Pathway-Dependent Co-Assembly of Elastin-Like Polypeptides

In natural systems, temperature-induced assembly of biomolecules can lead to the formation of distinct assembly states, created out of the same set of starting compounds, based on the heating trajectory followed. Until now it has been difficult to achieve similar behavior in synthetic polymer mixtures. Here, a novel pathway-dependent assembly based on stimulus-responsive polymers is shown. When a mixture of mono- and diblock copolymers, based on elastin-like polypeptides, is heated with a critical heating rate co-assembled particles are created that are monodisperse, stable, and have tunable hydrodynamic radii between 20 and 120 nm. Below this critical heating rate, the constituents separately form polymer assemblies. This process is kinetically driven and reversible in thermodynamically closed systems. Using the co-assembly pathway, fluorescent proteins and bioluminescent enzymes are encapsulated with high efficiency. Encapsulated cargo shows unperturbed function even after delivery into cells. The pathway-dependent co-assembly of elastin-like polypeptides is not only of fundamental interest from a materials science perspective, allowing the formation of multiple distinct assemblies from the same starting compounds, which can be interconverted by going back to the molecularly dissolved states. It also enables a versatile way for constructing highly effective vehicles for the cellular delivery of biomolecular cargo.

Illuminating the Impact of Submicron Particle Size and Surface Chemistry on Interfacial Position and Pickering Emulsion Type

Pickering emulsions are increasingly applied in the production of medicines, cosmetics, and in food technology. To apply Pickering emulsions in a rational manner it is insufficient to examine properties solely on a macroscopic scale, as this does not elucidate heterogeneities in contact angles (θ) of individual particles, which may have a profound impact on stability and microstructure. Here, we apply the super-resolution technique iPAINT to elucidate for the first time the microscopic origins of macroscopically observed emulsion phase inversions induced by a variation in particle size and aqueous phase pH. We find θ of single carboxyl polystyrene submicron particles (CPS) significantly decreases due to increasing aqueous phase pH and particle size, respectively. Our findings confirm that θ of submicron particles are both size- and pH-dependent. Interestingly, for CPS stabilized water-octanol emulsions, this enables tuning of emulsion type from water-in-oil to oil-in-water by adjustments in either particle size or pH.

Challenges, constraints and failures that are related to the posterior sagittal anorectoplasty approach to anorectal malformations in a low-resource context: An experience from a sudanese tertiary referral centre

BACKGROUND

Anorectal malformations (ARMs) in the sub-Saharan Africa are a common cause of neonatal referral for intestinal obstruction, and the posterior sagittal anorectoplasty (PSARP) approach is rapidly spreading. The small number of paediatric surgeons and the low-resource context limit children's access to care and constrain the quality of results. A retrospective, observational study has been done on a consecutive series of ARM cases admitted to a Sudanese tertiary paediatric surgical centre within the framework of a partnership between Italian and Sudanese academic institutions addressed to review and upgrade the standard of care of major congenital anomalies.

MATERIALS AND METHODS

The authors collected 94 ARM cases in a 3 years' period. Conditions on referral, operative procedures, post-operative course and follow-up were recorded and examined. Their correlations with complications and outcome were analysed.

RESULTS

The male/female ratio was 47/47. Eighty patients presented with an untreated ARM; 66 had a divided stoma and 14 had already a PSARP procedure, followed by a poor outcome or sequelae. In 25% of the cases, colostomy required re-doing. In 57 cases, a staged PSARP (primary or re-do) was done. Surgical-site infections occurred in nine patients. Some patients were lost to follow-up after preliminary colostomy. Post-operative dilatation programme suffered from the lack of systematic follow-up, and colostomy closure was possible in 46% of the cases due to problems in travelling and accessing hospital care. Anal stenosis was frequently observed among unfollowed patients.

CONCLUSION

Despite PSARP's widespread adoption in Africa, the risk of complications and failures is high. Primary management is often inappropriate, and a high rate of colostomy-related complications is observed. Poverty and lack of transportation reduce attendance to follow-up, hampering the final results. Investments in healthcare facilities and retention of trained health providers are needed to improve the standard of care.

