Assessing the effects of transient weather conditions on airborne transmission risk in naturally ventilated hospitals

BACKGROUND

Many UK hospitals rely heavily on natural ventilation as their main source of airflow in patient wards. This method of ventilation can have cost and energy benefits, but it may lead to unpredictable flow patterns between indoor spaces, potentially leading to the unexpected transport of infectious material to other connecting zones. However, the effects of weather conditions on airborne transmission are often overlooked.

METHODS

A multi-zone CONTAM model of a naturally ventilated hospital respiratory ward, incorporating time-varying weather, was proposed. Coupling this with an airborne infection model, this study assessed the variable risk in interconnected spaces, focusing particularly on occupancy, disease and ventilation scenarios based on a UK respiratory ward.

RESULTS

The results suggest that natural ventilation with varying weather conditions can cause irregularities in the ventilation rates and interzonal flow rates of connected zones, leading to infrequent but high peaks in the concentration of airborne pathogens in particular rooms. This transient behaviour increases the risk of airborne infection, particularly through movement of pathogens between rooms, and highlights that large outbreaks may be more likely under certain conditions. This study demonstrated how ventilation rates achieved by natural ventilation are likely to fall below the recommended guidance, and that the implementation of supplemental mechanical ventilation can increase ventilation rates and reduce the variability in infection risks.

CONCLUSION

This model emphasizes the need for consideration of transient external conditions when assessing the risk of transmission of airborne infection in indoor environments.

Instruments to measure skills and knowledge of physicians and medical students in palliative care: A systematic review of psychometric properties

PURPOSE

Palliative care is constantly increasing around the world. The knowledge and skills of future physicians in this area are crucial. This study evaluates the psychometric properties of knowledge and skills questionnaires used in palliative care, validated by physicians or medical students based on the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) methodology.

METHODS

A systematic review was carried out in Cosmin Databases, Cochrane Library, PsycINFO, SciELO, Cinahl, and Medline up to September 2020 (updated June 2021), based on the COSMIN methodology and PRISMA recommendations. The psychometric properties of each included questionnaire were identified. Methodological quality, quality of results, and quality of evidence were evaluated.

RESULTS

The search strategy yielded 12 questionnaires assessing the knowledge and skills of physicians or medical students. The Palliative Care Knowledge Questionnaire for PEACE (PEACE-Q) and Palliative Care Knowledge Test (PCKT) were the instruments with the highest scores for methodological quality, quality of results, and quality of evidence-based on the COSMIN methodology.

CONCLUSIONS

PEACE-Q and PCKT should be the preferred choice to assess palliative care knowledge and skills in physicians. In-depth studies following COSMIN validation criteria are recommended to improve the psychometric properties and cross-cultural validation of the questionnaires.

Why is mock care not a good proxy for predicting hand contamination during patient care?

BACKGROUND

Healthcare worker (HCW) behaviours, such as the sequence of their contacts with surfaces and hand hygiene moments, are important for understanding disease transmission.

AIM

To propose a method for recording sequences of HCW behaviours during mock vs actual procedures, and to evaluate differences for use in infection risk modelling and staff training.

METHODS

Procedures for three types of care were observed under mock and actual settings: intravenous (IV) drip care, observational care and doctors' rounds on a respiratory ward in a university teaching hospital. Contacts and hand hygiene behaviours were recorded in real-time using either a handheld tablet or video cameras.

FINDINGS

Actual patient care demonstrated 70% more surface contacts than mock care. It was also 2.4 min longer than mock care, but equal in terms of patient contacts. On average, doctors' rounds took 7.5 min (2.5 min for mock care), whilst auxiliary nurses took 4.9 min for observational care (2.4 min for mock care). Registered nurses took 3.2 min for mock IV care and 3.8 min for actual IV care; this translated into a 44% increase in contacts. In 51% of actual care episodes and 37% of mock care episodes, hand hygiene was performed before patient contact; in comparison, 15% of staff delivering actual care performed hand hygiene after patient contact on leaving the room vs 22% for mock care. The number of overall touches in the patient room was a modest predictor of hand hygiene. Using a model to predict hand contamination from surface contacts for Staphylococcus aureus, Escherichia coli and norovirus, mock care underestimated micro-organisms on hands by approximately 30%.

Palliative care undergraduate education: Do medical and nursing students need more skills in ethical and legal issues?

This study aimed to analyze the schools that teach ethical and legal aspects within the subject of palliative care in the degrees of medicine and nursing in Spain.

