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Search Results: 1 - 10 of 174193 matches for " Jeffrey E. Christensen "
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Yeast Modulation of Human Dendritic Cell Cytokine Secretion: An In Vitro Study
Ida M. Smith, Jeffrey E. Christensen, Nils Arneborg, Lene Jespersen
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096595
Abstract: Probiotics are live microorganisms which when administered in adequate amounts confer a health benefit on the host. The concept of individual microorganisms influencing the makeup of T cell subsets via interactions with intestinal dendritic cells (DCs) appears to constitute the foundation for immunoregulatory effects of probiotics, and several studies have reported probiotic strains resulting in reduction of intestinal inflammation through modulation of DC function. Consequent to a focus on Saccharomyces boulardii as the fundamental probiotic yeast, very little is known about hundreds of non-Saccharomyces yeasts in terms of their interaction with the human gastrointestinal immune system. The aim of the present study was to evaluate 170 yeast strains representing 75 diverse species for modulation of inflammatory cytokine secretion by human DCs in vitro, as compared to cytokine responses induced by a S. boulardii reference strain with probiotic properties documented in clinical trials. Furthermore, we investigated whether cytokine inducing interactions between yeasts and human DCs are dependent upon yeast viability or rather a product of membrane interactions regardless of yeast metabolic function. We demonstrate high diversity in yeast induced cytokine profiles and employ multivariate data analysis to reveal distinct clustering of yeasts inducing similar cytokine profiles in DCs, highlighting clear species distinction within specific yeast genera. The observed differences in induced DC cytokine profiles add to the currently very limited knowledge of the cross-talk between yeasts and human immune cells and provide a foundation for selecting yeast strains for further characterization and development toward potentially novel yeast probiotics. Additionally, we present data to support a hypothesis that the interaction between yeasts and human DCs does not solely depend on yeast viability, a concept which may suggest a need for further classifications beyond the current definition of a probiotic.
Altered Trabecular Bone Structure and Delayed Cartilage Degeneration in the Knees of Collagen VI Null Mice
Susan E. Christensen, Jeffrey M. Coles, Nicole A. Zelenski, Bridgette D. Furman, Holly A. Leddy, Stefan Zauscher, Paolo Bonaldo, Farshid Guilak
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033397
Abstract: Mutation or loss of collagen VI has been linked to a variety of musculoskeletal abnormalities, particularly muscular dystrophies, tissue ossification and/or fibrosis, and hip osteoarthritis. However, the role of collagen VI in bone and cartilage structure and function in the knee is unknown. In this study, we examined the role of collagen VI in the morphology and physical properties of bone and cartilage in the knee joint of Col6a1?/? mice by micro-computed tomography (microCT), histology, atomic force microscopy (AFM), and scanning microphotolysis (SCAMP). Col6a1?/? mice showed significant differences in trabecular bone structure, with lower bone volume, connectivity density, trabecular number, and trabecular thickness but higher structure model index and trabecular separation compared to Col6a1+/+ mice. Subchondral bone thickness and mineral content increased significantly with age in Col6a1+/+ mice, but not in Col6a1?/? mice. Col6a1?/? mice had lower cartilage degradation scores, but developed early, severe osteophytes compared to Col6a1+/+mice. In both groups, cartilage roughness increased with age, but neither the frictional coefficient nor compressive modulus of the cartilage changed with age or genotype, as measured by AFM. Cartilage diffusivity, measured via SCAMP, varied minimally with age or genotype. The absence of type VI collagen has profound effects on knee joint structure and morphometry, yet minimal influences on the physical properties of the cartilage. Together with previous studies showing accelerated hip osteoarthritis in Col6a1?/? mice, these findings suggest different roles for collagen VI at different sites in the body, consistent with clinical data.
