No detrimental effect from chronic exposure to buprenorphine on corticosteroid-binding globulin and corticosensitive immune parameters.

Opioid drugs reportedly regulate the immune system via their effects on the hypothalamic- pituitary-adrenal (HPA) axis. The present study was carried out to assess the effects of chronic exposure to buprenorphine on HPA axis activation, corticosteroid-binding globulin (CBG), the main glucocorticoid (GC) carrier, and the immune system. Results show that buprenorphine, delivered by osmotic pump subcutaneously in C57BL/6 male mice during a 10-day period, caused a marked decrease in total corticosterone (CORT) levels at day 1 of exposure. CORT levels then increased with maximal values observed at day 5 of exposure. After day 5, total CORT levels gradually decreased and returned to control values. No significant changes were observed in CBG protein levels and mRNA expression in the liver. Since CBG levels remained unchanged, the percentage of free CORT values in buprenorphine mice did not differ from control values. Thus, the variations observed in the amount of free CORT were related only to changes measured in total CORT. These endocrine changes did not have a significant impact on the immune parameters measured. Total CD(4)+ and CD(8)+ splenic and thymic populations were not modulated by buprenorphine. However, splenocytes from mice exposed to buprenorphine after 5 days exhibited greater proliferation upon anti-TCR monoclonal antibody stimulation than saline-exposed mice. These results indicate that buprenorphine can be safely used because it did not have significant effects on GC availability for immune corticosensitive cells.

Increased thermogenic response to food and fat oxidation in female athletes: relationship with VO(2 max).

The thermogenic response to food (TRF) and substrate oxidation were studied in 12 endurance-trained and 13 untrained female subjects. Energy expenditure and substrate oxidation were calculated by indirect calorimetry before and for 6 h after an oral test meal and after the same meal given intragastrically on a separate occasion. The TRF was calculated after the oral meal, the obligatory component after the intragastric meal (OTRF), and the facultative component from the difference between the two. VO(2 max) was measured on a treadmill and body composition by underwater weighing. The TRF and OTRF were significantly higher in trained than in untrained subjects: 223 +/- 63 vs. 185 +/- 50 kJ/6 h (P < 0.03) and 174 +/- 38 vs. 131 +/- 37 kJ/6 h (P < 0.01) for the TRF and OTRF in trained vs. untrained subjects, respectively. Multiple regression analysis showed that maximum O(2) consumption (VO(2 max)), but not percentage of body fat, was significantly related to OTRF (r =0.68, P < 0.01). Trained subjects had higher fatty acid oxidation than untrained subjects before (0.6 vs. 0.4 mg. kg(-1). min(-1), P < 0.05) and after the oral meal (13 +/- 6 vs. 8 +/- 4 g/6 h P < 0.05). These results demonstrate that 1) TRF is higher in trained than in untrained women; 2) this is due to a higher cost of nutrient digestion, absorption and storage; 3) the difference is related to higher VO(2 max); and 4) fatty acid oxidation is greater in trained women in both the postabsorptive and postprandial states. These observations suggest that endurance training induces metabolic changes that favor leanness.

Decreased serum insulin-like growth factor-I in burn patients: relationship with serum insulin-like growth factor binding protein-3 proteolysis and the influence of lipid composition in nutritional support.

