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S Kaya

Publications and source records attributed to S Kaya.

At least 55 records · Page 3Linked to original sources
PubMed1998

Half-site modification of Lys-480 of the Na+,K+-ATPase alpha-chain with pyridoxal 5'-diphospho-5'-adenosine reduces ATP-dependent phosphorylation stoichiometry from half to a quarter.

Pig and dog kidney Na+,K+-ATPase preparations, irrespective of specific activity, showed approximately 0.5 mol of maximum phosphorylation/mol alpha-chain for ATP or acetyl phosphate (AcP) at steady state conditions. Pyridoxal 5'-diphospho-5'-adenosine (AP2PL)-treated pig kidney enzymes containing approximately 0.5 mol of AP2PL probe at Lys-480/mol (Tsuda, T., Kaya, S., Funatsu, H., Hayashi, Y., and Taniguchi, K. (1998) J. Biochem. (Tokyo) 123, 169-174) showed a quarter-site phosphorylation by ATP and half-site phosphorylation from AcP. The addition of 10 microM ATP to the Mg2+-Na+-bound AP2PL enzyme induced rapid quarter-site phosphorylation (47/s), followed by two different AP2PL fluorescence changes, a rapid decrease (29/s) and a slow increase (1.1/s). The addition of 1 mM AcP to the Mg2+-Na+-bound AP2PL enzyme induced a slow half-site phosphorylation (3/s), followed by a monophasic AP2PL fluorescence increase (1.2/s). After treatment of the AP2PL enzyme with fluorescein 5'-isothiocyanate to modify Lys-501 fully, the Mg2+-Na+-dependent phosphorylation capacity from ATP of the resulting AP2PL-fluorescein 5'-isothiocyanate enzyme was reduced to approximately 6% without significant changes in half-site phosphorylation capacity with respect to AcP, dynamic AP2PL fluorescence change by ATP and change by AcP. These data and others support the hypothesis that the functional membrane-bound Na+, K+-ATPase has tetrameric properties.

Adenosine Diphosphate↗
PubMed1998

ATP and acetyl phosphate induces molecular events near the ATP binding site and the membrane domain of Na+,K+-ATPase. The tetrameric nature of the enzyme.

The addition of ATP to Mg2+-Na+-bound-probe labeled Na+,K+-ATPase preparations containing approximately 0.5 mol of pyridoxal 5'-diphospho-5'-adenosine (AP2PL) probe at Lys-480 and approximately 0.9 mol of fluorescein 5'-isothiocyanate (FITC) probe at Lys-501 showed a decrease and an increase in the AP2PL fluorescence intensity with neither significant ATP-dependent phosphorylation nor FITC fluorescence change. The rate constants for the fluorescence change increased nearly linearly with increasing ATP concentrations. The substitution of AcP for ATP decreased the FITC fluorescence rather monophasically, 8.5/s, which was followed by the half-site phosphorylation with same amount of components with different rate constant, 7.2 and 4.6/s, followed by a much slower increase in the two components of AP2PL fluorescence, 1.4 and 0.2/s. The addition of Na+ with increasing concentrations of ATP to the K+-bound AP2PL-FITC enzymes induced accelerations in the decrease and an increase in the AP2PL fluorescence intensity with two different increases in the FITC fluorescence intensity, showing that the same concentration of ATP is capable of inducing four different fluorescence changes. The addition of ATP to the Mg2+-Na+-bound enzymes modified with N-[p-(2-benzimidazolyl)phenyl]-maleimide (BIPM) at Cys-964 and retaining full Na+,K+-ATPase activity induced two different increases in BIPM fluorescence intensity. Each rate constant for the BIPM fluorescence change versus concentrations of ATP gave two intersecting straight lines. These data and the stoichiometries of fluorescence probe bindings and ATP- and AcP-dependent phosphorylation provide strong support for the conclusion that the functional membrane-bound Na+,K+-ATPase is a tetramer.

Adenosine Diphosphate↗
PubMed1998

Sinus histiocytosis with massive lymphadenopathy (Rosai-Dorfman disease).

Sinus histiocytosis with massive lymphadenopathy (SHML) is a distinct clinicopathological entity described by Rosai and Dorfman and differentiated by other childhood histiocytoses by its distinct characteristics. This is a rare pathology and should be kept in mind for differential diagnosis of neck masses, especially in childhood. In this article a case with SHML is presented and clinical features of the disease given.

