Neuromuscular junction denervation and terminal Schwann cell loss in the hTDP-43 overexpression mouse model of amyotrophic lateral sclerosis

AIMS

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease with complex aetiology. Despite evidence of neuromuscular junction (NMJ) denervation and 'dying-back' pathology in models of SOD1-dependent ALS, evidence in other genetic forms of ALS is limited by a lack of suitable animal models. TDP-43, a key mediator protein in ALS, is overexpressed in neurons in Thy1-hTDP-43WT mice. We therefore aimed to comprehensively analyse NMJ pathology in this model of ALS.

METHODS

Expression of TDP-43 was assessed via western blotting. Immunohistochemistry techniques, alongside NMJ-morph quantification, were used to analyse motor neuron number, NMJ denervation status and terminal Schwann cell morphology.

RESULTS

We present a time course of progressive, region-specific motor neuron pathology in Thy1-hTDP-43WT mice. Thy1-driven hTDP-43 expression increased steadily, correlating with developing hindlimb motor weakness and associated motor neuron loss in the spinal cord with a median survival of 21 days. Pronounced NMJ denervation was observed in hindlimb muscles, mild denervation in cranial muscles but no evidence of denervation in either forelimb or trunk muscles. NMJ pathology was restricted to motor nerve terminals, with denervation following the same time course as motor neuron loss. Terminal Schwann cells were lost from NMJs in hindlimb muscles, directly correlating with denervation status.

CONCLUSIONS

Thy1-hTDP-43WT mice represent a severe model of ALS, with NMJ pathology/denervation of distal muscles and motor neuron loss, as observed in ALS patients. This model therefore provides an ideal platform to investigate mechanisms of dying-back pathology, as well as NMJ-targeting disease-modifying therapies in ALS.

Effect of gentamicin on CD3+ T-lymphocyte proliferation for treatment of equine recurrent uveitis: An in vitro study

OBJECTIVE

The objective of the study was to determine the effect of gentamicin on CD3+ T-lymphocyte proliferation and cell viability using an in vitro cell culture model as a means of investigating the mechanism of action of low-dose intravitreal gentamicin injection.

ANIMALS STUDIED

Three adult horses with no evidence of ophthalmic or systemic disease.

PROCEDURE

Peripheral blood lymphocytes were treated with gentamicin at concentrations 37.5 μg/mL, 112.5 μg/mL, 187 μg/mL, 375 μg/mL, or 750 μg/mL then stimulated to proliferate with concanavalin A (ConA). 4',6-diamidino-2-phenylindole (DAPI) and carboxyfluoroscein succinimidyl ester (CSFE) were used as markers of cell viability and cell proliferation, respectively. Following 5-day culture, live cell counts and CSFE fluorescent intensity data were collected via automated cell count and flow cytometry. The experimental design was duplicated using preservative-free gentamicin and a proprietary brand formulation. Statistical analysis was performed using two-way ANOVA with Tukey's multiple comparison test.

RESULTS

No statistically significant comparisons in CD3+ T-lymphocyte live cell counts and geometric mean fluorescent intensity of CSFE were identified between gentamicin concentrations or formulations.

CONCLUSIONS

Gentamicin had no effect on equine peripheral blood CD3+ T-lymphocyte cell viability and proliferation in concentrations ranging from "safe" to "retinotoxic" in relation to intravitreal injection volumes. Low-dose intravitreal gentamicin may not suppress the Th1- and Th17-mediated immune response.

Tri-Lineage Differentiation Potential of Osteosarcoma Cell Lines and Human Bone Marrow Stromal Cells from Different Anatomical Locations

The bone cancer osteosarcoma, found mainly in adolescents, routinely forms around the growth plate/metaphysis of long bones. Bone marrow composition changes with age, shifting from a more hematopoietic to an adipocyte-rich tissue. This conversion occurs in the metaphysis during adolescence, implicating a link between bone marrow conversion and osteosarcoma initiation. To assess this, the tri-lineage differentiation potential of human bone marrow stromal cells (HBMSCs) isolated from the femoral diaphysis/metaphysis (FD) and epiphysis (FE) was characterized and compared to two osteosarcoma cell lines, Saos-2 and MG63. Compared to FE-cells, FD-cells showed an increase in tri-lineage differentiation. Additionally, differences were found between the Saos-2 cells exhibiting higher levels of osteogenic differentiation, lower adipogenic differentiation, and a more developed chondrogenic phenotype than MG63, with the Saos-2 being more comparable to FD-derived HBMSCs. The differences found between the FD and FE derived cells are consistent with the FD region containing more hematopoietic tissue compared to the FE. This may be related to the similarities between FD-derived cells and Saos-2 cells during osteogenic and chondrogenic differentiation. These studies reveal distinct differences in the tri-lineage differentiations of 'hematopoietic' and 'adipocyte rich' bone marrow, which correlate with specific characteristics of the two osteosarcoma cell lines.

Update on Immune Mechanisms in Hypertension

The contribution of immune cells in the initiation and maintenance of hypertension is undeniable. Several studies have established the association between hypertension, inflammation, and immune cells from the innate and adaptive immune systems. Here, we provide an update to our 2017 American Journal of Hypertension review on the overview of the cellular immune responses involved in hypertension. Further, we discuss the activation of immune cells and their contribution to the pathogenesis of hypertension in different in vivo models. We also highlight existing gaps in the field of hypertension that need attention. The main goal of this review is to provide a knowledge base for translational research to develop therapeutic strategies that can improve cardiovascular health in humans.

