Texas Tech University System

We report validation of the first isotope dilution mass spectrometry method for determination of aflatoxin B(1)-N(7)-guanine (AFB(1)-N(7)-Gua), a major human aflatoxin-DNA adduct that is excreted in the urine. Measurement of urinary AFB(1)-N(7)-Gua, a biomarker of the biologically effective dose following dietary aflatoxin B(1) (AFB(1)) exposure, has helped identify AFB(1) as a risk factor in the development of hepatocellular carcinoma, a common cancer worldwide. Triple-quadrupole mass spectrometry, coupled with the use of a stable isotope-labeled internal standard (AFB(1)-N(7)-(15)N(5)-Gua) and better solid phase extraction and immunoaffinity column chromatography, have enabled us to greatly improve accuracy, precision, specificity, and sensitivity over previously published determinations. The limit of quantitation for AFB(1)-N(7)-Gua was 0.8 pg/20 mL urine (0.07 pg/mg creatinine). The method was validated for accuracy and precision over the range of 0.8-25 pg/20 mL urine, with between-day and within-day reproducibility for analysis of six aliquots of a human urine sample containing 6.0 pg/20 mL measured at <6% coefficient of variation. AFB(1)-N(7)-Gua concentrations were measured in 20 human urine samples collected in a region with known aflatoxin exposure. The mean concentration of AFB(1)-N(7)-Gua, measured in 16/20 urine samples with levels above the method's limit of quantitation, was 2.9 pg/20 mL urine (0.28 pg/mg creatinine) with a range of <0.8-7.2 pg/20 mL urine (0.04-65 pg/mg creatinine). With improved accuracy and precision, this sensitive biomarker for recent human exposure to AFB(1) will be especially useful for measuring the efficacy of planned interventions to reduce aflatoxin-related liver cancer in AFB(1)-exposed populations.

For the past 30 years, data have suggested that unique islet populations exist, based on morphology and glucose sensitivity. Yet little has been done to determine the mechanism of these functional differences. The purpose of this study was to determine whether human islets were comprised functionally unique populations, and to elucidate a possible mechanism. Islets or pancreatic sections from 29 human donors were analyzed. Islets were isolated and measured for insulin secretion, cell composition and organization, insulin and glucagon granule density and insulin content. Insulin secretion was significantly greater in small compared with large islets. In sectioned human pancreata, β-cells comprised a higher proportion of the total endocrine cells in small islets (63%) than large islets (39%). A higher percentage of β-cells in small islets contacted blood vessels (44%) compared with large islets (31%). Total insulin content of isolated human islets was significantly greater in the small (1323 ± 512 μIU/IE) compared with large islets (126 ± 48 μIU/IE). There was less immunostaining for insulin in the large islets from human pancreatic sections, especially in the core of the islet, compared with small islets. The results suggest that differences in insulin secretion between large and small islets may be due to a higher percentage of β-cells in small islets with more β-cells in contact with blood vessels and a higher concentration of insulin/β-cell in small islets.

Bulked segregant analysis was used to identify simple sequence repeat (SSR) markers associated with pod and kernel traits in cultivated peanut, to permit rapid selection of superior quality genotypes in the breeding program. SSR markers linked to pod and kernel traits were identified in two DNA pools (high and low), which were established using selected F2:6 recombinant individuals resulting from a cultivated cross between a runner (Tamrun OL01) and a Spanish (BSS 56) peanut. To identify quantitative trait loci (QTLs) for pod and kernel-related traits, parents were screened initially with 112 SSR primer pairs. The survey revealed 8.9% polymorphism between parents. Of ten SSR primer pairs distinguishing the parents, five (PM375, PM36, PM45, pPGPseq8D9, and Ah-041) were associated with differences between bulks for seed length, pod length, number of pods per plant, 100-seed weight, maturity, or oil content. Association was confirmed by analysis of segregation among 88 F2:6 individuals in the RIL population. Phenotypic means associated with markers for three traits differed by more than 40%, indicating the presence of QTLs with major effects for number of pods per plant, plant weight, and pod maturity. The SSR markers can be used for marker assisted selection for quality and yield improvement in peanut. To the best of our knowledge, this is the first report on the identification of SSR markers linked to pod - and kernel- related traits in cultivated peanut.

