Large enrichments in fatty acid 2H/1H ratios distinguish respiration from aerobic fermentation in yeast Saccharomyces cerevisiae

Shifts in the hydrogen stable isotopic composition (2H/1H ratio) of lipids relative to water (lipid/water 2H-fractionation) at natural abundances reflect different sources of the central cellular reductant, NADPH, in bacteria. Here, we demonstrate that lipid/water 2H-fractionation (2εfattyacid/water) can also constrain the relative importance of key NADPH pathways in eukaryotes. We used the metabolically flexible yeast Saccharomyces cerevisiae, a microbial model for respiratory and fermentative metabolism in industry and medicine, to investigate 2εfattyacid/water. In chemostats, fatty acids from glycerol-respiring cells were >550‰ 2H-enriched compared to those from cells aerobically fermenting sugars via overflow metabolism, a hallmark feature in cancer. Faster growth decreased 2H/1H ratios, particularly in glycerol-respiring cells by 200‰. Variations in the activities and kinetic isotope effects among NADP+-reducing enzymes indicate cytosolic NADPH supply as the primary control on 2εfattyacid/water. Contributions of cytosolic isocitrate dehydrogenase (cIDH) to NAPDH production drive large 2H-enrichments with substrate metabolism (cIDH is absent during fermentation but contributes up to 20 percent NAPDH during respiration) and slower growth on glycerol (11 percent more NADPH from cIDH). Shifts in NADPH demand associated with cellular lipid abundance explain smaller 2εfattyacid/water variations (<30‰) with growth rate during fermentation. Consistent with these results, tests of murine liver cells had 2H-enriched lipids from slower-growing, healthy respiring cells relative to fast-growing, fermenting hepatocellular carcinoma. Our findings point to the broad potential of lipid 2H/1H ratios as a passive natural tracker of eukaryotic metabolism with applications to distinguish health and disease, complementing studies that rely on complex isotope-tracer addition methods.

Effects of increasing atmospheric CO2 on leaf water δ18O values are small and are attenuated in grasses and amplified in dicotyledonous herbs and legumes when transferred to cellulose δ18O values

The oxygen isotope composition of cellulose (δ18O values) has been suggested to contain information on stomatal conductance (gs) responses to rising pCO2. The extent by which pCO2 affects leaf water and cellulose δ18O values (δ18OLW and δ18OC) and the isotope processes that determine pCO2 effects on δ18OLW and δ18OC are, however, unknown. We tested the effects of pCO2 on gs, δ18OLW and δ18OC in a glasshouse experiment, where six plant species were grown under pCO2 ranging from 200 to 500 ppm. Increasing pCO2 caused a decline in gs and an increase in δ18OLW, as expected. Importantly, the effects of pCO2 on gs and δ18OLW were small and pCO2 effects on δ18OLW were not directly transferred to δ18OC but were attenuated in grasses and amplified in dicotyledonous herbs and legumes. This is likely because of functional group-specific pCO2 effects on the model parameter pxpex. Our study highlights important uncertainties when using δ18OC as a proxy for gs. Specifically, pCO2-triggered gs effects on δ18OLW and δ18OC are possibly too small to be detected in natural settings and a pCO2 effect on pxpex may render the commonly assumed negative linkage between δ18OC and gs to be incorrect, potentially confounding δ18OC based gs reconstructions.

Covariation between oxygen and hydrogen stable isotopes declines along the path from xylem water to wood cellulose across an aridity gradient

Oxygen and hydrogen isotopes of cellulose in plant biology are commonly used to infer environmental conditions, often from time series measurements of tree rings. However, the covariation (or the lack thereof) between δ18 O and δ2 H in plant cellulose is still poorly understood. We compared plant water, and leaf and branch cellulose from dominant tree species across an aridity gradient in Northern Australia, to examine how δ18 O and δ2 H relate to each other and to mean annual precipitation (MAP). We identified a decline in covariation from xylem to leaf water, and onwards from leaf to branch wood cellulose. Covariation in leaf water isotopic enrichment (Δ) was partially preserved in leaf cellulose but not branch wood cellulose. Furthermore, whilst δ2 H was well-correlated between leaf and branch, there was an offset in δ18 O between organs that increased with decreasing MAP. Our findings strongly suggest that postphotosynthetic isotope exchange with water is more apparent for oxygen isotopes, whereas variable kinetic and nonequilibrium isotope effects add complexity to interpreting metabolic-induced δ2 H patterns. Varying oxygen isotope exchange in wood and leaf cellulose must be accounted for when δ18 O is used to reconstruct climatic scenarios. Conversely, comparing δ2 H and δ18 O patterns may reveal environmentally induced shifts in metabolism.

Continuous Medicaid coverage during the COVID-19 public health emergency reduced churning, but did not eliminate it

Preserving insurance coverage in the wake of pandemic-related job loss was a priority in early 2020. To this end, the Families First Coronavirus Response Act implemented a continuous coverage policy in Medicaid to shore up access to health insurance. Prior to the pandemic, Medicaid enrollees experienced frequent coverage disruptions, known as "churning." The effect of the continuous coverage policy on churning during the COVID-19 public health emergency (PHE) is unknown. We performed a difference-in-differences analysis of nonelderly Medicaid enrollees using longitudinal national survey data to compare a 2019-2020 cohort exposed to the policy with a control cohort in 2018-2019. We found that the policy led to reduced transitions to uninsurance among adults, although not among children. The policy prevented over 300 000 transitions to uninsurance each month. However, disenrollment from Medicaid persisted at a low rate, despite the continuous coverage policy. As the PHE unwinds, policymakers should consider long-term continuous coverage policies to minimize churning in Medicaid.

