Minimum blood lactate and muscle protein of rats during swimming exercise

Few studies dealing with effort intensity during swimming exercise in rats have been reported in the literature. Recently, with the use of the lactate minimum test (LMT), our group estimated the minimum blood lactate (MBL) of rats during swimming exercises. This information allowed accurate evaluation of the effort intensity developed by rats during swimming exercise. The present study was designed to evaluate the effects of swimming exercise sessions in below, equivalent and above intensities to MBL, on protein metabolism of rats. Adult (90 days) sedentary male Wistar rats were used in the present study. Mean values of MBL, in the present study, were obtained at blood concentration of 6.7 +/- 0.4 mmol/L with a load of 5% bw. The animals were sacrificed at rest (R) or immediately after a single swimming session (30 min) supporting loads below (3.5% bw), equivalent (5.0% bw) and high load (6.5% bw) to AT. Blood samples were collected each 5 min of exercise for lactate determination. Soleus muscle protein synthesis (amount of L-[C-14] fenil alanyn incorporation to protein) and breakdown (tyrosin release) rates were evaluated. Blood lactate concentrations (mmol/L) stabilized with the below (5.4 +/- 0.01) and equivalent (6.4 +/- 0.006) to MBL but increased, progressively, with the high load. There were no differences in protein synthesis (pmol/mg.h) among rest values (65.2 +/- 3.4) and after-exercise supporting the loads below (61.5 +/- 1.3) and the equivalent (60.7+/-1.7) to MBL but there was a decrease with the high load (36.6+/-2.0). Protein breakdown rates (pmol/g.h) increase after exercise supporting the loads below (227.0 +/- 6.1), equivalent (227.9 +/- 6.0) and high (363.6 +/- 7.1) to MBL in relation to the rest (214.3 +/- 6.0). The results indicate the viability of the application of LMT in studies with rats since it detected alterations imposed by exercise.

Is coronary sinus blood oxygen tension behavior determined by myocardial oxygen tension variation during cardiac reperfusion?

The relationship between coronary sinus blood oxygen tension (CSPO 2) and myocardial oxygen tension (MPO 2) variations during cardiac ischemia and reperfusion was studied in anesthetized open-chest dogs. Oxygen tension was measured by a polarographic method. Ischemia resulted in a slightly decreased CSPO 2 and a more pronounced reduction of MPO 2. After reperfusion the CSPO 2 rose rapidly and transiently before it returned gradually to the control level. By contrast, during the recovery period, the MPO 2 increased slowly, with recovery occurring long after the peak of CSPO 2. These data suggest that during the reperfusion phase, the CSPO 2 variation is probably due to opening of the myocardial arteriovenous shunts instead of an increase of flow through the myocardial capillary bed.

Evaluation of platelet number and function and fibrinogen level in patients bitten by snakes of the Bothrops genus.

Platelet function and plasma fibrinogen levels were evaluated in 14 patients, 10 males and 4 females, aged 13-59 years bitten by Bothrops genus snakes. There was a statistical difference (p < 0.05) among plasma fibrinogen levels evaluated 24 and 48 hours after envenomation. There was a tendency towards normalization after 48 hours of treatment. The low platelet number was clear in 24-48 hour evaluations with a tendency towards normalization after 48 hours of treatment (p < 0.05). When platelet function was stimulated by collagen and epinephrine, it appeared to be within normal values. On the other hand, when it was stimulated by adenosine diphosphate (ADP), platelet function was hypoaggregated by a single micromol concentration until 48 hours after treatment. At a 3 micromol concentration, there were alterations only before specific treatment (p < 0.05). Fibrinogen levels and fibrin degradation product (FDP) levels appeared to be altered in 83.33% of patients evaluated. The authors suggest that platelet hypoaggregation is related to decreased fibrinogen and increased FDP levels.

Effects of simvastatin on bone regeneration in the mandibles of ovariectomized rats and on blood cholesterol levels.

