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Biomedical subjects

C R Baxter

Publications and source records attributed to C R Baxter.

At least 55 records · Page 3Linked to original sources
PubMed1983

Catechol-O-methyltransferase activity in erythrocytes of persons with severe thermal injury.

In the present investigation, we found that the catechol-O-methyltransferase activity (COMT) in erythrocytes of persons with severe thermal injury was strikingly increased when compared with that in erythrocytes of noninjured individuals. The specific activity of COMT in erythrocytes of burned patients was not correlated with extent of burn. Thus the echinocytes of burned persons are another example of abnormal red cells in which COMT activity is increased. This appears to be the first example of increased COMT activity in abnormal erythrocytes that is not associated with large numbers of reticulocytes.

Adult↗
PubMed1982

Lipid mobilization and metabolism after thermal trauma.

Lipid mobilization following thermal injury was studied in 25 patients with burns of between 35 and 95% TBSA for 30 to 50 days postinjury. The concentration of free fatty acids and glycerol in the plasma was elevated. The concentration of plasma triglycerides was elevated, while the concentration of ketone bodies remained normal. Thus it is suggested that the free fatty acids are primarily being re-esterified to triglycerides rather than being utilized for ketone body production. During the first 10 days postinjury, the plasma carnitine level was slightly decreased, while the concentration of carnitine in liver and muscle was elevated. The level of carnitine in burn wound fluid was similar to that in plasma. Therefore, the early decrease in plasma carnitine appeared to result from wound losses, as well as the sustained increased uptake by liver and muscle throughout the burn course.

Burns↗
PubMed1982

Cyclosporin A-induced increases in renin storage and release.

The effect of Cyclosporin A (CyA) on renin storage and release in rats was investigated. Renin release from incubated renal cortical slices was increased in rats treated with 25 or 50 mg/kg/day of CyA for 3 to 7 days. This was associated with an increase in renal cortical renin content, which was also increased over the same time period. Plasma renin activity was similarly elevated in these rats. It is possible that these increases in renin are related to the nephrotoxicity of CyA.

Animals↗
PubMed1982

Contractile function of heart muscle from burned guinea pigs.

Atrial muscle isolated from burned guinea pigs was used to assess myocardial contractile changes associated with thermal injury. Muscle was obtained 16-18 hours after the animals were subjected to sham burn (controls) or to scald burn equivalent to 16% of total body surface area. Isometric contractile tension (CT) and its maximal rate of increase (+dT/dt) were not significantly altered by burn. However, the maximal rate of relaxation (-dT/dt) was uniformly less in muscle from the burned group, and this difference was significant at several time intervals after in vitro contractile responses were elicited. Similarly, -dT/dt responses to increased stimulation frequency (0.1-3.0 Hz) and to increased calcium ion concentration (1.0-10.0 mM) were generally less in the burned group, whereas corresponding CT and +dT/dt responses of the burn and controls groups were not significantly different. Present data indicate that atrial muscle removed from moderately burned guinea pigs exhibits normal contractile capabilities, but may be characterized by impaired relaxation properties.

Animals↗
PubMed1981

The pathogenesis of abnormal erythrocyte morphology in burns.

The anemia of thermal injury is characterized by a decreased RBC half-life and abnormal RBC morphology (predominantly echinocytes). These changes are reversible in crossover studies with normal recipients, suggesting an extrinsic mechanism unrelated to initial heat or mechanical damage. Since alterations in plasma lipids, which are freely exchangeable with red cell lipids, produce similar changes, plasma and erythrocyte membrane lipid composition in 30 patients (mean 60% TBSA) was determined and related to RBC morphology in vivo and in vitro. Total cholesterol (TC) and phospholipids (PL) were decreased in plasma and plasma lipoproteins (LP) but remained normal in red blood cell membranes. The deficit in TC and LP cholesterol resulted from decreased cholesterol esters. Plasma phospholipids contained increased phosphatidylcholine (PC) and low lysophosphatidylcholine (LPC) and sphingomyelin levels. The essential fatty acid (EFA) composition of total plasma lipids rapidly decreased, with a more gradual decrease in EFA in red cell lipids. The ratio of free fatty acids to albumin in the plasma was greatly increased throughout and may have a primary role in the abnormal erythrocyte morphology and decreased half-life in burned patients.

Adult↗
PubMed1981

Development of acute burn shock in unresuscitated guinea pigs.

Conscious guinea pigs were used to study the development of burn shock as a function of the size of thermal injury to the body surface. Scale burns equivalent to 0 (control, n = 18), 15.7 +/- 0.8% (n = 11), 24.6 +/- 0.5% (n = 10), and 43.4 +/- 1.5% (n = 10) of total body surface area were obtained by use of a template device, while the animals were deeply anesthetized with methoxyflurane. Circulatory function was assessed without further anesthetic restraint before and at 1, 2, 4, 6, 8, and 24 hr after burn. Values from control guinea pigs varied little during the observation period. Hemodynamic functions of burned guinea pigs were abnormal, and both the magnitude and duration of dysfunction generally depended upon the size of injury. Burn shock was characterized by hemo-concentration, hypothermia, tachycardia (bradycardia in the 43.4% group), minimal adjustments in systemic blood pressure, hyperkalemia, normonatremia (hyponatremia in the 43.4% group) arterial acidemia, and decreased respiratory rate. Circulatory functions of the 15.7% and 24.6% groups returned toward control levels during 8 hr after burn. Severe shock persisted in the 43.4% group, which experienced 70% mortality by 24 hr. These experiments characterize the guinea pig as a reproducible small animal model for studying different severities of burn shock unencumbered by secondary influences associated with general anesthesia.

