Lipids as a target for drugs modulating multidrug resistance of cancer cells

In this review we focus on the role of the membrane lipids in multidrug resistance and its modulation. Results of the research performed in recent years indicate the importance of lipid phase playing active role in many membrane processes. Along with the alterations of lipid membrane composition of cancer cells (with respect to the normal ones) the resulting changes of the biophysical membrane properties are discussed. Next we describe the general features of multidrug resistance phenomenon paying a special attention to the role of lipids and alterations of lipid membrane composition in MDR cells. Taking into account the phase separation properties of sphingolipids the importance of membrane heterogeneity (presence of caveole and lipid rafts) is emphasised. On the basis of vacuum cleaner hypothesis of drug transport proteins action we discuss the importance of lipid bilayer as medium in which diffusion of drugs takes place. Considering the membrane fluidity and its influence on the integral proteins activity, we underline the role of balance between the passive cellular influx and active efflux of the drug molecules. Finally the effects exerted on membranes by different kinds of multidrug resistance modulators (chemosensitizers) are described. In this part we discuss the influence of verapamil, phenothiazine derivatives, tamoxifen and chosen flavonoids on the biophysical properties of membrane lipids. Some further consequences of the alteration of membrane state are also considered.

Mycobacterium tuberculosis infection as a zoonotic disease: transmission between humans and elephants

Between 1994 and 1996, three elephants from an exotic animal farm in Illinois died of pulmonary disease due to Mycobacterium tuberculosis. In October 1996, a fourth living elephant was culture-positive for M. tuberculosis. Twenty-two handlers at the farm were screened for tuberculosis (TB); eleven had positive reactions to intradermal injection with purified protein derivative. One had smear-negative, culture-positive active TB. DNA fingerprint comparison by IS6110 and TBN12 typing showed that the isolates from the four elephants and the handler with active TB were the same strain. This investigation indicates transmission of M. tuberculosis between humans and elephants.

Protective effect of green tea against lipid peroxidation in the rat liver, blood serum and the brain

This paper reports data on the effect of green tea on the lipid peroxidation products formation and parameters of antioxidative system of the liver, blood serum and central nervous tissue of healthy young rats drinking green tea for five weeks. The rats were permitted free access to solubilized extract of green tea. Bioactive ingredients of green tea extract caused in the liver an increase in the activity of glutathione peroxidase and glutathione reductase and in the content of reduced glutathione as well as marked decrease in lipid hydroperoxides (LOOH), 4-hydroksynonenal (4-HNE) and malondialdehyde (MDA). The concentration of vitamin A increased by about 40%. Minor changes in the measured parameters were observed in the blood serum. GSH content increased slightly, whereas the index of the total antioxidant status increased significantly. In contrast, the lipid peroxidation products, particularly MDA was significantly diminished. In the central nervous tissue the activity of superoxide dismutase and glutathione peroxidase decreased while the activity od glutathione reductase and catalase increased after drinking green tea. Moreover the level of LOOH, 4-HNE and MDA significantly decreased. The use of green tea extract appeared to be beneficial to rats in reducing lipid peroxidation products. These results support and substantiate traditional consumption of green tea as protection against lipid peroxidation in the liver, blood serum, and central nervous tissue.

Trifluoperazine induces domain formation in zwitterionic phosphatidylcholine but not in charged phosphatidylglycerol bilayers

