Ensuring quality in 17OHP mass spectrometry measurement:an international study assessing isomeric steroid interference

Objectives: Interference from isomeric steroids is a potential cause of disparity between mass spectrometry-based 17-hydroxyprogesterone (17OHP) results. We aimed to assess the proficiency of mass spectrometry laboratories to report 17OHP in the presence of known isomeric steroids. Methods:A series of five samples were prepared using a previously demonstrated commutable approach. These samples included a control (spiked to 15.0 nmol/L 17OHP) and four challenge samples further enriched with equimolar concentrations of 17OHP isomers (11α-hydroxyprogesterone, 11β-hydroxyprogesterone, 16α-hydroxyprogesterone or 21-hydroxyprogesterone). These samples were distributed to 38 participating laboratories that reported serum 17OHP results using mass spectrometry in two external quality assurance programs. The result for each challenge sample was compared to the control sample submitted by each participant. Results: Twenty-six laboratories (68 % of distribution) across three continents returned results. Twenty-five laboratories used liquid chromatography-tandem mass spectrometry (LC-MS/MS), and one used gas chromatography-tandem mass spectrometry to measure 17OHP. The all-method median of the control sample was 14.3 nmol/L, ranging from 12.4 to 17.6 nmol/L. One laboratory had results that approached the lower limit of tolerance (minus 17.7 % of the control sample), suggesting the isomeric steroid caused an irregular result. Conclusions: Most participating laboratories demonstrated their ability to reliably measure 17OHP in the presence of the four clinically relevant isomeric steroids. The performance of the 12 (32 %) laboratories that did not engage in this activity remains unclear. We recommend that all laboratories offering LC-MS/MS analysis of 17OHP in serum, plasma, or dried bloodspots determine that the isomeric steroids are appropriately separated.</p

Ensuring quality in 17OHP mass spectrometry measurement:an international study assessing isomeric steroid interference

Objectives: Interference from isomeric steroids is a potential cause of disparity between mass spectrometry-based 17-hydroxyprogesterone (17OHP) results. We aimed to assess the proficiency of mass spectrometry laboratories to report 17OHP in the presence of known isomeric steroids. Methods:A series of five samples were prepared using a previously demonstrated commutable approach. These samples included a control (spiked to 15.0 nmol/L 17OHP) and four challenge samples further enriched with equimolar concentrations of 17OHP isomers (11α-hydroxyprogesterone, 11β-hydroxyprogesterone, 16α-hydroxyprogesterone or 21-hydroxyprogesterone). These samples were distributed to 38 participating laboratories that reported serum 17OHP results using mass spectrometry in two external quality assurance programs. The result for each challenge sample was compared to the control sample submitted by each participant. Results: Twenty-six laboratories (68 % of distribution) across three continents returned results. Twenty-five laboratories used liquid chromatography-tandem mass spectrometry (LC-MS/MS), and one used gas chromatography-tandem mass spectrometry to measure 17OHP. The all-method median of the control sample was 14.3 nmol/L, ranging from 12.4 to 17.6 nmol/L. One laboratory had results that approached the lower limit of tolerance (minus 17.7 % of the control sample), suggesting the isomeric steroid caused an irregular result. Conclusions: Most participating laboratories demonstrated their ability to reliably measure 17OHP in the presence of the four clinically relevant isomeric steroids. The performance of the 12 (32 %) laboratories that did not engage in this activity remains unclear. We recommend that all laboratories offering LC-MS/MS analysis of 17OHP in serum, plasma, or dried bloodspots determine that the isomeric steroids are appropriately separated.</p

Pathway aberrations of murine melanoma cells observed in Paired-End diTag transcriptomes

