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Biomedical subjects

S Kaya

Publications and source records attributed to S Kaya.

At least 73 records · Page 4Linked to original sources
PubMed1997

MR imaging in squamous cell carcinoma of the head and neck with no palpable lymph nodes.

PURPOSE: To assess the efficacy of MR imaging in the detection of lymph node metastasis in patients with no palpable lymph nodes ("N0 neck") who have squamous cell carcinoma of the head and neck region. MATERIAL AND METHODS: MR neck imagings in 18 patients who underwent neck dissection (bilaterally in 2) for squamous cell carcinoma of the head and neck region were examined preoperatively for the purpose of detecting lymph node metastases. The imaging features taken into consideration were: size (cutoff point 10 mm), grouping, presence of central necrosis, and appearance of extracapsular spread. The MR examinations comprised spin-echo T1- and T2-weighted sequences. The MR findings were compared with those of surgery and histopathological examination. RESULTS: MR suggested metastatic lymph node involvement in 5 necks. In 2 of these, central necrosis was seen in the enlarged lymph nodes. In a third, a grouping of the lymph nodes was noted. Extracapsular spread was not present. Histopathological examination revealed metastatic lymph nodes in 7 of the 20 necks, the rate of clinically occult disease being 35%, and 4 of them had been accurately graded by MR. There was one false-positive MR examination. The MR sensitivity was 57.1% and specificity 92.3%. CONCLUSION: MR may reveal metastatic lymph nodes in patients with no clinical evidence of metastasis. However, conventional MR techniques are not always sufficient for decision-making on surgery in cases of "N0 neck".

Adult↗
PubMed1997

ATP-induced dynamic fluorescence changes of a N-[p-(2-benzimidazolyl)phenyl]maleimide probe at Cys241 in the alpha-chain of pig stomach H+,K+-ATPase.

H+,K+-ATPase preparations from pig stomach were modified with a sulfhydryl fluorescence reagent, N-[p-(2-benzimidazolyl)phenyl] maleimide (BIPM). The addition of ATP to the modified enzyme preparations in the presence of Mg2+ decreased the BIPM fluorescence but increased the Trp fluorescence. After exhaustion of ATP, the fluorescence intensities increased and decreased to the original levels, respectively. The results of stopped flow and rapid quenching experiments suggested that the decrease in BIPM fluorescence (36/s) was accompanied by binding of Mg2+ and ATP or phosphorylation (35 36/s) which was followed by slower increases in Trp fluorescence (24/s) and light scattering (20/s). Tosylphenylalanyl chloromethyl ketone-trypsin treatment of the modified preparations, which showed an about 1% decrease in BIPM fluorescence accompanying phosphorylation, gave one major fluorescent peptide peak on reverse-phase chromatography. Amino acid sequence analysis of the peptide revealed the following sequence, Ser-Pro-Glu-X-Thr-His-Glu-Ser-Pro-Leu-Glu-Thr-Arg. On comparison with the amino acid sequence deduced from cDNA from pig stomach [Maeda, M., Ishizaki, J., and Futai, M. (1988) Biochem. Biophys. Res. Commun. 157, 203-209], X was shown to correspond to Cys241 of the alpha-chain in H+,K+-ATPase. These data and others suggest that the decrease in BIPM fluorescence at Cys241 reflects some molecular event triggered by the binding of ATP with Mg2+ and/or phosphorylation, whereas the increases in the intrinsic Trp fluorescence and light scattering reflect one after phosphorylation.

Adenosine Triphosphate↗
PubMed1996

Ser-27, Tyr-10 and Tyr-7 in the alpha-chain of pig stomach H+,K(+)-ATPase as Ca(2+)-dependent phosphorylatable sites by intrinsic and extrinsic protein kinases.

When pig stomach membrane H+,K(+)-ATPase preparations were incubated with [gamma-32P]ATP, Mg2+ and Ca2+, reversible phosphorylation of specific Tyr and Ser residues in the N-terminal alpha-chain of H+,K(+)-ATPase occurred without any detectable phosphorylation in other regions of the alpha-chain. Mild tosylphenylalanyl chloromethyl ketone trypsin treatment followed by reverse-phase column chromatography yielded three radioactive peptide peaks. The first peak contained both Tyr10(32P) and Tyr7(32P) and the second peak contained Tyr10(32P). The third peak contained Ser27(32P) which was also obtained after trypsin treatment of partially purified H+,K(+)-ATPase preparations phosphorylated with protein kinase-C + Ca2+ or protein kinase-A. This is the first demonstration of Ca2(+)-dependent phosphorylation of the alpha-chain of H+,K(+)-ATPase by protein kinases.

Amino Acid Sequence↗
PubMed1996

Clinical experience with minitracheotomy.

