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Biomedical subjects

B A Pruitt

Publications and source records attributed to B A Pruitt.

At least 127 records · Page 7Linked to original sources
PubMed1987

Comparison of quantitative microbiology and histopathology in divided burn-wound biopsy specimens.

We examined the association between quantitative microbiologic results and histopathologic findings in divided biopsy specimens from 200 burned patients. Microbiologic counts were determined as log10 colony-forming units per gram of disrupted tissue. Histopathologic results were scored on a scale of 1 to 6, values of 4 or greater indicating microbial invasion of viable tissue. Agreement of 96.1% was found between negative cultures, arbitrarily identified as those with fewer than 5 logs/g, and histologic absence of invasive infection. In sharp contrast, however, histologic invasion occurred in only 36% of specimens with positive cultures. Though low tissue counts are essentially synonymous with negative histologic findings, quantitative microbiology is not a diagnostic substitute for histologic examination, since high tissue counts quite commonly do not indicate invasion. The principal value of quantitative burn-wound biopsies is the demonstration of predominant burn-wound flora.

Adolescent↗
PubMed1987

Flow cytometric measurement of rat lymphocyte subpopulations after burn injury and burn injury with infection.

Increased infection rates in burned patients may result from a disproportionate increase in the suppressor subpopulations. Measurement of lymphocyte subpopulations is difficult in burned patients because gradient-purified cells are contaminated by nonlymphoid cells. The accuracy of flow cytometric subpopulation analysis was improved by restricting (gating) the analysis to cells with light-scatter intensity typical of lymphocytes. Blood was obtained 48 hours after burn from rats receiving no burns, 30% scald burns, or burns seeded with Pseudomonas aeruginosa to induce infection. Subpopulations were identified by monoclonal antibodies to T-lymphocyte antigens. Gating increased the values obtained for most subpopulations, but the relative differences between groups were unchanged. Burned and infected animals, but not animals burned only, had a decreased ratio of helper to suppressor lymphocytes (HSR) relative to control. A decreased HSR correlated with sepsis, but not with infection susceptibility. This suggests that a decrease in HSR may be a result of infection rather than a cause of susceptibility to infection.

Animals↗
PubMed1987

Nyctohemeral rhythm in melatonin response to isoproterenol in vitro: comparison of rats and Syrian hamsters.

The in vitro response of melatonin synthesis was assessed by incubation of individual whole pineal glands for 4 hr without or with different concentrations of isoproterenol in the medium. Pineals were taken either at the end of the 14-hr light phase (day), or at 6 1/2 hr into the 10-hr dark phase (night) after a 30-min exposure of the animals to light just before sacrifice at night. The response was greater in pineals taken at night than in those taken at the end of the light phase in rats, but was absent at the end of the light phase in Syrian hamsters. Hamster pineals taken at night responded, though higher isoproterenol concentrations were required than in the rats. Unresponsiveness of hamster pineals during the day may explain previous failure of isoproterenol administration to stimulate pineal MEL content in this species.

Animals↗
PubMed1987

The influence of inhalation injury and pneumonia on burn mortality.

In order to assess the specific effects of inhalation injury and pneumonia on mortality in burn patients, the records of 1058 patients treated at a single institution over a five-year period, 1980-1984, were reviewed. Of these patients, 373 (35%) had inhalation injury diagnosed by bronchoscopy and/or ventilation perfusion lung scan. Of the 373 patients, 141 (38%) had subsequent pneumonia. Among the patients without inhalation injury, pneumonia occurred in 60 of 685 (8.8%). A multiple logistic equation was developed to estimate expected mortality at any age and burn size for patients without either inhalation injury or pneumonia, with either alone, or with both. Subtraction of the expected mortality without either inhalation injury or pneumonia from the expected mortality in the presence of either or both permitted the estimation of additional mortality attributable to these complications. Inhalation injury alone increased mortality by a maximum of 20% and pneumonia by a maximum of 40%, with a maximum increase of approximately 60% when both were present. The influence on mortality was maximal in the midrange of expected mortality without these complications for any age group. These data indicate that inhalation injury and pneumonia have significant, independent, additive effects on burn mortality and that these effects vary with age and burn size in a predictable manner.

