cssi/SciSciGPT-SciSciNet huggingface dataset:
Evaluation of 18F-Rho6G as a Novel PET Tracer for Myocardial Perfusion Imaging in a Swine Ischemia Reperfusion Model.

235 Objectives: Myocardial perfusion imaging is routinely used for assessment of relative blood flow in the detection of coronary artery disease and for risk-stratification. PET imaging offers intrinsic advantages in spatial resolution and sensitivity. However, currently available FDA approved PET perfusion agents have short half-lives requiring an on-site generator or cyclotron. We sought to evaluate a new perfusion agent based on an 18F-labeled rhodamine dye (18F-Rho6G) and to determine the myocardial extraction fraction and subsequent biodistribution in a swine ischemia-reperfusion model. Methods: 18F-Rho6G was produced as previously described1 with minor modification, in high specific activity (range 186-840 MBq/nmol) and high radiochemical purity (>90%). We first determined the in vivo first pass myocardial extraction fraction (FPMEF) of 18F-Rho6G in male Yorkshire swine (n=4) by intracoronary co-injection of 18F-Rho6G (8.14 ± 1.04 MBq) and 131I-albumin (0.296 ± 0.185) via a guide catheter placed in the left main coronary over 20 seconds, and simultaneous withdraw of serial 1 mL blood every 5 seconds for 2 minutes from a multipurpose catheter placed in the coronary sinus. To determine the FPMEF, the area under the activity curves for both tracers was calculated correcting for the ratio of injected activity, and counting efficiency of each isotope on the gamma counter. Following evaluation of FPMEF, one swine underwent a 90 min balloon occlusion and five days later underwent dynamic cardiac PET imaging on a Siemens Biograph mCT scanner to determine the biodistribution and clearance of the radiotracer under resting conditions over 60 minutes. The reconstructed cardiac PET images were merged with a contrast CT image for drawing of regions of interest (ROIs) using Carimas Version 2.9 (Turku, Finland). Results: The FPMEF of 18F-Rho6G was calculated at 79.4 ± 7.1 %. Under resting conditions, 18F-Rho6G demonstrated favorable cardiac imaging characteristics (Figure 1) with high uptake and retention in the myocardium, with a heart to blood ratio of 15.67, heart to liver ratio of 1.44, heart to lung ratio of 11.79, and heart to bone ratio of 1.33, all at 45-60 min post-injection. The uptake of the radiotracer was approximately 2.5 fold higher in the LV remote zone vs. the infarct territory at rest. Conclusions: 18F-Rho6G appears to be a highly promising 18F-labeled myocardial perfusion tracer with a high first pass myocardial extraction fraction and favorable heart to background tissue uptake patterns in a clinically relevant large animal model. Additional dynamic rest and stress 18F-Rho6G imaging studies are underway for determination of absolute flow in comparison to 15O-water and radioactive microspheres.
Optimal Jammer Placement in the Real Plane to Partition a Wireless Network

We consider the problem of jammer placement to partition a wireless network, where the network nodes and jammers are located in the real plane. In previous research, we found optimal and suboptimal jammer placements by reducing the search space for the jammers to the locations of the network nodes. In this paper, we develop techniques to find optimal jammer placements over all possible jammer placements in the real plane. Our approach finds a set of candidate jammer locations (CJLs) such that a jammer-placement solution using the CJLs achieves the minimum possible cardinality among all possible jammer placements in the real plane. The CJLs can be used directly with the optimal and fast, suboptimal algorithms for jammer placement from our previous work.
Defining cutoffs to diagnose obesity using the relative fat mass (RFM): Association with mortality in NHANES 1999-2014.

We have recently proposed and validated a simple and accurate method to estimate whole-body fat percentage in adults, the relative fat mass (RFM), derived from the ratio of height to waist circumference. We aimed to identify RFM cutoffs to diagnose obesity based on the association between RFM and all-cause mortality. We used data from adult participants (≥20 years of age, n = 43,793) of the National Health and Nutrition Examination Survey (NHANES) 1999–2014 linked with death certificate records from the National Death Index. Optimal RFM cutoffs were determined using receiver-operating characteristic analysis (the Youden’s index and the Euclidean minimum distance to the coordinate (0,1)). Final dataset for analyses comprised 31,008 adults. During a median follow-up of 8.3 years (IQR, 7.6–13.7), 2,517 deaths occurred. Youden and Euclidean optimal cutoffs of baseline RFM for all-cause mortality were 40.8% and 41.6% for women, and 30.9% and 28.9% for men, respectively. Similar cutoffs were obtained using measured whole-body fat percentage by dual energy X-ray absorptiometry. Adjusting for age, BMI category, ethnicity, education level, and smoking status, the hazard ratio for mortality using Cox proportional hazard regression was 1.41 (95% CI, 1.02–1.95) among women who had an RFM of 40.0–44.9% compared with women who had an RFM <35% (P = 0.035). Among men, the hazard ratio was 1.57 (95% CI, 1.07–2.30) among those with an RFM of 30.0–34.9% compared with men who had an RFM <25% (P = 0.020). Similar adjusted hazard ratios for same RFM categories were obtained in our validation population (NHANES III, n = 12,650, median follow-up: 23.3 years): 1.42 (95% CI, 1.01–2.00) among women (P = 0.043) and 1.50 (95% CI, 1.07–2.10) among men (P = 0.021). We suggest rounded RFM cutoffs of 40% for women and 30% for men to diagnose obesity and identify individuals at higher risk of death.
Corporate Market Investments: Risk, Returns, and Governance

