Chasing Graphene-Based Anticancer Drugs: Where are We Now on the Biomedical Graphene Roadmap?

Graphene and graphene-based materials have attracted growing interest for potential applications in medicine because of their good biocompatibility, cargo capability and possible surface functionalizations. In parallel, prototypic graphene-based devices have been developed to diagnose, imaging and track tumor growth in cancer patients. There is a growing number of reports on the use of graphene and its functionalized derivatives in the design of innovative drugs delivery systems, photothermal and photodynamic cancer therapy, and as a platform to combine multiple therapies. The aim of this review is to introduce the latest scientific achievements in the field of innovative composite graphene materials as potentially applied in cancer therapy. The "Technology and Innovation Roadmap" published in the Graphene Flagship indicates, that the first anti-cancer drugs using graphene and graphene-derived materials will have appeared on the market by 2030. However, it is necessary to broaden understanding of graphene-based material interactions with cellular metabolism and signaling at the functional level, as well as toxicity. The main aspects of further research should elucidate how treatment methods (e.g., photothermal therapy, photodynamic therapy, combination therapy) and the physicochemical properties of graphene materials influence their ability to modulate autophagy and kill cancer cells. Interestingly, recent scientific reports also prove that graphene nanocomposites modulate cancer cell death by inducing precise autophagy dysfunctions caused by lysosome damage. It turns out as well that developing photothermal oncological treatments, it should be taken into account that near-infrared-II radiation (1000-1500 nm) is a better option than NIR-I (750-1000 nm) because it can penetrate deeper into tissues due to less scattering at longer wavelengths radiation.

2-Methoxyestradiol and Hydrogen Peroxide as Promising Biomarkers in Parkinson's Disease

Estrogens function in numerous physiological processes including controlling brain cell growth and differentiation. 2-Methoxestradiol (2-ME2), a 17β-estradiol (E2) metabolite, is known for its anticancer effects as observed both in vivo and in vitro. 2-ME2 affects all actively dividing cells, including neurons. The study aimed to determine whether 2-ME2 is a potentially cancer-protective or rather neurodegenerative agent in a specific tissue culture model as well as a clinical setup. In this study, 2-ME2 activity was determined in a Parkinson's disease (PD) in vitro model based on the neuroblastoma SH-SY5Y cell line. The obtained results suggest that 2-ME2 generates nitro-oxidative stress and controls heat shock proteins (HSP), resulting in DNA strand breakage and apoptosis. On the one hand, it may affect intensely dividing cells preventing cancer development; however, on the other hand, this kind of activity within the central nervous system may promote neurodegenerative diseases like PD. Thus, the translational value of 2-ME2's neurotoxic activity in a PD in vitro model was also investigated. LC-MS/MS technique was used to evaluate estrogens and their derivatives, namely, hydroxy and methoxyestrogens, in PD patients' blood, whereas the stopped-flow method was used to assess hydrogen peroxide (H2O2) levels. Methoxyestrogens and H2O2 levels were increased in patients' blood as compared to control subjects, but hydoxyestrogens were simultaneously decreased. From the above, we suggest that the determination of plasma levels of methoxyestrogens and H2O2 may be a novel PD biomarker. The presented research is the subject of the pending patent application "The use of hydrogen peroxide and 17β-estradiol and its metabolites as biomarkers in the diagnosis of neurodegenerative diseases," no. P.441360.

Induction of 2-hydroxycatecholestrogens O-methylation: A missing puzzle piece in diagnostics and treatment of lung cancer

Lung cancer is one of the most common cancers worldwide, causing nearly one million deaths each year. Herein, we present the effect of 2-methoxyestradiol (2-ME), the endogenous metabolite of 17β-estradiol (E2), on non-small cell lung cancer (NSCLC) cells. We observed that 2-ME reduced the viability of lung adenocarcinoma in two-dimensional (2D) and three-dimensional (3D) spheroidal A549 cell culture models. Molecular modeling was carried out aiming to visualize amino acid residues within binding pockets of the acyl-protein thioesterases, namely 1 (APT1) and 2 (APT2), and thus to identify which ones were more likely involved in the interaction with 2-ME. Our findings suggest that 2-ME acts as an APT1 inhibitor enhancing protein palmitoylation and oxidative stress phenomena in the lung cancer cell. In order to support our data, metabolomics of blood serum from NSCLC patients was also performed. Moreover, computational analysis suggests that 2-ME as compared to other estrogen metabolism intermediates is relatively safe in terms of its possible non-receptor bioactivity within healthy human cells due to a very low electrophilic potential and hence no substantial risk of spontaneous covalent modification of biologically protective nucleophiles. We propose that 2-ME can be used as a selective tumor biomarker in the course of certain types of lung cancers and possibly as a therapeutic adjuvant or neoadjuvant.

Low prevalence of active COVID-19 in Slovenia: a nationwide population study of a probability-based sample

Objectives

Accurate population-level assessment of the coronavirus disease 2019 (COVID-19) burden is fundamental for navigating the path forward during the ongoing pandemic, but current knowledge is scant. We conducted the first nationwide population study using a probability-based sample to assess active severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, combined with a longitudinal follow-up of the entire cohort over the next 6 months. Baseline SARS-CoV-2 RNA testing results and the first 3-week follow-up results are presented.

Methods

A probability-based sample of the Slovenian population comprising data from 2.1 million people was selected from the Central Population Register (n = 3000). SARS-CoV-2 RNA was detected in nasopharyngeal samples using the cobas 6800 SARS-CoV-2 assay. Each participant filled in a detailed baseline questionnaire with basic sociodemographic data and detailed medical history compatible with COVID-19. After 3 weeks, participants were interviewed for the presence of COVID-19–compatible clinical symptoms and signs, including in household members, and offered immediate testing for SARS-CoV-2 RNA if indicated.

