Ventricular-arterial coupling predicts outcomes in adults with a systemic right ventricle

Background

Patients with a systemic right ventricle (SRV) and biventricular circulation experience high incidence of cardiovascular morbidities and decreased survival [1]. Non-invasive measures of subclinical ventricular dysfunction are needed to appropriately identify patients at increased risk for adverse outcomes. Ventricular-arterial coupling (VAC), the ratio between the effective arterial elastance (Ea) and ventricular end-systolic elastance (Ees), may predict clinical outcomes in patients with SRV [2].

Objectives

To assess VAC in adults with SRV and evaluate its correlation with clinical outcomes.

Methods

Consecutive cardiovascular magnetic resonance (CMR) examinations of adults with D-loop transposition of great arteries (TGA) after atrial switch operation and L-loop TGA performed at Boston Children's Hospital between 2005 and 2019 were analyzed. VAC was calculated as Ea/Ees (Ea = mean arterial blood pressure (MBP)/ventricular stroke volume; Ees = MBP/end-systolic volume). Global myocardial strain was measured by feature tracking analysis on cine steady-state free precession sequences. Cox proportional hazards regression analysis was performed to assess the association of SRV functional parameters with clinical outcomes. The analysis was adjusted for age, sex, and body mass index. The primary outcome was defined as a composite of death, cardiovascular arrest, hospitalizations for heart failure (HF); the secondary outcome as atrial arrhythmias; the tertiary outcome included other causes of cardiovascular hospitalizations (percutaneous or surgical interventions, device implantation, other cardiovascular disease). Cumulative incidence of the study outcomes was estimated using Kaplan-Meier method.

Results

One hundred sixty-seven adults (mean age 32±10 years, 59% men) with SRV were analyzed. Patients with HF (n=48, 29%) had higher VAC values as compared to those without HF (1.4±0.8 vs. 1.1±0.5, p=0.01). Over a mean follow-up of 6.5±4.2 years, 15 over 139 patients (11%) experienced the primary outcome with an incidence rate of 1.7 per 100 patient-years (95% confidence interval (CI), 1.04–2.85). Higher VAC values were significantly associated with an increased risk of the primary outcome (p for trend = 0.01, Figure 1). VAC was the only functional parameter associated with the primary outcome (hazard ratio (HR) 1.99, 95% CI: 1.06–3.73, p=0.031), secondary outcome (HR 2.33, 95% CI: 1.12–4.82, p=0.023) and tertiary outcome (HR 1.63, 95% CI: 1.09–2.44, p=0.018) in the adjusted analysis (Table 1). Ejection fraction (EF) was not associated with the study outcomes in the adjusted analysis (p>0.05, Table 1) whereas global circumferential and radial strain showed an association limited to the tertiary endpoint (p=0.004, Table 1).

Conclusions

CMR-derived VAC is associated with adverse outcomes in SRV patients and may improve risk stratification of this unique population.

Funding Acknowledgement

Type of funding sources: None.

Cedrus deodara (Roxb. ex D.Don) G.Don: A review of traditional use, phytochemical composition and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Cedrus deodara (Roxb. ex D.Don) G.Don (Family: Pinaceae) is a medicinal tree traditionally important and well mentioned in traditional system of medicine of India, Pakistan, China, Korea etc. for its use in the management of skin diseases, microbial infections, joint disorders, asthma, kidney stones, ulcer, brain disorders and immunological disorders.

AIM AND OBJECTIVES

This review provides an insight into the information available regarding traditional uses, ethnobotany, phytochemistry and, pharmacological profiling of C. deodara crude extract, its isolated compounds and, fractions, to explore its potential for the development of novel therapeutic agents.

MATERIAL AND METHODS

Various databases including Scopus, Google Scholar, Science Direct, ACS, Wiley, Web of Science, Springer Link and, PubMed were used to collect all the appropriate information available in previously published literature related to this plant. Besides, other official electronic sources viz. Encyclopedia Britannica and Northern Regional Center, Botanical Survey of India, theplantlist.org. and relevant book chapters and books were also explored.

