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Biomedical subjects

H Kaya

Publications and source records attributed to H Kaya.

At least 37 records · Page 2Linked to original sources
PubMed2001

Prevalence of human papillomavirus (HPV) DNA in larynx and lung carcinomas.

In this retrospective study, we investigated the HPV DNA occurrence in 21 laryngeal and 26 primary lung squamous cell carcinomas. Nonisotopic in situ hybridization (NISH) technique was performed with commercially available digoxigenin-labelled DNA probes for HPV screening. Subtyping for HPV subtypes 6/11, 16/18 and 31/33 was also performed. We observed HPV DNA signals in 10 (47.6%) cases of laryngeal SCC and in only 3 (11.5%) cases of lung SCC. Typing showed signals of HPV 6/11, 16/18 and 31/33 infection in 80%, 40%, 30% of the laryngeal carcinomas, respectively. In the lung, we demonstrated type 16/18 positivity in two and type 6/11 in one of the HPV-positive cases. We found a statistically significant correlation between HPV infection and tumour recurrence (p < 0.035) in laryngeal carcinomas, but not between HPV presence and tumour stage or grade in neither larynx nor lung.

Carcinoma, Squamous Cell↗
PubMed2001

Drug resistance in epithelial ovarian cancer: P-glycoprotein and glutation S-transferase. Can they play an important role in detecting response to platinum-based chemotherapy as a first-line therapy.

OBJECTIVE: Drug resistance is important for the treatment of ovarian cancer. P-glycoprotein and glutation S-transferase as resistance markers play an important role in the effectivity of chemotherapeutical agents. The role of P-glycoprotein and glutation S-transferase in the treatment of epithelial ovarian cancer is not well understood. We investigated the relation between P-glycoprotein and glutation S-transferase level for response to platinum-based chemotherapy in epithelial ovarian cancer. MATERIAL AND METHODS: We reviewed 30 cases diagnosed as epithelial ovarian cancer and treated with platinum-based chemotherapy in the Department of Obstetrics and Gynecology, Akdeniz University School of Medicine. The material was attained from initial parafin-embeded blocks stained for P-glycoprotein and glutation S-transferase. The cases that were diagnosed and treated before attending our clinic were not enrolled in the study. RESULTS: Mean age was 58.2 (25-70) and mean gravida 4.1 (0-10). Twenty-four patients (80%) were glutation S-transferase positive. Three cases (10%) out of 30 had positive reaction for P-glycoprotein. No difference was revealed regarding chemotherapy response rate among the cases showing glutation S-transferase positivity and P-glycoprotein negativity. CONCLUSION: Detection of glutation S-transferase and P-glycoprotein levels in epithelial ovarian cancer tissue is not important for response to platinum-based chemotherapy as a first line.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2000

Energetic components of cooperative protein folding.

A new lattice protein model with a four-helix bundle ground state is analyzed by a parameter-space Monte Carlo histogram technique to evaluate the effects of an extensive variety of model potentials on folding thermodynamics. Cooperative helical formation and contact energies based on a 5-letter alphabet are found to be insufficient to satisfy calorimetric and other experimental criteria for two-state folding. Such proteinlike behaviors are predicted, however, by models with polypeptidelike local conformational restrictions and environment-dependent hydrogen-bondinglike interactions.

Calorimetry↗
PubMed2000

Polymer principles of protein calorimetric two-state cooperativity.

The experimental calorimetric two-state criterion requires the van't Hoff enthalpy DeltaH(vH) around the folding/unfolding transition midpoint to be equal or very close to the calorimetric enthalpy DeltaH(cal) of the entire transition. We use an analytical model with experimental parameters from chymotrypsin inhibitor 2 to elucidate the relationship among several different van't Hoff enthalpies used in calorimetric analyses. Under reasonable assumptions, the implications of these DeltaH(vH)'s being approximately equal to DeltaH(cal) are equivalent: Enthalpic variations among denatured conformations in real proteins are much narrower than some previous lattice-model estimates, suggesting that the energy landscape theory "folding to glass transition temperature ratio" T(f) /T(g) may exceed 6.0 for real calorimetrically two-state proteins. Several popular three-dimensional lattice protein models, with different numbers of residue types in their alphabets, are found to fall short of the high experimental standard for being calorimetrically two-state. Some models postulate a multiple-conformation native state with substantial pre-denaturational energetic fluctuations well below the unfolding transition temperature, or predict a significant post-denaturational continuous conformational expansion of the denatured ensemble at temperatures well above the transition point, or both. These scenarios either disagree with experiments on protein size and dynamics, or are inconsistent with conventional interpretation of calorimetric data. However, when empirical linear baseline subtractions are employed, the resulting DeltaH(vH)/DeltaH(cal)'s for some models can be increased to values closer to unity, and baseline subtractions are found to correspond roughly to an operational definition of native-state conformational diversity. These results necessitate a re-assessment of theoretical models and experimental interpretations.

