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Biomedical subjects

A D Mason

Publications and source records attributed to A D Mason.

At least 127 records · Page 7Linked to original sources
PubMed1980

Subeschar antibiotic infusion in the treatment of burn wound infection.

In a reproducible infected rat burn model, subeschar infusion of antibiotics failed to protect the animals from death via burn wound invasion excepting those animals receiving carbenicillin. Subcutaneous injection of maximal doses of carbenicillin at a distance from the burn wound protected these animals equally well. Some advantage was defined for the subeschar route of administration with suboptimal doses of carbenicillin. More important is the fact that propective selection of an effective antibiotic could not be made on the basis of in vitro antibiotic sensitivity tests.

Animals↗
PubMed1979

Evaluation of Pseudomonas aeruginosa toxin A in experimental rat burn wound sepsis.

The search for methods to achieve control of Pseudomonas aeruginosa infection continues with the introduction of aluminum-absorbed toxoid developed from P. aeruginosa exotoxin. This toxoid induces significant titers of neutralizing and precipitating antibodies for toxin A when given with appropriate adjuvants. These experiments show that immunization with aluminum phosphate-absorbed toxoid failed to protect burned rats infected with P. aeruginosa. These and previous experiments show that active immunization with live P. aeruginosa provides good strain-specific protection in the same model. No cross-protection was demonstrated between strains of P. aeruginosa in these experiments.

Animals↗
PubMed1978

Abnormalities of phenylalanine and tyrosine kinetics. Significance in septic and nonseptic burned patients.

The flow of phenylalanine, the essential amino acid precursor of thyroid hormone and catecholamines, was severely elevated in five septic burned patients (6.70 +/- 1.07 mg/kg) and six nonseptic burned patients (5.00 +/- 0.44 mg/kg) when compared with seven normal controls (2.10 +/- 0.33 mg/kg). Fasting serum concentrations of phenylalanine were elevated in the septic burned patients (2.33 +/- 0.37 mg/100 ml of serum) relative to the nonseptic patients (1.28 +/- 0.21 mg/100 ml) and the controls (1.01 +/- 0.15 mg/100 ml). The rate of appearance of the phenylalanine metabolite, tyrosine, after an oral phenylalanine dose was normal in all burn patients. Increased serum concentrations and increased flow of phenylalanine are an index of rapid protein catabolism, further augmented by sepsis in the thermally injured, and not a reflection of decreased hepatic conversion of phenylalanine to tyrosine.

Adult↗
PubMed1978

Muscle blood flow following thermal injury.

Peripheral circulation is markedly increased during the hyperdynamic-hypermetabolic phase of thermal injury and appears to be directed primarily to the burn wound. To determine whether any portion of this extra blood flow reaches another major peripheral vascular bed, blood flow in the tibialis anterior muscle of the lower leg was measured by 133Xe clearance in ten hemodynamically stable, nonseptic burn patients (mean burn size = 42.5% total body surface) and five control subjects. Muscle blood flow was 3.52 +/- 0.26 ml/100 g.min (mean +/- S.E.M.) in these patients and 3.29 +/- 0.24 in controls, indicating that resting muscle perfusion was unaffected by the extent of total body surface injury, size of leg burn, or elevated rectal temperature (38.2 +/- 0.2 degrees C) of the patients. These results confirm the interpretations of previous studies suggesting that most of the increased peripheral blood flow following thermal injury is directed to the surface wound. Local and systemic factors responsible for the maintenance of muscle perfusion in the face of alterations in muscle metabolism following thermal injury are discussed.

Adolescent↗
PubMed1977

Effect of carbohydrate and fat intake on nitrogen excretion during total intravenous feeding.

Recent availability of intravenous soy bean oil emulsion for clinical trials in the United States prompted infusion of intravenous diets containing a constant nitrogen level (11.7 grams/m2/day) and 13 different combinations of carbohydrate (110-2300 kcal/m2/day) and fat (0-1100 kcal/m2/day) during 34 three-day studies in 5 patients who were clinically stable after injury or operation. Urea nitrogen excretion was inversely related to carbohydrate intake (P less than 0.01) and directly related to resting metabolic rate (P less than 0.01). Fat infusion did not affect nitrogen excretion at any level of carbohydrate intake. This study suggests that, when a primary clinical goal is nitrogen conservation, carbohydrate calories should be given in amounts approximating the resting metabolic rate. Additional calories and essential fatty acids now can be safely given as intravenous fat emulsion, but fat did not affect nitrogen conservation under the conditions of this study.

Adolescent↗
PubMed1977

Influence of the burn wound on local and systemic responses to injury.

