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Y Atalay

Publications and source records attributed to Y Atalay.

At least 19 recordsLinked to original sources
PubMed2006

Theoretical studies of molecular structure and vibrational spectra of melaminium citrate.

The molecular geometry and vibrational frequencies of melaminium citrate in the ground state have been calculated using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-31G(d) basis set. The optimized geometric bond lengths and bond angles obtained by using HF and density functional theory (DFT, B3LYP) show the best agreement with the experimental data. Comparison of the observed fundamental vibrational frequencies of melaminium citrate and calculated results by density functional B3LYP and Hartree-Fock methods indicate that B3LYP is superior to the scaled Hartree-Fock approach for molecular vibrational problems.

Citrates↗
PubMed2006

A theoretical study on 1-(thiophen-2-yl-methyl)-2-(thiophen-2-yl)-1H-benzimidazole.

The molecular geometry and vibrational frequencies of 1-(thiophen-2-yl-methyl)-2-(thiophen-2-yl)-1H-benzimidazole (C(16)H(12)N(2)S(2)) in the ground state has been calculated using the Hartree-Fock (HF) and density functional method (B3LYP) with 6-31G(d) basis set. The optimized geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP) show the best agreement with the experimental data. Comparison of the observed fundamental vibrational frequencies of 1-(thiophen-2-yl-methyl)-2-(thiophen-2-yl)-1H-benzimidazole (C(16)H(12)N(2)S(2)) and calculated results by density functional B3LYP and Hartree-Fock methods indicate that B3LYP is superior to the scaled Hartree-Fock approach for molecular vibrational problems.

Benzimidazoles↗
PubMed2006

A theoretical study on N-phenyl-N'-(2-thienylmethylene)hydrazine.

The molecular geometry and vibrational frequencies of N-phenyl-N'-(2-thienylmethylene)hydrazine (C11H10N2S) have been calculated using Hartree-Fock and density functional method (B3LYP) with 6-31G(d) basis set. The optimized geometric bond lengths and angles obtained using HF and DFT (B3LYP) are in agreement with the experimental data. B3LYP method seems to be appropriate than HF method for the calculation of vibrational frequencies and geometrical parameters of the (C11H10N2S) compound.

Heterocyclic Compounds, 2-Ring↗
PubMed2006

The molecular structure and vibrational spectra of 1-amino-5-benzoyl-4-phenylpyrimidin-2(1H) by Hartree-Fock and density functional methods.

The molecular structure and vibrational spectra of 1-amino-5-benzoyl-4-phenylpyrimidin-2(1H) (C(17)H(13)N(3)O(2)) have been investigated by Hartree-Fock and density functional method using standard B3LYP with 6-31G(d) basis set. The calculated results of the geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP) are in very good agreement with the experimental values. Comparison of the observed fundamental vibrational frequencies of 1-amino-5-benzoyl-4-phenylpyrimidin-2(1H) (C(17)H(13)N(3)O(2)) and calculated results by density functional B3LYP and Hartree-Fock methods indicate that B3LYP is superior to the scaled Hartree-Fock approach for molecular vibrational problems.

Algorithms↗
PubMed2006

Vibrational spectra and molecular structure of chiral and racemic 4-phenyl-1,3-oxazolidin-2-one by density functional theory and ab initio Hartree-Fock calculations.

The vibrational frequencies and molecular geometry of (R)- and (rac)-4-phenly-1,3-oxazolidin-2-one (4-POO) in the ground state have been calculated using the Hartree-Fock and density functional method (B3LYP) with 6-31G(d) basis set. The optimized geometric bond lengths are described better by HF while bond angles are reproduced more accurately by DFT (B3LYP). Comparison of the observed fundamental vibrational frequencies of (R)-POO and (rac)-4-POO and calculated results by density functional B3LYP and Hartree-Fock methods indicate that B3LYP is superior to the scaled Hartree-Fock approach for molecular vibrational problems.

Oxazolidinones↗
PubMed2005

Use of the bayley infant neurodevelopmental screener with premature infants.

