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Biomedical subjects

K J Carpenter

Publications and source records attributed to K J Carpenter.

At least 37 records · Page 2Linked to original sources
PubMed1995

Eijkman's contribution to the discovery of vitamins.

The work by Christiaan Eijkman in Batavia (now Djakarta, the capital of Indonesia) between 1890 and 1900, for which he received a Nobel Prize, is reviewed. While searching for a microorganism responsible for beriberi, he found that a condition of polyneuritis, with similarities to beriberi, could be produced consistently in chickens by feeding them polished rice, and that addition of the silverskin removed during polishing prevented this. He showed further that the silverskin did not act by physically preventing the entry of microorganisms into the endosperm, nor was its action explained by the protein and salts that it contributed. His tentative hypothesis was that this fraction contributed an antidote to a nerve poison produced by the fermentation of starch in the chickens' crop. However, his successor continued to use Eijkman's animal model and was able to show that silverskin supplied some unknown factor(s) that was required regardless of whether or not the diet contained starch. Fractionation eventually showed thiamin to be the active factor.

History, 19th Century↗
PubMed1992

Protein requirements of adults from an evolutionary perspective.

It is argued that the observed minimum needs for protein and individual amino acids by adult humans and animals may merely reflect the diet that their predecessors consumed in the course of their evolution. The ability to adapt to diets with a lower proportion of protein than was ever encountered in practice would have given no competitive advantage. This can explain the limited ability to reduce rates of amino acid catabolism. The protein requirement of domestic cats, obligate carnivores, corresponds to approximately 20% of their energy requirement. Humans adapt to lower levels (approximately 6%). Some urge that higher protein intakes, resulting in higher rates of protein synthesis and turnover, are desirable and that, in general, the more prosperous and successful groups eat more protein. But cause and effect may be reversed. Are higher rates of turnover and catabolism necessarily beneficial? Objective data are still not available.

Adaptation, Physiological↗
PubMed1991

Contribution of the dog to the science of nutrition.

In the 19th century when the basic principles of nutrition were established, the main work was done first in France and then in Germany. In each country dogs were the overwhelming choice as the model experimental animal. In France the complexity of nutritional requirements first came to be appreciated and the inadequacy of gelatin as a substitute for muscle protein was identified. In Germany quantitative balance procedures for nutrients were developed and it was shown that balance could be achieved at many levels after a period of adaptation. In the U.S.A. at the beginning of this century, Russell Chittenden showed that dogs could do well when fed low protein diets so long as they contained some nonprotein factors that were provided by meat and milk. On the basis of that work Joseph Goldberger developed a diet which produced a condition analogous to pellagra in dogs. This led to the discovery that yeast was a potent preventive of the disease and to the eventual identification of niacin as the primary active factor. Work in Britain with dogs as models for experimental rickets gave apparently conflicting results, with either environmental or dietary changes apparently protecting from the disease. Further work showed that calciferol could be obtained either by irradiation of the skin or by the consumption of another animal's store. Lastly, Edward Mellanby's continued work on the rachitic effect of cereals led to the spin-off finding that wheat flour improved with nitrogen chloride, although nontoxic to rats, was responsible for the problem of canine hysteria in dogs that had developed in the 1930s and 1940s. Its use by millers was than banned.

Animal Nutritional Physiological Phenomena↗
PubMed1990

The history of a controversy over the role of inorganic iron in the treatment of anemia.

In the 19th century it was a generally accepted principle that the power of major organic chemical synthesis was confined to the plant kingdom and that animals could only oxidize, hydrolyze and make minor alterations to large molecules, which they ingested as such. Since iron was found to be in organic combination in blood, it seemed likely that natural diets would be found to supply it in essentially the same form. It was not unexpected, therefore, that from 1850 on into the next century large dietary supplements of iron salts were reported to be almost (or entirely) indigestible. Yet iron salts were undoubtedly effective in treating simple anemia. To escape from the paradox, it was argued that iron salts combined with hydrogen sulfide in the gut, thus sparing the natural organic iron of the diet and allowing it to be better absorbed. Despite experiments refuting this hypothesis, the belief that inorganic iron could not be used in hemoglobin synthesis lingered into the 1920s.

Anemia, Hypochromic↗
PubMed1989

A collaborative study of methods of protein evaluation: introductory paper.

The USDA's collaborative study of methods of protein quality evaluation is introduced. It was intended primarily to provide a basis for the evaluation of possibly improved procedures for the labelling of foods as a source of dietary protein. In general, the usefulness of in vitro digestibility procedures has been confirmed, but problems remained for the in vitro evaluation of heat-damaged materials and of some types of pinto beans.

Amino Acids, Essential↗
PubMed1989

The estimation of 'available lysine' in human foods by three chemical procedures.

