A novel mechanical lung model of pulmonary diseases to assist with teaching and training

BACKGROUND: A design concept of low-cost, simple, fully mechanical model of a mechanically ventilated, passively breathing lung is developed. An example model is built to simulate a patient under mechanical ventilation with accurate volumes and compliances, while connected directly to a ventilator. METHODS: The lung is modelled with multiple units, represented by rubber bellows, with adjustable weights placed on bellows to simulate compartments of different superimposed pressure and compliance, as well as different levels of lung disease, such as Acute Respiratory Distress Syndrome (ARDS). The model was directly connected to a ventilator and the resulting pressure volume curves recorded. RESULTS: The model effectively captures the fundamental lung dynamics for a variety of conditions, and showed the effects of different ventilator settings. It was particularly effective at showing the impact of Positive End Expiratory Pressure (PEEP) therapy on lung recruitment to improve oxygenation, a particulary difficult dynamic to capture. CONCLUSION: Application of PEEP therapy is difficult to teach and demonstrate clearly. Therefore, the model provide opportunity to train, teach, and aid further understanding of lung mechanics and the treatment of lung diseases in critical care, such as ARDS and asthma. Finally, the model's pure mechanical nature and accurate lung volumes mean that all results are both clearly visible and thus intuitively simple to grasp

On the Inverse Problem of Binocular 3D Motion Perception

It is shown that existing processing schemes of 3D motion perception such as interocular velocity difference, changing disparity over time, as well as joint encoding of motion and disparity, do not offer a general solution to the inverse optics problem of local binocular 3D motion. Instead we suggest that local velocity constraints in combination with binocular disparity and other depth cues provide a more flexible framework for the solution of the inverse problem. In the context of the aperture problem we derive predictions from two plausible default strategies: (1) the vector normal prefers slow motion in 3D whereas (2) the cyclopean average is based on slow motion in 2D. Predicting perceived motion directions for ambiguous line motion provides an opportunity to distinguish between these strategies of 3D motion processing. Our theoretical results suggest that velocity constraints and disparity from feature tracking are needed to solve the inverse problem of 3D motion perception. It seems plausible that motion and disparity input is processed in parallel and integrated late in the visual processing hierarchy

Genome Typing and Epidemiology of Human Listeriosis in New Zealand, 1999 to 2018

International audienceThis study describes the epidemiology of listeriosis in New Zealand between 1999 and 2018 as well as the retrospective whole-genome sequencing (WGS) of 453 Listeria monocytogenes isolates corresponding to 95% of the human cases within this period. The average notified rate of listeriosis was 0.5 cases per 100,000 population, and non-pregnancy-associated cases were more prevalent than pregnancy-associated cases (averages of 19 and 5 cases per annum, respectively)

Epsilonproteobacteria in Humans, New Zealand

Using PCR–denaturing gradient gel electrophoresis, we examined 49 fecal samples from healthy volunteers and 128 diarrhea specimens to assess the distribution of Epsilonproteobacteria that might be routinely overlooked. Our results suggest that certain taxa that are not routinely examined for could account for a proportion of diarrhea of previously unknown etiology

Cathepsin-L can resist lysis by human serum in Trypanosoma brucei brucei.

Closely related African trypanosomes cause lethal diseases but display distinct host ranges. Specifically, Trypanosoma brucei brucei causes nagana in livestock but fails to infect humans, while Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense cause sleeping sickness in humans. T. b. brucei fails to infect humans because it is sensitive to innate immune complexes found in normal human serum known as trypanolytic factor (TLF) 1 and 2; the lytic component is apolipoprotein-L1 in both TLFs. TLF resistance mechanisms of T. b. gambiense and T. b. rhodesiense are now known to arise through either gain or loss-of-function, but our understanding of factors that render T. b. brucei susceptible to lysis by human serum remains incomplete. We conducted a genome-scale RNA interference (RNAi) library screen for reduced sensitivity to human serum. Among only four high-confidence 'hits' were all three genes previously shown to sensitize T. b. brucei to human serum, the haptoglobin-haemoglobin receptor (HpHbR), inhibitor of cysteine peptidase (ICP) and the lysosomal protein, p67, thereby demonstrating the pivotal roles these factors play. The fourth gene identified encodes a predicted protein with eleven trans-membrane domains. Using chemical and genetic approaches, we show that ICP sensitizes T. b. brucei to human serum by modulating the essential cathepsin, CATL, a lysosomal cysteine peptidase. A second cathepsin, CATB, likely to be dispensable for growth in in vitro culture, has little or no impact on human-serum sensitivity. Our findings reveal major and novel determinants of human-serum sensitivity in T. b. brucei. They also shed light on the lysosomal protein-protein interactions that render T. b. brucei exquisitely sensitive to lytic factors in human serum, and indicate that CATL, an important potential drug target, has the capacity to resist these factors

Use of HbA1c in the identification of patients with hyperglycaemia caused by a glucokinase mutation: observational case control studies.

HaemoglobinA1c (HbA1c) is recommended for diabetes diagnosis but fasting plasma glucose (FPG) has been useful for identifying patients with glucokinase (GCK) mutations which cause lifelong persistent fasting hyperglycaemia. We aimed to derive age-related HbA1c reference ranges for these patients to determine how well HbA1c can discriminate patients with a GCK mutation from unaffected family members and young-onset type 1 (T1D) and type 2 diabetes (T2D) and to investigate the proportion of GCK mutation carriers diagnosed with diabetes using HbA1c and/or FPG diagnostic criteria.This article is freely available via Open Access. Click on the ‘Additional Link’ above to access the full-text from the publisher’s site.07/0003473/Diabetes UK/United Kingdom PDA/02/06/098/Department of Health/United Kingdom RDA/03/07/073/Department of Health/United Kingdo

Topics, Skills, and Cases for an Undergraduate Musculoskeletal Curriculum in Southern Africa

Background: Most patients with orthopaedic pathology in low to middle-income countries are treated by nonspecialists. A curriculum to prepare undergraduate medical students for this duty should reflect the local pathology and skills that are required to manage patients in a resource-restricted environment. The aim of this study was to establish and prioritize a list of core orthopaedic-related knowledge topics, clinical cases, and skills that are relevant to medical students in southern Africa and areas with a similar clinical context. Methods: A modified Delphi consensus study was conducted with 3 interactive iterative rounds of communication and prioritization of items by experts from Africa, Europe, and North America. Preferred priorities were selected but were limited to 50% of all of the possible items. Percent agreement of ≥75% was defined as consensus on each of these items. Results: Most of the 43 experts who participated were orthopaedic surgeons from 7 different countries in southern Africa, but 28% were general practitioners or doctors working in primary or secondary-level facilities. Experts prioritized cases such as patients with multiple injuries, a limping child, and orthopaedic emergencies. Prioritized skills were manipulation and immobilization of dislocations and fractures. The most important knowledge topics included orthopaedic infections, the treatment of common fractures and dislocations, any red flags alerting to specialist referral, and back pain. Surgical skills for the treatment of urgent care conditions were included by some experts who saw a specific need in their clinical practice, but these were ranked lower. Conclusions: A wide geographic, academic, and expertise-specific footprint of experts informed this international consensus through their various clinical and academic circumstances. Knowledge topics, skills, and cases concerning orthopaedic trauma and infection were prioritized by the highest percent agreement. Acute primary care for fractures and dislocations ranked high. Furthermore, the diagnosis and the treatment of conditions not requiring specialist referral were prioritized. This study can inform national curricula in southern Africa and assist in the allocation of student clinical rotations