Top Tubes Research Articles

Qualification of a 17β-estradiol (E2) Assay in Sprague Dawley Rat Serum

Abstract Introduction/Objective Significant technical issues are associated with methods used for the measurement of estradiol.The objective of this study was to qualify an electrochemiluminescent (ECL) assay for the quantification of 17β-estradiol (E2) in rat serum. Hemolysis has been identified as a factor that interferes with accurate measurement.The impact of hemolysis was also assessed. Methods Approximately 1.0 mL of whole blood was collected from male and female rats into separate red top tubes and processed to serum. The LoQ for E2 was evaluated by analyzing the low calibrator or at least 6 serum samples diluted to produce a value at the low end of the reportable range 8 times in the same run.The mean, standard deviation, and %CV were calculated for each sample.The data set was analyzed by plotting the data and determining the concentration at the intersection of the precision profile curve. Linearity of dilution was performed using commercially available calibration verification material and E2 stripped rat serum.The correlation coefficient, the slope, and the % Nominal were calculated. Intra assay precision was evaluated by analyzing 8 consecutive times in a single run one rat serum sample that was not diluted or spiked. This analysis was performed during the evaluation of the LoQ.The mean, SD and %CV were calculated. The interference of hemolysis with the E2 assay was tested by analyzing at least 5 rat serum samples/pools spiked with hemolyzed rat serum at different hemoglobin concentrations.The %RE was calculated. Results The LoQ assays were acceptable. For all samples tested, the % CV was less than or equal to 25%.The LoQ was verified to be 8.50 pg/mL. The %CV was 15.6%. For samples with estradiol concentrations below the LoQ, a value of 4.25 pg/ml was reported. Linearity of dilution for E2 was acceptable.The correlation coefficients were greater than or equal to 0.9000, the slopes were between 0.7500 and 1.2500, and the % nominals for each level were between 75-125%. The intra-assay precision was considered acceptable with a %CV of 8.6%. There was no hemolysis interference in the assay when samples were spiked with hemoglobin concentrations of up to 70 mg/dL, based on the %RE of less than or equal to 25% of non-hemolyzed samples. Conclusion Qualification of the ECL method, demonstrates the assay is suitable for the determination of E2 in serum samples from rats and absence of hemolysis interference up to 70 mg/dL of hemoglobin concentration.

Intact Glucosinolate Determination in Brassica Vegetables Using Anion Exchange Cleanup and HILIC (Hydrophilic Interaction Liquid Chromatography) HPLC Chromatography

In this work an HPLC/hydrophilic interaction liquid chromatography (HILIC) system for intact glucosinolates was optimized using a weak anion exchange resin to remove carboxylic phenolics that absorbed at the same wavelength (229 nm) as glucosinolates, by selectively protonating contaminating phenolics with pKas from 2.98 to 4 while leaving the second OH of the sulfate of the thioglycosidic linkage (pKa = 1.92) ionized. Glucosinolates bound to the anion exchange resin, while the contaminating phenolics washed through. The extraction was performed in 2-ml snap top centrifuge tubes with 50 to 80 mg of fresh tissue in 0.3 ml of extractant. The corresponding spin tubes contained 20–22 mg of anion exchange resin and were loaded with 100 μl of extractant. A 48-well pressure plate was used to load, wash, and finally elute the glucosinolates without a centrifuge into autosampler vials. Seventeen glucosinolates found in common vegetables were separated in a 16-min isocratic run vs 50 min for the C18 gradient used in the desulfoglucosinolate method. The recovery of a spiked sample of phenethyl glucosinolate was greater than 90%, and the limit of detection (LOD) and limit of quantitation (LOQ) were 6.85 and 20.78 nmol respectively. The time from sample weighing to the end of the first chromatographic run was approximately 2 h.