Controlled n-Doping of Naphthalene-Diimide-Based 2D Polymers

2D polymers (2DPs) are promising as structurally well-defined, permanently porous, organic semiconductors. However, 2DPs are nearly always isolated as closed shell organic species with limited charge carriers, which leads to low bulk conductivities. Here, the bulk conductivity of two naphthalene diimide (NDI)-containing 2DP semiconductors is enhanced by controllably n-doping the NDI units using cobaltocene (CoCp₂ ). Optical and transient microwave spectroscopy reveal that both as-prepared NDI-containing 2DPs are semiconducting with sub-2 eV optical bandgaps and photoexcited charge-carrier lifetimes of tens of nanoseconds. Following reduction with CoCp₂ , both 2DPs largely retain their periodic structures and exhibit optical and electron-spin resonance spectroscopic features consistent with the presence of NDI-radical anions. While the native NDI-based 2DPs are electronically insulating, maximum bulk conductivities of >10^-4  S cm^-1 are achieved by substoichiometric levels of n-doping. Density functional theory calculations show that the strongest electronic couplings in these 2DPs exist in the out-of-plane (π-stacking) crystallographic directions, which indicates that cross-plane electronic transport through NDI stacks is primarily responsible for the observed electronic conductivity. Taken together, the controlled molecular doping is a useful approach to access structurally well-defined, paramagnetic, 2DP n-type semiconductors with measurable bulk electronic conductivities of interest for electronic or spintronic devices.

Use of integrated metabolomics, transcriptomics, and signal protein profile to characterize the effector function and associated metabotype of polarized macrophage phenotypes

MΦs display remarkable plasticity and the ability to activate diverse responses to a host of intracellular and external stimuli. Despite extensive characterization of M1 MΦs and a broad set of M2 MΦs, comprehensive characterization of functional phenotype and associated metabotype driving this diverse MΦ activation remains. Herein, an ex vivo model was utilized to produce 6 MΦ functional phenotypes. Isolated CD14⁺ PBMCs were differentiated into resting M0 MΦs, and then polarized into M1 (IFN-γ/LPS), M2a (IL-4/IL-13), M2b (IC/LPS), M2c (IL-10), and M2d (IL-6/LIF) MΦs. The MΦs were profiled using a bioanalyte matrix of 4 cell surface markers, ∼50 secreted proteins, ∼800 expressed myeloid genes, and ∼450 identified metabolites relative to M0 MΦs. Signal protein and expressed gene profiles grouped the MΦs into inflammatory (M1 and M2b) and wound resolution (M2a, M2c, and M2d) phenotypes; however, each had a unique metabolic profile. While both M1 and M2b MΦs shared metabotype profiles consistent with an inflammatory signature; key differences were observed in the TCA cycle, FAO, and OXPHOS. Additionally, M2a, M2c, and M2d MΦs all profiled as tissue repair MΦs; however, metabotype differences were observed in multiple pathways including hexosamine, polyamine, and fatty acid metabolism. These metabolic and other key functional distinctions suggest phagocytic and proliferative functions for M2a MΦs, and angiogenesis and ECM assembly capabilities for M2b, M2c, and M2d MΦs. By integrating metabolomics into a systems analysis of MΦ phenotypes, we provide the most comprehensive map of MΦ diversity to date, along with the global metabolic shifts that correlate to MΦ functional plasticity in these phenotypes.

Powerful Organic Molecular Oxidants and Reductants Enable Ambipolar Injection in a Large-Gap Organic Homojunction Diode

Doping has proven to be a critical tool for enhancing the performance of organic semiconductors in devices like organic light-emitting diodes. However, the challenge in working with high-ionization-energy (IE) organic semiconductors is to find p-dopants with correspondingly high electron affinity (EA) that will improve the conductivity and charge carrier transport in a film. Here, we use an oxidant that has been recently recognized to be a very strong p-type dopant, hexacyano-1,2,3-trimethylene-cyclopropane (CN6-CP). The EA of CN6-CP has been previously estimated via cyclic voltammetry to be 5.87 eV, almost 300 meV higher than other known high-EA organic molecular oxidants. We measure the frontier orbitals of CN6-CP using ultraviolet and inverse photoemission spectroscopy techniques and confirm a high EA value of 5.88 eV in the condensed phase. The introduction of CN6-CP in a film of large-band-gap, large-IE phenyldi(pyren-1-yl)phosphine oxide (POPy₂) leads to a significant shift of the Fermi level toward the highest occupied molecular orbital and a 2 orders of magnitude increase in conductivity. Using CN6-CP and n-dopant (pentamethylcyclopentadienyl)(1,3,5-trimethylbenzene)ruthenium (RuCp*Mes)₂, we fabricate a POPy₂-based rectifying p-i-n homojunction diode with a 2.9 V built-in potential. Blue light emission is achieved under forward bias. This effect demonstrates the dopant-enabled hole injection from the CN6-CP-doped layer and electron injection from the (RuCp*Mes)₂-doped layer in the diode.

Implementing Standardized Patient Caregivers to Practice Difficult Conversations in a Pediatric Dentistry Course

INTRODUCTION

Standardized patient (SP) methodology has been used in health professional education to help students develop communication, deeper diagnostic reasoning, and critical thinking skills. Few examples demonstrate the use of SPs to practice difficult conversations with pediatric caregivers in the pediatric dentistry literature. The objective of this educational activity was to describe the implementation of three SPs in a pediatric dentistry course for second-year dental students.

