1,721,177 research outputs found
An improved computational method to assess pituitary responsiveness to secretagogue stimuli
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Stimulated secretion of pituitary hormones in normal humans: A novel direct assessment from blood concentrations
No full textGrowth hormone (GH) treatment in GH‐deficient adults: effects on muscle size, strength and neural activation
No full textSummary. The effects of 6 months of recombinant growth hormone (GH) treatment (0–5 IU kg‐1 per week) on muscle size, strength and neural activation (EMG) was studied in eight adults with childhood onset GH deficiency (GHD). Before treatment, height, body mass (BM) and lean body mass (LBM) 6f the GHD subjects were significantly lower (P<0–01) from those recorded in eight healthy controls, while no significant differences were found between the body mass index (BMI) of the two populations. Thigh muscle + bone cross‐sectional area (CSAM+B) and lower limb muscle plus bone volume (LLVM+B) of the GHD patients were 66–1 ± 13–7% and 47–6 ± 6–8% of those recorded in the controls (P<0–01), whereas no difference in CSA/height2 was found between the two groups. By contrast, LLVM+B/height3 was 82–0 ± 19–0% that of the controls (P<0–05). Similarly, quadriceps muscle strength (MVC) of the GHD patients was 63–2 ± 12–4% that of controls (P<0–01), while no significant differences in the force per unit area (F/CSA) and per body mass (F/BM) were found. After 6 months of GH treatment LBM increased by 6–0 ± 4–2% (P<0.02), CSAM+B by 14–5 ± 12–7% (P<0.01) and LLVM+B by 10‐l ± 7–3% (P<0.01), absolute differences from the normals still persisting. However, the LLVM+B/height3 of the GHD patients after treatment was no longer significantly different from that of the controls. Quadriceps MVC increased by 9–8 ± 12–0% (P<0–02), differences from the controls being still significant, whereas the F/CSA and F/BM did not change. A right shift of the integrated EMG/Force relation, with no change in the maximal integrated EMG (iEMG) activity, was observed in the patients after treatment. In conclusion, the current study shows that adults with childhood onset GHD have a reduced skeletal muscle mass and strength which seem to be positively influenced by 6 months of GH treatment. Copyright © 1994, Wiley Blackwell. All rights reserve
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Effects of short-term, integrated body mass reduction program on maximal oxygen consumption and anaerobic alactic performance in obese subjects
No full textThe study investigated the effect of a short-term (3-week) body mass reduction program, combining energy-restricted diet, nutritional education, psychological counselling and aerobic exercise training (DEP-AT) on maximal oxygen consumption (VO2max) and anaerobic alactic performance evaluated with different techniques in obese patients (grade II and III). Fifty-three (14 males, 39 females) obese subjects [average±SD body mass index (BMI): 41.6±4.2 kg/m2] were tested before and after the DEP-AT program characterised by a daily conditioning protocol of aerobic exercise on cycloergometer, treadmill and armergometer for a total duration of 35 min at an intensity corresponding to 50% of individual VO2max during the first week of the program and at 60% in the following 2 weeks. VO2max was determined with the cycloergometric indirect method. Short-term alactic anaerobic performance was evaluated with: a) jumping test (5 consecutive jumps with maximal effort, Bosco technique), b) short sprint running test (8 m), and c) stair climbing test (modified Margaria test). The DEP-AT program induced a significant weight loss (-4.57±1.26%, p<0.001) and a significant ̇VO2max increase (14.1±20.5%, p<0.001). After the DEP-AT program, lower limb alactic anaerobic power output, calculated on a per kg body mass basis, increased significantly both in jumping and in stair climbing (20.1±24.8%, p<0.001 and 13.5±19.75%, p<0.001, respectively), as well as average horizontal velocity during short sprinting (7.2±17.6%, p<0.01 . Power output was a major determinant of the motor performance, being significantly correlated with: a) vertical displacement of the centre of gravity (R2=0.884, p<0.001) in jumping test, b) vertical velocity (R2=0.348, p<0.001) in stair climbing test, and c horizontal velocity (R2=0.394, p<0.001) in short running test. In conclusion, short-term DEP-AT program induces significant improvements in both aerobic capabilities and anaerobic performance, possibly through the combination of a number of contributory mechanisms, such as exercise-mediated training, shift in the balance between parasympathetic and sympathetic activity, a weight-loss dependent shift toward a more favourable region of the muscle power-velocity curve, acquisition of a certain degree of motor skill during the conditioning program, improvement of self-esteem and motivation. © 2003, Editrice Kurtis
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Quadriceps and hand-grip strength in adults with childhood-onset growth hormone deficiency
