Mixing properties of bi-disperse ellipsoid assemblies: mean-field behaviour in a granular matter experiment.

The structure and spatial statistical properties of amorphous ellipsoid assemblies have profound scientific and industrial significance in many systems, from cell assays to granular materials. This paper uses a fundamental theoretical relationship for mixture distributions to explain the observations of an extensive X-ray computed tomography study of granular ellipsoidal packings. We study a size-bi-disperse mixture of two types of ellipsoids of revolutions that have the same aspect ratio of α ≈ 0.57 and differ in size, by about 10% in linear dimension, and compare these to mono-disperse systems of ellipsoids with the same aspect ratio. Jammed configurations with a range of packing densities are achieved by employing different tapping protocols. We numerically interrogate the final packing configurations by analyses of the local packing fraction distributions calculated from the Voronoi diagrams. Our main finding is that the bi-disperse ellipsoidal packings studied here can be interpreted as a mixture of two uncorrelated mono-disperse packings, insensitive to the compaction protocol. Our results are consolidated by showing that the local packing fraction shows no correlation beyond their first shell of neighbours in the binary mixtures. We propose a model of uncorrelated binary mixture distribution that describes the observed experimental data with high accuracy. This analysis framework will enable future studies to test whether the observed mean-field behaviour is specific to the particular granular system or the specific parameter values studied here or if it is observed more broadly in other bi-disperse non-spherical particle systems.

How to successfully navigate a nursing student academic/grade grievance.

The challenges of managing an academic/grade grievance can be taxing on nursing faculty. Therefore, it is essential that faculty are well-equipped for these experiences. The purpose of this article is to enable nursing faculty to understand how to navigate a student academic/grade grievance. In this article, three nursing faculty with varying levels of teaching experience will share insightful information on the prevention, preparation, and processes for successfully navigating student academic/grade grievances. They will discuss steps for addressing an academic/grade grievance and lessons learned with helpful tips for nursing faculty to put into their toolbox for future use.

Mild to moderate cognitive impairment is a major risk factor for mortality and nursing home admission in the first year after hip fracture.

BACKGROUND: It is not well established if and to what extent mild to moderate cognitive impairment predicts mortality and risk of nursing home admission after hip fracture. OBJECTIVE: To investigate prospectively whether and to what extent mild to moderate cognitive impairment, contributes to mortality and admission to nursing home in the first year after acute hip fracture. METHODS: We enrolled 173 patients with acute hip fracture age 65 and older who reached a Mini-Mental State Examination (MMSE) score of at least 15 during acute care after hip fracture repair. An MMSE score of 15 to 24 (median) was classified as mild to moderate cognitive impairment. Primary outcomes were mortality in all and admission to nursing home among seniors who lived at home prior to their hip fracture. Follow-up was 12 months with clinical visits at baseline, 6, and 12 months, plus monthly phone calls. We used Cox proportional hazards models controlling for age, sex, body mass index, baseline number of comorbidities and 25-hydroxyvitamin D status, and severe incident infections to assess the risk of mortality and nursing home admission. Because the study population was enrolled in a factorial design clinical trial testing high dose vitamin D and/or an exercise home program, all analyses also controlled for these treatment strategies. RESULTS: Of 173 acute hip fracture patients enrolled, 79% were women, 77% were admitted from home, and 80% were vitamin D deficient (<20ng/ml). Mean age was 84 years. 54% had mild to moderate cognitive impairment. Over the 12-month follow-up, 20 patients died (27% of 173) and 47 (35% of 134) were newly admitted to a nursing home. Mild to moderate cognitive impairment was associated with a more than 5-fold increased risk of mortality (HR=5.77; 95% CI: 1.55-21.55) and a more than 7-fold increased risk of nursing home admission (HR=7.37; 95% CI: 1.75-30.95). Additional independent risk factors of mortality were male gender (HR=3.55; 95% CI: 1.26-9.97), low BMI (HR=7.25; 95% CI: 1.61-33.74), and baseline 25-hydroxyvitamin D level (per 1ng/ml: HR=0.93; 95% CI: 0.87-0.998; p=0.04). CONCLUSIONS: Mild to moderate cognitive impairment in patients with acute hip fracture is associated with a high risk of mortality and nursing home admission during the first year after hip fracture. Female gender, a greater BMI and a higher 25-hydroxyvitamin D status may protect against mortality after hip fracture independent of cognitive function.

Minkowski tensor shape analysis of cellular, granular and porous structures.