Land-use-based freshwater sediment source fingerprinting using hydrogen isotope compositions of long-chain fatty acids

Rapidly changing land use patterns and frequent extreme weather events have resulted in an increased sediment flux to freshwater systems globally, highlighting the need for land-use-based sediment source fingerprinting. Application of variability in hydrogen isotope compositions (δ2H values) of vegetation-specific biomarkers from soils and sediments is relatively underexplored for land-use-based freshwater suspended sediment (SS) source fingerprinting, but has the potential to complement the information from routinely applied carbon isotope analysis and provide new insights. We analysed δ2H values of long-chain fatty acids (LCFAs) as vegetation-specific biomarkers in source soils and SS collected from the mixed land use Tarland catchment (74 km2) in NE Scotland, to identify stream SS sources and quantify their contributions to SS. Plant growth form was the primary control on source soils LCFAs (n-C26:0, n-C28:0, n-C30:0) δ2H variability, while the isotopic composition of source water had no significant control. Forest and heather moorland soils covered with dicotyledonous and gymnosperm species were differentiated from arable land and grasslands soils covered with monocotyledonous species. SS samples collected for fourteen months from the Tarland catchment with a nested sampling approach showed monocot-based land use (cereal crops, grassland) to be the major source of SS with 71 ± 11% contribution on catchment-wide scale averaged throughout the sampling period. Storm events after a dry summer period and sustained high flow conditions in the streams during autumn and early winter suggested enhanced connectivity of more distant forest and heather moorland land uses covering relatively steep topography. This was shown by an increased contribution (44 ± 8%) on catchment-wide scale from dicot and gymnosperm-based land uses during the corresponding period. Our study demonstrated successful application of vegetation-specificity in δ2H values of LCFAs for land-use-based freshwater SS source fingerprinting in a mesoscale catchment where δ2H values of LCFAs were primarily controlled by plant growth forms.

The metabolic sensitivity of hydrogen isotope fractionation differs between plant compounds

Hydrogen stable isotope analyses (δ²H) of plant derived organic compounds are a useful tool for ecological, environmental, and palaeoclimatological research. However, during organic compound synthesis, variable biosynthetic ²H-fractionation has been suggested to occur as a result of changes in plant carbon fluxes. So far, inference has been based on examining the δ²H patterns of plant compounds along environmental gradients, among plant species, and between plant organs. In an alternative approach, we used four plant species with four different types of mutations that cause impaired starch synthesis to assess whether variability in carbon metabolism affects the biosynthetic ²H-fractionation during cellulose, phytol, and acetogenic lipid synthesis. We found that mutants with impaired starch synthesis always had higher cellulose and phytol δ²H values compared to the wild type. By contrast, ²H-fractionation during acetogenic lipid biosynthesis generally did not show strong metabolic sensitivity. We rationalise these differences by considering the biosynthetic pathway of each compound and the likely source of the variable isotope fractionation. In different organic compounds, the sensitivity of variable biosynthetic ²H-fractionation to changes in C-metabolism depends on incorporation of specific H atoms from precursor molecules. As such, we determined that the similar increase in cellulose and phytol δ²H values as an effect of impaired starch synthesis most likely originates in triose-phosphates.

Species variation in the hydrogen isotope composition of leaf cellulose is mostly driven by isotopic variation in leaf sucrose

Experimental approaches to isolate drivers of variation in the carbon-bound hydrogen isotope composition (δ² H) of plant cellulose are rare and current models are limited in their application. This is in part due to a lack in understanding of how ² H-fractionations in carbohydrates differ between species. We analysed, for the first time, the δ² H of leaf sucrose along with the δ² H and δ¹⁸ O of leaf cellulose and leaf and xylem water across seven herbaceous species and a starchless mutant of tobacco. The δ² H of sucrose explained 66% of the δ² H variation in cellulose (R²  = 0.66), which was associated with species differences in the ² H enrichment of sucrose above leaf water ( ε sucrose <math altimg="urn:x-wiley:01407791:media:pce14362:pce14362-math-0001" wiley:location="equation/pce14362-math-0001.png" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mtext>\unicode{x003B5}</mtext><mtext>sucrose</mtext></msub></mrow></math> : -126% to -192‰) rather than by variation in leaf water δ² H itself. ε sucrose <math altimg="urn:x-wiley:01407791:media:pce14362:pce14362-math-0002" wiley:location="equation/pce14362-math-0002.png" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><msub><mtext>\unicode{x003B5}</mtext><mtext>sucrose</mtext></msub></mrow></math> was positively related to dark respiration (R²  = 0.27), and isotopic exchange of hydrogen in sugars was positively related to the turnover time of carbohydrates (R²  = 0.38), but only when ε sucrose <math altimg="urn:x-wiley:01407791:media:pce14362:pce14362-math-0003" wiley:location="equation/pce14362-math-0003.png" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><msub><mi mathvariant="normal">\unicode{x003B5}</mi><mtext>sucrose</mtext></msub></mrow></mrow></math> was fixed to the literature accepted value of - 171 <math altimg="urn:x-wiley:01407791:media:pce14362:pce14362-math-0004" wiley:location="equation/pce14362-math-0004.png" xmlns="http://www.w3.org/1998/Math/MathML"><mrow><mrow><mo>\unicode{x02212}</mo><mn>171</mn></mrow></mrow></math> ‰. No relation was found between isotopic exchange of hydrogen and oxygen, suggesting large differences in the processes shaping post-photosynthetic fractionation between elements. Our results strongly advocate that for robust applications of the leaf cellulose hydrogen isotope model, parameterization utilizing δ² H of sugars is needed.

Constraining parameter uncertainty for predicting oxygen and hydrogen isotope values in fruit

Understanding δ18O and δ2H values of agricultural products like fruit is of particular scientific interest in plant physiology, ecology, and forensic studies. Applications of mechanistic stable isotope models to predict δ18O and δ2H values of water and organic compounds in fruit, however, are hindered by a lack of empirical parameterizations and validations. We addressed this lack of data by experimentally evaluating model parameter values required to model δ18O and δ2H values of water and organic compounds in berries and leaves from strawberry and raspberry plants grown at different relative humidities. Our study revealed substantial differences between leaf and berry isotope values, consistent across the different relative humidity treatments. We demonstrated that existing isotope models can reproduce water and organic δ18O and δ2H values for leaves and berries. Yet, these simulations require organ-specific model parameterization to accurately predict δ18O and δ2H values of leaf and berry tissue and water pools. We quantified these organ-specific model parameters for both species and relative humidity conditions. Depending on the required model accuracy, species- and environment-specific model parameters may be justified. The parameter values determined in this study thus facilitate applications of stable isotope models where understanding δ18O and δ2H values of fruit is of scientific interest.