When working with isolated islet preparations, measuring the volume of tissue is not a trivial matter. Islets come in a large range of sizes and are often contaminated with exocrine tissue. Many factors complicate the procedure, and yet knowledge of the islet volume is essential for predicting the success of an islet transplant or comparing experimental groups in the laboratory. In 1990, Ricordi presented the islet equivalency (IEQ), defined as one IEQ equaling a single spherical islet of 150 μm in diameter. The method for estimating IEQ was developed by visualizing islets in a microscope, estimating their diameter in 50 μm categories and calculating a total volume for the preparation. Shortly after its introduction, the IEQ was adopted as the standard method for islet volume measurements. It has helped to advance research in the field by providing a useful tool improving the reproducibility of islet research and eventually the success of clinical islet transplants. However, the accuracy of the IEQ method has been questioned for years and many alternatives have been proposed, but none have been able to replace the widespread use of the IEQ. This article reviews the history of the IEQ, and discusses the benefits and failings of the measurement. A thorough evaluation of alternatives for estimating islet volume is provided along with the steps needed to uniformly move to an improved method of islet volume estimation. The lessons learned from islet researchers may serve as a guide for other fields of regenerative medicine as cell clusters become a more attractive therapeutic option.

A key feature of a robust academic discipline is that its homegrown theories and investing in theory contribute to building good research. In the field of sport and social media research, the rigorous utilization of theory is one of the areas where the field is still facing “disciplinary pain.” In fact, the unique features of social media provide researchers in the sport research community with a valuable opportunity for proposing, testing, applying, critiquing, comparing, integrating, and expanding theories. In this commentary, the authors, based on their own experience (as researchers, readers, and reviewers of social media in sport), contend that reference resources are lacking on this topic to help young (or existing) researchers locate appropriate theories for their research. Hence, this work identifies, documents, and discusses the theories used, advanced, and developed in social media research for sport studies. Furthermore, a compilation is brought together of different theories from various disciplines that researchers in this community may consider for their future work.

BACKGROUND: During the COVID-19 pandemic, decreased volumes of stroke admissions and mechanical thrombectomy were reported. The study's objective was to examine whether subarachnoid haemorrhage (SAH) hospitalisations and ruptured aneurysm coiling interventions demonstrated similar declines. METHODS: We conducted a cross-sectional, retrospective, observational study across 6 continents, 37 countries and 140 comprehensive stroke centres. Patients with the diagnosis of SAH, aneurysmal SAH, ruptured aneurysm coiling interventions and COVID-19 were identified by prospective aneurysm databases or by International Classification of Diseases, 10th Revision, codes. The 3-month cumulative volume, monthly volumes for SAH hospitalisations and ruptured aneurysm coiling procedures were compared for the period before (1 year and immediately before) and during the pandemic, defined as 1 March-31 May 2020. The prior 1-year control period (1 March-31 May 2019) was obtained to account for seasonal variation. FINDINGS: There was a significant decline in SAH hospitalisations, with 2044 admissions in the 3 months immediately before and 1585 admissions during the pandemic, representing a relative decline of 22.5% (95% CI -24.3% to -20.7%, p<0.0001). Embolisation of ruptured aneurysms declined with 1170-1035 procedures, respectively, representing an 11.5% (95%CI -13.5% to -9.8%, p=0.002) relative drop. Subgroup analysis was noted for aneurysmal SAH hospitalisation decline from 834 to 626 hospitalisations, a 24.9% relative decline (95% CI -28.0% to -22.1%, p<0.0001). A relative increase in ruptured aneurysm coiling was noted in low coiling volume hospitals of 41.1% (95% CI 32.3% to 50.6%, p=0.008) despite a decrease in SAH admissions in this tertile. INTERPRETATION: There was a relative decrease in the volume of SAH hospitalisations, aneurysmal SAH hospitalisations and ruptured aneurysm embolisations during the COVID-19 pandemic. These findings in SAH are consistent with a decrease in other emergencies, such as stroke and myocardial infarction.

A medium-power, highly-efficient broadband linear power amplifier (PA) is designed in a 40-nm GaN technology that covers the key 5G FR2 band of 24-40 GHz. Load-pull simulations suggest better device broadband performance and peak power-added-efficiency (PAE) around V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> = 4-6 V. Measurement data corroborates the simulations and this PA achieves a small-signal 3-dB bandwidth (BW) of 18.0-40.3 GHz, with max. PAE/P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SAT</sub> of 42.1%/18.6 dBm at 28 GHz, and 26.0%/17.2 dBm at 38 GHz at V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> = 4 V. When tested with a 9 MHz × 100 MHz 256-quadratic-amplitude modulation (QAM) 5G new radio (NR) signal, it achieves an adjacent-channel-leakage-ratio (ACLR) of -27 dBc with P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OUT, AVG</sub> /PAE of 11.3 dBm/13.9% at 28 GHz. When compared with state-of-the-art broadband PAs, it achieves the best S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> 3-dB BW with excellent peak PAE and linearity. This work also reports the best PAE for broadband medium-power millimeter-wave GaN PA at P <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SAT</sub> ~ 20 dBm.

