Biomedical subjects

Waldemar Gottardi

Publications and source records attributed to Waldemar Gottardi.

6 recordsLinked to original sources

PubMed2006

N-Chlorotaurine and ammonium chloride: an antiseptic preparation with strong bactericidal activity.

The bactericidal activity of the endogenous antiseptic N-chlorotaurine (NCT) is significantly enhanced in the presence of ammonium chloride which induces the formation of monochloramine (NH(2)Cl) whose strong bactericidal activity is well known. In this study the properties of NCT plus ammonium chloride have been investigated. The reaction of active chlorine compounds like chloramine-T (N-chlorotoluene-sulfonamide sodium), chloroisocyanuric acid derivatives, hypochlorites (NaOCl, CaOCl(2)) with ammonium chloride did not stop at the stage of monochloramine, and the pungent smelling by-products di- and trichloramine, NHCl(2) and NCl(3), were also formed. This was not the case with NCT where only monochloramine was generated. The equilibrium constant of the reaction of NCT with ammonium was found to be [Formula: see text] , which allows to estimate the equilibrium concentration of monochloramine in aqueous solutions of NCT and ammonium chloride. At concentrations each ranging between 0.01% and 1.0% it comes to [NH(2)Cl]=3.5-254 ppm. As an unexpected result the monochloramine containing formulation turned out to be most stable in plain water without buffer additives. Quantitative killing assays revealed complete inactivation of 10(6) to 10(7)CFU/mL of seven bacterial strains by 0.1% NCT plus 0.1% ammonium chloride within 5 min, while with plain 0.1% NCT an incubation time of 2-4h was needed to achieve the same effect. The highly significant increase of bactericidal activity (200-300-fold) could be assigned to the presence of monochloramine which could be isolated by vacuum distillation. Aqueous solutions of NCT and ammonium chloride provide a highly effective and well tolerable antiseptic preparation appropriate to a treatment cycle of at least 1 month if stored in the refrigerator.

Ammonium Chloride↗

PubMed2005

Redox-iodometry: a new potentiometric method.

A new iodometric method for quantifying aqueous solutions of iodide-oxidizing and iodine-reducing substances, as well as plain iodine/iodide solutions, is presented. It is based on the redox potential of said solutions after reaction with iodide (or iodine) of known initial concentration. Calibration of the system and calculations of unknown concentrations was performed on the basis of developed algorithms and simple GWBASIC-programs. The method is distinguished by a short analysis time (2-3 min) and a simple instrumentation consisting of pH/mV meter, platinum and reference electrodes. In general the feasible concentration range encompasses 0.1 to 10(-6) mol/L, although it goes down to 10(-8) mol/L (0.001 mg Cl2/L) for oxidants like active chlorine compounds. The calculated imprecision and inaccuracy of the method were found to be 0.4-0.9% and 0.3-0.8%, respectively, resulting in a total error of 0.5-1.2%. Based on the experiments, average imprecisions of 1.0-1.5% at c(Ox)>10(-5) M, 1.5-3% at 10(-5) to 10(-7) M, and 4-7% at <10(-7) M were found. Redox-iodometry is a simple, precise, and time-saving substitute for the more laborious and expensive iodometric titration method, which, like other well-established colorimetric procedures, is clearly outbalanced at low concentrations; this underlines the practical importance of redox-iodometry.

Ascorbic Acid↗

PubMed2005

Chlorine covers on living bacteria: the initial step in antimicrobial action of active chlorine compounds.

OBJECTIVES: Although active chlorine compounds are well-known antimicrobial agents in human medicine, their initial steps of action have not been completely clarified. Using N-chlorotaurine (NCT), an endogenous mild representative, we observed persisting oxidation capacity affixed to bacteria. It was the aim of this study to investigate this 'chlorine cover'. METHODS: Pathogens were incubated in NCT, which was subsequently washed off. The oxidation capacity on the bacterial surface was measured photometrically. RESULTS: Superficial chlorination in the form of covalent N-Cl bonds to Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pyogenes, Escherichia coli, Proteus mirabilis, Pseudomonas aeruginosa and Candida albicans could be attached before killing took place. For S. aureus, 3 min incubation with NCT produced a cover of 3.3 x 10(-16) mol Cl(+)/cfu, while the cfu count was reduced by only 26%. The kind of microorganism, coating time, pH, buffer system and, basically, the chlorine compound, influenced the cover strength. The relative cover strength on S. aureus by NCT, chloramine T, sodium dichloro-isocyanurate or N,N-dichlorotaurine was 1:15.7:38.7:0.24. Chlorine covers were surprisingly stable and could be detected for 3 h at 20 degrees C (>8 h at 1 degrees C), even without a reduction of cfu. However, addition of 5% ammonium chloride caused a rapid loss of viability, explained by formation of highly bactericidal NH(2)Cl, an effect that resembles the ignition of a time-bomb. CONCLUSIONS: The chlorine cover can be regarded as the first sign of interaction between chlorinating agent and microorganism, and may explain the non-lethal features of postantibiotic effect and attenuation of bacterial virulence. Furthermore, it may be a decisive step in bacterial inactivation by the myeloperoxidase-hypochlorite system in innate immunity.