Do 2 H and 18 O in leaf water reflect environmental drivers differently?

We compiled hydrogen and oxygen stable isotope compositions (δ² H and δ¹⁸ O) of leaf water from multiple biomes to examine variations with environmental drivers. Leaf water δ² H was more closely correlated with δ² H of xylem water or atmospheric vapour, whereas leaf water δ¹⁸ O was more closely correlated with air relative humidity. This resulted from the larger proportional range for δ² H of meteoric waters relative to the extent of leaf water evaporative enrichment compared with δ¹⁸ O. We next expressed leaf water as isotopic enrichment above xylem water (Δ² H and Δ¹⁸ O) to remove the impact of xylem water isotopic variation. For Δ² H, leaf water still correlated with atmospheric vapour, whereas Δ¹⁸ O showed no such correlation. This was explained by covariance between air relative humidity and the Δ¹⁸ O of atmospheric vapour. This is consistent with a previously observed diurnal correlation between air relative humidity and the deuterium excess of atmospheric vapour across a range of ecosystems. We conclude that ² H and ¹⁸ O in leaf water do indeed reflect the balance of environmental drivers differently; our results have implications for understanding isotopic effects associated with water cycling in terrestrial ecosystems and for inferring environmental change from isotopic biomarkers that act as proxies for leaf water.

Effects of phenotypic variability on the oxygen and hydrogen isotope compositions of grains in different winter wheat varieties

Stable isotope analyses are the leading method for geographic origin determination, especially of plant-based agricultural products. Origin analysis is typically done by comparing a suspicious sample to reference materials with known geographic origin. Reference materials are usually collected at the species level, assuming different varieties of a species to have comparable isotope compositions within a given location. We evaluated whether different phenotypes that are expressed in different varieties of winter wheat (Triticum aestivum L.) influence the oxygen (δ¹⁸O) and hydrogen (δ²H) isotope composition of plant tissue water and organic compounds. We found that mean δ¹⁸O and δ²H values among winter wheat varieties did not differ significantly in leaf water, however, differed significantly in bulk dried grain tissue. The differences in bulk dried grain δ¹⁸O and δ²H values among varieties can be related to differences in phenotypic trait expression among varieties. Despite this substantial phenotypic variability, the overall variability of bulk dried grain δ¹⁸O and δ²H values among varieties was small (SD 0.54 ‰ for oxygen, 3.60 ‰ for hydrogen). We thus conclude that reference materials collected at the species level should be sufficient for geographic origin analysis of winter wheat and possibly other cereals using δ¹⁸O and δ²H values.

Metabolic exchange between pathways for isoprenoid synthesis and implications for biosynthetic hydrogen isotope fractionation

Hydrogen isotope ratios of plant lipids are used for paleoclimate reconstruction, but are influenced by both source water and biosynthetic processes. Measuring ² H : ¹ H ratios of multiple compounds produced by different pathways could allow these effects to be separated, but hydrogen isotope fractionations during isoprenoid biosynthesis remain poorly constrained. To investigate how hydrogen isotope fractionation during isoprenoid biosynthesis is influenced by molecular exchange between the cytosolic and plastidial production pathways, we paired position-specific ¹³ C-pyruvate labeling with hydrogen isotope measurements of lipids in Pachira aquatica saplings. We find that acetogenic compounds primarily incorporated carbon from ¹³ C2-pyruvate, whereas isoprenoids incorporated ¹³ C1- and ¹³ C2-pyruvate equally. This indicates that cytosolic pyruvate is primarily introduced into plastidial isoprenoids via glyceraldehyde 3-phosphate and that plastidial isoprenoid intermediates are incorporated into cytosolic isoprenoids. Probably as a result of the large differences in hydrogen isotope fractionation between plastidial and cytosolic isoprenoid pathways, sterols from P. aquatica are at least 50‰ less ² H-enriched relative to phytol than sterols in other plants. These results provide the first experimental evidence that incorporation of plastidial intermediates reduces ² H : ¹ H ratios of sterols. This suggests that relative offsets between the ² H : ¹ H ratios of sterols and phytol can trace exchange between the two isoprenoid synthesis pathways.

Using plant physiological stable oxygen isotope models to counter food fraud

Fraudulent food products, especially regarding false claims of geographic origin, impose economic damages of $30-$40 billion per year. Stable isotope methods, using oxygen isotopes (δ18O) in particular, are the leading forensic tools for identifying these crimes. Plant physiological stable oxygen isotope models simulate how precipitation δ18O values and climatic variables shape the δ18O values of water and organic compounds in plants. These models have the potential to simplify, speed up, and improve conventional stable isotope applications and produce temporally resolved, accurate, and precise region-of-origin assignments for agricultural food products. However, the validation of these models and thus the best choice of model parameters and input variables have limited the application of the models for the origin identification of food. In our study we test model predictions against a unique 11-year European strawberry δ18O reference dataset to evaluate how choices of input variable sources and model parameterization impact the prediction skill of the model. Our results show that modifying leaf-based model parameters specifically for fruit and with product-independent, but growth time specific environmental input data, plant physiological isotope models offer a new and dynamic method that can accurately predict the geographic origin of a plant product and can advance the field of stable isotope analysis to counter food fraud.

Changes in Coverage, Access, and Health Following Implementation of Healthy Behavior Incentive Medicaid Expansions vs. Traditional Medicaid Expansions

BACKGROUND

Several states expanded Medicaid under the Affordable Care Act using Section 1115 waivers to implement healthy behavior incentive (HBI) programs, but the impact of this type of expansion relative to traditional expansion is not well understood.

OBJECTIVE

To examine whether Medicaid expansion with healthy behavior incentive programs and traditional Medicaid expansion were associated with differential changes in coverage, access, and self-rated health outcomes among low-income adults.

DESIGN

Difference-in-differences analysis of American Community Survey and Behavioral Risk Factor Surveillance System data from 2011 to 2017.

PARTICIPANTS

Low-income adults ages 19-64 in the Midwest Census region (American Community Survey, n = 665,653; Behavioral Risk Factor Surveillance System, n = 71,959).

