Analytical variation concerning total 25-hydroxyvitamin D measurement, where are we now? A DEQAS review of current assay performance

The Vitamin D External Quality Assessment Scheme (DEQAS) distributes serum samples globally, on a quarterly basis, to assess participants' performance of specific methods for 25-hydroxyvitamin D (25OHD) and other vitamin D metabolites. In this review an assessment of the state of the art in the performance of 25OHD methods is presented. This assessment is based on an analysis of data submitted by scheme participants for the 2021/22 distribution cycle, which comprised of four distributions each containing five DEQAS samples. These distributions enabled the assessment of performance across a wide concentration range and included samples containing endogenous 25OHD₂. Overall analytical performance continues to improve, but there is still significant method variation and bias in some automated methods. These automated methods continue to be challenged in measuring 25OHD at the extremes of the measuring range and in the presence of 25OHD₂. LC-MS/MS methods still show superior performance with regards to bias, but are out-performed by some automated methods in terms of assay variability. Through participating in an accuracy based EQA scheme, such as DEQAS, laboratories are able to assess the accuracy of their methods in comparison to a gold standard reference measurement procedure. It is crucial for all laboratories to be aware of the performance and limitations of their 25OHD assays and to educate their users accordingly in order to ensure reliable assessment of vitamin D status.

Transient dystonia correlates with parkinsonism after 1-methyl-4-phenyl-1,2,3,6- tetrahydropyridine in nonhuman primates

Unilateral internal carotid artery 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) infusion in non-human primates produces transient contralateral hemi-dystonia followed by stable contralateral hemi-parkinsonism; the relationship between dystonia and parkinsonism remains unclear. We hypothesized that transient dystonia severity following MPTP correlates with parkinsonism severity. In male Macaca nemestrina (n = 3) and M. fascicularis (n = 17) we administered unilateral intra-carotid MPTP, then correlated validated blinded ratings of transient peak dystonia and delayed parkinsonism. We also correlated dystonia severity with post-mortem measures of residual striatal dopamine and nigral neuron counts obtained a mean 53 ± 15 days following MPTP, after resolution of dystonia but during stable parkinsonism. Median latency to dystonia onset was 1 day, and peak severity 2.5 days after MPTP; total dystonia duration was 13.5 days. Parkinsonism peaked a median of 19.5 days after MPTP, remaining nearly constant thereafter. Peak dystonia severity highly correlated with parkinsonism severity (r[18] = 0.82, p < 0.001). Residual cell counts in lesioned nigra correlated linearly with peak dystonia scores (r[18] = -0.68, p=<0.001). Dystonia was not observed in monkeys without striatal dopamine depletion (n = 2); dystonia severity correlated with striatal dopamine depletion when residual nigral cell loss was less than 50% ([11] r = -0.83, p < 0.001) but spanned a broad range with near complete striatal dopamine depletion, when nigral cell loss was greater than 50%. Our data indicate that residual striatal dopamine may not reflect dystonia severity. We speculate on mechanisms of transient dystonia followed by parkinsonism that may be studied using this particular NHP MPTP model to better understand relationships of transient dystonia to nigrostriatal injury and parkinsonism.

Salt supplementation in the management of orthostatic intolerance: Vasovagal syncope and postural orthostatic tachycardia syndrome

Salt supplementation is a common non-pharmacological approach to the management of recurrent orthostatic syncope or presyncope, particularly for patients with vasovagal syncope (VVS) or postural orthostatic tachycardia syndrome (POTS), although there is limited consensus on the optimal dosage, formulation and duration of treatment. Accordingly, we reviewed the evidence for the use of salt supplementation to reduce susceptibility to syncope or presyncope in patients with VVS and POTS. We found that short-term (~3 months) salt supplementation improves susceptibility to VVS and associated symptoms, with little effect on supine blood pressure. In patients with VVS, salt supplementation is associated with increases in plasma volume, and an increase in the time taken to provoke a syncopal event during orthostatic tolerance testing, with smaller orthostatic heart rate increases, enhanced peripheral vascular responses to orthostatic stress, and improved cerebral autoregulation. Responses were most pronounced in those with a baseline sodium excretion <170 mmol/day. Salt supplementation also improved symptoms, plasma volume, and orthostatic responses in patients with POTS. Salt supplementation should be considered for individuals with recurrent and troublesome episodes of VVS or POTS without cardiovascular comorbidities, particularly if their typical urinary sodium excretion is low, and their supine blood pressure is not elevated. The efficacy of the response, in terms of the improvement in subjective and objective markers of orthostatic intolerance, and any potential deleterious effect on supine blood pressure, should be routinely monitored in individuals on high salt regimes.

A data-driven approach for the detection of internal standard outliers in targeted LC-MS/MS assays

•

Identifying internal standard outliers in clinical mass spectrometry assays is imperative.

•

Current approaches for identifying outliers are arbitrary and do not account for assay drift.

•

A robust modelling strategy allows laboratories to define their own acceptance criteria from their own data.

•

This strategy is easily implemented and the code is freely available.

Heavy-labelled internal standard (IS) compounds are commonly used in liquid chromatography-tandem mass spectrometry (LC-MS/MS) assays to control for stochastic and systematic variation. Identifying samples that suffer from unwanted variation is critically important in order to avoid factitiously inaccurate results. Current approaches for outlier detection typically employ arbitrary thresholds and ignore systematic drift. To improve this, we applied robust linear mixed-effects models (LMMs) to capture the within- and between-run variability in IS signal and generate data-driven acceptance ranges for routine use.

