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Spatiotemporal mapping of spontaneous smooth muscle motility in capacious organs: the ex vivo urinary bladder and in vivo gravid uterus of the rabbit: a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Massey University, Palmerston North, New Zealand
(Massey University, 2023-08-20) Hulls, Corrin
The temporal and spatial dynamics of propagating myogenic contractions in the wall of the resting ex vivo urinary bladder and in vivo gravid uterus of the rabbit were characterised by spatiotemporal maps of area strain rate, of linear strain rate and contractile patch analysis, and related to cyclic variation in intravesical pressure (pves) in the bladder, and electrophysiological recordings in the gravid uterus. In the urinary bladder, patches of propagating contractions (PPCs) enlarged and involuted with a frequency in near synchrony with peaks in intravesical pressure. Maximum area percentage of the anterior surface of the bladder undergoing contraction and the sizes of individual PPCs also coincided with the peak in pves. Moreover, pves varied cyclically with total area of contraction and with the indices of the size and aggregation of PPCs, indicating that PPCs grew and involuted by a combination of peripheral enlargement or shrinkage and by coalescence or fission with other PPCs, their areas being maximal at or around the peak in pves. Bladder PPCs originated and propagated within temporary patch domains (TPDs) and comprised groups of near synchronous cyclic individual contractions (PICs). The TPDs were located principally along the vertical axis of the anterior surface of the bladder, either to the left or the right of midline and changed in location from one side to side and from side to tip or base. The sites of origin of PICs within PPCs were inconsistent, consecutive contractions often propagating in opposite directions along linear maps of strain rate. Similar patterns of movement of PPCs within TPDs of the same form occurred in areas of the anterior bladder wall that had been stripped of mucosa. The synchronisation and extended propagation of PICs within PPCs and the concurrent variation in pves of the bladder were sometimes lost or diminished, uncoordinated PICs then occurred, propagated shorter distances, and had little effect on pves. There was no evidence that any influence of bladder shape on stress influenced the principal direction of propagation of either PCCs or PICs or the disposition of TPDs. The disposition and dynamics of PPCs and their component individual myogenic contractions in the wall of the resting ex vivo tetrodotoxinized urinary bladder of the rabbit were characterised by spatiotemporal maps and related to cyclic variation in pves before and after the administration of carbachol, isoprenaline, carbenoxolone, and the RhoA-inhibitor Y-27632. The results confirm that the bladder wall can exhibit two contractile states that are of similar frequencies to those of the two types of electrophysiological discharge described by previous workers. In the first of these, large low frequency cyclic PPCs predominate. In the second, small irregular, higher frequency PICs predominate. Comparison of the effects of the drugs on the timing and disposition of contraction suggested indicated that the local spatial spread of contractions in PPCs was governed largely by myocytes, whilst the propagation, frequency, and duration of PPCs was likely governed via gap junctions between interstitial cells of cajal- intermuscular (ICC-IM) and myocytes. Spontaneous and oxytocin-induced contractile activity was quantified in the bicornuate uteri of pregnant rabbits maintained in situ, using data from electrophysiological recordings and spatiotemporal maps, and compared statistically. Spontaneous contractions occurred over a range of frequencies in gravid animals at 18-21 and at 28 days of gestation and propagated both radially and longitudinally over the uterine wall overlying each foetus. Patches of contractions were randomly distributed over the entire surface of the cornua and were pleomorphic in shape. No spatial coordination was evident between longitudinal and circular muscle layers nor temporal coordination that could indicate the activity of a localised pacemaker. The density and duration of contractions decreased, and their frequency increased with the length of gestation in the non-labouring uterus. Increasing intravenous doses of oxytocin had no effect on the mean frequencies, or the mean durations of contractions in rabbits of 18-21 days gestation but caused frequencies to decrease and durations to increase in rabbits of 28 days gestation, from greater spatial and temporal clustering of individual contractions. This was accompanied by an increase in the distance of propagation, the mean size of the patches of contraction, the area of the largest patch of contraction and the overall density of patches. Together these results suggest that progressive smooth muscle hypertrophy and displacement with increasing gestation is accompanied by a decrease in smooth muscle connectivity causing an increase in wall compliance and that oxytocin restores connectivity and decreases compliance, promoting volumetric expulsion rather than direct propulsion of the foetus by peristalsis. The latter effects were reversed by the β2 adrenergic receptor agonist salbutamol thus reducing area of contraction, duration, and distance of propagation. The characteristics of smooth muscle contraction that are associated with the maintenance of tone during accommodation appear to be to be similar in the capacious organs discussed. Hence, it appears there is patchy rather than uniform local revision of the state of tonal contraction over the surfaces of the various capacious organs during accommodation that can undergo neural modulation. There appears to be less similarity in regard to the mechanisms that secure the voiding contractions in these capacious structures. Whilst the actuation of the necessary shorter term increase in tone may be ultimately dependent upon a mechanosensitive myogenic reflex, the relative contributions of autonomic, hormonal, mechanical and voluntary reflexes that reset the threshold of this reflex and aid in the relatively rapid expulsion of the contents, appear to vary between organs.