INTERVENTIONS

Exposure to either HBI waiver or traditional Medicaid expansion in the state of residence.

MAIN MEASURES

Coverage: Medicaid, private, or any health insurance coverage; access: routine checkup, personal doctor, delaying care due to cost; health: cancer screening, preventive care, healthy behaviors, self-reported health.

KEY RESULTS

Healthy behavior incentive (HBI) and traditional expansion (TE) states experienced reductions in uninsurance (- 5.6 [- 7.5, - 3.7] and - 6.2 [- 8.1, - 4.4] percentage points, respectively) and gains in Medicaid (HBI, + 7.6 [2.4, 12.8]; TE, + 9.7 [5.9, 13.4] percentage points) relative to non-expansion states. Both expansion types were associated with increases in rates of having a personal doctor (HBI, + 3.8 [2.0, 5.6]; TE, + 5.9 [2.2, 9.6] percentage points) and mammography (HBI, + 5.6 [0.6, 10.6]; TE, + 7.3 [0.7, 13.9] percentage points). Meanwhile, checkups increased more in HBI than in TE states (p < 0.01), but no other changes in health care services differed between expansion types.

CONCLUSIONS

Medicaid expansion was associated with improvements in coverage and access to care with few differences between expansion types.

Morbidity following salvage esophagectomy for squamous cell carcinoma: the MD Anderson experience

The survival advantage associated with the addition of surgical therapy in esophageal squamous cell carcinoma (ESCC) patients who demonstrate a complete clinical response to chemoradiotherapy is unclear, and many institutions have adopted an organ-preserving strategy of selective surgery in this population. We sought to characterize our institutional experience of salvage esophagectomy (for failure of definitive bimodality therapy) and planned esophagectomy (as a component of trimodality therapy) by retrospectively analyzing patients with ESCC of the thoracic esophagus and GEJ who underwent esophagectomy following chemoradiotherapy between 2004 and 2016. Of 76 patients who met inclusion criteria, 46.1% (35) underwent salvage esophagectomy. Major postoperative complications (major cardiovascular and pulmonary events, anastomotic leak [grade ≥ 2], and 90-day mortality) were frequent and occurred in 52.6% of the cohort (planned resection: 36.6% [15/41]; salvage esophagectomy: 71.4% [25/35]). Observed rates of 30- and 90-day mortality for the entire cohort were 7.9% (planned: 7.3% [3/41]; salvage: 8.6% [3/35]) and 13.2% (planned: 9.8% [4/41]; salvage: 17.1% [6/35]), respectively. In summary, esophagectomy following chemoradiotherapy for ESCC at our institution has been associated with frequent postoperative morbidity and considerable rates of mortality in both planned and salvage settings. Although a selective approach to surgery may permit organ preservation in many patients with ESCC, these results highlight that salvage esophagectomy for failure of definitive-intent treatment of ESCC may also constitute a difficult clinical undertaking in some cases.

Expansion by Ballot Initiative: Challenges and Future Directions in Health Policy

Since 2017, four states have successfully adopted the Medicaid expansion through ballot initiative. We analyze how states could potentially use ballot initiatives to implement these programs. We find there are serious legal and political challenges to expansion by initiative. Only six non-expansion states allow for a ballot initiative to pass and implement the Medicaid expansion. Amongst those states, there are challenges that limit the development, scope, and implementation of an initiative. Whether a state adopts the Medicaid expansion has important implications for health care providers.

Aging impairs mouse skeletal muscle macrophage polarization and muscle-specific abundance during recovery from disuse

Impaired recovery of aged muscle following a disuse event is an unresolved issue facing the older adult population. Although investigations in young animals have suggested that rapid regrowth of skeletal muscle following a disuse event entails a coordinated involvement of skeletal muscle macrophages, this phenomenon has not yet been thoroughly tested as an explanation for impaired muscle recovery in aging. To examine this hypothesis, young (4-5 mo) and old (24-26 mo) male mice were examined as controls following 2 wk of hindlimb unloading (HU) and following 4 (RL4) and 7 (RL7) days of reloading after HU. Muscles were harvested to assess muscle weight, myofiber-specifc cross-sectional area, and skeletal muscle macrophages via immunofluorescence. Flow cytometry was used on gastrocnemius and soleus muscle (at RL4) single-cell suspensions to immunophenotype skeletal muscle macrophages. Our data demonstrated impaired muscle regrowth in aged compared with young mice following disuse, which was characterized by divergent muscle macrophage polarization patterns and muscle-specifc macrophage abundance. During reloading, young mice exhibited the classical increase in M1-like (MHC II⁺CD206^-) macrophages that preceeded the increase in percentage of M2-like macrophages (MHC II^-CD206⁺); however, old mice did not demonstrate this pattern. Also, at RL4, the soleus demonstrated reduced macrophage abundance with aging. Together, these data suggest that dysregulated macrophage phenotype patterns in aged muscle during recovery from disuse may be related to impaired muscle growth. Further investigation is needed to determine whether the dysregulated macrophage response in the old during regrowth from disuse is related to a reduced ability to recruit or activate specific immune cells.

Population-level factors associated with maternal mortality in the United States, 1997-2012

Background

In contrast to peer nations, the United States is experiencing rapid increases in maternal mortality. Trends in individual and population-level demographic factors and health trends may play a role in this change.

Methods

We analyzed state-level maternal mortality for the years 1997–2012 using multilevel mixed-effects regression grouped by state, using publicly available data including whether a state had adopted the 2003 U.S. Standard Certificate of Death, designed to simplify identification of pregnant and recently pregnant decedents. We calculated the proportion of the increase in maternal mortality attributable to specific factors during the study period.

Results

Maternal mortality was associated with higher population prevalence of obesity and high school non-completion among women of childbearing age; these factors explained 31.0% and 5.3% of the attributable increase in maternal mortality during the study period, respectively. Among delivering mothers, prevalence of diabetes (17.0%), attending fewer than 10 prenatal visits (4.9%), and African American race (2.0%) were also associated with higher maternal mortality, as was time-varying state adoption of the 2003 death certificate (31.1%).

