Biomedical subjects
A M Pearson
Publications and source records attributed to A M Pearson.
Further factors influencing N-nitrosamine formation in bacon.
The possible relationship of unsaturated fatty acids in adipose tissue to the formation of N-nitrosamines in bacon was evaluated by trials in which pigs were fed regular (control), tallow-, coconut fat- and corn oil-supplemented diets. Bacon prepared from pigs fed corn oil-supplemented diets contained significantly higher levels of N-nitrosopyrrolidine and N-nitrosodimethylamine than did control bacon samples; however, bacon produced from pigs fed a coconut fat-supplemented diet contained significantly lower levels of N-nitrosopyrrolidine. Fatty acid analyses of the adipose tissue of the bacon samples indicated that N-nitrosopyrrolidine levels in bacon correlated well with the degree of unsaturation of the adipose tissue. N-nitrosothiazolidine was detected in both brine-cured and dry-cured bacon at levels generally below 4 micrograms/kg. However, its formation was greatly reduced by the inclusion of alpha-tocopherol in the cure. The role of woodsmoke in N-nitrosothiazolidine formation in bacon is discussed.
Educational attainments of spina bifida children attending ordinary or special schools.
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Salt-its use in animal products- a human health dilemma.
High Na intake has been identified as one possible contributor to development of hypertension that occurs in 10 to 20% of the United States population. Per capita intake of salt, which is the major source of Na in the diet, is estimated to average 10 to 12 g/d. Discretionary use accounts for about 3 to 4 g, with an equal amount naturally present in unprocessed foods and 4 to 6 g being added during processing. Theories concerning the possible role of salt in development of hypertension are reviewed. As a result of the possible relationship of salt intake to hypertension, the Food and Nutrition Board has recommended that salt consumption be reduced to 3 to 8 g.capita-1.d-1. This would require a reduction in the amount of salt added by discretionary use and (or) during processing. The amount of salt found in various raw and processed animal products is presented and the role and importance of salt in these products are examined. Consideration is then given to methods that may be adopted to reduce Na consumption and the potential influence of these methods upon various animal products.
Educational attainments of spina bifida children attending ordinary or special schools.
Children with spina bifida who attend special schools are usually found to be retarded in their school attainment compared with those who attend ordinary schools. This finding has, however, often been confounded by the fact that the special school children tend to have lower IQs. In this study two groups of children were identified from those in the Greater London Council (GLC) Spina Bifida Survey, one attending ordinary and the other special schools. There were 11 pairs of boys and 11 of girls, each pair being closely matched for IQ. Examination of their scores on attainment tests showed that while results of reading tests did not differ significantly between the two types of schools, children of both sexes at special schools were behind their ordinary school counterparts in number work. These results were supported by similar findings, using analysis of co-variance, on the larger group of children in the GLC survey. The effect of other factors such as physical handicap, presence of a valve, and time spent in hospital, were explored, and possible explanations for the findings are discussed.
Effects of ad libitum, maintenance and sub-maintenance feeding and of compensatory growth on some biochemical properties of muscle from weanling rabbits.
Weanling male rabbits were fed either: 1) a complete diet ad libitum (control); 2) a maintenance diet; or 3) a sub-maintenance diet. After 20 days, half of each group was slaughtered and the remainder was placed on treatment 1 until they achieved the same body weights as the controls (about 30 more days), when they were also killed. Body organs, including livers, hearts, lungs and kidneys, were significantly reduced in weight by nutritional stress. Maintenance and sub-maintenance feeding resulted in creases in ultimate muscle pH, water content and alkali-soluble and -insoluble stromal proteins. The intracellular proteins, especially the myofibrillar fraction, decreased markedly, depending on the degree of nutritional stress. Swelling of the stromal proteins was less for the underfed rabbits, indicating that nutritional stress increased the number of acid-stable corss-linkages. Calcium-induced contraction was not effected by any of the nutritional treatments. Blood enzymes were not affected by nutritional stress from the standpoint of their multiple molecular forms, mobility or band profiles. All differences in muscle characteristics disappeared during compensatory growth except for the increased amount of alkali-insoluble stroma protein. The concepts of labile, mobilizable and fixed body proteins are discussed.
Structural characteristics of porcine skeletal muscle giant myofibers as observed by light and electron microscopy.
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Premeromyosin--an initial product of trypsin proteolysis in isolated myofibrils.
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Improved resolution of myofibrillar proteins with sodium dodecyl sulfate-polyacrylamide gel electrophoresis.