RESULTS

C. deodara is a popular medicinally active tree, traditionally used in the form of decoction, syrup, oil, powder, and extract alone or in combination with other herbs for the management of different ailments viz. asthma, ulcers, bone fractures, sprains rheumatism, boils, leprosy, etc. Phytochemical studies reported 105 chemical constituents from different parts of the plant, most of them belong to a class of terpenoids and flavonoids. Crude extracts, essential oils, fractions, and isolated compounds of C. deodara exhibited some important pharmacological activities including anticancer, antimicrobial, antifungal, analgesic, anti-inflammatory, neuroprotective, antidiabetic, antiurolithiatic, antiarthritic and, antiasthmatic.

CONCLUSION

Present article delivers in-depth information on botany, ethnopharmacology, phytochemistry, pharmacology, and toxicology. C. deodara has been in practice among indigenous people of India, Pakistan, Nepal, Korea, China, Nigeria and Russia and 28 different ethnicities for the management of approximately 40 diseases. Bioactive compounds particularly cedrin, himachalol, himachalene and atlantone are recognized as key constituents for observed pharmacological activities of C. deodara. However, further in-depth studies involving bio-guided fractionation, isolation, identification using advanced techniques to afford some new therapeutically active phytoconstituents in the management of different diseases. Preliminary pharmacological investigations on different extracts and fractions of C. deodara partially validated its traditional claims in different ailments such as skin diseases, asthma, neurological disorders, arthritis, microbial infections, gastric disturbances, and inflammation. However, immediate attempts are required to establish its mechanism of action, efficacy, dosage range, and safety in combating different pathological states.

A Numerical Approach to the Modeling of Thomson and Troian Slip on Nonlinear Radiative Microrotation of Casson Carreau Nanomaterials in Magnetohydrodynamics

The goal of the current work is to explore the influence of Thompson and Troian slip on the hydromagnetic microrotations of Carreau nanomaterials over a linearly stretched surface subject to NLTR, viscous dissipation, Newtonian heating, homogenous and heterogeneous reactions. Effect of non linear slip (Thompson and Troian slip) on non Newtonian nanofluid (Carreau nanofluid) subject to microrotation is the novelty of the investigation. Shooting technique is the instrumental to get appropriate numerical solution. The significant outcomes of the current study are that Casson parameter and Weissenberg number exhibit opposite results for velocity and heat transfer rate due to flow of micropolar Carreau nanofluid. Further, more and more Thompson and Troian slip yields diminution of flow velocity as well as microrotations. Amplifying Casson parameter intensifies the HTR from the stretched surface.

Interplay between spin proximity effect and charge-dependent exciton dynamics in MoSe2/CrBr3 van der Waals heterostructures

Semiconducting ferromagnet-nonmagnet interfaces in van der Waals heterostructures present a unique opportunity to investigate magnetic proximity interactions dependent upon a multitude of phenomena including valley and layer pseudospins, moiré periodicity, or exceptionally strong Coulomb binding. Here, we report a charge-state dependency of the magnetic proximity effects between MoSe2 and CrBr3 in photoluminescence, whereby the valley polarization of the MoSe2 trion state conforms closely to the local CrBr3 magnetization, while the neutral exciton state remains insensitive to the ferromagnet. We attribute this to spin-dependent interlayer charge transfer occurring on timescales between the exciton and trion radiative lifetimes. Going further, we uncover by both the magneto-optical Kerr effect and photoluminescence a domain-like spatial topography of contrasting valley polarization, which we infer to be labyrinthine or otherwise highly intricate, with features smaller than 400 nm corresponding to our optical resolution. Our findings offer a unique insight into the interplay between short-lived valley excitons and spin-dependent interlayer tunneling, while also highlighting MoSe2 as a promising candidate to optically interface with exotic spin textures in van der Waals structures.

COVID-19 in people living with diabetes: An international consensus

The COVID-19 pandemic has added an enormous toll to the existing challenge of diabetes care world-wide. A large proportion of patients with COVID-19 requiring hospitalization and/or succumbing to the disease have had diabetes and other chronic conditions as underlying risk factors. In particular, individuals belonging to racial/ethnic minorities in the U.S. and other countries have been significantly and disproportionately impacted. Multiple and complex socioeconomic factors have long played a role in increasing the risk for diabetes and now for COVID-19. Since the pandemic began, the global healthcare community has accumulated invaluable clinical experience on providing diabetes care in the setting of COVID-19. In addition, understanding of the pathophysiological mechanisms that link these two diseases is being developed. The current clinical management of diabetes is a work in progress, requiring a shift in patient-provider interaction beyond the walls of clinics and hospitals: the use of tele-medicine when feasible, innovative patient education programs, strategies to ensure medication and glucose testing availability and affordability, as well as numerous ideas on how to improve meal plans and physical activity. Notably, this worldwide experience offers us the possibility to not only prepare better for future disasters but also transform diabetes care beyond the COVID-19 era.

