Dissertations / Theses on the topic 'Myography'

Background: Patients with chronic kidney disease (CKD) face a markedly increased risk of cardiovascular morbidity and mortality. In this setting, aberrant endothelial function is a key initiating event in vascular disease. Haemodialysis (HD) patients characteristically exhibit significant abnormalities in vascular structure and function, which impact cardiovascular morbidity and mortality. Micro- and macro-vascular dysfunctions are the principle factors contributing to the increased risk of morbidity and mortality associated with obesity. Impaired endothelial function represents the earliest abnormality in the development of vascular disease in obesity and exhibits increased risk of cardiovascular disease. We first aimed to investigate the effect of HO and obesity on the vascular reactivity through directly examines the isolated subcutaneous arteries using wire myography. The second goal was to study changes that might underlie altered vascular responses following bariatric surgery and whether reduction in weight improves endothelial function. We also intended to correlate the ex vivo myography data with the in vivo results of pulse wave velocity (PWV) and blood pressure (BP) in both HO and obese patients. Methods: Abdominal subcutaneous fat biopsies were obtained from HO patients (n= l l ) during non-HO visits through small lower abdominal incisions using local anaesthetics; obese patients (n=12) during the time of bariatric surgery (using a laparoscopic port); and non-HD, non-obese healthy controls (n=26) during the time of elective surgery (hernia repair). Additional abdominal subcutaneous fat samples (n=4) were also obtained from obese patients at six months after bariatric surgery through an extra incision in the lower abdominal region using local anaesthetics. Different-sized arteries (small with internal diameter between 200 urn - 500 urn and large between 600 urn - 900 urn) were dissected, mounted and conducted on a wire myography on the same day. Cumulative concentration-response curves were constructed for the following vasoactive agents: noradrenalin (NA), endothelin-I (ET-I), U46619, angiotensin II (AngII), vasopressin, bradykinin (BK), acetylecholine (Ach) and sodium nitroprusside (SNP). Carotid-to-femoral arterial PWV was measured using an oscillometric device (Vicorder, Skidmore Medical Ltd., UK) for HD and obese patients in addition to measuring blood pressure (BP). Laboratory data were expressed as mean ± SEM and groups were compared by t-test. Results: In both HD and obese patients, greater contractile response to different vasoconstrictors was observed in different-sized arteries compared to control group. Although the potency of these drugs was similar between HD patients and controls, large vessels of HD patients were highly potent to U46619 and vasopressin compared to controls. Similarly, in obese patients, large vessels were also significantly more sensitive to U46619 and vasopressin than that of controls, while small vessels were highly potent to vasopressin response. The maximum vasorelaxation response of small and large vessels to Ach and BK (endothelium-dependent vasodilators) was significantly lower in both HD and obese patients than vessels of controls. A similar response to SNP (an endothelium-independent vasodilator) was obtained in all groups. However, the potencies of all vasodilators in all groups were similar. In HD patients, in vivo PWV was significantly correlated with the maximum contractile response of large arteries to vasopressin response (r = 0.829, P = 0.042). PWV was positively correlated with the percentage of maximum contractile response of small arteries to vasopressin (r = 0.886, P = 0.019). The diastolic but not systolic BP of HD patients was significantly inversely correlated with the response of large vessels to SNP (r = -0.954, P = 0.012), it was also negatively correlated with the percentage of contractile response of small arteries to vasopressin (r = -0.829, P = 0.042). There was no correlation observed in the responses of isolated small arteries to the other vasoconstrictor substances in terms of PWV or BP. In obese patients, The PWV was significantly correlated with the maximum contractile response of large arteries to U46619 (r = 0.928, P = 0.006), and with the maximum contractile response of small arteries to vasopressin (r = 0.885, P = 0.033).However, positive correlation was obtained between systolic (but not diastolic BP) of obese patients and the response of large vessels to U46619 (r = 0.785, P = 0.048). There was no significant difference in the vasocontractile or vasorelaxation responses of isolated vessels in obese patients before and after surgery; however, a trend of more contractile response to vasoconstrictors was observed in the obese group before surgery compared to those after surgery. Conclusion: These results suggest that HO and obesity can alter endothelial function via an incremental increase in vasocontractility in response to various stimuli and an impaired vasodilatation response to endothelium-dependent agonists in isolated different-sized vessels. In both groups, ex vivo arterial responses were correlated to in vivo assessment of arterial function. The association between these risk groups and endothelial dysfunction in isolated arteries would be expected to accelerate cardiovascular events, which impacts cardiovascular morbidity and mortality among these groups of patients. Therefore. the development of cardiovascular disease is mediated, at least partly, by functional alterations at the level of microcirculation.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 71-72).
This thesis describes the design of a novel handheld electrode probe and measurement system for use in rotational electrical impedance myography (EIM), which is a method for diagnosing neuromuscular disease. The probe can be controlled from a PC via USB and uses an array of small electrode cells that can be connected together into larger electrodes with the help of crosspoint switches. A measurement system capable of fast multifrequency impedance measurement has also been developed. The two systems have performed well, with measurements being very close to those achieved by more traditional electrical impedance myography methods.
by Michael Scharfstein.
M.Eng.

