Ahmet Ayar

Melatonin inhibits high voltage activated calcium currents in cultured rat dorsal root ganglion neurones.

The actions of melatonin on high-voltage activated calcium channels (HVACC) and intracellular free Ca(2+) concentration in cultured dorsal root ganglion (DRG) neurones from neonatal rats were investigated using the whole-cell patch clamp and the fura-2 fluorescence ratio Ca(2+)-imaging techniques. HVACC were pharmacologically and biophysically isolated and the effects of melatonin were investigated. Extracellular application of melatonin inhibited HVACC in a dose dependent manner. In calcium imaging experiments, application of extracellular recording medium containing 30 mM KCl evoked increases in intracellular free Ca(2+) that were dependent upon external Ca(2+) ions. This increase was prevented by both low (10 microM) and high dose (100 microM) of melatonin pre-treatment. The results of this study indicate that the pineal hormone melatonin has inhibitory actions on voltage dependent calcium entry in cultured rat DRG neurones.

Antinociceptive efficacy of levetiracetam in a mice model for painful diabetic neuropathy.

Background and Objective: Despite important advances in available knowledge, management of neuropathic pain remains incomplete, and results from experimental and clinical studies indicate that some anticonvulsants show promise for treating neuropathic pain. The aim of this study was to assess the antinociceptive efficacy of levetiracetam (LEV, ucb L059) in a mice model for painful diabetic neuropathy using the in vivo nociceptive behavioral ‘hot‐plate test.’

Homocysteine-induced enhancement of spontaneous contractions of myometrium isolated from pregnant women

Background.  Although many associations have been demonstrated between hyperhomocysteinemia and pregnancy complications, such as spontaneous abortion, preterm labor, preeclampsia and low birthweight, it is still not clear whether hyperhomocysteinemia is the cause or the consequence of these pregnancy complications. The aim of this study was to investigate the effects of homocysteine on the spontaneous contractility of isolated pregnant human myometrium.

Effects of erythromycin on pregnancy duration and birth weight in lipopolysaccharide-induced preterm labor in pregnant rats.

OBJECTIVE The aim of this study was to investigate the effects of erythromycin on pregnancy duration and on live birth weight in lipopolysaccharide (LPS)-induced preterm labor model in rats. STUDY DESIGN Total of 60 pregnant rats on day 16 of gestation was intraperitoneally injected with 25 microg/kg LPS. Animals were randomly divided into six groups and 20mg/kg (n=10), 40 mg/kg (n=10), 60 mg/kg (n=10), 80 mg/kg (n=10), and 100mg/kg (n=10) erythromycin and equal volume of physiological saline (n=10) were given intraperitoneally. Injection of LPS-to-vaginal bleeding interval, vaginal bleeding-to-delivery interval, LPS injection-to-delivery interval was monitored and live birth weight of neonates was determined. Statistical analysis was performed using Kruskal-Wallis, Mann-Whitney U-test and Spearman correlation analysis. RESULTS Intraperitoneal injection of erythromycin to LPS-administered rats caused significant increase in latent period, labor period, total period and live birth weight in a dose dependent manner. CONCLUSION These data shows that erythromycin causes prolongation of pregnancy period and increases live birth weight in LPS-induced preterm labor of pregnant rats.

The inhibitory role of melatonin on isolated guinea‐pig urinary bladder: an endogenous hormone effect

To investigate the effects of melatonin, an endogenous hormone, on acetylcholine and KCl‐induced contractions of isolated guinea‐pig detrusor muscle.

Reversal of iron deficiency anemia-induced peripheral neuropathy by iron treatment in children with iron deficiency anemia.

The effects of iron deficiency anemia (IDA) on nerve conduction and efficiency of iron therapy were investigated by peripheral nerve-electrophysiological measurements. Eighteen children (10 boys, eight girls; mean age 31 +/- 1.3 months) with IDA and 12 healthy children (six boys, six girls; mean age 29 +/- 1.3 months) were enrolled into the study. Nerve conduction velocity was measured in the median and posterior tibial nerve. After nerve conduction values were determined in the patients and controls, 6 mg/kg/24 h ferrous sulphate was given orally to the patients for 3 months and nerve conduction velocity tests were performed again. Median/motor and sensory nerve conduction velocity and tibial/motor nerve distal-amplitute values of children with IDA were lower than for the control group (p < 0.05, p < 0.01 and p < 0.001 respectively). With iron supplementation these values increased to the normal levels and even higher than control levels for some parameters. In correlation studies between whole blood parameters and nerve conduction velocity results, there was a correlation between median/sensory nerve conduction velocity values and serum iron levels. Additionally there was a correlation between some nerve conduction velocity values and age. In conclusion, the evidence from this preliminary study suggests that peripheral neuropathy may develop in children with IDA. Peripheral neuropathy symptoms in these patients may be improved by iron therapy.