Adolescent↗
PubMed1987

A dose-responsive model of smoke inhalation injury. Severity-related alteration in cardiopulmonary function.

The dose responsiveness of selected physiologic indices was studied in a sheep model of smoke inhalation injury. In this model, graded severity of injury was achieved by changing the contact time with smoke (defined by "unit"), whereas other variables were kept constant. Blood gas and cardiopulmonary indices were measured in 70 sheep, including 12 controls, either 24 or 72 hours after exposure to 3, 6, 9, 12, 15, or 18 units of smoke. A 12-unit dose of smoke was fatal within 72 hours and an 18-unit dose was fatal within 24 hours. The best correlation between smoke dose and response was observed in arterial oxygen tension 24 hours after exposure. At 24 hours, most of the cardiopulmonary indices showed significant change only after a 12-unit exposure. Although the exact shape of the dose-response curve could not be defined, sigmoid or curved linear shape was suggested, reflecting the progressive deterioration.

Animals↗
PubMed1987

Central hypogonadism in burned men.

Serum samples were obtained from 30 burned men at different times up to the fourth month after injury. Mean concentrations of estradiol (E2) were elevated above those for healthy control subjects. Mean serum total testosterone (T), sex hormone-binding globulin (SHBG), bioassayable luteinizing hormone (LH), thyroxine (T4), triiodothyronine (T3) and their free indices (FT4I and FT3I) were depressed below those of controls during the first postburn week. Mean values for T and LH were progressively higher in samples taken from later time periods but remained depressed. Mean SHBG and thyroid hormones rose and were not significantly different from control values during later periods of the study. Calculated non-SHBG-bound T (NSBT) was below normal in each time period. The close correlation of SHBG values with those of T3 and FT3I in the patients suggests that SHBG responds to the altered thyroid hormone milieu of burn injury. It is postulated that elevated serum E2 perhaps from adrenal precursors promotes an alteration of hypothalamic function resulting in a markedly reduced secretion of bioactive LH and diminished Leydig cell function.

Adolescent↗
PubMed1987

Clinical trial of imipenem/cilastatin in severely burned and infected patients.

Imipenem/cilastatin was examined for safety and efficacy in a population of 20 seriously burned patients with acute bacterial infections. The study was made up of 18 males and two females with an average age of 38 years and average burn size of 52 per cent of the total body surface area. Inhalation injury was present in 14 patients. The infections treated included 16 pulmonary, two urinary tract, one wound and one bacteremia. Treatment was clinically successful in 13 patients; five patients had no improvement and the clinical response could not be determined in two in whom multisystem organ failure preceded the treated infection. All of the clinical failures were in the pulmonary infection group. No serious toxicity or side effects were noted. No patient died while receiving the drug or as a consequence of known failure of the drug. Microbiologic success was noted in 12. Resistant organisms developed in eight of whom five were in the clinical failure group. Pseudomonas aeruginosa resistant to imipenem/cilastatin was isolated from seven patients and occurred at an average of 3.6 days after treatment was begun.

Adult↗
PubMed1986

Effects of environment on infection in burn patients.

Burn patients in an early cohort (n = 173) treated in an intensive care ward without separate enclosures were compared with a later cohort (n = 213) treated in a renovated unit with separate bed enclosures. The number of patients developing infection was significantly reduced in the late group. Observed mortality was compared with mortality predicted on the basis of burn size and age alone. Reduction in observed compared with predicted mortality, inapparent in the early group, was seen in the late group and was restricted to the subgroup of patients with predicted mortality of 25% to 75%, in which the observed mortality of 28.3% was less than the predicted mortality of 48.7%. The incidence of infected patients was reduced from 58.1% in the early cohort to 30.4% in the late cohort. In comparison of the early cohort with the late cohort, the overall proportion of patients with bacteremia was reduced from 20.1% to 9.4%, while the incidences of both pneumonia and burn wound invasion remained unchanged. Providencia and Pseudomonas species, endemic in the early cohort, were eliminated in the late cohort. Reduction of infection by environmental manipulation in burn patients was possible and was associated with improved survival.