A facile one pot synthesis of novel pyrimidine derivatives of 1,5-benzodiazepines via domino reaction and their antibacterial evaluation

A new series of pyrimidine (8, 14, 18 and 23) embellished analogues of 1,5-benzodiazepines were synthesized by the one-pot domino approach using the catalyst DABCO (1,4-diazabicyclo[2.2.2]octane). For each compound synthesized, anti-microbial efficacy was determined using broth microdilution assay and half maximal inhibitory concentration (IC₅₀). Furthermore, FESEM (Field emission scanning electron microscope) studies were also carried out to observe the effect of the structure of test compounds on the morphology of both Gram-positive (S. aureus) and Gram-negative (E. coli) cell walls. The leakage of nucleotides and their integral components from compromised bacterial cells was assessed by plotting the optical density (OD) with respect to time of exposure at 320 nm. Anti-bacterial studies revealed that compound 23 was most active against targeted bacterial species. Results of the antibacterial study indicated that all the test compounds possess significant antibacterial potential against targeted bacterial strains. Amongst all, in the FE-SEM study, compound 23 caused marked alteration in bacterial cell morphology and resulted in maximum leakage of cell nucleotides in bacterial strains as compared to controls. Further efforts are required to establish their efficacy as antibacterial agents in clinical management.

Body fat, metabolic syndrome and hyperglycemia in South Asians

The prevalence of overweight and obesity is escalating in South Asian countries. South Asians display higher total and abdominal obesity at a lower BMI when compared to Whites. Consequently, metabolic dysfunction leading to metabolic syndrome (MetS) and type 2 diabetes mellitus (T2DM) will account for a majority of the health burden of these countries. In this review, we discuss those factors that contribute to MetS and T2DM in South Asians when compared to whites, focusing on adiposity. Abdominal obesity is the single-most important risk factor for MetS and its predisposition to T2DM. Excessive ectopic fat deposition in the liver (non-alcoholic fatty liver disease) has been linked to insulin resistance in Asian Indians, while the effects of ectopic fat accumulation in pancreas and skeletal muscle need more investigation. South Asians also have lower skeletal muscle mass than Whites, and this may contribute to their higher risk T2DM. Lifestyle factors contributing to MetS and T2DM in South Asians include inadequate physical activity and high intakes of refined carbohydrates and saturated fats. These are reflective of the recent but rapid economic transition and urbanization of the South Asian region. There is need to further the research into genetic determinants of dysmetabolism as well as gene x environment interactions. Collectively, MetS and T2DM have multi-factorial antecedents in South Asians and efforts to combat it through low-cost and socio-culturally appropriate lifestyle interventions need to be supported.

Management of obesity in adult Asian Indians

The prevalence of obesity in India is increasing and ranges from 8% to 38% in rural and 13% to 50% in urban areas. Obesity is a risk factor for development of type 2 diabetes mellitus (T2DM), hypertension, dyslipidemia, coronary heart disease and many cancers. In Asian Indians excess abdominal and hepatic fat is associated with increased risk for T2DM and cardiovascular disease. There is higher risk for development of obesity related non-communicable diseases at lower body mass index levels, compared to white Caucasians. Despite being a commonly encountered medical problem, obesity poses challenges in treatment. Many Indian physicians find themselves to be lacking time and expertise to prepare an appropriate obesity management plan and patients experience continuous weight gain over time despite being under regular medical supervision. In this article, we outline approaches to obesity management in ‘real life mode’ and in context to Asian Indian patients.

Prevalence and trends of metabolic syndrome among adults in the asia-pacific region: a systematic review

Background

The Asia-Pacific region is home to nearly half of the world’s population. The region has seen a recent rapid increase in the prevalence of obesity, type-2 diabetes and cardiovascular disease. The present systematic review summarizes the recent prevalence and trends of Metabolic Syndrome (MetS) among adults in countries of the Asia-Pacific Region.