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 73-77).
This thesis discusses the need for a more quantitative, objective, and non-invasive method of neuromuscular disease assessment. Currently, the best solution to this problem requires large, bulky pieces of equipment and the time-consuming placement of numerous individual electrodes. In this thesis, a new hardware device and its corresponding software interface are described. The device includes a reconfigurable hand-held probe with an electrode head which both makes contact with the skin and eliminates the need for individual electrodes. The new software interface provides a simple way for users to control the device through the USB interface of a laptop. In addition, various strategies were explored for leveraging the linearity of the muscle tissue in order to shorten the measurement time.
by Roshni C. Cooper.
M.Eng.

Only a small amount of the available literature is concerned with venous control in lower vertebrates, such as fish. It has even been suggested that veins in fish are not important factors in active regulation of venous return. Preliminary work carried out for this thesis strongly refuted this assumption, highlighting gaps in the existing literature. As a result of the lack of information pertaining to the physiology of the central venous compartment of the circulation, my objective has been to investigate various aspects of this in the hagfish Eptatretus cirrhatus. Hagfishes, with the lowest arterial blood pressures and highest blood volumes amongst the chordates, are the earliest surviving group to separate off from the chordate lineage. They provide a unique opportunity to investigate likely physiological mechanisms in ancestral chordates. The data presented in this thesis suggest thtat 1) E. cirhatus exhibit some cardiovascular compensation during volume manipulation, however this only occurs with volume loading and not during volume depletion, 2) Veins from E. cirrhatus can respond vasoactively to adrenergic stimulation in vitro and 3) Plasma catecholamines in E. cirrhatus also respond to volume manipulation and provide a potential in vivo mechanism for the control of changes in cardiovascular parameters that were observed during volume loading.

Many neurological disorders are associated with speech and swallowing abnormalities. In turn, oropharyngeal dysfunction can negatively impact quality of life and survival. Reliable tools that quantify underlying motor deficits are needed for use in clinical care and therapeutic trials. As painless, non-invasive techniques, electrical impedance myography (EIM) and quantitative ultrasonography (QUS) are well-suited to provide biomarker data. Both of these user-friendly methods can provide sensitive indicators of disease status when applied to the limbs; existing work suggests that the examination of orofacial muscles could add valuable information. This document explores the role of EIM and QUS in evaluating tongue health and bulbar dysfunction in patients with neuromuscular conditions.

Background: Endothelial dysfunction is a key factor in the development of vascular complications in insulin resistance and diabetes and recent studies have established that endothelium-derived hyperpolarising factor (EDHF) plays an important physiological role in endothelium-derived relaxation responses, especially in small arteries and arterioles. Objective: This project aimed to identify the role of, and characterise, EDHF in animal models of insulin resistance, including the obese Zucker rat (OZR) as well as the fructose-fed (FF) Sprague-Dawley rat. Methods: Vascular function was studied in third-order mesenteric arteries from male and female Zucker rats using pressure myography, and in lobar arteries from male FF rats using wire myography. Endothelial function was determined by studying responses to the endothelium-dependent dilator acetylcholine (ACh) and the endothelium-independent dilator levcromakalim in the presence of a variety of inhibitors to study the roles of NO, EDHF and gap junctions. The effect of insulin resistance on gap junctions was further assessed by measuring the protein and mRNA expression of vascular connexins. Protein levels were determined by western blotting followed by semi-quantitative analysis of band intensity, whilst mRNA levels were quantified using real-time PCR, in which beta-actin was used as the housekeeping gene. Results: Metabolic parameter comparisons confirmed that male OZRs were type 2 diabetic, whilst female OZRs were insulin resistant. Responses to ACh were reduced in both the male and female OZRs compared with their gender controls, with the male OZR showing a greater degree of endothelial dysfunction. In all Zucker third-order mesenteric arteries, inhibition of NO had no effect; however inhibitors of EDHF abolished relaxation responses to ACh. Inhibitors of gap junctions associated with connexin 40 significantly (p less than 0.05, Student's t-test) attenuated the maximal response to ACh in the LZR, but had no effect in the OZR. Comparison of Western blot band intensity indicated that connexin 40 protein levels in mesenteric vascular homogenates in the OZR were significantly smaller (p less than 0.05, Student's t-test) than in the LZR, with no difference in connexin 43 protein levels. mRNA levels showed a significant (p less than 0.05, Student's t-test) decrease in connexin 40 expression in the OZR compar ed with the LZR, with no change in connexin 43 mRNA expression. Although FF rats did develop insulin resistance, responses to ACh were not altered in the FF rats as compared with their controls, and ACh responses were abolished by NO inhibitors. Conclusion: The findings presented in this thesis demonstrate that endothelial dysfunction is present in third-order mesenteric arteries from insulin-resistant female and type 2 diabetic male OZRs, and is associated with a defect in EDHF. However, endothelial function was not compromised in the insulin-resistant FF rats. Furthermore, the reduction in EDHF-mediated vasodilatation in the mesenteric arteries from female OZRs was associated with the functional absence of connexin 40-related gap junctions as well as a reduction in connexin 40 protein and mRNA levels. This novel finding suggests that gap junctions associated with connexin 40 may be a potential therapeutic target for diabetic vascular disease.