Adult↗
PubMed1986

Association of burn mortality and bacteremia. A 25-year review.

The relationship between bacteremia and mortality was studied in 5882 burn patients consecutively admitted to one burn center between 1959 and 1983. Among 5877 patients with adequate data, 1481 had one or more positive blood cultures; 1529 patients died. A predictor of mortality was developed, based on data from the 4396 patients without positive blood cultures, and used to assign a discrete probability of death in the absence of bacteremia to all the patients. Comparisons were then made between observed and predicted mortality in subsets of patients with bacteremia due to enteric organisms, Pseudomonas species, gram-positive organisms, or yeastlike organisms, or without bacteremia. These comparisons indicate significantly increased mortality in patients with gram-negative bacteremia, an equivocal increase in patients with blood cultures positive for yeastlike organisms, and no increase attributable to gram-positive bacteremia.

Adolescent↗
PubMed1986

Hypothalamic neuroendocrine correlates of cutaneous burn injury in the rat: I. Scanning electron microscopy.

Rats were given a standard scald burn on 60% of the body surface or only a sham burn and were sacrificed at intervals from 6 hr to 14 days later. Serum thyroxine (T4), free thyroxine index (FT4I) and triiodothyronine (T3) were depressed compared to values in respective shams as early as 6 hr post-burn. T4 and FT4I were less depressed on post-burn days (PBD) 2-3 than on PBD 1 and then exhibited a further fall. T3 remained depressed through PBD 14. Pineal melatonin content was elevated at 6 hr and fell to the normal daytime range in subsequent samples. The ventral portion of the diencephalon was prepared for scanning electron microscopy. Only in the burned rats and beginning on PBD 2, large numbers of supraependymal neurons (SEN) appeared in the ventricular space attached to the inferior walls and floor of the third cerebral ventricle. Transmission electron microscopy was used to confirm the neuronal nature of the SEN. Viewed by scanning electron microscopy, these persisted through PBD 14. SEN were interconnected by cables of their neurites exhibiting varicosities on individual neurites as they passed over perikarya of other SEN. Some SEN were seen to be only partially emerged from the underlying tissue and others were seen to send a thick process into the hypothalamic tissue. These observations indicate that after peripheral injury there is marked plasticity of the brain in an area thought to control the endocrine systems that show abnormalities after such a peripheral injury. The timing, location and nature of these anatomic changes indicate the possibility that at least some aspects of central nervous orchestration of the endocrine metabolic response to injury may be related to the emergence of a neuronal system receiving or sending messages through the cerebrospinal fluid and/or through new neurite circuits along the surface of the third ventricular wall. These structures may appear in response to initial primary hormonal changes and/or may play a role in maintaining the post-injury hormonal milieu manifested in part by a subsequent second fall in serum T4.

Animals↗
PubMed1986

Effects of infection on oxygen consumption and core temperature in experimental thermal injury.

Oxygen consumption (VO2) and colonic temperature (Tc) were measured in groups of rats before and after 30% total body surface, full thickness burns. Some wounds were seeded with Pseudomonas aeruginosa or Staphylococcus epidermidis, and some seeded wounds were treated with Sulfamylon or Silvadene. Three groups became bacteremic (B) during the 2-3 week period of observation. At an ambient temperature (Ta) of 32 C, VO2 of the B group rose from 0.83 +/- 0.01 to 1.20 +/- 0.01 ml/hr/g (mean +/- S.E., p less than 0.001) versus 0.81 +/- 0.01 to 0.99 +/- 0.02 for nine nonbacteremic (NB) groups (p less than 0.001). Tc increased only in the B groups--from 36.8 +/- 0.1 to 37.7 +/- 0.1 C (p less than 0.001). In the second or third week postinjury, VO2 of the NB rats was reduced when Ta was increased to 34 C; Tc followed changes in Ta. Sulfamylon lowered VO2 of P. aeruginosa seeded, NB rats. The metabolic cost of wound contamination appeared to vary with bacterial strain. The metabolic effects of infection appear to be a continuum, beginning with a modest rise in VO2 and progressing to greater increases in VO2 and Tc with wound invasion and systemic infection.

