Inflow cannula design for biventricular assist devices

Cardiovascular diseases are a leading cause of death throughout the developed world. With the demand for donor hearts far exceeding the supply, a bridge-to-transplant or permanent solution is required. This is currently achieved with ventricular assist devices (VADs), which can be used to assist the left ventricle (LVAD), right ventricle (RVAD), or both ventricles simultaneously (BiVAD). Earlier generation VADs were large, volume-displacement devices designed for temporary support until a donor heart was found. The latest generation of VADs use rotary blood pump technology which improves device lifetime and the quality of life for end stage heart failure patients. VADs are connected to the heart and greater vessels of the patient through specially designed tubes called cannulae. The inflow cannulae, which supply blood to the VAD, are usually attached to the left atrium or ventricle for LVAD support, and the right atrium or ventricle for RVAD support. Few studies have characterized the haemodynamic difference between the two cannulation sites, particularly with respect to rotary RVAD support. Inflow cannulae are usually made of metal or a semi-rigid polymer to prevent collapse with negative pressures. However suction, and subsequent collapse, of the cannulated heart chamber can be a frequent occurrence, particularly with the relatively preload insensitive rotary blood pumps. Suction events may be associated with endocardial damage, pump flow stoppages and ventricular arrhythmias. While several VAD control strategies are under development, these usually rely on potentially inaccurate sensors or somewhat unreliable inferred data to estimate preload. Fixation of the inflow cannula is usually achieved through suturing the cannula, often via a felt sewing ring, to the cannulated chamber. This technique extends the time on cardiopulmonary bypass which is associated with several postoperative complications. The overall objective of this thesis was to improve the placement and design of rotary LVAD and RVAD inflow cannulae to achieve enhanced haemodynamic performance, reduced incidence of suction events, reduced levels of postoperative bleeding and a faster implantation procedure. Specific objectives were: * in-vitro evaluation of LVAD and RVAD inflow cannula placement, * design and in-vitro evaluation of a passive mechanism to reduce the potential for heart chamber suction, * design and in-vitro evaluation of a novel suture-less cannula fixation device. In order to complete in-vitro evaluation of VAD inflow cannulae, a mock circulation loop (MCL) was developed to accurately replicate the haemodynamics in the human systemic and pulmonary circulations. Validation of the MCL’s haemodynamic performance, including the form and magnitude of pressure, flow and volume traces was completed through comparisons of patient data and the literature. The MCL was capable of reproducing almost any healthy or pathological condition, and provided a useful tool to evaluate VAD cannulation and other cardiovascular devices. The MCL was used to evaluate inflow cannula placement for rotary VAD support. Left and right atrial and ventricular cannulation sites were evaluated under conditions of mild and severe heart failure. With a view to long term LVAD support in the severe left heart failure condition, left ventricular inflow cannulation was preferred due to improved LVAD efficiency and reduced potential for thrombus formation. In the mild left heart failure condition, left atrial cannulation was preferred to provide an improved platform for myocardial recovery. Similar trends were observed with RVAD support, however to a lesser degree due to a smaller difference in right atrial and ventricular pressures. A compliant inflow cannula to prevent suction events was then developed and evaluated in the MCL. As rotary LVAD or RVAD preload was reduced, suction events occurred in all instances with a rigid inflow cannula. Addition of the compliant segment eliminated suction events in all instances. This was due to passive restriction of the compliant segment as preload dropped, thus increasing the VAD circuit resistance and decreasing the VAD flow rate. Therefore, the compliant inflow cannula acted as a passive flow control / anti-suction system in LVAD and RVAD support. A novel suture-less inflow cannula fixation device was then developed to reduce implantation time and postoperative bleeding. The fixation device was evaluated for LVAD and RVAD support in cadaveric animal and human hearts attached to a MCL. LVAD inflow cannulation was achieved in under two minutes with the suture-less fixation device. No leakage through the suture-less fixation device – myocardial interface was noted. Continued development and in-vivo evaluation of this device may result in an improved inflow cannulation technique with the potential for off-bypass insertion. Continued development of this research, in particular the compliant inflow cannula and suture-less inflow cannulation device, will result in improved postoperative outcomes, life span and quality of life for end-stage heart failure patients.

