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Biomedical subjects

F M Dong

Publications and source records attributed to F M Dong.

12 recordsLinked to original sources
PubMed2000

A new approach to estimating the minimum dietary requirement of phosphorus for large rainbow trout based on nonfecal excretions of phosphorus and nitrogen.

A new method was developed to estimate the minimum dietary requirement of phosphorus (P) for large fish for which conventional methods are not suitable. The method is based upon nonfecal (mainly urinary) excretion of inorganic P and total nitrogen from fish placed in a metabolic tank. In the first experiment, small and large rainbow trout (body wt 203 and 400 g, respectively) and, in the second experiment, P-sufficient, P-deficient and starved rainbow trout (different in diet history; body wt 349-390 g) were fed a constant amount (standard feeding rate) of semipurified diets with incremental P concentrations once daily at 15 degrees C. In all cases, there was no measurable excretion of P when dietary P concentration was low; however, beyond a specific dietary concentration, excretion of P increased rapidly. The point where the fish started to excrete P was assumed to be the minimum dietary requirement. By d 3 of consuming the experimental diets, the response of the fish to dietary P concentration stabilized, and excretion of P remained constant within dietary treatment groups for the subsequent sampling days (d 6, 9 and 12). The minimum dietary requirement of available P for fish having body wt of 203 and 400 g was estimated to be 6.62 and 5.54 g/kg dry diet, respectively, and that for P-sufficient, P-deficient and starved fish was estimated to be 4.06, 5.83 and 4.72 g/kg dry diet, respectively, when feed efficiency is 1.

Animal Nutritional Physiological Phenomena↗
PubMed1999

Survival of Anisakis simplex in microwave-processed arrowtooth flounder (Atheresthes stomias).

The purpose of this study was to define the relationship between survival and temperature of nematodes of the species Anisakis simplex in microwave-processed arrowtooth flounder (Atheresthes stomias). Ten fillets (each 126 to 467 g, 0.5 to 1.75 cm thick), with an average of five larvae of Anisakis simplex per fillet, were processed to target temperatures on high (100%) power using a commercial 700-W microwave oven. Fillets were neither covered nor rotated and had a temperature probe inserted to two-thirds depth into the thickest portion. After the fillet was digested using a 1% pepsin solution, the viability of nematodes was determined by viewing them under a dissecting microscope. Survival rates were 31% at 140 degrees F (60 degrees C), 11% at 150 degrees F (65 degrees C), 2% at 160 degrees F (71 degrees C), 3% at 165 degrees F (74 degrees C), and 0% at 170 degrees F (77 degrees C). Microwave processing of standardized fillet "sandwiches," 14 cm long, 4.5 cm wide, and approximately 1.75 cm high, each of which was preinoculated with 10 live nematodes, resulted in no survival at either 160 degrees F or 170 degrees F. Using ultraviolet light to detect both viable and nonviable nematodes in fillet sandwiches as an alternative method to pepsin digestion resulted in survival rates of 1% at 140 degrees F (60 degrees C), 3% at 145 degrees F (63 degrees C), and 0% at 150 degrees F (65 degrees C). Smaller fillet sandwiches, which most likely had fewer cold spots during microwave processing, required 150 degrees F (65 degrees C), whereas larger whole fillets required 170 degrees F (77 degrees C) to kill larvae of Anisakis simplex. The parasites were most likely inactivated by a thermal mechanism of microwave treatment. Damage to the nematodes was often evident from ruptured cuticles that were no longer resistant to digestive enzymes. The high hydrostatic pressure and low chloride content of the pseudocoelomic fluid probably contributed greatly to the damage incurred by the larvae.

Animals↗
PubMed1994

Fatty acid composition of salmonid muscle changes in response to a high oleic acid diet.

Substitution of high oleic acid sunflower oil for herring oil in formulated salmonid diets affected the fatty acid composition of muscle, liver and visceral fat from coho salmon (Oncorhynchus kisutch) and rainbow trout (O. mykiss). Fish were fed diets containing either high oleic acid sunflower oil or herring oil as the supplemental lipid source (12.4 g/100 g diet) for 1-2 mo. Muscle from fish fed the sunflower oil diet had twice the concentration of oleic acid (approximately 25 g/100 g lipid) as muscle from fish fed the herring oil diet (approximately 12 g/100 g lipid). The maximum concentration of oleic acid in the muscle was obtained after only 2 wk of feeding the sunflower oil diet. Oleic acid concentrations in liver and visceral fat of fish fed the sunflower oil diet were significantly higher than in fish fed the herring oil diet. Rainbow trout fed the sunflower oil diet for 4 wk maintained the higher oleic acid concentrations in muscle and liver when deprived of feed for 2 wk compared with fish fed the herring oil diet. These data indicated that accumulation of oleic acid in coho salmon and rainbow trout muscle was fairly rapidly achieved when a high oleic acid diet was fed. The differences between the fish receiving the two dietary treatments in fatty acid composition and in concentrations of thiobarbituric acid-reactive substances in muscle stored at refrigerated temperatures were consistent with previously reported differences in aroma perceived by a sensory panel.

Adipose Tissue↗
PubMed1992

Application of immunochemical assays to food analysis.

