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Biomedical subjects

A Toker

Publications and source records attributed to A Toker.

At least 19 recordsLinked to original sources
PubMed2006

Placental tissue cyclo-oxygenase 1 and 2 in pre-eclamptic and normal pregnancy.

OBJECTIVE: To investigate the activities of the 2 isoforms of prostaglandin synthetic enzyme cyclo-oxygenase (COX), COX-1 and COX-2, in the placental tissue of women with pre-eclampsia and healthy pregnant women. The relationship between placental lipid peroxidation and the activities of COX-1 and COX-2 was also investigated. METHODS: Tissue specimens were obtained from pre-eclamptic women (20 had severe pre-eclampsia and 38 had mild pre-eclampsia) and 27 healthy pregnant women who underwent cesarean section before the onset of labor. Malondialdehyde (MDA) levels and COX-1 and COX-2 activities were measured in placental tissue homogenates. RESULTS: Mean activities for COX-1 and COX-2 were significantly lower in women with severe pre-eclampsia than in healthy controls (P<0.05 and P<0.01, respectively). COX-1 and COX-2 activities were also lower in women with mild pre-eclampsia than in healthy controls, but the difference was of borderline significance (P=0.049 and P=0.059, respectively). The mean placental MDA level was significantly higher in pregnant women with severe and mild pre-eclampsia than in healthy pregnant women (P<0.01 for both). The correlation analysis showed significant negative correlations between MDA and COX-1 (r=-0.44, P<0.001) and MDA and COX-2 (r=-0.45, P<0.001) in the placental tissue of women with pre-eclampsia. CONCLUSION: These results suggest that COX-1 and COX-2 activities are decreased in the placental tissue of women with pre-eclampsia, probably by oxidative stress.

Adolescent↗
PubMed2006

An external support technique for the malacic trachea--treatment of tracheomalacia.

A 76-year-old woman was found to have a large, substernal, intrathoracic goiter. During excision, the trachea was found to be malacic. The trachea was sutured to a 16-mm ringed Gore-Tex (Gore & Associates, Arizona, USA) graft with Vicryl (Ethicon, Johnson & Johnson, USA) sutures. The graft was placed on the external surface of the trachea and surrounded the trachea almost 300 degrees. The patient was discharged on postoperative day seven without complications. She was seen at follow-up six months later and found to be free of complications.

Aged↗
PubMed2006

Treatment of a benign tracheoesophageal fistula in a ventilator dependent quadriplegic patient.

Management of an acquired benign tracheoesophageal fistula in a patient who is dependent on mechanical ventilation is controversial, since the usual procedure is weaning before repair. Here, we describe surgical treatment of a tracheoesophageal fistula in a quadriplegic patient with 28 months of follow-up, who has to remain permanently on mechanical ventilation with a tracheostomy cannula.

Anastomosis, Surgical↗
PubMed2005

Comparison of early postoperative results of thymectomy: partial sternotomy vs. videothoracoscopy.

BACKGROUND: The aim of this study was to compare the early postoperative results of thymectomy operations after partial sternotomy and videothoracoscopy for myasthenia gravis. METHODS: A total of 51 thymectomy operations were reviewed. The surgical procedure was simple thymectomy with partial sternotomy in the first 19 patients (Group I) and videothoracoscopic thymectomy (Group II) in the remaining patients. Both groups were compared in terms of preoperative data (age, gender, classification, duration of disease, medications), operative data (operation time, the mean amount of drainage, the duration of chest tube drainage), and postoperative data (duration of hospital stay, complications and pain). RESULTS: Groups were statistically uniform in terms of preoperative and operative data. Statistically significant differences were noted for the duration of chest tube drainage (48.8 vs. 29.8 hours, p < 0.001), the amount of drainage (264.4 vs. 178.6 ml, p = 0.001), the length of hospital stay (5.6 vs. 2.3 days, p = 0.000), and the visual analogue scale score (4.8 vs. 3.1, p < 0.001). CONCLUSIONS: Thymectomy with videothoracoscopic surgery demonstrated a more comfortable and faster recovery period without deterioration in myasthenic status.

Adult↗
PubMed2005

Resection of the tracheal carina in an eight-year-old child: a case report.

An 8-year-old girl, who had been mechanically ventilated for 2 days, was referred to our clinic with total atelectasis of the right lung. Bronchoscopic examination showed an endobronchial mass lesion which was located on the right side of the carina. Carinal resection was performed and the patient was discharged on postoperative day 7. We presented this case report because of the rarity of tracheal tumors in childhood and to discuss the recommended surgical technique for pediatric carinal resection.