Dissecting the relationship between plasma and tissue metabolome in a cohort of women with obesity: Analysis of subcutaneous and visceral adipose, muscle, and liver
(Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology, 2022-07) Wu ZE; Kruger MC; Cooper GJS; Sequeira IR; McGill A-T; Poppitt SD; Fraser K
Untargeted metabolomics of blood samples has become widely applied to study metabolic alterations underpinning disease and to identify biomarkers. However, understanding the relevance of a blood metabolite marker can be challenging if it is unknown whether it reflects the concentration in relevant tissues. To explore this field, metabolomic and lipidomic profiles of plasma, four sites of adipose tissues (ATs) from peripheral or central depot, two sites of muscle tissue, and liver tissue from a group of nondiabetic women with obesity who were scheduled to undergo bariatric surgery (n = 21) or other upper GI surgery (n = 5), were measured by liquid chromatography coupled with mass spectrometry. Relationships between plasma and tissue profiles were examined using Pearson correlation analysis subject to Benjamini-Hochberg correction. Plasma metabolites and lipids showed the highest number of significantly positive correlations with their corresponding concentrations in liver tissue, including lipid species of ceramide, mono- and di-hexosylceramide, sphingomyelin, phosphatidylcholine (PC), phosphatidylethanolamine (PE), lysophosphatidylethanolamine, dimethyl phosphatidylethanolamine, ether-linked PC, ether-linked PE, free fatty acid, cholesteryl ester, diacylglycerol and triacylglycerol, and polar metabolites linked to several metabolic functions and gut microbial metabolism. Plasma also showed significantly positive correlations with muscle for several phospholipid species and polar metabolites linked to metabolic functions and gut microbial metabolism, and with AT for several triacylglycerol species. In conclusion, plasma metabolomic and lipidomic profiles were reflective more of the liver profile than any of the muscle or AT sites examined in the present study. Our findings highlighted the importance of taking into consideration the metabolomic relationship of various tissues with plasma when postulating plasma metabolites marker to underlying mechanisms occurring in a specific tissue.
The development of a steerable needle robot with biomaterials for the application of 3D printing in situ towards in vivo artificial muscles : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering at Massey University, Palmerston North, New Zealand
(Massey University, 2023) Odendaal, Jean Henri
Additive manufacturing is an emerging and continually growing field of research with great potential in the development of new technologies through which to change the world as we know it. This thesis offers a look from a 3D printing perspective towards the diverse fields of artificial muscle fabrication, bioprinting, polymer chemistry which can effect shape change or other responses under stimuli, as well an in detail investigation into steerable needle robotics and its potential as a mechanism for additive manufacturing. Since the 3D printing of (bio)polymers is generally reserved for the fabrication of structures on beds which are far away from where their intended use is intended, this thesis proposes an approach to 3D printing exactly the polymer that is of interest in the location in which it is intended. This thesis presents the research and development of a flexible steerable needle robot for the application of 3D printing (bio)polymers which could take the form of artificial muscles, bone, nerves, etc. in vivo. This is extremely challenging, however, and the research undertaken is intended towards building the capability to one day in future achieving this goal. Several experiments are presented which explore the characteristics of a custom developed steerable needle robot in application for 3D printing which include: its mechanisms, its control systems, its algorithms to accurately reach a target goal within a presented body, as well as it visualization system. Furthermore, this developed robot is then utilized to ”3D print” a (bio)polymer inside of a prepared phantom body (e.g., gelatine) to fabricate a bio-fiber. While the bio-fibers presented by this thesis are simple and do not react under any stimulus to act as an artificial muscle, there is a further future opportunity identified which could utilize advanced polymer chemistry to in fact achieve this end result. This thesis contributes towards the synthesis of multiple fields of research towards the goal of one day realizing the imagination of science fiction. Namely, the ability to quickly regenerate human tissue without the need for complex surgeries as well as the fabrication of fibers which could form part of artificial limbs or bodies.
