Immunolocalization of the hyaluronan receptor CD44 in the reproductive tract of the mare.

Hyaluronan (HA), a glycosaminoglycan, is a major component of the pericellular matrix which envelopes mammalian cells. Binding of hyaluronan to one of its specific receptors, CD44, modulates transduction of intracellular signals which direct a variety of processes, including embryogenesis, wound healing, inflammation, and neoplasia. Since regulation of these processes is critical to equine reproductive success, localization of constitutive CD44 expression was evaluated by immunohistochemical methods in ovarian, oviductal, and uterine tissues from healthy mares. Ovarian stroma contained thecal cells with varying CD44 immunopositivity. Follicular and granulosa cells of some antral and atretic follicles were positive for CD44. In the oviduct, the luminal epithelium was variably positive for CD44, with overall decreasing intensity of immunostaining from the infundibulum to the isthmus. The CD44 molecule was expressed strongly by surface epithelial cells of the uterine endometrium, but was present only rarely among cells of uterine glands. In addition, CD44 was expressed by smooth muscle cells of vascular walls, oviduct, and uterus. Since CD44 is known to modulate cell movement and differentiation, and was present at multiple sites in the reproductive tract of normal mares, we inferred there may be an important role for the HA-CD44 signaling pathway in reproductive function and inflammation.

An outbreak of methicillin-resistant Staphylococcus aureus skin infections resulting from horse to human transmission in a veterinary hospital.

There are increasing reports of methicillin-resistant Staphylococcus aureus (MRSA) infection and colonization in horses and evidence that MRSA can be transmitted between horses and humans. The objective of this study was to investigate reports of skin infection in personnel working with a foal with community-associated MRSA colonization and subsequent infection. Clinical diagnostic specimens were collected from individuals reporting skin lesions following contact with the affected foal. Nasal and groin screening swabs were collected from other veterinary personnel that attended a voluntary screening clinic. MRSA skin infections were identified in three neonatal intensive care unit personnel. Nasal colonization was subsequently identified in 10/103 (9.7%) other veterinary hospital personnel. Isolates were indistinguishable by pulsed field gel electrophoresis, classified as Canadian epidemic MRSA-5, possessed SCCmecIV, were negative for the Panton-Valentine leukocidin and were multidrug resistant. Transmission to veterinary personnel despite short-term contact with standard protective barriers highlights the potential importance of MRSA as an emerging zoonotic pathogen, and indicates that further evaluation of interspecies transmission of MRSA and means to prevent zoonotic infection are required.

Polyclonal antibodies to rat interleukin-6 attenuate fever in rats after burn injuries: a preliminary report.

Rats with 50% total body surface area full-thickness burn injuries have sustained increases in body temperature without evidence of sepsis. In this animal model, the only known endogenous pyrogen consistently present in plasma is interleukin-6 (IL-6). We investigated the hypothesis that IL-6 acts as an endogenous pyrogen and produces the observed increase in body temperature. Body temperature and activity index were recorded every 5 minutes for control rats and rats with burns (50% total body surface area scald burns) for a period before the burn injuries and through the eighth day after the burn injuries. On the fifth day after the burn injuries, between 8 and 9 AM, control animals and animals with burns were given an intra-arterial dose of IL-6 polyclonal neutralizing antibody (IL-6 pAb) that was equivalent to one half of the neutralizing dose of IL-6 pAb. This calculation was based on plasma levels of IL-6 obtained from rats with burns in previous studies and on the neutralizing capability of the IL-6 used. On the sixth and seventh days after the burn injuries, a full neutralizing dose of IL-6 pAb was given. Blood samples were obtained for IL-6 assays at baseline and after treatment with IL-6 pAb but were lost because of the failure of an ultracold freezer. A one half neutralizing dose of IL-6 pAb produced no discernible effect on the body temperature of the control animals or of the animals with burns. On the sixth and seventh days after the burn injury, IL-6 pAb produced 45% and 34% respective decreases in body temperature compared with the animals with burns that received saline solution (P < .05 for both comparisons). On the eighth day after the burn injuries, the effect had completely dissipated. We concluded that our results support the idea that increased circulating levels of IL-6 may be causally related to fever that occurs in nonseptic rats with large burn wounds.

