摘要:

The authors have made a survey of the intestinal protozoa in two institutions: an orphanage and an old people's home. Results showed that the incidence of infection was high in both groups but that the younger age group showed a consistently higher rate of infection for all species found.Entamoeba histolyticawas found in 37% of the children and in 20.5% of the 'old-age' group.

ISSN:1923-4287    

DOI:10.1139/cjr47e-001

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Many of the problems concerning penicillin production and research have been found to require reliable assay data within a few hours. For this purpose a three hour turbidimetric assay method was developed, utilizing the increased rate of growth obtained when potassium nitrate was added to a conventional medium. With this rapid method many of the variations of the older 18 hr. incubation procedure, such as autolysis, partial autolysis, and secondary growth effects were avoided. Inhibition occurred during the active growth phase. The method has been checked against standard preparations, and has been shown to give equally reliable results when compared with the cup–plate method of assay.

ISSN:1923-4287    

DOI:10.1139/cjr47e-002

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

A simplified casein digest–corn steep medium is described that lends itself to large scale use. The advantages stressed are: use of fresh or frozen pancreas as a source of trypsin, a digest that is readily clarified, the clarification of corn steep by steaming in alkaline solution. The product is a medium that supports good growth of many species of bacteria and in whichClostridium botulinumproduces large and consistent yields of toxin.

ISSN:1923-4287    

DOI:10.1139/cjr47e-003

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

This paper deals with methods of producing high and consistent yields of Type A and Type BClostridium parabotulinumtoxins. It is shown that highly toxigenic strains readily lose toxin producing activity and that this type of variation may be largely prevented by storing in the cold young cultures to be used as inoculum in toxin production. The best medium of those tested consists of tryptic digest of casein, glucose, and yeast extract or clarified corn steep. Maximum growth occurs in 16 to 18 hr. at 35 °C. Growth is followed by gradual autolysis of the organisms, which is approximately complete in four to six days. Appreciable amounts of toxin are produced during the first 24 hr. of growth and a maximum is reached with the complete lysis of the organisms.Toxin may be completely precipitated from the culture fluid at pH 3.9 and may be partially purified by suspension and reprecipitation at pH 3.9. Acid precipitated toxins may be dried in vacuo, by lyophilization or spray drying. Dry toxins have been stored up to two years without loss of toxicity.Average yields per ml. of culture were:A toxin—1 × 106LD50's for the mouse (20 gm.)2 × 105LD50's for the guinea-pig (250 gm.)B toxin—1 × 103LD50's for the mouse (20 gm.)1 × 105LD50's for the guinea-pig (250 gm.)Type A toxin has the same order of toxicity for mice, guinea-pigs, chickens, and goldfish per unit of body weight. Type B toxin is 6000 to 8000 times more toxic for guinea-pigs than for mice, chickens, or goldfish on a body weight basis.

ISSN:1923-4287    

DOI:10.1139/cjr47e-004

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

In the preceding paper in this series it was shown that Type AClostridium parabotulinumwhen grown under accurately controlled conditions on a casein digest – glucose – corn steep medium produced large and consistent yields of toxin. In this paper a modified procedure is described. Cultures were inoculated in the usual manner and incubated for 10 hr., or until growth reached the upper third of logarithmic increase. Concentrate of the same medium was then added by a continuous drip method for 18 to 60 hr., or until the concentration of the medium was doubled to quadrupled.Under these circumstances the organisms continued to increase for some 40 hr. while in the controls in unconcentrated media growth ceased at 18 to 20 hr. The yield of toxin was increased two to three times over the controls in unconcentrated media.

ISSN:1923-4287    

DOI:10.1139/cjr47e-005

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

The return of armed services personnel plus the prospect of an influx of immigrants and tourists from malarious regions of the world has raised the question of the possibility of malaria becoming epidemic in Canada. In Manitoba no indigenous malaria has ever been reported, but the recent influx of carriers has awakened widespread interest in the anopheline fauna of Canada. Recent surveys indicate that anophelines are more abundant in Manitoba than was generally supposed. The anopheline records from the province are summarized and observations on the distribution, habits, and larval habitats ofAnopheles maculipennis occidentalisare reported.A.maculipennis occidentalisis sufficiently abundant and widespread in its distribution to be important as a potential vector, but its efficiency as a vector has not yet been determined. The evidence suggests that, in Manitoba,A.maculipennis occidentalischooses a variety of overwintering habitats both indoors and outside and that not all locations chosen are favourable. The climate of Manitoba in relation to malaria is discussed briefly with a chart of the isotherms for the mean summer temperatures. This shows that a large portion of southern and western Manitoba, where about 90% of the human population lives, lies on the warmer side of the 61° isotherm.

ISSN:1923-4287    

DOI:10.1139/cjr47e-006

出版商:NRC Research Press    

年代:1947

数据来源: NRC