Orientador: Marcos Roberto de Mattos Fontes
Resumo: Os acidentes ofídicos constituem um problema de saúde pública, afetando regiões de clima tropical e subtropical e áreas rurais e pobres de países da América Latina, África, Ásia e Oceania. No Brasil, o gênero Bothrops é responsável por cerca de 90% dos acidentes ofídicos notificados, cujo envenenamento é caracterizado por intensa mionecrose local ineficientemente neutralizada pela soroterapia. O veneno botrópico possui uma classe de proteínas miotóxicas estruturalmente semelhantes às fosfolipases A2 (PLA2), responsáveis por induzir lesões musculares por um mecanismo não-catalítico parcialmente explicado por diferentes hipóteses. Contudo, há evidências que os efeitos miotóxico e paralisante in vitro são decorrentes de sua atividade desestabilizadora de membranas e que atuam em sinergia com as PLA2 catalíticas no envenenamento. Neste estudo, foi desenvolvido um novo protocolo de purificação da miotoxina não-catalítica (PLA2 homólogas ou proteínas PLA2-like) botrópica BthTX-I, a qual foi avaliada em testes cristalográficos, calorimétricos, miográficos e morfológicos. Potenciais inibidores vegetais da classe dos cinamatos foram co-cristalizados com a BthTX-I e testados em inibir as lesões e paralisia musculares in vitro promovida pela toxina a fim de evoluir no conhecimento da relação estrutura/atividade das PLA2 homólogas miotóxicas. Dentre todos os compostos testados, os ácidos chicórico e caftárico apresentaram-se como excelentes inibidores da BthTX-I. Contudo, foi possível ap... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Snakebites are a public health problem, concerning tropical and subtropical regions, rural and poor areas of Latin America, Africa, Asia and Oceania countries. In Brazil, Bothrops genus accounts for about 90% of reported snakebites, whose envenomation is characterized by intense local myonecrosis inefficiently neutralized by antivenom. A class of myotoxic proteins found in Bothrops venoms which is structurally similar to phospholipases A2 (PLA2), is responsible for inducing muscle injuries by a non-catalytic mechanism, partially explained by different hypotheses. However, there are evidences that myotoxic and in vitro paralyzing effects are due to their destabilizing-membrane activity and they act in synergy with the catalytic PLA2 myotoxins in envenomation. In this study, it was developed a new protocol for purification of a non-catalytic botropic myotoxin (PLA2 homologues or PLA2-like proteins) BthTX-I, which was evaluated by crystallographic, calorimetric, myographic and morphologic assays. Potential plant inhibitors of cinnamates class were co-crystallized with BthTX-I and tested to inhibit in vitro paralysis and muscle injuries promoted by the toxin. Among all the compounds tested, the chicoric and caftaric acids presented excellent BthTX-I inhibition characteristiscs. However, only chicoric acid (CA) we were able to perform crystallographic experiments, which presented different structural characteristics compared to other ligands and bothropic toxins. According to the ... (Complete abstract click electronic access below)
Doutor

La misura senza contatto di segnali fisiologici e vitali ѐ uno dei fattori di maggior rilievo per la strumentazione biomedicale di nuova generazione. I metodi di misura con contatto di parametri fisiologici presentano dei limiti come l’invasività con la pelle, l’impossibilità di poter applicare gli elettrodi in particolari regioni corporee o in parti del corpo ristrette ed ѐ necessaria la collaborazione del soggetto. Per queste ragioni la Vibrometria Laser Doppler (LDV) ѐ stata introdotta per acquisire segnali associati all’attività biologica del corpo umano, per eliminare il contatto con la pelle e per rendere le prove più semplici. Questa tesi di dottorato si focalizza sull’utilizzo dell’LDV per la misura dell’attività cardiovascolare e muscolare in quanto sono parametri che permettono una valutazione dello stato di salute ed emozionale del soggetto sotto esame. Infatti, nella pratica clinica e giornaliera ѐ fondamentale la valutazione dei segnali vitali ed emozionali e la tecnologia LDV ha la capacità di misurare i movimenti vibrazionali della superficie corporea senza contatto, con una elevata sensibilità di acquisizione e ad una distanza notevole. Questo lavoro ha lo scopo di esplorare e dimostrare le capacità della Vibrometria Laser Doppler nel misurare la frequenza cardiaca con una incertezza di ± 9 ms rispetto alla tecnica convenzionale (elettrocardiografia) ed altri parametri cardiovascolari puntando il fascio laser sulla carotide. Infine, LDV viene usato anche per la misura delle proprietà di contrazione muscolare dei grandi e piccoli muscoli (muscoli facciali) con una accuratezza elevata sempre in confronto alla tecnica considerata gold standard (elettromiografia di superficie). La tecnica LDV, senza contatto, può dunque sostituire le tecnologie convenzionali, più invasive che richiedono l’applicazione di sensori sulla pelle del paziente e in questo modo si possono ottenere misurazioni di parametri cardiovascolari e muscolari completamente senza contatto andando a migliorare la qualità delle prove come interrogatori, controlli di sicurezza, controlli clinici e programmi di riabilitazione.
The measurements of physiological and vital signals without contact is a relevant research issue in modern biomedical instrumentation. Contact methods presently used to measure physiological parameters sometimes can be inconvenient or inadequate for patient comfort or to detect signals from particular body regions and the presence of cables is a limit for the patient mobility. For these reasons, the Laser Doppler Vibrometry (LDV) technique was introduced to acquire signals associated with biological activity in the human body, to avoid the contact with the skin and to make the tests easiest. This dissertation is focused on the novel use of LDV to measure cardiovascular and muscular activity to evaluate health and emotional state of participants. In fact, in daily and clinical practice is fundamental the assessment of vital and emotional signals and the LDV technique has the capability to measure the vibrational movements of the skin surface without contact, with a high sensitivity of acquisition and at a distance of several meters. In this work, the possibility to use LDV to measure the heart rate, with a deviation of ± 9 ms from the conventional gold standard method (electrocardiography) and other cardiovascular parameters assessed from the carotid artery are measured with LDV, will be explored and demonstrated. Finally, LDV is used to measure muscle contraction properties from the big and small muscles (facial muscles) with a high accuracy in confront of the gold standard method (surface electromyography). Using the non-contact LDV technique might provide surrogate measures for those obtained using conventional, more obtrusive assessment methods that require attached sensors and so, measurements of cardiovascular and muscular parameters without contact can improve tests as investigations, safety controls, clinical controls, rehabilitation programs.

