Systemic and myocardial hemodynamics during periodic obstructive apneas in sedated pigs

The effects of periodic obstructive apneas onsystemic and myocardial hemodynamics were studied in ninepreinstrumented sedated pigs under four conditions: breathing room air(RA), breathing 100% O₂,breathing RA after critical coronary stenosis (CS) of the left anteriordescending coronary artery, and breathing RA after autonomic blockadewith hexamethonium (Hex). Apneas with RA increased mean arterialpressure (MAP; from baseline 103.0 ± 3.5 to late apnea 123.6 ± 7.0 Torr, P < 0.001) and coronary blood flow (CBF; late apnea 193.9 ± 22.9% of baseline,P < 0.001) but decreased cardiacoutput (CO; from baseline 2.97 ± 0.15 to late apnea 2.39 ± 0.19 l/min, P < 0.001). Apneas withO₂ increased MAP (from baseline105.1 ± 4.6 to late apnea 110.7 ± 4.8 Torr, P < 0.001). Apneas with CS producedsimilar increases in MAP as apneas with RA but greater decreases in CO(from baseline 3.03 ± 0.19 to late apnea 2.1 ± 0.15 l/min,P < 0.001). In LAD-perfused myocardium, there was decreased segmental shortening (baseline 11.0 ± 1.5 to late apnea 7.6 ± 2.0%,P < 0.01) and regionalintramyocardial pH (baseline 7.05 ± 0.03 to late apnea 6.72 ± 0.11, P < 0.001) during apneas withCS but under no other conditions. Apneas with Hex increased to the sameextent as apneas with RA. Myocardial O₂ demand remained unchangedduring apnea relative to baseline. We conclude that obstructiveapnea-induced changes in left ventricular afterload and CO aresecondary to autonomic-mediated responses to hypoxemia. Increased CBFduring apneas is related to regional metabolic effects of hypoxia andnot to autonomic factors. In the presence of limited coronary flowreserve, decreased O₂ supply during apneas can lead to myocardial ischemia, which in turnadversely affects left ventricular function.

     

Effect of ambient air pollution on the incidence of appendicitis

Background

The pathogenesis of appendicitis is unclear. We evaluated whether exposure to air pollution was associated with an increased incidence of appendicitis.

Methods

We identified 5191 adults who had been admitted to hospital with appendicitis between Apr. 1, 1999, and Dec. 31, 2006. The air pollutants studied were ozone, nitrogen dioxide, sulfur dioxide, carbon monoxide, and suspended particulate matter of less than 10 μ and less than 2.5 μ in diameter. We estimated the odds of appendicitis relative to short-term increases in concentrations of selected pollutants, alone and in combination, after controlling for temperature and relative humidity as well as the effects of age, sex and season.

Results

An increase in the interquartile range of the 5-day average of ozone was associated with appendicitis (odds ratio [OR] 1.14, 95% confidence interval [CI] 1.03–1.25). In summer (July–August), the effects were most pronounced for ozone (OR 1.32, 95% CI 1.10–1.57), sulfur dioxide (OR 1.30, 95% CI 1.03–1.63), nitrogen dioxide (OR 1.76, 95% CI 1.20–2.58), carbon monoxide (OR 1.35, 95% CI 1.01–1.80) and particulate matter less than 10 μ in diameter (OR 1.20, 95% CI 1.05–1.38). We observed a significant effect of the air pollutants in the summer months among men but not among women (e.g., OR for increase in the 5-day average of nitrogen dioxide 2.05, 95% CI 1.21–3.47, among men and 1.48, 95% CI 0.85–2.59, among women). The double-pollutant model of exposure to ozone and nitrogen dioxide in the summer months was associated with attenuation of the effects of ozone (OR 1.22, 95% CI 1.01–1.48) and nitrogen dioxide (OR 1.48, 95% CI 0.97–2.24).