OBJECTIVES: To test the effects of the amount and type of fat in the nutritional support on serum insulin-like growth factor (IGF)-I concentrations in burn patients and to test the hypothesis that the serum proteolytic activity for insulin-like growth factor binding protein (IGFBP)-3 is a major mechanism for the decreased serum IGF-I observed in these patients. DESIGN: Randomized, double-blind trial of three different nutritional supports and analysis of serum IGF-I, IGFBP-3, and serum IGFBP-3 proteolysis. SETTING: Burn center in a university hospital. PATIENTS: A total of 23 severely burned (>25% total body surface area burned) adult patients. INTERVENTIONS: Patients were randomly assigned to three types of nutritional support differing in the amount of energy derived from fat and the presence or absence of fish oil: Group I (control), 35% fat; Group II, 15% fat; Group III, 15% fat with 50% as fish oil. Nutritional support was both parenteral and enteral and was started within 24 hrs of admission. MEASUREMENTS AND MAIN RESULTS: Serum IGF-I and IGFBP-3 were measured by radioimmunoassay every 3 days for 28 days in 23 severely burned adults. In six patients, IGFBP-3 was measured by ligand binding assay and the serum proteolytic activity for rhIGFBP-3 was measured as well. Serum IGF-I concentration was low in all subjects throughout the study period, but did increase with time (p < .01); significantly higher values were found in Group III (p < .05). Multivariate analysis showed that fish oil and low fat solutions were significantly correlated to serum IGF-I concentrations. Serum IGFBP-3 (radioimmunoassay) was higher than normal throughout the study with no difference between the groups. Between days 4 and 16, IGFBP-3 was cleaved into two fragments in all patients studied, and the molecular weights of the fragments were equal to those observed in the serum of a woman late in pregnancy. During this period of time, serum proteolytic activity for rhIGFBP-3 was >30% in 24 of the 30 samples measured, whereas 20 of the 28 samples measured thereafter were normal (<25%). Serum IGFBP-3 concentration from ligand binding assay was correlated with serum proteolytic capacity in all subjects (mean r2 = 0.77; p < .01) and with serum IGF-I concentrations in five of six subjects (mean r2 = 0.81; p < .01). CONCLUSIONS: In burn injury, serum IGF-I concentrations are sensitive to the amount and type of fat in their nutritional support. The presence of fish oil allowed for a more rapid recovery of serum IGF-I levels. The proteolysis of IGFBP-3 may be an important cause of the decreased serum IGF-I values and the protease(s) responsible for this seem to be similar to those observed in late pregnancy.

Increased burn-induced immunosuppression in lipopolysaccharide-resistant mice.

Severe burns induce a state of immunosuppression, and the inflammatory response after burn injury may play a role in this phenomenon. This study examined the effect of the inflammatory response to endotoxin on burn-induced immunosuppression and oxidative stress. An endotoxin-resistant mouse strain (C3H/HeJ) and a normally responding mouse strain (C3H/HeN) were compared. The mice were separated into three groups of five animals for each experimental day: (1) saline, (2) buprenorphine, and (3) buprenorphine and 20% total body surface area burn. All animals were fed ad libitum. The inflammatory response was studied at 1, 4, 7, 10, and 14 days postburn. Proliferation of activated splenocytes in burn mice was significantly lower on days 7, 10, and 14 for the C3H/HeJ strain and on days 4 and 10 for the C3H/HeN strain. Globally, C3H/HeJ presented stronger immune suppression than C3H/HeN. Oxidative stress parameters (liver malonaldehyde, spleen metabolic activity, and thiol concentrations) were higher in endotoxin-resistant mice than in the control strain. Impairment of the inflammatory response was more pronounced and oxidative stress was greater in endotoxin-resistant burn mice than in normal burn controls. Buprenorphine administration was not related to depression of these immune parameters. The inflammatory response following burn injury may be beneficial to the immune system.

Improved immune functions with administration of a low-fat diet in a burn animal model.