Beliefs underlying blood donors’ intentions to donate during two phases of an avian influenza outbreak

Using a Theory of Planned Behavior (TPB) framework the current study explored the beliefs of current blood donors (N=172) about donating during a low and high-risk phase of a potential avian influenza outbreak. While the majority of behavioral, normative, and control beliefs identified in preliminary research differed as a function of donors’ intentions to donate during both phases of an avian influenza outbreak, regression analyses suggested that the targeting of different specific beliefs during each phase of an outbreak would yield most benefit in bolstering donors’ intentions to remain donating. The findings provide insight in how to best motivate donors in different phases of an avian influenza outbreak.

Comparison of genomic DNA extraction techniques from whole blood samples : a time, cost and quality evaluation study

Genomic DNA obtained from patient whole blood samples is a key element for genomic research. Advantages and disadvantages, in terms of time-efficiency, cost-effectiveness and laboratory requirements, of procedures available to isolate nucleic acids need to be considered before choosing any particular method. These characteristics have not been fully evaluated for some laboratory techniques, such as the salting out method for DNA extraction, which has been excluded from comparison in different studies published to date. We compared three different protocols (a traditional salting out method, a modified salting out method and a commercially available kit method) to determine the most cost-effective and time-efficient method to extract DNA. We extracted genomic DNA from whole blood samples obtained from breast cancer patient volunteers and compared the results of the product obtained in terms of quantity (concentration of DNA extracted and DNA obtained per ml of blood used) and quality (260/280 ratio and polymerase chain reaction product amplification) of the obtained yield. On average, all three methods showed no statistically significant differences between the final result, but when we accounted for time and cost derived for each method, they showed very significant differences. The modified salting out method resulted in a seven- and twofold reduction in cost compared to the commercial kit and traditional salting out method, respectively and reduced time from 3 days to 1 hour compared to the traditional salting out method. This highlights a modified salting out method as a suitable choice to be used in laboratories and research centres, particularly when dealing with a large number of samples.

Significant differences in gene expression of GABA receptors in peripheral blood leukocytes of migraineurs

Migraine is a debilitating neurovascular disorder, with a substantial genetic component. The exact cause of a migraine attack is unknown; however cortical hyperexcitability is thought to play a role. As Gamma-aminobutyric Acid (GABA) is the major inhibitory neurotransmitter in the brain, malfunctioning of this system may be a cause of the hyperexcitability. To date, there has been limited research examining the gene expression or genetics of GABA receptors in relation to migraine. The aim of our study was to determine if GABA receptors play a role in migraine by investigating their gene expression using profile in migraine affected individuals and non-affected controls by Q-PCR. Gene expression of GABA(A) receptor subunit isoforms (GABRA3, GABRB3, GABRQ) and GABA(B) receptor 2 (GABBR2) was quantified in mRNA obtained from peripheral blood leukocytes from 28 migraine subjects and 22 healthy control subjects. Analysis of results showed that two of the tested genes, GABRA3 and GABBR2, were significantly down regulated in migraineurs (P=0.018; P=0.017), compared to controls. Results from the other tested genes did not show significant gene expression variation. The results indicate that there may be specific GABA receptor gene expression variation in migraine, particularly involving the GABRA3 and GABBR2 genes. This study also identifies GABRA3 and GABBR2 as potential biomarkers to select migraineurs that may be more responsive to GABA agonists with future investigations in this area warranted.

Shorter telomere length in peripheral blood cells associated with migraine in women

Objective To evaluate relative telomere length of female migraine patients. Background Migraine is a debilitating disorder affecting 6-28% of the population. Studies on the mechanisms of migraine have demonstrated genetic causes but the pathophysiology and subcellular effects of the disease remain poorly understood. Shortened telomere length is associated with age-related or chronic diseases, and induced stresses. Migraine attacks may impart significant stress on cellular function, thus this study investigates a correlation between shortening of telomeres and migraine. Methods Relative telomere length was measured using a previously described quantitative polymerase chain reaction method. A regression analysis was performed to assess differences in mean relative telomere length between migraine patients and healthy controls. Results The leukocyte telomeres of a cohort of 142 Caucasian female migraine subjects aged 18-77 years and 143 matched 17-77-year-old healthy control Caucasian women were examined.A significantly shorter relative telomere length was observed in the migraine group compared with the control group after adjusting for age and body mass index (P = .001). In addition, age of onset was observed to associate with the loss of relative telomere length, especially at early age of onset (<17 years old). No association was observed between relative telomere length and the severity and frequency of migraine attacks and the duration of migraine. Conclusion Telomeres are shorter in migraine patients and there is more variation in telomere length in migraine patients.

