AGE-RELATED CHANGES OF GLYCOLYTIC ACTIVITY AND ANTIOXIDANT CAPACITY IN THE BLOOD OF ALLOXAN DIABETIC RATS

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Introduction
Diabetes mellitus (DM) is one of the most prevalent endocrine diseases throughout the world. In recent years, a considerably increasing number of people have been found as having DM [4]. The increasing incidence of type 1 diabetes coupled with advances in the treatment of type 1 diabetes has resulted in an unprecedented number of older adult people living with and controllable type 1 diabetes [9].
It is known there are ontogenetic changes in the metabolism of human body [3]. Aging is characterized by a progressive deterioration in physiological functions and metabolic processes. The loss of cells during aging in vital tissues and organs is related to several factors including oxidative stress and inflammation [3].
Oxygen free radicals of mitochondrial origin seem to be involved in aging [12]. Available studies are consistent with the presumption that oxygen radicals endogenously produced by mitochondria are causally involved in setting the rate of aging in homeothermic vertebrates. Oxidative damage to tissue macromolecules seems to increase during aging. The rate of mitochondrial oxygen radical generation of post-mitotic tissues is negatively correlated with animal longevity.
Hyperglycaemia occurs commonly in acutely and critically ill patients and is associated with adverse clinical consequences. Hyperglycaemiamediated oxidative stress plays a crucial role in diabetic complications [6].
DM is characterized by metabolic disturbances. The most obvious symptom of diabetes, hyperglycaemia, is caused by inadequate uptake of glucose from the blood. DM manifests itself through hyperglycaemia due to an absolute or relative lack of insulin and/or insulin resistance [1,2]. A clinical diagnosis of dementia is likely preceded by a period of cognitive decline during which one's ability to properly manage glycaemia may be impacted; this is an especially important limitation in this population of older adults with type 1 diabetes where self-care plays such an important role in disease management [9].
A researcher Alisdair R Fernie claimed that the respiratory pathways of glycolysis, the tricarboxylic acid (TCA) cycle and the mitochondrial electron transport chain are ubiquitous throughout nature. They are essential for both energy provision in heterotrophic cells and a wide range of other physiological functions.
Glucose-6-phosphate dehydrogenase (insulindependent enzyme) is the first enzyme of pentose phosphate pathway. This enzyme accelerates the dehydrogenase reactions in oxidative stage of pentose phosphate pathway, which results in NADPH 2 formation. The cell regenerates reduced glutathione in a reaction catalyzed by glutathione reductase [5,7].
Ontogenetic shifts in the antioxidant system and carbohydrate metabolism including blood glycolysis against the DM background is less studied.
The objective of this experimental study was to assess the impact of aging on the level of basal glycaemia (BG) and activities of glucose-6phosphate dehydrogenase (G6PhD, [EC1.

Materials and Methods
The study was carries out in compliance with the Rules for All Vertebrate Animal Studies (1977) and the European Council Convention for the Protection of Vertebrate Animals used in experiments and for other scientific purposes (Strasbourg, 1986), and according to the directions of International Commit-tee of Medical Journals Editors (ICMJE), as well as to Bioethical expertise of preclinical and other scientific researches conducted on animals (Kyiv, 2006).We used 100 male Wistar rats divided into two age groups: the I group included 2-month (adult) rats, and the II group included 4-month (old) rats. Diabetes was modelled by injecting the rats with 5% solution of alloxan monohydrate intraperitoneally in a dose of 170 mg/kg. Blood was taken from the tail vein to evaluate basal glycaemia (BG) on 5-th and 47-th day after the alloxan injection. The rats were sacrificed on the 47-th day of the experiment in accordance with regulations on the ethical treatment of animals. Assessment of the activity of enzymes was performed by applying standard methods [13]. Statistical analysis was carried out by using Statistica 10 StatSoft Inc. To determine an adequate method of statistical estimation of the average difference between the study groups we used preliminary check of distribution quantities in samples. According to the Shapiro-Wilk test used to assess the normality of distribution in the sample volume n≤50, all samples, which did not receive data on deviation of the sample distribution from normal (p>0,05). Given these data, the use of Mann-Whitney test was considered sufficient for valid conclusions. Differences were considered to be statistically significant at p ≤ 0.05.