Interpretation

Our findings suggest that some cases of appendicitis may be triggered by short-term exposure to air pollution. If these findings are confirmed, measures to improve air quality may help to decrease rates of appendicitis.Appendicitis was introduced into the medical vernacular in 1886.¹ Since then, the prevailing theory of its pathogenesis implicated an obstruction of the appendiceal orifice by a fecalith or lymphoid hyperplasia.² However, this notion does not completely account for variations in incidence observed by age,^3,4 sex,^3,4 ethnic background,^3,4 family history,⁵ temporal–spatial clustering⁶ and seasonality,^3,4 nor does it completely explain the trends in incidence of appendicitis in developed and developing nations.^3,7,8The incidence of appendicitis increased dramatically in industrialized nations in the 19th century and in the early part of the 20th century.¹ Without explanation, it decreased in the middle and latter part of the 20th century.³ The decrease coincided with legislation to improve air quality. For example, after the United States Clean Air Act was passed in 1970,⁹ the incidence of appendicitis decreased by 14.6% from 1970 to 1984.³ Likewise, a 36% drop in incidence was reported in the United Kingdom between 1975 and 1994¹⁰ after legislation was passed in 1956 and 1968 to improve air quality and in the 1970s to control industrial sources of air pollution. Furthermore, appendicitis is less common in developing nations; however, as these countries become more industrialized, the incidence of appendicitis has been increasing.⁷Air pollution is known to be a risk factor for multiple conditions, to exacerbate disease states and to increase all-cause mortality.¹¹ It has a direct effect on pulmonary diseases such as asthma¹¹ and on nonpulmonary diseases including myocardial infarction, stroke and cancer.^11–13 Inflammation induced by exposure to air pollution contributes to some adverse health effects.^14–17 Similar to the effects of air pollution, a proinflammatory response has been associated with appendicitis.^18–20We conducted a case–crossover study involving a population-based cohort of patients admitted to hospital with appendicitis to determine whether short-term increases in concentrations of selected air pollutants were associated with hospital admission because of appendicitis.     

The Severity of Pandemic H1N1 Influenza in the United States,from April to July 2009: A Bayesian Analysis

Background

Accurate measures of the severity of pandemic (H1N1) 2009 influenza (pH1N1) are needed to assess the likely impact of an anticipated resurgence in the autumn in the Northern Hemisphere. Severity has been difficult to measure because jurisdictions with large numbers of deaths and other severe outcomes have had too many cases to assess the total number with confidence. Also, detection of severe cases may be more likely, resulting in overestimation of the severity of an average case. We sought to estimate the probabilities that symptomatic infection would lead to hospitalization, ICU admission, and death by combining data from multiple sources.

Methods and Findings

We used complementary data from two US cities: Milwaukee attempted to identify cases of medically attended infection whether or not they required hospitalization, while New York City focused on the identification of hospitalizations, intensive care admission or mechanical ventilation (hereafter, ICU), and deaths. New York data were used to estimate numerators for ICU and death, and two sources of data—medically attended cases in Milwaukee or self-reported influenza-like illness (ILI) in New York—were used to estimate ratios of symptomatic cases to hospitalizations. Combining these data with estimates of the fraction detected for each level of severity, we estimated the proportion of symptomatic patients who died (symptomatic case-fatality ratio, sCFR), required ICU (sCIR), and required hospitalization (sCHR), overall and by age category. Evidence, prior information, and associated uncertainty were analyzed in a Bayesian evidence synthesis framework. Using medically attended cases and estimates of the proportion of symptomatic cases medically attended, we estimated an sCFR of 0.048% (95% credible interval [CI] 0.026%–0.096%), sCIR of 0.239% (0.134%–0.458%), and sCHR of 1.44% (0.83%–2.64%). Using self-reported ILI, we obtained estimates approximately 7–9× lower. sCFR and sCIR appear to be highest in persons aged 18 y and older, and lowest in children aged 5–17 y. sCHR appears to be lowest in persons aged 5–17; our data were too sparse to allow us to determine the group in which it was the highest.

Conclusions

These estimates suggest that an autumn–winter pandemic wave of pH1N1 with comparable severity per case could lead to a number of deaths in the range from considerably below that associated with seasonal influenza to slightly higher, but with the greatest impact in children aged 0–4 and adults 18–64. These estimates of impact depend on assumptions about total incidence of infection and would be larger if incidence of symptomatic infection were higher or shifted toward adults, if viral virulence increased, or if suboptimal treatment resulted from stress on the health care system; numbers would decrease if the total proportion of the population symptomatically infected were lower than assumed. Please see later in the article for the Editors'' Summary     

Quinolines as a novel structural class of potent and selective PDE4 inhibitors. Optimisation for inhaled administration

Crystallography driven optimisation of a lead derived from similarity searching of the GSK compound collection resulted in the discovery of quinoline-3-carboxamides as highly potent and selective inhibitors of phosphodiesterase 4B. This series has been optimized to GSK256066, a potent PDE4B inhibitor which also inhibits LPS induced production of TNF-α from isolated human peripheral blood mononuclear cells with a pIC₅₀ of 11.1. GSK256066 also has a suitable profile for inhaled dosing.     

