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Biomedical subjects

N Hrboticky

Publications and source records attributed to N Hrboticky.

28 records · Page 2Linked to original sources
PubMed1991

Response of (n-3) and (n-6) fatty acids in piglet brain, liver and plasma to increasing, but low, fish oil supplementation of formula.

Addition of fish oils to infant formula provides (n-3) long-chain polyenoic fatty acids (LCP), specifically 22:6(n-3), to infants fed formula rather than human milk. Most fish oils, however, contain high levels of 20:5(n-3) and low (n-6) LCP. These studies determined the brain total, synaptic plasma membrane phosphatidylethanolamine and phosphatidylcholine, and plasma and liver phospholipid fatty acids of piglets fed from birth to 15 d with formula containing (percent fatty acids) 34% 18:2(n-6), 0.8% 18:3(n-3) and 0, 2 or 6 g/L menhaden oil, or sow milk. The brain 22:6(n-3) was higher and 22:4(n-6) lower in piglets fed 6 g/L menhaden oil compared with sow milk. Brain levels of 20:5(n-3) did not increase, or levels of 20:4(n-6) decrease, with increasing dietary (n-3) LCP. A diet concentration-dependent increase in 20:5(n-3) and decrease in 20:4(n-6) (P less than 0.0001) in liver phospholipid showed no evidence of maximum saturation or depletion, respectively, over the range of (n-3) LCP intake studied. The fish oil supplementation was effective in supplying 22:6(n-3) to the developing brain. The accompanying increase in 20:5(n-3) and decrease in 20:4(n-6), important eicosanoid precursors, in plasma and liver phospholipid show the need for caution in the use of fish oils low in (n-6) LCP as a source of (n-3) LCP for infant formula.

Animals↗
PubMed1990

Effect of a vegetable oil formula rich in linoleic acid on tissue fatty acid accretion in the brain, liver, plasma, and erythrocytes of infant piglets.

The effect of feeding sow-milk formula (SMF) or a vegetable-oil infant formula (FF) with minimal n-6 and n-3 long-chain polyenoic fatty acids (LCPs) but high linoleic acid (18:2n-6) and a high ratio of 18:2n-6 to linolenic acid (18:3n-3) on the fatty acids of brain lipid and liver, plasma, and red cell phospholipids was studied in piglets fed from birth for 5, 10, 15, or 25 d. Compared with SMF, FF reduced the concentrations of 18:1 and n-3 LCPs, especially 22:6n-3, in all tissues and increased 22:4n-6 in brain, liver, plasma, and red cell phosphatidylethanolamine. FF also increased 22:5n-6 in brain lipid, liver, and plasma but not in red cell phospholipids. Thus, changes in tissues capable of in situ desaturation were not completely reflected in the red cell phospholipids. The increased liver and brain n-6 LCP accretion in the FF piglets may suggest competent desaturation and possible inhibition of n-3 desaturation and/or acylation by dietary n-6 fatty acids.

Animals↗
PubMed1990

Brain synaptosomal, liver, plasma, and red blood cell lipids in piglets fed exclusively on a vegetable-oil-containing formula with and without fish-oil supplements.

Clinical studies showed that a decrease in red blood cell 22:6n-3 caused by feeding infants formula (F) can be prevented by supplementation with fish oil (F + O). It is not known whether fish-oil supplementation is able to support normal accretion of fatty acids with greater than or equal to 20 carbons (LCPs) in the brain. Therefore piglets were fed exclusively F + O, F, or sow milk (SM) for 15 d and their liver and brain synaptosomal fatty acids were determined. Feeding F + O corrected the low n-3 LCP in the liver phospholipid (PL) and synaptosomal phosphatidylethanolamine (PE) of piglets fed F compared with SM. An apparent compensatory increase in n-6 LCPs in liver PL and synaptosomal PE of piglets fed F compared with SM was suppressed by feeding F + O. F + O also reduced the ratio of plasma PL 20:4n-6 to 20:5n-3, important for eicosanoid metabolism. Supplementation of F with n-3 LCPs as fish oil, without n-6 LCPs, at levels giving normal brain n-3 LCP, may alter n-6 LCP accretion.

Animals↗
PubMed1990

Comparison of breast-feeding and formula feeding on intestinal and hepatic cholesterol metabolism in neonatal pigs.

Infant formulas (IFs) contain reduced cholesterol concentrations compared with breast milk (SM); how neonatal cholesterol metabolism responds to this difference is largely unknown. The effect of exclusive feeding of SM vs low-cholesterol IF on intestinal and hepatic cholesterol concentrations and synthesis during early postnatal development were compared in piglets. Animals were killed at birth or on days 5, 10, 15, or 25 postpartum. Plasma cholesterol concentrations were higher in SM-fed than in IF-fed piglets on days 15 and 25. In intestine both HMG-CoA reductase activity and 3H2O incorporation rates into cholesterol were similar for both groups or reduced in the IF-fed group at days 15 and 25. In liver, HMG-CoA reductase activity was higher in IF-fed than in SM-fed piglets on days 5, 10, and 15. Results indicate that during the early postpartum period, response to lower cholesterol intakes with IF occurs by increasing hepatic sterol synthesis whereas intestinal synthesis is largely unaffected.

