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Biomedical subjects

Q R Rogers

Publications and source records attributed to Q R Rogers.

At least 73 records · Page 4Linked to original sources
PubMed1994

Rats on a macronutrient self-selection diet eat most meals from a single food cup.

Computerized meal pattern analysis was performed on female Sprague-Dawley rats (n = 10). Rats were housed for 14 days in cages adapted for macronutrient selection. Rats selected their diet from vitamin and mineral supplemented, semipurified sources of carbohydrate, fat and protein, in three individual food cups. For analysis of meal patterns, minimum meal size was > 50 mg, and mean minimum intermeal interval was 7.9 min. Daily energy intake averaged 289.0 kJ, with 75% occurring during the dark cycle. Energy intake was 28% carbohydrate, 50% fat and 22% protein. Of 12.3 daily meals, 56% were from one, 35% from two, and only 9% of the meals were from three food cups. Seventy percent of the time carbohydrate was the first meal of the dark cycle. The average number of meals per day eaten from carbohydrate, fat, and protein were not significantly different (6.9, 6.2 and 5.6, respectively, p > 0.05). Energy intake for a meal was greatest when fat was eaten (18.35 kJ), than when either carbohydrate (8.68 kJ) or protein (8.97 kJ) was eaten. Meal duration was 7.03 min for carbohydrate, 3.75 min for fat, and 7.47 min for protein. These results provide evidence that rats on a macronutrient self-selection diet eat most meals from a single macronutrient source.

Animals↗
PubMed1994

Concentrations of amino acids in plasma from 45- to 47-week gestation mares and foetuses (Equus caballus).

Concentrations of 16 of 24 amino acids in plasma of foetuses were significantly higher, while four of 24 were lower, than their concentration in maternal plasma. The higher foetal concentrations of amino acids in plasma are similar to other species, with some exceptions, and suggest that equine placenta actively transports and concentrates amino acids into the umbilical circulation. Concentrations of nine of 24 amino acids were significantly lower in plasma from the umbilical artery compared to plasma from the umbilical vein, while no significant differences were present between maternal artery and vein plasma. The umbilical venous-arterial difference in concentrations of amino acids in plasma suggests the foetus extracts amino acids from the umbilical circulation for catabolism or protein synthesis, as in other species.

Amino Acids↗
PubMed1994

The histamine content of commercial pet foods.

The histamine contents of a range of North American commercial pet foods and pet food ingredients were determined by a spectrofluorometric technique. The change in histamine content of open cans of pet food stored in a refrigerator or at room temperature was also investigated. The histamine content of the pet foods examined ranged from a low of 0.16 microg/g in a liquid critical care diet to a high of 65.5 microg/g in a canned fish diet. The amount of histamine in the foods tested was insufficient to cause histamine toxicosis but it cannot be excluded that some of the foods contained sufficient histamine to cause idiosyncratic reactions in histamine-sensitive cats. Storage of opened cans of pet food, either under refrigeration or at room temperature, did not significantly increase the histamine content of most pet foods.

Journal Article↗
PubMed1994

Dietary cysteic acid serves as a precursor of taurine for cats.

The ability of cats to use dietary cysteic acid as a precursor for taurine was examined. For 39 wk, six groups of four specific-pathogen-free cats each were fed purified diets that provided either 1.25 g taurine or 0, 1.0, 2.0, 10 or 20 g cysteic acid/kg diet. Concentrations of taurine in plasma and whole blood were measured weekly for 13 wk and monthly until 39 wk. Muscle concentrations of taurine at 12 wk were measured on a biopsy sample of the semitendinosus muscle. Fecal and urinary excretions of taurine and cysteic acid at 17 wk were measured. Concentrations of taurine in plasma and whole blood were linearly and positively correlated with cysteic acid in the diet (r2 = 0.88). Urinary taurine, a major route of excess taurine excretion, was positively correlated with the cysteic acid concentration of the diet (r2 = 0.94). Muscle and whole-blood taurine concentrations were also positively correlated (r2 = 0.96) with dietary cysteic acid concentration. Gross and histopathological examinations were performed on cats fed diets containing 20 g cysteic acid/kg diet. No adverse gross clinical signs were observed in cats fed any diets containing cysteic acid; minor histopathologic changes of the pancreas and thyroid were found in three of four cats fed 20 g cysteic acid/kg diet. Results suggest that cats are able to use dietary cysteic acid as a precursor for taurine biosynthesis.

Administration, Oral↗
PubMed1994

Kittens choose a high leucine diet even when isoleucine and valine are the limiting amino acids.