Animals↗
PubMed1986

Rhythmic melatonin response of the Syrian hamster pineal gland to norepinephrine in vitro and in vivo.

Norepinephrine (NE, 10(-6) M) stimulated melatonin accumulation in the incubation medium of rat (but not Syrian hamster) pineals taken at the end of the light phase. However, NE elevated melatonin accumulation in the medium of pineals taken after 20 min of light exposure of animals of either species at 6 h into the 10-h dark phase. A dose response to 10(-7)-10(-5) M NE was observed in both the medium and pineals upon incubation of pineals taken from rats at 4 h into the light phase and from hamsters after 20 min light exposure at 6 h into the dark phase. Approximately 95% of the melatonin present was in the medium. The incubation time was 4 h in all cases. Subcutaneous injection of 1 microgram/g NE (either at the end of the light phase or after 30 min of light at 6 h into the dark phase) did not stimulate in vivo Syrian hamster pineal melatonin content determined 1 or 2 h after injection, whether the hamsters were placed in light or darkness after the injection. However, after 30 min of light beginning at 6 h into dark, injection of 5 micrograms/g desipramine (DMI, a blocker of catecholamine uptake into nerve endings) allowed a dramatic hamster pineal melatonin response to additional injection of 1 microgram/g NE, observed at 1 and 2 h in light after injection. A small effect of DMI alone was seen. DMI also potentiated the effect of NE (each 10(-6) M) on melatonin accumulation in the medium of incubated hamster pineals taken after a short light exposure at night. No significant stimulatory effect of NE and/or DMI was seen in vivo or in vitro near the middle of the light phase. Measurement of melatonin in the incubation medium is a useful method for studying pineal function. The Syrian hamster pineal has rhythm of sensitivity to NE (sensitivity evident at night) and even at night is protected by neuronal uptake from circulating NE-induced stimulation of melatonin production. NE appears to be the neurotransmitter for stimulation of pineal melatonin production in the Syrian hamster. The sensitivity rhythm and uptake protection might provide specificity of control of the nightly melatonin signal by reducing the chance of a melatonin response during the day or a response to circulating catecholamines from general sympathetic stimuli.

Animals↗
PubMed1986

Base-line and postthermal injury plasma histamine in rats.

Although plasma histamine concentration has been reported to increase after thermal injury in the rat to as much as 100-fold over normal human plasma levels, the pathophysiological significance and relevance to human disease is questionable. Lack of confidence in the rat as a model of histamine-mediated disease is based on reports that normal rat base-line plasma histamine concentration exceeds that of human plasma by 20- to 70-fold. The present study confirms that high concentrations of histamine (20-68.9 ng/ml) are found in rat plasma obtained in an uncontrolled manner; but concentrations are lower (1.17 +/- 0.49 ng/ml) or undetectable in a sensitive radioenzymatic assay when sampling technique and plasma isolation are controlled. The primary cause for falsely elevated values for plasma histamine concentration appeared to be due to manipulation of the rat. Plasma histamine concentration increased within 1 min after thermal injury and the increase was proportional to extent of surface area injured. In contrast to the finding of a single time-related peak of plasma histamine concentration after partial-thickness burn, a biphasic elevation was found after full-thickness injury. Thus the data indicate that normal rat plasma histamine concentration is similar to that of the human and below the reported threshold for modulation of a variety of immune responses. Furthermore, the data support a role for histamine and other mast-cell mediators in the local and systemic responses to injury.

Animals↗
PubMed1986

Thermoregulatory and nonthermoregulatory heat production in burned rat.