Results

A total of 1368 individuals (46%) consented to participate and completed the questionnaire. Two of 1366 participants tested positive for SARS-CoV-2 RNA (prevalence 0.15%; posterior mean 0.18%, 95% Bayesian confidence interval 0.03–0.47; 95% highest density region (HDR) 0.01–0.41). No newly diagnosed infections occurred in the cohort during the first 3-week follow-up round.

Conclusions

The low prevalence of active COVID-19 infections found in this study accurately predicted the dynamics of the epidemic in Slovenia over the subsequent month. Properly designed and timely executed studies using probability-based samples combined with routine target-testing figures provide reliable data that can be used to make informed decisions on relaxing or strengthening disease mitigation strategies.

Modification of DNA structure by reactive nitrogen species as a result of 2-methoxyestradiol-induced neuronal nitric oxide synthase uncoupling in metastatic osteosarcoma cells

2-methoxyestradiol (2-ME) is a physiological anticancer compound, metabolite of 17β-estradiol. Previously, our group evidenced that from mechanistic point of view one of anticancer mechanisms of action of 2-ME is specific induction and nuclear hijacking of neuronal nitric oxide synthase (nNOS), resulting in local generation of nitro-oxidative stress and finally, cancer cell death.

The current study aims to establish the substantial mechanism of generation of reactive nitrogen species by 2-ME. We further achieved to identify the specific reactive nitrogen species involved in DNA-damaging mechanism of 2-ME.

The study was performed using metastatic osteosarcoma 143B cells. We detected the release of biologically active (free) nitric oxide (^•NO) with concurrent measurements of peroxynitrite (ONOO⁻) in real time in a single cell of 143B cell line by using ^•NO/ONOO⁻ sensitive microsensors after stimulation with calcium ionophore. Detection of nitrogen dioxide (^•NO₂) and determination of chemical rate constants were carried out by a stopped-flow technique. The affinity of reactive nitrogen species toward the guanine base of DNA was evaluated by density functional theory calculations. Expression and localization of nuclear factor NF-kB was determined using imaging cytometry, while cell viability assay was evaluated by MTT assay.

Herein, we presented that 2-ME triggers pro-apoptotic signalling cascade by increasing cellular reactive nitrogen species overproduction – a result of enzymatic uncoupling of increased nNOS protein levels. In particular, we proved that ONOO⁻ and ^•NO₂ directly formed from peroxynitrous acid (ONOOH) and/or by auto-oxidation of ^•NO, are inducers of DNA damage in anticancer mechanism of 2-ME. Specifically, the affinity of reactive nitrogen species toward the guanine base of DNA, evaluated by density functional theory calculations, decreased in the order: ONOOH > ONOO⁻ > ^•NO₂ > ^•NO.

Therefore, we propose to consider the specific inducers of nNOS as an effective tool in the field of chemotherapy.

hmSOD1 gene mutation-induced disturbance in iron metabolism is mediated by impairment of Akt signalling pathway

BACKGROUND

Recently, skeletal muscle atrophy, impairment of iron metabolism, and insulin signalling have been reported in rats suffering from amyotrophic lateral sclerosis (ALS). However, the interrelationship between these changes has not been studied. We hypothesize that an impaired Akt-FOXO3a signalling pathway triggers changes in the iron metabolism in the muscles of transgenic animals.

METHODS

In the present study, we used transgenic rats bearing the G93A hmSOD1 gene and their non-transgenic littermates. The study was performed on the muscles taken from animals at three different stages of the disease: asymptomatic (ALS I), the onset of the disease (ALS II), and the terminal stage of the disease (ALS III). In order to study the molecular mechanism of changes in iron metabolism, we used SH-SY5Y and C2C12 cell lines stably transfected with pcDNA3.1, SOD1 WT and SOD1 G93A, or FOXO3a TM-ER.

RESULTS

A significant decrease in P-Akt level and changes in iron metabolism were observed even in the group of ALS I animals. This was accompanied by an increase in the active form of FOXO3a, up-regulation of atrogin-1, and catalase. However, significant muscle atrophy was observed in ALS II animals. An increase in ferritin L and H was accompanied by a rise in PCBP1 and APP protein levels. In SH-SY5Y cells stably expressing SOD1 or SOD1 G93A, we observed elevated levels of ferritin L and H and non-haem iron. Interestingly, insulin treatment significantly down-regulated ferritin L and H proteins in the cell. Conversely, cells transfected with small interfering RNA against Akt 1, 2, 3, respectively, showed a significant increase in the ferritin and FOXO3a levels. In order to assess the role of FOXO3a in the ferritin expression, we constructed a line of SH-SY5Y cells that expressed a fusion protein made of FOXO3a fused at the C-terminus with the ligand-binding domain of the oestrogen receptor (TM-ER) being activated by 4-hydroxytamoxifen. Treatment of the cells with 4-hydroxytamoxifen significantly up-regulated ferritin L and H proteins level.

CONCLUSIONS

Our data suggest that impairment of insulin signalling and iron metabolism in the skeletal muscle precedes muscle atrophy and is mediated by changes in Akt/FOXO3a signalling pathways.