Methods

Data on MetS in Asia-Pacific countries were obtained using a stepwise process by searching the online Medline database using MeSH terms ‘Metabolic Syndrome X’ and ‘Epidemiology/EP’. For the purpose of describing prevalence data for the individual countries, studies that were most recent, nationally representative or with the largest sample size were included. When evaluating secular trends in prevalence in a country we only considered studies that evaluated the temporal change in prevalence between similar populations, prospective studies based on the same population or National surveys conducted during different time periods.

Results

This literature search yielded a total of 757 articles, and five additional article were identified by screening of reference lists. From this total, 18 studies were eligible to be included in the final analysis. Of the 51 Asia-Pacific countries (WHO) we only located data for 15. There was wide between country variation in prevalence of MetS. A national survey from Philippines conducted in 2003 revealed the lowest reported prevalence of 11.9% according to NCEP ATP III criteria. In contrast, the highest recorded prevalence in the region (49.0%) came from a study conducted in urban Pakistan (Karachchi, 2004). Most studies reported a higher prevalence of MetS in females and urban residents. Data on secular trends were available for China, South Korea and Taiwan. An increase in the prevalence of MetS was observed in all three countries.

Conclusion

Despite differences in methodology, diagnostic criteria and age of subjects studied, the Asia-Pacific region is facing a significant epidemic of MetS. In most countries nearly 1/5th of the adult population or more were affected by MetS with a secular increase in prevalence. Strategies aimed at primary prevention are required to ameliorate a further increase in the epidemic and for the reduction of the morbidity and mortality associated with MetS.

Electronic supplementary material

The online version of this article (doi:10.1186/s12889-017-4041-1) contains supplementary material, which is available to authorized users.

Obesity, Diabetes and Cardiovascular Diseases in India: Public Health Challenges

Non-communicable diseases (NCDs; including coronary heart disease and type 2 diabetes) are rapidly increasing in India causing nearly 5.8 million deaths per year. Primary reasons for rise in NCDs in India are nutrition and lifestyle transitions. Further, presence of higher body fat, abdominal fat, liver and pancreatic fat and lower lean mass than whites, contribute to heightened metabolic and cardiovascular risk in Asian Indians. Importantly, conversion from pre-diabetes to diabetes occurs more rapidly, and reversion to normal glucose regulation with appropriate lifestyle measures is more difficult in Asian Indians than white population. Huge number of patients with diabetes and with complications increase morbidity, mortality and pose substantial economic burden. It is difficult, though not impossible, to decrease pace of rapidly expanding juggernaut of NCDs in India. Only concerted efforts from multiple stakeholders, consistently sincere efforts and intensely focused attention from health officialdom and clear political will may help counter this increasingly difficult challenge. Finally, all prevention and management approaches should be cost-effective, pragmatic, and focused on children and underprivileged populations.

Vascular Cells in Blood Vessel Wall Development and Disease

The vessel wall is composed of distinct cellular layers, yet communication among individual cells within and between layers results in a dynamic and versatile structure. The morphogenesis of the normal vascular wall involves a highly regulated process of cell proliferation, migration, and differentiation. The use of modern developmental biological and genetic approaches has markedly enriched our understanding of the molecular and cellular mechanisms underlying these developmental events. Additionally, the application of similar approaches to study diverse vascular diseases has resulted in paradigm-shifting insights into pathogenesis. Further investigations into the biology of vascular cells in development and disease promise to have major ramifications on therapeutic strategies to combat pathologies of the vasculature.

Phonon-Assisted Resonant Tunneling of Electrons in Graphene-Boron Nitride Transistors

We observe a series of sharp resonant features in the differential conductance of graphene-hexagonal boron nitride-graphene tunnel transistors over a wide range of bias voltages between 10 and 200 mV. We attribute them to electron tunneling assisted by the emission of phonons of well-defined energy. The bias voltages at which they occur are insensitive to the applied gate voltage and hence independent of the carrier densities in the graphene electrodes, so plasmonic effects can be ruled out. The phonon energies corresponding to the resonances are compared with the lattice dispersion curves of graphene-boron nitride heterostructures and are close to peaks in the single phonon density of states.