Diagnosis, Differential↗
PubMed1998

Prognostic significance of PCNA expression in laryngeal cancer.

OBJECTIVE: To assess the prognostic value of proliferating cell nuclear antigen (PCNA) in laryngeal carcinoma and its relation with other known prognostic clinicopathologic variables. DESIGN: A retrospective cohort study of 92 patients chosen randomly from patients treated between 1964 and 1993 with the diagnosis of laryngeal cancer. Prognostic factors including PCNA expression, grade, lymphovascular invasion, depth of tumor margins, neck metastasis, and clinical outcome were evaluated. SETTING: Hacettepe University Medical Faculty, Ankara, Turkey. PATIENTS: Eighty-five men and 7 women operated on for squamous cell carcinoma of the larynx were studied. Sixty-nine patients had total and 20 patients had partial laryngectomy with neck dissection, and 3 patients had endolaryngeal tumor excision. INTERVENTION: Hematoxylin and eosin-stained sections were reevaluated for grade, lymphovascular invasion, and depth of tumor margins; sections stained with monoclonal antibody against PC10 were examined for PCNA expression. RESULTS: The PCNA index correlated with grade, lymphovascular invasion, depth of tumor margins, neck metastasis, and local-regional recurrence. The PCNA index values of patients with occult metastasis were significantly higher than those of patients without metastasis (P=.006). CONCLUSIONS: The PCNA index is a more sensitive variable than grade in predicting tumor proliferation, occult lymph node metastasis, and prognosis. These results suggest that the PCNA index can be used in decision making for treatment and assessment of prognosis in laryngeal carcinomas.

Adult↗
PubMed1998

Long-term survival following bronchotomy for polypoid bronchial carcinoid tumours.

OBJECTIVE: Typical bronchial carcinoids are very low grade neuroendocrine neoplasm of the tracheobronchial tree and have very good results in surgical treatment. Surgical treatment varies from bronchotomy-excision to major resective procedures. We presented our results of bronchotomy, simple excision and long-term follow-up. METHODS: In Atatürk Centre for Chest Disease and Chest Surgery, 16 patients with bronchial carcinoid tumour underwent bronchotomy-excision over a 23-year-period. In all of the cases tumours were in polypoid type. Except these 16 cases 51 patients with bronchial carcinoids underwent operations in the same period. Presenting symptoms were haemoptysis, cough, recurrent pulmonary infection, dyspnea and chest pain. Rigid bronchoscopies were performed on all of the patients preoperatively for diagnosis of the tumour and to determine the surgical procedure and we performed control bronchoscopies on all of the patients in their follow-up period. RESULTS: Patients were checked for periods ranging from 2 to 23 years both radiologically and bronchoscopically. We did not find any recurrences and death related to surgery and morbidity rate were minimal. CONCLUSION: We think that bronchotomy and simple excision are effective and safe procedures for the treatment of bronchial carcinoid tumours with low morbidity in selected cases like polypoid type lesions and have as good a long-term survival rate as the other surgical treatment methods have.

Adult↗
PubMed1998

Protein kinase-dependent phosphorylation of H,K ATPase-containing membranes from rat and pig stomachs.

Previously H,K ATPase preparations from pig stomach were shown to contain intrinsic protein kinase activities which phosphorylated specific tyrosine and serine residues in the N-terminal of the alpha-chain of H,K ATPase (Togawa et al. 1996). In the present investigation, pig H,K ATPase-containing membrane preparations were compared with rat preparations. In contrast to results obtained with the alpha-subunit of H,K ATPase from pig, phosphorylation was not observed in the rat enzyme. Addition of rat preparations to the pig preparations resulted in decreased phosphorylation in pig preparations. To follow the phosphorylation of membrane proteins in vivo, 32P-loaded gastric cells prepared from rat were stimulated with several secretagogues. Proteins with molecular weights of about 120 and 80 kDa were markedly phosphorylated upon stimulation, but the alpha-subunit of H,K ATPase was not. These results suggest that phosphorylation of tyrosine or serine residues of H,K ATPase found in pig H,K ATPase preparations may not be involved in the acid secretion pathway.

Animals↗
PubMed1998

Childhood chronic pleural empyema: a continuing surgical challenge in developing countries.

