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Biomedical subjects

F M Loew

Publications and source records attributed to F M Loew.

At least 37 records · Page 2Linked to original sources
PubMed1980

Considerations in receiving and quarantining laboratory rodents.

The development of increased bacteriologic and viral screening has revealed evidence of exposure to possible pathogens in animals from even the best suppliers. Because the cost in money and space to quarantine all rodents in many types of research institutions is great, and because of an increased ability to detect possible pathogens, a dilemma exists. At the same time, regulations are being implemented which, in many cases, mandate a quarantine period. In all cases, however, the professional judgement of laboratory animal medicine specialists is increasingly needed to interpret the best course of action. A proper matching of animal quality with a realistic assessment of research requirements seems the best course, with quarantine implemented where truly appropriate.

Animals↗
PubMed1979

Thiamin deprivation in ventromedial hypothalamic hyperphagic rats: anorexia, specificity of food aversion, and a dietary consideration.

The anorexic consequence of thiamin deprivation was investigated in ventromedial hypothalamic (VMH) hyperphagic rats under either high-fat or low-fat thiamin-free diet conditions. The low-fat diet maintained feeding significantly longer in thiamin-deprived VMH rats than in intact rats, whereas the hig-fat diet sustained feeding in thiamin-deficient intact rats and accelerated anorexia onset in vitamin B1 deprived VMH rats. This effect was noted under both ad lib and pair-feeding conditions. Thiamin-deprived VMH rats subjected to weight control developed anorexia sooner than intact subjects regardless of the diet employed. The VMH rats fed a high-fat diet failed to resume feeding after thiamin readministration, which was interpreted as a permanent aversion to this diet. The relation between dietary intake and conditioned taste aversion is discussed with reference to the VMH and intact rat.

Animals↗
PubMed1978

Effects of plant and animal lipids rich in docosenoic acids on the myocardium of Cynomolgus monkeys.

Cynomolgus monkeys (Macaca fascicularis) were fed diets containing 25% rapeseed oil (RSO), partially-hydrogenated herring oil (PHHO) or a 3:1 mixture of lard/corn oil as control (CON) for 4 months. The RSO contained approximately 25% of the fatty acids as erucic acid (cis-docos-13-enoic, 22:1w9) while the PHHO contained a similar concentration of mainly cetoleic acid (cis-docos-11-enoic, 22:1w11). The CON contained no 22:1 acids. The monkeys developed the expected myocardial lipidosis, somewhat more pronounced in the RSO than the PHHO group, but small foci of mononuclear cell infiltration, while infrequent, occurred in all three groups. Significant intergroup differences in biochemical or hematologic measurements of serum constituents were an increase in serum cholesterol concentration in the RSO group and an increase in serum glutamicoxaloacetic transaminase activity in both RSO and PHHO groups at certain intervals. The shorter proportion of M. fascicularis life span represented by this experiment may account for the absence of clear intergroup differences such as are reported in rats used in similar studies.

Animals↗
PubMed1978

Morphologic effects of dietary plant and animal lipids rich in docosenoic acids on heart and skeletal muscle of cynomolgus monkeys.

Cynomolgi (Macaca fascicularis) were fed diets containing 25% rapeseed oil (RSO), partially hydrogenated herring oil (PHHO), or a 3:1 mixture of lard and corn oil as control for 4 months. The RSO contained approximately 25% of the fatty acids as erucic acid; the PHHO contained a similar concentration of mainly cetoleic acid. The control diet did not include such fatty acids. At the time of necropsy, the RSO- and PHHO-fed monkeys showed myocardial and skeletal muscle lipidosis. Foci of mononuclear cell infiltration, although infrequent, occurred in all three groups and were thought to be nonspecific. The only significant intergroup difference in serum biochemical or hematologic parameters was an increase in serum glutamic-oxaloacetic transaminase activity in both RSO and PHHO groups. Ultrastructural studies confirmed the presence of lipidosis in cardiac and skeletal muscle and revealed mild mitochondrial degeneration, causing a depression of the P/O ratio of the RSO group and a State III respiratory rate depression of the PHHO group. The difference in the exposure/life span ratio represented by this experiment may account for the absence of clear intergroup differences such as are reported in rats used in similar studies, but a true species difference in regard to dietary oils containing docosenoic acids has to be considered as well.

