The thoracoacromial axis in salvage head and neck reconstructive surgery, a case series.

We present the surgical technique, relevant anatomy and a consecutive case series of salvage head and neck free flap reconstructions utilising the thoracoacromial axis. We demonstrated that the thoracoacromial axis is safe and reliable in salvage head and neck reconstruction with particular use in reconstruction of tracheoespophageal and pharyngolaryngectomy fistulae.

Oral isotretinoin (Roaccutane) use during incisional surgery: safe or risky?

Two cases are presented that demonstrate normal wound healing following bilateral reduction mammoplasty, in young female patients taking therapeutic doses of Isotretinoin (Roaccutane). Review of the literature does not provide evidence that Isotretinoin impairs would healing, nor that it promotes hypertrophic or keloid scarring in surgical patients.

Power Reserve at Intolerance in Ramp-Incremental Exercise Is Dependent on Incrementation Rate.

INTRODUCTION: The mechanism(s) of exercise intolerance at V˙O2max remain poorly understood. In health, standard ramp-incremental (RI) exercise is limited by fatigue-induced reductions in maximum voluntary cycling power. Whether neuromuscular fatigue also limits exercise when the RI rate is slow and RI peak power at intolerance is lower than standard RI exercise, is unknown. METHODS: In twelve healthy participants, maximal voluntary cycling power was measured during a short (~6 s) isokinetic effort at 80 rpm (Piso) at baseline and, using an instantaneous switch from cadence-independent to isokinetic cycling, immediately at the limit of RI exercise with RI rates of 50, 25, and 10 W·min-1 (RI-50, RI-25, and RI-10). Breath-by-breath pulmonary gas exchange was measured throughout. RESULTS: Baseline Piso was not different among RI rates (analysis of variance; P > 0.05). Tolerable duration increased with decreasing RI rate (RI-50, 411 ± 58 s vs RI-25, 732 ± 93 s vs RI-10, 1531 ± 288 s; P < 0.05). At intolerance, V˙O2peak was not different among RI rates (analysis of variance; P > 0.05), but RI peak power decreased with RI rate (RI-50, 361 ± 48 W vs RI-25, 323 ± 39 W vs RI-10, 275 ± 38 W; P < 0.05). Piso at intolerance was 346 ± 43 W, 353 ± 45 W, and 392 ± 69 W for RI-50, RI-25, and RI-10, respectively (P < 0.05 for RI-10 vs RI-50 and RI-25). At intolerance, in RI-50 and RI-25, Piso was not different from RI peak power (P > 0.05), thus there was no "power reserve." In RI-10, Piso was greater than RI peak power at intolerance (P < 0.001), that is, there was a "power reserve." CONCLUSIONS: In RI-50 and RI-25, the absence of a power reserve suggests the neuromuscular fatigue-induced reduction in Piso coincided with V˙O2max and limited the exercise. In RI-10, the power reserve suggests neuromuscular fatigue was insufficient to limit the exercise, and additional mechanisms contributed to intolerance at V˙O2max.

Epidural Blood Patch as a Diagnostic and Therapeutic Intervention in Spontaneous Intracranial Hypotension: A Novel Approach to Management.

OBJECTIVE: Spontaneous intracranial hypotension (SIH) remains a diagnostic and therapeutic challenge. Nonspecific clinical features and a reluctance to treat without confirmatory imaging evidence undermine management. Investigations are often insensitive and expensive, with many patients continuing to an epidural blood patch (EBP) despite negative results. Current diagnostic standards are based on a literature base skewed toward difficult-to-treat cases at specialty centers. This study aims to develop a robust diagnostic and treatment algorithm in real-life clinical practice by 1) investigating the prognostic utility of symptoms of SIH and results of associated investigation from which a scoring system is derived and 2) analyzing the role of EBP as a diagnostic and treatment tool. METHODS: This is a retrospective study of 86 patients fulfilling clinical criteria for SIH and undergoing EBP, with follow-up ranging from 1 month to 15 years, using patient medical records and an online questionnaire. RESULTS: Although specific and prognostically significant, magnetic resonance imaging of the brain, magnetic resonance imaging of the spine, and symptom-based scoring systems were too insensitive to be of practical use. Most patients with positive and sustained responses to EBP did not meet current criteria for diagnosis. The 72-hour response to the first EBP was found to be highly specific and sensitive in the diagnosis of SIH in our cohort. CONCLUSIONS: This study supports the utility of EBP as a safe, accessible, and accurate diagnostic and therapeutic tool. We propose a simple treatment algorithm that facilitates diagnosis, treatment, and prediction of long-term outcomes in this challenging condition.

Characteristics of short-term re-presentations to a regional emergency department.

