THE CONSTRICTING INFLUENCE OF ADRENALIN UPON THE HUMAN CORONARY ARTERIES

1. Adrenalin causes a marked constriction of the human coronary artery, although it undoubtedly produces a relaxation in some mammals; e. g., calf, sheep, pig, etc. 2. The human coronary artery is probably provided with sympathetic vasoconstrictors. 3. If human blood-vessels are obtained in a warm condition within a few hours after death, they are often suitable for biological and pharmacological study.     

INFLUENCE OF TEMPERATURE UPON THE VELOCITY OF THE COMPLEMENT FIXATION REACTION IN SYPHILIS

Examination of syphilitic serum or cerebrospinal fluid can be made at any temperature between 23° and 37°C. The velocity of the fixation reaction, including the fixation of complement and subsequent hemolysis, is greater at a higher temperature, the optimum point being 37°C. The maximum reaction is also reached, however, when the mixture of lipoids, syphilitic serum, and complement is allowed to stand for a long enough period at a lower temperature, the minimum thermal point being near 23°C. For the optimum temperature (37°C.) an incubation of 30 minutes is sufficient, while for the minimum temperature (23°C.) 2 hours are necessary. At the temperature of 30°C. the reaction proceeds with moderate velocity and is complete within 60 minutes. Guinea pig complement gave a sharper reaction with the sera which contained less than one unit of the fixing substance. Fixation is complete, however, at any of the three temperatures within 20 minutes when there are more than two units present. A serum containing one unit of fixing substance will complete reaction within 30 minutes at 37°C., 60 minutes at 30°C., and 2 hours at 23°C., irrespective of whether human or guinea pig complement is used. For many reasons a properly adjusted thermostat for 37°C. is recommended for conducting the serum diagnosis of syphilis when possible, but it should not be overlooked that at a temperature near 30°C. an entirely reliable result can be obtained without a special incubator. Even at a temperature as low as 23°C. the test can be carried out if sufficient length of time is allowed. The foregoing conclusions refer only to the systems in which the acetone-insoluble fraction of tissue lipoids is used as antigen.     

THE INFLUENCE OF HYDROCORTISONE ON THE ACTION OF EXCESS VITAMIN A ON LIMB BONE RUDIMENTS IN CULTURE

The effect of hydrocortisone has been studied in organ cultures of the cartilaginous long bone rudiments from 7-day chick embryos and of the well ossified limb bones from late fetal mice. In the chick rudiments, which grow rapidly in culture, the growth rate was much reduced by hydrocortisone, less intercellular material was formed, and the hypertrophic cells of the shaft were much smaller than in the controls in normal medium. In the late fetal mouse bones, which grow very little in culture, hydrocortisone had no obvious effect on growth but arrested resorption of the cartilage. These effects resemble those described by others in the skeleton of animals treated with cortisone or hydrocortisone. The influence of hydrocortisone on the response of the chick and mouse explants to excess vitamin A was investigated. In the presence of excess vitamin A, cartilage (chick, mouse) and bone (mouse) rapidly disintegrated, but when hydrocortisone also was added to the medium, this dissolution of the intercellular material was much retarded, though not suppressed. The retardative action of hydrocortisone on the changes produced by excess vitamin A in skeletal tissue in culture, contrasts sharply with the strongly additive effect of the two agents on the skeleton in the intact animal (Selye, 1958). It is suggested that this discrepancy between the results obtained in vitro and in vivo is probably due to systemic factors that operate in the body but are eliminated in organ cultures.     

THE INFLUENCE OF EPINEPHRIN UPON THE CORONARY CIRCULATION OF THE MONKEY

Decrease in coronary flow was the constant response of freshly isolated monkey hearts to epinephrin. These hearts were perfused with autogenous hirudinized blood diluted with Locke solution. The results were constant at high or low perfusion pressures, in beating or resting hearts, and with all adequate doses. Increased coronary flow was obtained constantly in rabbit hearts under identical conditions. In the light of previous work upon isolated human coronary arteries, the general conclusion is drawn that, while actively dilating the coronary vessels in the dog, cat, rabbit, ox, sheep, and pig, epinephrin constricts the coronary vessels in man and the monkey. The coronary arteries of the last two species are presumably supplied with constrictor nerves of true sympathetic (thoracicolumbar) origin.     

A STUDY OF HUMAN SKIN GRAFTED UPON THE CHORIO-ALLANTOIS OF CHICK EMBRYOS

Human skin grafted upon the chorio-allantoic membrane of chick embryos adheres and becomes nourished for as long as 10 days. Occasionally regrafts upon a second egg have succeeded and thus prolonged the vitality of the graft to 14 days. In successful experiments the epithelium of the chorio-allantois fuses with that of the graft, the collagen fibers of the corium interlace with those of the membrane after the separation or disappearance of the ectodermal layer, and the blood vessels of the chick anastomose, and unite by intervening pools of extravasated blood, with those of the graft. This vascular communication between the two tissues is largely responsible for the nourishment of the graft by affording a plasmatic circulation. Gradually there is a partial revascularization of the graft by an ingrowth of blood vessels from the chick membrane. Human skin grafts were susceptible to experimental infection by several viruses.