Belgin Buyukakilli

No effect of GA-AS (904 nm) laser irradiation on the intact skin of the injured rat sciatic nerve

AbstractWe evaluated the electrophysiological and histopathological effects of low-energy gallium arsenide (904 nm) laser irradiation on the intact skin injured rat sciatic nerve. Twenty-four male Wistar rats were divided into three groups (n=8 each). At the level of proximal third of the femur the sciatic nerve was crushed bilaterally with an aneursym clip (Aesculap FE 751, Tuttingen, Germany) for half a second. A gallium arsenide laser (wavelength 904 nm, pulse duration 220 ns, peak power per pulse 27 W, spot size 0.28 cm2, pulse repetition rate 16, 128 and 1000 Hz; total applied energy density 0.31, 2.48 and 19 J/cm2) was applied to the right sciatic nerve for 15 min daily at the same time on 7 consecutive days. The same procedure was performed on the left sciatic nerve of same animal, but without radiation emission, and this was accepted as control. Compound muscle action potentials were recorded from right and left sides in all three groups before surgery, just at the end of injury, at the 24th hour and on the 14th and 21st days of injury in all rats using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara, USA). BIOPAC Acknowledge Analysis Software (ACK 100 W) was used to measure CMAP amplitude, area, proximal and distal latency, total duration and conduction velocity. Twenty-one days after injury, the rats were sacrificed. The sciatic nerves of the operated parts were harvested from the right and left sides. Histopathological evaluation was performed by light microscopy. Statistical evaluation was done using analysis of variance for two factors (right and left sides) repeated-measures (CMAP variables within groups) and the Tukey–Kramer Honestly Significant Difference test (CMAP variables between laser groups). The significance was set at p ≤ 0.05. No statistically significant difference (p ≥ 0.05) was found regarding the amplitude, area, duration and conduction velocity of CMAP for each applied dose (0.31, 2.48 and 19 J/cm2) on the irradiated (right) side and the control (left) side, or between irradiated groups. Twenty-one days after injury there were no qualitative differences in the morphological pattern of the regenerated nerve fibres in either irradiated (0.31, 2.48 and 19 J/cm2) or control nerves when evaluated by light microscopy. This study showed that low-energy GaAs irradiation did not have any effect on the injured rat sciatic nerve.

Protective and therapeutic effects of swimming exercise training on diabetic peripheral neuropathy of streptozotocin-induced diabetic rats

Background: Diabetic peripheral neuropathy (DPN) is a typical complication of diabetes. No definitive treatment and prevention of DPN has been established, and very few data on the role of exercise training on DPN have been reported. Aim of the study: The protective and therapeutic effects of aerobic physical activity on the development of DPN in Type 1 were investigated. Methods: Rats were assigned to 5 groups: C (control), E (exercise), D (diabetic), DEx (exercise after diabetic), ExD (diabetic after exercise); C containing 10 animals and E, D, DEx, ExD containing 15 animals. Diabetes was induced with streptozotocin (STZ) (45 mg/kg, ip). Development of diabetes was confirmed by measuring blood glucose levels 2 days after STZ treatment. Body weights of all the animals were evaluated weekly throughout the experiment. Motor dysfunction defined by a significant increase in compound muscle action potential (CMAP) latency was recorded. The amplitude of CMAP which mainly reflects axonal dysfunction was also measured using standard techniques. Sciatic nerve morphometry and blood glucose levels were analyzed in all the groups. Results: Blood glucose level significantly increased 2 days after STZ injection. All diabetic rats showed decreased body weight compared to control rats. An increase in motor latency of CMAP and a decrease in amplitude of CMAP, indicative of neuropathy, were seen in STZ rats. On the completion of the study (the 56th day post-STZ), histological examination revealed significant myelin loss (thinner myelin) in sciatic nerves of STZ rats. Treatment with swimming exercise had no effect on glycemic control but restored body weight, CMAP amplitude, CMAP latency or motor dysfunction in the diabetic animals. Conclusions: This study suggests that swimming exercise training has protective and therapeutic effects on DPN of STZ-induced diabetic rats.

