Molecular Characterisation of Bacteriophage K Towards Applications for the Biocontrol of Pathogenic Staphylococci

End of project reportThe aim of this work was to characterise staphylococcal bacteriophage (a bacterial virus) and to assess their potential as therapeutic agents against pathogenic strains of Staphylococcus aureus, particularly mastitis-causing strains. The project included the use of two newly isolated phage CS1 and DW2, and an existing polyvalent phage. The new phage were isolated from the farmyard and characterised by electron microscopy and restriction analysis. Both phage were shown to belong to the Siphoviridae family and were lytic for representatives of all three clonal groups of Irish mastitis-associated staphylococci. A cocktail of three phage (CS1, DW2 and K) at 108 (plaque forming units) PFU/ml was infused into cows teats in animal trials. The lack of an increase in somatic cell counts in milks indicated strongly that the phage did not irritate the animal. In addition, the most potent phage used in this study, phage K, was further studied by genome sequencing, which revealed a linear DNA genome of 127,395 base pairs, which encodes 118 putative ORFs (open reading frames)

An Anthropometric Study of 38 Individuals With Prader-Labhart- Willi Syndrome

Weight, height, sitting height, and 24 other anthropometric variables (5 body circumferences, skinfolds at 7 sites, 4 head dimensions, and 8 hand and foot measurements) were obtained on 38 Prader-Labhart-Willi syndrome (PLWS) individuals (21 with apparent chromosome 15 deletions and 17 nondeletion cases) with an age range of 2 weeks to 38½ years. More than half of these individuals were measured on more than one occasion. The measurements confirmed the presence of short stature, small hands and feet, obesity, and narrow bi-frontal diameter in PLWS. No differences were found for the anthropometric measurements between the 2 chromosome subgroups. Inverse correlations were produced with linear measurements (eg, height, hand and foot lengths) and age, which indicated a deceleration of linear growth relative to normal individuals with increasing age

Optimisation of the transmit beam parameters for generation of subharmonic signals in native and altered populations of a commercial microbubble contrast agent SonoVue®

The aim of this work was to establish the optimum acoustic characterisation approach and insonation transmit beam parameters for subharmonic signal generation with ‘native’ and ‘altered’ populations of a commonly-used microbubble contrast agent. Dynamic contrast-enhanced (DCE) ultrasound is a non-invasive method of imaging the microvasculature, typically implemented using harmonic imaging. Subharmonic imaging, in which echoes at half the fundamental frequency are detected, detects signals which are generated by the ultrasound contrast agents (UCAs) but not by tissue. However, optimal transmission parameters and furthermore, the optimum acoustic characterisation method have not been established. The subharmonic response of ‘native’ and ‘altered’ UCA, altered through decantation, was investigated at transmit centre frequencies 1.8–5 MHz and pulse lengths 1–8 cycles. The ‘altered’ UCA had reduced polydispersity (1–4 µm: 82% bubble volume), compared to ‘native’ (4–10 µm: 57% bubble volume). A custom-built narrow-band acoustic characterisation system was found to be more appropriate for acoustic characterisation compared to the commonly used broadband pulse-echo approach. Both UCA generated the highest subharmonic signal at pulse length of 3-cycles. The maximum ‘native’ subharmonic signal was generated at a transmit centre frequency of 1.9 MHz, corresponding to a subharmonic at 0.95 MHz. This optimal frequency increased in the ‘altered’ population to 2.3–2.5 MHz, bringing the subharmonic above 1 MHz and hence into a range amenable to clinical abdominal imaging transducers. The use of subharmonic signal detection coupled with a modified UCA size distribution has potential to significantly improve the quantification sensitivity and accuracy of DCE ultrasound imaging. Keywords: Ultrasound contrast agent; Acoustic characterisation; Subharmonic imagin

Development and Evaluation of a Multifrequency Ultrafast Doppler Spectral Analysis (MFUDSA) Algorithm for Wall Shear Stress Measurement: A Simulation and In Vitro Study