The interaction of trifluoperazine with the zwitterionic lipids dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine and with anionic dimyristoylphosphatidylglycerol was studied by means of microcalorimetry and fluorescence spectroscopy. Intercalation of drug molecules into the lipid bilayers was confirmed by the observed differential scanning calorimetry peak broadening and the decrease in chain-melting temperatures. For trifluoperazine:lipid mole ratios higher than 0.4 and 0.6 (for dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine, respectively) the deconvolution of transition profiles into two Gaussian components was possible, which suggests phase separation in the studied mixtures. Deconvolution of the thermograms was not possible for any of the drug:dimyristoylphosphatidylglycerol mole ratios studied. To confirm the existence of phase separation in trifluoperazine-phosphatidylcholine mixtures fluorescence spectroscopy experiments were performed using Laurdan as a probe. From the generalised polarisation versus excitation wavelength dependences, recorded at different temperatures, we conclude that a phase separation occurs in the gel state of the studied trifluoperazine-phosphatidylcholine mixtures. We attribute the existence of domains in the bilayer to the dissimilar interactions of two protonation forms of trifluoperazine with phosphatidylcholine molecules. Structural defects present at domain boundaries could be related to the trifluoperazine induced increase of membrane permeability and fluidity. This may partially explain the mechanism of multidrug resistance modulation by trifluoperazine.

Interaction of spectrin with phospholipids. Quenching of spectrin intrinsic fluorescence by phospholipid suspensions

Phospholipid suspensions prepared of phosphatidylethanolamine, phosphatidylserine and their mixtures are able to influence the intrinsic protein fluorescence of spectrin. In the case of phosphatidylethanolamine suspension up to 75% of protein fluorescence can be quenched. The interaction of phospholipid aggregates with spectrin is modulated by pH and ionic strength. Phospholipids, particularly phosphatidylethanolamine display a 'stabilizing' effect against the changes of protein fluorescence induced by increasing ionic strength and by thermal denaturation.

Peroxiredoxin 5 modulates immune response in Drosophila

BACKGROUND

Peroxiredoxins are redox-sensing enzymes with multiple cellular functions. Previously, we reported on the potent antioxidant function of Drosophila peroxiredoxin 5 (dPrx5). Studies with mammalian and human cells suggest that peroxiredoxins can modulate immune-related signaling.

METHODS

Survivorship studies and bacteriological analysis were used to determine resistance of flies to fungal and bacterial infections. RT-PCR and immunoblot analyses determined expression of dPrx5 and immunity factors in response to bacterial challenge. Double mutants for dprx5 gene and genes comprising the Imd/Relish and dTak1/Basket branches of the immune signaling pathways were used in epistatic analysis.

RESULTS

The dprx5 mutant flies were more resistant to bacterial infection than controls, while flies overexpressing dPrx5 were more susceptible. The enhanced resistance to bacteria was accompanied by rapid induction of the Imd-dependent antimicrobial peptides, phosphorylation of the JNK kinase Basket and altered transcriptional profiling of the transient response genes, puckered, ets21C and relish, while the opposite effects were observed in flies over-expressing dPrx5. Epistatic analysis of double mutants, using attacin D and Puckered as read outs of activation of the Imd and JNK pathways, implicated dPrx5 function in the control of the dTak1-JNK arm of immune signaling.

CONCLUSIONS

Differential effects on fly survivorship suggested a trade-off between the antioxidant and immune functions of dPrx5. Molecular and epistatic analyses identified dPrx5 as a negative regulator in the dTak1-JNK arm of immune signaling.

GENERAL SIGNIFICANCE

Our findings suggest that peroxiredoxins play an important modulatory role in the Drosophila immune response.

Mitochondrial peroxiredoxins are critical for the maintenance of redox state and the survival of adult Drosophila

Drosophila mitochondria contain two peroxidases, peroxiredoxin 3 (dPrx3) and peroxiredoxin 5 (dPrx5), which together constitute the sole known intramitochondrial mechanism for the catalytic removal of hydrogen and organic peroxides. dPrx3 exists exclusively within mitochondria, whereas dPrx5 is also present in some other intracellular compartments. Levels of these two peroxiredoxins were genetically manipulated, singly and together, in D. melanogaster, for the purpose of understanding their respective functions. Underexpression of dPrx3 by 90-95% had no discernable effect on life span under normal or oxidative stress conditions; the dPrx5 null flies were previously reported to exhibit a 10% shortening of mean life span and an increase in sensitivity to oxidative stress. Flies underexpressing both dPrx3 and dPrx5 showed an 80% decrease in life span, a severe disruption in thiol homeostasis, and a massive induction of apoptosis in the muscle and digestive system tissues. The early mortality in flies underexpressing both peroxiredoxins was partially offset by overexpression of thioredoxin reductase but not mitochondrion-targeted catalase. These results suggest that mitochondrial peroxiredoxins confer specific protection for thioredoxin/glutathione systems, play a critical role in the maintenance of global thiol homeostasis, and prevent the age-associated apoptosis and premature death.

