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Biomedical subjects

D L Burney

Publications and source records attributed to D L Burney.

6 recordsLinked to original sources
PubMed2000

Both ischemic and pharmacological preconditioning decrease hepatic leukocyte/endothelial cell interactions.

BACKGROUND: Ischemic preconditioning has been shown to protect some tissues from ischemia/reperfusion (I/R) injury. Adenosine is believed to play an important role by attenuating leukocyte-endothelial cell adhesive interactions. Dipyridamole increases adenosine bioavailability. The purpose of this study was to evaluate the effects of mechanical (MPC) and pharmacological preconditioning (PPC) on leukocyte endothelial cell interaction in hepatic I/R injury. METHODS: C57BL6 mice were subjected to 30 min of ischemia to the left lobe of the liver. Groups tested at 30 min, 2, 5, 12, and 24 hr of reperfusion had 1) sham laparotomy (n = 10, 2) I/R (n = 25), 3) ischemic preconditioning with 5 min of ischemia and 10 min reperfusion before I/R (n = 25), and 4) (PPC) with dipyridamole (n = 25). Intravital microscopic examination was used to assess leukocyte/endothelial cell adhesion. Blood was drawn for leukocyte counts and liver function tests. RESULTS: A significant decrease in leukocyte rolling was observed at 30-min and 5-hr reperfusion intervals in the PPC and ischemic preconditioning groups compared with the I/R group. A significant decrease in leukocyte saltation was also observed in the PPC and MPC groups at 2, 5, and 12 hr of reperfusion when compared with the I/R group. aspartate aminotransferase was significantly decreased in the 5-hr preconditioning groups. There was not a significant decrease in the white blood cell count because of PPC or MPC vs. I/R CONCLUSIONS: Preconditioning decreases endothelial/ leukocyte interaction and reduces liver damage as measured by aspartate aminotransferase. These data prove that IPC and PPC provide some degree of hepatic protection in I/R injury.

Animals↗
PubMed1996

Intestinal oxygenation and mucosal permeability with luminal mother's milk in developing piglets.

We have previously observed a developmental difference in mucosal permeability (i.e. the younger the animal, the greater the increase in permeability) after exposure to luminal nutrients derived from cow's milk-based infant formulas. There has been tremendous speculation and some clinical evidence that mother's milk may be protective against mucosal injury in developing intestine. In this study, we hypothesized that instillation of sow's milk into the intestinal lumen of developing piglets would cause no differences in either intestinal metabolic demand (oxygen uptake) or mucosal permeability among age groups. Intestinal blood flow (total and fractionated), arteriovenous oxygen content difference, venous pressure, and capillary pressure were measured, and vascular resistance and oxygen uptake were calculated, after 30 min of intraluminal instillation of predigested and solubilized sow's milk in 1-d-old, 3-d-old, 2-wk-old, and 1-mo-old piglet jejunoileum. In a separate group of animals, plasma-to-lumen clearance of chromium-51 EDTA was evaluated during luminal perfusion with digested and solubilized sow's milk in 1-d-old, 3-d-old, and 1-mo-old piglet jejunoileum. Intestinal oxygen uptake was similar among age groups of developing piglets, but EDTA clearance was significantly higher for intestinal segments perfused with sow's milk in 1-d-old, compared with older, animals. Thus, luminal perfusion with predigested and bile acid-solubilized sow's milk in 1-d-old piglet jejunoileum, compared with perfusion in older piglets, causes increased mucosal permeability in 1-d-old intestine, but this increased permeability is not due to increased intestinal oxygen uptake (i.e. increased metabolic demand).

Animals↗
PubMed1994

An animal model of necrotizing enterocolitis induced by infant formula and ischemia in developing piglets.

