The New Zealand white rabbit animal model of acute radiation syndrome: hematopoietic and coagulation-based parameters by radiation dose following supportive care.

PURPOSE: Animal models that accurately reflect human responses to radiation injury are needed for advanced mechanistic investigation and development of effective therapeutics. The rabbit is an established animal model accepted by the FDA for studies of cardiovascular disease, lipid metabolism, the development of anticoagulants, testing of bone implants, and the development of treatments for infectious diseases such as HIV. The purpose of this study was to investigate the New Zealand White (NZW) Rabbit model as a model of acute radiation exposure because of its established similarity to human vascular, immune, and coagulation responses. MATERIALS AND METHODS: Two sequential studies were performed in a total of 81 male NZW rabbits, 16-20 weeks of age. All animals underwent clinical observations and peripheral blood analyses following a single dose of 0, 6, 7, 8, 8.5, 9, or 10 Gy of total body irradiation via a 6 MV Linear accelerator photon source on day 0. Animals were treated with timed release fentanyl patch (days 0-30), subcutaneous hydration (day 1, Study 2 only), and oral sulfamethoxazole/trimethoprim 30 mg/kg once daily (days 3-30) and were followed for 30 days or to time of mortality. RESULTS: Study 1 revealed the estimated LD30, -50, -70, and -90 with 95% confidence intervals (CI) at 30 days to be 6.7 (CI: 5.9-7.4), 7.3 (CI: 6.7-7.8), 7.9 (CI: 7.3-8.4), and 8.8 (CI: 7.9-9.7) Gy, respectively. In study 2, a survey of blood coagulation and biochemical parameters were performed over time and necropsy. Complete blood counts taken from animals exposed to 7, 8, or 10 Gy, demonstrated dose-dependent depletion of lymphocytes, neutrophils, and platelets. Platelet counts recovered to baseline levels in survivors by day 30, whereas lymphocyte and neutrophil counts did not. Decedent animals demonstrated grade 3 or 4 neutropenia and lymphopenia at time of death; 64% of the decedents experienced a 30% or greater drop in hematocrit. Decedent animals demonstrated more than 100% increases from serum baseline levels of blood urea nitrogen, creatinine, aspartate aminotransferase, and triglyceride levels at the time of death whereas survivors on average demonstrated modest or no elevation. CONCLUSION: This NZW rabbit model demonstrates dose-dependent depletion of hematopoietic parameters. The LD50/30 of 7.8 Gy (95% CI: 6.6-8.4) with supportive care appears to be close to the ranges reported for rhesus macaques (5.25-7.44 Gy) and humans (6-8 Gy) with supportive care. These findings support the utility of the NZW rabbit model for further mechanistic investigation of acute radiation exposure and medical countermeasure testing.

Characterization of a fenpropathrin-degrading strain and construction of a genetically engineered microorganism for simultaneous degradation of methyl parathion and fenpropathrin.

A gram-negative fenpropathrin-degrading bacterial strain Sphingobium sp. JQL4-5 was isolated from the wastewater treatment sludge of an insecticide factory. Strain JQL4-5 showed the ability to degrade other pyrethroid insecticides, but it was not able to degrade methyl parathion. To enhance its degrading range of substrate, a methyl parathion hydrolase gene (mpd) was successfully introduced into the chromosome of strain JQL4-5 with a mini-Tn-transposon system. A genetically engineered microorganism (GEM) named JQL4-5-mpd resulted, which was capable of simultaneously degrading methyl parathion and fenpropathrin. Soil treatment results indicated that JQL4-5-mpd is a promising multifunctional bacterium in the bioremediation of multiple pesticide-contaminated environments.

Inhibition of Slug effectively targets leukemia stem cells via the Slc13a3/ROS signaling pathway.

Leukemia stem cells (LSCs) are the rare populations of acute myeloid leukemia (AML) cells that are able to initiate, maintain, and propagate AML. Targeting LSCs is a promising approach for preventing AML relapse and improving long-term outcomes. While Slug, a zinc-finger transcription repressor, negatively regulates the self-renewal of normal hematopoietic stem cells, its functions in AML are still unknown. We report here that Slug promotes leukemogenesis and its loss impairs LSC self-renewal and delays leukemia progression. Mechanistically, Slc13a3, a direct target of Slug in LSCs, restricts the self-renewal of LSCs and markedly prolongs recipient survival. Genetic or pharmacological inhibition of SLUG or forced expression of Slc13a3 suppresses the growth of human AML cells. In conclusion, our studies demonstrate that Slug differentially regulates self-renewal of LSCs and normal HSCs, and both Slug and Slc13a3 are potential therapeutic targets of LSCs.

Selective Expansion of Skeletal Muscle Stem Cells from Bulk Muscle Cells in Soft Three-Dimensional Fibrin Gel.

Muscle stem cells (MuSCs) exhibit robust myogenic potential in vivo, thus providing a promising curative treatment for muscle disorders. Ex vivo expansion of adult MuSCs is highly desired to achieve a therapeutic cell dose because of their scarcity in limited muscle biopsies. Sorting of pure MuSCs is generally required for all the current culture systems. Here we developed a soft three-dimensional (3D) salmon fibrin gel culture system that can selectively expand mouse MuSCs from bulk skeletal muscle preparations without cell sorting and faithfully maintain their regenerative capacity in culture. Our study established a novel platform for convenient ex vivo expansion of MuSCs, thus greatly advancing stem cell-based therapies for various muscle disorders. Stem Cells Translational Medicine 2017;6:1412-1423.

