2,092 research outputs found

    Defining the critical limit of oxygen extraction in the human small intestine

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    AbstractAlthough animal models have been used to characterize the relation between oxygen consumption and blood flow, reliable data have not been generated in the human small intestine. We perfused segments of human small intestine by using an ex vivo perfusion circuit that allowed precise manipulation of blood flow and perfusion pressure. Our goal was to define the critical level of intestinal blood flow necessary to maintain the metabolic needs of the tissue. Human small intestine (n = 5) tissue obtained at transplantation harvest was transported on ice to the laboratory. A 40-cm mid-jejunal segment was selected for perfusion, and appropriate inflow and outflow vessels were identified and cannulated. Perfusion with an autologous blood solution was initiated through an extracorporeal membrane oxygenation circuit. After a 30-minute equilibration period, arterial and venous blood gases were measured at varying flow rates while maintaining a constant hematocrit level. Arterial and venous oxygen content, arteriovenous oxygen difference (A-VO2 diff), and oxygen consumption (O 2 ) were then calculated. Our results demonstrated that at blood flows >30 ml/min/100 g, O 2 is independent of blood flow (1.6 ± 0.06 ml/min/100 g), and oxygen extraction is inversely related to flow. Below this blood flow rate of 30 ml/min/100 g, oxygen extraction does not increase further (6.3 ± 0.3 vol%), and O 2 becomes flow dependent. This ex vivo preparation defines for the first time a threshold value of blood flow for small intestine below which oxygen consumption decreases (30 ml/min/100 g). Previous animal studies have correlated such a decrease in oxygen consumption with functional and histologic evidence of tissue injury. This “critical” flow rate in human intestine is similar to that found previously in canine and feline intestine, but lower than that of rodent species. (J Vasc Surg 1996;23:832-8.

    Knowledge and Attitudes of Guam Residents Towards Cancer Clinical Trial Participation

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    Purpose/Background: Currently there are no cancer clinical trials conducted in Guam, but interest is growing. Limited information exists on the knowledge and attitudes of Guam’s population towards cancer clinical research, yet cancer is the second highest cause of death in Guam and among the CHamoru people, Guam’s indigenous population. CHamoru people suffer the highest rates of cancer mortality compared to other ethnic groups in Guam. The purpose of this study was to determine differences in knowledge and attitudes towards cancer clinical trials participation, and attitudes towards traditional medicine. Materials & Methods: A telephone survey instrument was designed, pilot-tested, IRB-approved, and implemented using a third-party marketing company. Questions were adapted from existing surveys and new questions were developed to address unique, Guam-specific interests. Recruited subjects were Guam residents adults 18 years of age and older with telephone service. Guam residents were called from October 6 to 10, 2018 to assess levels of knowledge and attitudes towards cancer clinical trials and the attitudes towards using traditional medicine to treat cancer. Descriptive statistics were computed for demographic variables by response category. Univariate logistic regression was conducted to investigate the bivariate association between a survey question and demographic variables. Odds ratios (ORs) and associated 95% confidence intervals (CIs) were calculated. Multivariable logistic regression model was developed for each question, adjusting for important covariates. Hosmer-Lemeshow tests and c-statistics were used to evaluate goodness of fit. Results: The survey respondents’ (n=152) demographic data closely reflected the US Census ethnicity data for Guam: CHamoru (47.0%), Filipino (26.5%), Caucasian (11.3%) and Other (15.2%). Fifty-three percent understood the term “clinical trial”; 73.7% would be willing to participate if they had cancer, and 59.9% believed they would receive good quality treatment from a clinical trial offered in Guam. Approximately 56.0% thought they would have to pay out-of-pocket expenses; and 67.0% disagreed or were not sure that clinical trial sponsors pay for the study drug while other costs are billed to the insurance company. Physician ethnicity was not important to 100% of Caucasians, but was important to at least 30.0% of non-Caucasians; family support was very important to 94.7% of respondents, while religious community support was important to 55.4%. Approximately 65.1% did not believe that people participating in clinical trials were treated like ‘guinea pigs’. Having college education (OR = 3.26; 95% CI: 1.53 – 6.98) and knowing English language well (OR=5.86; 95% CI: 1.21 – 28.38) were significantly associated with higher aggregated knowledge about clinical trials. Although the majority (67.2%) would seek traditional healing practices if diagnosed with cancer, most (84.9%) did not think a suruhano (CHamoru traditional healer) could treat cancer, and 94.7% did not believe cancer was caused by taotaomo’na (ancient spirits). Discussion/Conclusion: Knowledge and attitudes towards cancer clinical trials and the use of traditional medicine to treat cancer were significantly associated with key demographic variables including ethnicity, income, employment status, place of birth and insurance type. Knowledge about cancer clinical trials was as expected: more participants who are Caucasian, have a higher level of education, were born in U.S., are employed, have a higher income, private insurance, self-report that they speak English well, and do not follow religion, were more aware of what a clinical trial is than the other respondents. Though knowledge about cancer clinical trials is limited, attitudes towards participation in cancer clinical trials offered in Guam were largely positive