OBJECTIVE: To examine the utility of the Bayley Infant Neurodevelopmental Screener (BINS) for the neurodevelopmental follow up of high-risk preterms. METHODS: The study group consisted of 122 preterm infants of the gestational ages between 26 and 37 weeks. Medical factors such as; mean birth weight, gestational age, gender, birth place and type, number of multiple pregnancy, days of hospitalization and oxygen therapy, use of antenatal steroids, and occurrence of sepsis for each patient were evaluated. The neurodevelopmental examination and BINS administration was made at each visit to the patients whose ages were adjusted for prematurity. RESULTS: At the corrected age of 7-10 months patients at 26-29 GA had significantly lower total means of BINS scores when compared to those of the other two groups at 30-32 and 33-37 GA (P<0.01 and P<0.001). At the corrected age of 3-4 months, the total means of the BINS scores of the patients at 30-32 GA were lower than that of the patients at 33-37 GA (P<0.009). at 7-10 months the scores of the items defining the expressive and cognitive functions of the patients at 26-29 GA were lower than those of the patients at 30-32 GA (P<0.05) and 33-37 GA (P<0.05). At 16-20 months the mean scores of the items of expressive functions were significantly lower in patients of the 26-29 GA compared to those of the patients of 33-37 GA (P<0.03). CONCLUSION: As data accumulates, BINS will turn out to be a quick way of determining infants at risk of developmental delay in many aspects of neurologically high risk conditions.

Age Factors↗
PubMed2005

Theoretical studies of molecular structure and vibrational spectra of 2-amino-5-phenyl-1,3,4-thiadiazole.

The molecular geometry and vibrational frequencies of 2-amino-5-phenyl-1,3,4-thiadiazole (C8H7N3S) in the ground state has been calculated using the Hartree-Fock and density functional method (B3LYP) with 6-31G(d) basis set. The optimized geometric bond lengths and bond angles obtained by using HF and DFT (B3LYP) show the best agreement with the experimental data. Comparison of the observed fundamental vibrational frequencies of 2-amino-5-phenyl-1,3,4-thiadiazole (C8H7N3S) and calculated results by density functional B3LYP and Hartree-Fock methods indicate that B3LYP is superior to the scaled Hartree-Fock approach for molecular vibrational problems.

Guanidines↗
PubMed2004

Umbilical cord ghrelin concentrations in small- and appropriate-for-gestational age newborn infants: relationship to anthropometric markers.

Ghrelin is a newly discovered orexigenic peptide originating from the stomach. Circulating ghrelin levels reflect acute and chronic energy balance in humans. However, it is not known whether ghrelin also plays a role in energy homeostasis during fetal life. Forty-one small-for-gestational age (SGA) and 34 appropriate-for-gestational age (AGA) infants were studied in order to determine whether cord blood ghrelin concentrations were different in SGA infants compared with AGA infants and the relationship to anthropometric measurements at delivery. The cord blood ghrelin concentrations of SGA infants (means+/-S.E.M.; 15.20+/-3.08 ng/ml) were significantly greater than of AGA infants (2.19+/-0.24 ng/ml) (P<0.0001). They were negatively correlated with the infants' birth weights (r=-0.481, P<0.0001) and with body mass index values (r=-0.363, P<0.001). The higher ghrelin concentrations were found in female infants (20.42+/-4.55 ng/ml) than in males (7.05+/-2.27 ng/ml) in the SGA group (P=0.042). These data provide the first evidence that cord ghrelin levels of SGA infants are greater than those of AGA infants and it is suggested that ghrelin is also affected by nutritional status in the intrauterine period.

Birth Weight↗
PubMed2001

Asymptomatic neonatal cholelithiasis.

Cholelithiasis in neonates and infants has been rarely reported. With the current widespread use of diagnostic ultrasonography, more neonates may be found with gallstones and common bile duct stones. We describe a case of asymptomatic gallstones detected incidentally at the age of four days who presented with early onset of neonatal sepsis and dehydration.

Cholelithiasis↗
PubMed2001

Caffeine intoxication in a premature neonate.

Caffeine, which has a wide range between therapeutic and toxic levels, is a widely used medication for prevention and treatment of apnoea of prematurity. Despite its safety, caffeine overdose and intoxication has been previously reported in the literature. We present a 30-day-old 28-week preterm newborn who was exposed to 300 mg.kg-1 caffeine base by mouth accidentally. The patient exhibited agitations, irritability, tachycardia, tachypnoea, diuresis, electrolyte abnormalities, hyperglycaemia and metabolic acidosis, for which he received supportive treatment. No seizure activity was observed. The effects of intoxication lasted for 96 h and then completely resolved.

Caffeine↗
PubMed2000

Neonatal cerebral venous thrombosis coexisting with bilateral adrenal hemorrhage.

We report a case of severe perinatal asphyxia with both cerebral venous thrombosis and adrenal hemorrhage who survived with severe sequela including multicystic encephalomalasia, acquired microcephaly and blindness. Hematological investigations showed normal levels of anticardiolipin antibodies, protein C and S levels and activity, antithrombin III levels. Factor V Leiden mutation was negative. The adrenal hemorrhage resolved within three months with glucocorticoid therapy, the cerebral venous thrombosis resolved within two months without treatment. The literature on neonatal cerebral venous thrombosis is also reviewed.