Data from in-house LC-MS/MS assays for 25-hydroxyvitamin D₃ and D₂ and prednisolone were retrospectively collected. The variation in the percentage deviation of the internal standard area from the mean of the calibrators was modelled through the use of robust LMMs. The fitted LMMs revealed significant positive drift in IS signal over the analytical runs for vitamin D, with slope coefficients of 0.118 (95% CI: 0.098, 0.138) and 0.192 (0.168, 0.215) for D₃ and D₂, respectively. In contrast, the models for prednisolone demonstrated a significant negative drift in IS signal, with a slope coefficient of −0.164 (−0.297, −0.036). Non-parametric, cluster bootstrap resampling enabled us to define acceptance ranges for use in future assays.

Here, we have described a computational approach to extensively characterise the variation in IS signal in routinely-performed LC-MS/MS assays. This approach facilitates a robust quality assessment of IS outliers in routine practice and thus has the potential to improve patient safety. Importantly, this approach is applicable to other MS assays where linear variation in IS signal is observed.

Biotin supplementation causes erroneous elevations of results in some commercial serum 25-hydroxyvitamin d (25OHD) assays

The Vitamin D External Quality Assessment Scheme (DEQAS) distributes serum samples globally, on a quarterly basis, to assess participants' performance of specific methods for 25-hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25-(OH)₂D). DEQAS occasionally circulates samples containing high levels of substances found in certain clinical situations e.g. 25-OHD₂, 24,25-(OH)₂D₃, hypertriglyceridemia. The increased availability and use of health supplements containing biotin has led to case reports of assay interference in methods utilizing a biotin-streptavidin detection system. In October 2018, DEQAS included a serum sample (545) containing exogenous biotin (concentration =586 μg/L) which was analyzed by a total of 683 laboratories using 35 different methods. The same serum sample (544) without exogenous biotin was also included in the 5-sample set. All methods (760 laboratories) performed satisfactorily on sample 544 giving an All-Laboratory Trimmed Mean = 50.2 ± 6.5 nmol/L (±SD, CV = 12.9 %). The target value for this sample 544 (& 555) was 47.4 nmol/L as determined by Centers for Disease Control and Prevention (CDC) Atlanta, Georgia using their LC-MS/MS reference method. In contrast, #545 containing the exogenous biotin was reported by only 683 laboratories and gave an All-Laboratory Trimmed Mean = 66.8 ± 37.6 nmol/L (±SD, CV = 56.3 %). As expected, LC-MS/MS methods (143 labs) reported similar results for both 544 = 48.9 ± 4.4 nmol/L (±SD) and 545 = 48.3 ± 4.5 nmol/L (±SD) showing that assays involving chromatographic steps are unaffected by the presence of biotin. Several of the antibody-based assays including Abbott Architect, DiaSorin Liaison, Beckman Unicel and Siemens Centaur are also unaffected by the addition of biotin. Two assays, IDS-iSYS and Roche Total 25OHD, both of which use biotin-streptavidin, exhibit biotin interference yielding values with a significant positive bias for 545 of 102.6 nmol/L ± 78.7 nmol/L (±SD) and 517.8 nmol/L ± 209.8 nmol/L (±SD) respectively. Interestingly, the failure to report sample 545 data from 77 laboratories is due solely to those running Roche Total 25OHD or Roche Vitamin D Total II assays. Given the prevalence of the adversely affected assays (25 % of DEQAS users) and the high volume of 25OHD testing, clinicians using these assays should, where possible, only measure 25OHD when patients are off biotin.

Estimating uncertainty of target values for DEQAS serum materials

The External Quality Assessment (EQA) scheme for vitamin D metabolites (DEQAS) distributes human serum samples to laboratories across the world to assess their performance in measuring serum total 25-hydroxyvitamin D [25(OH)D], i.e. the sum of the concentrations of serum 25(OH)D₂ and 25(OH)D₃. In 2013 DEQAS, in collaboration with the Vitamin D Standardization Program (VDSP), became an accuracy-based EQAS when the National Institute for Standards and Technology (NIST) began assigning 25(OH)D target values to DEQAS serum samples using their Joint Committee for Traceability in Laboratory Medicine (JCTLM) approved reference measurement procedure (RMP). Historically, NIST has performed 4 determinations of 25-OHD2 and 25-OHD3 on each sample and used the mean values to calculate a single 'target value' for Total 25-OHD against which performance was judged. By definition the target values cannot be exact and each is associated with a level of uncertainty. The total uncertainty (U_NIST) has two components, one from the 25(OH)D₂, and 25(OH)D₃ measurements and the other associated with the calibration procedure. The total combined uncertainty is calculated by adding up these uncertainties. In future, uncertainties will be attached to the target value in each DEQAS serum sample, starting with the next distribution cycle in 2019. Confidence intervals obtained using these uncertainties will allow DEQAS participants to determine if their result agrees with the NIST assigned target value. Furthermore, if the value falls within the confidence interval the laboratory's assay would be regarded as traceable, i.e. standardized, to the NIST RMP.