Effects of atrial natriuretic factor on drinking responses to central angiotensin II

The present study examined the effects of ANF(4-28) [Wy-47,663], a synthetic 25 amino acid human atrial natriuretic factor, on the dipsogenic actions of centrally-administered angiotensin II in conscious rats. Bolus injection (100 ng) or continuous infusion (60 ng/min) of Wy-47,663 or vehicle into the lateral cerebroventricle had no effect on mean arterial pressure or heart rate. No obvious behavioral changes were observed after central administration of Wy-47,663 or vehicle. Central injection of angiotensin II (15 or 30 ng) promptly elicited prolonged drinking responses in vehicle-treated rats. In rats pretreated with Wy-47,663, the onset of the angiotensin II-induced drinking responses was significantly delayed compared to vehicle-treated animals. However, Wy-47,663 had no effect on the total volume consumed over 30 minutes after angiotensin II injection. Intravenous infusion of Wy-47,663 (2 micrograms/kg/min) failed to alter the dipsogenic action of centrally administered angiotensin II. These data indicate that atrial natriuretic factor found within the brain but not the peripheral circulation may participate in the regulation of extracellular fluid volume by modulating the dipsogenic actions of the central renin-angiotensin system.

Monitoring of MRP-like activity in human erythrocytes: inhibitory effect of isoflavones

A method to fluorometrically monitor efflux of 2',7'-bis-(carboxypropyl)-5(6)-carboxyfluorescein (BCPCF) from human erythrocytes was developed. Genistein, daidzein, sophoraisoflavone A, and licoisoflavone A induced 50% inhibition (IC(50)) of BCPCF efflux at 15-70 microM. The IC(50) value of the most efficient isoflavone, licoisoflavone A (15-25 microM), was comparable to that of indomethacin (approximately 10 microM) and markedly lower than for probenecid (100-200 microM), both known MRP1 inhibitors. Our results indicate that the human erythrocyte is a useful cell model in screening potential MRP inhibitors, that BCPCF is a good substrate for MRP, and that some isoflavones at low concentrations inhibit MRP-mediated efflux.

The effect of peroxiredoxin 4 on fly physiology is a complex interplay of antioxidant and signaling functions

Peroxiredoxin 4 (Prx4) has been implicated in a wide variety of biological processes, including development, progression of cancer, inflammation, and antioxidant function. The purpose of this study was to provide further insight into its multiple roles at the whole-animal level, using Drosophila. Reduced expression of dPrx4 (up to 90%) resulted in greater sensitivity to oxidative stress, an elevated H₂O₂ flux, and increases in lipid peroxidation, but no effect on longevity. Overexpression at low levels (<2-fold) gave reduced levels of oxidative damage and tended to show an increase in longevity. Flies expressing dPrx4 globally at high levels (>5-fold) had a dramatically reduced life span (by 20-80%) and increased apoptosis. Analysis of these overexpressors revealed an aberrant redistribution of the dPrx4 protein from the endoplasmic reticulum (ER) to cytosol and hemolymph. In addition to the known proapoptotic effects of the cytosolic form of dPrx4, dPrx4 overexpression triggered an NF-κB-mediated proinflammatory response, similar to that observed in cells under ER stress or when microbially challenged. Finally, we provide the first evidence that dPrx4, on secretion into the hemolymph, elicits a JAK/STAT-mediated response. The effects on fly survival and homeostasis appear to represent a combination of differential effects dictated in large part by dPrx4 subcellular and tissue-specific localization.