1528-P: Blood Level of Alpha-1 Antitrypsin in the Course of Acute Myocardial Infarction in Diabetic Patients: A Possible Clinical Significance

Introduction: Alpha-1 antitrypsin (A1AT) is known to protect lung tissue from damage. Such protection is extended to myocardial tissues during myocardial ischemia/infarction. Objective: The aim of the study was to determine the time course of A1AT levels in the plasma of myocardial infarction patients over 96 hours and compare it with healthy individuals. Methods: Blood samples were collected from patients (n=40, age 58 ± 11 yrs, males 29 and females 11), at 1, 4, 24, 48 and 96 hrs after confirmed diagnosis and admission to King Salman Cardiac Center in King Fahad Medical City, Riyadh, Saudi Arabia. IRB approval and consent was signed by all patients. The patients were divided into diabetics (n=19) and nondiabetic (21). Blood samples were collected in purple top tubes containing EDTA to prevent blood coagulation and immediately centrifuged at 6000 rpm at 4 C for 20 min. Plasma was decanted and stored at - 20 C until analyzed. AlAT was determined in plasma using Eliza kits (abcam, USA). Control blood samples were collected from 20 healthy individuals (age 46±10 yrs. Results: A1AT were significantly less in MI patients (1025±77 ug/ml at 96 hrs, P<001, n=40) compared to (1655±128 ug/ml, n=20) (mean ±SEM) in controls. Those patients in whom the decrease in A1AT was greater than 50 % of control values, they did not survive and deceased (673+71 ug/ml, approx 40%, n=3). The decrease was significantly greater in nondiabetic patients as compared to diabetics. A1AT after an MI attack was comparable in hypertensive and non-hypertensive and in STEMI and Non-STEMI patients. Conclusion: A1AT seem to be important in providing some protection to myocardial cells during an MI attack. A1AT levels seem to drop following an MI attack. The drop is larger in nondiabetic as compared to diabetics. In those patients in whom the level of A1AT drops to more than 50 % of normal values they are less likely to survive the MI attack. More studies are needed to confirm the above findings. Disclosure S.Y. Khatib: None. Funding King Fahad Medical City Research Center (016-2018)

Platelet and Leukocyte Concentration in Equine Autologous Conditioned Plasma Are Inversely Distributed by Layer and Are Not Affected by Centrifugation Rate

Background: Platelet rich plasma (PRP) is used extensively in equine regenerative medicine. Differences in preparation protocols give rise to significant variability in the cellular composition of PRP making it very difficult to establish a standard of care in the field. This study aimed to optimize the preparation protocol for leukocyte-reduced PRP (P-PRP).Methods: Blood (100 mL) was collected from horses (n = 5) and divided into 2 purple top EDTA tubes and 6 (15 mL) double syringesa with a final concentration of 10% acid citrate dextrose anticoagulant. Six double syringesa were collected from each horse; PRP samples were prepared in duplicate and centrifuged at 1,100 rpm (188 × g), 1,300 rpm (263 × g), or 1,500 rpm (350 × g). Duplicates were subjected to +/– braking at the end of centrifugation. The total volume of PRP generated was measured and divided into thirds. Each third (top, middle, and bottom) were drawn off separately using the inner (6 mL syringe) and placed in purple top EDTA tubes. Automated complete blood counts were performed on all peripheral whole blood and PRP samples.Results: The concentration of leukocytes was higher in the bottom layer of PRP compared to the top and middle layers (p < 0.0001). The concentration of platelets was slightly lower in the bottom layer of PRP than the middle layer (p = 0.02). Centrifugation braking increased the leukocyte concentration in the top (p = 0.03) and middle layers of PRP (p = 0.001). Centrifugation rate had no effect on the cellular composition of PRP (p = 0.1–0.6).Conclusions: Because layer of plasma affected both platelet and leukocyte concentrations in PRP, the most important modification for the current single spin, double syringe, plasma based PRP preparation protocols is to exclude the bottom 1/3 layer of PRP.

