Fungal wound infection (not colonization) is independently associated with mortality in burn patients

OBJECTIVE

To analyze the occurrence of fungal wound infection (FWI) after thermal injury and its relationship to mortality.

BACKGROUND

FWI is an uncommon but potentially lethal complication of severe thermal injury.

METHODS

The records of patients with thermal burns admitted to a single burn center (1991-2002) were reviewed. Analyses accounted for total burn size (TBS, percentage body surface area), full-thickness burn size (FTBS, percentage body surface area), age, inhalation injury, sex, and fungal-status category. Fungal colonization and infection were determined histopathologically.

RESULTS

Criteria for inclusion were met by 2651 patients. Each patient's fungal-status category was defined according to the deepest level of fungal involvement observed during the hospital course: no fungus (2476 patients), fungal wound colonization (FWC, 121 patients), or fungal wound infection (FWI, 54 patients). Median TBS (9%, 47%, 64%, respectively) and mortality (5%, 27%, 76%, respectively) varied significantly among fungal-status groups. Logistic regression was used to detect significant independent associations. FWI was associated with higher TBS. Mortality was associated with TBS, FTBS, inhalation injury, FWI, and age. Unlike FWI, FWC was not independently related to mortality, the greater observed mortality in FWC being explained by other variables such as TBS. The odds ratio for FWI (8.16) suggested about the same mortality impact as augmenting TBS by 33%. A midrange TBS of 30% to 60% was required for most of the detectable association of FWI with mortality.

CONCLUSIONS

FWI accompanies larger burns and is associated with mortality in burn patients, particularly in those with TBS 30% to 60%. This association is independent of burn size, inhalation injury, and age.

A temporal study of gene expression in rat lung following fixed-volume hemorrhage

Previous studies have indicated that hemorrhage may predispose the lung to respiratory distress syndrome. Gene expression profiling with oligonucleotide microarrays was used to evaluate the genetic responses of the lung to hemorrhage. Conscious rats, chronically instrumented with a catheter and telemetry device to record blood pressure, heart rate, and temperature, had 40% of their estimated blood volume removed at a rate of 1 ml/min over 7-10 min. Groups of three or more rats were euthanized at 1, 3, 6, 16, 24, 48, or 72 h following hemorrhage. Two additional groups were unmanipulated controls and instrumented animals with sham hemorrhage. Total RNA was isolated from lung, reverse-transcribed to cDNA, fluorescently labeled, and hybridized to oligonucleotide microarrays probing 5,671 rat genes. After hemorrhage, statistically detectable alteration of expression was seen in approximately 0.8% of the genes at some time during the 72-h test period (vs. sham hemorrhage) as determined by false discovery rate statistics in the statistical analysis of microarrays program. A subset was confirmed by RT-PCR analysis. Hemorrhage influenced genes that regulate intracellular signaling and structure, growth factors, and hormonal receptors. There also appeared to be increased expression of genes that may mediate sequestration of neutrophils and mononuclear cells from the circulation. This hemorrhage model, although producing severe hemodynamic alterations, avoided mortality and histological evidence of lung damage, a feature intended to help ensure reliable evaluation of gene expression. These results indicate that gene expression profiling with microarrays provides a new tool for exploring the response of a tissue to systemic blood loss.

One Hundred Ninety-Five Cases of High-Voltage Electric Injury

High-voltage electric injury (HVEI) is associated with a high incidence of extremity compartment syndrome and of major amputation. The purpose of this study was to review our experience with HVEI and to attempt to develop predictors of the need for fasciotomy and amputation in patients with HVEI. The records of the 195 patients with HVEI who were admitted to a single burn center during a 19-year period were reviewed. Evidence for muscle necrosis, to include myoglobinuria and elevated creatine phosphokinase (CPK) levels, was noted. A total 187 patients (95.9%) survived to hospital discharge. A total of 56 underwent fasciotomy within 24 h of injury; 80 patients underwent an amputation during the hospitalization. Fasciotomy was predicted by presence of myoglobinuria with an overall accuracy of 72.8%. Amputation was predicted by a logistic model incorporating myoglobinuria, undergoing a previous fasciotomy, and age, with an overall accuracy of 73.3%. HVEI was associated with high amputation risk and a low rate of mortality in patients admitted to our burn center. Patients with gross myoglobinuria are at higher risk of requiring fasciotomy and/or amputation.

The link between the insecticide heptachlor epoxide, estradiol, and breast cancer

Given the suspected effects of estrogens on breast cancer, xenoestrogenic insecticides may be a risk factor. Studies of the weak xenoestrogen, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), have failed to demonstrate a causal relationship, though another estrogenic organochlorine insecticide, dieldrin, belonging to the cyclodiene family, has recently been linked to breast cancer. Other cyclodienes such as heptachlor epoxide (HE) and oxychlordane (OC) present in breast tissue have not been evaluated as rigorously, presumably due to their lower concentration and lower recovery using solvent extraction procedures. We used sparging extraction coupled with gas chromatography to determine the levels of HE, OC, and DDE in adipose tissue within breast biopsies in a series of 34 women evaluated for breast abnormality. Of the three insecticides tested, only HE (p=0.007) was positively associated with prevalence of breast cancer in the biopsies. In rapid, non-genomic studies using isolated human leukocytes, flow cytometric methods were used to measure HE-induced oxidants and DNA damage. These studies indicated that HE, at concentrations similar to those in breast biopsies, induced an inverted-U increase in intracellular oxidants and DNA strand breaks [both blocked by specific nitric oxide- (NO-) synthesis blockade withL: -NMMA] in human polymorphonuclear leukocytes (PMNs). HE-treated PMNs also induced damage to surrounding lymphocytes in mixed-leukocyte incubations (also inhibited by NO blockade). The HE-induced changes in NO were inhibited by 17beta-estradiol-(17beta-E2) receptor antagonists and were mimicked by similar concentrations of 17beta-E2. The addition of tumor necrosis factor-alpha (TNF-alpha) increased intracellular oxidants and DNA damage and shifted the responses to lower HE concentrations. This study, along with others, suggests that HE-induced NO production may contribute to initiation, promotion, and progression of cancer.

Xenoestrogens: do they lower survival after thermal injury?

The effect of hormone disruptors on human health is an area of recent concern. The authors measured heptachlor epoxide and oxychlordane--the body storage forms of estrogenic insecticides-in the sera of patients with major burns (i.e., 7 survivors and 10 age- and burn-size-matched nonsurvivors) on days 1, 3, 5, 7, and 11 after they had been burned, as well as in 12 age-matched normal controls. During the hypermetabolic phase, serum concentrations of heptachlor epoxide and oxychlordane were greater in nonsurvivors than in controls, and heptachlor epoxide concentrations in nonsurvivors exceeded those in survivors on postburn day 5. The postburn alterations in heptachlor epoxide and oxychlordane concentrations could not be accounted for by changes in concentrations of circulating lipid. These findings, which indicate that xenoestrogens are released from fat depots after thermal injury, suggest a possible contribution to mortality, especially in older patients.