This paper studies the risk associated with corporate market investments. For the years 1970 to 2011, market investment returns are shown to be risky and inefficient. The value-weighted average firm-level portfolio risk is 60%; the Sharpe ratio is merely 4.7%. Using a novel fiscal-year factor pricing approach, I show that the market beta for all firms is 27%. Portfolio cash-flow risk relative to assets is comparable to operating cash-flow risk, and market investment returns substitute for accounting manipulation. Moreover, market investment risk decreases with institutional ownership. The findings suggest that market investment risk is substantial and associated with agency costs.
Analysis of 83mKr prompt scintillation signals in the PIXeY detector

Prompt scintillation signals from 83mKr calibration sources are a useful metric to calibrate the spatial variation of light collection efficiency and electric field magnitude of a two phase liquid-gas xenon time projection chamber. Because 83mKr decays in two steps, there are two prompt scintillation pulses for each calibration event, denoted S1a and S1b. We study the ratio of S1b to S1a signal sizes in the Particle Identification in Xenon at Yale (PIXeY) experiment and its dependence on the time separation between the two signals (Δ t), notably its increase at low Δ t. In PIXeY data, the Δ t dependence of S1b/S1a is observed to exhibit two exponential components: one with a time constant of 0.05 ± 0.02 μ s, which can be attributed to processing effects and pulse overlap and one with a time constant of 10.2 ± 2.2 μs that increases in amplitude with electric drift field, the origin of which is not yet understood.
Trivalent sulfonium compounds (TSCs): Tetrahydrothiophene-based amphiphiles exhibit similar antimicrobial activity to analogous ammonium-based amphiphiles

Recent advances in the development of quaternary ammonium compounds (QACs) have focused on new structural motifs to increase bioactivity, but significantly less studied has been the change from ammonium- to sulfonium-based disinfectants. Herein, we report the synthesis of structurally analogous series of quaternary ammonium and trivalent sulfonium compounds (TSCs). The bioactivity profiles of these compounds generally mirror each other, and the antibacterial activity of sulfonium-based THT-18 was found to be comparable to the commercial disinfectant, BAC. The development of these compounds presents a new avenue for further study of disinfectants to combat the growing threat of bacterial resistance.
An Arabidopsis Oxalyl-CoA Decarboxylase, AtOXC, Is Important for Oxalate Catabolism in Plants

Considering the widespread occurrence of oxalate in nature and its broad impact on a host of organisms, it is surprising that so little is known about the turnover of this important acid. In plants, oxalate oxidase is the most well-studied enzyme capable of degrading oxalate, but not all plants possess this activity. Recently, acyl-activating enzyme 3 (AAE3), encoding an oxalyl-CoA synthetase, was identified in Arabidopsis. This enzyme has been proposed to catalyze the first step in an alternative pathway of oxalate degradation. Since this initial discovery, this enzyme and proposed pathway have been found to be important to other plants and yeast as well. In this study, we identify, in Arabidopsis, an oxalyl-CoA decarboxylase (AtOXC) that is capable of catalyzing the second step in this proposed pathway of oxalate catabolism. This enzyme breaks down oxalyl-CoA, the product of AtAAE3, into formyl-CoA and CO2. AtOXC:GFP localization suggested that this enzyme functions within the cytosol of the cell. An Atoxc knock-down mutant showed a reduction in the ability to degrade oxalate into CO2. This reduction in AtOXC activity resulted in an increase in the accumulation of oxalate and the enzyme substrate, oxalyl-CoA. Size exclusion studies suggest that the enzyme functions as a dimer. Computer modeling of the AtOXC enzyme structure identified amino acids of predicted importance in co-factor binding and catalysis. Overall, these results suggest that AtOXC catalyzes the second step in this alternative pathway of oxalate catabolism.
Incorporation of feeding functional group information informs explanatory patterns of long-term population changes in fish assemblages

The objective of this study was to evaluate long term trends of fish taxa in southern Lake Michigan while incorporating their functional roles to improve our understanding of ecosystem level changes that have occurred in the system over time. The approach used here highlighted the ease of incorporating ecological mechanisms into population models so researchers can take full advantage of available long-term ecosystem information. Long term studies of fish assemblages can be used to inform changes in community structure resulting from perturbations to aquatic systems and understanding these changes in fish assemblages can be better contextualized by grouping species according to functional groups that are grounded in niche theory. We hypothesized that describing the biological process based on partial pooling of information across functional groups would identify shifts in fish assemblages that coincide with major changes in the ecosystem (e.g., for this study, shifts in zooplankton abundance over time). Herein, we analyzed a long-term Lake Michigan fisheries dataset using a multi-species state space modeling approach within a Bayesian framework. Our results suggested the population growth rates of planktivores and benthic invertivores have been more variable than general invertivores over time and that trends in planktivores can be partially explained by ecosystem changes in zooplankton abundance. Additional work incorporating more ecosystem parameters (e.g., primary production, etc.) should be incorporated into future iterations of this novel modeling concept.
Comparing the Effectiveness and Safety Associated With Infliximab vs Infliximab-abda Therapy for Patients With Hidradenitis Suppurativa

