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Biomedical subjects

A Ersoz

Publications and source records attributed to A Ersoz.

9 recordsLinked to original sources
PubMed2000

Beneficial effects of dietary restriction on cerebral cortical synaptic terminals: preservation of glucose and glutamate transport and mitochondrial function after exposure to amyloid beta-peptide, iron, and 3-nitropropionic acid.

Recent studies have shown that rats and mice maintained on a dietary restriction (DR) regimen exhibit increased resistance of neurons to excitotoxic, oxidative, and metabolic insults in experimental models of Alzheimer's, Parkinson's, and Huntington's diseases and stroke. Because synaptic terminals are sites where the neurodegenerative process may begin in such neurodegenerative disorders, we determined the effects of DR on synaptic homeostasis and vulnerability to oxidative and metabolic insults. Basal levels of glucose uptake were similar in cerebral cortical synaptosomes from rats maintained on DR for 3 months compared with synaptosomes from rats fed ad libitum. Exposure of synaptosomes to oxidative insults (amyloid beta-peptide and Fe(2+)) and a metabolic insult (the mitochondrial toxin 3-nitropropionic acid) resulted in decreased levels of glucose uptake. Impairment of glucose uptake following oxidative and metabolic insults was significantly attenuated in synaptosomes from rats maintained on DR. DR was also effective in protecting synaptosomes against oxidative and metabolic impairment of glutamate uptake. Loss of mitochondrial function caused by oxidative and metabolic insults, as indicated by increased levels of reactive oxygen species and decreased transmembrane potential, was significantly attenuated in synaptosomes from rats maintained on DR. Levels of the stress proteins HSP-70 and GRP-78 were increased in synaptosomes from DR rats, consistent with previous data suggesting that the neuroprotective mechanism of DR involves a "preconditioning" effect. Collectively, our data provide the first evidence that DR can alter synaptic homeostasis in a manner that enhances the ability of synapses to withstand adversity.

Amyloid beta-Peptides↗
PubMed1999

Evaluation of heparin-coated circuits with full heparin dose strategy.

Heparin-coated cardiopulmonary circuits (HCC) in combination with a reduced systemic heparin dose has been demonstrated to reduce postoperative hemorrhage after cardiac surgery. But, it has still been equivocal whether this effect was related to the improved bio-compatibility or to the reduced exposure of the circulating heparin. Sixty patients undergoing elective coronary artery bypass grafting were randomly allocated into two groups either to be operated by HCC (30 patients) or uncoated but otherwise identical circuits (NHCC). Full systemic heparinization was induced in both groups. Hemodynamic parameters, hematological and biocompatibility tests were monitored within 24 hours. Postoperative blood loss, requirements for transfusions, clinical performance were recorded. Arterial filters were examined electron microscopically. Platelet levels remained significantly higher in the HCC group starting at the tenth minute following the institution of cardiopulmonary bypass until postoperative 24 hours. Electron microscopy showed significantly more platelet adhesion and pseudopod formation in the NHCC group. The mean amount of shed pleural and mediastinal blood measured from the time of the sternal closure was significantly lower in the HCC group (316 +/- 30 cc for HCC and 550 +/- 35 cc for NHCC). Mean postoperative transfusion requirements were also lower in the HCC group (230 +/- 23 cc for HCC and 320 +/- 25 cc for NHCC). The use of HCC and full systemic heparinization did not change the inflammatory response or biocompatibility but demonstrated benefits in platelet preservation and postoperative bleeding.

Adult↗
PubMed1997

Psychiatric complications of cardiac surgery postoperative delirium syndrome.

Psychiatric disturbances due to cardiopulmonary bypass, especially postoperative delirium syndrome, are among the immediate complications of open-heart surgery. In a series of 32 male and 18 female patients the prevalence of such disorders was investigated and search was made for possible risk factors for their occurrence. Psychiatric, neurologic and electroencephalographic evaluation was made pre- and postoperatively, in addition to haemodynamic, echocardiographic, angiographic and regional cerebral blood flow studies. Nine of the 50 patients had significantly reduced perfusion of certain cerebral lobes in single photon emission computed tomography, and in six of them the psychiatric tests indicated postoperative delirium; three of these six also had moderate electroencephalographic changes. The cerebral hypoperfusion persisted on day 15 in four patients, while psychiatric tests were negative. The study showed possible risk factors to be patient age, long aortic cross-clamp time, high-dose inotropic support and excessive transfusion of blood or blood products.

Adult↗
PubMed1995

Effect of selenium on ischemic and reperfusion injury in isolated guinea pig lungs.

1. An experimental comparative study on isolated guinea pig lungs was carried out to determine the effect of selenium added to pulmoplegic solution on ischemic lung preservation. 2. Two different types of solutions (Eurocollins in control group and Eurocollins + selenium 10(-3) M in experimental group) were infused before 3 hr of normothermic ischemia. 3. Tissue malone dialdehyde (MDA) and tissue glutathione (GSH) levels were assessed before the ischemic period, after the ischemia and at the end of reperfusion. Electron microscopic changes were also studied at the end of reperfusion to compare the cellular injury between the groups. 4. Addition of selenium before the ischemic period relatively decreased tissue MDA levels after reperfusion but did not alter tissue GSH levels.

Animals↗
PubMed1994

The effects of thyroid hormones on the heart following global ischemia. A clinical and experimental study.

Cardiopulmonary bypass is associated with a reduction in plasma thyroid hormone concentrations in patients undergoing cardiac surgery. However, studies of the effects of cardiopulmonary bypass on thyroid function are limited and many studies report conflicting data concerning only the period of cardiopulmonary bypass. In this study, we tried to clinically determine the effects of cardiopulmonary bypass on concentrations of thyroid hormones by comprehensive thyroid function tests in 10 patients before and after surgery, and observed the benefits of triiodothyronine supplementation after global ischemia on myocardial function experimentally in guinea pigs. In patients undergoing surgery, concentrations of total triiodothyronine and free triiodothyronine decreased progressively on the institution of cardiopulmonary bypass and remained below normal levels until 24 hours postoperatively. In the guinea pig hearts studied in a Langendorf perfusion apparatus, T3 supplementation enhanced percentage recovery of ventricular contractile force, heart work and heart rate with respect to other groups receiving no T3 supplementation or T3 supplementation without any ischemic interval.

Aged↗