Improving standard of pediatric surgical care in a low resource setting: the key role of academic partnership

Background

An epidemiological transition is interesting Sub-Saharan Africa increasing the burden of non-communicable diseases most of which are of surgical interest. Local resources are far from meeting needs and, considering that 50% of the population is less than 14 years of age, Pediatric surgical coverage is specially affected. Efforts are made to improve standards of care and to increase the number of Pediatric surgeons through short-term specialist surgical Missions, facilities supported by humanitarian organization, academic Partnership, training abroad of local surgeons. This study is a half term report about three-years Partnership between the University of Chieti- Pescara, Italy and the University of Gezira, Sudan to upgrade standard of care at the Gezira National Centre for Pediatric Surgery (GNCPS) of Wad Medani. Four surgical Teams per year visited GNCPS. The Program was financed by the Italian Agency for Development Cooperation.

Methods

The state of local infrastructure, current standard of care, analysis of caseload, surgical activity and results are reported. Methods utilized to assess local needs and to develop Partnership activities are described.

Results

Main surgical task of the visiting Team were advancements in Colorectal procedures, Epispadias/Exstrophy Complex management and Hypospadias surgery (20% of major surgical procedures at the GNCPS). Intensive care facilities and staff to assist more complex cases (i.e. neonates) are still defective. Proctoring, training on the job of junior surgeons, anaesthetists and nurses, collaboration in educational programs, advisorship in hospital management, clinical governance, maintenance of infrastructure together with training opportunities in Italy were included by the Program. Despite on-going efforts, actions have not yet been followed by the expected results. More investments are needed on Healthcare infrastructures to increase health workers motivation and prevent brain drain.

Conclusions

The key role that an Academic Partnership can play, acting through expatriated Teams working in the same constrained contest with the local workforce, must be emphasized. Besides clinical objectives, these types of Global Health Initiatives address improvement in management and clinical governance. The main obstacles to upgrade standard of care and level of surgery met by the Visiting Team are scarce investments on health infrastructure and a weak staff retention policy, reflecting in poor motivation and low performance.

Multivalent Patchy Colloids for Quantitative 3D Self-Assembly Studies

We report methods to synthesize sub-micron- and micron-sized patchy silica particles with fluorescently labeled hemispherical titania protrusions, as well as routes to efficiently characterize these particles and self-assemble these particles into non-close-packed structures. The synthesis methods expand upon earlier work in the literature, in which silica particles packed in a colloidal crystal were surface-patterned with a silane coupling agent. Here, hemispherical amorphous titania protrusions were successfully labeled with fluorescent dyes, allowing for imaging by confocal microscopy and super-resolution techniques. Confocal microscopy was exploited to experimentally determine the numbers of protrusions per particle over large numbers of particles for good statistical significance, and these distributions were compared to simulations predicting the number of patches as a function of core particle polydispersity and maximum separation between the particle surfaces. We self-assembled these patchy particles into open percolating gel networks by exploiting solvophobic attractions between the protrusions.

Super-resolution microscopy on single particles at fluid interfaces reveals their wetting properties and interfacial deformations

Solid particles adsorbed at fluid interfaces are crucial for the mechanical stability of Pickering emulsions. The key parameter which determines the kinetic and thermodynamic properties of these colloids is the particle contact angle, θ. Several methods have recently been developed to measure the contact angle of individual particles adsorbed at liquid-liquid interfaces, as morphological and chemical heterogeneities at the particle surface can significantly affect θ. However, none of these techniques enables the simultaneous visualization of the nanoparticles and the reconstruction of the fluid interface to which they are adsorbed, in situ. To tackle this challenge, we utilize a newly developed super-resolution microscopy method, called iPAINT, which exploits non-covalent and continuous labelling of interfaces with photo-activatable fluorescent probes. Herewith, we resolve with nanometer accuracy both the position of individual nanoparticles at a water-octanol interface and the location of the interface itself. First, we determine single particle contact angles for both hydrophobic and hydrophilic spherical colloids. These experiments reveal a non-negligible dependence of θ on particle size, from which we infer an effective line tension, τ. Next, we image elliptical particles at a water-decane interface, showing that the corresponding interfacial deformations can be clearly captured by iPAINT microscopy.

