Interleukin-8 (IL-8), melanoma growth-stimulatory activity, and neutrophil-activating peptide selectively mediate priming of the neutrophil NADPH oxidase through the type A or type B IL-8 receptor

The capacity of neutrophils to generate superoxide (O-2) can be enhanced by prior exposure to "priming" agents such as interleukin-8 (IL-8), melanoma growth-stimulatory activity (MGSA), and neutrophil-activating peptide (ENA-78). The biological effects of these chemokines are mediated by at least two distinct receptors: type A (IL-8-RA) and type B (IL-8-RB). Using neutralizing monoclonal antibodies to IL-8-RA and IL-8-RB, we have investigated the contribution each receptor makes to the priming response. Preincubation with IL-8, MGSA, or ENA-78 enhanced the ability of neutrophils to generate O-2 following stimulation with the bacterial peptide formyl-Met-Leu-Phe. The priming effect of IL-8 was eliminated by an anti-IL-8 monoclonal antibody (mAb) that is known to bind IL-8 with high affinity and prevent receptor occupancy. Incubation of neutrophils with a neutralizing mAb specific for IL-8-RA blocked IL-8-induced priming but had no effect on priming by MGSA or ENA-78. In contrast, treatment with a neutralizing mAb specific for IL-8-RB failed to inhibit the priming effect of IL-8 but blocked both MGSA and ENA-78-induced priming. These observations indicate that the priming effect of IL-8 on the neutrophil respiratory burst is predominantly mediated via IL-8-RA, whereas priming by MGSA and ENA-78 is mediated by IL-8-RB.     

Osteolytic form of Paget's disease. Differential diagnosis and pathogenesis

Of fourteen patients with Paget's disease for whom adequate roentgenograms and pathological material were available, six had lesions showing significant or predominant osteolysis. Based on a study of these six patients and a review of the literature, the following mechanisms were identified as causes of the so-called osteolytic type of the disease: (1) an "early" destructive Paget's lesion; (2) "advanced" Paget's disease with secondary degenerative changes; (3) "seeding" of an independent osteolytic lesion, particularly tumor in pre-existing Paget's disease; (4) sarcomatous transformation; and (5) immobilization after fracture. An osteolytic lesion in a patient without other bone disease may be due to Paget's disease, while an associated lytic lesion may be the result of a variety of conditions. Accurate pathological diagnosis is essential.     

Jejunal atresia with absent mesentery and a helical ileum

Of 59 infants with jejunoileal atresia, seven presented with absence of mesentery, the main superior mesenteric artery ceasing to exist beyond the origin of the right colic or ileocolic artery, and a helical ileum. This distinctive form of jejunal atresia has been recognized with increasing frequency in recent years. Distal to the atresia, the small bowel receives its blood supply retrograde from an artery derived from the ileocolic or right colic arcades, and the ileum coils around its nutrient artery in an "apple peel" or "Christmas tree" deformity. The first three patients in this report died. The lastion, but they recovered as their malabsorption gradually disappeared. The treatment includes resection of the dilated bowel, as in other atresias. Resection of part of the distal bowel may be required for additional atresias or for poor vascularity with questionable viability. Postoperative malabsorption generally requires intravenous hyperalimentation.     

Fibromuscular dysplasia of the superior mesenteric artery and coexisting cerebral berry aneurysms

Fibromuscular dysplasia of the systemic artery and cerebral "berry" (saccular) aneurysm are nonatheromatous lesions of uncertain etiology. The coexistence of these vascular disorders in the individual reported here is unusual and may provide a possible explanation of their pathogenesis.     

Admittance tympanometry in otosclerotic ears

Twenty-eight surgically confirmed otosclerotic ears were evaluated to determine whether tympanometric admittance measurements could differentiate otosclerosis from a normal population. Subjects were tympanometrically measured at test conditions B220, B660, G220 and G660 Hz. When comparing mean curve peak amplitude to normative standards, 20 ears showed significantly low admittance tympanograms. Further investigation revealed no significant differences in curve width or pressure of the curve peak. Of the remaining eight otosclerotic ears, all produced diphasic "W"-notched tympanometric configurations. Diagnostic implications and physiological hypothesis are discussed.     

