Παρασκευή 14 Δεκεμβρίου 2018

Flow-Mediated Drug Transport from Drug-Eluting Stents is Negligible: Numerical and In-vitro Investigations

Abstract

Prior numerical studies have shown that the blood flow patterns surrounding drug-eluting stents can enhance drug uptake in stented arteries. However, these studies employed steady-state simulations, wherein flow and drug transport parameters remained constant with respect to time. In the present study, numerical simulations and in-vitro experiments were performed to determine whether luminal blood flow patterns can truly enhance drug uptake in stented arteries. Unlike the aforementioned studies, the time-varying depletion of drug within the stent coating was modelled and the simulation results were validated qualitatively with the in-vitro experiments. The simulations showed that the non-Newtonian properties of blood, its complex near-wall behavior, and the pulsatility of its flow all affect drug uptake only modestly. Furthermore, flow-mediated drug transport was found to be negligible due to the rapid rate at which drug depletes at the stent coating surfaces that are exposed to arterial blood flow. For fluid dynamicists, these results show that steady-state simulations must be avoided when modelling drug transport in stented arteries. For device designers, these results may be used to optimize the shape of drug-eluting stent struts and coatings to improve stent efficacy.



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High Speed Pneumatic Stepper Motor for MRI Applications

Abstract

Presented in this paper is an exploration into the efficacy of a plastic, four-cylinder piston pneumatic motor designed for driving medical instruments inside magnetic resonance imaging (MRI) systems. Because of the increasing use of MRI for diagnostic and interventional purposes and the benefits that could be realized by operating with real-time MR image guidance, there exists a significant need for MRI compliant surgical devices. Some type of actuation mechanism is necessary to drive such devices. The motor can be controlled to operate in a "step" type motion by using pneumatic valves to sequentially apply air pressure to push the piston surfaces, meaning the motor is metal-free and does not use electricity. The stepwise nature of this piston stepper motor is ideal for the accurate, controlled movements required for MRI-guided interventions. The motor was geared down by a gearbox to increase torque. Performance indices determined include output torque and achievable rotational velocity with respect to factors such as air pressure and load conditions. The stepper motor achieved speeds of approximately 2000 rpm, and maximum output torques of approximately 19 N mm. The motor represents a high speed pneumatic stepper motor design capable of actuating devices in MR environments without affecting image quality.



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Strongyloides stercoralis infection in imported and local dogs in Switzerland: from clinics to molecular genetics

Abstract

Strongyloides stercoralis is a worldwide-distributed intestinal nematode affecting mainly humans and dogs. Canine strongyloidosis is generally characterised by diarrhoea, malabsorption and bronchopneumonia, and may be fatal in cases of impaired immunity. In recent years, molecular and epidemiological studies suggested that host-adapted populations of S. stercoralis with different zoonotic potential may exist. Clinical and subclinical cases of S. stercoralis infection have been increasingly diagnosed in imported (France, Belgium, Bulgaria) and locally born dogs in Switzerland, showing that this parasite is currently circulating in Europe. Three of these clinical cases will be described here. All three dogs presented severe disease, characterised by harsh diarrhoea, dehydration, vomiting, respiratory and/or neurologic signs, and needed intensive care and hospitalisation. One of these dogs was related to a Swiss breeding kennel, in which the infection was subsequently diagnosed in several other dogs. Faeces were analysed by three coproscopical methods including (i) the Baermann technique, which consistently identified the typical S. stercoralis first-stage larvae in both clinical and subclinical infections, (ii) the sedimentation-zinc chloride flotation and (iii) sodium acetate—acetic acid—formalin concentration (SAFC) methods, which allowed the additional identification of parasitic females and/or eggs in two of the clinical cases. Interestingly, S. stercoralis isolated from all three independent clinical cases exhibited an identical genetic background on the nuclear 18S rDNA (fragment involving hypervariable regions I and IV) and the mitochondrial cytochrome oxidase subunit I (cox1) loci, similar to that of zoonotic isolates from other geographical regions, and not to that of dog-adapted variants. Due to the clinical relevance and zoonotic potential of this parasite, the awareness of both diagnosticians and clinicians is strongly required.



