Analysis of Biofilm Adhesion on CAD/CAM Lithium Disilicates Under Different Types of Intraoral Polishing.

PURPOSE: To evaluate the adhesion of Streptococcus mutans (S. mutans) on lithium disilicate ceramics, submitted to different intraoral polishing protocols, and the degree of surface smoothness obtained. MATERIALS AND METHODS: Fifty lithium disilicate specimens were divided into 5 groups (n=10): G1-Glaze Group (positive control); G2-Glaze Group + Wear + Glaze; G3-Wear Group (negative control); G4-Ceramisté Wear Group; G5-Optrafine Wear Group. Surface roughness (Ra - µm) was evaluated and the surface characteristics were assessed using a scanning electron microscope (SEM); to assess S. mutans biofilm, the number of cultured cells was evaluated by counting colony-forming units (CFU/mL). The data underwent one-way ANOVA followed by Tukey's test (P⟨.05). RESULTS: There was a significant difference in the surface roughness of all groups compared with G3. There was no significant difference between the G4 and G5 groups that received polishing. G1 group had the lowest mean roughness values. There was a difference in Log values (CFU/mL) between the G3 group and the groups that received glaze (G1 and G2). The G3 group had the highest adhesion of S. mutans (4.53 Log). CONCLUSION: The most effective polishing protocol after wear is glazing, presenting the lowest roughness and CFU/mL values.

Amyloidogenesis of feline amylin and plasma levels in cats with diabetes mellitus or pancreatitis.

Amylin is a pancreatic hormone cosecreted along with insulin and involved in pancreatic amyloidosis and ß-cell apoptosis in diabetic cats and humans. Amylin is usually elevated in early stages of type 2 diabetes but recently was found to be increased in acute and chronic pancreatitis in humans. Currently, there are little data about feline amylin propensity to fibrillate and no information on circulating levels of this hormone during feline pancreatitis. We compared 4 amylin analogues and found cat amylin to be more prone to amyloid fibrillation than human amylin, the triple-proline analogue pramlintide and rat amylin. We also measured plasma amylin levels in healthy lean cats, diabetic cats, and cats with pancreatitis. Plasma amylin was higher in diabetic cats compared with healthy lean cats (P < 0.001). Interestingly, amylin levels during pancreatitis were higher than those of both lean cats (P < 0.0001) and diabetic cats without pancreatitis (P < 0.005). These data support evidence of feline amylin being more prone to aggregation than human amylin in vitro, which may influence diabetes mellitus progression and ß-cell failure in vivo. Furthermore, our data show an increase in amylin levels during feline pancreatitis and the need for future research on the role of this hormone in the pathogenesis of pancreatic inflammation associated to feline diabetes mellitus.

Performance during a strenuous swimming session is associated with high blood lactate: pyruvate ratio and hypoglycemia in fasted rats.

The aim of this study was to investigate the effect of lactatemia elevation and glycemia reduction on strenuous swimming performance in fasted rats. Three rats were placed in a swimming tank at the same time. The first rat was removed immediately (control group) and the remaining ones were submitted to a strenuous swimming session. After the second rat was exhausted (Exh group), the third one was immediately removed from the water (Exe group). According to the period of time required for exhaustion, the rats were divided into four groups: low performance (3-7 min), low-intermediary performance (8-12 min), high-intermediary performance (13-17 min), and high performance (18-22 min). All rats were removed from the swimming tanks and immediately killed by decapitation for blood collection or anesthetized for liver perfusion experiments. Blood glucose, lactate, and pyruvate concentrations, blood lactate/pyruvate ratio, and liver lactate uptake and its conversion to glucose were evaluated. Exhaustion in low and low-intermediary performance were better associated with higher lactate/pyruvate ratio. On the other hand, exhaustion in high-intermediary and high performance was better associated with hypoglycemia. Lactate uptake and glucose production from lactate in livers from the Exe and Exh groups were maintained. We concluded that there is a time sequence in the participation of lactate/pyruvate ratio and hypoglycemia in performance during an acute strenuous swimming section in fasted rats. The liver had an important participation in preventing hyperlactatemia and hypoglycemia during swimming through lactate uptake and its conversion to glucose.

Active surveillance cultures: comparison of inguinal and rectal sites for detection of multidrug-resistant bacteria.

