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Biomedical subjects

Levent Sinan Bir

Publications and source records attributed to Levent Sinan Bir.

10 recordsLinked to original sources
PubMed2006

Neuroprotective effects of L-carnitine and vitamin E alone or in combination against ischemia-reperfusion injury in rats.

BACKGROUND: Neurological injury because of transient cerebral ischemia is a potential complication of cardiovascular surgery. In this study, the neuroprotective effects of L-carnitine, vitamin E, and the combination of these agents on ischemia/reperfusion (I/R) injury were determined in a rat model of transient global cerebral I/R. METHODS: Rats were pretreated with L-carnitine (100 mg/kg, i.v.) and vitamin E (50 mg/kg, i. v.), alone or in combination and then subjected to cerebral I/R induced by a four-vessel-occlusion technique for a duration of 15 min followed by 15 min of reperfusion. Malondialdehyde (MDA) levels, superoxide dismutase (SOD) activity, and glutathione (GSH) levels were measured in the cerebral tissues. Histopathological examinations were also carried out under light and electron microscopy. RESULTS: The results showed that I/R elevated MDA levels, which were accompanied by a reduction in SOD activities and GSH levels. Surviving neurons was markedly decreased in CA1 and CA3 subfield of hippocampus in I/R animals. L-carnitine, vitamin E, and their combination restored MDA levels and SOD activities, with a tendency to increase surviving neurons in CA1 and CA3 subfield. Combined treatment of L-carnitine and vitamin E had better GSH levels than individual treatment of these agents. CONCLUSIONS: The results suggest that L-carnitine has a potent neuroprotective effect against cerebral-I/R-induced injury in rat brain that is comparable to that of vitamin E. However, the combined use of L-carnitine and vitamin E does not further protect from neuronal injury, although it provides an increase in GSH levels.

Animals↗
PubMed2006

Increased serum malondialdehyde levels in chronic stage of ischemic stroke.

Serum lipoperoxidation products such as malondialdehyde (MDA) reflect oxidative stress. There are contradictory results addressing the levels of lipoperoxidation products in chronic phase of ischemic stroke. In the present study, we aimed to determine the serum MDA levels in stroke patients 6 months after the cerebrovascular accident. We also compared serum MDA levels in two major groups of patients with ischemic stroke resulting from small vessel and large vessel diseases, respectively. Serum MDA levels of thirty-eight patients who had ischemic stroke (19 with atherothrombotic ischemic stroke and 19 with lacunar infarction) and 30 healthy volunteers were measured. While there was no significant difference in serum MDA levels between the chronic ischemic stroke subgroups (p = 0.795), the serum MDA levels of patients with atherothrombotic ischemic stroke (p < 0.001) or with lacunar infarction (p < 0.001) were significantly higher compared to the control group. We also demonstrated that serum MDA levels of the patients with and those without hypertension (p = 0.846), diabetes mellitus (p = 0.891), or dyslipidemia (p = 0.38) were not significantly different. In conclusion, serum MDA levels were elevated in chronic stroke patients with small or large vessel diseases. To the best of our knowledge, this is the first report showing that serum MDA levels of these two groups are not significantly different. Furthermore, serum MDA levels do not differ solely by the existence or nonexistence of hypertension, diabetes mellitus or hyperlipidemia.

Adult↗
PubMed2005

Effects of intrathecal anandamide on somatosensory evoked responses in rats.

Anandamide, endogenous ligand of cannabinoid receptors produces similar effects of cannabinoids via CB1 receptors in the central nervous system. Its effect on ascending pathways of somatosensory conduction and somatosensory cortex is not known. The aim of this study was to determine the effects of anandamide on somatosensory evoked potentials (SEP). In this study, 24 Wistar male rats were used. The rats were divided into 4 groups. At the beginning, sciatic nerve stimulated scalp SEP traces were obtained from all of the rats. Later, 0.02 cm(3) anhydrous ethanol, 100 microg/kg, 200 microg/kg and 400 microg/kg anandamide dissolved in anhydrous ethanol were injected intrathecally to the first (control), second, third and fourth groups, respectively. Five minutes later, second SEP traces were started. In every SEP trace, two negative waves (N1, N2) following positive deflections were obtained. The latency and amplitudes of these waves assessed were compared in each group. In control and second groups, the parameters of these waves before and after the injections were not significantly different. However, in the third and fourth groups, latencies of N1 and N2 after injections were found significantly longer. This effect was dose dependent. In any of the groups, no significant changes were detected in the amplitudes after injections. In conclusion, anandamide, when injected intrathecally in pharmacological doses caused an induction of moderate conduction delay in SEP systems.