Genome differentiation of Drosophila melanogaster from a microclimate contrast in Evolution Canyon, Israel

The opposite slopes of "Evolution Canyon" in Israel have served as a natural model system of adaptation to a microclimate contrast. Long-term studies of Drosophila melanogaster populations inhabiting the canyon have exhibited significant interslope divergence in thermal and drought stress resistance, candidate genes, mobile elements, habitat choice, mating discrimination, and wing-shape variation, all despite close physical proximity of the contrasting habitats, as well as substantial interslope migration. To examine patterns of genetic differentiation at the genome-wide level, we used high coverage sequencing of the flies' genomes. A total of 572 genes were significantly different in allele frequency between the slopes, 106 out of which were associated with 74 significantly overrepresented gene ontology (GO) terms, particularly so with response to stimulus and developmental and reproductive processes, thus corroborating previous observations of interslope divergence in stress response, life history, and mating functions. There were at least 37 chromosomal "islands" of interslope divergence and low sequence polymorphism, plausible signatures of selective sweeps, more abundant in flies derived from one (north-facing) of the slopes. Positive correlation between local recombination rate and the level of nucleotide polymorphism was also found.

Modeling the role of peroxisome proliferator-activated receptor γ and microRNA-146 in mucosal immune responses to Clostridium difficile

Clostridium difficile is an anaerobic bacterium that has re-emerged as a facultative pathogen and can cause nosocomial diarrhea, colitis or even death. Peroxisome proliferator-activated receptor (PPAR) γ has been implicated in the prevention of inflammation in autoimmune and infectious diseases; however, its role in the immunoregulatory mechanisms modulating host responses to C. difficile and its toxins remains largely unknown. To characterize the role of PPARγ in C. difficile-associated disease (CDAD), immunity and gut pathology, we used a mouse model of C. difficile infection in wild-type and T cell-specific PPARγ null mice. The loss of PPARγ in T cells increased disease activity and colonic inflammatory lesions following C. difficile infection. Colonic expression of IL-17 was upregulated and IL-10 downregulated in colons of T cell-specific PPARγ null mice. Also, both the loss of PPARγ in T cells and C. difficile infection favored Th17 responses in spleen and colonic lamina propria of mice with CDAD. MicroRNA (miRNA)-sequencing analysis and RT-PCR validation indicated that miR-146b was significantly overexpressed and nuclear receptor co-activator 4 (NCOA4) suppressed in colons of C. difficile-infected mice. We next developed a computational model that predicts the upregulation of miR-146b, downregulation of the PPARγ co-activator NCOA4, and PPARγ, leading to upregulation of IL-17. Oral treatment of C. difficile-infected mice with the PPARγ agonist pioglitazone ameliorated colitis and suppressed pro-inflammatory gene expression. In conclusion, our data indicates that miRNA-146b and PPARγ activation may be implicated in the regulation of Th17 responses and colitis in C. difficile-infected mice.

Reaction of arylsulfonylhydrazones of aldehydes with alpha-magnesio sulfones. A novel olefin synthesis