Light contamination during the dark phase in "photoperiodically controlled" animal rooms: effect on tumor growth and metabolism in rats

Enhanced neoplastic growth and metabolism have been reported in animals maintained in a constant light (24L:0D) environment. Results from this laboratory indicate that tumor growth is directly dependent upon increased ambient blood concentrations of arachidonic and linoleic acids, particularly linoleic acid. Tumor linoleic acid utilization and production if its putative mitogenic metabolite, 13-hydroxyoctadecadienoic acid (13-HODE), are suppressed by the circadian neurohormone melatonin, the production of which is itself regulated by light in all mammals. This study was performed to determine whether minimal light contamination (0.2 lux) in an animal room during an otherwise normal dark phase may disrupt normal circadian production of melatonin and affect tumor growth and metabolism. Animals of groups I (12L:12D), II (12L:12-h light-contaminated dark phase), and III (24L:0D) had plasma total fatty acid (TFA), linoleic acid (LA), and melatonin concentrations measured prior to tumor implantation; groups I and II had daily cycles in plasma TFA and LA values, whereas group III had constant values throughout the day. The integrated mean TFA and LA values for the entire day were similar in all groups. Although group-I animals had a normal nocturnal surge of melatonin (127.0 pg/ml) at 2400 h, the nocturnal amplitude was suppressed in group-II animals (16.0 pg/ml); circadian variation in melatonin concentration was not seen in group-III animals (7.4 pg/ml). At 12 weeks of age, rats had the Morris hepatoma 7288CTC implanted as "tissue-isolated" tumors grown subcutaneously. Latency to onset of palpable tumor mass for groups I, II, and III was 11, 9, and 5 days respectively. Tumor growth rates were 0.72 +/- 0.09, 1.30 +/- 0.15, and 1.48 +/- 0.17 g/d (mean +/- SD, n = 6/group) in groups I, II, and III respectively. Arteriovenous difference measurements for TFA and LA across the tumors were 4.22 +/- 0.89 and 0.83 +/- 0.18 (group I), 8.26 +/- 0.66 and 1.64 +/- 0.13 (group II), and 7.10 +/- 0.78 and 1.50 +/- 0.16 (group III)/min/g, and groups II and III were significantly different from group I (P < 0.05). Tumor TFA and LA contents were 14.3 +/- 1.7 and 1.8 +/- 0.3 (group I), 52.9 +/- 5.5 and 7.9 +/- 0.8 (group II), and 106.0 +/- 12.0 and 18.5 +/- 2.4 (group III) micrograms/g and were significantly different from each other (P < 0.001). Production of 13-HODE by the hepatomas in groups I, II, and III was 35.5 +/- 6.3, 109.6 +/- 10.6, and 196.2 +/- 34.9 ng/min/g respectively, values which also were significantly different among groups (P < 0.001). The results indicate that minimal light contamination of only 0.2 lux during an otherwise normal dark phase inhibits host melatonin secretion and increases the rate of tumor growth and lipid uptake and metabolism. These data suggest that great care must be taken to prevent "light-leaks" in animal rooms during the dark phase of a diurnal cycle because such contamination may adversely affect the outcome of tumor growth investigations.

Sexual differences in 5'-deiodinase activity in the Harderian gland of Syrian hamsters and the effect of pinealectomy: regulation by androgens

Sexual differences on thyroxin 5'-deiodinase (5'-D) in the Harderian gland of Syrian hamsters were investigated. We compared the 24-h profile of 5'-D activity in male and female hamsters, observing a clear rhythm in males but not in females. Female values were always significantly higher than male ones. After pinealectomy day/night variations in male 5'-D activity at the time points studied were abolished, results that are in correlation with serum thyroid hormones. We also studied the regulation by androgen of the enzyme activity. Basal 5'-D activity increased in castrated males and levels fell when animals were implanted with testosterone or its product 5 alpha-dihydrotestosterone (DHT). Female 5'-D activity was also inhibited by androgens. As only the addition of DHT in the presence of epitestosterone, an inhibitor of the conversion of testosterone on DHT, in castrated males was able to decrease 5'-D activity to the control animal levels, we suggest a probable direct effect of DHT by itself.

Mg(2+)-dependent and Ca2+, Mg(2+)-dependent ATPase activities in the harderian gland of rodents: age and sex influences

Three experiments employing male and female Syrian hamsters (aged 1, 2, and 8-10 months), male Sprague-Dawley rats (aged 1, 2, and 10 months) and male C57B1 mice (aged 2, 7, 13, and 29 months) examined the effects of age and sex on Mg(2+)-dependent and Ca2+, Mg(2+)-dependent ATPase activity in the Harderian gland. Significant differences due to age and sex were observed in the hamsters and rats but not with age in mice. Generally, male hamsters had significantly higher Mg(2+)-dependent and Ca2+, Mg(2+)-dependent (exception at one timepoint) ATPase activity than did females. Age-matched male and female rats had similar values of Mg(2+)-dependent ATPase activity, but males had significantly higher Ca2+, Mg(2+)-dependent ATPase activity than females at 2 months of age.

Update on current therapeutic approaches in burns

Burn injury results in a rapid loss of intravascular volume as wound edema forms, which reduces the circulating blood volume and generates the need for fluid therapy to combat hypovolemia. Fluid resuscitation of a burn patient is usually carried out with isotonic, sodium- and chloride-containing fluids, such as lactated Ringer's solution. The initial 24 h resuscitation volume is based on the burn size and body weight of the patient. Following a successful resuscitation, the burn patient develops stereotypic neurohormonal and metabolic responses that, depending on the extent of injury, last for several weeks or months. Breathing of incomplete products of combustion by the fire victim produces inhalation injury, the incidence of which rises with increasing burn size and the severity of which is proportional to the duration of exposure. Systemic hypoxia from carbon monoxide toxicity causes early death; chemical airway injury increases mortality and predisposes to subsequent pneumonia that further reduces survival. The diagnosis of inhalation injury is made by bronchoscopy and/or xenon scan and therapy involves support of ventilation. Thermal destruction of the cutaneous mechanical barrier and the presence of nonviable avascular burn eschar as well as impairment of other host defenses render the burn patient susceptible to local as well as systemic infections. Care following resuscitation is focused on topical antimicrobial therapy, burn wound excision, and wound closure by grafting. Nutritional support and the prevention and control of infection are constant themes in burn patient management. A progressive improvement in general care of the acutely injured patient, prevention of shock, effective means of maintaining organ function, prevention and control of burn wound and other infections, and physiologically based metabolic support have significantly increased burn patient survival in recent decades.

