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Biomedical subjects

T Ozgünen

Publications and source records attributed to T Ozgünen.

8 recordsLinked to original sources
PubMed2001

Effects of ketamine on different types of anxiety/fear and related memory in rats with lesions of the median raphe nucleus.

The aim of the present study was to determine the involvement of the median raphe serotonergic system in the effects of ketamine on anxiety behaviours and related memory. The effects of ketamine pretreatment (3 and 10 mg/kg, i.p.) on three types of fear-motivated behaviours, unconditioned one-way escape, conditioned avoidance and freezing were tested. Experiments were performed with the inhibitory avoidance apparatus in rats with ibotenic acid lesions of the median raphe nucleus. It was found that 10 mg/kg ketamine had an anxiogenic-like effect on one-way escape type of fear and anxiolytic-like effect on conditioned freezing-related fear; these effects were unaffected by median raphe lesions. Both ketamine doses impaired freezing-related fear memory. Ketamine (10 mg/kg) also produced an anxiolytic-like effect on avoidance type of fear and impaired avoidance memory. The median raphe lesions attenuated the anxiolytic action of the drug on the avoidance type of fear and prevented ketamine-induced avoidance memory impairment. These results suggest that the anxiolytic-like effect of ketamine on avoidance-type fear is mediated through the median raphe serotonergic system.

Analysis of Variance↗
PubMed2000

Median raphe nucleus mediates forming long-term but not short-term contextual fear conditioning in rats.

The brain serotonin is involved in mediation of emotional behaviour including anxiety and related fear conditioning. It is known that the median raphe nucleus (MRN) is the origin of a serotonergic pathway and mainly innervates septo-hippocampal formation which plays an important role in emotional cognition. However, its regulatory role in different types of fear conditioning is still unclear. In the present study, the animals underwent ibotenic acid or sham lesions of the median raphe nucleus and the effects of MRN lesions on immediate and delayed fear conditioning to multiple contextual cues were studied. Freezing behaviour served as a measure of contextual fear. Sham-lesioned animals showed reliable conditional freezing when observed immediately following foot-shock (1.0 mA) for 3-min test and 48 h after the shock for 12-min test. Rats with MRN lesions displayed robust freezing behaviour immediately after the shock, even though they showed a marked deficit in freezing 48 h following the shock. These findings indicate that the MRN-serotonergic septo-hippocampal pathway is involved in the regulation of anxiety related to fear conditioning triggered by contextual cues, suggesting that short-term contextual fear is independent on the MRN while long-term contextual fear depends on the MRN.

Animals↗
PubMed2000

Pregnancy outcomes in young Turkish women.

STUDY OBJECTIVE: We documented adolescent pregnancies that were thought to be at high risk for increased obstetric complications. DESIGN, SETTING, PARTICIPANTS: This study covered 442 pregnant women who were under 19 years of age and who delivered in Cukurova University, School of Medicine, Department of Obstetrics and Gynecology between January 1, 1993 and December 31, 1997, retrospectively. RESULTS: The patients' mean age was 18.24 years and their mean gestational age was 38.2 weeks. The newborns' mean birthweight was 3093.05 g and their mean birth height was 45.75 cm. Apgar score in the 1st minute was 6.79 and at the 5th minute 8.37. Cesarean section rate was 28.5%. The most common causes were pregnancy-induced hypertension (PIH) and breech delivery. There were 32 stillborns and 5 early neonatal deaths. The most frequent obstetric complications were PIH (14.5%), preterm delivery (7.0%), and low birthweight (< 2000 g) (10.2%). The pregnant adolescents with obstetric problems (44.4%) had poor obstetric results. CONCLUSIONS: Adolescent pregnancies are considered high risk with many obstetric complications and poor obstetric results. To decrease the complications adolescent pregnancies must be followed-up as high risk pregnancies, especially in developing countries where socioeconomic factors are more pronounced.

Adolescent↗
PubMed1996

The ionic basis of membrane potential changes from before fertilization through the first cleavage in the egg of the frog Rana cameranoi.

Experiments were performed to identify the ionic basis of membrane potential changes in the Rana cameranoi egg, from prior to fertilization through the first cleavage. The membrane potential was monitored continuously during this period. Ten per cent Ringer was used as the recording solution in the control group. The effects of Na+ or Ca2+ conductances were observed by altering external concentrations of these ions. K+ and Cl- conductances were tested by adding channel blockers of these ions (TEA and SITS, respectively) to the extracellular medium. The resting potential of the unfertilized egg is mainly affected by K+ conductance. Chloride conductance is responsible for the depolarization phase of the fertilization potential evoked by sperm entry, and K+ conductance is responsible for the repolarization phase of this potential. We suggest that Na+ permeability does not directly contribute to the fertilization potential; however fertilization potential peak is significantly reduced upon a reduction of extracellular sodium. The fertilization potential is not significantly influenced by extracellular Ca2+, and eggs fertilized in calcium-free solutions maintain their normal development; these results suggest that extracellular Ca2+ does not significantly contribute to the electrical and mechanical blocks that prevent polyspermy. The membrane potential of the fertilized egg does not alter significantly until the first cleavage. Potassium conductance contributes to hyperpolarization generated upon the first cleavage, whereas sodium is the basic ion responsible for the phase which follows peak hyperpolarization, and which plays a role in the return of the post-cleavage membrane potential to a steady level. Cl- conductance, which is important as the ionic basis of the fertilization potential, does not significantly influence any parameter of the cleavage cycle.

4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfo↗
PubMed1995

Fraser syndrome.

In a consanguineous marriage, a woman at 32 weeks' pregnancy presented with intrauterine growth retardation and bilateral renal agenesis. Fraser syndrome (cryptophthalmus syndactyly syndrome) was diagnosed based on cryptophthalmos, atresia of meatus acusticus externus in auricula, syndactyly, hypoplastic larynx, hypoplastic left lung, agenesis of urinary system and aberrant pancreas in duodenum. The syndrome is inherited as a recessive trait and the risk of recurrence is 25%.

Abnormalities, Multiple↗
PubMed1993

Endogenous digoxin-immunoreactive substance in normal and preeclamptic pregnancies.

AIMS: To determine the potential use of a digoxin-immunoreactive substance in the prediction of preeclampsia, to study the relationship between serum levels of this substance and gestational age, and to evaluate the correlation between this substance and blood pressure findings in preeclamptic pregnancies. METHODS: Serum digoxin-immunoreactive substance concentrations were measured by RIA (double antibody radioimmunoassay) in normotensive (n = 14) and preeclamptic (n = 17) pregnant women in their third trimesters. Statistical evaluation was performed with the Mann-Whitney U-test and correlation-regression analysis. RESULTS: The mean (+/- S.E.) digoxin-immunoreactive substance levels in the normal and preeclamptic patients were 0.29 +/- 0.06 and 0.31 +/- 0.05 ng/ml, respectively, the slightly higher level in the hypertensive group being statistically non-significant. Serum digoxin-immunoreactive substance levels did not demonstrate good correlation with gestational age and systolic blood pressure in preeclamptic pregnancies. CONCLUSIONS: An endogenous digoxin-immunoreactive substance is present in the sera of third trimester pregnant women, but it does not contribute to the pathogenesis or prediction of preeclampsia.

Adolescent↗