Changes in prolactin, cortisol and testosterone concentrations during queen succession in a colony of naked mole-rats (Heterocephalus glaber): a case study

Colonies of naked mole-rats (Heterocephalus glaber, NMRs) are characterised by an extreme skew in lifetime reproductive success with only one female and one to three male consorts in a colony. The rest of the individuals in a colony are reproductively suppressed and much research has been focussed on elucidating that mechanism. The dopamine system and prolactin have recently been implicated in the suppression of reproduction of subordinate NMRs. To investigate the changes in prolactin during the removal of an aged reproductive female (queen) and succession of a new queen, blood samples were collected during different stages of queen removal: before queen removal, after separation, but in olfactory contact with the queen and after the total removal of the queen. Further, plasma cortisol and testosterone concentrations were determined. The colony appeared unstable prior to queen removal as indicated by high concentrations of cortisol and testosterone and lack of successful breeding. A new queen succeeded the old queen whilst she was still in olfactory contact. The time preceding queen succession was characterised by high levels of aggression, the death of a number of individuals, high cortisol and testosterone and low prolactin concentrations. Once the older queen was removed entirely and the new queen had given birth, prolactin concentrations increased and cortisol and testosterone concentrations decreased in subordinate NMRs. The results suggest that low prolactin levels are associated with low reproductive suppression during times of colony instability due to the removal or death of a queen.

Reversal of catabolism by beta-blockade after severe burns

BACKGROUND

The catecholamine-mediated hypermetabolic response to severe burns causes increased energy expenditure and muscle-protein catabolism. We hypothesized that blockade of beta-adrenergic stimulation with propranolol would decrease resting energy expenditure and muscle catabolism in patients with severe burns.

METHODS

Twenty-five children with acute and severe burns (more than 40 percent of total body-surface area) were studied in a randomized trial. Thirteen received oral propranolol for at least two weeks, and 12 served as untreated controls. The dose of propranolol was adjusted to decrease the resting heart rate by 20 percent from each patient's base-line value. Resting energy expenditure and skeletal-muscle protein kinetics were measured before and after two weeks of beta-blockade (or no therapy, in controls). Body composition was measured serially throughout hospitalization.

RESULTS

Patients in the control group and the propranolol group were similar with respect to age, weight, percentage of total body-surface area burned, percentage of body-surface area with third-degree burns, and length of time from injury to metabolic study. Beta-blockade decreased the heart rates and resting energy expenditure in the propranolol group, both as compared with the base-line values (P<0.001 and P=0.01, respectively) and as compared with the values in the control group (P=0.03 and P=0.001, respectively). The net muscle-protein balance increased by 82 percent over base-line values in the propranolol group (P=0.002), whereas it decreased by 27 percent in the control group (P not significant). The fat-free mass, as measured by whole-body potassium scanning, did not change substantially in the propranolol group, whereas it decreased by a mean (+/-SE) of 9+/-2 percent in the control group (P=0.003).

CONCLUSIONS

In children with burns, treatment with propranolol during hospitalization attenuates hypermetabolism and reverses muscle-protein catabolism.

Determinants of blood loss during primary burn excision

BACKGROUND

Excisional therapy for burn wounds is frequently associated with large operative blood losses. Our objective was to identify patient and operative factors that affect surgical blood loss and determine strategies to minimize hemorrhage.

METHODS

Data from 92 consecutive pediatric patients with severe burns (>40% total body surface area) were evaluated. Patient demographics, burn characteristics, operative factors, and clinical course variables were correlated with blood loss. Blood loss at the time of initial total burn excision was determined by a standardized, previously validated method. Data were analyzed sequentially and cumulatively through univariate and cross-sectional multivariate linear regression.

RESULTS

Demographic factors that correlated with increased blood loss were older age, male sex, and larger body size. Area of full-thickness (third-degree) burn correlated with blood loss, whereas total burn size did not. High wound bacteria counts (derived from quantitative tissue cultures), total wound area excised, and operative time were the strongest predictors of the volume of operative hemorrhage. Blood loss increased with delay to primary burn excision at a maximum at 5 to 12 days after burn injury.

