Clastogenic factors in plasma of HIV-1 infected patients

The objective of this study was to investigate the clastogenic activity of plasma ultrafiltrates from HIV-I infected patients. Clastogenic factors are chromosome-damaging agents with low molecular weight (<10,000 daltons) which cause chromosome aberrations, sister chromatid exchanges, DNA strand breakage, and gene mutation. They have first been described in the plasma of irradiated persons, but they are also found in hereditary breakage syndromes and chronic inflammatory diseases with autoimmune reactions. Their formation and their clastogenic effects are modulated by superoxide anion radicals. We analyzed a total of 22 HIV-1 positive patients in comparison to 20 reference plasma samples from healthy HIV negative blood donors of similar age. The plasma ultrafiltrates (filter cutoff 10,000 daltons) from patients induced a statistically significant increase in chromosomal breakage in the cytogenetic test system (20.5 ± 6.8 aberrations per 100 cells), while no increase was observed in test cultures exposed to plasma ultrafiltrates from healthy blood donors (6.3 ± 2.9 aberrations per 100 cells). The breakage values were slightly, but not significantly, lower in the 10 patients with more than 200 T-helper cells/ml (18 ± 4 aberrations per 100 cells), than in the 12 patients with less than 200 T-helper cells/ml (22.3 ± 7.9 aberrations per 100 cells). HIV patients with high clastogenic activity (induction of more than 20 aberrations per 100 cells, range 20 to 39) showed higher plasma levels for malondialdehyde than those with lower clastogenic activity (less than 20 aberrations per 100 cells, range 12 to 18). However, the difference was statistically not significant. Another lipid peroxidation product, 4-hydroxynonenal, was increased equally in both groups. There were no significant differences in water- and lipid-soluble plasma antioxidants between the low- and high-breakage group. In agreement with previous findings, the clastogenic effects of plasma ultrafiltrates in the test cultures were reduced by the antioxidant enzyme superoxide dismutase. The presence of clastogenic factors in the plasma of HIV patients is further evidence for a prooxidant state in these persons. Since clastogenic factor formation appears to occur at an early stage of the disease, it may be significant for virus release or activation, because of the superoxide anion stimulating effects of clastogenic factors. From a practical standpoint, clastogenic factors may be useful for evaluation of promising drugs.     

Growth and development of copepodite stages of Pseudocalanus spp.

Quantitative expressions are presented describing the effectsof temperature and food concentration on the growth and developmentof the copepodite stages of Pseudocalanus spp. The calculationswere made on the basis of experimental data from the literaturefor two geographically separate populations of Pseudocalanusfrom Puget Sound (Washington, USA) and from the southern NorthSea. Relationships were obtained between the growth parametersfor Pseudocalanus sp. from Puget Sound and temperature in the8–15.5°C range and food concentrations from 10 mgC m^-3 to excess, as well as for Pseudocalanus elongatus fromthe southern North Sea at high food concentrations and in the4–15°C temperature range. Also computed was the totaldevelopment time of P. elongatus for the final four copepodidstages as a function of food concentration from 50 mg C m^-3to excess and temperature from 5 to 20°C. Empirical modelscomputed here may be used with good precision in mathematicalmodels of pelagic communities.     

Cysteine Metabolism and Oxidative Processes in the Rat Liver and Kidney after Acute and Repeated Cocaine Treatment