Importance Although limited effective and affordable treatment options exist for hidradenitis suppurativa, recent studies describe the effectiveness of a medical therapy, infliximab, for the treatment of hidradenitis suppurativa. Cost-saving biosimilar alternatives have recently become available, but no data currently exist on their safety and effectiveness. Objective To evaluate the effectiveness of infliximab-abda vs infliximab administration associated with the treatment of hidradenitis suppurativa. Design, Setting, and Participants This retrospective cohort study identified patients treated with infliximab or infliximab-abda between 2016 and 2020 at the dermatology clinic at the University of North Carolina at Chapel Hill. The study population included patients who met the clinical criteria for hidradenitis suppurativa and had received a continuous dose of infliximab or infliximab-abda for at least 10 weeks. In total, 62 potential participants were identified using clinical tracking lists on the electronic medical records, and 34 participants were included in the final analysis. Exposures Patients who started receiving infliximab or infliximab-abda were clinically tracked for a minimum of 10 weeks using the electronic medical record system, beginning at the time of drug initiation. Patients received loading doses of 10 mg/kg at weeks 0, 2, and 6, and then treatment was continued with a maintenance dose administered every 4 to 8 weeks. Main Outcomes and Measures The primary outcome measure was Hidradenitis Suppurativa Clinical Response, defined as at least 50% decrease in inflammatory nodule count without any increase in number of abscesses or draining sinuses. Results Of 34 participants, 20 comprised the infliximab treatment group (mean [SD] age, 42.2 [13.2] years; 17 women [85%]), and 14 comprised the infliximab-abda treatment group (mean [SD] age, 35.5 [10.9] years; 13 women [93%]). The proportions of patients achieving a Hidradenitis Suppurativa Clinical Response were 71% (10 patients) in the infliximab-abda and 60% (12 patients) in the infliximab treatment group, which were not significantly different (P = .47). Conclusions and Relevance This cohort study found that both infliximab administration and infliximab-abda administration were associated with similar and significant improvement in disease as measured by the Hidradenitis Suppurativa Clinical Response. Infliximab-abda is likely a reasonable treatment option for hidradenitis suppurativa, and further research is warranted.
Dysregulation of Systemic Immunity in Aging and Dementia.

Neuroinflammation and the tissue-resident innate immune cells, the microglia, respond and contribute to neurodegenerative pathology. Although microglia have been the focus of work linking neuroinflammation and associated dementias like Alzheimer’s Disease, the inflammatory milieu of brain is a conglomerate of cross-talk amongst microglia, systemic immune cells and soluble mediators like cytokines. Age-related changes in the inflammatory profile at the levels of both the brain and periphery are largely orchestrated by immune system cells. Strong evidence indicates that both innate and adaptive immune cells, the latter including T cells and B cells, contribute to chronic neuroinflammation and thus dementia. Neurodegenerative hallmarks coupled with more traditional immune system stimuli like infection or injury likely combine to trigger and maintain persistent microglial and thus brain inflammation. This review summarizes age-related changes in immune cell function, with special emphasis on lymphocytes as a source of inflammation, and discusses how such changes may potentiate both systemic and central nervous system inflammation to culminate in dementia. We recap the understudied area of AD-associated changes in systemic lymphocytes in greater detail to provide a unifying perspective of inflammation-fueled dementia, with an eye toward evidence of two-way communication between the brain parenchyma and blood immune cells. We focused our review on human subjects studies, adding key data from animal models as relevant.
Testing the effectiveness of community-engaged citizen science to promote physical activity, foster healthier neighborhood environments, and advance health equity in vulnerable communities: The Steps for Change randomized controlled trial design and methods

Abstract While low-income midlife and older adults are disproportionately affected by non-communicable diseases that can be alleviated by regular physical activity, few physical activity programs have been developed specifically with their needs in mind. Those programs that are available typically do not address the recognized local environmental factors that can impact physical activity. The specific aim of the Steps for Change cluster-randomized controlled trial is to compare systematically the initial (one-year) and sustained (two-year) multi-level impacts of an evidence-based person-level physical activity intervention (Active Living Every Day [ALED] and age-relevant health education information), versus the ALED program in combination with a novel neighborhood-level citizen science intervention called Our Voice. The study sample (N = 300) consists of insufficiently active adults ages 40 years and over living in or around affordable senior public housing settings. Major study assessments occur at baseline, 12, and 24 months. The primary outcome is 12-month change in walking, and secondary outcomes include other forms of physical activity, assessed via validated self-report measures supported by accelerometry, and physical function and well-being variables. Additional intervention impacts are assessed at 24 months. Potential mediators and moderators of intervention success will be explored to better determine which subgroups do best with which type of intervention. Here we present the study design and methods, including recruitment strategies and yields. Trial registration clinicaltrial.gov Identifier = NCT03041415
Validation of the Hopkins Symptom Checklist-25/Nepali Version among Bhutanese Refugees in the United States.

