ELECTROPHORETIC STUDIES ON PR8 INFLUENZA VIRUS.

Crude preparations of PR8 influenza virus, obtained by high-speed centrifugation, contain two electrophoretically distinct components. One of these, present to the extent of 10 to 20 per cent, was identified by electrophoresis, centrifuge, and activity tests, as an impurity similar to or identical with a high molecular weight acidic substance shown by Knight to be elaborated by normal uninfected embryos. The other component, present to the extent of 80 to 90 per cent, appeared to represent the active virus.

BIOPHYSICAL PROPERTIES OF PREPARATIONS OF PR8 INFLUENZA VIRUS.

The biophysical properties of several preparations of PR8 influenza virus have been studied. Electron micrographs showed slightly irregular, circular particles with an average diameter of 115 mmicro and a standard deviation of the distribution of diameters of 15 per cent. The specific volume was determined with a pycnometer to be 0.

THE SEDIMENTATION RATE OF THE BIOLOGICAL ACTIVITIES OF INFLUENZA A VIRUS.

The sedimentation rates of the mouse infectivity principles of the PR8 and the F12 strains of influenza A virus were shown by studies in the separation cell to have values which are not significantly different from sedimentation rates of the principal components of purified preparations. It was shown further that the bulk of the chicken red blood cell agglutinating activity and of the chick embryo infectivity of PR8 influenza virus preparations sediments at the same rate as that of the 100 mmicro. component.

INFLUENCE OF pH AND OF CERTAIN OTHER CONDITIONS ON THE STABILITY OF THE INFECTIVITY AND RED CELL AGGLUTINATING ACTIVITY OF INFLUENZA VIRUS.

A study has been made of the pH stability of centrifugally purified strains of influenza virus with respect to the biological properties of mouse infectivity and chicken red blood cell agglutinating activity. Observations also were made on the importance of composition of buffer, temperature of storage, and concentration of virus protein to the stability of the virus. When tested for stability at a protein concentration of 0.

STUDIES ON A NON-HEMOLYTIC STREPTOCOCCUS ISOLATED FROM THE RESPIRATORY TRACT OF HUMAN BEINGS : III. IMMUNOLOGICAL RELATIONSHIP OF STREPTOCOCCUS MG TO STREPTOCOCCUS SALIVARIUS TYPE I.

The results of studies on the immunological relationship between streptococcus MG and Streptococcus salivarius type I are described. Evidence is presented to show that Streptococcus salivarius type I, like streptococcus MG, possesses a capsular polysaccharide antigen. Similarities in the capsular polysaccharides of these two different species of non-hemolytic streptococci appear to be responsible for their immunological relationship.

STUDIES ON A NON-HEMOLYTIC STREPTOCOCCUS ISOLATED FROM THE RESPIRATORY TRACT OF HUMAN BEINGS : II. IMMUNOLOGICAL CHARACTERISTICS OF STREPTOCOCCUS MG.

The results of studies on the antigenic structure and immunological specificity of a non-hemolytic streptococcus, designated streptococcus MG, are described. Evidence is presented to show that this microorganism possesses a capsule and that this structure contains a polysaccharide antigen which is responsible for the type specific serological reactions obtained with streptococcus MG.

STUDIES ON A NON-HEMOLYTIC STREPTOCOCCUS ISOLATED FROM THE RESPIRATORY TRACT OF HUMAN BEINGS : I. BIOLOGICAL CHARACTERISTICS OF STREPTOCOCCUS MG.

A single serological type of non-hemolytic streptococcus, designated streptococcus MG, has been isolated from the lungs of fatal cases of primary atypical pneumonia, from the sputa of patients with this disease, and occasionally from the respiratory tracts of normal human beings. Certain biological characteristics of this microorganism have been studied. All of the 59 strains isolated have been shown to belong to a homogeneous bacteriological group with characteristics which serve to distinguish it from any other well defined species of streptococcus.

DIFFERING RATES OF DEATH AT INNER AND OUTER SURFACES OF THE PROTOPLASM : II. NEGATIVE POTENTIAL IN NITELLA CAUSED BY FORMALDEHYDE.

A previous paper showed that when the inner protoplasmic surface has lost its potential under the influence of formaldehyde the outer surface can still respond to changes in the concentration of electrolytes. The present paper indicates that after the inner surface has lost its potential there may be a sudden development of negative potential at the outer surface due to substances coming out of the sap and combining with formaldehyde.