Vegetation indices mapping for Bhiwani district of Haryana (India) through LANDSAT-7ETM+ and remote sensing techniques

This study describes the VIs Vegetation Condition Index in term of vegetation health of wheat crop; with help of LANDSAT-7ETM+ data based NDVI and LAI for Bhiwani District of Haryana states (India) and gave the spatial development pattern of wheat crop in year 2005 over the study area of India. NDVI is found to vary from 0.3 to 0.8. In northern and southern parts of study area NDVI varied from 0.6 to 0.7 but in western part of Bhiwani showed NDVI 0.2 to 0.4 due to fertility of soil and well canal destitution. LAI showed variation from 1 to 6 accordingto the health of crop as the same manner of NDVI because LAI VI is NDVI dependent only change the manner of representation of vegetation health, due to this fact relation curve (r2=) between NDVI and LAI of four different growing date of sates are in successively increasing order 0.509, 0.563, 0.577 and 0.719. The study reveals that VIs can be mapped with LANDSAT-7ETM+ through remote sensing, which can be further used for many studies like crop yield or estimating evaptranspiration on regional basis for water management because satellite observations provide better spatial and temporal coverage, the VIs based system will provide efficient tools for monitoring health of crop for improvement of agricultural planning. VIs based monitoring will serve as a prototype in the other parts of the world where ground observations are limited or not available.

Quantification of dislocation nucleation stress in TiN through high-resolution in situ indentation experiments and first principles calculations

Through in situ indentation of TiN in a high-resolution transmission electron microscope, the nucleation of full as well as partial dislocations has been observed from {001} and {111} surfaces, respectively. The critical elastic strains associated with the nucleation of the dislocations were analyzed from the recorded atomic displacements, and the nucleation stresses corresponding to the measured critical strains were computed using density functional theory. The resolved shear stress was estimated to be 13.8 GPa for the partial dislocation 1/6 <110> {111} and 6.7 GPa for the full dislocation ½ <110> {110}. Such an approach of quantifying nucleation stresses for defects via in situ high-resolution experiment coupled with density functional theory calculation may be applied to other unit processes.

Experimental Quantification of Resolved Shear Stresses for Dislocation Motion in TiN

Experimental quantification of the critical resolved shear stress (CRSS) at the level of unit dislocation glide is still a challenge. By using in situ nanoindentation in a high-resolution transmission electron microscope and strain analysis of the acquired structural images, the CRSS for the motion of individual dislocations on {110}⟨011⟩ slip system and glide dislocation re-emission from a tilt grain boundary in TiN are quantified. This work offers an approach to measure the local stresses associated with dislocation motion in high-strength materials.

Decadal changes in the land use/land cover and shoreline along the coastal districts of southern Gujarat, India

The coastal zone along the districts of Surat, Navsari, and Valsad in southern Gujarat, India, is reported to be facing serious environmental challenges in the form of shoreline erosion, wetland loss, and man-made encroachments. This study assesses the decadal land use/ land cover (LULC) changes in these three districts for the years 1990, 2001, and 2014 using satellite datasets of Landsat TM, ETM, and OLI. The LULC changes are identified by using band ratios as a pre-classification step, followed by implementation of hybrid classification (a combination of supervised and unsupervised classification). An accuracy assessment is carried out for each dataset, and the overall accuracy ranges from 90 to 95%. It is observed that the spatial extents of aquaculture, urban built-up, and barren classes have appreciated over time, whereas the coverage of mudflats has depreciated due to rapid urbanization. The changes in the shoreline of these districts have also been analyzed for the same years, and significant changes are found in the form of shoreline erosion. The LULC maps prepared as well as the shoreline change analysis done for this study area will enable the local decision makers to adopt better land-use planning and shoreline protection measures, which will further aid in sustainable future developments in this region.