Potential Health Benefits of Olive Oil and Plant Polyphenols

Beneficial effects of natural plant polyphenols on the human body have been evaluated in a number of scientific research projects. Bioactive polyphenols are natural compounds of various chemical structures. Their sources are mostly fruits, vegetables, nuts and seeds, roots, bark, leaves of different plants, herbs, whole grain products, processed foods (dark chocolate), as well as tea, coffee, and red wine. Polyphenols are believed to reduce morbidity and/or slow down the development of cardiovascular and neurodegenerative diseases as well as cancer. Biological activity of polyphenols is strongly related to their antioxidant properties. They tend to reduce the pool of reactive oxygen species as well as to neutralize potentially carcinogenic metabolites. A broad spectrum of health-promoting properties of plant polyphenols comprises antioxidant, anti-inflammatory, anti-allergic, anti-atherogenic, anti-thrombotic, and anti-mutagenic effects. Scientific studies present the ability of polyphenols to modulate the human immune system by affecting the proliferation of white blood cells, and also the production of cytokines or other factors that participate in the immunological defense. The aim of the review is to focus on polyphenols of olive oil in context of their biological activities.

Capping Agent-Dependent Toxicity and Antimicrobial Activity of Silver Nanoparticles: An In Vitro Study. Concerns about Potential Application in Dental Practice

Objectives: In dentistry, silver nanoparticles (AgNPs) have drawn particular attention because of their wide antimicrobial activity spectrum. However, controversial information on AgNPs toxicity limited their use in oral infections. Therefore, the aim of the present study was to evaluate the antibacterial activities against a panel of oral pathogenic bacteria and bacterial biofilms together with potential cytotoxic effects on human gingival fibroblasts of 10 nm AgNPs: non-functionalized - uncapped (AgNPs-UC) as well as surface-functionalized with capping agent: lipoic acid (AgNPs-LA), polyethylene glycol (AgNPs-PEG) or tannic acid (AgNPs-TA) using silver nitrate (AgNO3) as control. Methods: The interaction of AgNPs with human gingival fibroblast cells (HGF-1) was evaluated using the mitochondrial metabolic potential assay (MTT). Antimicrobial activity of AgNPs was tested against anaerobic Gram-positive and Gram-negative bacteria isolated from patients with oral cavity and respiratory tract infections, and selected aerobic Staphylococci strains. Minimal inhibitory concentration (MIC) values were determined by the agar dilution method for anaerobic bacteria or broth microdilution method for reference Staphylococci strains and Streptococcus mutans. These strains were also used for antibiofilm activity of AgNPs. Results: The highest antimicrobial activities at nontoxic concentrations were observed for the uncapped AgNPs and the AgNPs capped with LA. It was found that AgNPs-LA and AgNPs-PEG demonstrated lower cytotoxicity as compared with the AgNPs-TA or AgNPs-UC in the gingival fibroblast model. All of the tested nanoparticles proved less toxic and demonstrated wider spectrum of antimicrobial activities than AgNO3 solution. Additionally, AgNPs-LA eradicated Staphylococcus epidermidis and Streptococcus mutans 1-day biofilm at concentration nontoxic to oral cells. Conclusions: Our results proved that a capping agent had significant influence on the antibacterial, antibiofilm activity and cytotoxicity of AgNPs. Clinical significance: This study highlighted potential usefulness of AgNPs against oral anaerobic Gram-positive and Gram-negative bacterial infections and aerobic Staphylococci strains provided that pharmacological activity and risk assessment are carefully performed.

A Proposed Molecular Mechanism of High-Dose Vitamin D3 Supplementation in Prevention and Treatment of Preeclampsia

A randomized prospective clinical study performed on a group of 74 pregnant women (43 presenting with severe preeclampsia) proved that urinary levels of 15-F(2t)-isoprostane were significantly higher in preeclamptic patients relative to the control (3.05 vs. 2.00 ng/mg creatinine). Surprisingly enough, plasma levels of 25-hydroxyvitamin D3 in both study groups were below the clinical reference range with no significant difference between the groups. In vitro study performed on isolated placental mitochondria and placental cell line showed that suicidal self-oxidation of cytochrome P450scc may lead to structural disintegration of heme, potentially contributing to enhancement of oxidative stress phenomena in the course of preeclampsia. As placental cytochrome P450scc pleiotropic activity is implicated in the metabolism of free radical mediated arachidonic acid derivatives as well as multiple Vitamin D3 hydroxylations and progesterone synthesis, we propose that Vitamin D3 might act as a competitive inhibitor of placental cytochrome P450scc preventing the production of lipid peroxides or excess progesterone synthesis, both of which may contribute to the etiopathogenesis of preeclampsia. The proposed molecular mechanism is in accord with the preliminary clinical observations on the surprisingly high efficacy of high-dose Vitamin D3 supplementation in prevention and treatment of preeclampsia.

Aliskiren attenuates oxidative stress and improves tubular status in non-diabetic patients with chronic kidney disease-Placebo controlled, randomized, cross-over study

PURPOSE

Pharmacological inhibition of the renin-angiotensin-aldosteron system (RAAS) may have a beneficial impact on proteinuria and chronic kidney diseases (CKD) progression. Despite recent progress by means of angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), there is still no optimal therapy which can stop progression of the nephropathy. Recently introduced aliskiren is the first orally bioavailable direct renin inhibitor approved for the treatment of hypertension. The purpose was to evaluate the extent of oxidative stress and tubular injury after the direct renin inhibitor, aliskiren compared with placebo and perindopril in patients with non-diabetic chronic kidney disease (NDCKD).

MATERIAL/METHODS

A randomized, double-blind, cross-over trial was performed in 14 patients receiving 300mg aliskiren, 10mg perindopril and placebo in random order. The end point was a change in the urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) and α1-microglobulin (α1m) and 15-F(2α)-isoprostane.

