Catalytic properties of Sepharose-bound L-alanine dehydrogenase from Bacillus cereus.

(1) L-Alanine dehydrogenase from Bacillus cereus was purified by a two-step chromatographic procedure involving Cibacron-Blue 3G-A Sepharose 4B-CL, and Sepharose 6B-CL, and immobilized on CNBr-activated Sepharose 4B. (2) Following immobilization via two of the six subunits, L-alanine dehydrogenase retained 66% of the specific activity of the soluble enzyme. The affinity of the immobilized enzyme for NH4+, pyruvate and L-alanine, was not different to that of the soluble form. The Km of the Sepharose-bound L-alanine dehydrogenase for pyridine coenzymes was 6-8-times higher than in the soluble case. (3) The stability of L-alanine dehydrogenase towards urea or thermal denaturation was increased by immobilization. (4) The incubation at 37 degrees C for 24 h of the immobilized L-alanine dehydrogenase with 3 M NH4Cl/NH4OH buffer (pH 9) released 70% of the enzyme. The specific activity and the affinity of the 'solubilized' L-alanine dehydrogenase for the pyridine coenzymes was the same as that obtained with the original, soluble L-alanine dehydrogenase.

Comparative results of respiratory virus isolation attempts in chorioallantoic membrane fragments and embryonated chicken eggs.

Attempts performed with 39 samples of nasopharyngeal secretion resulted in the isolation of 21 (54%) hemagglutinating viral agents in chorioallantoic membrane (CAM) fragments, while a single strain (2.5%) was isolated in the embryonated egg. The time interval required for virus isolation in CAM fragments ranged from 4 to 20-24 days and was longer then 10 days in the embryonated egg. Maintenance of CAM fragments in roller tubes leads to a more abundant virus multiplication and, implicitly, to a reduction of the time interval necessary for virus isolation.

[Role of parainfluenza varuses in etiology of acute respiratory infections in children (serological diagnosis)]. / Rolul virusurilor paragripale în etiologia infectiilor respiratorii acute ale copilului (diagnostic serologic).

Serologic investigations carried out in 254 children admitted to a Clinic for Children for respiratory diseases, established a diagnosis of infection with parainfluenza virus in 19.2% of cases. The predominant age-group affected was 7--12 months and 0--6 months; the causative agent in most cases was parainfluenza type 3, followed by type 2 and then type 1. The role of parainfluenza viruses in the aetiology of laryngotracheobronchiectasis was confirmed, as well as their participation in the aetiology of pneumonia in infants. The results also showed the wide circulation of parainfluenza viruses in children and their outstanding contribution to respiratory diseases among hospitalized children within a period of four years.

[Serological studies of the role of the respiratory syncytial virus in acute respiratory diseases in children]. / Investigatii serologice privind participarea virusului respirator sincitial în îmbolnavirile respiratorii acute la copii

The presence of the syncytial respiratory virus was determined by CF in 281 children admitted with acute respiratory diseases between 15 Sept. 1971 and 30 Dec. 1973, using the Long antigen prepared in the "St. Nicolau" Institute of Virology, Bucharest. In 38 children (13.5%) a serologic diagnosis of infection with the syncytial virus was established; in the other cases of respiratory infection of different etiology, antibodies to the syncytial virus were found in low but constant titers in both serum samples. The presence of these antibodies in a high proportion of the children points to the wide circulation of the syncytial virus in the infantile population, with all its clinico-epidemiologic implications.