Animals↗
PubMed1989

Menstrual cycle effects on the metabolism of tryptophan loads.

The metabolism of tryptophan (Trp) was examined during the follicular and luteal phases of the human menstrual cycle. Eight healthy women were administered capsulated Trp (3 g) or placebo (3 g lactose) during two follicular and two luteal phases of their menstrual cycles. Trp loading resulted in increased plasma concentrations of Trp and kynurenine, in an increase in the ratio of Trp to neutral amino acids in plasma, and in an increase in urinary excretion of Trp and kynurenine at both phases of the menstrual cycle. However at 3 h after Trp ingestion, plasma kynurenine levels in the luteal phase (23.6 +/- 3.1 mumol/L) were 40% higher than in the follicular phase (16.7 +/- 1.1 mumol/L) (p less than 0.05). Urinary kynurenine excretion in the luteal phase (81.6 +/- 14.4 mumol/24 h) was 28% greater than in the follicular phase (63.9 +/- 13.0 mumol/24 h) (p less than 0.05). The results indicate that the catabolism of Trp via the kynurenine pathway is affected by the phase of the human menstrual cycle.

Adult↗
PubMed1989

Effect of linoleic acid-rich infant formula feeding on brain synaptosomal lipid accretion and enzyme thermotropic behavior in the piglet.

The effects of a vegetable oil-based infant formula, virtually devoid of n-6 and n-3 long chain polyenoid fatty acids (LCP) and high in 18:2(n-6) and 18:2(n-6)/18:3(n-3) ratio, on brain synaptosome lipid composition and enzyme thermotropic behavior were studied in neonatal piglets. Term gestation piglets were fed either sow milk (SMF) or formula (FF) from birth for 5, 10, 15, or 25 days. Synaptosomal cholesterol, total lipid phosphorus, and phospholipid class composition did not differ between SMF and FF piglets. Synaptosomal fatty acid composition, however, was influenced by diet. The proportion of n-3 LCP, especially 22:6(n-3), was decreased, while the n-6 LCP, especially 22:4(n-6) and 22:5(n-6), were increased in FF compared to SMF piglets. These diet-related changes were most pronounced in the ethanolamine glycerophospholipid fraction and increased with the duration of feeding. FF thus reversed an apparent developmental increase in the synaptosomal n-3/n-6 LCP ratio. The monoene content, especially 18:1, was also reduced in the synaptosomes of FF compared to SMF pigs. FF had no effect on the activity of synaptosomal acetylcholinesterase. However, higher transition temperatures for this enzyme, indicating decreased membrane fluidity, were found in the FF compared to SMF piglets. The data suggest that exclusive feeding of proprietary formulae, devoid of LCP and high in 18:2(n-6) and/or the 18:2 (n-6)/18:3(n-3) ratio, may compromise normal fatty acid accretion and physical properties of brain synaptosomal membranes.

Acetylcholinesterase↗
PubMed1988

Nonlinear estimation of parameters in biphasic Arrhenius plots.

This paper presents a formal procedure for the statistical analysis of data on the thermotropic behavior of membrane-bound enzymes generated using the Arrhenius equation and compares the analysis to several alternatives. Data is modeled by a bent hyperbola. Nonlinear regression is used to obtain estimates and standard errors of the intersection of line segments, defined as the transition temperature, and slopes, defined as energies of activation of the enzyme reaction. The methodology allows formal tests of the adequacy of a biphasic model rather than either a single straight line or a curvilinear model. Examples on data concerning the thermotropic behavior of pig brain synaptosomal acetylcholinesterase are given. The data support the biphasic temperature dependence of this enzyme. The methodology represents a formal procedure for statistical validation of any biphasic data and allows for calculation of all line parameters with estimates of precision.

Acetylcholinesterase↗
PubMed1984

Acculturation to Canadian Foods by Chinese immigrant boys: changes in the perceived flavor, health value and prestige of foods.

Acculturation changes in the perceived qualities of foods was demonstrated in a group of first and second generation Chinese adolescent immigrants. The type and degree of change in perceived flavor, health value and prestige ratings varied for individual foods. The second generation subjects and those with more accultured patterns of language use, gave higher hedonic flavor and prestige ratings to dessert, snack and fast foods. This same group exhibited better discrimination between nutrient rich and poor foods as assessed by changes in perception of health value. Food perceptions of the more accultured second generation Chinese group were also found to approach those of an age and sex matched group of Canadian Anglophones. The results suggest that on immigration diet westernization may have nutritionally undesirable effects.

Acculturation↗