Immunochemical assays are powerful bioanalytical techniques with application to several areas in food science, including food analysis, microbiology, nutrition, food safety, food quality, and process control. In principle, immunochemical techniques can be applied to the analysis of any compound, with only one specific antibody needed that can be obtained either from laboratory animals or, when available, from commercial sources. A well-designed immunochemical assay can detect targeted compounds at levels as low as 10(-12) M. Immunochemical techniques require little or no sample pretreatment, making these analytical procedures relatively rapid. The initial cost of developing an immunoanalytical assay may be high, but when the procedure is well established, the cost per test is often a fraction of that for other analytical methods. For these reasons, immunoanalytical assays provide an attractive alternative for the food analyst who requires either inexpensive qualitative screening tests or reliable quantitative methods with a high degree of sensitivity. This review concentrates on the use of enzyme immunoassay to address analytical problems in food chemistry and the analysis of various food components.

Animals↗
PubMed1992

Molecular cloning and mapping of phenol degradation genes from Bacillus stearothermophilus FDTP-3 and their expression in Escherichia coli.

Two genes of the meta pathway of phenol degradation were cloned from a phenol-utilizing strain of Bacillus stearothermophilus and were mapped by subcloning and by use of a Tn5 insertion mutation. They code for phenol hydroxylase and catechol 2,3-dioxygenase, respectively. The gene encoding catechol 2,3-dioxygenase, which is more thermostable than catechol 2,3-dioxygenase encoded by the other gene, shares rather limited homology with that from Pseudomonas putida.

Catechol 2,3-Dioxygenase↗
PubMed1992

Irradiated or aseptically prepared frozen dairy desserts: acceptability to bone marrow transplant recipients.

Sterile ice cream and frozen yogurt were offered to immunosuppressed patients recovering from bone marrow transplantation. To obtain sterile products, two of the dairy desserts (prepackaged ice cream and frozen yogurt bars) were exposed to 40 kGy of cobalt 60 irradiation. Four different flavors of ice cream were aseptically prepared under a laminar airflow hood using commercially sterilized ingredients. A commercially sterile, frozen milk-based drink on the low-microbial menu served as the control. Ratings of the seven products by 17 patients indicated that a frozen vanilla milk-based drink and aseptically prepared chocolate ice cream were highly acceptable to recovery immunosuppressed patients who have difficulty eating most foods. However, the seven desserts received higher ratings from a sensory panel of healthy individuals than from the patient panel, confirming that new foods for the low-microbial diet should be "market-tested" by the targeted patient population before inclusion in the menu.

Adult↗
PubMed1980

Incidence of increased numbers of Clostridium perfringens in the intestinal tract of rats fed xylitol.

Sprague-Dawley rats were fed diets containing up to 20% xylitol for 49 days. When the rats were fed a xylitol regimen intended to produce adaptation to xylitol, approximately half of the animals adapted to xylitol and remained free from diarrhea during the feeding regimen. The other half did not adapt to xylitol and developed severe and persistent diarrhea accompanied by large volumes of intestinal gas. These non-adapted rats had significantly higher levels of intestinal tract Clostridium perfringens (10(6)--10(11) organisms per gram intestinal contents) than did control rats fed a xylitol-free cornstarch diet (0-10(4) organisms per gram). Rats adapted to dietary xylitol did not have detectable levels of C. perfringens in the gastrointestinal tract.

Adaptation, Physiological↗
PubMed1980

Effects of alanine on gluconeogenesis in isolated rat hepatocytes.

The effect of alanine on pyruvate kinase was investigated in isolated rat hepatocytes. Alanine at concentrations of 2, 5 or 10 mM increased glucose production by 73% during the first 30 minutes of incubation of hepatocytes with 9 mM lactate and 1 mM pyruvate. After 3 minutes, the rate was not affected by the addition of alanine. A dose-response study showed that maximal stimulation of gluconeogenesis was achieved with 0.5 mM alanine. Using a method that measured recycling of phosphoenolpyruvate to pyruvate, it was found that in either fed or starved rats, alanine significantly decreased the percentage of phosphoenolpyruvate recycling when lactate was the substrate. However, no significant change in recycling was noted when either pyruvate or lactate-pyruvate was the glucose precursor. This study suggests that in intact liver cells, alanine has an inhibitory effect on pyruvate kinase. However, the inhibition is not of sufficient magnitude to completely account for the increase in glucose production when lactate is the substrate. It is hypothesized that alanine may have other effects on gluconeogenesis in addition to that of inhibiting pyruvate kinase.

Alanine↗
PubMed1980

Effects of dietary xylitol on redox state and gluconeogenesis in the rat liver.

Rats fed a 20% xylitol diet were compared to rats fed for 6 weeks a diet of either 20% glucose, cornstarch or sucrose (plus 45% cornstarch), or the AIN-76TM diet (basal diet). There were no differences between the rats (diarrhea-free) fed xylitol and those fed the other carbohydrate sources in the lactate/pyruvate ratio in freeze clamped livers. Gluconeogenesis was measured from 10 mM of various precursors in isolated hepatocytes. Rats fed xylitol had: a) a lower rate of glucose production from lactate compared to rats fed the sucrose, glucose or basal diet; b) a lower rate of gluconeogenesis from xylitol than in rats fed either the basal or glucose diets, and c) equal capacity to produce glucose from pyruvate, glycerol, dihydroxyacetone or alanine as rats fed the other diets. Ethanol added to isolated hepatocyte incubations did not have a greater inhibitory effect on gluconeogenesis in xylitol-fed animals than in those fed the other carbohydrates. Results of this study indicate that dietary xylitol has little effect on the hepatic cytosolic redox state or on the ability of the rat liver to produce glucose in the presence of ethanol, but may have an effect on the rate of glucose production from some precursors.

Animals↗