Polymerization behavior of hydrophilic-rich phase of dentin adhesive

The 2-fold objectives of this study were 1) to understand whether model hydrophobic- and hydrophilic-rich phase mimics of dentin adhesive polymerize similarly and 2) to determine which factor, the dimethacrylate component, bisphenol A glycerolate dimethacrylate (BisGMA) or photoinitiator concentration, has greater influence on the polymerization of the hydrophilic-rich phase mimic. Current dentin adhesives are sensitive to moisture, as evidenced by nanoleakage in the hybrid layer and phase separation into hydrophobic- and hydrophilic-rich phases. Phase separation leads to limited availability of the cross-linkable dimethacrylate monomer and hydrophobic photoinitiators within the hydrophilic-rich phase. Model hydrophobic-rich phase was prepared as a single-phase solution by adding maximum wt% deuterium oxide (D2O) to HEMA/BisGMA neat resins containing 45 wt% 2-hydroxyethyl methacrylate (HEMA). Mimics of the hydrophilic-rich phase were prepared similarly but using HEMA/BisGMA neat resins containing 95, 99, 99.5, and 100 wt% HEMA. The hydrophilic-rich mimics were prepared with standard or reduced photoinitiator content. The photoinitiator systems were camphorquinone (CQ)/ethyl 4-(dimethylamino)benzoate (EDMAB) with or without [3-(3, 4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-2-hydroxypropyl]trimethylammonium chloride (QTX). The polymerization kinetics was monitored using a Fourier transform infrared spectrophotometer with a time-resolved collection mode. The hydrophobic-rich phase exhibited a significantly higher polymerization rate compared with the hydrophilic-rich phase. Postpolymerization resulting in the secondary rate maxima was observed for the hydrophilic-rich mimic. The hydrophilic-rich mimics with standard photoinitiator concentration but varying cross-linker (BisGMA) content showed postpolymerization and a substantial degree of conversion. In contrast, the corresponding formulations with reduced photoinitiator concentrations exhibited lower polymerization and inhibition/delay of postpolymerization within 2 h. Under conditions relevant to the wet, oral environment, photoinitiator content plays an important role in the polymerization of the hydrophilic-rich phase mimic. Since the hydrophilic-rich phase is primarily water and monomethacrylate monomer (e.g., HEMA as determined previously), substantial polymerization is important to limit the potential toxic response from HEMA leaching into the surrounding tissues.

Quantum mechanical metric for internal cohesion in cement crystals

Calcium silicate hydrate (CSH) is the main binding phase of Portland cement, the single most important structural material in use worldwide. Due to the complex structure and chemistry of CSH at various length scales, the focus has progressively turned towards its atomic level comprehension. We study electronic structure and bonding of a large subset of the known CSH minerals. Our results reveal a wide range of contributions from each type of bonding, especially hydrogen bonding, which should enable critical analysis of spectroscopic measurements and construction of realistic C-S-H models. We find the total bond order density (TBOD) as the ideal overall metric for assessing crystal cohesion of these complex materials and should replace conventional measures such as Ca:Si ratio. A rarely known orthorhombic phase Suolunite is found to have higher cohesion (TBOD) in comparison to Jennite and Tobermorite, which are considered the backbone of hydrated Portland cement.

Diabetes in South Asians

Economic, dietary and other lifestyle transitions have been occurring rapidly in most South Asian countries, making their populations more vulnerable to developing Type 2 diabetes and cardiovascular diseases. Recent data show an increasing prevalence of Type 2 diabetes in urban areas as well as in semi-urban and rural areas, inclusive of people belonging to middle and low socio-economic strata. Prime determinants for Type 2 diabetes in South Asians include physical inactivity, imbalanced diets, abdominal obesity, excess hepatic fat and, possibly, adverse perinatal and early life nutrition and intra-country migration. It is reported that Type 2 diabetes affects South Asians a decade earlier and some complications, for example nephropathy, are more prevalent and progressive than in other races. Further, prevalence of pre-diabetes is high, and so is conversion to diabetes, while more than 50% of those who are affected remain undiagnosed. Attitudes, cultural differences and religious and social beliefs pose barriers in effective prevention and management of Type 2 diabetes in South Asians. Inadequate resources, insufficient healthcare budgets, lack of medical reimbursement and socio-economic factors contribute to the cost of diabetes management. The challenge is to develop new translational strategies, which are pragmatic, cost-effective and scalable and can be adopted by the South Asian countries with limited resources. The key areas that need focus are: generation of awareness, prioritizing health care for vulnerable subgroups (children, women, pregnant women and the underprivileged), screening of high-risk groups, maximum coverage of the population with essential medicines, and strengthening primary care. An effective national diabetes control programme in each South Asian country should be formulated, with these issues in mind.