DIFFERING RATES OF DEATH AT INNER AND OUTER SURFACES OF THE PROTOPLASM : I. EFFECTS OF FORMALDEHYDE ON NITELLA.

When protoplasm dies it becomes completely and irreversibly permeable and this may be used as a criterion of death. On this basis we may say that when 0.2 M formaldehyde plus 0.

STUDIES OF THE INNER AND OUTER PROTOPLASMIC SURFACES OF LARGE PLANT CELLS : II. MECHANICAL PROPERTIES OF THE VACUOLAR SURFACE.

The vacuolar surface of Nitella is covered with a non-aqueous film too thin to be visible as a separate membrane. The motion of the protoplasm may subject this film to a good deal of mechanical disturbance. Apparently this does not rupture the film for no dye escapes into the protoplasm as the result of such disturbance when the vacuolar sap is deeply stained with neutral red or brilliant cresyl blue.

THE PATHOGENESIS OF TUMORS OF THE LIVER PRODUCED BY BUTTER YELLOW.

A conspicuous feature of the cirrhosis that is produced by butter yellow is the new formation of bile ducts that sprout from ducts of the larger portal spaces and penetrate between "portal units" to anastomose with liver cell columns at the periphery of these units. Hyperplasia of the liver may occur with butter yellow administration in the absence of cirrhosis or other change associated with widespread destruction of liver tissue; it occurs as diffuse or focal lesions and affects both parenchymal cells and newly formed ducts. Focal hyperplasia is a precursor of trabecular and adenomatous hepatomas which arise as multiple tumors.

THE INFLUENCE OF DIET ON THE PRODUCTION OF TUMORS OF THE LIVER BY BUTTER YELLOW.

The presence of fat in the diet accelerates the production of hepatic tumors by p-dimethylaminoazobenzene (butter yellow), and when its quantity is very small, few are produced. Butter yellow with diets consisting in large part of rice, or with other diets with low protein content, causes nodular cirrhosis, but, rice substituted for sugar in a diet containing protein, fat, and butter yellow with adequate vitamins accelerates the production of tumors though the added rice is insufficient to induce nodular cirrhosis. Rice favors the production of hepatic tumors by agencies that are not yet explained.

RELATIONSHIP OF A NEW GROWTH FACTOR REQUIRED BY CERTAIN HEMOLYTIC STREPTOCOCCI TO GROWTH PHENOMENA IN OTHER BACTERIA.

By a series of quantitative assays of concentrates prepared in a variety of ways, it has been shown that the previously described growth factor now called "strepogenin," required by certain hemolytic streptococci, is very similar to and possibly identical with the recently described growth factors for Lactobacillus casei and Smith's Streptococcus lactis. An improved procedure for assay of strepogenin with the aid of Lactobacillus casei has been described, and additional properties of the growth factor have been presented.

INDUCED RESISTANCE OF THE CENTRAL NERVOUS SYSTEM TO EXPERIMENTAL INFECTION WITH EQUINE ENCEPHALOMYELITIS VIRUS : III. ABORTIVE INFECTION WITH WESTERN VIRUS AND SUBSEQUENT INTERFERENCE WITH THE ACTION OF HETEROLOGOUS VIRUSES.

Although vaccination of guinea pigs with formalin-inactivated Western equine encephalomyelitis virus rendered them specifically immune to an intracerebral challenge dose of 1,000 M.L.D.

A SEDIMENTABLE COMPONENT OF ALLANTOIC FLUID AND ITS RELATIONSHIP TO INFLUENZA VIRUSES.

Macromolecular material was isolated from normal allantoic fluid by a centrifugation procedure comparable to that currently employed for the concentration and purification of influenza viruses. The yield of material was found to vary with the age of the embryo, reaching a maximum average value after 14 days of incubation at 39 degrees C. of about 0.

THE DETERMINING INFLUENCE OF TAR, BENZPYRENE, AND METHYLCHOLANTHRENE ON THE CHARACTER OF THE BENIGN TUMORS INDUCED THEREWITH IN RABBIT SKIN.