    Altered patterns of gene duplication and differential gene gain and loss in fungal pathogens

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    <p>Abstract</p> <p>Background</p> <p>Duplication, followed by fixation or random loss of novel genes, contributes to genome evolution. Particular outcomes of duplication events are possibly associated with pathogenic life histories in fungi. To date, differential gene gain and loss have not been studied at genomic scales in fungal pathogens, despite this phenomenon's known importance in virulence in bacteria and viruses.</p> <p>Results</p> <p>To determine if patterns of gene duplication differed between pathogens and non-pathogens, we identified gene families across nine euascomycete and two basidiomycete species. Gene family size distributions were fit to power laws to compare gene duplication trends in pathogens <it>versus </it>non-pathogens. Fungal phytopathogens showed globally altered patterns of gene duplication, as indicated by differences in gene family size distribution. We also identified sixteen examples of gene family expansion and five instances of gene family contraction in pathogenic lineages. Expanded gene families included those predicted to be important in melanin biosynthesis, host cell wall degradation and transport functions. Contracted families included those encoding genes involved in toxin production, genes with oxidoreductase activity, as well as subunits of the vacuolar ATPase complex. Surveys of the functional distribution of gene duplicates indicated that pathogens show enrichment for gene duplicates associated with receptor and hydrolase activities, while euascomycete pathogens appeared to have not only these differences, but also significantly more duplicates associated with regulatory and carbohydrate binding functions.</p> <p>Conclusion</p> <p>Differences in the overall levels of gene duplication in phytopathogenic species <it>versus </it>non-pathogenic relatives implicate gene inventory flux as an important virulence-associated process in fungi. We hypothesize that the observed patterns of gene duplicate enrichment, gene family expansion and contraction reflect adaptation within pathogenic life histories. These adaptations were likely shaped by ancient, as well as contemporary, intimate associations with monocot hosts.</p

    Quantification of Progesterone and 17-β Estradiol in Mouse Serum by Liquid Chromatography-Tandem Mass Spectrometry