Bronchoscopy↗
PubMed2005

An unusual localization of thymoma.

A 41-year-old man with myasthenia gravis was referred to our clinic to undergo a thymectomy by video-assisted thoracic surgery. After physical examination of the thorax and evaluation by computed tomography, a mass lesion was noticed in the neck and thymectomy was performed by partial sternotomy combined with a cervical incision. The cervical thymoma was discontinuous with the thymus. Thymoma in the neck has rarely been reported. In this case report we emphasize the possible presence of thymoma in the neck and the importance of neck evaluation in patients with myasthenia gravis.

Adult↗
PubMed2004

[A comparison of the effects of 50 % oxygen combined with CPAP to the non-ventilated lung vs. 100 % oxygen on oxygenation during one-lung ventilation].

OBJECTIVE: In a prospective, randomised, double-blind study the effects of FiO (2) of 0,5 with CPAP and a FiO (2) of 1.0 without CPAP on oxygenation and pulmonary shunt during one-lung ventilation (OLV) were examined. METHODS: In 20 patients undergoing thoracotomy (ASA II/III) two sequential ventilation methods were used during OLV: a) FiO (2) of 1.0 (OLV-100) and b) a FiO (2) of 0.5 in N (2)O combined with CPAP of 5 cm H (2)O to the non-ventilated lung (OLV-CPAP), whereby the sequence in 10 patients was OLV-CPAP followed by OLV-100; and the opposite in the remaining 10 patients. Operating conditions were graded by the surgeon. RESULTS: OLV-CPAP was associated with a better oxygenation and a lower shunt compared to OLV-100 (paO (2) : 198 +/- 40 mmHg vs 181 +/- 38 mmHg; p < 0.05 and Qs/Qt: 30 +/- 6 % vs. 34 +/- 8 %; p < 0.01, respectively). The different sequence of the ventilation methods did not cause significant differences in the results. The surgical conditions were not impaired by the CPAP of 5 cm H (2)O. CONCLUSION: The application of low FiO (2) with CPAP provided a better oxygenation and a lower pulmonary shunt during the OLV compared to high FiO (2) without CPAP.

Aged↗
PubMed2003

Perioperative pneumoperitoneum after lobectomy -- bilobectomy operations for lung cancer: a prospective study.

BACKGROUND: The aim of this study is to identify the effectiveness of perioperative pneumoperitoneum to prevent air leak after the lobectomy-bilobectomy operations for lung cancer. METHODS: A prospective study was designed on consecutive 50 patients who had lobectomy-bilobectomy operations for lung cancer and whose remnant lung had failed to fill the half of the hemithoracic cavity under 30 cm H(2)O positive pressure ventilation during the operation with totally relaxed diaphragm. The patients were divided into two groups: group 1 (25 patients) with perioperative pneumoperitoneum, group 2 (25 patients) without perioperative pneumoperitoneum. RESULTS: The statistical analysis between the two groups did not show any significant difference in terms of age, preoperative FEV1, and the type of resection. Perioperative pneumoperitoneum significantly reduced the duration of postoperative air leak (2.2 +/- 1.15 days vs. 6.04 +/- 3.27 days p < 0.0001) and total chest tube drainage time (3.84 +/- 0.98 days vs. 7.88 +/- 3.16 days p < 0.001). CONCLUSION: Perioperative pneumoperitoneum after lobectomy-bilobectomy operations for lung cancer is an effective method to decrease air leak and chest tube drainage time.

Adult↗
PubMed2003

How can we approach a left-sided stab wound in the neck, with isolated tracheal laceration?

Any penetrating trauma to the mediastinum may cause great vessel damage resulting in massive bleeding or even shock. Associated tracheal injury increases morbidity and mortality. We report a case of a penetrating mediastinal injury with isolated tracheal laceration. The stab entered in the left supraclavicular fossa. The patient presented with right-sided pneumothorax, pneumomediastinum and respiratory collapse. Bronchoscopy revealed two injuries in the trachea that were repaired by right thoracotomy and left cervicotomy. The patient was discharged on postoperative day 6. Isolated thoracic tracheal injury is very rare in mediastinal stab wounds and operative strategy may change according to bronchoscopic findings.

Adolescent↗
PubMed2002

Clinical experience of surgical therapy in 207 patients with thoracic hydatidosis over a 12-year-period.