CONCLUSIONS

Early definitive surgical therapy before extensive bacterial colonization and rapid operative excision is a strategy that may decrease operative hemorrhage and transfusion requirements during burn surgical procedures.

Efficacy of a high-carbohydrate diet in catabolic illness

OBJECTIVE

To determine within the setting of isocaloric, isonitrogenous enteral diets whether a diet that supplies most of its calories from fat or carbohydrate would be most beneficial at limiting muscle protein wasting in catabolic illness.

DESIGN

Prospective, randomized, crossover trial.

SETTING

Academic pediatric burn unit in tertiary medical center.

PATIENTS

Fourteen severely burned (>40% total body surface area) children underwent systemic metabolic and cross-leg muscle protein kinetic studies.

INTERVENTIONS

All were treated clinically in a similar manner, including early excision and grafting, antimicrobial therapy, and isocaloric, isonitrogenous enteral nutritional support. Subjects randomly received either a high-carbohydrate enteral diet (3% fat, 82% carbohydrate, 15% protein), or a high-fat enteral diet (44% fat, 42% carbohydrates, 14% protein) for 1 week and then crossed over to the other diet for a second week.

MEASUREMENTS AND MAIN RESULTS

On day 5 of each diet, muscle protein kinetics were determined from femoral arterial and venous blood samples during a primed-constant d5-phenylalanine infusion. Indirect calorimetry was used to determine systemic resting energy expenditure and respiratory quotient. The seven boys and seven girls were 7.1 +/- 1.1 (mean +/- sem) years old and suffered burns over 65 +/- 4% of their bodies, with 52 +/- 6% being third-degree burns. Muscle protein degradation markedly decreased (p <.01) with administration of the high-carbohydrate diet. Protein synthesis was unaltered. Endogenous insulin concentrations increased during the high-carbohydrate feeding period. No differences in energy expenditure were seen between study diets.

CONCLUSIONS

In severely burned pediatric patients, enteral nutrition supplied predominantly as carbohydrate rather than fat improves the net balance of skeletal muscle protein across the leg. This is attributable to decreased protein breakdown, suggesting a protein-sparing effect of high-carbohydrate feedings.

Attenuation of posttraumatic muscle catabolism and osteopenia by long-term growth hormone therapy

OBJECTIVE

To determine whether the beneficial effects of growth hormone persist throughout the prolonged hypermetabolic and hypercatabolic response to severe burn.

SUMMARY BACKGROUND DATA

The hypermetabolic response to severe burn is associated with increased energy expenditure, insulin resistance, immunodeficiency, and whole body catabolism that persists for months after injury. Growth hormone is a potent anabolic agent and salutary modulator of posttraumatic metabolic responses.

METHODS

Seventy-two severely burned children were enrolled in a placebo-controlled double-blind trial investigating the effects of growth hormone (0.05 mg/kg per day) on muscle accretion and bone growth. Drug or placebo treatment began on discharge from the intensive care unit and continued for 1 year after burn. Total body weight, height, dual-energy x-ray absorptiometry, indirect calorimetry, and hormone values were measured at discharge, then at 6 months, 9 months, and 12 months after burn. Results were compared between groups.

RESULTS

Growth hormone subjects gained more weight than placebo subjects at the 9-month study point; this disparity in weight gain continued to expand throughout the remainder of the study. Height also increased in the growth hormone group compared with controls at 12 months. Change in lean body mass was greater in those treated with growth hormone at 6, 9, and 12 months. Bone mineral content was increased at 9 and 12 months; this was associated with higher parathormone levels.

CONCLUSIONS

Low-dose recombinant human growth hormone successfully abates muscle catabolism and osteopenia induced by severe burn.