Predicting physical properties of materials with spatially complex structures is one of the most challenging problems in material science. One key to a better understanding of such materials is the geometric characterization of their spatial structure. Minkowski tensors are tensorial shape indices that allow quantitative characterization of the anisotropy of complex materials and are particularly well suited for developing structure-property relationships for tensor-valued or orientation-dependent physical properties. They are fundamental shape indices, in some sense being the simplest generalization of the concepts of volume, surface and integral curvatures to tensor-valued quantities. Minkowski tensors are based on a solid mathematical foundation provided by integral and stochastic geometry, and are endowed with strong robustness and completeness theorems. The versatile definition of Minkowski tensors applies widely to different types of morphologies, including ordered and disordered structures. Fast linear-time algorithms are available for their computation. This article provides a practical overview of the different uses of Minkowski tensors to extract quantitative physically-relevant spatial structure information from experimental and simulated data, both in 2D and 3D. Applications are presented that quantify (a) alignment of co-polymer films by an electric field imaged by surface force microscopy; (b) local cell anisotropy of spherical bead pack models for granular matter and of closed-cell liquid foam models; (c) surface orientation in open-cell solid foams studied by X-ray tomography; and (d) defect densities and locations in molecular dynamics simulations of crystalline copper.

Heterogeneity of pericentric inversions of the human y chromosome.

Pericentric inversions of the human Y chromosome (inv(Y)) are the result of breakpoints in Yp and Yq. Whether these breakpoints occur recurrently on specific hotspots or appear at different locations along the repeat structure of the human Y chromosome is an open question. Employing FISH for a better definition and refinement of the inversion breakpoints in 9 cases of inv(Y) chromosomes, with seemingly unvarying metacentric appearance after banding analysis, unequivocally resulted in heterogeneity of the pericentric inversions of the human Y chromosome. While in all 9 inv(Y) cases the inversion breakpoints in the short arm fall in a gene-poor region of X-transposed sequences proximal to PAR1 and SRY in Yp11.2, there are clearly 3 different inversion breakpoints in the long arm. Inv(Y)-types I and II are familial cases showing inversion breakpoints that map in Yq11.23 or in Yq11.223, outside the ampliconic fertility gene cluster of DAZ and CDY in AZFc. Inv(Y)-type III shows an inversion breakpoint in Yq11.223 that splits the DAZ and CDY fertility gene-cluster in AZFc. This inversion type is representative of both familial cases and cases with spermatogenetic impairment. In a further familial case of inv(Y), with almost acrocentric morphology, the breakpoints are within the TSPY and RBMY repeat in Yp and within the heterochromatin in Yq. Therefore, the presence of specific inversion breakpoints leading to impaired fertility in certain inv(Y) cases remains an open question.

Enzymes of the biosynthesis of octadecanoid-derived signalling molecules.

It is known that octadecanoids, i.e. jasmonic acid and related compounds are involved in plant defence reactions against (1) microbial pathogens, (2) herbivores and (3) damage by UV-B or UV-C light as well as (4) senescence and (5) mechanotransduction. Jasmonic acid is likely to occur ubiquitously in the plant kingdom, and it has also been found in some fungi. The pathway of octadecanoid biosynthesis was elucidated in the early 80s by Vick and Zimmerman. This review summarizes recent progress in the identification and characterization of octadecanoid biosynthetic enzymes and in the understanding of the regulation of octadecanoid biosynthesis.

Transgenic Nicotiana tabacum and Arabidopsis thaliana plants overexpressing allene oxide synthase.

Allene oxide synthase (AOS), encoded by a single gene in Arabidopsis thaliana (L.) Heynh., catalyzes the first step specific to the octadecanoid pathway. Enzyme activity is very low in control plants, but is upregulated by wounding, octadecanoids, ethylene, salicylate and coronatine (D. Laudert and E.W. Weiler, 1998, Plant J 15: 675-684). In order to study the consequences of constitutive expression of AOS on the level of jasmonates, a complete cDNA encoding the enzyme from A. thaliana was constitutively expressed in both A. thaliana and tobacco (Nicotiana tabacum L.). Overexpression of AOS did not alter the basal level of jasmonic acid; thus, output of the jasmonate pathway in the unchallenged plant appears to be strictly limited by substrate availability. In wounded plants overexpressing AOS, peak jasmonate levels were 2- to 3-fold higher compared to untransformed plants. More importantly, the transgenic plants reached the maximum jasmonate levels significantly earlier than wounded untransformed control plants. These findings suggest that overexpression of AOS might be a way of controlling defense dynamics in higher plants.

12-Oxophytodienoate reductase 3 (OPR3) is the isoenzyme involved in jasmonate biosynthesis.