OBJECTIVE: The present study aims to describe the characteristics of early ED re-presentations in a regional hospital in New South Wales, Australia. METHODS: This was a retrospective review of all patients re-presenting within 72 h of discharge from Coffs Harbour Base Hospital ED, a regional ED, for the 2016-2017 financial year. Presentations were categorised according to their diagnosis and cause for re-presentation. RESULTS: Of the 38 986 presentations to the ED within the study period, 2125 patients met re-presentation inclusion criteria (5.45%). Diagnoses most likely to re-present were injury/trauma (18.8%), gastrointestinal (14.8%) and psychiatric (12.5%). The most common cause for re-presentation was disease progression (32.7%). Patients aged over 66 were the most likely to be admitted on re-presentation (35.8%) followed by the 17-65 age group (24.2%) and the <16 age group (18.7%). CONCLUSIONS: Re-presentations were common, but did not lead to increased admissions. The regional hospital in the present study had a higher 72 h ED re-presentation rate than the comparative major city hospital. In particular, paediatric and psychiatric re-presentations were a greater burden to the regional ED. This may be secondary to a lack of alternative services, particularly for these patient groups. Improving these outpatient services may help to reduce the burden of 72 h ED re-presentations.

Flocculation on a chip: a novel screening approach to determine floc growth rates and select flocculating agents.

Flocculation is a key purification step in cell-based processes for the food and pharmaceutical industry where the removal of cells and cellular debris is aided by adding flocculating agents. However, finding the best suited flocculating agent and optimal conditions to achieve rapid and effective flocculation is a non-trivial task. In conventional analytical systems, turbulent mixing creates a dynamic equilibrium between floc growth and breakage, constraining the determination of floc formation rates. Furthermore, these systems typically rely on end-point measurements only. We have successfully developed for the first time a microfluidic system for the study of flocculation under well controlled conditions. In our microfluidic device (µFLOC), floc sizes and growth rates were monitored in real time using high-speed imaging and computational image analysis. The on-line and in situ detection allowed quantification of floc sizes and their growth kinetics. This eliminated the issues of sample handling, sample dispersion, and end-point measurements. We demonstrated the power of this approach by quantifying the growth rates of floc formation under forty different growth conditions by varying industrially relevant flocculating agents (pDADMAC, PEI, PEG), their concentration and dosage. Growth rates between 12.2 µm s-1 for a strongly cationic flocculant (pDADMAC) and 0.6 µm s-1 for a non-ionic flocculant (PEG) were observed, demonstrating the potential to rank flocculating conditions in a quantitative way. We have therefore created a screening tool to efficiently compare flocculating agents and rapidly find the best flocculating condition, which will significantly accelerate early bioprocess development.

Dissociating external power from intramuscular exercise intensity during intermittent bilateral knee-extension in humans.

KEY POINTS: Continuous high-intensity constant-power exercise is unsustainable, with maximal oxygen uptake (V̇O2 max ) and the limit of tolerance attained after only a few minutes. Performing the same power intermittently reduces the O2 cost of exercise and increases tolerance. The extent to which this dissociation is reflected in the intramuscular bioenergetics is unknown. We used pulmonary gas exchange and 31 P magnetic resonance spectroscopy to measure whole-body V̇O2, quadriceps phosphate metabolism and pH during continuous and intermittent exercise of different work:recovery durations. Shortening the work:recovery durations (16:32 s vs. 32:64 s vs. 64:128 s vs. continuous) at a work rate estimated to require 110% peak aerobic power reduced V̇O2, muscle phosphocreatine breakdown and muscle acidification, eliminated the glycolytic-associated contribution to ATP synthesis, and increased exercise tolerance. Exercise intensity (i.e. magnitude of intramuscular metabolic perturbations) can be dissociated from the external power using intermittent exercise with short work:recovery durations. ABSTRACT: Compared with work-matched high-intensity continuous exercise, intermittent exercise dissociates pulmonary oxygen uptake (V̇O2) from the accumulated work. The extent to which this reflects differences in O2 storage fluctuations and/or contributions from oxidative and substrate-level bioenergetics is unknown. Using pulmonary gas-exchange and intramuscular 31 P magnetic resonance spectroscopy, we tested the hypotheses that, at the same power: ATP synthesis rates are similar, whereas peak V̇O2 amplitude is lower in intermittent vs. continuous exercise. Thus, we expected that: intermittent exercise relies less upon anaerobic glycolysis for ATP provision than continuous exercise; shorter intervals would require relatively greater fluctuations in intramuscular bioenergetics than in V̇O2 compared to longer intervals. Six men performed bilateral knee-extensor exercise (estimated to require 110% peak aerobic power) continuously and with three different intermittent work:recovery durations (16:32, 32:64 and 64:128 s). Target work duration (576 s) was achieved in all intermittent protocols; greater than continuous (252 ± 174 s; P < 0.05). Mean ATP turnover rate was not different between protocols (∼43 mm min-1 on average). However, the intramuscular phosphocreatine (PCr) component of ATP generation was greatest (∼30 mm min-1 ), and oxidative (∼10 mm min-1 ) and anaerobic glycolytic (∼1 mm min-1 ) components were lowest for 16:32 and 32:64 s intermittent protocols, compared to 64:128 s (18 ± 6, 21 ± 10 and 10 ± 4 mm min-1 , respectively) and continuous protocols (8 ± 6, 20 ± 9 and 16 ± 14 mm min-1 , respectively). As intermittent work duration increased towards continuous exercise, ATP production relied proportionally more upon anaerobic glycolysis and oxidative phosphorylation, and less upon PCr breakdown. However, performing the same high-intensity power intermittently vs. continuously reduced the amplitude of fluctuations in V̇O2 and intramuscular metabolism, dissociating exercise intensity from the power output and work done.

