摘要:

Two strains ofMicrococcus epidermidisand five ofMicrococcus pyogeneswere found to produce antibiotics that were detected by using a mucoidStreptococcus pyogenesas test organism. The antibiotics were also active against some other Gram-positive organisms, but not against Gram-negative bacteria. TheM.epidermidisstrains inhibited most β-haemolytic streptococci with the exception of mucoid Lancefield Group C. TheM.pyogenesstrains were active against the majority of mucoidS.pyogenes(Group A), but few or none of the nonmucoid strains were inhibited. Streptococci of Groups B, C, and G were not affected. On the basis of antibacterial spectrum and characteristics of the antibiotics (dialysis, stability, and production curves) the seven strains were divided into four groups producing antibiotics of different types.Three strains of β-haemolytic streptococci were tested which were known to produce antibiotics. Two of these showed a selective inhibition similar to the micrococci. They inhibited all of the mucoidS.pyogenesbut few of the nonmucoid; they inhibited all strains of Group C, both mucoid and nonmucoid, but did not inhibit the Group G strains tested.These observations suggest that, apart from capsulation, there may be a fundamental metabolic difference between the majority of mucoid and nonmucoid strains ofS.pyogenes.

ISSN:1923-4287    

DOI:10.1139/cjr50e-025

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Purified influenza virus A (PR8 strain) was found to contain about 11% phospholipid and 5% nucleic acid in agreement with previously reported work. The method of Schmidt and Thannhauser, applied to the nucleic acid fraction of the virus, indicated the presence of 4.5% pentose nucleic acid and 0.3% desoxypentose nucleic acid. When influenza virus was grown in the allantoic membrane of the embryonated egg in the presence of inorganic radioactive phosphorus both phospholipid and nucleic acid components of the virus were found to contain the isotope. The specific radioactivity of the nucleic acid fraction was about four times that of the phospholipid.

ISSN:1923-4287    

DOI:10.1139/cjr50e-026

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

At room temperature, the ascorbic acid content of the brown adipose tissue is doubled when rats are fed a high fat diet. It is nevertheless lower than in tissues studied by others under somewhat similar conditions. In cold adapted rats, the brown body is considerably hypertrophied and the ascorbic acid content is from four to eight times higher than at room temperature. Under our experimental conditions, rats exposed to cold doubled the weight of their perirenal fat with little or no change in total body weight. It is concluded that cold stimulates fat metabolism and that both ascorbic acid and the brown adipose tissue are involved in the process.

ISSN:1923-4287    

DOI:10.1139/cjr50e-027

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Using a purified diet deficient in choline and containing 18% casein, it has been found that in the duckling: (a) betaine and aminoethanol have little or no lipotropic activity, are poor growth factors, and cannot prevent perosis; (b) monomethylaminoethanol and dimethylaminoethanol, on the other hand, have well marked lipotropic activity. Both substances stimulate growth and are antiperotic, dimethylaminoethanol being the most active of the two in these respects; (c) ducklings, like chicks, appear unable to methylate aminoethanol to any extent; (d) a level of 28% casein is more satisfactory than one of 18% in the prevention of fatty infiltration of the liver in ducklings.Betaine and methionine have a definite lipotropic activity, when fed to ducklings along with a semipurified diet containing peanut meal as the only natural ingredient. The substitution of yellow corn meal to sucrose in the above semipurified diet inhibits the lipotropic activity of methionine, without affecting that of betaine.The availability of a protein low in sulphur amino acids has resulted in the preparation of a more hypolipotropic diet. On this diet, ducklings presented livers containing, on the average, 24% of lipids. Methionine added to this diet is strongly lipotropic, but is without effect on growth. Methionine will promote growth only in presence of choline.Ducklings like chicks and poults appear to be able to convert methionine to cystine. In presence of 0.4% cystine, approximately 0.5% methionine is required for normal growth.

ISSN:1923-4287    

DOI:10.1139/cjr50e-028

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

A stable antibiotic was produced by a strain ofMicrococcus epidermidisthat showed a wide range of activity against Gram-positive organisms. A mucoidStreptococcus pyogeneswas used as test organism. This strain could be made resistant by being grown in increasing concentrations of antibiotic but the organism reverted to its original susceptibility immediately on transfer to medium without antibiotic. There was no antiluminescent activity when tested onPhotobacterium fischeri. The test organism was not lysed by the antibiotic. The active substance was dialyzable, was remarkably heat stable, and was soluble only in water or, providing water was present, in solvents that were completely miscible with water. Purification was successful only to the extent of removing a number of inactive fractions by differential solubilities. The activity was destroyed by trypsin but not by pepsin. The physical and chemical data make it probable that the substance is a polypeptide of low molecular weight.