Mouse monoclonal antibodies were developed against a synthetic aflatoxin B(1) (AFB)-lysine-cationized bovine serum albumin conjugate. The isotype of one of these antibodies, IIA4B3, has been classified as immunoglobulin G1(lambda). The affinity and specificity of IIA4B3 were further characterized by a competitive radioimmunoassay. The affinities of IIA4B3 for AFB and its associated adducts and metabolites are ranked as follows: AFB-lysine > 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl formamido)-9-hydroxy-AFB > AFB = 8,9-dihydro-8-(N(7)-guanyl)-9-hydroxy-AFB > aflatoxin M(1) > aflatoxin Q(1). IIA4B3 had about a 10-fold higher affinity for binding to AFB-lysine adduct than to AFB when (3)H-AFB-lysine was used as the tracer. The concentration for 50% inhibition for AFB-lysine was 0.610 pmol; that for AFB was 6.85 pmol. IIA4B3 had affinities at least sevenfold and twofold higher than those of 2B11, a previously developed antibody against parent AFB, for the major aflatoxin-DNA adducts 8,9-dihydro-8-(N(7)-guanyl)-9-hydroxy-AFB and 8,9-dihydro-8-(2,6-diamino-4-oxo-3,4-dihydropyrimid-5-yl formamido)-9-hydroxy-AFB, respectively. An analytical method based on a competitive radioimmunoassay with IIA4B3 and (3)H-AFB-lysine was validated with a limit of detection of 10 fmol of AFB-lysine adduct. The method has been applied to the measurement of AFB-albumin adduct levels in human serum samples collected from the residents of areas at high risk for liver cancer.

OBJECTIVE: To describe how skepticism about medical care and other individual differences, including worry about health status, are associated with evaluations of health care among the noninstitutionalized elderly. DATA SOURCES/STUDY SETTING: Data were collected through a survey of approximately 5,000 community-dwelling elders (aged 65 and older) in a southwestern region of the United States. STUDY DESIGN: Global evaluations of health care were measured with two items from the Consumer Assessment of Health Plans Study (CAHPS) instrument, an overall care rating (OCR) and a personal doctor rating (PDR). Multivariate ordered logit regression models were tested to examine how medical skepticism and other factors were associated with ratings of 0-7, 8-9, and 10. PRINCIPAL FINDINGS: Consumers who were skeptical of prescription drugs relative to home remedies, who held attitudes that they understand their health better than most doctors, and who worried about their health had worse OCR and PDR. Those who held attitudes that individual behavior determines how soon one gets better when sick had better PDR and OCR. CONCLUSIONS: Health policymakers, managers, and providers may need to consider the degree to which they should attempt to satisfy skeptical consumers, many of whom may never rate their care highly. Alternatively, they may need to target skeptical consumers with educational efforts explaining the benefits of medical care.

Human islets come in a variety of sizes and shapes, and the total volume of islets used for research or clinical transplants must be estimated in a manner that is simple and valid. Islet equivalent (IEQ) measurements are the standard estimate of islet volume. We published a new method (the Kansas method) for estimating rat islet volume using cell numbers that was reliable and valid. Here we modified the method for human islets. We measured the dimensions of isolated human islets showing that they are not spherical and became less so in larger islets, with an average smallest/largest diameter ratio of 0.73 in large islets and 0.85 in small islets. Human islets were individually loaded into 96-well plates, dissociated into single cells, and the total cell number per islet determined with computer-assisted cytometry. Based on the counted cell number per islet, a regression model was created to convert islet diameter to cell number with a high R(2) value (0.99). Separate regression equations for male and female donors or young and old donors were not significantly different than the pooled data and did not improve the regression values. There was an inverse correlation between the cell number per IEQ and islet size. The Kansas method was validated with ATP/cell and cell viability data. Compared to the actual cell count, conventional IEQ measurements overestimated tissue volume of large islets by nearly double. Examples of differences in results obtained from the same data sets normalized to IEQ or the Kansas method included viability and insulin secretion concentrations. The implications of the error associated with the current IEQ method of volume estimation are discussed.

