Levent Öztürk

Variables affecting the occurrence of gastroesophageal reflux in obstructive sleep apnea patients

A number of recent studies have suggested that apnea and/or hypopnea episodes may be in a causal relationship with nocturnal gastroesophageal reflux (GER) episodes in obstructive sleep apnea (OSA) patients. In this study, we addressed the possible factors that may affect the occurrence of reflux events in OSA patients. For this reason, we investigated respiratory and sleep parameters in OSA patients with or without nocturnal GER episodes. Nineteen patients who were referred to the sleep laboratory for suspected sleep apnea were included in the study. All subjects underwent polysomnographic evaluation simultaneously with distal and proximal esophageal pH monitoring. During the recording period, a total of 134 reflux events, 134 from distal probes and none from proximal probes, were recorded. We divided patients into two groups: (1) nocturnal GER-positive patients (n=8; age: 41.9±11.9) and (2) nocturnal GER-negative patients (n=11; age: 45.4±3.3). We compared demographic, respiratory and sleep parameters between the two groups. Then we analysed the time relation between GER episodes and obstructive respiratory events. The two groups were matched by age and body mass index. Sleep and respiratory parameters were not different between the two groups. In conclusion, we suggested that age, body mass index and the severity of disease in obstructive sleep apnea patients are not effective determinants of gastroesophageal reflux. There is no sufficient evidence to accept arousals and obstructive apneas as primary causes of gastroesophageal reflux and vice versa. And finally, sleep macroorganisation has no impact on the occurrence of GER in OSAS.

Arginase activity and nitric oxide levels in patients with obstructive sleep apnea syndrome

OBJECTIVE: Obstructive sleep apnea syndrome is characterized by repetitive obstruction of the upper airways, and it is a risk factor for cardiovascular diseases. There have been several studies demonstrating low levels of nitric oxide in patients with obstructive sleep apnea syndrome compared with healthy controls. In this study, we hypothesized that reduced nitric oxide levels would result in high arginase activity. Arginase reacts with L-arginine and produces urea and L-ornithine, whereas L-arginine is a substrate for nitric oxide synthase, which produces nitric oxide. METHODS: The study group consisted of 51 obstructive sleep apnea syndrome patients (M/F: 43/8; mean age 49±10 years of age) and 15 healthy control subjects (M/F: 13/3; mean age 46±14 years of age). Obstructive sleep apnea syndrome patients were divided into two subgroups based on the presence or absence of cardiovascular disease. Nitric oxide levels and arginase activity were measured via an enzyme-linked immunosorbent assay of serum samples. RESULTS: Serum nitric oxide levels in the control subjects were higher than in the obstructive sleep apnea patients with and without cardiovascular diseases (p<0.05). Arginase activity was significantly higher (p<0.01) in obstructive sleep apnea syndrome patients without cardiovascular diseases compared with the control group. Obstructive sleep apnea syndrome patients with cardiovascular diseases had higher arginase activity than the controls (p<0.001) and the obstructive sleep apnea syndrome patients without cardiovascular diseases (p<0.05). CONCLUSION: Low nitric oxide levels are associated with high arginase activity. The mechanism of nitric oxide depletion in sleep apnea patients suggests that increased arginase activity might reduce the substrate availability of nitric oxide synthase and thus could reduce nitric oxide levels.

FEF25–75/FVC measurements and extrathoracic airway obstruction in obstructive sleep apnea patients

The aims of this study were to evaluate patients with obstructive sleep apnea syndrome (OSAS) with regards to dysanapsis (airway size relative to lung size) and to demonstrate the differences between the patients with and without extrathoracic airway obstruction. The study population consisted of 15 patients with OSAS and 14 age and body mass index (BMI) matched control subjects. OSAS patients and control subjects showed similar characteristics in FEV1, FEV1/FVC, FEF25–75, and FEF25–75/FVC ratios. Expiration reserve volume was significantly higher in the control group than in OSAS patients (p<0.01). Six patients exhibited extrathoracic airway obstruction while awake. Of these, three had also a sawtooth pattern in their flow–volume curves. The remaining nine patients had no extrathoracic airway obstruction and had lower apnea–hypopnea indexes (AHI) than the obstruction group (p<0.05). OSAS patients and age- and BMI-matched healthy controls had similar characteristics in terms of dysanapsis. In addition, there was no relation between the FEF25–75/FVC ratio and AHI, MinO2, and MeanO2. Extrathoracic airway obstruction may be a feature of only severe OSAS patients.