BACKGROUND Bhutanese refugees' mental problems are relatively high. The Hopkins Symptom Checklist-25 (HSCL-25) has been used widely in examining refugees' mental health, but its psychometric properties in Nepali version is unknown. PURPOSE To examine psychometric properties of the HSCL-25/Nepali version. METHODS Bhutanese refugees (n = 209) responded to demographic questionnaire, the HSCL-25/Nepali, and the Refugee Health Survey-15. Exploratory factor analysis (EFA), convergent validity, and internal consistency were performed. RESULTS After three rounds of EFA, item 14 was deleted resulting in HSCL-24/Nepali with good construct validity and excellent internal consistency (α = .94). CONCLUSIONS The HSCL-24/Nepali version is reliable and valid and can be used to culturally, appropriately assess psychological distress of Bhutanese refugees as it omits item 14 that captures individual's sexual interest.
Hyperoxia: is it a biomarker for mortality?

Dear Editor,I have read Drs. Asfar, Singer, andRadermacher’s article with greatinterest [1]. The authors have pre-sented the potential beneﬁcial andharmful effects of hyperoxia inexcellent mechanistic detail. How-ever, in my opinion, the hypothesesthey presented are not clinicallyapplicable, because reported shortmoments of high PaO
Identification of Salmonella with the O-1 Bacteriophage

The O-1 bacteriophage test of Cherry et al. (1954) for the presumptive identification of salmonellae in the diagnostic laboratory was investigated. A phage lysate with a titer of 1012 plaque-forming units per ml was found to be optimal. This preparation lysed 98.2% of Salmonella strains tested, while maintaining its high specificity for salmonellae. Gram-negative organisms other than salmonellae were resistant to the O-1 phage; however, 5.9% of Escherichia coli strains tested were susceptible. The O-1 phage test is a simple, rapid, inexpensive, sensitive, and specific procedure for the identification of salmonellae in the diagnostic laboratory. A presumptive identification is obtained 1 day earlier than with conventional biochemical tests.
A closer look at frailty in ESRD: Getting the measure right

Patients treated with dialysis have low levels of physical functioning and activity. Whether this translates into frailty or not may depend on how the frailty phenotype is operationalized. This is a secondary analysis of data from the Renal Exercise Demonstration Project to evaluate two methods of operationalizing the Fried phenotype for frailty: Using measured walking speed and muscle weakness (FRAILmeas) and using substitution of the Physical Function Scale (PF) from the SF-36 questionnaire for walking speed and muscle weakness (FRAILsubst). Complete data for both measures were available for 188 hemodialysis patients. The frailty score (FRAILmeas) was the sum of criteria scores for measured gait speed, chair stand, body mass index, vitality, and physical activity. The frailty score (FRAILsubst) substituted the PF scale score (<75) as a surrogate measure for gait speed and for weakness. The frailty score ranged from 0 to 5. Scores ≥3 were categorized as frail, and <3 as not frail. The substitution of the PF score for walking speed and muscle weakness resulted in 78% of patients being categorized as frail compared to 24% using actual measured walking speed and muscle weakness (P < .001). The component of frailty that had the highest prevalence was low physical activity (average 54% of subjects). Frailty (using the FRAILmeas) was higher in patients with increasing age, female gender, and lower self-reported PF. Frailty is highly prevalent in hemodialysis patients; however, measured constructs of the components of frailty should be used to report the frailty phenotype.
AN AVERAGING METHOD FOR STOCHASTIC APPROXIMATIONS WITH DISCONTINUOUS DYNAMICS, CONSTRAINTS, AND STATE DEPENDENT NOISE

Publisher Summary This chapter presents an averaging method for stochastic approximations with discontinuous dynamics, constraints, and state dependent noise. In telecommunications systems, the signal is quantized frequently and only the quantized form is transmitted to use the communications channel as efficiently as possible. It is desirable to adapt the quantizer to the particular signal to maximize the quality of the received signal. The chapter describes a stochastic approximation form of an adaptive quantizer and discusses state-dependent noise.
New Nonparametric Estimation of the Marginal Effects in Fixed-Effects Panel Models: An Application on the Environmental Kuznets Curve

This paper considers kernel-based nonparametric estimation of panel models using local linear least squares, when both the fixed individual effects and the time effects present. The marginal effect is of the main interest. A within-group type nonparametric estimator is developed, where the within transformation is based on locally weighted average. For nonparametric fixed-effects models, it is shown that conventional within transformation or first difference render panel nonparametric estimators biased and the bias does not degenerate even with large samples. The proposed estimator, on the other hand, not only achieves the degenerating approximated bias of the order h^2 but also has the approximated variance of the order 1/(NT(h^3)). The optimal bandwidth parameter is also obtained to be of the order (NT)^{-1/7}. The new estimation is applied to analyze the nonlinear relationship between emission and income (i.e., the environmental Kuznets curve) using U.S. state-level panel data on nitrogen oxide and sulfur dioxide emissions.
Abdominal Aortic Hemodynamics in Intermittent Claudication Patients at Rest and during Dynamic Pedaling Exercise.