RESULTS

Aliskiren reduced excretion of 15-F(2α)-isoprostane (p=0.03) and α1m (p=0.01) as compared to placebo. There were no differences between aliskiren and perindopril in this regard. NAG urine excretion did not change after aliskiren and perindopril.

CONCLUSIONS

Aliskiren attenuates oxidative stress and may improve functional status of tubules in patients with NDCKD.

Diallyl trisulfide is more cytotoxic to prostate cancer cells PC-3 than to noncancerous epithelial cell line PNT1A: a possible role of p66Shc signaling axis

Diallyl trisulfide (DATS) is an organosulfur compound isolated from garlic, and has been shown to have anticancer activity both in vitro and in vivo. The aim of this study was to compare cytotoxic effects of DATS on prostate cancer cells PC-3 and noncancerous human prostate epithelial cells PNT1A. PC-3 prostate cancer and noncancerous human prostate epithelial cells PNT1A were used in the study. We observed that PNT1A cells had higher resistance to DATS-induced cell death than PC-3 cells. Investigating signaling pathways involved in the cell death we observed that p66Shc phosphorylation at serine 36 and extracellular signal-regulated kinase 1/2 activation induced by DATS, were significantly attenuated in PNT1A cells as compared to PC-3 cells. Moreover, DATS-induced Akt inactivation was also significantly reduced in PNT1A cells. In addition to that, DATS-induced reactive oxygen species generation was nearly completely abolished in PNT1A cells. Interestingly, DATS induced only slight decrease in the level of ferritin H, whereas ferritin L was elevated. These data suggest that cytotoxicity of DATS toward PNT1A cells is strongly reduced as opposed to PC-3 cancer cells, which corresponds to the lower activation of prodeath signaling pathway mediated by the adaptor protein p66Shc in the noncancerous PNT1A cells.

Geldanamycin-induced osteosarcoma cell death is associated with hyperacetylation and loss of mitochondrial pool of heat shock protein 60 (hsp60)

Osteosarcoma is one of the most malignant tumors of childhood and adolescence that is often resistant to standard chemo- and radio-therapy. Geldanamycin and geldanamycin analogs have been recently studied as potential anticancer agents for osteosarcoma treatment. Here, for the first time, we have presented novel anticancer mechanisms of geldanamycin biological activity. Moreover, we demonstrated an association between the effects of geldanamycin on the major heat shock proteins (HSPs) and the overall survival of highly metastatic human osteosarcoma 143B cells. We demonstrated that the treatment of 143B cells with geldanamycin caused a subsequent upregulation of cytoplasmic Hsp90 and Hsp70 whose activity is at least partly responsible for cancer development and drug resistance. On the other hand, geldanamycin induced upregulation of Hsp60 gene expression, and a simultaneous loss of hyperacetylated Hsp60 mitochondrial protein pool resulting in decreased viability and augmented cancer cell death. Hyperacetylation of Hsp60 seems to be associated with anticancer activity of geldanamycin. In light of the fact that mitochondrial dysfunction plays a critical role in the apoptotic signaling pathway, the presented data may support a hypothesis that Hsp60 can be another functional part of mitochondria-related acetylome being a potential target for developing novel anticancer strategies.

[Isoprostanes - important marker of the oxidative stress estimation in patients with chronic kidney disease]

The discovery of isoprostanes, which are products of non-enzymatic lipid peroxidation, resulted in the research on the new role of free radicals in physiology and pathophysiology. Isoprostane quantitative analysis is a great achievement in the evaluation of free radical impact on many diseases in human. Isoprostanes were also found to be elevated in end-stage renal disease, another condition associated with increased oxidative stress. The aim of the study was to evaluate the influence of nephroprotective treatments on the urinary excretion of 15-F2alpha-isoprostane in the treated patients with Chronic Kidney Disease (CKD).

MATERIAL AND METHODS

84 patients (32 females and 52 males); age 18-65 years (average 39.06 +/- 4.92), with chronic non-diabetic proteinuric nephropathy, normal or slightly impaired stable renal function expressed as estimated creatinine cleamace above 30 mi/min, were selected from the cohort that attended our renal outpatients department. Clinical evaluation and laboratory tests were performed at the randomization point and after each period of the study A commercial ELISA Kit (Cayman Chemical Co) was used to measure the urinary excretion of 15-F2alpha-isoprostane in the treated patients.

RESULTS

It was found that the blockade of renin-angiotensin-aldosteron system (with aliskiren, cilazapril, perindopril, spironolakton) and the treatment with atorwastatin significantly reduced urinary levels of 15-F2alpha-isoprostane relatively to the control group. It was not observed for pentoxyfilline treatment.

CONCLUSIONS

Urine levels of isoprostanes are significantly decreased in patients with Chronic Kidney Disease during nephroprotective treatments.

Activation of hydrogen peroxide to peroxytetradecanoic acid is responsible for potent inhibition of protein tyrosine phosphatase CD45

Hydrogen peroxide induces oxidation and consequently inactivation of many protein tyrosine phosphatases. It was found that hydrogen peroxide, in the presence of carboxylic acids, was efficiently activated to form even more potent oxidant - peroxy acid. We have found that peroxytetradecanoic acid decreases the enzymatic activity of CD45 phosphatase significantly more than hydrogen peroxide. Our molecular docking computational analysis suggests that peroxytetradecanoic acid has a higher binding affinity to the catalytic center of CD45 than hydrogen peroxide.