BACKGROUND: Surgical treatment may be necessary in childhood chronic pleural empyema. METHODS: Over a 21-year period 642 children with pleural empyema were hospitalized and 104 of them underwent surgical treatment. The records of the children who underwent surgery for the treatment of empyema were retrospectively reviewed to describe the role, indications, and results of surgical treatment of childhood chronic pleural empyema. RESULTS: Etiologic diseases or conditions leading to empyema were pneumonia in 69 patients, tuberculosis in 13, hydatid cyst in eight, postpneumonectomy empyema in five, and other causes in nine patients. Indications for surgery were severe pleural thickening in 54 cases (51.9%), trapped lung in 36 cases (34.6%), loculated empyema in eight cases (7.7%) and broncho-pleural fistula in six cases (5.8%). Operations performed were decortication in 90 patients, pulmonary resection and decortication in seven, muscle flap closure in five, and pneumonectomy in two. Success rates in the treatment of nonspecific and tuberculous empyema were 93% and 54%, respectively. CONCLUSIONS: Surgical treatment is still necessary in childhood pleural empyema in developing countries, and success rates are very high in nonspecific pleural empyema and acceptable in tuberculous pleural empyema.

Child↗
PubMed1998

Reliability of a hospital utilization review method in Turkey.

OBJECTIVE: To determine whether the Appropriateness Evaluation Protocol (AEP) is reliable in Turkey. METHODS: Three reviewers, two physicians and one nurse each reviewed 196 patient-days concurrently by using the AEP at three hospitals, two of which were teaching hospitals. Inter-reviewer reliability was assessed both for all cases reviewed (overall agreement), and for only those judged inappropriate by at least one reviewer (specific agreement). In addition, overall agreement between pairs of reviewers was evaluated by the Kappa statistic. RESULTS: The overall agreement between pairs of reviewers was very high: 93.4-95.9%, and it was similar between all pairs. The level of overall agreement was highly statistically significant: k=0.725-0.833, P<0.001. The specific agreement rates ranged from a low of 61.8% to a high of 75%. CONCLUSIONS: These results show, for the first time, that the AEP method is reliable in Turkey.

Hospitals, Teaching↗
PubMed1998

Fluorescein 5'-isothiocyanate-modified Na+, K+ -ATPase, at Lys-501 of the alpha-chain, accepts ATP independent of pyridoxal 5'-diphospho-5'-adenosine modification at Lys-480.

The modification of Na+,K+-ATPase with increasing pyridoxal 5'-diphospho-5'-adenosine (AP2PL) concentrations resulted in saturation of the approximately 0.5 mol AP2PL probe incorporation into the Lys-480/mol catalytic alpha-chain and reduced the Na+,K+-ATPase activity to around half without affecting the phosphorylation by acetyl phosphate (AcP), and led to increases in the AP2PL fluorescence caused by ATP and AcP. Further modification with fluorescein 5'-isothiocyanate (FITC) resulted in approximately 0.9 mol FITC probe incorporation into the Lys-501/mol alpha-chain and reduced the activity to below 5% without affecting the phosphorylation by AcP and these fluorescence increases. The ATP binding capacity of the AP2PL-FITC enzyme was shown to be at least 50% of that of the control enzyme (approximately 0.8 mol/mol alpha-chain). This is the first direct demonstration that Na+-bound FITC-modified enzymes accept ATP with an affinity for ATP (K(1/2) > 150 microM) reduced by two orders of magnitude. The data also suggest half site reactivity of Lys-480 as to AP2PL and all site reactivity of Lys-501 as to FITC in the catalytic subunits.

Adenosine Diphosphate↗
PubMed1998

Does binding of ouabain to human alpha1-subunit of Na+, K+-ATPase affect the ATPase activity of adjacent rat alpha1-subunit?

To ascertain whether ouabain binding to human alpha1-subunit influences coexpression of rat alpha1-subunit, the ouabain-sensitive profiles of Na+,K+-ATPase activity and 86Rb+ uptake activity and ouabain binding capacity were measured in HeLa cells stably expressing rat alpha1-subunit. The ouabain-sensitive profile of ATPase and 86Rb+ uptake activity seemed to be the sum of two components, one with high and one with low apparent affinity to ouabain, which were similar to that observed in HeLa and NRK-52E cells derived from human and rat, respectively. The ATPase activity with low sensitivity to ouabain increased in simple proportion to the amount of the rat alpha1 mRNA derived from transfected cDNA, which was determined by the reverse transcription-polymerase chain reaction method. The turnover number of the human Na+,K+-ATPase activity obtained from the ratio of the Na+,K+-ATPase activity to the ouabain binding capacity is about 150/sec. The expression of the rat alpha1-subunit had no effect on the turnover numbers of the Na+,K+-ATPase activity with high affinity to ouabain estimated from the ouabain binding capacity as the active site concentration. These results suggested that the ouabain bound to human alpha1-subunit did not inhibit the ATPase activity of the coexpressing rat alpha1 in these cells.

