Stability of parenteral ceftriaxone disodium solutions in frozen and liquid states: effect of freezing and microwave thawing.

The stability of ceftriaxone disodium solutions stored in glass bottles was tested in two parenteral solvents (0.9% NaCl; 5% dextrose) at two concentration rates (10 and 50 mg/mL) and three temperatures (-22 degrees C, 5 degrees C, room temperature). The solutions, which had been initially frozen, were thawed at room temperature or by exposure to microwave radiations. The stability of each sample was determined by a quantitative bacteriological agar gel diffusion assay and by high-performance liquid chromatography. The results of this study indicate that admixtures of ceftriaxone disodium at the concentration rates tested can be frozen for six months without a significant loss in antibiotic activity. At room temperature, the stability is dependent on the concentration of ceftriaxone disodium. At 5 degrees C, the stability is related to the concentration of ceftriaxone and of the solvent. The results obtained by both analytical methods are very close. In order to perform routine assays, the high-performance liquid chromatography method was chosen on the basis of its rapidity and reproducibility.

Experimental approach to rouleau formation. Comparison of three methods.

From a clinical point of view, the approach to erythrocyte aggregate or rouleau formation and cohesion is undeniably of great interest. A large number of methods have been suggested for studying this parameter such as: back-scattering of light, nephelometry, ultrasound, etc... In this paper the authors have compared three methods to approach rouleau formation: direct observation of rouleau formation (rheoscope); 'erythrocyte aggregometer': with this technique, the light transmitted by the sample is integrated over a period of time and provides an index (IA); laser reflectometer based on studying the light that is back-scattered by the blood sheared in the gap of a viscometer. The results show that the indexes measured by both reflexion and transmission vary according to hematocrit and reach a maximum value at hematocrit levels of between 30 and 40%. In contrast, observation using the rheoscope did not provide qualitative evidence of this phenomenon.

[Evaluation of the alginat membrane filter method for the Enterovirus concentration in water (author's transl)]. / Alginat-Filter zur Konzentrierung von Enterovirus aus wässerigem Milieu - Grenzen der Methode.

It is bound to use a concentration method for the research of enteroviruses in water. One of the concentration methods, the filtration on alginat membranes, avoids the problem of the virus elution from the filter, then the membrane is soluble in a sodium citrat buffer. This method was studied with different types of water (synthetic water, tap water and wastewater). -The recovery efficiency of Poliovirus I in clear waters (synthetic water and tap water) was poor, unsatisfying reproducible; the results are better for small virus concentrations. This efficiency may be slowly enhanced by the addition to the sample of aluminium chlorid at a final concentration of 5.10(-4) M. -The technical problems (brittleness of the membranes, slow filtrations speed, small sample volume), soon noticeable with clear waters, are more important in the case of trouble waters. Meanwhile the use of this filtration method gives better results for the recovery of Poliovirus I in wastewaters than the direct inoculation to cells cultures.

[Attempt to express the spontaneous global bacteriolytic power of water]. / Essai d'expression du pouvoir bactériolytique spontané global d'une eau.

The utilization of a technique for the determination of spontaneous bacteriolytic power in surface waters has led us to propose a new way of expressing the spontaneous bacteriolytic power of water: PBSG. PBSG allows us to evaluate the intensity of global spontaneous bacteriolysis and to compare the global spontaneous bacteriolytic powers of different water samples.

[Study of the behavior of poliomyelitis virus type 1 in diffrerent hydrous media (author's transl)]. / Etude du comportement du virus poliomyélitique de type 1 dans différents milieux hydriques

After having analyzed several surveys on natural inactivation of viruses in water, the authors have attempted to determine the survival life of poliomyelitis virus type 1 in hydrous medium, of known composition, well-buffered and devoid of any bacterial contamination on the one hand, and on the other hand, in a similar medium with addition of organic humate-type substances. The experiment was carried out at 4 degrees C and at laboratory room temperature (18 degrees C-24 degrees C). Results tend to confirm that the presence of humate-type substances seems to have no significant influence on the development of poliomyelitis virus type 1. Moreover, under the experimental conditions used, the survival life of the virus is much longer than the one previously described. It represents an average of 296 days for a storage temperature of 18 degrees C-24 degrees C. It is longer in water kept at 4 degrees C; in fact, according to statistical calculations and to titrations carried out over a period of 550 days, the total disappearance of the virus was detected only after a period of 10 to 15 years.

[Concentration of viruses in water by the 2 phase polymer method: quantitative study]. / Concentration des virus dans l'eau par la méthode des polymères à deux phases: étude quantitative

The authors attempt to determine the sensibility of polymer two phases system applied to the concentration of viruses from water. They show that this technic agrees to the research of poliomyelitic viruses in waters since viral recuperation is always upper than 74.5%. Besides, they notice that average percentages of regained viruses are always 100% where the initial concentrations of viruses are 10(2) or 10(3) per liter; on the other hand if the initial concentration is higher the yield of this method is decreasing.