Acute Electrophysiological Effect of Pulsed Gallium–Arsenide Low-Energy Laser Irradiation on Isolated Frog Sciatic Nerve

We evaluated the acute electrophysiological effects of low-energy pulsed laser irradiation on isolated frog sciatic nerve measured by extracellular recording technique. A pulsed gallium–arsenide (GaAs) laser (wavelength: 904 nm, pulse duration 220 ns, peak power per pulse: 27 W, spot size: 0.28 cm2, total applied energy density: 0.005–2.5 J/cm2) was used for the experiment. Sixty isolated nerves were divided into six groups (n=10), each of which received a different laser dose. In each group, action potentials were recorded before laser irradiation which served as the control data. The extracellular action potentials were recorded for each combination of 1, 3, 5, 7, 10, 13 and 15 minutes of irradiation time and 4, 8, 16, 32, 64 and 128 repetition frequency by using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara, USA). Action potential amplitude, area, duration and conduction velocity were measured. Statistical evaluation was performed using repeated measures variance analysis by SPSS 9.0. There were no statistically significant differences for action potential amplitude, area and conduction velocity among the laser groups and control data (p>0.05). The study showed that low-energy GaAs irradiation at 4–128 Hz repetition frequencies administered for irradiation times of 1–15 min generates no effect on action potential amplitude, area, duration and conduction velocity in isolated frog sciatic nerve.

Assessment of Cadmium Genotoxicity in Peripheral Blood and Bone Marrow Tissues of Male Wistar Rats

In this study, Cadmium (Cd) genotoxicity was investigated in both bone marrow and peripheral blood treatment using rat micronucleus technique as genotoxicity test at acute and chronic treatment in the same animals. This study evaluated the frequency of micronuclei in the peripheral blood and bone marrow of male rats treated with unique cadmium dose (15 mg/kg. body w/day) by gavage for 60 days and acute treatment for 24 h, respectively. Mitomycin C (MMC) 2 mg/kg body wt was used as a positive control. This study shows that cadmium chloride treatment significantly induced the frequency of micronucleus in polychromatic erythrocytes in both tibia bone marrow and peripheral blood (p < 0.001, p < 0.01, respectively). This increase in micronucleus frequency shows that cadmium has a genotoxic effect on bone marrow and peripheral blood at this level. Also, in order to determine cytotoxicity in bone marrow and peripheral blood, the ratio of polychromatic erythrocytes to normochromatic erythrocytes was calculated in bone marrow and peripheral blood. Cd treatment decreased this ratio in only bone marrow. The results of this study demonstrate that Cd has both toxic and genotoxic potential in bone marrow and only genotoxic potential in peripheral blood. There is a significant difference between the control group and exposed group, including acute and chronic treatment for blood Cd level (p < 0.001). No significant difference was found between acute and chronic exposure group (p > 0.05).

Determination of acute and chronic effects of cadmium on the cardiovascular system of rats

In this study, the systemic hemodynamics induced by acute and chronic cadmium (Cd+2) intoxication in the cardiovascular system of rats using thoracic electrical bioimpedance were examined and the acute and chronic effects of Cd+2 intoxication on the activities of antioxidant enzymes and malondialdehyde (MDA) were compared. Also, in this study, ultrastructural changes in the heart and aorta of rats were evaluated. Thirty-eight male Wistar albino rats were randomly divided into control, acute, and chronic groups. Chronic group was administered by oral gavage an aqueous solution of CdCl2 for 60 days, at dose of 15 mg Cd+2/kg/day. Acute group was administered by oral gavage an aqueous solution of CdCl2 with a single dose of 15 mg Cd+2/kg. Cadmium increased the stroke volume and cardiac output of rats in the chronic group, but did not change the heart rate significantly. Antioxidant enzymes activities and MDA level significantly increased in the chronic group. In ultrastructural examination, there were widespread degenerative changes in heart muscle cells of the chronic group but endothelial cells and smooth muscle cells in the aorta tissue samples had normal morphological features in all groups. All of the findings indicate that Cd+2 toxication can cause deformation in heart muscle cells due to an increase in free radicals and lipid peroxidation. Also, this study has confirmed that a long-term-Cd+2 exposure increased stroke volume (SV) and cardiac output (CO), but did not change the heart rate (HR).