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Cochrane corner: platinum-induced hearing loss after treatment for childhood cancer.

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Cochrane corner: platinum-induced hearing loss after treatment for childhood cancer.

Int J Audiol. 2018 Dec 13;:1-4

Authors: Brennan-Jones CG, McMahen C, Van Dalen EC

Abstract
This Cochrane Corner features the review entitled "Platinum-induced hearing loss after treatment for childhood cancer" published in 2016. In their review, van As et al. identified 13 cohort studies including 2837 participants with a hearing test after treatment with a platinum-based therapy for different types of childhood cancers. All studies had problems related to quality of the evidence. The reported frequency of hearing loss varied between 1.7% and 90.1% for studies that included a definition of hearing loss; none of the studies provided data on tinnitus. Only two studies evaluated possible risk factors. One study found a higher risk of hearing loss in people treated with the combination of cisplatin plus carboplatin compared to treatment with cisplatin only and for exposure to aminoglycosides. The other found that age at treatment (lower risk in older children) and single maximum cisplatin dose (higher risk with an increasing dose) were significant predictors for hearing loss, while gender was not. This systematic review shows that children treated with platinum analogues are at risk of developing hearing loss, but the exact prevalence and risk factors remain unclear.

PMID: 30545270 [PubMed - as supplied by publisher]



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The evaluation of the sense of hearing in patients with carotid artery stenosis within the extracranial segments.

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The evaluation of the sense of hearing in patients with carotid artery stenosis within the extracranial segments.

Acta Neurol Belg. 2018 Dec 12;:

Authors: Dorobisz K, Dorobisz T, Janczak D, Krecicki T

Abstract
Stenosis of arteries that supplies blood to the brain is one of the main causes of ischemic stroke which is the third most common cause of deaths in Europe. Atherosclerosis of carotid and vertebral arteries is responsible for 20% of the ischemic stroke cases. Stenosis may be either asymptomatic or manifested with typical neurological symptoms including motor and sensory disturbances as well as disturbances in vision and speech. However, discrete non-specific symptoms of ischemia, including headaches and vertigo, tinnitus and hearing loss, are also quite common. These symptoms may be indicative of a clinically significant stenosis of carotid and vertebral arteries, particularly within the internal carotid artery region, as well as of a risk of ischemic stroke. To date, research reports were unable to provide exact explanation of correlations between impaired hearing and the stenosis of carotid and vertebral arteries. Despite this, numerous articles list these symptoms as one of the first non-specific symptoms of this disorder. The ischemic mechanism within the inner ear region may lead to early symptoms of atherosclerosis of large vessels. However, no evidence of relationship and no explanation could be provided with this regard. The objective of the study was to assess the effect of carotid and vertebral artery stenosis on the function of the hearing and equilibrium organ on the basis of diagnostic audiological examinations including pure-tone threshold audiometry, impedance audiometry, otoacoustic emission tests and brainstem auditory evoked potential tests. The study was conducted in 63 patients (32 males, 31 females) aged 45-75 years, presenting with carotid and vertebral artery stenosis and treated at the Vascular Surgery Clinic of the University Clinical Hospital in Wrocław. Patients were stratified into two subgroups according to their age (45-60 years, 61-75 years). Patients were also divided into subgroups according to the stenotic arteries and to the symptomatic/asymptomatic status of the disorder. All patients were homogeneous in terms of the degree of artery stenosis. The control group consisted of 32 healthy persons (14 males, 18 females) aged 48-75 years. Patients qualified to the control group reported no history of middle or inner ear disorders, disturbed hearing, vertigo and balance disorders, as well as cardiovascular diseases; they also presented with unremarkable ultrasound scans of the arteries. All patients were subjected to precise audiological examinations. Prior to being qualified for the study, patients were subjected to the assessment of arteries by means of Doppler ultrasonography. The hearing organ function was assessed by means of pure-tone threshold audiometry, impedance audiometry, otoacoustic emission tests and brainstem auditory evoked potential tests. Reduction of the flow through the carotid arteries causes problems in the organ of hearing; abnormalities are reported especially in tone threshold audiometry, examinations of the stapedius muscle reflexes and brainstem auditory evoked potentials, which prove the presence of receptive cochlear-extracochlear hearing damage. Disturbances of the organ of hearing have similar severity in stenosis of the internal carotid artery and vertebral artery. Abnormalities found in audiologic examinations in patients with carotid artery stenosis are not always explicitly clinically expressed in patients with hearing loss; we should consider diagnostics for carotid artery stenosis.

