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Biomedical subjects

L Traber

Publications and source records attributed to L Traber.

At least 19 recordsLinked to original sources
PubMed2000

Both dermal matrix and epidermis contribute to an inhibition of wound contraction.

Contracture is a major detriment to functional recovery from large wounds. To determine the relative value of dermal replacement and epidermal coverage in inhibiting wound contraction, five full-thickness wounds (all 5 x 5 cm2) were placed on the back of 8 swine and treated in the following manner: (1) open wound, (2) porcine acellular dermis (analogous to AlloDerm for human use), (3) porcine acellular dermis with epidermal autograft placed 7 days postwounding, (4) porcine acellular dermis with immediate epidermal autograft, and (5) conventional-thickness autograft. Scar dimensions and punch biopsies were taken at days 14 and 30 postwounding. The planimetry results demonstrated that wound contraction was significantly greater with the open wounds (group 1) than all other wounds with a dermal substitute. Furthermore, wounds with initial epidermal coverage had significantly less contraction than unepithelialized wounds (14.8 +/- 1.1 cm2 at day 14 in wound group 2 vs. 20.4 +/- 0.6 cm2 in wound group 4; p < 0.05). Biopsy results revealed that wounds with initial epithelial coverage had the least amount of inflammation. These findings suggest that both dermal matrix and epidermal coverage contribute to an inhibition of wound contraction and that prompt epithelial coverage appears to impede contraction by reducing inflammation.

Animals↗
PubMed1998

Urinary glycosylated, free and total pyridinoline and free and total deoxypyridinoline in diabetes mellitus.

OBJECTIVE: Published data on bone metabolism in diabetes mellitus are conflicting. We have measured pyridinium crosslinks, biochemical markers of bone resorption, in order to evaluate bone resorption in diabetes mellitus. We also wished to investigate whether, as a consequence of chronic hyperglycaemia, pyridinoline is glycosylated to a greater extent in patients with diabetes mellitus. DESIGN AND PATIENTS: This cross sectional study included 142 patients (64 males, 78 females) with insulin dependent and non-insulin dependent diabetes mellitus (IDDM and NIDDM). These patients were compared to a healthy control group of 99 individuals (39 males and 60 females). MEASUREMENTS: Pyridinium crosslinks, glycosylated, free and total pyridinoline (gPYD, fPYD, tPYD) and free and total deoxypridinoline (fDPD, tDPD) were measured in a spot urine sample by high performance liquid chromatography (HPLC). Urinary creatinine, albumin and glucose were also measured. RESULTS: In the diabetic group, values of urinary gPYD and tDYD were significantly lower than in controls. gPYD excretion was lowest in patients with severe glycosuria. Free pyridinium crosslinks, both fPYD and fDPD, were excreted to a significantly lower extent. The molar ratio of tPYD to tDPD was significantly increased in diabetes mellitus. CONCLUSIONS: Decreased excretion of tDPD suggests low bone resorption in IDDM and NIDDM. Pyridinoline is not glycosylated to a greater extent in diabetes mellitus and tends to be decreased in proportion to the degree of glycosuria. Excretion of gPYD, fPYD and fDPD is depressed in severe glycosuria. Diminshed degradation to the final products, fPYD and fDPD, might represent increased resistance to enzymatic activity or diminished enzymatic activity. The increased molar ratio tPYD/tDPD in urine suggests an increased ratio in bone collagen in diabetes mellitus.

Adolescent↗
PubMed1996

Differential effects of prolonged septicemia on isolated pulmonary arteries and veins from sheep.

Isolated third-order pulmonary arteries and veins from sheep were examined for the effects of septicemia on norepinephrine-induced contractions, nitric oxide (NO)-mediated dilation, and basal cyclic GMP levels. The groups studied were as follows: control sheep (n = 7); sheep given live Pseudomonas aeruginosa (Ps, n = 6) for 48 h; and sheep given NG-mono-methyl-L-arginine during the last 24 h of Ps infusion (Ps-L-NMMA, n = 4). The norepinephrine-induced contractions were significantly greater (p < .05) in arteries from septic (Ps and Ps-L-NMMA) sheep. Basal cyclic GMP levels were similar in all of the arteries. The norepinephrine-induced contractions were significantly depressed (p < .05) in veins from septic (Ps and Ps-L-NMMA) sheep. Basal cyclic GMP levels in veins from Ps sheep were markedly elevated (p < .01). N omega-nitro-L-arginine methyl ester (L-NAME) ex vivo decreased cyclic GMP in both arteries and veins. Removal of endothelium enhanced contractions and decreased cyclic GMP in arteries and veins only from control sheep. The results show that septicemia differently affects the pulmonary artery and vein. The enhanced vasoconstriction of the artery is due to decreased endothelium-dependent NO release; the attenuated vasoconstriction of the vein is associated with NO-mediated increased cyclic GMP levels.