The Effect of Preventive Use of Alanyl-Glutamine on Diaphragm Muscle Function in Cecal Ligation and Puncture-Induced Sepsis Model

BACKGROUND Low muscle glutamine levels during sepsis are associated with reduced protein synthesis and elevated protein breakdown, in particular myofibrillar protein breakdown. Thus, in a cecal ligation and puncture (CLP)-induced sepsis model in the rat, we hypothesized that glutamine pretreatment would protect the diaphragm muscle function. METHODS Eighty-four male Wistar rats weighing between 180 g and 200 g received standard amino acid solution 1.2 g kg(-1) per day intraperitoneally (IP) or standard amino acid solution 1.2 g kg(-1) per day plus alanyl-glutamine (GLN) 0.25 g kg(-1) per day (IP) during the first 6 days of the experiment. On the seventh day, CLP or sham procedures were applied. The sham and CLP groups were equally divided into 3 subgroups according to the termination of the experiment, which took place at either the 24th hour, 48th hour, or 72nd hour. After the compound muscle action potentials (CMAP) were recorded from the diaphragms of the rats at these selected times, they were decapitated under ketamine/xylazine anesthesia, and diaphragms were harvested for biochemical and histopathological examination. RESULTS The mean area and amplitude of CMAP were significantly larger in sham+GLN groups when compared with CLP and CLP+GLN groups at all times (p < .05). Diaphragm Ca+2 -ATPase levels were found to be significantly decreased in CLP group at all times compared to sham groups (p < .05). Diaphragm reduced glutathione levels were significantly higher in sham+GLN groups when compared with CLP and CLP+GLN groups at all times (p < .05). In histopathologic assessment, moderate neutrophil infiltration, which was observed in CLP48, was significantly reduced with alanyl-glutamine supplementation in CLP+GLN48 group (p < .05). CONCLUSIONS This study showed that glutamine pretreatment did not improve diaphragm muscle function, but prevented the biochemical and histopathological changes in diaphragmatic muscle in CLP-induced sepsis. However, further studies are needed to clarify whether a higher dose of glutamine supplementation might protect the diaphragmatic muscle functions.

Reversible conduction block in isolated frog sciatic nerve by high concentration of bupivacaine

We evaluated the effects of a high concentration of bupivacaine commonly used for spinal anaesthesia on the reversibility of conduction block and compound nerve action potential (CNAP) parameters in isolated frog sciatic nerve measured by extracellular recording technique. Isolated frog sciatic nerves were bathed in 1.3% bupivacaine solution for 20 min. In each nerve, action potentials were recorded before exposure to bupivacaine solution, which served as the control data. The extracellular action potentials were recorded after 20 min in the drug by using a BIOPAC MP 100 Acquisition System Version 3.5.7 (Santa Barbara, USA). The nerves were washed for 3h continuously with Ringers solution and action potentials were recorded. The nerve was then soaked overnight in Ringers solution at room temperature and tested for impulse recovery. There were significant differences among the experiments regarding CNAP peak-to-peak amplitude, area and duration but conduction velocities among the experiments did not show any statistical difference. In the presence of bupivacaine the extracellular action potential amplitude decreased by 46.99+/-29.31% relative to the control amplitude (P<0.05), recovered to 47.10+/-26.90% after 3h of wash, and reached 123.20+/-39.70% after the overnight soak process. This study showed that exposing nerve to high concentration of bupivacaine causes reversible impulse blockade and that bupivacaine does not cause neurotoxic effect on isolated frog sciatic nerve.

