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We successfully observed 191 near-Earth asteroids using the Arecibo Observatory’s S-band planetary radar system from 2017 December through 2019 December. We present radar cross sections for 167 asteroids; circular-polarization ratios for 112 asteroids based on Doppler-echo-power spectra measurements; and radar albedos, constraints on size and spin periods, and surface-feature and shape evaluation for 37 selected asteroids using delay-Doppler radar images with a range resolution of 75 m or finer. Out of 33 asteroids with an estimated effective diameter of at least 200 m and sufficient image quality to give clues of the shape, at least 4 (∼12%) are binary asteroids, including 1 equal-mass binary asteroid, 2017 YE5, and at least 10 (∼30%) are contact-binary asteroids. For 5 out of 112 asteroids with reliable measurements in both circular polarizations, we measured circular-polarization ratios greater than 1.0, which could indicate that they are E-type asteroids, while the mean and the 1σ standard deviation were 0.37 ± 0.23. Further, we find a mean opposite-sense circular-polarization radar albedo of 0.21 ± 0.11 for 41 asteroids (0.19 ± 0.06 for 11 S-complex asteroids). We identified two asteroids, 2011 WN15 and (505657) 2014 SR339, as possible metal-rich objects based on their unusually high radar albedos, and discuss possible evidence of water ice in 2017 YE5.

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We conducted radar observations of near-Earth asteroid 2019 OK on 2019 July 25 using the Arecibo Observatory S-band (2380 MHz, 12.6 cm) planetary radar system. Based on Arecibo and optical observations the apparent diameter is between 70 and 130 m. Combined with an absolute magnitude of H = 23.3 ± 0.3, the optical albedo of 2019 OK is likely between 0.05 and 0.17. Our measured radar circular polarization ratio of μ C = 0.33 ± 0.03 indicates 2019 OK is likely not a V- or E-type asteroid and is most likely a C- or S-type. The measured radar echo bandwidth of 39 ± 2 Hz restricts the apparent rotation period to be approximately between 3 minutes (0.049 hr, D = 70 m) and 5 minutes (0.091 h, D = 130 m). Together, the apparent diameter and rotation period suggest that 2019 OK is likely not a rubble-pile body bound only by gravity. 2019 OK is one of a growing number of fast-rotating near-Earth asteroids that require some internal strength to keep them from breaking apart.

Radar remote sensing is a powerful tool used to image planets, moons, asteroids, and comets with ground-based and orbital instruments. Variations in the backscatter coefficient, or albedo, are related to changes in the near-surface properties. Analyses of radar albedos have revealed polar ice deposits on Mercury (Slade et al., 1992), identified methane lakes on Titan (Stofan et al., 2007), and provided evidence for the ice crusts of Europa, Ganymede, and Callisto (Ostro et al., 1992). Interpretations of radar albedos of asteroids have been used to infer metallic composition, such as for 16 Psyche (Magri et al., 1999), the possible remnant metallic core that is the target of NASA’s Psyche mission. Analyses that combine measurements of radar albedos of asteroids with dielectric models have been used to determine the near-surface porosity of asteroids (Magri et al., 2001; Hickson et al., 2020). In these models, the radar albedo is used to determine the Fresnel reflectivity of the near-surface, which can then be used to determine the complex index of refraction of the near-surface material, n=√εµ. The index of refraction is a function of the complex permittivity, ε, and the complex permeability, µ. Most minerals are paramagnetic, with permeabilities approaching that of vacuum. As such, many interpretations of the Fresnel reflectivity of planetary surfaces are predominantly concerned with the permittivity. However, some iron oxide minerals are ferromagnetic, and possess permeabilities that can be significantly greater than that of vacuum. The importance of these minerals in interpreting radar backscatter has been identified for Mars, for which iron oxide minerals such as magnetite, hematite, and goethite have been identified in the regolith (Stillman 2006). Earth-based spectroscopic observations of near-Earth asteroid 101955 Bennu, the target of NASA’s OSIRIS-REx mission, hinted at the presence of magnetite on the surface (Cloutis et al., 2013). Spectral data obtained by the OSIRIS-REx spacecraft have recently corroborated these early Earth-based observations (Hamilton et al., 2019). These data, combined with compositional analyses of analogue CI/CM carbonaceous chondrite meteorites, indicate that the surface of Bennu could be comprised up to 10% by magnetite. In this study, we model the effect of magnetic iron oxides on the radar albedo of asteroids. Since the iron oxide abundance on asteroids is not well understood, we use Bennu as a test case. Laboratory measurements of the magnetic permeability of magnetite have been carried out by several authors, including Pettinelli et al., 2005, Cereti et al., 2007, and Stillman 2006 with application to orbital sounding radar of Mars. The measured permeability in these studies can be extrapolated to a volume fraction of magnetite of 10%, relevant for Bennu as mentioned above, using effective medium approximations. Figure 1 shows the measurements of magnetic permeability of various magnetite mixtures from Pettinelli et al., 2005 and Cereti et al., 2007 fit with the Bruggeman Symmetric mixing model using a permeability of 5.5 for the magnetite phase. Figure 1: Magnetite mixture permeability measurements from the literature fitted with the Bruggeman Symmetric effective medium model. At 10% magnetite, this model predicts an effective permeability of 1.21. This corresponds to an increase of the index of refraction by a factor of √1.21 = 1.1, or 10%. For a smooth surface at normal incidence, the radar albedo, σ, is equal to the Fresnel reflectivity: σ = abs((√εµ - 1)/(√εµ + 1))^2. Ignoring the imaginary part (which is often significantly lower than the real part), for a permittivity of 3 and permeability of 1 the above equation gives a radar albedo of σ = 0.072. If we further assume that this surface is comprised of 10% magnetite (and assume that the magnetite’s permittivity has already been incorporated into the effective permittivity of 3), changing the effective permeability to 1.21 increases the radar albedo to σ = 0.097. In this simple example, considering the magnetic effect of 10% magnetite increased the radar albedo by 35% compared with a strictly dielectric model. We have shown through laboratory measurements from the literature and electromagnetic modeling that iron oxides can increase radar albedos of asteroids appreciably due to their magnetic properties. These magnetic properties must be better understood in the context of asteroids, and their abundances better characterized, for improved interpretation of planetary radar datasets. References: Cereti, A., et al. (2007). Electromagnetic measurements on Martian soil analogs: Implications for MARSIS and SHARAD radars in detecting subsoil water. Planetary and Space Science, 55(1-2), 193-202. Cloutis, E. A., et al. (2013). Possible Causes of Blue Slopes (~ 0.5-2.5 µm) in Carbonaceous Chondrite Spectra. LPI, (1719), 1550. Hamilton, V. E., et al. (2019). Evidence for widespread hydrated minerals on asteroid (101955) Bennu. Nature Astronomy, 3(4), 332-340. Hickson, D. C., et al. Modeling the Dielectric Properties of Minerals from Crystals to Bulk Powders for Improved Interpretation of Asteroid Radar Observations. Journal of Geophysical Research: Planets, e2019JE006141. Magri, C., et al. (1998). Mainbelt asteroids: Results of Arecibo and Goldstone radar observations of 37 objects during 1980-1995. Magri, C., et al. (2001). Radar constraints on asteroid regolith properties using 433 Eros as ground truth. Meteoritics & Planetary Science, 36(12), 1697-1709. Ostro, S. J., et al. (1992). Europa, Ganymede, and Callisto: new radar results from Arecibo and Goldstone. Journal of Geophysical Research: Planets, 97(E11), 18227-18244. Pettinelli, E., et al. (2005). Laboratory investigations into the electromagnetic properties of magnetite/silica mixtures as Martian soil simulants. Journal of Geophysical Research: Planets, 110(E4). Slade, M. A., et al. (1992). Mercury radar imaging: Evidence for polar ice. Science, 258, 635 – 640. Stillman, D.E. (2006) Frequency and Temperature Dependence in Electromagnetic Properties of Martian Analog Minerals. Doctoral Thesis, Colorado School of Mines. Stofan, E. R., et al. (2007). The lakes of Titan. Nature, 445(7123), 61-64.

