Evaluating the effect of NPO status on mucosal coating during double contrast barium esophagrams.

INTRODUCTION: Current guidelines for double contrast barium esophagography studies (BAS) suggest that patients should be nil per os (NPO) prior to completing BAS for optimal esophageal coating, although the time required varies between practices and institutions. It is believed that consumption of food or water disrupts the ability for thick barium contrast to properly coat the esophageal mucosa. Exams that are rescheduled for this reason can lead to delays in care, without substantial evidence that NPO status truly affects esophageal mucosal coating for these exams with current barium mixtures. OBJECTIVE: The study aims to identify the necessity, or lack thereof, of standard NPO protocol in patients undergoing BAS, in effort to prevent unnecessary procedural delay. MATERIALS AND METHODS: This study is an IRB-approved HIPAA-compliant study of 370 consecutive adult patients (115 male/255 female, mean age 55) who underwent BAS at our institution from January to June of 2022. Patients were divided into two groups: < 4 h NPO (n = 334), and ≥ 4 h NPO (n = 36). Four abdominal radiologists blinded to NPO interval independently reviewed a random sample of approximately 92 patients (91-94) and graded esophageal coating on a 4-point-scale with 1 being insufficient coating and 4 being optimal coating. RESULTS: No significant statistical difference in mean esophageal coating score was found between the ≥ 4 h NPO cohort (3.04 ± SD 0.78) and the < 4 h NPO cohort (2.97 ± SD 0.70; P = 0.54). Subset analysis of patients who were NPO for < 2 h (n = 9) also showed no significant difference in mean esophageal coating score (3.11 ± SD 0.6; P = 0.92), compared to the standard ≥ 4 NPO status. CONCLUSION: Non-adherence to standard NPO protocol prior to BAS studies did not result in a significant difference in esophageal coating when compared to traditional preprocedural fasting of 4 or more hours.

Dendritic spine head diameter predicts episodic memory performance in older adults.

Episodic memory in older adults is varied and perceived to rely on numbers of synapses or dendritic spines. We analyzed 2157 neurons among 128 older individuals from the Religious Orders Study and Rush Memory and Aging Project. Analysis of 55,521 individual dendritic spines by least absolute shrinkage and selection operator regression and nested model cross-validation revealed that the dendritic spine head diameter in the temporal cortex, but not the premotor cortex, improved the prediction of episodic memory performance in models containing ß amyloid plaque scores, neurofibrillary tangle pathology, and sex. These findings support the emerging hypothesis that, in the temporal cortex, synapse strength is more critical than quantity for memory in old age.

Integration across biophysical scales identifies molecular and cellular correlates of person-to-person variability in human brain connectivity.

Brain connectivity arises from interactions across biophysical scales, ranging from molecular to cellular to anatomical to network level. To date, there has been little progress toward integrated analysis across these scales. To bridge this gap, from a unique cohort of 98 individuals, we collected antemortem neuroimaging and genetic data, as well as postmortem dendritic spine morphometric, proteomic and gene expression data from the superior frontal and inferior temporal gyri. Through the integration of the molecular and dendritic spine morphology data, we identified hundreds of proteins that explain interindividual differences in functional connectivity and structural covariation. These proteins are enriched for synaptic structures and functions, energy metabolism and RNA processing. By integrating data at the genetic, molecular, subcellular and tissue levels, we link specific biochemical changes at synapses to connectivity between brain regions. These results demonstrate the feasibility of integrating data from vastly different biophysical scales to provide a more comprehensive understanding of brain connectivity.

A Molecular Basis of Human Brain Connectivity.

Neuroimaging is commonly used to infer human brain connectivity, but those measurements are far-removed from the molecular underpinnings at synapses. To uncover the molecular basis of human brain connectivity, we analyzed a unique cohort of 98 individuals who provided neuroimaging and genetic data contemporaneous with dendritic spine morphometric, proteomic, and gene expression data from the superior frontal and inferior temporal gyri. Through cellular contextualization of the molecular data with dendritic spine morphology, we identified hundreds of proteins related to synapses, energy metabolism, and RNA processing that explain between-individual differences in functional connectivity and structural covariation. By integrating data at the genetic, molecular, subcellular, and tissue levels, we bridged the divergent fields of molecular biology and neuroimaging to identify a molecular basis of brain connectivity. One-Sentence Summary: Dendritic spine morphometry and synaptic proteins unite the divergent fields of molecular biology and neuroimaging.

Comparison of Golgi-Cox and Intracellular Loading of Lucifer Yellow for Dendritic Spine Density and Morphology Analysis in the Mouse Brain.

Dendritic spines are small protrusions on dendrites that serve as the postsynaptic site of the majority of excitatory synapses. These structures are important for normal synaptic transmission, and alterations in their density and morphology have been documented in various disease states. Over 130 years ago, Ramón y Cajal used Golgi-stained tissue sections to study dendritic morphology. Despite the array of technological advances, including iontophoretic microinjection of Lucifer yellow (LY) fluorescent dye, Golgi staining continues to be one of the most popular approaches to visualize dendritic spines. Here, we compared dendritic spine density and morphology among pyramidal neurons in layers 2/3 of the mouse medial prefrontal cortex (mPFC) and pyramidal neurons in hippocampal CA1 using three-dimensional digital reconstructions of (1) brightfield microscopy z-stacks of Golgi-impregnated dendrites and (2) confocal microscopy z-stacks of LY-filled dendrites. Analysis of spine density revealed that the LY microinjection approach enabled detection of approximately three times as many spines as the Golgi staining approach in both brain regions. Spine volume measurements were larger using Golgi staining compared to LY microinjection in both mPFC and CA1. Spine length was mostly comparable between techniques in both regions. In the mPFC, head diameter was similar for Golgi staining and LY microinjection. However, in CA1, head diameter was approximately 50% smaller on LY-filled dendrites compared to Golgi staining. These results indicate that Golgi staining and LY microinjection yield different spine density and morphology measurements, with Golgi staining failing to detect dendritic spines and overestimating spine size.

Dendritic Spine Remodeling and Synaptic Tau Levels in PS19 Tauopathy Mice.

Synapse or dendritic spine loss is the strongest correlate of cognitive decline in Alzheimer's disease (AD), and neurofibrillary tangles (NFTs), but not amyloid-ß plaques, associate more closely with transition to mild cognitive impairment. Yet, how dendritic spine architecture is affected by hyperphosphorylated tau is still an ongoing question. To address this, we combined cell and biochemical analyses of the Tau P301S mouse line (PS19). Individual pyramidal neurons in the hippocampus and medial prefrontal cortex (mPFC) were targeted for iontophoretic microinjection of fluorescent dye, followed by high-resolution confocal microscopy and 3D morphometry analysis. In the hippocampus, PS19 mice and non-transgenic (NTG) littermates displayed equivalent spine density at 6 and 9 months, but both genotypes exhibited age-related thin spine loss. PS19 mice exhibited significant increases in synaptic tau protein levels and mean dendritic spine head diameter with age. This suggests that CA1 pyramidal neurons in PS19 mice may undergo spine remodeling in response to tau accumulation and age. In the mPFC, spine density was similar among PS19 mice and NTG littermates at 6 and 9 months, but age-related reductions in synaptic tau levels were observed among PS19 mice. Collectively, these studies reveal brain region-specific changes in dendritic spine density and morphology in response to age and the presence of hyperphosphorylated tau in the PS19 mouse line.