Dental development in a sample of South African HIV-positive children

Aims: While oral soft tissue manifestations associated with HIV-infection in children are well documented, few studies have investigated the dental development of this group. The aim of this study was to assess dental development in a sample of HIVpositive children in comparison with an age-matched HIV-negative control group. Methods and results: The sample comprised 44 HIV-positive children and 44 HIVnegative children matched for age, gender, and ethnicity. An orthopantomograph (OPG) of each patient was assessed in order to calculate the dental age. The mineralization stages of teeth were used to calculate the dental age using tables formulated by Phillips and van Wyk-Kotze for this grouping. Results showed that dental development for both groups were similar to the dental age-related tables. HIV-positive children between 8 and 10 years of age showed significantly advanced dental development (p = 0.04). HIV-positive females showed significant advancement in dental age as compared to their chronological ages. Thirty-six (81.8%) HIV-positive children were on antiretroviral (ARV) drugs. Conclusion: HIV-positive children presented stages of dental development in accordance with their chronological ages and in tandem with that of the HIV-negative controls

Comparison of a piezoelectric and a standard surgical handpiece in third molar surgery

Aim: The aim was to compare the use of a piezoelectric hand piece versus a standard surgical handpiece in removal of impacted third molars under general anaesthesia. Materials and methods: Thirty patients undergoing routine third molar removal were included in the study. Panoramic radiographs were used to assess the positioning of the impacted third molars. The patients were randomly subdivided and the split mouth technique was used in which each side (left or right) of the mouth was randomly assigned to two treatment groups. Hence each patient served as their own control. In one group, a piezoelectric handpiece was used, while a conventional handpiece was used for the second group. All aspects of preoperative care, general anaesthesia, surgery and post-operative care were standardised for the two groups. The following parameters were recorded; time of surgery, bleeding during surgery, post-operative swelling, post-operative pain, associated complications and post-operative nerve injury. Results: No statistically significant difference was found between the groups in terms of pain and swelling. There was less bleeding with the use of the piezoelectric device as compared with the standard surgical handpiece; however, the surgical time was longer. There were no reports of trauma to the lips or intra-oral soft tissue. There were two incidences (6.7%) of post-operative paraesthesia in the standard surgical handpiece group. Conclusions: The use of a piezoelectric device is an acceptable alternative to the standard surgical handpiece in third molar surgery. Its use is advocated in difficult cases especially where there is inferior alveolar nerve approximation

Crystal structure analysis and supramolecular association in ethyl N-[amino(iminio)methyl]carbamate dichloride hemi-hydrate

X-ray crystallography on [EtOC(=O)N(H)C(=N+H2)NH2]Cl·½H2O (1) shows the asymmetric unit to comprise two independent cations, two chloride anions and crystal water. The main conformational difference between the cations is seen in the relative orientation of the ethyl groups; geometry-optimisation confirms the all-trans conformation is the most stable. The remaining parts of the cations are co-planar and feature intramolecular N–H···O(carbonyl) hydrogen bonds. An analysis of the N–H bonds suggests substantial delocalisation of the positive charge over the CN3 atoms. In the crystal, columns comprising the first independent cation are surrounded by four columns of the second cation within a network of water-O–H···Cl, N–H···Cl and N–H···O(water, carbonyl) hydrogen bonds, many of which are charge-assisted. The packing has been further investigated by Hirshfeld surface analysis, molecular electrostatic potential and interaction energy calculations. The charge-assisted N–H···Cl hydrogen bonds are significantly stronger than the water-O–H···Cl interactions consistent the distribution of the positive charge over the CN3 atoms

A reactivity-selectivity study of the Friedel-Crafts acetylation of 3,3′-dimethylbiphenyl and the oxidation of the acetyl derivatives

<p>Abstract</p> <p>Background</p> <p>Friedel-Crafts acetylation is an important route to aromatic ketones, in research laboratories and in industry. The acetyl derivatives of 3,3′-dimethylbiphenyl (3,3′-dmbp) have applications in the field of liquid crystals and polymers and may be oxidized to the dicarboxylic acids and derivatives that are of interest in cancer treatment.</p> <p>Findings</p> <p>The effect of solvent and temperature on the selectivity of monoacetylation of 3,3’-dmbp by the Perrier addition procedure was studied using stoichiometric amounts of reagents. 4-Ac-3,3′-dmbp was formed almost quantitatively in boiling 1,2-dichloroethane and this is almost twice the yield hitherto reported. Using instead a molar ratio of substrate:AcCl:AlCl₃ equal to 1:4:4 or 1:6:6 in boiling 1,2-dichloroethane, acetylation afforded 4,4′- and 4,6′-diacetyl-3,3′-dmbp in a total yield close to 100%. The acetyl derivatives were subsequently converted to the carboxylic acids by hypochlorite oxidation. The relative stabilities of the isomeric products and the corresponding σ-complexes were studied by DFT calculations and the data indicated that mono- and diacetylation followed different mechanisms.</p> <p>Conclusions</p> <p>Friedel-Crafts acetylation of 3,3′-dmbp using the Perrier addition procedure in boiling 1,2-dichloroethane was found to be superior to other recipes. The discrimination against the 6-acetyl derivative during monoacetylation seems to reflect a mechanism including an AcCl:AlCl₃ complex or larger agglomerates as the electrophile, whereas the less selective diacetylations of the deactivated 4-Ac-3,3′-dmbp are suggested to include the acetyl cation as the electrophile. The DFT data also showed that complexation of intermediates and products with AlCl₃ does not seem to be important in determining the mechanism.</p