Blood level of alpha‐1 antitrypsin in the course of acute myocardial infarction patients: A possible clinical significance

IntroductionWide experimental evidence has proved Alpha 1 antitrypsin, which is released from the liver, to protect lung tissue from damage during inflammation. There is experimental evidence also suggests such protection is extended to myocardial tissues during myocardial ischemia/infarction.ObjectiveThe aim of the study was to determine the levels and the time course of A1AT in the plasma of myocardial infarction patients over 96 hours and compare it with healthy subject as control.MethodsBlood samples were collected from patients (n=40) arriving at emergency department at 1, 4, 24, 48 and 96 hrs after diagnosis and admission to King Salman Cardiac Center, in King Fahad Medical City in Riyadh, Saudi Arabia. Blood samples were collected in purple top tubes containing EDTA to prevent blood coagulation. Blood plasma was separated by centrifugation with in 3 hrs of collection. Plasma was decanted and stored until analyzed. Alpha 1 antitrypsin was determined in all patients’ blood samples using human Eliza kits( abcam USA). In addition control blood samples were collected from 20 healthy individuals.ResultsA1AT levels were significantly less in MI patients (1025±77 ug/ml at 96 hrs, P&lt;001) compared to (1655±128 ug/ml) (mean ± SEM) in controls. It was very interesting to find those patients win whom the decrease in A1AT was &gt;50 % of control values, they did not survive and passed away (deceased) (673+71 ug/ml, n=3). Also the levels of A1AT after an MI attack was comparable and not significant in hypertensive compared to non‐hypertensive or in STEMI and Non‐STEMI patients but was significantly (P&lt;0.03) higher in non‐smokers (1457+163, n=27) compared to smokers (1153±155, n=10).ConclusionThe plasma level of A1AT is suggested to be important in providing some protection to myocardial cells during an MI attack. A1AT levels seem to drop shortly following an MI attack. The drop in the level is larger in smokers. In those patients in whom the level of A1AT drops to more about 50 % of normal values they are less likely to survive the MI attack. More studies are needed to confirm the above findings.Support or Funding InformationWe acknowledge the financial support from the research center at King Fahad Medical City, Riyadh, Saudi ArabiaFigure 1Figure 2

Influence of sodium chlorate, ferulic acid, and essential oils on Escherichia coli and porcine fecal microbiota.

The influence of sodium chlorate (SC), ferulic acid (FA), and essential oils (EO) was examined on the survivability of two porcine diarrhetic enterotoxigenic Escherichia coli (ETEC) strains (F18 and K88) and populations of porcine fecal bacteria. Fecal bacterial populations were examined by denaturing gradient gel electrophoresis (DGGE) and identification by 16S gene sequencing. The treatments were control (no additives), 10 mM SC, 2.5 mg FA /mL, a 1.5% vol/vol solution of an EO mixture as well as mixtures of EO + SC, EO + FA, and FA + SC at each of the aforementioned concentrations. EO were a commercial blend of oregano oil and cinnamon oil with water and citric acid. Freshly collected porcine feces in half-strength Mueller Hinton broth was inoculated with E. coli F18 (Trial 1) or E. coli K88 (Trial 2). The fecal-E. coli suspensions were transferred to crimp top tubes preloaded with the treatment compounds. Quantitative enumeration was at 0, 6, and 24 h. All treatments reduced (P < 0.05) the counts of E. coli F18 at 6 and 24 h. With the exception of similarity coefficient (%SC), all the other treatments reduced (P < 0.05) the K88 counts at 24 h. The most effective treatments to reduce the F18 and K88 CFU numbers were those containing EO. Results of DGGE revealed that Dice percentage similarity coefficients (%SC) of bacterial profiles among treatment groups varied from 81.3% to 100%SC. The results of gene sequencing showed that, except for SC at 24 h, all the other treatments reduced the counts of the family Enterobacteriaceae, while Lactobacillaceae and Ruminococcaceae increased and Clostridiaceae decreased in all treatments. In conclusion, all treatments were effective in reducing the ETEC, but EO mixture was the most effective. The porcine microbial communities may be influenced by the studied treatments.

Liquid Film Thickness around Taylor Finger

Taylor finger is characterized by single elongated air bubble which grows upward during the drainage of liquid from closed top vertical tubes. The characteristics of Taylor finger is similar to the Taylor bubble commonly observed in gas- liquid two phase flow. During the upward growth of Taylor finger, liquid from tube drains as a thin film around the Taylor finger. Exact prediction of film thickness is important in several engineering design and process calculations such as design of contacting devices, two phase flow through porous media, boiling in tubes and monolith reactors. Present study proposes the experimental technique to estimate the thickness of draining liquid film. Based on experiments an empirical model has been proposed for non-dimensional film thickness. The proposed model agrees well with the experimental data and equation proposed in literatures.