BACKGROUND: Rectal swabs are the most widely used surveillance technique for detecting multidrug-resistant bacteria colonizing the intestinal tract. Obtaining these samples may cause embarrassment and discomfort to patients. Prior studies indicate that perirectal swabs are as sensitive and specific as rectal swabs with greater patient acceptance. AIM: To compare inguinal and rectal swabs for the detection of multidrug-resistant bacteria colonizing the intestinal tract. METHODS: An epidemiological, comparative, prospective, and controlled study was undertaken with 102 Brazilian patients. Inguinal and rectal swabs were collected for culture and compared. FINDINGS: Compared to rectal swabs, the sensitivity and specificity of inguinal swabs was 91.8% and 88.7%, respectively. Even when there were low colony counts from rectal samples, there were more than 100 colonies from inguinal samples. CONCLUSION: The inguinal region can be considered an acceptable alternative for collecting surveillance cultures for multidrug-resistant bacteria colonizing the intestinal tract. The inguinal swab technique is sensitive and specific for assessing multidrug-resistant micro-organisms, less embarrassing for patients, and simple to implement in hospital practice.

Macrophage migration inhibitory factor promotes eosinophil accumulation and tissue remodeling in eosinophilic esophagitis.

Macrophage migration inhibitory factor (MIF) is involved in eosinophil biology and in type 2 inflammation, contributing to allergic and helminthic diseases. We hypothesized that MIF participates in the pathogenesis of eosinophilic esophagitis (EoE), an allergic condition characterized by esophageal eosinophilic inflammation. MIF is highly expressed in esophageal mucosa of patients with EoE, compared with gastro-esophageal reflux disease and control patients, where it co-localizes predominantly with eosinophils. In vitro, recombinant MIF promotes human eosinophil chemotaxis, while MIF antagonist and CXCR4 antagonist, AMD3100, revert this effect. In a model of EoE induced by ovalbumin, Mif-deficient mice have reduced inflammation and collagen deposition compared with wild-type (WT) mice. Importantly, treatment of WT mice with anti-MIF or with AMD3100 during the challenge phase prevents accumulation of eosinophils and tissue remodeling. Conversely, recombinant MIF promoted tissue eosinophil inflammation in allergic mice. Together, these results implicate MIF in the pathogenesis of esophageal inflammation and suggest that targeting MIF might represent a novel therapy for EoE.

[Transport of mucoid mucus in healthy individuals and patients with chronic obstructive pulmonary disease and bronchiectasis]. / Transporte de secreções mucóides de indivíduos saudáveis e pacientes com doença pulmonar obstrutiva crónica e bronquiectasias.

OBJECTIVE: To characterise and compare the in vitro transport properties of respiratory mucoid secretion in individuals with no lung disease and in stable patients with chronic obstructive pulmonary disease (COPD) and bronchiectasis. METHODOLOGY: Samples of mucus were collected, from 21 volunteers presenting no lung disease who had undergone surgery, from 10 patients presenting chronic COPD, and from 16 patients with bronchiectasis. Mucociliary transport (MCT), transport by cough (SCM), and contact angle (CAM) were evaluated. RESULTS: MCT was found to be greater in healthy individuals (1.0±0.19) than in COPD (0.91±0.17) and bronchiectasis (0.76±0.23) patients (p<0.05), whereas SCM was greater in COPD patients (16.31±7.35 cm) than in patients with bronchiectasis (12.16±6.64 cm) and healthy individuals (10.50±25.8 cm) (p<0.05). No significant differences were observed between the groups regarding CAM. CONCLUSION: Mucus from healthy individuals allows better mucociliary transport compared to that from patients with lung diseases. However, the mucus from COPD patients allows a better transport by coughing, demonstrating that these individuals have adapted to a defence mechanism compared to patients with bronchiectasis, who have impairment in their ciliary and cough transport mechanisms.

Spermatogenesis of riffle bugs, Rhagovelia whitei and Rhagovelia sp (Veliidae), and backswimmers Martarega sp (Notonectidae).