We conducted an observational radiographic study to determine the inter- and intra-observer reliability of the AO classification of fractures of the distal radius. Plain posteroanterior and lateral radiographs of 456 patients with an acute fracture of the distal radius were classified by a consultant orthopaedic hand specialist and two specialist trainees, and the k coefficient for the inter- and intra-observer reliability of the type, group and subgroup classification was calculated. Only the type of fracture (A, B or C) was found to provide substantial intra-observer reliability (k type 0.65). The inclusion of ‘group’ and ‘subgroup’ into the classification reduced the inter-observer reliability to fair (kgroup 0.29, ksubgroup = 0.28) and the intra-observer reliability to moderate (kgroup 0.53, ksubgroup 0.49). Disagreement was found to arise between specific subgroups, which may be amenable to clarification. Cite this article: Bone Joint J 2015; 97-B:818–23.

Introduction/Aims Patient care in general practice is mostly autonomous with infrequent exposure to clinical emergencies. The aim of in situ simulation was to build confidence in managing these scenarios, encourage multi professional team working using practice equipment within the surgery environment. Clinical emergencies provoke anxiety to GP surgery staff as exposure is low and infrequent. Method The simulation was conducted in a busy training GP surgery. 2 medical emergency scenarios were run in real-time. 14 staff participated (4 GPs, 2 GP Registrars, 3 practice nurses, 1 student nurse, 1 Health care assistant and 3 receptionists). The sessions focused on a structured approach to clinical emergency and human factors. It was conceptualised so that participants would gain confidence to transfer and apply learning to other emergencies. Pre and post session questionnaires were completed. The main covet of the debriefing was to encourage reflections from team members, identify existing latent threats in their existing systems and empower them to explore ways of improving management. Results The sessions were widely well received. All members of the team valued the session with 93% of candidates rating ‘extremely useful’ and 85% stating they enjoyed (the session) very much. For the emergency topics covered, self-rated confidence scores increased by two Likert scale points, additionally other emergency topics increased by one Likert scale point. Latent safety threats that were identified included; poor awareness of emergency bag contents, the need for additional emergency bag equipment and availability and access to emergency guidelines and algorithms. The team raised interventions that they thought would be helpful, for example allocating the duty doctor to bring their own personal doctors bag to the patient which would include observation measuring equipment. Four GP practice emergencies were identified and laminated guidelines were to be attached to the emergency bag. Conclusions In situ simulation in general practice not only provided an opportunity for the multi professional team to improve skills in clinical management of infrequent emergencies but also reinforced each team member’s roles, enabled each participant to identify areas of improvement and ”group think” ways of implementing improvement. It flagged up latent error threats and instilled transferrable confidence to all practice employees. Simulation is invaluable in developing the attributes required for successful team working in ”real-time-critical” but infrequent clinical situations.1 Members of well working teams experience low levels of stress and place a greater emphasis on quality of patient care.2 References . http://www.who.int/patientsafety/education/curriculum/who_mc_topic-4.pdf . Borrill C, West M, Shapiro D, Rees A. Team working and effectiveness in health care. British Journal of Healthcare Management 2000;6(8):364–371. (ISSN 1358-0574) http://homepages.inf.ed.ac.uk/jeanc/DOH-glossy-brochure.pdf