Abstract LB-240: Immuno-genomic detection and prognostication of aggressive prostate cancer phenotypes by next-generation RNA sequencing

Abstract Prostate cancer (PC) is the most common non-cutaneous malignancy in men. The prediction of outcome based on multicore biopsy specimens is problematic, mainly due to tumor multifocality compounded by intratumoral heterogeneity. Since 1) cancer assays compare a patient’s profile to that of individuals unknown to have PC, and 2) baseline signatures of the diseased man are specific to his genome while those of the controls are specific to theirs, such intrinsic inter-individual genomic differences have impeded valid disease signature identification. Thus, methods that filter out inter-individual “noise” not related to the disease should enhance the identification of a robust prognostic PC signature. OBJECTIVE: Assess the ability of a novel immuno-genomics blood-based RNA expression assay for PC prognosis. The method, which uses a proprietary algorithm to interrogate CD2 and CD14 cells, is a real-time surveillance of gene expression changes consequent to PC that filters out intrinsic inter-individual genomic signatures not related to PC. We expect this Subtraction-Normalized Expression of Phagocytes (SNEP) approach to be valuable in making apt clinical decisions and stratifying patients with aggressive PC (need life-saving treatments) from those with indolent disease (safe for active surveillance). PATIENTS: Men were eligible for enrollment if they 1) were determined by their physician to have a risk profile that warrants a prostate biopsy (Pre-Biopsy blood draw), 2) had a biopsy &amp;gt;90 d prior to but &amp;lt;1 yr of study entry and scheduled for but have not undergone therapy post biopsy blood draw, and 3) are on active surveillance such that a biopsy will be done within the next year. METHODS: Peripheral blood samples (n = 713) were collected in purple top Vacutainer tubes. CD2 and CD14 cells were isolated 4 h later using Miltenyi’s MACS Microbeads and mRNA was extracted using the Qiagen’s miRNEasy Mini Kit. The raw (FASTQ) RNA-Seq data (Illumina) was trimmed (Trimmomatic), aligned (Bowtie2), and quantified (Express). Transcripts with quantifiable expression changes between samples from the two cell types were identified following differential expression analysis using a linear model and cell type as endpoints. This resulted in the final set of 10,643 transcripts with &amp;lt;10% False Discovery Rate (FDR) and &amp;gt;1.5 absolute fold change. RESULTS: We identified genomic signatures in biopsy-positive patients that are predictive of Gleason grade, Cores Positive (CP), Maximum Involvement (MI), and an Aggressiveness Index (AI - an aggregate of the 3 endpoints). The signature scores were significantly associated with GG (tau 0.427, p 1.3x10-25), CP (tau 0.275, p3.3x10-11), MI (tau 0.564, p 8.5x10-44), and AI (tau 0.517, p 7.2x10-37). Interestingly, 1) certain transcripts were found to be specific to each endpoint (108 for GG, 88 for CP, 93 for MI, and 102 for AI), 2) some pairwise overlap was seen - highlighting the complementary of the three endpoints, and 3) no overall overlap was detected between all four endpoints. CONCLUSION: The multiple genomic signatures identified from CD2/CD14 RNA expression ratios - per SNEP assay - gives a prognostic summary that is comparable to prostate biopsy information including tumor grade, size/volume, and heterogeneity, and leads to the development of an aggressiveness signature that if validated will affect patient care decisions. Citation Format: Amin I. Kassis, Ricardo Henao, Kirk J. Wojno, Geffrey Erickson, Harry Stylli, Philip W. Kantoff. Immuno-genomic detection and prognostication of aggressive prostate cancer phenotypes by next-generation RNA sequencing [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-240.

Effect of time and temperature on stability of progestagens, testosterone and cortisol in Asian elephant blood stored with and without anticoagulant.