Background Lower-extremity exercise has been shown to eliminate adverse hemodynamics conditions, such as low and oscillating blood flow and wall shear stress, in the abdominal aortas of healthy young and older adults. Methods We use cine phase-contrast magnetic resonance imaging and a custom MRI-compatible exercise cycle to quantify hemodynamic changes because of pedaling exercise in patients diagnosed with intermittent claudication. Results With only an average heart increase of 35 ± 18% and exercise workload of 36 ± 16 watts, the patients experienced approximately 3- and 6-fold increases in blood flow, and 4- and 16-fold increases in wall shear stress at the supraceliac and infrarenal aortic locations, respectively. Also, all oscillations in flow and shear stress at rest were eliminated with exercise. Conclusions Claudication patients experience 3- to 4-fold lower oscillations in flow and shear stress at rest as compared with healthy age-matched controls, likely because of reduced distal arterial compliance as a result of distal atherosclerosis. The magnitude of flow and shear oscillatory indices may be good indicators of distal arterial compliance and health, and may provide predictive power for the efficacy of focal interventions.
Two-dimensional transform domain adaptive filtering

A two-dimensional (2D) orthogonal transform is incorporated into a 2D FIR adaptive filter to improve the input autocorrelation matrix eigenvalue spread, thereby achieving improved convergence rates for 2D adaptive filters operating in colored noise. Eigenvalues analyses are used to predict the relative merits of different transforms when operating on different colored noise inputs. Both theoretical predictions and experimental results are presented to demonstrate that the reduction in eigenvalue spread results in greatly improved convergence rates in 2D adaptive filters, which suffer from inherently slow convergence due to the large number of coefficients required in two dimensions. >
Effect of a rumen-protected niacin product on lactation performance by dairy cows during summer in Wisconsin

ABSTRACT The objective of this study was to evaluate the effect of a rumen-protected niacin product (NiaShure, Balchem Corp., New Hampton, NY) on lactation performance by dairy cows during the summer in Wisconsin. Eighty lactating dairy cows (63 ± 29 DIM) were used in a 10-wk lactation trial (a 2-wk pretreatment covariate period followed by an 8-wk treatment period). Cows were stratified by breed, parity, and DIM and randomly assigned to 10 pens of 8 cows each. Pens were assigned randomly to either control or 12 g/d per cow rumen-protected niacin TMR. Ambient temperature and humidity were monitored weekly to calculate temperature–humidity index, and individual cow rectal temperatures were measured weekly to characterize heat-stress conditions during the experiment. Milk yield, milk composition, milk component yields, DMI, BW, and rectal temperature were unaffected (P > 0.10) by treatment. Under summer conditions in Wisconsin, dietary supplementation with rumen-protected niacin at 12 g/d per cow did not affect (P > 0.10) lactation performance or body temperature of dairy cows.
The PET54 gene of Saccharomyces cerevisiae: characterization of a nuclear gene encoding a mitochondrial translational activator and subcellular localization of its product

The product of the nuclear Saccharomyces cerevisiae gene PET54 is specifically required, along with at least two other nuclear gene products, for translation of the mitochondrial mRNA encoding subunit III of cytochrome c oxidase (coxIII). We have genetically mapped PET54 (to the right arm of chromosome VII, 4.8 cM centromere-distal to SUF15), and have biochemically characterized the gene and its product. We determined the nucleotide sequence of a 1.6-kb DNA fragment carrying PET54 and identified the PET54 reading frame by determining the sequence of an ochre mutant allele as well as frameshift and frameshift-revertant alleles of the gene. The wild-type PET54 gene encodes a slightly basic 293-amino acid protein. PET54 is expressed from two mRNAs, both with unusual features: a major transcript with an extremely short 5'-untranslated leader, and a minor transcript with a relatively long 5'-leader carrying three short open reading frames. Antiserum raised against a trpE-PET54 fusion protein was used to probe subcellular fractions. These experiments showed that the PET54 protein is specifically associated with mitochondria, suggesting that it is likely to act directly in coxIII translation.
Health Care Systems of the World, Changing

This entry analyzes the funding, contracting, and provision of health care as well as administration and government regulation as “core” functions of selected health care systems across the world, and assesses recent changes in those systems. Despite major differences in those core elements, the entry illustrates similarities in basic policy goals, policy challenges, and programmatic change across countries: separation of funding and contracting health care, and a general shift towards case-based hospital payment. Another finding concerns “exit” behavior: offered a choice between public and private schemes, consumers indeed act – in particular, the young and healthy find private insurance more attractive than public schemes. Income level, (public) health spending, and health are closely associated. Nevertheless, statistical correlation does not equal causality, and some countries fared better than others in improving the health of their population. Political instability obviously undermines government capacity to safeguard access to basic health services. Fiscal stability and public trust in a well-functioning banking and finance system, too, are essential to prevent dramatic loss of real incomes and to develop systems of collective savings for pre-paid health insurance. Keywords: health; health administration; health care; health policy and politics; international comparison
Temperature dependence of optical properties of aqueous dispersions of phosphatidylcholine

Abstract Aqueous dispersions of dipalmitoyl phosphatidyl choline exhibit a sharp decrease in turbidity at the crystal-liquid phase transition temperature of 41°C. The intensity of light scattered at 45°, 90°, and 135° also undergoes a sharp drop at the same temperature. Similarly, the refractive index of such dispersions decreases abruptly with the phase transition. Employing the relationship between light scattering intensity and specific refractive increment, it can be shown that about one half of the change in absorbancy and scattering are accounted for by the change in refractive index. The change in refractive index can be entirely accounted for by the known expansion and corresponding decrease in density of the bilayer. That part of the observed change in scattering and turbidity which is not accounted for by the observed change in average refractive index is apparently due to a decrease in the anisotropy of the bilayer during the melting process. Calculations based on a model which, although oversimplified, is consistent with the known thinning of the bilayer during the melting process, give quantitative agreement with experimental results. Below the phase transition temperature other changes in optical properties are observed; near 32°C, the light scattering envelope changes and the turbidity of dispersions drops markedly. The average refractive index remains constant in this region. For this and other reasons, it is postulated that these pre-transition changes indicate an aggregation-disaggregation phenomenon.
Chemisorption and reactions of nitric oxide on rhodium