The mechanical behaviour of high-impact polystyrene under pressure

High-impact polystyrene [HIPS], a two-phase polymeric system, has been investigated studying the pressure dependence of stress-elongation behaviour in tension over the range from atmospheric pressure to 4 kbar at room temperature and constant strain-rate. A comparative study of polystyrene [PS] was also undertaken. HIPS sealed from the environment exhibited ductile behaviour at all pressures. Surprisingly, specimens exposed to silicone oil environment exhibited two transitions as the applied hydrostatic pressure was raised: a ductile-to-brittle followed by a brittle-to-ductile transition. Stress-whitening was suppressed at relatively low pressures. The dilational requirement for profuse crazing was restrained by the combined effect of fluid under pressure resulting in the suppression of the energy absorption mechanism.Analysis of the stress-elongation curves for sealed specimens indicated that the pressure dependency of craze-initiation stress differs from that of shear band initiation stress. The brittle-to-ductile transition occurred when the initiation stresses of both processes became equal. The principal stress for craze initiation showed almost no pressure dependency, suggesting that crazes initiate when the principal stress level of the tensile specimen reaches a critical value irrespective of the applied hydrostatic pressure. A value for the proposed triaxial tension around the rubber particles was determined from the experimental results and found to be in good agreement with a calculated value. A general mechanics argument was used to explain the existence of the ductile-to-brittle and the brittle-to-ductile transition in HIPS, and also to predict the pressure dependencies of brittle-fracture stress and craze-initiation stress for sealed and non-sealed specimens.Nomenclature P hydrostatic pressure, here taken as always positive - BD brittle-to-ductile transition - CS craze-to-shear band transition - _T observed tensile stress - ¹ the first principal stress - _f ^s fracture stress for sealed specimens - _f ^ns fracture stress for non-sealed specimens - _y yield stress - _f fracture stress - _ci craze initiation stress     

Sociocultural factors and the development of disordered eating: A longitudinal analysis of competing hypotheses.

Sociocultural models hypothesize causal paths in the development of eating disorders, yet few longitudinal studies have controlled for temporal stability, leaving open the question as to causality and the directionality of effects. In the present study, the authors tested portions of the socioculturally based dual-pathway model, specifically, the risk factor hypotheses that internalization of the thin ideal predicts body dissatisfaction, that body dissatisfaction predicts depressive affect, and that depressive affect predicts disordered eating. The authors also examined competing hypotheses (e.g., disordered eating predicts depressive affect) as well as the possibility of simultaneous relationships (i.e., variables would be related to one another within a time frame). The 6 models (3 cross-lagged and 3 simultaneous) were evaluated using 236 female freshmen who provided self-report data during their 1st semester in college and 6 months later. While controlling for temporal stability, structural equation modeling revealed that (a) internalization and body image each were related to the other across time; (b) body image was related directionally, but only in the simultaneous context, to depressive affect; and (c) depressive affect and disordered eating were related reciprocally and temporally to one another. Directions for future research and implications for intervention are provided. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Factors Associated With Persistence in Science and Engineering Majors: An Exploratory Study Using Classification Trees and Random Forests

Many students who start college intending to major in science or engineering do not graduate, or decide to switch to a non‐science major. We used the recently developed statistical method of random forests to obtain a new perspective of variables that are associated with persistence to a science or engineering degree. We describe classification trees and random forests and contrast the results from these methods with results from the more commonly used method of logistic regression. Among the variables available in Arizona State University data, high school and freshman year GPAs have highest importance for predicting persistence; other variables such as number of science and engineering courses taken freshman year are important for subgroups of the student population. The method used in this study could be employed in other settings to identify faculty practices, teaching methods, and other factors that are associated with high persistence to a degree.     

Antioxidant-restricted diet reduces plasma nonesterified fatty acids in trained athletes

Nonesterified FA (NEFA) are a major fuel source for humans at rest and during moderate exercise. The effect of dietary antioxidant restriction on plasma NEFA levels and exercise performance in trained athletes was examined. Seventeen athletes followed a 2-wk restricted-antioxidant (R-AO) diet, which resulted in a threefold reduction in antioxidant intake (ascorbic acid, 139 to 49 mg; β-carotene, 5093 to 1142 μg) and a significant (P=0.001) reduction in the plasma NEFA. The amount and types of fat consumed were not different between the R-AO and habitual diets. Exercise time to exhaustion was not affected by the R-AO diet, but rating of perceived exertion (RPE) was significantly (P=0.03) elevated. The increase in RPE may have occurred as a result of the R-AO diet and subsequent reduction in plasma NEFA; however, further research is required to confirm this conclusion.     

Physical factors affecting kinesin-based transport of synthetic nanoparticle cargo

Recently, kinesin biomolecular motors and microtubules filaments (MTs) were used to transport metal and semiconductor nanoparticles with the long-term goal of exploiting this active transport system to dynamically assemble nanostructured materials. In some cases, however, the presence of nanoparticle cargo on MTs was shown to inhibit transport by interfering with kinesin-MT interactions. The primary objectives of this work were (1) to determine what factors affect the ability of kinesin and MTs to transport nanoparticle cargo, and (2) to establish a functional parameter space in which kinesin and MTs can support unimpeded transport of nanoparticles and materials. Of the factors evaluated, nanoparticle density on a given MT was the most significant factor affecting kinesin-based transport of nanoparticles. The density of particles was controlled by limiting the number of available linkage sites (i.e., biotinylated tubulin), and/or the relative concentration of nanoparticles in solution. Nanoparticle size was also a significant factor affecting transport, and attributed to the ability of particles < 40 nm in diameter to bind to the "underside" of the MT, and block kinesin transport. Overall, a generalized method of assembling and transporting a range of nanoparticle cargo using kinesin and MTs was established.