In addition to OPR1 and OPR2, two isoenzymes of 12-oxophytodienoate reductase, a third isoform (OPR3) has recently been identified in Arabidopsis thaliana (L.) Heynh. The expression of the OPR3 gene is induced not only by a variety of stimuli, such as touch, wind, wounding, UV-light and application of detergent, but also by brassinosteroids. The three enzymes were expressed in a functional form in Escherichia coli, and OPR2 was additionally expressed in insect cell cultures and overexpressed in A. thaliana. Substrate conversion was analyzed using a stereospecific assay. The results show that OPR3 effectively converts the natural (9S,13S)-12-oxophytodienoic acid [Km = 35 microM, Vmax 53.7 nkat (mg protein)-1] to the corresponding 3-2(2'(Z)-pentenyl) cyclopentane-1-octanoic acid (OPC-8:0) stereoisomer while OPR1 and OPR2 convert (9S,13S)-12-oxophytodienoic acid with greatly reduced efficiency compared to OPR3. Thus, OPR3 is the isoenzyme relevant for jasmonate biosynthesis.

12-Oxophytodienoate-10,11-reductase: occurrence of two isoenzymes of different specificity against stereoisomers of 12-oxophytodienoic acid

The reduction of 12-oxophytodienoic acid (OPDA) to 3-oxo-2(2'[Z]-pentenyl)-cyclopentane-1-octanoic acid is catalyzed by 12-oxophytodienoate-10,11-reductase (OPR). Analysis of the isomer preference of OPR has indicated that the activity is composed of two isoenzymes exhibiting different stereoselectivities. The two isoforms of OPR have been separated, using protein extracts of Rock Harlequin (Corydalis sempervirens) as the starting material. OPRI, the enzyme reported earlier from the same species and corresponding to the cloned OPR from Arabidopsis, utilized 9R,13R-OPDA >> 9S, 13R-OPDA but not the 13S-configured isomers, whereas the new activity, OPRII, effectively reduced all four OPDA isomers, including the natural 9S,13S-OPDA (cis-[+]-OPDA). OPRII activity is characterized in detail. The enzyme's enzymatic, biochemical, and immunological properties prove that it is a close relative of OPRI. The roles of OPRI and OPRII in octadecanoid biology are discussed.

Left ventricular wall thickening does occur in elite power athletes with or without anabolic steroid Use.

Reports on the occurrence of left ventricular wall thickening in resistance-trained athletes have rejected the possibility for this physiological adaptation to occur without concomitant anabolic steroid abuse. Others have concluded short bursts of arterial hypertension that occur with maximal weight lifting are not sufficient to induce left ventricular wall thickening, and left ventricular wall thickness >/=13 mm should not be found in pure resistance-trained athletes. Therefore, we examined 4 elite resistance-trained athletes by two-dimensional echocardiography. In addition, we retrospectively examined the individual left ventricular dimensions of 13 bodybuilders from our previous echocardiographic studies. All 4 elite resistance-trained athletes had left ventricular wall thicknesses beyond 13 mm. One of the elite bodybuilders has the largest left ventricular wall thickness (16 mm) ever reported in a power athlete. Retrospectively, 43% of the drug-free bodybuilders and 100% of the steroid users had left ventricular wall thickness beyond the normal range of 11 mm. In addition, 1 drug-free subject and 3 steroid users were beyond the critical mark of 13 mm. No subjects demonstrated diastolic dysfunction. In contrast to previous reports, we have demonstrated that left ventricular wall thicknesses >/=13 mm can be found routinely in elite resistance-trained athletes. The use of anabolic steroids concomitant with intensive resistance exercise does appear to augment left ventricular size without dysfunction. Anabolic steroids may accelerate left ventricular wall thickening indirectly by increasing strength, thus augmenting the pressor response.

Aortic valve thickening associated with power training: is it pressure overload?

This is a first report of aortic valve thickening secondary to intermittent hypertensive episodes experienced with weight lifting.

Molecular cloning and characterization of 12-oxophytodienoate reductase, an enzyme of the octadecanoid signaling pathway from Arabidopsis thaliana. Structural and functional relationship to yeast old yellow enzyme.

Using partial amino acid sequence information for 12-oxophytodienoate-10,11-reductase obtained from Corydalis sempervirens we have cloned the homologous enzyme from Arabidopsis thaliana. The open reading frame of the cDNA encodes a polypeptide of 372 amino acids (Mr = 41,165) with significant similarity to the sequence of Old Yellow Enzyme from Saccharomyces carlsbergensis (Saito, K., Thiele, D. J., Davio, M., Lockridge, O., and Massey, V. (1991) J. Biol. Chem. 266, 20720-20724), a flavin (FMN)-protein catalyzing the NADPH-dependent reduction of the olefinic bond of alpha,beta-unsaturated carbonyls. Specifically, all residues required for binding of FMN in Old Yellow Enzyme are conserved in the A. thaliana sequence, as are all residues associated with catalytic activity. The enzyme was functionally expressed from its cDNA in Escherichia coli and thus proven to encode OPDA reductase. Further similarities of OPDA reductase and yeast Old Yellow Enzyme include their binding to and elution by reductant from N-(4-hydroxybenzoyl)aminohexyl-Sepharose, the immunoreactivity of yeast Old Yellow Enzyme with an antiserum raised against plant OPDA reductase and the demonstration that Old Yellow Enzyme is an active OPDA reductase. It is thus conceivable that the physiological role of Old Yellow Enzymes now known from bacteria, yeasts, and higher plants, is in oxylipin metabolism.