Effects of sleep deprivation on anaerobic exercise-induced changes in auditory brainstem evoked potentials

Background  The present study was designed to assess how anaerobic exercise affects auditory brainstem response (ABR) parameters, and whether one night of sleep deprivation could alter these possible exercise‐induced changes in ABRs.

Flurbiprofen in rapid eye movement sleep deprivation induced hyperalgesia.

BACKGROUND Rapid eye movement (REM) sleep deprivation induces hyperalgesia in healthy rats. Here, we evaluated the effects of flurbiprofen, an anti-inflammatory and neuroprotective agent, on the increased thermal responses observed in REM sleep deprived rats. METHODS Forty female rats were divided into four groups following 96-hour REM sleep deprivation: intraperitoneal injections of placebo, and flurbiprofen 5 mg/kg, 15 mg/kg and 40 mg/kg were made in CONT (n=10), FBP5, FBP15 and FBP40 groups respectively. Pain threshold measurements were performed three times at baseline (0.hour), at the end of REM sleep deprivation (96.hour) and at 1 h after injections (97.hour) by hot plate and tail-flick tests. RESULTS REM sleep deprivation induced a significant decrease in pain thresholds of all rats (hotplate: 0.hour vs 96.hour, 9.75±2.85 vs 5.10±2.02, p<0.001; tail flick: 0.hour vs 96.hour, 11.92±4.62 vs 7.92±5.15, p<0.001). Flurbiprofen in 15 mg/kg and 40 mg/kg doses significantly improved pain tolerance measured by tail flick test (tail flick in FBP15 and FBP40 groups: 96.hour vs 97.hour, 7.01±4.97 vs 8.34±3.61 and 5.06±1.57 vs 7.04±2.49, p<0.05 for both). CONCLUSION 96 h of REM sleep deprivation resulted in reduced pain thresholds in both hot plate and tail flick tests. Flurbiprofen was used for the first time in a rat model of REM sleep deprivation, and it provided anti-nociceptive effects in 15 mg/kg and 40 mg/kg doses. Flurbiprofen may have the potential for treatment of painful syndromes accompanying insomnia or sleep loss.

DNA methylation of the prestin gene and outer hair cell electromotileresponse of the cochlea in salicylate administration

Background/aim: Activity of the prestin gene may have a role in the pathogenesis of salicylate-induced ototoxicity. We investigated DNA methylation for prestin gene exon 1 in salicylate-injected guinea pigs.Materials and methods: Fifteen guinea pigs (30 ears) underwent audiological evaluation including 1000 Hz probe-tone tympanometry and a distortion product otoacoustic emission (DPOAE) test. The animals were randomly divided into three groups. Groups 2 (8 ears) and 3 (14 ears) were injected with intramuscular saline and sodium salicylate (200 mg/kg), respectively twice daily for 2 weeks. Group 1 (8 ears) received no injection. DPOAE measurements were performed at baseline; after 1, 2, 4, and 8 h (acute effect); and after 1 and 2 weeks (chronic effect). After audiological measurements, the animals were sacrificed for DNA isolation.Results: While a significant decrease (P < 0.01) was found for the acute effect in all frequencies in Group 3 according to baseline measurements, there was no difference in terms of chronic effect. DNA methylation increased during the acute phase of salicylate administration, whereas it returned to initial levels during the chronic phase.Conclusion: Salicylate-induced changes in DPOAE responses may be related to prestin-gene methylation. These results may have important implications for salicylate ototoxicity.