<p>Abstract</p> <p>Background</p> <p>Melanoma is the major cause of skin cancer deaths and melanoma incidence doubles every 10 to 20 years. However, little is known about melanoma pathway aberrations. Here we applied the robust Gene Identification Signature Paired End diTag (GIS-PET) approach to investigate the melanoma transcriptome and characterize the global pathway aberrations.</p> <p>Methods</p> <p>GIS-PET technology directly links 5' mRNA signatures with their corresponding 3' signatures to generate, and then concatenate, PETs for efficient sequencing. We annotated PETs to pathways of KEGG database and compared the murine B16F1 melanoma transcriptome with three non-melanoma murine transcriptomes (Melan-a2 melanocytes, E14 embryonic stem cells, and E17.5 embryo). Gene expression levels as represented by PET counts were compared across melanoma and melanocyte libraries to identify the most significantly altered pathways and investigate the expression levels of crucial cancer genes.</p> <p>Results</p> <p>Melanin biosynthesis genes were solely expressed in the cells of melanocytic origin, indicating the feasibility of using the PET approach for transcriptome comparison. The most significantly altered pathways were metabolic pathways, including upregulated pathways: purine metabolism, aminophosphonate metabolism, tyrosine metabolism, selenoamino acid metabolism, galactose utilization, nitrobenzene degradation, and bisphenol A degradation; and downregulated pathways: oxidative phosphorylation, ATPase synthesis, TCA cycle, pyruvate metabolism, and glutathione metabolism. The downregulated pathways concurrently indicated a slowdown of mitochondrial activities. Mitochondrial permeability was also significantly altered, as indicated by transcriptional activation of ATP/ADP, citrate/malate, Mg⁺⁺, fatty acid and amino acid transporters, and transcriptional repression of zinc and metal ion transporters. Upregulation of cell cycle progression, MAPK, and PI3K/Akt pathways were more limited to certain region(s) of the pathway. Expression levels of c-<it>Myc </it>and <it>Trp53 </it>were also higher in melanoma. Moreover, transcriptional variants resulted from alternative transcription start sites or alternative polyadenylation sites were found in <it>Ras </it>and genes encoding adhesion or cytoskeleton proteins such as integrin, β-catenin, α-catenin, and actin.</p> <p>Conclusion</p> <p>The highly correlated results unmistakably point to a systematic downregulation of mitochondrial activities, which we hypothesize aims to downgrade the mitochondria-mediated apoptosis and the dependency of cancer cells on angiogenesis. Our results also demonstrate the advantage of using the PET approach in conjunction with KEGG database for systematic pathway analysis.</p

Health tourism on the rise? Evidence from the balance of payments statistics

The study assesses the presence and magnitude of global trends in health tourism using health-related travel (HRT) spending reported in the International Monetary Fund\u27s Balance of Payments Statistics database. Linear regression and quantile regression are applied to estimate secular trends of the import and export of HRT based on a sample of countries from 2003 to 2009. The results show that from 2003 to 2009 the import and export of health tourism rose among countries with a high volume of such activities (accounting for the upper 40 % of the countries), but not among those with a low volume. The uneven growth in health tourism has generated greater contrast between countries with high and low volumes of health tourism activities. However, the growth in the total import of health tourism did not outpace the population growth, implying that in general the population\u27s tendency to engage in health tourism remained static. © 2013 Springer-Verlag

Trends and structural shifts in health tourism: Evidence from seasonal time-series data on health-related travel spending by Canada during 1970-2010

There has been a growing interest in better understanding the trends and determinants of health tourism activities. While much of the expanding literature on health tourism offers theoretical or qualitative discussion, empirical evidences has been lacking. This study employs Canada\u27s outbound health tourism activities as an example to examine the trends in health tourism and its association with changing domestic health care market characteristics. A time-series model that accounts for potential structural changes in the trend is employed to analyze the quarterly health-related travel spending series reported in the Balance of Payments Statistics (BOPS) during 1970-2010 (n=156). We identified a structural shift point which marks the start of an accelerated growth of health tourism and a flattened seasonality in such activities. We found that the health tourism activities of Canadian consumers increase when the private investment in medical facilities declines or when the private MPI increases during the years following the structural-change. We discussed the possible linkage of the structural shift to the General Agreement on Trade in Services (GATS), which went into effect in January, 1995