Abstract The adsorption and desorption of NO and its reactions with CO over polycrystalline Rh have been studied using flash desorption spectroscopy (FDS), titration techniques, and steady state reaction kinetics. At 330 K, NO absorbs with an initial sticking probability near unity. At saturation about 15% of these are dissociated as indicated by their rapid reaction with CO to produce CO2 (g). NO desorbs in a single FDS peak at 430 K. Most of the NO, however, dissociates prior to and during the flash, producing two major N2 peaks (β1 and β2) and an O2 peak. Possible mechanisms for NO dissociation and the formation of N2 are discussed. Co-adsorption of NO and CO produces a CO2 FDS peak at 480 K. This CO2 is the product of a Langmuir-Hinshelwood reaction between adsorbed CO and adsorbed oxygen atoms, and is rate-limited by the dissociation of NO. This suggests that β1 N2, also appearing at 480 K, is rate-limited by the same process. The creation of empty sites by NO desorption or the thermal activation of other sites accelerates this dissociation, a process whose exothermicity could play an important role in the β1 N2 desorption peak. The β2 N2 peak appears at 650 K, very close to the desorption temperature (670 K) for nitrogen adatoms deposited on Rh by activation of N2 (g). Thus the associative desorption of N(a) is not affected by the presence of O(a). A low energy adsorption state for CO arises in the presence of N(a). Preliminary results for the steady state kinetics of NO reduction by CO indicate N2 and CO2 as major products. Adsorbed CO inhibits the reaction at low temperatures by occupying sites required for NO adsorption and dissociation. The large activation energy at these temperatures reflects the increasing rate of CO desorption with temperature. At higher temperatures, the competition of many processes indicates the necessity for much more detailed study.
Performance of Aluminum and Carbon Foams for Air Side Heat Transfer Augmentation

The air side heat transfer performance of three aluminum foam samples and three modified carbon foam samples are examined for comparison with multilouvered fins often found in compact heat exchangers. The aluminum foam samples have a bulk density of 216 kg/m 3 with pore sizes of 0.5, 1, and 2 mm. The modified carbon foam samples have bulk densities of 284, 317, and 400 kg/m 3 and machined flow passages of 3.2 mm in diameter. The samples were placed in a forced convection arrangement using a foil heater as the heat source and ambient air as the sink. A constant heat flux of 9.77 kW/m 2 is applied throughout the experiments with the mean air velocity ranging from 1 to 6 m/s as the control parameter. The steady volume-averaged momentum equation and a two-equation nonequilibrium heat transfer model are employed to extract the volumetric heat transfer coefficients. Pressure drop measurements are correlated with the Darcy-Forcheimer relation. Empirical heat transfer correlations for the aluminum and carbon foam samples are provided. Using a hypothetical heat exchanger considering only the thermal resistance between the ambient air and the outer tube wall, the air side performance for each sample is modeled based on the local heat transfer coefficients and friction factors obtained from experiments. The performance of each sample is evaluated based on a coefficient of performance (COP, defined as the ratio of the total heat removed to the electrical input of the blower), compactness factor (CF, defined as the total heat removed per unit volume), and power density (PD, defined as the total heat removed per unit mass). Results show the carbon foam samples provide significant improvement in CF but the COP and PD are considerably lower than that for comparable multilouvered fin heat exchangers.
Effects of exercise training on high density lipoproteins and apolipoprotein A-I in old and young men

Although exercise training has been demonstrated to improve lipid profiles in young and middle-aged subjects, the response in training in the elderly has received little attention. In this study, we assessed and compared the changes in aerobic capacity, lipid profiles, and body composition in young (Y, 31.9 +/- 5.5 years; n = 18) and older (O, 65.1 +/- 6.1 years; n = 10) subjects in response to similar 3-month exercise training programs (80% to 85% of heart rate reserve, three times per week). We hypothesized that the responses would be qualitatively similar for the two groups, although the absolute quantitative response might be somewhat less in the elderly. The two groups were quite similar at baseline for percent body fat (Y, 30.1% +/- 7.2% v O, 30.3% +/- 4.7%; P = NS) and maximal aerobic capacity (Y, 36.8 +/- 8.1 v O, 36.3 +/- 8.3 mL/kg/min; P = NS). In addition, there were no significant differences in the baseline lipid profiles between the groups. After training, the improvements in body composition were similar, with both groups losing similar amounts of fat (Y, 2.86% +/- 3.14% v O, -2.85% +/- 1.78%) and neither group significantly changing their fat-free mass. Maximal aerobic capacity improved in both groups, but the increment was greater in the young (18% v 10%, P less than .05). HDL-cholesterol (+6%, P less than .01) and apolipoprotein A-I (+6%, P less than .01) concentrations increased significantly only in the young. These increments, however, were not different from those observed in the older subjects (+7% and +4%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of fibrillation on acetylcholinesterase mRNA in cultured embryonic rat myotubes