Background The transition from the hospital environment with its associated specialist facilities and equipment to community based practice can be challenging for General Practice (GP) trainees. Though the trainees obtain experience and competence in management of emergencies in the hospital setting, application of these skills in the community may be a daunting task. Simulation based teaching has gained popularity in GP training especially in communication skills development1 and the management of acute emergencies.2 The project team designed a half day teaching programme which would expose first-year GP trainees to the workings of a General Practitioner in the community. Project Description The project management team consisted of the GP Training Director, GP Education Scholar, Clinical Innovation Fellows and the Simulation Lead. The programme was designed to match the Royal College of General Practitioners curriculum objectives for acute care(1). The team designed a half day course ‘Get Ready for Community Practice’ [GRCP] to facilitate contextual and task learning in GP trainees using a combination of simulation scenarios with actors, manikins and part task trainers. First year trainees rotated around seven ‘OSCE-style’ stations featuring acute asthma and chest pain during GP consultations, stroke and diabetic ketoacidosis at home visits, paediatric emergencies of anaphylaxis and meningitis in surgery and skill-based practice of gynaecology and ear examinations. Participants were expected to diagnose, investigate and manage patients appropriately with the same equipment and medication that would be available to them in community practice. Results GRCP was included in the Swindon first-year GP trainees’ teaching programme with 82% participating over 2 pilot sessions in March 2017. A questionnaire was completed by each participant which focused on perceived usefulness and resulting confidence in managing each scenario if faced in the community. 96% of participants rated the overall programme as ‘useful’ or ‘very useful’. The 2 stations found most useful by trainees were the paediatric emergencies with 86% reporting they felt ‘very confident’ or ‘extremely confident’ in administering an IM injection in general practice. Conclusions The GRCP simulation sessions were well received by GP trainees who found them useful in preparation for community practice. The paediatric emergencies were particularly well received, likely because they simulated situations with which trainees were less familiar at managing and wanted further experience. This pilot demonstrates the usefulness of simulation as a learning tool to transition GP trainees into community practice and the GRCP programme has scope for expansion to all regional GP trainees.

Lignin preparations from kraft and sulfite pulping, steam explosion, and enzyme saccharification processes were assessed as substrates for lignin polymerization catalyzed by Trametes hirsuta laccase (ThL). Oxygen consumption associated with laccase catalyzed oxidation of the selected lignins was measured using a microplate-based oxygen assay. Laccase-induced changes in the molecular masses of the lignin polymers were assessed with aqueous-alkaline size exclusion chromatography (SEC) and changes in monomeric phenolics by reverse-phase high pressure liquid chromatography (HPLC). Obtaining consistent results in the lignin-laccase assay system required careful pH monitoring and control. All lignin preparations were oxidized by ThL, the rate being highest for steam-exploded eucalypt and lowest for enzyme-saccharified lignin. Comparing lignins, higher lignin-laccase reactivity was correlated with lower lignin molecular mass and higher amounts of monomeric phenolics. Solubility was not an indicator of reactivity. Steam-exploded and lignosulfonate-treated pine preparations were further fractionated by ultrafiltration to determine what molecular mass fractions were the most reactive in ThL catalyzed oxidation. Both retentate (> 3kDa), and to a lesser degree permeate (

Phytohormone production and modification by soil bacteria has the potential to influence plant growth and performance. We studied the long term effects of nitrogenous fertilisation and weed control on the concentration of IAA equivalents and 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity in bulk soil in a Pinus radiata plantation. IAA equivalent concentrations were increased by weed control and ACC deaminase activity was increased by weed control and fertilisation. Measurements of P. radiata growth were positively correlated with IAA equivalent concentrations. ACC deaminase activity was positively correlated with P. radiata growth only in the absence of fertilisation. These results suggest that plantation management can induce long term effects on soil bacterial phytohormone production and modification, which may influence plant growth.

This study examined the relation between academic procrastination tendency and student writing success. We found that the tendency to procrastinate on writing tasks was associated with general anxiety, anxiety about writing the paper, writing the paper later than usual, less satisfaction with writing the paper, and lower grades. Additionally, receipt of feedback on writing was associated with better writing outcomes for high procrastinators. These results have implications for understanding academic procrastination and the use of academic interventions to address procrastination.

