Studies on the interactions of 3,6‐diaminoacridine derivatives with human serum albumin by fluorescence spectroscopy

This study reports the preparation and investigation of the modes of binding of the two symmetric 3,6‐diaminoacridine derivatives obtained from proflavine, which are 3,6‐diphenoxycarbonyl aminoacridine and 3,6‐diethoxycarbonyl aminoacridine to human serum albumin (HSA). The interaction of HSA with the derivatives was investigated using fluorescence quenching and ultraviolet‐visible absorption spectra at pH 7.2 and different temperatures. The results suggest that the derivatives used can interact strongly with HSA and are the formation of HSA‐derivative complexes and hydrophobic interactions as the predominant intermolecular forces in stabilizing for each complex. The Stern‐Volmer quenching constants, binding constants, binding sites and corresponding thermodynamic parameters ΔH, ΔS and ΔG were calculated at different temperatures. The binding distance (r) ~ 3 nm between the donor (HSA) and acceptors (3,6‐diethoxycarbonyl aminoacridine, 3,6‐diphenoxycarbonyl aminoacridine and proflavine) was obtained according to Förster's non‐radiative energy transfer theory. Moreover, the limit of detection and limit of quantification of derivatives were calculated in the presence of albumin. Copyright © 2014 John Wiley & Sons, Ltd.     

Degradation of polyester polyurethane by a newly isolated soil bacterium, Bacillus subtilis strain MZA-75

A polyurethane (PU) degrading bacterial strain MZA-75 was isolated from soil through enrichment technique. The bacterium was identified through 16S rRNA gene sequencing, the phylogenetic analysis indicated the strain MZA-75 belonged to genus Bacillus having maximum similarity with Bacillus subtilis strain JBE0016. The degradation of PU films by strain MZA-75 in mineral salt medium (MSM) was analyzed by scanning electron microscopy (SEM), fourier transform infra-red spectroscopy (FT-IR) and gel permeation chromatography (GPC). SEM revealed the appearance of widespread cracks on the surface. FTIR spectrum showed decrease in ester functional group. Increase in polydispersity index was observed in GPC, which indicates chain scission as a result of microbial treatment. CO₂ evolution and cell growth increased when PU was used as carbon source in MSM in Sturm test. Increase in both cell associated and extracellular esterases was observed in the presence of PU indicated by p-Nitrophenyl acetate (pNPA) hydrolysis assay. Analysis of cell free supernatant by gas chromatography–mass spectrometry (GC–MS) revealed that 1,4-butanediol and adipic acid monomers were produced. Bacillus subtilis strain MZA-75 can degrade the soft segment of polyester polyurethane, unfortunately no information about the fate of hard segment could be obtained. Growth of strain MZA-75 in the presence of these metabolites indicated mineralization of ester hydrolysis products into CO₂ and H₂O.     

The kinase VRK1 is required for normal meiotic progression in mammalian oogenesis

The kinase VRK1 has been implicated in mitotic and meiotic progression in invertebrate species, but whether it mediates these events during mammalian gametogenesis is not completely understood. Previous work has demonstrated a role for mammalian VRK1 in proliferation of male spermatogonia, yet whether VRK1 plays a role in meiotic progression, as seen in Drosophila, has not been determined. Here, we have established a mouse strain bearing a gene trap insertion in the VRK1 locus that disrupts Vrk1 expression. In addition to the male proliferation defects, we find that reduction of VRK1 activity causes a delay in meiotic progression during oogenesis, results in the presence of lagging chromosomes during formation of the metaphase plate, and ultimately leads to the failure of oocytes to be fertilized. The activity of at least one phosphorylation substrate of VRK1, p53, is not required for these defects. These results are consistent with previously defined functions of VRK1 in meiotic progression in Drosophila oogenesis, and indicate a conserved role for VRK1 in coordinating proper chromosomal configuration in female meiosis.     

Embryonic poly(A)-binding protein (EPAB) is required for oocyte maturation and female fertility in mice

Gene expression during oocyte maturation and early embryogenesis up to zygotic genome activation requires translational activation of maternally-derived mRNAs. EPAB [embryonic poly(A)-binding protein] is the predominant poly(A)-binding protein during this period in Xenopus, mouse and human. In Xenopus oocytes, ePAB stabilizes maternal mRNAs and promotes their translation. To assess the role of EPAB in mammalian reproduction, we generated Epab-knockout mice. Although Epab(-/-) males and Epab(+/-) of both sexes were fertile, Epab(-/-) female mice were infertile, and could not generate embryos or mature oocytes in vivo or in vitro. Epab(-/-) oocytes failed to achieve translational activation of maternally-stored mRNAs upon stimulation of oocyte maturation, including Ccnb1 (cyclin B1) and Dazl (deleted in azoospermia-like) mRNAs. Microinjection of Epab mRNA into Epab(-/-) germinal vesicle stage oocytes did not rescue maturation, suggesting that EPAB is also required for earlier stages of oogenesis. In addition, late antral follicles in the ovaries of Epab(-/-) mice exhibited impaired cumulus expansion, and a 8-fold decrease in ovulation, associated with a significant down-regulation of mRNAs encoding the EGF (epidermal growth factor)-like growth factors Areg (amphiregulin), Ereg (epiregulin) and Btc (betacellulin), and their downstream regulators, Ptgs2 (prostaglandin synthase 2), Has2 (hyaluronan synthase 2) and Tnfaip6 (tumour necrosis factor α-induced protein 6). The findings from the present study indicate that EPAB is necessary for oogenesis, folliculogenesis and female fertility in mice.     

Hemodynamic effects of perioperative stressor events during rhinoplasty

The hemodynamic effects of perioperative stressors, including preoperative patient anxiety, intraoperative local anesthetic/adrenaline infiltrations, and some painful interventions, have not been fully elucidated in plastic surgery procedures. The present study was designed to determine the hemodynamic effects of perioperative stressor events in American Society of Anesthesiologists class I patients undergoing rhinoplasty procedures under general anesthesia. The study included 50 healthy patients, 18 to 51 years of age (mean age, 27 +/- 7 years), who underwent a rhinoplasty procedure in the authors' department. All patients were connected to a digital ambulatory Holter recorder for 24 hours starting on the day before the operation and continuing throughout the procedure. All of the patients received 10 ml of 2% lidocaine with 1:80,000 adrenaline 15 minutes after intubation. Observations consisted of heart rate, noninvasive blood pressure, and power spectral heart rate variability analyses, the latter of which is indicative of the sympathovagal balance of the patients. The majority of patients developed a persistent, moderate sinus tachycardia before the induction of anesthesia. After the infiltration of lidocaine/adrenaline, a mild to moderate and short-lasting tachycardia was detected. A similar increase in pulse rate was also noticed during lateral osteotomies. No significant blood pressure changes attributable to perioperative stressors (with the exclusion of general anesthesia induction, intubation, and extubation) were observed. Sympathetic activity was found to be responsible from marked tachycardia before the induction, which was attributable to preoperative anxiety. The authors' study has demonstrated that there are three hemodynamically unstable periods causing tachycardia for rhinoplasty patients that directly concern the plastic surgeon: immediate preoperative anxiety, local anesthetic/adrenaline injection, and lateral osteotomies. The authors conclude that these patients would benefit from routine use of premedications and that a lidocaine/adrenaline combination is a safe adjunct to general anesthesia in young rhinoplasty patients. In addition, a deeper anesthesia during local infiltration and osteotomies would be appropriate.