Conclusions

Our findings indicate that, in addition to better case ascertainment of maternal deaths, adverse changes in chronic diseases, insufficient healthcare access, and social determinants of health represent identifiable risks for maternal mortality that merit prompt attention in population-directed interventions and health policies.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5935-2) contains supplementary material, which is available to authorized users.

Sequence-specific DNA solid-phase extraction in an on-chip monolith: Towards detection of antibiotic resistance genes

Antibiotic resistance of bacteria is a growing problem and presents a challenge for prompt treatment in patients with sepsis. Currently used methods rely on culturing or amplification; however, these steps are either time consuming or suffer from interference issues. A microfluidic device was made from black polypropylene, with a monolithic column modified with a capture oligonucleotide for sequence selective solid-phase extraction of a complementary target from a lysate sample. Porous properties of the monolith allow flow and hybridization of a target complementary to the probe immobilized on the column surface. Good flow-through properties enable extraction of a 100μL sample and elution of target DNA in 12min total time. Using a fluorescently labeled target oligonucleotide related to Verona Integron-Mediated Metallo-β-lactamase it was possible to extract and detect a 1pM sample with 83% recovery. Temperature-mediated elution by heating above the duplex melting point provides a clean extract without any agents that interfere with base pairing, allowing various labeling methods or further downstream processing of the eluent. Further integration of this extraction module with a system for isolation and lysis of bacteria from blood, as well as combining with single-molecule detection should allow rapid determination of antibiotic resistance.

Diabetic ketoacidosis complicating pregnancy

BACKGROUND

Although diabetic ketoacidosis (DKA) in pregnancy can result in significant adverse consequences for both mother and fetus, the response to treatment, time course of recovery, and perinatal outcomes have not been well studied in pregnancy.

OBJECTIVE

We examined the precipitating factors, laboratory abnormalities, treatment strategies, and clinical recovery in pregnancies complicated by DKA.

STUDY DESIGN

This is a retrospective cohort study of pregnancies complicated by DKA between October 1999 and June 2015. The diagnosis was verified by hyperglycemia; anion gap >12 mEq/L, pH <7.3, HCO3 <15 mEq/L; and the presence of ketones. Each episode of DKA was reviewed and subsequent perinatal outcomes analyzed.

RESULTS

During this period, we identified 33 women with 40 admissions (incidence: 0.2%). The majority of women had type 1 diabetes (67%), and almost all presented with nausea and vomiting (97%). Over half had poor compliance with prescribed insulin. The initial mean blood glucose was 380 mg/dL, within 6 hours, it was <200 mg/dL. By 12 hours, the acidosis had resolved in 90% of patients.

CONCLUSION

Nausea and vomiting is a prominent presenting feature of DKA in pregnancy. With aggressive insulin and resuscitation, hyperglycemia and acidosis improve rapidly. With current treatment, good perinatal outcomes can be expected.

Cluster Analysis of Acute Care Use Yields Insights for Tailored Pediatric Asthma Interventions

STUDY OBJECTIVE

We undertake this study to understand patterns of pediatric asthma-related acute care use to inform interventions aimed at reducing potentially avoidable hospitalizations.

METHODS

Hospital claims data from 3 Camden city facilities for 2010 to 2014 were used to perform cluster analysis classifying patients aged 0 to 17 years according to their asthma-related hospital use. Clusters were based on 2 variables: asthma-related ED visits and hospitalizations. Demographics and a number of sociobehavioral and use characteristics were compared across clusters.

RESULTS

Children who met the criteria (3,170) were included in the analysis. An examination of a scree plot showing the decline in within-cluster heterogeneity as the number of clusters increased confirmed that clusters of pediatric asthma patients according to hospital use exist in the data. Five clusters of patients with distinct asthma-related acute care use patterns were observed. Cluster 1 (62% of patients) showed the lowest rates of acute care use. These patients were least likely to have a mental health-related diagnosis, were less likely to have visited multiple facilities, and had no hospitalizations for asthma. Cluster 2 (19% of patients) had a low number of asthma ED visits and onetime hospitalization. Cluster 3 (11% of patients) had a high number of ED visits and low hospitalization rates, and the highest rates of multiple facility use. Cluster 4 (7% of patients) had moderate ED use for both asthma and other illnesses, and high rates of asthma hospitalizations; nearly one quarter received care at all facilities, and 1 in 10 had a mental health diagnosis. Cluster 5 (1% of patients) had extreme rates of acute care use.

CONCLUSION

Differences observed between groups across multiple sociobehavioral factors suggest these clusters may represent children who differ along multiple dimensions, in addition to patterns of service use, with implications for tailored interventions.

Understanding type 2 diabetes mellitus screening practices among primary care physicians: a qualitative chart-stimulated recall study

Background

Early diagnosis and treatment of prediabetes and type 2 diabetes mellitus (T2DM) can prevent future health problems, yet many individuals with these conditions are undiagnosed. This could be due, in part, to primary care physicians’ (PCP) screening practices, about which little is known. The objectives of this study were to identify factors that influence PCPs’ decisions to screen patients for T2DM and to characterize their interpretation and communication of screening test results to patients.

Methods

We conducted semi-structured chart-stimulated recall interviews with 20 University of Michigan Health System (UMHS) primary care physicians. PCPs were asked about their recent decisions to screen or not screen 134 purposively sampled non-diabetic patients who met American Diabetes Association criteria for screening for T2DM. Interviews were audio-recorded, transcribed, and analyzed using qualitative directed content analysis. Data on patient demographic characteristics and comorbidities were abstracted from the electronic health record.

Results

The most common reasons PCPs gave for not screening 63 patients for T2DM were knowledge of a previously normal screening test (49%) and a visit for reasons other than a health maintenance examination (48%). The most common reasons PCPs gave for screening 71 patients for T2DM were knowledge of a previously abnormal screening test (49%), and patients’ weight (42%) and age (38%). PCPs correctly interpreted 89% of screening test results and communicated 95% of test results to patients. Among 24 patients found to have prediabetes, PCPs usually (58%) recommended weight loss and increased physical activity but never recommended participation in a Diabetes Prevention Program or use of metformin.