Painting Supramolecular Polymers in Organic Solvents by Super-resolution Microscopy

Despite the rapid development of complex functional supramolecular systems, visualization of these architectures under native conditions at high resolution has remained a challenging endeavor. Super-resolution microscopy was recently proposed as an effective tool to unveil one-dimensional nanoscale structures in aqueous media upon chemical functionalization with suitable fluorescent probes. Building upon our previous work, which enabled photoactivation localization microscopy in organic solvents, herein, we present the imaging of one-dimensional supramolecular polymers in their native environment by interface point accumulation for imaging in nanoscale topography (iPAINT). The noncovalent staining, typical of iPAINT, allows the investigation of supramolecular polymers' structure in situ without any chemical modification. The quasi-permanent adsorption of the dye to the polymer is exploited to identify block-like arrangements within supramolecular fibers, which were obtained upon mixing homopolymers that were prestained with different colors. The staining of the blocks, maintained by the lack of exchange of the dyes, permits the imaging of complex structures for multiple days. This study showcases the potential of PAINT-like strategies such as iPAINT to visualize multicomponent dynamic systems in their native environment with an easy, synthesis-free approach and high spatial resolution.

Supramolecular Block Copolymers under Thermodynamic Control

Supramolecular block copolymers are becoming attractive materials in nascent optoelectronic and catalytic technologies. However, their dynamic nature precludes the straightforward tuning and analysis of the polymer’s structure. Here we report the elucidation on the microstructure of triarylamine triamide-based supramolecular block copolymers through a comprehensive battery of spectroscopic, theoretical, and super-resolution microscopic techniques. Via spectroscopic analysis we demonstrate that the direct mixing of preassembled homopolymers and the copolymerization induced by slow cooling of monomers lead to the formation of the same copolymer’s architecture. The small but pronounced deviation of the experimental spectra from the linear combination of the homopolymers’ spectra hints at the formation of block copolymers. A mass balance model is introduced to further unravel the microstructure of the copolymers formed, and it confirms that stable multiblock supramolecular copolymers can be accessed from different routes. The multiblock structure of the supramolecular copolymers originates from the fine balance between favorable hydrogen-bonding interactions and a small mismatch penalty between two different monomers. Finally, we visualized the formation of the supramolecular block copolymers by adapting a recently developed super-resolution microscopy technique, interface point accumulation for imaging in nanoscale topography (iPAINT), for visualizing the architectures formed in organic media. Combining multiple techniques was crucial to unveil the microstructure of these complex dynamic supramolecular systems.

iPAINT: a general approach tailored to image the topology of interfaces with nanometer resolution

Understanding interfacial phenomena in soft materials such as wetting, colloidal stability, coalescence, and friction warrants non-invasive imaging with nanometer resolution. Super-resolution microscopy has emerged as an attractive method to visualize nanostructures labeled covalently with fluorescent tags, but this is not amenable to all interfaces. Inspired by PAINT we developed a simple and general strategy to overcome this limitation, which we coin 'iPAINT: interface Point Accumulation for Imaging in Nanoscale Topography'. It enables three-dimensional, sub-diffraction imaging of interfaces irrespective of their nature via reversible adsorption of polymer chains end-functionalized with photo-activatable moieties. We visualized model dispersions, emulsions, and foams with ∼20 nm and ∼3° accuracy demonstrating the general applicability of iPAINT to study solid/liquid, liquid/liquid and liquid/air interfaces. iPAINT thus broadens the scope of super-resolution microscopy paving the way for non-invasive, high-resolution imaging of complex soft materials.

Imaging Nanostructures by Single-Molecule Localization Microscopy in Organic Solvents

The introduction of super-resolution fluorescence microscopy (SRM) opened an unprecedented vista into nanoscopic length scales, unveiling a new degree of complexity in biological systems in aqueous environments. Regrettably, supramolecular chemistry and material science benefited far less from these recent developments. Here we expand the scope of SRM to photoactivated localization microscopy (PALM) imaging of synthetic nanostructures that are highly dynamic in organic solvents. Furthermore, we characterize the photophysical properties of commonly used photoactivatable dyes in a wide range of solvents, which is made possible by the addition of a tiny amount of an alcohol. As proof-of-principle, we use PALM to image silica beads with radii close to Abbe's diffraction limit. Individual nanoparticles are readily identified and reliably sized in multicolor mixtures of large and small beads. We further use SRM to visualize nm-thin yet μm-long dynamic, supramolecular polymers, which are among the most challenging molecular systems to image.

