Optically transparent dense colloidal gels

Traditionally it has been difficult to study the porous structure of dense colloidal gels and (macro) molecular transport through them simply because of the difference in refractive index between the colloid material and the continuous fluid phase surrounding it, rendering the samples opaque even at low colloidal volume fractions. Here, we demonstrate a novel colloidal gel that can be refractive index-matched in aqueous solutions owing to the low refractive index of fluorinated latex (FL)-particles (n = 1.37). Synthesizing them from heptafluorobutyl methacrylate using emulsion polymerization, we demonstrate that they can be functionalized with short DNA sequences via a dense brush-layer of polystyrene-b-poly(ethylene oxide) block-copolymers (PS-PEO). The block-copolymer, holding an azide group at the free PEO end, was grafted to the latex particle utilizing a swelling-deswelling method. Subsequently, DNA was covalently attached to the azide-end of the block copolymer via a strain-promoted alkyne-azide click reaction. For comparison, we present a structural study of single gels made of FL-particles only and composite gels made of a percolating FL-colloid gel coated with polystyrene (PS) colloids. Further we demonstrate that the diffusivity of tracer colloids dispersed deep inside a refractive index matched FL-colloidal gel can be measured as function of the local confinement using Dynamic Differential Microscopy (DDM).

Serum vitamin D levels in Indian patients with retinal venous occlusions

Purpose

To estimate serum vitamin D (25 OH D) level in patients of retinal vein occlusion (RVO) and compare it with age-matched controls.

Methods and material

Forty patients above 18 years of age with retinal vein occlusion and forty age-matched controls underwent serum vitamin D (Vit D) level estimation using a standard protocol. Student’s t test was used to analyse differences between the mean of two groups.

Results

The mean age in RVO and control group was 60.25 and 60.73 years respectively. The mean (±SD) level of vitamin D in RVO patients was 13.68 (±4.58) ng/mL (range 5.5–24.8), and the 95% CI of mean was 12.21–15.14 with SD 4.58 while in control group it was 23.03 (±2.89) ng/ml (range 18.4–30.1) with 95% CI of mean being 22.11–23.96 with SD 2.89 (p value of <0.005). While comparing the level of Vitamin D based on type of occlusion the mean level of Vit D in CRVO patients was 15.36 (SD 5.30) and in BRVO it was 12.77 (SD 3.96) which was statistically not significant (p = 0.08). The odds ratio calculated for RVO cases versus controls was 133.33 which was statistically significant (P < 0.05).

Conclusions

There is a paucity of published literature on level of Vit D in RVO. This study shows significantly lower levels of serum vitamin D in Indian patients with retinal vein occlusion as compared to age matched controls. Establishment of this correlation has possible implications for prophylaxis or treatment of RVOs.

Universal institutional delivery among mothers in a remote mountain district of Nepal: what are the challenges?

Setting: Eight village development committees of Mugu District, a remote mountainous district of Nepal that has poor maternal health indicators. Objectives: 1) To assess the proportion of mothers who delivered in health facilities (institutional delivery); 2) among mothers who delivered at home, to understand their reasons for doing so; and 3) among mothers who delivered in health facilities, to understand their challenges. Design: Cross-sectional study involving semi-structured interviews with mothers conducted in 2015. Results: Of 275 mothers, 97 (35%) had an institutional delivery. Multivariate logistic regression analysis showed that women who resided within 1 h distance from the birthing centre, had adequate mass media exposure or had only one child were more likely to deliver in hospital. Reasons for non-institutional delivery (n = 178) were related to geographical access (49%), personal preferences (18%) and perceived poor quality care (4%). Mothers who accessed institutional delivery (n = 97) also reported difficulties related to travel (60%), costs (28%), dysfunctional health system (18%) and unfriendly attitudes of the health-care providers (7%). Conclusion: To improve access to institutional delivery, the government should establish a 24/7 emergency ambulance network, including air ambulance. Health system issues, including unfriendly staff attitudes, urgently need to be addressed to gain the trust of the mothers.

Seasonal immunohistochemical reactivity of S-100 and α-smooth muscle actin proteins in the epididymis of dromedary camel, Camelus dromedarius

The S-100 and alpha smooth muscle actin (α-SMA) proteins have been localised in epididymal tissue of several mammalian species, but there have been no data for a seasonal work in camel. The aim of this study was to investigate the immunoreactivities of S-100 and α-SMA proteins in the epididymis of dromedary camel during breeding and nonbreeding seasons. The immunopositive signals for both proteins were observed in different regions of camel epididymis. S-100-immunopositive signals were noted in both the epididymal epithelium and the intertubular connective tissue, while α-SMA signals were confined to the intertubular connective tissue, especially in the peritubular smooth muscle coat and the blood vessels. This study showed an increase in the intensity of S-100 and α-SMA immunoreactions during the breeding season in different regions of camel epididymis than that seen in the nonbreeding season. In conclusion, epididymis might be considered as a source of S-100 and α-SMA proteins in the camel and the secretion of these proteins showed distinct seasonal variations. Further, S-100 and α-SMA may affect the structural and physiological states of the epididymal duct.