External Quality Assessment of 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) assays

The discovery that mutations of the CYP24A1 gene are a cause of idiopathic infantile hypercalcemia (IIH) has revived interest in measuring serum 24,25(OH)₂D₃. Several studies have also suggested that a high 25-hydroxyvitamin D₃(25-OHD₃):24,25(OH)₂D₃ ratio might provide additional diagnostic information in the investigation of vitamin D deficiency. Measurement of 24,25(OH)₂D₃ is necessarily restricted to laboratories with mass spectrometry methods although cross reactivity of the metabolite in immunoassays for 25-OHD is a potential cause of misleading results. The international External Quality Assessment (EQA) scheme for vitamin D metabolites (DEQAS) was set up in 1989. In 2013 DEQAS became an accuracy based EQA for 25-OHD with 'target values' assigned by the National Institute of Standards and Technology (NIST) Reference Measurement Procedure (RMP). A pilot scheme for serum 24,25(OH)₂D₃ was started in 2015 and participants were asked to measure the metabolite on each of the 5 samples sent out for 25-OHD. Inter-laboratory agreement was poor but this may reflect methodological differences, in particular different approaches to assay standardization. An important potential contribution to reducing variability among assays was the development by NIST of a 24,25(OH)₂D₃ RMP and its use in assigning values to SRMs 972a, 2973 and 2971, supported by the NIH Office of Dietary Supplements (ODS) as part of the Vitamin D Standardization Program (VDSP) effort.

Hydroxyvitamin D assays: An historical perspective from DEQAS

Recent years have seen a substantial increase in demand for 25-hydroxyvitamin D (25-OHD) assays. DEQAS (the Vitamin D External Quality Assessment Scheme) has been monitoring the performance of these assays since 1989. The first DEQAS distribution was in June 1989 and results were submitted by 13 laboratories in the UK, two of which used HPLC/UV; the rest used ligand binding assays with a tritium tracer. Inter-laboratory CVs (ALTM) ranged from 29.3% (42.7nmol/L) to 53.7% (20.0nmol/L). Currently the scheme has participants in 56 countries using 30 methods or variants of methods. In January 2017, 918 participants returned results and inter-laboratory CVs (ALTM) ranged from 10.3% (73.1nmol/L) to 15.3% (29.4nmol/L). Over the last 27 years, there have been a number of significant milestones in assay development. The first major advance was the development of an iodinated 25-OHD tracer by Hollis and Napoli in 1992, subsequently used in an RIA kit marketed by DiaSorin. This and other commercial radioimmunoassays that followed brought 25-OHD assays within reach of many more non-specialist routine laboratories. With the introduction of fully automated non-isotopic assays without solvent extraction, measurement of 25-OHD became available to any clinical chemistry laboratory with an appropriate analytical platform. However, as the limitations of these non-extraction assays became apparent more laboratories started using LC-MS/MS methodology. Meanwhile the variable accuracy of 25-OHD methods has been addressed by the Vitamin D Standardization Program (VDSP) which encourages manufacturers to produce methods traceable to the reference measurement procedures (RMPs) of NIST, University of Ghent and the Centers for Disease Control and Prevention (CDC). DEQAS changed to an accuracy-based scheme in 2013 and now assesses assay accuracy against the NIST RMP. This review will use DEQAS results and statistics to chart the historical development in 25-OHD assay technology and highlight some of the problems encountered in obtaining reliable results for this most challenging of analytes.

Quality assessment of vitamin D metabolite assays used by clinical and research laboratories

The Vitamin D External Quality Assessment Scheme (DEQAS) was launched in 1989 and monitors the performance of 25-hydroxyvitamin D (25-OHD) and 1,25- dihydroxyvitamin D (1,25(OH)₂D) assays. In April 2015 a pilot scheme for 24,25-dihydroxyvitamin D (24,25(OH)₂D) was introduced. The 25-OHD scheme is accuracy - based with target values assigned by the NIST Reference Measurement Procedure (RMP) for 25-OHD₂ and 25-OHD₃. A similar method is used to assign values for 3-epi-25-OHD. Five samples of human serum are distributed quarterly to over 1000 participants in 58 countries (April 2016) and clinical laboratories are expected to submit results within approximately 5 weeks. Research laboratories with assays run less frequently are not given a deadline. Archived samples with NIST- assigned values are also available. Performance is assessed on the first four samples with the fifth reserved for investigations e.g. recovery experiments or to assess the influence of other serum constituents such as lipids. DEQAS provides rapid feedback, with an on-line preliminary report available immediately after a participant submits results and a comprehensive report soon after the results deadline. In 2015, DEQAS investigations revealed that several 25-OHD immunoassays under-recovered 25-OHD₂ and 25-OHD results were falsely low on a sample with a modestly raised triglyceride concentration. An RMP for 1,25 (OH)₂D is not yet available and results are judged against the Method Mean. Free advice is available from the DEQAS Advisory Panel which includes experts on methodology and biostatistics. DEQAS collaborates closely with the Vitamin D Standardization Program (VDSP) and both organizations have successfully worked with participants and manufacturers to improve the accuracy of vitamin D assays.