Left ventricular size and function in elite bodybuilders using anabolic steroids.

OBJECTIVE: To investigate the relationship between resistance training, anabolic steroid use, and left ventricular function. DESIGN: Sixteen competitive bodybuilders were recruited for an echocardiography study. SETTING: University of North Texas Health Science Center (Fort Worth, TX, U.S.A.); the cardiologist and technician were blinded as to subjects' drug status. SUBJECTS: Eight competitive heavyweight drug-free (DF) bodybuilders and eight competitive heavyweight body-builders on self-directed regimens of anabolic steroids. RESULTS: Average body mass indexes (BMI; kg/m2) for the drug-user (DU) and DF groups were not significantly different (34.1 +/- 2.8 and 32.0 +/- 4.3, respectively). Increases in left ventricular posterior wall and ventricular septal thickness were apparent in the DU group (p < 0.05). The ratio of echocardiographic findings to BMI revealed a significantly smaller left ventricular end-diastolic dimension (LVDEd/BMI; p < 0.05) in the DU group. The smaller LVDEd in DUs is coupled with a significantly disproportionate septal and posterior wall thickness in DUs when indexed to body mass compared to DFs. There was no direct evidence of diastolic dysfunction detected by mitral inflow velocity patterns. CONCLUSION: Anabolic steroids may potentiate concentric left ventricular hypertrophy with decreasing ventricular compliance without affecting cardiac function.

Enzymes of octadecanoid biosynthesis in plants--12-oxo-phytodienoate 10,11-reductase.

Octadecanoids, potent cyclic plant signaling molecules derived from alpha-linolenic acid, are involved in the regulation of a multitude of physiological processes such as senescence, herbivore and pathogen defense, mechanoperception and morphogenesis. The first cyclic intermediate in the Vick-Zimmerman pathway of octadecanoid biosynthesis is 12-oxo-phytodienoic acid. Its conversion to the end product of the pathway, jasmonic acid, a C12 compound, first proceeds through reduction to 3-oxo-2-(pent-2'-enyl)-cyclopentane-1-octanoic acid, which is then converted to jasmonic acid by three cycles of beta-oxidation. The first of these conversions is a decisive point in the biosynthetic sequence, in that it channels the octadecanoid into the pathway of beta-oxidation. 12-Oxo-phytodienoate reductase was purified to apparent homogeneity from a cell suspension culture of Corydalis sempervirens. The enzyme is soluble and a monomer of apparent molecular mass 41 kDa which prefers NADPH over NADH to reduce the 10,11-double bond of 12-oxo-phytodienoic acid. The structure of the reaction product was proved by derivatization, GC/MS and NMR analysis. The enzyme accepts both the cis and the trans isomer of 12-oxo-phydodienoic acid, with a preference for the cis-isomer (6:1). 12-Oxo-phytodienoate reductase will also convert the synthetic substrate 2-cyclohexenone to cyclohexanone, but the enzyme did not reduce some other cyclic alpha,beta-unsaturated ketones tested (the plant hormone abscisic acid or the steroids testosterone and progesterone). Characteristic parameters of 12-oxo-phytodienoate reductase were determined.

Clonal propagation of Isoplexis canariensis.

Isoplexis is a plant genus closely related to Digitalis. Members of this genus contain cardenolides considered more "primitive" than those present in Digitalis. Isoplexis plants, tissue cultures, and isolated cardenolides may thus be used to elucidate the biosynthesis of cardenolides in the Scrophulariaceae. Therefore, a method was developed to cultivate and propagate Isoplexis canariensis (L.) Lindl. ex. G. Don in vitro. Seeds were germinated in liquid modified MS medium and shoot cultures were established and propagated in liquid modified MS medium containing 0.1 mg/l IAA and 1 mg/l BAP. Shoot cultures were also established from excised axillary buds and propagated on solid culture medium containing 0.1 mg/l IAA and 1 mg/l BAP. Shoots of either origin were rooted in medium containing 1 to 5 mg/l IAA and 0.5 to 4 mg/l IBA. Rooted plantlets were cultivated for 2 to 3 weeks in hormone-free modified MS medium and then transferred to the greenhouse, where they developed into healthy plants.