Estrogen/Estrogen Receptor Alpha Signaling in Mouse Posterofrontal Cranial Suture Fusion

BACKGROUND: While premature suture fusion, or craniosynostosis, is a relatively common condition, the cause is often unknown. Estrogens are associated with growth plate fusion of endochondral bones. In the following study, we explore the previously unknown significance of estrogen/estrogen receptor signaling in cranial suture biology. METHODOLOGY/PRINCIPAL FINDINGS: Firstly, estrogen receptor (ER) expression was examined in physiologically fusing (posterofrontal) and patent (sagittal) mouse cranial sutures by quantitative RT-PCR. Next, the cranial suture phenotype of ER alpha and ER beta knockout (alphaERKO, betaERKO) mice was studied. Subsequently, mouse suture-derived mesenchymal cells (SMCs) were isolated; the effects of 17-beta estradiol or the estrogen antagonist Fulvestrant on gene expression, osteogenic and chondrogenic differentiation were examined in vitro. Finally, in vivo experiments were performed in which Fulvestrant was administered subcutaneously to the mouse calvaria. Results showed that increased ERalpha but not ERbeta transcript abundance temporally coincided with posterofrontal suture fusion. The alphaERKO but not betaERKO mouse exhibited delayed posterofrontal suture fusion. In vitro, addition of 17-beta estradiol enhanced both osteogenic and chondrogenic differentiation in suture-derived mesenchymal cells, effects reversible by Fulvestrant. Finally, in vivo application of Fulvestrant significantly diminished calvarial osteogenesis, inhibiting suture fusion. CONCLUSIONS/SIGNIFICANCE: Estrogen signaling through ERalpha but not ERbeta is associated with and necessary for normal mouse posterofrontal suture fusion. In vitro studies suggest that estrogens may play a role in osteoblast and/or chondrocyte differentiation within the cranial suture complex

The use of plants in the traditional management of diabetes in Nigeria: Pharmacological and toxicological considerations

Ethnopharmacological relevance: The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century. In Nigeria, the use of herbal medicine alone or alongside prescription drugs for its management is quite common. We hereby carry out a review of medicinal plants traditionally used for diabetes management in Nigeria. Based on the available evidence on the species׳ pharmacology and safety, we highlight ways in which their therapeutic potential can be properly harnessed for possible integration into the country׳s healthcare system. Materials and methods: Ethnobotanical information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed and Scopus up to 2013 for publications on medicinal plants used in diabetes management, in which the place of use and/or sample collection was identified as Nigeria. ‘Diabetes’ and ‘Nigeria’ were used as keywords for the primary searches; and then ‘Plant name – accepted or synonyms’, ‘Constituents’, ‘Drug interaction’ and/or ‘Toxicity’ for the secondary searches. Results: The hypoglycemic effect of over a hundred out of the 115 plants reviewed in this paper is backed by preclinical experimental evidence, either in vivo or in vitro. One-third of the plants have been studied for their mechanism of action, while isolation of the bioactive constituent(s) has been accomplished for twenty three plants. Some plants showed specific organ toxicity, mostly nephrotoxic or hepatotoxic, with direct effects on the levels of some liver function enzymes. Twenty eight plants have been identified as in vitro modulators of P-glycoprotein and/or one or more of the cytochrome P450 enzymes, while eleven plants altered the levels of phase 2 metabolic enzymes, chiefly glutathione, with the potential to alter the pharmacokinetics of co-administered drugs. Conclusion: This review, therefore, provides a useful resource to enable a thorough assessment of the profile of plants used in diabetes management so as to ensure a more rational use. By anticipating potential toxicities or possible herb–drug interactions, significant risks which would otherwise represent a burden on the country׳s healthcare system can be avoided

Carbapenem resistance expressed by Gram-negative bacilli isolated from a cohort of Libyan patients

Background and objectives: Carbapenem-resistant Enterobacteriaceae (CRE) and other Gram-negative bacteria are among the most common pathogens responsible for both community and hospital acquired infection. The global spread of cephalosporinases in Enterobacteriaceae has led to the increased use of carbapenems resulting in the emergence and rapid spread of CRE. This has become an alarming public health concern, yet the condition in Libya remains unclear. The aim of this study was to obtain a better understanding of CRE strains prevalent in Libyan patients by investigating their phenotypic characteristics and antibiograms. Methods: Gram-negative bacterial species were collected from Misrata Central Hospital, Misrata Cancer Centre and Privet Pathology Laboratories. Clinical samples and swabs were obtained from hospitalised and non-hospitalised patients and from mechanical ventilation and suction machines. Patients who had received antibiotic therapy for at least three days prior to the study were excluded. The identification and characterization of the isolated species were achieved using the growth characteristics on MacConkey and blood agar, spot tests and API 20E or API 20NE biochemical testing systems. Screening for carbapenem resistance was performed using the disk diffusion method with carbapenem 10 μg and cephalosporin 30 μg disks and minimum inhibitory concentrations (MIC) determined using the Sensititre Gram-negative Xtra plate format (GNX2F). All strains demonstrating resistance or reduced susceptibility to one of the four carbapenems were subjected to carbapenememase activity detection using the RAPIDEC CARBA NP test, Modified Hodge test and carbapenem inactivation methods. Results: A total of one hundred and forty isolates representing fourteen bacterial species were isolated from 140 non-duplicated specimens. Clinical specimens included urine samples (96/140, 68.57%), sputum (15/140, 10.71%), surgical wound swabs (18/140, 12.85%), foot swabs from diabetes mellitus (DM) patients (6/140, 4.29%), ear swabs (3/140, 2.14%) and wound swabs (2/140, 1.43%). Thirty-four (24.29%) isolates demonstrated resistance to at least one of the four carbapenems with Klebsiella pneumoniae representing 73.53% (25 isolates) of all carbapenem resistant species, followed by 8.82% for Pseudomonas aeruginosa (3 isolates), 5.88% for both Proteus mirabilis (2 isolates) and Escherichia coli (2 isolates) and 2.94% for both Citrobacter koseri (1 isolate) and Rahnella aquatilis (1 isolate). The other isolates were either susceptible or cephalosporinase producers. Conclusion: This study has revealed the high rate of carbapenem resistance amongst Libyan patients and emphasizes the crucial need for accurate screening, identification and susceptibility testing to prevent further spread of nosocomial and community acquired resistance. This may be achieved through the establishment of antibiotic stewardship programmes along with firm infection control practices.National Research Foundation of South Africa; Libyan GovernmentWeb of Scienc