PRINCIPLES: Hydatid disease is the most severe helminthic zoonosis, with a major medical, social, and economic impact in Turkey. The aim of this study was to evaluate retrospectively 207 patients diagnosed with hydatid cyst and treated surgically in our department between January 1990 and December 2001. METHODS: Hundred and ninety three patients were male and 14 female. They ranged in age from 19 to 72 years (mean 25.3 years). The most common presenting symptoms were cough, expectoration and chest pain. The surgical approach was thoracotomy in 198 patients, bilateral staged thoracotomies in 5 patients, median sternotomy in one patient and video-assisted thoracic surgery in 3 patients. RESULTS: Hundred and thirty eight of the 265 intrapulmonary cystic lesions were found in the right lung and 127 in the left lung. Intrathoracic extrapulmonary cystic lesions were detected in 13 patients. 38 patients also had cystic lesions in the liver. Conservative surgical procedures were adopted except for small wedge resections in 8 patients, segmentectomy in 4 patients and lobectomy in one. Operative and postoperative mortality was nil. Albendazole treatment was given to patients who had multiple intrathoracic cysts or additional hepatic cysts after 1994. CONCLUSIONS: Our preferred surgical techniques for removal of cysts were conservative surgical procedures such as enucleation of cysts or removal by cystotomy. Radical procedures such as pneumonectomy, lobectomy and segmentectomy should be avoided as far as possible.

Adult↗
PubMed2002

Phosphoinositides and signal transduction.

Phosphoinositides comprise a family of eight minor membrane lipids which play important roles in many signal transducing pathways in the cell. Signaling through various phosphoinositides has been shown to mediate cell growth and proliferation, apoptosis, cytoskeletal changes, insulin action and vesicle trafficking. A number of advances in signal transduction in the last decade has resulted in the discovery of a growing list of proteins which directly interact with high affinity and specificity with distinct phosphoinositides. Equally important, a number of phosphoinositide binding domains such as the pleckstrin homology domain have emerged as critical mediators of phosphoinositide signaling. Here, recent advances in phosphoinositide signaling are discussed. The aim of this review is to highlight particularly exciting advances made in the field over the last few years. The regulation of phosphoinositide metabolism by lipid kinases, phosphatases and phospholipases is reviewed, and considerable emphasis is placed on phosphoinositide-binding proteins. Finally, the role of these lipids in regulating signaling pathways and cell function is described.

Biological Transport↗
PubMed2001

Phosphorylation of the activation loop of gamma p21-activated kinase (gamma-Pak) and related kinases (MSTs) in normal and stressed neutrophils.

Neutrophils stimulated with a variety of chemoattractants exhibit a rapid activation of two p21-activated kinases (Paks) with molecular masses of approximately 63 and 69 kDa (gamma- and alpha-Pak). A number of in vitro studies suggest that modification of Thr(402) in the activation loop (AL) of gamma-Pak can play a critical role in the regulation of this kinase under certain circumstances. A phosphospecific Ab was generated to this region of Pak (pPak(AL)Ab). This Ab reacted with activated gamma- and alpha-Pak from fMLP-stimulated neutrophils that contain the sequence KRXT(P)XXGTP in their ALS: The rapid but transient activation of Paks in normal stimulated neutrophils coincided with phosphorylation and dephosphorylation at the ALs of these enzymes. In contrast, stressed cells exhibited a prolonged phosphorylation at Thr(402) in both intact gamma-Pak and a proteolytic fragment of this kinase. The pPak(AL)Ab also reacted with the mammalian sterile twenty-like kinases (MSTs) (members of the Pak family) in osmotically stressed neutrophils and neutrophils treated with certain apoptotic agents (i.e., tumor promoters that inhibit type 1 and 2A protein phosphatases) but not in normal fMLP-stimulated cells. Thus, our results indicate that the AL of gamma-Pak undergoes transient phosphorylation during normal neutrophil stimulation and chronic phosphorylation in stressed cells. In addition, we demonstrate that a number of MSTs are present in neutrophils and also undergo phosphorylation during stressful circumstances.

Androstadienes↗
PubMed2001

Mechanisms of cold-induced platelet actin assembly.

Various agonists but also chilling cause blood platelets to increase cytosolic calcium, polymerize actin, and change shape. We report that cold increases barbed end nucleation sites in octyl glucoside-permeabilized platelets by 3-fold, enabling analysis of the intermediates of this response. Although chilling does not change polyphosphoinositide (ppI) levels, a ppI-binding peptide completely inhibits cold-induced nucleation. The C terminus of N-WASp, which inhibits the Arp2/3 complex, blocks nucleation by 40%; GDPbetaS, N17Rac and N17Cdc42 have no effects. Some gelsolin translocates to the detergent-insoluble cytoskeleton after cooling. Chilled platelets from gelsolin-deficient mice have approximately 50% fewer new actin nuclei compared with platelets from wild-type mice. EGTA completely inhibits gelsolin translocation into the cytoskeleton, and the small amount of gelsolin initially there becomes soluble. Chilling releases adducin from the detergent-resistant cytoskeleton. We conclude that platelet actin filament assembly induced by cooling involves ppI-mediated actin filament barbed end uncapping and de novo nucleation independently of surface receptors or downstream signaling intermediates besides calcium. The actin-related changes occur in platelets at temperatures below 37 degrees C, suggesting that the platelet may be more activable at temperatures at the body surface than at core temperature, thereby favoring superficial hemostasis over internal thrombosis.

