Publications by authors named "Sarah Pan"

From early in life, children learn to perform actions on the objects in their environments. Although children learn from observing others' actions, actively engaging with the material to be learned can be important for learning. This study tested whether instruction that included opportunities for children to be active supported toddlers' action learning.

View Article and Find Full Text PDF

In mice, retinal vascular and astrocyte networks begin to develop at birth, expanding radially from the optic nerve head (ONH) towards the retinal periphery. The retinal vasculature grows towards the periphery ahead of differentiated astrocytes, but behind astrocytic progenitor cells (APCs) and immature astrocytes. Endothelial cell specific Vegfr-2 disruption in newborn mice not only blocked retinal vascular development but also suppressed astrocytic differentiation, reducing the abundance of differentiated astrocytes while causing the accumulation of precursors.

View Article and Find Full Text PDF

Purpose: The transient middle cerebral artery occlusion (MCAO) model of stroke is one of the most commonly used models to study focal cerebral ischemia. This procedure also results in the simultaneous occlusion of the ophthalmic artery that supplies the retina. Retinal cell death is seen days after reperfusion and leads to functional deficits; however, the mechanism responsible for this injury has not been investigated.

View Article and Find Full Text PDF

The development of biomarkers to predict the progression of Parkinson's disease (PD) from its earliest stage through its heterogeneous course is critical for research and therapeutic development. The Parkinson's Progression Markers Initiative (PPMI) study is an ongoing international multicenter, prospective study to validate biomarkers in drug-naïve PD patients and matched healthy controls (HC). We quantified cerebrospinal fluid (CSF) alpha-synuclein (α-syn), amyloid-beta1-42 (Aβ1-42), total tau (t-tau), and tau phosphorylated at Thr181 (p-tau) in 660 PPMI subjects at baseline, and correlated these data with measures of the clinical features of these subjects.

View Article and Find Full Text PDF

Although the influenza virus only infects the respiratory system, myalgias are commonly experienced during infection. In addition to a greater risk of hospitalization and death, older adults are more likely to develop disability following influenza infection; however, this relationship is understudied. We hypothesized that upon challenge with influenza, aging would be associated with functional impairments, as well as upregulation of skeletal muscle inflammatory and atrophy genes.

View Article and Find Full Text PDF

Inflammation in the central nervous system (CNS) is primarily regulated by microglia. No longer considered a homogenous population, microglia display a high degree of heterogeneity, immunological diversity and regional variability in function. Given their low rate of self-renewal, the microenvironment in which microglia reside may play an important role in microglial senescence.

View Article and Find Full Text PDF

Underserved minorities are vulnerable to diagnostic delays and under-treatment of Parkinson's disease (PD). The purpose of this mixed-methods study was to understand knowledge and attitudes about PD among a racially/ethnically diverse group of community members. In the qualitative arm, ten homogeneous focus groups of 6 to 8 White, African-American and Chinese American older adults at senior centers in Philadelphia were conducted.

View Article and Find Full Text PDF

Importance: We observed a significant correlation between cerebrospinal fluid (CSF) levels of tau proteins and α-synuclein, but not β-amyloid 1-42 (Aβ1-42), and lower concentration of CSF biomarkers, as compared with healthy controls, in a cohort of entirely untreated patients with Parkinson disease (PD) at the earliest stage of the disease studied so far.

Objective: To evaluate the baseline characteristics and relationship to clinical features of CSF biomarkers (Aβ1-42, total tau [T-tau], tau phosphorylated at threonine 181 [P-tau181], and α-synuclein) in drug-naive patients with early PD and demographically matched healthy controls enrolled in the Parkinson's Progression Markers Initiative (PPMI) study.

Design, Setting, And Participants: Cross-sectional study of the initial 102 research volunteers (63 patients with PD and 39 healthy controls) of the PPMI cohort.

View Article and Find Full Text PDF

Objectives: We determined whether Philadelphia Lead Court is effective in enforcing lead hazard remediation in the homes of children with elevated blood lead levels.

Methods: We created a deidentified data set for properties with an initial failed home inspection (IFHI) for lead hazards from January 1, 1998, through December 31, 2008, and compared compliance rates within the first year and time to compliance for lead hazard remediation between 1998 and 2002 (precourt period) and between 2003 and 2008 (court period). We evaluated predictors of time to compliance.

View Article and Find Full Text PDF

The Philadelphia Lead Court (PLC) was created as an innovative law enforcement strategy to compel property owners to comply with city health codes to remediate their properties of lead hazards, which had led to elevated blood lead levels and lead poisoning in resident children. This study presents a detailed account of and analyzes the opinions of fifteen key informants drawn from the Philadelphia health and law departments and judicial system that staff and run the PLC in response to a fifteen-question structured survey. Main themes reviewed include the effectiveness of the PLC as compared with precourt law enforcement strategies and within the context of a specialized court, the use of fines, the impact of grant funding for remediation work, the major advantages and disadvantages of the PLC, and suggested changes to improve court function, followed by key recommendations.

View Article and Find Full Text PDF