We examined the course of spermatogenesis and the meiotic chromosome complements in aquatic species of true bugs, Heteroptera. The chromosome complement of the Veliidae species was 2n = 39 (38A + X0) and 23 (22A + X0) in Rhagovelia whitei and Rhagovelia sp, respectively, and in the species of the Notonectidae (Martarega sp) it was 26 (22A + 2m + XY); all collected from the region of São José do Rio Preto, SP, Brazil. An impressive characteristic of the first analysis was the size of the cells belonging to Martarega sp, which were six times larger than the same cells in Pentatomidae and twice as large as the cells in aquatic Heteroptera (Gerridae). Regarding spermatogenesis, all the species analyzed showed the same pattern: holocentric chromosomes and elongated spermatids with the chromatin distributed evenly along the head. The family Veliidae showed several bodies impregnated with silver nitrate at prophase, while the family Notonectidae displayed only one. The cells of Notonectidae also showed an evident and round body until the end of prophase I and in the family Veliidae the silver-impregnated bodies were disorganized, where the only region visualized was possibly that of the NOR. In metaphase, silver-stained regions were found at the periphery of all chromosomes in Veliidae and at the periphery of some chromosomes in Notonectidae. The spermatids of Veliidae showed a less silver-impregnated vesicle, while Notonectidae showed silver staining only in part of the nuclear membrane. Therefore, families of Heteroptera have some differences and features that can help identify and classify these species.

Morphology and biochemical markers of people living with HIV/AIDS undergoing a resistance exercise program: clinical series.

This descriptive case study aimed at assessing body's composition and impact on biochemical markers of people living with HIV/AIDS (S1=male-1, S2=female-1) undergoing a four-month intervention program of resistance exercises. Was analyzed the lipid profile (total cholesterol, LDL, HDL and triglycerides serum), immunological parameters (CD4 and viral load/VL) and morphological parameters (body mass index BMI, waist/Hip/WHR, perimeters and skinfold). Blood samples and antropometric measures were obtained in the pre-exercise (pre-test) and immediately after (16 weeks) of exercise (post-test). An increase in HDL (38 pre, 42 post), LDL (89.6 pre, 95 post) was noted for S1 and a decrease in HDL (33 pre, 25 post) and LDL (121.6 pre, 121 post) for S2; a decrease in Triglyceride for S1 (292 pre, 214 post) and increase for S2 (102 pre, 166 post). Total cholesterol increased for both subjects (186 pre, 261 post S1 and 175 pre, 179 post S2). there was a decrease in CD4 for S1 (598 pre, 577 post) and an increase for S2 (748 pre, 1.071 post). With respect to viral load, we found that both subjects (S1 and S2) presented values below the minimum limit (pre and post test), with no significant changes. Body composition improved (LMpre S1=43.13% and S2=23.35% and LMpost S1=46.51 and S2=26.15%; BFpre S1=41.13 and S2=18.14% and BFpost S1=38.32 and S2=14.77%), as did BMI (25.27 pre, 27.44 post S1) and (24.24 pre, 24.74 post S2). The resistance exercise program as base in this intervention model promoted a healthy state for HIV and AIDS patients and did not pose any health risks to them.

Modified-release recombinant human TSH (MRrhTSH) augments the effect of (131)I therapy in benign multinodular goiter: results from a multicenter international, randomized, placebo-controlled study.

BACKGROUND: Recombinant human TSH (rhTSH) can be used to enhance (131)I therapy for shrinkage of multinodular goiter (MG). OBJECTIVE, DESIGN, AND SETTING: The objective of the study was to compare the efficacy and safety of 0.01 and 0.03 mg modified-release (MR) rhTSH as an adjuvant to (131)I therapy, vs. (131)I alone, in a randomized, placebo-controlled, international, multicenter study. PATIENTS AND INTERVENTION: Ninety-five patients (57.2 ± 9.6 yr old, 85% females, 83% Caucasians) with MG (median size 96.0, range 31.9-242.2 ml) were randomized to receive placebo (group A, n = 32), MRrhTSH 0.01 mg (group B, n = 30), or MRrhTSH 0.03 mg (group C, n = 33) 24 h before a calculated activity of (131)I. MAIN OUTCOME MEASURES: The primary end point was a change in thyroid volume (by computerized tomography scan, at 6 months). Secondary end points were the smallest cross-sectional area of the trachea; thyroid function tests; Thyroid Quality of Life Questionnaire; electrocardiogram; and hyperthyroid symptom scale. RESULTS: Thyroid volume decreased significantly in all groups. The reduction was comparable in groups A and B (23.1 ± 8.8 and 23.3 ± 16.5%, respectively; P = 0.95). In group C, the reduction (32.9 ± 20.7%) was more pronounced than in groups A (P = 0.03) and B. The smallest cross-sectional area of the trachea increased in all groups: 3.8 ± 2.9% in A, 4.8 ± 3.3% in B, and 10.2 ± 33.2% in C, with no significant difference among the groups. Goiter-related symptoms were effectively reduced and there were no major safety concerns. CONCLUSION: In this dose-selection study, 0.03 mg MRrhTSH was the most efficacious dose as an adjuvant to (131)I therapy of MG. It was well tolerated and significantly augmented the effect of (131)I therapy in the short term. Larger studies with long-term follow-up are warranted.