METHODS

We developed three SP encounters covering interactions with caregivers of an infant with severe early childhood caries, an adolescent on the path to gender affirmation, and a child with autism and dental caries whose caregiver was resistant to fluoride- and silver-containing dental materials. We describe the case design process, rubric construction and calibration, student debriefing, and pandemic modifications. We evaluated the effectiveness of the implementation by thematic analysis of student reflections following each encounter using a qualitative descriptive framework.

RESULTS

Eighty-three students completed each encounter. Qualitative analysis showed that students preferred a more realistic encounter by having a child or other distraction present. Students relied on different elements of motivational interviewing depending on the objective of each encounter and the age of the patient. Overall, the SP encounters were well received by students and faculty as an alternative or supplement to traditional student evaluation methods.

DISCUSSION

We noted a number of lessons learned about implementing SP methodology in pediatric dental education. With these experiences now in place, future evaluations should measure student performance in the SP encounters against student performance during clinical care.

Automated in vivo drug screen in zebrafish identifies synapse-stabilising drugs with relevance to spinal muscular atrophy

Synapses are particularly vulnerable in many neurodegenerative diseases and often the first to degenerate, for example in the motor neuron disease spinal muscular atrophy (SMA). Compounds that can counteract synaptic destabilisation are rare. Here, we describe an automated screening paradigm in zebrafish for small-molecule compounds that stabilize the neuromuscular synapse in vivo. We make use of a mutant for the axonal C-type lectin chondrolectin (chodl), one of the main genes dysregulated in SMA. In chodl-/- mutants, neuromuscular synapses that are formed at the first synaptic site by growing axons are not fully mature, causing axons to stall, thereby impeding further axon growth beyond that synaptic site. This makes axon length a convenient read-out for synapse stability. We screened 982 small-molecule compounds in chodl chodl-/- mutants and found four that strongly rescued motor axon length. Aberrant presynaptic neuromuscular synapse morphology was also corrected. The most-effective compound, the adenosine uptake inhibitor drug dipyridamole, also rescued axon growth defects in the UBA1-dependent zebrafish model of SMA. Hence, we describe an automated screening pipeline that can detect compounds with relevance to SMA. This versatile platform can be used for drug and genetic screens, with wider relevance to synapse formation and stabilisation.

Domain binding and isotype dictate the activity of anti-human OX40 antibodies

BACKGROUND

Previous data suggests that anti-OX40 mAb can elicit anti-tumor effects in mice through deletion of Tregs. However, OX40 also has powerful costimulatory effects on T cells which could evoke therapeutic responses. Human trials with anti-OX40 antibodies have shown that these entities are well tolerated but to date have delivered disappointing clinical responses, indicating that the rules for the optimal use of anti-human OX40 (hOX40) antibodies is not yet fully understood. Changes to timing and dosages may lead to improved outcomes; however, here we focus on addressing the role of agonism versus depleting activity in determining therapeutic outcomes. We investigated a novel panel of anti-hOX40 mAb to understand how these reagents and mechanisms may be optimized for therapeutic benefit.

METHODS

This study examines the binding activity and in vitro activity of a panel of anti-hOX40 antibodies. They were further evaluated in several in vivo models to address how isotype and epitope determine mechanism of action and efficacy of anti-hOX40 mAb.

RESULTS

Binding analysis revealed the antibodies to be high affinity, with epitopes spanning all four cysteine-rich domains of the OX40 extracellular domain. In vivo analysis showed that their activities relate directly to two key properties: (1) isotype-with mIgG1 mAb evoking receptor agonism and CD8+ T-cell expansion and mIgG2a mAb evoking deletion of Treg and (2) epitope-with membrane-proximal mAb delivering more powerful agonism. Intriguingly, both isotypes acted therapeutically in tumor models by engaging these different mechanisms.

CONCLUSION

These findings highlight the significant impact of isotype and epitope on the modulation of anti-hOX40 mAb therapy, and indicate that CD8+ T-cell expansion or Treg depletion might be preferred according to the composition of different tumors. As many of the current clinical trials using OX40 antibodies are now using combination therapies, this understanding of how to manipulate therapeutic activity will be vital in directing new combinations that are more likely to improve efficacy and clinical outcomes.

Interaction of Axonal Chondrolectin with Collagen XIXa1 Is Necessary for Precise Neuromuscular Junction Formation

Chondrolectin (Chodl) is needed for motor axon extension in zebrafish and is dysregulated in mouse models of spinal muscular atrophy (SMA). However, the mechanistic basis of Chodl function is not known. Here, we use Chodl-deficient zebrafish and mouse mutants to show that the absence of Chodl leads to anatomical and functional defects of the neuromuscular synapse. In zebrafish, the growth of an identified motor axon beyond an "en passant" synapse and later axon branching from synaptic points are impaired, leading to functional deficits. Mechanistically, motor-neuron-autonomous Chodl function depends on its intracellular domain and on binding muscle-derived collagen XIXa1 by its extracellular C-type lectin domain. Our data support evolutionarily conserved roles of Chodl in synaptogenesis and provide evidence for a "synapse-first" scenario of motor axon growth in zebrafish.

Long term use of hydraulic artificial urethral sphincters in nine dogs from New Zealand with urethral sphincter mechanism incompetence

AIMS

To report on the long-term outcomes of hydraulic artificial urethral sphincter (HAUS) placement for the correction of urethral sphincter mechanism incompetence (USMI) in New Zealand dogs.