No full textThe effects of chronic growth hormone (GH) deficiency on muscle size and strength of postural (quadriceps) and non-postural (hand-grip) muscle groups, as well as on vertical jump capacity, were evaluated in six adults with childhood-onset GH deficiency. Data obtained were compared to those recorded in an age-, sex- and exercise-matched healthy control group. Thigh muscle plus bone cross-sectional area (CSA(M+B)) of the dominant quadriceps was significantly lower (p < 0.001) than in controls, while the CSA(M+B)/(Body height)2 ratio was similar to that of controls. The maximum voluntary contraction (MVC) of the quadriceps of patients was significantly lower (p < 0.002) than in controls, while no differences existed in the quadriceps force expressed per unit area (MVC/CSA) between patients and controls. As far as hand-grip was concerned, the CSA(M+B) of the dominant forearm was significantly lower (p < 0.003) than in controls, while the CSA(M+B)/(Body height)2 ratio was no different. The hand-grip MVC of patients was significantly lower (p < 0.004) than in controls, while no differences existed in the MVC/CSA ratio. It is noteworthy also that no difference existed in the hand-grip to quadriceps MVC ratio of the two groups. Furthermore, no differences were found in the vertical lump capacity, because both Δ Height and Δ Height/Body weight of patients were not significantly different from those of controls. In conclusion, our study suggests that GH deficiency seems to reduce the size and strength of postural and non-postural muscle groups to the same extent. However, these findings are likely to be attributed to a simple dimensional scaling, because their CSA/(Body height)2, MVC/CSA and vertical jump capacity were comparable to those of controls
Physical exercise in the elderly: Its effects on the motor and endocrine system
No full textAgeing is associated with reduced maximal aerobic power, muscle strength and power; namely, reduced fitness. Based on the existing evidence concerning exercise prescription for healthy adults, in 1990, the American College of Sports Medicine (ACSM) made the following recommendations: frequency of training: 3-5 days/-week, intensity: 60-90% HRmax, or 50-85%VO2max, duration: 20-60 min of continuous aerobic activity with involvement of large muscle groups. However, the target of improving/maintaining physical fitness is inappropriate for the whole elderly population, which includes the frail. In these subjects, the achievement of a better health status is certainly the primary goal, as recently stated by the 1996 Heidelberg guidelines. Physical activity should be prescribed on the basis of an individual health/fitness gradient with different goals. Lower levels of physical activity than those recommended by the ACSM may reduce the risk for certain chronic degenerative diseases and yet may not be of sufficient quantity or quality to improve VO2max. In the wake of these considerations and the inclusion of the improvement/maintaining of health status among the goals of exercise prescription in the elderly population, in 1991, the ACSM lowered the recommended exercise intensity to as low as 35-40%VO2max. One of the most critical consequences of ageing of the motor system is muscle weakness. Several causes may be held responsible for this phenomenon; among these sarcopenia is, probably, the most common. The latter involves both a decrease in muscle fibre size and number. However, atrophy cannot alone entirely account for senile muscle weakness. As a matter of fact, the maximum force that may be generated per muscle cross-sectional area (F/CSA) is lower in elderly subjects. This phenomenon suggests that muscular or neural factors, or more likely both, are involved. Another common cause for the decrease in F/CSA is muscle activation. Recent reports show incomplete quadriceps muscle activation in very old (80+) men and women. Since almost complete (95%) muscle activation was found in a population of subjects ∼70 year old, it seems that activation capacity rapidly falls beyond the 7th decade. Therefore, taken together, the above neural factors may account for large part of the decrease in force with ageing. Hormonal changes in themselves are not the simple explanation for all of the changes associated with ageing. Studying the effects of strength training on the endocrine system is complicated by a variety of factors related to both the exercise challenge itself and the accurate measurements of hormones. The measurement of hormonal changes is complicated by the manner in which they are released, transported and interact with the target tissue. Many hormones are released in a pulsatile manner with superimposed diurnal, monthly, and seasonal rhythms. They often exist in different molecular weight fractions and are frequently transported in a bound form. From the work that has been carried out in younger people it would appear, that if sufficient high resistance exercise is carried out, then the acute hormonal response is not qualitatively different to that following a bout of endurance exercise. Exercise training programs have been suggested as possible countermeasures against involutional bone loss, being able to prevent or reverse almost 1% of bone loss per year in both lumbar spine and femoral neck for both pre- and postmenopausal women. As far as elderly people are concerned, it appears that strength training may have a more beneficial effect than aerobic training on BMD, especially in postmenopausal women, although some evidence suggests that also aerobic training may improve BMD in the elderly. To date, the effect of physical activity on bone turnover has received limited attention despite the strict dependence of bone mass on the balance between bone formation and bone resorption. The equilibrium between these two components of bone turnover is crucial for bone mass and BMD, since bone loss, or increase, results from an uncoupling of bone formation and bone resorption. During the last few years there has been a rapid development of reliable methods to measure biochemical markers of bone metabolism. Since these markers reflect the cellular events, they may provide new opportunities to elucidate the effects of physical exercise on bone metabolism
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