Time Usage by College Students: Knowledge Acquisition, Degree Value, Work, Sleep and Fun

Modern professors often lament at least the perception of declining amounts of time that today’s college students allocate to knowledge acquisition relative to students from earlier eras. Employing a recently commissioned, 1,000+ response data set this paper investigates the hours allocated to learning and numerous other activities for students who attended college from the 1960s through those still in college, to investigate time usage over seven distinct time frames. The focus is on how time allocations have differed and potential justifications for those differences. The results reflect how time allocations have changed over the generations

Peer effects in adolescent bodyweight: Evidence from rural China

Peer effect is a potential determinant of individual weight gain that has drawn considerable attention recently. The presence of peer effect implies that policies targeted at changing bodyweight can have enhanced effectiveness through a multiplier effect. This study aims to measure the peer effects on adolescent bodyweight in China. Using the small community nature of the rural sample of the wave 2000 of the China Health and Nutrition Survey, we define plausible peer groups and assess the effect of the average BMI of his/her peer group on the BMI of an adolescent. An instrumental variable (IV) approach is applied to control for potential endogeneity of the peer group\u27s BMI. We find evidence supporting peer effect on BMI in general. The peer effect is around 0.3 with slight variation between two alternative peer definitions. Split sample analysis shows that the peer effect is significant for females (0.32-0.37), and insignificant for male adolescents. Furthermore, we find strong influence of same-gender peers (0.34-0.42) for female adolescents. Conditional quantile regressions show that the peer effect in weight gain is mainly present at or below the median in the conditional BMI distribution for girls, and at the higher end of the BMI distribution for boys. Multiple tests show strong identification, and strong instruments in our IV estimation. Placebo tests suggest that our results are reasonably robust to the correlated effect, due to unobserved community- and province-level factors. © 2013 Elsevier Ltd

Proposed reform of the H-1B programme under Trump administration and the adverse selection in Green Card applications

The dialogue of major reform in immigration laws along with increase in rejection of H-1B petitioners since the start of the Trump administration may make employers find H-1B renewal becoming more difficult and costly for low-end positions and less-educated employees. Using the Program Electronic Review Management (PERM) application data, this article examines the impact of the recent threat of immigration reform on the share of entry-level positions and petitioners with no college degree in Green Card applications. We found evidence that entry-level positions and applicants without a college degree became more heavily represented among new PERM applications after 2016, even when a trend and occupations were accounted for. The findings are consistent with the hypothesis that employers face stronger incentive to retain workers and sponsor their PERM applications since H-1B renewal will likely become more difficult and costly for low-end positions and less-educated workers

International accreditation, linguistic proximity and trade in medical services

The recent growth in the globalization of medical services has attracted broad attention from scholars and policymakers. The intimacy and risk associated with many medical services makes these markets especially sensitive to trade barriers, transaction costs and asymmetric information. This paper uses a gravity model to investigate the factors associated with the global pattern of bilateral trade in medical services. Using data from the United Nations International Trade in Services Database, we differentiate between trade flows in which the recipient travels to the service provider, ‘medical tourism,’ and those trade flows in which the service is delivered to the recipient, ‘other health services.’ Our findings indicate that, after controlling for various economic, historical and geographic linkages, linguistic proximity and international accreditation are not significant predictors of the bilateral pattern of medical tourism, though they are associated with greater trade in other health services. We argue the key difference is that trade in other health services, including medical transcription, diagnostic analysis and laboratory services, is akin to trade in intermediate inputs. The medical service providers contracting for these services are especially sensitive to risk and have strong incentives to monitor quality. By contrast, medical tourism is a market in which patients do not have strong incentives to engage in costly monitoring or information gathering. Providers seeking to market their services to patients abroad have mitigated the effects of linguistic dissimilarity and asymmetric information by exploiting the strong complementarities between medical and non-medical tourism services