Oxidative stress in colonic adenocarcinoma: An impact on the body's antioxidative status and oxidative protein damage.

BACKGROUND: Thus far, the pathogenesis of these intestinal tumors has not been fully explained. However, the analysis of risk factors and research regarding their formation that have continued for 3 decades have allowed us to demonstrate a significant role of oxidative stress in the processes leading to the development of cancer in the large intestine as well as in some other organs. OBJECTIVES: The aim of the study was to examine the level of anti-oxidative status and the degree of oxidative protein damage in patients with varying severity of colonic adenocarcinoma (CAC) in relation to healthy individuals. MATERIAL AND METHODS: The study involved 4 groups (A-D) of patients with increasing severity of CAC stages according to Dukes' classification and a control group of healthy volunteers. Total antioxidant capacity (TAC) of blood plasma, as well as carbonyl (C=O) group contents in blood plasma proteins as a product of their oxidative damage, were estimated in all participants. Both parameters were determined by spectrophotometric methods using commercial kit to test TAC and 2,4-dinitrophenylhydrazine to assay the contents of C=O groups. RESULTS: In each of the studied groups, A-D, a statistically significant reduction in the TAC values was noted relative to the control group, which progressed with increased severity of CAC stages: 1.783 mmol/L vs 1.191 mmol/L (group A), 1.07 mmol/L (group B), 0.931 mmol/L (group C), and 0.899 mmol/L (group D). At the same time, significantly increased contents of protein C=O groups were observed compared to the controls, also progressive in the course of growing CAC severity: 0.496 nmol/mg protein vs 0.57 nmol/mg protein (group A), 0.689 nmol/mg protein (group B), 0.804 nmol/mg protein (group C), and 1.054 nmol/mg protein (group D). CONCLUSIONS: The CAC-related oxidative stress considerably reduces the systemic anti-oxidative status and increases the protein damage; both those changes become worse in parallel with the progression of this cancer.

Vitamin C modulates DNA damage induced by hydrogen peroxide in human colorectal adenocarcinoma cell lines (HT29) estimated by comet assay in vitro.

INTRODUCTION: Cancer cells, compared to normal cells, are under increased oxidative stress associated with oncogenic transformation, alterations in metabolic activity, and increased generation of reactive oxygen species. MATERIAL AND METHODS: We investigated the ability of vitamin C to reduce the damage induced by hydrogen peroxide, in human colorectal adenocarcinoma cells in vitro by the comet assay. Additionally, we measured the kinetics and efficacy of the repair of DNA damage after incubation with vitamin C in the presence of H2O2. RESULTS: The obtained results showed that 1 h pre-incubation with vitamin C and exposure to H2O2 for the last 10 min of incubation caused a statistically significant (p < 0.05) increase in DNA migration in comet tails in all experimental series. For the 10 µM, 25 µM, 50 µM, 100 µM vitamin C concentrations the levels of DNA damage were as follows: 18.6%, 21.1%, 25.3% and 27.2%, respectively, as compared to the untreated cells (3.26%). However, in comparison with H2O2 alone (29.1%), we observed a statistically significant (p < 0.05) decrease of the genotoxic effect in HT29 cells induced by H2O2 for the two lowest of concentrations of vitamin C: 10 µM and 25 µM. The HT29 cells were able to achieve effective repair of the damaged DNA within 60 and 120 min after incubation with the tested compounds. All the values obtained in the test were statistically significant (p < 0.05). CONCLUSIONS: Vitamin C caused a weaker DNA damaging effect of hydrogen peroxide and positively influences the level of oxidative DNA damage in HT29 cells (decrease ∼ 30%). We noted that DNA damage was effectively repaired during 120 min postincubation in the tested cells and that oxidative damage was the major type of damage.

Adverse effects of antioxidative vitamins.

High doses of synthetic antioxidative vitamins: A, E, C and ß-carotene are often used on long-term basis in numerous preventive and therapeutic medical applications. Instead of expected health effects, the use of those vitamins may however lead to cases of hypervitaminosis and even to intoxication. The article points out main principles of safety which are to be observed during supplementation with antioxidative vitamins. Toxic effects resulting from erroneous administration of high doses of those substances on organs and systems of the organism are also discussed. Attention is drawn to interactions of antioxidative vitamins with concomitantly used drugs, as well as intensification of adverse effects caused by various exogenous chemical factors. Moreover, the article presents the evaluation of supplementation with these vitamins, which was performed in large studies.

Vacuolar H(+)-ATPase subunits Voa1 and Voa2 cooperatively regulate secretory vesicle acidification, transmitter uptake, and storage.