Reactions of representative tosylhydrazones of aldehydes and ketones with alpha-metalated sulfones were examined in order to develop a practical olefination method. Treatment of aldehyde tosylhydrazone 2 with an excess of alpha-lithiated methyl phenyl or dimethyl sulfones yielded 3a. The reaction of 2 with sterically unhindered lithiated alkyl sulfones gave mixtures of the respective olefination products 3b-d along with the Shapiro fragmentation product 4. Sterically hindered lithiated sulfones afforded Shapiro products exclusively. In contrast, aldehyde tosylhydrazones 2 or 6 in reactions with a variety of alpha-magnesio primary or secondary alkyl sulfones gave olefination products 3a-j and 7a-c in high yields (Tables 1 and 2). beta-Branched alkyl sulfones afforded predominantly (E)-alkenes, whereas unhindered primary sulfones gave mixtures of (E)- and (Z)-alkenes with low selectivity. Reaction of the 2,4,6-triisopropylbenzenesulfonylhydrazone (trisylhydrazone) of cyclodecanone 11c with alpha-magnesio methyl phenyl sulfone afforded the methylidene derivative 12a contaminated with the Shapiro product 13. Tosylhydrazone 2 resisted reaction with i-PrMgCl and gave only a small amount of the addition product in reaction with Bu(2)Mg. Some mechanistic aspects of the reaction of tosylhydrazones with organomagnesium compounds are discussed.

Interactions of Phenothiazines with Lipid Bilayer and their Role in Multidrug Resistance Reversal

The mechanism of multidrug resistance (MDR) reversal is not fully understood yet. Interaction of MDR modifiers with lipid bilayer of cell membranes and alterations of fluidity or other biophysical properties of plasma membrane might be an important factor in mechanism of MDR modulation and reversal. In this review we focus on phenothiazines which belong to the group of drugs known to modify MDR in different types of cells, from cancer cells up to various kinds of microorganisms. First, the aggregation properties of phenothiazines and their interactions with lipid bilayers are described. The localization of phenothazine derivative molecules in bilayers and alteration of membrane properties are discussed. Apart from the influence on model bilayers also the interactions of phenothiazines with cellular membranes (especially of erythrocytes) are reviewed. In subsequent sections the anti-MDR activity of phenothiazine derivatives observed in microorganisms and in cancer cells is described. The possible molecular mechanisms involved in MDR reversal by these compounds are presented. The direct interactions of phenothiazines with multidrug transporters and other effects of these modulators on plasma membranes are discussed. Finally, the structural features of phenothiazine derivatives essential for their optimal MDR reversal activity are described.

Prevention of mother-to-child transmission of hepatitis B virus (HBV) during pregnancy and the puerperium: current standards of care

BACKGROUND

Mother-to-child transmission (MTCT) of hepatitis B virus continues to occur despite the interventions of hepatitis B vaccination and immunoglobulin. The most significant risk factor in transmission is high maternal viral load. Being aware of viral replicative activity permits risk stratification and allows the opportunity for additional preventative measures such as antiviral therapy.

METHODS

Retrospective audit of investigations and clinical management among hepatitis B surface antigen-positive pregnant women from three maternity services across Victoria over a five-year period from 2006 to 2011.

RESULTS

Over the study period at the three institutions, there were 46,855 births, and 398 hepatitis B-positive pregnant women. 87% of the women were non-Australian-born. Viral load testing was performed in <20% of all pregnancies, and hepatitis B e antigen status assessed in 33%. Only 18% of the women with hepatitis B were referred for specialist care, but if referred, they were more likely to have an assessment of viral replicative status performed. Compliance with administration of neonatal hepatitis B immunoglobulin and birth-dose vaccination was high (>90%).

CONCLUSION

There is scope for considerable improvement in referral and assessment of pregnant women with hepatitis B infection. Guidelines addressing the issue of maternal viral replicative status and the need for antiviral therapy may assist in guiding clinical management.