Physiological explanations of heterosis
E Andresen, K Christensen
Genetics Selection Evolution , 1982, DOI: 10.1186/1297-9686-14-1-106b
Abstract:
Physiological explanations of heterosis
Andresen E,Christensen K
Genetics Selection Evolution , 1982,
Abstract:
The effects of oral clefts on hospital use throughout the lifespan
George L Wehby, Dorthe Pedersen, Jeffrey C Murray, Kaare Christensen
BMC Health Services Research , 2012, DOI: 10.1186/1472-6963-12-58
Abstract: We estimate two-part regression models for hospital admission and length of stay for several age groups up to 68 years of age. The study employs unique secondary population-based data from several administrative inpatient, civil registration, demographic and labor market databases for 7,670 individuals born with oral clefts between 1936 and 2002 in Denmark, and 220,113 individuals without oral clefts from a 5% random sample of the total birth population from 1936 to 2002.Oral clefts significantly increase hospital use for most ages below 60 years by up to 233% for children ages 0-10 years and 16% for middle age adults. The more severe cleft forms (cleft lip with palate) have significantly larger effects on hospitalizations than less severe forms.The results suggest that individuals with oral clefts have higher hospitalization risks than the general population throughout most of the lifespan.Birth defects are common health problems with life-long implications. For example, about 3% of all children in the United States (US) are born with birth defects [1]. Oral clefts or cleft lip and/or cleft palate are one of the most prevalent birth defects and include clefts of the lip with or without the palate or clefts of the palate only. More than 6,500 affected babies were born with oral clefts in 2001 in the US [1]. Oral cleft incidence ranges between 1 per 500 to 1 per 2500 births and varies by ancestral origin and socioeconomic status [2]. The majority of cases occur without other major birth defects [3,4]. A complex etiology of genetic and environmental factors likely contributes to oral clefts [5-11].Oral clefts are associated with difficulties in feeding, growth, cognitive development, speech and behavior and require several surgical, medical, nutritional, dental, and other healthcare interventions [12,13]. Oral clefts may significantly increase the risk of neonatal and infant mortality, especially when present with other birth defects [5,14-18]. Furthermore, oral cleft
Utility values for symptomatic non-severe hypoglycaemia elicited from persons with and without diabetes in Canada and the United Kingdom
Adrian R Levy, Torsten LU Christensen, Jeffrey A Johnson
Health and Quality of Life Outcomes , 2008, DOI: 10.1186/1477-7525-6-73
Abstract: Using validated health states, time trade-off utilities were elicited from 51 Canadian respondents with diabetes, and 79 respondents in Canada and 75 respondents in the United Kingdom (UK) without diabetes.Each hypoglycaemic episode was associated with a reduction in utility and persons with diabetes consistently reported slightly higher utility values than respondents without diabetes. The utility for diabetes without hypoglycaemia ranged from 0.88 to 0.97, the mean utility for rare hypoglycaemic events (quarterly) ranged between 0.85 and 0.94. The utility for the intermittent state (monthly) ranged from 0.77 to 0.90 and from 0.66 to 0.0.83 for the frequent state (weekly). Differences were observed between respondents without diabetes in Canada and the UK. Using a multivariate linear OLS regression, the estimated utilities associated with a single hypoglycaemic event were -0.0033 and -0.0032 for respondents with diabetes and without diabetes, respectively.Among respondents with and without diabetes, there was a demonstrable utility loss associated with hypoglycaemia. Considering a utility loss of 0.03 as a minimum clinically important difference for persons with diabetes, the evidence from this study indicates that as low as ten symptomatic non-severe hypoglycaemic episodes per year may be of clinical importance and that the importance increases with frequency of episodes. Integrating directly elicited utility values such as those reported here will improve the quality and applicability of economic evaluations of diabetes treatment.Hypoglycaemia is a common unintended consequence of insulin that ranges from being bothersome to resulting in coma or even death among persons with diabetes. One group of investigators in the United Kingdom (UK) reported that 73% of insulin users who responded to a mail survey reported at least one hypoglycaemic episode in the past three months [1]. Weekly rates of hypoglycaemic episodes have been estimated at 0.82 and 0.33 for persons w
Response to Haskell's "Academic Freedom ... & Student Evaluation"
Jeffrey E. Stake
Education Policy Analysis Archives , 1997,
Abstract: Haskell (1997) argued that the administrative practice of student evaluation of faculty is a threat to academic freedom. However, before that claim can be substantiated, several prior questions must be addressed: To whom does academic freedom belong? Individual faculty? The academy? Whose actions can violate the right? Can any lines be drawn based on whether the substance or form of classroom behavior is influenced? And still another crucial point is whether a body can violate academic freedom without any intent to interfere with or control the substance of what is said to students.
Note on the Lattice Fermion Chiral Symmetry Group
Jeffrey E. Mandula
Physics , 2007,
Abstract: The group structure of the variant chiral symmetry discovered by Luscher in the Ginsparg-Wilson description of lattice chiral fermions is analyzed. It is shown that the group contains an infinite number of linearly independent symmetry generators, and the Lie algebra is given explicitly. CP is an automorphism of the chiral group, and the CP transformation properties of the symmetry generators is found. Features of the currents associated with these symmetries are discussed, including the fact that some different, non-commuting symmetry generators lead to the same Noether current. These strange features occur in all implementations of lattice fermions based on the Ginsparg-Wilson relation, including overlap, domain-wall, and perfect-action chiral fermions. The conclusions are illustrated in a solvable example, free overlap fermions.
Numerical Analysis of the Quark Fraction of the Proton Spin
Jeffrey E. Mandula
Physics , 1992,
Abstract: We report on a lattice QCD estimate of the quark spin fraction of the proton spin. The estimate is arrived at by means of a lattice QCD simulation of the polarized proton matrix element of the Adler-Bell-Jackiw anomaly. The preliminary result of the simulation is that this fraction is rather small. This is in accord with the interpretation of the EMC experiment that the quark spins are responsible for very little, if any, of the proton spin. (Talk given at the Adriatico Research Conference on Polarization Dynamics in Nuclear and Particle Physics, Trieste, January, 1992) NOTE: This paper is available only in postscript form.
Gauge Fixing and the Gibbs Phenomenon
Jeffrey E. Mandula
Physics , 1998, DOI: 10.1016/S0920-5632(99)85233-5
Abstract: We address the question of why global gauge fixing, specifically to the lattice Landau gauge, becomes an extremely lengthy process for large lattices. We construct an artificial "gauge-fixing" problem which has the essential features encountered in actuality. In the limit in which the size of the system to be gauge fixed becomes infinite, the problem becomes equivalent to finding a series expansion in functions which are related to the Jacobi polynomials. The series converges slowly, as expected. It also converges non-uniformly, which is an observed characteristic of gauge fixing. In the limiting example, the non-uniformity arises through the Gibbs phenomenon.
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