Introdução: O papel do sistema nervoso simpático (SNS) na remodelação ventricular esquerda na insuficiência aórtica crônica (IAo) é pouco conhecido. O aumento da atividade do SNS tem associação com remodelamento ventricular e mau prognóstico na insuficiência cardíaca (IC) não valvar, fazendo do seu bloqueio farmacológico importante conduta terapêutica. A despeito de similaridades na evolução clínica da IAo com IC não valvar, não há estudos com mensuração direta da atividade do SNS em IAo. Objetivo: Quantificar a atividade nervosa simpática muscular (ANSM) em pacientes com IAo importante em três situações clínicas, representativas da história natural dessa doença. Métodos: Trata-se de estudo transversal, unicêntrico, incluindo 30 pacientes com IAo importante que foram alocados em três grupos: (I) assintomáticos (n = 10, 70% homens, 37,4 ± 13,6 anos), (II) sintomáticos em pré-operatório de troca de valva aórtica (TVA) (n = 10, 70% homens, 42,2 ± 12,1 anos) e (III) - pós-operatório de TVA (n = 10, 80% homens, 41,2 ± 15,4 anos). Grupo controle formado por voluntários saudáveis sem doença cardíaca estrutural (n = 10) correspondentes para idade, sexo e IMC também foram avaliados. Variáveis clínicas, ecocardiográficas e BNP (peptídeo natriurético atrial) foram analisadas nos grupos. Apenas a pressão arterial sistólica era significativamente menor no grupo III. A ANSM foi mensurada utilizando a técnica padrão de microneurografia muscular (MM). A variável desfecho foi a Resumo média do número de espículas obtidas num registro contínuo de 10 minutos de MM. Resultados: Os grupos IAo não diferiram em relação às características demográficas, antropométricas e ecocardiográficas, assim como etiologia e BNP. A média de espículas obtidas pela MM, representativa da ANSM, nos grupos I, II, III e controle foi, respectivamente, 25,5 ± 4,1, 25,1 ± 3,6, 28,6 ± 6,5 e 15,6 ± 1,5 (p=0,001). Houve apenas diferença estatística entre os grupos IAo e o grupo controle. Conclusão: Houve aumento significativo da ANSM em pacientes com IAo importante associado ao remodelamento ventricular esquerdo em relação a indivíduos sem doença cardíaca estrutural. A ANSM foi similar em pacientes com IAo importante assintomáticos, sintomáticos e em pós-operatório de TVA. A participação da ação do SNS na IAo deve estar associada ao remodelamento ventricular, mas sem correlação com mudanças clínicas
Introduction: The role of sympathetic nervous system (SNS) in the left ventricle remodeling of severe aortic regurgitation (AR) remains poorly understood. The increase in SNS activity is associated with ventricular remodeling and poor prognosis in non-valvular heart failure (HF), making its pharmacological blockade an important therapeutic approach. Despite similarities in the clinical evolution of AR with non-valvular HF, there are no studies with direct measurement of SNS activity in AR. Aims: The present study aimed to quantify muscular sympathetic nervous activity (MSNA) in patients with severe AR in three clinical situations: asymptomatic, symptomatic before aortic valve replacement (AVR), and patients submitted to AVR. Methods: Thirty patients with severe AR were allocated to three groups: (I) asymptomatic patients (n=10, 70% men, age: 37.4 ± 13.6), (II) symptomatic patients before AVR (n=10, 70% men, age: 42.2 ± 12.1), and (III) patients submitted to AVR (n=10, 80% men, age: 41.2 ± 15.4). Healthy volunteers (n = 10) matched for age, sex, and BMI were also assessed. The AR groups did not differ in relation to etiology, demographic, anthropometric or echocardiographic data. Only systolic blood pressure was significantly lower in group III. MSNA was recorded using microneurography, with a spike per minute result. Results: The means of 10-minute recordings in groups I, II, III and control were 23.2 ± 6.4, 25.5 ± 4.1, 25.1 ± 3.6 and 15.6 ± 1.5, respectively (p=0.001). Only the AR and control groups differed from each other. Conclusions: AR is associated with relatively higher SNS activity, which is similar across different stages of the disease (asymptomatic, symptomatic and postoperative). The role of the SNS in AR must be associated with ventricular remodeling, but without correlation with clinical change