The purpose of this study was to characterize the impact of a low-fat (LF; 1% fat) diet, a high-fat (HF; 25% fat) diet, and a standard (SD; 5% fat) diet on immune and oxidative parameters in a 20% body surface area burn animal model fed ad libitum for 10 days postinjury. Although the mechanisms are poorly understood, the amount of dietary lipid in nutritional support has been shown to have immunomodulatory effects after burn injury. Burned mice fed the LF diet showed a normal response in activated splenocyte proliferation compared to burned animals that received the SD or HF diet. Animals fed the SD and HF diets presented increased production of nitric oxide and prostaglandin E2 response after burn injury, which is associated with inhibited splenocyte proliferation. The total thiol concentration in spleen cells from burned animals kept on the HF diet was significantly higher than that in unburned animals, while no increase in these oxidative parameters was observed in LF-fed burned animals. Moreover, the LF diet significantly reduced hepatic lipid peroxidation, as measured by malonaldehyde concentration, compared to the other two diets. These results suggest that the administration of a LF diet in mice after a burn injury prevents inhibition of in vitro splenocyte proliferation and reduces the intensity of oxidative stress.

Antiangiogenic effects of the oral administration of liquid cartilage extract in humans.

BACKGROUND: The antiangiogenic properties of shark cartilage extracts have been demonstrated in animal models but there are no data in human subjects. MATERIALS AND METHODS: A placebo or one of two doses of a liquid shark cartilage extract was orally administered daily, from Day 1 to Day 23 of the study protocol, to 29 healthy male volunteers randomized into three groups. On Day 12, a polyvinyl alcohol sponge threaded in a perforated silicone tubing was inserted subcutaneously on the anterior side of the arm and removed on Day 23. Evaluation of endothelial cell density, with factor VIII immunostaining, an indirect measurement of angiogenesis, was performed on histological sections of the implant using a semiquantitative numerical scale ranging from 1 (low density) to 5 (high density). The hydroxyproline content of the sponges was measured by HPLC. RESULTS: The mean endothelial cell density was significantly lower in groups that had received the liquid cartilage extract: grades 2.24 +/- 0.10, 2.47 +/- 0.10, and 3.15 +/- 0.11 for 7 and 21 ml liquid cartilage extract and placebo, respectively (P < 0.01 for both comparisons). No grade 1 was observed in the placebo group, whereas 9 treated subjects received a grade 1. Hydroxyproline content of the sponges did not differ between groups and there was no significant correlation between hydroxyproline content and endothelial cell density in the sponges. CONCLUSIONS: These results demonstrate that the liquid cartilage extract contains an antiangiogenic component bioavailable in humans by oral administration. This is the first report of an inhibition of wound angiogenesis in healthy men.

Decreased corticosteroid-binding globulin in burn patients: relationship with interleukin-6 and fat in nutritional support.

OBJECTIVES: To analyze the effect of low-fat nutritional solutions, with or without fish oil, on serum interleukin (IL)-6, and to explore the relationships between IL-6, corticosteroid-binding globulin (CBG; the main cortisol carrier in plasma), and protein metabolism in severely burned adult patients. DESIGN: Randomized, double-blind study with control and low fat-fed groups. SETTING: Burn center of Hôtel-Dieu Hospital of Montréal. PATIENTS: Thirty-seven men and women with thermal burn injury over >20% of body surface area and no other known medical condition. INTERVENTIONS: Within 24 hrs after admission, nutritional support was started through a gastroenteral tube inserted under endoscopic guidance. The goal for energy intake was calculated using the Curreri formula, and was adjusted with biweekly measurements of resting energy expenditure. Patients were randomly assigned to one of the following groups: control (35% of energy as fat); low fat 1 (15% of energy as fat); and low fat 2 (50% of fat in the form of fish oil). MEASUREMENTS AND MAIN RESULTS: Tumor necrosis factor (TNF)-alpha and TNF-beta, IL-6, CBG, and cortisol free fraction were measured every 3 days for 28 days. Nitrogen balance and urinary 3-methylhistidine excretion were measured daily. IL-6 concentrations were high in all patients, with the highest value (460 +/- 111 units/mL) observed on day 4. Concentrations of IL-6 were higher in control patients than in low fat-fed patients between days 13 and 28, but not between days 1 and 13. Multivariate analysis showed that IL-6, total body surface area burned, and sepsis scores were independent predictors of CBG between days 1 and 13 (n = 170; p<.00001). High IL-6 concentrations were predictors of low CBG concentrations and high cortisol free fractions. There was no relationship between IL-6, nitrogen balance, and 3-methylhistidine excretion. TNF-alpha and TNF-beta activity measurements by biological assay showed no correlation with other factors measured. CONCLUSIONS: a) Low-fat feeding, with or without fish oil, does not change the early production of IL-6 after burn injury; b) serum IL-6 is negatively correlated with CBG, which supports the hypothesis that this cytokine inhibits hepatic CBG production; and c) IL-6 does not appear to directly influence protein metabolism in burn patients.