The effect of indomethacin on the cytokine cascade and body temperature following burn injury in rats.

This study investigates the hypothesis that indomethacin's ability to prevent "fever" following burn injury in rats is mediated via decreased plasma concentrations of IL-6, the putative mediator of increased body temperature. Sprague-Dawley rats had radio transmitters and osmotic pumps containing indomethacin placed in the peritoneal cavity. Seven days later full thickness scald burns to 50% of the body surface area were produced. Following burn injuries, daily blood samples were obtained from a carotid catheter for assay of lipopolysaccharide (LPS), interleukin-1alpha (IL-1alpha), IL-1beta, tumor necrosis factor-alpha (TNF-alpha) and IL-6. In addition, body temperature (T(B)) and activity index were obtained every five minutes by telemetry. There were four experimental groups: burn + indomethacin (B-In); burn + polyethylene glycol (Peg) (B-Peg); control + indomethacin (C-In); and control + Peg (C-Peg). Burned animals demonstrated a significant two-fold increase in plasma IL-1alpha levels (p=0.004) and a seven-fold increment in IL-6 (p=0.0001) through the 7th PBD, and indomethacin administration had no significant effect upon the cytokine plasma levels. There were no significant increases in IL-1beta, TNF-alpha or LPS in any group. Indomethacin eliminated the chronic increase in T(B) following burn injury, and this effect was not produced by changes in plasma levels of the endogenous pyrogens IL-1alpha and IL-6.

Vagotomy modifies but does not eliminate the increase in body temperature following burn injury in rats.

INTRODUCTION: Rats with burn injury to > or = 50% of the BSA demonstrate a significant increase in body temperature (T(B)) during light hours, and decrease of circadian variation in T(B). This study investigated the hypothesis that part or all of the signal for increased T(B) in rats with burn injury is transmitted to the central nervous system by way of afferent vagal fibers. METHODS: Four groups of animals were studied: Burn-Sham Vagotomy; Control-Sham Vagotomy; Burn-Vagotomy and Control-Vagotomy. Anesthetized animals had bilateral subdiaphragmatic vagotomy (VagX) or sham VagX performed, and AM radio transmitters were implanted in the peritoneal cavity for the purpose of recording T(B) and activity index (AI). Following a one week recovery period, burn animals received scald burns equal to 50.3 +/- 2.5% BSA. RESULTS: The main effect of VagX upon T(B) was a small but significant reduction in T(B) during dark hours. At least 87% of this decrease in post-burn T(B) was also present for the control vagotomy group. Vagotomy had no effect on the increase in T(B) for the burn groups during light hours. During dark hours, VagX significantly reduced T(B) in burns and controls, and burn injury significantly reduced activity. CONCLUSIONS: One may speculate that afferent vagal signals are partially responsible for maintenance of T(B), with or without burn injury, and that the major signal for increase in T(B) for animals with burn injury is not a neural one via afferent vagal pathways.

Humoral versus neural pathways for fever production in rats after administration of lipopolysaccharide.

BACKGROUND: These studies address the question of the relative roles of humoral and neural pathways in the genesis and control of the fever component of the acute phase response. METHODS: Two experiments were performed to examine the effect of vagotomy (VagX) on the febrile response to intraperitoneal (i.p.) and intra-arterial (i.a.) lipopolysaccharide (LPS), and plasma cytokine and LPS concentrations after intravenous (i.v.) or i.p. injections of LPS. In experiment 1, body temperature (T(B)) was obtained from unperturbed animals by using radio transmitters and telemetry after injection of LPS i.a. or i.p. In the second study, serial blood samples were obtained for cytokine and LPS assay after injection of LPS either i.v. or i.p. Colonic temperatures (T(C)) were obtained from indwelling thermistors. RESULTS: The maximal increments in T(B) for animals receiving LPS i.a. and i.p. with or without VagX were not different from one another: sham vagotomy (Sham-VagX) + LPS i.a., 1.20 +/- 0.26 degrees C; VagX + LPS i.a., 1.23 +/- 0.64 degrees C; Sham-VagX + LPS i.p., 1.45 +/- 0.27 degrees C; VagX + LPS i.p., 1.50 +/- 0.35 degrees C (F = 1.12, p = 0.36). Neither were the four resulting response curves for T(B) different from one another. Plasma levels of LPS, tumor necrosis factor-alpha, and interleukin-6 were significantly elevated at 45 minutes after LPS injection by either the i.v. or i.p. routes, preceding any increments in T(B), and were not effected by VagX. CONCLUSION: Fever development for animals receiving LPS in experiment 1 demonstrates a temporal relationship -- with increments in plasma levels of LPS and pyrogenic cytokines obtained in experiment 2 after administration of LPS either i.p. or i.v. Vagotomy had no discernible effect on the responses regardless of the route of administration of LPS.