Alkaloid toxicities negatively impact livestock health and production and are of serious economic concern to animal industries. To date, few strategies have been developed to evaluate alkaloid levels in feed or to counteract alkaloid toxicities. The present research evaluated the applicability of imprinting technology to synthesize polymers that have potential to interact with ergot alkaloids and therefore reduce their bioavailability in the GIT. The studies also evaluated applicability of synthesized polymers for use in the ruminal environment using an in vitro ruminal fermentation model, and for the ability to ameliorate vasoconstriction using ex vivo myographic evaluations. In the first experiment, styrene-based molecularly imprinted polymer (MIP) was synthesized using ergotamine as the imprinting template and evaluated for specificity of adsorption to various ergot alkaloids. Cross reactivity with related alkaloids exists due to similarities in structure and functional groups. Both polymers (MIP and NIP) showed strong adsorption intensity and no difference was observed for estimated maximum adsorption capacity between MIP and NIP. Morphologically, MIP was highly porous with greater surface area than NIP. Solid phase extraction indicated stronger adsorption of MIP than NIP to ergot alkaloids suggesting the potential for MIP as a sorbent material for solid phase extraction (SPE) columns used for sample clean-up prior to HPLC or LC-MS/MS analysis of complex samples. In Experiment 2, methacrylic acid-based polymers were synthesized with ergotamine as a template. Among the 4 alkaloids evaluated for selectivity, adsorption difference between MIP and NIP interacted with alkaloid concentration, although differences were generally consistent across concentrations. Imprinting did not affect lysergol and bromocriptine adsorption, but resulted in higher adsorption to methylergonovine. However, there was no difference between MIP and NIP for adsorption of ergotamine. Hydrophobic interactions and H-bonding were the primary interactive forces between polymers and alkaloid adsorbents. Morphologically, MIP had greater surface area and porosity implying a larger surface for adsorption. In addition to its application as SPE sorbent, this MIP was a suitable candidate for application as a feed adsorbent to reduce the bioavailability of certain alkaloid in the gut. In experiment 3, methacrylic acid-based polymers were evaluated for their effect on in vitro ruminal fermentation. There were no interactions between polymer type and inclusion level, and no differences between polymer types for cumulative gas production or rate of gas production. Total gas production and rate of gas production were unaffected by inclusion level. Polymers did not affect total or individual VFA concentrations, ammonia-N or methane concentration at any inclusion level. However, a logarithmic increase in polymer dose level decreased the pH linearly with maximum depression of 0.24 units. This study indicated that, within the range of expected use levels, polymers were essentially inert and would not be expected to affect ruminal fermentation. In experiment 4, ex vivo myographic bioassays were used to determine the impact of polymers on ergotamine bioavailability. Responses measured in the ex vivo myographic studies had similar trend as the responses generated from in vitro isothermal adsorption studies. Results of that study also showed that ex vivo myographic responses could be predicted from in vitro isothermal adsorption studies with more than 80% accuracy. These studies indicate that synthetic polymers are potentially effective adsorbents to mitigate ergot toxicity with little evidence of substantial differences between MIP and NIP.

The knowledge of blood vessel biomechanics is used for understanding and developing treatments for cardiovascular disease. The objective of this project was to develop an experimental protocol, for education and research, that separates active diameter response from the passive, as a function of the intraluminal pressure in a pressure myograph. The design process was performed in three steps. First the protocol was designed for an artificial vessel and then expanded to include passive properties of blood vessels, finally further developments needed to analyze active blood vessels were suggested. The system was built as a pressure myograph containing a vessel chamber where the vessel was mounted on two cannulas, two pressure sensors for calculating the intraluminal pressure, and one microscope equipped with a camera for diameter observations. Reference data for the artificial vessel material was acquired from a uniaxial tensile test. The results was in the form of stress-stretch relations. Both the results from the artificial vessel and the passive blood vessel was in a acceptable reference range. The results indicate that the experimental protocol can be used for testing passive properties of both artificial vessels and small blood vessels. No results were obtained for active blood vessels, thus the experimental protocol can not be used for separating the active response to diameter change of blood vessels. However, further developments of the experimental protocol are discussed.
Kunskap om blodkärlens biomekanik används för att förstå och utveckla behandlingsmetoder mot hjärt- och kärlsjukdomar. Syftet med det här projektet var att utveckla ett experiment som mäter små blodkärls diameter och vätsketryck in vitro. Experimentet skulle sedan separera det aktiva muskelbidraget till diameterförändring från det passiva bidraget. Genom att göra detta kan kunskapen om biomekaniken hos blodkärl utvecklas inom såväl forskning som utbildning. Experimentet utvecklades i tre steg. Först utvecklades det för artificiella blodkärl och anpassades sedan för passiva blodkärl. Slutligen diskuteras vidareutvecklingar av experimentet gällande de aktiva egenskaperna för blodkärl. Experimentet utformades genom att ett kärl placerades i en kammare. Blodkärlet fästes i vardera ände på varsin kanyl som var kopplade till trycksensorer. För att registrera diametern placerades kammaren under ett kameramikroskop. Resultatet består av spänning-sträcknings diagram. Både resultatet för det artificiella blodkärlet och det passiva blodkärlet var inom ett godkänt referensintervall. Dessa resultat stödjer antagandet att experimentet kan användas för att studera passiva egenskaper av artificiella och verkliga blodkärl med storlek mellan 1.9-4.4 mm i ytterdiameter. Ingen mätdata från aktiva blodkärl kunde samlas in, utan utvecklingskrav på systemet för hantering av aktiva blodkärl har föreslagits.