Muscle strength in individuals with healed burns.

OBJECTIVE: To quantify the long-term effects of burns on muscle strength and to investigate the impact of the initial severity of the trauma on muscle strength. DESIGN: Cross-sectional study comparing individuals with healed burns to nonburned control individuals matched for age, gender, body mass index, and physical activity level. SETTING: Subjects were selected from the data bank of a burn center of a large Montreal teaching hospital and tested in a university laboratory. PATIENTS: Thirty subjects (mean age, 36.3 +/- 11.5 yrs) with second- and third-degree burns covering 15% to 75% of total body surface area (TBSA) (mean, 35.5% +/- 15.9%) were evaluated more than 1 year after discharge (mean, 37.3 +/- 20.4 months; range, 15 to 92 months). Thirty unburned subjects were recruited from the community at large. MAIN OUTCOME MEASURE: Maximal torque, work, and power developed by the elbow and knee flexors and extensors. RESULTS: Subjects with burns of > 30% of TBSA produced significantly less torque, work, and power in the quadriceps than control subjects (15.2% to 20.5% depending on velocity [p < .05]). The ability to develop muscle power at the elbow was also compromised in the severely burned subjects (19.2% in extension and 18.7% in flexion [p = .07]) at the faster velocities. No differences were observed between controls and patients with small burn injuries (TBSA of < 30%). CONCLUSION: Patients who had severe burns (TBSA of > 30%) had weaker muscles even years after the trauma, suggesting either an inability to fully recover or insufficient rehabilitation.

Role of the autonomic nervous system in the thermogenic response to food in lean individuals.

The aim of this study was to determine the role of the autonomic nervous system (ANS) in obligatory and facultative components of the thermogenic response to food (TRF). Nineteen lean, healthy subjects participated in this study, which comprised two protocols, each exploring one component of the ANS. In the first experimental group, propranolol (prime: 80 micrograms/kg; continuous: 1 microgram.kg-1.min-1) was infused intravenously to inhibit sympathetic nervous activity (SNA), whereas in the second group atropine (prime: 5 micrograms/kg; continuous: 5 micrograms.kg-1.min-1) was used to inhibit parasympathetic nervous activity (PNA). The TRF was measured on four occasions: 1) after oral ingestion of a breakfast, during 0.9% NaCl perfusion, 2) after oral ingestion of the same breakfast, during the perfusion of one of the drugs, 3) after intragastric injection of a pureed form of the same meal as in part 1, during 0.9% NaCl perfusion, and 4) after intragastric feeding, during the administration of one of the drugs. Energy expenditure was measured by indirect calorimetry for 30 min before and 6 h after ingestion of the meal. Facultative TRF was defined as the difference between oral and intragastric TRF. Intragastric feeding significantly reduced TRF in both studies: 6.6 +/- 1.0 vs. 8.7 +/- 0.8% of the ingested energy in the SNA study and 5.5 +/- 1.6 vs. 7.4 +/- 3.1% in the PNA study. During propranolol infusion, TRF was significantly lower than it was during saline infusion after oral feeding (6.9 +/- 1.0% vs. 8.7 +/- 0.8% of ingested energy) but not after intragastric feeding. During atropine administration, TRF was reduced after both oral and intragastric feeding, although statistical significance was not reached in the latter. Atropine administration decreased gastric emptying (measured with an isotopic method) 2 h postingestion by 50%. These results show that the SNA is necessary for the facultative component of TRF to occur in humans. The role of the PNA appears to be related to its action on gastric emptying.