Ultrafast transient absorption of eumelanin suspensions: the role of inverse Raman scattering

An ultrafast investigation is carried out on synthetic eumelanin suspended either in water or in DMSO-methanol. Upon photoexcitation by visible femtosecond pulses, the transient absorption (TA) dynamics of the suspensions are probed in a broad visible spectral range, showing clear nonlinearities. The latter arise from pump-probe interactions that induce the inverse Raman scattering (IRS) effect. We show how eumelanin TA dynamics are modified in proximity of the solvent Stokes and anti-Stokes scattering peaks, demonstrating that IRS affects the sign of TA but not the relaxation times. We compare the results obtained in both suspensions, unveiling the role of the surrounding environment. Eventually, the intrinsic response of synthetic eumelanin to ultrafast photoexcitation is evaluated.

A multidisciplinary study of the extracutaneous pigment system of European sea bass (Dicentrarchus labrax L.). A possible relationship between kidney disease and dopa oxidase activity level

Infectious diseases and breeding conditions can influence fish health status. Furthermore it is well known that human and animal health are strongly correlated. In lower vertebrates melano-macrophage centres, clusters of pigment-containing cells forming the extracutaneous pigment system, are widespread in the stroma of the haemopoietic tissue, mainly in kidney and spleen. In fishes, melano-macrophage centres play an important role in the immune response against antigenic stimulants and pathogens. Hence, they are employed as biomarker of fish health status. We have investigated this cell system in the European sea bass (Dicentrarchus labrax L.) following the enzyme activities involved in melanin biosynthesis. We have found a possible relationship between kidney disease of farmed fishes and dopa oxidase activity level, suggesting it as an indicator of kidney disease. Moreover variations of dopa oxidase activity in extracutaneous pigment system have been observed with respect to environmental temperature. At last, for the first time, using femtosecond transient absorption spectroscopy (Femto-TA), we pointed out that pigment-containing cells of fish kidney tissue present melanin pigments.

Prevalence of xerophthalmia among children in Beheira governorate, Egypt

A survey was conducted on a sample representative of the entire Beheira governorate to identify high-risk areas of vitamin A deficiency [VAD] and assess xerophthalmia prevalence. The study also tested the reliability of a household cluster survey for assessing xerophthalmia prevalence. A trained ophthalmologist examined 10, 664 children. The results showed that VAD was present in the region, but did not appear to be a public health problem. Ocular signs of VAD were more prevalent among older children, suggesting an improvement in socioeconomic conditions and health care over the past few years. The household cluster survey appeared to be a reliable method for assessing xerophthalmia prevalence in the region

Prevalence of xerophthalmia among children in Beheira governorate, Egypt

A survey was conducted on a sample representative of the entire Beheira governorate to identify high-risk areas of vitamin A deficiency (VAD) and assess xerophthalmia prevalence. The study also tested the reliability of a household cluster survey for assessing xerophthalmia prevalence. A trained ophthalmologist examined 10,664 children. The results showed that VAD was present in the region, but did not appear to be a public health problem. Ocular signs of VAD were more prevalent among older children, suggesting an improvement in socioeconomic conditions and health care over the past few years. The household cluster survey appeared to be a reliable method for assessing xerophthalmia prevalence in the region.