Activity of 2-chlorodeoxyadenosine (Cladribine) in 2-hour intravenous infusion in 94 previously treated patients with low grade non-Hodgkin's lymphoma

The purpose of our study was to determine the efficacy of 2-chlorodeoxyadenosine (2-CdA) administered in 2-hour intravenous infusions in previously treated patients with low grade non-Hodgkin's lymphoma (LGNHL). We treated 94 LGNHL patients with 2-CdA at a dosage of 0.12 mg/kg/24h in 2-hour intravenous infusion for 5 consecutive days. The treatment consisted of from 1 to 7 courses (median 3), repeated usually at monthly intervals. All patients were refractory to or relapsed after standard chemotherapy. Of these 94 patients 78 (83%) had clinical stage IV of the disease. Complete response (CR) was obtained in 12 (12.8%) and partial response (PR) in 36 (38.3%) giving an overall response rate of 51.1%. In 12 (12.8%) grade 4 thrombocytopenia with haemorrhagic diathesis was noted, grade 4 neutropenia was observed in 12 (12.8%) and infections complicated the course of treatment in 38 (40.4%) patients. 2-CdA treatment was the cause of death of 3 patients. The results of our study show that 2-CdA given in 2-hour infusions is an effective agent in advanced, heavily pretreated patients with LGNHL.

Effects of ectopic expression of Drosophila DNA glycosylases dOgg1 and RpS3 in mitochondria

The main purpose of this study was to determine whether enhancement of repair capacity would attenuate mitochondrial DNA oxidative damage and result in greater cell survival under stressful conditions. The repair of oxidative damage is initiated by DNA glycosylases, which catalyze the excision of oxidized bases, such as 8-hydroxydeoxyguanosine (8-oxodG). Drosophila DNA glycosylases, dOgg1 and RpS3, were ectopically expressed within the mitochondrial matrix in Drosophila S2 cells, causing a severalfold decrease in the levels of 8-oxodG in mitochondrial DNA. Unexpectedly, cells did not show increased resistance to oxidative stress, but instead became more susceptible to treatment with hydrogen peroxide or paraquat. Even in the absence of oxidative challenge, cells expressing RpS3 or dOgg1 in mitochondria exhibited increased apoptosis relative to controls, as determined by flow-cytometric analysis of Annexin V and DNA degradation measured by the Comet assay. Another notable finding was that ectopic expression of either dOgg1 or RpS3 in mitochondria increased cell survival after exposure to the nitric oxide donor SNAP. These results suggest that ectopic expression of one of the constituents of the DNA repair system in mitochondria may cause a perturbation in the base excision repair pathway and lower, rather than enhance, survivability.

Drosophila peroxiredoxin 5 is the second gene in a dicistronic operon

We identified a Drosophila homologue that belongs to a subfamily of the mammalian peroxiredoxin 5 genes. The Drosophila peroxiredoxin 5 (dPrx 5) gene corresponds to CG7217 (FlyBase nomenclature), and exhibits identical polarity to that of the nearby upstream CG7215 gene, for which the deduced amino acid sequence reveals an ubiquitin-like domain at the N-terminus. The tandem pattern of the arrangement of these two genes is well-conserved among the Drosophilids. In addition to CG7215 and dPrx5 gene-specific transcripts that could be transcribed independently from two distinct promoters, transcripts spanning both coding regions have been identified, leading to the characterization of this gene cluster as a dicistronic operon. The different transcripts exhibit stage-specific accumulation patterns. While the upstream CG7215 gene can be expressed from both mono- and dicistronic mRNAs, the downstream dPrx5 gene is likely to be expressed predominantly from its monocistronic transcripts.

Genomic Signatures of Speciation in Sympatric and Allopatric Hawaiian Picture-Winged Drosophila

The Hawaiian archipelago provides a natural arena for understanding adaptive radiation and speciation. The Hawaiian Drosophila are one of the most diverse endemic groups in Hawaiì with up to 1,000 species. We sequenced and analyzed entire genomes of recently diverged species of Hawaiian picture-winged Drosophila, Drosophila silvestris and Drosophila heteroneura from Hawaiì Island, in comparison with Drosophila planitibia, their sister species from Maui, a neighboring island where a common ancestor of all three had likely occurred. Genome-wide single nucleotide polymorphism patterns suggest the more recent origin of D. silvestris and D. heteroneura, as well as a pervasive influence of positive selection on divergence of the three species, with the signatures of positive selection more prominent in sympatry than allopatry. Positively selected genes were significantly enriched for functional terms related to sensory detection and mating, suggesting that sexual selection played an important role in speciation of these species. In particular, sequence variation in Olfactory receptor and Gustatory receptor genes seems to play a major role in adaptive radiation in Hawaiian pictured-winged Drosophila.

