Sterilization Value Research Articles

Immunogenicity of irradiated Salmonella typhimurium cells and endotoxin.

The effects of high doses of radiation (1, 5, or 20 Mrad) on the toxicity, pyrogenicity, and immunogenicity of Salmonella typhimurium cells and endotoxin were studied. Toxicity decreased progressively after exposure to 1, 5, or 20 Mrad. The lethal effect of 1-Mrad exposed cells was greater than that of heat-, acetone-, or alcohol-killed preparations. An amount of 5 Mrad is about a 50% end point in terms of inactivation of the lethal lipopolysaccharide or cell-associated determinants. The fever response to radiation-killed salmonellae decreased between 1- and 20-Mrad exposure. The immunogenicity of 1-Mrad-treated cells usually exceeded that of nonirradiated preparations in mouse-protection tests. With increasing radiation doses, there was a dramatic decrease in, but not an abolition of, immunogenicity. Preparations exposed to 20 Mrad which were nonlethal afforded significant protection. The results are interpreted as a reflection of a dissociation of the primary and secondary toxic determinants of endotoxin after irradiation. The data indicate the potential value of radiation sterilization as a means of production of Salmonella vaccine.

VOLUNTARY STERILISATION FOR FAMILY WELFARE: A Proposal by the Simon Population Trust

The value of sterilization for couples who have completed their families depends upon how satisfied they are with the contraceptive methods in general use. The legal background of sterilization in Britain is reviewed. Indications for sterilization are 1)eugenic; 2)therapeutic; 3)socioeconomic; and 4)convenience. Therapeutic indications rarely apply to men. Certain precautions are listed including written consent of applicant and spouse religious objections and existence of neurosis or psychosis. 75% sterilized women were found to be entirely satisfied and less than 5% expressed regret over the ste rilization. Reports on the success of sterilization abroad are summarized. The Simon Trust holds that voluntary sterilization can help solve some family problems and encourages this practice in the United Kingdom.

STUDIES ON THE BIONOMICS AND CONTROL OF THE BURSATE NEMATODES OF HORSES AND SHEEP: V. COMPARISONS OF THE LETHAL EFFECTS OF SOME NON-NITROGENOUS FERTILIZERS ON THE FREE-LIVING STAGES OF SCLEROSTOMES

The effect on the free-living stages of sclerostomes of some non-nitrogenous artificial fertilizers, containing potash, phosphoric acid or calcium, is discussed. Of these fertilizers kainit has most practical advantages. Under the conditions of the experiments, which are otherwise ideal for the survival of the larvae, one part of kainit to 23 parts of fresh horse feces is necessary to sterilize them. The proportions in which the other fertilizers must be mixed are:—Muriate of potash 1:17, (potassium chloride, one of the main constituents of the previous fertilizer, is rather more lethal); carbonate of potash 1:13; sulphate of potash 1:5. Superphosphate (20%) sterilized when mixed at 1:5, and 16% superphosphate required 2:5. Basic slag and raw rock phosphate (Florida) had no sterilizing value. Lime, in spite of its reputation as a sterilizing agent for many pests has, when mixed with fresh feces, little effect on the free-living stages of sclerostomes.

Hot Air Sterilization of Dairy Utensils

Summary 1.The destructive effect of hot air on various types of bacteria is shown. 2.A temperature necessary for effective sterilization of utensils has been determined which seems to make the process of hot air sterilization practical for dairy farms or plants where utensils can be held. 3.The temperature of hot air necessary to cause sterilization in from four to six minutes has been determined. 4.No definite facts have been presented to show the value of hot air sterilization from a practical standpoint. The results merely point out some of the fundamental facts upon which rest the commercialization of the process. This is an engineering and economic problem.