The purpose of this study was to evaluate the effects of simvastatin on guided bone regeneration in the mandibles of ovariectomized rats, and to observe their blood cholesterol levels. Seventy female rats were divided into two groups: control and treated, both groups containing normal and ovariectomized rats. A month after ovariectomy a bone defect was created in the mandible, and was covered by a polytetrafluoroethylene membrane. The treated groups received simvastatin orally for 15 or 30 days. The rats were sacrificed 15, 30 or 60 days after surgery, at which time a blood sample was extracted for blood cholesterol level analysis and the mandible was extracted for densitometric, histological and morphometric analysis. All specimens underwent analysis of variance. The ovariectomized animals had higher cholesterol levels than the treated normal animals, and no significant difference was found between the different treatment periods and the sacrifice times. The densitometric, histological and morphometric analysis showed that the treated ovariectomized animals developed more new bone than the control ovariectomized rats, but no significant difference was observed between the treatment periods. It can be concluded that the deficiency of estrogen increased the level of blood cholesterol and that the simvastatin aided new bone formation in the ovariectomized animals.

Progression of liver fibrosis in blood donors infected with hepatitis C virus

Background/Aims. Chronic hepatitis by HCV is progressive towards cirrhosis, with variable rate. We evaluated the rate of fibrosis progression (RFP), risk factors associated with advanced fibrosis (F3 and F4), and estimated the evolution time to cirrhosis. Methods. We transversely selected 142 blood donors infected only with HCV, with a known route of infection, submitted to liver biopsy at admission. RFP= ratio between stage of fibrosis (METAVIR)/estimated duration of infection in years. Non-parametric tests and logistic regression analysis, with significance level of 5% were used. Results. Median RFP was 0.086 U/year (0.05 - 0.142). Ten patients had F4 and 25 had F3. Median RFP values were significantly different (p=0.001) from one age group at contamination to the others and ALT and AST levels. There were no differences in the expected evolution to cirrhosis between intermediate fibrosers (F2) and the rapid fibrosers (F3 and F4). The independent variables associated with advanced fibrosis were ALT (OR 7.2) and GGT (OR 6.4) and age at inclusion (OR 1.12). Conclusion. This study suggests that RFP is extremely variable, it is exponential with age, and mainly influenced by host characteristics, especially age at contamination and possibly ethnical group. These asymptomatic patients had high percentage of fibrosis F2, F3 and F4.

Responses of blood lactate concentration in aerobic and anaerobic training protocols at different swimming exercise intensities in rats

A swimming periodized experimental training model in rats in which different training protocols (TP) were classified in aerobic (A) and anaerobic (AN) intensity levels. The purpose of the present study was to verify if the classification of the TP used in the periodized training experimental model presented the blood lactate concentration [La] response adequate to the aerobic and anaerobic intensities levels. Twenty three male Wistar rats were divided into three groups. Two groups of swimming training (continuous, CT, n = 7, and periodized training, PET, n = 7) rats were evaluated during 5 weeks in eight different TP (TP-1 to TP-8) through the analysis of the [La] response. The third group was the sedentary control (SC, n = 9). The TP were classified in five intensity levels, three aerobic (A-1, A-2, A-3) and two anaerobic (AN-1, AN-2). Analysis of variance (ANOVA one-way, P<0.05) indicated significant differences in the [La] among the TP and among the five intensity levels. All TP of the A-2 and A-3 intensity levels differed from the A-1 and AN-1. The A-1 and AN-1 also differed among them. These findings demonstrate that the TP were classified properly at different levels of aerobic and anaerobic intensities, as based on the [La] response in a way similar to that of high performance swimming with humans. The results offer new perspectives for the study of exercise training in swimming rats at different levels intensity for performance or for health.

Effect of instrumentation using curettes, piezoelectric ultrasonic scaler and er,cr:Ysgg laser on the morphology and adhesion of blood components on root surfaces - A SEM study