Proteins, pathogens, and failure at the composite-tooth interface

In the United States, composites accounted for nearly 70% of the 173.2 million composite and amalgam restorations placed in 2006 (Kingman et al., 2012), and it is likely that the use of composite will continue to increase as dentists phase out dental amalgam. This trend is not, however, without consequences. The failure rate of composite restorations is double that of amalgam (Ferracane, 2013). Composite restorations accumulate more biofilm, experience more secondary decay, and require more frequent replacement. In vivo biodegradation of the adhesive bond at the composite-tooth interface is a major contributor to the cascade of events leading to restoration failure. Binding by proteins, particularly gp340, from the salivary pellicle leads to biofilm attachment, which accelerates degradation of the interfacial bond and demineralization of the tooth by recruiting the pioneer bacterium Streptococcus mutans to the surface. Bacterial production of lactic acid lowers the pH of the oral microenvironment, erodes hydroxyapatite in enamel and dentin, and promotes hydrolysis of the adhesive. Secreted esterases further hydrolyze the adhesive polymer, exposing the soft underlying collagenous dentinal matrix and allowing further infiltration by the pathogenic biofilm. Manifold approaches are being pursued to increase the longevity of composite dental restorations based on the major contributing factors responsible for degradation. The key material and biological components and the interactions involved in the destructive processes, including recent advances in understanding the structural and molecular basis of biofilm recruitment, are described in this review. Innovative strategies to mitigate these pathogenic effects and slow deterioration are discussed.

Aerosol optical and physical properties during winter monsoon pollution transport in an urban environment

We analysed aerosol optical and physical properties in an urban environment (Kolkata) during winter monsoon pollution transport from nearby and far-off regions. Prevailing meteorological conditions, viz. low temperature and wind speed, and a strong downdraft of air mass, indicated weak dispersion and inhibition of vertical mixing of aerosols. Spectral features of WinMon aerosol optical depth (AOD) showed larger variability (0.68-1.13) in monthly mean AOD at short-wavelength (SW) channels (0.34-0.5 μm) compared to that (0.28-0.37) at long-wavelength (LW) channels (0.87-1.02 μm), thereby indicating sensitivity of WinMon AOD to fine aerosol constituents and the predominant contribution from fine aerosol constituents to WinMon AOD. WinMon AOD at 0.5 μm (AOD 0. 5) and Angstrom parameter ( α) were 0.68-0.82 and 1.14-1.32, respectively, with their highest value in December. Consistent with inference from spectral features of AOD, surface aerosol loading was primarily constituted of fine aerosols (size 0.23-3 μm) which was 60-70 % of aerosol 10- μm (size 0.23-10 μm) concentration. Three distinct modes of aerosol distribution were obtained, with the highest WinMon concentration at a mass median diameter (MMD) of 0.3 μm during December, thereby indicating characteristics of primary contribution related to anthropogenic pollutants that were inferred to be mostly due to contribution from air mass originating in nearby region having predominant emissions from biofuel and fossil fuel combustion. A relatively higher contribution from aerosols in the upper atmospheric layers than at the surface to WinMon AOD was inferred during February compared to other months and was attributed to predominant contribution from open burning emissions arising from nearby and far-off regions. A comparison of ground-based measurements with Moderate Resolution Imaging Spectroradiometer (MODIS) data showed an underestimation of MODIS AOD and α values for most of the days. Discrepancy in relative distribution of fine and coarse mode of MODIS AOD was also inferred.

Aerosol optical and physical properties during winter monsoon pollution transport in an urban environment

We analysed aerosol optical and physical properties in an urban environment (Kolkata) during winter monsoon pollution transport from nearby and far-off regions. Prevailing meteorological conditions, viz. low temperature and wind speed, and a strong downdraft of air mass, indicated weak dispersion and inhibition of vertical mixing of aerosols. Spectral features of WinMon aerosol optical depth (AOD) showed larger variability (0.68-1.13) in monthly mean AOD at short-wavelength (SW) channels (0.34-0.5 μm) compared to that (0.28-0.37) at long-wavelength (LW) channels (0.87-1.02 μm), thereby indicating sensitivity of WinMon AOD to fine aerosol constituents and the predominant contribution from fine aerosol constituents to WinMon AOD. WinMon AOD at 0.5 μm (AOD 0. 5) and Angstrom parameter ( α) were 0.68-0.82 and 1.14-1.32, respectively, with their highest value in December. Consistent with inference from spectral features of AOD, surface aerosol loading was primarily constituted of fine aerosols (size 0.23-3 μm) which was 60-70 % of aerosol 10- μm (size 0.23-10 μm) concentration. Three distinct modes of aerosol distribution were obtained, with the highest WinMon concentration at a mass median diameter (MMD) of 0.3 μm during December, thereby indicating characteristics of primary contribution related to anthropogenic pollutants that were inferred to be mostly due to contribution from air mass originating in nearby region having predominant emissions from biofuel and fossil fuel combustion. A relatively higher contribution from aerosols in the upper atmospheric layers than at the surface to WinMon AOD was inferred during February compared to other months and was attributed to predominant contribution from open burning emissions arising from nearby and far-off regions. A comparison of ground-based measurements with Moderate Resolution Imaging Spectroradiometer (MODIS) data showed an underestimation of MODIS AOD and α values for most of the days. Discrepancy in relative distribution of fine and coarse mode of MODIS AOD was also inferred.