Activation of the ubiquitin pathway in rat skeletal muscle by catabolic doses of glucocorticoids.

To evaluate whether catabolic levels of glucocorticoids activate the ubiquitin pathway in conjunction with their known proteolytic effect in skeletal muscle, rats were injected daily with corticosterone (CTC; 10 mg/100 g body wt) for 7 days. Two peaks of urinary excretion of 3-methylhistidine (3-MH), a specific marker of myofibrillar proteolysis, were observed at days 1 and 3 (165 and 295% of controls, respectively). Levels of ubiquitin pathway mRNAs in skeletal muscle were assessed around the 3-MH peaks. In the extensor digitorum longus, a first rise of two polyubiquitin (pUb) mRNAs was seen at day 1 (183 and 162% of control for the UbB and UbC transcripts, respectively, P < 0.01). An accumulation of both E2-14k mRNAs (140%, P < 0.02, and 157% of controls, P < 0.01) and proteasome C8 subunit mRNA (222% of control, P < 0.05) was seen at day 2. A second more important peak of induction of pUb mRNA was seen at day 3 (251 and 217% of controls for the UbB and UbC transcripts, respectively, P < 0.001). All transcripts returned to near control levels by day 4. In the soleus, induction of E2-14k mRNA started at day 3 and reached 216 and 208% of controls at day 4 (P < 0.001), whereas an increase of pUb mRNA was observed at days 3 (213 and 241%, P < 0.05) and 4 (211 and 221%, P < 0.001). A rise of proteasome C8 subunit mRNA accumulation was also seen in the soleus at days 3 (217%, P < 0.05) and 4 (157%, P < 0.05). Reduced ubiquitin conjugate levels, possibly due to their rapid degradation through increased proteasome activity, were observed in both muscle types at day 3. The parallel between the catabolic effects of CTC and activation of the ubiquitin pathway in muscles of CTC-treated rats strongly suggests the involvement of this system in glucocorticoid-induced muscular atrophy.

In vitro models to study wound healing fibroblasts.

Phenotypic and contractile properties of human fibroblasts from dermis and from an experimental wound model were studied in vitro. When cultured in monolayer, dermal fibroblasts had an elongated spindle shape, were small in diameter and grew at a high rate. Wound fibroblasts grew slowly and were large, star shaped and had cytoplasmic stress fibres. Smooth muscle alpha actin was detected in 10 percent of dermal cells, whereas 20-80 per cent of wound fibroblasts contained this protein in their cytoplasm. The contractile property of cells was evaluated using a three-dimensional cell culture model. Our results show that wound fibroblasts contract collagen gels during the first days more strongly than dermal fibroblasts. These results show that, in vitro, wound fibroblasts have greater contractile capacity than dermal cells. The significant proportion of wound fibroblasts containing alpha-smooth muscle actin suggests that alpha-smooth muscle actin ratio may be related to wound contraction.

Should we still use the Harris and Benedict equations?

Resting metabolic rate (RMR) is commonly predicted using the Harris-Benedict (HB) equations, but an overestimation of 10% to 15% is normally found. More recent studies have proposed equations with a better predictive value. In this study, we explore the relationship between measured RMR and HB in 67 healthy volunteers and in a data set from the literature and compared measured RMR with six more recent equations. Mean differences between RMR and HB were 21%, 12%, 10%, and 4% for the lowest to the highest RMR quartile, respectively, and 20%, 8%, 6%, and -4% for Owen's subjects. Among the six recent equations, only the World Health Organization (WHO) equations predicted RMR within 10% in 100% of the cases. Our results suggest that overestimation of RMR by HB is not a homogenous finding but is inversely related to RMR. This may have important implications for predicting RMR in women and in patients with diminished lean body mass. In addition, the WHO equations appear more precise than the HB equations.