Design, synthesis, and bioactivity of the first nonsteroidal mimetics of brassinolide

Ten novel compounds, each consisting of two subunits and a linker, were designed with the aid of molecular modeling to resemble the natural steroidal phytohormone brassinolide. The mimetics were synthesized and subjected to the rice leaf lamina inclination bioassay to test for brassinosteroid activity. Most of the mimetics displayed very weak or no bioactivity, but two were strongly active when coapplied with the auxin indole-3-acetic acid (IAA), which synergizes the activity of brassinosteroids. Thus, 1-(4,6 alpha,7 alpha-trihydroxy-5,6,7,8-tetrahydronaphthyl)-2-(6 alpha',7 alpha'-dihydroxy-5',6',7',8'-tetrahydronaphthyl)ethyne (4) and (E)-1,2-bis[trans-(4a alpha,8a beta)-4-oxo-6 alpha,7 alpha-dihydroxy-4a,5,6,7,8,8a-hexahydro-(3H)-naphthyl]ethylene (11) showed exceptional activity at doses as low as 0.01 ng and 0.001 ng/plant, respectively. These compounds are the first biologically active nonsteroidal brassinolide mimetics.

Anti-Acne Action of Peptides Isolated from Burdock Root-Preliminary Studies and Pilot Testing

This work aimed to study the anti-bacterial, anti-biofilm and anti-oxidant potential effects of low molecular weight (LMW) peptides (Br-p) isolated from burdock (Arctium lappa L.) roots. We conducted a preliminary study to exclude or confirm the antibiotic activity of the LMW peptides fraction of this plant. Br-p were isolated using gel filtration and a 10 kDa cut-off membrane. The obtained peptides were identified by MALDI TOF/TOF. Antibacterial activity was tested against acne strains using diffusion tests, MIC and MBC. The fibroblast cytotoxicity of Br-p was tested, and the selectivity index (SI) value was determined. The fraction of 46 Br-p peptides isolated from burdock root with a molecular weight below 5000 Da and theoretic pI (isoelectric point) of 3.67-11.83 showed a narrow spectrum of activity against Gram-positive acne bacterial strains. One of the Br-p peptides assessed on MALDI RapidDeNovo was LRCDYGRFFASKSLYDPLKKRR cationic peptide. It was analogous to that contained in A. lappa protein, and theoretically it was matched as a peptide with antibiotic nature. Br-p did not show toxicity to fibroblasts in the tested concentration up to 10 mg/mL, obtaining CC50 10 mg/mL. The SI value for the tested Propionibacterium strains ranged from 160 to 320. Finally, an active dressing based on chitosan/alginate/genipin was prepared using freeze-drying. The formed dressing was evaluated for its anti-acne activity. To sum up: preliminary biological studies confirmed the anti-acne properties of the isolated peptide fraction from burdock root and pointed to the possibility of using it to create an active dressing on the skin.

The Role of Complement Activating Collectins and Associated Serine Proteases in Patients With Hematological Malignancies, Receiving High-Dose Chemotherapy, and Autologous Hematopoietic Stem Cell Transplantations (Auto-HSCT)

