1,25 dihydroxyvitamin D3 stimulates phospholipase C-gamma in rat colonocytes: role of c-Src in PLC-gamma activation.

Our laboratory has previously demonstrated that 1,25-dihydroxyvitamin D3 (1,25[OH]2D3) rapidly stimulated polyphosphoinositide (PI) hydrolysis, raised intracellular Ca2+, and activated two Ca2+-dependent protein kinase C (PKC) isoforms, PKC-alpha and -betaII in the rat large intestine. We also showed that the direct addition of 1,25(OH)2D3 to isolated colonic membranes failed to stimulate PI hydrolysis, but required secosteroid treatment of intact colonocytes, suggesting the involvement of a soluble factor. Furthermore, this PI hydrolysis was restricted to the basal lateral plasma membrane of these cells.

TESTS FOR PNEUMOCOCCUS HYPERSENSITIVENESS IN DOGS AFTER RECOVERY FROM EXPERIMENTAL PNEUMOCOCCUS LOBAR PNEUMONIA.

The data derived from the above described investigations indicate that dogs do not develop hypersensitivity to the pneumococcus as the result of experimental lobar pneumonia. This inference is based on the following findings: 1. Fifteen dogs were given Type I and Type II pneumococcus lobar pneumonia and following recovery were tested for hypersensitiveness by means of intrabronchial and intracutaneous injections of the autolysate made from the homologous pneumococcus.

CHANGES IN THE TITER OF ANTIPNEUMOCOCCAL HUMORAL IMMUNITY IN ADULT HUMAN BEINGS.

Fifty-five individuals were tested to determine the pneumococcidal promoting activity of their serum against Types I and II pneumococci. By repeated tests an attempt was made to study the constancy of the degree of their immunity over intervals of 2 to 6 months. In this group were included nine persons with common colds and twelve cases of a severe influenza-like infection.

THE RELATION OF NATURAL HUMORAL ANTIPNEUMOCOCCAL IMMUNITY TO THE INCEPTION OF LOBAR PNEUMONIA.

A study of the pneumococcidal-promoting action of the serum of lobar pneumonia patients, secured from 4 to 48 hours after the onset of the disease, has revealed the fact that in the majority of instances the serum possessed the power to promote killing of the homologous pneumococcus, isolated in different instances from the lung, blood, and sputum. While in some instances this action was slight, in others it was present to as great a degree as in normal individuals and persisted as long as 48 hours or more after the beginning of the disease. The variations observed from case to case were not related to the extent of the pneumonic lesion or to the virulence of the several pneumococcus strains but appeared to depend on differences in individual human beings in respect to the natural antipneumococcus properties of their blood and their reaction to the invading microorganism.

A STUDY OF THE RESISTANCE OF NORMAL HUMAN BEINGS TO RECENTLY ISOLATED STRAINS OF PATHOGENIC PNEUMOCOCCI.

With a view to obtaining information as to the virulence of pneumococci for human beings a study was made of the pneumococcidal action of normal human serum-leucocyte mixtures for freshly isolated strains of pathogenic pneumococci. It was found that human beings as a group showed well marked pneumococcus destroying power in their blood for all types of organisms studied. Individuals, however, exhibited wide variations in their reactions against the different types.

CHANGES IN HUMORAL IMMUNITY OCCURRING DURING THE EARLY STAGES OF EXPERIMENTAL PNEUMOCOCCUS INFECTION.

A study was made of the changes in humoral immunity occurring during the early phases of experimental pneumococcus infection in the dog and cat. The methods devised by Robertson and Sia were employed to demonstrate the presence of anti-pneumococcus properties in the serum of animals naturally resistant to this micro-organism. It was found that with a generalized and overwhelming infection accompanied by early blood invasion, there was a prompt and rapid decrease in the concentration of natural humoral immune bodies which frequently disappeared entirely by the time of death.