Circadian rhythms in reproductive and thyroid hormones in gonadally regressed male hamsters exposed to natural autumn photoperiod and temperature conditions

Two groups of young adult male Syrian hamsters were kept in a vivarium at 22 degrees C and a light:dark cycle of 14.5:9.5 h (lights on 06.30 h; indoor) or in a naturally decreasing photoperiod and fluctuating ambient temperature conditions (outdoor) from October 1 (day length 11 h 50 min) to November 30 (day length 10 h 12 min). Representative animals from each group were killed at 3-hour intervals with additional time points near the onset of light. Weights of the paired gonads and accessory organs revealed that all of the animals kept outdoors and none of those kept indoors underwent reproductive regression. Significant circadian rhythms were observed in serum luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin (PRL), thyrotropin (TSH), thyroxine (T4), triiodothyronine (T3) and testosterone in indoor and outdoor-housed hamsters. The 24-hour acrophase in serum LH, TSH, T4 and T3 occurred between 13.00 and 16.00 h, while that of serum testosterone and PRL occurred between 18.00 and 20.00 h in indoor hamsters. Hormonal variables in which there was a significant alteration in the 24-hour acrophase of outdoor animals relative to that in the indoor animals included pituitary PRL and serum testosterone, PRL, FSH and TSH. Hamsters housed indoors had a significant rhythm in brown adipose tissue type-II 5'-deiodinase activity, but no rhythm was evident in this tissue in outdoor animals. The natural autumnal conditions depressed serum LH and testosterone around the clock, though the depression of serum FSH relative to indoor hamster values was best seen between 09.00 and 21.00 h and that for PRL between 15.00 and 24.00 h.(ABSTRACT TRUNCATED AT 250 WORDS)

New sensitive serum melatonin radioimmunoassay employing the Kennaway G280 antibody: Syrian hamster morning adrenergic response

A new procedure with the G280 antibody of Kennaway provides an assay for circulating melatonin (aMT) with a sample volume (200 microliters), an analytic (0.33 pg/ml) and functional (0.62-0.80 pg/ml) detectability, a 50% displacement dose (6.4 pg/ml), a Kd (0.657 pM), and measured circulating daytime levels lower than reported for previous procedures, and 100% assay recovery. The normal daytime range in adult human and Syrian hamster serum was 0.4-4 pg/ml. The pattern of fall of the nocturnal surge of Syrian hamster serum aMT near the time of lights-on was unaltered by extended darkness. Isoproterenol (ISO) injection 1 hr after lights-on, when aMT had reached daytime levels, raised serum and pineal aMT dramatically 2 hr postinjection. The same dose of ISO injected 4 hr into light produced only a small detectable increase. Novel extension of nocturnal darkness did not affect the responses to ISO. Thus, when they are allowed to occur at the usual time on a 10-hr dark schedule, both the fall from the nocturnal aMT surge and the subsequent loss of pineal beta-adrenergic responsiveness in this species occur endogenously (probably entrained) rather than from gating by acute effects of morning light. Changes in daytime serum aMT consistent with concomitant changes in the pineal can be measured with a sufficiently sensitive radioimmunoassay.

The renal effects of low-dose dopamine in thermally injured patients

The renal effects of low-dose dopamine (LDD) therapy in hyperdynamic thermally injured patients are unknown. We investigated the renal effects of LDD in ten burn patients (mean +/- SEM age and % total body surface burned: 30.2 +/- 3.3 years and 53.4% +/- 7%) and six controls (mean age; 20.2 +/- 0.5 years). Administration of LDD significantly increased glomerular filtration rate, effective renal plasma flow, sodium excretion, and urine flow in the controls and effective renal plasma flow, urine flow, heart rate, and cardiac index in the patients. The chronotropic effect of dopamine appears to be a principal contributor to the patients' increased effective renal plasma flow. Sodium excretion was increased by LDD only in the patients in whom the predopamine sodium excretion exceeded 5 mEq/h. Lack of a consistent natriuretic effect and the consistent chronotropic effect suggest that the routine use of low-dose dopamine in burn patients is unwarranted. The side effects that attend the desired response determine clinical use, i.e., the potential for blood flow redistribution and increased cardiac work demands must be balanced against increased renal plasma flow and natriuresis.

Serum luteinizing hormone, prolactin, and thyrotropin and their pituitary subunit mRNA levels during proestrus in the Syrian hamster

mRNA levels for alpha, luteinizing hormone beta (LH beta), and prolactin (Prl) were examined during the hamster estrous cycle, with sampling most frequent (1-hour intervals) on the afternoon of proestrus. These transcripts encode the peptide subunits for the pituitary hormones LH and Prl which are necessary for reproductive function. Serum hormone levels of LH and Prl, analyzed by 24-hour periodic regression, exhibited a 24-hour periodicity on proestrus characterized by a large surge peaking at about 18.00 h. Combining the data for non-proestrous days of the cycle disclosed a rhythm with similar timing for LH and Prl. Thyroid-stimulating hormone (TSH) and TSH beta RNA profiles during hamster proestrus are reported for the first time. Serum TSH exhibited a pronounced peak coincident with that of the other hormones on proestrus. Because of variations at other times on the day of proestrus, however, a 24-hour periodicity was not manifested by regressional analysis. Combined non-proestrous serum TSH data also revealed no consistently timed regressional 24-hour periodicity. During proestrus, pituitary mRNA values for alpha, LH beta, and Prl simultaneously exhibited a rise from the lowest to the highest of all proestrous values in the 3-5 h prior to the time of the pre-ovulatory peak of circulating hormone concentrations. RNA for TSH beta exhibited an earlier, broader peak on proestrus. Periodic regression indicated a significant 24-hour rhythm for alpha mRNA in data pooled from non-proestrous days (acrophase 05.00 h) and for TSH beta mRNA on proestrus (acrophase 04.54 h).(ABSTRACT TRUNCATED AT 250 WORDS)

Dissociation of blood volume and flow in regulation of salt and water balance in burn patients

The relationship between effective blood volume and related hormones in burn patients following resuscitation is not well understood. Previous reports have suggested that hormone secretion is altered by a resetting of neural control mechanisms. Serum and urine sodium, plasma renin activity, serum ADH, cardiac index, effective renal plasma flow, and total blood volume were measured in seven burn patients (mean age, total burn size, and postburn day: 32 years, 56%, and 9 days, respectively). The same values (with the exception of cardiac index and blood volume) were measured in 10 control patients (mean age, 24 years). The blood volume of patients was measured by 51chromium red blood cell (RBC) labeling and compared to normal predicted values based on body surface area and sex. Mean serum sodium and osmolality were 138 mmol/L (millimolar) and 286 mosm/kg, respectively, in both patients and control subjects. Mean +/- standard error of the mean total blood volume in the patients was low, 81% +/- 4% of predicted values. Cardiac index and renal plasma flow were significantly elevated. Plasma renin activity and antidiuretic hormone (ADH) levels were elevated and altered in the direction expected from blood volume measurements despite the findings of increased blood flow. Dissociation of organ flow and hormonal response suggests that simultaneous direct blood volume measurements are necessary to elucidate factors other than altered neural control settings to explain hormonal changes in the flow phase of injury. Depressed total blood volume appears to promote elevated ADH levels in burn patients following resuscitation. Whether there is an additional role of altered neural control settings remains to be established.