MATERIAL AND METHODS

Descriptive Analysis of the palliative care subject and their ethical and legal curricular competencies in the Spanish Nursing and Physicians undergraduate. The training received in legal ethical aspects related to palliative care was compared with the criteria established by the European Association for Palliative Care (EAPC).

DATA SOURCES

The National Conference of Nursing Deans, The National Conference of Spanish Medical Faculty Deans and The Ministry of Science, Innovation, and Universities databases were searched.

RESULTS

Twenty-one universities have an undergraduate in medicine with palliative care in their curricular training explicitly. The degree in nursing is present in fifty-six universities, palliative care is present in 62.5% of the cases. The degrees of nursing and medicine receive approximately the same level of training in ethical and legal aspects of palliative care.

CONCLUSION

The specific training received in ethical and legal issues of palliative care must be improved in medical and nursing to meet the EAPC levels.

At what stage in the undergraduate curriculum is it best to train in family medicine? A study from two medical schools in Spain

BACKGROUND

A course in family medicine (FM) could dispel the possibility of negative stereotyping about this speciality, and instil in students a greater interest. However, when is it preferable: at the beginning or at the end of undergraduate training?

OBJECTIVES

To determine changes in knowledge and attitudes towards FM by medical students completing a course in primary care at the beginning or the end of the undergraduate training and whether those changes anticipate the choice of speciality.

METHODS

Students from Albacete and Seville medical schools (primary care course in second and sixth years, respectively) were asked to respond to the 'valuation of attitudes towards and knowledge of family medicine questionnaire' (CAMF). Students from Albacete answered before and after the course, and in Seville second-year students answered at the end of the first trimester. All students were invited to respond again at the end of their undergraduate training. Afterwards, we investigated the score on the speciality exam (order for the election from highest to lowest score) and their choice of speciality. The outcome measures were the MIR exam score, the number in the ranking, the chosen speciality and the result of the CAMF.

RESULTS

In Albacete 88 and 64 and in Seville 50 and 98 students responded in their second and sixth years, respectively. In Albacete, mean CAMF scores were 15.4, 22.7 before and after the course, and 21.8 at the end while in Seville, 13.9 in the second year, and 23.5 in the sixth year. Logistic regression analysis showed an association of the choice of FM only with the score on the speciality exam (OR: 0.667; 95%CI: 0.553-0.806).

CONCLUSION

There were no significant differences between CAMF scores at the end of undergraduate training. Only the score on the speciality exam predicts FM choice: the higher the score, the lower the probability of choosing FM.

Quantifying the phosphorylation timescales of receptor-ligand complexes: a Markovian matrix-analytic approach

Cells interact with the extracellular environment by means of receptor molecules on their surface. Receptors can bind different ligands, leading to the formation of receptor-ligand complexes. For a subset of receptors, called receptor tyrosine kinases, binding to ligand enables sequential phosphorylation of intra-cellular residues, which initiates a signalling cascade that regulates cellular function and fate. Most mathematical modelling approaches employed to analyse receptor signalling are deterministic, especially when studying scenarios of high ligand concentration or large receptor numbers. There exist, however, biological scenarios where low copy numbers of ligands and/or receptors need to be considered, or where signalling by a few bound receptor-ligand complexes is enough to initiate a cellular response. Under these conditions stochastic approaches are appropriate, and in fact, different attempts have been made in the literature to measure the timescales of receptor signalling initiation in receptor-ligand systems. However, these approaches have made use of numerical simulations or approximations, such as moment-closure techniques. In this paper, we study, from an analytical perspective, the stochastic times to reach a given signalling threshold for two receptor-ligand models. We identify this time as an extinction time for a conveniently defined auxiliary absorbing continuous time Markov process, since receptor-ligand association/dissociation events can be analysed in terms of quasi-birth-and-death processes. We implement algorithmic techniques to compute the different order moments of this time, as well as the steady-state probability distribution of the system. A novel feature of the approach introduced here is that it allows one to quantify the role played by each kinetic rate in the timescales of signal initiation, and in the steady-state probability distribution of the system. Finally, we illustrate our approach by carrying out numerical studies for the vascular endothelial growth factor and one of its receptors, the vascular endothelial growth factor receptor of human endothelial cells.