This study used scanning electron microscopy (SEM) to evaluate the morphology and adhesion of blood components on root surfaces instrumented by curettes, piezoelectric ultrasonic scaler and Er,Cr:YSGG laser. One hundred samples from 25 teeth were divided into 5 groups: 1) Curettes; 2) Piezoelectric ultrasonic scaler; 3) Curettes plus piezoelectric ultrasonic scaler; 4) Er,Cr:YSGG laser; 5) Curettes plus Er,Cr:YSGG laser. Ten samples from each group were used for analysis of root morphology and the other 10 were used for analysis of adhesion of blood components on root surface. The results were analyzed statistically by the Kruskall-Wallis and Mann-Whitney tests with a significance level of 5%. The group treated with curettes showed smoother surfaces when compared to the groups were instrumented with piezoelectric ultrasonic scaler and the Er,Cr:YSGG laser. The surfaces instrumented with piezoelectric ultrasonic scaler and Er,Cr:YSGG laser, alone or in combination with hand scaling and root planing, did not differ significantly (p>0.05) among themselves. No statistically significant differences (p>0.05) among groups were found as to the adhesion of blood components on root surface. Ultrasonic instrumentation and Er,Cr:YSGG irradiation produced rougher root surfaces than the use of curettes, but there were no differences among treatments with respect to the adhesion of blood components.

Determinants of blood pressure in type 2 diabetic subjects with high occurrence of inadequate glycemic control

Study design: Association study Objective: To analyze the association between different biological/behavioral risk factors and blood pressure in a sample of type 2 diabetes mellitus patients with poor glycemic control. Methods: A sample of 121 type 2 diabetic patients was selected in the Public Healthcare System in a middle size Brazilian city. Blood pressure was measured using an aneroid device, previously calibrated. Six determinants of blood pressure were taken into count: age, hypoglycemic agents, general obesity, abdominal obesity, eating behaviors and physical activity level. Results: The type 2 diabetic patients presented mean age of 60.1±8.9 years-old and, at least, one risk factor. Eating behaviors (OR adj= 0.31 [0.12-0.75]) and sports practice (OR adj= 0.12 [0.02-0.75]) constituted protective factors associated with lower systolic blood pressure. On the other hand, age was positively associated with high systolic blood pressure (OR adj= 3.81 [1.39-10.38]). Patients with 5-6 risk factors, presented higher values of systolic and (F= 3.857; p= 0.011 [post hoc with p= 0.039]), diastolic blood pressure (F= 4.158; p= 0.008 [post hoc with p= 0.036]) and increased occurrence of hypertension (p= 0.010). Conclusion: Our findings indicate that, behavioral variables were important determinants of blood pressure in type 2 diabetic patients with poor glycemic control and clustering of behavioral and biological risk factors increase the hypertension occurrence.

Dietary intake and blood lipid profile in overweight and obese schoolchildren

Abstract. Background: The high blood lipid levels and obesity are one of the main risk factors for cardiovascular diseases, and the atherosclerotic process begins in childhood. Some environmental factors are supposed to be involved in this relationship, such as dietary factors. This study aimed to investigate the relationship between dietary intake and blood lipids levels in overweight and obese schoolchildren. Methods. This is a cross-sectional study with 147 overweight and obese schoolchildren in Botucatu city, Brazil. The anthropometric measurements (body weight, height, body mass index, waist circumference and skinfolds), pubertal staging evaluation and biochemical tests were taken in all children. Three 24h-recall were applied in order to estimate the dietary intake and its relationship with blood lipid levels. The Student t test and multiple linear regression analysis were used for statistical analysis. Statistical significance was assessed at the level of 0.05. The data were processed in SAS software (version 9.1.3; SAS Institute). Results: At this study, 63% of children were obese (body mass index higher than 95§ssup§th§esup§ percentile) and 80% showed high body fat percentage. The percentage of children with abnormal total cholesterol and triglycerides was 12% and 10%, respectively, and 28% presented at least one abnormal lipid levels. The average values of anthropometric measurements were higher in children with elevated lipid levels. Total cholesterol levels were positively related to full-fat dairy products and triglycerides levels to saturated fat percentage. Conclusions: Saturated fat was positively associated with elevated lipid levels in overweight and obese schoolchildren. These results reinforce the importance of healthy dietary habits since childhood in order to reduce the risks of cardiovascular diseases in adulthood. © 2012 Rinaldi et al.; licensee BioMed Central Ltd.