Animals↗
PubMed1978

Subacute toxicological evaluation of sclerotia of Sclerotinia sclerotiorum in rats.

Weanling Wistar rats of both sexes were fed diets containing 0 (control), 1% and 5% ground sclerotia of Sclerotinia sclerotiorum derived from infected rapeseed (Brassica napus). Body weight, feed consumption and clinical appearance were monitored over an 84-day period. Blood samples were collected on days 41 and 84 and necropsies performed on day 84. Weight gain and feed consumption were similar in the control and 1% groups. In the 5% group, weight gain was depressed, feed wastage was greater and at termination more than half the rats were in poor body condition with alopecia and hyperkeratosis of the tail. These effects were probably nutritional and due to unpalatability of the diet. Blood urea nitrogen and blood glucose concentrations did not vary consistently among the groups. Serum glutamic-pyruvic transaminase activity was significantly depressed (p less than 0.001) by consumption of sclerotia. This depression was dose-related and consistent on days 41 and 84. There were no significant differences (p greater than 0.05) between groups in the ratios of liver weight and kidney weight to body weight.

Alanine Transaminase↗
PubMed1977

Heart mitochondrial metabolism after feeding herring oil to rats and monkeys.

Heart mitochondrial oxidation of palmityl CoA and pyruvic acid was studied in rats and in the monkey Macaca fascicularis to determine the effects of feeding partially hydrogenated herring oil. Herring oil glycerides contain cetoleic acid (cis-11-docosenoic) which could have a similar effect to erucic acid (cis-13-docosenoic) in causing a rat cardiomyopathy. The initial rat heart mitochondrial response to dietary cetoleic acid (67% cis, 33% trans) was an in vitro decrease in palmityl CoA oxidation. Pronlonged feeding of cetoleic acid mixture was associated with a significant metabolic adaptation, increasing pyruvate and palmityl CoA oxidation above control levels. In vitro addition of cetoleyl CoA (pure cis isomer) stimulated pyruvate dehydrogenase activity, a possible response to decreased B-oxidation. There was no significant adaptive change in pyruvate or palmityl CoA use in monkeys after prolonged feeding of partially hydrogenated herring oil. Cetoleyl CoA was a good substrate for monkey heart carnitine acyl transferase even in the presence of palmityl CoA. These observations suggest that C22 fatty acids may be metabolized more rapidly in monkey heart than in rat heart. Metabolic differences argue against using the rat as an experimental model for studying possible cardiotoxic effects of docosenoic acids in primates.

Animals↗
PubMed1976

Induction of bovine polioencephalomalacia with a feeding system based on molasses and urea.

Polioencephalomalacia (PEM), a disease first described in the United States and related to intensive beef production, appeared in Cuba coincident with the use of a new, molasses-urea-based diet to fatten bulls. Because the only experimental means so far of reproducing PEM has been with amprolium, a structural analog of thiamin, the present study attempted to induce the disease using the molasses-urea-based diet. Six Holstein bulls (200-300 kg) were studied during consumption of three successive diets: 1) commercial molasses-urea-restricted forage diet of Cuban feedlots, 2) a period in which forage was gradually withdrawn and 3) a forage-free diet composed only of molasses, urea and fish meal. PEM was reproduced in this way. At ten-day intervals, blood concentrations of glucose, lactate, pyruvate and urea were measured, as well as when clinical signs of PEM appeared. The signs, clinical course and lesions of the experimentally induced disease were comparable to those of field cases. The biochemical results suggested a block in pyruvate oxidation as in PEM elsewhere in the world. No evidence existed of urea intoxication. In addition, brain and liver concentration of total thiamin from field cases and normal animals were found to be similar.

Animal Feed↗
PubMed1976

Thiamin status of laboratory rabbits.

Measurements of blood thiamin concentration, erythrocyte transketolase (TK) activity, and stomach and cecal thiamin concentration were made in 10 normal New Zealand white rabbits consuming a commercial pelleted rabbit diet. The concentration of the vitamin was somewhat higher in stomach content (57.2 +/- 11.8 m mug/g) than in cecal content (38.5 +/- 14.9 mmug/g). Erythrocyte TK activity was well within the range reported as normal in other mammalian species (TPP effect=2.6% for hexose and 0.5% for pentose).

Animals↗