The value of biological samples collected in the field is compromised if storage conditions result in analyte degradation, especially in warmer climates like Thailand. We evaluated the effects of time and temperature on immunoactive steroid hormone stability in Asian elephant (Elephas maximus) blood stored with and without an anti-coagulant before centrifugation. For each elephant (5 male, 5 female), whole blood was aliquoted (n = 2ml each) into 13 red top (without anticoagulant) or purple top (with anticoagulant) tubes. One tube from each treatment was centrifuged immediately and the serum or plasma frozen at -20°C (Time 0, T0). The remaining 12 aliquots were divided into stored temperature groups: 4°C, room temperature (RT, ~22°C), and 37°C, and centrifuged after 6, 24, 48 and 62h of storage. Serum and plasma concentrations of progestagens in females, testosterone in males and cortisol in both sexes were quantified by validated enzyme immunoassays. Steroid concentration differences from T0 were determined by a randomized complete block ANOVA and Dunnett's tests. The only evidence of hormone degradation was cortisol and testosterone concentrations in serum stored at 37°C. Testosterone concentrations declined by 34% at 48h and 52% at 62h, cortisol was decreased by 19% after 48h and 27% after 62h at 37°C, respectively. None of the other aliquots displayed significant changes over time at any temperature. In conclusion, steroids appear to be stable in blood for nearly 3days at room or refrigeration temperatures before centrifugation; steroids in samples with ethylenediaminetetraacetic acid were particularly stable. However, warmer temperatures may negatively affect steroids stored without anti-coagulant, perhaps due to red blood cell metabolism. Thus, under field conditions with no access to cold or freezer temperatures, collection of plasma is a better choice for elephants up to at least 62h before centrifugation.

157. Reducing Blood Culture Contamination Rates Through the Use of a Red Top Tube Discard

BackgroundSepticemia is a major cause of death in the United States and accounts for up to $16.7 billion in annual health care expenses. Blood culture is the gold standard for laboratory diagnosis of bacteremia and resultant septicemia; however, false-positive blood cultures hinder the accurate determination of true bacteremia with often serious implications. The goal of this study was to determine the efficacy of collecting a 1 mL discard in a red tube prior to blood culture collection and to assess its effectiveness in reducing contamination rates in Hartford Hospital Emergency Department (HHED).MethodsDuring the months of June to December 2017 blood cultures were collected by the phlebotomy team using ChloraPrep (chlorhexidine) as the sole disinfecting agent. Blood cultures consisted of BD BACTEC plus Aerobic/F and BD BACTEC Lytic/10 Anaerobic drawn at the same time and monitored on BD BACTEC FX instrument for 5 days. Prior to collecting blood cultures 1 mL of blood was collected in a red top tube and discarded. Monthly and overall contamination rates were then compared with 2016 in which a red top discard tube was not used.ResultsDuring June to December 2016, there were a total of 9,576 blood cultures collected with a total of 178 contaminants and an overall contamination rate of 1.9%. During June to December 2017, there were a total of 9,133 blood cultures collected with a total of 73 contaminants and an overall contamination rate of 0.8%. During both years, our contamination rates were well below the CLSI recommendation; however, a significant reduction in blood culture contamination was observed after the use of a Red Top discard tube (0.8% vs. 1.9%) (Figures 1–3). ConclusionThe cost of a standard blood draw with Red Top tubes is minimal (few cents) while a single collection using an initial specimen diversion device (ISDD) can range from $15 to $18. During the course of this study, the use of a standard Red Top discard cost approximately $456 (2017); if an ISDD was used instead, this would have generated $136,995 in healthcare cost. At our institution, we were able to keep our contamination rates below 1% after the implementation of a standard Red Top discard tube. This suggests that the use of a Red Top discard prior to blood culture collection is an effective means for reducing and maintaining a low blood contamination rate.Disclosures All authors: No reported disclosures.