[[Internet use by adolescents for medicine related topics]]

Señor editor: Internet ha revolucionado la manera de comunicarse y también el acceso a la información, especialmente entre los adolescentes. Lo que originariamente se buscaba en libros o se aprendía en los  hogares, muchos jóvenes hoy lo obtienen a golpe de clic, sin dejar al margen las cuestiones sobre temas médicos. Por ello hemos querido adentrarnos en el conocimiento de las características que ofrece Internet para determinar su uso por los  adolescentes en temas relacionados con la medicina

Validez predictiva del Cuestionario de Conocimientos y Actitudes hacia la Medicina de Familia abreviado

Señor editor: No abundan en la bibliografía instrumentos de valoración de conocimientos y actitudes hacia la medicina de familia (MF), y los pocos que existen proceden principalmente de ámbitos anglosajones… 

Stochastic descriptors to study the fate and potential of naive T cell clonotypes in the periphery

The population of naive T cells in the periphery is best described by determining both its T cell receptor diversity, or number of clonotypes, and the sizes of its clonal subsets. In this paper, we make use of a previously introduced mathematical model of naive T cell homeostasis, to study the fate and potential of naive T cell clonotypes in the periphery. This is achieved by the introduction of several new stochastic descriptors for a given naive T cell clonotype, such as its maximum clonal size, the time to reach this maximum, the number of proliferation events required to reach this maximum, the rate of contraction of the clonotype during its way to extinction, as well as the time to a given number of proliferation events. Our results show that two fates can be identified for the dynamics of the clonotype: extinction in the short-term if the clonotype experiences too hostile a peripheral environment, or establishment in the periphery in the long-term. In this second case the probability mass function for the maximum clonal size is bimodal, with one mode near one and the other mode far away from it. Our model also indicates that the fate of a recent thymic emigrant (RTE) during its journey in the periphery has a clear stochastic component, where the probability of extinction cannot be neglected, even in a friendly but competitive environment. On the other hand, a greater deterministic behaviour can be expected in the potential size of the clonotype seeded by the RTE in the long-term, once it escapes extinction.

On SIR epidemic models with generally distributed infectious periods: Number of secondary cases and probability of infection

Recently, Clancy [SIR epidemic models with general infectious period distribution, Statist. Prob. Lett. 85 (2014) 1–5] has shown how SIR epidemics in which individuals’ infection periods are not necessarily exponentially distributed may be modeled in terms of a piecewise-deterministic Markov process (PDMP). In this paper, we present a more detailed description of the underlying PDMP, from which we analyze the population transmission number and the infection probability of a certain susceptible individual.

Appropriateness of newborn screening for classic galactosaemia: a systematic review

Currently, there is no universal agreement on galactosaemia screening, fundamentally because of the risk-benefit uncertainties. We conducted two exhaustive systematic searches in the main electronic databases (PubMed, Embase, Cochrane, etc.) to recover relevant information about the disease and screening test/s in order to support decision making in Spain. All of the 45 studies identified that covered disease issues were retrospective case series or cross-sectional analysis (level-4 evidence). Studies consistently found that the majority of patients presented characteristic symptomatology before diagnosis. Long term disabilities were not significantly correlated with age of diagnosis, onset of dietary restriction or strict diet compliance. The five studies that provided accuracy data used different cut-off points and verification tests, and thus differed in their definitions of a positive case (level-3b evidence). The estimated sensitivity was 100 % and the specificity 99.9 %. The false-positive rate ranged from 0.0005 % to 0.25 %, and the PPV from 0 % to 64.3 %. The comparative clinical effectiveness in relation to not screening or implementation of other programs is unknown. In summary, existing evidence remains insufficient to establish the appropriateness of newborn screening for galactosaemia screening, although health benefits could be expected if early diagnosis and treatment is achieved. If screening is implemented in Spain, it would be important that a pilot programme be implemented to assess false positive rate and ensure that early diagnosis is not delayed.

Stochastic descriptors in an SIR epidemic model for heterogeneous individuals in small networks

We continue here the work initiated in [13], and analyse an SIR epidemic model for the spread of an epidemic among the members of a small population of N individuals, defined in terms of a continuous-time Markov chain X. We propose a structure by levels and sub-levels of the state space of the process X, and present two different orders, Orders A and B, for states within each sub-level, which are related to a matrix and a scalar formalism, respectively, when developing our analysis. Stochastic descriptors regarding the length and size of an outbreak, the maximum number of individuals simultaneously infected during an outbreak, the fate of a particular individual within the population, and the number of secondary cases caused by a certain individual until he recovers, are deeply analysed. Our approach is illustrated by carrying out a set of numerical results regarding the spread of the nosocomial pathogen Methicillin-resistant Staphylococcus Aureus among the patients within an intensive care unit. In this application, our interest is in analysing the effectiveness of control strategies (the isolation of the patient initiating the outbreak and the proper room configuration of the intensive care unit) that intrinsically introduce heterogeneities among the members of the population.