Anabolic effects of oxandrolone after severe burn

OBJECTIVE

To explore the hypothesis that oxandrolone may reverse muscle catabolism in cachectic, critically ill pediatric burn patients.

SUMMARY BACKGROUND DATA

Severe burn causes exaggerated muscle protein catabolism, contributing to weakness and delayed healing. Oxandrolone is an anabolic steroid that has been used in cachectic hepatitis and AIDS patients.

METHODS

Fourteen severely burned children were enrolled during a 5-month period in a prospective cohort analytic study. There was a prolonged delay in the arrival of these patients to the burn unit for definitive care. This neglect of skin grafting and nutritional support resulted in critically ill children with significant malnutrition. On arrival, all patients underwent excision and skin grafting and received similar clinical care. Subjects were studied 5 to 7 days after admission, and again after 1 week of oxandrolone treatment at 0.1 mg/kg by mouth twice daily or no pharmacologic treatment. Muscle protein kinetics were derived from femoral arterial and venous blood samples and vastus lateralis muscle biopsies during a stable isotope infusion.

RESULTS

Control and oxandrolone subjects were similar in age, weight, and percentage of body surface area burned. Muscle protein net balance decreased in controls and improved in the oxandrolone group. The improvement in the oxandrolone group was associated with increased protein synthesis efficiency. Muscle protein breakdown was unchanged.

CONCLUSIONS

In burn victims, oxandrolone improves muscle protein metabolism through enhanced protein synthesis efficiency. These findings suggest the efficacy of oxandrolone in impeding muscle protein catabolism in cachectic, critically injured children.

Determinants of skeletal muscle catabolism after severe burn

OBJECTIVE

To determine which patient factors affect the degree of catabolism after severe burn.

SUMMARY BACKGROUND DATA

Catabolism is associated with severe burn and leads to erosion of lean mass, impaired wound healing, and delayed rehabilitation.

METHODS

From 1996 to 1999, 151 stable-isotope protein kinetic studies were performed in 102 pediatric and 21 adult subjects burned over 20-99. 5% of their total body surface area (TBSA). Patient demographics, burn characteristics, and hospital course variables were correlated with the net balance of skeletal muscle protein synthesis and breakdown across the leg. Data were analyzed sequentially and cumulatively through univariate and cross-sectional multiple regression.

RESULTS

Increasing age, weight, and delay in definitive surgical treatment predict increased catabolism (P < .05). Body surface area burned increased catabolism until 40% TBSA was reached; catabolism did not consistently increase thereafter. Resting energy expenditure and sepsis were also strong predictors of net protein catabolism. Among factors that did not significantly correlate were burn type, pneumonia, wound contamination, and time after burn. From these results, the authors also infer that gross muscle mass correlates independently with protein wasting after burn.

CONCLUSIONS

Heavier, more muscular subjects, and subjects whose definitive surgical treatment is delayed are at the greatest risk for excess catabolism after burn. Sepsis and excessive hypermetabolism are also associated with protein catabolism.

Biobrane improves wound healing in burned children without increased risk of infection

A synthetic bilaminar membrane used as a skin substitute (Biobrane) has been shown to decrease pain and hospitalization in superficial second-degree burns. Despite these benefits, it has not been utilized universally, particularly in young children, due to a perceived increase in related infections. We propose that when this synthetic membrane is applied to superficial scald burns <25% of the total body surface area (TBSA), decreased healing times are expected without increased risk of infection. Between 1994-1999, 89 children treated within 48 h after receiving superficial partial thickness scald burns covering 5-25% TBSA with no indication of infection were seen at our hospital. Forty-one were assigned randomly to receive treatment with the skin substitute Biobrane and 48 to receive conservative treatment with topical antimicrobials and dressing changes. Comparisons of treatment were made between groups for length of hospitalization, wound healing times, and infectious complications. Children treated with Biobrane or topical antimicrobials were similar in age, race, sex, %TBSA burned, and location of burn. Those receiving Biobrane had shorter hospitalizations and healing times, which was significant for both infants and toddlers and older children. Treatment groups were not different in the use of systemic antibiotics or readmissions for infectious complications. Biobrane was removed in 5.9% of cases for non-adherence. The application of Biobrane within 48 h of superficial burns provides for shorter hospitalizations and faster healing times in children of all ages without increased risk of infection.