In minitracheotomy, a relatively simple percutaneous technique for tracheal cannulation, a small-bore tube is inserted via the cricothyroid membrane to provide access to suction removal of excess secretion or aspirated material from the tracheobronchial tree. It allows efficient tracheobronchial toilet while preserving glottic function and avoiding the disadvantages of conventional tracheostomy and endotracheal intubation. The indications for minitracheotomy in 20 cases were excessive postoperative or postpneumonic secretion (14), difficulty with endotracheal suction (5) and acute airway obstruction (1). The only major complication was bleeding in one case. Minor bleeding occurred at the incision in two cases. The cannula was retained for 3-8 days and removal was followed by closure within 48 hours. There were no adverse laryngeal effects. Minitracheotomy was well tolerated by the patients and is a useful adjunct for removal of airway secretion and hospitalized patients.

Adolescent↗
PubMed1996

Role of MRI in the diagnosis of otitic hydrocephalus.

The pathogenesis of otitic hydrocephalus still remains doubtful. Magnetic resonance imaging (MRI) demonstrated sigmoid and transverse sinus thrombosis in two consecutive patients. The role of MRI in the diagnosis and pathogenesis of this complication, together with literature findings, is discussed. Until now, lumbar puncture, which is a minimally invasive technique, was the only diagnostic measure. MRI, however, can be used to establish the diagnosis of otitic hydrocephalus by showing the thrombosis in the sigmoid and transverse sinus.

Child, Preschool↗
PubMed1995

Reversible phosphorylation of both Tyr7 and Tyr10 in the alpha-chain of pig stomach H+,K(+)-ATPase by a membrane-bound kinase and a phosphatase.

When pig stomach membrane H+,K(+)-ATPase preparations were incubated with [gamma-32P]ATP and Mg2+ with vanadate, 32P was incorporated into the alpha-chain of H+,K(+)-ATPase to a steady-state level of approximately 0.7 mol of phosphotyrosine (Tyr(P))/mol of phosphoenzyme intermediates. The addition of a membrane H+,K(+)-ATPase preparation with Mg2+ accelerated the liberation of 32P from Tyr(P) residues in the alpha-chain. Mild tosylphenylalanyl chloromethyl ketone-trypsin treatment solubilized 32P-containing peptides from the alpha-chain almost completely. A reverse-phase column chromatography of the supernatant gave two peaks of 32P-peptide with similar total radioactivities. The amino acid sequence of both peaks was shown to be Gly-Lys-Ala-Glu-Asn-Tyr-Glu-Leu-Tyr-Gln--, which is consistent with the amino-terminal sequence of the alpha-chain of H+,K(+)-ATPase deduced from cDNA from pig stomach except that the initial Met was absent. The comparison of the recovery of amino acid from each Edman cycle showed that the phosphorylation of Tyr10 occurred preceding the phosphorylation of Tyr7. These data and others suggested the presence of a novel membrane-bound enzyme system to participate in reversible phosphorylation of both Tyr residues in the alpha-chain of H+,K(+)-ATPase.

Amino Acid Sequence↗
PubMed1994

Pyridoxal 5'-phosphate probes at Lys-480 can sense the binding of ATP and the formation of phosphoenzymes in Na+,K(+)-ATPase.

The Lys-480 in the alpha-subunits of Na+,K(+)-ATPase from pig kidneys was specifically modified with pyridoxal 5'-phosphate (PLP) or pyridoxal 5'-diphospho-5'-adenosine (AP2PL) probes in the presence of NaCl. The site was shown to be the same as the ATP-protectable binding of these probes (Hinz, H.R., and Kirley, T.L. (1990) J. Biol. Chem. 265, 10260-10265). Modifications strongly reduced both Na+,K(+)-ATPase activity and the amount of Na(+)-dependent phosphoenzyme from [32P]ATP but not from [32P]acetyl-phosphate (AcP). Addition of AcP to the enzyme induced a slight decrease in the fluorescence of the PLP probe in the presence of 2 M NaCl and 4 mM MgCl2 but a single exponential increase in the presence of 16 mM NaCl and 4 mM MgCl2. The addition of ATP induced single exponential fluorescence increases at both Na+ concentrations. The data show that these probes can sense molecular events related to the formation of phosphoenzymes induced by AcP and presumably to the formation of Mg-Na-ATP-enzyme complex. The data also suggest that PLP or AP2PL probes at Lys-480 in the presence of Na+ and Mg2+ do not affect the transphosphorylation from AcP to Asp-369 to form phosphoenzymes but that they inhibit the transphosphorylation from the gamma-phosphoryl group of ATP and also ATP binding in the absence of Mg2+.

Adenosine Triphosphate↗
PubMed1994

Lymphoma with bilateral cavernous sinus involvement in early childhood.

A 4-year-old girl developed complete ophthalmoplegia with intact pupillary responses. Computed tomography and magnetic resonance imaging demonstrated a mass invading the cavernous and sphenoid sinuses and posterior ethmoidal cells. Biopsy revealed non-Hodgkin lymphoma. This patient is the youngest reported with malignant lymphoma of the cavernous sinus and the second reported with bilateral cavernous sinus involvement.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

[Prenatal diagnosis of severe stenosis of the ductus arteriosus Botalli in a twin pregnancy].