Animals↗
PubMed2005

Impaired sympathetic skin response in chronic obstructive pulmonary disease.

The sympathetic skin response (SSR) is considered as one of the indexes of autonomic nervous system functions, especially related with the sudomotor function of unmyelinated sympathetic fibers. SSRs are recorded as the potentials with biphasic or multiphasic waveforms by conventional electromyography. SSRs are evaluated by measuring latency (time from the stimulus to the onset), amplitude, and area (the space under the curve of the waveform). Although dysautonomia is a feature of chronic obstructive pulmonary disease (COPD), as demonstrated by acetylcholine sweat-spot test, there are no data concerning SSR in COPD patients. In this study, we electrophysiologically investigated the sudomotor function of the sympathetic nervous system in patients with COPD. SSRs were recorded in 30 patients with COPD and 21 healthy volunteers. Normal responses were obtained from all subjects in the control group. No response was observed in three patients with COPD. The mean latency, amplitude and area values of the potentials recorded of the remaining 27 patients were compared to the control. The mean latency was longer (p<0.01) and the mean amplitude and area values were lower (p=0.012, p=0.021, respectively) in the patients compared to the control. We also demonstrated significant correlations between the latency, amplitude, or area values of the SSR and two parameters of pulmonary function tests forced expiratory volume one second/forced vital capacity (FEV1/FVC) and FEV1/FVC %. In conclusion, SSR is impaired in patients with COPD, which indicates the dysfunction of the sympathetic nervous system. Furthermore, the degree of impairment in SSR may reflect the severity of airway obstruction in patients with COPD.

Electrophysiology↗
PubMed2003

Horner's syndrome as a complication in thoracic surgical practice.

OBJECTIVE: To determine the incidence, reasons and prognosis about Horner's syndrome in thoracic surgical patients. METHODS: In this prospective clinical study, 933 adult patients were assessed between the years of 1998 and 2002. All patients who underwent chest tube insertion (n: 662 patients) or thoracotomy (n: 342 patients), or who had thoracic trauma (n: 268 patients) were routinely examined to detect of Horner's syndrome. The patients with Horner's syndrome due to the invasion of malignant tumour to sympathetic chain were not included in the study. RESULTS: Horner's syndrome was detected in twelve patients from these 933 patients (1.3%). The considered etiologic factors were chest tube pressure in five patients, operative complication in two patients and trauma in five patients. In patients with chest tube pressure were fully recovered from Horner's syndrome but the remaining did not. CONCLUSIONS: Malposition of the chest tube is an important aetiological factor of Horner's syndrome, and it is reversible if the tube position is corrected urgently.

Adolescent↗
PubMed2003

Migraine patients with or without vertigo: comparison of clinical and electronystagmographic findings.

OBJECTIVE: To find the differences between patients with migraine with and without vertigo. STUDY DESIGN: A prospective study. SETTING: Ambulatory dizziness centre of a tertiary referral hospital. METHODS: Eighty-four patients with migraine (31 with headache, 53 with headache and vertigo) according to the diagnostic criteria of migraine published by the International Headache Society in 1988 were included in the study. Patient history, vestibular tests, electronystagmography (ENG), and imaging studies were performed for differential diagnosis. MAIN OUTCOME MEASURES: Clinical findings and ENG parameters. RESULTS: Fifty-three of 84 patients (63%) had episodic vertigo attacks. Vertigo was independent from headache in 24 patients (45%). Vertigo symptoms always appeared later in the history of migraine headache. Headache started at age 27 +/- 8.3 years and vertigo symptoms began 7.7 +/- 8.7 years later. The beginning age of the migraine and female-to-male ratio were significantly greater in the vertigo group. Fifty-eight of the 84 patients had ENG testing. Fifty-eight percent of the patients with migraine and 55% of the patients with migraine + vertigo had abnormal ENG findings. None of the tests except the Dix-Hallpike manoeuvre had a statistically significant difference between the two groups. CONCLUSION: The presence of the same ENG abnormalities in patients with pure headache shows that the vestibular pathways are also affected in these patients, even when there are no vestibular symptoms.

Adult↗