Interlaboratory validation of in vitro serological assay systems to assess the potency of tetanus toxoid in vaccines for veterinary use.
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Animal Testing Alternatives↗
Biomedical subjects
J Woltjes
Publications and source records attributed to J Woltjes.
Interlaboratory validation of in vitro serological assay systems to assess the potency of tetanus toxoid in vaccines for veterinary use.
An interlaboratory validation study was carried out in seven laboratories to evaluate the suitability of in vitro serological assay systems for the assessment of the potency of tetanus toxoid in single and multicomponent vaccines for veterinary use. Nine commercial vaccines and one experimental tetanus toxoid preparation were selected for immunization purposes according to Method A of the European Pharmacopoeia. Levels of tetanus antibodies in guinea-pig and rabbit serum samples were estimated by indirect ELISA, toxin binding inhibition (ToBI) test, passive haemagglutination (HA) test and by the prescribed standard toxin neutralization (TN) test in mice. Estimates of potency obtained by in vitro tests and by TN test were in good agreement for the various vaccines tested and for antibody levels of individual serum samples in the range 2.6 IU/ml to 266 IU/ml. Significant (P < 0.05) intralaboratory variation occurred less frequently for ELISA and ToBI test than for HA test. The frequency of significant (P < 0.05) interlaboratory variation was acceptable for the ELISA and the ToBI test but greater variation was observed for the HA test. It is concluded that the ELISA and ToBI tests are suitable in vitro assay systems for assessing the potency of tetanus toxoid in batches of single and multicomponent vaccines for veterinary use. Rigid standardization of the HA test is essential before this test can be used for the same quality control purpose.
Animals↗
Virulence of beta-hemolytic and non-hemolytic Streptococcus mutans: lethal dose determinations in neonatal mice.
The virulence of beta-hemolytic and non-hemolytic strains of Streptococcus mutans was studied in neonatal mice by LD50 determinations after intracerebral injection of the bacteria. Although the differences in LD50 values are small the results may indicate that beta-hemolytic S. mutans strains (mean LD50 of 6.3 X 10(7) c.f.u.) were more virulent than non-hemolytic S. mutans strains (mean LD50 of 47.7 X 10(7) c.f.u.). The LD50 values of other viridans streptococci varied between 4.8 and 10(7) c.f.u. Strains of S. pyogenes and S. agalactiae were highly virulent in this animal model with LD50 values lower than 10(5) c.f.u.
Animals↗
beta-haemolysis and pigment production by the oral bacterium Streptococcus mutans.
The prevalence of beta-haemolysis and yellow pigmentation among 89 isolates of Streptococcus mutans from human dental plaque and 59 Strep. mutans isolates from positive cultures of human dental root canals were investigated. beta-Haemolytic strains were more frequent among the root-canal isolates (25.4 per cent) than among the dental plaque isolates (12.4 per cent). The distribution of pigment production among beta-haemolytic strains (22 pigmented strains out of 26 strains) and among non-haemolytic strains (5 pigmented strains out of 122 strains) showed a relationship between haemolysin and pigment production. beta-Haemolytic, pigmented strains (biotype c and e and 35-39 per cent guanine plus cytosine) were common in plaque and were the dominant type of Strep. mutans in some plaques. As beta-haemolysis by Strep. mutans was only demonstrated after strict anaerobic growth, whereas pigment production was demonstrated after growth under less anaerobic conditions (candle jar) on sucrose-containing agar plates, the observation of pigment may facilitate a presumptive identification of beta-haemolytic strains of Strep. mutans.
Dental Plaque↗
Detection and characterization of hemolysin production in Streptococcus mutans.
Beta-hemolytic strains of Streptococcus mutans were identified and physiological reactions and hemolysin production were studied. Strict anaerobic conditions were shown to be indispensable for the expression of beta-hemolysis on blood agar plates; hemolysis was only observed after growth in an atmosphere with an oxygen content of 10 ppm or lower. The occurrence of beta-hemolytic strains was found not to be restricted to one biotype of S. mutans. Two hemolytic activities were detected in liquid cultures. Oxygen-labile activity was detected in prereduced broth cultures and was shown to be unstable and indetectable in supernatants. Solubilization of oxygen-labile hemolysin was achieved by the addition of Tween 80 to the cultures. Oxygen-stable activity was detected in supernatants of cell suspensions in the presence of maltose, Casamino Acids, and Tween 80. In contrast to oxygen-labile activity, oxygen-stable activity was not detected in broth cultures.
Anaerobiosis↗
beta-Haemolysis by Streptococcus mutans.
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Hemolysis↗
Double-osmotic-shock procedure to prepare gentamicin adenine mononucleotide transferase for the enzymatic assay of gentamicin.
The release of gentamicin adenine mononucleotide transferase during single, cold, osmotic-shock treatment of Escherichia coli K-12 W677/HJR66 is not always maximal. The quantity of gentamicin adenine mononucleotide transferase in osmotic extracts could be significantly increased when a double-shock procedure was performed.
Adenosine Monophosphate↗
Gentamicin assay by enzymatic adenylylation and the application of a double osmotic shock procedure to prepare gentamicin adenine mono-nucleotide transferase.
The release of gentamicin adenine mono-nucleotide transferase (GAdT) during single cold osmotic shock treatment of E. coli K12 W677/HJR66 is not always maximal. The yield of GAdT could not be improved by using E. coli harvested at different stages of growth, by prolonging the exposure to the different steps of the shock procedure, by changing the sucrose concentration, or the magnesium chloride volume. The quantity of GAdT in osmotic extracts could be increased when a double shock procedure was performed. Using an aliquot (30 microliter) of the extract, an accurate and quick assay for gentamicin, sisomicin and tobramycin in microvolumes of serum (30 microliter) can be accomplished. To avoid high background activity in the assay, the extracts should be prepared from E. coli grown in gentamicin-free medium.
Adenosine Triphosphate↗
The priming of extracorporeal circuits: the effect on canine blood elements.
Improving hemocompatibility is of major interest in extracorporeal circulation (ECC). Changes in numbers and functions of the blood cells during ECC have been ascribed to the nonphysiologic materials of the circuit. In this study, commonly used priming fluids (banked blood, Ringer's lactated solution, gelatin solution and dextran 70 solution) have been investigated for their influence on numbers and functions of canine thrombocytes, leukocytes and erythrocytes. Infusion of banked blood and Ringer's lactated solution did not affect number and function of the thrombocytes, whereas the plasma expanders caused dramatic, but reversible decreases. Leukocyte numbers were also affected, but only gelatin resulted in a decrease of leukocyte function. No effect on erythrocyte numbers was observed. It is concluded that under these experimental circumstances some priming solutions cause acute intravascular aggregation. To obtain the optimal condition for studying the hemocompatibility of ECC, preferably Ringer's lactated solution should be used.
Animals↗