Acetylcholinesterase (AChE) and AChE mRNA were evaluated in spontaneously fibrillating myotubes derived from 20-day-old rat fetuses and in matched cultures in which fibrillation was prevented by adding tetrodotoxin on the fourth day of culture. On the eighth day of culture, the AChE activity of fibrillating and nonfibrillating cultures was 5332 and 1861 pmol ACh hydrolyzed min-1 dish-1, respectively (P less than 0.005). Total mRNA was essentially the same in fibrillating and nonfibrillating cultures (27.4 and 25.4 micrograms/dish, respectively). AChE mRNA was assessed by assaying the AChE produced by Xenopus oocytes microinjected with purified mRNA. The AChE produced by mRNA from fibrillating and nonfibrillating cultures was 0.46 and 0.10 pmol ACh hydrolyzed min-1 oocyte-1, respectively (P less than 0.005).
T-Lymphocyte depletion induced in rats by analogs of tilorone hydrochloride☆

Abstract Tilorone, a bis-basic substituted fluorene-9-one compound, and four of its analogs depleted lymphocytes in thymic-dependent areas in both the spleen and lymph nodes after both sc and oral administration to rats. Twenty-nine out of 39 analogs administered by either route depleted lymphocytes in the spleen, lymph nodes, or in both. Active analogs encompassed a wide variety of polycylic ring structures including fluorene, fluoranthene, anthraquinone, dibenzothiophene, dibenzofuran, and even a bicyclic ring (naphthyridine) and a simple pyridine ring. The two teriary amine side chains in active compounds included ether, ketone, ester, alkane, and thioether but not carboxamide, thioester, or sulfonamide linkages. The mesenteric lymph node was especially susceptible to analogs administered by the oral route. The subcutaneous route was often associated with acute necrosis of cells in the thymic cortex, probably an indirect effect of stress and adrenal stimulation, which had the consequence of blocking lymphocyte depletion in the spleen and nodes. This complicating effect of certain compounds may be partly responsible for the inability to correlate lymphocyte-depletion with antiviral activity.
Holocaust Curriculum Development for Latvian Schools: Arriving at Purposes, Aims, and Goals through Curriculum Deliberation

Abstract Teaching about the Holocaust is a deeply sensitive and controversial topic in the Republic of Latvia. Due to a Soviet-imposed silence on the topic and the developing nature of democratic education in Latvia, many schools cover this history superficially, if it is covered at all. This study examines a cross-cultural curriculum development project that sought to break the historical silence surrounding the Holocaust in Latvia and provide Latvian teachers with an inviting, defensible, and efficacious curriculum that is both sensitive to societal reluctance to discuss the Holocaust and responsive to the needs of students living in a pluralistic democracy. This ethnographic and descriptive case study draws on multiple interviews with curriculum writers and project personnel, as well as field notes from the 18 month project, and examines how writers arrived at the curricular purposes, aims, goals, and content that would open this closed area. Significant findings include new understandings of the chall...
SHOULD AN ISOLATED HUMERAL LESION DETECTED DURING PROSTATE CANCER METASTATIC SURVEY BE BIOPSIED

We report radiographic and pathological results in 2 patients with biopsy proved prostate cancer who underwent full metastatic evaluation, including bone biopsy, after undergoing a bone scan consistent with a solitary metastatic lesion to the humerus. CASE HISTORIES Two men underwent prostate biopsy because of high levels of serum prostate specific antigen (PSA). Patient 1, who was 60 years old and had a serum PSA level of 4.5 ng/ml, was diagnosed with Gleason score 3 4 adenocarcinoma of the prostate. Patient 2, who was 49 years old and had a serum PSA level of 4.8 ng/ml, was diagnosed with Gleason score 3 3 prostatic adenocarcinoma. Bone scan in each patient demonstrated increased uptake in the right humerus that was read as being suspicious for metastasis without other suspicious areas. In both cases subsequent plain film radiography confirmed a focal lesion in the right humerus. Magnetic resonance imaging (MRI) showed bone marrow replacementin bot h cases, which prompted open biopsy (fig. 1). Biopsy in both cases was consistent with enchondroma, a benign primary tumor of bone that required no further treatment (fig. 2). Both patients underwent radical prostatectomy with lymph node dissection, and both had organ confined disease.
Open-field behavior and heart rate in prenatally X-irradiated rats.

Albino rats were exposed to X irradiation in utero on day 16 of gestation. In two separate experiments, animals that received 200 r, but not those that received 100 r, showed increased locomotor activity in an open-field on three successive daily 3-minute test sessions. In contrast to this hyperactivity, exploration measured by the duration of sniffing at novel objects was lower in irradiated animals on the first test day, but reached the level of the controls on the second test day. Animals with previous testing experience did not show increased locomotor activity at the age of one year. Measures of defecation did not discriminate as reliably as did locomotor activity. Animals that received 200 r also had a higher heart rate than a control group, with the difference decreasing over a 60-minute testing period. The data would indicate that prenatally X-irradiated rats show fearfulness when exposed to novel situations but with increased exposure to the testing situation or experience the animals' responses tend to approximate those of unexposed animals.
A 10-mg nomogram was more effective than a 5-mg nomogram for warfarin induction in outpatient venous thromboembolism.