Blood parameters of chicks from eggs injected with ascorbic acid and subjected to thermal stress

This study was aimed to verify if chicks from eggs injected with ascorbic acid and subjected to thermal stress would have higher immunity than chicks from incubation at thermoneutrality without injection of ascorbic acid. The parameters evaluated were temperature on oxygen saturation in hemoglobin, glucose, number of erythrocytes, hematocrit rate and number of hemoglobins of newly hatched male chicks, hatched from eggs injected with ascorbic acid (AA) and subjected to thermal stress during incubation. The experimental design was completely randomized in factorial scheme 5 (application levels of ascorbic acid) x 2 (incubation temperatures). The data were subjected to analysis of variance using the General Linear Model procedure (GLM) of SAS ®. For the parameters (number of erythrocytes, rate of hematrocit and values of hemoglobin), there was significant interaction (p <0.05) between treatments in egg and incubation temperatures. Analyzing the interactions for these parameters, it was observed that the application of 0% ascorbic acid in egg minimized the effect of heat stress when compared with treatment without injection. The application of ascorbic acid levels in eggs incubated under heat stress failed to maximize the immunity of newly hatched chicks. It is assumed that the increased liquid in the amniotic fluid, in those embryos injected with water, favored the lower heat conductance for these embryos, thus helping in their development in relation to immunity. Considering that hemoglobin is related to the transport of gases, these data suggest that increasing the concentration of AA solution inoculated may influence the respiratory rates of eggs.

Low dose of dichloroacetate infusion reduces blood lactate after submaximal exercise in horses

The acute administration of an indirect activator of the enzyme pyruvate dehydroge-nase (PDH) in human athletes causes a reduction in blood lactate level during and after exercise. A single IV dose (2.5m.kg-1) of dichloroacetate (DCA) was administered before a submaximal incremental exercise test (IET) with five velocity steps, from 5.0 m.s-1 for 1 min to 6.0, 6.5, 7.0 and 7.5m.s-1 every 30s in four untrained mares. The blood collections were done in the period after exercise, at times 1, 3, 5, 10, 15 and 20 min. Blood lactate and glucose (mM) were determined electro-enzymatically utilizing a YSI 2300 automated analyzer. There was a 15.3% decrease in mean total blood lactate determined from the values obtained at all assessment times in both trials after the exercise. There was a decrease in blood lactate 1, 3, 5, 10, 15 and 20 min after exercise for the mares that received prior DCA treatment, with respective mean values of 6.31±0.90 vs 5.81±0.50, 6.45±1.19 vs 5.58±1.06, 6.07±1.56 vs 5.26±1.12, 4.88±1.61 vs 3.95±1.00, 3.66±1.41 vs 2.86±0.75 and 2.75±0.51 vs 2.04±0.30. There was no difference in glucose concentrations. By means of linear regression analysis, V140, V160, V180 and V200 were determined (velocity at which the rate heart is 140, 160, 180, and 200 beats/minute, respectively). The velocities related to heart rate did not differ, indicating that there was no ergogenic effect, but prior administration of a relatively low dose of DCA in mares reduced lactatemia after an IET.

Bone marrow aspirate combined with low-level laser therapy: A new therapeutic approach to enhance bone healing

This study evaluated the influence of bone marrow aspirate (BMA), low-level laser therapy (LLLT) and their combination on bone healing in surgically created critical-size defects (CSDs) in rat calvaria. 40 rats were divided into four groups: C (control), BMA, LLLT and BMA/LLLT. A 5 mm diameter CSD was created in the calvarium of each animal. In Group C, the defect was filled by blood clot only. In Group BMA, the defect was filled with BMA. In groups LLLT and BMA/LLLT, the defect received laser irradiation (InGaAlP laser), was filled with blood clot or BMA respectively, and irradiated again. Animals were euthanized 30 days postoperatively. Histomorphometric and immunohistochemical analyses were performed. Newly formed bone area (NFBA) was calculated as percentage of the total area of the original defect. Proliferating cell nuclear antigen (PCNA), runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) immunohistochemical staining were performed. PCNA-positive, Runx2-positive and OCN-positive cells were quantified. Data were statistically analyzed. Group BMA/LLLT had significantly greater NFBA than groups C, BMA or LLLT. Group BMA presented significantly greater NFBA than control, while group LLLT did not. Group BMA/LLLT presented a significantly higher number of PCNA-positive and OCN-positive cells than any of the other groups. Groups BMA/LLLT and BMA showed a significantly lower number of Runx2-positive cells than groups C or LLLT. The combination of BMA/LLLT yielded significantly greater bone formation in surgically created CSD in rat calvaria when compared to control, or either treatment alone. © 2013 Elsevier B.V. All rights reserved.

