Upper-limb exercise in tetraplegia using functional electrical stimulation

Cervical spinal cord injury can result in dysfunction in both the lower and upper limbs (tetraplegia), andmay be accompanied by a range of secondary complications. The degree of upper-limb dysfunctiondepends upon the level and completeness of the lesion; in this paper we consider tetraplegics with a neurological level in the range C4-C6. A person with a C5- or C6-level injury will generally retain control of the shoulder and elbow flexor muscles biceps), but will have no control of the hand, wrist or elbow extensors (triceps).With a complete C4 injury voluntary control of the entire arm is lost. Thus, we propose that functional electrical stimulation (FES) of the biceps and triceps muscles may enhance the efficacy of cyclical upper-limb exercise. Alternatives for partial restoration of function include tendon transfer surgery or mechanical orthoses1. Previous FES research for C4-C6 tetraplegics has focused on systems for hand function2,3 and improved working area (i.e. overhead reach)4,5,6,7, but the provision of upper-limb exercise modalities using FES assistance has been neglected. This is important because the lack of effective exercise can lead rapidly to severe cardiopulmonary deconditioning in this population

Arm-cranking exercise assisted by Functional Electrical Stimulation in C6 tetraplegia: a pilot study

Tetraplegic volunteers undertook progressive exercise training, using novel systems for arm-cranking exercise assisted by Functional Electrical Stimulation (FES). The main aim was to determine potential training effects of FES-assisted arm-crank ergometry (FES-ACE) on upper limb strength and cardiopulmonary {fitness} in tetraplegia. Surface FES was applied to the biceps and triceps during exercise on an instrumented ergometer. Two tetraplegic volunteers with C6 Spinal Cord Injury (SCI) went through muscle strengthening, baseline exercise testing and three months of progressive FES-ACE training. Repeat exercise tests were carried out every four weeks during training, and post-training, to monitor upper-limb strength and cardiopulmonary fitness. At each test point, an incremental test was carried out to determine peak work rate, peak oxygen uptake, gas exchange threshold and oxygen uptake-work rate relationship during FES-ACE. Peak oxygen uptake for Subject A increased from 0.7 l/min to 1.1 l/min, and peak power output increased from 7 W to 38 W after FES-ACE training. For Subject B, peak oxygen uptake was unchanged, but peak power output increased from 3 W to 8 W. These case studies illustrate potential benefits of FES-ACE in tetraplegia, but also the differences in exercise responses between individuals. Keywords: electrical stimulation; spinal cord injury; cardiopulmonary fitness; rehabilitation; tetraplegi

Mitochondria Dysfunction in Lung Cancer-Induced Muscle Wasting in C2C12 Myotubes

Aims: Cancer cachexia is a syndrome which results in severe loss of muscle mass and marked fatigue. Conditioned media from cachexia-inducing cancer cells triggers metabolic dysfunction in skeletal muscle, including decreased mitochondrial respiration, which may contribute to fatigue. We hypothesized that Lewis lung carcinoma conditioned medium (LCM) would impair the mitochondrial electron transport chain (ETC) and increase production of reactive oxygen species, ultimately leading to decreased mitochondrial respiration. We incubated C2C12 myotubes with LCM for 30 min, 2, 4, 24 or 48 h. We measured protein content by western blot; oxidant production by 2′,7′-dichlorofluorescin diacetate (DCF), 4-amino-5-methylamino-2′,7′-difluorofluorescein diacetate (DAF), and MitoSox; cytochrome c oxidase activity by oxidation of cytochrome c substrate; and oxygen consumption rate (OCR) of intact myotubes by Seahorse XF Analyzer. Results: LCM treatment for 2 or 24 h decreased basal OCR and ATP-related OCR, but did not alter the content of mitochondrial complexes I, III, IV and V. LCM treatment caused a transient rise in reactive oxygen species (ROS). In particular, mitochondrial superoxide (MitoSOX) was elevated at 2 h. 4-Hydroxynonenal, a marker of oxidative stress, was elevated in both cytosolic and mitochondrial fractions of cell lysates after LCM treatment. Conclusion: These data show that lung cancer-conditioned media alters electron flow in the ETC and increases mitochondrial ROS production, both of which may ultimately impair aerobic metabolism and decrease muscle endurance

