Flow-Structure Interaction in the Upper Airway: Motions of a Cantilevered Flexible Plate in Channel Flow with Flexible Walls

The present work seeks to elucidate the flow-structure dynamics of the upper airway so that improved clinical strategies for the alleviation of snoring and sleep apnoea can be developed and applied on an evidence basis. Analogue computational modelling, appropriately related to the anatomically correct system, is used. Hitherto, such modelling has been confined to flow in a rigidchannel to study flutter of the soft palate. Clinical evidence suggests that apneic events can involve combined motions and interactions of the soft palate and flexible walls of the pharynx. We model a flexible cantilevered plate (the soft-palate) mounted in a channel of square cross-section (the pharynx), the downstream side walls of which are flexible to capture deformation in airway collapse. Upstream of the flexible plate is a rigid plate (the hard palate) that spans the channel to permit airflow to be drawn from two inlets (oral and nasal). The commercial FSI software ADINA is used to construct the model and undertake the three-dimensional investigation. Results show that motions of the soft-palate have little effect on the deformation of the side walls. However, the amplitude and frequency of soft-palate vibrations are found to be strongly dependent upon side-wall stiffness and, hence, dynamics

A comparison of intermediate and long-acting insulins in people with type 2 diabetes starting insulin: an observational database study

AimsInsulin is normally added to oral glucose-lowering drugs in people with type 2 diabetes when glycaemic control becomes suboptimal. We evaluated outcomes in people starting insulin therapy with neutral protamine Hagedorn (NPH), detemir, glargine or premixed insulins.MethodsInsulin-naïve people with type 2 diabetes (n = 8009), ≥ 35 years old, HbA(1c) ≥ 6.5% and begun on NPH (n = 1463), detemir (n = 357), glargine (n = 2197) or premix (n = 3992), were identified from a UK database of primary care records (The Health Improvement Network). Unadjusted and multivariate-adjusted analyses were conducted, with persistence of insulin therapy assessed by survival analysis.ResultsIn the study population (n = 4337), baseline HbA(1c) was 9.5 ± 1.6%, falling to 8.4 ± 1.5% over 12 months (change -1.1 ± 1.8%, p Discussion and conclusionIn routine clinical practice, people with type 2 diabetes commenced on NPH experienced a modest disadvantage in glycaemic control after 12 months compared with other insulins. When comparing the insulins, glargine achieved best HbA(1c) reduction, while premix showed greatest weight gain and the highest dose requirement, but had the best persistence of therapy.J. Gordon, R. D. Pockett, A. P. Tetlow, P. McEwan, P. D. Hom

Antimicrobial activity of graphene oxide-metal hybrids.

With resistant bacteria on the increase, there is a need for new combinations of antimicrobials/biocidal agents to help control the transmission of such microorganisms. Particulate forms of graphite, graphene oxide (GO) and metal-hybrid compounds (silver-graphene oxide (AgGO) and zinc oxide graphene oxide (ZnOGO)) were fabricated and characterised. X-Ray diffraction and Diffuse Reflectance Infrared Fourier Transform Spectroscopy demonstrated the composition of the compounds. Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy determined the compounds were heterogeneous and irregular in shape and size and that the level of silver in the AgGO sample was 57.9 wt% and the ZnOGO contained 72.65 wt % zinc. The compounds were tested for their antimicrobial activity against four prominent bacteria; Escherichia coli, Staphylococcus aureus, Enterococcus faecium and Klebsiella pneumoniae. AgGO was the most effective antimicrobial (Minimum inhibitory concentration E. coli/Enterococcus faecium 0.125 mg mL−1; S. aureus/K. pneumoniae 0.25 mg mL−1). The addition of Ag enhanced the activity of GO against the bacteria tested, including the generally recalcitrant K. pneumoniae and Enterococcus faecium. These findings demonstrated that GO-metal hybrids have the potential to be utilised as novel antimicrobials or biocides in liquid formulations, biomaterials or coatings for use in the treatment of wounds where medically relevant bacteria are becoming increasingly resistant

Cardiopulmonary exercise testing and cardiopulmonary morbidity in patients undergoing major head and neck surgery

Cardiopulmonary exercise testing (CPET) is used as a risk stratification tool for patients undergoing major surgery. In this study, we investigated the role of CPET in predicting day five cardiopulmonary morbidity in patients undergoing head and neck surgery. This observational cohort study included 230 adults. We recorded preoperative CPET variables and day five postoperative cardiopulmonary morbidity. Full data from 187 patients were analysed; 43 patients either had incomplete data sets or declined surgery/CPET. One hundred and nineteen patients (63.6%) developed cardiopulmonary morbidity at day five. Increased preoperative heart rate and duration of surgery were independently associated with day five cardiopulmonary morbidity. Those with such morbidity also had lower peak V̇O2 11.4 (IQR 8.4-18.0) vs 16.0 (IQR 14.0-19.7) ml.kg-1.min-1, P<0.0001 and V̇O2 at AT 10.6 (IQR 9.1-13.1) vs 11.5 (IQR 10.5-13.0) ml.kg-1.min-1, p=0.03. Logistic regression model containing peak V̇O2 and duration of surgery demonstrated that increased peak V̇O2 was associated with a reduction in the likelihood of cardiopulmonary complications OR 0.92 (95%CI 0.87 to 0.96), p=0.001. The area under the receiver operating characteristic curve for this model was 0.75(95%CI 0.68 to 0.82), p<0.0001, 64% sensitivity, 81% specificity. CPET can help to predict day five cardiopulmonary morbidity in the patients undergoing head and neck surgery. A model containing peak V̇O2 allowed identification of those with such complications

Vascular phenotype in angiogenic and non-angiogenic lung non-small cell carcinomas

We have previously described a group of non-small cell lung carcinomas without morphological evidence of neo-angiogenesis. In these tumours neoplastic cells fill up the alveoli and the only vessels present appear to belong to the trapped alveolar septa. In the present study we have characterised the phenotype of the vessels present in these non-angiogenic tumours, in normal lung and in angiogenic non-small cell lung carcinomas. The vessels, identified by the expression of CD31, were scored as mature when expressing the epitope LH39 in the basal membrane and as newly formed when expressing αVβ3 on the endothelial cells and/or lacking LH39 expression. In the nine putative non-angiogenic cases examined, the vascular phenotype of all the vessels was the same as that of alveolar vessels in normal lung: LH39 positive and αVβ3 variable or negative. Instead in 104 angiogenic tumours examined, only a minority of vessels (mean 13.1%; range 0–60%) expressed LH39, while αVβ3 (in 45 cases) was strongly expressed on many vessels (mean 55.5%; range 5–90%). We conclude that in putative non-angiogenic tumours the vascular phenotype is that of normal vessels and there is no neo-angiogenesis. This type of cancer may be resistant to some anti-angiogenic therapy and different strategies need to be developed