Effect of processing on muscle structure and protein digestibility in vitro : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Food Technology at Massey University, Palmerston North, New Zealand
(Massey University, 2021) Chian, Feng Ming
The objective of this thesis was to investigate the effect of processing on meat protein properties, muscle structure and in vitro protein digestibility of beef. Meat processing techniques including pulsed electric field (PEF), shockwave (SW) processing, exogenous enzyme (actinidin) treatment, and sous vide (SV) cooking were explored, either alone or in combination, in this project. This thesis also aimed to study the diffusion of enzymes (actinidin from kiwifruit and pepsin in the gastric juice) into the meat. The first experiment investigated the effect of PEF processing alone on the ultrastructure and in vitro protein digestibility of bovine Longissimus thoracis, a tender meat cut (Chapter 3). It was observed that the moisture content of the PEF-treated samples (specific energy of 48 ± 5 kJ/kg and 178 ± 11 kJ/kg) was significantly lower (p < 0.05) by 1.3 to 4.6 %, compared to the untreated samples. The pH, colour, and protein thermal profile of the PEF-treated muscles remained unchanged. Pulsed electric field treatment caused the weakening of the Z-disk and I-band junctions and sarcomere elongation (25 to 38 % longer) of the muscles. The treatment improved in vitro meat protein digestibility by at least 18 %. In this thesis, the protein digestibility was determined in terms of the ninhydrin-reactive amino nitrogen released during simulated oral-gastro-small intestinal digestion. An enhanced proteolysis of the PEF-treated meat proteins (such as α-actinin and β-actinin subunit) during simulated digestion was also observed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The improvement in protein digestibility of the PEF-treated meat was supported by more severe disruption of Z-disks and I-bands observed in PEF-treated samples, at the end of simulated digestion. In the second experiment, PEF treatment (specific energy of 99 ± 5 kJ/kg) was applied to bovine Deep and Superficial pectoral muscles in conjunction with SV cooking (60 ℃ for 24 h) (Chapter 4). This muscle cut was tested as it is a tough cut and requires slow cooking. There was no significant difference detected in the specific activities of the sarcoplasmic cathepsins present in the cytosol between the control and PEF-treated samples, both before and after cooking. In addition, similar micro- and ultrastructures were observed between the control SV-cooked and PEF-treated SV-cooked pectoral muscles. The combined PEF-SV treatment increased the in vitro protein digestibility of the pectoral muscles by approximately 29 %. An improvement in proteolysis of the treated meat proteins (e.g. myosin heavy chains and C-protein) during simulated digestion was also observed using SDS-PAGE. More damaged muscle micro- and ultrastructures were detected in PEF-treated SV-cooked muscles at the end of in vitro oral-gastro-small intestinal digestion, showing its enhanced proteolysis compared to the control cooked meat. Next, the effect of SW processing and subsequent SV cooking on meat protein properties, muscle structure and in vitro protein digestibility of bovine Deep and Superficial pectoral muscles were investigated (Chapter 5 and 6). Shockwave processing (11 kJ/pulse) alone decreased the enthalpy and thermal denaturation temperature of the collagen (p < 0.05) when compared to the raw control, studied using a differential scanning calorimeter. The purge loss, pH, colour, and the protein gel electrophoresis profile of the SW-treated raw muscles remained unaffected. Shockwave processing led to the disorganisation of the sarcomere structure and also modified the protein secondary structure of the myofibres. After subsequent SV cooking (60 ℃ for 12 h), more severe muscle fibre coagulation and denaturation were observed in the SW-treated cooked meat compared to the cooked control. An increase in cook loss and a decrease in the Warner-Bratzler shear force were detected in the SW-treated SV-cooked meat compared to the control cooked meat (p < 0.05). The in vitro protein digestibility of the SW-treated SV-cooked meat was improved by approximately 22 %, with an enhanced proteolysis observed via SDS-PAGE, compared to the control SV-cooked meat. These results were supported by the observation of more destruction of the micro- and ultrastructures of SW-treated cooked muscles, observed at the end of the simulated digestion. The effect of the kiwifruit enzyme actinidin on muscle microstructure was studied using Picro-Sirius Red staining (Chapter 7). Meat samples were subjected to two different conditions, simulating meat marination (pH 5.6) and gastric digestion in humans (pH 3). Actinidin was found to have a greater proteolytic effect on the myofibrillar proteins than the connective tissue under both conditions. When compared with pepsin under simulated gastric conditions, actinidin had a weaker proteolytic effect on the connective tissue of cooked meats. Nevertheless, incubating the cooked meat in a solution containing both actinidin and pepsin resulted in more severe muscle structure degradation, when compared to muscles incubated in a single enzyme system. Thus, the co-ingestion of kiwifruit and meat could promote protein digestion of meat in the stomach. In addition, both actinidin and pepsin were successfully located at the edges of the muscle cells and in the endomysium using immunohistofluorescence imaging. The observations suggest that the incubation solutions penetrate into the muscle through the extracellular matrix to the intracellular matrix, enabling the proteases to access their substrates. Overall, the present work demonstrated that there were strong interactions between processing, muscle protein properties and structure, and in vitro protein digestibility of the meat. Processing induces changes in meat protein properties and muscle structure, which in turn affects the digestion characteristics of muscle-based foods.