The goals of this study were to determine whether the long-term training regimens experienced by competitive collegiate swimmers would result in altered levels of total and free serum insulin-like growth factor I (IGF-I) as well as IGF-binding proteins (BP) IGFBP-1 and -3. Two male (Teams 1M and 2M) and one female (Team 2F) teams were studied at the start of training, after 2 mo of training, after 4 mo (2–4 mo had the highest volume of training), after 5 mo (near the end of tapering; only for Team 1M), and several days after training was over. For Team 1M, total IGF-I concentrations were increased by 76% after 4 mo and were subsequently maintained at this level. Total IGF-I responses were more variable for Teams 2F and 2M. Free IGF-I levels were increased nearly twofold for all teams at 2 mo and were maintained or increased further with subsequent training. Only the levels of free IGF-I for Team 1M returned to pretraining values after training had ended. Training had little effect on IGFBP-1 levels. For all teams, serum IGFBP-3 was elevated by 4 mo of training (for Team 2F it was increased at 2 mo) by 30–97% and remained at these higher levels thereafter. The ratio of total IGF-I to IGFBP-3 was not increased by training in any group. These data indicate that serum levels of total and free IGF-I and total IGFBP-3 can be increased with intense training and maintained with reduced training (tapering). The findings show that changes in free IGF-I levels are not accounted for by alterations in the total IGF-I/IGFBP-3 complex or in IGFBP-3 levels and indicate that there are other important determinants of free IGF-I.

The aims of this work were to establish whether glutamine infusion via alanyl-glutamine dipeptide provides effective therapy against muscle atrophy from glucorticoids and whether the glucocorticoid induction of glutamine synthetase (GS) is downregulated by dipeptide supplementation. Rats were given hydrocortisone 21-acetate or the dosing vehicle and were infused with alanine (AA) or alanyl-glutamine (AG) at the same concentrations and rates (1.15 mumol.min-1.100 g body wt-1, 0.75 ml/h) for 7 days. Compared with AA infusion in hormone-treated animals, AG infusion prevented total body and fast-twitch muscle mass losses by over 70%. Glucocorticoid treatment did not reduce muscle glutamine levels. Higher serum glutamine was found in the AG-infused (1.72 +/- 0.28 mumol/ml) compared with the AA-infused group (1.32 +/- 0.06 mumol/ml), but muscle glutamine concentrations were not elevated by AG infusion. Following glucocorticoid injections, GS enzyme activity was increased by two- to threefold in plantaris, fast-twitch white (superficial quadriceps), and fast-twitch red (deep quadriceps) muscle/fiber types of the AA group. Similarly, GS mRNA was elevated by 3.3- to 4.1-fold in these same muscles of hormone-treated, AA-infused rats. AG infusion diminished glucocorticoid effects on GS enzyme activity to 52-65% and on GS mRNA to 31-37% of the values with AA infusion. These results provide firsthand evidence of atrophy prevention from a catabolic state using glutamine in dipeptide form. Despite higher serum and muscle alanine levels with AA infusion than with AG infusion, alanine alone is not a sufficient stimulus to counteract muscle atrophy. The AG-induced muscle sparing is accompanied by diminished expression of a glucocorticoid-inducible gene in skeletal muscle. However, glutamine regulation of GS appears complex and may involve more regulators than muscle glutamine concentration alone.

Skeletal muscle atrophy from glucocorticoids is prevented by glutamine infusion. Because the gene-encoding glutamine synthetase (GS) is glucocorticoid inducible, it represented an appropriate model for resting whether glucocorticoids and glutamine exert opposing actions on the expression of specific genes related to atrophy in muscle tissue. Rats were administered hydrocortisone 21-acetate or the dosing vehicle (carboxymethyl cellulose) and were infused with saline (Sal) or glutamine (Gln, 240 mM, 0.75 ml/h) for 7 days. Hormone treatment did not significantly lower glutamine levels in fast-twitch white or red regions of the quadriceps. Despite higher serum glutamine concentrations with amino acid infusion [1.52 +/- 0.03 (Gln) vs. 1.20 +/- 0.04 (Sal) mumol/ml], muscle glutamine concentrations were not markedly increased in these fiber types. In saline-infused animals, glucocorticoid treatment produced 200-300% increases in plantaris, fast-twitch white, and fast-twitch red muscle GS enzyme activity and mRNA. Moreover, in all muscle types studied, glutamine infusion diminished glucocorticoid effects on GS enzyme activity to 131-159% and on GS mRNA to 110-200% of the values in saline-treated controls. These data demonstrate that glutamine infusion results in inhibiting GS expression, but the absence of changes in muscle glutamine concentration suggests the interplay of additional regulators of the GS gene.

Volcanism has a profound impact on our planet. The process can be viewed from three different levels – global, regional, and local. Global scale features are associated with tectonic plate boundaries: the oceanic ridge systems and their attendant basins that cover 60% of the Earth's surface, and subduction zones and related volcanic arcs (mountain belts) and back arc regions. Regional scale features (>100 km) are flood basalts, hotspot tracks, continental rift valleys, volcanoes, and volcanic cone fields. Local features are the individual volcanic landforms that make up these regional and global features. The local features are characterized by specific morphologies that are dependent on their mode of origin, composition, spatial location, and state of erosion. The volcano's morphology provides readable clues as to the hazard implications in the event of renewed eruption. Volcanic landforms alter climate by creating long-term orographic effects, and volcanic eruptions produce short-term (