Calorimetry↗
PubMed2000

Human pulp reaction to dentine bonded amalgam restorations: a histologic study.

OBJECTIVE: The aim of this study was to investigate the human pulp response to Scotchbond Multi Purpose Plus (SMPP) bonding agent in non-exposed Class V cavities. METHODS: SMPP was placed in 24 of 40 cavites according to manufacturer's instructions and the cavities were restored with amalgam. The remaining 16 cavities were capped with a calcium hydroxide formulation (Dycal) sealed with zinc-oxide eugenol, and restored with the amalgam. After extraction at 10 and 35 days, the teeth were fixed, sectioned and stained for light microscopy. RESULTS: All Dycal-capped teeth, at both 10 and 35 days, exhibited no pulp inflammation and no demonstrable bacteria. Six cases sealed with SMPP at 10 days showed no pulp inflammation or stained bacterial profiles. The remaining six teeth demonstrated mild to moderate inflammatory pulpal responses and five out of these six cases exhibited stained bacterial profiles. Nine out of 12 teeth showed no inflammatory pulp responses at 35 days, the remaining three cases exhibited mild to moderate pulp inflammation without stained bacteria. CONCLUSIONS: None of the teeth sealed with SMPP presented severe inflammatory pulpal reactions histologically. SMPP did not exhibit significant deleterious effects on the human pulp tissue during the test periods.

Adolescent↗
PubMed2000

Essential thrombocythemia and recurrent myocardial infarction.

We report the case of recurrent myocardial infarction with essential thrombocythemia (ET) in a 61-year-old female patient. Only one report of recurrence of myocardial infarction has been previously described. Coronary angiography 10 days after the infarction was normal. Thrombocythemia had been controlled with hydroxyurea.

Angina, Unstable↗
PubMed2000

Severe and prolonged febrile myalgia in familial Mediterranean fever.

Familial Mediterranean fever (FMF) is characterized by recurrent attacks of fever and serositis. Typical attacks of FMF last 3 to 5 days. Fever and myalgia are not always improved by colchicine therapy and sometimes require steroid therapy. We present two cases of severe prolonged febrile myalgia where steroid therapy was needed.

Adolescent↗
PubMed2000

hosoba toge toge, a syndrome caused by a large chromosomal deletion associated with a T-DNA insertion in Arabidopsis.

We isolated a T-DNA-tagged mutant named hosoba toge toge (hot) in which a pleiotropic phenotype was observed in both the shoot and root throughout the life cycle. The phenotype and allelism indicated that the mutant has a defect in both the FASCIATA1 (FAS1) gene and the FT gene located on the bottom arm of chromosome 1. Analysis of the junctions between the T-DNA ends and the plant genome suggested the presence of a 75.8-kbp deletion at the insertion site. In addition to FAS1 and FT, 13 genes were predicted to exist in the region corresponding to that deleted in hot. They include homologs of genes for type II inositol-1,4,5-triphosphate 5-phosphatase (IP5Pase), the beta-chain of N-acetyl-beta-glucosaminidase (NAGase), NADPH oxidoreductase of the zeta-crystallin family, polygalacturonase, and endo-1,4-beta-glucanase. Although most aspects of the hot phenotype can be explained by loss of FAS1 and FT functions, some novel phenotypic features which may represent aspects of a mutant phenotype due to loss-of-function of other gene(s) were observed. One "wild-type" ecotype and a previously reported T-DNA insertion line, neither of which has any obvious phenotypic abnormality, carry a possible loss-of-function mutation in the zeta-crystallin homolog and in the NAGase beta chain homolog, respectively.

Arabidopsis↗
PubMed2000

Reduced levels of 1,25-dihydroxyvitamin D(3) in rat dams and offspring after exposure to a reconstituted PCB mixture.