Proof-of-concept of a 16-week foot muscle specific intervention programme on non-contact anterior cruciate ligament and lateral ankle sprain injury risk : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Sport & Exercise Science at Massey University, Manawatu, Palmerston North, New Zealand
(Massey University, 2020) van der Merwe, Carla
During high-intensity sports where abrupt decelerations and unanticipated changes of direction are prevalent, impaired foot function is thought to play a role in increasing the risk for non-contact anterior cruciate ligament rupture (ACLR) and lateral ankle sprain (LAS) injury. The risk for sustaining an ACLR is linked to increased rearfoot eversion and excessive, dynamic subtalar joint pronation coupled with internal rotation of the shank, leading to a larger knee valgus angle, and increasing anterior cruciate ligament (ACL) strain under high loads. Impaired forefoot stability is linked to larger moment arm lengths around the ankle joint, increasing the risk for lateral ankle sprain (LAS) under high loads. Previous research has shown that dynamic foot function can influence ankle, knee, and hip movement. Increasing forefoot and medial longitudinal arch stiffness modulates the distal-to-proximal transfer of rotational movement in straight-line walking and running as well as low intensity change of direction tasks. Foot stiffness is created by both passive and active structure in the foot. Passive structures include the foot bones and -ligaments and work in conjunction with the plantar fascia to create stiffness and stability. The intrinsic and extrinsic muscles acting on the foot act in synergy to create stiffness actively. However, current prophylactic programmes do not aim to explicitly train the foot muscles. The aim of this project was thus to provide proof of concept for a foot muscle specific training intervention on dynamic foot function, as well as risk factors associated with ACLR and LAS injury. Establishing proof of concept provides valuable information for future large-scale randomised control studies investigating the integration of a foot muscle specific intervention in to ACLR and LAS injury prevention programmes. The overview of the functional anatomy of the foot in Chapter 2 described the bones that form the joints of the foot as well as the muscles that move the bones of the foot. The interaction of the segments of the foot is described as well as the way in which the foot is modelled. The chapter also provided the contextual evidence for exercise selection. Chapter 4 reviewed the literature and highlighted the relationship between dynamic, excessive subtalar joint pronation and rearfoot eversion to internal tibial rotation, the increase in the knee valgus angle and ACL strain. A link between instability of the forefoot and a larger hallux extension range of motion increasing risk for LAS is discussed. The review also discussed the effect of intrinsic and extrinsic foot muscles on movement of the foot segments and general foot function. A hypothesis was formed that a foot muscle specific intervention has the potential to influence dynamic foot function and risk factors associated with ACLR and LAS, supplementing current prophylactic programmes. Current literature does not definitively describe the coupling relationship between the segments of the lower limb nor the coupling between the segments of the foot during high-intensity unanticipated change of direction tasks. It is thus unknown whether training the foot muscles in an attempt to modulate the transfer of rotational forces from distal-to-proximal segments to decrease injury risk, is justified. A modified vector coding technique was adapted to describe and quantify the coordination patterns between the lower limb and foot segments, respectively. In Chapter 5 the literature regarding the modifications to the vector coding technique and its development from the continues relative phase method of describing movement relationship between objects was presented. The coupling relationship between the tri-planar calcaneus and transverse plane rotation of the shank during unanticipated change of direction tasks was described in Chapter 6. A distal-to-proximal coupling relationship between frontal- and transverse plane movement of the calcaneus and transverse plane rotation of