Conclusions

Previous screening test results, visit types, and patients’ weight and age influenced PCPs’ decisions to screen for T2DM. When patients were screened, test results were generally correctly interpreted and consistently communicated. Recommendations to patients with prediabetes could better reflect evidence-based strategies to prevent T2DM.

Electronic supplementary material

The online version of this article (doi:10.1186/s12875-017-0623-3) contains supplementary material, which is available to authorized users.

A Quadruplex Real-Time PCR Assay for the Rapid Detection and Differentiation of the Most Relevant Members of the B. pseudomallei Complex: B. mallei, B. pseudomallei, and B. thailandensis

The Burkholderia pseudomallei complex classically consisted of B. mallei, B. pseudomallei, and B. thailandensis, but has now expanded to include B. oklahomensis, B. humptydooensis, and three unassigned Burkholderia clades. Methods for detecting and differentiating the B. pseudomallei complex has been the topic of recent research due to phenotypic and genotypic similarities of these species. B. mallei and B. pseudomallei are recognized as CDC Tier 1 select agents, and are the causative agents of glanders and melioidosis, respectively. Although B. thailandensis and B. oklahomensis are generally avirulent, both display similar phenotypic characteristics to that of B. pseudomallei. B. humptydooensis and the Burkholderia clades are genetically similar to the B. pseudomallei complex, and are not associated with disease. Optimal identification of these species remains problematic, and PCR-based methods can resolve issues with B. pseudomallei complex detection and differentiation. Currently, no PCR assay is available that detects the major species of the B. pseudomallei complex. A real-time PCR assay in a multiplex single-tube format was developed to simultaneously detect and differentiate B. mallei, B. pseudomallei, and B. thailandensis, and a common sequence found in B. pseudomallei, B. mallei, B. thailandensis, and B. oklahomensis. A total of 309 Burkholderia isolates and 5 other bacterial species were evaluated. The assay was 100% sensitive and specific, demonstrated sensitivity beyond culture and GC methods for the isolates tested, and is completed in about an hour with a detection limit between 2.6pg and 48.9pg of gDNA. Bioinformatic analyses also showed the assay is likely 100% specific and sensitive for all 84 fully sequenced B. pseudomallei, B. mallei, B. thailandensis, and B. oklahomensis strains currently available in GenBank. For these reasons, this assay could be a rapid and sensitive tool in the detection and differentiation for those species of the B. pseudomallei complex with recognized clinical and practical significance.

Crisaborole and its potential role in treating atopic dermatitis: overview of early clinical studies

Atopic dermatitis (AD), a chronic, relapsing, inflammatory skin disease that is characterized by intense pruritus and eczematous lesions with up to 90% of patients presenting with mild to moderate disease. Current topical treatments for AD have not changed in over 15 years and are associated with safety concerns. In AD, overactivity of phosphodiesterase 4 (PDE4), leads to inflammation and disease exacerbation. Crisaborole Topical Ointment, 2%, is a novel, nonsteroidal, topical anti-inflammatory PDE4 inhibitor currently being investigated for the treatment of mild to moderate AD. Preliminary studies in children and adults demonstrated favorable efficacy and safety profiles. Crisaborole may represent an anti-inflammatory option that safely minimizes the symptoms and severity of AD and that can be used for both acute and long-term management.

Early pregnancy changes in bacterial vaginosis-associated bacteria and preterm delivery

BACKGROUND

We evaluated the importance of measuring early vaginal levels of eight bacterial vaginosis (BV)-associated bacteria, at two points in pregnancy, and the risk of spontaneous preterm delivery (SPTD) among pregnant women and the subgroup of pregnant women with a history of preterm delivery (PTD).

METHODS

This prospective cohort study enrolled women at five urban obstetric practices at Temple University Hospital in Philadelphia PA. Women with singleton pregnancies less than 16 weeks gestation self-collected vaginal swabs at two points in pregnancy, prior to 16 weeks gestation and between 20-24 weeks gestation, to measure the presence and level of eight BV-associated bacteria. Women were followed-up for gestational age at delivery via medical records.

RESULTS

Among women reporting a prior PTD, women with higher levels of Leptotrichia/Sneathia species, BVAB1 and Mobiluncus spp., prior to 16 weeks gestation, were significantly more likely to experience a SPTD. In addition, pregnant women with a prior PTD and increasing levels of Leptotrichia/Sneathia species (aOR: 9.1, 95% CI 1.9, 42.9), BVAB1 (aOR: 16.4, 95% CI 4.3, 62.7) or Megasphaera phylotype 1 (aOR: 6.2, 95% CI 1.9, 20.6), through 24 weeks gestation, were significantly more likely to experience an SPTD. Among the overall group of pregnant women, the levels of BV-associated bacteria were not related to SPTD.

CONCLUSION

Among the group of women reporting a prior PTD, increasing levels of BVAB1, Leptotrichia/Sneathia species, and Megasphaera phylotype 1, through mid-pregnancy were related to an increased risk of SPTD.

Risk factors for severe delayed postpolypectomy bleeding

BACKGROUND AND STUDY AIMS

Postpolypectomy bleeding is a rare but serious adverse event. The aim of this study was to identify factors associated with the risk of severe delayed postpolypectomy bleeding.

PATIENTS AND METHODS

This was a case-control study, comparing cases who developed hematochezia and required medical evaluation 6 hours to 14 days after colonoscopic polypectomy, and control patients who underwent polypectomy without delayed bleeding, and who were selected in approximately a 3 : 1 ratio. The following risk factors were specified a priori: resuming anticoagulation (within 1 week following polypectomy), aspirin use, hypertension, and polyp diameter.

RESULTS

Of the 4592 patients who underwent colonoscopy with polypectomy, 41 patients (0.9 %) developed delayed postpolypectomy bleeding (cases), and 132 patients were selected as controls. The mean age was 64.3 years for cases and 65.4 years for controls. Cases presented on average 6 days after polypectomy (range 1 - 14 days), and 48 % required blood transfusion (average 4.2 units, range 0 - 17). Two patients required surgery. Anticoagulation was resumed following polypectomy in 34 % of cases compared with 9 % of controls (OR 5.2; 95 % CI 2.2 - 12.5; P < 0.001). For every 1 mm increase in polyp diameter, the risk of hemorrhage increased by 9 % (OR 1.09; 95 % CI 1.0 - 1.2; P = 0.008). Hypertension (OR 1.1) and aspirin use (OR 1.1) did not increase the risk of postpolypectomy bleeding. In exploratory analysis, diabetes (OR 2.5) and coronary artery disease (OR 3.0) were associated with postpolypectomy hemorrhage, but the association was no longer statistically significant once adjusted for the use of anticoagulation.