Total resting leg blood flow, measured by venous occlusion plethysmography; leg oxygen consumption; substrate turnover; and leg surface temperature were determined in 21 nonseptic burn patients and four normals. The patients studied during the second to third week postinjury sustained total body surface injuries averaging 45% (range 12-86%) and leg injuries of 35% total leg surface (0-82.5%). To integrate the peripheral metabolic and circulatory events with the systemic responses to injury, total body oxygen consumption, cardiac output, rectal and mean skin temperatures were also measured. Leg blood flow and leg surface temperature generally increased with total burn size but did not correlate with cardiac output, total body oxygen consumption, or body temperature. However, leg blood flow was closely related to the extent of the leg burn (r(2) = 0.73). To evaluate the metabolic determinants of the wound blood flow, patients were matched for burn size (40.5% total body surface in one group vs. 42%), resulting in similar systemic responses to injury (cardiac index 7.8 +/- 0.7 L/min m(2) vs. 7.5 +/- 0.8, VO(2) 204 +/- 12 ml/min m(2) vs. 241 +/- 22, rectal temperature 38.5 +/- 0.3 degrees vs. 38.3 +/- 0.3 degrees , NS). One group (n = 7) had extensive leg burns (58% of the leg surface), the other (n = 9) minimal leg injuries (9.5%). Leg oxygen consumption was similar in the two groups (0.24 +/- 0.01 ml/100 ml leg min vs. 0.19 +/- 0.04, NS), although leg blood flow was markedly increased in the injured extremities (8.0 +/- 0.5 ml/100 ml leg min vs. 4.2 +/- 0.4, p < 0.001). Glucose uptake and lactate production were enhanced in the burned extremities (glucose 0.34 +/- 0.08 mg/100 ml leg mmn vs. 0.04 +/- 0.03, p < 0.01, lactate 0.30 +/- 0.08 mg/100 ml leg min vs. 0.06 +/- 0.06, p < 0.05) and related in a general manner with size of the leg burn. Increased peripheral blood flow following injury is directed to the wound and unrelated to aerobic metabolic demands of the extremity. The selectively perfused wound consumes glucose and produces lactate. The increased systemic cardiovascular and metabolic responses to thermal injury are essential for the enhanced circulatory and anaerobic demands of the healing wound.

Adolescent↗
PubMed1977

Influence of the burn wound on peripheral circulation in thermally injured patients.

Simultaneous measurements of resting leg blood flow and surface and rectal temperatures were made in 45 studies of 9 normal subjects and 28 burn patients. The patients had burns from 3-86% of the total body surface with leg injury ranging from 0-87.5% of the leg surface. In the patient group, blood flow was essentially normal in the uninjured legs, increased in a curvilinear manner with the size of the leg burn, and approached a plateau of 8.0 ml/100 ml-min as the percent of leg burn exceeded 60%. Increasing the leg surface temperature by 5 degrees C increased blood flow in patients with burned and unburned extremities to the same extent as in normal subjects. Increased peripheral blood flow following thermal injury is directed primarily to the burn wound. Variations in surface temperature modify this peripheral vascular response to injury.

Adolescent↗
PubMed1976

Platelet aggregation following defibrination with ancrod.

In vitro platelet aggregation was studied in dogs following defibrination with Ancrod. There was marked inhibition of aggregation immediately after defibrination. A gradual return toward normal aggregation was observed over the 96 hours study period, but aggregation was still abnormal at 96 hours after defibrination. There was an inverse and highly significant correlation between aggregation and fibrin degradation product level. Fibrinogen was not measurable after defibrination for the entire study period. Aggregation was thus independent of fibrinogen concentration in this study.

Ancrod↗
PubMed1976

Comparison of coarse mesh gauze with biologic dressings on granulating wounds.

Twenty patients with large area granulating wounds were selected for the study. On each patient, a small area of uniform appearance was divided into four subareas, and each subarea was randomly assigned treatment with a single 24 hour application of cadaver allograft, fresh porcine xenograft, formalinized xenograft, or "wet-to-dry" applications of coarse mesh gauze changed three times daily. At 24 hours, all four areas were uncovered. The subareas were ranked in terms of appearance on a best, second best, third best, and worst scale by experienced paramedical personnel who were not told which area received which treatment. Contact sponge quantitative microbiology was performed on each subarea before and after treatment on seventeen of the twenty patients. The results of these rankings suggest that coarse mesh gauze, changed three times daily, was significantly better at improving wound appearance than any of the biologic dressings. Among the biologic dressings, formalinized xenograft was significantly the worst. There was no significant difference between cadaver allograft and porcine xenograft. Analysis of quantitative cultures was limited by the problems of applying statistical methods to series of paired cultures in which initial values are quite different. Within the framework of such limitations and our 24 hour study, there was not significant change in surface colonization when either coarse mesh gauze or biologic dressings were used.

Adolescent↗