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Physiological responses of wild antelope to exercise training as a prospective treatment to prevent capture myopathy
Get PDFCapture myopathy is a lethal condition associated with physiological stress in wildlife and is responsible for most deaths during game capture. Exercise training to improve fitness has been proposed as a preventative management strategy for capture myopathy but lacks scientific evidence. The aim of this study was to determine whether regular exercise training of wild antelope is indeed feasible, and whether physiological adaptations occur that could mitigate the response to capture stress. Forty wild blesbok (Damaliscus pygargus phillipsi) were habituated for two weeks to a boma. Twenty were randomly selected to be exercise trained for four weeks, consisting of thirtyminute low, medium and high intensity running sessions four or five times per week. Ten of the exercise trained and ten untrained blesbok were subjected to a twenty-minute capture stress event that included chasing by humans, a motorised quadbike, and a helicopter. Immediately following this event, the animals were immobilised, physiological variables recorded, and blood samples obtained at 0 and 40 minutes. The same sampling occurred on days 2 and 5 after the original stress event but only at 0 minutes. Untrained and unstressed animals served as controls for the effect of training and the acute stress response, respectively. The exercise trained blesbok responded physiologically better to the capture stress event , indicated by lower blood lactate concentrations [exercised: Median (Mdn) = 9.4 mmol/l , Interquartile range (IQR) = 7.9 – 12.4 mmol/l vs. non-exercised: Mdn = 11.0 mmol/l, IQR = 10.5 – 14.1 mmol/l] and reduced post-capture stress rectal temperatures [exercised: Mdn = 41.4 °C, IQR = 41.1 – 41.6 °C vs. non-exercised: Mdn: 41.8 °C, IQR = 41.6 - 41.8 °C]. Although the pH did not differ between the groups - the exercise trained blesbok group had less animals presenting acidaemic, there was an increased cHCO3 - [mean (M) ± standard deviation (SD) of exercised: 20 ± 3 vs. non-exercised: 16 ± 5 mmol/l) and BEecf (M ± SD of exercised: - 5 ± 3 vs. non-exercised: - 10 ± 6 mEq/L) that supports an increased buffering ability for the exercised group. These findings conform to previous exercise training studies in humans, horses, and rodents that indicate similar adaptations in trained groups exposed to exertional stress compared to untrained groups. The data also confirmed the severe hypoxaemia that is caused by the opioid immobilisation drugs. This is the first study showing that wild antelope can be successfully exercise trained, which led to physiological adaptations resulting in improved fitness. Whether this training programme will prevent the onset of capture myopathy and reduce fatalities still needs to be further investigated
Mechanisms underlying the development of weakness in idiopathic inflammatory myopathies: an in vitro single muscle fibre contractility study
Get PDFIntroduction: Polymyositis (PM), dermatomyositis (DM) and necrotising autoimmune myopathy (NAM) form part of the spectrum of idiopathic inflammatory myopathies (IIMs). Although the pathogenic mechanisms are different, the unifying feature is that of weakness caused, in some way or another, by an inflammatory attack on muscle. The mechanism by which weakness develops is still unclear, but experimental animal data suggest that dysfunction of the contractile apparatus might contribute to muscle weakness in these conditions. This study investigated the contractile function of single muscle fibres from patients with IIMs in vitro. Methods: Muscle biopsies obtained from patients with IIMs and healthy controls were dissected and chemically permeabilised. Single muscle fibres were dissected out and subjected to contractility measurement based on standard protocols utilising a permeabilised single fibre system. Specific force (SF; maximum force normalised to cross-sectional area), was calculated for each fibre and compared between the two groups. In addition, maximum shortening velocity and power output were assessed in some of the fibres, and calcium sensitivity in the rest. The myosin heavy chain composition of each fibre was determined by means of gel electrophoresis. Results: A total of 178 fibres from IIM cases and 174 fibres from controls were studied. Specific (normalised) force was 23%, 24% and 29% lower in the IIM group for all fibre types combined, type I fibres, and type IIa fibres, respectively. Shortening velocity and maximum power output were significantly higher in the IIM group for both type I and IIa fibres, compared to controls, while calcium sensitivity was higher in type IIa fibres from IIM cases than controls. Discussion: The findings from this study suggest that weakness in IIMs may, at least in part, be caused by dysfunction of the contractile apparatus leading to impaired contractile force. The higher shortening velocity, power output and calcium sensitivity in fibres from IIM cases probably represents compensatory mechanisms. Although the mechanism by which contractile function is affected has not been investigated, animal studies suggest a role for TNF-α. The findings of this study provide a basis for further investigation into the mechanisms underlying weakness in IIMs
Characteristics and adaptation of skeletal muscle to endurance exercise
Get PDFThesis (PhD)--University of Stellenbosch, 2005.ENGLISH ABSTRACT: Skeletal muscle adapts to stimuli by modifying structural and metabolic protein expression.