CONCLUSIONS

Resuming anticoagulation following polypectomy and polyp diameter were strongly associated with increased risk of severe delayed postpolypectomy bleeding.

Vaginal symptoms and bacterial vaginosis (BV): how useful is self-report? Development of a screening tool for predicting BV status

Vaginal complaints compel an evaluation of bacterial vaginosis (BV), however, many cases of BV are asymptomatic. We evaluated the sensitivity and specificity of vaginal symptoms in the diagnosis of BV and examined the utility of creating a BV screening tool using clinical, behavioural and demographic characteristics. A total of 1916 pregnant women were included in this analysis. In total, 757 women screened positive for BV and over one third of BV-positive women presented without any lower genital tract symptoms (39.4%). African American race, abnormal vaginal odour, and smoking were independently related to BV positivity. A BV screening tool including these three factors was fairly predictive of BV status with the area under the ROC curve equal to 0.669. This three-item prediction rule may be useful in identifying high- risk pregnant women in need of BV screening and, given the high specificity, accurately identify the group of BV-negative pregnant women.

A trial of education, prompts, and opinion leaders to improve prescription of lipid modifying therapy by primary care physicians for patients with ischemic heart disease

BACKGROUND

Recent clinical trials indicate that treatment with lipid modifying therapy improves outcomes in patients with ischemic heart disease (IHD) and low levels of high density lipoprotein (HDL) cholesterol. The results of these trials, however, have not been widely implemented in clinical practice.

OBJECTIVES

To develop and test an intervention designed to increase the rate of prescription of lipid modifying therapy and to determine the relative effectiveness of three different prompts (progress notes, patient letters, or computer chart reminders).

METHODS

The study was conducted in 11 US Department of Veterans Affairs Medical Centers. The effect of the intervention on the proportion of eligible patients receiving lipid modifying therapy was compared between five intervention sites and six matched control sites using a controlled before and after study design. Additionally, 92 providers within the intervention clinics were randomized to receive one of the three prompts. Data were analyzed using logistic regression modeling which incorporated terms to account for the clustered nature of the data.

RESULTS

At the intervention sites the prescription rate increased from 8.3% during the pre-intervention period to 39.1% during the intervention (OR = 6.5, 95% CI 5.2 to 8.2, p<0.0001) but remained unchanged at the control sites. The interaction between group (control v intervention) and time period was highly significant (p<0.0001). The adjusted odds of receiving a prescription during the intervention period was 3.1 times higher at the intervention sites than at the control sites (95% CI 2.1 to 4.7). Overall, there was no significant difference in prescription rates among the three prompt groups. However, there was a significant interaction between prompt group and site, indicating that the efficacy of the prompts differed by site.

CONCLUSION

An intervention for primary care providers consisting of an educational workshop, opinion leader influence, and prompts substantially increased the prescription rate of lipid modifying therapy.

Follicular phase hormone levels and menstrual bleeding status in the approach to menopause

OBJECTIVE

(1) Characterize the relationship between follicular phase hormone levels and menstrual bleeding patterns in the approach to menopause; (2) identify racial differences in hormone levels; (3) determine independent contributions of menstrual status, race, age, BMI, and smoking to hormone levels.

DESIGN

Randomly identified, population-based cohort, stratified to obtain equal numbers of African American and Caucasian women, prospectively followed for 5 years.

SETTING

Women in Philadelphia County, PA, identified by random-digit telephone dialing.

PARTICIPANT(S)

Women aged 35 to 47 years with regular menstrual cycles at enrollment (N = 436).

DATA COLLECTION

Blood sampling twice in each of 7 assessment periods during days 1-6 of the cycle, menstrual dates identified through structured interview and daily symptom reports, anthropometric measures and standardized questionnaires at each assessment period.

MAIN OUTCOME MEASURE(S)

Serum levels of follicular E(2), FSH, inhibin B, and LH.

RESULT(S)

The mean levels of E(2), FSH, inhibin B, and LH were differentially associated with the 5 menstrual status groups defined by changes in bleeding patterns. Significant changes in hormone levels occurred prior to missed menstrual cycles for inhibin B, FSH, and LH. All hormones had a highly significant interaction between menstrual status and BMI. African American women had significantly lower levels of E(2) and LH compared to Caucasian women in univariate analyses. The interaction of race, menstrual status, and BMI was highly significant (P<.001) for E(2), with African American women having lower E(2) levels until postmenopause, when E(2) levels were higher in AA women with BMI > or =25 and BMI > or =30.

CONCLUSION(S)

Levels of E(2), FSH, LH, and inhibin B are significantly associated with menstrual bleeding patterns in late reproductive age women and differentiate the earliest stages of the menopausal transition. Racial differences in mean levels of E(2) appear strongly mediated by BMI.

Disability after clinical fracture in postmenopausal women with low bone density: the fracture intervention trial (FIT)

Relatively little is known about outcomes following clinical osteoporotic fractures at nonhip, nonvertebral skeletal sites. To address this issue, we prospectively assessed post-fracture disability at multiple skeletal sites in a population of 909 older (aged 55-81 years), community-dwelling women with low femoral neck bone mineral density who had experienced a fracture while enrolled in the Fracture Intervention Trial (FIT). FIT is a randomized, double-masked, placebo-controlled trial that was designed to determine the effect of alendronate on fracture incidence, and the current study was conducted as a secondary analysis of FIT data. Following incident clinical fractures, FIT participants were followed prospectively for assessment of site-specific, fracture-related disability. Measures of disability were self-reported days hospitalized or confined to bed because of the fracture ('bed days') and days of reduced usual activities because of the fracture ('limited activity days'). Of fracture types evaluated, those of the hip resulted in the highest percentage of subjects with any bed days or limited activity days after fracture (94% with any bed days and 100% with any limited activity days), though the mean number of bed days and limited activity days appeared highest after lumbar vertebral fractures (25.8 mean bed days and 158.5 mean limited activity days). Substantial disability also was reported after fractures of thoracic vertebrae, humerus, distal forearm, ankle and foot. Within fracture types, post-fracture disability was highly variable, ranging from none to more than 6 months.