The aims of this study were to determine whether glutamine infusion prevents the decline in protein synthesis and muscle wasting associated with repeated glucocorticoid treatment. Hormone (cortisol acetate, 100 mg.kg body wt-1.day-1) and vehicle (carboxymethyl cellulose)-treated female rats were infused with either saline or glutamine (240 mM, 0.75 ml/h) for a 7-day period. Glutamine infusion attenuated the decline of plantaris muscle glutamine concentration (3.0 +/- 0.2 vs. 2.3 +/- 0.2 mumol/g) and prevented > 70% of the total muscle mass losses due to the glucocorticoid injections. Fractional synthesis rates of myosin heavy chain (MHC) and total protein were determined after constant [3H]leucine infusion from the leucyl-tRNA precursor pool, which was similar in all groups (range 4.8 +/- 0.5 to 6.3 +/- 0.4 disintegrations.min-1.pmol-1). MHC synthesis rates (%/day) in plantaris muscles were reduced to approximately 40% of controls (4.2/9.4). Although glutamine had no effect on MHC synthesis in vehicle-treated animals (10.1/9.4), it prevented 50% (7.6/4.2) of the hormone-induced decline in MHC synthesis rates. The same results were obtained with total protein synthesis measurements. Changes in muscle mass did not appear related to estimates of protein breakdown. In conclusion, these data show that glutamine infusion is effective therapy in counteracting glucocorticoid-induced muscle atrophy. Atrophy attenuation appears related to maintaining muscle glutamine levels, which in turn may limit the glucocorticoid-mediated downregulation of MHC synthesis.

Amended insulin to glucose ratios were calculated from the concentrations of serum insulin and blood glucose measured concurrently during either a glucagon tolerance test or after feeding in healthy dogs. Values greater than 30 microU/mg which are supportive of a diagnosis of insulinoma were obtained at certain times during the test period. Amended insulin to glucose ratios calculated from serum insulin and blood glucose concentrations obtained during a glucagon tolerance test and an oral glucose tolerance test on a dog with an insulinoma were less than 30 microU/mg, or equivocal, at different times during the test period. This indicates that under some circumstances healthy dogs may have elevated amended insulin to glucose ratios, and dogs with insulinoma may have a normal amended insulin to glucose ratio. Care is essential for interpretation of amended insulin to glucose ratios, and a diagnosis of insulinoma using the ratio must be made in conjunction with appropriate clinical signs of hypoglycaemia.

This investigation was undertaken to evaluate whether the mitochondrial disfunction associated with glucocorticoid treatment is expressed at the level of cytochrome-c oxidase (COX) and whether endurance training attenuates this response. Adult female rats were administered cortisol acetate (100 mg/kg body wt) or an equal volume of the vehicle solution for 11 days. Endurance training was performed by treadmill running up to 28 m/min (with intervals at 50 m/min for 2 min every 15 min), for 90 min/day, 6 days/wk, for 8–10 wk. During hormone treatments, the training animals ran every day. Exercise prevented 43–55% of the hormone-induced atrophy in various fast-twitch muscles or muscle groups. Cortisol acetate treatment produced no significant effects on COX enzyme activities or subunit mRNA content in deep red or superficial white quadriceps or mixed plantaris muscles. The levels of COX were increased as a result of training by 70–110% in plantaris and red quadriceps muscles, but no changes were seen in white quadriceps muscles. Both nuclear-encoded (COX IV) and mitochondrial-encoded (COX III) mRNAs were increased approximately twofold by the exercise program in these same muscles. These data indicate that the impaired mitochondrial functioning associated with glucocorticoids is not observed at the COX step of electron transport. The prolonged endurance-training regimen appears to induce relatively parallel increases in COX enzyme activity and mRNA expression with coordinate changes in nuclear and mitochondrial mRNAs.

Skeletal muscle glutamine synthetase (GS) expression is reduced by endurance exercise and is increased when normal innervation is interrupted. This investigation was undertaken to determine whether GS expression is downregulated by the increased contractile activity associated with functional overload. Plantaris muscles overloaded for 30 days by synergist ablation were 70% heavier than those in sham-operated and unoperated control muscles. GS mRNA levels from hypertrophied muscles, measured by Northern and dot-blot hybridization, were reduced to 30% of controls. Changes in total RNA concentration and the proportion of poly(A)+ RNA in the total RNA pool did not account for the decline in GS mRNA. Despite reduced levels of GS mRNA, GS enzyme activity (nmol.h-1.mg protein-1) was unchanged in the hypertrophied muscles (overload, 79 +/- 5; control, 82 +/- 4). To further examine the lack of relationship between GS mRNA and enzyme activity, the concentration of glutamine, a known posttranslational modifier of GS activity, was measured. Consistent with the observed enzyme activities, muscle glutamine was unchanged in hypertrophied muscle (overload, 6.2 +/- 0.3; control, 5.8 +/- 0.4 mumol/g tissue). These results suggest that translational or posttranslational regulation, other than through alterations in glutamine concentration. may play a role in maintaining GS enzyme levels in hypertrophied muscle. Moreover, the regulation of GS activity in muscle hypertrophy may differ from the regulation with endurance training, in which changes in enzyme activity parallel changes in mRNA.

