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Biomedical subjects

A W Anderson

Publications and source records attributed to A W Anderson.

At least 73 records · Page 4Linked to original sources
PubMed1975

Semisolid fermentation of ryegrass straw.

Candida utilis, Aureobasidium pullulans, and Trichoderma viride were grown on pretreated ryegrass straw. The pretreatment consisted of hydrolysis of straw with 0.5 N H(2)SO(4) (water-substrate, 3:1) at 121 C, 100 C, and room temperature and adjustment of the hydrolysate to pH 4.5 to 5.0 with 5 N NH(4)OH. The 121 C pretreatment yielded a material containing 30% sugar and 2.3% N. The fermentation was carried on semisolid substrate (moisture level, 75%) in rotating jars for 2 to 3 days at room temperature. The organisms grew rapidly during the period from 18 to 42 h of incubation. During this period the number of microbial cells increased by 20- to 200-fold, and the level of NH(3)-N decreased from 1.3 to 0.9%. The fermentation resulted in a fourfold increase in protein, fivefold increase in crude fat, and 40% increase in the digestibility of straw. The best result in terms of increasing protein and digestibility of straw was obtained when C. utilis was grown on straw preheated at 121 C.

Journal Article↗
PubMed1973

Quantitative detection of type A staphylococcal enterotoxin by Laurell electroimmunodiffusion.

The detection of staphylococcal enterotoxin A by the quantitative technique of electroimmunodiffusion is described. High dilutions of type-specific rabbit antiserum were used in 1% agarose gels, 1 mm thick, and prepared in 0.05-mug barbital buffer, pH 8.6. Volumes of 10 muliters containing 1.5 to 10 ng of toxin were electrophoresed out of 4-mm diameter wells at 5 mA/cm width of gel. The precipitin cones formed were made visible by first immersing the agarose gels in 0.2 M NaCl and then overlaying the surface with the purified globulin fraction of sheep serum against rabbit globulin, followed by soaking of the gels in 1% aqueous cadmium acetate and staining with 0.1% thiazine red in 1% glacial acetic acid. Fully extended cones, 4 to 23 mm in length depending on toxin concentration and antiserum dilution, were developed in 2 to 5 h of electrophoresis, and visualization was achieved within 2 to 3 h. Because the method is qualitative, quantitative, simple, rapid, and sensitive, it offers a practical tool for the detection of small amounts of bacterial toxins in contaminated foods. The method should also qualify as a sensitive detection device in biochemical procedures which attempt to trace, detect, and identify biological substances in nanogram quantities, provided these substances are antigenic and capable of forming a precipitate with their specific antibodies.

Animals↗
PubMed1971

Comparison of animal sera for suitability in coagulase testing.

The sera of several animals were examined for suitability in coagulase testing. The assay for coagulase-reacting factor (CRF) activities of the whole sera indicated the following relative concentrations of CRF: human > pig > rabbit > horse > bovine, chicken, and lamb. Human, pig, and rabbit sera had adequate amounts of CRF for coagulase testing. The plasmin activities of the different sera, arranged from the strongest to the weakest, were as follows: rabbit > human > lamb > horse > bovine, chicken, and pig. Fibrinolysis was observed when rabbit, human, lamb, or horse sera were incorporated into coagulase test agars. Pig serum was superior to the other sera for use in the plate test for coagulase since it had adequate amounts of CRF and the plasminogen-plasmin system was not activated by staphylokinase or staphylococcal Müller factor. Heparinized pig plasma was more suitable than citrated pig plasma since citrate interfered with the growth of Staphylococcus aureus, and the use of heparinized plasma prevented false-positive coagulase reactions due to citrate utilization.

Agar↗
PubMed1971

Rapid detection and quantitative estimation of type A botulinum toxin by electroimmunodiffusion.

An experimental system is described for the detection and quantitative estimation of type A botulinum toxin by electroimmunodiffusion. The method is shown to be rapid, specific, and quantitative. As little as 14 mouse LD(50) per 0.1 ml of type A toxin was detected within 2 hr. When applied to experimentally contaminated foods such as canned tuna, pumpkin, spinach, green beans, and sausage, the technique detected botulinum toxin rapidly and identified it as to type and quantity. A specific rabbit type A antitoxin was produced for this in vitro system since the equine antitoxin (Center for Disease Control) tested in this experiment was found to be unsuitable.

Animals↗
PubMed1970

Polymyxin-coagulase-mannitol-agar. I. A selective isolation medium for coagulase-positive Staphylococci.

A selective, differential plating medium was developed for the isolation and identification of coagulase-positive and mannitol-fermenting staphylococci. Coagulase produced by growing Staphylococcus aureus caused an opaque zone of fibrin to form around each colony. Several strains of S. aureus produced a visible coagulase reaction by 8 hr, and all strains gave a positive reaction before 12 hr. Mannitol fermentation was usually observed between 12 and 36 hr. Rabbit serum was filtered through Sephadex G-100 to obtain plasmin- and plasminogen-free coagulase-reacting factor (CRF). False-negative reactions, caused by staphylokinase and staphylococcal Müller factor action on plasminogen, were eliminated when this CRF was used. False-positive reactions by lipolytic, coagulase-negative staphylococci were reduced, since gel filtration removed the serum lipoprotein which served as a primary source of opacity. The addition of 75 mug of polymyxin B per ml selectively retarded the growth of S. epidermidis and minimized false-positive reactions caused by citrate-utilizing gram-negative rods. The preparation, characteristics, and use of the medium are presented.

Agar↗
PubMed1969

Comparison of the fatty acids of proteolytic type B and nonproteolytic types E and F of Clostridium botulinum.