The B subunit of coagulation factor XIII is linked to renin and the Duffy blood group to α-spectrin on human chromosome 1

Family linkage studies were used to detect two linkage relationships on human chromosome 1. The B subunit of coagulation factor XIII showed significant linkage to renin with a maximum lod score of 5.071 at a distance of 10 cM. Significant linkage was also shown between the Duffy blood group and α-spectrin with linkage results giving a combined lod score of 3.194 at 5 cM.

Controlling whole blood activation and resultant clot properties on various material surfaces : a possible therapeutic approach for enhancing bone healing

Injured bone initiates the healing process by forming a blood clot at the damaged site. However, in severe damage, synthetic bone implants are used to provide structural integrity and restore the healing process. The implant unavoidably comes into direct contact with whole blood, leading to a blood clot formation on its surface. Despite this, most research in bone tissue engineering virtually ignores the important role of a blood clot in supporting healing. Surface chemistry of a biomaterial is a crucial property in mediating blood-biomaterials interactions, and hence the formation of the resultant blood clot. Surfaces presenting mixtures of functional groups carboxyl (–COOH) and methyl (–CH3) have been shown to enhance platelet response and coagulation activation, leading to the formation of fibrin fibres. In addition, it has been shown that varying the compositions of these functional groups and the length of alkyl groups further modulate the immune complement response. In this study, we hypothesised that a biomaterial surface with mixture of –COOH/–CH3(methyl), –CH2CH3 (ethyl) or –(CH2)3CH3 (butyl) groups at different ratios would modulate blood coagulation and complement activation, and eventually tailor the structural and functional properties of the blood clot formed on the surface, which subsequently impacts new bone formation. Firstly, we synthesised a series of materials composed of acrylic acid (AA), and methyl (MMA), ethyl (EMA) or butyl methacrylates (BMA) at different ratios and coated on the inner surfaces of incubation vials. Our surface analysis showed that the amount of –COOH groups on the surface coatings was lower than the ratios of AA prepared in the materials even though the surface content of –COOH groups increased with increasing in AA ratios. It was indicated that the surface hydrophobicity increased with increasing alkyl chain length: –CH 3 > –CH2CH3 > –(CH2)3CH3, and decreased with increasing –COOH groups. No significant differences in surface hydrophobicity was found on surfaces with –CH3 and –CH2CH3 groups in the presence of –COOH groups. The material coating was as smooth as uncoated glass and without any major flaws. The average roughness of material-coated surface (3.99 ± 0.54 nm) was slightly higher than that of uncoated glass surface (2.22 ± 0.29 nm). However, no significant differences in surface average roughness was found among surfaces with the same functionalities at different –COOH ratios nor among surfaces with different alkyl groups but the same –COOH ratios. These suggested that the surface functional groups and their compositions had a combined effect on modulating surface hydrophobicity but not surface roughness. The second part of our study was to investigate the effect of surface functional groups and their compositions on blood cascade activation and structural properties of the formed clots. It was found that surfaces with –COOH/–(CH2)3CH3 induced a faster coagulation activation than those with –COOH/–CH3 and –CH2CH3, regardless of the –COOH ratios. An increase in –COOH ratios on –COOH/–CH3 and –CH2CH3 surfaces decreased the rate of activation. Moreover, all material-coated surfaces markedly reduced the complement activation compared to uncoated glass surfaces, and the pattern of complement activation was entirely similar to that of surface-induced coagulation, suggesting there is an interaction between two cascades. The clots formed on material-coated surfaces had thicker fibrin with a tighter network at the exterior when compared to uncoated glass surfaces. Compared to the clot exteriors, thicker fibrins with a loose network were found in clot interiors. Coated surfaces resulted in more rigid clots with a significantly slower fibrinolysis after 1 h of lysis when compared to uncoated glass surfaces. Significant differences in fibrinolysis after 1 h of lysis among clots on material-coated surfaces correlated well with the differences in fibrin thickness and density at clot exterior. In addition, more growth factors were released during clot formation than during clot lysis. From an intact clot, there was a correlation between the amount of PDGF-AB release and fibrin density. Highest amount of PDGF-AB was released from clots formed on surfaces with 40% –COOH/60% –CH 3 (i.e. 65MMA). During clot lysis, the release of PDGF-AB also correlated with the fibrinolytic rate while the release of TGF-â1 was influenced by the fibrin thickness. This suggested that different clot structures led to different release profiles of growth factors in clot intact and degrading stages. We further validated whether the clots formed on material-coatings provide the microenvironment for improved bone healing by using a rabbit femoral defect model. In this pilot study, the implantation of clots formed on 65MMA coatings significantly increased new bone formation with enhanced chondrogenesis, osteoblasts activity and vascularisation, but decreased inflammatory macrophage number at the defects after 4 weeks when compared to commercial bone grafts ChronOSTM â-TCP granules. Empty defects were observed when blood clot formation was inhibited. In summary, our study demonstrated that surface functional groups and their relative ratios on material coatings synergistically modulate activation of blood cascades, resultant fibrin architecture, rigidity, susceptibility to fibrinolysis as well as growth factor release of the formed clots, which ultimately alter the healing microenvironment of injured bones.

