Improved nanocomposite of montmorillonite and hydroxyapatite for defluoridation of water

A novel hydroxyapatite montmorillonite (HAP-MMT) nanocomposite system was synthesized using a simple wet chemical in situ precipitation method. Neat nano hydroxyapatite (HAP) was also synthesized for comparison. The characterization of the materials was carried out using Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) isotherms to study the functional groups, morphology, crystallinity and the surface area respectively. Batch adsorption studies and kinetic studies on fluoride adsorption were conducted for the HAP-MMT system and for neat HAP. The effect of parameters such as contact time, pH, initial concentration, temperature, and thermodynamic parameters and the effect of coexisting ions on fluoride adsorption by HAP-MMT were studied. Results of the isotherm experiments were fitted to four adsorption isotherm models namely Langmuir, Freundlich, Temkin and Dubinin Radushkevich. Fluoride adsorption over HAP-MMT fitted to the Freundlich adsorption isotherm model and showed more than two-fold improved adsorption capacity (16.7 mg g⁻¹) compared to neat HAP. The best-fitting kinetic model for both adsorbents was found to be pseudo second order. Calculated thermodynamic parameters indicated that the fluoride adsorption by HAP-MMT is more favorable compared to that on HAP within the temperature range of 27 °C–60 °C. Improved fluoride adsorption by HAP-MMT is attributed to the exfoliated nature of HAP-MMT. Gravity filtration studies carried out using a 1.5 ppm fluoride solution, which is closer to the ground water fluoride concentrations of Chronic Kidney Disease of unknown etiology (CKDu) affected areas in Sri Lanka, resulted in a 1600 ml g⁻¹ break through volume indicating the potential of HAP-MMT to be used in real applications.

A novel hydroxyapatite montmorillonite (HAP-MMT) nanocomposite was synthesized using a simple wet chemical in situ precipitation method. This nanocomposite showed improved adsorption properties towards fluoride ions in water.     

Patient characteristics and clinical outcomes following initial surgical intervention for MEN1 associated pancreatic neuroendocrine tumours: A systematic review and exploratory meta-analysis of the literature

Background

This systematic review aimed to define the outcomes of different pancreatic resection procedures for multiple endocrine neoplasia type 1 (MEN1) associated pancreatic neuroendocrine neoplasms (pNENs).

Suicidal Behaviour on Subway Systems: A Review of the Epidemiology

Suicide on subway systems is a public health challenge that has been reported in urban centers worldwide. Our objective was to analyze studies of suicide on subway systems, develop a profile of characteristics that are suggestive of association with suicides or attempts, and show how this profile can inform prevention. A literature review involving epidemiology studies and studies relating to subway suicide was conducted. Twenty-eight studies were included in this review. Across studies, characteristics were not often assessed for risk factor status, although several characteristics were remarkably similar. Those attempting suicide on the subway appear to be affected by serious mental illness and have contact with mental health services before the suicidal behavior. Several characteristics may be shared among this population, emphasizing the potential for prevention in clinical and public health domains. Well-designed studies that utilize robust data collection and statistical methods are needed to establish the risk status associated with these characteristics.     

Oxidative stress is closely associated with insulin resistance in genotypes 1 and 3 chronic hepatitis C

Background

Chronic hepatitis C (CHC) infection is associated with insulin resistance and with oxidative stress, but the relationship between the two has not been thoroughly examined.

Purpose

To evaluate the association between insulin resistance and oxidative stress in CHC patients.

Method

In 115 CHC patients (68 with genotype 1 and 47 with genotype 3), the relationship between the serum concentration of malondialdehyde (MDA), a marker of oxidative stress and insulin resistance as defined by the homeostasis model (HOMA-IR) was examined.

Results

There was no significant difference in MDA levels between genotype 1- and genotype 3-infected subjects (12.882 vs. 12.426 ng/mL, p = 0.2). By univariate analysis, factors associated with HOMA-IR in both genotypes were oxidative stress as measured by MDA (p = 0.002), body mass index (BMI), portal activity, and fibrosis. Genotype-specific differences in HOMA-IR association were steatosis and triglycerides (TG) for genotype 1, and age and glutathione (GSH) for genotype 3. In a stepwise multiple linear regression analysis in both genotypes, MDA was a significant and independent predictor of HOMA-IR (p = 0.04). As expected, BMI and fibrosis were likewise independently correlated to HOMA-IR. In addition, MDA levels were higher (p < 0.001) and GSH levels were lower (p = 0.023) in insulin-resistant subjects compared to their insulin-sensitive counterparts.

Conclusions

It is concluded that in CHC, oxidative stress is an independent predictor of HOMA-IR, irrespective of virus genotype. Further studies on the role of oxidative stress in the development of insulin resistance in CHC are warranted.     

Cellular and molecular mechanisms in the development of a cleft lip and/or cleft palate; insights from zebrafish (Danio rerio)

Human cleft lip and/or palate (CLP) are immediately recognizable congenital abnormalities of the face. Lip and palate develop from facial primordia through the coordinated activities of ectodermal epithelium and neural crest cells (NCCs) derived from ectomesenchyme tissue. Subtle changes in the regulatory mechanisms of NCC or ectodermal epithelial cells can result in CLP. Genetic and environmental contributions or a combination of both play a significant role in the progression of CLP. Model organisms provide us with a wealth of information in understanding the pathophysiology and genetic etiology of this complex disease. Small teleost, zebrafish (Danio rerio) is one of the popular model in craniofacial developmental biology. The short generation time and large number of optically transparent, easily manipulated embryos increase the value of zebrafish to identify novel candidate genes and gene regulatory networks underlying craniofacial development. In addition, it is widely used to identify the mechanisms of environmental teratogens and in therapeutic drug screening. Here, we discuss the value of zebrafish as a model to understand epithelial and NCC induced ectomesenchymal cell activities during early palate morphogenesis and robustness of the zebrafish in modern research on identifying the genetic and environmental etiological factors of CLP.