Lipids were extracted from vegetative cells and spores of Clostridium botulinum. The total lipids extracted averaged approximately 3.8% of the dry weight of vegetative cells and 2.5% of the dry weight of spores of types 61E, "F," and 115B. The fatty acids were analyzed in the form of their methyl esters by gas-liquid chromatography. Infrared spectroscopy, mercuric acetate fractionation, and silver nitratethin layer chromatography served as complementary means of analysis. The total fatty acids included straight chain, saturated, unsaturated, and cyclopropane acids. Hexadecanoic and tetradecanoic acids were the predominant acids in both the spores and vegetative cells. Together, they comprised over 50% of the total fatty acids. Unsaturated acids were the second major group. These were primarily 7,8-tetradecenoic, 9,10-hexadecenoic, 7,8-hexadecenoic, 11,12-octadecenoic, and 9,10-octadecenoic acids. Nonproteolytic types 61E and "F" possessed an 18-carbon diunsaturate, which was not found in the vegetative cells or spores of proteolytic type 115B. A mechanism for the synthesis of unsaturated and cyclopropane acids was proposed.

Chromatography, Gas↗
PubMed1969

Activation of coagulase clotting by trypsin inhibitor.

Egg white trypsin inhibitor activated coagulase clotting when added to a final concentration between 2 and 60 mg/ml. The greatest increase in clotting rate was observed in reaction mixtures containing the lowest concentrations of serum and plasma. Maximal activation was reached with 40 mg of trypsin inhibitor per ml when either serum or plasma was used as the source of coagulase-reacting factor (CRF). The increased rate of clotting is partly due to inhibition of plasmin. Freezing and thawing reduced plasma clotting inhibition. Soybean trypsin inhibitor also activated the coagulase reaction. The increased rate of clotting was observed with a coagulase preparation from organisms which produced plasminogen activators and with the culture supernatant fraction from organisms which did not activate plasminogen to plasmin. The tube test for coagulase could be made more sensitive for some strains of staphylococci by increasing the concentration of CRF (added as plasma or serum) by adding trypsin inhibitor, or both.

Animals↗
PubMed1968

Isolation and role of nonheme iron protein in Clostridium botulinum.

A type of iron-bound protein was isolated from Clostridium botulinum by a modification of the method used for isolating ferredoxin from C. pasteurianum. This method involved acetone and diethylaminoethyl cellulose treatments followed by ammonium sulfate fractionation. The protein exhibited maximal absorption in the ultraviolet region near 260 mmu. Portions of the isolated iron protein were separated by disc electrophoresis and, following specific iron-bound protein staining, showed a positive reaction in the same position on the gel column as was first demonstrated by use of cell-free extract. Evidence accumulated by use of a cell-free extract of C. botulinum suggests that pyruvate is metabolized through a phosphoroclastic system as demonstrated in other clostridia. It is probable that ferredoxin is an electron mediator between pyruvic oxidase and hydrogenase for hydrogen evolution and acetyl phosphate formation.

Bacterial Proteins↗
PubMed1967

Influence of culture media on the radiation resistance of Micrococcus radiodurans.

The addition of NZ-case (a tryptic digest of casein) to a growth medium (PC) consisting of tryptone, glucose, and yeast extract caused a significant decrease in gamma radiation resistance of Micrococcus radiodurans. The level of radiation resistance was inversely related to the concentration of NZ-case. The ld(50) for this organism was approximately 700 krad when grown in tryptone, glucose, yeast extract, and dl-methionine (TGYM) broth, but it was approximately one-half as resistant when grown in a PC medium containing 0.5% NZ-case (PCNZ). The resistance to ultraviolet light was also reduced. Cultures transferred from PCNZ to TGYM media regained the high level of resistance.

Caseins↗
PubMed1966

Radiation survival of food pathogens in complex media.

When 15 bacterial species representing genera associated with food-borne diseases were irradiated individually, all except Escherichia coli and Streptococcus faecalis showed typical linear dose-survival curves in Hartsell's broth. The minimal lethal dose (MLD) for the organisms tested ranged from 3.0 x 10(5) to 6.0 x 10(5) rad. Salmonella paratyphi B, S. wichita, S. typhi, E. coli, and S. faecalis were found to be the least sensitive to radiation. In commercially canned crabmeat the survival curves of S. typhi, S. paratyphi B, and S. wichita exhibited to varying degrees an initial linear death decline with increasing radiation doses, followed by a distinct tailing effect caused by survival of low numbers at the higher doses. The above species of Salmonella were further individually subjected to gamma-radiation in various dilutions of crabmeat. The "tailing effect" gradually disappeared, with the dose-survival curve tending to become linear as the concentration of the crabmeat decreased.

Crustacea↗
PubMed1965

Ecology of Micrococcus radiodurans.

An ecological study of Micrococcus radiodurans indicated that microorganisms possessing the same morphological and radiation-resistance characteristics as that organism could be isolated from ground beef and from pork sausage. Further studies showed that such organisms also could be isolated from beef hides and from water from a creek adjacent to the packing plant from which the meat samples were obtained. Similar microorganisms were not isolated, however, from a limited number of samples of soil, hay, and fecal material. The use of high levels of gamma-radiation in the initial isolation procedures proved to be advantageous in inactivating most of the other microflora and facilitating the isolation of M. radiodurans. Control experiments indicated that M. radiodurans did not compete well with the microflora present in ground meat, soil, and beef hides. Preincubation before irradiation of meat and soil samples or enrichment culture techniques did not enhance the isolation of M. radiodurans. The presence of M. radiodurans in creek water suggested one possible source of this organism.

Ecology↗