Seventeen test foods were each analyzed by four methods. Total lysine was measured by conventional amino acid analysis. Reactive lysine was measured with either fluorodinitrobenzene, o-phthalaldehyde or a differential dye-binding procedure. The results were then compared with another group's results from rat growth assays of the same samples for availably lysine. A sample of deliberately heat-damaged milk powder gave a rat assay value corresponding to 64% of its total lysine content; other values were all higher and on average 99% for 7 animal products, and 87% for 9 vegetable products. The correlation coefficient between the two sets of values was 0.95. The 'reactive lysine' procedures failed to give a better prediction of the rat values.

Animals↗
PubMed1989

Effect of environmental enrichment during nutritional rehabilitation on body growth, blood parameters and cerebral cortical development of rats.

Environmental enrichment has been reported to aid recovery from behavioral deficits associated with malnutrition in infants and young rats. This study investigated whether corresponding neuroanatomical changes could be detected. Rats were suckled either by well-fed dams or dams malnourished during lactation. At weaning, well-fed males were either housed in pairs (standard condition, SC) or 12 per large cage with toys (enriched condition, EC) and fed a 17% protein diet (SC control and EC control, respectively). Malnourished pups were fed either a 17% (rehabilitation; "rehab") or a 6% (low protein) protein diet and housed in the SC or EC environment (SC rehab, EC rehab, SC low protein, and EC low protein). After 30 d there were no differences in hematocrit, serum total protein and albumin levels between SC and EC animals. Rehab rats had significantly lower serum total protein and albumin levels than did controls. Cortical thickness and dendritic branching of occipital cortex pyramidal cells were evaluated. Early malnutrition did not permanently affect cortical thickness. EC rehab rats had thicker cortices than did SC rehab rats at almost all locations measured. SC rehab rats had fewer high order dendrites than did SC controls. The difference in dendritic branching between EC and SC rats was 44% among rehab rats, 21% among controls and 11% (not significant) among low protein-fed rats. Environmental enrichment during nutritional rehabilitation enhances dendritic branching and thickness of the occipital cortex.

Animals↗
PubMed1988

Immature corn as a source of niacin for rats.

The variability in the concentration and biological availability of niacin in corn was investigated. Plots of both sweet and field corn were harvested at different stages. In rat growth assays for available niacin, grains harvested at the immature, "milky" stage and then dried gave values of 88 and 74 micrograms/g, respectively. These values were in contrast to the low growth assay values of 18 and 16 micrograms/g for grain harvested at maturity, and even higher than the value of approximately 56 micrograms/g obtained for each immature corn in both the Association of Official Analytical Chemists procedure of chemical analysis and a standard microbiological procedure. However, when the milky grains were precooked at neutral pH, the values from these procedures were higher and agreed with the biological assay results. It is suggested that, during the initial alkaline digestion used for these two procedures, a proportion of the niacin in NAD, the major form of niacin in milky corn, degrades. However, when the materials are first cooked at neutral pH, nicotinamide is released without loss, and the pyridine ring is then stable. The traditional American Indian practice of roasting and drying "green corn" apparently provided a valuable source of niacin.

Animals↗
PubMed1988

Ethanol and leucine as possible stress factors in rats marginally deficient in niacin and vitamin B-6.

Young rats were fed a purified diet containing no niacin (and 0.85 g/kg tryptophan) and only 0.5 mg/kg vitamin B-6. Three supplements were tested in a 2 x 2 x 2 multifactorial experiment: 1) 25 mg/kg niacin plus 7.3 mg/kg vitamin B-6; 2) 15 g/kg L-leucine; and 3) 12.15% (wt/wt) ethanol in the drinking water. The ethanol, for those receiving it, contributed approximately 15% of the rats' total energy intake, and their diets had some of the carbohydrate omitted to maintain approximately the same proportion of energy to other nutrients. The vitamin supplements stimulated 4-wk weight gain (and gain-feed ratio), but ethanol depressed it, and to a significantly greater extent in the absence of the vitamin supplement. Excretion of N1-methylnicotinamide was increased only by the vitamin supplement. Leucine had no significant effects either by itself or by interaction with the other supplements.

Analysis of Variance↗
PubMed1987

Leucine excess and niacin status in rats.