This study was conducted to determine the effect of excess leucine on the dietary choice of kittens. The basal diets contained 16% (low nitrogen) or 24% (adequate nitrogen) amino acids and were limiting in isoleucine and valine. The addition of leucine to either of these basal diets has been shown to cause a transitory adverse effect on the growth and food intake of kittens. In separate experiments each basal diet was used to test three sets of choices: basal vs. basal + 10% leucine; basal + alanine vs. basal + leucine (isonitrogenous) and basal vs. basal + alanine. When offered basal vs. basal + excess leucine, the kittens chose significantly more of the excess leucine diet regardless of the level of nitrogen in the basal diet. When offered an isonitrogenous choice of excess alanine vs. excess leucine, the kittens selected somewhat more of the excess leucine diets over the excess alanine diets; this selection was sustained longer in kittens fed low nitrogen. In the third choice experiment (basal vs. basal + alanine), the group offered the low nitrogen diets exhibited no preferences, and the group offered adequate-nitrogen diets selected significantly more of the excess alanine diet. These results for kittens are opposite to those for rats, a species that will select a low protein basal or even a protein-free diet over a diet containing excess leucine.

Animals↗
PubMed1994

Nitrogen balance, plasma free amino acid concentrations and urinary orotic acid excretion during long-term fasting in cats.

The purpose of this study was to ascertain the changes in nitrogen balance, plasma free amino acid concentrations, urinary orotic acid excretion and body weight during long-term fasting in adult obese cats. Results from eight cats that fasted rather than eat an unpalatable diet are reported. After 5 to 6 wk of weight loss, six of the eight cats developed signs of hepatic lipidosis, and the livers of all cats were severely infiltrated with lipids. Cats lost (mean +/- SE) 33.2 +/- 1.4% of their pre-fasting body weight. Mean nitrogen balance (+/- SE) was -547 +/- 54 mg.d-1.kg-2/3 for the first week, and then the net nitrogen losses decreased to a plateau (-303 +/- 52 mg.d-1.kg-2/3) after 4 wk. Fasting was associated with a decrease in plasma concentration of essential amino acids. When plasma amino acid concentrations were considered individually, concentrations of alanine, methionine, taurine, citrulline, arginine and tryptophan decreased the most (> or = 50%), whereas concentrations of glutamine, glutamate and ornithine significantly increased. Orotic acid was not detected in the urine during the fast. After 1 wk of fasting, obese cats had reduced nitrogen excretion, but not to the same extent as has been shown in obese humans or obese rats. It is suggested that the availability of several amino acids may become limiting for liver protein synthesis during fasting and that these deficiencies may contribute to the development of hepatic lipidosis. Orotic acid was not linked to hepatic lipidosis caused by fasting in cats.

Amino Acids, Essential↗
PubMed1994

Assessment of the nutritional adequacy of pet foods through the life cycle.

Despite the lack of precise information on the requirements for many of the nutrients essential for cats and dogs and the paucity of information on the availability of nutrients in foods, many commercial diets support excellent growth, reproduction, and maintenance. However, these diets use empirical information that cannot be readily applied to the formulation of new diets. Progress in companion animal nutrition requires more precise information on requirements for various life stages (especially reproduction and maintenance), along with values for the bioavailability of nutrients in dietary ingredients. There is virtually no information on the bioavailability of nutrients for companion animals in many of the common dietary ingredients used in pet foods. These ingredients are generally byproducts of the meat, poultry and fishing industries, with the potential for wide variation in nutrient composition. Claims of nutritional adequacy of pet foods based on the current Association of American Feed Control Official (AAFCO) nutrient allowances ("profiles") do not give assurances of nutritional adequacy and will not until ingredients are analyzed and bioavailability values are incorporated. The AAFCO feeding test provides a superior method for assessing nutritional adequacy to the profile, although the current protocol has procedural and interpretative limitations.

Animal Feed↗
PubMed1994

Microbial degradation of taurine in fecal cultures from cats given commercial and purified diets.

Freshly passed feces were collected from cats (n = 5-7) given cooked and uncooked commercial canned-type diets, casein and soy protein containing purified diets and a commercial extruded diet. The feces were anaerobically cultured in medium containing either taurine, taurocholic acid or [2-3H]taurine for 24 h at 37 degrees C. Taurine degradation in cultures was greatest for cultures from cats receiving diets reputed to cause taurine depletion. Diaminopimelic acid in feces indicated that differences in taurine degradation rate among groups was associated with differences in bacterial numbers in feces. After 6 h of incubation, < 10% of taurocholate and > 60% of taurine remained. Nearly all the tritium on the labeled taurine was recovered as water. These results indicate that deconjugation and deamination are the initial steps in microbial catabolism of taurocholic acid and that enteric microbial growth may be a major determinant of dietary taurine requirement of cats.

Animal Feed↗
PubMed1994

An epizootic of feline herpesvirus, type 1 in a large specific pathogen-free cat colony and attempts to eradicate the infection by identification and culling of carriers.