A transcription factor map as revealed by a genome-wide gene expression analysis of whole-blood mRNA transcriptome in multiple sclerosis

Background Several lines of evidence suggests that transcription factors are involved in the pathogenesis of Multiple Sclerosis (MS) but a complete mapping the whole network has been elusive. One of the reasons is that there are several clinical subtypes of MS and transcription factors which may be involved in one subtype may not be in others. We investigated the possibility that this network could be mapped using microarray technologies and modern bioinformatics methods on a dataset from whole blood in 99 untreated MS patients (36 Relapse Remitting MS, 43 Primary Progressive MS, and 20 Secondary Progressive MS) and 45 age-matched healthy controls, Methodology/Principal Findings We have used two different analytical methodologies: a differential expression analysis and a differential co-expression analysis, which have converged on a significant number of regulatory motifs that seem to be statistically overrepresented in genes which are either differentially expressed (or differentially co-expressed) in cases and controls (e.g. V$KROX_Q6, p-value < 3.31E-6; V$CREBP1_Q2, p-value < 9.93E-6, V$YY1_02, p-value < 1.65E-5). Conclusions/significance: Our analysis uncovered a network of transcription factors that potentially dysregulate several genes in MS or one or more of its disease subtypes. Analysing the published literature we have found that these transcription factors are involved in the early T-lymphocyte specification and commitment as well as in oligodendrocytes dedifferentiation and development. The most significant transcription factors motifs were for the Early Growth response EGR/KROX family, ATF2, YY1 (Yin and Yang 1), E2F-1/DP-1 and E2F-4/DP-2 heterodimers, SOX5, and CREB and ATF families.

Packed red blood cells suppress myeloid dendritic cell and monocyte inflammatory responses in a whole blood model of transfusion