Nutritional vitamin A status in northeast Brazilian lactating mothers.

BACKGROUND: Vitamin A deficiency is the major cause of morbidity and mortality among children and in women of reproductive age in developing countries. The present study aimed to assess maternal nutritional vitamin A status, as well as analyse the association of preformed vitamin A and pro-vitamin A consumption on the nutritional status of nursing mothers, based on serum retinol and retinol colostrum concentrations coupled with dietary intake. METHODS: Serum and colostrums were collected from 86 healthy parturients, recruited within 16 h postpartum. Blood samples were obtained, the morning after an overnight fast. Retinol was analysed by high-performance liquid chromatography. Dietary vitamin A was assessed using a food frequency questionnaire and the women were separated into two groups according to the predominant dietary source of vitamin A: group A, > 50% preformed vitamin A (n = 37); and group B > 50% pro-vitamin A carotenoids, (n = 49). RESULTS: Serum retinol and total vitamin A ingestion (mean +/- SD) were higher in group A than in group B (1.4 +/- 0.4 micromol L(-1) and 2072.0 +/- 1465.9 microg retinol activity equivalent (RAE) day(-1) versus 1.2 +/- 0.6 micromol L(-1) and 1051.6 +/- 920.4 microg RAE day(-1), respectively (P < 0.05), but colostrum retinol (3.4 +/- 1.7 micromol L(-1) and 3.6 +/- 1.9 micromol L(-1)) was similar in both groups. In group B, 36.7% (n = 18) of the nursing mothers presented a risk of developing vitamin A deficiency, based on their dietary intake. CONCLUSIONS: On the basis of the intake of the pro-vitamin A carotenoids, some women may be at risk of vitamin A deficiency. However, their status is currently normal, as indicated by serum and milk retinol concentrations.

Increased endothelin-1 reactivity and endothelial dysfunction in carotid arteries from rats with hyperhomocysteinemia.

BACKGROUND AND PURPOSE: There are interactions between endothelin-1 (ET-1) and endothelial vascular injury in hyperhomocysteinemia (HHcy), but the underlying mechanisms are poorly understood. Here we evaluated the effects of HHcy on the endothelin system in rat carotid arteries. EXPERIMENTAL APPROACH: Vascular reactivity to ET-1 and ET(A) and ET(B) receptor antagonists was assessed in rings of carotid arteries from normal rats and those with HHcy. ET(A) and ET(B) receptor expression was assessed by mRNA (RT-PCR), immunohistochemistry and binding of [(125)I]-ET-1. KEY RESULTS: HHcy enhanced ET-1-induced contractions of carotid rings with intact endothelium. Selective antagonism of ET(A) or ET(B) receptors produced concentration-dependent rightward displacements of ET-1 concentration response curves. Antagonism of ET(A) but not of ET(B) receptors abolished enhancement in HHcy tissues. ET(A) and ET(B) receptor gene expressions were not up-regulated. ET(A) receptor expression in the arterial media was higher in HHcy arteries. Contractions to big ET-1 served as indicators of endothelin-converting enzyme activity, which was decreased by HHcy, without reduction of ET-1 levels. ET-1-induced Rho-kinase activity, calcium release and influx were increased by HHcy. Pre-treatment with indomethacin reversed enhanced responses to ET-1 in HHcy tissues, which were reduced also by a thromboxane A(2) receptor antagonist. Induced relaxation was reduced by BQ788, absent in endothelium-denuded arteries and was decreased in HHcy due to reduced bioavailability of NO. CONCLUSIONS AND IMPLICATIONS: Increased ET(A) receptor density plays a fundamental role in endothelial injury induced by HHcy. ET-1 activation of ET(A) receptors in HHcy changed the balance between endothelium-derived relaxing and contracting factors, favouring enhanced contractility.

Risk factors for surgical site infection after surgery for esophageal perforation.

