İstanbul Sağlık ve Teknoloji Üniversitesi Kurumsal Akademik Arşivi
DSpace@İSTÜN, Üniversite mensupları tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Controlled bio-catalytic synthesis of ampyrone–vanillin macromolecules: Deciphering the transition from nano-oligomers to polymers and the limits of enzymatic stability
(Elsevier, 2026) Temizkan Özdamar, Kevser
This study reports the time-controlled biocatalytic synthesis of nanostructured macromolecules derived from heteroaromatic ampyrone and bio-based vanillin. By optimizing the reaction duration (2, 4, and 6 h) with Horseradish Peroxidase (HRP), stable nano-oligomers (NSO-1, NSO-2) and a robust polymer (nano-pores polymer/NP-P) were successfully isolated. The novelty of this work lies in the precise temporal mapping of the HRP-catalyzed process, identifying a 6 h ‘stability window’ that maximizes molecular growth (Mw = 5743 g/ mol, n ≈ 14) before the onset of enzymatic chain scission. Characterization revealed a significant reduction in the optical band gap from 2.38 eV to 1.49 eV and a morphological transition from macrocrystalline rods to nano porous matrices. These results demonstrate that temporal control in enzymatic synthesis enables fine-tuning of optoelectronic and thermal properties, positioning these sustainable hybrids as viable candidates for organic photovoltaics and smart material technologies.
The effects of early postnatal alcohol exposure on bone molecular composition in a mouse model
(Wiley, 2026) Dursun, İlknur; Elibol, Birsen; Garip Ustaoğlu, Şebnem
Background: Perinatal exposure to alcohol is a critical risk factor for long- term skeletal health in humans and has been demon strated in rodent models. Early postnatal alcohol gavage exposure in mice is used to study third trimester toxicity in humans. However, further research is required to fully characterize the effects of alcohol on bone molecular composition and distinguish them from the alterations associated with gavage- related stress in mouse models. Methods: Female mouse pups were assigned to untreated control (C), gavage control (GC), and alcohol- treated (A) groups. Between postnatal days 3 and 20, the A group received ethanol (3.0 g/kg/day) by intragastric gavage, while the GC group under went the same gavage procedure without any solution (neither milk nor ethanol). At postnatal day 90, femoral bone molecular composition and bone metabolism were evaluated by attenuated total reflection Fourier- transform infrared (ATR- FTIR) spec troscopy and biochemical studies. Results: Several ATR- FTIR- derived matrix and mineral- related alterations, including reduced total protein- related indices, lower collagen cross- link ratio, reduced mineral- to- matrix ratio, and increased crystallinity, were observed in both GC and A groups rel ative to untreated controls, indicating a substantial long- term influence of the gavage procedure itself. Compared with the GC, the A group showed additional selective differences, most notably reduced relative carbonate content and increased CTX- I levels. In the C group, serum 25(OH)D, PTH, and calcitonin levels differed from both GC and A groups, whereas osteocalcin was increased in the GC group relative to the C group, and no significant difference was observed between the GC and A groups. Conclusion: Prolonged neonatal gavage was associated with substantial long- term changes in bone molecular composition and several circulating bone- related hormonal markers. Against this background, postnatal alcohol exposure was associated with additional selective differences, particularly in CTX- I and relative carbonate content. These findings highlight the importance of discriminating between the effect of the procedure and the effect of alcohol in developmental models based on repeated neonatal gavage.