ISSN:1923-4287    

DOI:10.1139/cjr50e-029

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Anin vitrostudy has been made of the oxygen uptake of mammary gland tissue of female rats in various experimental states. Because of the very high proportion of fat in mammary tissue the values ofare determined on a fat-free as well as a water-free basis, thus providing a more accurate measure of the oxygen consumption of this tissue. The oxygen utilization by mammary gland of pregnant animals is increased approximately three times over the activity in the normal, or resting, gland. This increase is maintained during lactation and a return toward normal levels occurs during postlactational involution. The response top-phenylenediamine indicated that during lactation the increased energy requirements decreased the reserves of the cytochrome system in mammary tissue. There is a well developed mammary gland in adult male rats; but the average fat content and response top-phenylenediamine of the tissue are almost identical with values for adult female rats. The use ofp-phenylenediamine as a histological stain for the cytochrome system in mammary tissue is described.

ISSN:1923-4287    

DOI:10.1139/cjr50e-030

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

In 19 subjects with chronic occlusive arterial disease an intramuscular injection of 75 mgm. Priscoline (2-benzyl-2-imidazoline) was found in most cases to produce a greater rise in toe temperature than did the body warming procedure of Gibbon and Landis. In five subjects the vasodilating property of Priscoline was found to be superior to that of spinal anesthesia. In four cases the results with Priscoline predicted the effect of sympathectomy with greater accuracy than did the body warming test. The superiority of the Priscoline test was ascribed to the presence of denervation sensitivity due to a disturbance of sympathetic innervation occurring in association with occlusive arterial disease.

ISSN:1923-4287    

DOI:10.1139/cjr50e-031

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

In addition to the two forms of haemoglobin previously recognized in the blood of the foetus and newborn, a third form has been detected by following the rate of reaction with sodium hydroxide. This component appeared in 33 of the 66 samples studied but could not be detected in the remainder. No explanation could be found for this anomaly. Confirmation was obtained of the presence of a second form of haemoglobin in adult blood. This was shown to differ from the most refractory fraction of foetal blood. It is suggested that the older terminology is no longer sufficiently definitive and an alternative scheme is proposed.

ISSN:1923-4287    

DOI:10.1139/cjr50e-032

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The total bilirubin, total haemoglobin, and haemoglobin fractions were studied in the cord blood and in the heel puncture blood at one, three, and seven days, and at three or four weeks after birth, in 32 normal newborns. No relationship was found to exist between the rate of destruction of the total haemoglobin, or of its most refractory componentf3and the degree of bilirubinaemia. The proportion of thisf3, component did not always undergo progressive steady destruction, nor did it seem to be selectively destroyed in the neonatal period and it would not appear to play any special role in the production of neonatal jaundice.

ISSN:1923-4287    

DOI:10.1139/cjr50e-033

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Well marked interference is demonstrable when LCM virus is injected cerebrally in hamsters and MM virus peritoneally four or seven days later, the usual paralyzing action of the latter virus being prevented. This interference can still be demonstrated when the MM virus is injected 30 days after the LCM virus, but not when the sequence of the injections is reversed. The unparalyzed survivors of a successful interference experiment are actively immune to LCM virus. The brain, cord, and viscera of survivors, tested 10 and 11 days after the beginning of an interference experiment, contain the same amount of LCM virus as the organs of controls inoculated with this virus alone. The same organs, however, contain significantly less MM virus than the organs of controls inoculated with MM virus only. It appears that in a successful interference experiment, MM virus is prevented from multiplying in the organs of the hamster for at least six or seven days. Observations on the distribution of LCM and MM viruses in the viscera, brain, and cord of normal hamsters show that in both instances the blood is quickly invaded, and thereafter viral growth occurs in the viscera as well as the central nervous system. The reaction between the two viruses probably therefore occurs in viscera as well as central nervous system.

ISSN:1923-4287    

DOI:10.1139/cjr50e-034

出版商:NRC Research Press    

年代:1950

数据来源: NRC