Geldanamycin and its derivatives as Hsp90 inhibitors

The Hsp90 molecule, one of the most abundant heat shock proteins in mammalian cells, maintains homeostasis and prevents stress-induced cellular damage. Hsp90 is expressed under normal conditions at a level of about 1-2 Percent of total proteins, while its expression increases 2-10 fold in cancer cells. The two main constitutively expressed isoforms of Hsp90 are known as Hsp90-alpha and Hsp90-beta, and their upregulation is associated with tumor progression, invasion and formation of metastases, as well as development of drug resistance. The Hsp90 is a key target for many newly established, potent anticancer agents containing Hsp90 N-terminal ATP binding inhibitors, such as geldanamycin, and its analogues 17AAG and 17DMAG. The therapeutic usage of geldanamycin has been limited due to its poor water solubility and severe hepatotoxicity. Therefore, its analogues, including 17AAG, 17DMAG, Tanespimycin and Retaspimycin hydrochloride, with improved pharmacokinetic profiles, have been developed.

Neuroprotective effects of tempol acyl esters against retinal ganglion cell death in a rat partial optic nerve crush model

PURPOSE

The aim of this study is to search for more effective derivatives of the superoxide dismutase mimetic tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl). Although tempol is neuroprotective in a rat partial optic nerve crush (PONC) model, relatively high doses are required to exert this effect.

METHODS

Tempol acyl esters with different-length fatty acids (tempol-C4, tempol-C8, tempol-C12 and tempol-C16) were synthesized and the following properties were evaluated: water-octanol partition coefficient, liposome-liposome energy transfer, and electron paramagnetic resonance (EPR). Brown Norway rats underwent PONC and received tempol or acyl esters intraperitoneally once daily for 7 consecutive days. We then compared the effects of tempol and its four esters on retinal ganglion cell (RGC) damage using a retrograde labelling method.

RESULTS

The water-octanol partition coefficient increased with increasing length of attached acyl chain. However, the energy of the liposome-liposome transfer seemed to be optimal for tempol-C8 and tempol-C12. The EPR signal was very similar for all tested compounds, suggesting similar efficiency of superoxide scavenging. Partial optic nerve crush in vehicle-treated animals reduced RGC numbers by approx. 59% when compared with sham-operated eyes. Tempol did not affect RGC loss at a dose of 1 mg/kg. In contrast, at molar doses equivalent to 1 mg/kg of tempol, tempol-C8 showed a significant neuroprotective effect, whereas tempol-C4, tempol-C12 and tempol-C16 did not act neuroprotectively.

CONCLUSION

Manipulating the hydrophobicity of tempol seems to be a promising tool for developing more potent neuroprotectants in the PONC degeneration model. However, the resulting compounds need further pharmacological evaluation.

Protein tyrosine phosphatase CD45 as a molecular biosensor of hydrogen peroxide generation in cell culture media

We have designed a useful method of assessing reactive oxygen species generation in biological fluids. The novel assay utilizes tyrosine phosphatase CD45 as a biosensor of oxidative stress. Applying this new method, we examined oxygen species generation in the following cell culture media: RPMI 1640, DMEM, DMEM enriched with pyruvate and MEM. We discovered that the media (especially RPMI 1640) significantly reduced the activity of protein tyrosine phosphatase. The media-caused inactivation of CD45 was reversible after treatment with dithiothreitol being a powerful reducing agent. Interestingly, the media supplemented with catalase did not exhibit any inhibitory effect on CD45 activity which suggests a hydrogen peroxide-mediated mechanism of the enzyme inactivation. In addition to that, we assessed the impact of oxidative stress level on the activity of CD45 as measured in Jurkat cells cultured in RPMI 1640 either exposed or not exposed to the light of laminar flow cabinet fluorescent lamp. We found that Jurkat cells that were exposed to light displayed ca. 20% lower activity of CD45 than the cells protected against the light. The obtained results indicate that production of hydrogen peroxide in the medium leading to inhibition of CD45 was light-dependent, and that careful protection of cell culture media from the light may help to prevent the artifact in cell studies. Hydrogen peroxide, responsible for CD45 inactivation, can be generated in cell culture media after exposition to light due to photoreactive amino acids present in the media.

Methyl-beta-cyclodextrin induces mitochondrial cholesterol depletion and alters the mitochondrial structure and bioenergetics

There is growing evidence of mitochondrial membrane raft-like microdomains that are involved in the apoptotic pathway. The aim of this study was to investigate the effect of methyl-beta-cyclodextrin (MβCD), being a well-known lipid microdomain disrupting agent and cholesterol chelator, on the structure and bioenergetics of rat liver mitochondria (RLM). We observed that MβCD decreases the function of RLM, induces changes in the mitochondrial configuration state and decreases the calcium chloride-induced swelling. These data suggest that disruption of mitochondrial raft-like microdomains by cholesterol efflux on one hand impairs mitochondrial bioenergetics, but on the other hand it protects the mitochondria from swelling.

Effect of pentoxifylline on proteinuria, markers of tubular injury and oxidative stress in non-diabetic patients with chronic kidney disease - placebo controlled, randomized, cross-over study

Inhibition of the renin-angiotensin-aldosterone system (RAAS) with angiotensin converting enzyme inhibitors (ACEI) and/or angiotensin II subtype 1 receptor antagonists (ARB) is a common strategy used in the management of patients with chronic kidney disease (CKD). However, there is no universal therapy that can stop progression of CKD. Pentoxifylline (PTE) is a non-specific phosphodiesterase inhibitor with anti-inflammatory properties. It has been reported to have promising effects in CKD treatment. In a placebo-controlled, randomized, cross-over study we evaluated the influence of PTE (1200 mg/day) added to RAAS blockade on proteinuria, surrogate markers of tubular injury and oxidative stress-dependent products in 22 non-diabetic patients with proteinuria (0.4-4.3 g per 24 h) with normal or declined kidney function [eGFR 37-178 mL/min]. In an eight-week run-in period, therapy using ACEI and/or ARB was adjusted to achieve a blood pressure below 130/80 mm Hg. Next, patients were randomly assigned to one of two treatment sequences: PTE/washout/placebo or placebo/washout/PTE. Clinical evaluation and laboratory tests were performed at the randomization point and after each period of the study. The PTE therapy reduced proteinuria (by 26%) as compared to placebo. There were no differences in alpha(1)-microglobulin, urine excretion of N-acetyl-beta-d-glucosaminidase (NAG), hsCRP, the urinary excretion of 15-F(2)t-isoprostane, blood pressure (BP), eGFR and serum creatinine between the PTE and placebo groups. Pentoxifylline may decrease proteinuria in non-diabetic patients with CKD.