Harderian gland porphyrin, lysosomal and type II 5'-deiodinase rhythms in Sprague-Dawley and Fischer-344 rats kept under chronic long- or short-photoperiod conditions

1. Harderian gland porphyrin concentrations were 1.5-fold higher in Fischer-344 male rats than in Sprague-Dawley male rats and there were no differences due to exposure to LD 14:10 (LP) or LD 10:14 (SP) lighting conditions for 8 weeks in either strain. 2. 24-hr periodic regression analyses of porphyrin concentration detected a significant rhythm in both lighting conditions in both strains, with no differences in acrophase due to lighting conditions. 3. In both strains, porphyrin levels were highest in the late phase-early dark period and fell during the early part of the dark period. 4. Acid phosphatase activity did not vary with time (circadian rhythm), strain or photoperiodic lighting condition. 5. Circadian rhythms in beta-glucuronidase, alpha-mannosidase and hexosaminidase activity were present in some instances, but, probably due to the low amplitude to these rhythms, a consistent effect of strain or housing condition was not found. When 24-hr rhythms were observed in either strain, the acrophase occurred during the afternoon-early evening daylight period. 6. A significant effect of strain on mean values of type II 5'-deiodinase activity was noted in Fischer-344 rats. 7. Significant rhythms in type II 5'-deiodinase activity were found in both strains exposed to LD 10:14.

Pineal lysosomal enzyme circadian rhythms in male hamsters exposed to natural decreasing photoperiod and temperature conditions

Circadian rhythms in acid phosphatase (ACP), hexosaminidase (HEX) and beta-glucuronidase (RON) activity were studied in the pineal glands of adult male Syrian hamsters exposed to control (20 +/- 2 degrees C and 14:10 LD) conditions or to naturally decreasing autumn photoperiod and temperature conditions (outside) for 8 weeks. Testes and testosterone levels (p less than 0.001 in both instances) were severely depressed in animals exposed to natural environmental conditions illustrating that the treatment period was of sufficient length to produce pineal-mediated gonadal atrophy. Significant rhythms were found in all enzymes in the pineal glands of control and outside animals with the exception of HEX activity in the control animals. Significant acrophase differences in outside vs. control animals were noted in ACP (7.9 hr earlier, p less than 0.001) and RON (9.8 hr later, p less than 0.001). A significant drop in RON and HEX activity (p less than 0.01 in both instances) was noted in association with the acute lights exposure in the morning to which control animals were exposed. The around-the-clock mean value of each enzyme was significantly lower in outside vs. control hamsters. These results demonstrate that environmental changes which provoke the pineal-mediated depression in gonadal activity also alter the activity of and shift the circadian rhythmicity of lysosomal enzymes in the pineal itself.

Melatonin and porphyrin in the harderian glands of the Syrian hamster: circadian patterns and response to autumnal conditions

1. Adult male Syrian hamsters were killed at nine intervals during a 24 hr period in the autumn, after 2 months either indoors in controlled conditions or in natural outdoor conditions. 2. Harderian glands were taken for determination of N-acetyltransferase (NAT) and hydroxyindole-O-methyltransferase (HIOMT) activities and melatonin and porphyrin concentrations. 3. Mean 24 hr Harderian NAT and melatonin values were lower outside than inside. 4. Twenty-four hour melatonin rhythms were detected with similar daytime (afternoon) acrophases in both environmental conditions. 5. An NAT rhythm was seen only in animals kept inside, with a circadian maximum in the late dark phase. 6. Mean 24 hr HIOMT activity was slightly higher outdoors than indoors, and 24 hr rhythms were not detected in either condition. 7. Mean porphyrin concentrations were higher outdoors, with 24 hr rhythms detected in both conditions and a significantly earlier nocturnal circadian maximum outdoors.

Twenty-four hour variation of alpha 1-adrenergic receptors in the pineal gland of the male Syrian hamster

Specific binding of [125I]iodo-[beta-(4-hydroxyphenyl)-ethylaminomethyl]tetralone ([ 125I]HEAT) was used to assess alpha 1-adrenergic receptors on pineal gland membranes of male Syrian hamsters (Mesocricetus auratus) housed under a 14:10 h light-dark cycle (lights on at 06.00 h). Saturation experiments with pooled pineal membrane preparations showed the presence of alpha 1-adrenergic receptor sites (dissociation constant Kd approx. 0.1 nM). Analysis of 4 time points indicated no significant change in Kd, but significant (P less than 0.01) changes of receptor density (Bmax) with a minimum recorded at night. Binding of a constant amount of [125I]HEAT (200 pM) to pineal membranes at 8 time points exhibited a circadian variation (P less than 0.001) of receptor density with lowest values around midnight and highest levels during daytime.

Pineal lysosomal enzymes in the Syrian hamster: circadian rhythm and effects of castration or short photoperiod treatment

A circadian rhythm in acid phosphatase and hexosaminidase was found in adult male hamsters exposed to a long photoperiod (14:10 h light/dark [LD]; lights on 06.00 h) and killed at 08.00, 14.00, 20.00, 02.00, 04.00, 05.50 and 0.615 h. Hexosaminidase and beta-glucuronidase activity at 02.00, 04.00 and 05.50 h (values pooled for these times before lights on) were significantly elevated compared to enzyme activity at 06.15 and 08.00 h (pooled values after lights on), suggesting a fall in activity associated with lights on. Hypogonadism was induced in female Syrian hamsters by exposure to a short photoperiod (10:14 h LD) until a majority of them were vaginally acyclic. Pineal lysosomal enzyme activities (acid phosphatase, beta-glucuronidase, hexosaminidase, alpha-arabinosidase and beta-galactosidase) were significantly elevated in short photoperiod-exposed animals compared to animals in 14:10 LD, when measured near the middle of the light phase. In the third experiment, castrated animals were used to determine if lowered androgen levels might also affect pineal lysosomal enzyme activity. The results indicated that light phase beta-glucuronidase, hexosaminidase and beta-glucosidase activities were lower in castrated males compared to their intact controls. In summary, these results demonstrate that (1) lysosomal enzyme activity is present in the Syrian hamster pineal, (2) changes can be observed which suggest involvement of this activity in pineal function and, (3) a circadian rhythm in enzyme activity is present with peak activity occurring during the night. In the short photoperiod and castration experiments, the changes in lysosomal enzyme activity could reflect either a hormonal manipulation or a change in circadian regulation of enzyme activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal consequences of subcutaneous 6-methoxy-2-benzoxazolinone pellets or injections in prepubertal male and female rats