Purpose As exploratory research, this project aimed to develop and assess the effect of implementing a food waste reduction program at a restaurant on a university campus. Design/methodology/approach Data collection consisted of an audit of both pre and postconsumer food waste to determine the effectiveness of various reduction strategies and a survey to assess attitudes of employees toward food waste. As exploratory research, a personalized database was created to track current food waste amounts and reasons for waste in the restaurant operation to determine if the same method could be employed in future research. Findings Overall, the restaurant in this study implemented various effective food waste reduction practices that were inexpensive and simple, resulting in a weekly average reduction of 14.3 pounds of food waste. The top five food item products wasted by the kitchen were also identified for both pre and postintervention phases as well as the reasons for generating kitchen waste. Furthermore, data reported on postconsumer waste included weight quantities and product types. Originality/value The project resulted in evidence that a personalized food tracking system is useful for identifying and quantifying food waste in foodservice operations. Therefore, the research design and data collection methods used in this project can be used in future research on a larger scale.

BACKGROUND: The School Wellness Policy (SWP) mandate marks one of the first innovative and extensive efforts of the US government to address the child obesity epidemic and the influence of the school environment on child health. However, no systematic review has been conducted to examine the implementation of the mandate. The study examines the literature on SWP implementation by using the Diffusion of Innovations Theory as a framework. METHODS: Empirically based literature on SWP was systematically searched and analyzed. A theory-driven approach was used to categorize the articles by 4 diffusion stages: restructuring/redefining, clarifying, routinizing, and multiple stages. RESULTS: Twenty-one studies were identified, and 3 key characteristics of the reviewed literature were captured: (1) uniformity in methodology, (2) role of context in analyzing policy implementation, and (3) lack of information related to policy clarification. Over half of the studies were published by duplicate set of authors, and only 1 study employed a pure qualitative methodology. Only 2 articles include an explicit theoretical framework to study theory-driven constructs related to SWP implementation. CONCLUSIONS: Policy implementation research can inform the policy process. Therefore, it is essential that policy implementation is measured accurately. Failing to clearly define implementation constructs may result in misguided conclusion.

Abstract Objective To develop a stress leak point pressure (LPP) test for dogs, determine LPP for continent female dogs, and determine urethral pressure profile (UPP) values for nonanesthetized, continent female dogs. Animals 22 continent female dogs weighing from 21 to 29 kg. Procedure A standard UPP test and a modification of the LPP test used in women were performed on all dogs. On 3 occasions, dogs underwent UPP testing while awake. They then were anesthetized with propofol, and LPP was measured at bladder volumes of 75. 100, and 150 ml. For LPP tests, abdominal pressure was applied by inflating a human blood pressure cuff placed around the dog’s abdomen. LPP were recorded through a urethral catheter (bladder LPP) and a rectal balloon catheter (abdominal LPP). Results Mean ± SD and median maximal urethral closure pressure was 110.1 ± 20.2 and 109.0 cm water, respectively. Mean bladder LPP for the 75, 100, and 150 ml bladder volumes was 172.4 cm water. Significant differences among LPP for the 3 bladder volumes were not detected. Conclusions Stress LPP can be recorded in female dogs. ( Am J Vet Res 1999;60:676–678)

, and excellent ability to align LC molecules. The high stability of the P-ECS film was confirmed from the very low variation of sheet resistance (2%) and transmittance (10%) observed during a bending test of 1000 cycles. In addition, a twisted nematic LC device constructed using the P-ECS films shows a good bright-dark switching performance. The P-ECS film functions simultaneously as a transparent electrode, a film-type polarizer, and a LC alignment layer, demonstrating the multi-functionality of the active CNT film. This study thus highlights a wide range of possible applications for active polarizers and flexible displays.

Objective: Increasing rural community college degree attainment is very important to foster rural areas’ economic and social well-being. Rural community colleges differ greatly from their suburban and urban counterparts in financial aid patterns and student bodies. However, existing literature is vacant with respect to student financial aid and degree attainment in rural community colleges. The objective of this study was to examine the relationship between financial aid and associate degree attainment for rural community college students and compare the financing patterns of the three locales. Method: Using data from Beginning Postsecondary Students Longitudinal Study (BPS:04/09), we performed a series of logistic regression models that include financial aid variables and control variables from psychological, sociological, organizational, and internationalist perspectives. Results: We found rural community college students exceeded other locales in degree attainment. Logistic regression results reveal insignificant roles of Pell Grants and Federal Subsidized Loans, and negative role of Federal Unsubsidized Loans in associate degree attainment for rural community college students. Contributions: The results suggest that public subsidies, such as Pell Grants, were not sufficient to cover rural students’ unmet need for financing degree attainment, and that rural students are more cost-conscious in borrowing and spending than their suburban and urban counterparts.