Effect of pentoxifylline on proteinuria, markers of tubular injury and oxidative stress in non-diabetic patients with chronic kidney disease - placebo controlled, randomized, cross-over study

BACKGROUND

Inhibition of the renin-angiotensin-aldosterone system (RAAS) with angiotensin converting enzyme inhibitors (ACEI) and/or angiotensin II subtype 1 receptor antagonists (ARB) is a common strategy used in the management of patients with chronic kidney disease (CKD). However, there is no universal therapy that can stop progression of CKD. Pentoxifylline (PTE) is a non-specific phosphodiesterase inhibitor with anti-inflammatory properties. It has been reported to have promising effects in CKD treatment.

METHODS

In a placebo-controlled, randomized, cross-over study we evaluated the influence of PTE (1200 mg/day) added to RAAS blockade on proteinuria, surrogate markers of tubular injury and oxidative stress-dependent products in 22 non-diabetic patients with proteinuria (0.4-4.3 g per 24 h) with normal or declined kidney function [eGFR 37-178 mL/min]. In an eight-week run-in period, therapy using ACEI and/or ARB was adjusted to achieve a blood pressure below 130/80 mm Hg. Next, patients were randomly assigned to one of two treatment sequences: PTE/washout/placebo or placebo/washout/PTE. Clinical evaluation and laboratory tests were performed at the randomization point and after each period of the study.

RESULTS

The PTE therapy reduced proteinuria (by 26%) as compared to placebo. There were no differences in alpha(1)-microglobulin, urine excretion of N-acetyl-beta-d-glucosaminidase (NAG), hsCRP, the urinary excretion of 15-F(2)t-isoprostane, blood pressure (BP), eGFR and serum creatinine between the PTE and placebo groups.

CONCLUSION

Pentoxifylline may decrease proteinuria in non-diabetic patients with CKD.

[Protein tyrosine phosphatases--endogenous markers of oxidative stress]

The reversible phosphorylation of structural and regulatory proteins in eucaryotic cells is one of the most important regulatory mechanisms. Protein tyrosine phosphatases (PTP) regulate a wide range of signal transduction pathways that control many cellular processes such as cell proliferation, differentiation and growth. Disorder in PTP gene expression is implicated in the development of cancer, autoimmune and neurodegenerative diseases. The active sites of these enzymes are characterized by the consensus sequence containing cysteine which is essential for enzyme activity and highly susceptible to oxidation. Reversible oxidation of the catalytic cysteine is becoming recognized as a general mechanism for regulation of PTP enzymatic activity. These findings suggest that protein tyrosine phosphatases may be considered as very sensitive markers of oxidative stress. Many studies have demonstrated that the production of reactive oxygen species during oxidative stress can inactivate protein tyrosine phosphatases.

A novel biosensor for evaluation of apoptotic or necrotic effects of nitrogen dioxide during acute pancreatitis in rat

The direct and accurate estimation of nitric dioxide levels is an extremely laborious and technically demanding procedure in the molecular diagnostics of inflammatory processes. The aim of this work is to demonstrate that a stop-flow technique utilizing a specific spectroscopic biosensor can be used for detection of nanomolar quantities of NO(2) in biological milieu. The use of novel compound cis-[Cr(C(2)O(4))(AaraNH(2))(OH(2))(2)](+) increases NO(2) estimation accuracy by slowing down the rate of NO(2) uptake. In this study, an animal model of pancreatitis, where nitrosative stress is induced by either 3g/kg bw or 1.5 g/kg bw dose of L-arginine, was used. Biochemical parameters and morphological characteristics of acute pancreatitis were monitored, specifically assessing pancreatic acinar cell death mode, NO(2) generation and cellular glutathione level. The severity of the process correlated positively with NO(2) levels in pancreatic acinar cell cytosol samples, and negatively with cellular glutathione levels.

Ultrastructural response of arcuate nucleus neurons to fasting in aged rats

The arcuate nucleus of the hypothalamus (ARH) is involved in the control of energy homeostasis. Leptin - an adipocyte derived hormone - is known to act on the hypothalamic nuclei and thus to control body weight by food intake reduction. Oxidative stress is believed to be implicated in leptin signalling. However, its relevance for leptin-induced signal transduction within ARH remains unclear. The goal of the study was to investigate the effect of fasting on morphological alterations of the neuronal endoplasmic reticulum/Golgi network as well as on the expression of leptin receptors in the arcuate nucleus of aged rats. Male Wistar rats, aged 24 months, were fasted for 96 hours. The control animals were fed ad libitum. Membranous whorls in the ARH neurons were visualized using the electron microscopy technique. Leptin receptors in the membranes of ARH neurons were determined immunohistochemically (IHC), and soluble leptin receptors in the plasma as well as plasma isoprostanes were quantified immunochemically (ELISA). An intense formation of membranous whorls was observed, directly associated with the cisternae of the rough endoplasmic reticulum, as well as lamellar bodies. Interestingly, the whorls were often localized near a well-developed Golgi complex. Moreover, some Golgi complexes displayed an early stage of whorl formation. Groups of residual lipofuscin granules were found in the immediate proximity of the whorls. An increased immunoreactivity with neuronal leptin receptors suggests that hypersensitive neurons may still effectively respond to the fasting serum levels of leptin, mediating ultrastructural transformation of ARH neurons during short-term fasting. Having observed a significant accumulation of lipofuscin granules and a marked increase of total 8-isoprostane serum level in the fasting rats, we hypothesize that signal transduction within the neurons of ARH is dependent on oxidative stress phenomena.

