Predicting the Splash of a Drop Impacting a Thin Liquid Film.

An experimental study is carried out to investigate droplet-film interactions when a drop impinges on a thin stagnant film of the same liquid. The impacting drop causes either liquid deposition or splash, consisting of prompt generation of secondary drops or a delayed process. By varying the drop diameter and impact velocity, measurements are made to characterize the phenomena using five different liquids that are chosen to cover a wide range of liquid properties (viscosity and surface tension). The drop impact dynamics are captured with a high-speed digital camera with real-time, high-resolution image processing. The drop-splash threshold is found to scale with inertial and viscous forces, or Reynolds number (Re), as well as capillary forces, as described by the balance of gravitational and interfacial tension forces, or Bond number (Bo); fluid properties are described by their Morton number (Mo). A correlation, functionally expressed as Re = ϕ(Bo,Mo), is devised to determine the splash/no-splash (or deposition) boundary, and the predictions for the splash/no-splash outcomes agree well with the experimental outcomes as well as those readily available in the literature.

Quantifying Brain Iron in Hereditary Hemochromatosis Using R2* and Susceptibility Mapping.

BACKGROUND AND PURPOSE: Brain iron dyshomeostasis is increasingly recognized as an important contributor to neurodegeneration. Hereditary hemochromatosis is the most commonly inherited disorder of systemic iron overload. Although there is an increasing interest in excessive brain iron deposition, there is a paucity of evidence showing changes in brain iron exceeding that in healthy controls. Quantitative susceptibility mapping and R2* mapping are established MR imaging techniques that we used to noninvasively quantify brain iron in subjects with hereditary hemochromatosis. MATERIALS AND METHODS: Fifty-two patients with hereditary hemochromatosis and 47 age- and sex-matched healthy controls were imaged using a multiecho gradient-echo sequence at 3T. Quantitative susceptibility mapping and R2* data were generated, and regions within the deep gray matter were manually segmented. Mean susceptibility and R2* relaxation rates were calculated for each region, and iron content was compared between the groups. RESULTS: We noted elevated iron levels in patients with hereditary hemochromatosis compared with healthy controls using both R2* and QSM methods in the caudate nucleus, putamen, pulvinar thalamus, red nucleus, and dentate nucleus. Additionally, the substantia nigra showed increased susceptibility while the thalamus showed an increased R2* relaxation rate compared with healthy controls, respectively. CONCLUSIONS: Both quantitative susceptibility mapping and R2* showed abnormal levels of brain iron in subjects with hereditary hemochromatosis compared with controls. Quantitative susceptibility mapping and R2* can be acquired in a single MR imaging sequence and are complementary in quantifying deep gray matter iron.

The involvement of caregivers of patients with dementia during mastoid surgery under local anaesthesia.

BACKGROUND: With a growing ageing population, there is a higher prevalence of dementia in patients with conditions that can be managed surgically. Patients with dementia undergoing surgery under general anaesthesia often have poorer outcomes than those without. Therefore, local anaesthesia can be an option. METHODS: Two patients with severe dementia and advanced cholesteatoma were identified for operative management. They were deemed too high risk to proceed with general anaesthesia. This article describes our experience of performing mastoid surgery under local anaesthesia in the presence of a primary carer in the operating theatre. RESULTS: The complete extirpation of cholesteatoma was achieved in both cases. The carers reported that local anaesthesia helped to facilitate communication and aid patient co-operation. CONCLUSION: Our experience, albeit limited to two cases, illustrates an alternative individualised peri-operative strategy in the surgical management of patients with dementia and concurrent advanced cholesteatoma.

Single-use lidocaine hydrochloride 5 per cent w/v and phenylephrine hydrochloride 0.5 per cent w/v topical spray; can it now be employed as a multi-use atomiser?