25-Hydroxyvitamin D assays: Potential interference from other circulating vitamin D metabolites

The vitamin D External Quality Assessment Scheme (DEQAS) for 25-hydroxyvitamin D (25-OHD) has approximately 1100 participants in 53 countries using 26 different methods or variants of methods (October 2014). In April 2015, the scheme was extended to cover 24,25-dihydroxyvitamin D (24,25(OH)₂D). Since 2013, the 25-OHD scheme has been accuracy-based with values assigned by the NIST reference measurement procedure (RMP). DEQAS is uniquely placed to assess the accuracy (bias) and specificity of 25-OHD methods in a routine laboratory setting. Other vitamin D metabolites are known to interfere in 25-OHD assays and DEQAS has distributed samples spiked with 3-epi-25-OHD₃ (52.4nmol/L), 24R,25(OH)₂D₃ (14.4nmol/L) and 24S,25(OH)₂D₃ (57.9nmol/L). The 3-epimer showed a cross reactivity of 56% in a competitive protein binding assay but was not detected in any antibody-based methods. Not all HPLC/UV or LC-MS/MS methods were able to resolve 3-epi-25-OHD₃ from 25-OHD₃ and thus overestimated total 25-OHD. The cross reactivity of 24R,25(OH)₂D₃ (24S,25(OH)₂D₃) ranged from <5% (<5%) to 548% (643%) in ligand binding assays. Both 24-hydroxylated metabolites were resolved by HPLC/UV and LC-MS/MS methods and thus caused no complications in the measurement of 25-OHD. Most antibodies to 25-OHD are known to cross-react with dihydroxylated metabolites but interference in some assays was far greater than expected. This may be related to the anomalous behaviour of exogenously added metabolites in these 25-OHD methods.

Myocardial infarction in a young man with antiphospholipid syndrome and cocaine use

The authors present a case of myocardial infarction in a 26-year-old man with antiphospholipid syndrome (APS) and a history of recent cocaine use. His only traditional cardiovascular risk was that he smoked. The authors propose that his cocaine use and APS brought about a potentially catastrophic cardiac event despite therapeutic anticoagulation. This was supported by the finding of normal coronary arteries on angiography despite both a significant regional wall motion abnormality on echocardiography and a significant rise in Troponin I. This case suggests the presence of a synergistic effect between cocaine and antiphospholipid antibodies. ( Lupus (2007) 16, 444—446)

The osteoarthritic niche and modulation of skeletal stem cell function for regenerative medicine

Osteoarthritis (OA) is the most common cause of arthritis worldwide and represents a significant healthcare burden, particularly in the context of an ageing population. Traditionally, painkillers, injections and physiotherapy have been the mainstay of treatment, with patients being referred for joint replacement surgery (arthroplasty) when these options fail. Whilst effective in reducing pain and improving joint function, these approaches are not without potential complications. With the development of tissue-engineering techniques over recent years there has been considerable interest in applying these strategies to provide new, innovative, alternative effective means of treating OA. This review explores the unique microenvironment present within an osteoarthritic joint, highlighting the features that comprise the osteoarthritic niche and could be modulated in the development of novel treatments for OA. Existing tissue-engineering strategies for repairing bone and cartilage defects are discussed, with particular reference to how these might be modified, both to improve existing treatments, such as impaction bone grafting, as well as in the development of future treatments for OA.

Potential teratogenic effects of ultrasound on corticogenesis: implications for autism

The phenotypic expression of autism, according to the Triple Hit Hypothesis, is determined by three factors: a developmental time window of vulnerability, genetic susceptibility, and environmental stressors. In utero exposure to thalidomide, valproic acid, and maternal infections are examples of some of the teratogenic agents which increase the risk of developing autism and define a time window of vulnerability. An additional stressor to genetically susceptible individuals during this time window of vulnerability may be prenatal ultrasound. Ultrasound enhances the genesis and differentiation of progenitor cells by activating the nitric oxide (NO) pathway and related neurotrophins. The effects of this pathway activation, however, are determined by the stage of development of the target cells, local concentrations of NO, and the position of nuclei (basal versus apical), causing consequent proliferation at some stages while driving differentiation and migration at others. Ill-timed activation or overactivation of this pathway by ultrasound may extend proliferation, increasing total cell number, and/or may trigger precipitous migration, causing maldistribution of neurons amongst cortical lamina, ganglia, white matter, and germinal zones. The rising rates of autism coincident with the increased use of ultrasound in obstetrics and its teratogenic/toxic effects on the CNS demand further research regarding a putative correlation.

The presence of anticardiolipin antibodies in adults may be influenced by infections in infancy

OBJECTIVES

There has been limited success defining environmental factors important in the development of antiphospholipid (Hughes) syndrome (APS). Recent work suggests that the perinatal environment may be important in the development of other autoimmune diseases. We measured anticardiolipin antibodies (aCL) in a general population with well-defined early lives to see whether fetal and infant growth and infections were associated with aCL positivity in adult life.

METHODS

aCLs were measured using an ELISA in 1384 individuals from the Hertfordshire cohort study. We investigated associations between the presence of aCL and early growth and infectious exposure in infancy in men and women.