METHODS

Retrospective data were obtained from cases of dogs which had a HAUS placed after failed medical and/or surgical management of USMI between August 2012 and November 2016. Owner assessment of urinary incontinence was evaluated by an online survey in May 2017 using a visual analogue scale (0 being normal, 100 being severely affected) for the frequency, volume and severity of any straining to urinate, immediately prior to the placement of the HAUS and at the time of the survey. The number of days between surgery and the completion of survey were recorded.

RESULTS

Seven females and two male dogs, which were all desexed except for one female, were eligible for inclusion in the study. The period of follow-up following HAUS placement ranged from 206-1,685 days. Following HAUS placement, frequency and volume of urinary incontinence decreased for six dogs and were practically unchanged for three dogs. The median frequency score decreased from 70 to 13 and the volume score decreased from 73 to 12. There was no consistent change in the perceived degree of straining to urinate. Complications occurred in three dogs; one required repositioning of a dislodged injection port, one required management for haematuria and a hypoplastic bladder, and one required surgical removal of fibrous tissue around the HAUS cuff.

CONCLUSIONS AND CLINICAL RELEVENCE

HAUS placement was an effective method for the treatment of persistent USMI in most dogs and provided good clinical results based on owner assessment. The technique was associated with few complications and allowed successful long-term control of urinary incontinence without the need for medical management.

Nuclear quantum effect with pure anharmonicity and the anomalous thermal expansion of silicon

Despite the widespread use of silicon in modern technology, its peculiar thermal expansion is not well understood. Adapting harmonic phonons to the specific volume at temperature, the quasiharmonic approximation, has become accepted for simulating the thermal expansion, but has given ambiguous interpretations for microscopic mechanisms. To test atomistic mechanisms, we performed inelastic neutron scattering experiments from 100 K to 1,500 K on a single crystal of silicon to measure the changes in phonon frequencies. Our state-of-the-art ab initio calculations, which fully account for phonon anharmonicity and nuclear quantum effects, reproduced the measured shifts of individual phonons with temperature, whereas quasiharmonic shifts were mostly of the wrong sign. Surprisingly, the accepted quasiharmonic model was found to predict the thermal expansion owing to a large cancellation of contributions from individual phonons.

Design and operating characteristic of a vacuum furnace for time-of-flight inelastic neutron scattering measurements

We present the design and operating characteristics of a vacuum furnace used for inelastic neutron scattering experiments on a time-of-flight chopper spectrometer. The device is an actively water cooled radiant heating furnace capable of performing experiments up to 1873 K. Inelastic neutron scattering studies performed with this furnace include studies of phonon dynamics and metallic liquids. We describe the design, control, characterization, and limitations of the equipment. Further, we provide comparisons of the neutron performance of our device with commercially available options. Finally we consider upgrade paths to improve performance and reliability.

IL-6 secretion in osteoarthritis patients is mediated by chondrocyte-synovial fibroblast cross-talk and is enhanced by obesity

Increasing evidence suggests that inflammation plays a central role in driving joint pathology in certain patients with osteoarthritis (OA). Since many patients with OA are obese and increased adiposity is associated with chronic inflammation, we investigated whether obese patients with hip OA exhibited differential pro-inflammatory cytokine signalling and peripheral and local lymphocyte populations, compared to normal weight hip OA patients. No differences in either peripheral blood or local lymphocyte populations were found between obese and normal-weight hip OA patients. However, synovial fibroblasts from obese OA patients were found to secrete greater amounts of the pro-inflammatory cytokine IL-6, compared to those from normal-weight patients (p < 0.05), which reflected the greater levels of IL-6 detected in the synovial fluid of the obese OA patients. Investigation into the inflammatory mechanism demonstrated that IL-6 secretion from synovial fibroblasts was induced by chondrocyte-derived IL-6. Furthermore, this IL-6 inflammatory response, mediated by chondrocyte-synovial fibroblast cross-talk, was enhanced by the obesity-related adipokine leptin. This study suggests that obesity enhances the cross-talk between chondrocytes and synovial fibroblasts via raised levels of the pro-inflammatory adipokine leptin, leading to greater production of IL-6 in OA patients.

Solution-Processed Organic and Halide Perovskite Transistors on Hydrophobic Surfaces

Solution-processable electronic devices are highly desirable due to their low cost and compatibility with flexible substrates. However, they are often challenging to fabricate due to the hydrophobic nature of the surfaces of the constituent layers. Here, we use a protein solution to modify the surface properties and to improve the wettability of the fluoropolymer dielectric Cytop. The engineered hydrophilic surface is successfully incorporated in bottom-gate solution-deposited organic field-effect transistors (OFETs) and hybrid organic-inorganic trihalide perovskite field-effect transistors (HTP-FETs) fabricated on flexible substrates. Our analysis of the density of trapping states at the semiconductor-dielectric interface suggests that the increase in the trap density as a result of the chemical treatment is minimal. As a result, the devices exhibit good charge carrier mobilities, near-zero threshold voltages, and low electrical hysteresis.