BACKGROUND/AIMS: The lipid component of piglet formula (0.5% fat) causes increased mucosal permeability in 1-day-old piglets after ischemia/reperfusion. The present study examined if luminal exposure to infant formulas (3.5% fat) and ischemia/reperfusion result in an animal model of necrotizing enterocolitis and if injury is dependent on the formula fat composition. METHODS: Plasma-to-lumen clearance of 51Cr-ethylenediamine-tetraacetic acid was measured, and morphology was evaluated during luminal perfusion with preterm, term, and delipidated preterm cow milk-based infant formulas before and after ischemia/reperfusion in 1-day-old and 1-month-old piglet jejunoileum. In a separate set of experiments, a 1-2-cm segment of ileum was exteriorized and opened to expose the mucosal surface, and the villi were superfused with the above formulas (no ischemia). RESULTS: Before ischemia, clearances were markedly higher for intestinal loops perfused with preterm formula than for loops perfused with term and delipidated formulas in 1-day-old animals. After ischemia, clearances in loops perfused with preterm formula were significantly greater and grossly hemorrhagic and histologically necrotic compared with loops perfused with delipidated formula (minimal injury). Superfusion with preterm formula caused diffuse hyperemia and hemorrhage into intestinal villi. CONCLUSIONS: Luminal perfusion of 1-day-old piglet jejunoileum with predigested and bile acid-solubilized preterm infant formula, in combination with ischemia/reperfusion, produces an animal model of necrotizing enterocolitis, but only if the lipid fraction of the formula is present.

Animal Feed↗
PubMed1992

Influence of luminal nutrient composition on hemodynamics and oxygenation in developing intestine.

Age-related differences in the intestinal hemodynamic and oxygenation responses to carbohydrate, protein, and lipid were studied in 1-day-, 3-day-, 2-wk-, and 1-mo-old piglets. A branch of the mesenteric vein draining an isolated loop of jejunoileum was used to measure intestinal blood flow, arteriovenous oxygen content difference, and venous and capillary pressure and to calculate oxygen uptake and vascular resistance. Fractionated intestinal flow was measured with radiolabeled microspheres. Measurements were made before and after luminal placement of either 5% glucose, 2.3% casec, or 5% corn oil. In 1-day-old animals, unlike all older age groups, total intestinal blood flow and vascular resistance were unchanged by any nutrient. Fractionated flow to the mucosa/submucosa levels did, however, increase in the intestine of 1-day-old piglets to a similar extent as that in older age groups. Placement of lipid or protein into the lumen led to increased oxygen uptake in all age groups, whereas carbohydrate absorption resulted in no increase in intestinal oxygen consumption in 1- and 3-day-old animals. In 1-day-olds, the increased oxygen consumption was achieved by enhanced oxygen extraction with no change in total blood flow, whereas all other groups demonstrated increases in blood flow and/or oxygen extraction. Compared with a mixed meal, oxygen consumption was not significantly greater for an individual nutrient component.

Aging↗
PubMed1991

Postprandial hemodynamics and oxygenation in developing piglet intestine.

Age-related differences in the intestinal hemodynamic and oxygenation responses to feeding were studied in 1-day- (never-nursed and nursed-fasted), 3-day-, 2-wk-, and 1-mo-old piglets. A distal branch of the superior mesenteric vein draining an isolated loop of jejunoileum was used to measure intestinal blood flow, arteriovenous oxygen content difference, venous pressure, and capillary pressure. Calculations of oxygen uptake and vascular resistance were performed from the measured variables. Radioactive microspheres were used to measure fractionated flow. After luminal instillation of a cow milk-based formula, postprandial oxygen uptake increased to a similar extent in all age groups. In never-nursed newborns the increase was achieved by a dramatic rise in oxygen extraction with no change in total flow, while all other groups demonstrated a combined increase in blood flow and oxygen extraction. Mucosal blood flow increased to a similar extent in all age groups, but in never-nursed newborns it was at the expense of muscularis-serosa flow. Thus, because oxygen extraction and mucosal blood flow appear to be near maximal during feeding alone, newborn intestine may be at risk for tissue hypoxia and subsequent mucosal injury in the presence of a superimposed cardiovascular stress.

Aging↗