Draining phenomenon in closed narrow tubes pierced at the top: an experimental and theoretical analysis

The phenomenon of draining, although ubiquitous in nature, has received scant attention especially in the meso-scale. We observe that closed top tubes drain by the inception of an axisymmetric ‘Taylor finger’ while a minute pierce of the top closure results in an altogether different physics with air entry from the top pushing the liquid out. Again, a coupled mechanism comprising full bore followed by film draining is observed for “too small” a top pierce at “high enough” Eotvos number. Top pierce initiates draining in dimensions which would not drain otherwise and finger entry hastens the process of draining. The myriad of phenomena thus exhibited is depicted as phase diagrams in vertical and inclined conduits. A mechanistic model has been proposed to predict draining and the onset of finger entry in vertical tubes.

Haemoglobin Profiles of University Students Participating in Routine Medical Examinations, 2009-2011

Introduction: Haemoglobin estimation is one of the most frequently investigated laboratory tests as it is the primary predictor of anaemia. Anaemia is a major public health concern in places all around the world as it is known to adversely impact energy levels. Aims and objectives of this study were to evaluate the prevalence of anaemia based on haemoglobin measurement among University students who participated in routine medical examinations 2009- 2011. Method: Two hundred and seventy-two cases were included in a convenient sampling. Blood was collected in the standard K3EDTA purple top tubes. Samples were thoroughly mixed and haemoglobin estimation was done using the HemoQue Haemoglobin System. Commercial controls were run with each batch. Results: Commercial controls results showed 1.1559 % coefficient of variation. Mean age and haemoglobin concentration of all students were 23.011 ± 2.919 years (range 17-36), and 13.209 ± 1.356 g/dl (range 7.6 - 19.7), respectively. The mean haemoglobin for males and females was 14.19 and 12.51 respectively, t = 9.297(p =0.0001) Anaemia prevalence was lower in males than females (19.4%; n = 113 vs 32.7%; n = 159 respectively. Conclusions: The anaemia prevalence is higher in female than in males, approximately almost twice as high. At the institution where the study was conducted, emphasis is placed on quality nutrition, a likely factor in stemming the prevalence of the more common dietary related anaemias. Nevertheless, more laboratory evaluations will be needed to determine the specific cause of anaemia in the student population whose haemoglobin falls below the WHO age and gender specific cut off points.

Theory and Design of Counter Flow Shell-and-Coil Heat Exchanger for CO2Based Solar Water Heater

A shell type helical tube countercurrent flow heat exchanger was designed, fabricated and tested using CO2 refrigerant material. Helical copper tube was immersed in bulk water tank. Hot CO2 was piped to upper coil baffle and cold CO2 was circulated into collector loop through lower baffle. Cold water was made to enter through lower tap and hot water was taken out from upper tap. Both in/out pipes were inserted from the top and coil tubes from upper and lower sides of water tank. Supercritical thermosyphon operation was achieved by evacuated glass tube solar heat collector using CO2 refrigerant. U shaped copper pipes enveloped in aluminum foil were inserted in evacuated glass tubes to transfer heat under thermosiphon principle to upper header connected to inlet baffle of shell type helical coil heat exchanger. Lower header was connected to heat exchanger helical coil outlet baffle. Solar collector heat raised CO2 refrigerant temperature from 35 to 78C giving temperature difference of 43C. Temperature of CO2 refrigerant at exit from heat exchanger was found to be 40C at surrounding ambient temperature of 36C. Heat exchanger raised the inlet water temperature from 26 to 55C under off water tap condition in about 3 hours. Inlet and outlet temperature difference of heat exchanger was measured to be 27C. We believe system efficiency can further increase if we use the system in mild sunshine cold weather regions duplicating geothermal loop.

Comparison and generalization of R410A and R134a distribution in the microchannel heat exchanger with the vertical header

This article presents the experimental results of R410A and R134a distribution in the vertical header of a reversible outdoor microchannel heat exchanger. Two-phase refrigerant enters into the test header through multiple parallel microchannel tubes in the bottom pass and exits through multiple parallel microchannel tubes in the top pass, representing the flow in the outdoor microchannel heat exchanger of a reversible system under heat pump mode. The difference in fluid properties between R410A and R134a causes the difference in flow patterns and refrigerant distribution results. Non-dimensional analysis shows that the inertia of R410A is higher than that of R134a, with the following results: (1) at low qualities (churn flow), more liquid R410A reaches the top tubes, so R410A distribution is a little better than R134a; (2) at high qualities (semi-annular flow), more bottom tubes are bypassed by the liquid film of R410A, so R410A distribution is worse than R134a, even though more liquid reaches the top tubes for R410A. The distribution results of R410A and R134a are generalized with coefficient of variation, flow regime map, and a distribution function.