Radical ion probes. 11. Reaction of 1,1-dimethyl-5,7-di-t-butylspiro[2.5]octa-4,7-dien-6-one with 5-hexenyl magnesium bromide

In an ongoing effort to establish 1,1-dimethyl-5,7-di-t-butylspiro[2.5]octa-4,7-dien-6-one (1) as a mechanistic probe for the detection of single electron transfer (SET), the reaction of1 with 5-hexenyl magnesium bromide was examined in the hopes of observing cyclization of any intermediate 5-hexenyl radicals to cyclopentylcarbinyl radicals. A polar process dominated the reaction, but in the less prevalent SET process, the 5-hexenyl → cyclopentylcarbinyl rearrangement was extensive, indicative of freely diffusing paramagnetic intermediates

Inverted Regioselectivities in the Reactions of Chlorine Atoms with Heteroarylmethanes

The relative reactivities of the two methyl groups of 2,6-dimethylquinoline (2,6-DMQ) and 2,7 dimethylquinoline (2,7-DMQ) toward several radicals were assessed by intramolecular competitions. The regioselectivities observed for t-BuO· and Br· (k6/k2, k7/k2 \u3e 1) are consistent with electrophilic characteristics of these radicals and estimates of relative stability of the resulting radicals. In contrast, Cl· displays inverted selectivities (k6/k2, k7/k2 \u3c 1) suggesting a directive effect of the DMQ nitrogen. Complexation of Cl· by the N lone pair of dimethylquinolines, followed by a novel intramolecular hydrogen abstraction through a 5-center cyclic transition state, explains the regioselectivities observed in these reactions. Although bromine atoms also complex with heteroaromatics, the Br· complexes have a low reactivity toward benzylic hydrogens. Evidence from intermolecular competition experiments, lasr flash photolysis studies, semiempirical MO calculations, and dimethylbutane quenching experiments is presented in support of the proposed intramolecular hydrogen abstraction process

Improving the Efficiency of the Mn^2+/3+ Couple in Quantum Dot Solar Cells: The Role of Spin Crossover

In this study, we present the synthesis of a family of first-row transition metal redox mediators based on the bis­[hydrotris­(pyrazolyl)]­borate manganese­(II/III) (MnTp₂) redox couple. Using cyclic voltammetry, the electrochemical properties and characteristic spin crossover inherent in this class of metal complexes were analyzed. From the electrochemical analysis the standard heterogeneous rate constant (<i>k</i>_s,h) was estimated. These constants were 1–2 orders of magnitude lower than other outer-sphere redox couples, such as Co­(bpy)₃^2+/3+ with <i>k</i>_s,h values decreasing from 6.39 (± 0.7) × 10^–3 cm/s in Co­(bpy)₃ to 1.60 (± 0.3) × 10^–5 cm/s in bis­[hydrotris­(4-ethylpyrazolyl)]­borate manganese­(II/III). It was theorized that the drastic reduction in the rate of electron transfer could be used to increase the lifetimes of the injected electrons in quantum dot sensitized solar cells (QDSSCs). Indeed, this was found to be the case with the slope of open-circuit voltage decay measurements being an order of magnitude lower in the Mn-based redox couples, compared to Co­(bpy)₃ when using cells prepared under the same conditions. This increase led us to then focus on optimizing the electrolyte solvent to assess the current–voltage characteristics of cells prepared using the MnTp₂ family of redox mediators. These cells displayed enhanced power conversion efficiencies when compared to Co­(bpy)₃ despite poor diffusion throughout the nanostructured TiO₂ film. Analysis of the quenching rate constant via Stern–Volmer quenching analysis suggested that the MnTp₂ family of redox mediators possesses an adequate ability to regenerate the quantum dot sensitizer, with values of <i>k</i>_q being on similar orders of magnitude as other Co- and Cu-based redox couples employed in dye-sensitized solar cells. Ultimately, it was concluded that the increase in the lifetime of the injected electron, working in concert with increased open-circuit voltage potentials, was the source of the significantly improved power conversion efficiencies