We conducted a prospective study of 312 patients (194 with multiple myeloma, 118 with lymphomas) receiving high-dose conditioning chemotherapy and autologous hematopoietic stem cell transplantation (auto-HSCT). Polymorphisms of MBL2 and MASP2 genes were investigated and serial measurements of serum concentrations of mannose-binding lectin (MBL), CL-LK collectin and MASP-2 as well as activities of MBL-MASP-1 and MBL-MASP-2 complex were made. Serum samples were taken before conditioning chemotherapy, before HSCT and once weekly after (totally 4-5 samples); in minority of subjects also 1 and/or 3 months post transplantation. The results were compared with data from 267 healthy controls and analyzed in relation to clinical data to explore possible associations with cancer and with chemotherapy-induced medical complications. We found a higher frequency of MBL deficiency-associated genotypes (LXA/O or O/O) among multiple myeloma patients compared with controls. It was however not associated with hospital infections or post-HSCT recovery of leukocytes, but seemed to be associated with the most severe infections during follow-up. Paradoxically, high MBL serum levels were a risk factor for prolonged fever and some infections. The first possible association of MBL2 gene 3′-untranslated region polymorphism with cancer (lymphoma) in Caucasians was noted. Heterozygosity for MASP2 gene +359 A>G mutation was relatively frequent in lymphoma patients who experienced bacteremia during hospital stay. The median concentration of CL-LK was higher in myeloma patients compared with healthy subjects. Chemotherapy induced marked increases in serum MBL and MASP-2 concentrations, prolonged for several weeks and relatively slighter decline in CL-LK level within 1 week. Conflicting findings on the influence of MBL on infections following chemotherapy of myeloma and lymphoma have been reported. Here we found no evidence for an association between MBL deficiency and infection during the short period of neutropenia following conditioning treatment before HSCT. However, we noted a possible protective effect of MBL during follow-up, and suspected that to be fully effective when able to act in combination with phagocytic cells after their recovery.

Cyclization of flavokawain B reduces its activity against human colon cancer cells

Chalcones are naturally occurring compounds exhibiting biological activity through multiple mechanisms. Flavokawain B is one of chalcones found in kava plant. In our studies, we focused on the anticancer activity of flavokawain B in colorectal cancer cells LoVo and its resistant to doxorubicin subline-LoVo/Dx. Strong cytotoxic activity of flavokawain B and its ability to inhibit the proliferation in both cell lines was detected. These effects accompanied with induction cell cycle arrest in G2/M phase and the presence of SubG1 fraction. Flavokawain B at low concentration led to increase of caspase-3 activity. The chalcone-induced apoptosis was also confirmed by DNA fragmentation. In our work, the conversion of flavokawain B to corresponding flavanone-5,7-dimetoxyflavanone-was shown to be more extensive in cancer than in non-cancer cells. We found that the cyclization of the chalcone was related to the significant decrease in the cytotoxicity. Cell proliferation and cell cycle progression were not impaired significantly in the studied cancer cells incubated with 5,7-dimethoxyflavanone. We did not observe apoptosis in the cells incubated with flavanone. The results from biological studies agreed with the theoretical activity that emerges from structural parameters.

Genistein inhibits the activity of kv1.3 potassium channels in human T lymphocytes

In the present study, the whole-cell patch-clamp technique was applied to follow the inhibitory effect of genistein--a tyrosine kinase inhibitor and a natural anticancer agent--on the activity of voltage-gated potassium channels Kv1.3 expressed in human T lymphocytes (TL). Obtained data provide evidence that genistein application in the concentration range of 1-80 microM reversibly decreased the whole-cell potassium currents in TL in a concentration-dependent manner to about 0.23 of the control value. The half-blocking concentration range of genistein was from 10 to 40 microM. The current inhibition was correlated in time with a significant decrease of the current activation rate. The steady-state activation of the currents was unchanged upon application of genistein, as was the inactivation rate. The inhibitory effect of genistein on the current amplitude and activation kinetics was voltage-independent. The current inhibition was not changed significantly in the presence of 1 mM of sodium orthovanadate, a tyrosine phosphatase inhibitor. Application of daidzein, an inactive genistein analogue, did not affect significantly either the current amplitudes or the activation kinetics. Possible mechanisms of the observed phenomena and their significance for genistein-induced inhibition of cancer cell proliferation are discussed.