The effect of fasting on the ultrastructure of the hypothalamic arcuate nucleus in young rats

In the present study, we described ultrastructural changes occurring in the neurons of the hypothalamic arcuate nucleus after food deprivation. Young male Wistar rats (5 months old, n = 12) were divided into three groups. The animals in Group I were used as control (normally fed), and the rats in Groups II and III were fasted for 48 hours and 96 hours, respectively. In both treated groups, fasting caused rearrangement of the rough endoplasmic reticulum forming lamellar bodies and membranous whorls. The lamellar bodies were rather short in the controls, whereas in the fasting animals they became longer and were sometimes participating in the formation of membranous whorls composed of the concentric layers of the smooth endoplasmic reticulum. The whorls were often placed in the vicinity of a very well developed Golgi complex. Some Golgi complexes displayed an early stage of whorl formation. Moreover, an increased serum level of 8-isoprostanes, being a reliable marker of total oxidative stress in the body, was observed in both fasting groups of rats as compared to the control.

Ultrastructural observations on the hypothalamic arcuate nuclei of aged rats in the fasting/refeeding model

The arcuate nucleus of the hypothalamus (ARH) is involved in the control of energy homeostasis. This is the first study on the ultrastructural response of ARH neurons in aged rats after short-term fasting and subsequent refeeding. Male Wistar rats (24 weeks old) were fasted for 48 or 96 hours and were then refed for 24 hours. The controls were normally fed. The rats received water ad libitum. In both groups of fasting animals, we observed a rearrangement of the arcuate rough endoplasmic reticulum (RER) and Golgi complexes to form membranous whorls. Moreover, refeeding for 24 hours did not reverse this process. The RER was frequently found to be well organized into lamellar bodies composed of several cisternae. The membranous whorls were composed of concentric layers of endoplasmic reticulum and Golgi complexes. In addition, multiform lipofuscin granules were observed in close relationship with Golgi complexes and membranous whorls. Lipofuscin granules within the neurons of the arcuate nucleus are assumed to be a morphological manifestation of oxidative stress phenomena, which are presumably implicated in the formation of membranous whorls in both fasting and fasting/refed animals. This observation correlates with a significant increase in 8-isoprostane serum levels in the fasting and fasting/refed animals as compared to the fed control rats.

Dynamics of oxidative damage at early stages of estrogen-dependant carcinogenesis

The objective of this study was to assess the dynamics of oxidative damage to cellular macromolecules such as proteins, lipids, and DNA under conditions of oxidative stress triggering early stages of estrogen-dependent carcinogenesis. A rodent model of carcinogenesis was used. Syrian hamsters were sacrificed after 1, 3, 5 h and 1 month from the initial implantation of 17beta-estradiol (E2). Matching control groups were used. Kidneys as target organs for E2-mediated oxidative stress were excised and homogenized for biochemical assays. Subcellular fractions were isolated. Carbonyl groups (as a marker of protein oxidation) and lipid hydroxyperoxides were assessed. DNA was isolated and 8-oxodGuo was assessed. Electron paramagnetic resonance spectroscopy was used to confirm the results for lipid peroxidation. Exposition to E2 in rodent model leads to a damage of macromolecules of the cell, including proteins and DNA, but not lipids. Proteins appear to be primary target of the damage but are shortly followed by DNA. It has previously been speculated that protein peroxides can increase DNA modifications. This time sequence was observed in our study. Nevertheless, direct relation between protein and DNA damage still remains unsolved.

Dynamics of estrogen-induced oxidative stress

The objective of this study was to assess the dynamics of oxidative damage to cellular macromolecules such as proteins, lipids and DNA under conditions of oxidative stress triggering early stages of estrogen-dependent carcinogenesis. A rodent model of carcinogenesis was used. Syrian hamsters were sacrificed after 1, 3, 5 h and one month from the initial implantation of estradiol. Matching control groups were used. Kidneys as target organs for estradiol-mediated oxidative stress were excised and homogenized for biochemical assays. Subcellular fractions were isolated. Carbonyl groups (as a marker of protein oxidation) and lipid hydroxyperoxides were assessed. DNA was isolated and 8-oxodGuo was assessed. Electron paramagnetic resonance spectroscopy was used to confirm the results for lipid peroxidation. Exposition to estradiol in the rodent model leads to damage of macromolecules of the cell, including proteins and DNA, but not lipids. Proteins appear to be the primary target of the damage but are closely followed by DNA. It has previously been speculated that protein peroxides can increase DNA modifications. This time sequence was observed in our study. Nevertheless, the direct relation between protein and DNA damage still remains unsolved.