Early prediction of persisting post-concussion symptoms following mild and moderate head injuries.

OBJECTIVES: King (1996) reported that a combination of emotional, organic and neuropsychological measures taken at 7-10 days following mild and moderate head injury may significantly help predict patients most likely to suffer persisting post-concussion symptoms (PCS) at three months post-injury. This study investigated a cross-validation sample (N = 57) to determine whether the results would be replicated for the early prediction of longer-term sufferers (i.e. those with persisting symptoms at 6 months post-injury). DESIGN: Multiple regression analyses were used in which scores on the Hospital Anxiety and Depression Scale, Impact of Event Scale, Short Orientation Memory and Concentration Test, Rivermead Post-Concussion Symptoms Questionnaire and Post-Traumatic Amnesia taken at 7-10 days post-injury were the independent measures. Scoring on the Rivermead Post-Concussion Symptoms Questionnaire taken at 6 months post-injury was the dependent measure. METHODS: Sixty-six consecutive patients admitted to any trauma ward in Oxfordshire with a mild or moderate head injury were recruited from a largescale randomized controlled sample. The assessment measures were administered at 7-10 days post-injury and the Rivermead Post-Concussion Symptoms Questionnaire at 6 months post-injury. Nine patients were unable to be followed up, leaving an active sample of 57. RESULTS: The cross-validation data confirmed that a similar combination of measures to that found in the original study best predicted persisting PCS but that the strength of prediction diminished for the longer term prediction (i.e. 6 months post-injury). CONCLUSIONS: The Hospital Anxiety and Depression Scale, Impact of Even Scale and Post-Traumatic Amnesia in combination are recommended as useful prognostic screening instruments for predicting persisting PCS, but great caution is required if they are used to aid predictions beyond 3 months post-injury.

Chronic indomethacin administration blocks increased body temperature after burn injury in rats.

This study investigates the hypothesis that continuous administration of indomethacin (a cyclo-oxygenase inhibitor) will chronically reduce body temperature (TB) in burned rats (i.e., modulate "true" fever). Male Sprague-Dawley rats had radio transmitters and osmotic pumps (containing indomethacin) placed in the peritoneal cavity, and 7 days later large full-thickness scald burns were produced. Activity and TB were continually recorded through the 14th postburn day (PBD). There were 4 experimental groups: burn + indomethacin (B-In), n = 9; burn + polyethylene glycol (B-Peg), n = 6; control + indomethacin (C-In), n = 9; and control + polyethylene glycol (C-Peg), n = 6. From PBD 5 through PBD 10, the B-Peg group had consistently and significantly higher TB during light hours than the B-In, C-In, and C-Peg groups. From PBD 7 through PBD 12, the B-In group had an average TB during light hours significantly lower or not different than the C-In and C-Peg groups. These results support the hypothesis that in this burned-rat model chronically increased TB during the light hours may be "fever" (rather than hyperthermia) and that the final effector link could be a prostanoid because changes in activity do not explain the changes in body temperature.

Routine follow up after head injury: a second randomised controlled trial.