Previous studies revealed effects of polychlorinated biphenyls (PCBs) and other polyhalogenated hydrocarbons on steroid hormone levels and hormone-dependent functions including behavior. In the present study serum concentrations of the vitamin D(3) metabolites 25-hydroxycholecalciferol (25-D) and 1,25-dihydroxycholecalciferol (1,25-D) were determined in rat dams and offspring after exposure to a PCB mixture that was reconstituted according to the congener pattern found in human breast milk. Unmated females were exposed to diets adulterated with 0; 5; 20; or 40 mg PCBs/kg diet. Exposure started 50 days prior to mating and was terminated at birth. Gestational exposure reduced serum concentrations of 1,25-D in dams in a dose-dependent manner. Concentration of 25-D was also decreased at the time of delivery, but not at weaning. Determination of 1,25-D in offspring at weaning revealed reductions in both high-exposure groups. Levels of 25-D were diminished only at the highest exposure level. Internal PCB concentrations in adipose tissue and brains exhibited a linear relation to dosages in diet. Concentrations of PCBs in brains were similar in dams and offspring at birth, but decreased at the end of lactation in dams. In offspring, values increased during this period because of continued exposure via the milk. In the adipose tissue, PCB levels were much lower in offspring than in dams. To our knowledge, this is the first report of PCB-induced effects on vitamin D(3) metabolites. In dams, reductions were seen even at the lowest exposure level used. Further studies are needed to evaluate the biological significance of these reductions in pregnant dams and possible consequences for the developing offspring.

Adipose Tissue↗
PubMed2000

Delocalization transition of a rough adsorption-reaction interface

We introduce a kinetic interface model suitable for simulating adsorption-reaction processes which take place preferentially at surface defects such as steps and vacancies. As the average interface velocity is taken to zero, the self-affine interface with Kardar-Parisi-Zhang-like scaling behavior undergoes a delocalization transition with critical exponents that fall into a different universality class. As the critical point is approached, the interface becomes a multivalued, multiply connected self-similar fractal set. The scaling behavior and critical exponents of the relevant correlation functions are determined from Monte Carlo simulations and scaling arguments.

Journal Article↗
PubMed2000

Multiplicity of ordered phases in frustrated systems obtained from hard-spin mean-field theory

Random quenched dilution of the triangular-lattice antiferromagnetic Ising model locally relieves frustration, leading to ordering phenomena. We have studied this system, under such dilution of one sublattice, using hard-spin mean-field theory. After a threshold dilution, two sublattices develop nonzero magnetizations of equal magnitude and opposite signs, as all three sublattices exhibit spin-glass order. In this phase, multiple sets of ordered solutions occur. A phase diagram is obtained in dilution fraction and temperature.

Journal Article↗
PubMed2000

Lipid peroxidation in umbilical arterial blood at birth: the effects of breech delivery.

OBJECTIVE: To determine oxygen free radical activity in breech presentation at birth and relate it to umbilical cord blood acid-base status. DESIGN: A series of 63 singleton deliveries (28 cephalic deliveries as controls), 23 breech deliveries with normoacidemia, and 12 breech deliveries with mild acidaemia) had determination of malondialdehyde and acid-base parameters. SETTING: The delivery suite in the Department of Obstetrics and Gynaecology at the Süleyman Demirel University, Isparta, Turkey. PARTICIPANTS: Sixty-three singleton infants born at term with spontaneous or induced labour and initially normal fetal heart rate tracing. METHODS: After delivery, umbilical cord arterial and venous blood samples were collected for the determination of malondialdehyde concentrations. Oxygen saturation, pO2, pCO2, pH, and base excess were also measured. MAIN OUTCOME MEASURES: Umbilical cord arterial and venous blood gases and malondialdehyde levels. RESULTS: There was a significant correlation between umbilical arterial and venous levels of malondialdehyde and all acid-base parameters (P < 0.001). There were negative correlations between malondialdehyde levels and pH, pO2 and bicarbonate, while there was a positive correlation between malondialdehyde concentrations and pCO2. A positive correlation between malondialdehyde levels and base excess was present in the control group and total breech group (n = 35). The malondialdehyde levels in the total breech group, nonacidaemic breech group (n = 23) and the mildly acidaemic breech group (n = 12) were significantly higher than those in the control group (P < 0.0001). However, acid-base parameters in the nonacidaemic breech group were not statistically different from those in the control group. CONCLUSION: Lipid peroxidation products (malondialdehyde) existed to some extent in the umbilical cords of newborns with normal acid-base parameters in breech delivery. Our data support the contention that lipid peroxide may be a more sensitive measure for metabolic dysfunctions due to fetal hypoxia than acid-base balance.

Acid-Base Imbalance↗
PubMed2000

Effects of calcium and calcium chelators on growth and morphology of Escherichia coli L-form NC-7.

Growth of a wall-less, L-form of Escherichia coli specifically requires calcium, and in its absence, cells ceased dividing, became spherical, swelled, developed large vacuoles, and eventually lysed. The key cell division protein, FtsZ, was present in the L-form at a concentration five times less than that in the parental strain. One interpretation of these results is that the L-form possesses an enzoskeleton partly regulated by calcium.