Methods for implantation of micro-wire bundles and optimization of single/multi-unit recordings from human mesial temporal lobe

OBJECTIVE

The authors report methods developed for the implantation of micro-wire bundles into mesial temporal lobe structures and subsequent single neuron recording in epileptic patients undergoing in-patient diagnostic monitoring. This is done with the intention of lowering the perceived barriers to routine single neuron recording from deep brain structures in the clinical setting.

APPROACH

Over a 15 month period, 11 patients were implanted with platinum micro-wire bundles into mesial temporal structures. Protocols were developed for (A) monitoring electrode integrity through impedance testing, (B) ensuring continuous 24-7 recording, (C) localizing micro-wire position and 'splay' pattern and (D) monitoring grounding and referencing to maintain the quality of recordings.

MAIN RESULTS

Five common modes of failure were identified: (1) broken micro-wires from acute tensile force, (2) broken micro-wires from cyclic fatigue at stress points, (3) poor in vivo micro-electrode separation, (4) motion artifact and (5) deteriorating ground connection and subsequent drop in common mode noise rejection. Single neurons have been observed up to 14 days post-implantation and on 40% of micro-wires.

SIGNIFICANCE

Long-term success requires detailed review of each implant by both the clinical and research teams to identify failure modes, and appropriate refinement of techniques while moving forward. This approach leads to reliable unit recordings without prolonging operative times, which will help increase the availability and clinical viability of human single neuron data.

Swelling equilibrium of dentin adhesive polymers formed on the water-adhesive phase boundary: experiments and micromechanical model

During their application to the wet, oral environment, dentin adhesives can experience phase separation and composition change, which can compromise the quality of the hybrid layer formed at the dentin-adhesive interface. The chemical composition of polymer phases formed in the hybrid layer can be represented using a ternary water-adhesive phase diagram. In this paper, these polymer phases are characterized using a suite of mechanical tests and swelling experiments. The experimental results were evaluated using a granular micromechanics-based model incorporating poro-mechanical effects and polymer-solvent thermodynamics. The variation in the model parameters and model-predicted polymer properties was studied as a function of composition along the phase boundary. The resulting structure-property correlations provide insight into interactions occurring at the molecular level in the saturated polymer system. These correlations can be used for modeling the mechanical behavior of the hybrid layer, and are expected to aid in the design and improvement of water-compatible dentin adhesive polymers.

Liquid chromatography tandem mass spectrometry method for determination of antidiabetic chalcones derivative S001-469 in rat plasma, urine and feces: application to pharmacokinetic study

A sensitive and selective liquid chromatography tandem mass spectrometry assay was developed for quantitation of a novel antidiabetic chalcones derivative S001-469 in rat matrices. Plasma and urine samples were prepared by double liquid-liquid extraction with diethyl ether and feces by protein precipitation using acetonitrile. Chromatographic elution was carried on cyano guard column (30 mm × 4.6 mm i.d., 5 µm) in isocratic mode at a flow rate of 0.75 mL/min using mobile phase comprising of methanol: ammonium acetate buffer (pH 4.6, 10 mM) (90:10, v/v). Run time was 6 min. Detection was achieved by employing positive ionization mode on a triple-quadrupole LC-MS/MS system with an electrospray ionization (ESI) source. The calibration curves were linear over the range of 0.78-400 ng/mL for all 3 matrices. The method was validated and proved reliable through high and consistent intra- and inter- day accuracy and precision (<15%) values. Recoveries was >85% from spiked plasma, urine and feces samples. S001-469 was stable in plasma at room temperature till 8 h and at -60 °C for 30 d and 3 freeze-thaw cycles.