RESULTS

ELISA positive aCL (IgM and IgG) was present in 22 (3%) men and 15 (2%) women. Using the highest octile of aCL results, in men higher birth weight (per lb of birth weight: OR 1.18, 95% CI 1.02-1.36, P = 0.02) and diarrhoeal infection in the first year of life (OR 2.55, 95% CI 1.10, 5.92, P = 0.03) were associated with an increased likelihood of being aCL positive. In women, diarrhoeal infection in the first year of life was also associated with an increased likelihood of aCL positivity (OR 2.23, 95% CI 1.01, 4.91, P = 0.05). For IgG titre in men, significant relationships were found with sharing a bedroom (regression coefficient 1.13; 95% CI 1.05, 1.22; P = 0.02) and diarrhoea in the first year (coefficient 1.25; 95% CI 1.00, 1.56; P = 0.05).

CONCLUSION

A developing immune system when exposed to the infectious environment may influence the likelihood of producing aCL in adult life.

Occurrence of infected amoebae in cooling towers compared with natural aquatic environments: implications for emerging pathogens

Many species of bacteria pathogenic to humans, such as Legionella, are thought to have evolved in association with amoebal hosts. Several novel unculturable bacteria related to Legionella have also been found in amoebae, a few of which have been thought to be causes of nosocomial infections in humans. Because amoebae can be found in cooling towers, we wanted to know whether cooling tower environments might enhance the association between amoebae and bacterial pathogens of amoebae in order to identify potential "hot spots" for emerging human pathogens. To compare occurrence of infected amoebae in natural environments with those in cooling towers, 40 natural aquatic environments and 40 cooling tower samples were examined. Logistic regression analysis determined variables that were significant predictors of the occurrence of infected amoebae, which were found in 22 of 40 cooling tower samples but in only 3 of the 40 natural samples. An odds ratio showed that it is over 16 times more likely to encounter infected amoebae in cooling towers than in natural environments. Environmental data from cooling towers and natural habitats combined revealed dissolved organic carbon (DOC) and pH were predictors of the occurrence of the pathogens, however, when cooling tower data alone were analyzed, no variables accounted for the occurrence. Several bacteria have novel rRNA sequences, and most strains were not culturable outside of amoebae. Such pathogens of amoebae may spread to the environment via aerosols from cooling towers. Studies of emerging infectious diseases should strongly consider cooling towers as a source of amoeba-associated pathogens.

Effects of Short-Term Glucagon Administration on Gluconeogenic Enzymes in the Liver of Midlactation Dairy Cows

During lactation, the dairy cow experiences an increased demand for glucose to support milk production. Increased glucose demand can be met through increased capacity for gluconeogenesis, increased supply of glucose precursors, or a combination of both processes. Glucagon, a key hormone in glucose homeostasis, acts to promote gluconeogenesis and increase glucose output from liver. The objective of this study was to determine the effect of short-term administration of glucagon on expression of gluconeogenic enzymes in lactating dairy cattle. Sixteen multiparous Holstein cows were selected from the Purdue University Animal Sciences Dairy Research Center herd. Cows were stratified on the basis of milk production and days in milk and randomly assigned to either a saline or glucagon injection group (n = 8 per group). Cows were injected subcutaneously at -21, -14, -7, and 0 h relative to final glucagon and saline injections with either 3.75 mg of lyophilized bovine glucagon (15 mg/d) dissolved in 60 mL of 0.15 M NaCl (pH 10.25) or 60 mL of 0.15 M NaCl. Liver biopsy samples were obtained 1 wk before injection to establish baseline values and at 3 h after cows received final glucagon and saline injections. Biopsy samples were analyzed for mRNA abundance, enzyme activity, protein abundance, and in vitro measures of gluconeogenesis. Glucagon did not alter pyruvate carboxylase or cytosolic phosphoenolpyruvate carboxykinase (PEPCK) mRNA abundance, enzyme activity, or protein abundance, although there was a tendency for greater mRNA expression with the glucagon treatment (4.69 vs. 6.78, arbitrary units). Glucagon injections did not change mitochondrial PEPCK mRNA expression. Gluconeogenesis from 2.5 mM [2-(14)C]propionate and 2.0 mM [U-(14)C]lactate was similar in liver biopsy samples from glucagon-treated and control cows. There was no effect of glucagon on dry matter intake and milk production. Glucose, nonesterified fatty acids, beta-hydroxybutyrate acid, and insulin were not altered by glucagon. Blood glucagon was elevated, 76.09 vs. 96.14 pg/mL, for cows receiving glucagon injections. The data indicate that 24-h administration of glucagon does not alter cytosolic PEPCK mRNA expression or result in immediate alterations in total PEPCK enzyme activity and gluconeogenic capacity.

A microsatellite genetic linkage map for Xiphophorus

Interspecies hybrids between distinct species of the genus Xiphophorus are often used in varied research investigations to identify genomic regions associated with the inheritance of complex traits. There are 24 described Xiphophorus species and a greater number of pedigreed strains; thus, the number of potential interspecies hybrid cross combinations is quite large. Previously, select Xiphophorus experimental crosses have been shown to exhibit differing characteristics between parental species and among the hybrid fishes derived from crossing them, such as widely differing susceptibilities to chemical or physical agents. For instance, genomic regions harboring tumor suppressor and oncogenes have been identified via linkage association of these loci with a small set of established genetic markers. The power of this experimental strategy is related to the number of genetic markers available in the Xiphophorus interspecies cross of interest. Thus, we have undertaken the task of expanding the suite of easily scored markers by characterization of Xiphophorus microsatellite sequences. Using a cross between Xiphophorus maculatus and X. andersi, we report a linkage map predominantly composed of microsatellite markers. All 24 acrocentric chromosome sets of Xiphophorus are represented in the assembled linkage map with an average intergenomic distance of 7.5 cM. Since both male and female F1 hybrids were used to produce backcross progeny, these recombination rates were compared between "male" and "female" maps. Although several genomic regions exhibit differences in map length, male- and female-derived maps are similar. Thus Xiphophorus, in contrast to zebrafish, Danio rerio, and several other vertebrate species, does not show sex-specific differences in recombination. The microsatellite markers we report can be easily adapted to any Xiphophorus interspecies and some intraspecies crosses, and thus provide a means to directly compare results derived from independent experiments.