Cardiovascular pathology is the leading cause of death and disability in the Western world, and current diagnostic testing usually evaluates the anatomy of the vessel to determine if the vessel contains blockages and plaques. However, there is a growing school of thought that other measures, such as wall shear stress, provide more useful information for earlier diagnosis and prediction of atherosclerotic related disease compared to pulsed-wave Doppler ultrasound, magnetic resonance angiography, or computed tomography angiography. A novel algorithm for quantifying wall shear stress (WSS) in atherosclerotic plaque using diagnostic ultrasound imaging, called Multifrequency ultrafast Doppler spectral analysis (MFUDSA), is presented. The development of this algorithm is presented, in addition to its optimisation using simulation studies and in-vitro experiments with flow phantoms approximating the early stages of cardiovascular disease. The presented algorithm is compared with commonly used WSS assessment methods, such as standard PW Doppler, Ultrafast Doppler, and Parabolic Doppler, as well as plane-wave Doppler. Compared to an equivalent processing architecture with one-dimensional Fourier analysis, the MFUDSA algorithm provided an increase in signal-to-noise ratio (SNR) by a factor of 4–8 and an increase in velocity resolution by a factor of 1.10–1.35. The results indicated that MFUDSA outperformed the others, with significant differences detected between the typical WSS values of moderate disease progression (p = 0.003) and severe disease progression (p = 0.001). The algorithm demonstrated an improved performance for the assessment of WSS and has potential to provide an earlier diagnosis of cardiovascular disease than current techniques allow

Cytoplasmic BK\u3csub\u3eCa\u3c/sub\u3e channel intron-containing mRNAs contribute to the intrinsic excitability of hippocampal neurons

High single-channel conductance K+ channels, which respond jointly to membrane depolarization and micromolar concentrations of intracellular Ca2+ ions, arise from extensive cell-specific alternative splicing of pore-forming α-subunit mRNAs. Here, we report the discovery of an endogenous BKCa channel α-subunit intron-containing mRNA in the cytoplasm of hippocampal neurons. This partially processed mRNA, which comprises ≈10% of the total BKCa channel α-subunit mRNAs, is distributed in a gradient throughout the somatodendritic space. We selectively reduced endogenous cytoplasmic levels of this intron-containing transcript by RNA interference without altering levels of the mature splice forms of the BKCa channel mRNAs. In doing so, we could demonstrate that changes in a unique BKCa channel α-subunit introncontaining splice variant mRNA can greatly impact the distribution of the BKCa channel protein to dendritic spines and intrinsic firing properties of hippocampal neurons. These data suggest a new regulatory mechanism for modulating the membrane properties and ion channel gradients of hippocampal neurons

Heritability of subcortical volumetric traits in mesial temporal lobe epilepsy.

OBJECTIVES: We aimed to 1) determine if subcortical volume deficits are common to mesial temporal lobe epilepsy (MTLE) patients and their unaffected siblings 2) assess the suitability of subcortical volumetric traits as endophenotypes for MTLE. METHODS: MRI-based volume measurements of the hippocampus, amygdala, thalamus, caudate, putamen and pallidium were generated using an automated brain reconstruction method (FreeSurfer) for 101 unrelated 'sporadic' MTLE patients [70 with hippocampal sclerosis (MTLE+HS), 31 with MRI-negative TLE], 83 unaffected full siblings of patients and 86 healthy control subjects. Changes in the volume of subcortical structures in patients and their unaffected siblings were determined by comparison with healthy controls. Narrow sense heritability was estimated ipsilateral and contralateral to the side of seizure activity. RESULTS: MTLE+HS patients displayed significant volume deficits across the hippocampus, amygdala and thalamus ipsilaterally. In addition, volume loss was detected in the putamen bilaterally. These volume deficits were not present in the unaffected siblings of MTLE+HS patients. Ipsilaterally, the heritability estimates were dramatically reduced for the volume of the hippocampus, thalamus and putamen but remained in the expected range for the amygdala. MRI-negative TLE patients and their unaffected siblings showed no significant volume changes across the same structures and heritability estimates were comparable with calculations from a healthy population. CONCLUSIONS: The findings indicate that volume deficits for many subcortical structures in 'sporadic' MTLE+HS are not heritable and likely related to acquired factors. Therefore, they do not represent suitable endophenotypes for MTLE+HS. The findings also support the view that, at a neuroanatomical level, MTLE+HS and MRI-negative TLE represent two distinct forms of MTLE

Age-related normative changes in cerebral perfusion: data from The Irish Longitudinal Study on Ageing (TILDA)