Neonatal dehydration and electrolyte disorders
(Nova Science Publishers, 2026) Günebak, Çiğdem Tuba; Keskin Sarılar, Zuhal; Samut Bülbül, Serap
Water constitutes the most prevalent substance within the human body, representing a fundamental component of bodily fluids. This vital element is indispensable for maintaining cellular homeostasis, accounting for approximately 75% of body weight in term infants. Water plays a pivotal role in a multitude of physiological processes. Dynamic alterations in body composition and fluid distribution are observed during the intrauterine period, labor, and the early postnatal period. The equilibrium of body fluid balance and distribution is contingent on the balance between water intake and loss. Dehydration is a prevalent issue in neonates, associated with considerable morbidity and mortality rates, and failure to promptly identify and manage this condition can result in severe complications. Dehydration is classified into three forms according to serum osmolality: hypernatremic, normonatremic (isonatremic), and hyponatremic dehydration. Sodium, potassium, magnesium, calcium, and phosphorus are vital for the maintenance of normal biochemical reactions and homeostatic functioning. Newborns in need of fluid electrolyte support should be evaluated by physical examination and other parameters (low urine volume, high urine density, high serum Na+), and treatment should be started rapidly.
A novel HPLC technique for the determination of casticin in pharmaceutical preparations and human plasma
(Marmara University Press, 2026) Egeli Yılmaz, Derya; Tırıs, Gizem; Kepekçi Tekkeli, Şerife Evrim
This study introduces a combined HPLC and UV detection technique for the quantification of casticin in capsule and human plasma samples. The chromatographic separation was carried out utilizing a C18 column (150 mm × 4.6 mm × 5 μm) at a temperature of 25 ºC. Isocratic elution with a mobile phase comprising 60:40 v/v (methanol-0.05% formic acid) was employed. Flow rate was adjusted 1 mL/min. The analyte was determined at a wavelength of 258 nm, with a retention time of 14.7±0.01 min. The developed method underwent validation according to ICH criteria, covering specificity, linearity, precision, accuracy, detection and quantitation limits, as well as robustness. The linear range was determined to be 10-60 ng/mL for both capsule and spiked plasma specimens. The suggested technique was performed to the analysis of casticin in spiked human plasma and pharmaceutical preparations, yielding a recovery of 106.04% and demonstrating precision through intra-day and inter-day experiments with the highest relative standard deviation (RSD %) value of 4.94. Consequently, the technique was performed to the quantifying of human plasma specimens from in a patient taking medication containing casticin.
Investigation of volumetric alterations in thalamic subnuclei in progressive and stable mild cognitive impairment using magnetic resonance imaging
(İstanbul University Press, 2026) Harı, Emre; Soylu, Can
Objective: This study aimed to evaluate the volumes of thalamic subnuclei known to function in large-scale cognitive networks between progressive mild cognitive impairment (pMCI) and stable MCI (sMCI) groups progressing to dementia. Materials and Methods: Magnetic resonance imaging and clinical data of 31 pMCI (Age: 68.66±6.86; education: 15.71±2.46; gender: 15 female) and 31 sMCI (Age: 70.18±7.24; education: 16.23±2.68; gender: 13 female) patients with no statistically significant differences in age, gender, education, and follow-up interval (mean 21 months) from the Alzheimer's Disease Neuroimaging Initiative database were used. FreeSurfer software was used for individual thalamus segmentation and volume calculation. Thalamic nuclei were divided into anterior, medial, posterior, lateral, ventral, and intralaminar nucleus groups. The volumes of each nucleus were normalised using intracranial volume. Normalised volumes were compared between groups using independent samples t-test, and false discovery rate (FDR) correction was applied. Correlation analysis was performed using florbetapir (AV45) PET scores to evaluate the relationship between amyloid burden in the brain and volumetric decrease. Results: Statistically significant volumetric decreases were detected in the bilateral anterior (Right: t=2.432 pFDR=0.048; Left: t=2.327 pFDR=0.048) and lateral (t=2.372 pFDR=0.048) nucleus groups in pMCI compared to sMCI. A negative correlation was found between PET scores and bilateral anterior nucleus groups (Right: r=-0.353 p=0.026, left: r=-0.350 p=0.026). Conclusion: In our study, the anterior thalamic nucleus group, closely associated with memory, showed reduced volume in MCI patients who progressed to dementia, and this reduction correlated with amyloid burden in the brain. Based on the findings of our study, the anterior thalamic nucleus group may provide supportive value to other MRI biomarkers in predicting conversion to dementia.