Effects of a replication of a multicomponent model for preventing adolescent pregnancy in three Kansas communities

CONTEXT

A significant amount of attention has been devoted to the complex issue of teenage pregnancy and to programs for reducing pregnancy among adolescents. Careful evaluations of such programs are needed to ascertain what strategies will be most effective at reducing teenage pregnancy.

METHODS

A pretest-posttest comparison group design was used to analyze the effects of a comprehensive multicomponent school and community intervention on estimated pregnancy rates and birthrates among young people in three Kansas communities: Geary County, Franklin County and selected neighborhoods of Wichita.

RESULTS

There were high levels of program activity in all three communities during the intervention period, including teacher training and sexuality education for students. Survey respondents rated highly such project interventions as the extension of school-linked clinic hours to accommodate student schedules and support groups established in middle schools. Between 1994 and 1997, the proportions of adolescents reporting that they had ever had sex decreased significantly among all ninth and 10th graders in Geary County, from 51% to 38% among females and from 63% to 43% among males. In Franklin County, more males in grades 11 and 12 reported using condoms in 1996 (55%) than had done so in 1994 (39%). Age at first intercourse remained relatively stable in Franklin and Geary counties during the intervention period. The estimated pregnancy rate among adolescents aged 14-17 decreased between 1994 and 1997 in Geary Country, while it increased in comparison areas. The estimated pregnancy rates among 14-17-year-olds decreased in both Franklin County and its comparison communities. The birthrate declined both in one target area of Wichita and in its comparison area from 1991-1993 to 1994-1996. Over the same time period, the birthrate increased in a second target area of Wichita, while it decreased in the comparison community.

CONCLUSIONS

This evaluation of a comprehensive multicomponent program for adolescent pregnancy prevention contributes to our understanding of this model and its replicability in diverse communities. Ongoing program evaluation is important for developing initiatives and for refining strategies so they respond to local conditions.

The effect of intravenous lactated Ringer's solution versus 0.9% sodium chloride solution on serum osmolality in human volunteers

Animal studies have shown that large volumes of IV lactated Ringer's solution (LR) decrease serum osmolality, thereby increasing cerebral water. These studies have led to recommendations to limit LR to avoid cerebral edema in neurosurgical patients. Eighteen healthy human volunteers aged 20-48 yr received 50 mL/kg LR over 1 h on one occasion and 0.9% sodium chloride (NS) on another. Venous samples were taken at baseline (T1), at infusion end (T2), and 1 h after T2 (T3). Time until first urination was noted. With LR, serum osmolality decreased by 4+/-3 mOsm/kg from T1 to T2 and increased insignificantly with NS. At T3, osmolality returned almost to baseline in the LR group. Blood pH increased from T1 to T2 with LR by 0.04+/-0.04 and decreased with NS by 0.04+/-0.04. These pH changes persisted at T3. Subjective mental changes occurred only with NS. Abdominal discomfort was more common with NS. Time until first urination was longer with NS (106+/-11 min) than with LR (75+/-10 min) (P < 0.001). In healthy humans, an infusion of large volumes of LR, but not NS, transiently decreased serum osmolality, whereas acidosis associated with NS persisted and urinary output was slower with NS.

IMPLICATIONS

Large volumes of lactated Ringer's solution administered to healthy humans produced small transient changes in serum osmolality. Large volumes of sodium chloride did not change osmolality but resulted in lower pH.

wing blister, a new Drosophila laminin alpha chain required for cell adhesion and migration during embryonic and imaginal development

We report the molecular and functional characterization of a new alpha chain of laminin in Drosophila. The new laminin chain appears to be the Drosophila counterpart of both vertebrate alpha2 (also called merosin) and alpha1 chains, with a slightly higher degree of homology to alpha2, suggesting that this chain is an ancestral version of both alpha1 and alpha2 chains. During embryogenesis, the protein is associated with basement membranes of the digestive system and muscle attachment sites, and during larval stage it is found in a specific pattern in wing and eye discs. The gene is assigned to a locus called wing blister (wb), which is essential for embryonic viability. Embryonic phenotypes include twisted germbands and fewer pericardial cells, resulting in gaps in the presumptive heart and tracheal trunks, and myotubes detached from their target muscle attachment sites. Most phenotypes are in common with those observed in Drosophila laminin alpha3, 5 mutant embryos and many are in common with those observed in integrin mutations. Adult phenotypes show blisters in the wings in viable allelic combinations, similar to phenotypes observed in integrin genes. Mutation analysis in the eye demonstrates a function in rhabdomere organization. In summary, this new laminin alpha chain is essential for embryonic viability and is involved in processes requiring cell migration and cell adhesion.