An analysis of individual, household, and environmental risk factors for intestinal helminth infection among children in Qena Governorate, Upper Egypt

During 1994 a cross-sectional survey was carried out on a sample representative of the population in Qena Governorate, Upper Egypt, to investigate the relationship between intestinal helminthic infection among children and a wide range of variables (demographic, behavioural, cultural, socioeconomic, and environmental). Data were collected by direct observation and by administering a questionnaire to mothers in charge of the household in a sample of 768 households representative of the entire population in the governorate. A stool sample survey was conducted at the same time on all children 2-12 years of age living in the selected households (n = 2657). Diagnosis of intestinal helminths was made on the basis of the Kato-Katz thick-smear technique. After univariate analyses, conducted to define associations among individual, familial, and community variables and prevalence of infection, the relevant variables were included in a multivariate logistic model to assess the importance of each factor as an independent determinant of infection. Several factors were independently associated with increased risk of intestinal helminth infection. In particular, the age of the child (between 4 and 5 years) (individual), the age of marriage for the mother (cultural), type of garbage disposal (household), and type of settlement (environmental) gave the highest predictive value for infection. The present results are consistent with those of former studies and highlight the importance of a multisectorial approach in the control of intestinal helminth infection.

Design, testing, and results of an outcomes-managed approach to patients requiring prolonged mechanical ventilation

BACKGROUND: Outcomes management that uses critical pathways may decrease costs while improving outcomes for patients who require prolonged mechanical ventilation. OBJECTIVE: To study the efficacy of an outcomes-managed approach to weaning patients from prolonged (more than 3 days) mechanical ventilation. METHODS: A method of multidisciplinary care delivery was designed that included an outcomes manager, a care pathway for patients receiving mechanical ventilation, and weaning protocols. Data collection consisted of three parts: a retrospective review of 124 patients who required prolonged ventilation during a 1-year period before implementation of the care model, a 6-month prospective study in which 91 patients were alternately assigned by month to an outcomes-managed approach or a non-outcomes-managed approach, and a 6-month prospective study of 90 patients in which an outcomes-managed approach without alternate-month assignment was used. RESULTS: Outcomes management had no significant effect on total duration of mechanical ventilation or length of stay in the hospital, days of mechanical ventilation without tracheostomy, days of mechanical ventilation with tracheostomy, or outcome (weaned, withdrawal from mechanical ventilation, death, or transfer without weaning). However, duration of mechanical ventilation was 1.3 days shorter, length of stay in the hospital was 2.1 days shorter, and the cost per case was $ 3341 less for patients in the outcomes-managed group than for patients in the non-outcomes-managed group. CONCLUSION: Outcomes-managed care did not have a significant effect on duration of ventilation, length of stay in the hospital, or outcome in patients receiving long-term mechanical ventilation.

Design, testing, and results of an outcomes-managed approach to patients requiring prolonged mechanical ventilation

BACKGROUND

Outcomes management that uses critical pathways may decrease costs while improving outcomes for patients who require prolonged mechanical ventilation.

OBJECTIVE

To study the efficacy of an outcomes-managed approach to weaning patients from prolonged (more than 3 days) mechanical ventilation.

METHODS

A method of multidisciplinary care delivery was designed that included an outcomes manager, a care pathway for patients receiving mechanical ventilation, and weaning protocols. Data collection consisted of three parts: a retrospective review of 124 patients who required prolonged ventilation during a 1-year period before implementation of the care model, a 6-month prospective study in which 91 patients were alternately assigned by month to an outcomes-managed approach or a non-outcomes-managed approach, and a 6-month prospective study of 90 patients in which an outcomes-managed approach without alternate-month assignment was used.

RESULTS

Outcomes management had no significant effect on total duration of mechanical ventilation or length of stay in the hospital, days of mechanical ventilation without tracheostomy, days of mechanical ventilation with tracheostomy, or outcome (weaned, withdrawal from mechanical ventilation, death, or transfer without weaning). However, duration of mechanical ventilation was 1.3 days shorter, length of stay in the hospital was 2.1 days shorter, and the cost per case was $ 3341 less for patients in the outcomes-managed group than for patients in the non-outcomes-managed group.

CONCLUSION

Outcomes-managed care did not have a significant effect on duration of ventilation, length of stay in the hospital, or outcome in patients receiving long-term mechanical ventilation.

Antibacterial drugs in Crohn's disease

The evidence of a beneficial role of antibacterial drugs in Crohn's disease is largely empirical. Data accumulate to show that these drugs may well be used as an adjunctive therapy to oral anti-inflammatory drugs. Circumstantial evidence has also been provided that antibacterial drugs are effective in relieving symptoms related to bacterial overgrowth and when used for specific indications such as perianal lesions.