L'activite musculaire est a l'origine d'une emission acoustique, particulierement importante lors d'un effort musculaire. Ces ondes acoustiques, de quelques dizaines de hertz, sont situees dans la majeur partie en dessous de la limite inferieure du champ auditif de l'oreille humaine. Nous avons observe et analyse les signaux residuels acoustomyographiques recueillis sur les muscles paraspinaux et biceps brachial, en l'absence de contraction. L'analyse de ces signaux a ete effectuee d'une part, par des methodes standard (transformation de fourier, etc. ), afin de les comparer aux bruits musculaires sous effort, d'autre part, nous avons analyse la complexite de ces signaux en utilisant les methodes modernes d'analyse des systemes dynamiques complexes, dans l'espace des phases. Il resulte de cette etude que les signaux de repos different de ceux sous effort essentiellement par leur amplitude et frequence moyenne plus faibles. Par des experiences appropriees, nous avons montre que le signal de repos traduisait des proprietes de filtrage mecanique du muscle et que l'origine intra-corporelle du bruit de repos n'etait pas liee au probleme d'entrelacement des fibres musculaires. Ces resultats nous ont permis d'amorcer une etude sur les proprietes de filtrage du muscle qui sont tres sensibles a la contraction et a la fatigue musculaire. Cette etude a montre que le signal acoustomyographique du muscle au repos peut etre un nouveau moyen interessant pour evaluer l'etat du muscle dans les conditions normales ou pathologique

Дисертаційна робота присвячена створенню міографічної системи протезної руки з розширеними можливостями рухів та жестів із розпізнаванням міоелектричних сигналів нейромережевим інтерфейсом та оптичним ідентифікатором контактної поверхні для дотику пальців. У роботі вдосконалено метод розпізнавання категорій фізіологічних рухів та жестів шляхом аналізу електро- та форс- міографічних сигналів мультирівневими штучними нейронними мережами, що дозволило підвищити точність класифікації жестів кисті руки. Вдосконалено метод розпізнавання контактної поверхні пальцем протезу шляхом оптичної ідентифікації із засобами концентрації оптичної енергії, що дало можливість підвищити достовірність ідентифікації структури об’єктів маніпуляції. Вдосконалено метод координації рухів протезу кисті руки на основі одночасної реєстрації і розпізнавання фізіологічних сигналів та сигналу оптичної ідентифікації.

La contraction musculaire est à l'origine d'un phénomène vibratoire de surface, ou bruit musculaire, qui a été étudié par de nombreux chercheurs durant les quinze dernières années. Les études, menées in vitro sur des muscles stimules, ont toutes montre que la fréquence moyenne du bruit musculaire correspondait à la fréquence de résonance transversale du muscle. Aucune étude n'a eu pour sujet les modes spatiaux de vibration ; on s'attend à ce qu'une structure étendue, telle qu'un muscle, ait des modes de résonance spatio-temporels sous la forme d'ondes stationnaires. J'ai d'abord étudié expérimentalement les modes de vibration du muscle en contraction volontaire isométrique-isotonique. Les résultats obtenus pour les fonctions de corrélation des déplacements à la surface du muscle ont confirmé l'hypothèse des vibrations stationnaires transversales. Pour les faibles contractions le mode fondamental est dominant ; avec l'augmentation de la contraction volontaire, la contribution d'autres modes a été observée. J'ai ensuite propose un modèle stochastique des vibrations de surface, qui généralise le modèle déterministe de barry en incorporant des sources d'excitation à larges bandes. J'ai montré que le processus associe est markovien. Les techniques standard d'étude des processus markoviens m'ont permis de représenter le bruit musculaire dans un espace des phases ou les degrés de liberté sont les moyennes locales (sur des intervalles de temps de plus en plus longs) du vecteur d'état du processus. La courbe représentative dans l'espace des phases est une spirale qui est en très bon accord avec celle obtenue a partir des résultats expérimentaux. L'amortissement de cette spirale permet de quantifier l'atténuation mécanique du muscle, ce qui suggère des applications medico-cliniques.