A study of the optical and polarisation properties of InGaN/GaN multiple quantum wells grown on a-plane and m-plane GaN substrates.

We report on a comparative study of the low temperature emission and polarisation properties of InGaN/GaN quantum wells grown on nonpolar ([Formula: see text]) a-plane and ([Formula: see text]) m-plane free-standing bulk GaN substrates where the In content varied from 0.14 to 0.28 in the m-plane series and 0.08 to 0.21 for the a-plane series. The low temperature photoluminescence spectra from both sets of samples are broad with full width at half maximum height increasing from 81 to 330 meV as the In fraction increases. Photoluminescence excitation spectroscopy indicates that the recombination mainly involves strongly localised carriers. At 10 K the degree of linear polarisation of the a-plane samples is much smaller than of the m-plane counterparts and also varies across the spectrum. From polarisation-resolved photoluminescence excitation spectroscopy we measured the energy splitting between the lowest valence sub-bands to lie in the range of 23-54 meV for the a- and m-plane samples in which we could observe distinct exciton features. Thus the thermal occupation of a higher valence sub-band cannot be responsible for the reduction of the degree of linear polarisation at 10 K. Time-resolved spectroscopy indicates that in a-plane samples there is an extra emission component which is at least partly responsible for the reduction in the degree of linear polarisation.

Reduced expression of the presynaptic co-chaperone cysteine string protein alpha (CSPα) does not exacerbate experimentally-induced ME7 prion disease.

Infection of mice with the ME7 prion agent results in well-characterised neuropathological changes, which includes vacuolation, neurodegeneration and synaptic degeneration. Presynaptic dysfunction and degeneration is apparent through the progressive reduction in synaptic vesicle proteins and eventual loss of synapses. Cysteine string protein alpha (CSPα), which regulates refolding pathways at the synapse, exhibits an early decline during chronic neurodegeneration implicating it as a mediator of disease mechanisms. CSPα null mice develop a progressive neuronal dysfunction through disruption of the integrity of presynaptic function. In this study, we investigated whether reduced expression of CSPα would exacerbate ME7 prion disease. Wild type (+/+) and heterozygous (+/-) mice, which express about a ∼50% reduction in CSPα, were used as a distinct genetic background on which to impose prion disease. +/+ and +/ - mice were inoculated with brain homogenate from either a normal mouse brain (NBH) or from the brain of a mouse which displayed clinical signs of prion disease (ME7). Behavioural tests, western blotting and immunohistochemistry, which resolve key elements of synaptic dysfunction, were used to assess the effect of reduced CSPα on disease. Behavioural tests revealed no change in the progression of disease in ME7-CSPα +/- animals compared to ME7-CSPα +/+ animals. In addition, the accumulation of misfolded PrP(Sc), the diseased associated gliosis or synaptic loss were not different. Thus, the misfolding events that generate synaptic dysfunction and lead to synaptic loss are unlikely to be mediated by a disease associated decrease in the refolding pathways associated with CSPα.

Electromagnetic stirring in a microbioreactor with non-conventional chamber morphology and implementation of multiplexed mixing.

BACKGROUND: Microbioreactors have emerged as novel tools for early bioprocess development. Mixing lies at the heart of bioreactor operation (at all scales). The successful implementation of micro-stirring methods is thus central to the further advancement of microbioreactor technology. The aim of this study was to develop a micro-stirring method that aids robust microbioreactor operation and facilitates cost-effective parallelization. RESULTS: A microbioreactor was developed with a novel micro-stirring method involving the movement of a magnetic bead by sequenced activation of a ring of electromagnets. The micro-stirring method offers flexibility in chamber designs, and mixing is demonstrated in cylindrical, diamond and triangular shaped reactor chambers. Mixing was analyzed for different electromagnet on/off sequences; mixing times of 4.5 s, 2.9 s, and 2.5 s were achieved for cylindrical, diamond and triangular shaped chambers, respectively. Ease of micro-bubble free priming, a typical challenge of cylindrical shaped microbioreactor chambers, was obtained with a diamond-shaped chamber. Consistent mixing behavior was observed between the constituent reactors in a duplex system. CONCLUSION: A novel stirring method using electromagnetic actuation offering rapid mixing and easy integration with microbioreactors was characterized. The design flexibility gained enables fabrication of chambers suitable for microfluidic operation, and a duplex demonstrator highlights potential for cost-effective parallelization. Combined with a previously published cassette-like fabrication of microbioreactors, these advances will facilitate the development of robust and parallelized microbioreactors. © 2015 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.