Group versus one-to-one multi-component lifestyle interventions for weight management: a systematic review and meta-analysis of randomised controlled trials.

BACKGROUND: Multi-component lifestyle interventions that incorporate diet, physical activity and behaviour change are effective for weight management. However, it is not clear whether delivery in a group or one-to-one format influences weight loss efficacy. The present study aimed to systematically review the evidence of the effectiveness of group compared to one-to-one multi-component lifestyle interventions for weight management. METHODS: MEDLINE, EMBASE, CINAHL, CENTRAL and ISRCTN databases were searched from inception up to February 2020 for randomised controlled trials comparing group versus one-to-one multi-component lifestyle interventions for weight loss in adults with a body mass index ≥ 25 kg m-2 . The primary outcome was weight loss (kg) at 12 months and the secondary outcome was attainment of ≥5% weight loss at 12 months. Risk of bias was assessed using the Cochrane Risk of Bias Tool. Meta-analysis used random effects and estimated risk ratios and continuous inverse variance methods. Heterogeneity was investigated using I2 statistics and sensitivity analyses. RESULTS: Seven randomised controlled trials with 2576 participants were included. Group interventions were favoured over one-to-one interventions for weight loss at 12 months (-1.9 kg, 95% confidence interval = -1.3 to -2.6; I2  = 99%). Participants of group interventions were more likely to attain ≥5% weight loss at 12 months relative to one-to-one interventions (relative risk = 1.58, 95% confidence interval = 1.25-2.00; I2  = 60%). CONCLUSIONS: Group multi-component lifestyle interventions are superior for weight loss compared to one-to-one interventions with respect to adult weight management. Further research is required to determine whether specific components of group interventions can explain the superiority of weight loss outcomes in group interventions.

Injectable hydrogels with high fixed charge density and swelling pressure for nucleus pulposus repair: biomimetic glycosaminoglycan analogues.

The load-bearing biomechanical role of the intervertebral disc is governed by the composition and organization of its major macromolecular components, collagen and aggrecan. The major function of aggrecan is to maintain tissue hydration, and hence disc height, under the high loads imposed by muscle activity and body weight. Key to this role is the high negative fixed charge of its glycosaminoglycan side chains, which impart a high osmotic pressure to the tissue, thus regulating and maintaining tissue hydration and hence disc height under load. In degenerate discs, aggrecan degrades and is lost from the disc, particularly centrally from the nucleus pulposus. This loss of fixed charge results in reduced hydration and loss of disc height; such changes are closely associated with low back pain. The present authors developed biomimetic glycosaminoglycan analogues based on sulphonate-containing polymers. These biomimetics are deliverable via injection into the disc where they polymerize in situ, forming a non-degradable, nuclear "implant" aimed at restoring disc height to degenerate discs, thereby relieving back pain. In vitro, these glycosaminoglycan analogues possess appropriate fixed charge density, hydration and osmotic responsiveness, thereby displaying the capacity to restore disc height and function. Preliminary biomechanical tests using a degenerate explant model showed that the implant adapts to the space into which it is injected and restores stiffness. These hydrogels mimic the role taken by glycosaminoglycans in vivo and, unlike other hydrogels, provide an intrinsic swelling pressure, which can maintain disc hydration and height under the high and variable compressive loads encountered in vivo.

The bioethical experiences of student dietitians on their final clinical placement.

BACKGROUND: Dietetic students are exposed to bioethical dilemmas on clinical placements; however, the nature of these situations has not been investigated. The present study aimed to analyse students' reports of incidents and their associated personal development plans (PDP) to assess the type of ethical incidents faced and how they cope with them. METHODS: Final-year dietetic students were recruited via an announcement in class. The students' PDPs were analysed using thematic analysis to identify the type of ethical issues faced and how they felt about them. The 500-word PDPs were submitted after the final placement. RESULTS: Thirteen (13/26) students identified 'ethics' as a learning need and most of these incidents were related to enteral feeding (10/13). Ethical issues identified related to nonmaleficence; best interest; consent and capacity; truth telling and integrity; autonomy and substituted decision-making; futile treatment; beneficence and confidentially. The themes for how the students coped included being unsure; lack of confidence or knowledge with ethics and/or with communication; lack of experience; unease/concern about shared decision-making; and their own role in the situation. CONCLUSIONS: Student dietitians are exposed to a wide range of complex ethical clinical situations, with those related to enteral feeding being the most common. Students felt unsure of what to do and lacked confidence, which resulted in unease and concern; however, students appeared to have some ethical sensitivity. Communication problems with the multidisciplinary team or families were a common theme. Clinical educators need to support students in these situations and act as role models.

Wide shear zones and the spot model: implications from the split-bottom geometry.

