Effects of in-vivo administration of taurine and HEPES on the inflammatory response in rats.

The effect of in-vivo administration of N-2-hydroxyethylpiperazine-N'-2- ethane sulphonic acid (HEPES) and taurine on rat paw oedema and reactive oxidant production was examined. Carrageenan-induced paw oedema was attenuated following intraperitoneal injection of HEPES. Chemiluminescence production by isolated peripheral blood mononuclear cells (PBMC) was reduced in HEPES-treated rats. Taurine-treated rats did not exhibit attenuation of paw oedema using subcutaneous or intraperitoneal administration but intracerebroventricular administration produced a significant reduction at a dosage of 4.0 mumol. No reduction in chemiluminescence production was observed by PBMC using subcutaneous or intraperitoneal administration of taurine, but intracerebroventricular administration produced a significant reduction at a dosage of both 0.4 and 4.0 mumol. Intravenous injection of [14C]HEPES or [3H]taurine demonstrated rapid clearance with a significantly longer half-life of HEPES compared with taurine. These results support previous reports of anti-inflammatory activity of taurine when administered centrally. The lack of anti-inflammatory effect when taurine was administered subcutaneously or intraperitoneally may be a consequence of rapid distribution or clearance. The greater anti-inflammatory effects of HEPES compared with taurine may be due to its slower distribution or clearance in-vivo.

Acute and chronic bioeffects of single and multiple doses of piezoelectric shockwaves (EDAP LT.01).

Piezoelectric second generation lithotriptors are an established means of administering extracorporeal shockwave lithotripsy (ESWL) enabling treatment to be performed without anaesthesia or analgesia, but higher shockwave doses and multiple or staged treatment are frequently required. The bioeffects of this modality of ESWL, therefore, require further assessment. Seven experimental groups of adult male rabbits were treated using the EDAP LT.01 in order to determine the acute and chronic bioeffects of clinical dose, excess dose, divided excess dose, high frequency and multiple treatment (X10) piezoelectric shockwaves (PSW). Renal function was measured before and after treatment using mercaptoacetyltriglycine (MAG 3) scans. Gross and histological morphological changes were assessed at one and 30 days following application of PSW. Application of single clinical dose PSW was not associated with any significant functional or morphological renal injury. Excess dose PSW caused transient gross renal contusion, which resolved in the majority of animals with no persistent microscopic abnormality. Divided excess dose PSW resulted in no gross or microscopic damage. High frequency PSW was associated with mild histological abnormality. Multiple PSW treatments caused small discrete fibrotic lesions in all cases, without any change in renal function.

The coagulase of Staphylococcus aureus 8325-4. Sequence analysis and virulence of site-specific coagulase-deficient mutants.

The sequence of the coagulase gene (coa) from Staphylococcus aureus strain 8325-4 is reported. The deduced amino acid sequence of the coagulase protein is compared with previously reported sequences of coagulases from strains 213 and BB. The secreted mature forms of coagulase proteins are composed of three distinct segments: (i) the N-terminal 150-270 residues, which are c. 50% identical, (ii) a central region with high (greater than 90%) residue identities, and (iii) a C-terminal region composed of repeated 27-amino-acid residue sequences. The variable N-terminal sequences are probably responsible for antigenic differences among coagulases of different serotype. The region of coagulase which binds to prothrombin and activates it to form staphylothrombin is also located in the N-terminal half of the protein. A site-specific substitution mutation in the coa gene, which abolished plasma clotting activity, was isolated by recombinational allele-replacement in strains 8325-4 and M60. The Coa- mutants did not show diminished virulence in subcutaneous and intramammary infections of mice. No evidence for a role for coagulase in virulence of toxigenic or nontoxigenic strains was obtained. This contradicts findings of several groups using Coa- mutants generated by chemical mutagenesis and suggests that the earlier results were obtained with strains that had suffered additional mutations in virulence-related genes.

Virulence of protein A-deficient and alpha-toxin-deficient mutants of Staphylococcus aureus isolated by allele replacement.

The gene coding for protein A (spa) of Staphylococcus aureus 8325-4 has been inactivated by substituting part of the spa coding sequence for a DNA fragment specifying resistance to ethidium bromide. The in vitro-constructed spa::EtBrr substitution mutation was introduced into the S. aureus chromosome by recombinational allele replacement. Southern blot hybridization showed that the in vitro-constructed mutation was present in the chromosomal spa locus. We have previously reported the inactivation of the alpha-toxin gene (hly) by allele replacement with an in vitro-constructed hly::Emr (erythromycin resistance) mutation (M. O'Reilly, J.C.S. de Azavedo, S. Kennedy, and T.J. Foster, Microb. Pathogen. 1:125-138, 1986). A double Spa- Hly- mutant was constructed by transduction. The virulence of Spa- and Hly- mutants was tested by experimental infection of mice. When subcutaneous injections were given, Hly- mutants formed a flat, darkened lesion, whereas Hly+ strains caused a raised, cream lesion. Alpha-toxin was shown to be a major factor in forming subcutaneous lesions and in causing the death of mice injected intraperitoneally. Spa- mutants were slightly less virulent than their Spa+ counterparts, which suggests that protein A is also a virulence factor of S. aureus.