OBJECTIVE: To confirm that patients admitted to hospital with a head injury benefit from a routinely offered early intervention service. PATIENTS AND METHODS: A mixed rural and urban Health District of 560000 people with two accident and emergency departments provided the setting. Existing routine services for most patients with head injury are minimal. All patients aged 16-65 years admitted to hospital after a head injury of any severity, with or without other injuries entered the trial. Prospective randomisation, with a block randomisation procedure was used to allocate all eligible patients to either: a group offered an additional service by a specialist team; or a group receiving existing standard services. Patients were assessed at follow up six months after injury. The primary outcome measure was the Rivermead head injury follow up questionnaire, a validated and reliable measure of social disability. The Rivermead post-concussion symptoms questionnaire was used to estimate severity of post-concussion symptoms. Each patient in the trial group was contacted 7-10 days after injury, and offered assessment and interventions as needed. These initially focused on the provision of information, support, and advice. Forty six per cent of patients in the trial group also received further outpatient intervention or additional support by telephone. RESULTS: 314 patients were registered: 184 were randomised into the trial group, 130 into the control group. For prognostic data, the groups were comparable at randomisation, and remained comparable when assessed at six months. 132 trial and 86 control patients were followed up at six months after injury. Patients' posttraumatic amnesia ranged from mild (n=79, 40%), and moderate (n=62, 32%), to severe (n=38, 19%) and very severe (n=17, 9%). The trial group patients had significantly less social disability (p=0.01) and significantly less severe post-concussion symptoms (p=0.02) at follow up at six months after injury than the control group patients. CONCLUSIONS: The early interventions offered by a specialist service significantly reduced social morbidity and severity of post-concussion symptoms in trial group patients at six months after head injury. Recommendations about how specialist services should be targeted are made both in the light of these results and those from a previous randomised controlled trial.

Calorigenic response of burned rats with adrenal medullectomies to catecholamines.

In previous studies, we established that circulating epinephrine (E) is not essential for a normal hypermetabolic response to burn injury in the rat, within the zone of thermal neutrality. In other studies, burned rats with adrenal medullectomy (AdxB) studied at 22 degrees C were unable to maintain rectal temperature (TR) after alpha-adrenergic blockage. These data suggest that norepinephrine (NE) is calorigenic in such animals without formal cold acclimation. These studies investigate the hypothesis that, contrary to the usual belief, norepinephrine might be calorigenic in rats without formal cold acclimation. Burned (B) and control (C) rats with adrenal medullectomies (Adx) and Sham (S) Adx (AdxB, SAdxB, AdxC, and SAdxC) were housed at either 22 degrees C or 28 degrees C. Calorimetry was performed during the eighth to eleventh days after the burn. For groups housed at 22 degrees C and studied at 28 degrees C, NE given intravenously (iv) produced an average 16.5%+/-3.3% increment in heat production (HP) for the four groups, which was significant for AdxB, SAdxB, and SAdxC. Intravenous administration of E produced an average increment in HP of 4.44%+/-4.1%, which was not significant. HP was significantly higher after NE than E in three cases. Studies with animals housed at 28 degrees C and studied at 28 degrees C produced intermediate but similar results. For groups housed at 28 degrees C and studied at 22 degrees C, iv administration of E and NE produced average decreases in He of 18%+/-6.7% for E and 10.75%+/-4.7% for NE. Except for the AdxC group, these differences were significant. These data suggest that chronic exposure to an ambient temperature of 22 degrees C produces an enhanced calorigenic response to NE in burn and control rats. Based on the data presented here, combined with earlier studies, NE must be considered as a facilitator for hypermetabolic response to burn injury in the rat. It is interesting to speculate whether NE is calorigenic for patients with large burn wounds, which are managed without dressings at ambient temperatures below thermal neutrality.

Studies on the mechanism of fever after intravenous administration of endotoxin.

BACKGROUND: The sequential events in fever production after intravenous administration of lipopolysaccharide (LPS) remain unsettled and controversial. Vessels of the organum vasculosum laminae terminalis (OVLT) lack the tight junctions of the blood-brain barrier and allow substances of high molecular weight to enter the interstitium but not the neuropil. The present studies investigate the hypothesis that the OVLT is needed for fever production after intravenous administration of LPS in the rat. METHODS: Electrolytic lesions were produced in the OVLT of rats. After recovery, left carotid and right atrial catheters were inserted, and 24 hours later calorimetry was performed. Blood was drawn for baseline assay for cytokines and LPS after which LPS was given intravenously, with studies continued for 5 hours, and additional blood samples were drawn at 90 and 300 minutes. RESULTS: The maximal increment in rectal temperature for the sham lesion LPS group (1.25 +/- 0.44 degrees C) was significantly greater than for the sham-saline (-0.05 +/- 0.46 degrees C) and the lesion-LPS groups (0.35 +/- 0.45 degrees C) for minutes 120 to 300. Ninety minutes after LPS administration, serum levels of interleukin (IL)-6, tumor necrosis factor-alpha, and LPS were significantly elevated (p < 0.0001) above baseline for the sham-LPS and lesion-LPS groups. IL-1beta serum levels remained below detection levels. CONCLUSION: Large lesions of the OVLT prevent and/or attenuate fever due to LPS even though tumor necrosis factor-alpha and IL-6 are greatly increased in serum. IL-1beta does not seem to be an endogenous humoral mediator in this model.