Animals↗
PubMed1981

Quantitative evaluation of plasma-opsonizing activity from the lag period of phagocytosis-connected oxygen consumption by leukocytes in whole blood.

The lag period preceding the burst of oxygen consumption by phagocytes was measured with an oxygen electrode after the addition of unopsonized zymosan in CO-treated and diluted whole blood. The duration of the lag period correlated with the phagocytic index (r = 0.98, p < 0.001). The phagocytic index was defined as the mean number of zymosan particles per phagocyte. The lag period was termed opsonizing time and used for evaluation of plasma opsonizing activity. The opsonizing time was found to be inversely related to the plasma concentration used (< 15%) and was independent of phagocyte concentration. Magnesium ions were required throughout the opsonizing time, but calcium ions were essential only during the initial phase, indicating that the alternative complement pathway plays a major role in the observed opsonizing time. The mean opsonizing times in blood from normal adults and newborn infants were 5.6 +/- 0.7 min (n = 7) and 9.1 +/- 0.7 (n = 4), respectively. The opsonizing time, expressed as its reciprocal value, correlated significantly with phagocytic index, CH50 activity, and immunochemically assayed C3, but not C4, concentration in plasma.

Adult↗
PubMed1980

Acute electric burns. Current diagnostic and therapeutic approaches to management.

A review of 102 cases of high-voltage electric injuries was performed. The average total body surface area was 15.2%. The average age was 32 years. The mortality was 2.1%. Advances in fluid therapy have virtually eliminated renal failure. Devitalized muscle was accurately identified preoperatively with the use of the technetium Tc 99m pyrophosphate muscle scan. Septic complications were reduced substantially by using the following therapeutic modalities: early excision of the burn eschar and necrotic muscle; quantitative wound biopsies to monitor the bacterial flora; allograft as a temporary coverage of open wounds; and early creation of local and distant flaps. Early institution of physical and occupational therapy are mandatory if the patient is to be restored to his or her maximum postinjury potential.

Adolescent↗
PubMed1980

A critical evaluation of povidone-iodine absorption in thermally injured patients.

Povidone-iodine ointment is a widely used topical antimicrobial agent in thermally injured patients. In 17 patients with burns ranging from 4 to 85% TBSA this agent was applied to both partial- and full-thickness burns. Peak serum iodine levels in patients treated within 24 hours of injury ranged from 595 to 4,900 micrograms per dL. The amount of iodine absorbed was directly related to the size of the burn. Serum iodine levels continued to rise until the drug was discontinued and remained elevated for as long as 7 days after discontinuance. Iodine excretion was directly related to renal function. The highest serum and lowest urinary iodine levels were present in patients who developed renal failure. Thyroid function was not affected by drug usage. A proven cause-and-effect relationship between the elevated serum iodine attributed to the absorption of povidone-iodine and metabolic acidosis, hypernatremia, and hyperosmolarity was not established. Close monitoring of the patient's fluid and electrolyte balance is imperative during drug usage. The drug is contraindicated in any patient with impaired renal function. The high serum levels of this inorganic ion imply potential toxicity, but clinical evidence of cell or organ toxicity is as yet undetermined.

Absorption↗
PubMed1980

Pulmonary function measurements in patients with thermal injury and smoke inhalation.

We performed serial pulmonary function measurements in 28 patients with thermal injury in order to investigate the pulmonary effects of smoke inhalation, small and large surface burns, and the combination of burn and inhalation. Patients were studied at postinjury time intervals of 9.0 +/- 0.6 (M +/- SEM), 22.0 +/- 1.6, 37.3 +/- 2.2, 58.4 +/- 2.5 hours; 11.5 +/- 0.6 days; 1.1 +/- 0.1 and 5.0 +/- 0.5 months. Spirometry was found to be as useful as more sophisticated measurements in the examination of both burn and smoke inhalation groups. Smoke inhalation caused severe airway obstruction 9 h after exposure. Patients with surface burn resuscitated with 4 ml of Ringer's lactate/per cent surface area burn/kilogram developed a significant restrictive defect over the first 58 h, despite normal pulmonary capillary wedge pressures. The restrictive defect in these patients correlated with the size of surface and chest burn, degree of fluid retention, and reduction in colloid osmotic pressure. Surface burn and smoke inhalation caused the greatest deterioration in pulmonary function. These defects gradually resolved during the period of observation.

Adult↗
PubMed1980

A comparison of leukocyte function and burn mortality.