Prevention of allograft HCV recurrence with peri-transplant human monoclonal antibody MBL-HCV1 combined with a single oral direct-acting antiviral: A proof-of-concept study

Patients with active hepatitis C virus (HCV) infection at transplantation experience rapid allograft infection, increased risk of graft failure and accelerated fibrosis. MBL-HCV1, a neutralizing human monoclonal antibody (mAb) targeting the HCV envelope, was combined with a licensed oral direct-acting antiviral (DAA) to prevent HCV recurrence post-transplant in an open-label exploratory efficacy trial. Eight subjects received MBL-HCV1 beginning on the day of transplant with telaprevir initiated between days 3 and 7 post-transplantation. Following FDA approval of sofosbuvir, two subjects received MBL-HCV1 starting on the day of transplant with sofosbuvir initiated on day 3. Combination treatment was administered for 8-12 weeks or until the stopping rule for viral rebound was met. The primary endpoint was undetectable HCV RNA at day 56 with exploratory endpoints of sustained virologic response (SVR) at 12 and 24 weeks post-treatment. Both subjects receiving mAb and sofosbuvir achieved SVR24. Four of eight subjects in the mAb and telaprevir group met the primary endpoint; one subject achieved SVR24 and three subjects relapsed 2-12 weeks post-treatment. The other four subjects experienced viral breakthrough. There were no serious adverse events related to study treatment. This proof-of-concept study demonstrates that peri-transplant immunoprophylaxis combined with a single oral direct-acting antiviral in the immediate post-transplant period can prevent HCV recurrence.

Failed tracheostomy under local anaesthesia…plan B?

Severe stridor of recent onset is a challenge to deal with because of the lack of investigations on which to base the management plan. We describe a case of an elderly lady who presented to us with a short history of severe stridor. We encountered unanticipated difficulties with tracheostomy under local anaesthesia as the thyroid was replaced by a diffuse mass and the airway had to be secured by an awake fibre-optic intubation. Awake fibre-optic intubation is thought to be a relative contraindication in acute upper airway obstruction, but occasionally tracheostomy under local anaesthesia may not be possible and in experienced hands an awake fibre-optic intubation is a reasonable alternative.

The Discrete Dynamics of Monotonically Decomposable Maps

We extend results of Gouzé and Hadeler (in Nonlinear World 1:23-34, 1994) concerning the dynamics generated by a map on an ordered metric space that can be decomposed into increasing and decreasing parts. Our main results provide sufficient conditions for the existence of a globally asymptotically stable fixed point for the map. Applications to discrete-time, stage-structured population models are given.

Emergency tracheal catheterization for jet ventilation: a role for the ENT surgeon?

Stridor causing respiratory failure is an ENT and anaesthetic emergency requiring prompt management to secure a clear airway. We describe a case of subacute partial upper airway obstruction due to a large laryngeal carcinoma in an 81-year-old male resulting in respiratory failure. The patient became apnoeic after gaseous induction of general anaesthesia, and after two failed intubation attempts an emergency transtracheal airway catheter was placed by the surgeon under direct vision below the cricothyroid membrane, as this had tumour involvement. The patient was subsequently manually jet-ventilated with ease until a formal tracheostomy was made. Where difficulties with tracheal anatomy are encountered due to the presence of pathology, the insertion of a temporary airway catheter for jet ventilation by the surgeon can buy valuable time and be life-saving.

Awake insertion of the laryngeal mask airway using topical lidocaine and intravenous remifentanil*

We assessed the use of intravenous remifentanil for the insertion of the laryngeal mask airway in 10 healthy awake volunteers, a technique primarily developed to facilitate functional magnetic resonance imaging studies of anaesthesia. Each volunteer received 200 microg glycopyrronium intravenously. Topical airway anaesthesia was effected by 4 ml nebulised lidocaine 4%, followed by 12 sprays of lidocaine 10%. Remifentanil was subsequently infused to achieve an initial target effect-site concentration of 2 ng.ml(-1); increments of 1 ng.ml(-1) were allowed with the maximum effect-site concentration limited to 6 ng.ml(-1). Insertion of the laryngeal mask airway was successful on the first attempt in all cases. The median (IQR [range]) target effect-site remifentanil concentration at insertion was 2.5 (2-3 [2-4]) ng.ml(-1). All volunteers were co-operative during the procedure and only one reported discomfort. Sore throat was a complication in all volunteers. We conclude that the technique allows successful insertion of the laryngeal mask airway in healthy awake volunteers under conditions that were safe and reproducible.

Influence of improved teaching on medical students’ acquisition and retention of drug administration skills

BACKGROUND

Drug administration error is a major problem causing substantial morbidity and mortality worldwide. Lack of education about drug administration appears to be a causative factor. We devised an online teaching module for medical students and assessed its short- and long-term efficacy.

METHODS

One hundred and thirty clinical medical students were invited to undertake additional, online, teaching about drug administration. Those participating were identified and the number of web pages viewed recorded. The students' knowledge retention was tested by means of drug administration questions incorporated into routine assessments and examinations over the next 6 months. Other indices of all students' performance were recorded to correct for confounding factors.

RESULTS

Just over half (52%) responded to the invitation to participate. The amount of interest they showed in the teaching module correlated positively with their performance in questions about drug administration, although the latter waned over time. Surprisingly, correcting for students' general ability and keenness revealed that the less able students were most likely to undertake the teaching module.

CONCLUSIONS

Additional online teaching about drug administration improves students' knowledge of the topic but clearly requires reinforcement; however, only about half the students took up the option. Medical students must acquire these fundamental skills, and online teaching can help. Medical educators must ensure that drug administration is taught formally to all students as part of the curriculum and must understand that it may require additional teaching.