Pathogenesis of fever in a rat burn model: the role of cytokines and lipopolysaccharide.

We investigated the possible causal relationship between interleukin-6 (IL-6) and increased body temperature (T(B)) in a rat burn model. Transmitters for measuring core temperature and estimating activity were implanted in the abdominal cavity. Animals in the burn group were clipped and received full-thickness scald burns to 45% to 55% of the body surface area, and control animals were clipped. T(B) and activity were measured continuously through the tenth postburn day. Carotid lines were placed, and serial blood samples obtained for lipopolysaccharide, IL-6, and tumor necrosis factor-alpha assay. From the third through the tenth postburn day, the burn group had a consistently significantly higher T(B) during light hours than the control group did (average, 0.45 degrees C +/- 10 degrees C, p = 0.0001). Differences in activity during light hours were not significant between the two groups, therefore, do not account for the observed significant difference in T(B). The average IL-6 serum levels were 3.5-fold higher for the burned animals. In this study, burn and control serum levels of IL-6 demonstrated positive correlation with T(B). These data suggest, but do not prove, a causal relationship between IL-6 and fever in the rat burn model, and make it unlikely that circulating systemic lipopolysaccharide is the cause.

Manipulation of the inflammatory response to burn injury.

BACKGROUND: Burn injury is characterized by hypermetabolism and protein catabolism. Endotoxin, derived from either wound or gut, may participate in this response. METHODS: Eleven seriously burned patients were treated with the endotoxin-binding agent polymyxin B and underwent partitional calorimetry and nitrogen balance studies. The data from theses patients were compared with data from 28 contemporary, similarly burned patients who did not receive polymyxin B. RESULTS: Elevated levels of circulating endotoxin were not consistently detected in either group. Interleukin-6 was elevated and correlated with rectal temperature and nitrogen excretion in both groups. Administration of polymyxin B produced no change in metabolic rate but produced a significantly more positive nitrogen balance and was associated with a prompt reduction in interleukin-6 levels. CONCLUSIONS: These data support the hypothesis that endotoxin plays a role in the postburn protein catabolism but not in the hypermetabolic response. This protein catabolic response is statistically associated with circulating interleukin-6 levels, suggesting a possible role for interleukin-6 in postinjury protein wasting.

Measurement of post-traumatic amnesia: how reliable is it?

OBJECTIVE: To develop and test a clinical protocol for determining post-traumatic amnesia by retrospective questioning. To establish its limits and factors which influence reliability. DESIGN: Two independent assessments using the Rivermead post-traumatic amnesia protocol were undertaken by separate observers on various groups of patients at various time intervals. Analysis investigated the correlations between assessments, the percentage difference between assessments, the number of patients changing category, and the differences between these analyses in the different patient subgroups. Assessments were undertaken both in hospital and in the patients' homes. Four different patient groups were studied. These were group A: 12 inpatients with very severe head injury late after injury; Group B: 40 patients interviewed at home six months after injury; group C: 22 patients interviewed within a few weeks of injury at home; group D: 116 patients interviewed initially within a few weeks and then at six months, on both occasions at home. The Rivermead post-traumatic amnesia protocol involved clinical questioning of the patient to establish how long after injury (in hours/days/weeks) the patient regained continuous day to day memory. All periods of coma were included. Severity was categorised with standard criteria. RESULTS: Overall correlation was good (Spearman's r 0.79), but the correlation was lower for patients with post-traumatic amnesia < 24 hours and when there was a long delay between assessments. In all groups 19%-25% of patients changed categories between assessments, but only 2% changed by two categories. CONCLUSIONS: The assessment of post-traumatic amnesia with the Rivermead post-traumatic amnesia protocol is reasonably reliable. The misclassification rate however, is significant enough that some caution should be taken in individual cases. Other evidence does show post-traumatic amnesia to be valid, and it probably remains the best simple prognostic item available. In clinical practice one should avoid placing too much weight on post-traumatic amnesia alone.