OBJECTIVE: This study investigated the risk of contamination of lidocaine hydrochloride 5 per cent w/v and phenylephrine hydrochloride 0.5 per cent w/v topical solution after modification of the application technique. METHODS: This paper reports a prospective basic sciences study involving 22 study samples and 1 control sample of the lidocaine hydrochloride and phenylephrine hydrochloride topical anaesthetic spray. The samples were assessed for microbiological contamination after a single use on patients using a modified application technique. The modification involves keeping the nozzle (actuator) pressed down whilst withdrawing the spray to at least 30 cm (1 ft) from the patient, before releasing the nozzle (actuator) and subsequently reapplying the spray. RESULTS: Three of the 23 samples confirmed bacterial growth in the bottle contents, but there was no growth in any of the samples from the pump. These bacteria are considered to be contaminants. CONCLUSION: There is a potential to use the lidocaine hydrochloride 5 per cent w/v and phenylephrine hydrochloride 0.5 per cent w/v topical solution as a multi-use spray by changing the actuator between patients. This would have significant beneficial cost implications without the attendant infection control risk.

Ambroxol as a novel disease-modifying treatment for Parkinson's disease dementia: protocol for a single-centre, randomized, double-blind, placebo-controlled trial.

BACKGROUND: Currently there are no disease-modifying treatments for Parkinson's disease dementia (PDD), a condition linked to aggregation of the protein α-synuclein in subcortical and cortical brain areas. One of the leading genetic risk factors for Parkinson's disease is being a carrier in the gene for ß-Glucocerebrosidase (GCase; gene name GBA1). Studies in cell culture and animal models have shown that raising the levels of GCase can decrease levels of α-synuclein. Ambroxol is a pharmacological chaperone for GCase and is able to raise the levels of GCase and could therefore be a disease-modifying treatment for PDD. The aims of this trial are to determine if Ambroxol is safe and well-tolerated by individuals with PDD and if Ambroxol affects cognitive, biochemical, and neuroimaging measures. METHODS: This is a phase II, single-centre, double-blind, randomized placebo-controlled trial involving 75 individuals with mild to moderate PDD. Participants will be randomized into Ambroxol high-dose (1050 mg/day), low-dose (525 mg/day), or placebo treatment arms. Assessments will be undertaken at baseline, 6-months, and 12-months follow up times. Primary outcome measures will be the Alzheimer's disease Assessment Scale-cognitive subscale (ADAS-Cog) and the ADCS Clinician's Global Impression of Change (CGIC). Secondary measures will include the Parkinson's disease Cognitive Rating Scale, Clinical Dementia Rating, Trail Making Test, Stroop Test, Unified Parkinson's disease Rating Scale, Purdue Pegboard, Timed Up and Go, and gait kinematics. Markers of neurodegeneration will include MRI and CSF measures. Pharmacokinetics and pharmacodynamics of Ambroxol will be examined through plasma levels during dose titration phase and evaluation of GCase activity in lymphocytes. DISCUSSION: If found effective and safe, Ambroxol will be one of the first disease-modifying treatments for PDD. TRIAL REGISTRATION: ClinicalTrials.gov NCT02914366, 26 Sep 2016/retrospectively registered.

Medication status and dual-tasking on turning strategies in Parkinson disease.

BACKGROUND: Parkinson disease (PD) patients have turning impairments that may increase fall risk. Clinics lack specialized kinematic equipment used in gait and turn analysis and require a simple method to evaluate fall risk and advise patients in turning strategy selection. OBJECTIVES: To enhance understanding of PD turning strategies and determine if turning can be assessed using a video-recording and categorization method, we compared 180-degree and 90-degree turns as a function of medication status and dual-tasking (DT). METHODS: 21 PD participants (H&Y stage 1-3) in PD-ON and PD-OFF medication states and 16 controls completed 180-degree and 90-degree turn-tasks with and without DT. Video-recordings of tasks permitted classification of 180-degree turns into Few-Step turns (FST) vs. Multi-Step turns (MST) and 90-degree turns into Step vs. Spin-turns. FST were further sub-classified into Twisting vs. Sideways turns and MST into Backward, Festination, Forward or Wheeling turns. Percentages of subtypes were analyzed across groups by task. RESULTS: IN 180-degree tasks, there was an effect of group: FST vs. MST F(2,55) = 9.578, p < .001. PD participants in the off-medication state (PD-OFF) produced significantly more MST with a larger number of different turning subtypes vs. controls or PD on medication (PD-ON). In 90-degree tasks, controls significantly increased their proportion of Step-turns while DT (p < .001), an adaptation not observed in PD-ON or PD-OFF. CONCLUSIONS: PD turning impairments may stem from an inability to select a unified turning strategy and to adapt to the turning environment, which may be exacerbated in PD-OFF. Video-analysis may prove beneficial in predicting a clinical course for PD patients by revealing features of turning dysfunction.