MicroRNA-302/367 cluster governs hESC self-renewal by dually regulating cell cycle and apoptosis pathways.

miR-302/367 is the most abundant miRNA cluster in human embryonic stem cells (hESCs) and can promote somatic cell reprogramming. However, its role in hESCs remains poorly understood. Here, we studied functional roles of the endogenous miR-302/367 cluster in hESCs by employing specific TALE-based transcriptional repressors. We revealed that miR-302/367 cluster dually regulates hESC cell cycle and apoptosis in dose-dependent manner. Gene profiling and functional studies identified key targets of the miR-302/367 cluster in regulating hESC self-renewal and apoptosis. We demonstrate that in addition to its role in cell cycle regulation, miR-302/367 cluster conquers apoptosis by downregulating BNIP3L/Nix (a BH3-only proapoptotic factor) and upregulating BCL-xL expression. Furthermore, we show that butyrate, a natural compound, upregulates miR-302/367 cluster expression and alleviates hESCs from apoptosis induced by knockdown of miR-302/367 cluster. In summary, our findings provide new insights in molecular mechanisms of how miR-302/367 cluster regulates hESCs.

[Construction of a stable genetically engineered microorganism for degrading HCH & methyl parathion and its characteristics].

A GEM designated as BHC-A-mpd, capable of simultaneously degrading of methyl parathion (MP) and HCH was successfully constructed by random insertion of a methyl parathion hydrolase gene (mpd) into chromosome of a HCH-degrading strain BHC-A with the mini-Tn-transposon system. The growth and degrading characteristics of BHC-A-mpd was compared with the original strain BHC-A, and the result showed that there was no difference in this two aspects, A600 nm of BHC-A-mpd in LB medium could reach 2.5 in logarithmic period, which was the same as that of the original strain BHC-A.BHC-A-mpd showed the same HCH-degrading ability as BHC-A and could degrade 5 mg/L of gamma-HCH in 10 h. BHC-A-mpd showed high genetica stability and could degrade many kinds of organophosphorus pesticides. All these results indicated that BHC-A-mpd was a promising GEM in bioremediation of MP and HCH co-contaminated environment.

[Isolation, identification and characteristics of a phoxim-degrading bacterium XSP-1].

A bacteria strain XSP-1 capable of utilizing phoxim as sole carbon source was isolated from sludge collected from a pesticide manufacturer. It was preliminarily identified as Delftia sp. according to its physiological-biochemical analysis and the similarity analysis of its 16S rRNA gene sequence (GenBank Accession No. EF061135). Strain XSP-1 could degrade 100 mg/L phoxim within 7 h completely. The optimal pH and temperature for degradation were 7.0 and 35 degrees C respectively. The degrading rate showed a positive correlation to the initial inoculum size. Strain XSP-1 also showed good degrading performance against methyl parathion, chlorpyrifos and fenitrothion. PCR detection with degenerated primers designed according to the conserved sequences of reported mpd gene did not find target band, but it needs further study to verify whether strain XSP-1 harbors a new mpd gene.

[Bioremediation of fenpropathrin-contaminated soil by Sphingomonas sp.JQL4-5].

JQL4-5 (Sphingomonas sp.), a fenpropathrin-degrading strain isolated from soils exposed to repeated pesticides contamination, was used in this work to study factors affecting its degrading capacity of fenpropathrin in soil microcosms. In sterilized soil, the degradation rates of fenpropathrin by JQL4-5 were faster than those in unsterilized soil. Various factors, including soil pH, temperature, initial fenitrothion concentration, and inoculum size influenced its degradation efficiency. The addition of 10(6) CFU x g(-1) was able to degrade varying concentrations (10-200 mg x kg(-1) soil) of fenpropathrin over a temperature range of 20-40 degrees C and pH range (6.5 - 7.5). The results indicated that strain JQL4-5 has potential use in bioremediation of fenpropathrin-contaminated soil.

Analysis of the role of LinA and LinB in biodegradation of delta-hexachlorocyclohexane.

Commercial formulations of hexachlorocyclohexane (HCH) consist of a mixture of four isomers, alpha, beta, gamma and delta. All these four isomers are toxic and recalcitrant pollutants. Sphingobium (formerly Sphingomonas) sp. strain BHC-A is able to degrade all four HCH isomers. Eight lin genes responsible for the degradation of gamma-HCH in BHC-A were cloned and analysed for their role in the degradation of delta-HCH, and the initial conversion steps in delta-HCH catabolism by LinA and LinB in BHC-A were found. LinA dehydrochlorinated delta-HCH to produce 1,3,4,6-tetrachloro-1,4-cyclohexadiene (1,4-TCDN) via delta-pentachlorocyclohexene (delta-PCCH). Subsequently, both 1,4-TCDN and delta-PCCH are catalysed by LinB via two successive rounds of hydrolytic dechlorinations to form 2,5-dichloro-2,5-cyclohexadiene-1,4-diol (2,5-DDOL) and 2,3,5-trichloro-5-cyclohexene-1,4-diol (2,3,5-TCDL) respectively. LinB could also catalyse the hydrolytic dechlorination of delta-HCH to 2,3,5,6-tetrachloro-1,4-cyclohexanediol (TDOL) via 2,3,4,5,6-pentachlorocyclohexanol (PCHL).

[Isolation, identification and characteristics of a fenpropathrin-degrading bacterium JQL4-5].

A bacterium capable of utilizing fenpropathrin as sole carbon source was isolated from activated sludge collected from wastewater treating system of a pesticide manufacturer. This bacterium was identified as Sphingomonas sp. according to its physiological & biochemical analysis and the similarity analysis of its 16S rDNA sequence (GenBank Accession No. DQ177525). This bacterium could degrade 99.8% of 20 mg/L fenpropathrin in 24h. The optimal pH and temperature for the degradation were 7.0 and 30 degrees C, respectively. The degradation speed was related positively to initial inoculum size. The enzyme distribution experiment showed that the degrading-enzyme in the bacterium was endoenzyme.