Prepubertal 27-day-old female rats maintained in a 14L:10D cycle (lights on 06:00 h) were injected s.c. at 13:00 h with saline or 2, 20 or 200 micrograms 6-methoxy-2-benzoxazolinone (6-MBOA) and killed 25-27 h later. No significant differences in body, pituitary or ovarian weight were noted. Differences in uterine weight (mg/100 g body weight) and in circulating free thyroxine index fit the pattern of a reduction after the lower doses with reversal of this effect after the highest dose. A dose-related rise in plasma prolactin concentration was accompanied by a significant increase in pituitary prolactin at the lowest (2 micrograms) dose. When 27-day-old prepubertal male and female rats maintained in a 14L:10D cycle were implanted with a beeswax pellet or a wax pellet that contained 100 micrograms or 1 mg 6-MBOA and killed 3 days later between 14:00 and 16:00 h, body and absolute ventral prostate weights (but not weights of other accessory organs, testes or relative ventral prostate weights) in males were lower. Pituitary (but not plasma) prolactin concentrations were higher after the lower dose compared to the controls; pituitary and plasma values of LH and FSH were unchanged. In females, reproductive variables were unchanged except for a reduction of pituitary prolactin after the 1 mg dose. Triiodothyronine and its free index were elevated after the higher dose in males and the lower dose in females. The free thyroxine index appeared raised after the larger dose only in males.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated environmental temperature alters the responses of the reproductive and thyroid axes of female Syrian hamsters to afternoon melatonin injections

Female Syrian hamsters were kept in a light (14:10 h light:dark cycle, lights on 0600 h)- and temperature (22 or 30 degrees C)-controlled room; some groups were treated with an afternoon s.c. injection of melatonin (6.25, 12.5, or 25 micrograms/day) for 11 or 14 weeks. The melatonin-induced suppression of the reproductive system in hamsters maintained at 22 degrees C (as measured by vaginal cycles, uterine weights, ovarian histology, and plasma and pituitary prolactin levels) was delayed if hamsters were kept at 30 degrees C. The dose-related depression of thyroxine (T4) after melatonin injections for 14 weeks in 22 degrees C was not seen at 30 degrees C. Rather, the depression of plasma T4 and triiodothyronine (T3) seen at the end of 11 or 14 weeks of exposure to 30 degrees C without melatonin injections (vs. control levels at 22 degrees C) was offset by melatonin injections, raising T4 and T3 particularly at the lower doses. In contrast, there was no consistent effect of higher temperature alone on reproductive variables. The interactive effects of temperature and melatonin on the reproductive and thyroidal systems in female hamsters are apparently complex and probably provide a fine-tuning mechanism for the environmental control of endocrine physiology.

Swimming depresses nighttime melatonin content without changing N-acetyltransferase activity in the rat pineal gland

Recently, it was shown that a 1.5-ml subcutaneous saline injection depressed N-acetyltransferase (NAT) activity and melatonin content in the rat pineal gland at night. The present studies were undertaken to determine if another perturbation, swimming, could duplicate this response. Rats swam at 23.10 h (lights out at 20.00 h) for 10 min and were killed 15 and 30 min after the unset of swimming. Pineal NAT activity was found to be unaffected while melatonin content was depressed dramatically. Hydroxyindole-O-methyltransferase (HIOMT) activity as well as the content of serotonin (5HT), 5-hydroxytryptophan (5HTP) and 5-hydroxyindoleacetic acid (5HIAA) were not changed by this treatment. In a second study, pineal melatonin again was depressed without a concomitant drop in NAT activity. Mean serum melatonin at 15 min after onset of swimming was increased although the rise was not statistically significant. In the final study, it was found that NAT activity was slightly increased in intact rats and unchanged in adrenalectomized rats at 7 min after swimming onset. At 15 min both intact and adrenalectomized animals had NAT activity values similar to those of controls. Pineal melatonin content in intact and adrenalectomized rats plummeted to 50% of control values at 7 min and fell further to 25% at 15 min. While the rate of melatonin synthesis was not directly measured, lack of change in the activities of the enzymes involved in melatonin synthesis and the contents of two melatonin precursors suggests that swimming depresses pineal melatonin content by enhancing melatonin efflux from the gland.

Nyctohemeral rhythms of gonadal, thyroid and pineal function in the hyperprolactinemic male rat

In young adult male rats bearing a donor anterior pituitary gland grafted for 3 weeks under a kidney capsule, serum prolactin (PRL) concentrations were elevated and exhibited a rhythm with the highest values in the light phase. Serum PRL in control animals did not exhibit a significant rhythm. Eutopic pituitary PRL content, manifesting a biphasic (12-hr) rhythm with crests during the day and night in controls, exhibited a similar pattern in grafted rats though an overall reduction in pituitary PRL content was seen in the grafted animals. Neither the normal biphasic serum testosterone rhythm nor the normal 24-hr rhythm (nocturnal surge) of pineal N-acetyltransferase activity and melatonin content were altered in the hyperprolactinemic rats. Serum thyroxine (T4) and triiodothyronine (T3) and their free indices (FT4I, FT3I) and serum thyrotropin (TSH) were highest during the day in controls and grafted rats and a 12-hr rhythmic component was detected in data for these variables. In the grafted animals, the 12-hr component was reflected in an additional peak at night detectable by testing of means. The overall serum T4, FT4I, and TSH levels were lower in grafted rats though overall T3 and FT3I levels did not differ between grafted and controls. T3 uptake (T3U) values were similar between controls and grafted rats, in both cases exhibiting a fall during the night. Changes in serum thyronines could not be explained by changes in serum binding as assessed by the T3U, and thus may represent changes in thyroidal secretion of T4.(ABSTRACT TRUNCATED AT 250 WORDS)

Elevated daytime rat pineal and serum melatonin levels induced by isoproterenol are depressed by swimming

Isoproterenol (1 mg/kg) was subcutaneously injected into adult male rats during the day to stimulate pineal N-acetyltransferase (NAT) activity and pineal and serum melatonin levels. Two hours after isoproterenol administration when levels of each of these variables had increased significantly, the experimental animals swam for 10 min in 22 degrees C water. At 15 min after swimming onset, pineal and serum melatonin levels were highly significantly depressed compared to those in control animals that did not swim. The high NAT level was not influenced by swimming. In a second study, isoproterenol injected rats swam for either 1, 3, 6 or 10 min and were sampled 15 min after the onset of swimming. The reduction in the elevated pineal melatonin in these animals was correlated with the length of the swim, i.e., as the duration of swim increased the percent reduction in pineal melatonin also increased. Neither pineal NAT nor hydroxyindole-O-methyltransferase (HIOMT) activities were influenced by swimming. The results suggest that elevated pineal and serum melatonin induced by isoproterenol can be depressed with no effect on the activity of the enzymes which convert serotonin to melatonin.