Actin-Related Protein 2↗
PubMed2001

The carboxyl terminus of protein kinase c provides a switch to regulate its interaction with the phosphoinositide-dependent kinase, PDK-1.

The function of protein kinase C family members depends on two tightly coupled phosphorylation mechanisms: phosphorylation of the activation loop by the phosphoinositide-dependent kinase, PDK-1, followed by autophosphorylation at two positions in the COOH terminus, the turn motif, and the hydrophobic motif. Here we address the molecular mechanisms underlying the regulation of protein kinase C betaII by PDK-1. Co-immunoprecipitation studies reveal that PDK-1 associates preferentially with its substrate, unphosphorylated protein kinase C, by a direct mechanism. The exposed COOH terminus of protein kinase C provides the primary interaction site for PDK-1, with co-expression of constructs of the carboxyl terminus effectively disrupting the interaction in vivo. Disruption of this interaction promotes the autophosphorylation of protein kinase C, suggesting that the binding of PDK-1 to the carboxyl terminus protects it from autophosphorylation. Studies with constructs of the COOH terminus reveal that the intrinsic affinity of PDK-1 for phosphorylated COOH terminus is over an order of magnitude greater than that for unphosphorylated COOH terminus, contrasting with the finding that PDK-1 does not bind phosphorylated protein kinase C effectively. However, effective binding of the phosphorylated species can be induced by the activated conformation of protein kinase C. This suggests that the carboxyl terminus becomes masked following autophosphorylation, a process that can be reversed by the conformational changes accompanying activation. Our data suggest a model in which PDK-1 provides two points of regulation of protein kinase C: 1) phosphorylation of the activation loop, which is regulated by the intrinsic activity of PDK-1, and 2) phosphorylation of the carboxyl terminus, which is regulated by the release of PDK-1 to allow autophosphorylation.

3-Phosphoinositide-Dependent Protein Kinases↗
PubMed2001

Antagonists of calcium fluxes and calmodulin block activation of the p21-activated protein kinases in neutrophils.

Neutrophils stimulated with fMLP or a variety of other chemoattractants that bind to serpentine receptors coupled to heterotrimeric G proteins exhibit rapid activation of two p21-activated protein kinases (Paks) with molecular masses of approximately 63 and 69 kDa (gamma- and alpha-Pak). Previous studies have shown that products of phosphatidylinositol 3-kinase and tyrosine kinases are required for the activation of Paks. We now report that a variety of structurally distinct compounds which interrupt different stages in calcium/calmodulin (CaM) signaling block activation of the 63- and 69-kDa Paks in fMLP-stimulated neutrophils. These antagonists included selective inhibitors of phospholipase C (1-[6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl]-1H-pyrrole-2,5-dione), the intracellular Ca(2+) channel (8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate), CaM (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide; N-(4-aminobutyl)-5-chloro-1-naphthalenesulfonamide; trifluoperazine), and CaM-activated protein kinases (N-[2-(N-(chlorocinnamyl)-N:-methylaminomethyl)phenyl]-N-[2-hydroxyethyl]-4-methoxybenzenesulfonamide). This inhibition was dose-dependent with IC(50) values very similar to those that interrupt CaM-dependent reactions in vitro. In contrast, less active analogues of these compounds (1-[6-((17beta-3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl]-2,5-pyrrolidinedione; N-(6-aminohexyl)-1-naphthalenesulfonamide; N-(4-aminobutyl)-1-naphthalenesulfonamide; promethazine; 2-[N-(4-methoxybenzenesulfonyl)]amino-N-(4-chlorocinnamyl)-N-methylbenzyl-amine]) did not affect activation of Paks in these cells. CaM antagonists (N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide; trifluoperazine), but not their less-active analogues (N-(6-aminohexyl)-1-naphthalenesulfonamide; promethazine), were also found to block activation of the small GTPases Ras and Rac in stimulated neutrophils along with the extracellular signal-regulated kinases. These data strongly suggest that the Ca(2+)/CaM complex plays a major role in the activation of a number of enzyme systems in neutrophils that are regulated by small GTPases.

Animals↗