The Vo sector of the vacuolar H(+)-ATPase is a multisubunit complex that forms a proteolipid pore. Among the four isoforms (a1-a4) of subunit Voa, the isoform(s) critical for secretory vesicle acidification have yet to be identified. An independent function of Voa1 in exocytosis has been suggested. Here we investigate the function of Voa isoforms in secretory vesicle acidification and exocytosis by using neurosecretory PC12 cells. Fluorescence-tagged and endogenous Voa1 are primarily localized on secretory vesicles, whereas fluorescence-tagged Voa2 and Voa3 are enriched on the Golgi and early endosomes, respectively. To elucidate the functional roles of Voa1 and Voa2, we engineered PC12 cells in which Voa1, Voa2, or both are stably down-regulated. Our results reveal significant reductions in the acidification and transmitter uptake/storage of dense-core vesicles by knockdown of Voa1 and more dramatically of Voa1/Voa2 but not of Voa2. Overexpressing knockdown-resistant Voa1 suppresses the acidification defect caused by the Voa1/Voa2 knockdown. Unexpectedly, Ca(2+)-dependent peptide secretion is largely unaffected in Voa1 or Voa1/Voa2 knockdown cells. Our data demonstrate that Voa1 and Voa2 cooperatively regulate the acidification and transmitter uptake/storage of dense-core vesicles, whereas they might not be as critical for exocytosis as recently proposed.

EMG frequency during isometric, submaximal activity: a statistical model for biceps brachii.

The purpose of this study was to develop a statistical model to describe the electromyography (EMG) signal frequency changes during a submaximal isometric contraction. Thirty subjects performed a 30-second isometric contraction of the biceps brachii muscle at 80% of the maximal voluntary isometric force. Surface EMG electrodes recorded electrical activity of the biceps brachii. Zero-Crossing-Rate was calculated to identify EMG frequency shifts. The mean frequencies for every one-second period were used to calculate a linear relationship between frequency and time. A significant relationship (p<0.05) between slope and initial frequency value was identified. The model described EMG frequency changes during submaximal effort of biceps brachii up to 15 seconds. The prediction error was 9.8%. Modifying this equation to initial values of frequency of each participant decreased prediction error to 7.2%. These results demonstrate that despite individual differences between subjects it is possible to derive single equation that describes EMG alterations during submaximal, isometric contractions across a homogeneous group of people.

[The estimation of antioxidative vitamins concetrations in blood plasma of patients with neoplasms of gallblader and biliary tract]. / Ocena stezen witamin antyoksydacyjnych w osoczu krwi chorych z nowotworami pecherzyka i dróg zólciowych.

Gallbladder and biliary tract cancer is a serious clinical problem. In-spite of wide range of new diagnostic and therapeutic methods, the significant improvement of treatment results, has not been noticed so far. The research about prevention methods, seems to be important, among the ways of improvement of the diagnosis and therapy outcomes of these diseases. It is related for example to study about one of the cause of biliary tract carcinogenesis--the imbalance between production of reactive oxygen species (ROS) and their inactivation by the antioxidative barrier. One of the components of this organism protection complex are antioxidative vitamins. The aim of this study was to measure the concentration of antioxidative vitamins (A, C, E, and beta-carotene) in serum, in patients with cancer of gallbladder and and biliary tract, in comparison to the results of healthy volunteers. The study groups comprised of 56 patients, both sexes with acute and chronic cholecystitis and with above-mentioned neoplasmas. The results shoved, that concentration of antioxidative vitamins in serum of patients with gallbladder and biliary tract cancer, was significantly decreased. The outcomes of this research, seem to confirm the participation of antioxidative barrier in inhibition of carcinogenesis of in those important parts of digestive system.

[The influence of the increasing doses of vitamin C on the concentration of the substance reacting with thiobarbituric acid (TBARS) in mice liver]. / Wplyw wzrastajacych dawek witaminy C na stezenie substancji reagujacych z kwasem tiobarbiturowym (TBARS) w watrobie myszy.

Ascorbic acid is known antioxidant protecting many organs and tissues. In some circumstances can act as prooxidant, particullary when coexists with high concentration of ferrum and copper jons. Condition like that can take place for example in liver. In this research Vitamin C was administered to the mice in increasing dosages, then the concentration of TBARS-prooxidant markers was measured in homogenats of their livers. The outcomes of the research are equivocal.

[Antioxidative properties of vitamin E as a new approach to its applications in therapy]. / Wlasciwosci antyoksydacyjne witaminy E podstawa jej nowych zastosowan w terapii.