This study describes the clinical course of an inadvertent feline herpesvirus, type 1 (FHV-1) outbreak in 2 specific pathogen-free (SPF) research and breeding colonies housing 690 cats and assesses a programme that was designed to eradicate the virus from the colonies. The clinical signs observed in these cats were milder, with more eye involvement than those previously described for FHV-1 infection and did not include abortion. FHV-1 eradication was based on the detection and elimination of both active and latent viral carriers. Carrier cats were detected by virus isolation from oral swabs before and after corticosteroid-induced reactivation of FHV-1 excretion. Four per cent of recovered cats were actively shedding virus prior to corticosteroid treatment; 21% of the virus negative cats shed virus after one corticosteroid injection, and 12% of remaining culture negative cats tested positive upon a second corticosteroid treatment 6 weeks later. The colony remained virus free for 8 months after all detectable virus carriers were culled and there was no seroconversion among new kittens. A second epizootic of FHV-1 then occurred among susceptible animals. At this time, all breeding cats that had tested negative after 2 injections of corticosteroids were treated a third time; 23% of them now tested positive for FHV-1. This study demonstrates that corticosteroid treatment can be useful in improving the rate of detection, essential as a basis for decreasing the incidence of enzootic disease, but it is unlikely to detect all possible FHV-1 carriers in large populations of cats.

Animals↗
PubMed1994

Experimental induction of hepatic lipidosis in cats.

The effect of long-term voluntary fasting on hematologic variables, biochemical profiles, and liver histologic findings was assessed in 15 obese cats (> 40% overweight). Clinical signs and laboratory results consistent with hepatic lipidosis were observed in 12 of 15 cats after 5 to 7 weeks of fasting, and were associated with 30 to 35% reduction of initial body weight. Histologic examination of successive liver biopsy specimens revealed that obesity was not associated with liver parenchymal lipid accumulation, but that fasting resulted in lipidosis in all 15 cats. The long-term fast was associated with an early (after 2 to 4 weeks of fasting) and significant (P < 0.05) reduction in serum urea, glucose, and albumin concentrations, and RBC mass. Fasting for 5 to 7 weeks was associated with a significant (P < 0.05) increase in hepatic-associated enzyme activities and in total and direct serum bilirubin concentrations. Significant (P < 0.05) changes in serum alkaline phosphatase developed as early as 3 weeks before the onset of hyperbilirubinemia. Except for development of hepatic lipidosis, cats appeared to tolerate the fast without other adverse effect. This study confirmed that long-term fasting may induce clinical hepatic lipidosis in obese cats. Fasting appears to induce a syndrome of hepatic lipidosis that is indistinguishable from feline idiopathic hepatic lipidosis and may be an appropriate model to study the pathophysiologic features and treatment of hepatic lipidosis.

Alkaline Phosphatase↗
PubMed1994

Temporal changes in concentrations of amino acids in plasma and whole blood of healthy neonatal foals from birth to two days of age.

Temporal changes, as well as differences in distribution, in concentrations of 24 amino acids in plasma and whole blood of neonatal foals were determined from birth to 2 days of age. In addition, differences in concentrations of amino acids in plasma between mare and foal pairs were determined at birth. Significant (P < 0.05) hypoaminoacidemia existed for 15 amino acids in plasma of foals at birth, compared with mares (paired t-test). Concentrations of 7 amino acids (aspartate, glutamate, glutamine, glycine, hydroxyproline, phenylalanine, proline) in plasma of foals were higher (P < 0.05) at birth than in mares, and concentrations of 2 (taurine, tryptophan) were not different (P > 0.05). Significant (P < 0.05) temporal changes for concentrations of 19 of 24 amino acids in plasma were observed during the 48-hour period. Concentrations of 13 of the 19 amino acids in plasma that had significant changes were higher (P < 0.05) at 48 hours. Significant (P > 0.05) effect of time on concentration of 5 amino acids (alanine, methionine, phenylalanine, taurine, threonine) in plasma was not found after birth. Temporal changes in concentrations of 7 amino acids (alanine, asparagine, glutamine, histidine, hydroxyproline, methionine, and threonine) in whole blood were not significantly (P > 0.05) different from those in plasma. Temporal changes for concentrations of the remaining 17 amino acids in whole blood were significantly (P < 0.05) different, compared with plasma. Distribution of the concentrations of 18 amino acids between whole blood and plasma was significantly (P < 0.05) different.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
PubMed1994

Concentrations of amino acids in plasma and whole blood in response to food deprivation and refeeding in healthy two-day-old foals.