The spot model has been developed by Bazant and co-workers to describe quasistatic granular flows. It assumes that granular flow is caused by the opposing flow of so-called spots of excess free volume, with spots moving along the slip lines of Mohr-Coulomb plasticity. The model is two-dimensional and has been successfully applied to a number of different geometries. In this paper we investigate whether the spot model in its simplest form can describe the wide shear zones observed in experiments and simulations of a Couette cell with split bottom.We give a general argument that is independent of the particular description of the stresses, but which shows that the present formulation of the spot model in which diffusion and drift terms are postulated to balance on length scales of order of the spot diameter, i.e. of order 3-5 grain diameters, is difficult to reconcile with the observed wide shear zones. We also discuss the implications for the spot model of co-axiality of the stress and strain rate tensors found in these wide shear flows, and point to possible extensions of the model that might allow one to account for the existence of wide shear zones.

Mathematical modelling of corneal swelling.

This paper presents a differential model of the corneal transport system capable of modelling thickness changes in response to osmotic perturbations applied to either limiting membrane. The work is directed towards understanding corneal behaviour in vivo. The model considers the coupled viscous flows within the corneal stroma and across the epithelial and endothelial membranes. The flows within the stroma are established based on transport theory in porous media, while the flows across the membranes are described using the phenomenological equations of irreversible thermodynamics. The ability of the numerical model to reproduce corneal thickness changes in response to endothelial perturbations was tested against available experimental data. The sensitivity of the model to changes in stromal and membrane transport coefficients was examined.

Chaos-induced pulse trains in the ionization of hydrogen.

We predict that a hydrogen atom in parallel electric and magnetic fields, excited by a short laser pulse to an energy above the classical saddle, ionizes via a train of electron pulses. These pulses are a consequence of classical chaos induced by the magnetic field. We connect the structure of this pulse train (e.g., pulse size and spacing) to fractal structure in the classical dynamics. This structure displays a weak self-similarity, which we call "epistrophic self-similarity." We demonstrate how this self-similarity is reflected in the pulse train.

A model for the preliminary biological screening of potential keratoprosthetic biomaterials.

A series of in vitro screening assays for the preliminary selection of biomaterials for use in the fabrication of artificial corneas (keratoprostheses) (KPros) have been investigated. These screening assays assessed the initial binding of inflammatory and cell adhesive proteins, activation of inflammatory proteins, adhesion of keratocytes, epithelial cells and macrophages and the production of inflammatory cytokines by keratocytes contacting biomaterials. Central optic biomaterials were selected on the basis of low-inflammatory and cell adhesion potential. Peripheral skirt materials were selected on the basis of low-inflammatory potential but good cell adhesion to anchor the implant within the host cornea. Green fluorescent protein (GFP) gene transfer was used in a novel context to investigate cell invasion in the absence of external staining techniques. Confocal laser scanning microscopy and scanning electron microscopy were used to investigate GFP positive keratocyte invasion of porous materials. The results of in vitro assays were compared to a corneal organ culture system in which the biomaterials were assessed within a stromal environment. A range of polyurethane-based interpenetrating polymers with a range of water contents were screened. All materials showed low-inflammatory potential. A reduction in biomaterial water content induced an increase in complement C3 and fibronectin binding and in cell adhesion to materials, whilst differences in co-monomer formulation had little impact. The screening methods used in the current study provide a suitable preliminary assessment regime for the in vitro evaluation of potential KPro materials.

Geometry and topology of escape. I. Epistrophes.

We consider a dynamical system given by an area-preserving map on a two-dimensional phase plane and consider a one-dimensional line of initial conditions within this plane. We record the number of iterates it takes a trajectory to escape from a bounded region of the plane as a function along the line of initial conditions, forming an "escape-time plot." For a chaotic system, this plot is in general not a smooth function, but rather has many singularities at which the escape time is infinite; these singularities form a complicated fractal set. In this article we prove the existence of regular repeated sequences, called "epistrophes," which occur at all levels of resolution within the escape-time plot. (The word "epistrophe" comes from rhetoric and means "a repeated ending following a variable beginning.") The epistrophes give the escape-time plot a certain self-similarity, called "epistrophic" self-similarity, which need not imply either strict or asymptotic self-similarity.

Polymers for biodegradable medical devices XI. Microencapsulation studies: characterization of hydrocortisone-loaded poly-hydroxybutyrate-hydroxyvalerate microspheres.

