N-Phenyl-4-hydroxy-2-quinolone-3-carboxamides as selective inhibitors of mutant H1047R phosphoinositide-3-kinase (PI3Kα)

This work describes our efforts to optimize the lead PI3Kα inhibitor N-benzyl 4-hydroxy-2-quinolone-3-carboxamide using structure-based design and molecular docking. We identified a series of N-phenyl 4-hydroxy-2-quinolone-3-carboxamides as selective inhibitors of mutant H1047R versus wild-type PI3Kα and we also showed that the cell growth inhibition by these compounds likely occurs by inhibiting the formation of pAKT and induction of apoptosis.     

Simultaneous determination of flupirtine and its major active metabolite in human plasma by liquid chromatography–tandem mass spectrometry

A rapid, selective and sensitive HPLC–tandem mass spectrometry method was developed and validated for simultaneous determination of flupirtine and its active metabolite D-13223 in human plasma. The analytes and internal standard diphenhydramine were extracted from plasma samples by liquid–liquid extraction, and chromatographed on a C₁₈ column. The mobile phase consisted of acetonitrile–water–formic acid (60:40:1, v/v/v), at a flow rate of 0.5 ml/min. Detection was performed on a triple quadrupole tandem mass spectrometer by selected reaction monitoring (SRM) mode via atmospheric pressure chemical ionization (APCI). The method has a limit of quantitation of 10 ng/ml for flupirtine and 2 ng/ml for D-13223, using 0.5-ml plasma sample. The linear calibration curves were obtained in the concentration range of 10.0–1500.0 ng/ml for flupirtine and 2.0–300.0 ng/ml for D-13223. The intra- and inter-run precision (RSD), calculated from quality control (QC) samples was less than 7.2% for flupirtine and D-13223. The accuracy as determined from QC samples was less than 5% for the analytes. The overall extraction recoveries of flupirtine and D-13223 were determined to be about 66% and 78% on average, respectively. The method was applied for the evaluation of the pharmacokinetics of flupirtine and active metabolite D-13223 in volunteers following peroral administration.     

Structural, photophysical and theoretical studies of two dodecachlorinated porphyrins

Two dodecachlorinated porphyrins, 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra(4-chlorophenyl)porphyrin free base (TCl₁₂PPH₂) and its nickel compound (TCl₁₂PPNi), have been synthesized. Single-crystal X-ray diffraction analysis shows that porphyrin rings are heavily distorted and exhibit saddled conformations. The Soret and Q bands of two compounds are red-shifted compared to their non-chlorinated counterparts. Theoretical calculations reveal that the optical band gap of TCl₁₂PPH₂ is reduced, whereas that of TCl₁₂PPNi remains almost the same as to its non-chlorinated nickel compound due to the concurrent lowering of HOMO and LUMO energy levels. The frontier molecular orbitals are degenerated due to the decrease of symmetry of the molecules.     

The Medical System in Ghana

Ghana is a developing country in West Africa with a population of about 25 million. Medical illnesses in Ghana overlap with those in developed countries, but infection, trauma, and women’s health problems are much more prominent. Medical practice in rural Africa faces extremely limited resources, a multiplicity of languages (hundreds in Ghana), and presentation of severe illnesses at later stages than seen elsewhere. Despite these limitations, Ghana has established a relatively successful national medical insurance system, and the quality of medical practice is high, at least where it is available. Ghana also has a well-established and sophisticated administrative structure for the supervision of medical education and accreditation, but it has proven very difficult to extend medical training to rural areas, where health care facilities are particularly short of personnel. Physicians are sorely needed in rural areas, but there are few because of the working conditions and financial limitations. Hospital wards and clinics are crowded; time per patient is limited. This article details some of the differences between medical practice in Ghana and that in wealthier countries and how it functions with very limited resources. It also introduces the medical education and training system in Ghana. The following article describes an attempt to establish and maintain a residency training program in General Medicine in a rural area of Ghana.     

Phosphorylation of elF-4E and initiation of protein synthesis in P19 embryonal carcinoma cells

Mitogenic stimulation of protein synthesis is accompanied by an increase in elF-4E phosphorylation. The effect on protein synthesis by induction of differentiation is less well known. We treated P19 embryonal carcinoma cells with the differentiating agent retinoic acid and found that protein synthesis increased during the first hour of addition. However, the phosphorylation state, as well as the turnover of phosphate on elF-4E, remained unchanged. Apparently, the change in protein synthesis after RA addition is regulated by another mechanism than elF-4E phosphorylation. By using P19 cells overexpressing the EGF receptor, we show that the signal transduction pathway that leads to phosphorylation of elF-4E is present in P19 cells; the EGF-induced change in phosphorylation of elF-4E in these cells is likely to be regulated by a change in elF-4E phosphatase activity. These results suggest that the onset of retinoic acid-induced differentiation is triggered by a signal transduction pathway which involves changes in protein synthesis, but not elF-4E phosphorylation. © 1995 Wiley-Liss, Inc.     

Functional RelBE-Family Toxin-Antitoxin Pairs Affect Biofilm Maturation and Intestine Colonization in Vibrio cholerae

Toxin–antitoxin (TA) systems are small genetic elements that typically encode a stable toxin and its labile antitoxin. These cognate pairs are abundant in prokaryotes and have been shown to regulate various cellular functions. Vibrio cholerae, a human pathogen that is the causative agent of cholera, harbors at least thirteen TA loci. While functional HigBA, ParDE have been shown to stabilize plasmids and Phd/Doc to mediate cell death in V. cholerae, the function of seven RelBE-family TA systems is not understood. In this study we investigated the function of the RelBE TA systems in V. cholerae physiology and found that six of the seven relBE loci encoded functional toxins in E. coli. Deletion analyses of each relBE locus indicate that RelBE systems are involved in biofilm formation and reactive oxygen species (ROS) resistance. Interestingly, all seven relBE loci are induced under the standard virulence induction conditions and two of the relBE mutants displayed a colonization defect, which was not due to an effect on virulence gene expression. Although further studies are needed to characterize the mechanism of action, our study reveals that RelBE systems are important for V. cholerae physiology.     

Cytoplasmic APE1 promotes resistance response in osteosarcoma patients with cisplatin treatment

Chemotherapy resistance has become a hold back and major clinical challenge in osteosarcoma cancer. The alteration and subcellular distribution of apurinic/apyrimidinic endonuclease 1 (APE1) has been reported to be involved in chemotherapy resistance in many cancers. Here, we report that the cytoplasmic distribution of APE1 plays a key role in the sensitivity of combination platinum chemotherapy in osteosarcoma. Interestingly, the prevalence of cisplatin-induced DNA damage and apoptosis in low cytoplasmic APE1 osteosarcoma cell lines was higher than in high expression of cytoplasmic APE1 cell lines. Overexpression of cytoplasmic APE1 protected the osteosarcoma cells from CDDP-induced apoptosis. In addition, clinical data also show that the level of cytoplasmic APE1 was negatively associated with sensitivity to combination chemotherapy of cisplatin in osteosarcoma patients. Our findings suggest that cytoplasmic APE1 plays a significant role in chemotherapy resistance. This role is a supplement to the extranuclear function of APE1, and cytoplasmic APE1 expression level could be a promising predictor of platinum treatment prognosis for osteosarcoma patients.