Integrated approaches to academic anaesthesia - the Cambridge experience

There is mounting concern about the pressures experienced by University Departments of Anaesthesia, which, if lost, could threaten undergraduate peri-operative medicine teaching, development of critical appraisal skills among anaesthetists, and the future of coherent research programs. We have addressed these problems by establishing a foundation course in scientific methods and research techniques (the Cambridge SMART Course), complemented by competitive, fully funded, 12-month academic trainee attachments. Research conducted during academic attachments has been published and used to underpin substantive grant applications allowing work towards higher degrees. Following the attachment, a flexible scheme ensures safe reintroduction to clinical training. Research at consultant level is facilitated by encouraging applications for Clinician Scientist Fellowships, and by ensuring that the University Department champions, legitimises and validates the allocation of research time within the new consultant contract. We believe that these are important steps in safeguarding research and teaching in anaesthesia, critical care and peri-operative medicine.

A web-based system for teaching, assessment and examination of the undergraduate peri-operative medicine curriculum

Today's students are generally computer literate and have high expectations of university information technology resources. Most United Kingdom medical schools now provide networked computers for learning, research, communication and accessing the worldwide web. We have exploited these advances to augment and improve the teaching of peri-operative medicine and anaesthesia to medical students in our university, who are taught in several hospitals over a wide geographical area. Course material such as departmental induction information, lecture notes and assessment sheets can be accessed online, contributing to the smooth running of the course. Streamed videos and simulations allow students to familiarise themselves with common practical procedures in advance. Development of a web-based end of course assessment has resulted in substantially less administration and bureaucracy for course organisers and proved to be a valuable research tool. Students' and teachers' opinions of the new course structure have been overwhelmingly positive.

Childhood obesity: a challenge for the anaesthetist?

The definition of childhood obesity has not been standardized in the past, making studies difficult to compare. In spite of this, the increase in the incidence of childhood obesity is evident and has now reached epidemic proportions. Obese children experience few of the medical complications seen in obese adults. Respiratory physiology appears to be most affected, the degree of which is determined by the level of obesity. Although there is a considerable amount of information on the anaesthetic management of the obese adult, very little has been written concerning the obese child. There is less pathology in the obese child when compared with the adult but some evidence shows a higher likelihood of a critical incident occurring when anaesthetizing such children. This shows that we need to be as worried about anaesthetizing the obese child as we are for the obese adult. This concern should increase with increasing body mass index.

Effect of videotape feedback on anaesthetists' performance while managing simulated anaesthetic crises: a multicentre study

The aim of this study was to examine the performance of anaesthetists while managing simulated anaesthetic crises and to see whether their performance was improved by reviewing their own performances recorded on videotape. Thirty-two subjects from four hospitals were allocated randomly to one of two groups, with each subject completing five simulations in a single session. Individuals in the first group completed five simulations with only a short discussion between each simulation. Those in the second group were allowed to review their own performance on videotape between each of the simulations. Performance was measured by both 'time to solve the problem' and mental workload, using anaesthetic chart error as a secondary task. Those trainees exposed to videotape feedback had a shorter median 'time to solve' and a smaller decrease in chart error when compared to those not exposed to video feedback. However, the differences were not statistically significant, confirming the difficulties encountered by other groups in designing valid tests of the performance of anaesthetists.

The poverty of information systems management in home health agencies: implications for survivability

Home health agencies are increasingly being challenged to cope with economic, financial and clinical pressures. This study examines the extent to which home health agencies have cultivated their information systems as an aid for managing performance and external forces. Colorado and New Mexico home health agencies participated in the research project. The findings indicate that only modest investments have been made by respondents in their information systems. The typical respondent reports a personal computer-based system which addresses some financial reporting data, but which does not emphasize care delivery or contextual factors. The implications of these findings for the survivability of home health agencies are discussed.

Non-invasive assessment of shunt and ventilation/perfusion ratio in neonates with pulmonary failure

AIMS

To make non-invasive measurements of right to left (R-L) shunt and reduced ventilation/perfusion ratio (V(A)/Q) in neonates with pulmonary failure and to examine sequential changes in these variables after treatment.

METHODS

Twelve neonates with pulmonary failure were studied. They ranged in gestational age from 24 to 37 (median 27) weeks and were 1-39 (median 4) days old. Shunt and reduced V(A)/Q were derived from their effects on the relation between inspired oxygen pressure (PIO(2)) and arterial oxygen saturation measured with a pulse oximeter (SpO(2)). Pairs of PIO(2) v. SpO(2) data points were obtained by varying PIO(2) in a stepwise fashion. A computer algorithm based on a model of pulmonary gas exchange fitted a curve to these data. With PIO(2) on the abscissa, an increase in shunt produced a downward movement of the curve, whereas reducing V(A)/Q to < 0.8 shifted the curve to the right. The right shift gives a variable that is inversely related to V(A)/Q, the PIO(2) - PO(2) difference, where PO(2) is mixed capillary oxygen pressure.

RESULTS

Ten of the 12 infants on the first study day had large shunts (range 5.9-31.0%, median 19.9%, normal < 8%) and large PIO(2) - PO(2) differences (range 9.7-64.4 kPa, median 19.8 kPa, normal < 7 kPa) equivalent to a median V(A)/Q of 0.2 (normal median V(A)/Q = 0.8). Sequential improvement in shunt and V(A)/Q were shown in most infants after treatment. Sudden large changes in these variables were shown in two infants.

CONCLUSION

This simple non-invasive method distinguishes between shunt and reduced V(A)/Q in neonates with pulmonary failure.