Using simulation modeling, our research is the first study to investigate impact of two different stockout compensation strategies (E-SC and S-SC) compared to no-stockout compensation strategy (N-SC) on supplier's profits and etailer's profits in e-commerce drop-shipping supply chain. The conceptual model is a two-echelon production-inventory system with a make-to-stock supplier and an etailer. The results from this study suggests that on average, the profit difference is less than 4.0 percent in E-SC compared to N-SC for both the supplier and etailer. However, when demand variability is high, production capacity is low and service level is low, the profit difference for both the supplier and etailer is significantly higher in E-SC compared to N-SC. Also, if both the supplier and etailer pursue S-SC strategy, then on average, an increase in wholesale price by around 1.0 percent compared to wholesale price in N-SC is sufficient to offset the stockout compensation cost for the supplier.

This study examines the role of multimodality in facilitating service-learning goals. We report findings from qualitative interviews with 20 college instructors who have designed and facilitated multimodal community-engaged learning projects, identifying their motivations, goals, and the impact of these projects through reflections. Based on our qualitative analysis of these instructor responses, we discuss the technological and pedagogical implications of multimodal social advocacy projects in technical and professional writing courses.

With the availability of more and more efficient and sophisticated Computational Fluid Dynamics (CFD) tools, engineering designs are also becoming more and more software driven. Yet, the insights in temporal and spatial scaling issues are still with us and very often imbedded in complexity and many design aspects. In this paper, with a revisit to a so-called leakage issue in sucker rod pumps prevalent in petroleum industries, the author would like to demonstrate the need to use perturbation approaches to circumvent the multi-scale challenges in CFD with extreme spatial aspect ratios and temporal scales. In this study, the gap size between the outer surface of the plunger and the inner surface of the barrel is measured with a mill (one thousandth of an inch) whereas the plunger axial length is measured with inches or even feet. The temporal scales, namely relaxation times, are estimated with both expansions in Bessel functions for the annulus flow region and expansions in Fourier series when such a narrow circular flow region is approximated with a rectangular one. These engineering insights derived from the perturbation approaches have been confirmed with the use of full-fledged CFD analyses with sophisticated computational tools as well as experimental measurements. With these confirmations, new perturbation studies on the sucker rod leakage issue with eccentricities have been presented. The volume flow rate or rather leakage due to the pressure difference is calculated as a quadratic function with respect to the eccentricity, which matches with the early prediction and publication with comprehensive CFD studies. In short, a healthy combination of ever more powerful modeling tools along with the physics, mathematics, and engineering insights with dimensionless numbers and classical perturbation approaches may provide a balanced and more flexible and efficient strategy in complex engineering designs with the consideration of parametric and phase spaces.

The aim of this study is to develop an inexpensive method for preparing transparent and heat insulating tin oxide film. Antimony-doped tin oxide (ATO) thin films have wide variety of technical applications, such as high transmission of visible light and heat insulated coatings. Films were formed by the dip-coating of this colloidal suspension. The structure and morphology of these films were analyzed using XRD and SEM analysis. The optical properties of the ATO thin films were investigated using a UV–VIS spectrophotometer. The heat insulating performance was evaluated using Halogen lamps to irradiate a film coated glass which cover on wooden box for two hours. The results of this study indicate that only the SnO phase (tetragonal rutile structure) appeared in X-ray diffraction, and the Sb dopant does not from a second phase. However, the crystallinity of the SnO structure is impaired by the presence of antimony. For the heat insulating performance the ATO coated glass achieves better heat insulation than that of bare glass.

The issues of leakage with respect to the clearance between the pump plunger outer surface and the pump barrel inner surface and other operational conditions have been revisited in this paper. Both Poiseuille flow rate due to the pressure difference and Couette flow rate due to the plunger motion have been considered. The purpose of this study is to explore the possibility of representing the entire downhole pump system with a simple viscoelastic model. We have explored both Kelvin and Maxwell viscoelastic models along with the dynamic behaviors of a mass point attached to the viscoelastic model. By using the time-dependent polished rod force measured with a dynamometer as the input to the viscoelastic models, we have obtained the displacement responses, which match closely with the actual measurements in experiments and operations. Further study and experiments have been planned and partially implemented in the McCoy School of Engineering at Midwestern State University, a member of the Texas Tech University System.