Effects of RU 486 on energy expenditure and meal tolerance in normal men.

OBJECTIVE: To evaluate the possible actions of glucocorticoids on resting energy expenditure and the thermogenic response to food in man. METHODS: The morning after administration of RU 486 or placebo, resting metabolic rate (RMR) and the thermogenic response to food (TRF), were measured after the ingestion of a standardized meal in 12 healthy male volunteers. Plasma glucose (PG) and insulin (PI) concentrations were also measured at regular intervals. RESULTS: 1) After RU 486 administration, plasma cortisol was elevated throughout the test comparatively to placebo. 2) Fraction and concentration of free cortisol were also higher after RU 486 than after placebo. 3) Corticosteroid-binding-globulin (CBG) was similar in both experimentations. 4) RMR was not different after RU 486 (1656 +/- 144 kcal/day) or after placebo (1632 +/- 120 kcal/day). 5) TRF was not different after RU 486 or placebo (54 +/- 12 kcal vs 59 +/- 13 kcal over a 6 hour period for RU 486 and placebo, respectively). 6) Baseline glucose concentrations were similar at baseline but PG was higher 90 minutes postprandial with RU 486: 5.3 +/- 1.7 mmol/L vs 3.7 +/- 0.8 mmol/L for placebo. 7) Plasma insulin was similar at baseline but it was significantly higher at 90 minutes postprandial after RU 486 (347 +/- 143 vs 241 +/- 73 pmol/L for RU 486 and placebo, respectively). CONCLUSIONS: This study shows that acute inhibition of glucocorticoid action does not alter RMR and TRF in healthy men and that a mild deterioration of glucose tolerance follows the ingestion of RU 486.

Corticosteroid-binding globulin during inflammation and burn injury: nutritional modulation and clinical implications.

Corticosteroid-binding globulin (CBG) is the main carrier of glucocorticoids in mammals. Serum CBG shows little physiological variation with the exception of pregnancy. Experimental inflammation and burn injury decrease serum CBG in rats and while the mechanism of this effect is unknown, in vitro experiments suggest that interleukin-6 may be involved. In severely burned patients, we have found that CBG was markedly decreased within a few hours postinjury. This decrease lasted about 2 weeks and was accompanied by an increase in the free fraction of serum cortisol. In addition, serum CBG responded to dietary manipulation in these patients, with low fat feeding resulting in higher serum CBG concentrations and lower serum-free cortisol values. This feeding suggests that during severe stress, CBG may be important in regulating the amount of cortisol reaching target tissues such as the immune system and wounds.

Improved clinical status and length of care with low-fat nutrition support in burn patients.

BACKGROUND: The optimal amount and type of fat in the nutrition support of burned patients have not been determined. The aim of this study was to test low-fat nutritional solutions, with or without fish oil, on protein metabolism, morbidity, and length of care in severely burned adults. METHODS: In a prospective randomized clinical trial, 43 patients were assigned to one of the following groups: control (35% fat), low-fat solution (ie, 15% of total calories as fat), low-fat with fish oil, given for 30 days. Nitrogen balance, urinary 3-methylhistidine excretion, urinary cortisol, and clinical status were measured daily. Corticosteroid-binding globulin and total and free serum cortisol were measured every 3 days. RESULTS: Compared with controls, patients on low-fat support had fewer cases of pneumonia: 3/24 vs 7/13 (p = .02), better respiratory and nutrition status, and shorter time to healing: 1.2 vs 1.8 days/% burned area (p = 0.01). There was no difference in nitrogen balance between groups, and 3-methylhistidine excretion was higher and serum free cortisol was lower in log-fat--fed patients than in controls. There was no difference between the two low-fat groups in any of the parameters measured. CONCLUSIONS: This study showed that low-fat nutrition support decreases infectious morbidity and shortens length of stay in burn patients. Fish oil does not seem to add clinical benefit to low-fat solutions. In addition, this study provides the first evidence that nutrition intervention modulates cortisol-binding globulin and the concentration of free circulating cortisol after a severe stress.