Adrenal Gland Diseases↗
PubMed2000

Urinary nitric oxide in newborns with infections.

BACKGROUND: Neonatal sepsis is a major problem in newborn nurseries because of the difficulty in early diagnosis and because of the high morbidity and mortality. The objective of the present study was to investigate whether urinary nitric oxide (NO) levels could be useful for the diagnosis of infected newborns. METHODS: Newborns with suspected infection according to previously defined criteria between ages of 1-7 days and 8-30 days were included as the study groups (p) to be compared with age-matched healthy controls (c). Urine NO levels were assayed by Sievers NOA based on chemiluminescence and expressed as corrected for urine creatinine. RESULTS: 20 newborns with suspected infection at 1-7 days of age (group 1p) were compared with 45 healthy age-matched newborns (group 1c). 16 newborns with suspected infection at 8-30 days of age (group 2p) were compared with 15 healthy age-matched newborns (group 2c). The groups were similar with regard to birth weight and gestational age; however, the urinary NO levels in newborns with suspected infection at 1-7 days of age (80.25+/-60.68 micromol/mg creatinine) were higher than in healthy newborns (25.45+/- 19.35 micromol/mg creatinine). Similarly, newborns with suspected infection at 8-30 days of age had higher urinary NO levels (81.78+/- 40.43 micromol/mg creatinine) than age-matched controls (36.99+/-24.58 micromol/mg creatinine; p < 0.05). The sensitivity of urinary NO levels to detect infection was 50% in both age groups, and the specificity was 95% for 1-7 days of age and 93% for 8-30 days of age. Groups 1p and 2p were similar with regard to NO production. Altogether 12 patients had culture-proven sepsis, 11 patients had clinical sepsis, and 13 patients had other infections. The NO levels were similar in patients with culture-proven and clinical sepsis and higher than in patients with other infections. No difference was observed among NO levels of patients with gram-positive and gram-negative sepsis. CONCLUSIONS: Urinary NO levels which are quick and easy to measure are higher in infected newborns as compared with controls, and although the specificity is good, the sensitivity of the test is low, necessitating the use of another marker in addition to NO.

Biomarkers↗
PubMed1999

Excitatory amino acids and taurine levels in cerebrospinal fluid of hypoxic ischemic encephalopathy in newborn.

The recent studies indicating the transiently enhanced expression of excitatory amino acid receptors in hypoxia vulnerable brain regions and the elevated concentration of aspartate and glutamate in cerebrospinal fluid of asphyxiated newborns strongly suggest the role of excitatory amino acids in hypoxic ischemic brain damage in the developing human brain. In this study, we compared the concentrations of glutamate, aspartate, taurine and glycine in the cerebrospinal fluid of asphyxiated infants with values of a healthy control group. The concentrations of aspartate (5.82 +/- 3.36), glutamate (1.76 +/- 1.0) and taurine (9.32 +/- 9.1) were significantly elevated in cerebrospinal fluid of asphyxiated infants (P < 0.05). When compared to the control group, the high levels of aspartate was correlated with the degrees of hypoxic-ischemic encephalopathy (HIE) and the varying outcome. The high levels of aspartate and glutamate in the asphyxiated patients adds further evidence to the role of excitotoxicity in hypoxic ischemic encephalopathy. The mental and motor development of the patients in asphyxiated group was followed for 3 years.

Aspartic Acid↗
PubMed1999

Plasma leptin levels of large for gestational age and small for gestational age infants.

The hormone leptin produced in the adipose tissue is involved in the regulation of body weight. This study investigates whether plasma leptin levels are related to an infant's birthweight, and whether the levels change with feeding. We measured plasma leptin levels from infants who were large for gestational age (n = 21), small for gestational age (n = 21), and appropriate for gestational age (n = 20). Two blood samples were collected before and after breastfeeding from each infant and plasma leptin concentrations were determined by radioimmunoassay. Leptin concentration was found to be increased in large for gestational age infants and to be decreased in small for gestational age infants compared with the level in appropriate for gestational age infants. There was a positive correlation between plasma leptin levels and both the infants' birthweights and the body mass indexes. Plasma leptin concentrations were found to be decreased during fasting and to be increased after feeding (p < 0.01). It is concluded that the plasma leptin levels correlate with the size of adipose tissue mass and are related to the nutritional status.

Anthropometry↗