Esophageal perforations carry a high potential for morbidity and mortality. The prognosis depends on rapid and precise diagnosis and management. Surgical site infections (SSIs) are very common following the surgical treatment of esophageal lesions. We aimed identify significant risk factors for SSI after surgery for esophageal perforation via an historical cohort study including patients who underwent surgical management of esophageal perforation. The predictive variables were analyzed by bivariate analysis and multiple logistic regression. Eighty-one patients were studied during a 10-year period ending in 2004. The mean age was 42.6 years. In 44% of the patients the time interval between the perforation and surgery was up to 6 h and in 30% it was > 24 h. Associated lesions occurred in other cavities; 17% in the chest, 5% in the abdomen, 5% in the extremities, 4% in the spinal column and bone marrow and 2% in the face. There were grade I lesions in eight cases (10%), grade II in 64 cases (79%) and grade III in nine cases (11%). The mean time of surgery procedure was 117.2 min. The mean SSI was 7.99. SSIs occurred in 33 patients (41%). The risk factors for SSI following surgical management of esophageal perforation were: age > or = 50 years, time delay to treatment > 24 h, associated lesion in another cavity and Injury Severity Score > or = 15.

The balloon catheter induces an increase in contralateral carotid artery reactivity to angiotensin II and phenylephrine.

1. The effects of balloon injury on the reactivity of ipsilateral and contralateral carotid arteries were compared to those observed in arteries from intact animals (control arteries). 2. Carotid arteries were obtained from Wistar rats 2, 4, 7, 15, 30 or 45 days after injury and mounted in an isolated organ bath. Reactivity to angiotensin II (Ang II), phenylephrine (Phe) and bradykinin (BK) was studied. Curves were constructed in the absence or presence of endothelium or after incubation with 10 microm indomethacin, 500 microm valeryl salicylate or 0.1 microm celecoxib. 3. Phe, Ang II and BK maximum effects (Emax) were decreased in ipsilateral arteries when compared to control arteries. No differences were observed among pD2 or Hill coefficient. 4. Emax to Phe (4 and 7 days) and to Ang II (15 and 30 days) increased in the contralateral artery. In addition, Phe or Ang II reactivity was not significantly different in aorta rings from control or carotid-injured animals. 5. The increased responsiveness of contralateral artery was not due to changes in carotid blood flow or resting membrane potential. The endothelium-dependent inhibitory component is not present in the contraction of contralateral arteries and it is not related to superoxide anion production. 6. Indomethacin decreased contralateral artery responsiveness to Phe and Ang II. Valeryl salicylate reduced the Ang II response in contralateral and control arteries. Celecoxib decreased the Phe Emax of contralateral artery. 7. In conclusion, decreased endothelium-derived factors and increased prostanoids appear to be responsible for the increased reactivity of contralateral arteries after injury.

Rat liver responsiveness to gluconeogenic substrates during insulin-induced hypoglycemia.

Hepatic responsiveness to gluconeogenic substrates during insulin-induced hypoglycemia was investigated. For this purpose, livers were perfused with a saturating concentration of 2 mM glycerol, 5 mM L-alanine or 5 mM L-glutamine as gluconeogenic substrates. All experiments were performed 1 h after an ip injection of saline (CN group) or 1 IU/kg of insulin (IN group). The IN group showed higher (P<0.05) hepatic glucose production from glycerol, L-alanine and L-glutamine and higher (P<0.05) production of L-lactate, pyruvate and urea from L-alanine and L-glutamine. In addition, ip injection of 100 mg/kg glycerol, L-alanine and L-glutamine promoted glucose recovery. The results indicate that the hepatic capacity to produce glucose from gluconeogenic precursors was increased during insulin-induced hypoglycemia.

Oxidative stress as a signaling mechanism of the vascular response to injury: the redox hypothesis of restenosis.

The prominent role of redox processes in tissue injury and in vascular cell signaling suggest their involvement in the repair reaction to vessel injury, which is a key determinant of restenosis post-angioplasty. Experimental studies showed a protective effect of superoxide dismutase or antioxidants on vasospasm, neointimal thickening or remodeling after balloon injury. It was also shown that oxidized thiols induce chelatable metal-dependent amplification of the vascular repair reaction. Ongoing or completed clinical trials show a promising effect of the antioxidant probucol against restenosis. However, few studies addressed the molecular physiological mechanisms underlying the redox hypothesis of restenosis. We recently showed evidence for marked oxidative stress early after balloon injury, with superoxide production mediated primarily by non-endothelial NAD(P)H oxidase-type flavoenzyme(s). This effect was closely related to the degree of injury. There is evidence supporting a role for such early redox processes in apoptotic cell loss and NF-kappa B activation. We present new data on the time course of oxidative stress after balloon injury of intact rabbit iliac arteries. Our data show that despite substantial neointimal growth and lumen narrowing, superoxide production and glutathione levels are unaltered at day 14 and 28 after balloon injury. At day 7 after injury, the peak neointimal proliferation in this model, there was significant decrease of vascular superoxide dismutase activity, without clear evidence of spontaneous superoxide production. Thus, oxidative stress after injury is likely to be an early transient event, which parallels the inflammatory and proliferative phases of the vascular response. We propose that such early redox processes act as dose-dependent signal transducers of gene programs that affect the final repair.