Background and Aims: Sex differences have been observed in several cardiovascular diseases, in terms of mortality and morbidity. Female patients experience worse clinical outcomes than their male counterparts. Although multiple mechanisms may be involved, sex differences in vascular reactivity of large and small blood vessels have not been investigated. This thesis aims to assess sex-dependent difference in vasoconstrictor responses of human vessels isolated from a variety of vascular beds from older patients (mean age 68 years) with and without existing coronary artery disease. Specific aims include evaluation of :(1a) sex differences in vascular responses of internal mammary artery (IMA) and saphenous vein (SV) segments from male and female patients undergoing CABG and (1b) mechanisms underlying sex dependent vascular responses. (2) sex differences in microvascular reactivity of vessels isolated from mediastinal and peripheral subcutaneous areas in patients with CAD. (3a) sex difference in vascular reactivity of subcutaneous microvessels from patients with no known CAD, undergoing elective non-cardiac surgery. (3b) subcutaneous microvascular reactivity of males and females patients with CAD to those without known CAD. Methods: This thesis used wire myography technique to assess functional changes in vasoconstrictor responses of isolated large conduit and small blood vessels. Concentration-response curves were formed for various vasoconstrictors including phenylephrine, serotonin, endothelin-1 and the thromboxane mimetic, U46619. Western blot analysis was employed to measure the biochemical parameters, including receptor abundance endothelin-1. Summary of major findings: Female IMA segments display hypersensitive responses to serotonergic and α₁-adrenergic receptor stimulation, compared to males. Blocking eNOS and/or cyclooxygenase revealed that prostaglandins account for in the observed α₁-adrenergic mediated sex differences. Biochemical analysis revealed increased density of 5HT2A [2A in subscript] receptors in the female IMA. Similar sex differences were observed in the pericardial microvessels of the same patient cohort, with females showing increased sensitivity to serotonergic and α₁-adrenergic receptor stimulation. Interestingly, no sex differences were observed in the peripheral subcutaneous microvessels of patients with existing CAD. In patients without known CAD, female subcutaneous microvessels were hypersensitive to serotonergic and α₁-adrenergic receptor stimulation, compared to matched males. When compared to subcutaneous microvessels of male and female patients without known CAD, male and female CAD patients exhibited increased sensitivity to a1- adrenergic agonist. Male CAD patients were also hypersensitive to serotonin and the thromboxane A₂ mimetic, U46619, relative to those without known CAD. Conclusions: For the first time, in a population cohort with a mean age of 68 years, female vascular hyper-reactivity in both large graft arteries (IMA) and microvessels has been demonstrated. Female vascular hypersensitivity is consistently seen in response to serotonergic and α₁-adrenergic receptor agonist. In part, this may be due to sex-differences in prostanoid activity. The IMA hyper-reactivity in the group of older women may contribute to their poorer outcomes following CABG and microvascular differences amongst patients without documented cardiovascular disease may pre-dispose them to hypertension.
Thesis (Ph.D.) -- University of Adelaide, School of Medicine, 2015

Experimental vibration analysis of mechanical structures is a well established field.Plenty of literature exists on macro scale structures in the fields of civil, mechanical and aerospace engineering, but the study of vibrations of micro scale structures such as MEMS, liquid droplets, and biological cells is relatively new. For such structures, the amplitudes of vibration are typically in nanometeror sub-nanometer range and the frequencies are in KHz to MHz range depending upon the dimensions of the structure. In our study, we use a scanningLaser Doppler Vibrometer (LDV) to measure the vibrations of micro-scale objects such as MEMS structures, micro droplets and cells. The vibrometercan capture frequency response up to 24 MHz withpicometer displacement resolution. First, we present the study of dynamics of a 2-D micromechanical structure—a MEMSelectrothermal actuator. The structure is realized using SOI MUMPs process from MEMSCAP. The fabricated device is tested for its dynamic performance characteristics using the LDV. In our experiments, we could capture up to 50 out-of-plane modes of vibration—an unprecedented capture—with a single excitation. Subsequent FEM based numerical simulations confirmed that the captured modes were indeed what the experiments indicated, and the measured frequencies werefound to be within 5% of theoretically predicted. Next, we study the dynamics of a 3-D micro droplet and show how the substrate adhesion modulates the natural frequency of the droplet. Adhesion properties of droplets are decided by the degree of wettability that is generally measured by the contact angle between the substrate and the droplet. In this work, we were able to capture 14 modes of vibration of a mercury droplet on different substrates and measure the correspondingfrequencies experimentally. We verify these frequencies with analytical calculations and find that all the measured frequencies are within 6% of theoretically predicted values. We also show that considering any two pairs of natural frequencies, we can calculate the surface tension and the contact angle, thus providing a new method for measuring adhesion of a droplet on an unknown surface. Lastly, we present a study of vibrations of biological cells.Our first study is that of single muscle fibers taken from drosophila.Muscle fibers with different pathological conditions were held in two structural configurations—asa fixed-fixed beam and a cantilever beam—and their vibration signatures analysed.We found that there was significant reduction in natural frequency of diseased fibers. Among the diseased fibers, we could confidently classify the myopathies into nemaline and cardiac types based on the natural frequency of single fibers. We have noticed that the elastic modulus of the muscle which decides the natural frequency is dictated by the myosin expression levels. Our last example isa study of the vibration signatures of cancer cells. Here we measure the natural frequencies of normal and certain cancerous cells, and show that we can distinguish the two based on their natural frequencies. We find that the natural frequency of cancerous cells is approximately half of that of normal cells. Within the cancerous cells, we are able to distinguished epithelial cancer cells and mesenchymal cancer cells based on their natural frequency values. For Epithelial cells,we activate the signaling pathways to induce EMT and notice the reduction in the natural frequency. This mechanical assay based on vibration response corroborates results from the biochemical assays such as Western blots and PCR, thus opening a new technique of mechano-diagnostics.