Persistence of muscle catabolism after severe burn

BACKGROUND

The hypermetabolic response to severe burn is characterized by muscle protein catabolism. Current opinion states that the hypermetabolic state resolves soon after complete wound closure. Clinically, we have witnessed that burned children appear to be hypermetabolic and catabolic long after full healing of their wounds. Our goal in this study was to determine scientifically if burn-associated hypermetabolism persists after full wound healing.

METHODS

To determine the duration of muscle catabolism and systemic hypermetabolism after severe burn in children, patients with > 40% total body surface area burns were enrolled in a prospective, longitudinal study; resting energy expenditure was measured by indirect calorimetry, muscle protein kinetics were determined by using stable isotopic methodology, and body composition was measured by dual-energy x-ray absorptiometry imaging. Data were collected at 6, 9, and 12 months after injury.

RESULTS

The mean total body surface area burned was 65% +/- 13%, and the mean age was 7.6 +/- 1. 5 years. Resting energy expenditure was elevated above the predicted age-matched levels from the Harris-Benedict equation and incrementally declined throughout the 12-month study. The net protein balance and lean mass reflected catabolic persistence at 6 and 9 months after severe burn. Between 9 and 12 months, protein breakdown decreased, net protein balance improved, and lean body mass increased.

CONCLUSIONS

In severely burned children, hypermetabolism and catabolism remain exaggerated for at least 9 months after injury. This suggests that therapeutic attempts to manipulate the catabolic and hypermetabolic response to severe injury should be continued long after injury.

Gut epithelial apoptosis after severe burn: effects of gut hypoperfusion

BACKGROUND

Severe cutaneous burn causes transient mesenteric vasoconstriction and altered gut mucosal integrity. We recently showed that burn also increases gut epithelial cell death by apoptosis. The goal of this study was to determine whether changes in gut perfusion after burn contribute to burn-associated gut apoptosis.

STUDY DESIGN

We first correlated superior mesenteric artery blood flow with measurement of gut perfusion at the tissue level by laser doppler in four nonburned rats before, during, and after arterial clamping to validate our measurements of gut perfusion. We then characterized gut perfusion sequentially over time after burn; gut perfusion was measured 3 cm from the ligament of Treitz before burn and hourly for 6 hours. A group of control rats underwent the exact same protocol without the burn to exclude effects of anesthesia and laparotomy on tissue perfusion (n = 4). We studied a third group of rats with hypoperfusion of the same duration and magnitude induced mechanically without burn (n = 7). Sections of the proximal gut from all three groups (control without burn, burn, and hypoperfusion without burn) were examined for epithelial apoptosis.

RESULTS

Linear regression analysis demonstrated a strong correlation between superior mesenteric artery blood flow and intestinal tissue perfusion measured by laser doppler under both low and high flow conditions (r = 0.85). Laser doppler measurements of gut perfusion after burn showed deceased gut perfusion that was maximal at 2 hours postburn (p < 0.05), and that persisted for 4 hours (p < 0.05). By 6 hours, gut perfusion returned to baseline. Apoptosis increased significantly in the burn group (2.11 +/- 0.17%) compared with control (0.52 +/- 0.2%) and the mechanically decreased perfusion group (0.51 +/- .03) (p < 0.001).

CONCLUSIONS

We conclude that burn-induced gut hypoperfusion is insufficient to cause burn-related increased gut epithelial apoptosis. We speculate that the signal for increased gut epithelial apoptosis is primarily related to proinflammatory mediators induced by the burn wound.