Sequential excision and grafting of the burn injuries of 1507 patients treated between 1967 and 1986: end results and the determinants of death.

The development of a more aggressive approach to burn wound management, leading to complete excision within 72 hours after burn, has led some to conclude that total early excision is a major force behind improved survival rates. We have summarized the results of treatment of 1507 patients with burn injuries treated between 1967 and 1986. Wounds were managed with use of standard topical therapy, occlusive dressings, and staged excision and grafting of full-thickness injury or deep dermal injury (not healed by 21 days). Data were analyzed with use of a logistic-regression model because, with the exception of older patient cohorts, the data did not fit the probit model. The major determinants predicting death were the percentage of body surface area burned, age, smoke inhalation, and the percentage of full-thickness burn. Concordance was 97%. These data show that aggressive sequential wound excision and grafting produces end results comparable with those achieved with complete early burn wound excision for similar age ranges and injury. Early harvest of available donor sites in patients with large burns may be more important to survival than complete early wound excision.

Retrospective evaluation of admission criteria for paediatric electrical injuries.

In the medical community, the practice of admitting all electrical burns for 24-48 h of observation, monitoring and laboratory evaluation is widespread. This retrospective review of paediatric electrical burns was conducted to determine which patients may safely be treated as outpatients. Retrospective analysis of all paediatric burns admitted between 1980 and 1991 identified 35 patients with electrical injuries. Patients were divided into two groups for analysis: those burned by exposure to household voltages (120-240 V; n = 26) and those exposed to high voltages, in excess of 1000 V (n = 9). The majority of household electrical injuries occurred secondary to contact with the household 120 V (21/26). Contact with an extremity accounted for the largest number of these injuries (18/26). The mouth was the second most frequent site of injury (7/26). Most of these patients (20/26) had < 1 per cent BSA burn. No patient in the household-voltage group had an arrythmia that required treatment, nor were there any identified examples of compartment syndrome or other vascular complications. Seven patients did require minimal skin grafting. No deaths occurred in either group. The patients in the household-voltage group were significantly younger. High-voltage electrical injuries occurred in an older patient population and required more aggressive care and surgical intervention. This was evident at the time of initial evaluation. Based on these data, healthy children with small partial-thickness electrical burns and no initial evidence of cardiac or neurovascular injury do not appear to need hospital admission.

Carbohydrate Transport by the Anaerobic Thermophile Clostridium thermocellum LQRI.

Clostridium thermocellum is an anaerobic thermophilic bacterium which degrades cellulose and ferments the resulting glucose, cellobiose, and cellodextrins predominantly to ethanol. However, relatively little information was available on carbohydrate uptake by this bacterium. Washed cells internalized intact oligomers as large as cellopentaose. Since cellobiose and cellodextrin phosphorylase activities were detected in the cytosol and were not associated with cell membranes, phosphorylation of carbohydrates occurred intracellularly. Kinetic studies indicated that cellobiose and larger cellodextrins were taken up by a common uptake system while glucose entered via a separate mechanism. When cells were treated with metabolic inhibitors including iodoacetate and arsenate, the uptake of radiolabeled glucose or cellobiose was reduced by as much as 90%, and this reduction was associated with a 95% decline in intracellular ATP content. A combination of the ionophores nigericin and valinomycin abolished the proton-motive force but only slightly decreased transport and ATP. These results suggested that the two modes of carbohydrate transport in C. thermocellum were ATP dependent. This work is the first demonstration of cellodextrin transport by a cellulolytic bacterium.

Effect of adrenal medullectomy on responses in heat production, plasma catecholamines and body temperature of burned rats to changes in the temperature of the hypothalamus.