Results and Discussion
The BG level ( fig. 1) on the fifth day of the experiment in the animals of both groups increased on average by 115% from baseline values. We founded that on 47-th day this index was higher in group of old rats by 20% compared with the adult rats.  In our previous studies [6,7] we investigated Langerhans islands in alloxan-diabetic rats and recorded histomorphological alterations: their pancre-atic share reliably decreased by 55%, number and percentage of beta-cells with necrosis decreased diminished by 90% and 97% respectively compared with the control.
PK is the enzyme that catalyses the final step of glycolysis. It catalyses the transfer of a phosphate group from phosphoenolpyruvate (PEP) to adenosine diphosphate (ADP), yielding one molecule of pyruvate and one molecule of ATP.
PK activity ( fig. 2) in erythrocytes of adult and old animals with diabetes went down by 35% and 50% respectively compared with the control. The tendency toward the decrease in the PK activity can be explained by the fact that PK is regulated by in-sulin, which is less produced in conditions of alloxan-induced diabetes.
G6PhD activity ( fig. 3) in erythrocytes of the adult and old animals with diabetes decreased by 27% and 45% respectively compared with the control on 47-th day. This is associated with the reduced NADPH 2 production [8].
GR activity ( fig. 4) in erythrocytes of the adult and old animals with alloxan diabetes lowered by 29% and 35% respectively compared with the control on 47-th day. The changes may be explained by age-related disorders of glucose metabolism due to disturbances in free radical mechanisms. Moreover, hyperglycaemia leads to increased free radical mechanism and oxidative modification of protein (insulin and insulin-dependent enzyme) in old rats [11]. Decreased GR activity leads to decline in the reduced glutathione level. These changes may result from age-related disorders of free radical metabolism and age-related NADPH 2 deficiency [9, 10].
Although Yatabe et al. demonstrated somewhat uncertainty they suggest that intermediate blood glucose levels (110-180 mg/dL) may be regarded as the most optimal for adult critically ill patients, with 144-180 mg/dL probably being the preferred target, based on a lower risk of hypoglycaemia than 110-144 mg/dL. Though there have been studies showing a correlation between hypoglycemia and worsened clinical outcomes, a causal link has to be confirmed. Nonetheless, some researchers suggest even mild hypoglycaemia should be avoided in critically ill patients. Since patients who receive insulin infusion are at a higher risk of hypoglycaemia, a reliable tool for measuring blood glucose concentrations, such as an arterial blood gas analyzer, should be frequently used. Acute glycaemic control in patients with premorbid hyperglycaemia is a novel issue.

Conclusion
We have determined when getting aged, the alloxan-diabetic rats demonstrate changes in the sensitivity of pyruvate kinase, glucose-6-phosphate dehydrogenase and glutathione reductase activities in erythrocytes resulted from the effect of diabetes mellitus factors (hyperglycaemia). We can suggest that glycaemic control is key purpose for older patients with type 1 diabetes in order to prevent of complication, which can be aggravated with age factor. Зростаюча захворюваність на цукровий діабет 1-го типу в поєднанні з прогресом лікування діабету 1-го типу зумовила безпрецедентну кількість дорослих людей, які живуть та лікують діабет 1-го типу.
Annually, approximately 1.3 million new cases of colorectal cancer (CRC) are diagnosed worldwide [1]. The CRC development is preceded by an abnormal proliferation of the colonic mucosa that forms a polyp in most cases. The excessive proliferation is considered to be a result of a combination of unfavourable external factors (smoking, alcohol abuse, lack of plant fibre in the diet) and genetic predisposition, which through molecular-genetic modifications can trigger the "polyp-carcinoma" se-quence [2].
During the last decade, a significant amount of data regarding cancer stem cells (CSCs) subpopulation and their role in tumour initiation and progression has been accumulated [3][4][5]. CD44 is one of the most used markers of CSCs in CRC. Even though, the questions of its diagnostic and prognostic value for CRC patients are still remaining open [4].
CD44 is a transmembrane glycoprotein that is expressed by embryonic stem cells, as well as by some progenitor and mature cells, including cells of connective tissue and bone marrow [6]. According to the literature, the CD44 gene is a part of an intestinal stem cell gene signature [7]. In addition, it is known that CD44 expression is characteristic of the CSCs subpopulation [8]. The main ligand of CD44