Characterization of type-II thyroxine 5'-deiodinase activity in rat Harderian gland

Thyroxine 5'-deiodinase activity was studied in male rat Harderian gland homogenates. The reaction rate was proportional to the tissue content in the homogenate and dependent on pH, with an optimum pH of 7.0, and temperature, between 4-37 degrees C. 5'-deiodinase activity was increased by dithiothreitol (DTT) in a dose-dependent manner, and inhibited moderately by propylthiouracil (PTU) and strongly by iopanoic acid (IA). Thyroidectomy enhanced the enzymatic activity (30-fold above the control value) but this increase is totally prevented by the in vivo iopanoic acid treatment. Thyroxine 5'-deiodinase activity was also dependent on T4 concentration (Km = 3.3 nM; Vmax = 10 fmol 125I-released/mg protein/h) and exhibited a nyctohemeral rhythmicity with a maximal activity at 03.00 h (4-fold above basal values) and minimal activity between 12.00-21.00 h.

Pineal and retinal lysosomal enzyme rhythms

Pineal glands and the neurosensory portion of the retinae of adult male rats adapted to a 24-h cycle with lights on from 06.00 to 20.00 h were collected at 9 timepoints during the cycle. Significant rhythms in both pineal and retinal hexosaminidase, beta-glucuronidase, acid phosphatase and beta-glucosidase were observed. For each enzyme, pineals had greater overall activity per unit amount of protein than did retinae. All 4 significantly rhythmic pineal enzymes peaked within 30 min of each other (18.30-19.00 h) whereas the retinal enzymes peaked some 6 h earlier, between 11.30 and 13.45 h. To our knowledge, this is the first report demonstrating 24-h rhythms in lysosomal enzymes in the pineal gland and retina. Since the acrophases (peak times) of these enzymes within each tissue are tightly synchronized yet different between tissues, lysosomes may play unique roles in the physiology of different structures in the photoneuroendocrine system with respect to time in the light-dark cycle.

Splenic hypertrophy and extramedullary hematopoiesis induced in male Syrian hamsters by short photoperiod or melatonin injections and reversed by melatonin pellets or pinealectomy

Adult male Syrian hamsters either placed in a short photoperiod alone or kept in a long photoperiod and given daily afternoon injections of the pineal indole melatonin (25 micrograms) exhibited splenic hypertrophy and extramedullary hematopoiesis in addition to a marked regression in testicular weight. The testicular regression as well as the changes in spleen weight and histology could be prevented if the animals in short photoperiod were either pinealectomized or implanted subcutaneously with a pellet containing 1 mg melatonin. Female Syrian hamsters given afternoon injections of melatonin for 7 or 12 weeks had ovaries devoid of corpora lutea; additionally, these animals had reduced relative spleen weights compared to the control animals. In conclusion, it is apparent that spleen weight varies with the functional status of the gonads. Splenic hypertrophy accompanied by pineal-induced testicular regression in males may be related to splenic extramedullary hematopoiesis.

Norepinephrine or isoproterenol stimulation of pineal N-acetyltransferase activity and melatonin content in the Syrian hamster is restricted to the second half of the daily dark phase

Seven experiments were performed to investigate the sensitivity of the hamster pineal gland to exogenously administered norepinephrine (NE). In these studies NE (1 mg/kg) administration was preceded (10 min earlier) by the injection of the catecholamine uptake inhibitor desmethylimipramine (DMI; 5 mg/kg). When DMI and NE were given at night, the hamsters were exposed to light to depress pineal N-acetyltransferase activity and melatonin values to low levels; the drugs were then given 20 (DMI) and 30 (NE) min later, and the subsequent changes in pineal N-acetyltransferase and melatonin were monitored. The combination of DMI and NE administration anytime during the normal light period or during the first 4 h of the normal dark period failed to stimulate either pineal N-acetyltransferase activity or melatonin levels. Conversely, DMI followed by NE (injected either intraperitoneally or subcutaneously) in the second half of the dark phase typically stimulated pineal melatonin production. Likewise, the NE agonist isoproterenol promoted pineal melatonin production only in the latter half of the dark phase. If hamsters were exposed to continual light at night or if they were superior cervical ganglionectomized, a procedure which sympathetically denervates the pineal gland, the stimulatory effect of NE on melatonin production was significantly suppressed. Thus, the hamster pineal gland is sensitive to NE only during the latter half of the normal dark period and both darkness and an intact sympathetic innervation to the pineal gland are required for the gland to develop maximal sensitivity to the catecholamine. Also, the hamster pineal seems not to exhibit a supersensitivity response to NE following a period of reduced exposure to the catecholamine.(ABSTRACT TRUNCATED AT 250 WORDS)

The Syrian hamster pineal gland responds to isoproterenol in vivo at night

Failure of isoproterenol (ISO) injections to raise pineal melatonin content has generated doubt about beta-adrenergic control of the melatonin rhythm in Syrian hamsters. However, the effect of ISO injected at night after light-induced reduction of pineal melatonin has not been reported. In this study, light exposure began at 6 1/4 h into one (normally 10-h) dark phase. The hamsters were injected with either ISO (1 mg/kg) or vehicle 15 min later when pineal melatonin content was low. Light exposure continued. Two h after ISO but not vehicle injection, pineal melatonin content rose more than six-fold. In other animals injected at the end of the usual light phase then kept in light for 2 h, pineal melatonin was equally low after ISO or vehicle injection. The Syrian hamster pineal gland can respond in vivo to a beta-adrenergic agonist injected at the physiologically relevant time of the normal nocturnal melatonin surge. This finding, taken together with the previously reported inhibition of the endogenous nocturnal melatonin surge with a beta-blocking drug, suggests that a beta-adrenergic mechanism controls the hamster pineal melatonin rhythm.

Injections of alpha-melanocyte stimulating hormone affect pineal serotonin, melatonin and N-acetyltransferase activity

To determine if exogenously administered alpha-melanocyte stimulating hormone (alpha-MSH) affects nighttime pineal N-acetyltransferase activity, pineal levels of 5-hydroxytryptophan, serotonin and melatonin, and plasma prolactin levels, adult male hamsters were injected at 1900 hr (lights out 2000-0600 hr) with two doses of the peptide and killed at 0300 hr. The low dose of alpha-MSH (200 ng) produced a significant fall in pineal serotonin, pineal NAT activity and plasma prolactin values. The high dose of the peptide (20 micrograms) increased circulating prolactin titers and pineal serotonin levels and caused a concomitant decrease in pineal melatonin levels.

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.

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.