the shank was established. The distal-proximal coupling between the calcaneus and shank suggested that shank rotation may be modulated by manipulating the frontal and transverse plane movement of the calcaneus. It thus seems worthwhile to investigate whether training the muscles that act on the foot would manipulate shank rotations and, in this way, decrease the strain on the ACL, reducing ACLR risk. In Chapter 7 the coupling relationship between the foot segments was described as it influences LAS risk. The forefoot was the only point of contact during unanticipated change of direction tasks. Throughout stance, an anti-phase coupling relationship in the form of metatarsal flexion coupled with calcaneus eversion, and metatarsal extension was coupled with calcaneus inversion. These coupling relationships indicated the importance of forefoot function in calcaneus control and potentially LAS risk. In the loading phase, metatarsal inversion was coupled with calcaneus inversion, potentially increasing LAS risk if metatarsal inversion was not limited. At maximum calcaneus inversion- and adduction velocities, both of which are associated with increased risk for LAS, hallux and metatarsal flexion accelerated. The increased forefoot flexion acceleration indicating the importance of the forefoot stiffness in creating forefoot stability, potentially influencing whole foot stiffness and lateral ankle stability during change of direction tasks. As the forefoot provides stiffness the foot is likely to be more stable and the rearfoot segments are free to move and align with the shank, potentially decreasing LAS risk. It seems thus important to investigate whether training the foot muscles will influence LAS risk. The 16-week progressive foot muscle specific intervention program was detailed in Chapter 8. Exercise components, selection and progression was described. The outcomes of the proof-of-concept study revealed that training the muscles acting on the foot show potential to resist the deformation of the medial longitudinal arch (MLA). Resistance to MLA deformation potentially played a role in the observed decrease of the maximum knee valgus angle, and ACLR risk factor, of the training group (TG). LAS injury risk factors, maximum ankle inversion angle and maximum ankle eversion moment arm length were also smaller for the group undergoing the intervention training. The decrease in the maximums of these LAS risk factors was potentially influenced by the increasing stiffness of the metatarsal anterior transverse arch (MetATA), which is likely to increase foot and ankle stability. Guidelines for future randomised controlled trials included variables to consider ensuring the groups are well matched before the intervention. A proposal regarding the methodology and implementation of an injury prevention programme as well as sample size recommendations were outlined. To ensure the groups are well matched before the intervention it would be prudent to match athletes for stance times, peak ground reaction forces (GRF) in addition to sport and body mass index (BMI). During data collection, the approach speed and thus the timing of the unanticipated change of direction task proved difficult to monitor and control, which potentially influenced the kinetic and kinematic outcomes of the pilot study. The TG also had low compliance to training which could have influenced the result of the intervention. Sample size calculations revealed that a sample size of 30 (falling within the recommended size for biomechanical studies) are needed to find significant differences in foot arch and foot segment angle variables. However, a larger number of athletes are needed per group to establish changes to ACLR and LAS risk variables. Functional anatomy and the coupling relationship between the segments of the lower limb and foot segments justified investigating the effect of foot muscle-specific intervention on ACLR and LAS risk factors. The pilot study revealed that training the muscles acting on the foot seem to influence foot function, but the effect on risk factors associated with ACLR and LAS is unclear. Following the guidelines as described in future randomised control trial is necessary to establish the effectiveness of integrating foot muscle-specific exercises into current ACLR and LAS prophylactic programmes.
