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A T WILSON

Publications and source records attributed to A T WILSON.

31 records · Page 2Linked to original sources
PubMed1953

The egestion of phagocytized particles by leukocytes.

Streptococci that were phagocytized by human or mouse leukocytes were usually enclosed in a digestive vacuole. At times the vacuole emptied itself, discharging the cocci to the outside. Whether the egested streptococci then multiplied in the extracellular environment appeared to depend upon how long they had been in the vacuole. The phenomenon of egestion also involves particles other than bacteria, as shown by observation of an erythrocyte that was phagocytized by a human leukocyte and was hemolyzed intracellularly, forming a cell ghost that was then egested.

Animals↗
PubMed1952

The antistreptococcal property of milk. I. Some characteristics of the activity of lactenin in vitro; the effect of lactenin on hemolytic streptococci of the several serological groups.

The measurement in vitro of lactenin, the antistreptococcal substance of milk, is affected by the size of the inoculum, the temperature of incubation, and the type of medium employed. Hemolytic streptococci belonging to the several serological groups vary in susceptibility to lactenin. All group A streptococci, regardless of type, are highly sensitive to it, and milk receiving a small inoculum sterilizes itself within 48 hours or less. By contrast, most strains of groups B, C, D, and E, although they may temporarily be inhibited, ultimately achieve full growth. Strains belonging to groups F, G, H, K, and L vary in sensitivity, some being fully inhibited and others achieving full growth. When streaked on the surface of milk-agar plates and examined at the end of 24 hours the streptococci fall into two classes: sensitive strains which do not produce visible colonies on the plate, and resistant strains which grow excellently. Very few strains show an intermediate degree of sensitivity. Human and goat milk contain an antistreptococcal principle which appears to be the same as the lactenin of cow milk, since streptococci which are inhibited by milk from one species are inhibited by milk from the others, and vice versa.

Animals↗
PubMed1952

The antistreptococcal property of milk. II. The effects of anaerobiosis, reducing agents, thiamine, and other chemicals on lactenin action.

Lactenin is reversibly inactivated by the exclusion of atmospheric oxygen. It is also inactivated by the sulfur-containing reducing agents cysteine, glutathione, thioglycollic acid, and BAL. Group A streptococci which have been acted upon by lactenin have been killed, and not merely prevented from multiplying, since they cannot be revived by inactivating lactenin through the addition of a reducing agent. Thiamine in great excess inactivates lactenin. The mechanism by which it accomplishes this has not been discovered, but it suggests that the mode of action of lactenin may be to deny thiamine to the lactenin-sensitive cell. Lactenin sensitivity is not, however, related to a requirement for exogenous thiamine, nor does lactenin appear to function by binding environmental thiamine in a form unavailable to the sensitive cell.

Anaerobiosis↗
PubMed1952

The antistreptococcal property of milk. III. The role of lactenin in milk-borne epidemics; the in vivo action of lactenin.

The ability of lactenin to prevent the multiplication of group A streptococci when milk becomes contaminated with that organism accounts in part at least, for the infrequency of milk-borne streptococcal epidemics. From epidemiological studies it has been shown that most such epidemics arise from the consumption of raw milk in which streptococci occur as a result of bovine mastitis due to group A streptococcus. Lactenin fails to prevent the establishment of mastitis due to the group A streptococcus because the milk in the cow's udder is at a low oxidation-reduction potential and the lactenin is inactive. Lactenin, being destroyed by temperatures of 80 degrees C. or above, is absent from canned and powdered milk. When the latter have been diluted or reconstituted, they can serve as excellent growth media for group A streptococci, and epidemics have occurred as a result of contamination of milk supplies of those types. The administration of lactenin by mouth or intraperitoneal injection failed to protect mice from peritonitis or subcutaneous infection due to group A streptococcus.

Animals↗
PubMed1950

The sterilization of bacteriological media and other fluids with ethylene oxide.

Ethylene oxide is an effective sterilizing agent for bacteriological broths, milk, and serum. A short time after it has exerted its sterilizing effect, the treated fluids again become capable of supporting bacterial growth. Ethylene oxide has been shown to destroy a number of aerobic Gram-positive and Gram-negative organisms, aerobic and anaerobic spore-forming bacilli, fungi, and vaccinia virus. No organisms have been encountered which withstand its action. The quantity of ethylene oxide necessary for sterilization depends to some degree on the character of the medium sterilized. None of the materials tested required more than 1 volume per cent of liquid ethylene oxide. Ethylene oxide is highly reactive chemically, and its reactions with many of the components of complex biological fluids cannot be fully anticipated. Regardless of the chemical changes produced, ethylene oxide did not permanently alter the essential qualities of the growth factors in broth and milk which are required by fastidious organisms such as group A streptococci and others. However, its effect on the biological activity of any particular organic compound should be assayed before it can be assumed not to have a deleterious effect. The sterilization of media by ethylene oxide is accompanied by a rise in pH. Fluids which have a relatively high initial pH may require adjustment with sterile acid to return them to the optimal pH for bacterial growth. A mixture of ethylene oxide and broth was toxic to mice for 6 hours after admixture. Toxicity disappeared on incubating the mixture longer, and no residual toxicity could be demonstrated after 6 hours, even on repeated intraperitoneal inoculations. As a means of sterilizing bacteriological media and other biological fluids, ethylene oxide deserves consideration when heat and filtration cannot be used.

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