Publications by authors named "Halil İbrahim Kisakesen"

2-Phenylethanol is an aromatic compound commonly used in the food, cosmetic, and pharmaceutical industries. Due to increasing demand for natural products by consumers, the production of this flavor by microbial fermentation is gaining interest, as a sustainable alternative to chemical synthesis or expensive plant extraction, both processes relying on the use of fossil resources. However, the drawback of the fermentation process is the high toxicity of 2-phenylethanol to the producing microorganism.

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Silver is a non-essential metal used in medical applications as an antimicrobial agent, but it is also toxic for biological systems. To investigate the molecular basis of silver resistance in yeast, we employed evolutionary engineering using successive batch cultures at gradually increased silver stress levels up to 0.25-mM AgNO in 29 populations and obtained highly silver-resistant and genetically stable Saccharomyces cerevisiae strains.

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Iron plays an essential role in all organisms and is involved in the structure of many biomolecules. It also regulates the Fenton reaction where highly reactive hydroxyl radicals occur. Iron is also important for microbial biodiversity, health and nutrition.

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Caffeine is a naturally occurring alkaloid, where its major consumption occurs with beverages such as coffee, soft drinks and tea. Despite a variety of reports on the effects of caffeine on diverse organisms including yeast, the complex molecular basis of caffeine resistance and response has yet to be understood. In this study, a caffeine-hyperresistant and genetically stable Saccharomyces cerevisiae mutant was obtained for the first time by evolutionary engineering, using batch selection in the presence of gradually increased caffeine stress levels and without any mutagenesis of the initial population prior to selection.

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Phenolic inhibitors in lignocellulosic hydrolysates interfere with the performance of fermenting microorganisms. Among these, coniferyl aldehyde is one of the most toxic inhibitors. In this study, genetically stable Saccharomyces cerevisiae mutants with high coniferyl aldehyde resistance were successfully obtained for the first time by using an evolutionary engineering strategy, based on the systematic application of increasing coniferyl aldehyde stress in batch cultures.

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Researchers have started focusing on investigating the anticarcinogenic effects of natural products with the slightest side effects possible, because current breast cancer treatment approaches are unable to achieve absolute success especially on aggressive subtypes. Propolis is among these products with its antimicrobial, antifungal, anti-inflammatory, and anticancer effects. Therefore, seven different samples were collected from different regions (Argentina, China, and Istanbul-Turkey) and applied on nonaggressive breast cancer cell line (BCCL) MCF-7 and aggressive cell lines SK-BR-3, and MDA-MB-231.

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High-throughput aging studies with yeast as a model organism involve transposon-mutagenesis and yeast knockout collection, which have been pivotal strategies for understanding the complex cellular aging process. In this study, a chronologically long-lived Saccharomyces cerevisiae mutant was successfully obtained by using another high-throughput approach, evolutionary engineering, based on systematic selection in successive batch cultures under gradually increasing levels of caloric restriction. Detailed comparative physiological and transcriptomic analyses of the chronologically long-lived mutant and the reference strain revealed enhanced levels of respiratory metabolism, upregulation of genes related to carbohydrate metabolic processes, glycogen-trehalose pathways, stress response, and repression of protein synthesis-related genes in the long-lived mutant SRM11, already in the absence of caloric restriction.

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Natural products with bioactive components are widely studied on various cancer cell lines for their possible cytotoxic effects, recently. Among these products, honey stands out as a valuable bee product containing many active phenolic compounds and flavonoids. Numerous types of multifloral honey and honeydew honey are produced in Turkey owing to its abundant vegetation.

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Preeclampsia (PE) is one of the leading causes of maternal and fetal morbidity and mortality, occurring usually in the second half of pregnancy and affecting approximately 5-8% of pregnancies in the world. miRNAs play critical role in the regulation of placental development processes. We aimed to determine specific novel miRNAs for early diagnosis of preeclampsia which is one of the most dangerous pregnancy diseases.

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There is growing attention focused on local estrogen production in the breast tissue and its possible role in breast cancer initiation and progression. Understanding the underlying mechanisms for estrogen synthesis and the microenvironment consisting of tumor and its surrounding adipose tissue might open new avenues in breast cancer prevention, prognosis and treatment. In order to obtain insight, we compared peritumoral and tumor tissue expressions of CYP17A1 and CYP19A1 genes, which play an important role in estrogen biosynthesis.

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miRNA involvement has been observed in almost every type of cancer, including breast cancer. The etiology of abnormal expression of miRNAs in cancer is still not clearly understood. In order to obtain insight into miRNA de-regulation in breast cancer, we analyzed expression levels of five breast cancer-related miRNAs, miRNA21, miRNA155, miRNA19a, miRNA17-5p and let7a miRNA, in both malignant and neighboring non-tumoral paraffin-embedded tissues of 47 patients with invasive ductal breast cancer.

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Background: The aim of this study was to investigate a possible association of the CYP1A1 Ile462Val and GSTM1 null polymorphisms with the risk of developing bladder cancer in a Turkish population.

Patients And Methods: The study constituted 176 patients with bladder cancer and 97 healthy individuals. Evaluation of CYP1A1 Ile462Val gene polymorphism was performed by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP).

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