Experimental observation of the collision of three vortex rings

We investigate for the first time the motion, interaction and simultaneous collision between three initially stable vortex rings arranged symmetrically, making an angle of 120 degrees between their straight path lines. We report results with laminar vortex rings in air and water obtained through measurements of the ring velocity field with a hot-wire anemometer, both in free flight and during the entire collision. In the air experiment, our flow visualizations allowed us to identify two main collision stages. A first ring-dominated stage where the rings slowdown progressively, increasing their diameter rapidly, followed by secondary vortex structures resulting after the rings make contact. Local portions of the vortex tubes of opposite circulation are coupled together thus creating local arm-like vortex structures moving radially in outward directions, rapidly dissipating kinetic energy. From a similar water experiment, we provide detailed shadowgraph visualizations of both the ring bubble and the full size collision, showing clearly the final expanding vortex structure. It is accurately resolved that the physical contact between vortex ring tubes gives rise to three symmetric expanding vortex arms but also the vortex reconnection of the top and lower vortex tubes. The central collision zone was found to have the lowest kinetic energy during the entire collision and therefore it can be identified as a safe zone. The preserved collision symmetries leading to the weak kinematic activity in the safe zone is the first step into the development of an intermittent hydrodynamic trap for small and lightweight particles.

Suitability of Becton Dickinson Vacutainer rapid serum tube for collecting and storing blood samples for antibiotic and anticonvulsant drug monitoring

AimsTo investigate the suitability of newly developed Becton Dickinson Vacutainer rapid serum tube (RST) for therapeutic drug monitoring of antibiotics and anticonvulsants.MethodsTwo pools of citrated whole blood were created by...

Pilot study to assess effects of collection tube types and processing delay on measurements of persistent organic pollutants and lipids in human serum

Glass red top tubes (RTs), traditionally used to draw blood for biomonitoring studies, have some limitations during field sampling (e.g., tube breakage, timely processing may be difficult). This pilot study examined whether serum separation tubes (SSTs) with delayed processing time (48h) can be used instead of red top tubes (RTs) to accommodate field conditions. Using state-of-the-art methodologies, PBDEs, PCBs, OCPs, PFCs, cholesterol and triglycerides were measured to evaluate any differences among 2 test conditions (RTs with 2h processing time; SSTs with 48h processing time). Between the 2 test conditions, we observed high rank correlations among the measured compounds and no statistically significant differences in the levels of measured compounds. We conclude that SSTs with delayed processing time (48h) produce similar results as RTs with short processing time (2h), suggesting that SSTs could be good substitutes for RTs for new epidemiological and biomonitoring field studies. The use of SSTs offers a tremendous opportunity for the use of samples archived in various SSTs.

Out-of-plane elastic buckling behavior of hinged planar truss arch with lateral bracings

This paper is concerned with the out-of-plane elastic buckling behavior of planar truss arch with continuous or discrete lateral bracings. Firstly, planar truss arches with continuous lateral bracings are studied, and a closed form solution of out-of-plane elastic buckling load is obtained theoretically. As for planar truss arches laterally restrained with discrete bracings, two key parameters, namely lateral bracing threshold stiffness and out-of-plane elastic buckling load of an arch segment between two adjacent bracings, are investigated by the finite element method, respectively. Besides, it is found from finite element results that, if the planar truss arch is manufactured by using intersecting joints between web members and chord tubes and is laterally restrained on top chord tubes, the out-of-plane buckling of bottom chord tubes will fully be prohibited. However, the gusset-plate connections between chord tubes and web members cannot prevent the planar truss arch from the out-of-plane buckling due to their weak stiffness, even though the arch is laterally fully restrained on top chord tubes.