Objective To establish normative reference values for total grey matter cerebral blood flow (CBFGM) measured using pseudo-continuous arterial spin labelling (pCASL) MRI in a large cohort of community-dwelling adults aged 54 years and older. Background Quantitative assessment of CBFGM may provide an imaging biomarker for the early detection of those at risk of neurodegenerative diseases, such as Alzheimer's and dementia. However, the use of this method to differentiate normal age-related decline in CBFGM from pathological reduction has been hampered by the lack of reference values for cerebral perfusion. Methods The study cohort comprised a subset of wave 3 (2014-2015) participants from The Irish Longitudinal Study on Ageing (TILDA), a large-scale prospective cohort study of individuals aged 50 and over. Of 4,309 participants attending for health centre assessment, 578 individuals returned for 3T multi-parametric MRI brain examinations. In total, CBFGM data acquired from 468 subjects using pCASL-MRI were included in this analysis. Normative values were estimated using Generalised Additive Models for Location Shape and Scale (GAMLSS) and are presented as percentiles, means and standard deviations. Results The mean age of the cohort was 68.2 ± 6.9 years and 51.7% were female. Mean CBFGM for the cohort was 36.5 ± 8.2 ml/100g/min. CBFGM decreased by 0.2 ml/100g/min for each year increase in age (95% CI =-0.3,-0.1; p ≤ 0.001) and was 3.1 ml/100g/min higher in females (95% CI = 1.6, 4.5; p ≤ 0.001)

Dynamic Blood-Brain Barrier Regulation in Mild Traumatic Brain Injury

Whereas the diagnosis of moderate and severe traumatic brain injury (TBI) is readily visible on current medical imaging paradigms (magnetic resonance imaging [MRI] and computed tomography [CT] scanning), a far greater challenge is associated with the diagnosis and subsequent management of mild TBI (mTBI), especially concussion which, by definition, is characterized by a normal CT. To investigate whether the integrity of the blood-brain barrier (BBB) is altered in a high-risk population for concussions, we studied professional mixed martial arts (MMA) fighters and adolescent rugby players. Additionally, we performed the linear regression between the BBB disruption defined by increased gadolinium contrast extravasation on dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) on MRI and multiple biomechanical parameters indicating the severity of impacts recorded using instrumented mouthguards in professional MMA fighters. MMA fighters were examined pre-fight for a baseline and again within 120 h post-competitive fight, whereas rugby players were examined pre-season and again post-season or post-match in a subset of cases. DCE-MRI, serological analysis of BBB biomarkers, and an analysis of instrumented mouthguard data, was performed. Here, we provide pilot data that demonstrate disruption of the BBB in both professional MMA fighters and rugby players, dependent on the level of exposure. Our data suggest that biomechanical forces in professional MMA and adolescent rugby can lead to BBB disruption. These changes on imaging may serve as a biomarker of exposure of the brain to repetitive subconcussive forces and mTBI

Impact of source data on the interpretation of contrast-enhanced magnetic resonance angiography of the lower limbs

Background The primary purpose of this study is to examine whether use of source data is effective in increasing the number of arterial segments that can be interpreted from maximum intensity projections of lower limb MR angiograms. Correlation between sites of arterial disease and venous contamination was also measured. Interpretation of source data is performed routinely by radiologists, but the value of this has not been well studied with randomized studies. Results The proportion of segments visible above the knee was 87% using maximal intensity projection alone (MIP) and 88% when the MIP was combined with source data. The proportions were 67% for MIP and 72% for MIP plus source data below the knee. There was substantial agreement between presence of arterial disease and venous contamination in the calf and thigh. Conclusion The use of source data increases the number of assessable segments, but not individuals, by a statistically significant but small amount (1.2%, p <0.05). This study supports the association between arterial disease and venous contamination

Measuring dementia carers' unmet need for services - an exploratory mixed method study

<p>Abstract</p> <p>Background</p> <p>To ensure carers of people with dementia receive support, community services increasingly use measures of caregiver (carer) burden to assess for unmet need. This study used Bradshaw's taxonomy of need to explore the link between measures of carer burden (normative need), service use (expressed need), and carer's stated need (felt need).</p> <p>Methods</p> <p>This mixed method exploratory study compared measures of carer burden with community services received and unmet needs, for 20 community-dwelling carer/care-recipient pairs.</p> <p>Results</p> <p>A simple one-item measure of carers' felt need for more services was significantly related to carer stress as measured on the GHQ-30. Qualitative data showed that there are many potential stressors for carers, other than those related to the care-giving role. We found a statistically significant rank correlation (p = 0.01) between carer's use of in-home respite and the care-recipient's cognitive and functional status which is likely to have been related to increased requirement for carer vigilance, effort and the isolation of spouse carers. Otherwise, there were no statistically significant relationships between carer burden or stress and level of service provision.</p> <p>Conclusion</p> <p>When carers are stressed or depressed, they can recognise that they would like more help from services, even if measures of carer burden and care recipient status do not clearly indicate unmet service needs. A question designed to elicit carer' <it>felt </it>need may be a better indicator of service need, and a red flag for recognising growing stress in carers of people with dementia. Assessment of service needs should recognise the fallibility of carer burden measures, given that carer stress may not only come from caring for someone with dementia, but can be significantly compounded by other life situations.</p