Premature ductus arteriosus stenosis is a rare cardiovascular disease, which has a poor prognosis. The case presented was detected even in early pregnancy and was progressed rapidly to the stage of severe foetal heart failure. The patient was first seen at 20 weeks of gestation with one of the foetuses of a twin pregnancy, showing signs of cardiac decompensation and advanced hydrops fetalis universalis. Obstruction of the ductus arteriosus may result from maternal tocolysis treatment with prostaglandin synthetase inhibitors, such as indomethacin or maternal salicylate or in conjunction with foetal post maturity.

Adult↗
PubMed1994

Different susceptibility to phospholipase A2 treatment of the fluorescence intensity changes in the vicinity of Cys-964 and Lys-501 in the alpha-chain of probe-labeled Na+,K(+)-ATPase.

Phospholipase A2 [EC 3.1.1.4] treatment of pig kidney Na+,K(+)-ATPase [EC 3.6.1.3] labeled with fluorescence probes at the alpha-chain reduced the extent of the fluorescence intensity change of an N-[p-(2-benzimidazolyl)phenyl]maleimide (BIPM) probe at Cys-964 to below one-third of the control level accompanying the accumulation of phosphoenzymes. However, it only induced a slight decrease in that of a fluorescence isothiocyanate (FITC) probe at Lys-501 with a large decrease in the rate of change. The addition of phosphatidylserine (PS) or phosphatidylinositol (PI) to the phospholipase-treated BIPM-FITC-labeled enzyme increased the rate of the FITC fluorescence change. Phospholipase treatment of the BIPM-enzyme greatly reduced the Na+,K(+)-ATPase activity. The addition of PS or PI to the treated enzyme induced reactivation. These data and others suggest that Cys-964 and Glu-953 (Rb+ protectable dicyclohexyl carbodiimide binding site) are located in the vicinity of the surface area of the enzyme where hydrocarbon chains of phospholipids are present, and conserved H-bonding amino acids, Thr-955 and Ser-962, are located rather near the center of a domain forming a cation binding route or cage with other hydrophobic transmembrane segments. These data may indicate that the interaction between the BIPM probe and the hydrocarbon chains of phospholipids changes in such a way as to sense the change in the binding state of various ligands accompanying the sequential appearance of reaction intermediates of the enzyme.

Acrylamides↗
PubMed1994

An extra phosphorylation of Na+,K(+)-ATPase by paranitrophenylphosphate (pNPP): evidence for the oligomeric nature of the enzyme.

Paranitrophenylphosphate (pNPP) induced fluorescence changes in fluorescence isothiocyanate (FITC)-labeled Na+,K(+)-ATPase preparations. The extents of changes were similar to those induced by acetylphosphate (AcP) accompanying accumulation of a K(+)-sensitive phosphoenzyme (E2P) and an ouabain bound phosphoenzyme in the presence of Mg2+ and 16 mM Na+. Phosphoenzymes formed from [32P]pNPP were shown to turn over. The ratio of the maximum amount of the phosphoenzyme formed from pNPP to that of the phosphoenzyme formed from ATP and that of the ouabain-enzyme complex under steady-state conditions was shown to be close to 1:0.5:1. Such extra phosphorylation has hitherto only been observed in a transient state with the additions of high concentrations of ATP [Peluffo, R.D., Garrahan, P.J., and Rega, A. (1992) J. Biol. Chem. 267, 6596-6601]. Our data are compatible with the simultaneous presence of high and low affinity ATP-binding sites in Na+,K(+)-ATPase [Hamer, E. and Schoner, W. (1993) Eur. J. Biochem. 213, 743-748]. The maximum amount of paranitrophenol-sensitive fraction to synthesize [32P]pNPP in fully accumulated ADP-sensitive phosphoenzyme (E1P) from [32P]ATP was around 1/4 of the amount of ouabain-enzyme complex. These data and others indicate that a much higher degree of oligomerization, rather than (alpha beta)2, may be the functional unit of the enzyme in the membranes.

Adenosine Triphosphate↗
PubMed1994

Management of intrathoracic goitre.

A retrospective review is presented of 20 cases with resection of intrathoracic goitre between 1975 and 1993. The mean age of the 11 men and nine women was 53 years. The intrathoracic goitre was primary in seven cases and secondary in 13. The presenting clinical features and the pathology, surgical risks and optimal approaches are discussed. Primary intrathoracic goitre should be approached via a thoracotomy, because of the independent vascular supply. As secondary intrathoracic goitres are supplied by vascular pedicles arising from the inferior thyroid artery, a cervical collar incision is preferable. In the event of significant mediastinal bleeding, which is difficult to control from a cervical incision, a T-shaped incision for partial or full sternotomy can be performed, or even thoracotomy.

Adult↗