Purpose/Objective: The basis for poor outcomes in some patients post transfusion remains largely unknown. Despite leukodepletion, there is still evidence of immunomodulatory effects of transfusion that require further study. In addition, there is evidence that the age of blood components transfused significantly affects patient outcomes. Myeloid dendritic cell (DC) and monocyte immune function were studied utilising an in vitro whole blood model of transfusion. Materials and methods: Freshly collected (‘recipient’) whole blood was cultured with ABO compatible leukodepleted PRBC at 25% blood replacement-volume (6hrs). PRBC were assayed at [Day (D) 2, 14, 28and 42 (date-of expiry)]. In parallel, LPS or Zymosan (Zy) were added to mimic infection. Recipients were maintained for the duration of the time course (2 recipients, 4 PRBC units, n = 8).Recipient DC and monocyte intracellular cytokines and chemokines (IL-6, IL-10, IL-12,TNF-a, IL-1a, IL-8, IP-10, MIP-1a, MIP-1b, MCP-1) were measured using flow cytometry. Changes in immune response were calculated by comparison to a parallel no transfusion control (Wilcoxin matched pairs). Influence of storage age was calculated using ANOVA. Results: Significant suppression of DC and monocyte inflammatory responses were evident. DC and monocyte production of IL-1a was reduced following exposure to PRBC regardless of storage age (P < 0.05 at all time points). Storage independent PRBC mediated suppression of DC and monocyte IL-1a was also evident in cultures costimulated with Zy. In cultures co-stimulated with either LPS or Zy, significant suppression of DC and monocyte TNF-a and IL-6 was also evident. PRBC storage attenuated monocyte TNF-a production when co-cultured with LPS (P < 0.01 ANOVA). DC and monocyte production of MIP-1a was significantly reduced following exposure to PRBC (DC: P < 0.05 at D2, 28, 42; Monocyte P < 0.05 all time points). In cultures co-stimulated with LPS and zymosan, a similar suppression of MIP-1a production was also evident, and production of both DC and monocyte MIP-1b and IP-10 were also significantly reduced. Conclusions: The complexity of the transfusion context was reflected in the whole blood approach utilised. Significant suppression of these key DC and monocyte immune responses may contribute to patient outcomes, such as increased risk of infection and longer hospital stay, following blood transfusion.

Dengue fever viral exposure rates among blood donors during outbreaks in North Queensland

Introduction: Dengue poses a problem for safe transfusion of blood components with confirmed reports of transfusion-transmission in Hong Kong and Singapore. The largest outbreak in 50 years occurred in North Queensland during 2008/2009 with more than 1,000 confirmed cases in Cairns and Townsville. During this outbreak, supplementary questioning for all donors was implemented, and fresh components were not manufactured from at risk donors. We aim to determine the seroprevalence of dengue exposure in this population during this epidemic. Methods: Samples were collected from blood donors during the 2008/2009 epidemic and 3 months after the last confirmed case. These samples were tested for anti-Dengue IgM, IgG and NS1 antigen with commercially available ELISA based assay kits from PanBio. Results: Initial analyses revealed 2.7% of samples from deferred donors were IgM repeat reactive. Of these, 16% were also positive for anti-dengue IgG, while none of these were positive for the NS1 viral antigen. However, two NS1 positives were found in samples collected from deferred donors. Conclusions: This initial analysis represents recent and cumulative past exposure in a presumed asymptomatic population, and will provide documentation of the rate of asymptomatic dengue infection during the epidemic. This data can also be used to assess the risk of dengue becoming endemic in North Queensland given that the mosquito vector is established in this region.

Effect of aerobic interval training and caffeine on blood platelet function

Purpose: Hyperactive platelets contribute to the thrombotic response in humans, and exercise transiently increases platelet function. Caffeine is routinely used by athletes as an ergogenic aid, but the combined effect of exercise and caffeine on platelet function has not been investigated. Methods: Twelve healthy males were randomly assigned to one of four groups and undertook four experimental trials of a high-intensity aerobic interval training (AIT) bout or rest with ingestion of caffeine (3 mg·kg-1) or placebo. AIT was 8 × 5 min at approximately 75% peak power output (approximately 80% V?O2peak) and 1-min recovery (approximately 40% peak power output, approximately 50% V?O2peak) intervals. Blood/urine was collected before, 60, and 90 min after capsule ingestion and analyzed for platelet aggregation/activation. Results: AIT increased platelet reactivity to adenosine diphosphate (placebo 30.3%, caffeine 13.4%, P < 0.05) and collagen (placebo 10.8%, caffeine 5.1%, P < 0.05) compared with rest. Exercise placebo increased adenosine diphosphate-induced aggregation 90 min postingestion compared with baseline (40.5%, P < 0.05), but the increase when exercise was combined with caffeine was small (6.6%). During the resting caffeine protocol, collagen-induced aggregation was reduced (-4.3%, P < 0.05). AIT increased expression of platelet activation marker PAC-1 with exercise placebo (P < 0.05) but not when combined with caffeine. Conclusion: A single bout of AIT increases platelet function, but caffeine ingestion (3 mg·kg) does not exacerbate platelet function at rest or in response to AIT. Our results provide new information showing caffeine at a dose that can elicit ergogenic effects on performance has no detrimental effect on platelet function and may have the potential to attenuate increases in platelet activation and aggregation when undertaking strenuous exercise.

