T3SS and alginate biosynthesis of Pseudomonas aeruginosa impair healing of infected rabbit wounds.

Pseudomonas aeruginosa (a Gram-negative bacterium) is an opportunistic pathogen found in many infected wounds and is known to impair healing. To test the hypothesis that knocking out P. aeruginosa genes that are overexpressed during wound infection can cripple a pathogen's ability to impair healing, we assessed two pathways: the Type III secretion system (T3SS) and alginate biosynthesis. We generated single- and double-mutant strains of ExsA (T3SS activator), AlgD (GDP- mannose 6-dehydrogenase of alginate biosynthesis) and their complemented strains and evaluated their pathogenicity in a rabbit ear full-thickness excision-wound infection model. Wounds were inoculated with different strains (wild type, mutants, and complementary strains) at 106 CFU/wound on post-wounding day 3. After 24 h, 5 days and 9 days post-infection, wounds were harvested for measuring bacterial counts (viable and total) and wound healing (epithelial gap). On day 9 post-infection, the viable counts of the double mutant, (exsA/algD)‾ were 100-fold lower than the counts of the wild type (PAO1), single mutants, or the complement double-mutant, (exsA/algD)‾/+. Also, when compared to wounds infected with wild type or control strains, wounds infected with the double-knockout mutant was less inhibitory to wound healing (p < 0.05). Additionally, the double mutant showed greater susceptibility to macrophage phagocytosis in vitro than all other strains (p < 0.001). In conclusion, compared to single gene knockouts, double knockout of virulence genes in T3SS pathway and alginate biosynthesis pathway is more effective in reducing P. aeruginosa pathogenicity and its ability to impair wound healing. This study highlights the necessity of a dual-targeted anti-virulence strategy to improve healing outcomes of P. aeruginosa-infected wounds.

Short-Chain Fatty Acids Alter Metabolic and Virulence Attributes of Borrelia burgdorferi.

Borrelia burgdorferi responds to a variety of host-derived factors and appropriately alters its gene expression for adaptation under different host-specific conditions. We previously showed that various levels of acetate, a short-chain fatty acid (SCFA), altered the protein profile of B. burgdorferi In this study, we determined the effects of other physiologically relevant SCFAs in the regulation of metabolic/virulence-associated proteins using mutant borrelial strains. No apparent increase in the synthesis of outer surface protein C (OspC) was noted when a carbon storage regulator A (csrA of B. burgdorferi, or csrABb ) mutant (mt) was propagated within dialysis membrane chambers implanted within rat peritoneal cavity, while the parental wild type (wt; B31-A3 strain) and csrABb cis-complemented strain (ct) had increased OspC with a reciprocal reduction in OspA levels. Growth rates of wt, mt, ct, 7D (csrABb mutant lacking 7 amino acids at the C terminus), and 8S (csrABb with site-specific changes altering its RNA-binding properties) borrelial strains were similar in the presence of acetate. Increased levels of propionate and butyrate reduced the growth rates of all strains tested, with mt and 8S exhibiting profound growth deficits at higher concentrations of propionate. Transcriptional levels of rpoS and ospC were elevated on supplementation of SCFAs compared to those of untreated spirochetes. Immunoblot analysis revealed elevated levels of RpoS, OspC, and DbpA with increased levels of SCFAs. Physiological levels of SCFAs prevalent in select human and rodent fluids were synergistic with mammalian host temperature and pH to increase the levels of aforementioned proteins, which could impact the colonization of B. burgdorferi during the mammalian phase of infection.

Antioxidant activity of Arthritin--a polyherbal formulation.

In complete freund's adjuvant induced arthritis in male albino rats, a significant increase in serum lipid peroxidase besides increase in paw swelling and a significant decrease in superoxide dismutase, glutathione peroxidase and total reduced glutathione levels were observed. Arthritin produced a marked reversal of these enzyme levels, besides a significant reduction in paw swelling. The results suggest that, the polyherbal formulation 'Arthritin' exerts its effects by modulating lipid peroxidation and enhancing anti-oxidant and detoxifying enzyme systems.

Epidemic dropsy in the eastern region of Nepal.

Twenty-six persons from five families comprising 34 members residing in different areas of Saptari district of the eastern region of Nepal developed symptoms of epidemic dropsy over 6-8 weeks. Seventeen patients were studied during July-August 1996. The age of affected individuals varied from 3 to 75 years. Members who had not consumed food cooked in mustard oil or who were not residing with the family were spared. Mustard oil, which was used for cooking, was found to be contaminated with oil of Argemone mexicana seeds. Sanguinarine was detected in all mustard oil samples collected from the homes of affected families. Gastrointestinal symptoms were present in 82 per cent of cases a week or so prior to the onset of pedal oedema. Pitting oedema of the lower limbs, fever, and darkening of the skin were the most consistent features, found in all cases. Other prominent features such as local erythema (82 per cent) and tenderness (88 per cent) of the lower limbs were present in most cases. Two striking features not previously noted were perianal itching (100 per cent) and severe carditis (35 per cent) with congestive cardiac failure (29 per cent). Other unique features noted were 'sarcoid' skin changes (18 per cent), bilateral pleural effusion, and Roth's spots and subhyloid haemorrhages in the fundus in one patient. Other important findings were anaemia (88 per cent), hepatomegaly (41 per cent), pneumonia (35 per cent) and ascites (12 per cent). There were no deaths due to epidemic dropsy. In the majority of cases, oedema, cutaneous changes, and carditis showed a marked improvement in 2-3 weeks and patients were well after 6-8 weeks of follow-up.