The Bacillus subtilis SftA (YtpS) and SpoIIIE DNA translocases play distinct roles in growing cells to ensure faithful chromosome partitioning

In several bacterial species, the faithful completion of chromosome partitioning is known to be promoted by a conserved family of DNA translocases that includes Escherichia coli FtsK and Bacillus subtilis SpoIIIE. FtsK localizes at nascent division sites during every cell cycle and stimulates chromosome decatenation and the resolution of chromosome dimers formed by recA -dependent homologous recombination. In contrast, SpoIIIE localizes at sites where cells have divided and trapped chromosomal DNA in the membrane, which happens during spore development and under some conditions when DNA replication is perturbed. SpoIIIE completes chromosome segregation post-septationally by translocating trapped DNA across the membrane. Unlike E. coli , B. subtilis contains a second uncharacterized FtsK/SpoIIIE-like protein, SftA (formerly YtpS). We report that SftA plays a role similar to FtsK during each cell cycle but cannot substitute for SpoIIIE in rescuing trapped chromosomes. SftA colocalizes with FtsZ at nascent division sites but not with SpoIIIE at sites of chromosome trapping. SftA mutants divide over unsegregated chromosomes more frequently than wild-type unless recA is inactivated, suggesting that SftA, like FtsK, stimulates chromosome dimer resolution. Having two FtsK/SpoIIIE paralogues is not conserved among endospore-forming bacteria, but is highly conserved within several groups of soil- and plant-associated bacteria.     

Intrauterine growth restriction decreases pulmonary alveolar and vessel growth and causes pulmonary artery endothelial cell dysfunction in vitro in fetal sheep

Intrauterine growth restriction (IUGR) increases the risk for bronchopulmonary dysplasia (BPD). Abnormal lung structure has been noted in animal models of IUGR, but whether IUGR adversely impacts fetal pulmonary vascular development and pulmonary artery endothelial cell (PAEC) function is unknown. We hypothesized that IUGR would decrease fetal pulmonary alveolarization, vascular growth, and in vitro PAEC function. Studies were performed in an established model of severe placental insufficiency and IUGR induced by exposing pregnant sheep to elevated temperatures. Alveolarization, quantified by radial alveolar counts, was decreased 20% (P < 0.005) in IUGR fetuses. Pulmonary vessel density was decreased 44% (P < 0.01) in IUGR fetuses. In vitro, insulin increased control PAEC migration, tube formation, and nitric oxide (NO) production. This response was absent in IUGR PAECs. VEGFA stimulated tube formation, and NO production also was absent. In control PAECs, insulin increased cell growth by 68% (P < 0.0001). Cell growth was reduced in IUGR PAECs by 29% at baseline (P < 0.01), and the response to insulin was attenuated (P < 0.005). Despite increased basal and insulin-stimulated Akt phosphorylation in IUGR PAECs, endothelial NO synthase (eNOS) protein expression as well as basal and insulin-stimulated eNOS phosphorylation were decreased in IUGR PAECs. Both VEGFA and VEGFR2 also were decreased in IUGR PAECs. We conclude that fetuses with IUGR are characterized by decreased alveolar and vascular growth and PAEC dysfunction in vitro. This may contribute to the increased risk for adverse respiratory outcomes and BPD in infants with IUGR.     

Vertical ground reaction forces diminish in mice after botulinum toxin injection

We examined changes in weight-bearing ability in mice after injection with botulinum toxin type A (BTX) to determine whether BTX can be used to isolate the effects of muscle on bone. As ambulation patterns were previously shown to improve within two weeks post-injection, we hypothesized that BTX injection to the posterior hindlimb would not significantly affect the mouse's ability to bear weight in the affected limb one week post-injection. Female BALB/c mice (N=13, 16-17 week old) were injected with either 20 μL of BTX (1U/100 g) or saline (SAL) in the left posterior hindlimb. Vertical ground reaction forces (GRF), hindlimb muscle cross-sectional area (MCSA), and tibial bone micro-architecture were assessed for 42 d following injection. Peak and average vertical GRF were 11±1% and 23±3% lower, respectively, in the BTX-injected hindlimb within 4d post-injection and remained lower than the SAL-injected hindlimb 14-21 d post-injection (15±4% and 10±2%, respectively). Time between forelimb and hindlimb peaks was 30-40% greater in the BTX-injected hindlimb than SAL-injected hindlimb 4-14 d post-injection. Peak vertical GRF recovered earlier following BTX injection than MCSA or bone volume fraction. These results indicate that weight-bearing ability recovered despite persistent muscle atrophy, and that weight-bearing alone was insufficient to maintain bone in the absence of muscle activity. We suggest that the absence of high-frequency signals typically associated with fast-twitch muscle activity may be contributing to the ongoing degradation of bone after BTX injection.     