Risk of contamination of lidocaine hydrochloride and phenylephrine hydrochloride topical solution: in vivo and in vitro analyses.

OBJECTIVE: To investigate the risk of contamination of lidocaine hydrochloride 5 per cent weight/volume and phenylephrine hydrochloride 0.5 per cent weight/volume topical solution, both in patients (in vivo) and in the laboratory setting (in vitro). METHODS: This paper reports a prospective study involving 10 samples of the lidocaine hydrochloride and phenylephrine hydrochloride topical anaesthetic spray. The samples were assessed for microbiological contamination after a single use on patients in a controlled laboratory environment. Additional samples were assessed for baseline contamination and later assessed for contamination in an in vitro setting. RESULTS: In the in vivo setting, 2 of the 10 samples were positive for cultures from both the pump and the bottles. However, in the in vitro setting, the pump and the contents of the bottles were contaminated after a single use when the sterile solution was sprayed from distances of 1 and 2 cm. CONCLUSION: The lidocaine hydrochloride and phenylephrine hydrochloride topical solution assembly was contaminated in both in vivo and in vitro settings after a single use.

Involuntary craniofacial lingual movements in intensive care-acquired quadriplegia.

BACKGROUND: The syndrome of involuntary craniofacial lingual movements in the setting of acute intensive care-acquired quadriplegia (critical illness neuromyopathy) following sepsis-associated encephalopathy has not been previously described. We suggest a localization and treatment for this disabling condition. METHODS: Three patients (2 female) from our center were quadriplegic from critical illness neuromyopathy when they developed involuntary craniofacial lingual movements following sepsis-associated encephalopathy. RESULTS: Extensive investigations failed to identify an etiology for the abnormal movements. Movements were of large amplitude, of moderate speed, and semi-rhythmic in the jaw, tongue, and palate, persistent and extremely bothersome to all patients. Injection with Botulinum toxin type A was very beneficial. CONCLUSIONS: Involuntary craniofacial lingual movements in the setting of flaccid quadriplegia following sepsis-associated encephalopathy are consistent with focal craniofacial brainstem myoclonus and constitutes a new syndrome. Botulinum toxin type A treatment maybe helpful in treatment.

Naturalistic evaluation of entacapone in patients with signs and symptoms of L-dopa wearing-off .

OBJECTIVE: To evaluate the effectiveness of entacapone in the management of levodopa wearing-off in Parkinson's disease (PD) in a naturalistic, real-life setting. RESEARCH DESIGN AND METHODS: This prospective, open-label, observational study included patients with idiopathic PD. Patients were eligible for inclusion if they had been taking 3-5 doses of levodopa per day for ≥2 months and had shown signs of levodopa wearing-off for ≥1 month. Subjects received entacapone (recommended dose: 1 × 200 mg tablet with each levodopa dose) for 28 days. Patients were asked to complete a wearing-off questionnaire and the eight-question Parkinson's Disease Questionnaire Quality of Life assessment (PDQ-8). Activities of daily living (both in the on and off states) were assessed using the Unified Parkinson's Disease Rating Scale (UPDRS) part II. Clinical Global Impression (CGI) of severity of PD-related symptoms was assessed using a modified CGI tool. Patient global assessment of severity of PD symptoms was also obtained. RESULTS: A total of 341 patients were enrolled by 68 physicians across Canada. At Day 28, 56.9% of the subjects indicated improvement compared to baseline on the modified CGI of change (CGI-C); 21.4% reported no change. Improvements were also observed on the UPDRS II and the PDQ-8. Benefit from entacapone appeared to be relatively uniform across subgroups (e.g., number of daily levodopa doses, use of other anti-PD medications). STUDY LIMITATIONS: The results of this study may be biased due to factors inherent in open-label, community-based trials (e.g., compliance). This is, however, reflective of everyday clinical practice. CONCLUSIONS: In this naturalistic, real-life study, the addition of entacapone to levodopa therapy provided benefits in quality of life and activities of daily living for a substantial proportion of PD patients experiencing wearing-off.