Animals↗
PubMed1997

Are pyridoxal and fluorescein probes in lysine residues of alpha-chain in Na+,K(+)-ATPase sensing ATP binding?

Na+,K(+)-ATPase preparations from pig kidneys were treated with 50 microM pyridoxal 5'-diphospho-5'-adenosine (AP2PL) in the presence of NaCl. The resulting preparations contained 0.5 mol of the AP2PL probe at the Lys-480/mol alpha-chain. This modification reduced both Na+,K(+)-ATPase activity and the amount of Na(+)-dependent phosphoenzyme from ATP to around 50% but not that from acetyl phosphate (AcP). The addition of 1 mM AcP to the modified enzyme in the presence of Mg2+ and Na+ induced phosphorylation (3.0/s) followed by an AP2PL fluorescence increase (1.2/s). The addition of 10 microM ATP instead of AcP induced rapid phosphorylation (28/s) followed by a slow increase in fluorescence (1.0/s). When modified enzyme preparations were treated with fluorescein 5'-isothiocyanate (FITC), the phosphorylation capacity from ATP was reduced to around 5% with little influence on either the AP2PL fluorescence change by ATP or phosphorylation from AcP. The addition of increasing concentrations of ATP with 160 mM NaCl to the K(+)-bound AP2PL-FITC-labeled enzyme showed different rates for each fluorescence change and different affinities for ATP of the changes. These data and others indicate that the AP2PL probe at Lys-480 can monitor ATP binding to high- and low-affinity sites and suggest the simultaneous presence of two different low-affinity sites for ATP detected by an AP2PL probe at Lys-480 and an FITC probe at Lys-501.

Adenosine Diphosphate↗
PubMed1997

A venous anomaly of the neck.

Vascular anomalies localize mostly in the head and neck region. Besides the complications they present, when they are left untouched, they are cosmetically ugly. A vascular lesion in any part of the body of a child is always bothersome to the parents and may be a problem for the family. The confusion about classification of these lesions and the delay in seeing the physician may adversely affect the child also. There has been a debate concerning the classification of vascular malformations, their clinical presentation, and their treatment modalities. In this paper we reviewed the classification as accepted in the literature and presented a case of huge venous anomaly in the neck region with its angiographic and MRI views and discussed the possible complications and modes of treatment.

Adolescent↗
PubMed1997

Blindness as a rare complication of neck dissection.

Blindness is a rare and rather unexpected complication of neck dissection. There have been only a few cases reported to date, all following bilateral neck dissections. We present a case of blindness after one-sided neck dissection and an insidious finding of bilateral common carotid artery occlusion.

Blindness↗
PubMed1997

Pleurectomy/decortication for palliation in malignant pleural mesothelioma: results of surgery.

OBJECTIVE: Surgery can only offer palliation in an attempt to slow the progression of malignant pleural mesothelioma (MPM). We want to assess the effectiveness and safety of pleurectomy/decortication in establishing a tissue diagnosis, and controlling pleural fluid accumulation and symptoms in patients with MPM. METHODS: We reviewed our pleurectomy results in 100 patients with MPM over a 19 year period. Major symptoms were chest pain, cough and dyspnea, and radiographic findings included pleural mass, pleural fluid and constriction of involved hemithorax. RESULTS: Approximately two thirds of the patients underwent surgery prior to tissue diagnosis. Eighty-nine patients had stage I and stage II disease, 8 and 81%, respectively. The patients underwent subtotal (44%) or total pleurectomy (56%). The surgical mortality rate was 1% (1/100) and the morbidity rate was 22%. Morbidity included prolonged air leak (n = 12), empyema (n = 6), reaccumulation of pleural fluid (n = 2) and wound infection (n = 2). Palliative results included dyspnea and cough relief in all patients, chest relief in 60 (85%) and pleural fluid control in 52 (96%) patients. Median survival was 17 months in MPM patients. CONCLUSIONS: We conclude that pleurectomy/decortication safely provides both tissue diagnosis and effective of pleural effusion and symptoms and therefore excellent palliation in patients with MPM.

Adolescent↗