Exercise has been shown to be effective in preventing glucocorticoid-induced atrophy in muscles containing high proportions of type II or fast-twitch fibers. This investigation was undertaken to further evaluate this response in type IIa and IIb fibers, determined by histochemical staining for myofibrillar adenosinetriphosphatase with alkaline and acid preincubation. Steroid [cortisol acetate (CA), 100 mg/kg body wt] and exercise (running 90 min/day, 29 m/min) treatments were initiated simultaneously for 11 consecutive days in female rats. Fiber distribution and area measurements were performed in a deep and superficial region of plantaris muscle. The exercise regimen spared approximately 40% of the CA-induced plantaris muscle atrophy. In the deep region, the fiber population, which contained approximately 13% type I (slow-twitch), 24% type IIa, and 63% IIb fibers, was not affected by either treatment. In the superficial section, which consisted solely of type II fibers, the proportion of type IIa fibers was higher (27 vs. 9%, P less than 0.01) in the steroid- than in the vehicle-treated groups. Within each region, type IIa fibers were less susceptible to atrophy than type IIb fibers, and within each fiber type, the deep region had less atrophy than the superficial region. Type I fibers were unchanged by steroid treatment. For type IIa fibers, exercise prevented 100% of the atrophy in the deep region and 50% in the superficial region. For type IIb fibers, the activity spared 67 and 40% of the atrophy in these same regions, respectively. These results show that glucocorticoids are capable of changing the myosin phenotype.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of treadmill running on estrous cycles was studied in the rat. Additional effects of cortisol acetate treatment and adrenalectomy were studied in both exercising and sedentary rats. Sedentary rats given the vehicle or cortisol acetate, or which had been adrenalectomized, all exhibited estrous cycles with diestrous phases that were uniformly less than 4 days. However exercising rats had extended estrous cycles; 50-62% of cycles were incomplete within 11 days and 78% of rats had cycles with diestrous phases that were more than 4 days long. There were no difference in duration of estrous cycles of running rats that received vehicle, received cortisol acetate, or had been adrenalectomized. We conclude that the running regimen resulted in a delay of the normal ovulatory period in rats, and that this effect of running was not affected by the presence or absence of glucocorticoids.

We investigated whether the prevention of glucocorticoid-induced muscle atrophy by glutamine infusion is associated with alterations in serum levels of insulin-like growth factor (IGF)-I and its binding proteins (IGFBPs). Hormone (cortisol acetate [CA], 100 mg/kg body wt/day) and vehicle (carboxymethyl cellulose [CMC])-treated female rats were infused with either saline or glutamine (240 mM, 0.75 ml/hr) for a 7-day period. Glutamine infusion prevented over 70% of the skeletal muscle mass loss due to the glucocorticoid injections. Serum IGF-I concentrations, which were measured by radioimmunoassay (RIA) after acid solid-phase extraction of IGFBPs, were not significantly different among groups (range of means: 373-395 ng/ml). Saline/CA treatment resulted in a 2-fold increase in circulating levels of IGFBP-3 (38- to 50-kDa bands from ligand blotting measurements) versus the saline/CMC group. Levels of 30- to 32-kDa bands were increased by approximately 3-fold in the CA-treated rats. Immunoprecipitation studies suggested that the increase in the 30- to 32-kDa binding proteins were not due to elevated levels of IGFBP-1, -2, or -5. None of the treatments significantly modified circulating levels of IGFBP-4 (24 kDa). Glutamine infusion did not reverse the effects of glucocorticoids on circulating levels of 38- to 50- and 30- to 32-kDa IGFBPs. We conclude that the attenuation of glucocorticoid-induced muscle atrophy by glutamine infusion is not associated with changes in circulating levels of IGF-I or IGFBPs.

This study was designed to evaluate individual variation in ovarian responses to exercise. Rats ran on a treadmill (15% incline) at a rate of 26 m.min-1 for 90 min every day for 14-21 d; control rats were placed on a stationary treadmill for the same period of time. Based on daily vaginal cytology, 9 of 17 exercising rats had abnormal (5 d) estrous cycles in the first cycle of training compared to only 2 of 19 controls. Throughout the training period, the length of estrous cycles of 8 of the 17 exercising rats were relatively unaffected; the mean length of completed cycles was 5.1% +/- 0.4 (SE) d. However, of those length of completed cycles was 5.1 +/- 04 (SE) d. However, of those thought to have ovulated based on vaginal cytology, fewer exercising than control rats had new corpora lutea on their ovaries. In exercising rats acyclic periods of up to 21 d were associated with serum progesterone levels similar to those of the diestrus phase of the estrous cycle (mean, 29 +/- 4 SE nmol.l-1). We conclude that treadmill running extends the period of progesterone secretion, delaying ovulation in a susceptible population of rats, and that vaginal cornification may not be an accurate indication of ovulation in these animals.

Disorientation, muscle fasciculations and weakness seen in a 12-year-old neutered female domestic shorthaired cat were attributed to hypoglycaemia associated with a large hepatoma. Glucagon tolerance tests on this cat and a healthy cat showed that their plasma glucose concentrations increased and decreased at about the same rate. Plasma insulin concentrations in the healthy cat increased and decreased in parallel with the plasma glucose concentration. In the affected cat, plasma insulin concentrations increased initially but decreased more rapidly. Reflecting these observations, the amended insulin to glucose ratios in the affected cat were much lower than those of the healthy cat, until the 4-hour sample. Serum somatostatin, somatomedin and gastrin concentrations were measured but no conclusions as to pathogenesis of the hypoglycaemia could be made. The alterations in insulin secretion in the affected cat suggested that altered hormonal control of glucose homeostasis mav have occurred with this ...