Concentrations of amino acids in plasma and whole blood in response to 10 hours of food deprivation were determined in healthy 2-day-old foals (n = 8) and were compared with control values in foals of the same age (n = 8) allowed free access to suckle. In addition, response of concentrations of amino acids in plasma to 15 minutes of free-access suckling was determined at the end of the 10-hour period in both groups. Response of 13 amino acids in plasma of food-deprived foals was significantly (P < 0.05) different, compared with that in control foals. Concentrations of 3 amino acids (alanine, glycine, and phenylalanine) in plasma increased significantly (P < 0.05), whereas concentrations of 7 amino acids (asparagine, citrulline, histidine, ornithine, proline, tryptophan, and tyrosine) in plasma decreased significantly (P < 0.05) during food deprivation. Response of concentrations of 2 amino acids (glycine and histidine) in whole blood was significantly (P < 0.05) different from that in plasma of food-deprived vs control foals. Refeeding of food-deprived foals resulted in significantly (P < 0.05) different responses for concentrations of all but 2 amino acids (cystine and taurine) in plasma, compared with responses in controls. Changes in concentrations of amino acids in plasma and whole blood of foals in response to food deprivation are similar to those in foals with septicemia and in children with grade 1 or 2 kwashiorkor. The significantly different response of food-deprived foals to refeeding may be attributable to increased protein intake or altered physiologic state.

Amino Acids↗
PubMed1994

Effects of protein, lipid, or carbohydrate supplementation on hepatic lipid accumulation during rapid weight loss in obese cats.

Effects of restricted tube-feeding (25% of energy requirements) of protein, lipid, or carbohydrates on body weight loss; hematologic and clinical chemical variables; plasma lipid and amino acid concentrations; nitrogen balance; and hepatic histologic features and lipid concentrations were compared with values in voluntary-fasting cats (control, CON). Twelve obese cats (6.1 +/- 0.1 kg, > 40% above optimal body weight) were randomly assigned to 4 matched treatment groups (n = 3)--protein (PRO), lipid (LIP), carbohydrate (CHO), and CON--and were offered a low-palatability diet for 4 weeks. Cats of the PRO, LIP, and CHO groups were also tube-fed isocaloric amounts (88 kcal of metabolizable energy) of a casein-soybean protein mixture, corn oil, or a dextrin-dextrose mixture, respectively, during the 4 weeks. All cats fasted, rather than eat the low-palatability purified diet. Cats of the PRO group lost weight at a lower rate (P < 0.05) than did cats of other groups. After 4 weeks of fasting, serum alkaline phosphatase activities were higher than reference values in all cats of the CON and LIP groups and in 2 cats of the CHO group. At that time, 1 cat of the LIP group had lethargy, hepatomegaly, and hyperbilirubinemia. Total hepatic lipid and triglyceride concentrations increased in all groups during the study, but the increase was significantly (P < 0.05) less in cats of the PRO group, compared with those of the CON and LIP groups, and those of the CHO group, compared with those of the LIP group.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1993

The role of palatability in the food intake response of rats fed high-protein diets.

Male albino rats, trained to eat over a 3-h period, reduced their food intake from 0.38 +/- 0.04 g of a low-protein diet to 0.14 +/- 0.03 g of a high-protein diet, within 1 min following diet presentation. Since this occurred before the metabolic effects of a high-protein diet should be seen, we suggest that, although neophobia could play a role, poor initial palatability may be a significant factor in this early depression in food intake. To differentiate initial palatability from responses to metabolic feedback, we designed a feeding paradigm using positive or negative taste cues and a 6-h feeding period. Pre-treatment with a 6% casein diet containing 0.15% quinine HCl resulted in near equal consumption of a 75% casein and a 6% casein unadulterated diet during the first 30 min after introduction of the diets. Later, the rate of consumption of the high-protein diet was lower than of the lower-protein diet, likely the result of post-absorptive factors. We suggest that prevention of the early reduction in food intake due to initial palatability may facilitate study of post-absorptive response(s) to high-protein diets.

Animals↗
PubMed1993

Learned preference and aversion for complete and isoleucine-devoid diets in rats.

Choice tests using flavored solutions were conducted to demonstrate a learned preference or aversion in rats fed replete (complete) or isoleucine (ILE)-devoid diets. In the first learning trial, rats demonstrated a preference for the flavored solutions paired with the replete diet at 6 and 24 h (p < 0.001), and an aversion for the solutions paired with the ILE-devoid diet at 6 h (p < 0.05). In the second trial, using a different concentration of tastant, rats ingested significantly more of the flavored solution paired with the replete diet at 24 h (11.4 +/- 3.0 g vs. 5.4 +/- 1.0 g, respectively; p < 0.05), and significantly more of a novel flavored solution than of the solution paired with the ILE-devoid diet at 24 h (12.4 +/- 2.4 g vs. 1.7 +/- 0.6 g, respectively; p < 0.001). These results suggest that learning contributes to the rat's ability to self-select diets that promote growth, and that a learning paradigm pairing flavored solutions with complete and indispensible amino acid-devoid diets may be used to demonstrate learned preferences and aversions for such diets in rats.

Animals↗