Of the several tests which measure leukocyte bactericidal competency only one, chemotaxis, has been reported to reflect both leukocyte dysfunction and patient mortality in major thermal injury. To validate the reliability that chemotaxis reflects mortality functional chemotactic index (FCI) was measured in leukocytes from 33 patients with 30% or greater total body surface area burns. Additionally, nitroblue tetrazolium (NBT) reduction and O2 consumption were compared to FCI. Significant decreases were seen in FCI values compared to normals. No differences, however, were seen in FCI values between surviving and nonsurviving patients. NBT reduction and O2 consumption also showed decreases with a significant difference between the mean decrease in surviving and nonsurviving patients. While the data show all these laboratory tests to be reflective of significant impairments in host defense, they do not appear to be reliable as predictive indices of patient survival and therefore should not be interpreted as such.

Burns↗
PubMed1979

Surgical management of traumatic injuries of the right colon. Twenty years of civilian experience.

Three hundred seven patients with right colon injuries were treated at Parkland Memorial Hospital, Dallas, between 1953 and 1973. These injuries were managed with loop colostomies, suture and cecostomy, primary repair, right colectomy, diverting colostomy, and appendectomy or cecostomy alone. The indications and results of each type of repair are analyzed separately. The mortality (3.21%), morbidity (22%), and hospital stay were not related to the modality of treatment, but were influenced by the injuring agent. Adequate treatment of civilian right colon injuries implies careful individualization to avoid serious septic complications and subsequent mortality.

Adult↗
PubMed1979

Early tangential excision and immediate mesh autografting of deep dermal hand burns.

Thermal injuries to the hand constitute not only one of the most common burns, but one of the most difficult for the burn surgeon to treat. Early wound closure is mandatory if maximum functional return is to be attained and scarring minimized. Over the last three and one-half years, 60 patients with deep dermal dorsal hand and finger burns were treated by tangential excision and immediate mesh autografting. All patients were admitted to the hospital within 24 hours of injury and excision was performed between the third to the tenth post burn day. Operative technique consisted of sequential eschar excision using the Humby knife or Goulian-Weck dermatome until viable dermis was visible. Mesh autograft, ratio 1 to 1(1/2) without expansion, was applied. There was 100% graft take in all but four hands. Hand function with full range of motion returned by the tenth postoperative day. Complications were minor. Patient follow-up ranged from six months to three and one-half years. No patient has required subsequent surgery for scar revision or contracture release. Range of motion in all patients has been excellent and all patients have continued to maintain normal hand function. The cosmetic appearance has been good except for the early "mesh" appearance of the graft which has become less apparent with time. In summary, early tangential excision and immediate mesh autografting of deep dermal dorsal hand burns has fulfilled the following burn principles-preservation of tissue, prevention of wound infection, maintenance of function and early wound closure.

Adolescent↗
PubMed1979

The role of NADH-NADPH oxidase activity in the leukocyte function of burned patients.

Irreversible sepsis, in spite of advancements in topical therapy and antimicrobial agents, remains the leading cause of death in major thermal injury. A defect in intracellular bactericidal capacity in leukocytes from severely burned patients appears to correspond with increases in bacterial wound colonization and ultimate sepsis. This leukocyte defect has been demonstrated by abnormally low nitroblue tetrazolium reduction (NBT) and oxygen consumption of white cells in patients with major thermal injury. The subcellular mechanisms responsible for decreased bactericidal capacity were therefore investigated. Nicotinamide-adenine dinucleotide (NADH) and nicotinamide-adenine phosphodinucleotide (NADPH) oxidase activity was measured in patients with major burns, controls (normals), and in patients with nonburn stress or infection. NADH and NADPH oxidase levels in leukocytes from burn patients were not significantly different from those of normal nonchallenged controls but were significantly lower than the leukocyte values found in the patients with nonburn infections or stress. This NADH and NADPH defect in the subcellular leukocyte fraction suggests that it may be a significant factor in the reduced bactericidal function of the intact leukocyte in thermally injured patients.

Burns↗
PubMed1979

Liquid propane cold injury: a clinicopathologic and experimental study.

A case of liquid propane cold injury is described. This injury was produced by evaporative heat loss, without ignition, from skin and underlying tissues. The cutaneous appearance was that of a flame burn but underlying deep tissue damage was present. Acute vascular compromise and progressive wound sepsis were complications which required surgical intervention. A liquid propane animal model was created which defined the pathophysiology of the clinical injury. The potential for this injury exists wherever volatile liquified gases are used.

Adolescent↗
PubMed1978

Problems and complications of burn shock resuscitation.

The problems and complications of the fluid resuscitation phase of the treatment of major thermal burns are many and varied. Emphasis has been placed on the most important organ system responses commonly observed in the first week after injury. The efficacy of treatment and the lack of available treatment are outlined. The mechanical complications occurring from poorly selected and monitored fluid administration sites, complications of monitoring, problems of constrictive edema (usually in the extremities), airway problems, respiratory care, and innumerable other technical aspects were purposely omitted. While these problems and complications are extremely important and occur commonly in our experience, they are in the realm of technical performance of good emergency and intensive care medicine and their optimal management does not affect the problems and complications of the residual organ systems.

Adult↗