An evaluation of sensorimotor integration during locomotion toward a target in Parkinson's disease.

Recent research suggests that basal ganglia dysfunction may result in problems integrating concurrent vision and proprioception during movement. We evaluated dopaminergic system involvement in this sensorimotor process during locomotion within a large sample of Parkinson's disease (PD) patients while "On" and "Off" their dopaminergic medications (n=25), in conditions that selectively manipulated the availability of proprioception, vision or both. The present experiment focused on two main objectives: i) to examine the relative influence of visual and proprioceptive inputs on locomotion and target accuracy in patients with PD; and ii) to examine the influence of dopamine replacement therapy on sensorimotor integration while moving toward the target. All participants walked at a self-selected pace on a GAITRite carpet in two baseline conditions (light and dark), as well as four experimental darkness conditions: a) to a remembered target (i.e. proprioception only), b) to a remembered target with light on chest for body position awareness (proprioception plus), c) with vision of a lit target, also with light on chest (vision and proprioception), d) pushed in wheelchair to remembered target (no proprioception or vision). Final position was measured by 2-D radial error, and revealed a group by condition interaction, suggesting that PD patients "Off" their medications move to targets with less accuracy, but approach the accuracy of healthy participants when in the "On" state. Both PD and healthy improved their accuracy with availability of concurrent vision and proprioception (condition c). Interestingly, our results demonstrate that PD "Off" performed the task with greater difficulty than when "On" medication, but only when proprioception was the sole source of feedback. Since PD, whether medicated or unmedicated were even more affected when proprioception was removed (wheelchair), a memory-related explanation can be ruled out. Our results suggest that the basal ganglia are not specifically involved in visuoproprioceptive integration; however, assimilation of proprioceptive feedback to guide an ongoing movement may be a critical function of the basal ganglia.

How frequent are accessory sinus ostia?

The frequency of accessory sinus ostia (ASO) has been estimated at between four and 50 per cent in the findings of studies designed for other purposes or from uncontrolled observations. The literature revealed no study specifically designed to determine the prevalence of ASO. We have carried out a prospective cohort study to measure the prevalence of ASO. The prevalence of ASO was determined in rhinology clinic patients and general ENT clinic controls. Overall ASO occurred in four per cent. Seven per cent of rhinology patients and two per cent of controls had ASO. Of the rhinology patients with rhinitis or sinusitis, eight per cent exhibited ASO. The overall prevalence in this study is lower than most quoted figures in the literature. There was increased prevalence of ASO in patients with rhinitis or sinusitis compared to controls. (p<0.05) This study should be regarded as a pilot study and further investigations of the relationship between ASO and nasal disease is merited.

Polyflex stent: is it radiopaque enough?

We report a case of tracheal stenosis in which a migrated Polyflex (Rusch AG, Germany) stent entered the right main bronchus but could not be identified on the chest radiograph. The stent was identified at bronchoscopy and removed under general anaesthesia. Polyflex stents are radiopaque but may not always show up on radiograph. We recommend reliance on clinical symptoms rather than imaging to diagnose migration. If stent migration is suspected then imaging should include thoracic inlet films that incorporate a lateral view.

Tetrode technology: advances in implantable hardware, neuroimaging, and data analysis techniques.