PMID: 30542965 [PubMed - as supplied by publisher]



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Circulating Immune Complexes and Heat Shock Protein 70 in the Sera of Patients with Sudden Sensorineural Hearing Loss.

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Circulating Immune Complexes and Heat Shock Protein 70 in the Sera of Patients with Sudden Sensorineural Hearing Loss.

J Int Adv Otol. 2018 Dec 12;:

Authors: Osińska KP, Gołda R, Osiński S, Kaźmierczak H, Krumrych W, Marzec M, Przybylski G

Abstract
OBJECTIVES: The aim of this paper is to analyze and assess the usefulness of heat shock protein 70 (Hsp70) and circulating immune complexes (CIC) in patients with sudden sensorineural hearing loss (SSHL) in a tertiary care hospital in a research university (2014-2017).
MATERIALS AND METHODS: Patients were interviewed about the history of diseases; underwent an ear, nose, and throat (ENT) examination; a hearing test; and were analyzed for the presence of CIC and Hsp70 protein. A simple dot blot method was designed for the purpose of identification of Hsp70 bound to CIC and free Hsp70.
RESULTS: In 59.4% of patients with idiopathic SSHL, elevated levels of immune complexes were observed. Compared with healthy subjects, a significant difference was noted (p=0.00016). Positive reactions to the presence of free Hsp70 protein were noted in the sera of 48.4% of patients. In the control group, free Hsp70 was observed in 8% of patients (p=0.0000034). Hsp70 bound to CIC was detected in the sera of 62.5% of patients; and in healthy cases, in 12% (p<0.0001).
CONCLUSION: In the sera of persons with SSHL, there are elevated levels of CIC and Hsp70. After the application of the innovative method for determining the occurrence of Hsp70 bound to CIC, it was stated that its presence is greater than that of free Hsp70, commonly detected by means of the Western-blot method. The dot blot method applied in the present study increases the Hsp70 identification and by the same token increases the probability of detection of autoimmunological background of SSHL.

PMID: 30541735 [PubMed - as supplied by publisher]



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Cochrane corner: platinum-induced hearing loss after treatment for childhood cancer.

Related Articles

Cochrane corner: platinum-induced hearing loss after treatment for childhood cancer.

Int J Audiol. 2018 Dec 13;:1-4

Authors: Brennan-Jones CG, McMahen C, Van Dalen EC

Abstract
This Cochrane Corner features the review entitled "Platinum-induced hearing loss after treatment for childhood cancer" published in 2016. In their review, van As et al. identified 13 cohort studies including 2837 participants with a hearing test after treatment with a platinum-based therapy for different types of childhood cancers. All studies had problems related to quality of the evidence. The reported frequency of hearing loss varied between 1.7% and 90.1% for studies that included a definition of hearing loss; none of the studies provided data on tinnitus. Only two studies evaluated possible risk factors. One study found a higher risk of hearing loss in people treated with the combination of cisplatin plus carboplatin compared to treatment with cisplatin only and for exposure to aminoglycosides. The other found that age at treatment (lower risk in older children) and single maximum cisplatin dose (higher risk with an increasing dose) were significant predictors for hearing loss, while gender was not. This systematic review shows that children treated with platinum analogues are at risk of developing hearing loss, but the exact prevalence and risk factors remain unclear.

PMID: 30545270 [PubMed - as supplied by publisher]



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