A New Hypothesis on the Frequency Discrimination of the Cochlea

OBJECTIVE Medial olivocochlear efferent (MOCE) neurons innervate outer hair cells (OHCs) of the cochlea, which in turn leads to basilar membrane motion. We hypothesized that MOCE-induced alterations in basilar membrane motion, independent of traveling waves, is responsible for the cochlear frequency discrimination of sound. MATERIALS AND METHODS Eleven guinea pigs underwent bilateral otoscopic and audiologic evaluations under general anesthesia. The study comprised two parts. Part I (n=11) included spontaneous otoacoustic emission (SOAE) recordings with or without contralateral pure-tone acoustic stimuli (1 and 8 kHz) at 60 dB sound pressure level (SPL). Part II involved pure-tone (1 or 8 kHz) acoustic trauma in the right ears of two randomly selected subgroups (G1: 1 kHz; n=4 and G8: 8 kHz; n=4). The remaining three animals served as controls. After frequency-specific deafness was confirmed by distortion product otoacoustic emission (DPOAE), SOAEs were recorded in the left ears in the presence of a contralateral pure-tone (1 and 8 kHz) stimulus of 60 dB SPL. Furthermore, the surface of the organ of Corti was examined by scanning electron microscopy (SEM). RESULTS The contralateral pure tone led to frequency-specific activation in SOAEs in part I (without trauma) and part II (with trauma) measurements. SEM showed heterogeneous OHC damage along the cochlea in traumatized ears with pure tone. CONCLUSION We suggest that MOCEs convey acoustic information from traumatized ears to intact ears. Traumatized ears can show frequency-specific activation in the presence of diffuse damage in OHCs that excludes the passive transmission of the pressure wave from the perilymph to the basilar membrane.

DETECTION OF DRIVER SLEEPINESS AND WARNING THE DRIVER IN REAL-TIME USING IMAGE PROCESSING AND MACHINE LEARNING TECHNIQUES

The aim of this study is to design and implement a system that detect driver sleepiness and warn driver in real-time using image processing and machine learning techniques. Viola-Jones detector was used for segmenting face and eye images from the cameraacquired driver video. Left and right eye images were combined into a single image. Thus, an image was obtained in minimum dimensions containing both eyes. Features of these images were extracted by using Gabor filters. These features were used to classifying images for open and closed eyes. Five machine learning algorithms were evaluated with four volunteer’s eye image data set obtained from driving simulator. Nearest neighbor IBk algorithm has highest accuracy by 94.76% while J48 decision tree algorithm has fastest classification speed with 91.98% accuracy. J48 decision tree algorithm was recommended for real time running. PERCLOS the ratio of number of closed eyes in one minute period and CLOSDUR the duration of closed eyes were calculated. The driver is warned with the first level alarm when the PERCLOS value is 0.15 or above, and with second level alarm when it is 0.3 or above. In addition, when it is detected that the eyes remain closed for two seconds, the driver is also warned by the second level alarm regardless of the PERCLOS value. Designed and developed real-time application can able to detect driver sleepiness with 24 FPS image processing speed and 90% real time classification accuracy. Driver sleepiness were able to detect and driver was warned successfully in real time when sleepiness level of driver is achieved the defined threshold values.

Timpanoplasti Cerrahisinde Desfluran ve Sevofluran Anestezisinin Kan Glukoz Düzeyleri Üzerine Etkilerinin Karşılaştırılması

Introduction: The effects of intravenous anesthetic drugs and inhaled anesthetics to the blood glucose (GLC) levels were investigated. Unfortunately, there is no adequate studies comparing these effects with new agents such as sevoflurane and desflurane drugs. In this study, blood GLC level changes among the the patients undergoing general anesthesia with sevoflurane and desflurane during the tympanoplasty surgery, were investigated. Material and methods: 60 patients,ages ranging between 18-65 in the ASA I-II risk group were randomly allocated to one of the two groups; The sevoflurane-remifentanyl drugs combination was applied to the group S and the desfluran-remifentanyl drugs combination was used for the group D. After fasting for 8 hours at the preoperative period, the blood GLC levels were measured before induction, at the 5 th , 10 th , 30 th , 60 th , 90 th , 120 th minutes, during the intraoperative period and 30 minutes after the extubation. Blood lactate levels were measured intraoperatively at 5th and 120th minutes.Results: There was no statistically significant difference between groups in terms of mean glucose levels (p>0,05). A statistically significant difference was observed between the T1-T6 and T0 values obtained in the desflurane groups according to the mean GLC level. In the sevoflurane group; there was no statistically significant difference at the third measurement time (p=0,223). In all other measurement times, the mean GLC levels were statistically significantly higher than the first measurement time.Conclusion: There was no difference between the two groups, in terms of blood GLC levels, representing patients who underwent anesthesia with sevoflurane and desflurane during tympanoplasty surgery.