[Descemet's stripping automated endothelial keratoplasty (DEAEK). Systematic review of clinical-effectiveness and safety]

OBJECTIVE

To conduct a systematic review of the efficacy/effectiveness, safety and cost of Descemet's stripping automated endothelial keratoplasty (DSAEK) technique in patients with corneal endothelial failure.

METHODS

Comprehensive literature search conducted in the main biomedical databases from January-May 2012.

RESULTS

Following a critical perusal of the total of 485 abstracts retrieved, 16 case series and one economic evaluation study were included. Corrected distance visual acuity and uncorrected distance visual acuity improved after treatment with DSAEK, attaining values of 0.6 to 0.8 and 0.5 respectively. The degree of post-DSAEK astigmatism was not significant with respect to baseline values. The main complications were graft dislocation-detachment (1.5-23%), primary failure (0-12%) and endothelial rejection (0.8-8.5%).

CONCLUSIONS

In Fuchs' dystrophy and bullous keratopathy, data on the effectiveness of DSAEK indicate post-intervention improvement in uncorrected and corrected distance visual acuity. Astigmatism arising after DSAEK was not significant. The most significant post-DSAEK complications are linked to the viability of the graft, with the most frequent complications being dislocation-detachment and, to a lesser extent, endothelial rejection. The studies that assess DSAEK are case series, and for the most part retrospective. The quality of this type of studies is both low and limited.

Studying light propagation in self-assembled hybrid photonic-plasmonic crystals by fourier microscopy

Hybrid metallodielectric systems where dielectric components are combined with metals supporting surface plasmons are able to spatially redistribute the electromagnetic field intensity within its volume through hybrid photonic-plasmonic modes. While most of the work done recently in this kind of systems has been focused on the way such redistribution takes place and how light couples to or is emitted from such samples, the way light propagation takes place has not been studied in depth. Here we consider light propagation in hybrid systems fabricated by self-assembly methods measuring their equifrequency surfaces both in reflection and emission configurations. Comparing spectroscopic measurements with equifrequency surfaces provides a deeper insight into the way light propagates in these structures, showing the possibilities they may present for several applications.

Cell adhesion strength is controlled by intermolecular spacing of adhesion receptors

Spatial patterning of biochemical cues on the micro- and nanometer scale controls numerous cellular processes such as spreading, adhesion, migration, and proliferation. Using force microscopy we show that the lateral spacing of individual integrin receptor-ligand bonds determines the strength of cell adhesion. For spacings > or = 90 nm, focal contact formation was inhibited and the detachment forces as well as the stiffness of the cell body were significantly decreased compared to spacings < or = 50 nm. Analyzing cell detachment at the subcellular level revealed that rupture forces of focal contacts increase with loading rate as predicted by a theoretical model for adhesion clusters. Furthermore, we show that the weak link between the intra- and extracellular space is at the intracellular side of a focal contact. Our results show that cells can amplify small differences in adhesive cues to large differences in cell adhesion strength.

Induction of cell polarization and migration by a gradient of nanoscale variations in adhesive ligand spacing

Cell interactions with adhesive surfaces play a vital role in the regulation of cell proliferation, viability, and differentiation, and affect multiple biological processes. Since cell adhesion depends mainly on the nature and density of the adhesive ligand molecules, spatial molecular patterning, which enables the modulation of adhesion receptor clustering, might affect both the structural and the signaling activities of the adhesive interaction. We herein show that cells plated on surfaces that present a molecularly defined spacing gradient of an integrin RGD ligand can sense small but consistent differences in adhesive ligand spacing of about 1 nm across the cell diameter, which is approximately 61 mum when the spacing includes 70 nm. Consequently, these positional cues induce cell polarization and initiate cell migration and signaling. We propose that differential positional clustering of the integrin transmembrane receptors is used by cells for exploring and interpreting their environment, at high spatial sensitivity.

Cell adhesion and polarisation on molecularly defined spacing gradient surfaces of cyclic RGDfK peptide patches

In vivo cell migration and location are orchestrally guided by soluble and bound chemical gradients. Here, gradients of extracellular matrix molecules are formed synthetically by the combination of a surface nanopatterning technique called block copolymer nanolithography (BCN) and a biofunctionalisation technique. A modified substrate dip-coating process of BCN allows for the formation of precise molecular gradients of cyclic RGDfK peptide patches at interfaces, which are presented to cells for testing cell adhesion and polarisation. Surfaces formed by BCN consist of hexagonally ordered gold dot patterns with a gradient in particle spacing. Each dot serves as a chemical anchor for the binding of cyclic RGDfK peptides, which are specifically recognised by alpha(v)beta(3) integrins. Due to steric hindrance only up to one integrin binds to one functionalised gold dot which forms a peptide patch spacing. We demonstrate how cell morphology, adhesion area, actin and vinculin distribution as well as cell body polarisation are influenced by the peptide patch spacing gradient. As a consequence, these gradients of adhesive ligands induce cell orientation towards smaller particle spacing when the gradient strength is 15nm/mm at least. This implicates that an adherent cell's sensitivity to differentiate between ligand patch spacing is approximately 1nm across the cell body.