Sex hormones, hemostasis and early pregnancy loss

AIMS

This study was designed to determine the association between coagulation factors and spontaneous abortion adjusting for sex steroids and to examine the influence of sex hormones on coagulation factors early in pregnancy.

METHODS

Pregnant women presenting to the emergency department at the Hospital of the University of Pennsylvania were recruited and followed through 22 weeks gestation. Cases were women who experienced a spontaneous abortion (n=29) and controls were women who maintained their pregnancy to 22 weeks gestation (n=89). Participants completed a baseline questionnaire to assess demographic, reproductive, and drug use information. Blood samples measured estradiol, progesterone, fibrinogen, and factor VII antigen.

RESULTS

Cases of spontaneous abortion had significantly lower levels of estradiol, progesterone, fibrinogen and factor VII antigen compared to controls. The relationship between low levels of fibrinogen and factor VII antigen was diminished adjusting for the sex steroids. Regression analyses found low progesterone was the primary prospective marker for early pregnancy loss among our study population.

CONCLUSIONS

The relationship between coagulation factors and spontaneous abortion was reduced after adjustment for progesterone suggesting that progesterone mediates the relationship between low levels of coagulation factors and spontaneous abortion. Progesterone seems to be the primary marker for a spontaneous abortion among women seeking emergent care.

Risk factors for post-ERCP pancreatitis: a prospective, multicenter study

BACKGROUND

Post-ERCP pancreatitis is poorly understood. The goal of this study was to comprehensively evaluate potential procedure- and patient-related risk factors for post-ERCP pancreatitis over a wide spectrum of centers.

METHODS

Consecutive ERCP procedures were prospectively studied at 11 centers (6 private, 5 university). Complications were assessed at 30 days by using established consensus criteria.

RESULTS

Pancreatitis occurred after 131 (6.7%) of 1963 consecutive ERCP procedures (mild 70, moderate 55, severe 6). By univariate analysis, 23 of 32 investigated variables were significant. Multivariate risk factors with adjusted odds ratios (OR) were prior ERCP-induced pancreatitis (OR 5.4), suspected sphincter of Oddi dysfunction (OR 2.6), female gender (OR 2.5), normal serum bilirubin (OR 1.9), absence of chronic pancreatitis (OR 1.9), biliary sphincter balloon dilation (OR 4.5), difficult cannulation (OR 3.4), pancreatic sphincterotomy (OR 3.1), and 1 or more injections of contrast into the pancreatic duct (OR 2.7). Small bile duct diameter, sphincter of Oddi manometry, biliary sphincterotomy, and lower ERCP case volume were not multivariate risk factors for pancreatitis, although endoscopists performing on average more than 2 ERCPs per week had significantly greater success at bile duct cannulation (96.5% versus 91.5%, p = 0.0001). Combinations of patient characteristics including female gender, normal serum bilirubin, recurrent abdominal pain, and previous post-ERCP pancreatitis placed patients at increasingly higher risk of pancreatitis, regardless of whether ERCP was diagnostic, manometric, or therapeutic.

CONCLUSIONS

Patient-related factors are as important as procedure-related factors in determining risk for post-ERCP pancreatitis. These data emphasize the importance of careful patient selection as well as choice of technique in the avoidance of post-ERCP pancreatitis.

Do clerkship experiences affect medical students' attitudes toward chronically ill patients?

PURPOSE

To measure changes in medical students' attitudes toward chronically ill patients, and to identify experiences, specifically during clerkships, that contributed to students' attitudes.

METHOD

A cohort of students from five U.S. medical schools voluntarily participated in three surveys longitudinally administered before and after required clinical rotations. The first two questionnaires were identical and asked for demographic information and pre-matriculation experiences with chronically ill patients. The third was modified to include questions about clinical experiences with chronically ill patients. Responses from the first and third questionnaires were linked for analysis.

RESULTS

A total of 502 of 695 students (69%) completed both the first and the third questionnaires. Many students (36%) had had pre-matriculation experiences with chronic illness. After clinical training, 25% of the respondents stated that they would seek another career specialty if the incidence of chronically ill patients increased in their chosen field, compared with the 9% who responded so before clinical training (p <.001). While 73% of the students had favorable perceptions toward chronically ill patients, and 91% felt involved in care, significantly fewer students (p <.01) had had positive patient care experiences when working with residents (57%) and attendings (59%). Gender, age, prior experiences, and school site were not associated with attitudinal changes.

CONCLUSION

Students begin medical school with positive attitudes toward caring for chronically ill patients, but this perception depreciates with clinical experience, which may affect specialty decisions. Contributing factors may include adequate role modeling by residents and attendings and a perceived discrepancy in the quality of care patients receive.

Influence of hemostatic factors on spontaneous abortion

To assess the relationship between hemostatic factors and spontaneous abortion, 134 pregnant women presenting to the emergency department were recruited and followed through 22 weeks' gestation. Cases were women experiencing a spontaneous abortion and controls were women who maintained their pregnancy. Fibrinogen, factor VII antigen, activated protein C-sensitivity ratio (APC-SR), protein S, and plasmin-antiplasmin (PAP) were measured. Cases had lower mean levels of fibrinogen and factor VII antigen compared with controls (3.1 g/L vs. 3.7 g/L and 89% of normal vs. 109% of normal, respectively). Regression analyses found that women with fibrinogen levels below 3.0 g/L had a five-fold increased risk of spontaneous abortion (OR = 5.1, 95% CI: 1.8-14.4) and women with factor VII antigen levels below 94% of normal had a threefold increased risk of spontaneous abortion normal (OR = 3.3, 95% CI: 1.2-8.5). Similar mean levels of APC-SR, protein S, and PAP were found in the two groups.