Bimetallic Ni‒Co phosphide nanosheets self-supported on nickel foam as high-performance electrocatalyst for hydrogen evolution reaction

In this work, bimetallic nickel-cobalt phosphide (Ni-Co-P/NF) self-supported on nickel foam (NF) is synthesized for hydrogen evolution reaction (HER). A two-step method of electrodeposition with subsequently low-temperature phosphatizing is adopted. The physicochemical characterizations of the as-prepared Ni-Co-P/NF show that the surface is covered by metallic phosphide compounds (NiCoP, NiP and Co2P) with unique morphology, consisted of nanosheets randomly dispersed on villiform 3D integrated framework. The electrochemical characterizations demonstrate that Ni-Co-P/NF exhibits the highest performance for HER, in 1.0 M KOH aqueous solution, compared to other as-prepared electrocatalysts. Specifically, it requires very low overpotential values of 85, 210 and 350 mV for delivering large current densities of −10, −500 and −1,500 mA cm−2, respectively, revealing a low Tafel slope of 46 mV dec−1. Besides, Ni-Co-P/NF also displays long-term durability lasting 24 h without obvious deactivation. This work highlights that the NiCoP, NiP and Co2P active phases play a crucial role for the good HER activity. In addition, the unique morphology with self-supported structure provides large electrochemical surface area, allowing the exposure of higher amount of active sites for HER. These self-supported electrocatalysts, without binder, could also improve the electrode's HER activity and stability. This work, therefore, provides a controllable and feasible strategy to synthesize bimetallic phosphides of unique morphology with high HER activity. © 2019 Elsevier Lt

In Silico and In Vitro Screening of 50 Curcumin Compounds as EGFR and NF-κB Inhibitors

The improvement of cancer chemotherapy remains a major challenge, and thus new drugs are urgently required to develop new treatment regimes. Curcumin, a polyphenolic antioxidant derived from the rhizome of turmeric (Curcuma longa L.), has undergone extensive preclinical investigations and, thereby, displayed remarkable efficacy in vitro and in vivo against cancer and other disorders. However, pharmacological limitations of curcumin stimulated the synthesis of numerous novel curcumin analogs, which need to be evaluated for their therapeutic potential. In the present study, we calculated the binding affinities of 50 curcumin derivatives to known cancer-related target proteins of curcumin, i.e., epidermal growth factor receptor (EGFR) and nuclear factor κB (NF-κB) by using a molecular docking approach. The binding energies for EGFR were in a range of −12.12 (±0.21) to −7.34 (±0.07) kcal/mol and those for NF-κB ranged from −12.97 (±0.47) to −6.24 (±0.06) kcal/mol, indicating similar binding affinities of the curcumin compounds for both target proteins. The predicted receptor-ligand binding constants for EGFR and curcumin derivatives were in a range of 0.00013 (±0.00006) to 3.45 (±0.10) µM and for NF-κB in a range of 0.0004 (±0.0003) to 10.05 (±4.03) µM, indicating that the receptor-ligand binding was more stable for EGFR than for NF-κB. Twenty out of 50 curcumin compounds showed binding energies to NF-κB smaller than −10 kcal/mol, while curcumin as a lead compound revealed free binding energies of >−10 kcal/mol. Comparable data were obtained for EGFR: 15 out of 50 curcumin compounds were bound to EGFR with free binding energies of −10 kcal/mol. This indicates that the derivatization of curcumin may indeed be a promising strategy to improve targe specificity and to obtain more effective anticancer drug candidates. The in silico results have been exemplarily validated using microscale thermophoresis. The bioactivity has been further investigated by using resazurin cell viability assay, lactate dehydrogenase assay, flow cytometric measurement of reactive oxygen species, and annexin V/propidium iodide assay. In conclusion, molecular docking represents a valuable approach to facilitate and speed up the identification of novel targeted curcumin-based drugs to treat cancer