Source Citation Kovacs MJ, Rodger M, Anderson DR, et al. Comparison of 10-mg and 5-mg warfarin initiation nomograms together with low-molecular-weight heparin for outpatient treatment of acute veno...
Ruptured chordae tendineae of the tricuspid valve as a complication of endomyocardial biopsy in heart transplant patients

Abstract Percutaneous transvenous endomyocardial biopsy is the preferred method to detect graft rejection in the transplanted heart. This procedure has undergone improvements and modifications making endomyocardial biopsy safe from the right internal jugular or femoral venous approach. 1,2 Large series have documented the low morbidity and mortality associated with endomyocardial biopsy. Major complications include cardiac perforation and tamponade occurring in 1,2 Other cardiac complications are arrhythmias, bundle branch block and endocarditis. Recently, coronary arterial-right ventricular fistula secondary to repeated endomyocardial biopsies has been described. 3 With improved survival in cardiac transplant patients, complications of repeated endomyocardial biopsies may become more apparent. This report describes 5 patients with orthotopic cardiac transplants who have echocardiographic evidence of tricuspid valve chordal rupture as a complication of endomyocardial biopsy.
Suppression of cell-mediated immune responses in vivo and in vitro by 1-thiocarbamoyl-2-imidazolidinone.

Abstract Both in vivo and in vitro, the niridazole metabolite, 1-thiocarbamoyl-2-imidazolidinone (TCI), was found to suppress various manifestations of cell-mediated immunity. In vivo, doses of 10 −6 g/kg every other day delayed rejection of BALB/cJ (H−2 d ) skin allografts by C57BL/6J (H−2 b ) mice. Much lower single doses (∼10 −11 g / kg ) markedly reduced both pulmonary granuloma formation around, Schistosoma mansoni eggs in C57BL/6J mice and delayed footpad swelling in sensitized CF 1 mice responding to S. mansoni egg antigen (SEA). Reduction of footpad swelling occured when TCI was given 24 hr before, but not 4 hr after, antigenic challenge. In vitro, SEA-dependent production of eosinophil stimulation promoter (ESP) activity by sensitized mouse spleen cells was decreased > 90% by 10 −10 g TCI / ml . TCI failed, however, to inhibit the action of preformed ESP lymphokine on eosinophils. The blastogenic response of sensitized lymph node cells to SEA was reduced by > 70% by 10 −11 to −10 −8 g TCI / ml . The drug produced no effect on either antigen-dependent lymphokine production or blastogenesis if it was added 5 min after, instead of before, stimulating antigen.
On differential thermal analyzer curves for the melting and freezing of alloys

Using a heat-flow model of a differential thermal analyzer and thermal characteristics obtained by fitting experimental results for a pure metal, the response of the differential thermal analyzer is modeled for the melting and solidification of alloys. The enthalpy-temperature relation used for the alloy simulations is obtained by two different methods: (1) equilibrium and Scheil considerations derived solely from thermodynamic information and (2) solute-diffusion micromodels coupled to the differential thermal analysis (DTA) heat-flow equations. During the consideration of pure material melting, simple expressions are obtained for the effect of sample size and heating rate on the DTA melting onset temperature, peak temperature, and peak height, which assist in the proper calibration of a differential thermal analyzer. For alloys, the smearing effect of the DTA heat flow at different heating and cooling rates is demonstrated for various solidification-path features. In particular, the DTA peak temperature during melting, which is often selected as the liquidus temperature experimentally, is shown to be significantly higher than the liquidus temperature for small-freezing-range alloys and/or for alloys with slow solid diffusion. The DTA curves calculated for freezing with dendritic growth due to supercooling, quantify the errors associated with the determination of the liquidus temperature on cooling.
Simple methods for plating single vegetative cells of, and for replica-plating, filamentous blue-green algae.

Heterocyst-forming, filamentous blue-green algae may be broken into fragments having an average length as close to one cell as desired, by cavitation in an ultrasonic cleaner. The resulting fragments from six algae give rise to clones, with high plating efficiency. Sporulated clones of Anabeana flos-aquae may be replica-plated with velveteen.
Bacteriophage T4 transcriptional control gene 55 codes for a protein bound to Escherichia coli RNA polymerase

Abstract Escherichia coli RNA polymerase purified after T4 infection contains several bacteriophage-specific proteins, one of which has been suggested to be the product of transcriptional control gene 55 (Stevens, 1972; Horvitz, 1973). This report proves that gene 55 codes directly for the 22,000 molecular weight polymerase-binding protein. (1) The appearance of this protein requires a full-sized, but not an active, gene 55 product; and (2) gene 55 temperature-sensitive mutants produce, under permissive conditions, 22,000 molecular weight proteins that show reduced in vitro binding to RNA polymerase.
Reporting results from studies evaluating diagnostic tests

Evaluating a new diagnostic test requires careful planning. It involves choosing the appropriate comparative procedure, patients, specimens, and individuals performing the tests. The type of study design used to evaluate a new test has a direct impact on how the study results can be reported. This article describes some statistically appropriate and inappropriate practices for reporting results from different studies evaluating qualitative diagnostic tests. Special attention is given to describing a practice called discrepant resolution and its associated problems.