The effect of perceived control over eating on the life satisfaction of women and men: results from a community sample

OBJECTIVE

To test whether overweight, or perception of lack of control over eating, or both, contributed to the level of life satisfaction for women and men in a random sample of community-dwelling adults.

METHOD

This study examined the effects of body mass index (BMI) and perceived control over eating on life satisfaction for women and men in a community-based sample of 1,069 women and 963 men.

RESULTS

For women, both lack of perceived eating control and higher BMI were associated with less life satisfaction, and lack of control over eating was the more important predictor. For men, only lack of perceived eating control was associated with less life satisfaction. Furthermore, for both women and men, the contribution of eating control to life satisfaction was unaffected by BMI, that is, the life satisfaction of heavier people was not more affected by perceived control over eating than was the life satisfaction of lighter people.

DISCUSSION

These findings suggest that psychological issues related to eating and weight can affect global aspects of well-being.

Requirements for the cytoplasmic domain of the alphaPS1, alphaPS2 and betaPS integrin subunits during Drosophila development

The integrins are a family of transmembrane heterodimeric proteins that mediate adhesive interactions and participate in signaling across the plasma membrane. In this study we examine the functional significance of the cytoplasmic domains of the alphaPS1, alphaPS2 and betaPS subunits of the Drosophila Position Specific (PS) integrin family by analyzing the relationship between cytoplasmic domain structure and function in the context of a developing organism. By examining the ability of ssPS molecules lacking the cytoplasmic domain to rescue embryonic abnormalities associated with PS integrin loss, we find that although many embryonic events require the betaPS cytoplasmic domain, this portion of the molecule is not required for at least two processes requiring PS integrins: formation of midgut constrictions and maintaining germband integrity. Furthermore, our studies demonstrate that mutant proteins affecting four highly conserved amino acid residues in the cytoplasmic tail function with different efficiencies during embryonic development, suggesting that interaction of PS integrins with cytoplasmic ligands is developmentally modulated during embryogenesis. We have also examined the ability of alphaPS1 and alphaPS2 to function without their cytoplasmic domains. By analyzing the ability of transgenes producing truncated alphaPS molecules to rescue abnormalities associated with integrin loss, we find that the cytoplasmic tail of alphaPS2 is essential for both embryonic and postembryonic processes, while this portion of alphaPS1 is not required for function in the wing and in the retina. Furthermore, temperature-shift experiments suggest roles for the alphaPS2 cytoplasmic domain in signaling events occurring in the developing wing.

Evaluating community coalitions for prevention of substance abuse: the case of Project Freedom

In the United States alone, there are more than 2,000 community coalitions to address local concerns about abuse of alcohol, tobacco, and other drugs. This article describes an evaluation system used to examine the process, outcome, and impact of coalitions for the prevention of substance abuse. The evaluation addresses five key questions: (a) Was the community mobilized to address substance abuse (Process)? (b) What changes in the community resulted from the coalition (Outcome)? (c) Is there a change in reported use of alcohol and other substances by youths (Outcome)? (d) Does the coalition have a community-level impact on substance abuse (Impact)? and (e) Is community-level impact related to changes facilitated by the coalition (Impact)? To address these and other questions, using eight core measurement instruments, the evaluation system collects 15 distinct measures. This evaluation system is illustrated with a multiyear study of Project Freedom, a substance abuse coalition in a large midwestern city.

A novel alpha integrin subunit associates with betaPS and functions in tissue morphogenesis and movement during Drosophila development

We have identified a novel alpha integrin subunit in Drosophila, that associates with betaPS integrin. We report the temporal expression of the gene encoding this integrin subunit, which we have called alphaPS3, throughout development and the localization of its expression during embryogenesis. AlphaPS3 RNA was localized to tissues undergoing invagination, tissue movement and morphogenesis such as salivary gland, trachea, midgut, dorsal vessel, midline of the ventral nerve cord, amnioserosa and the amnioproctodeal invagination. AlphaPS3 DNA localized to the chromosomal vicinity of scab (scb), previously identified by a failure of dorsal closure. Embryos homozygous for the 119 allele of scb had no detectable alphaPS3 RNA and the 1035 allele of scb contains a Pelement inserted just 5′ of the coding region for the shorter of the gene's two transcripts. Furthermore, mutations in the scb locus exhibit additional defects corresponding to sites of alphaPS3 transcription, including abnormal salivary glands, mislocalization of the pericardial cells and interrupted trachea. Removal of both maternal and zygotic betaPS produced similar defects, indicating that these two integrin subunits associate in vivo and function in the movement and morphogenesis of tissues during development in Drosophila. Phenotypic similarities suggest that laminin A is a potential ligand for this integrin, at least in some tissues.

Ketorolac appears to decrease polyuria during intracranial surgery

Two cases are described of patients, undergoing surgery for intracranial pathology, who developed polyuria intraoperatively. The urine output decreased to within normal range shortly after the administration of ketorolac, a nonsteroidal antiinflammatory drug. The possible mechanisms producing the increased urinary output and the influence of prostaglandins on renal function are discussed.

