Engineering and validation of a novel lipid thin film for biomembrane modeling in lipophilicity determination of drugs and xenobiotics

Background  

Determination of lipophilicity as a tool for predicting pharmacokinetic molecular behavior is limited by the predictive power of available experimental models of the biomembrane. There is current interest, therefore, in models that accurately simulate the biomembrane structure and function. A novel bio-device; a lipid thin film, was engineered as an alternative approach to the previous use of hydrocarbon thin films in biomembrane modeling.     

Meiotic competence and acetylation pattern of UV light classified mouse antral oocytes after meiotic arrest with isobutylmethylxanthine

Chromatin transformation from a diffused or NSN configuration to a compacted or SN shape that forms a ring around the nucleolus is regarded as one of the modifications necessary for successful embryonic development. But the process of the transformation is poorly understood. In this study we cultured mouse antral oocytes under meiotic arrest with IBMX for periods between 3 and 24 hr. We observed the chromatin status of the oocytes before and after culture under UV illumination. We reported here that the NSN configured oocytes transformed temporally through an intermediate form into the SN configuration while under meiotic arrest in vitro. Meiotic rate was improved in the NSN oocytes after the meiotic arrest but decreased in the SN oocytes. We also reported that chromatin of both the NSN and SN oocytes was acetylated and the two groups underwent the same pattern of H4/K5 deacetylation during meiotic maturation. We hypothesized that the transformation of mouse oocyte from the NSN to SN type may be time rather than oocyte size specific and the abrupt deacetylation of NSN oocyte during spontaneous maturation may explain its poor meiotic and developmental competence.     

Distribution of bacteria and fungi in the earthworm Libyodrillus violaceous (Annelida: Oligochaeta), a native earthworm from Nigeria

Earthworms are soil invertebrates that play a key role in recycling organic matter in soils. In Nigeria, earthworms include Libyodrillus violaceous. Aerobic and anaerobic bacterial counts, as well as fungal counts of viable microorganisms in soils and gut sections, were made on twenty L. violaceous collected from different sites on the campus of the University of Agriculture, Abeokuta, Nigeria. The samples were collected between April and November, 2002. Numbers of microorganisms were higher in castings and gut sections than in un-ingested soil samples. The guts and their contents also had higher moisture and total nitrogen contents than the un-ingested soils. Bacteria and fungi isolated from the samples were identified by standard microbiological procedures on the bases of their morphological and biochemical characteristics. Isolated bacteria were identified as Staphylococcus, Bacillus spp., Pseudomonas aeruginosa, Streptococcus mutans, Clostridium, Spirocheata spp., Azotobacter spp., Micrococcus lylae, Acinetobacter spp., Halobacterium for bacteria. Yeast isolates were identified as Candida spp., Zygosaccharomyces spp., Pichia spp., and Saccharomyces spp while molds were identified as, Aspergillus spp., Pytium spp., Penicillium spp., Fusarium spp and Rhizopus spp. Of the five locations examined, the refuse dump area had the highest numbers of both aerobic and anaerobic organisms, followed by the arboretum while the cultivated land area recorded the lowest counts. The higher numbers of microorganisms observed in the gut sections and casts of the earthworms examined in this work reinforce the general concept that the gut and casts of earthworms show higher microbial diversity and activity than the surrounding soil.     

Identification of a Novel Cell Death Receptor Mediating IGFBP-3-induced Anti-tumor Effects in Breast and Prostate Cancer

Insulin-like growth factor-binding protein-3 (IGFBP-3), a major regulator of endocrine actions of IGFs, is a p53-regulated potent apoptotic factor and is significantly suppressed in a variety of cancers. Recent epidemiologic studies suggest that IGFBP-3 contributes to cancer risk protection in a variety of cancers, and a polymorphic variation of IGFBP-3 influences cancer risk, although other studies vary in their conclusions. Some antiproliferative actions of IGFBP-3 have been reported to be independent of IGFs, but the precise biochemical/molecular mechanisms of IGF-independent, antiproliferative actions of IGFBP-3 are largely unknown. Here we report a new cell death receptor, IGFBP-3R, that is a single-span membrane protein and binds specifically to IGFBP-3 but not other IGFBP species. Expression analysis of IGFBP-3 and IGFBP-3R indicates that the IGFBP-3/IGFBP-3R axis is impaired in breast and prostate cancer. We also provide evidence for anti-tumor effect of IGFBP-3R in vivo using prostate and breast cancer xenografts in athymic nude mice. Further in vitro studies demonstrate that IGFBP-3R mediates IGFBP-3-induced caspase-8-dependent apoptosis in various cancer cells. Knockdown of IGFBP-3R attenuated IGFBP-3-induced caspase activities and apoptosis, whereas overexpression of IGFBP-3R enhanced IGFBP-3 biological effects. IGFBP-3R physically interacts and activates caspase-8, and knockdown of caspase-8 expression or activity inhibited IGFBP-3/IGFBP-3R-induced apoptosis. Here, we propose that IGFBP-3R represents a novel cell death receptor and is essential for the IGFBP-3-induced apoptosis and tumor suppression. Thus, the IGFBP-3/IGFBP-3R axis may provide therapeutic and prognostic value for the treatment of cancer.     