Young rats were fed a niacin-deficient diet with and without 15 g/kg supplementary L-leucine. Both groups grew slowly for 5 wk and showed no difference in the severity of their condition. Nor did their 14CO2 production differ after intraperitoneal dosing with [methylene-14C]tryptophan. In a 2 X 3 X 3 multifactorial trial with a niacin-free basal diet, the effects of 15 g/kg supplementary leucine were compared with isonitrogenous glycine supplements. Half of the diets were also marginally deficient in pyridoxine and resulted in slower growth, but no interactive effect with leucine. The leucine supplement depressed excretion of N1-methylnicotinamide only in the groups receiving supplementary tryptophan. It was also associated with a depression in the level of nicotinamide nucleotides in the rats' livers that was not eliminated by addition of either 25 mg/kg nicotinic acid or 1 g/kg L-tryptophan. The existence of pellagra in Hyderabad, India, has been hypothesized to result from excessive leucine in the diet rather than from a deficiency of niacin/tryptophan. Neither our results with rats nor those of others appear to provide support for this hypothesis.

Animals↗
PubMed1986

The history of enthusiasm for protein.

In the 1890s the USDA recommended over 110 g dietary protein per day for working men. This was based on Liebig's idea that protein was the source of muscular energy and the observation that protein consumption was higher in the more successful (i.e., affluent) social groups or nations than elsewhere. Chittenden's demonstration of physical energy being maintained on one-half this level of intake then led to reassessment of these standards, and attention was transferred to the discovery of trace nutrients and their practical significance. In the 1950s and 1960s protein again received priority attention. The "World Protein Gap" was considered the major cause of infant mortality and retarded development in the Third World but a problem that could be solved by the application of sophisticated technology. It then appeared that such technology was in general inapplicable to the real-life situation of more primitive communities. It was also found that a more equitable supply of ordinary foods could supply adequate protein, provided that, in the case of infants, attention was paid to their not being too bulky to allow adequate energy intake.

Developing Countries↗
PubMed1985

A reexamination of the composition of diets associated with pellagra.

Diets described in historical studies of human pellagra, have been reexamined by using modern tables of nutrient composition. Five apparently pellagragenic diets from field studies were estimated to have niacin equivalents (NE) well in excess of the Recommended Dietary Allowance (RDA), i.e., 6.6 mg/1000 kcal. In these diets, the estimated contribution of riboflavin was below the RDA, i.e., 0.6 mg/1000 kcal. A series of trials of the pellagra-preventive value of different foods carried out by the U.S. Public Health Service from 1920 to 1936 used over 400 women subjects, of whom fifty developed signs of pellagra on diets now calculated to contribute 7.2-10.6 mg NE/1000 kcal. Most of these diets apparently had less than 60% of the RDA for riboflavin. Further calculations, assuming that the niacin in ordinary cereal foods has only 30% bioavailability, still left half of the pellagragenic diets apparently with more than the RDA for "available NE." Possible reasons for the apparent discrepancy between these results and the RDA's calculated from more recent controlled studies are discussed. It is suggested that the pellagra epidemic in the U.S.A. in the early 1900's has not yet been explained satisfactorily.

Biological Availability↗
PubMed1983

The relationship of pellagra to corn and the low availability of niacin in cereals.

The poorest inhabitants of an area generally eat the narrowest range of foods, and one staple (which serves as a cheap source of calories) dominates. In turn, the specific type of malnutrition seen in that area depends upon that predominant staple and how it is processed before consumption. Corn, used here in the sense of "Indian corn" or maize, was brought to Europe from America, and over the period 1750-1850 became the typical peasant's staple in many of the areas bordering the Mediterranean. By the end of that period, it had also come to be recognized that pellagra had become a serious, chronic disease in these same countries, flaring up each spring amongst the poorest people living on diets containing much corn and very little animal food (i.e., meat, eggs or dairy products) or wine and being generally in a state of wretchedness. Nothing of the sort was seen in areas where wheat and rice were the staple foods, even when they were highly milled. Most scientists agreed on this association with corn, though not on what was the true cause-and-effect relationship. Research in the present century has shown that pellagra is primarily due to a dietary deficiency of niacin. However, the niacin content of different foods did not tie in well with their pellagra-preventive value. But then it was discovered that a second nutrient, tryptophan, could act as precursor of the vitamin with approximately one sixtieth of the activity of the actual vitamin. The "niacin equivalent" values of foods (calculated from their content of both nutrients) show a much better correlation with their pellagra-preventive value. Thus, mature corn is lower in niacin content than are wheat and rice; also the mixed proteins of corn are lower in their tryptophan content. What is not explained by the calculation of "niacin equivalent" is the general freedom from pellagra of the peasants in Mexico and Central America, where corn has been the staple for millenia and where poverty, the consequent lack of animal foods in the diet, and general misery, have been fully equal to the conditions in Europe. It has been known for 40 years that analytical values for the niacin content of foods depended greatly on the method of extraction used, with the highest values being obtained after treatment with alkali. We have confirmed with rat growth assays that the niacin in corn, wheat and rice is only about one-third available to this species, even after ordinary cooking at neutral pH.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