Multiplex PCR assay for the detection and quantification of Campylobacter spp., Escherichia coli O157:H7, and Salmonella serotypes in water samples

Three pathogens, Campylobacter, Salmonella, and Shiga-toxin-producing Escherichia coli, are leading causes of bacterial gastroenteritis in the United States and worldwide. Although these three bacteria are typically considered food-borne pathogens, outbreaks have been reported due to contaminated drinking water and irrigation water. The aim of this research was to develop two types of PCR assays that could detect and quantify three pathogens, Campylobacter spp., E. coli O157:H7, and Salmonella spp., in watershed samples. In conventional PCR, three target strains were detected by multiplex PCR (m-PCR) using each specific primer pair simultaneously. Under optimized m-PCR conditions, the assay produced a 90-bp product for Campylobacter jejuni, a 150-bp product for E. coli O157:H7, and a 262-bp product for Salmonella Typhimurium, and the limitation of detection was approximately 700 copies for all three bacteria. In addition, real-time PCR was performed to quantify the three pathogens using SYBR green fluorescence. The assay was designed so that each target had a different melting temperature [C. jejuni (80.1 °C), E. coli O157:H7 (83.3 °C), and S. Typhimurium (85.9 °C)]. Therefore, this system could quantify and distinguish three pathogens simultaneously in a single reaction.     

Prolactin-mediated regulation of lipid biosynthesis genes in vivo in the lactating mammary epithelial cell

Prolactin (PRL) is known to play an essential role in mammary alveolar proliferation in the pregnant mouse, but its role in lactation has been more difficult to define. Genetic manipulations that alter expression of the PRL receptor and its downstream signaling molecules resulted in developmental defects that may directly or indirectly impact secretory activation and lactation. To examine the in vivo role of PRL specifically in lactation, bromocriptine (BrCr) was administered every 8 h to lactating mice on the second day postpartum, resulting in an ~95% decrease in serum PRL levels. Although morphological changes in secretory alveoli were slight, by 8 h of BrCr, pup growth was inhibited significantly. Phosphorylated STAT5 fell to undetectable levels within 4 h. Decreased milk protein gene expression, β-casein, and α-lactalbumin, was observed after 8 h of treatment. To assess mammary-specific effects on lipid synthesis genes, we isolated mammary epithelial cells (MECs) depleted of mammary adipocytes. Expression of genes involved in glucose uptake, glycolysis, pentose phosphate shunt, de novo synthesis of fatty acids, and biosynthesis of triacylglycerides was decreased up to 19-fold in MECs by just 8 h of BrCr treatment. Glands from BrCr-treated mice showed a twofold reduction in intracellular cytoplasmic lipid droplets and a reduction in cytosolic β-casein. These data demonstrate that PRL signaling regulates MEC-specific lipogenic gene expression and that PRL signals coordinate the milk synthesis and mammary epithelial cell survival during lactation in the mouse.     

FXYD proteins stabilize Na,K-ATPase: amplification of specific phosphatidylserine-protein interactions

FXYD proteins are a family of seven small regulatory proteins, expressed in a tissue-specific manner, that associate with Na,K-ATPase as subsidiary subunits and modulate kinetic properties. This study describes an additional property of FXYD proteins as stabilizers of Na,K-ATPase. FXYD1 (phospholemman), FXYD2 (γ subunit), and FXYD4 (CHIF) have been expressed in Escherichia coli and purified. These FXYD proteins associate spontaneously in vitro with detergent-soluble purified recombinant human Na,K-ATPase (α1β1) to form α1β1FXYD complexes. Compared with the control (α1β1), all three FXYD proteins strongly protect Na,K-ATPase activity against inactivation by heating or excess detergent (C₁₂E₈), with effectiveness FXYD1 > FXYD2 ≥ FXYD4. Heating also inactivates E₁ ↔ E₂ conformational changes and cation occlusion, and FXYD1 protects strongly. Incubation of α1β1 or α1β1FXYD complexes with guanidinium chloride (up to 6 m) causes protein unfolding, detected by changes in protein fluorescence, but FXYD proteins do not protect. Thus, general protein denaturation is not the cause of thermally mediated or detergent-mediated inactivation. By contrast, the experiments show that displacement of specifically bound phosphatidylserine is the primary cause of thermally mediated or detergent-mediated inactivation, and FXYD proteins stabilize phosphatidylserine-Na,K-ATPase interactions. Phosphatidylserine probably binds near trans-membrane segments M9 of the α subunit and the FXYD protein, which are in proximity. FXYD1, FXYD2, and FXYD4 co-expressed in HeLa cells with rat α1 protect strongly against thermal inactivation. Stabilization of Na,K-ATPase by three FXYD proteins in a mammalian cell membrane, as well the purified recombinant Na,K-ATPase, suggests that stabilization is a general property of FXYD proteins, consistent with a significant biological function.