Severely burned patients are hypermetabolic within their thermoneutral zone (TNZ), where there are no thermoregulatory demands on heat production. The rat has been used as a model of postburn hypermetabolism without clear evidence that it behaves in a similar way. Male rats (400-500 g; n = 34-39) were placed as a group in a respiration chamber and metabolic rates for the average rat were determined over 3-6 h at ambient temperatures between 9 and 36 degrees C. Colonic temperatures (Tco) and body weights were measured after each run. Animals were studied sequentially as normals (N), after clipping (C) and following 50% total body surface scald burns. Clipping increased the lower critical temperature (LCT) from 27.7 to 29.1 degrees C without affecting resting heat production (N = 42.6 +/- 0.5; C = 42.0 +/- 0.8 W/m2; mean +/- S.E.) or Tco (N = 36.6 +/- 0.1; C = 36.6 +/- 0.1 degrees C) in the TNZ. Injury increased LCT to 32.8 degrees C and the burned animals were hypermetabolic (47.2 +/- 0.6 W/m2; P less than 0.05 vs. N) and febrile (36.9 +/- 0.1 degrees C; P less than 0.05 vs. N) in the elevated TNZ. These metabolic and temperature responses of burned rats are limited in magnitude but are qualitatively similar to those of patients. The extra heat production in the TNZ reflects the basic metabolic cost of injury.

Animals↗
PubMed1986

Evaluation of (1-sarcosine, 8-isoleucine) angiotensin II as a therapeutic agent for oleic acid-induced pulmonary edema.

(1-Sarcosine, 8-isoleucine) angiotensin II was assessed as a therapeutic agent for acute respiratory distress syndrome with oleic acid pulmonary edema in sheep used as an experimental model. Under general anesthesia with controlled mechanical ventilation with 100% oxygen, 32 sheep received oleic acid (0.075 ml/kg) intravenously. After oleic acid infusion, 20 animals were treated with continuous intravenous infusion of the angiotensin II analogue; nine received 300 ng/kg/min, six received 600 ng/kg/min, and five received 2000 ng/kg/min. Cardiopulmonary measurements were repeated every 30 minutes for 270 minutes. According to time-integrated PaO2, six of 15 animals of the groups given 300 and 600 ng/kg/min (43%) did not respond to the treatment. All animals responded in the group given 2000 ng/kg/min. Animals in the latter group had lower Qs/Qt, PaCO2, and airway resistance than had the control animals. Elevation of pulmonary vascular resistance was limited and mean arterial blood pressure was well maintained. These results reveal that (1-Sar, 8-Ile) angiotensin II is effective in the treatment of oleic acid-induced pulmonary edema.

1-Sarcosine-8-Isoleucine Angiotensin II↗
PubMed1985

Lightning injury with survival in five patients.

Of a total of 4,153 admissions, five patients with lightning-associated injuries were admitted to a burn center during a 15-year period, 1969 through 1983. In these patients, the burned portion of the total body surface ranged from 3% to 29% (average, 16%), and all survived. The associated injuries and complications in these lightning-strike victims and a review of treatment guidelines are presented.

Adolescent↗
PubMed1985

Microbial colonization in a new intensive care burn unit. A prospective cohort study.

Renovation of an existing intensive care burn facility required closure for ten months. An interim eight-bed open intensive care ward (B) was established in a burn convalescence ward. The renovated unit (A) contained nine single-bed intensive care rooms and seven intermediate-level care beds in four rooms. Patients admitted to unit A were treated as a cohort. The first 25 admissions to unit A and the last 25 admissions to ward B meeting the inclusion criteria were compared. Microbial colonization was monitored by a fixed protocol of admission and multiple weekly sputum, wound, stool, and urine cultures. During intensive care, both cohorts exhibited the same incidence of gram-negative wound, sputum, and urine colonization. Occurrence of antibiotic-resistant organisms was the same. No evidence of bacterial cross-contamination was observed between A and B. A continuation of Providencia stuartii and Pseudomonas aeruginosa (type 15) endemics occurred in B. The collected data demonstrate that the A cohort was colonized with new, similar but distinct gram-negative organisms and indicate that cohort separation may be a practical way of eliminating endemic resistant gram-negative organisms from burn units.

Adult↗