Isothiocyanate-functionalized RGD peptides for tailoring cell-adhesive surface patterns

With the advances made in surface patterning by micro- and nanotechnology, alternative methods to immobilize biomolecules for different purposes are highly desired. RGD peptides are commonly used to create cell-attractive surfaces for cell-biological and also medical applications. We have developed a fast, one-step method to bind RGD peptides covalently to surfaces by thiourea formation, which can be applied to structured and unstructured materials. RGD peptides were fused to an isothiocyanate anchor during synthesis and directly immobilized on amino-terminated surfaces. The spreading behavior of fibroblasts and the formation of focal contacts served to prove the applicability of the coupling method. Two different linear peptides and one cyclic peptide were compared. All the peptides induced spreading behavior and the formation of focal contacts in murine fibroblasts. Adhesion was specific as cells neither recognized the corresponding negative control peptides nor spread in the presence of soluble H-RGDS-OH peptide. We successfully applied our coupling method to functionalize surface patterns created by microcontact printing (microCP) and chemical etching. Cells recognize areas selectively coated with RGD-containing peptides, proliferate and maintain this preference during long-term cultivation. Our method significantly facilitates surface modification with any kind of peptide - even for the preparation of peptide-functionalized small surface areas.

Specific integrin labeling in living cells using functionalized nanocrystals

We present an integrin labeling method using functionalized quantum dots (QDs). Cyclic Arg-Gly-Asp (RGD) peptides and a biotin-streptavidin linkage are used to specifically couple individual QDs to integrins of living cells. The spacer distance between the RGD sequence and the QD surface is a crucial parameter to ensure specific binding to individual alpha(v)beta(3) integrins of osteoblast cells. Despite blinking, the position of single QDs is tracked with nanometer precision and localized diffusive behavior is observed. We show that blinking events do not prevent the acquisition of quantitative parameters from the QD trajectories.

Mimicking cellular environments by nanostructured soft interfaces

We present herein an innovative technique for decorating soft polymer surfaces with metallic nanostructures fabricated by diblock copolymer micelle nanolithography. Thus far, such nanolithography has been limited to plasma-resistant inorganic substrates such as glass. Our new development is based on the transfer of nanopatterns from glass to soft substrates. Special emphasis is given to hydrogel surfaces with respect to their properties for tailoring cell adhesion. Besides planar surfaces, periodic gold nanopatterns on curved surfaces have been fabricated, as demonstrated on the interior surface of a tubelike hydrogel, which potentially mimic situations of vessels in vivo.

Highly Efficient Biocatalytic Resolution ofcis- andtrans-3-Aminoindan-1-ol: Syntheses of Enantiopure Orthogonally Protectedcis- andtrans-Indane-1,3-diamine

The efficient chemoenzymatic synthesis of enantiopure 1,3-difunctionalized indane derivatives has been achieved. The corresponding cis and trans N-protected amino alcohols were successfully resolved by acetylation using lipase B, which is a biocatalyst isolated from Candida antarctica. All the possible isomers were obtained in very good chemical yields and ee values (>99 %). The utility of these compounds was subsequently shown by the preparation of orthogonally protected cis- and trans-indane-1,3-diamine using a Mitsunobu reaction. Both enantiomers of the trans isomer and a desymmetrized cis diastereomer were prepared in enantiopure form. Complete inversion of configuration during the Mitsunobu reaction was demonstrated by a combination of NMR techniques and molecular modeling. The utility and versatility of the strategy was also demonstrated by the selective deprotection of each nitrogen atom under mild reaction conditions.

Synthesis of (R)-3,4-diaminobutanoic acid by desymmetrization of dimethyl 3-(benzylamino)glutarate through enzymatic ammonolysis

Lipase B from Candida antarctica is shown to be a highly efficient catalyst for the desymmetrization of dimethyl 3-(benzylamino)glutarate (1) through aminolysis and ammonolysis reactions. Using this procedure, enantiopure monoamides are obtained in high yield. The synthetic value of these compounds is demonstrated by the preparation of an enantiopure nonnatural amino acid, i.e. (R)-3,4-diaminobutanoic acid [(+)-12].