Experimental vibration analysis of mechanical structures is a well established field.Plenty of literature exists on macro scale structures in the fields of civil, mechanical and aerospace engineering, but the study of vibrations of micro scale structures such as MEMS, liquid droplets, and biological cells is relatively new. For such structures, the amplitudes of vibration are typically in nanometeror sub-nanometer range and the frequencies are in KHz to MHz range depending upon the dimensions of the structure. In our study, we use a scanningLaser Doppler Vibrometer (LDV) to measure the vibrations of micro-scale objects such as MEMS structures, micro droplets and cells. The vibrometercan capture frequency response up to 24 MHz withpicometer displacement resolution. First, we present the study of dynamics of a 2-D micromechanical structure—a MEMSelectrothermal actuator. The structure is realized using SOI MUMPs process from MEMSCAP. The fabricated device is tested for its dynamic performance characteristics using the LDV. In our experiments, we could capture up to 50 out-of-plane modes of vibration—an unprecedented capture—with a single excitation. Subsequent FEM based numerical simulations confirmed that the captured modes were indeed what the experiments indicated, and the measured frequencies werefound to be within 5% of theoretically predicted. Next, we study the dynamics of a 3-D micro droplet and show how the substrate adhesion modulates the natural frequency of the droplet. Adhesion properties of droplets are decided by the degree of wettability that is generally measured by the contact angle between the substrate and the droplet. In this work, we were able to capture 14 modes of vibration of a mercury droplet on different substrates and measure the correspondingfrequencies experimentally. We verify these frequencies with analytical calculations and find that all the measured frequencies are within 6% of theoretically predicted values. We also show that considering any two pairs of natural frequencies, we can calculate the surface tension and the contact angle, thus providing a new method for measuring adhesion of a droplet on an unknown surface. Lastly, we present a study of vibrations of biological cells.Our first study is that of single muscle fibers taken from drosophila.Muscle fibers with different pathological conditions were held in two structural configurations—asa fixed-fixed beam and a cantilever beam—and their vibration signatures analysed.We found that there was significant reduction in natural frequency of diseased fibers. Among the diseased fibers, we could confidently classify the myopathies into nemaline and cardiac types based on the natural frequency of single fibers. We have noticed that the elastic modulus of the muscle which decides the natural frequency is dictated by the myosin expression levels. Our last example isa study of the vibration signatures of cancer cells. Here we measure the natural frequencies of normal and certain cancerous cells, and show that we can distinguish the two based on their natural frequencies. We find that the natural frequency of cancerous cells is approximately half of that of normal cells. Within the cancerous cells, we are able to distinguished epithelial cancer cells and mesenchymal cancer cells based on their natural frequency values. For Epithelial cells,we activate the signaling pathways to induce EMT and notice the reduction in the natural frequency. This mechanical assay based on vibration response corroborates results from the biochemical assays such as Western blots and PCR, thus opening a new technique of mechano-diagnostics.

Vasomotor tone is largely maintained by sympathetic nerves, myogenic reactivity and key local and circulating hormones. Acting together, these factors ensure moment-to-moment adjustments of net vascular tone required to maintain hemodynamic stability. In rat mesenteric small veins (MSV) and arteries (MSA), we investigated the contribution of the endothelium, L-type voltage operated calcium channels (L-VOCCs), PKC and Rho kinase to myogenic reactivity. The interaction of myogenic reactivity with norepinephrine (NE), endothelin-1 (ET-1), and sympathetic nerve activation was also investigated under conditions of changing transmural distending pressure. We also evaluated the relative contribution of alpha adrenergic (α-A) and endothelinergic receptors to NE and ET-1 contractile responses, respectively. Additionally, the effects of changing transmural pressure on endothelial dilator function of MSV were examined. Myogenic reactivity was not altered by nitric oxide synthase (NOS) inhibition or endothelium removal in both vessels. L-VOCCs blockade completely abolished arterial tone, while only partially reducing venous tone. PKC and Rho kinase inhibitors largely abolished venous and arterial myogenic reactivity. Increasing transmural pressure did not alter NE, ET-1, and bradykinin responses, but it significantly reduced neurogenic contractions. MSV were more sensitive to NE, ET-1 and sympathetic nerve activation compared with corresponding arteries. α-A and ET-1 receptor agonist and antagonist application revealed the participation of α1-A and ETA receptors in NE and ET-1 contractile responses, respectively. α2-A and ETB receptors appeared to mediate NE and ET-1 responses in MSV, respectively. Bradykinin induced-vasodilation was mainly reduced by NOS inhibition, and BKCa and SkCa blockade. These results suggest that myogenic factors are important contributors to net venous tone in MSV; PKC and Rho kinase activation are important to myogenic reactivity in both vessels, while L-VOCCs play a limited role in the veins versus the arteries; mesenteric veins maintain an enhanced sensitivity to NE, ET-1 and sympathetic nerve activation compared to the arteries with neurogenic contractions being affected by transmural pressure elevations; α1-ARs and ETA are the predominant receptors mediating contractile responses to NE and ET-1, respectively, with functional evidence indicating the presence of α2-ARs and ETB receptors in MSV; and venous endothelial dilator function is not affected by an elevation of transmural pressure.
Natural Sciences and Engineering Research Council of Canada (NSERC). Libyan Ministry of Education and Scientific Research.