The article presents current state of knowledge about antioxidative action of vitamin E, enabling significant broadening of its possible application in medicine. Mechanisms are discussed due to which it takes a very important part in protection of an organism against effects of oxidative stress. Followed from here consequences of this vitamin deficiencies were indicated. Detailed review was made of its role in counteracting diseases of the largest social significance: cancer and cardiovascular system diseases. Attention was paid to observed controversies and discrepancies in therapeutic effects. Unfavourable effects that could appear with application of large doses of vitamin E, typical for antioxidative therapy, were characterised.

[The biomedical aspects of the non-antioxidative action of vitamin E and its resulting role in therapy]. / Biomedyczne aspekty nieantyoksydacyjnego dzialania witaminy E i wynikajacej z nich jej roli w terapii.

The review of current informations connected with the non-antioxidative applications of vitamin E in therapy was performed. After explanation indispensable structural and nomenclatural questions, were have talked over was for above mentioned uses: biological activity of this vitamin, food sources and the metabolism. It was presented the systemic non-antioxidative functions and the resulting actions from here with range of prevention. The attention on day requirement, the states of deficiency and hypovitaminosis, and also on normal concentration in blood plasma was emphasized.

Adaptation of the phosphotungstate method to determine reduced and oxidized vitamin C in blood plasma.

The phosphotungstate reagent (PTR) was used for quantitative spectrophotometric determination of physiological forms of vitamin C in blood plasma. An immediate action of PTR on the first half of the tested samples allowed to determine reduced vitamin C concentrations (I) at 700 nm. 10 mM dithiothreitol added to the second half of the samples reduced oxidized vitamin C in it--hence the total amount of this vitamin was reduced with a concentration (II) determined as above (remains of dithiothreitol were removed with N-ethylmaleimide). The difference of results (II) and (I) gave the concentration of oxidized vitamin C. The method is characterised by fault-less analytical parameters: correlation coefficients of analytical curves > 0.99, recovery factor 100.5%, variation coefficients intra- and inter-serial < 3% and < 5%, respectively, detection limit 0.05 microM. The simplicity of the method enables an easy control of the ratio of oxidized and reduced vitamin C concentrations in blood plasma--the biomarker of the level of oxidative damage to cells.

[Gallbladder motor activity in patients with virus hepatitis B]. / Czynnosc motoryczna pecherzyka zólciowego u chorych z wirusowym zapaleniem watroby typu B.

In acute stage of virus hepatitis B patients often complain of dyspeptic discomfort. They may be a consequence of alimentary tract motor activity disorders including these of gallbladder. Routine ultrasonography in an early phase of virus hepatitis often reveals gallbladder wall thickening what may confirm the above thesis. Thus, a group of 15 patients in an acute phase of virus hepatitis B was subjected to examinations. Gallbladder motor activity was assessed by ultrasonographic method determining its total volume and ejection fraction and volume after test meal stimulus. First examination was performed in the first week since the appearance of yellowing of the walls, successive in 4 and 8 week of the disease. Obtained results were compared to the values obtained in the group of 25 healthy volunteers. It was found out that gallbladder volume was significantly decreased and ejection fraction increased in the acute phase of virus hepatitis B than in the controls. This may speak for gallbladder hyperreactivity in patients in the course of virus hepatitis B. These disorders decreased during two-month observation but even in the 8 week the investigated parameters differed from those found in the control group.

[Dental mask of gastroesophageal reflux disease]. / Maska stomatologiczna choroby refluksowej przelyku.

In the last few years the interest of extraesophageal symptoms of gastroesophageal reflux disease is getting greater and greater. Because of it is often appearance, this disease is noticed not only by gastroenterologists, but also other doctors and dentists. They think that pathological, backward reflux of esophagus in many cases can be responsible for dental organ disease. Clinical research proofs that often pouring the sour mixture from the stomach into the esophagus and then to mouth can cause a diminution in the teeth such as: erosion and decay. The background agum and tounque can be gastroesophageal reflux disease. acquantance with this facts among the dentists can help to make a diagnosis and treat well patients with a pathological reflux of esophagus.

Adaptation of the phosphotungstate method for the determination of vitamin C contents in animal and human tissues.

The usefulness of phosphotungstate reagent for vitamin C determination in tissue homogenates has been confirmed. An optimal homogenization medium was selected: 1.8 M solution of HPO3 in 1.3 M CH3COOH. With this medium the analytical curve (at 700 nm) demonstrated the right linearity, correlation and recovery coefficients were appropriately high (0.999 and 99.8%) and the values of intraserial and interserial variation coefficient were low (< 5% and < 10%, respectively). It makes this method sensitive, easily repeatable, and useful for vitamin C determination in animal and human tissues, including neoplastic ones.