Molecular characterization of a caprine adenovirus

Restriction endonuclease site maps were constructed for the genome of a caprine adenovirus (GAdV), strain NC90-7261, which was isolated in 1990 from a 3-year-old goat with encephalitis. Genomic GAdV DNA was digested with seven restriction endonucleases (RE). Genomic DNA libraries of GAdV were constructed by cloning BamHI and HindIII restriction fragments into a plasmid vector. Using cloned GAdV genomic fragments as probes in Southern blot hybridizations, an RE site map was constructed. The position of several clones was confirmed by limited nucleotide sequencing and the location of several RE sites was determined by single or double RE digestions of cloned fragments. The size of the GAdV genome was determined to be 28.2 kbp. The restriction pattern described in this report is different from that of other adenoviruses. Although the genomic organization of this GAdV is likely to be similar to that of other adenoviruses, the overall level of sequence similarity is low.

Using empowerment theory in collaborative partnerships for community health and development

Models of community empowerment help us understand the process of gaining influence over conditions that matter to people who share neighborhoods, workplaces, experiences, or concerns. Such frameworks can help improve collaborative partnerships for community health and development. First, we outline an interactive model of community empowerment that describes reciprocal influences between personal or group factors and environmental factors in an empowerment process. Second, we describe an iterative framework for the process of empowerment in community partnerships that includes collaborative planning, community action, community change, capacity building, and outcomes, and adaptation, renewal, and institutionalization. Third, we outline activities that are used by community leadership and support organizations to facilitate the process of community empowerment. Fourth, we present case stories of collaborative partnerships for prevention of substance abuse among adolescents to illustrate selected enabling activities. We conclude with a discussion of the challenges and opportunities of facilitating empowerment with collaborative partnerships for community health and development.

Breastfeeding attitudes and knowledge of pediatricians-in-training

A 15-minute questionnaire was administered to the pediatric housestaff in an academic training program to assess their breastfeeding attitudes, knowledge, and confidence to manage breastfeeding problems. Questionnaires were self-administered and anonymous. The participation rate was 53% (n = 29). Overall, the study participants indicated a supportive attitude toward breastfeeding (2.6 on a 6-point scale where 1 = most supportive and 6 = least supportive). Women agreed more strongly than men that pediatricians should strongly encourage mothers to breastfeed and disagreed more strongly than men that breastfeeding is instinctive. Although supportive of breastfeeding, the housestaff in this study were not knowledgeable regarding breastfeeding management, answering only 53% of the questions correctly. Their self-confidence in this area was appropriately low, with only 14% of the total sample describing themselves as "confident" or "very confident" to manage common breastfeeding problems. Pediatricians-in-training have extremely limited knowledge of breastfeeding management. To be truly supportive of breastfeeding, pediatricians should receive didactic and clinical training in breastfeeding management.

Monitoring ambient ozone with a network of passive samplers: a feasibility study

Ambient levels of ozone have been measured at 46 mountain forest, desert, Class I Wilderness areas and other remote locations using a network of passive samplers. Typical values were 40-80 ppb (2 week samples) and exhibited temporal variations (studied for up to 1 year) as well as changes with elevation (studied up to 10 500 ft (3 200 m)). The performance of the passive sampler was evaluated with respect to reproducibility, field controls, data capture (>0.95), precision for co-located samples (av. = 11.9%, n = 103), and the role of other atmospheric oxidants as potential interferents (2 locations). Suggestions for additional sampler performance evaluation and network operation are outlined.

Breastfeeding initiation among a low income multiethnic population in northern California: an exploratory study

Influences on the decision to initiate breastfeeding among low income mothers served by a suburban medical center in northern California were explored. Sixty-four mothers of children 0-24 months of age were interviewed in English or Spanish regarding their infant feeding education, breastfeeding attitudes and behavior, and social support. Fifty-nine percent reported having discussed infant feeding with a physician; these mothers were more likely to attempt breastfeeding than those who did not. Fifty-nine percent of the entire study population initiated breastfeeding. Initiation rates were highest for the Asian American group (86 percent), and lowest for Latinas (48 percent). Further research is needed regarding modifiable influences on breastfeeding initiation, including physician encouragement to breastfeed, for various ethnic groups.

Changes in coronary heart disease risk factors in the 1980s: evidence of a male-female crossover effect with age

The Stanford Five-City Project was initiated in 1978 to evaluate the effects of community-wide health education on coronary heart disease risk factors in two control (San Luis Obispo and Modesto) and two treatment (Monterey and Salinas) cities. This paper examines sex differences in the prevalence of smoking, hypercholesterolemia, and hypertension from the baseline survey in 1979-1980 through the conclusion of the intervention in 1985-1986. Four independent cross-sectional surveys (n = 1,713, 1,709, 1,848, and 1,768) and four repeated surveys of a cohort (n = 817) were conducted. This analysis presents findings separately for a younger age group (25-49 years) and an older age group (50-74 years). Smoking, hypercholesterolemia, and hypertension were more prevalent among younger men than younger women in both treatment and control cities. In general, this excess risk among younger men disappeared or reversed in the older age group. Over the 7-year study, the prevalence of hypertension and smoking decreased for both men and women in all surveys, the prevalence of hyper-cholesterolemia displayed no definite change, and male/female ratios of risk factor prevalence showed either no change or a slight decrease. This study confirms a higher prevalence of the three major risk factors for coronary heart disease among younger men, with the prevalence of hypercholesterolemia and, to a lesser extent, the prevalence of smoking becoming greater among women than men in the older age group and the prevalence of hypertension becoming equivalent.