Hydrocortisone-loaded monolithic microspheres were prepared, using a single emulsion solvent evaporation process, from a range of poly-beta-hydroxybutyrate-hydroxyvalerate copolymers in which both molecular weight and hydroxyvalerate content were varied. Many similarities were observed in the effects of process parameters and co-polymer composition on the morphologies of the microspheres, and the morphologies of microcapsules prepared (and previously reported) by a double emulsion process. The yields of the single emulsion process were generally superior to those of the double emulsion process, although these were adversely affected by hydrocortisone incorporation as the molecular weight of the copolymer was reduced. The predominant effect of hydrocortisone incorporation was on polymer morphology, characterized by the appearance of small surface pores; an effect which increased with increasing drug loading. Changes in polymer molecular weight, copolymer composition and process temperature, together with the incorporation of polycaprolactone in the form of a solvent blend, enabled microspheres with a range of morphologies to be produced providing the potential for control of drug release.

Responsive hydrophobically associating polymers: a review of structure and properties.

Responsive hydrophobically associating polymers can in many ways be considered to be analogous to proteins in their ability to form compact molecules with a defined secondary structure, and hence, functionality. These molecules are characterized by the presence of alternating charged and hydrophobic groups. The balance between charge repulsion and hydrophobic interactions is sensitive to environmental pH and therefore changes in pH produce controllable conformational changes. The change from a charged extended chain to a collapsed uncharged coil structure is sometimes referred to as hypercoiling behaviour and enables the polymer to act as a simple switch between an 'on' and 'off' state. The purpose of this review is to illustrate the structure and behaviour of polymers that exhibit hypercoiling behaviour and to highlight their potential pharmaceutical applications, which in terms of drug delivery is likely to be related to their surface behaviour and solubilizing activity.

The ex vivo wettability of soft contact lenses.

PURPOSE: To investigate the ex vivo wettability of Etafilcon A contact lenses over an eight hour period of wear and observe the influence of surfactant pre-treatment. METHODS: Etafilcon A hydrogel lenses, comprising poly[2-hydroxyethyl methacrylate-co-methacrylic acid] and 58% water, were soaked for 12 hours in either 0.9% saline (control) or a 1% aqueous solution of poloxamine 1107 (treated). The advancing and receding contact angles were subsequently determined ex vivo after various periods of wear in six adapted contact lens wearers using a single-blind, randomised protocol. Contact angles were measured with a dynamic contact angle tensiometer, using the Wilhelmy plate technique. Patient comfort scores were recorded and the static surface tensions of the probe fluids assessed. RESULTS: Control lenses exhibited no change in wetting angles over time, indicating a lack of surface modification by components within the tear film. Treated lenses exhibited a significantly reduced advancing angle (p < 0.001) and hysteresis angle (p < 0.001) when compared with control lenses. In addition, treated lenses were consistently rated as being more comfortable than control lenses (p = 0.04). CONCLUSIONS: This study has shown clearly that new Etafilcon A lenses do not exhibit significant changes in wettability during the initial four hour wearing period. Pre-treatment of such lenses with a polymeric surfactant results in wetting of the lenses due to the adsorption of surfactant. The surfactant is retained by the lens for at least eight hours of wear, resulting in significant improvements in subjective comfort, especially over the first 30 minutes of wear.

An in vivo comparison of the kinetics of protein and lipid deposition on group II and group IV frequent-replacement contact lenses.

PURPOSE: To investigate the degree and rate of deposition of protein and lipid on FDA group II and group IV contact lens materials over a period of up to 28 days of wear. METHODS: Twenty-two subjects wore a group IV lens (Acuvue) and a group II lens (Soflens 66) in a randomized, cross-over study. The lenses were randomly worn for periods between 1 and 28 days and then collected for laboratory-based deposition analysis. RESULTS: The group II lenses revealed an increased degree of lipoidal spoilage (p < 0.0001) and the group IV lenses exhibited increased protein spoilage (p < 0.0001). Surface protein for both materials reached a maximum after 1 day and did not increase over the 4-week wearing period (p = NS). Total protein for group IV lenses reached a maximum between 1 and 7 days and then reached a plateau, with no further increase occurring (p = NS), whereas total protein accumulation on the group II lens continued to increase across all time periods (p < 0.05). Lipid deposition on the group IV lens was maximal after 1 day and increased no further (p = NS), whereas lipid deposition on the group II material monotonously increased and progressively built-up over the 4 weeks of wear (p < 0.0001). CONCLUSIONS: The kinetics of contact lens deposition is mediated by the chemical structure of the contact lens material under consideration. Protein deposition occurs rapidly with group IV materials before reaching a maximum, whereas N-vinyl pyrrolidone-containing group II materials progressively accumulate protein and lipid deposits, with no plateau occurring.

Examination of particulate macroporous hydrogels in an extracorporeal rat haemoperfusion model.