Identification and chromosomal assignment of two heterozygous mutations in the Trp53 gene in L5178Y/Tk(+/-)-3.7.2C mouse lymphoma cells

The thymidine kinase locus (Tk1) in Tk(+/-)-3.7.2C mouse lymphoma cells is widely used to identify mutagenic agents. Because Trp53 (the mouse homolog of human TP53) is located with Tk1 on chromosome 11 and is critical in regulating cellular responses following exposure to DNA damaging agents, we wanted to determine if these mouse lymphoma cells harbor mutations in Trp53. Single-stranded conformation polymorphism (SSCP) analysis of PCR-amplified exons 4-9 of Trp53 indicated mutations in both exons 4 and 5. We sequenced exons 4-9 from isolated clones of Tk(+/-)-3.7.2C cells and a Tk-/- mutant (G4). Mutant G4 has two copies of the chromosome carrying the Tk1- allele and no copy of the chromosome carrying the Tk1+ allele and thus could establish linkage of the individual Trp53 and Tk1 alleles. DNA sequence analysis revealed no mutations in exons 6-9 in any Tk(+/-)-3.7.2C or G4 clones. As suggested by SSCP, there was a nonsense mutation in exon 4 at bp 301 (codon 101) in one Trp53 allele. Tk(+/-)-3.7.2C clones have both mutant and wild-type sequences at bp 301; G4 clones have wild-type exon 4 sequence. These data allow assignment of the Trp53 exon 4 mutated allele to chromosome 11 carrying the Tk1+ allele. The exon 4 mutation leads to a stop codon early in translation, thus functionally deleting the Trp53 allele on the Tk1(+)-bearing chromosome. As previously reported, we find a missense mutation in exon 5 at bp 517 (codon 173) in one Trp53 allele. Using the G4 clones we determined that the exon 5 mutation is linked to the Tk1- allele. Thus the Tk +/-(-)3.7.2C mouse lymphoma cells have two mutant Trp53 alleles, likely accounting for their rapid cell growth and contributing to their ability to detect the major types of mutational damage associated with the etiology of tumor development. This ability to integrate across the mutational events seen in the multiple stages of tumor development further supports the use of the assay in chemical and drug safety studies and its recommendation as part of the required screening battery for regulatory agency submissions.

Amsacrine-induced mutations in AS52 cells

Amsacrine is an acridine-derived inhibitor of topoisomerase II that intercalates into DNA. We performed a detailed molecular analysis of 6-thioguanine (6-TG)-resistant mutant colonies arising in AS52 cells following Amsacrine treatment. AS52 cells carry a single copy of the bacterial gpt gene, functionally expressed using the SV40 early promoter and stably integrated into the Chinese hamster ovary genome. A 1-hr treatment with 0.1 to 0.5 microM Amsacrine was both cytotoxic and mutagenic, resulting in an average mutant frequency (MF) of 143 x 10(6) at 0.5 microM. Fifty independent 6-TG-resistant colonies were isolated for further study. These clones were initially characterised by PCR to estimate the relative proportion of putative point mutants and deletions or rearrangements; then a subset of mutants was further characterised by Southern blotting, Northern blotting, and DNA sequence analysis. Total deletion of the gpt gene sequences was found in 1 (2%) of the mutants, and 7 (14%) of the mutant clones had altered PCR patterns, suggesting complex deletions or rearrangements. The remaining 42 (84%) mutants had a wild-type PCR profile. Of these, 21 mutants were further analysed by Southern blotting. Interestingly, Southern blotting revealed genomic deletions/rearrangements in 12 of 21 mutants with a wild-type PCR profile. These deletions/rearrangements were further shown to affect gpt gene expression. The remaining nine mutants with a wild-type PCR profile were sequenced. Four of these mutants had mutations in the gpt structural gene. Overall, genomic deletions/rearrangements were observed in 12/21 independent mutants subjected to PCR and Southern blotting. Thus, deletions/rearrangements were the most common mutation observed following Amsacrine treatment of AS52 cells.