Bacterial Proteins↗
PubMed2000

Trisomy 14 with thrombocytosis and monocytosis.

It has been reported that trisomy 14 is associated with myeloid malignancies, but a case with increased platelet count has also been reported. However, the clinical significance of trisomy 14 is still uncertain. We report a patient with trisomy 14 with thrombocytosis and a gradual increase in monocytosis. He was treated with hydroxyurea, cytarabine and aclarubicin in low doses and his quality of life was maintained for a period of about 1 year from blastic crisis. Hydroxyurea, cytarabine or aclarubicin in low doses may be the treatment of choice for trisomy 14 patients with respect to the patients' quality of life.

Aclarubicin↗
PubMed2000

Induction of experimental periodontitis in mice with Porphyromonas gingivalis-adhered ligatures.

BACKGROUND: Little information is available on the colonization of periodontopathic bacteria and alveolar bone loss in a mouse system, because of the difficulty in establishing bacteria in the oral cavity. The aim of this study was to establish experimental periodontitis in mice by applying a Porphyromonas gingivalis-adhered ligature onto the molars. METHODS: Specific pathogen-free C3H/HeN mice were divided into 3 groups: 80 infected, 80 sham-infected, and 48 non-treated control mice. Sterile silk ligatures were preincubated with and without P. gingivalis 381 in vitro and then physically tied on the right maxillary first molar of infected and sham-infected mice, respectively. Ten mice from the infected and sham-infected groups and 6 from the control group were sacrificed at 2-week intervals for up to 15 weeks after infection. RESULTS: Plaque samples were collected at the time of sacrifice and alveolar bone loss was examined. The results indicated that P. gingivalis was recovered from the plaque samples in 95% of the infected mice after 1 week and then gradually dropped to 58% after 15 weeks of infection, whereas P. gingivalis was not isolated in either sham-infected or control mice throughout the experimental period. The infected mice showed significant P. gingivalis-induced bone loss at the sites where the ligature was tied weeks 13 to 15. A linear regression analysis revealed a significant positive correlation between the number of P. gingivalis recovered and alveolar bone loss at 15 weeks after infection (P <0.01). CONCLUSIONS: The use of a P. gingivalis-adhered ligature supported a long-lasting infection of P. gingivalis in mice, resulting in P. gingivalis-induced alveolar bone breakdown.

Alveolar Bone Loss↗
PubMed1999

A pair of related genes with antagonistic roles in mediating flowering signals.

Flowering in Arabidopsis is promoted via several interacting pathways. A photoperiod-dependent pathway relays signals from photoreceptors to a transcription factor gene, CONSTANS (CO), which activates downstream meristem identity genes such as LEAFY (LFY). FT, together with LFY, promotes flowering and is positively regulated by CO. Loss of FT causes delay in flowering, whereas overexpression of FT results in precocious flowering independent of CO or photoperiod. FT acts in part downstream of CO and mediates signals for flowering in an antagonistic manner with its homologous gene, TERMINAL FLOWER1 (TFL1).

Amino Acid Sequence↗
PubMed1999

The effect of melatonin on lipid peroxidation during radiotherapy in female rats.

BACKGROUND: Because radiotherapy is one of the causes of primary or secondary ovarian failure, protection of ovarian functions in the patients receiving total body or pelvic radiotherapy is of importance. In this study, we investigated the role of melatonin in the oxidative damage in both whole body and ovaries, which is caused by radiotherapy. MATERIALS AND METHODS: Eighteen female rats were divided into 3 groups, each of which consisted of 6 rats. First group was control group receiving no treatment, second group received total body radiotherapy (RT) by 2 x 360 cGy only and third group received radiotherapy plus melatonin. Malondialdehyde (MDA) levels in both blood and ovarian tissue were detected as the indicator of free radical (FR) damage. Levels of erythrocyte superoxide dismutase (SOD) and glutathion peroxidase (GPX) in blood were measured as the indicators of antioxidant level. RESULTS: Radiotherapy caused a significant increase in the levels of MDA in blood and ovarian tissue (p < 0.001). However, MDA levels decreased in the radiotherapy plus melatonin group (p < 0.05). SOD and GPX levels decreased insignificantly in the radiotherapy only group while they increased in the radiotherapy plus melatonin group significantly (p < 0.01 and p < 0.05, respectively). CONCLUSION: Melatonin, in rats, reduced the level of MDA, which is elevated by radiotherapy and increased the levels of SOD and GPX, which are involved in the antioxidant system.

Animals↗