Spectrum of ocular diseases in patients attending eye camps in Andaman and Nicobar

BACKGROUND

Andaman and Nicobar Island is a group of 572 islands with a population of 3,80,500. The only service hospital as well as govt hospital is situated at its capital, Portblair. The islands are interconnected only by sea passage and to reach the capital by this route it sometimes takes two days.

METHODS

The objective of this study is to assess the spectrum of different ocular diseases in remote islands of Andaman and Nicobar. Author had conducted various camps on these remote islands as a community outreach programme over two years.

RESULTS

Top eye diseases found were refractive error (35%), cataract (22%), conjunctival infammatory disease (15%), glaucoma cases (07%), pterygium (07%), NLDO (02%) and uveitis (02%). Out of total 132 cataract patients screened, 32 patients (approximately 24%) were operated in INHS Dhanvantari at free of cost with help of NPCB (National Programme for Control of Blindness).

CONCLUSION

This was the first kind of study conducted on these remote islands to know the prevalence of different ocular diseases. The important point to be seen in this study was unawareness of glaucoma and cataract load. No optometrist was posted in the PHCs to provide primary eye care like prescribing glasses, which is also a big concern.

Designing disordered materials using DNA-coated colloids of bacteriophage fd and gold

DNA has emerged as an exciting binding agent for programmable colloidal self-assembly. Its popularity derives from its unique properties: it provides highly specific short-ranged interactions and at the same time it acts as a steric stabilizer against non-specific van der Waals and Coulomb interactions. Because complementary DNA strands are linked only via hydrogen bonds, DNA-mediated binding is thermally reversible: it provides an effective attraction that can be switched off by raising the temperature only by a few degrees. In this article we introduce a new binary system made of DNA-functionalized filamentous fd viruses of ∼880 nm length with an aspect ratio of ∼100, and 50 nm gold nanoparticles (gold NPs) coated with the complementary DNA strands. When quenching mixtures below the melt temperature Tm, at which the attraction is switched on, we observe aggregation. Conversely, above Tm the system melts into a homogenous particulate 'gas'. We present the aggregation behavior of three different gold NP to virus ratios and compare them to a gel made solely of gold NPs. In particular, we have investigated the aggregate structures as a function of cooling rate and determine how they evolve as function of time for given quench depths, employing fluorescence microscopy. Structural information was extracted in the form of an effective structure factor and chord length distributions. Rapid cooling rates lead to open aggregates, while slower controlled cooling rates closer to equilibrium DNA hybridization lead to more fine-stranded gels. Despite the different structures we find that for both cooling rates the quench into the two-phase region leads to initial spinodal decomposition, which becomes arrested. Surprisingly, although the fine-stranded gel is disordered, the overall structure and the corresponding length scale distributions in the system are remarkably reproducible. Such highly porous systems can be developed into new functional materials.

An 'omics' approach towards the characterisation of laboratory scale anaerobic digesters treating municipal sewage sludge

In this study, laboratory scale digesters were operated to simulate potential shocks to the Anaerobic Digestion (AD) process at a 350 ML/day wastewater treatment plant. The shocks included high (42 °C) and low (32 °C) temperature (either side of mesophilic 37 °C) and a 20% loading of fats, oil and grease (FOG; 20% w:v). These variables were explored at two sludge retention times (12 and 20 days) and two organic loading rates (2.0 and 2.5 kgTS/m(3)day OLR). Metagenomic and metabolomic approaches were then used to characterise the impact of operational shocks in regard to temperature and FOG addition, as determined through monitoring of biogas production, the microbial profile and their metabolism. Results showed that AD performance was not greatly affected by temperature shocks, with the biggest impact being a reduction in biogas production at 42 °C that persisted for 32 ± 1 days. The average biogas production across all digesters at the completion of the experiment was 264.1 ± 76.5 mL/day, with FOG addition observed to significantly promote biogas production (+87.8 mL/day). Metagenomic and metabolomic analyses of the digesters indicated that methanogens and methane oxidising bacteria (MOB) were low in relative abundance, and that the ratio of oxidising bacteria (methane, sulphide and sulphate) with respect to sulphate reducing bacteria (SRB) had a noticeable influence on biogas production. Furthermore, increased biogas production correlated with an increase in short chain fatty acids, a product of the addition of 20% FOG. This work demonstrates the application of metagenomics and metabolomics to characterise the microbiota and their metabolism in AD digesters, providing insight to the resilience of crucial microbial populations when exposed to operational shocks.

The Man Behind the Royal Massacre

Delusional disorder is a relatively uncommon psychiatric condition in which patients present with non-bizarre delusions, but with no accompanying prominent perceptual disturbances, thought disorder or significant and sustained mood symptoms. Apart from their delusions, people with delusional disorder may continue to socialize and function in a normal manner and their behavior does not generally seem odd or bizarre to others for many years of the onset of their symptoms. Because of this, they are brought to the clinician many years after the onset of their symptoms, only when their delusional behavior becomes overt. Thus, identifying and treating delusional disorders in time is a challenging task.

Can ganglion cell complex assessment on cirrus HD OCT aid in detection of early glaucoma?