Influence of psoralen on NAT activity and melatonin levels in rat pineal gland during the daily period of darkness

A single injection of either 5 or 10 mg/kg 8-methoxypsoralen (8-MOP) was given intraperitoneally to male rats at the end of the 14 h light phase (at 2000 h). Two h later (at 2200 h), when the normal nocturnal surge of N-acetyltransferase (NAT) activity and melatonin content in the pineal gland had begun in vehicle-injected controls, mean pineal NAT after the 10 mg/kg 8-MOP was 1.8-fold higher than that after vehicle, though pineal melatonin content did not differ between vehicle- and drug-injected rats. By 4 h into the dark period (at 2400 h), the NAT activity in both 8-MOP injected groups of rats was greater than that in vehicle treated animals; again, however, 8-MOP treatment did not influence the pineal melatonin content. At 0200 h (6 h into the dark period), the difference between the NAT activity in pineals of rats treated with 5 mg/kg 8-MOP and the vehicle was not statistically significant, but the animals that received 10 mg/kg drug still had statistically elevated levels of the serotonin acetylating enzyme. At 0200 h the pineal melatonin levels were equivalent among the three treatment groups. Rats given 5mg/kg 8-MOP always had NAT values intermediate between those of rats injected with vehicle and those that received 10 mg/kg 8-MOP suggesting that the NAT response to the drug was dose related. These results show that the pineal response to psoralen involves an elevation of NAT activity without a commensurate change in the melatonin content of the gland.

Reproductive effects of 6-chloromelatonin implants and/or injections in male and female Syrian hamsters (Mesocricetus auratus)

Adult female hamsters were injected each afternoon for 9 weeks with 2.5, 15 or 25 micrograms of melatonin or 6-chloromelatonin (CM). Each drug resulted in a significant dose-related depression in uterine, ovarian and anterior pituitary gland weights. Additionally, plasma and pituitary concentrations of prolactin fell with increasing dose of either indole whereas pituitary levels of LH and FSH were positively correlated with dose. There was no difference in effectiveness between the two drugs. Adult male hamsters treated for 10 weeks with daily afternoon injections of melatonin and a blank beeswax pellet had depressed testicular and accessory organ weights and plasma and pituitary concentrations of prolactin. Implantation of a 1 mg melatonin or CM beeswax pellet in hamsters concurrently receiving daily afternoon injections of melatonin prevented the organ weight and hormonal changes, except for plasma prolactin. Adult male hamsters treated for 10 weeks with daily afternoon injections of CM and a blank beeswax pellet had depressed reproductive organ weights and pituitary and plasma concentrations of prolactin; this depression in hormonal values and organ weights was totally prevented if the CM-injected hamsters were also bearing a beeswax-melatonin pellet. In conclusion, 6-chloromelatonin is as effective as melatonin with regards to antigonadotrophic and counter-antigonadotrophic effects in male and female Syrian hamsters.

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.

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.

Serum melatonin after a single aqueous subcutaneous injection in Syrian hamsters

A single injection of 25 micrograms melatonin was given subcutaneously in 0.1 ml saline either at 3 h into the light phase (morning) in female Syrian hamsters or at 1 h before the beginning of the dark phase (evening) in males (L/D 14/10 h). In both cases, the maximal mean serum values seen at 20 min after injection (50 ng/ml) were more than 1,000 times the normal nocturnal melatonin concentration. By 1 h after injection, serum melatonin had fallen to 10% (morning) or 4% (evening) of the respective 20-min value. The average half-times for plasma concentration during the second hour after injection were 14 min in the morning and 13 min in the evening. After either morning or evening injection, serum melatonin reached normal daytime concentration between 2 and 4 h after injection.

Pineal dependence of the Syrian hamster's nocturnal serum melatonin surge

The usual nocturnal surge of pineal melatonin content was blocked by bilateral superior cervical ganglionectomy in male Syrian hamsters. Ganglionectomy and pinealectomy each prevented the nocturnal rise of serum melatonin concentration seen in control animals. The normal nocturnal surge of circulating melatonin in this species appears to depend on the pineal gland and its sympathetic innervation.

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.

Reduced serum T4 and T3 and their altered serum binding after burn injury in rats

Total T4 and T3 concentrations are often suppressed in burned patients. To investigate the significance of such changes, we have characterized serum T4 and T3 after full-thickness scald burns (60% body surface under anesthesia) of 270-gm male Sprague-Dawley rats housed in a light:dark cycle of 14:10 hr. Groups (N = 9-15) of BURN, SHAM (anesthesia, fur clipped, no burn) and CON (controls) were sacrificed on postburn days 8 and 14. T4 and T3 (radioimmunoassay), free indices (FT4I and FT3I = respective total T4 or T3 X in vitro charcoal T3 uptake, T3U), and free concentrations (FT4 and FT3 = total T4 or T3 X respective equilibrium dialyzable fraction, T4DF or T3DF) were not different between CON and SHAM. Compared to SHAM, mean T4 and FT4I (by about 48% of respective SHAM means on both days), TT3 (by 36, 43%), and FT3I (by 38, 45%) (days 8, 14) were suppressed in BURN (all p less than 0.001). T4DF (both days) and T3DF (day 14) were significantly elevated in BURN, demonstrating a deficit in serum binding, but T3U was not. FT4 (by 26, 22%) and FT3 (by 33, 34%) (day 8, 14) were significantly lower in BURN. On either day, covariance analyses (BURN vs. combined CON + SHAM) correlated FT4I or FT3I with respective FT4 or FT3 (all p less than 0.001, slopes not different in BURN vs. CON + SHAM), but the lower FT4I and FT3I in BURN significantly overestimated (all p less than 0.001) the depression of respective FT4 and FT3 in BURN.(ABSTRACT TRUNCATED AT 250 WORDS)

Hormonal changes in burned hamsters

Burned male Syrian hamsters (burn size 23% of body surface) exhibited reduced total (T4) and free (FT4) serum concentrations, a defect in T4 binding to serum proteins manifested by the T4 dialyzable fraction but not the in vitro T3 charcoal uptake, and reduced serum testosterone concentration. These changes are similar to those noted previously in burned humans. Unlike such patients, burned hamsters did not exhibit reduced serum T3 nor elevated rT3 concentrations in a reproducible manner. Pinealectomy performed before burning in hamsters did not prevent the burn-induced depression in serum T4 and testosterone.

Nonthyroidal control of metabolism after burn injury: possible role of glucagon

The endocrine basis for control of metabolism in nonthyroidal illness is not yet understood. Burn injury is associated with reduced serum concentrations of thyroid hormones and with resting hypermetabolism. One index of severity is total burn size (TBS, % body surface). After overnight fasting and recumbency, resting metabolic rate (MR, O2 consumption) was measured weekly and plasma was sampled for determination of glucose, total cholesterol, triglycerides, insulin, glucagon, somatostatin, growth hormone, norepinephrine, epinephrine, and cortisol in 28 burned men, 17-23 years old, TBS 2%-85%, including 8 controls with minimal injury (TBS less than or equal to 7.5%). MR was elevated in proportion to burn size mainly in the first week then declined toward normal. Growth hormone was not changed. Two multiple regression analyses (validated by random partitioning of data) determined which plasma variables independently reflected residual variation in MR: without TBS entered as a variable, high MR was associated with elevated glucose, cortisol, and glucagon, and low cholesterol (cumulative r2 = 0.79); with TBS entered, high MR was associated with greater TBS, elevated norepinephrine, and again high glucagon and low cholesterol (r2 = 0.81). Resting metabolism after burn injury is controlled not by the thyroid but may be controlled by a set of antiinsulin hormones that does not include growth hormone, but possibly includes glucagon.