The technical advances in hardware and software for multiunit recordings have made it easier to gather data from a large number of neurons for behavioral correlations. This paper discusses several such advances in implantable hardware, magnetic resonance imaging of electrodes in situ, and data analysis software for multiple simultaneous signals.

Methods for digital video recording, storage, and communication of movement disorders.

Video technology has now reached a level of sophistication that allows easy digitization. Digital video can be easily edited, reproduced, incorporated into databases, and posted on intra- and Internet sites for clinical use and demonstration purposes. Numerous methods exist for the production of digital video. This article synthesizes and simplifies the available methodologies in order to easily choose the technology that is the most appropriate for the movement disorder specialist's end use. Depending on available resources, issues such as cost, ease, and time to conversion are discussed. In addition, our experience with the use of one of the methodologies is briefly presented.

How many antibiotics are produced by the genus Streptomyces?

Streptomyces is the largest antibiotic-producing genus in the microbial world discovered so far. The number of antimicrobial compounds reported from the species of this genus per year increased almost exponentially for about two decades, followed by a steady rise to reach a peak in the 1970s, and with a substantial decline in the late 1980s and 1990s. The cumulative number shows a sigmoid curve that is much flatter than what a logistic equation would predict. We attempted to fit a mathematical model to this curve in order to estimate the number of undiscovered antimicrobials from this genus as well as to predict the trends in the near future. A model assuming that the screening efforts are encouraged by a previous year's success and that the probability of finding a new antibiotic is a function of the fraction of antibiotics undiscovered so far offered a good fit after optimizing parameters. The model estimated the total number of antimicrobial compounds that this genus is capable of producing to be of the order of a 100,000 - a tiny fraction of which has been unearthed so far. The decline in the slope appeared to be due to a decline in screening efforts rather than an exhaustion of compounds. Left to itself, the slope will become zero in the next one or two decades, but if the screening efforts are maintained constant, the rate of discovery of new compounds will not decline for several decades to come.

A dynamical-systems model for Parkinson's disease.

The juxtaposition of hypokinetic and hyperkinetic symptoms in Parkinson's disease (PD) presents a challenge in modeling the basal ganglia. We propose a model of the striatum that can account for the mixture of symptoms seen in PD. In the model, the problem of motor planning is cast in terms of a particle in a potential, where potentials are generated internally in striatal modules, subject to afferent control. Planned movement is governed by Hamilton's equations, where potential energy is supplied by potentials expressed in the striatum. To test the model in realistic situations, a dynamic simulation of a two-link robot arm was used. Normal movement is modeled and shown to exhibit observed experimental properties. Symptoms of PD are reproduced by modeling hypothetical consequences of PD pathology.

Building neural representations of habits.

Memories for habits and skills ("implicit or procedural memory") and memories for facts ("explicit or episodic memory") are built up in different brain systems and are vulnerable to different neurodegenerative disorders in humans. So that the striatum-based mechanisms underlying habit formation could be studied, chronic recordings from ensembles of striatal neurons were made with multiple tetrodes as rats learned a T-maze procedural task. Large and widely distributed changes in the neuronal activity patterns occurred in the sensorimotor striatum during behavioral acquisition, culminating in task-related activity emphasizing the beginning and end of the automatized procedure. The new ensemble patterns remained stable during weeks of subsequent performance of the same task. These results suggest that the encoding of action in the sensorimotor striatum undergoes dynamic reorganization as habit learning proceeds.

Epidemic diseases and host clustering: an optimum cluster size ensures maximum survival.

The risk of infection is generally believed to increase with gregariousness. Using a discrete time spatial simulation model we tested the effect of host clustering on transmission of infection within a population. Over a large parameter range, an optimum cluster size was observed to ensure maximum probability of escaping infection. Although the within cluster transmission increased with cluster size, the between cluster distance increased thereby decreasing the probability of transmission across clusters. The probability of stochastic extinction of the pathogen also increased with increasing cluster size. Thus contrary to the popular belief, clustering can be an effective strategy to minimize the risk of infections.