Can backward sled towing potentiate five metre sprint performance? : a thesis presented in partial fulfilment of the requirements for the degree of Master of Sport and Exercise at Massey University, Palmerston North, New Zealand
(Massey University, 2019) Monaghan, Daniel John
Post-activation potentiation (PAP) describes an augmentation within muscle properties, with the ability to enhance muscular performance. Due to the complexity of this highly individualised phenomenon, PAP has the greatest effect in well-trained populations. Back squat, sled towing, and sled pushing protocols have shown to acutely improve 20 m sprint performance. Potentiating activities that reflect the specific movement profiles of the performance activity are proposed as most effective, suggesting a possible relationship between muscle specific potentiation and augmented sprint performance. Therefore, the use of a quadriceps dominant sprint related exercise (i.e., backward sled towing) may acutely enhance sprint performance. The objectives of this study were to determine whether backward sled towing can elicit a PAP response to enhance 5 m sprint performance, and to determine if sled loading via a reduction in velocity can elicit an improvement in 5 m sprint performance. A randomised design was used to examine the effects of forward and backward sled tow loading of 35% and 55% reduction of individual’s maximal velocity (rVelmean) on 5 m sprint performance. Eighteen participants performed one familiarisation session, followed by four intervention sessions (55% rVelmean backward; 55% rVelmean forward; 35% rVelmean backward; 35% rVelmean forward) separated by a minimum of 24-hours. Intervention sessions included baseline un-resisted 5 m sprints, and the collection of maximum voluntary contractions of lower limb musculature via surface electromyography (EMG), followed by three loaded sled tows over a distance of 3.2 m or 5 m for heavy and light loads, respectively. An un-resisted 5 m sprint was then completed following 6 and 12 min rest. Mean sprint velocity, EMG, and sprint kinematic and temporal data were collected during each session. EMG was used to determine if a potentiated effect was due to changes in neural excitation. Sled towing, irrespective of load or rest period, produced no significant change in 5 m sprint velocity (p > 0.05). Significant difference was found between both 35% and 55% backwards calculated velocity reduction and actual velocities during towing (p < 0.01). There was no significant change in EMG across sessions. Kinetic and temporal data suggested no significant changes in baseline measures; however, current findings highlight the importance of vertical force production during sprint acceleration. Sled towing to potentiate sprint performance using a reduction of velocity requires further investigation. The author acknowledges that greater time under tension during conditioning activities may result in greater sprint related potentiation. However, further research is required to assess the legitimacy of this speculation.
The use of facial hedonic measurements to explore relationships between food structure, oral processing and acceptability : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy, completed at the School of Psychology at Massey University (Albany campus), New Zealand
(Massey University, 2017) Li, Bei
Hedonic responses to food should vary over time because flavour perception during oral processing is dynamic. Hedonic liking scales and temporal drivers of liking (TDL) are frequently used to assess food acceptability during product development and evaluation. These tools are only able to provide an assessment of liking at a static time point and they are also interruptive of normal food behaviours. To overcome these limitations, this thesis assesses dynamic affective responses to imagery stimuli and tastant stimuli using facial electromyography as a psychophysiological measurement (EMG) (Chapter 3.3 and 4.4). Facial muscles that are used to display negative affect (M. Corrugator supercilii and M. levator), a muscle that is active when smiling (M. zygomaticus major) and a muscle that is active when chewing (M. masseter) were all recorded using facial EMG. Additionally, multi-level modelling (MLM) was used to predict the hedonic liking ratings to these stimuli (Chapter 5.3.3). This direct measure revealed that dynamic affective responses were able to be discriminated using facial EMG. Strong activity in corrugator and levator muscles was evoked by disliked stimuli, whereas for liked stimuli only the zygomaticus muscle increased in activity. From the multi-level modelling results, hedonic liking ratings were able to be predicted using facial muscle activity. Importantly, hedonic liking ratings were able to be predicted using muscle data at the beginning and the end of the tasting (Chapter 4.4). These experiments confirm that facial EMG is not only able to assess dynamic affective responses to foods, but also that facial muscle activity can predict hedonic liking ratings.
A study of capillaries in equine skeletal muscle : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Anatomy and Physiology at Massey University
(Massey University, 1993) Slassor, Lynn Elizabeth
Four horses of varying ages, breeds and sex were used to evaluate the variation in capillary supply and fibre type proportions in a range of equine skeletal muscles. A total of 100 muscles were sampled from the four horses. These samples were stained for myosin ATPase activity from which fibres were classified as ATPase low or ATPase high. Visualisation of capillaries was also achieved by the use of this stain. The 100 muscle samples were assessed for capillary/fibre ratio and for capillary density. From these muscles, 22 were chosen for more detailed analysis on the number of capillaries surrounding each fibre and the fibre area for ATPase low and ATPase high fibres individually. Fibre type distribution was found to vary from 0% to 100% ATPase low fibres and therefore a complete range of muscle fibre type proportions were obtained. An extensive range was found within a muscle or between adjacent muscles. There was no significant difference in mean fibre area between the two fibre types in the muscles examined. The percentage of ATPase low fibres and capillary/fibre ratio showed a significant regression (regression coefficient = 0.36, p < 0.05) For both the ATPase low fibres and the ATPase high fibres, larger fibres were surrounded by more capillaries. It was concluded that, although fibre size is the primary determinant for capillary supply, the contractile properties of the muscle in which a fibre is found will also determine the number of capillaries it should have at its disposal.
