Prostaglandin E2 induces transcription of skeletal muscle mass regulators interleukin-6 and muscle RING finger-1 in humans.

Cyclooxygenase (COX) inhibiting drugs augment muscle mass and strength improvements during resistance exercise based treatment of sarcopenia in older individuals. Initial evidence suggests a potential mechanism of COX inhibitor blunted prostaglandin (PG) E2 stimulation of interleukin (IL)-6 and the ubiquitin ligase MuRF-1, reducing their inhibition on muscle growth. The purpose of this investigation was to determine if PGE2 stimulates IL-6 and MuRF-1 transcription in skeletal muscle. Muscle biopsies were obtained from 10 young individuals and incubated ex vivo with PGE2 or control and analyzed for IL-6 and MuRF-1 mRNA levels. PGE2 upregulated (P<0.05) expression of both IL-6 (195%) and MuRF-1 (51%). A significant relationship was found between IL-6 and MuRF-1 expression after incubation with PGE2 (r=0.77, P<0.05), suggesting regulation through a common pathway. PGE2 induces IL-6 and MuRF-1 transcription in human skeletal muscle, providing a mechanistic link between COX inhibiting drugs, PGE2, and the regulation of muscle mass.

Influence of aerobic cycle exercise training on patellar tendon cross-sectional area in older women.

Nine to 12 weeks of resistance exercise training in young individuals induces quadriceps muscle (∼6%) and region-specific patellar tendon (4-6%) hypertrophy. However, 12 weeks of resistance exercise training (∼1 h total exercise time) in older individuals (60-78 years) induces quadriceps muscle hypertrophy (9%) without impacting patellar tendon size. The current study examined if a different loading paradigm using cycle exercise would promote patellar tendon hypertrophy or alter the internal tendon properties, measured with magnetic resonance imaging signal intensity, in older individuals. Nine women (70 ± 2 years) completed 12 weeks of aerobic upright cycle exercise training (∼28 h total exercise time). Aerobic exercise training increased (P < 0.05) quadriceps muscle size (11 ± 2%) and VO2max (30 ± 9%). Mean patellar tendon cross-sectional area (CSA) (2 ± 1%) and signal intensity (-1 ± 2%) were unchanged (P > 0.05) over the 12 weeks of training. Region-specific CSA was unchanged (P > 0.05) at the proximal (-1 ± 3%) and mid regions (2 ± 2%) of the tendon but tended (P = 0.069) to increase at the distal region (5 ± 3%). Region-specific signal intensity differed along the tendon but was unchanged (P > 0.05) with training. Although more studies are needed, exercise-induced patellar tendon hypertrophy, compared with skeletal muscle, appears to be attenuated in older individuals, while the loading pattern associated with aerobic exercise seems to have more impact than resistance exercise in promoting patellar tendon hypertrophy.

A comparison of frequency and sources of nursing job stress perceived by intensive care, hospice and medical-surgical nurses.

This study compared the frequency and sources of nursing job stress perceived by 35 intensive care (ICU), 30 hospice and 73 medical-surgical nurses. Analysis of variance revealed no significant differences among the three groups of nurses on the overall frequency of job stress. Post-hoc Tukey tests demonstrated a significant difference in three stress subscales among the three groups. ICU and hospice nurses perceived significantly more stress than medical-surgical nurses related to death and dying; ICU and medical-surgical nurses perceived significantly more stress than hospice nurses related to floating; and medical-surgical nurses perceived significantly more stress than ICU and hospice nurses related to work-overload/staffing. Spearman-Rank Correlation revealed no significant correlations among the three groups in their rank-ordering of the eight stress subscales. Death and dying situations were the most stressful to ICU and hospice nurses, while work-overload/staffing situations were the most stressful to medical-surgical nurses. Results of the study, although not generalizable, have implications for nurse managers.

Polarization characteristics of noncircular core single-mode fibers.

It is well known that geometrical or dielectric imperfections in conventional graded-index single-mode fibers depolarize light after a few centimeters. A slight improvement in the polarization performance of these fibers is achieved by introducing noncircularity in the core shape. This is evident from the measurements on borosilicate fibers with dumbbell shaped cores. This result is correlated with Marcatili's analysis, which shows that changing the core geometry, from square to rectangular, does not appreciably alter the difference in the propagation constants of the two fundamental modes with orthogonal polarizations. Thus, the noncircular geometry and the associated increase in stress-induced birefringence introduced during the manufacturing process alone are not sufficient to improve the polarization performance, and the enhancement of the anisotropic birefringence is necessary to achieve single-polarization fibers.

Viewing refractive-index profiles and small-scale inhomogeneities in glass optical fibers: some techniques.

Methods which have proved to be useful for measuring core-cladding refractive-index differences, for approximating refractive-index profiles, and for viewing various inhomogeneities in solid multimode optical fibers are described. Optical, transmission-interference, and scanning-electron-beam microscopy have been used, and the illustrations include examples of photomicrographs made by each of these techniques.

Properties of ion-bombarded fused quartz for integrated optics.

Development of techniques for production of carefully controlled, low-loss optical waveguides in solid dielectric materials is essential to development of integrated optical circuits for signal processing in future optical communications systems. Ion implantation offers an attractive possibility because of the refractive index and film thickness control possible by this technique. To evaluate this possibility we have investigated some of the optical properties of ion-bombarded fused quartz. A variety of ions ranging from helium ions to bismuth ions has been used. We have concentrated on refractive index and optical loss variations (on those implants into which a beam could be launched) as effected by (1) ion species and dose, (2) surface preparation, (3) surface temperature during bombardment, and (4) postbombardment annealing. This paper does not attempt to give an inclusive account of all the results obtained but principally discusses the best results so far, which are those using lithium ions. For lithium ion bombardment we have observed approximately linear variation of refractive index at 6328 A with dose n = n(0) + 2.1 x 10(-21)C, where n(0) is the prebombardment value (= 1.458 for fused quartz), and C is the ion concentration in ions/cm(3) (C < 2.2 x 10(19)). The optical absorption decreases significantly with increase in substrate temperature during implantation, and losses less than 0.2 dB/cm have been achieved. The refractive index change appears to be primarily due to disorder produced by the incident particles rather than a chemical doping effect as evidenced by postbombardment annealing studies.

Silicon oxynitride films on fused silica for optical waveguides.

We have evaluated chemical vapor-deposited silicon oxynitride films on fused silica as a potential integrated optics medium. Refractive index of these glassy films depends on composition, which is adjusted by controlling the ratio of the nitric oxide and silane reactants. Films of n = 1.48-1.54 had losses <0.4 dB/cm at 633 nm. The preparation of the fused silica substrate surface and other precautions to minimize scattering centers ape discussed.

Effect of refractive index gradients on index measurement by the abeles method.

Abeles's method of determining the refractive index of a thin film is discussed. Attention is directed to the effect of a graded index transition between the film and the substrate on the measured index. First, a closed-form analysis of the problem for a long transition region is given. This is followed by a computer analysis applicable to transition regions of any length.

Performance of an 11-GHz Optical Modulator Using LiTaO(3).

An 11-GHz optical modulator using LiTaO(3) as the electrooptic material has been designed and built. The experimental model has a bandwidth of about 100 mHz and is tunable over 1.5 GHz with uniform modulation characteristics. A phase modulation index of 0.45 rad was achieved with 1.6 W of modulating power.