ADP Ribose Transferases↗
PubMed1993

Does positive end-expiratory pressure significantly reduce airway blood flow?

Nutritive (systemic arterial) airway blood flow (mL/min/100 grams tissue) was studied in various size airways at four randomized levels of positive end expiratory pressure (PEEP) in smoke injured and normal lungs. Seven sheep were studied 24 hours after an isolated injury to the left lung using cotton smoke. Radioactive 15-microns microspheres were utilized to measure this airway blood flow. These data demonstrated a marked increase in systemic arterial blood flow to the airways in the injured left lung. Increasing levels of PEEP significantly reduced this hyperemic response. PEEP did not significantly affect the uninjured right lung. Systemic airway blood flow was never reduced to below normal control levels (uninjured) in either lung despite PEEP of up to 20 cm H2O. Severe reduction in airway nutritive flow, and the possibility of airway necrosis, does not appear to occur at PEEP levels of up to 20 cm H2O.

Animals↗
PubMed1992

Comparison of the pulmonary lymphatic and hemodynamic changes of near-drowning in a sheep model.

The hemodynamic and lung lymph changes following near-drowning (ND) were studied in sheep. Experimental ND was by transtracheal aspiration of 10 ml/kg body weight of either seawater (SW) or freshwater (FW). Extravascular lung water and lung lymph protein flux were significantly increased, but cardiac index was depressed in both groups following ND. Systemic and pulmonary vascular resistances were markedly elevated with FW compared to only a slight rise with SW. Lung lymph oncotic pressure decreased with SW ND from baseline of 9.7 +/- 0.4 to 6.8 +/- 0.63 mm Hg (P < 0.05). In contrast, FW ND increased lung lymph oncotic pressure from 12.8 +/- 0.9 to 16.6 +/- 1.3 mm Hg (P < 0.05). These data suggest that the changes in lung lymph and hemodynamic response to SW and FW ND differ in sheep. The changes are immediate and profound with SW, but slower in onset and less severe with FW. FW ND is associated with hemolysis, which is absent in SW ND.

Animals↗
PubMed1992

Bronchial blood flow during changes in inhaled oxygen and carbon dioxide concentrations in conscious sheep.

Bronchial artery blood flow index (BFI) was measured in an unanesthetized sheep model using a chronically implanted ultrasonic flow probe. The bronchial circulation was monitored during changes of the concentrations of oxygen and carbon dioxide in inhaled air. Control BFI was 15.9 +/- 3.8 ml/min/m2 during normoxic breathing with 0% CO2 (n = 6) and 18.0 +/- 1.6 ml/min/m2 while breathing 28% O2 and 0% carbon dioxide (n = 6). Hypoxia (FIO2 = 0.10) significantly increased BFI to 25.8 +/- 4.9 ml/min/m2 with a decrease in the bronchovascular resistance index (BVRI) from a baseline of 7.85 +/- 1.73 to 4.75 +/- 0.86 mm Hg/(ml/min)/m2. Hyperoxia (FIO2 = 1.0) raised BFI to 30.5 +/- 10.1 ml/min/m2 without a significant decrease in BVRI. Changing the inhaled carbon dioxide concentration from 0 to 10% resulted in a significant increase in BFI from 18.0 +/- 1.6 to 43.6 +/- 10.3 ml/min/m2 and a decrease in BVRI from 5.56 +/- 0.44 to 4.63 +/- 2.18 mmHg/(ml/min)/m2 (not significant). The change in BFI varies directly with lymph flow for hypoxia and hypercarbia. This is consistent with changes in cardiac index, indicating probable changes in surface area being perfused in the lung. Changes in BFI with hyperoxia did not follow changes in systemic vascular resistance or cardiac index. Similarly, lymph flow elevation did not occur during hyperoxia. These data suggest that BFI changes with hyperoxia are not related to changes in total systemic vascular resistance, or cardiac index, and a different mechanism may control bronchovascular flow for this condition.