Databases and software for the analysis of mutations in the human p53 gene, human hprt gene and both the lacI and lacZ gene in transgenic rodents

We have created databases and software applications for the analysis of DNA mutations at the human p53 gene, the human hprt gene and both the rodent transgenic lacI and lacZ loci. The databases themselves are stand-alone dBASE files and the software for analysis of the databases runs on IBM-compatible computers with Microsoft Windows. Each database has a separate software analysis program. The software created for these databases permit the filtering, ordering, report generation and display of information in the database. In addition, a significant number of routines have been developed for the analysis of single base substitutions. One method of obtaining the databases and software is via the World Wide Web. Open the following home page with a Web Browser: http://sunsite.unc.edu/dnam/mainpage. html . Alternatively, the databases and programs are available via public FTP from: anonymous@sunsite.unc.edu. There is no password required to enter the system. The databases and software are found beneath the subdirectory: pub/academic/biology/dna-mutations. Two other programs are available at the site, a program for comparison of mutational spectra and a program for entry of mutational data into a relational database.

Room-temperature lasing of end-pumped Ho:Lu(3)Al(5)O(12)

Room-temperature lasing at 2.1-microm has been demonstrated in Ho:Lu(3)Al(5)O(12) with a slope efficiency of 82% and a threshold energy of 4.4 mJ. A maximum absorbed energy of 17 mJ yielded 10 mJ of laser output energy. To simulate diode-pumping experiments, a tunable Co:MgF(2) laser operating at 1.878 microm was used to achieve lasing on (5)I(7) ? (5)I(8) transitions.

Lindane does not alter the estrogen receptor or the estrogen-dependent induction of progesterone receptors in sexually immature or ovariectomized adult rats

Lindane, gamma-1,2,3,4,5,6-hexachlorocyclohexane (gamma-HCH), has been shown to disrupt reproductive function in mammals. Many of these adverse effects on female reproduction such as alterations in sexual receptivity, disrupted ovarian cyclicity, reduction in uterine weight and termination of pregnancy are thought to be due to altered ovarian hormone secretions and/or an impaired response to circulating estrogen. It has been suggested that gamma-HCH may block the response of estrogen-dependent tissues to estradiol via an interaction with the estrogen receptor. To test this hypothesis, estrogen (ER) and progesterone (PR) receptor affinity and number were evaluated in sexually immature, 17 beta-estradiol-3-benzoate (EB)-primed Long Evans female rats following exposure to vehicle or gamma-HCH (40 mg/kg) for 7 days (Study 1) and in adult, ovariectomized EB-primed Long-Evans rats following gavage with vehicle or gamma-HCH (0, 10, 20, or 40 mg/kg) for 5 days (Study 2). Chlordecone (kepone; 40 mg/kg; i.p.) was used in Study 2 as a positive control for the alteration of the estrogen-induction of PR in the pituitary. Neither gamma-HCH nor chlordecone altered serum estradiol concentrations. gamma-HCH did not change the ER number (1, 24, or 30 h after EB) or the estrogen-dependent induction of PR (24 or 48 h after EB) in the hypothalamus (HYP), pituitary, or uterus. These data indicate that the effects of gamma-HCH on the female reproductive system do not involve an alteration in the ER and that heterogeneity exists between target tissues in their response to xenobiotics.

Illinois: Community mental health: a noble failure?

Two studies were made in the northwestern region of Illinois to determine if the community approach helped restore the social competence and reduce the build-up of chronically ill patients. In the first study there was no indication that community care was superior to that of a traditional state hospital. Seventy-four per cent of the patients in the sample, however, had a history of repeated hospitalizations. The second study evaluated only first-admission patients and found that community-oriented programs were more effective. Both the center and the hospital had some patients for whom neither system of care was more effective in preventing chronicity. The center has established several pilot projects for managing those chronic patients.