Modelling non-linearities in the vestibulo-ocular reflex (VOR) after unilateral or bilateral loss of peripheral vestibular function

We recorded the vestibulo-ocular reflex (VOR) in 18 normal subjects, 50 patients with unilateral loss of vestibular function and 18 patients with bilateral loss of vestibular function. The unilateral cases had either partial loss (i.e. vestibular neuronitis or Meniere's disease) or total loss (i.e. vestibular nerve section), whereas bilateral cases had only partial loss (i.e. due to ototoxicity or to suspected microangiopathy, secondary to severe kidney disease). Tests were performed at 1/6-Hz passive head rotation in the dark, with peak head velocities ranging from 125 to 190 degrees/s. We report on the distinct VOR non-linearities observed in unilateral versus bilateral patients: whereas unilateral patients all exhibit an asymmetric hypofunction with decreasing VOR gain at higher head velocities, bilateral patients have a more severe but symmetric hypofunction associated with increasing VOR gain at higher head velocities. We present a model study that can duplicate the nature of these characteristics, based mainly on peripheral non-linear semicircular canal characteristics and secondary central compensation. Theoretical analyses point to the importance of clinical test parameters (rotation speed and frequency) in the determination of a functional VOR and the detection of reflex non-linearities, so that test protocols can seriously bias the evaluation of adequate functional recovery.

Inhibitors of the lipoxygenase pathway block development of Brugia malayi L3 in vitro

Brugia malayi L3 molt to the L4 stage in serum-free cultures supplemented with arachidonic, linoleic, or linolenic acids and the basidiomycetous yeast Rhodotorula minuta. These fatty acids are capable of entering the eicosanoid pathway of arachidonate metabolism, the pathway responsible for generating a number of biologically active mediators, including prostaglandins, leukotrienes, and lipoxins. To determine whether this pathway was required for L3 development, we added dual inhibitors of cyclooxygenase and lipoxygenase to in vitro cultures containing B. malayi L3. These compounds significantly inhibited L3 molting. To evaluate whether 1 or both of these pathways of arachidonate metabolism were involved in molting, we tested drugs inhibiting either cyclooxygenase or lipoxygenase. Lipoxygenase inhibitors blocked L3 molting, whereas cyclooxygenase inhibitors did not. To assess whether enzymes operating downstream of lipoxygenase were also involved in L3 molting, we added inhibitors of enzymes involved in leukotriene synthesis and found they were also capable of preventing development. We tested the same inhibitor panel on Dirofilaria immitis L3. A single lipoxygenase inhibitor and inhibitors of 2 different enzymes operating downstream of lipoxygenase disrupted D. immitis development. These results demonstrate that a lipoxygenase pathway product is required for molting of the infective stage larvae of filarial parasites.

Predicting and explaining cardiac rehabilitation attendance

BACKGROUND

A variety of factors influence patients' health behaviour; these are patterns of practitioner practice, patient characteristics and availability of resources.

OBJECTIVES

To examine patient-related factors (demographic, health, psychosocial characteristics) that may influence patients' attendance at cardiac rehabilitation programs and their subsequent behaviour change.

PATIENTS AND METHODS

A prospective cohort design was used. Three hundred four acute myocardial infarction and/or coronary artery bypass graft surgery patients from a tertiary care centre in a Western Canadian city were enrolled to participate in telephone interviews at two weeks and again at approximately six months after their hospital discharge. Measures of self-efficacy and behaviour performance for cardiac health maintenance and role resumption, motivation and social support were used at both interview times. A survey focusing on factors influencing patients' choices to attend cardiac rehabilitation programs was also administered at the interview six months after discharge.

RESULTS

Attendance at cardiac rehabilitation programs is not associated with patients' risk factor status, and elderly and rural-living patients are at particular risk for nonattendance.

CONCLUSIONS

Systematic mechanisms to guide the appropriate referral of patients to this health care resource and administer secondary prevention initiatives to those with limited access to resources need to be a priority in cardiovascular health care.

Psychosocial components of cardiac recovery and rehabilitation attendance

OBJECTIVE

To examine the relations between demographic factors, specific psychosocial factors, and cardiac rehabilitation attendance.

DESIGN

Cohort, repeated measures design.

SETTING

A large tertiary care centre in western Canada

PATIENTS

304 consecutive consenting patients discharged following acute myocardial infarction and/or coronary artery bypass graft surgery.

MAIN OUTCOME MEASURES

The Jenkins self-efficacy expectation scales and activity checklists of behaviour performance for maintaining health and role resumption, modified version of the self-motivation inventory, and the shortened social support scale.

RESULTS

Those who had higher role resumption behaviour performance scores at two weeks after discharge were significantly less likely to attend cardiac rehabilitation programmes. At six months after discharge, those who attended cardiac rehabilitation demonstrated higher health maintenance self-efficacy expectation and behaviour performance scores. Health maintenance self-efficacy expectation and behaviour performance improved over time. Women reported less social support but showed greater improvement in health maintenance self-efficacy expectation. Changes in self-efficacy scores were unrelated to-but changes in health maintenance behaviour performance scores were strongly associated with-cardiac rehabilitation attendance.

CONCLUSIONS

Cardiac patients and practitioners may have misconceptions about the mandate and potential benefits of rehabilitation programmes. Patients who resumed role related activities early and more completely apparently did not see the need to "rehabilitate" while those who attended cardiac rehabilitation programmes enhanced their secondary prevention behaviours.