Bacteria↗

PubMed2005

N,N-dichlorotaurine: chemical and bactericidal properties.

The biogenous antimicrobial agent N-chlorotaurine (NCT) converts by disproportionation to N,N-dichlorotaurine (NDCT) at a rate proportional to acidity. This occurs at appreciable amounts already in weakly acidic biological systems. To understand the consequences of NDCT formation, a thorough investigation of this undescribed compound was mandatory, which needed its synthesis. Differently from NCT, this was possible in the aqueous system using trichloroisocyanuric acid. While the free acid, Cl(2)HNCH(2)CH(2)SO(3)H, was not available in pure form, its sodium and potassium salts were analytically pure and showed melting points (decomposition) of 125-128 degrees C (potassium) and 162-164 degrees C (sodium). The sodium salt demonstrated unexpected long-term stability even at room temperature (8.4 % loss of activity within 4 months). The aqueous solutions of both salts exhibited a weak acid reaction, and they were less stable than NCT. With regard to chlorination of amines (transhalogenation), NDCT was, surprisingly, less efficacious than NCT, which manifested itself by a lack of reactivity at pH < 7, for which a mechanistic explanation is given. Compared on a molar scale, NDCT was more bactericidal than NCT against the gram-negative bacteria E. coli, P. aeruginosa and P. mirabilis, while there was no difference concerning the gram-positive ones, S. aureus and S. epidermidis. The increase of bactericidal activity at acidic pH was the same as observed with NCT and is attributed to a higher susceptibility of bacteria in this environment. Taken together, NDCT seems not to be suited to substitute NCT as a preparation fit for medical practice.

Anti-Infective Agents, Local↗

PubMed2005

Tolerability and efficacy of N-chlorotaurine in epidemic keratoconjunctivitis--a double-blind, randomized, phase-2 clinical trial.

The aim of this study was to assess the tolerability and efficacy of N-chlorotaurine (NCT), an endogenous antimicrobial agent, in epidemic keratoconjunctivitis. In a prospective double-blind, randomized phase 2b study, the infected eyes were treated for 7 days with eye drops containing 1% aqueous solution of N-chlorotaurine (33 subjects) or gentamicin (27 subjects, control group). Adenovirus types 3, 4, 8, 19, and 37 were detected in 39 subjects (65%), enteroviruses in 8 (13.3%), and staphylococci in 5 (8.3%). Subjective and objective symptoms were scaled and added to a subjective and objective score, respectively, on day 1 (baseline), day 4, and day 8. Analyzing the whole study population, the subjective score on day 8 was lower in the NCT group (P = 0.016), whereas there were no differences in the objective score. However, in severe infections caused by adenovirus type 8 (n = 20) both the subjective and objective score were lower in the NCT group on day 4 (P = 0.003 and 0.015, respectively), which was also true for the subjective score on day 8 (P = 0.004) in this subgroup. The frequency of subepithelial infiltrates was similar in both groups. N-chlorotaurine was well-tolerated, shortened the duration of illness, and seems to be a useful causative therapeutic approach in severe epidemic keratoconjunctivitis.

Adenoviridae↗

PubMed2002

Chemical properties of N-chlorotaurine sodium, a key compound in the human defence system.

N-chlorotaurine (NCT) is known to play an important role in the human defence system. The already proved utility of the sodium salt as a disinfectant in human medicine suggested a thorough investigation of its chemical properties. Chlorine transfer to N-H groups (transhalogenation) and oxidation of thio and aromatic compounds represent its main reactions. Auto-chlorination causes disproportionation forming N, N-dichlorotaurine (NDCT) with K(d) = [NDCT][taurine]/f(a)[NCT]2aH+ = (4.5 +/- 0.8) x 10(6), while the reaction with ammonium releasing NH2Cl is characterised by K(NHCl2) = [NH2Cl][taurine]/[NCT][NH4+]f(a)2 = 0.02 +/- 0.004. The verified unique stability and low level reactivity of NCT are considered essential for its function in the mammalian defence system and its practical applicability, which manifests itself in an optimal compromise between microbicidal activity and toxicity.

Disinfectants↗