A series of macroporous hydrogels has been synthesized, selected from a range of such materials in which the presence of functional groups has been shown to produce sorbent properties with respect to molecules having clinical significance in the field of liver support. The use of freeze thaw polymerization, together with inverse suspension polymerization in hexane, or in brine, enables macroporous beads ranging in size from 150 to 2000 microm, to be prepared from functional monomers exhibiting a range of chemical functionalities and aqueous solubilities. In order to investigate the behaviour of these rigid porous hydrophilic substrates in haemoperfusion, a rat model was used to explore various aspects of whole blood response. The materials were incorporated into an extracorporeal circuit linking the right carotid artery and left jugular vein of male Sprague-Dawley rats. Erythrocyte, leucocyte and platelet levels were monitored over a 240 min haemoperfusion period. The most significant observation is that, apart from the strongly acidic polyacrylic acid substrate. matrix chemistry has relatively little effect on leucocyte or platelet response. The most important factors appear to be surface area, pore size and surface rugosity, which do produce measurable, but not dramatic differences. This is encouraging for future work, since these variables may be manipulated by polymerization conditions.

Influence of contact lens material surface characteristics and replacement frequency on protein and lipid deposition.

The aim of the study was to quantify the influence of both contact lens material and replacement frequency on protein and lipid deposition. The following hypotheses were tested: (1) both protein and lipid interaction with contact lenses are material-dependent, and (2) the key factors are the material ionicity for the protein deposition and the material chemical composition for the lipid deposition. Three high water content contact lens materials were tested: netrafilcon A (FDA group II, Gentle Touch), etafilcon A (FDA group IV, Acuvue), and vifilcon A (FDA group IV, Focus). Contact lens spoilation was analyzed using ultraviolet spectroscopy and fluorescence spectrophotometry. The results showed that (1) significantly more proteins were deposited on the ionic materials than on the nonionic materials, and that among the ionic materials, the higher the ionicity, the higher the level of protein deposition; (2) there were significantly more surface proteins on the ionic materials after 3 months than after 1 month of wear, but no difference over time was demonstrated for the nonionic materials; and (3) significantly more lipids were deposited onto the surface of vifilcon A than etafilcon A or netrafilcon A, and the presence of vinylpyrrolidone in the vifilcon A formulation was thought to be the cause of increased deposition. The protein and lipid interactions with contact lenses were found to be material- and time-dependent. Protein attraction was found to be related to the material ionicity. The presence of vinylpyrrolidone was a key factor in the attraction of lipids.

Lipid and protein deposition of N-vinyl pyrrolidone-containing group II and group IV frequent replacement contact lenses.

PURPOSE: The purpose of this study was to investigate the degree of protein and lipid deposition that occurs on N-vinyl-2-pyrrolidone (NVP) containing group II (non-ionic, high water content) and NVP containing group IV (ionic, high water content) frequent replacement hydrogel contact lens materials. METHODS: Twenty subjects were fitted with Group II (Vasurfilcon A) and Group IV (Vifilcon A) contact lenses, which were replaced monthly. The lenses were worn as a contralateral pair for 3 consecutive monthly periods. At the end of each monthly period, the lenses were collected for analysis of protein and lipid deposits. Protein deposition (following extraction) was examined by transmission UV and lipoidal deposition was examined using fluorescence spectrophotofluorimetry. RESULTS: There was a significant difference in the lipid and protein deposition profiles between the two materials. The Group II lens deposited approximately 2x more lipid (38 versus 73 fluorescence units; P < 0.0001) and the Group IV lens deposited approximately 17x more protein (488 micrograms versus 28 micrograms; P < 0.0001). Whilst the mean results across months were not significantly different for either protein or lipid (P = NS), the results revealed significant inter- and intra-subject variation. CONCLUSIONS: Protein deposition was predominantly controlled by the ionic charge of the lens materials, whereas the lipid deposition was predominantly determined by the NVP content. This study demonstrates that inter-subject variation and material characteristics significantly influence the deposition profile of hydrogel contact lens materials.

Spoilation and clinical performance of monthly vs. three monthly Group II disposable contact lenses.

Twelve subjects were fitted with a high water content, nonionic contact lens (Pilkington Barnes-Hind "Precision UV"), which was either replaced every month for 3 months or worn for 3 consecutive months before replacement occurred. Visual quality, high and low contrast acuity, and comfort were unaltered with either replacement schedule, but overall satisfaction was significantly greater with the shorter replacement schedule (p = 0.04). Front surface wettability revealed a large amount of intersubject variability and was reduced at the 3-month visit with the longer replacement period lenses (p = 0.003). Visible deposits also increased with longer replacement times (p < 0.05). Laboratory-based analytical results showed that both gross lipid and gross extractable protein significantly increased in the 3-month lenses compared with the 1-month lenses, with 44% less lipid accumulation and 60% less protein deposition occurring with the shorter replacement time. The results support the replacement of high water content lenses on a monthly basis.