Dynamics of estrogen-induced oxidative stress

The objective of this study was to assess the dynamics of oxidative damage to cellular macromolecules such as proteins, lipids and DNA under conditions of oxidative stress triggering early stages of estrogen-dependent carcinogenesis. A rodent model of carcinogenesis was used. Syrian hamsters were sacrificed after 1, 3, 5 h and one month from the initial implantation of estradiol. Matching control groups were used. Kidneys as target organs for estradiol-mediated oxidative stress were excised and homogenized for biochemical assays. Subcellular fractions were isolated. Carbonyl groups (as a marker of protein oxidation) and lipid hydroxyperoxides were assessed. DNA was isolated and 8-oxodGuo was assessed. Electron paramagnetic resonance spectroscopy was used to confirm the results for lipid peroxidation. Exposition to estradiol in the rodent model leads to damage of macromolecules of the cell, including proteins and DNA, but not lipids. Proteins appear to be the primary target of the damage but are closely followed by DNA. It has previously been speculated that protein peroxides can increase DNA modifications. This time sequence was observed in our study. Nevertheless, the direct relation between protein and DNA damage still remains unsolved.

Persistence of protein oxidation products and plasma antioxidants in juvenile idiopathic arthritis. A one-year follow-up study

OBJECTIVE

Plasma protein oxidation products and blood antioxidants, like superoxide dismutase (SOD), glutathione peroxidase (GPx) and total antioxidant status (TAS) were investigated in children with juvenile idiopathic arthritis (JIA) in a year follow-up study.

METHODS

Carbonyl group content within plasma proteins, activity of red blood cell SOD and GPx, as well as the blood TAS level were determined in 14 children with JIA twice, namely at the admission to the hospital (Time 0 = T0) and then after a year of treatment (Time 1 = T1).

RESULTS

An increased level of plasma protein carbonyls was observed in both assessments (T0 and T1) as compared to control. However there was no significant difference in plasma carbonyls level between the initial (T0) and final (T1) examination of the patients. Similarly, SOD activity was higher in children with JIA as compared to control subjects and did not change significantly after a year of follow-up. Red blood cell GPx activity remained within the normal range throughout the study. Interestingly, the blood TAS level was initially comparable to control and rose significantly after the year of treatment.

CONCLUSION

A level of plasma protein oxidation products remains significantly higher in children with JIA as compared to healthy subjects. The lack of accumulation of plasma protein carbonyls may result from efficient proteolysis in childhood and/or adaptive increase of the blood TAS level in the course of effective anti-inflammatory therapy. Analysis of plasma oxidative stress markers and antioxidant potential of the blood might be helpful in monitoring the clinical treatment of children suffering from JIA.

Dual effect of 2-methoxyestradiol on cell cycle events in human osteosarcoma 143B cells

We have demonstrated for the first time that the steroid metabolite, 2-methoxyestradiol (2-ME) is a powerful growth inhibitor of human osteosarcoma 143 B cell line by pleiotropic mechanisms involving cell cycle arrest at two different points and apoptosis. The ability of 2-ME to inhibit cell cycle at the respective points has been found concentration dependent. 1 microM 2-ME inhibited cell cycle at G1 phase while 10 microM 2-ME caused G2/M cell cycle arrest. As a natural estrogen metabolite 2-ME is expected to perturb the stability of microtubules (MT) in vivo analogously to Taxol--the MT binding anticancer agent. Contrary to 2-ME, Taxol induced accumulation of osteosarcoma cells in G2/M phase of cell cycle only. The presented data strongly suggest two different mechanisms of cytotoxic action of 2-ME at the level of a single cell.

Dual effect of 2-methoxyestradiol on cell cycle events in human osteosarcoma 143B cells

We have demonstrated for the first time that the steroid metabolite, 2-methoxyestradiol (2-ME) is a powerful growth inhibitor of human osteosarcoma 143 B cell line by pleiotropic mechanisms involving cell cycle arrest at two different points and apoptosis. The ability of 2-ME to inhibit cell cycle at the respective points has been found concentration dependent. 1 microM 2-ME inhibited cell cycle at G1 phase while 10 microM 2-ME caused G2/M cell cycle arrest. As a natural estrogen metabolite 2-ME is expected to perturb the stability of microtubules (MT) in vivo analogously to Taxol--the MT binding anticancer agent. Contrary to 2-ME, Taxol induced accumulation of osteosarcoma cells in G2/M phase of cell cycle only. The presented data strongly suggest two different mechanisms of cytotoxic action of 2-ME at the level of a single cell.

Determination of adenine nucleotides and their metabolites in human saliva

The profile and normal concentrations of nucleotide metabolites in human saliva and reproducibility of these determinations were analyzed. Samples of human saliva collected from healthy individuals at weekly intervals, were deproteinized and analysed for the content of adenine nucleotides and their metabolites by reversed-phase HPLC. Initial ATP, hypoxanthine and uric acid concentrations were 0.52 +/- 0.15 microM, 1.91 +/- 0.37 microM and 184 +/- 22 microM respectively. A substantial individual variation persisted within 3 weeks of sampling excepted hypoxanthine which showed some unrelated variations. Determination of nucleotides and their catabolites in saliva due to its simplicity and reproducibility, may be of clinical value in diagnosis of local or systemic disorders.

Determination of adenine nucleotides and their metabolites in human saliva

The profile and normal concentrations of nucleotide metabolites in human saliva and reproducibility of these determinations were analyzed. Samples of human saliva collected from healthy individuals at weekly intervals, were deproteinized and analysed for the content of adenine nucleotides and their metabolites by reversed-phase HPLC. Initial ATP, hypoxanthine and uric acid concentrations were 0.52 +/- 0.15 microM, 1.91 +/- 0.37 microM and 184 +/- 22 microM respectively. A substantial individual variation persisted within 3 weeks of sampling excepted hypoxanthine which showed some unrelated variations. Determination of nucleotides and their catabolites in saliva due to its simplicity and reproducibility, may be of clinical value in diagnosis of local or systemic disorders.