3-Hydroxyanthranilic Acid Delays Paralysis in Caenorhabditis elegans Models of Amyloid-Beta and Polyglutamine Proteotoxicity.

Age is the primary risk factor for neurodegenerative diseases such as Alzheimer's and Huntington's disease. Alzheimer's disease is the most common form of dementia and a leading cause of death in the elderly population of the United States. No effective treatments for these diseases currently exist. Identifying effective treatments for Alzheimer's, Huntington's, and other neurodegenerative diseases is a major current focus of national scientific resources, and there is a critical need for novel therapeutic strategies. Here, we investigate the potential for targeting the kynurenine pathway metabolite 3-hydroxyanthranilic acid (3HAA) using Caenorhabditis elegans expressing amyloid-beta or a polyglutamine peptide in body wall muscle, modeling the proteotoxicity in Alzheimer's and Huntington's disease, respectively. We show that knocking down the enzyme that degrades 3HAA, 3HAA dioxygenase (HAAO), delays the age-associated paralysis in both models. This effect on paralysis was independent of the protein aggregation in the polyglutamine model. We also show that the mechanism of protection against proteotoxicity from HAAO knockdown is mimicked by 3HAA supplementation, supporting elevated 3HAA as the mediating event linking HAAO knockdown to delayed paralysis. This work demonstrates the potential for 3HAA as a targeted therapeutic in neurodegenerative disease, though the mechanism is yet to be explored.

On the benefits of the tryptophan metabolite 3-hydroxyanthranilic acid in Caenorhabditis elegans and mouse aging.

Tryptophan metabolism through the kynurenine pathway influences molecular processes critical to healthy aging including immune signaling, redox homeostasis, and energy production. Aberrant kynurenine metabolism occurs during normal aging and is implicated in many age-associated pathologies including chronic inflammation, atherosclerosis, neurodegeneration, and cancer. We and others previously identified three kynurenine pathway genes-tdo-2, kynu-1, and acsd-1-for which decreasing expression extends lifespan in invertebrates. Here we report that knockdown of haao-1, a fourth gene encoding the enzyme 3-hydroxyanthranilic acid (3HAA) dioxygenase (HAAO), extends lifespan by ~30% and delays age-associated health decline in Caenorhabditis elegans. Lifespan extension is mediated by increased physiological levels of the HAAO substrate 3HAA. 3HAA increases oxidative stress resistance and activates the Nrf2/SKN-1 oxidative stress response. In pilot studies, female Haao knockout mice or aging wild type male mice fed 3HAA supplemented diet were also long-lived. HAAO and 3HAA represent potential therapeutic targets for aging and age-associated disease.

Caenorhabditis elegans orthologs of human genes differentially expressed with age are enriched for determinants of longevity.

We report a systematic RNAi longevity screen of 82 Caenorhabditis elegans genes selected based on orthology to human genes differentially expressed with age. We find substantial enrichment in genes for which knockdown increased lifespan. This enrichment is markedly higher than published genomewide longevity screens in C. elegans and similar to screens that preselected candidates based on longevity-correlated metrics (e.g., stress resistance). Of the 50 genes that affected lifespan, 46 were previously unreported. The five genes with the greatest impact on lifespan (>20% extension) encode the enzyme kynureninase (kynu-1), a neuronal leucine-rich repeat protein (iglr-1), a tetraspanin (tsp-3), a regulator of calcineurin (rcan-1), and a voltage-gated calcium channel subunit (unc-36). Knockdown of each gene extended healthspan without impairing reproduction. kynu-1(RNAi) alone delayed pathology in C. elegans models of Alzheimer's disease and Huntington's disease. Each gene displayed a distinct pattern of interaction with known aging pathways. In the context of published work, kynu-1, tsp-3, and rcan-1 are of particular interest for immediate follow-up. kynu-1 is an understudied member of the kynurenine metabolic pathway with a mechanistically distinct impact on lifespan. Our data suggest that tsp-3 is a novel modulator of hypoxic signaling and rcan-1 is a context-specific calcineurin regulator. Our results validate C. elegans as a comparative tool for prioritizing human candidate aging genes, confirm age-associated gene expression data as valuable source of novel longevity determinants, and prioritize select genes for mechanistic follow-up.

Fecal Impaction in the Emergency Department: An Analysis of Frequency and Associated Charges in 2011.

GOALS: The aim of this study was to analyze the incidence and associated charges of fecal impaction for trends in hospital and patient demographics in emergency departments (ED) across the United States. BACKGROUND: In 2010, an ICD-9-CM code (560.32) for fecal impaction was introduced, allowing for assessment of fecal impaction incidence. STUDY: Data were obtained from the National Emergency Department Sample records in which fecal impaction (ICD-9-CM code 560.32) was first listed as a diagnosis in 2011. RESULTS: In 2011, there were 42,481 [95% confidence interval (CI), 39,908-45,054] fecal impaction ED visits, with an overall rate of 32 fecal impaction visits per 100,000 ED visits. Adjusted for inflation in 2014 dollars, the associated mean charge of a fecal impaction ED visit was $3060.47 (95% CI, $2943.02-$3177.92), with an aggregate national charge in the US of $130,010,772 (95% CI, $120,688,659-$139,332,885). All charges were adjusted for inflation and reported in 2014 dollars. Late elders (85+ y) had the highest rate of fecal impaction ED visits, followed by early elders (65 to 84 y). Medicare was the primary payer for the greatest number of fecal impaction ED visits accounting for nearly two thirds of visit payments. CONCLUSION: This study reports previously unexplored statistics on the number, frequency, and associated charges of ED visits with a primary diagnosis of fecal impaction, a condition found most commonly among elders.

Emergency department burden of constipation in the United States from 2006 to 2011.

OBJECTIVES: Although constipation is typically managed in an outpatient setting, there is an increasing trend in the frequency of constipation-related hospital visits. The aim of this study was to analyze trends related to chronic constipation (CC) in the United States with respect to emergency department (ED) visits, patient and hospital characteristics, and associated costs. METHODS: Data from 2006 to 2011, in which constipation (The International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) diagnosis codes 564.00-564.09) was the primary discharge diagnosis, were obtained from the National Emergency Department Sample (NEDS). RESULTS: Between 2006 and 2011, the frequency of constipation-related ED visits increased by 41.5%, from 497,034 visits to 703,391 visits, whereas the mean cost per patient rose by 56.4%, from $1,474 in 2006 to $2,306 in 2011. The aggregate national cost of constipation-related ED visits increased by 121.4%, from $732,886,977 in 2006 to $1,622,624,341 in 2011. All cost data were adjusted for inflation and reported in 2014 dollars. Infants (<1 year old) had the highest rate of constipation-related ED visits in both 2006 and 2011. The late elders (85+ years) had the second highest constipation-related ED visit rate in 2006; however, the 1- to 17-year-old age group experienced a 50.7% increase in constipation-related ED visit rate from 2006 to 2011 and had the second highest constipation-related ED visit rate in 2011. CONCLUSIONS: The frequency of and the associated costs of ED visits for constipation are significant and have increased notably from 2006 to 2011.