RU 486 prevents the acute effects of cortisol on glucose and leucine metabolism.

Glucocorticoids have deleterious effects on glucose and protein metabolism. RU 486 is an antiprogestin with antiglucocorticoid activity, which could be used to prevent the undesirable metabolic effects of glucocorticoids. A randomized, controlled, double blind study was performed in eight healthy male volunteers who were tested four times: during the iv infusion of cortisol (2 micrograms/kg.min for 5 h) after the oral ingestion of RU 486 (600 mg) or a placebo, and during the infusion of a normal saline solution with placebo or RU 486 ingestion. During each test, a primed continuous iv infusion of D-[6,6-2H]glucose and [1-13C-]leucine was given for the calculation of hepatic glucose production and plasma leucine appearance rate. 13CO2 enrichment in breath was measured for the calculation of leucine oxidation. Plasma concentrations of cortisol, ACTH, insulin, C-peptide, glucagon, and GH were measured at regular intervals. Compared to saline, cortisol infusion increased plasma glucose 5.5 +/- 0.6 vs. 4.7 +/- 0.4 mmol/L; P < 0.01) and leucine (179 +/- 35 vs. 155 +/- 35 mumol/L; P < 0.01) concentrations as well as the leucine appearance rate (2.24 +/- 0.3 vs. 2.0 +/- 0.28 mumol/kg.min; P < 0.05) and oxidation (0.51 +/- 0.22 vs. 0.39 +/- 0.06 mumol/kg.min; P < 0.01), and there was no change in hepatic glucose production. None of the metabolic changes induced by cortisol were seen when cortisol was administered after the ingestion of RU 486. When RU 486 was given before normal saline infusion, plasma glucose concentrations were transiently lower than those after placebo ingestion, as was the hepatic glucose production. No change in insulin, C-peptide, or glucagon was seen between tests. GH concentrations were higher during cortisol infusion, but not when cortisol was administered after the ingestion of RU 486. The following conclusions were reached. 1) RU 486 can suppress the effects of acute hypercortisolemia on glucose and protein metabolism and GH secretion in man. Long term studies are warranted to explore the potential of antiglucocorticoid molecules as preventive agents of the deleterious effects of chronic glucocorticoid administration. 2) RU 486 is useful molecule for studying the metabolic effects of cortisol in man.

PIP: In Montreal, Quebec, a randomized, double blind study was conducted in eight healthy men at Hotel-Dieu Hospital during administration of cortisol (2 mcg/kg per minute for 5 h) with RU-486 (600 mg), during cortisol administration with a placebo, during 0.9% saline administration with RU-486, and during normal saline administration with a placebo. Clinicians administered a primed continuous infusion of D-[6,6-2H]glucose and [1-13C-]leucine during each test to determine hepatic glucose production and plasma leucine appearance rate. Continuous infusion of labeled bicarbonate in four men was also conducted to calculate the recovery factor of carbon dioxide in their breath. Researchers wanted to examine glucose and protein metabolism during hypercortisolemia with or without RU-486 and the effects of RU-486 on the metabolic effects of acute cortisol deficiency. Among men receiving the placebo, plasma glucose levels were higher during cortisol infusion than saline infusion (5.5 vs. 4.7 mmol/l; p 0.01). The leucine appearance rate was also higher during cortisol infusion than saline infusion (2.24 vs. 2 mcmol/kg per min; p 0.05) as well as leucine oxidation (0.51 vs. 0.31 mcmol/kg; p 0.01). Hepatic glucose production did not change in either placebo group. Cortisol did not induce the same metabolic changes when it was administered after RU-486. Normal saline infusion after RU-486 induced a short-term lower plasma glucose level and hepatic glucose production. Insulin, C-peptide, or glucagon did not change. Cortisol induced increased growth hormone (GH) levels (e.g., at 240 min, 5.9 vs. 1.7 mcg/l; p 0.01) while GH levels did not change when cortisol was administered after RU-486. These findings show that RU-486 suppresses the effects of acute hypercortisolemia on glucose and protein metabolism and GH secretion in males. Long-term studies could reveal the potential of RU-486 to prevent the adverse effects of chronic glucocorticoid administration. RU-486 allows researchers to study the metabolic effects of cortisol in males.

