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Biomedical subjects

G Arslan

Publications and source records attributed to G Arslan.

At least 91 records · Page 5Linked to original sources
PubMed1998

The effect of etomidate induction on plasma cortisol levels in children undergoing cardiac surgery.

OBJECTIVE: To investigate the effect of a single induction dose of etomidate on plasma cortisol and adrenocorticotrophic hormone (ACTH) levels in pediatric patients with congenital heart disease. DESIGN: A prospective, randomized study. SETTING: A university hospital. PARTICIPANTS: Thirty children undergoing cardiopulmonary bypass. INTERVENTIONS: Patients were randomly allocated into two groups to receive etomidate, 0.3 mg/kg, and fentanyl, 1 microg/kg, or ketamine, 1 mg/kg, and fentanyl, 1 microg/kg intravenously, for anesthesia induction. Anesthesia was maintained with 50% nitrous oxide and 0.5% isoflurane in oxygen. Plasma cortisol and ACTH levels were measured on five occasions: preoperatively, after induction of anesthesia, after cross-clamping, at the end of surgery, and 24 hours postoperatively. MEASUREMENTS AND MAIN RESULTS: Plasma cortisol levels of the etomidate group decreased with anesthesia induction and remained significantly low during cardiopulmonary bypass, at the end of operation, and 24 hours postoperatively. Plasma cortisol levels of the etomidate group after the anesthesia induction, during cardiopulmonary bypass, and at the end of the operation were significantly lower than the ketamine group. CONCLUSION: These results show that etomidate is a suitable agent for suppressing the increase in cortisol levels associated with the stress response caused by cardiopulmonary bypass in children with congenital heart defects, and can be used safely.

Adrenocorticotropic Hormone↗
PubMed1997

Down-regulation of adenosine A2A receptors upon NGF-induced differentiation of PC12 cells.

PC12 cell differentiation was induced by one week of nerve growth factor (NGF) treatment and adenosine A2A receptor expression and activity were analysed. Undifferentiated PC12 cells expressed very high levels of adenosine A2A receptors (approximately equal to 2 pmol/mg) and exhibited strong cyclic AMP (cAMP) responses when stimulated with the selective adenosine A2A receptor agonist 2-[p-(2-carbonylethyl) phenylethylamino-5'-N-ethylcarboxamidoadenosine]. NGF-induced differentiation was accompanied by a down-regulation of adenosine A2A receptors: receptor binding decreased to 500 fmol/mg, immunoreactive A2A receptor protein was decreased by about half and cAMP production was reduced by 60%. In situ hybridization experiments demonstrated a heterogenous distribution of A2A receptor mRNA and a decreased number of strongly labelled cells after NGF treatment. Stimulation of the cells with the non-selective adenosine receptor agonist N-ethylcarboxamidoadenosine (NECA) inhibited NGF-induced mitogen-activated protein kinase activation. These results thus show that NGF-induced differentiation of PC12 cells is accompanied by a decrease in A2A receptor-mediated cAMP accumulation. This might be a way for PC12 cells to counteract an inhibitory effect of A2A receptor activation on some aspects of neurotrophin signalling.

Animals↗
PubMed1997

Characterization of human A2A adenosine receptors with the antagonist radioligand [3H]-SCH 58261.

1. We have characterized the binding of the new potent and selective antagonist radioligand [3H]-5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazol o[1,5- c]pyrimidine, [3H]-SCH 58261, to human cloned A2A adenosine receptors. 2. In Chinese hamster ovary (CHO) cells transfected with the human cloned A2A receptor, [3H]-SCH 58261 specific binding (about 70%) was rapid, saturable, reversible and proportional to protein concentration. The kinetic KD value was 0.75 nM. Saturation experiments showed that [3H]-SCH 58261 labelled a single class of recognition sites with high affinity (KD = 2.3 nM) and limited capacity (apparent Bmax = 526 fmol mg-1 protein). 3. Competition experiments revealed that binding of 0.5 nM [3H]-SCH 58261 was displaced by adenosine receptor agonists with the following order of potency: 2-hexynyl-5'-N-ethylcarboxamidoadenosine (2HE-NECA) > 5'-N-ethylcarboxamidoadenosine (NECA) = 2-phenylaminoadenosine (CV 1808) > 2-[4-(2-carboxyethyl)-phenethylamino]-5'-N-ethylcarboxamidoadenosi ne (CGS 21680) > R-N6-phenylisopropyladenosine (R-PIA) > or = N6-cyclohexyladenosine (CHA) > S-N6-phenylisopropyladenosine (S-PIA). 4. Adenosine receptor antagonists inhibited [3H]-SCH 58261 binding with the following order: 5-amino-9-chloro-2-(2-furyl)-[1,2,4]-triazolo[1,5-c] quinazoline (CGS 15943) > SCH 58261 > xanthine amine congener (XAC) > (E,18%-Z,82%)7-methyl-8-(3,4-dimethoxystyryl)-1,3- dipropylxanthine (KF 17837S) > 8-cyclopentyl-1,3-dipropylxanthine (DPCPX) > theophylline. 5. Affinity values and rank order of potency of both receptor agonists and antagonists were similar to those previously obtained in human platelet and rat striatal membranes, except for CV 1808 which was more potent than CGS 21680. SCH 58261 was a competitive antagonist at inhibiting NECA-induced adenosine 3':5'-cyclic monophosphate (cyclic AMP) accumulation in CHO cells transfected with human A2A receptors. Good agreement was found between binding and functional data. 6. Thus, the new antagonist radioligand is preferable to the receptor agonist radioligand [3H]-CGS 21680 hitherto used to examine the pharmacology of human cloned A2A adenosine receptors.

Animals↗
PubMed1997

Is there still a place for surgery in the treatment of ureteral stones?

Although most ureteral stones can be treated with Extracorporeal Shock Wave Lithotripsy (ESWL) and endourology, there still is a small percent of patients whose stones can not be treated with minimally invasive techniques and thus require open surgery. Retroperitoneoscopic surgery is a good alternative for this subgroup of patients. It provides a direct access to the retroperitoneum, less morbid than an open operation and provides a better cosmetic result. On the very rare occasion open surgery with ureteral reimplantation to the bladder is required in those patients with lower ureteral stones. We have seen 1297 patients with stones larger than 5 mm in the ureter during the last 7 years. Among those undergoing watchful waiting 82% were stone-free; and that was 2.4% of all ureteral stones. Among those 1258 patients whom required a treatment 82.1% underwent in situ ESWL and 74.5% of them were rendered stone-free. In 8.9% of the patients ureteroscopy was performed (50% primary, and 50% for failed ESWL) with a stone-free rate of 75.8%. Open stone surgery was required in 8.9%, and retroperitoneoscopic surgery for ureteral stones was performed in only 0.15% of all patients. The best form of treatment for a ureteral stone is watchful waiting and the patient passing the stone without any intervention. Although that is the best scenario, this is a very painful condition and unfortunately most patients require some form of treatment. While ESWL for upper and mid ureteral non-obstructing and non-impacted stones is highly effective, stones in the lower ureter can be successfully treated via ureteroscopy. There still are some patients who require open surgery and retroperitoneoscopic surgery can be an alternative for this subgroup of patients offering a less morbid and better cosmetic result.

Adolescent↗