Furthermore, a muscle group may vary within itself to accommodate specialisation in regions.
Structural and metabolic characteristics of an individual are regulated partly by genotype, but
contraction duration and intensity may play a greater role in muscle phenotype. The aims of this
dissertation were to investigate: structural and metabolic regionalisation in a muscle group, possible
relationships between training volume and intensity and hybrid fibres, muscle characteristics of
athletes from two different ethnic groups, and muscle adaptation in already well-trained athletes
subjected to high intensity interval training.
Myosin heavy chain (MHC) isoform content and citrate synthase (CS) activities were measured in
the Quadriceps femoris (QF) muscle of 18 female rats. Muscle was divided into superficial, middle
and deep, distal, central and proximal parts. MHC IIb and IIx were more abundant in superficial
regions (P < 0.05) with low CS activities compared to deeper parts. Isoform content varied along the
length of deep regions. This study showed that the QF has regional specialisation. Therefore,
standardisation of sampling site is important.
Hybrid fibre proportions in muscle biopsies of 12 middle distance runners and 12 non-runners were
investigated. MHC IIa/IIx correlated with training volume/week in runners (r = -0.66, P < 0.05) and
MHC IIa/IIx correlated with exercise hours/week in non-runners (r = -0.72, P < 0.01). Average
preferred racing distance (PRDA) correlated better with MHC IIa/IIx in runners (r = -0.85, P <
0.001). MHC IIa/IIx may therefore be more closely related to exercise intensity than previously
thought.
Fibre type characteristics and performance markers were investigated in 13 Xhosa and 13 Caucasian
distance runners, matched for performance, training volume and PRDA. Xhosa runners had less
MHC I and more MHC IIa fibres in muscle biopsies than Caucasian runners (P < 0.05). Xhosa
runners had lower plasma lactate at 80% peak treadmill speed (PTS) (P < 0.05), but higher lactate
dehydrogenase (LDH) (P < 0.01) and phosphofructokinase (P = 0.07) activities in homogenate
muscle samples. LDH activities in MHC I (P = 0.05) and IIa (P < 0.05) fibre pools were higher in
Xhosa runners. Xhosa athletes may thus have a genetic advantage or they may have adapted to
running at a higher intensity.
Six weeks of individually standardised high intensity interval treadmill training (HIIT) were
investigated in 15 well-trained runners. PTS increased after HIIT (P < 0.01), while maximum
oxygen consumption (VO2max) only showed a tendency to have increased as a result of HIIT (P = 0.06). Sub-maximal tests showed lower plasma lactate at 64% PTS (P = 0.06), with lower heart
rates at workloads from 64% to 80% PTS (P < 0.01) after HIIT. No changes were observed for
cross-sectional area, capillary supply and enzyme activities in homogenates muscle samples. LDH
activity showed a trend (P = 0.06) to have increased in MHC IIa pools after HIIT. Higher HIIT
speed was related to decreases in MHC I fibres, but increases in MHC IIa/IIx fibres (r = -0.70 and r
= 0.68, respectively, P < 0.05). Therefore, HIIT may alter muscle fibre composition in well-trained
runners, with a concomitant improvement in performance markers.AFRIKAANSE OPSOMMING: Skeletspier kan adapteer deur strukturele en metaboliese protein ekspressie te verander as gevolg
van stimulante. ‘n Spiergroep kan ook intern verskil om spesialisering in spierdele toe te laat.
