Mouse thyroglobulin (MTg) or thyroid extract (TE) was given repeatedly to good responder C3H/Anf (H-2k) and poor responder BALB/c (H-2d) mice in the absence of adjuvant. Anti-MTg antibodies reached high levels in good responder mice given high doses of thyroid antigen. To eliminate stimulation by alloantigenic determinants and reduce the chance of denaturation. TE from syngeneic mice was prepared freshly each week and injected into good and poor responder strains. Again, significant antibody titers were observed in good responder mice. The antibody was specific for MTg since (a) it was not inhibited by extracts of other organs and (b) it reacted strongly with the closely related rat Tg and weakly with Tg from other species. Histology revealed mononuclear cell infiltration of the thyroid of good responder, but not of poor responder mice, regardless of the strain used to provide the thyroid antigen. The data demonstrate the presence of both T and B cell populations reactive with this self antigen and their stimulation by repeated high doses of antigen, without the aid of adjuvant, to override the regulatory controls that normally prevent autoimmune responses.

Background: Staphylococci are a common cause of catheter-associated urinary tract infections. The present study evaluated biofilm forming capacity and the presence of both icaA and icaD genes among staphylococci strains isolated from patients undergoing ureteral catheterization. Methodology: Different bacterial strains were isolated from urine and stents segments collected from 100 patients. Strains were identified by traditional microbiological methods. Stents were examined for biofilm using a scanning electron microscope (SEM). Staphylococcal isolates were tested for their ability to produce biofilm using the tissue culture plate assay method (TCP). The presence of icaA and icaD genes was determined by PCR technique. Results: Fifty-three staphylococcal strains were isolated and identified from 284 samples (18.7%). Forty-six staphylococcal strains were isolated from stent segment cultures while only seven strains were isolated from urine samples at the day of stent removal. S. aureus represented 6.3%, and S. epidermidis represented 12.3%. Out of the 18 S. aureus strains, 15 (83.3%) were biofilm producers and out of 35 S. epidermidis strains, 31 (88.6%) were biofilm producers. Staphylococcal strains were further classified as high (56.6%), moderate (30.2%) and non biofilm producers (13.2%). All biofilm producing strains were positive for icaA and icaD genes, and all biofilm negative strains were negative for both genes. Conclusion: Staphylococci isolated from catheter segments showed a higher extent of biofilm production than that isolated from urine samples. All biofilm producing staphylococci were positive for icaA and icaD genes, which indicates the important role of ica genes as virulence markers in staphylococcal infections associated with urinary catheterization.

Background: Ureteral catheters are valuable indispensable devices may readily acquire biofilms on the inner or outer surfaces. This study evaluated the efficacies of ureteral catheters impregnated with ciprofloxacin, N-acetylcysteine each alone and in combination on microbial adherence.Methods: Antimicrobial durability of ureteral catheters coated, through instant dip method, with ciprofloxacin were determined using modified Kirby-Bauer method. Ciprofloxacin-coated catheters showed zones of inhibition ranged from 15 to 45 mm in diameter (baseline) against nine clinical strains recently isolated from patients undergoing ureteral stent removal. Segments coated with ciprofloxacin, N-acetylcysteine each alone and in combination, through instant dip method, were incubated with the tested microorganisms, washed, sonicated, cultured and the number of viable cells were determined.Results: Ciprofloxacin-coated catheters soaked in urine and incubated at 37 °C, maintained antimicrobial activities and produce zones of inhibition that measured 2-10 mm for at least 8 weeks. Effect of ciprofloxacin and N-acetylcysteine coated catheters on microbial adherence were found to be dose dependent. Catheters impregnated with ciprofloxacin/N-acetylcysteine showed the highest inhibitory effect on microbial adherence when compared with controls (85.5%-100%).Conclusion: Catheters impregnated with ciprofloxacin, using instant dip method, were shown to have broad spectrum, prolonged antimicrobial durability and high efficacy. On the other hand, Catheters impregnated with ciprofloxacin/NAC showed the highest inhibitory effect on microbial adherence to stent surfaces.

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A simple, sensitive and specific agar cup diffusion bioassay for the antibacterial Colistin sulfate was developed. Using a strain of Escherichia coli ATCC 8739 as the test organism, Colistin sulfate at concentrations ranging from 100 to 1600 µg/ml could be measured in pharmaceuticals. A prospective validation of the method showed that the method was linear (r 2 = 0.999), precise (RSD< 2.8%) and accurate (percent recovery ranges between 98-102%). The method shows that results confirm its precision, not differing significantly from the other method described in the literature. We conclude that microbiological assay is satisfactory using Escherichia coli ATCC 8739 for quantitation of in-vitro antibacterial activity of Colistin sulfate.

Studies were initiated to define the H-2-linked genetic control of response to self-determinants of MTg. In addition to the Ir gene control of H-2K end, a modifying effect of D end was seen. The extent of regulation depended upon the derivation of the K-end Ir-Tg gene(s) as well as the D-end genes. When the Ir-Tg gene was from good responder H-2k and H-SS strains, and the H-2D-end gene from the d allele, antibody levels were moderate to high but cellular infiltration was significantly reduced. These findings demonstrate genetic interaction between I-region and D-end gene products in the response to a self-antigen, MTg.

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