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    Quantification of progesterone and 17-β estradiol in mouse serum by liquid chromatography-tandem mass spectrometry Authors: Benjamin Kennard, Allison Cobble, Amy Gravitte, Keleigh Galloway, Jen Kintner, Jennifer Hall, Stacy Brown Introduction: In the United States, Chlamydia trachomatis is a commonly appearing sexually transmitted infection1. It affects the U.S. healthcare system to a tune of about $500 million dollars annually2. In women, it generally appears asymptomatic and can lead to severe secondary complications such as pelvic inflammatory diseases or infertility1. Female sex hormones, estrogen and progesterone, are being identified to have a role in chlamydial infection. Specifically, this study aims to create quantification methods to detect levels of estrogen and progesterone in mice, infected with Chlamydia muridarum, plasma samples. Methods: Progesterone samples were prepared using solid-liquid extraction (SLE+) cartridges with ethyl acetate as the elution solvent. Estradiol samples were prepared using liquid-liquid extraction (LLE) with methyl tert-butyl ether and subsequent derivatization with DMIS. Following sample preparation, hormones were quantified in samples using LC-MS/MS with a gradient elution of 1 mM ammonium fluoride in water and acetonitrile. The separation was achieved using a UCT C18 column (100 x 21.mm, 1.8 μm particle size) maintained at 50oC. The mass spectrometer was set up to isolate molecular ions for progesterone (m/z 315.0910) and derivatized estradiol (m/z 431.1835). Quantification was facilitated by the use of deuterium-labeled internal standards and their corresponding molecular ions in the mass spectrometer (d9-progesterone; m/z 324.1230 and d5-estradiol; m/z 436.2922). Results: Several aspects of the assay presented have been optimized for maximum analyte recovery and analytical sensitivity, including column choice, mobile phase, derivatizing agents for estradiol, and extraction protocols for progesterone. The LC-MS/MS method was investigated for precision and accuracy over three separate days. The dynamic range of the progesterone assay was 5 – 100 ng/mL, with a limit of detection of 1 ng/mL. Likewise, the estradiol assay was linear in the range of 5 – 100 ng/mL, with a limit of detection of 0.5 ng/mL. The average precision, represented by % RSD was 0.74 – 8.5% and 6.3 – 13.4% for progesterone and estradiol, respectively. The accuracy of the method, represented by % error was 1.6 – 14.4% and 4.0 – 10.5% for progesterone and estradiol, respectively. Successful validation was defined as \u3c 15% RSD and error (\u3c 20% at the limit of quantification), per current FDA Guidelines. Conclusions: The developed LC-MS/MS method is specific for progesterone and estradiol, and the extraction is suitable for preparation of mouse serum samples. This assay could be successfully applied to hormone quantification in mouse samples to support the investigation of the link between chlamydia infection and hormone levels in female animals. References 1. Chlamydia - 2017 Sexually Transmitted Diseases Surveillance. https://www.cdc.gov/std/stats17/chlamydia.htm. Accessed October 23, 2018. 2. Owusu-Edusei K, Chesson HW, Gift TL, et al. The Estimated Direct Medical Cost of Selected Sexually Transmitted Infections in the United States, 2008. Sex Transm Dis. 2013;40(3):197-201. doi:10.1097/OLQ.0b013e318285c6d

    Fine particle pH and the partitioning of nitric acid during winter in the northeastern United States

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    Particle pH is a critical but poorly constrained quantity that affects many aerosol processes and properties, including aerosol composition, concentrations, and toxicity. We assess PM1 pH as a function of geographical location and altitude, focusing on the northeastern U.S., based on aircraft measurements from the Wintertime Investigation of Transport, Emissions, and Reactivity campaign (1 February to 15 March 2015). Particle pH and water were predicted with the ISORROPIA-II thermodynamic model and validated by comparing predicted to observed partitioning of inorganic nitrate between the gas and particle phases. Good agreement was found for relative humidity (RH) above 40%; at lower RH observed particle nitrate was higher than predicted, possibly due to organic-inorganic phase separations or nitrate measurement uncertainties associated with low concentrations (nitrate \u3c 1 µg m−3). Including refractory ions in the pH calculations did not improve model predictions, suggesting they were externally mixed with PM1 sulfate, nitrate, and ammonium. Sample line volatilization artifacts were found to be minimal. Overall, particle pH for altitudes up to 5000 m ranged between −0.51 and 1.9 (10th and 90th percentiles) with a study mean of 0.77 ± 0.96, similar to those reported for the southeastern U.S. and eastern Mediterranean. This expansive aircraft data set is used to investigate causes in variability in pH and pH-dependent aerosol components, such as PM1 nitrate, over a wide range of temperatures (−21 to 19°C), RH (20 to 95%), inorganic gas, and particle concentrations and also provides further evidence that particles with low pH are ubiquitous

    People with long-term conditions sharing personal health data via digital health technologies:a scoping review to inform design

