Influence of hydrocortisone on cytopathic effect of Newcastle disease virus and stability to freezing of vescicular stomatitis virus

Summary The presence of hydrocortisone in virus-infected cell cultures leads to enhancement of the syncytia forming ability of Newcastle disease virus and to production of vescicular stomatitis virus particles which loose their infectivity upon storage below 0°C.This work was supported by the Italian Consiglio Nazionale delle Ricerche (CNR), Progetto finalizzato Virus, Contract N. 77.00284.84.     

The activity of Newcastle disease virus-envelope proteins after treatment with detergents.

Treatment of NDV with anionic detergents or lipid solvents destroys the activities of hemagglutinin and neuraminidase. After disruption of the virus with non-ionic detergents, the activities of envelope proteins remain unchanged. It is suggested that the phosholipids are very important for the biological activity of NDV-envelope proteins.     

The effect of hydrocortisone and thyroxine on development of calcium homeostasis in embryonic intestinal epithelium

Cytoplasmic Ca²⁺ concentration of epithelial cells from 14-day embryonic chick duodena decreased during 72 h of organ culture to a value 54% of that found at 17 days in vivo. The ability of cells to maintain a constant Ca²⁺ concentration when challenged with high extracellular calcium was also significantly reduced. Addition of 1 M hydrocortisone during culture restored both parameters of Ca²⁺ homeostasis to that of 16-day uncultured duodena, and rise in cytoplasmic Ca²⁺ was significant within 4 h of hormone treatment. Thyroxine influenced epithelial Ca²⁺ similarly, but to a lesser degree and only after 48–72 h of culture. These data indicate that glucocorticoids, and possibly thyroid hormones, influence the development of calcium homeostasis in intestinal epithelium.     

The effect of BCG-vaccination on vaccinia virus infections in mice.

Pretreatment with BCG yielded a high degree of protection against experimental vaccinia virus infections in mice. Corynebacterium parvum and Aristolochia acid were less protective; other immunostimulants were ineffective.     

Cryo-bioorganic chemistry: freezing effect on stereoselection of l- and dl-leucine cooligomerization in aqueous solution

The chirality of l-/dl-leucine (50–50%) cooligomerization was investigated in liquid and frozen aqueous solutions. Cooligomerization was carried out by carbonyldiimidazole activation without initiator at an ambient (+22°C) and frozen (−18°C) temperature, respectively. The separated samples obtained after different time intervals of treatment were completely hydrolyzed (HCl) and the diastereomeric l- and d-leucine derivates of Marfey's reagent (1-fluoro-2,4-dinitrophenyl-5-l-alanine amide) were then traced and evaluated by RP-HPLC analysis. After 9 days of oligomerization, the l-Leu content was slightly enhanced in the liquid (57%) and somewhat more enhanced in the frozen (64%) samples. After 17 days, however, the l-Leu content had decreased in the liquid (53%) and frozen (56%) conditions. These l-enantiomer amplifications indicate that an l-antipode is preferentially incorporated into the α-helical turn of the oligomer in the earlier stage of cooligomerization, while, later, the d-antipode is also incorporated. The role of ice in the improved stereoselection is discussed. This is the first recorded example of the effect of freezing on stereoselection. Received 27 October 2000; revised 11 December 2000; accepted 4 January 2000     

Studies on yellow mosaic disease of soybean. I. Effect of virus infection on plant pigments

Zusammenfassung Es wird gezeigt, dass die Abnahme des Chlorophyllgehalts in den von der gelben Mosaik-Krankheit befallenen Soyabohnenblättern auf eine Stimulierung der Chlorophyllase-Aktivität im Frühstadium der Erkrankung zurückzuführen ist.     

Rapid freezing of biologic tissue. Measurement of temperature and rate of freezing by thin-layer thermocouple]

An apparatus for rapid freezing of biological tissues by contact with a copper block cooled by liquid helium has been devised to reduce the contamination of copper block surface. It prevents the precooling of the specimen while going through the layers of cold helium gas surrounding the copper block and reduces the quantity of helium necessary for freezing. It also enables one to obtain easily reproducible results from freezing by immersion in liquid coolants. Freezing rates are measured directly, related to the specimen thickness, by a thin film thermocouple; its low thermal inertia gives speed measurements of the order of 100,000 degrees C/s.