Small-bowel involvement in systemic lupus erythematosus: a morphometric and immunohistochemical study.

BACKGROUND: We have investigated the intestinal mononuclear cell subpopulations in patients with systemic lupus erythematosus (SLE) and correlated these with the disease activity. METHODS: Eighteen female outpatients were studied; in 10 of them lupus activity was measured with the Lupus Activity Criteria Count and the SLE Disease Activity Index. Eight patients were in lupus remission. The control group consisted of 10 healthy volunteers. Peroral jejunal biopsy was performed in all individuals, at the angle of Treitz, using a Watson capsule, under X-ray control. Histologic studies analysed the villous to crypt ratio, lamina propria cells, and intraepithelial lymphocyte count. Immunohistochemical evaluation was carried out with the indirect immunoperoxidase technique, using monoclonal antibodies against CD3, CD4, CD8, D1, D7, D9, and M1. RESULTS: Lamina propria CD3+, CD8+, D7+, and M1+ cells from patients with SLE did not differ significantly from those of controls. CD4+ cells were decreased in all patients with SLE, especially in the clinically inactive patients. D1+ and D9+ cells were also decreased in all patients. CONCLUSION: The finding of quantitative abnormalities in the cell-mediated immunity of the intestinal mucosa may reflect systemic defects of the immune system in SLE.

[Technologic features in the working process in nurseries]. / Características tecnológicas do processo de trabalho em berçários.

The relationship established between health professionals and newborns is analysed in this study. The research focuses mainly on the fact that this interaction is mediated by scientific knowledge, technology and the equipment used on the care of babies. This is a exploratory qualitative research. The data was collected in two nurseries in the city of Ribeirão Preto, SP, Brazil. It was verified that the procedures used in these nurseries fulfilled the necessities of newborns regarding the control and maintenance of vital functions (cardio-respiratory, thermoregulation, oxygenation, fluid-electrolyte balance and nutrition), as well as the administration of medicines, and collection of organic material for diagnosis and therapy. It was also observed that nursery professionals prepare, install, control and do the maintenance of the equipment, while doctors are in charge of installing and controlling it in more invasive procedures.

Clinical patterns of diarrhea in AIDS. A retrospective study at the Federal University Hospital, Rio de Janeiro.

Three hundred and fifty two medical records of AIDS inpatients were analysed in a retrospective study to establish the frequency, clinical patterns and etiology of AIDS-related diarrhea. Diarrhea was observed in 58.8% of the patients, being a chronic symptom in 65.7%, and the first complaint in 24.6%. The most common cause of diarrhea was coccidea and the etiology remained unknown in 56.1% of the patients. Routine stool examination was the most sensitive method in the diagnosis of diarrhea. In countries with limited resources, the use of stool examinations seems to provide appropriate clinical management. The implementation of an objective protocol could improve the etiologic diagnosis of AIDS-related diarrhea without the burden of more complex and invasive technologies.

Changes in glycemia induced by exercise in rats: contribution of hepatic glycogenolysis and gluconeogenesis.

The participation of hepatic glycogenolysis and gluconeogenesis to the glycemic changes promoted by exercise was investigated. For this purpose, we employed swimming rats (2.5% body weight extra load attached to the tail, at 24 degrees C) using a favorable condition to measure hepatic glycogenolysis (fed rats) and a favorable condition to measure hepatic gluconeogenesis (fasted rats). This experimental approach permits us to compare the contribution of hepatic glycogenolysis and gluconeogenesis to glucose changes for a specific schedule of exercise. The animals were investigated at rest, after 5 minutes of swimming and after swimming to exhaustion. Our results show that hepatic glycogen has a crucial role to determine hyperglycemia during exercise. In contrast, hypoglycemia developed during exercise when glycogen was depleted. However, the ability of the liver to produce glucose from L-lactate, glycerol and L-glutamine was increased during exercise. Taken together, these findings suggest that the hepatic capacity to produce glucose from gluconeogenic substrates (except for L-alanine) was increased when hepatic glycogen stores were depleted. Thus, the increased capacity to produce glucose shown by livers from exercising rats must to be an important metabolic adaptation to protect against severe hypoglycemia.