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    The use of digital technology amongst people living with a range of long-term health conditions to support self-management has increased dramatically. More recently, digital health technologies to share and exchange personal health data with others have been investigated. Sharing personal health data with others is not without its risks: sharing data creates threats to the privacy and security of personal data and plays a role in trust, adoption and continued use of digital health technology. Our work aims to inform the design of these digital health technologies by investigating the reported intentions of sharing health data with others, the associated user experiences when using these digital health technologies and the trust, identity, privacy and security (TIPS) considerations for designing digital health technologies that support the trusted sharing of personal health data to support the self-management of long-term health conditions. To address these aims, we conducted a scoping review, analysing over 12,000 papers in the area of digital health technologies. We conducted a reflexive thematic analysis of 17 papers that described digital health technologies that support sharing of personal health data, and extracted design implications that could enhance the future development of trusted, private and secure digital health technologies.</p

    Decreased microbial co-occurrence network stability and SCFA receptor level correlates with obesity in African-origin women.

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    We compared the gut microbial populations in 100 women, from rural Ghana and urban US [50% lean (BMI &lt; 25 kg/m2) and 50% obese (BMI ≥ 30 kg/m2)] to examine the ecological co-occurrence network topology of the gut microbiota as well as the relationship of short chain fatty acids (SCFAs) with obesity. Ghanaians consumed significantly more dietary fiber, had greater microbial alpha-diversity, different beta-diversity, and had a greater concentration of total fecal SCFAs (p-value &lt; 0.002). Lean Ghanaians had significantly greater network density, connectivity and stability than either obese Ghanaians, or lean and obese US participants (false discovery rate (FDR) corrected p-value ≤ 0.01). Bacteroides uniformis was significantly more abundant in lean women, irrespective of country (FDR corrected p &lt; 0.001), while lean Ghanaians had a significantly greater proportion of Ruminococcus callidus, Prevotella copri, and Escherichia coli, and smaller proportions of Lachnospiraceae, Bacteroides and Parabacteroides. Lean Ghanaians had a significantly greater abundance of predicted microbial genes that catalyzed the production of butyric acid via the fermentation of pyruvate or branched amino-acids, while obese Ghanaians and US women (irrespective of BMI) had a significantly greater abundance of predicted microbial genes that encoded for enzymes associated with the fermentation of amino-acids such as alanine, aspartate, lysine and glutamate. Similar to lean Ghanaian women, mice humanized with stool from the lean Ghanaian participant had a significantly lower abundance of family Lachnospiraceae and genus Bacteroides and Parabacteroides, and were resistant to obesity following 6-weeks of high fat feeding (p-value &lt; 0.01). Obesity-resistant mice also showed increased intestinal transcriptional expression of the free fatty acid (Ffa) receptor Ffa2, in spite of similar fecal SCFAs concentrations. We demonstrate that the association between obesity resistance and increased predicted ecological connectivity and stability of the lean Ghanaian microbiota, as well as increased local SCFA receptor level, provides evidence of the importance of robust gut ecologic network in obesity

    Adolescent Experiences with Self-Asphyxial Behaviors and Problematic Drinking in Emerging Adulthood

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    Self-asphyxial behavior to achieve a euphoric high (The Choking Game; TCG), occurs most often during early adolescence. Participants in TCG often engage in other risky behaviors. This study investigated the relationship between prior experience with TCG and problematic drinking behaviors in emerging adulthood. Emerging adults, 18 to 25 years old (N = 1248), 56% female, and 78% Caucasian completed an online survey regarding knowledge of and prior engagement in TCG and current drinking behaviors. Participants who personally engaged in TCG during childhood/adolescence or were familiar with TCG reported significantly more problematic drinking behaviors during emerging adulthood. Those present when others engaged in TCG but resisted participation themselves reported significantly less current problematic drinking behaviors than those who participated, but significantly more current problematic drinking behaviors than those never present. Emerging adults with increased social familiarity with TCG during adolescence endorsed greater problematic drinking behaviors. Results suggest resistance skills may generalize across time/activities
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