Animals↗
PubMed1991

Endotoxin-induced alterations in contractility of isolated blood vessels from sheep.

The present study examined reactivity to norepinephrine (NE) and KCl in isolated, suffused blood vessels from the systemic and pulmonary circulations of endotoxin-treated and control sheep. A possible mechanism underlying an endotoxin-induced alteration in vascular reactivity was also investigated. Chronically instrumented sheep were given Escherichia coli endotoxin (1.5 micrograms/kg). Eight to 12 h later these endotoxin-treated animals exhibited a significantly increased cardiac output and decreased systemic vascular pressure and resistance. The pulmonary vascular pressure and resistance were not changed. The isolated superficial femoral artery from the endotoxin sheep exhibited depressed contractions in response to KCl (75 mM) and to NE (10(-7)-10(-5) M), whereas the pulmonary artery (tertiary branch) did not exhibit altered reactivity. The decreased sensitivity to NE in the femoral artery from endotoxin sheep did not appear to involve an alteration of alpha- or beta-adrenoceptors, or an increased release of vasodilator prostanoids, or endothelium-derived relaxing factor.

Animals↗
PubMed1990

Hydroxyethyl starch pretreatment in bacteremic sheep.

Live bacteria were infused in a chronic ovine lung lymph model to determine if a preceding infusion of the colloid, hydroxyethyl starch (HES), exaggerated the cardiopulmonary dysfunction or impaired removal of bacteria by macrophages in the pulmonary circulation. HES was infused (3 mL/kg/hr; n = 6) from 24 to 12 hr before the bacteria and decreased plasma protein content and increased pulmonary lymph to plasma protein concentration because of its oncotic properties. Ringer's lactate (2 mL/kg/hr) was given after stopping HES and also to the control group (n = 6). Infusion of live Ps. aeruginosa (2.5 x 10(8) Ps./min for approximately 30 min) induced equivalent pulmonary hypertension, increased pulmonary microvascular permeability, and cardiovascular depression in the two groups. The removal of bacteria in the lungs was not affected, indicating that this measurement of the function of the mononuclear phagocytic system was not impaired by the preceding HES.

Animals↗
PubMed1990

Bronchial blood flow and eicosanoid blockade following airway acid aspiration.

The systemic circulation to the lung is thought to be an important microvascular exchange region which may contribute to pulmonary edema resulting from airway injury. In a chronic sheep model, we have evaluated the flow through the bronchial artery after airway injury caused by the aspiration of 2.5 ml/kg of 0.1 N hydrochloric acid with and without inhibition of thromboxane synthetase and cyclooxygenase. Cyclooxygenase inhibition with ibuprofen resulted in no rise in bronchial artery blood flow associated with airway acid aspiration (9.8 +/- 1.72 ml/min to 63.7 +/- 8.9 ml/min in the control group versus 11.3 +/- 2.5 ml/min to 10.3 +/- 3.4 ml/min in the ibuprofen group). No difference in bronchial artery blood flow was noted between control acid aspiration and acid aspiration with thromboxane synthetase inhibition. Significant early reduction in lung lymph flow was noted in the cyclooxygenase inhibition group compared to control. These data suggest that inhibition of the cyclooxygenase pathway of eicosanoid production may lessen the injury caused by airway acid aspiration. The decrease in airway blood flow with associated reduction in lymph flow suggests that airway blood flow may be important in the generation of pulmonary edema in this model.

Animals↗
PubMed1990

Airway aspiration of hydrochloric acid in sheep.

