Nonclinical Safety Assessment of SYN-004: An Oral ß-lactamase for the Protection of the Gut Microbiome From Disruption by Biliary-Excreted, Intravenously Administered Antibiotics.

SYN-004 is a first in class, recombinant ß-lactamase that degrades ß-lactam antibiotics and has been formulated to be administered orally to patients receiving intravenous ß-lactam antibiotics including cephalosporins. SYN-004 is intended to degrade unmetabolized antibiotics excreted into the intestines and thus has the potential to protect the gut microbiome from disruption by these antibiotics. Protection of the gut microbiome is expected to protect against opportunistic enteric infections such as Clostridium difficile infection as well as antibiotic-associated diarrhea. In order to demonstrate that oral SYN-004 is safe for human clinical trials, 2 Good Laboratory Practice-compliant toxicity studies were conducted in Beagle dogs. In both studies, SYN-004 was administered orally 3 times per day up to the maximum tolerated dose of the formulation. In the first study, doses of SYN-004 administered over 28 days were safe and well tolerated in dogs with the no-observed-adverse-effect level at the high dose of 57 mg/kg/day. Systemic absorption of SYN-004 was minimal and sporadic and showed no accumulation during the study. In the second study, doses up to 57 mg/kg/day were administered to dogs in combination with an intravenous dose of ceftriaxone (300 mg/kg) given once per day for 14 days. Coadministration of oral SYN-004 with intravenous ceftriaxone was safe and well tolerated, with SYN-004 having no noticeable effect on the plasma pharmacokinetics of ceftriaxone. These preclinical studies demonstrate that SYN-004 is well tolerated and, when coadministered with ceftriaxone, does not interfere with its systemic pharmacokinetics. These data supported advancing SYN-004 into human clinical trials.

Exploiting a bacterial drug-resistance mechanism: a light-activated construct for the destruction of MRSA.

A cunning and dangerous plan foiled! An enzyme-specific molecular construct exploits the overexpression of beta-lactamase in several drug-resistant bacteria. Specific photodynamic toxicity was detected towards beta-lactam-resistant methicillin-resistant Staphylococcus aureus (MRSA), whereby the usual mechanism for antibiotic resistance (cleavage of the beta-lactam ring) releases the phototoxic component from the prodrug (see picture; Q = quencher).

Tp47 induces cell death involving autophagy and mTOR in human microglial HMO6 cells.

BACKGROUND: Tp47 can induce immune cells to produce numerous inflammatory factors, some of which can trigger autophagy. Increased autophagy has a dual effect on cell survival. However, whether Tp47 induces autophagy in microglia is unknown. OBJECTIVE: To evaluate the potential role of Tp47 in microglia. METHODS: After treatment with Tp47, autophagy-related proteins were assessed in HMO6 human microglial cells by flow cytometry, Western blotting and immunofluorescence. Cell death was assessed by flow cytometry and trypan blue staining. Changes in mTOR pathway proteins were explored by using Western blotting. RESULTS: After treatment with Tp47, a gradual increase in total LC3 expression was observed as a dose- and time-dependent accumulation of its active form, LC3-II (P < 0.05), but P62 expression was downregulated (P < 0.05). Moreover, microglial mortality gradually increased in a dose- and time-dependent manner. 3-Methyladenine (3-MA), a specific inhibitor of PI3KC3, reversed autophagy and cell death. The mortality rate of HMO6 microglial cells treated with Tp47 was approximately 13.7 ±â€¯2%, and the basal expression of p-mTOR, p-p70s6k and p-S6 in these cells was significantly downregulated by Tp47. Moreover, the mortality rate of microglia was significantly reduced after mTOR agonist intervention. CONCLUSION: In human microglial HMO6 cells, Tp47 induces autophagy- and mTOR pathway-dependent cell death.

Preliminary ecotoxicity hazard evaluation of DOPO-HQ as a potential alternative to halogenated flame retardants.

Recent regulatory and environmental pressures have led to increasing demands for environmentally friendly flame retardants as alternatives to halogenated flame retardants (HFRs). A new flame retardant alternative, 10-(2, 5-dihydroxyl phenyl)-9, 10-dihydro-9-oxa-10- phosphaphenanthrene-10-oxide (DOPO-HQ), was applied due to its high thermal stability and glass transition temperature. However, there is little information available for its ecotoxicology. For this purpose, the preliminary ecotoxicity of DOPO-HQ was investigated and evaluated, using aquatic, terrestrial and microorganism toxicity according to Organization for Economic Co-operation and Development (OECD) guidelines under the framework of the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) regulation. No effect was observed on Pseudokirchneriella subcapitata, Daphnia magna and Gobiocypris rarus at the saturation water solubility. For active sludge, Eisenia foetida and seedling emergence, no effect was observed at the limited highest concentration of 1000 mg/L or 1000 mg kg-1 dw. However, moderate effect on the shoot weight is observed with the maximum inhibition rate of 46.3% when exposed to 1000 mg kg-1 dw. Comparing the ecotoxicity of DOPO-HQ with that of HFRs and their typical alternatives, the toxicity of DOPO-HQ is markedly lower than those of triphenyl phosphate (TPP) and HFRs such as tris(2-chloro-1-methylethyl) phosphate (TCPP), tris(1,3-dichloro-2-propyl) phosphate (TDCCP), tris(2-chloroethyl) phosphate (TCEP) and tetrabromobisphenol A (TBBPA). Similar low effect levels were observed for resorcinol bis (biphenyl) phosphate (RDP), bisphenol A bis (biphenyl) phosphate (BDP) and its parent chemical 9, 10-dihydro-9-oxa-10-phosphaphenanthrene -10-oxide (DOPO). DOPO-HQ could be a potential alternative to HFRs from an environmental perspective.