Strukturele en metaboliese karaktereienskappe van ‘n individu word deels gereguleer deur gene,
maar kontraksie tydperk en intensiteit mag ‘n groter rol speel in spierfenotipe. Die doelwitte van
hierdie tesis was om ondersoek in te stel in: strukturele en metaboliese eienskappe in
spiergroepstreke, moontlike verhoudings tussen oefeningsvolume of intensiteit en baster vesels,
spier eienskappe in atlete van twee etniese groepe, en spier adaptasie in goed geoefende atlete
blootgestel aan hoë intensiteit interval oefening.
Miosien swaar ketting (MSK) isovorm inhoud en sitraat sintase (SS) aktiwiteite is gemeet in die
Quadriceps femoris (QF) spier van 18 wyfie rotte. Spiere was opgedeel in oppervlakkig, middel en
diep, asook distaal, sentraal en proksimale dele. MSK IIb en IIx was meer oorvloedig in
oppervlakkige dele (P < 0.05) met lae SS aktiwiteite in vergelyking met dieper dele. Isovorm
inhoud het ook verskil oor die lengte van diep dele. Dus bevat die QF gespesialiseerde streke en is
die area van monsterneming belangrik.
Baster vesel proporsies is ondersoek in spiermonsters van 12 middel afstand hardlopers en 12 niehardlopers.
MSK IIa/IIx van hardlopers het met oefeningsvolume/week gekorreleer (r = -0.66, P <
0.05), asook MSK IIa/IIx van nie-hardlopers met oefeningsure/week (r = -0.72, P < 0.01).
Gemiddelde voorkeur wedloop afstand (VWAG) het beter met MSK IIa/IIx gekorreleer in
hardlopers (r = -0.85, P < 0.001). MSK IIa/IIx mag dus meer verwant wees aan oefeningsintensiteit.
Veseltipe eienskappe en prestasie merkers was ondersoek in 13 Xhosa en 13 Caucasian langafstand
atlete, geëweknie vir prestasie, oefeningsvolume en VMAG. Xhosa hardlopers het minder tipe I en
meer tipe IIA vesels in hul spiermonsters gehad as die Caucasian hardlopers (P < 0.05). Xhosa
hardlopers het laer plasma laktaat by 80% van hul maksimale trapmeul spoed (MTS) (P < 0.05),
maar hoër laktaat dihidrogenase (LDH) (P < 0.01) en fosfofruktokinase (P = 0.07) aktiwiteite in
homogene spiermonsters gehad. LDH aktiwiteite in MSK I (P = 0.05) en IIa (P < 0.05)
veselbondels was hoër in Xhosa hardlopers. Xhosa atlete mag dus ‘n genetiese voorsprong geniet, of
hulle het geadapteer om by hoër intensiteite te hardloop.
Ses weke van geïndividualiseerde gestandardiseerde hoë intensiteit interval trapmeul oefening
(HIIT) was ondersoek in 15 goed geoefende hardlopers. MTS het verhoog na HIIT (P < 0.01), en
maksimale surrstof verbruik (VO2max) het ‘n neiging getoon om te verhoog het na HIIT (P = 0.07).
Submaksimale toetse het laer plasma laktaat by 64% MTS getoon (P = 0.06), met laer harttempos by werkladings 64% tot 80% MTS (P < 0.01). Geen veranderings was gemerk vir deursnit area,
kapillêre toevoer en ensiem aktiwiteite in homogene spiermonsters nie. LDH aktiwiteit het ‘n
neiging getoon om te verhoog het (P = 0.06) in MSK IIa veselbondels na HIIT. Hoër HIIT snelhede
was verwant aan ‘n daling in MSK I vesels, maar ‘n verhoging in MSK IIa/IIx vesels (r = -0.70 en r
= 0.68, respektiwelik, P < 0.05). HIIT mag dus spier veseltipe verander in goed geoefende
hardlopers, met gevolglike verbetering in prestasie merkers.Doctora
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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