Context

Ganglion cell complex is damaged early in glaucoma. Does this loss of GCC help in early diagnosis of glaucoma.

Aims

To compare the RNFL thickness and ganglion cell complex (GCC) in diagnosed patients of glaucoma, pre-perimetric glaucoma and normal controls.

Settings and design

Case controlled, observational study.

Methods and material

33 glaucoma patients, 45 pre-perimetric glaucoma, and 30 controls were enrolled in the study. ONH parameters on cirrus HD OCT like CD ratio, para papillary RNFL thickness and GCC were calculated for each case.

Statistical analysis used

ANOVA test to analyse differences between groups. ROC for ganglion cell layer.

Results

RNFL thickness was 71.6 μ and GCC was 69.19 μ in glaucoma patients. RNFL thickness was 77.31 μ and GCC was 71 μ in pre-perimetric glaucoma and 99.6 μ and 85.16 μ in controls respectively. The difference of mean for RNFL and GCC by ANOVA was statistically significant for controls, glaucoma patients and pre-perimetric glaucoma patients. RNFL (p < 0.001) and GCC (p < 0.001). Receiver operating characteristic curve for GCC was 0.83 (p < 0.000).

Conclusions

The RNFL analysis is increasingly being used as newer tool in diagnosis of glaucoma. In addition, GCC can be used as a supplementary tool in picking up cases of pre-perimetric glaucoma as loss is significant in pre-perimetric glaucoma also.

Experience of propofol sedation in a UK ERCP practice: lessons for service provision

OBJECTIVE

Endoscopic retrograde cholangiopancreatography (ERCP) in the UK has been historically performed under conscious sedation. However, given the increasing complexity of cases, the role of propofol-assisted ERCP (propERCP) is increasing. We describe our experience of propERCP and highlight the importance of this service.

DESIGN

Our prospective ERCP database was interrogated between January 2013 and January 2014. Data collection included procedural information, patient demographics, American Association of Anaesthesiologists (ASA) status, Cotton grade of endoscopic difficulty and endoscopic and anaesthetic complications. Comparison was made with patients undergoing conscious sedation ERCP (sedERCP).

RESULTS

744 ERCPs were performed in 629 patients (53% male). 161 ERCPs were performed under propofol. PropERCP patients were younger compared with the sedERCP group (54 vs 66 years, p<0.0001) but ASA grade 1-2 status was similar (84% vs 78%, p=0.6). An increased number of Cotton grade 3-4 ERCPs were performed in the propERCP group (64% vs 34%, p<0.0001). Indications for propERCP included sphincter of Oddi manometry (27%), previously poorly tolerated sedERCP (26%), cholangioscopy (21%) and patient request (8%). 77% of cases were elective, 12% were urgent day-case transfers and 11% were urgent inpatients. 59% of cases were tertiary referrals. ERCP was completed successfully in 95% of cases. Anaesthetic and endoscopic complications were comparable between the two groups (5% and 7% vs 3% and 5%). Where sedERCP had been unsuccessful due to patient intolerance, the procedure was completed successfully using propofol.

CONCLUSIONS

PropERCP is safe and is associated with high endoscopic success. The need for propERCP is likely to increase given patient preference and the high proportion of complex procedures being undertaken. All endoscopy units should look to incorporate propofol-assisted endoscopy into aspects of their services.

Biliary and hepatic involvement in IgG4-related disease

BACKGROUND

IgG4-related disease (IgG4-RD) is a multi-systemic disorder. IgG4-related sclerosing cholangitis (IgG4-SC) is the biliary manifestation of the disease, often in association with autoimmune pancreatitis (AIP). Hepatic manifestations of IgG4-RD are less well described within the literature.

AIM

To examine and present an overview of IgG4-RD with a focus on the biliary and hepatic manifestations.

METHODS

An electronic search using Medline was performed. Search items included 'IgG4 multi-system disease, IgG4 associated cholangitis, IgG4 associated liver disease and autoimmune pancreatitis (AIP)'.

RESULTS

IgG4-RD is characterised by an IgG4-positive lymphoplasmacytic tissue infiltrate, storiform fibrosis and an obliterative phlebitis. The HISORt criteria may be used to establish the diagnosis and incorporate a multi-disciplinary approach involving histology, radiology, serum IgG4 levels and response to steroid therapy. IgG4-SC is the commonest extrapancreatic manifestation of type-1 AIP, while the hepatic manifestations remain poorly defined. Important differential diagnoses include primary sclerosing cholangitis, secondary sclerosing cholangitis, cholangiocarcinoma and pancreatic carcinoma. Current treatment regimens remain ill defined although steroid therapy is used first line unless contraindicated. Patients with relapsing disease or multifocal disease should be considered for azathioprine. Available data would also suggest a role for rituximab.

CONCLUSIONS

IgG4-related sclerosing cholangitis is a common manifestation of IgG4-related disease which requires a multi-disciplinary approach to establish the diagnosis. Differentiating IgG4-related sclerosing cholangitis from other conditions, both benign and malignant, is challenging, but vital. Steroids remain the mainstay of treatment. Our understanding of the pathogenesis of the hepatic manifestations of IgG4-related disease continues to evolve.