Assessing future possible selves by gender and socioeconomic status using the anticipated life history measure

This is a report from the first phase of a longitudinal study of the ways young adults imagine their future lives. The future possible selves of 223 18- and 19-year-old adults were examined using the Anticipated Life History measure (ALH), a psychological instrument prompting participants to describe their future life course from their 21st birthday until their death. When the ALH narratives were coded for presence/absence of life events, female participants were more likely to predict career choice, marriage, children, divorce, and death of spouse than their male counterparts; when coded for psychological qualities, female participants demonstrated greater psychological complexity and awareness of future life role choices and conflicts. Participants with lower SES wrote ALH narratives with fewer altruistic acts, less awareness of life role complexity, and fewer anticipated conflicts and their resolutions than those with higher SES.

Investigating development of infective stage larvae of filarial nematodes

Lymphatic filariasis is a parasitic disease affecting millions of individuals and one of the leading causes of disability in the world. However, considering the magnitude of filariasis as a public health problem, relatively little is known about the basic biology of the disease and its causative agents, filarial nematodes. In this paper, the biology of the infective stage larvae of the nematodes responsible for lymphatic filariasis and the approaches used to study their development are reviewed.

The poverty of information systems management in home health agencies: implications for survivability

Home health agencies are increasingly being challenged to cope with economic, financial and clinical pressures. This study examines the extent to which home health agencies have cultivated their information systems as an aid for managing performance and external forces. Colorado and New Mexico home health agencies participated in the research project. The findings indicate that only modest investments have been made by respondents in their information systems. The typical respondent reports a personal computer-based system which addresses some financial reporting data, but which does not emphasize care delivery or contextual factors. The implications of these findings for the survivability of home health agencies are discussed.

Husbands' versus wives' fertility goals and use of contraception: the influence of gender context in five Asian countries

Using data from Pakistan, India, Malaysia, Thailand, and the Philippines, we explore how gender context influences (1) husband-wife concordance in the demand for children and (2) the impact of each spouse's fertility preferences on contraceptive use. We also explore whether the husband's pronatalism can explain the wife's unmet need for contraception. The results suggest that gender context has little net effect on couples' concordance, but influences the relative weight of husbands' and wives' preferences in determining contraceptive use. Analysis of women's unmet need for contraception suggests that the husbands' pronatalism contributes to wives' unmet need, but only to a relatively small degree, especially in settings where unmet need is high. This is the case because the proportion of couples with differing fertility goals is small in most communities.

Development of a serum-free system for the in vitro cultivation of Brugia malayi infective-stage larvae

Over the past several years, numerous attempts have been made to culture the infective-stage (L3) larvae of the human filarial parasite Brugia malayi in an in vitro system that promotes molting to the fourth larval stage (L4). Although there have been reports in the literature of successful L3 to L4 development in vitro, all of these systems have required serum supplementation. The complexity of serum as a culture supplement has made reproducibility of results and identification of specific factors necessary for L3 development problematic. We have developed a serum-free in vitro system consisting of RPMI 1640 supplemented with one of three fatty acids (arachidonic, linoleic, or linolenic) that supports consistent and reproducible molting to the fourth larval stage in the presence of a basidiomycetous yeast, Rhodotorula minuta. Coculture with this yeast, initially isolated as a culture contaminant, is required for successful molting. In serum-free cultures lacking R. minuta, L3 larvae survive for upward of 2 weeks, but do not molt successfully. The L4 larvae generated in cultures containing R. minuta are well formed, as seen by light and electron microscopy, and are capable of further development upon transfer to a permissive host. This culture system is inexpensive and easily reproducible, thus making it a useful tool for studying the requirements for the development of B. malayi L3.

Tetracycline inhibits development of the infective-stage larvae of filarial nematodes in vitro

In recent years, studies have linked tetracycline treatment of filaria-infected animals with reduced adult worm burdens and decreased levels of microfilaremia. These observations are believed to be attributable to clearance of Wolbachia, intracellular rickettsial-like organisms found within filarial tissues. Although maximal worm reductions were observed when treatment was initiated early in infection, it is not known whether tetracycline inhibits development of infective-stage larvae. To address this issue, we studied the effect of tetracycline on three different species of filarial nematodes, Brugia malayi, Brugia pahangi, and Dirofilaria immitis, in a serumfree in vitro system supporting molting to the fourth larval stage. Tetracycline was capable of inhibiting L3 to L4 molting within a dosage range similar to that reported for susceptible rickettsial organisms. However, Wolbachia DNA could still be detected in nematodes from tetracycline-treated cultures. In addition, three other antibiotics with anti-rickettsial and anti-chlamydial activity (chloramphenicol, erythromycin, and ciprofloxacin) failed to inhibit L3 to L4 molting. Although tetracycline is capable of completely blocking molting of infective-stage larvae, it remains possible that this effect is due to pharmacological activities unrelated to its anti-rickettsial functions.

Evidence for male-biased dispersal in lake malawi cichlids from microsatellites

This study addressed within-population dispersal patterns among the species-rich Lake Malawi cichlids, specifically among the rock-dwelling mbuna group. Relatedness values were calculated for 160 individuals belonging to two species from known locations in the field by screening six highly polymorphic microsatellite loci. The results from both species indicate that spatially adjacent females have higher average relatedness values than those separated by larger distances, but that this pattern is reversed in males. This therefore provides firm evidence for male-biased dispersal within the Malawian cichlid flock.