We have compared the effects of aspiration of 2.5 ml/kg of 0.1 N hydrochloric acid (HCl) on groups undergoing normal saline aspiration (2.5 ml/kg) and a sham control in unanesthetized sheep with chronic lung lymph fistula for up to 148 hr. Significant changes in pulmonary lymph flow and cardiopulmonary variables occurred in the airway acid group within the first 48 hr, as compared to saline and sham control. In the HCl group lymph flow increased from a baseline of 8.5 +/- 1.5 to 21.8 +/- 3.0 ml/hr (mean +/- SEM) at 2 hr. Pulmonary vasoconstriction occurred at this time with significant elevations of lymph thromboxane B2 from a baseline of 400 +/- 11 to 2,090 +/- 690 pg/ml. During the early acid aspiration phase products of lipid peroxidation were noted to increase from 0.29 +/- 0.03 to 0.81 +/- 0.17 absorbance units. Associated with elevated lymph flow was a significant drop in cardiac index in the airway-acid-aspirated group (6.59 +/- 0.52 to 5.53 +/- 0.36 L/min/m2) and a rise in bronchial blood flow from 9.8 +/- 1.7 to 63.7 +/- 8.9 ml/min. These data suggest that a moderate airway acid injury created by 2.5 ml/kg of HCl results in acute pulmonary damage with the release of several potential mediators which may be responsible for the observed effects. The long-term acid-injured animals survived for up to 1 week following the aspiration procedure with evidence of resolution of lung damage by wet-weight dry-weight evaluation of lung (normal lab control = 4.0 +/- 0.2, and 148 hr after acid = 4.5 +/- 0.3) and microscopic evidence of minimal persistent injury. These data document the pulmonary damage and repair resulting from airway acid instillation.

Animals↗
PubMed1988

Beta endorphin, a vasoconstrictor during septic shock.

UNLABELLED: A relationship between increased peripheral resistance (TPRI) and decreased cardiac index (CI) and mortality from sepsis has been suggested. The relationship between endogenous opiates and this response was evaluated. METHODS: Chronically instrumented sheep were given E. coli endotoxin (LPS, 1.5 mcg/kg x 30 minutes). In one study, survivors (n = 9) and nonsurvivors (n = 11) of LPS were compared along with survivors (n = 8) of half the dose of LPS. In a second study, two groups of animals received naloxone: one (n = 11) had a bolus of 2 mg/kg followed by a 2 mg/kg/hr continuous infusion started 30 minutes before LPS while the other had the bolus and infusion started 1 hour after LPS was begun. RESULTS: Both vasoconstrictive and vasodilative phases were seen. Vasoconstriction was associated with elevated beta endorphin levels, a pattern sustained until death in the nonsurvivors. Both pre- and posttreatment with naloxone lessened the maximum increase in total peripheral resistance index compared with untreated sheep. DISCUSSION: The vasoconstrictive aspects of the response to LPS correlated with elevated beta endorphin levels and with mortality. This vascular response is attenuated with naloxone blockade.

Animals↗
PubMed1988

Myocardial depression in hyperdynamic endotoxemia.

The presence of myocardial depression is difficult to assess in most animal models of septic shock caused by hypovolemia. We studied endotoxemia in fluid-resuscitated conscious sheep. They underwent chronic instrumentation with pulmonary artery, arterial, and left atrial catheters. After 1 week of recovery, 1.5 micrograms/kg of endotoxin (LPS) was administered intravenously over a period of 30 min. One group of nine sheep stayed on baseline fluids (2 ml/kg/h of Ringer's lactate), while a second group (n = 6) was resuscitated with 7 ml/kg/h Ringer's lactate solution over the 24-h study period. Both groups were compared with controls. Eight hours after LPS, left ventricular stroke work index was depressed in both groups. In the group resuscitated with 7 ml/kg Ringer's lactate this depression associated with a normal left atrial pressure and a constant peripheral resistance indicated a shift in the Starling work curve downward and to the right evidencing myocardial depression.

Animals↗
PubMed1988

Cardiopulmonary changes with intermittent endotoxin administration in sheep.

Chronic sepsis was induced by administering endotoxin (lipopolysaccharide--LPS) at 12-hr intervals to sheep. The animals (n = 7) responded to the first dose of LPS with increased pulmonary arterial pressure (PAP), systemic vascular resistance, plasma and lymph thromboxane B2 (TxB2) concentrations, and lung lymph flow rate concurrent with a reduction in the cardiac index (CI). Subsequent doses of LPS produced an elevation of PAP and TxB2 which was progressively attenuated and eventually disappeared. With LPS the lung lymph flow was markedly elevated and CI increased. This latter was transient and associated with a reduction in systemic vascular resistance. Concomitant with the cardiopulmonary changes prekallikrein levels were not diminished, but there was a statistically significant reduction in C1-esterase inhibitor. The administration of LPS was discontinued after 5 days and the cardiopulmonary variables rapidly returned to baseline levels. Chronic endotoxemia appears to be associated with an elevated pulmonary microvascular permeability and a tendency toward a hyperdynamic circulation but with an appreciable degree of refractoriness associated with regional hemodynamics and eicosanoid biosynthesis.

Animals↗