The research goal was to attempt to clarify the consequences of increased strength on performance at submaximal exercise intensities. Eight subjects (4 males, 4 females) completed a 3-d.wk-1, 16-wk resistance training regimen. After training, upper (bench press, BP) and lower (parallel squat, PS) extremity strength were increased by 23% and 37%, respectively. Performance at the same absolute work rates as before training was increased by 30-159% following training depending on intensity and type of exercise. Performance at the same relative work rates (80%, 60%, 40%) remained unchanged by the training for both exercises. Prior to training, PS repetitions at 40% were correlated (r = 0.69, P0.05) with the percentage of slow-twitch (ST) fibers in the vastus lateralis muscle. There were similar relationships at 40% (r = 0.73) and at 60% (r = 0.83) for the PS exercise after training. However, the resistance program did not result in greater relative submaximal performance in individuals with a higher percentage of ST fibers. We conclude that strength improvement of up to 40% does not produce a strength-related performance deficit, when training and testing procedures are identical. Yet, these data do not rule out the potential of a strength-related repetition performance deficit. When subjects were equally divided by strength levels, those tested at the highest absolute resistance had significantly lower bench press repetition performance at 60% and 40% of the 1-RM than the subjects tested at the lowest absolute resistance.

Subjects (5 males, 5 females) performed heavy-resistance exercise at a constant stimulus 3 days/wk for 8 wk. Work rates were then increased to higher but constant levels for an additional 8 wk. Half times of the first training period were 14 and 10 days for the bench press and parallel squat, respectively. The second time course resulted in only one-third of the overall magnitude of strength increases for both exercises as the first, and the kinetics were slower in the parallel squat but similar in the bench press (half time 13 days). Skeletal muscle fiber area was significantly increased (19%) in fast-twitch fibers by the end of the second training period. Postexercise elevations in serum cortisol and prolactin were seen only in the male subjects. Because the males trained at considerably higher work loads than the females, these results imply that absolute amounts of resistance may be an essential requirement for inducing certain hormonal responses. Serum cortisol levels in males after exercise were blunted by the 5th wk of the first time course. For serum testosterone, neither resting nor higher post-exercise concentrations were different at any point of the training periods for either sex. We conclude that the strength time course results are not inconsistent with current thought on factors contributing to strength accumulation. The absence of a specific serum androgenic response with strength development may be related to the fact that the constant exercise stimulus is not conducive to establishing clear-cut hormone-strength relationships.

This study was undertaken to determine whether regular endurance exercise is a deterrent to a developing state of muscle atrophy from glucocorticoids and to evaluate whether the contractile activity antagonizes the hormonal actions on glutamine synthetase, alanine aminotransferase, and cytosolic aspartate aminotransferase (cAspAT). Adult female rats were administered cortisol acetate (CA, 100 mg/kg body wt) or an equal volume of the vehicle solution for up to 15 days. Exercise (treadmill running at 31 m/min, 10% grade, 90 min/day) was introduced after 4 days of CA treatment, at which time plantaris and quadriceps muscle mass had been reduced to 90% of control levels. Running for 11 consecutive days prevented 40 mg of the 90-mg loss and 227 mg of the 808-mg loss that were subsequently observed in plantaris and quadriceps muscles, respectively, in the sedentary animals. Glutamine synthetase mRNA and enzyme activity were elevated threefold by glucocorticoid treatment in the deep quadriceps (fast-twitch red) muscles after 4 days. Initiating exercise completely interfered with the further hormonal induction (to approximately 5-fold) of this enzyme and, after 11 consecutive days of the exercise regimen, glutamine synthetase mRNA and enzyme activity were 58 and 68% of values from CA-treated sedentary animals. In vehicle-treated groups, basal levels of glutamine synthetase expression were also diminished by exercise to approximately 40% of the values in sedentary controls. Hormone treatment did not alter either aminotransferase enzyme activity but reduced cAspAT mRNA in fast-twitch red muscles by 50%. Exercise abolished the glucocorticoid effect on cAspAT mRNA.(ABSTRACT TRUNCATED AT 250 WORDS)

One purpose of this study was to determine whether the suppression of glucocorticoid-induced glutamine synthetase (GS) gene expression by exercise is localized to fiber types that are known to be primarily recruited during endurance running. A second purpose examined whether denervation, which is associated with a reduction in contractile activity, would upregulate GS expression. Exercise consisted of treadmill running at 31 m/min for 12-16 wk. Glucocorticoid treatment (100 mg/kg body wt hydrocortisone 21-acetate) was administered during the last 11 days of the exercise program. Basal GS expression was lowest (GS enzyme activity, 43 +/- 3 nmol.h-1.mg protein-1; GS mRNA, 1.0 arbitrary units) in the slow-twitch red soleus, a muscle type that is known to resist glucocorticoid-induced muscle wasting, intermediate (74 +/- 10 and 1.7 +/- 0.2) in fast-twitch red quadriceps, a muscle type susceptible to atrophy, and highest (106 +/- 16 and 5.4 +/- 1.3) in fast-twitch white quadriceps, a muscle type known to be most susceptible to atrophy. Hormone treatment increased GS enzyme activity and mRNA by two- to fourfold in all muscle types. Exercise diminished GS enzyme activity and mRNA in the fast-twitch red fibers to 35-70% of sedentary control values in both basal and glucocorticoid-stimulated muscles. The running also reduced GS enzyme activity in hormone-treated slow-twitch fibers but did not alter basal or glucocorticoid-induced GS expression in fast-twitch white fibers. These results indicate that glucocorticoids induce similar relative GS expression across all muscle types, but the low absolute levels of expression in slow-twitch muscles are not related to any atrophy.(ABSTRACT TRUNCATED AT 250 WORDS)

