Derry Mercer

Identification, expression, and tissue distribution of the three rat lysyl hydroxylase isoforms

Lysyl hydroxylases (LH) (procollagen-lysine 2-oxoglutarate 5-dioxygenase; PLOD) catalyse the hydroxylation of lysine residues during the post-translational modification of collagenous proteins. In this paper, we describe the first identification and cloning of LH isoforms 2 and 3 from the rat, including both LH2 splice variants (LH2a and LH2b). The rat LHs are expressed in almost all tissue and cell types examined, indicating a probable lack of tissue specificity for LH function. All LH isoforms were stably transfected into CHO-K1 cells and this represents the first example of recombinant LH production in a eukaryotic cell line. Expression and production of all LH isoforms led to an increase in total collagen synthesis. LH1 and LH2a expression and production led to an increase in total pyridinium cross-link production. Evidence that LH2a possesses telopeptide lysyl hydroxylase activity, previously thought to be a novel enzyme, is presented.

Novel Tetracycline Resistance Gene,tet(32), in the Clostridium-Related Human Colonic Anaerobe K10 and Its Transmission In Vitro to the Rumen Anaerobe Butyrivibrio fibrisolvens

ABSTRACT A novel tetracycline resistance gene, designatedtet(32), which confers a high level of tetracycline resistance, was identified in the Clostridium-related human colonic anaerobe K10, which also carries tet(W).tet(32) was transmissible in vitro to the rumen anaerobeButyrivibrio fibrisolvens2221R. The predicted gene product oftet(32) has 76% amino acid identity with Tet(O). PCR amplification indicated that tet(32) is widely distributed in the ovine rumen and in porcine feces.

Activity of Cysteamine against the Cystic Fibrosis Pathogen, Burkholderia cepacia Complex

ABSTRACT There are no wholly successful chemotherapeutic strategies against Burkholderia cepacia complex (BCC) colonization in cystic fibrosis (CF). We assessed the impact of cysteamine (Lynovex) in combination with standard-of-care CF antibiotics in vitro against BCC CF isolates by the concentration at which 100% of bacteria were killed (MIC100) and checkerboard assays under CLSI standard conditions. Cysteamine facilitated the aminoglycoside-, fluoroquinolone- and folate pathway inhibitor-mediated killing of BCC organisms that were otherwise resistant or intermediately sensitive to these antibiotic classes. Slow-growing BCC strains are often recalcitrant to treatment and form biofilms. In assessing the impact of cysteamine on biofilms, we demonstrated inhibition of BCC biofilm formation at sub-MIC100s of cysteamine.

Identification, expression and tissue distribution of the three rat lysyl hydroxylase isoforms

Introduction  Lysyl hydroxylases (LHs) (procollagen‐lysine 2‐oxoglutarate 5‐dioxygenase; PLOD) catalyse the hydroxylation of lysine residues during the post‐translational modification of collagenous proteins.

NP108, an Antimicrobial Polymer with Activity against Methicillin- and Mupirocin-Resistant Staphylococcus aureus

ABSTRACT Staphylococcus aureus is a clinically significant human pathogen that causes infectious diseases ranging from skin and soft tissue infections (SSTI) and health care-associated infections (HAI) to potentially fatal bacteremia and endocarditis. Nasal carriage of S. aureus, especially for persistent carriage, is associated with an increased risk of subsequent infection, particularly nosocomial and surgical site infections (SSI), usually via autoinfection. NP108 is a cationic antimicrobial polymer composed of generally recognized as safe (GRAS) amino acid building blocks. NP108 is broad spectrum and rapidly bactericidal (3-log kill in ≤3 h), killing bacteria by membrane disruption and cell lysis. NP108, contrary to many antibiotics, shows equally effective antimicrobial activity against a variety of S. aureus (MIC100 = 8 to 500 mg/liter) and S. epidermidis (MIC100 = 4 to 8 mg/liter) isolates, whether exponentially growing or in stationary phase. NP108 is antimicrobially active under nutrient-limiting conditions similar to those found in the anterior nares (MIC100 = 8 mg/liter) and kills antibiotic-resilient small colony variants (MIC100 = 32 mg/liter) and S. aureus biofilms (prevention, MIC100 = 1 to 4 mg/liter; eradication, MIC100 ≥ 31.25 mg/liter). NP108 is active against isolates of S. aureus resistant to the current standard-of-care decolonization agent, mupirocin, with no significant increase in the MIC100. NP108 is water soluble and has been formulated into compatible aqueous gel vehicles for human use in which antimicrobial efficacy is retained (2.0% [wt/vol]). NP108 is a potential nonantibiotic antimicrobial alternative to antibiotics for the nasal decolonization of S. aureus, with clear advantages in its mechanism of action over the existing gold standard, mupirocin.

Cysteamine, an Endogenous Aminothiol, and Cystamine, the Disulfide Product of Oxidation, Increase Pseudomonas aeruginosa Sensitivity to Reactive Oxygen and Nitrogen Species and Potentiate Therapeutic Antibiotics against Bacterial Infection

ABSTRACT Cysteamine is an endogenous aminothiol produced in mammalian cells as a consequence of coenzyme A metabolism through the activity of the vanin family of pantetheinase ectoenzymes. It is known to have a biological role in oxidative stress, inflammation, and cell migration. There have been several reports demonstrating anti-infective properties targeting viruses, bacteria, and even the malarial parasite. We and others have previously described broad-spectrum antimicrobial and antibiofilm activities of cysteamine. Here, we go further to demonstrate redox-dependent mechanisms of action for the compound and how its antimicrobial effects are, at least in part, due to undermining bacterial defenses against oxidative and nitrosative challenges. We demonstrate the therapeutic potentiation of antibiotic therapy against Pseudomonas aeruginosa in mouse models of infection. We also demonstrate potentiation of many different classes of antibiotics against a selection of priority antibiotic-resistant pathogens, including colistin (often considered an antibiotic of last resort), and we discuss how this endogenous antimicrobial component of innate immunity has a role in infectious disease that is beginning to be explored and is not yet fully understood.