Amino acids and skeletal muscle growth in lambs : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University, Palmerston North, New Zealand
(Massey University, 2014) Sales, Francisco
The objectives of this thesis were three-fold. Firstly, to identify whether reduced muscle growth in twin compared to singleton lambs during late pregnancy and early post-natal life was associated with changes in the concentration of intracellular free amino acids (FAA) that may play a role in the regulation of pathways involved in muscle growth. Secondly, to evaluate if supplementation with a specific amino acid improved muscle growth in twin fetuses/lambs, and thirdly to examine the role of mTOR signalling. The first objective was investigated by examining the differences in muscle FAA concentrations between singleton and twin fetuses in late pregnancy from either heavy or light ewes, under a maintenance or ad libitum feeding regimen. Twin fetuses had lower intracellular FAA concentrations of arginine (Arg), leucine, valine, glutamine, while muscle mass was positively associated only with Arg concentration. A further study characterised the FAA concentrations of singleton and twin well-fed lambs at 140 days pregnancy and at weaning. High levels of Arg and glutamine were associated with muscle growth during pregnancy; however several FAA appeared to be associated with muscle growth to weaning. Objective 2 was tested by examining the effects of maternal Arg administration on fetal muscle growth and mTOR signalling. Well-fed twin-bearing ewes, received either an intravenous bolus of Arg or saline solution 3 times daily from 100 days of pregnancy to parturition. Female lambs from supplemented ewes had increased birth weight and muscle mass at market weight, associated with increased ribosome number and mTOR abundance at P140 and increased ribosome number at weaning, compared to control females. An additional experiment supplemented twin-born lambs with Arg via fortification of colostrum and milk replacer from birth to 28 days or from birth to 70 days of life. Supplementation increased body growth between 7 and 21 days of life. Only supplemented females expressed higher muscle weight at 70 days, compared with control females. Collectively, these results indicate that singleton and twin muscle differs in Arg concentration, and the use of Arg during pregnancy and early neonatal life improves muscle growth in females. This action potentially occurs through mTOR signalling, and ameliorates reduced females weight in at birth and growth from birth to weaning.
The effects of acute alcohol consumption on muscular performance and recovery after exercise : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Sport and Exercise Science at Massey University, Manawatu, New Zealand
(Massey University, 2012) Barnes, Matthew John
The acute consumption of alcohol after sport, particularly team sport, is common place. Indeed, sportspeople regularly consume hazardous levels of alcohol at rates significantly higher than non-sportspeople during this period. Much focus is given to behaviours that may enhance the rate of recovery after sport/exercise however little attention has been given to behaviours that may have the opposite, negative effect such as alcohol consumption. Further, while it is widely recommended that alcohol consumption be avoided if damage/injury to skeletal muscle is present little direct evidence exists to support this recommendation. As acute post-eccentric exercise alcohol consumption has previously been shown to impact the magnitude of force loss associated with such exercise, the overall purpose of this thesis was to further investigate the interaction between acute alcohol consumption and damage to skeletal muscle. Within this thesis the consumption of 1 g, but not 0.5 g, of alcohol per kg bodyweight was found to magnify the force loss typically observed in the days after laboratory based, eccentrically biased exercise. This affect was shown to be due to a combination of decreased neural drive and alterations at the muscle level in the days following the damaging event. Investigation into the effect of alcohol on recovery from an ecologically valid game simulation found that acute alcohol consumption and the stresses induced by a rugby match may interact to reduce lower body power output in the days after the match. Other sports specific performance measures, testosterone and cortisol, and markers of immunoendocrine function were unaffected by this combination. In conclusion, the findings presented in this thesis provide evidence that the consumption of alcohol, even at volumes considerably less than those regularly consumed by sportspeople, has deleterious effects on muscle function when consumed soon after strenuous eccentric exercise. This affect is not seen with a lower dose of alcohol or with modest levels of muscle damage. Important to the wider sporting community, these data support the recommendation of limiting alcohol consumption when damage/injury to skeletal muscle has occurred.

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