Commensalism in an agroecosystem: hydraulic redistribution by deep‐rooted legumes improves survival of a droughted shallow‐rooted legume companion

We investigated commensalism of water use among annual shallow-rooted and perennial deep-rooted pasture legumes by examining the effect of hydraulic lift by Cullen pallidum (N.T.Burb.) J.W.Grimes and Medicago sativa on growth, survival and nutrient uptake of Trifolium subterraneum L. A vertically split-root design allowed separate control of soil water in top and bottom soil. Thirty-five days after watering ceased in the top tube, but soil remained at field capacity in the bottom tube, an increase in shallow soil water content by hydraulic lift was 5.6 and 5.9 g kg(-1) soil overnight for C. pallidum and M. sativa, respectively. Trifolium subterraneum in this treatment maintained higher leaf water potentials (with M. sativa) or exhibited a slower decline (with C. pallidum) than without companion perennial plants; and shoot biomass of T. subterraneum was 56% (with C. pallidum) and 67% (with M. sativa) of that when both top and bottom tubes were at field capacity. Uptake of rubidium (a potassium analog) and phosphorus by T. subterraneum was not facilitated by hydraulic lift. Interestingly, phosphorus content was threefold greater, and shoot biomass 1.5-3.3-fold greater when T. subterraneum was interplanted with C. pallidum compared with M. sativa, although dry weight of C. pallidum was much greater than that of M. sativa. This study showed that interplanting with deep-rooted perennial legumes has benefited the survival of T. subterraneum.

Accuracy of HOMA-IR in Clinical Practice

Purpose: Insulin resistance (IR) is closely associated with NASH and cardiovascular mortality in the general population. There is also data suggesting that patients with hepatitis C and IR have lower response rates to the treatment with Pegylated Interferon and Ribavirin. HOMA-IR (Homeostasis Model Assessment of Insulin Resistance) is an attractive screening tool for insulin resistance in clinical practice. The formula includes fasting insulin (mU/L) multiplied by fasting glucose (mg/dL) then divided by 405. Values of HOMA-IR> 2 are strongly correlating with the presence of IR. This observational study evaluates the accuracy of HOMA-IR in our hospital clinical lab. Methods: 32 subjects with high risk for IR were screened with OGTT and HOMA-IR for a diet and exercise study. Blood was drawn after 12 hours overnight fast and was sent to the main hospital clinical lab for measurement of insulin and glucose (speckled top tube). At the same time plasma was immediately centrifuged and glucose was measured in real time using Glucose Analyzer (Beckman, CA). The rest of separated plasma was stored at −70°C until later analysis in our obesity research clinical lab (ORC). HOMA-IR was calculated using same lab values and the results were split in two groups: the ORC data and the clinical lab data. Results: The clinical lab data identified only 14 (43.75%) subjects with HOMA> 2 compared with the ORC lab data, which had 28 (87.5%). The range of HOMA-IR measured by clinical lab was 0.34-6.19 (mean=2.32) and that measured by ORC lab was 1.38-10.92 (mean=5.09). The average difference between insulin and glucose values of the two groups was 8.44 mU/L and 20.56 mg/dL respectively. Five subjects had fasting glucose levels over 120 mg/dL in the ORC lab data compared with none over 106 mg/dL in the clinical lab data. If only clinical lab data had been used, 14 (50%) subjects would have been screened out for IR and new onset diabetes would have been missed in five subjects. Conclusion: Insulin and glucose degradation is likely the explanation for the observed differences between the two groups. Inaccuracies in the measurement of fasting insulin and glucose in clinical practice will likely underestimate HOMA-IR. There is data in literature suggesting that in a red top tube glucose concentration may decrease with 25% over 3 hours due to hemolysis. As a result, we conclude that only special gray top tubes (with Fluoride-Oxalate as anti-hemolytic) should be used for fasting glucose measurement. Also, standardized methods for insulin measurement should be developed (i.e. colect in lavender top tube with EDTA, refrigerate until processed and centrifuge sample as soon as possible) in order to prevent insulin degradation and increase the accuracy of the results.