Increased leucine flux and leucine oxidation during the luteal phase of the menstrual cycle in women.

Possible changes in protein metabolism during the menstrual cycle were examined in eight healthy women who received an intravenous infusion of L-[1-13C]leucine on time during the follicular phase of the menstrual cycle and one time during the luteal phase. Enrichment of plasma [13C]ketoisocaproate and expired 13CO2 were measured to determine leucine flux and oxidation. Continuous respiratory gas exchange measurements were made for the determination of CO2 production, O2 uptake, and energy expenditure. The day of the tests, plasma thyroid hormone concentrations were measured as well as plasma and urinary cortisol. Leucine flux was higher during the luteal than during the follicular phase (2.25 +/- 0.39 vs 2.01 +/- 0.42 mumol.kg-1.min-1; P < 0.01), and leucine oxidation was also increased during the luteal phase [0.52 +/- 0.14 vs. 0.44 +/- 0.05 mumol.kg-1.min-1 (P < 0.05) for luteal and follicular phases, respectively]. Resting energy expenditure was increased during the luteal phase compared with the follicular phase (218 +/- 22 and 199 +/- 12 kJ/h, respectively). Plasma free triiodothyronine (T3) and the ratio triiodothyronine/reverse triiodothyronine (T3/rT3) were both significantly higher during the luteal phase [7.7 +/- 0.6 vs. 7.1 +/- 0.8 and 4.65 +/- 0.80 vs. 3.93 +/- 0.70 for T3 and T3/rT3, respectively (P < 0.05 for both comparisons)]. This study shows small changes in protein metabolism during the menstrual cycle in women, with an increase in oxidative leucine metabolism during the luteal phase. The concomitant increase observed in circulating free T3 raises the possibility that fluctuations in protein metabolism and thyroid hormones throughout the menstrual cycle are causally related.

Human wound healing fibroblasts have greater contractile properties than dermal fibroblasts.

Contractile and phenotypic properties of human fibroblasts from healing wounds were compared to those of dermal fibroblasts using in vitro models. Wound fibroblasts were recovered from implants, made of a polyvinyl alcohol sponge threaded into a perforated silicone tube, 12 days after their subcutaneous implantation in human volunteers. Dermal fibroblasts were isolated from the skin of healthy subjects. Two morphologically different fibroblast populations were observed in cells cultured from implants. In order to characterize these fibroblast populations, intracellular alpha-actin expression was studied by immunofluorescence labeling of cells cultured in monolayer. This protein was detected in less than 1% of the dermal fibroblasts. By contrast, 30 to 40% of wound fibroblasts were labeled and contained fiber networks of alpha-actin. These results confirm the presence of myofibroblasts in human wound healing tissues. The contractile property of fibroblasts and myofibroblasts was evaluated using a three-dimensional cell culture model (fibroblast populated collagen gels). Cells were incorporated in a collagen matrix and cultured for 14 days. The surface area of collagen gels was measured every day. Our results show that wound fibroblasts strongly contract collagen gels during the first 24 hr (surface area at 24 hr = 20-55% of initial surface area) in comparison to dermal fibroblasts (surface area at 24 hr = 70-75% of initial surface area). This superior level of contraction was observed until the fifth day of culture.(ABSTRACT TRUNCATED AT 250 WORDS)