-80% of the cardiac fibroblasts. At postnatal day 5, hearts lacking fibroblasts appeared similar to controls with normal morphology and comparable numbers of endothelial and smooth muscle cells, despite a pronounced reduction in fibrillar collagen. Immunoblotting and proteomic analysis of control and fibroblast-deficient hearts identified differential abundance of several ECM proteins. In addition, fibroblast loss decreased tissue stiffness and resulted in increased cardiomyocyte mitotic index, DNA synthesis, and cytokinesis. Moreover, decellularized matrix from fibroblast-deficient hearts promoted cardiomyocyte DNA replication. While cardiac architecture was not overtly affected by fibroblast reduction, few pups survived past postnatal day 11, suggesting an overall requirement for PDGFRα expressing fibroblasts. CONCLUSIONS: These studies demonstrate the key role of fibroblasts in matrix production and cardiomyocyte cross-talk during mouse perinatal heart maturation and revealed that fibroblast-derived ECM may modulate cardiomyocyte maturation in vivo. Neonatal depletion of fibroblasts demonstrated that although hearts can tolerate reduced ECM composition, fibroblast loss eventually leads to perinatal death as the approach simultaneously reduced fibroblast populations in other organs.

A Mathematical Model of the Dynamics of Cytokine Expression and Human Immune Cell Activation in Response to the Pathogen Staphylococcus aureus.

Cell-based mathematical models have previously been developed to simulate the immune system in response to pathogens. Mathematical modeling papers which study the human immune response to pathogens have predicted concentrations of a variety of cells, including activated and resting macrophages, plasma cells, and antibodies. This study aims to create a comprehensive mathematical model that can predict cytokine levels in response to a gram-positive bacterium, S. aureus by coupling previous models. To accomplish this, the cytokines Tumor Necrosis Factor Alpha (TNF-α), Interleukin 6 (IL-6), Interleukin 8 (IL-8), and Interleukin 10 (IL-10) are included to quantify the relationship between cytokine release from macrophages and the concentration of the pathogen, S. aureus, ex vivo. Partial differential equations (PDEs) are used to model cellular response and ordinary differential equations (ODEs) are used to model cytokine response, and interactions between both components produce a more robust and more complete systems-level understanding of immune activation. In the coupled cellular and cytokine model outlined in this paper, a low concentration of S. aureus is used to stimulate the measured cellular response and cytokine expression. Results show that our cellular activation and cytokine expression model characterizing septic conditions can predict ex vivo mechanisms in response to gram-negative and gram-positive bacteria. Our simulations provide new insights into how the human immune system responds to infections from different pathogens. Novel applications of these insights help in the development of more powerful tools and protocols in infection biology.