The benign tumors of rabbit skin which appear in response to benzpyrene and methylcholanthrene are nearly all of the same kinds that tar produces, namely frill horns, papillomas, and carcinomatoids; but the collateral effects of these agents render many of them very different from the tar tumors. The connective tissue of the corium is so slowly excited by the pure hydrocarbons that for a long while it furnishes to most of the growths only a scanty stroma, when any, and in consequence they remain small,-low, dry, indolent, bas-relief affairs, made up almost entirely of the neoplastic epithelium,-not florid, fleshy excrescences with a large connective tissue component, such as tarring calls forth. The frill horns usually desquamate instead of building up like those due to tar, and some of their cells undergo a dyskeratotic change with result in spherical, homogeneous, deep-staining bullet-like elements, which give to the growths a singular aspect.

THE INITIATING AND PROMOTING ELEMENTS IN TUMOR PRODUCTION : AN ANALYSIS OF THE EFFECTS OF TAR, BENZPYRENE, AND METHYLCHOLANTHRENE ON RABBIT SKIN.

Benzpyrene brings about neoplastic changes in rabbit epidermis much sooner than has been supposed. The long interval that elapses before visible growths appear is due in the main to the relatively slight power of the carcinogen to encourage multiplication of the cells it renders neoplastic. Yet some slight power of this sort it has.

THE HISTOPATHOLOGY OF PROGRESSIVE MUSCULAR DYSTROPHY AS REVEALED BY ULTRAVIOLET PHOTOMICROGRAPHY.

Results have been presented of the application of a simplified technique of ultraviolet photomicrography to a study of the specific lesions in muscle in subjects with progressive muscular dystrophy. An exact description of the histological changes occurring in this syndrome, as revealed by photomicrographs in ultraviolet light, is difficult at this time because of the lack of an adequate system of nomenclature. Attention has been drawn, however, to lesions of consistent character, found in sections of muscle removed at biopsy, which appear to be specific for the disease.

CERTAIN CONDITIONS DETERMINING ENHANCED INFECTION WITH THE RABBIT PAPILLOMA VIRUS.

The infection of normal or hyperplastic rabbit skin with the papilloma virus can be greatly enhanced by protecting the scarified and inoculated area with a layer of paraffined gauze until healing occurs. In this way the necrosis which follows upon scarification and also the scabbing are almost entirely prevented and in consequence epithelial regeneration is usually complete within 24 hours. Not only are many susceptible cells provided to the virus far earlier than would otherwise be the case,-and collateral tests have shown that it becomes associated with them within a few hours instead of after many,-but the inoculum is itself conserved, instead of becoming largely lost amidst necrotic tissue and scab, as under ordinary circumstances.

THE CONSTITUTION OF MITOCHONDRIA AND MICROSOMES, AND THE DISTRIBUTION OF NUCLEIC ACID IN THE CYTOPLASM OF A LEUKEMIC CELL.

1. Rat tumor extracts, containing chiefly the cytoplasmic constituents of leukemic cells, were fractionated into three main portions, the different components separating in the centrifuge according to size. 2.

THE RECOVERABILITY OF VIRUS FROM PAPILLOMAS PRODUCED THEREWITH IN DOMESTIC RABBITS.

By preliminary preparation of the skin in ways that render it hyperplastic the presence of infective virus can be demonstrated in extracts of domestic rabbit papillomas which yield no growths when inoculated by the ordinary methods and which for this reason have been supposed to contain no virus. The amount of virus recovered by the method outlined in the present work, however, is small when compared with the yield obtained in most instances from comparable cottontail rabbit papillomas. The yield is greatly influenced not only by the virus strain used to produce the growths but by the individual rabbit host.

THE EFFECT OF CHEMICAL CARCINOGENS ON VIRUS-INDUCED RABBIT PAPILLOMAS.

The application of methylcholanthrene and tar to virus-induced papillomas of the domestic rabbit caused them to become carcinomatous with great rapidity, and the malignant changes were frequently multiple. In bringing on the cancers the chemical agents acted in their specific capacity as carcinogens, not as ordinary stimulants of cell proliferation. The cancers derived from the virus-infected cells and were of the same types as arise from these elements spontaneously after a much longer time.

TITRATION OF INFLUENZA VIRUS IN CHICK EMBRYOS.

A study was made to establish the reproducibility of end points obtained in the titration of influenza viruses in chick embryos. Six tests were performed, each composed of five replicate titrations of a purified preparation of the PR8 strain of influenza virus. The data from these titrations were subjected to statistical analysis which revealed that the chances are 19 out of 20 that differences in end points of 0.