Age‐dependent dystonia in striatal Gγ7 deficient mice is reversed by the dopamine D2 receptor agonist pramipexole

Gγ7 is enriched in striatum and forms a heterotrimeric complex with Gα_olf/Gβ, which is coupled to D1 receptor (D1R). Here, we attempted to characterize the pathophysiological, neurochemical, and pharmacological features of mice deficient of Gγ7 gene. Gγ7 knockout mice exhibited age‐dependent deficiency in rotarod behavior and increased dystonia‐like clasping reflex without loss of striatal neurons. The neurochemical basis for the motor manifestations using immunoblot analysis revealed increased levels of D1R, ChAT and NMDA receptor subunits (NR1 and NR2B) concurrent with decreased levels of D2R and Gα_olf, possibly because of the secondary changes of decreased Gα_olf/Gγ7‐mediated D1R transmission. These behavioral and neurochemical changes are closely related to those observed in Huntington's disease (HD) human subjects and HD model mice. Taking advantage of the finding of D2R down‐regulation in Gγ7 knockout mice and the dopamine‐mediated synergistic relationship in the control of locomotion between D2R‐striatopallidal and D1R‐stritonigral neurons, we hypothesized that D2‐agonist pramipexole would reverse behavioral dyskinesia caused by defective D1R/Gα_olf signaling. Indeed, the rotarod deficiency and clasping reflex were reversed by pramipexole treatment under chronic administration. These findings suggest that Gγ7 knockout mice could be a new type of movement disorders, including HD and useful for the evaluation of therapeutic candidates.     

Human furin Cys198 imposes dihedral and positional restraints on His194 for optimal Ser386-proton transfer

Inhibitors of human furin may represent the clinical remedy for very aggressive cancer, viral, and bacterial infections. Most of the currently available inhibitors are weak in terms of potency, drug-likeness, and furin specificity thereby necessitating the development of newer compounds especially mechanism-based inhibitors. Here, the roles of active site Cys198 (C198), His194 (H194), and Ser386 (S386) were investigated using computational-site-directed mutagenesis and molecular dynamics (MD) simulation. Data were obtained from six (6) biosystems: wildtype (C198/S386), furin-C198G (S386), furin-S386G (C198), and their peptide (nascent hydrolyzed peptide H₂N-RTRR-CO₂) bound complexes. The results strongly supported that in wildtype furin but not S386G and C198G mutants, following S386/scissile carbon attack (4.0 Å), the peptide retracted from the active site, representing peptide release post hydrolysis. Furthermore, in S386G mutant, C194 side chain thiolate ion may act as the nucleophile replacement but competing electron-rich centers (H194, H364) and energetically unattainable geometric strain on the peptide may constitute the limiting factors. In biosystems not complexed with peptide (representative of pre-attack state), C198 preferentially engaged H194 imidazole moiety via sulfur–π bond system causing a dihedral and positional restraints on the imidazole ring for ultimate alignment of its NE2 hydrogen atom with the side chain enolate oxygen of S364 required for optimal proton transfer. In summary, small-molecular-weight compounds with dual serine and cysteine protease inhibitory actions may represent a new class of potent and furin-selective compounds for future clinical applications.     

Genomic and epidemiological characteristics of SARS-CoV-2 in Africa

Since late 2019, the coronavirus disease 2019 (COVID-19) outbreak, caused by SARS-CoV-2, has rapidly evolved to become a global pandemic. Each country was affected but with a varying number of infected cases and mortality rates. Africa was hit late by the pandemic but the number of cases rose sharply. In this study, we investigated 224 SARS-CoV-2 genome sequences from the Global Initiative on Sharing Avian Influenza Data (GISAID) in the early part of the outbreak, of which 69 were from Africa. We analyzed a total of 550 mutations by comparing them with the reference SARS-CoV-2 sequence from Wuhan. We classified the mutations observed based on country and region, and afterwards analyzed common and unique mutations on the African continent as a whole. Correlation analyses showed that the duo variants ORF1ab/RdRp 4715L and S protein 614G variants, which are strongly linked to fatality rate, were not significantly and positively correlated with fatality rates (r = -0.03757, P = 0.5331 and r = -0.2876, P = 0.6389, respectively), although increased number of cases correlated with number of deaths (r = 0.997, P = 0.0002). Furthermore, most cases in Africa were mainly imported from American and European countries, except one isolate with no mutation and was similar to the original isolate from Wuhan. Moreover, unique mutations specific to countries were identified in the early phase of the outbreak but these mutations were not regional-specific. There were common mutations in all isolates across the continent as well as similar isolate-specific mutations in different regions. Our findings suggest that mutation is rapid in SARS-CoV-2 in Africa and although these mutations spread across the continent, the duo variants could not possibly be the sole cause of COVID-19 deaths in Africa in the early phase of the outbreak.     

Clinical implication of pretreatment neutrophil to lymphocyte ratio in soft tissue sarcoma

Introduction: Elevated neutrophil to lymphocyte ratio has been identified as a prognostic indicator in malignancies whereas; its association with extremity and trunk soft tissue sarcoma remain unclear. The aim of this study is to determine the utility of full blood neutrophil lymphocyte ratio (NLR) in preoperative diagnosis and its predictive value for survival in patients managed for soft tissue sarcoma of the trunk and extremities. Method: 223 patients who presented with a soft tissue tumor were retrospectively reviewed. The study period was from January 2002-December 2009. Preoperative NLR as well as demographics, clinical and histopathological data were analysed. Results: Full blood NLR was significantly higher in patient with a soft tissue sarcoma compared to benign soft tissue tumors (p < 0.001). Cox regression analysis demonstrated that elevated NLR >5 (p < 0.05) may be an adverse prognostic factor for Overall Survival. Conclusion: The preoperative NLR is a simple, investigation predicting the preoperative diagnosis of a soft tissue sarcoma and a predictor of worse overall survival for patient with a soft tissue sarcoma.