Burn (B) and control (C) rats with and without adrenal medullectomy (Adx) 9-11 days postburn underwent warning and cooling of the preoptic anterior hypothalamus (POAH) during calorimetry at 22 degrees and 28 degrees C ambient. Blood was drawn for catecholamine assay during each displacement of the POAH temperature (Thy). The heat production (Hp) for the AdxB group at 22 degrees and 28 degrees C was not different from the Hp for the sham AdxB group (80 +/- 4 vs 86 +/- 8 at 22 degrees C, 58 +/- 8 vs 64 +/- 7 W/m2 at 28 degrees C) in spite of there being no detectable circulating epinephrine (E) for the AdxB groups. Cooling of the POAH of the AdxB 22 degrees C group, however, did not induce a further increment in Hp, in contrast to all other groups. Thy demonstrated good significant negative linear correlation with Hp for all groups. The resulting slopes were not significantly different from one another, indicating no difference in thermal sensitivity of the POAH between the groups. In four of eight groups plasma norepinephrine (NE) demonstrated positive correlation with Hp and in five of eight groups negative correlation with Thy, Plasma E values did not correlate with Hp and demonstrated negative correlation with Thy in two of four possible groups. These data show that postburn hypermetabolism is not dependent on E in the rat and suggest that NE may be calorigenic in burned rats.

Effect of alpha adrenergic blockade on thermoregulation in adrenal demedullated burned rats.

This study in burned rats studied at two ambient temperatures (22 degrees and 28 degrees C) and housed at 28 degrees C was designed to investigate the role of catecholamines in the maintenance of thermal homeostasis following burn injury. Two weeks prior to burn or sham burn, animals underwent adrenal medullectomy or sham adrenal medullectomy. Between postburn days 9 and 13, simultaneous direct and indirect calorimetry was performed following administration of 2mg/kg of phentolamine (alpha adrenergic blocking agent) via a carotid arterial line. Following administration of phentolamine, heat production and body temperature decreased and heat loss increased immediately. The cooling slopes for the burn groups were significantly steeper than for the control groups, within ambient temperatures. Within ambient temperatures, the presence or absence of the adrenal medulla had no discernible effect on the cooling slope of the burns or the controls. The burned animals cooled 1.9-3.5 times faster at 22 degrees than at 28 degrees C, and controls cooled 2.0-3.9 times faster at 22 degrees than at 28 degrees C. Phentolamine produced a several-fold increase in serum concentrations of both norephinephrine (NE) and epinephrine (E), indicating a gross overlap in alpha and beta adrenergic receptor utilization for E and NE. The progressive cooling of the adrenal demedullated burn group at 22 degrees C following phentolamine administration seems to indicate that norepinephrine is calorigenic for rats under these experimental circumstances. These experimental results indicate a relatively non-essential role for catecholamines in the maintenance of thermal homeostasis within the thermal neutral zone in the rat.

The interrelationships between wound management, thermal stress, energy metabolism, and temperature profiles of patients with burns.

This prospective randomized study was performed to evaluate the metabolic and thermal responsiveness of patients with burns to thermal stress with three protocols of wound care: group I (n = 7) treated with dressings and variable ambient temperature selected for patients subjective comfort; group II (n = 7) treated without dressings and variable ambient temperature for patient comfort; group III (n = 6) treated without dressings and ambient temperature of 25 degrees C, electromagnetic heaters were set to achieve patient subjective comfort; and group IV (n = 6) healthy volunteers. After baseline partitional calorimetry was performed, individual patients were cold-challenged while subjectively comfortable by sequentially lowering either the ambient temperature or the output from the electromagnetic heaters. Heat balance and temperatures were obtained after each perturbation in external energy support. For patients in groups I and II, subjective perception of thermal comfort (warm, neutral, neutral and fed, cool, or cold) was more strongly correlated (p < 0.02) with the changes in the rate of heat production than the actual ambient temperature. For patients treated with electromagnetic heaters, changes in heat production were most strongly correlated with the energy output from the electromagnetic heaters. Even though the environmental conditions required to achieve a particular level of comfort are quite different between treatment groups, the difference in temperature between the patient's surface and ambient is approximately the same for groups I, II, and IV for each subjective state.(ABSTRACT TRUNCATED AT 250 WORDS)