Water quality monitoring records for estimating tap water arsenic and nitrate: a validation study

<p>Abstract</p> <p>Background</p> <p>Tap water may be an important source of exposure to arsenic and nitrate. Obtaining and analyzing samples in the context of large studies of health effects can be expensive. As an alternative, studies might estimate contaminant levels in individual homes by using publicly available water quality monitoring records, either alone or in combination with geographic information systems (GIS).</p> <p>Methods</p> <p>We examined the validity of records-based methods in Washington State, where arsenic and nitrate contamination is prevalent but generally observed at modest levels. Laboratory analysis of samples from 107 homes (median 0.6 μg/L arsenic, median 0.4 mg/L nitrate as nitrogen) served as our "gold standard." Using Spearman's rho we compared these measures to estimates obtained using only the homes' street addresses and recent and/or historical measures from publicly monitored water sources within specified distances (radii) ranging from one half mile to 10 miles.</p> <p>Results</p> <p>Agreement improved as distance decreased, but the proportion of homes for which we could estimate summary measures also decreased. When including all homes, agreement was 0.05-0.24 for arsenic (8 miles), and 0.31-0.33 for nitrate (6 miles). Focusing on the closest source yielded little improvement. Agreement was greatest among homes with private wells. For homes on a water system, agreement improved considerably if we included only sources serving the relevant system (ρ = 0.29 for arsenic, ρ = 0.60 for nitrate).</p> <p>Conclusions</p> <p>Historical water quality databases show some promise for categorizing epidemiologic study participants in terms of relative tap water nitrate levels. Nonetheless, such records-based methods must be used with caution, and their use for arsenic may be limited.</p

A Proposed Framework for Patient-Focused Policy at the U.S. Food and Drug Administration

Medical product sponsors are encouraged to include the patient perspective in their medical product development strategy to inform product design, augment regulatory submissions, argue for alternative clinical trial designs, or to support indications in specific patient populations. The goal is to create a patient-focused ecosystem that enables industry to integrate the patient voice throughout the medical product lifecycle. To this end, the U. S. Food and Drug Administration (FDA) has published several guidance documents to provide industry with the expectations and opportunities for conducting patient-focused activities. From an industry perspective, the Center for Devices and Radiologic Health (CDRH) and the Center for Drug Evaluation and Research (CDER)/Center for Biologics Evaluation and Research (CBER) patient-focused policies are complementary. The basic tenets promoted in all FDA patient-focused guidance could apply across therapeutic areas. However, there remain differences in these guidance documents across FDA centers, and there is no framework in place to provide industry with consistent recommendations. Without a coordinated patient-focused policy from the FDA, there is the potential for confusion and a lack of consistency among industry and regulatory decision-makers. The objective of this paper was to propose an alternative framework for patient-focused policy at the FDA, which recognizes the potential for different types of patient input to be used across therapeutic areas and medical product types. Further, these policies need to provide greater clarity on how patient input data is used, so that sponsors may navigate the opportunities to use patient input regardless of the FDA center under which their product is regulated. Creating consistent, coherent, and transparent FDA patient-focused policy will encourage sponsors to obtain patient input more often and with greater certainty of the value that these data may have to their medical product strategies

Single organelle function and organization as estimated from Arabidopsis mitochondrial proteomics

Mitochondria host vital cellular functions, including oxidative phosphorylation and co-factor biosynthesis, which are reflected in their proteome. At the cellular level plant mitochondria are organized into hundreds of discrete functional entities, which undergo dynamic fission and fusion. It is the individual organelle that operates in the living cell, yet biochemical and physiological assessments have exclusively focused on the characteristics of large populations of mitochondria. Here, we explore the protein composition of an individual average plant mitochondrion to deduce principles of functional and structural organisation. We perform proteomics on purified mitochondria from cultured heterotrophic Arabidopsis cells with intensity-based absolute quantification and scale the dataset to the single organelle based on criteria that are justified by experimental evidence and theoretical considerations. We estimate that a total of 1.4 million protein molecules make up a single Arabidopsis mitochondrion on average. Copy numbers of the individual proteins span five orders of magnitude, ranging from >40 000 for Voltage-Dependent Anion Channel 1 to sub-stoichiometric copy numbers, i.e. less than a single copy per single mitochondrion, for several pentatricopeptide repeat proteins that modify mitochondrial transcripts. For our analysis, we consider the physical and chemical constraints of the single organelle and discuss prominent features of mitochondrial architecture, protein biogenesis, oxidative phosphorylation, metabolism, antioxidant defence, genome maintenance, gene expression, and dynamics. While assessing the limitations of our considerations, we exemplify how our understanding of biochemical function and structural organization of plant mitochondria can be connected in order to obtain global and specific insights into how organelles work