Effects of tibolone on plasma homocysteine levels in postmenopausal women

OBJECTIVE To investigate the effects of tibolone on levels of plasma homocysteine, an independent risk factor for cardiovascular disorders, in postmenopausal women. DESIGN Prospective, randomized clinical study. SETTING University hospital. PATIENT(S) Postmenopausal healthy women. INTERVENTION(S) Tibolone (2.5 mg/d) or calcium (1250 mg/d) and conjugated equine estrogens (0.625 mg/d) plus medroxyprogesterone acetate (5 mg/d) were administered orally for 6 months. Blood samples were collected at the start and the end of therapy. MAIN OUTCOME MEASURE(S) Plasma homocysteine levels. RESULT(S) Administration of tibolone and calcium caused only a 4% decrease in plasma homocysteine levels compared with initial levels. In contrast, conjugated equine estrogens plus medroxyprogesterone acetate caused a 29% decrease in plasma homocysteine levels. CONCLUSION(S) Despite the reported beneficial effect of tibolone on the serum lipid profile, tibolone had no statistically significant effect on serum homocysteine levels in postmenopausal women. The possible cardiovascular protective role of tibolone might be unrelated to its effects on homocysteine levels.

Effects of erythromycin on stretch-induced contractile activity of isolated myometrium from pregnant women.

Background. Despite the fact that preterm labor and birth account for the vast majority of neonatal morbidity and mortality the currently available treatment options are still far from satisfactory. The aim of this study was to investigate the effects of erythromycin on stretch‐induced contractions of pregnant human myometrial strips, obtained at cesarean section.

CORRELATIVE STUDY OF THE COGNITIVE IMPAIRMENT, REGIONAL CEREBRAL BLOOD FLOW, AND ELECTROENCEPHALOGRAM ABNORMALITIES IN CHILDREN WITH DOWN’S SYNDROME

The aim of this study was to investigate possible correlations of the cognitive impairment with abnormalities of regional cerebral blood flow and electroencephalogram in children with (Downs Syndrome) DS. Nine patients with DS were evaluated by single photon emission computed tomography (SPECT) in combination with clinical findings, electroencephalography (EEG), and magnetic resonance imaging (MRI). In cases with IQs below 40, there were one or more findings of abnormal EEG/MRI and brain perfusion SPECT. In 6 cases (66.7%) EEG findings were normal, but 3 (33.3%) had abnormal EEG findings. Perfusion abnormalities were most pronounced in the fronto-parieto-temporal region in the form of hypoperfusion (n = 5) and in the right hemisphere (n = 5) than the left hemisphere (n = 1). These findings suggest that the children with DS had varying levels of structural, perfusion, and electrophysiological abnormalities in the brain and these abnormalities were reflected by measurable alterations of the cognitive functions.

Inhibitory Effects of Sildenafil Citrate on the Tonus of Isolated Dog Internal Anal Sphincter

PURPOSEAlthough the exact pathogenesis of anal fissure is not known, hypertonicity of the internal anal sphincter might be involved in its pathogenesis as main event. To gain information about possible usefulness of the novel, smooth-muscle–relaxing drug, sildenafil, in chronic anal fissure, we investigated the effect of sildenafil citrate on acetylcholine-induced contractility of internal anal sphincter isolated from dogs.METHODSInternal anal sphincter strips were taken from German shepherd dogs and suspended in a tissue bath filled with Krebs solution at 37°C (pH 7.4) continuously bubbled with 95 percent oxygen and 5 percent carbon dioxide, and isometric contractions were recorded. Contractions were evoked by 10 μM acetylcholine, and the effects of different concentrations of sildenafil citrate (0.1, 0.3, and 1 mM) on the isometric tension of each internal anal sphincter strip were examined. The statistical significance was analyzed by one-way analysis of variance.RESULTSPretreatment with sildenafil citrate (0.1 mM) attenuated contractile response to acetylcholine (n = 3), which were significantly weak compared with the maximum contractile response to the acetylcholine alone (610 ± 110 mg vs. 2,825.17 ± 416 mg; n = 12; P < 0.05). Sildenafil citrate also significantly inhibited the acetylcholine-induced contractions in a dose-dependent manner when applied after.CONCLUSIONSThis experimental in vitro study showed that sildenafil citrate relaxes acetylcholine stimulated contractions of isolated dog internal anal sphincter. This may be of importance for raising the possibility that sildenafil cit-rate may have future potential in the treatment of chronic anal fissure. Further studies are needed for a conclusive decision on possible usefulness of sildenafil citrate in patients with chronic anal fissure.