Identifying Young Brown Dwarfs Using Gravity-Sensitive Spectral Features

We report the initial results of the Brown Dwarf Spectroscopic Survey Gravity Project, to study gravity sensitive features as indicators of youth in brown dwarfs. Low-resolution (R~2000) J-band and optical (R~1000) observations using NIRSPEC and LRIS at the W.M. Keck Observatory reveal transitions of TiO, VO, K I, Na I, Cs I, Rb I, CaH, and FeH. By comparing these features in late-type giants and in old field dwarfs we show that they are sensitive to the gravity (g = GM/R^2) of the object. Using low-gravity spectral signatures as age indicators, we observed and analyzed J-band and optical spectra of two young brown dwarfs, G 196-3B (20-300 Myr) and KPNO Tau-4 (1-2 Myr), and two possible low mass brown dwarfs in the sigma Orionis cluster (3-7 Myr). We report the identification of the phi bands of TiO near 1.24 microns and the A-X band of VO near 1.18 microns together with extremely weak J-band lines of K I in KPNO-Tau4. This is the first detection of TiO and VO in the J-band in a sub-stellar mass object. The optical spectrum of KPNO-Tau4 exhibits weak K I and Na I lines, weak absorption by CaH, and strong VO bands, also signatures of a lower gravity atmosphere. G 196-3B shows absorption features in both wavelength regions like those of KPNO-Tau4 suggesting that its age and mass are at the lower end of published estimates. Whereas sigma Ori 51 appears to be consistent with a young sub-stellar object, sigma Ori 47 shows signatures of high gravity most closely resembling an old L1.5/L0, and can not be a member of the sigma Orionis cluster.Comment: 14 pages, 4 figures. To appear in the January 10, 2004 issue of the Astrophysical Journa

The NIRSPEC Brown Dwarf Spectroscopic Survey II: High-Resolution J-Band Spectra of M, L and T Dwarfs

We present a sequence of high resolution (R~20,000 or 15 km/s) infrared spectra of stars and brown dwarfs spanning spectral types M2.5 to T6. Observations of 16 objects were obtained using eight echelle orders to cover part of the J-band from 1.165-1.323 micron with NIRSPEC on the Keck II telescope. By comparing opacity plots and line lists, over 200 weak features in the J-band are identified with either FeH or H2O transitions. Absorption by FeH attains maximum strength in the mid-L dwarfs, while H2O absorption becomes systematically stronger towards later spectral types. Narrow resolved features broaden markedly after the M to L transition. Our high resolution spectra also reveal that the disappearance of neutral Al lines at the boundary between M and L dwarfs is remarkably abrupt, presumably because of the formation of grains. Neutral Fe lines can be traced to mid-L dwarfs before Fe is removed by condensation. The neutral potassium (K I) doublets that dominate the J-band have pressure broadened wings that continue to broaden from ~50 km/s (FWHM) at mid-M to ~500 km/s at mid-T. In contrast however, the measured pseudo-equivalent widths of these same lines reach a maximum in the mid-L dwarfs. The young L2 dwarf, G196-3B, exhibits narrow potassium lines without extensive pressure-broadened wings, indicative of a lower gravity atmosphere. Kelu-1AB, another L2, has exceptionally broad infrared lines, including FeH and H2O features, confirming its status as a rapid rotator. In contrast to other late T objects, the peculiar T6 dwarf 2MASS 0937+29 displays a complete absence of potassium even at high resolution, which may be a metallicity effect or a result of a cooler, higher-gravity atmosphere.Comment: 53 pages, 21 figures, data will be available at http://www.astro.ucla.edu/~mclean/BDSSarchive

EGZOENCIMI U HRANI ZA RIBE S POSEBNIM OSVRTOM NA FITAZU: PREGLED

The global aquaculture industry has come under increasing pressure to optimize production efficiency while reducing environmental loadings. These new demands, which have been accompanied in certain countries by legislation, have stimulated the development of elite low output dietary formulations. Several feed manufacturers have developed diets with modified energy: protein ratios, which reduce environmental phosphorus loadings with minimum impact upon fish growth. However, problems relating to end product quality have materialized following application of these high lipid diets and it is clear that alternative strategies must be developed. In particular, there remains an urgent need to replace the expensive fishmeal component of aquafeeds. One approach might be to supplement diets with exogenous enzymes (exoenzymes) that enhance the value and utility of alternative, low grade proteins while reducing ecological impacts. This paper briefly reviews the literature relating to experimental exoenzyme aquafeeds, with specific reference to phytase.Kompletna industrija akvakulture nalazi se pod povećanim pritiskom glede optimalizacije efikasne proizvodnje, dok se u isto vrijeme smanjuju mogućnosti iskorištavanja akvatorija. Ovi, novi zahtjevi koji su u nekim zemljama povezani s legislativom, potaknuli su razvoj niskih iskorištenosti hranidbenih formulacija. Nekoliko proizvođaća razvilo je hrane s modificiranom energijom: količina bjelančevina koja smanjuje nakupljanje P a okolišu s minimalnim utjecajem na rast riba. No, problemi koji se odnose na kvalitetu gotovoga proizvoda materijalirizirani su uporabom hrana s visokim postotkom lipida i jasno je da mora biti razvijena alternativna strategija, napose stoga što ostaje urgentna potreba za zamjenu skupog ribljeg brašna kao komponente u hrani za ribe. Jedna od mogućnosti mogla bi biti dodatak egzogenih enzima (egzoenzima) koji povećavaju vrijednost i iskorištenost nisko vrijednih bjelančevina. U ovom je radu dan kratak prikaz literaturnih podataka koji se odnose na eksperimentalne hrane s egzoenzimima, s posebnim osvrtom na fitazu