Standard experimental procedures for continuous polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate were modified to give more effective separation and improved resolution of myofibrillar proteins. The system utilizes a running gel consisting of 10% acrylamide with 0.1% bisacrylamide crosslinker (100:1) incorporating 400 mM Tris/glycine (pH 8.80), 0.1 mM ethylenediaminetetraacetate, 5% glycerol and 0.1% sodium dodecyl sulfate. Electrophoresis was performed at 1 mA per gel with corresponding running times of 4-6 h. The myosin heavy chain enters and migrates as a narrow symmetrical band while the smaller regulatory proteins of the myofibril are resolved. The utility of the procedure in relation to the study of protein structure is detailed.
Some factors that may alter consumption of animal products. A review.
Trends in consumption of animal products are discussed, including reasons for changes. Although consumption of some products has increased--notably that of broilers and beef--for other products, it has declined, i.e., total dairy products and eggs. Evidence shows that consumers desire a lower fat content in both meat and dairy products, although, in the case of meat, minimal levels are necessary for palatability. Overall, it is suggested that consumers are concerned with nutritional quality and are influenced by health-related concerns. The use of vegetable proteins as extenders and substitutes for animal proteins is reviewed, with the conclusion that they will continue to influence consumption of animal products.
Isolation of an extracellular neutral proteinase from Pseudomonas fragi.
A single proteolytic enzyme (EC 3.4.4.-) was isolated from culture supernatants of Pseudomonas fragi with 20% yielded and 60-fold purification by means of stepwise DEAE-Sephadex batch adsorption, ammonium sulfate precipitation, gel filtration and DEAE-cellulose chromatography. The enzyme was Zn-2+ activated and Ca-2+ stabilized, had optimum activity at pH 6.5--8.0 and 40 degrees C. The molecular weight range was 40 000--50 000 as determined by dodecylsulfate gel electrophoresis, gel filtration and Zn assay. This proteinase has properties similar to other extracellular bacterial neutral proteinases.
Proteolytic enzyme preparation from Pseudomonas fragi: its action on pig muscle.
An extracellular preparation from Pseudomonas fragi with proteolytic enzyme activity was isolated, and its action on meat proteins and meat protein ultrastructure was studied. First, a suitable growth medium for proteolytic enzyme production was determined, and a method for partial purification of the proteolytically active fraction was developed. The enzyme preparation displayed optimal proteolytic activity at neutral pH and 35 C. Proteolytic activity was irreversibly lost by mild heat treatment. The enzyme preparation was tested for its ability to hydrolyze isolated pig muscle proteins. Myofibrillar protein was rapidly degraded, G-actin and myosin were broken down at a slower rate, and the sarcoplasmic proteins were least susceptible to hydrolysis. Electron micrographs of pork muscle showed that the proteolytic enzyme preparation caused a complete loss of dense material from the Z line. Similarities are discussed between the action of P. fragi extracellular proteolytic enzyme(s) on meat and normal bacterial spoilage of meat.
Helminths of wolves, Canis lupus L., in the Yukon and Northwest Territories.
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Hematology of the brown bear (Ursus arctos) from southwestern Yokon Territory, Canada.
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Blood chemistry of the brown bear (Ursus arctos) from southwestern Yukon Territory, Canada.
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Isoelectric focusing of S- -(4-pyridylethyl)-L-cysteine myosin components on polyacrylamide gel.
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Action of Pseudomonas fragi on the proteins of pig muscle.
Considerable salt-soluble protein degradation was observed in pork muscle inoculated with Pseudomonas fragi. During a 20-day incubation period at 10 C, the samples proceeded to rank spoilage or putrefaction. There was a large decrease in the salt-soluble protein fraction and a corresponding increase in nonprotein nitrogen. Disc gel electrophoretic patterns showed that breakdown of the salt-soluble proteins had occurred after incubation for 20 days. During incubation for 10 days at 10 C, P. fragi produced large amounts of extracellular proteolytic activity in ground pork. Most of the proteolytic activity appeared immediately after spoilage occurred. However, a significant increase in the ability to hydrolyze casein and a slight increase in the ability to hydrolyze denatured hemoglobin occurred prior to spoilage.
Observations by electron microscopy on pig muscle inoculated and incubated with Pseudomonas fragi.
Myofibrils from pig muscle inoculated and incubated with Pseudomonas fragi showed an extremely disrupted appearance as compared to uninoculated controls. There was an almost complete absence of material in the H zone, marked disruption of the A band (probably myosin), and some loss of dense material from the Z line. These changes indicated that marked proteolysis had occurred. Bacteria observed in spoiled muscle tissue exhibited protrusions or blebs on the outer surface of the cell walls. The blebs appeared to form detached globules that migrated into the muscle mass. Bacteria grown in non-muscle-containing media did not produce blebs, which indicates the blebs were induced by growth on muscle tissue. The possibility that the blebs and globules may contain a proteolytic enzyme responsible for myofibrillar disruption is discussed.