Alterations of mental status and thyroid hormones after thermal injury

In 16 burn patients, mean values for serum T4 and T3, their T3 uptake-derived free indices (FT4I and FT3I) and dialysis-derived free concentrations (FT4 and FT3) were depressed (all P less than 0.001) compared to respective means in 13 normal subjects. In the patients, the free hormone indices were relatively more depressed below control values than were the free hormone concentrations. However, within the group of burn patients, variation in FT4I reflected that of FT4 (r = 0.91), and variation in FT3I reflected that of FT3 (r = 0.93). We then studied serum T4, T3, and their free indices in 134 patients (burn size, 6-96% of the skin area), including 45 nonsurvivors, none of whom received steroid, dopamine, or iodine treatment. At each sampling, the level of obtundation (LO) was determined on a 6-point scale from normal to deep coma. Whereas initially low mean FT4I values rose in survivors, they remained lower in nonsurvivors than in survivors until death in the nonsurvivors. In nonsurvivors, mean LO worsened in the first week and remained worse than that in survivors until death. Multiple regression analyses showed that for a given age or burn size, nonsurvival was better correlated with lower T4 or FT4I than with T3 or FT3I, but was even more closely correlated with worse LO (P less than 0.001). Exclusion of data obtained within 24 h of narcotic or tranquilizer doses did not weaken the relationship of nonsurvival with LO and FT4I. Nonsurvival after burn injury was associated with reduced T4, FT4I, and mental status for up to weeks before death, this association being independent of treatment with drugs acting on mental status or thyroid function.

Pineal function in burns: melatonin is not a marker for general sympathetic activity

Burn injury in humans or rats is a model of marked elevation of general sympathetic activity for weeks, manifested in part by increased heart rate, metabolic rate, core temperature, and plasma and urinary catecholamines. Plasma melatonin was sampled at 2-h intervals for 24 h in 9 control subjects and 11 patients with severe burn injury. Daytime melatonin was not different between the groups, but nighttime values were significantly lower in the burn patients. A nocturnal surge was still significant in the patients. Resting heart rate and rectal temperature were elevated in the burn patients. In male Sprague-Dawley rats, pineal melatonin content did not differ between controls and those with an experimental burn at 4 h into the light phase nor during the nocturnal surge. Male Syrian hamsters with burns had lower daytime pineal melatonin content than did controls, but the nocturnal surge in pineal melatonin was not significantly different between groups, nor was daytime morning serum melatonin. Sympathetic activity appears partitioned, with that controlling melatonin (nocturnal surge) regulated independently. In agreement with our previous findings in other models, melatonin is not a marker for general sympathetic activity, even following severe burn injury.

Pineal-induced depression of free thyroxine in Syrian hamsters

Blind hamsters had no alteration of the dialyzable fraction of serum thyroxine (T4) but had depressed total and free T4 concentrations compared to controls. Prevention of the effects of blinding by pinealectomy indicates pineal influence on circulating free T4 concentration. Parallel changes in free T4 and the free T4 index indicate adequacy of the index in representing pineal-induced changes in free T4.

Effects of injections and/or chronic implants of melatonin and 5-methoxytryptamine on plasma thyroid hormones in male and female Syrian hamsters

Plasma thyroid hormone concentrations in male and female Syrian hamsters were evaluated in five experiments after two pineal indoles, melatonin (MEL) and 5-methoxytryptamine (5-MT), were administered as chronic s.c. implants and/or daily afternoon injections. Circulating concentrations of thyroxine (T4), ordinarily maintained by the long photoperiod (LD 14:10), were inhibited by daily afternoon injections of 25 micrograms MEL but not 5-MT in male (experiment 1) and female (experiment 2) Syrian hamsters. The suppressive effect of MEL injections on T4 concentration in the long photoperiod was prevented in both sexes by a s.c. beeswax pellet containing either 1 mg MEL or 5-MT. In the third experiment, various doses of MEL or 5-MT were injected each afternoon for 12 weeks to compare the effectiveness of these two indoles in reducing T4 concentrations in hamsters maintained in the long photoperiod. Only the highest dose (200 micrograms) of 5-MT effectively suppressed T4 concentrations whereas all doses of MEL (greater than or equal to 5 micrograms) significantly reduced plasma T4. MEL or 5-MT (1-1,000 micrograms) were implanted in beeswax pellets in male hamsters exposed to short photoperiod (LD 10:14) to determine if either indole could prevent the short photoperiod-induced suppression of T4 (experiments 4 and 5). Regression and covariance analyses showed a significant log dose-related elevation of T4 in these hamsters, indicating equal potency of MEL and 5-MT in preventing the short photoperiod-induced suppression of T4. 5-MT given by either injection or implantation raised plasma triiodothyronine (T3) in female (experiment 2) but not in male hamsters.(ABSTRACT TRUNCATED AT 250 WORDS)

Replacement therapy with modified immunoglobulin G in burn patients: preliminary kinetic studies

Suppression of serum immunoglobulin G for periods ranging from days to weeks following thermal injury may enhance the risk of infection in burn patients. In an initial trial, we attempted to determine whether intravenous pulses of Immunoglobulin G (IgG) will establish and maintain normal serum IgG concentrations in this interval. The levels of endogeneous serum IgG in eight control patients, mean total burn size 45 percent body surface area (no IgG infusions), were measured by radial immunodiffusion on various postburn days. Commercially available reduced alkylated IgG (5 percent Gamimune, Cutter Biological, Berkeley, California) was infused in doses of 500 mg/kg twice per week in four patients (total burn size 32 percent) and once per week in five patients (total burn size 47 percent), beginning during the first postburn week. Circulating IgG was measured prior to each infusion and at three postinfusion times: (1) 15 minutes (peak), (2) one day, and (3) either day 3, 4, or 6. Surgery or blood transfusions prior to one of these time points invalidated kinetic analysis of some infusions. Exponential two-point decay constants for total serum IgG after each of 24 infusions were calculated separately for early (day 0-1) and later (day 1-3 or 1-4) postinfusion intervals and assessed by stepwise regression analysis to determine sources of variation in decay. Early decay was seen to be faster with larger burn size after accounting for variation of decay with preinfusion and peak IgG values. Later decay was not related to burn size. Maltose, a constituent of the IgG preparation, was detectable in serum for only four to eight hours after each infusion and may have contributed to a 20 percent increase in total serum glucose between four and eight hours postinfusion. Mean serum IgG in patients given infusions twice weekly was in the normal range after one infusion, about a week earlier than in untreated patients. Such infusions maintained normal IgG levels.