Effect of interval training intensity on fat oxidation, blood lactate and the rate of perceived exertion in obese men

Purpose The objectives of this study were to examine the effect of 4-week moderate- and high-intensity interval training (MIIT and HIIT) on fat oxidation and the responses of blood lactate (BLa) and rating of perceived exertion (RPE). Methods Ten overweight/obese men (age = 29 ±3.7 years, BMI = 30.7 ±3.4 kg/m2) participated in a cross-over study of 4-week MIIT and HIIT training. The MIIT training sessions consisted of 5-min cycling stages at mechanical workloads 20% above and 20% below 45%VO2peak. The HIIT sessions consisted of intervals of 30-s work at 90%VO2peak and 30-s rest. Pre- and post-training assessments included VO2max using a graded exercise test (GXT) and fat oxidation using a 45-min constant-load test at 45%VO2max. BLa and RPE were also measured during the constant-load exercise test. Results There were no significant changes in body composition with either intervention. There were significant increases in fat oxidation after MIIT and HIIT (p ≤ 0.01), with no effect of intensity. BLa during the constant-load exercise test significantly decreased after MIIT and HIIT (p ≤ 0.01), and the difference between MIIT and HIIT was not significant (p = 0.09). RPE significantly decreased after HIIT greater than MIIT (p ≤ 0.05). Conclusion Interval training can increase fat oxidation with no effect of exercise intensity, but BLa and RPE decreased after HIIT to greater extent than MIIT.

HPLC method for preliminary analysis of constituents in rat blood after oral administration of the extract of Acanthopanax senticosus

An HPLC with SPE method has been developed for analysis of constituents in rat blood after oral administration of the extract of Acanthopanax senticosus (ASE). The plasma sample was prepared by SPE method equipped with Oasis HLB cartridge (3cc, 60 mg). The analysis was performed on a Dikma Diamonsil RP(18) column (4.6 mmx150 mm, 5 microm) with the gradient elution of solvent A (ACN) and solvent B (0.1% aqueous phosphoric acid, v/v) and the detection wavelength was set at 270 nm. The calibration curve was linear over the range of 0.156-15.625 microg/mL. The LOD was 60 ng/mL. The intraday precision was less than 5.80%, and the interday precision was less than 6.0%. The recovery was (87.30 +/- 1.73)%. As a result, 19 constituents were detected in rat plasma after oral administration of the ASE, including 11 original compounds in ASE and eight metabolites, and three of the metabolites originated from syringin in ASE. Six constituents were identified by comparing with the corresponding reference compounds.

What's in it for me? Virtual conspicuous donation strategies as a source of value in blood donation

Providing an incentive is becoming common practice among blood service organisations. Driven by self-orientated motives rather than pure philanthropic intentions, research is showing that people increasingly want something in return for their support. It is contended that individuals donate conspicuously with the hope it will improve their social standing. Yet there is limited evidence for the effectiveness of conspicuous recognition strategies, and no studies, to the researcher’s knowledge, that have examined conspicuous donation strategies in an online social media context. There is a need to understand what value drives individuals to donate blood, and whether conspicuous donation strategies are a source of such value post blood donation. The purpose of this paper is to conceptualise how conspicuous donation strategies, in the form of virtual badges on social media sites, can be applied to the social behaviour of blood donation, as a value-adding tool, to encourage repeat behaviour.

Give some, get some: investigating the relationship between conspicuous donation behaviour on social media and customer value in a blood donation context

Previous research has questioned the role of altruism in charitable donation and suggests that such behaviour is also motivated by self-interest, such as public recognition or emotional satisfaction. Recognising this, not-for-profit organisations have developed strategies that allow individuals to donate conspicuously, and are at an embryonic stage of turning to social media to provide such recognition. Under investigation in this paper, is the relationship between conspicuous donation behaviour (CDB) on social media and customer value, in blood donation. Online survey results, from a sample of 186 Australian blood donors, support the proposed framework. Significant relationships between self-orientated CDB and emotional value, and other-orientated CDB and social value are demonstrated. The findings provide valuable insights into the use of conspicuous donation strategies on social media as a means to add value to the donation experience, and contribute to our understanding into the under-researched areas of CDB and customer value.