The effect of tumor necrosis factor-α inhibitor soon after hypoxia-ischemia on heart in neonatal rats

AIMS Perinatal hypoxic-ischemic insult has acute and long term deleterious effects on many organs including heart. Although tumor necrosis factor alpha (TNF-α) has been reported to increase soon after hypoxia, the inhibition of this mediator has not been documented. The aim of this study was to investigate the effects of a TNF-α inhibitor (etanercept) on contractility and ultrastructure of rat heart muscles exposed to hypoxia-ischemia during neonatal period. MAIN METHODS Forty-five seven-day old rats divided into three groups were included in this study. The right carotid arteries of Saline and Etanercept groups of rats were ligated and kept in a hypoxia chamber containing 8% oxygen for 2h. Immediately after hypoxia, while Etanercept group was administered 10mg/kg etanercept, Saline group had only saline intraperitoneally. The carotid arteries of rats in Sham group were located without ligation and hypoxia. Mechanical activity of heart was recorded and tissue samples were examined by electron microscopy in the sixteenth week following the hypoxia-ischemia. KEY FINDINGS While atrial contractile force in Etanercept group was similar to Sham group, there was significant decrease in Saline group (p<0.001). However, there was only non-significant decrease in ventricular contractility of Saline group comparing to Sham group (p>0.05). After hypoxia-ischemia, ultrastructural degenerative changes and mitochondrial damage in atriums of Etanercept group were significantly less severe than Saline group. SIGNIFICANCE This study demonstrated that neonatal hypoxia-ischemia caused long term cardiac dysfunction and ultrastructural degenerative changes in the heart of rats. TNF-α inhibitor administration soon after hypoxia-ischemia may have heart protective effect.

Determination of the effects of pulmonary arterial hypertension and therapy on the cardiovascular system of rats by impedance cardiography.

Aim To evaluate the effects of bosentan, sildenafil, and combined therapy on the cardiovascular system using impedance cardiography (ICG) in rats with monocrotaline (MCT)-induced pulmonary arterial hypertension (PAH). Methods Seventy male Wistar-albino rats were randomized into five groups. A single dose of MCT was given to all rats, except to the control group. After 4 weeks, bosentan, sildenafil, and combined treatment was started and lasted for 3 weeks. The last group that developed PAH did not receive any medication. Echocardiographic evaluation was performed to determine the PAH development. Thoracic fluid content index (TFCI), stroke volume index (SI), heart rate (HR), cardiac index (CI), and myocardial contractility index (IC) were determined. All procedures were performed at the baseline and after 4 and 7 weeks. Results Echocardiographic parameters showed that the all MCT-injected rats developed PAH. There were no significant inter- and intra-group differences in TFCI, SI, and IC (P > 0.05), but at the 7th week, CI value in the sildenafil-treated PAH rats was significantly higher than in other groups and HR of PAH rats with combined therapy was significantly lower than in other groups. Conclusion PAH did not have an effect on LV function of rats, or if it did, the effect was compensated by physiological processes. Also, sildenafil treatment deteriorated the LV cardiac index.

Clinical and histopathological relationship of sildenafil and bosentan treatments in rats with monocrotaline induced pulmonary hypertension

BACKGROUND Pulmonary arterial hypertension (PAH) is a challenging disorder characterized by increasing pulmonary artery pressure, which is hard to treat. OBJECTIVE This study was aimed to investigate the effects of bosentan, sildenafil and their combination. METHODS Saline or MCT were applied to Wistar rats. By the development of PAH (4th week), MCT-given rats were treated orally with bosentan, sildenafil and combination of sildenafil and bosentan or placebo. ECHO examinations were performed. Tissues obtained from all of the rats were evaluated under an electron microscope. RESULTS Left ventricular end diastolic diameter significantly increased in sildenafil and combined groups. Sildenafil group revealed a significant decrease in RV pressure and wall thickness. Examination of lung revealed a significant amount of connective tissue formation and increase in inflammatory cells in all the groups except controls in the interalveolar septum. Examination of PA revealed an increase in connective tissue volume, hypertrophic changes and expansions in granular endoplasmic reticulum cisternaes in smooth muscle cells in active groups rather than in the controls. Unlike the controls, the examination of the RV revealed an enlargement of the sarcoplasmic reticulum cisternaes in some cells, due to the calcium increase. CONCLUSION Sildenafil and the combined therapy demonstrated to have more impact on pressure and the RV parameters in rats, with lower inflammatory findings in lung tissue (Fig. 6, Ref. 31).