The present study sought to evaluate the inconsistencies previously observed regarding the predominance of continuous or interval training for improving fitness. The experimental design initially equated and subsequently maintained the same relative exercise intensity by both groups throughout the program. Twelve subjects were equally divided into continuous (CT, exercise at 50% maximal work) or interval (IT, 30 s work, 30 s rest at 100% maximal work) training groups that cycled 30 min day−1, 3 days week−1, for 8 weeks. Following training, aerobic power (VO2max), exercising work rates, and peak power output were all higher (9–16%) after IT than after CT (5–7%). Vastus lateralis muscle citrate synthase activity increased 25% after CT but not after IT. A consistent increase in adenylate kinase activity (25%) was observed only after IT. During continuous cycling testing the CT group had reduced blood lactate (1ab) levels and respiratory quotient at both the same absolute and relative (70% VO2max) work rates after training, while the IT group displayed similar changes only at the same absolute work rates. By contrast, both groups responded similarly during intermittent cycling testing with lower 1ab concentrations seen only at absolute work rates. These results show that, of the two types of training programs currently employed, IT produces higher increases in VO2max and in maximal exercise capacity. Nevertheless, CT is more effective at increasing muscle oxidative capacity and delaying the accumulation of 1ab during continuous exercise.

This work evaluated the anticatabolic capacity of androgenic-anabolic steroids and exercise (contractile activity) in inhibiting skeletal muscle atrophy associated with excessive levels of circulating glucocorticoids. With androgenic-anabolic steroids, most binding studies indicate that they have very low binding specificity for the glucocorticoid receptor. Androgens may interact through their own receptor to interfere with glucocorticoid functioning at the gene level, but this remains unproven. Current literature suggests that androgens do not prevent atrophy but may retard growth suppression accompanying glucocorticoid treatment. With exercise, functional overload, resistance, and endurance types of training are capable of preventing muscle atrophy from glucocorticoids. Androgen and glucocorticoid-receptor binding and glucocorticoid-receptor activation studies have, thus far, not established that atrophy prevention is mediated through the receptor. In conclusion, the role of androgenic-anabolic steroids as glucocorticoid antagonists requires further study. Study of the effects of exercise on muscle gene expression of glucocorticoid-inducible proteins is needed to gain additional understanding of this mechanism of atrophy prevention.

This investigation was undertaken to evaluate whether endurance running of the type known to retard the muscle atrophy associated with glucocorticoid excess inhibits activation of glucocorticoid-receptor complexes to a DNA binding state. Female adrenalectomized rats received an injection (50 microCi/100 g body wt ip) of [3H]triamcinolone acetonide and remained sedentary or were immediately exercised by endurance running at 23 m/min for up to 90 min. Receptor activation, as quantified by binding to DNA-cellulose, steadily increased from 10-20% of the receptors capable of binding DNA in uninjected controls to 25-45% by 5 min and to 53-80% by 90 min after receiving the hormone in all muscles studied (fast-twitch red vastus lateralis, fast-twitch white vastus lateralis, slow-twitch soleus, mixed gastrocnemius, and heart). Exercise did not influence the time-course changes in percent activation. When activation was determined from changes in the conformational state of the receptor as measured by diethylaminoethyl-cellulose anion exchange chromatography, there was a similar time-dependent formation of activated receptor forms in all muscle types. However, exercise did not inhibit or delay the appearance of the activated receptor from the unactivated state. These results indicate that glucocorticoid receptor activation occurs at a rate that is independent of both fiber type and delivery of steroid to working muscles during exercise. If exercise alters receptor activation, a longer time period, beyond 90 min of running, or even additional training may be needed for inhibition to be expressed.

This study was designed to evaluate individual variation in ovarian responses to exercise. Rats ran on a treadmill (15% incline) at a rate of 26 m.min-1 for 90 min every day for 14-21 d; control rats were placed on a stationary treadmill for the same period of time. Based on daily vaginal cytology, 9 of 17 exercising rats had abnormal ( > 5 d) estrous cycles in the first cycle of training compared to only 2 of 19 controls. Throughout the training period, the length of estrous cycles of 8 of the 17 exercising rats were relatively unaffected; the mean length of completed cycles was 5.1% +/- 0.4 (SE) d. However, of those length of completed cycles was 5.1 +/- 0>4 (SE) d. However, of those thought to have ovulated based on vaginal cytology, fewer exercising than control rats had new corpora lutea on their ovaries. In exercising rats acyclic periods of up to 21 d were associated with serum progesterone levels similar to those of the diestrus phase of the estrous cycle (mean, 29 +/- 4 SE nmol.l-1). We conclude that treadmill running extends the period of progesterone secretion, delaying ovulation in a susceptible population of rats, and that vaginal cornification may not be an accurate indication of ovulation in these animals.