Low level laser therapy increases angiogenesis in a model of ischemic skin flap in rats mediated by VEGF, HIF-1α and MMP-2

It is known that low level laser therapy is able to improve skin flap viability by increasing angiogenesis. However, the mechanism for new blood vessel formation is not completely understood. Here, we investigated the effects of 660 nm and 780 nm lasers at fluences of 30 and 40 J/cm2 on three important mediators activated during angiogenesis. Sixty male Wistar rats were used and randomly divided into five groups with twelve animals each. Groups were distributed as follows: skin flap surgery non-irradiated group as a control; skin flap surgery irradiated with 660 nm laser at a fluence of 30 or 40 J/cm2 and skin flap surgery irradiated with 780 nm laser at a fluence of 30 or 40 J/cm2. The random skin flap was performed measuring 10 × 4 cm, with a plastic sheet interposed between the flap and the donor site. Laser irradiation was performed on 24 points covering the flap and surrounding skin immediately after the surgery and for 7 consecutive days thereafter. Tissues were collected, and the number of vessels, angiogenesis markers (vascular endothelial growth factor, VEGF and hypoxia inducible factor, HIF-1α) and a tissue remodeling marker (matrix metalloproteinase, MMP-2) were analyzed. LLLT increased an angiogenesis, HIF-1α and VEGF expression and decrease MMP-2 activity. These phenomena were dependent on the fluences, and wavelengths used. In this study we showed that LLLT may improve the healing of skin flaps by enhancing the amount of new vessels formed in the tissue. Both 660 nm and 780 nm lasers were able to modulate VEGF secretion, MMP-2 activity and HIF-1α expression in a dose dependent manner. © 2013 Published by Elsevier B.V.

Effects of dietary clinoptilolite and calcium levels on uric acid and calcium blood concentrations and bone quality of commercial layers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of Low-Level Laser Therapy on Biceps Braquialis Muscle Fatigue in Young Women

Objective: This study aims to investigate the effects of low-level laser therapy (LLLT) on biceps brachi muscular fatigue in 20 young females. Background data: Exhausting physical activity leads to muscular fatigue, which could decrease muscular strength, and may cause impairment in motor control and muscle pain. Several biochemical and biophysical resources have been studied in an attempt to accelerate the recovery of muscle fatigue. Among these, LLLT is emphasized. Methods: Twenty subjects were randomized in one laser group and one placebo group in two sessions of a crossover design experimental procedure; the second session taking place within 7 days of the first. In the first session, subjects underwent a collection of surface electromyographic (SEMG) data of the biceps brachii muscle, followed by active or placebo LLLT at the same muscle, followed then by another EMG sample of biceps brachii. Blood samples were collected five times during the experimental procedure. Second session procedures were identical to the first, with exception of LLLT, which was the opposite of the first session. The fatigue protocol consisted of 60sec of elbow flexion-extension movement performed with 75% of one maximum repetition. Blood lactate, EMG fatigue, and the number of elbow flexion-extension repetitions during the fatigue protocol were used to evaluate the effects of laser therapy (808nm wavelength, 100mW output power, power density of 35.7 W/cm(2), 70sec each point and 7J/point on eight points). Results: No statistical differences were found for eletromyographic fatigue and blood lactate values between groups. Mean numbers of elbow flexion-extension repetitions were 22.6 +/- 7.58 after placebo, and 25.1 +/- 9.89 after active LLLT group, but these differences were not statistically significant (p=0.342). Conclusions: LLLT had limited effects on delaying muscle fatigue in a young female sample, although a tendency was observed in the active laser group toward showing lower electromyography fatigue of biceps brachii muscle. No intergroup differences were found in the number of muscle contractions and lactate concentration.