The role of cocaine in modulating the metabolism of sulfur-containing compounds in the peripheral tissues is poorly understood. In the present study we addressed the question about the effects of acute and repeated (5 days) cocaine (10 mg/kg i.p.) administration on the total cysteine (Cys) metabolism and on the oxidative processes in the rat liver and kidney. The whole pool of sulfane sulfur, its bound fraction and hydrogen sulfide (H₂S) were considered as markers of anaerobic Cys metabolism while the sulfate as a measure of its aerobic metabolism. The total-, non-protein- and protein- SH group levels were assayed as indicators of the redox status of thiols. Additionally, the activities of enzymes involved in H₂S formation (cystathionine γ-lyase, CSE; 3-mercaptopyruvate sulfurtransferase, 3-MST) and GSH metabolism (γ-glutamyl transpeptidase, γ-GT; glutathione S-transferase, GST) were determined. Finally, we assayed the concentrations of reactive oxygen species (ROS) and malondialdehyde (MDA) as markers of oxidative stress and lipid peroxidation, respectively. In the liver, acute cocaine treatment, did not change concentrations of the whole pool of sulfane sulfur, its bound fraction, H₂S or sulfate but markedly decreased levels of non-protein SH groups (NPSH), ROS and GST activity while γ-GT was unaffected. In the kidney, acute cocaine significantly increased concentration of the whole pool of sulfane sulfur, reduced the content of its bound fraction but H₂S, sulfate and NPSH levels were unchanged while ROS and activities of GST and γ-GT were reduced. Acute cocaine enhanced activity of the CSE and 3-MST in the liver and kidney, respectively. Repeatedly administered cocaine enhanced the whole pool of sulfane sulfur and reduced H₂S level simultaneously increasing sulfate content both in the liver and kidney. After repeated cocaine, a significant decrease in ROS was still observed in the liver while in the kidney, despite unchanged ROS content, a marked increase in MDA level was visible. The repeated cocaine decreased 3-MST and increased γ-GT activities in both organs but reduced GST in the kidney. Our results show that cocaine administered at a relatively low dose shifts Cys metabolism towards the formation of sulfane sulfur compounds which possess antioxidant and redox regulatory properties and are a source of H₂S which can support mitochondrial bioenergetics.     

De novo designed cyclic cationic peptides as inhibitors of plant pathogenic bacteria

Head-to-tail cyclic peptides of 4-10 residues consisting of alternating hydrophilic (Lys) and hydrophobic (Leu and Phe) amino acids were synthesized and tested against the economically important plant pathogenic bacteria Erwinia amylovora, Xanthomonas vesicatoria and Pseudomonas syringae. The antibacterial activity, evaluated as the minimal inhibitory concentration (MIC), the cytotoxicity against human red blood cells and stability towards protease degradation were determined. The influence of cyclization, ring size, and replacement of l-Phe with d-Phe on antibacterial and hemolytic activities was studied and correlated with the degree of structuring and hydrophobicity. Our results showed that linear peptides were inactive against the three bacteria tested. Cyclic peptides were active only toward X. vesicatoria and P. syringae, being c(KLKLKFKLKQ) (BPC10L) the most active peptide with MIC values of 6.25 and 12.5 microM, respectively. The improved antibacterial activity of cyclic peptides compared to their linear counterparts was associated to an increase of the hydrophobicity, represented as RP-HPLC retention time (t(R)), and secondary structure content which are related to an enhanced amphipathicity. A decrease of antibacterial and hemolytic activities was observed when a d-Phe was introduced into the cyclic sequences, which was attributed to their low amphipathicity as shown by their low secondary structure content and low t(R). The small size, simple structure, bactericidal effect, and stability to protease degradation of the best peptides make them potential candidates for the development of effective antibacterial agents for use in plant protection.     

Cytological analysis of hybrids among triticales and trigopiros

WE STUDIED THREE DIFFERENT TRICEPIROS: (Don Santiago x Don Noé), (Cumé x Horovitz) and (Cumé x Don Noé). The tricepiro (Don Santiago x Don Noé) was obtained by crossing the triticale Don Santiago INTA (AABBRR, 2n = 6x = 42) with the trigopiro Don Noé INTA (AABBDDJJ, 2n = 8x = 56). The number of chromosomes for the F(1) was 2n = 49, the most frequent meiotic configuration being 14 bivalents and 21 univalents. The univalents were situated in the periphery of the equatorial plane, whereas the bivalents were located in the central zone. The chromatids in some of the univalents split when bivalents underwent reductional division in anaphase I. There were few laggard chromosomes or chromatids at this phase. The number of chromosomes (2n = 48-58) was high and variable, and the number of bivalents per cell (18-23) also high in F (3) individuals. In all F (8) tricepiros (Don Santiago x Don Noé), F (12) tricepiros (Cumé x Horovitz) and F (12) tricepiros (Cumé x Don Noé), the number of chromosomes (2n = 42) was the same, these retaining the rye genome, as demonstrated by GISH and FISH. These new synthesized allopolyploids constitute interesting models for investigating the evolutionary changes responsible for diploidization, and the chromosomal and genomic re-ordering that cannot be revealed in natural allopolyploids.     

Life-history traits of Amur sleeper, <Emphasis Type=Italic>Perccottus glenii</Emphasis>, in the invaded Vistula River: early investment in reproduction but reduced growth rate

In recent decades, Amur sleeper is one of the most invasive fish species in Eastern and Central Europe. Generally, it is assumed that success of an invasive species can largely depend on the plasticity of its life-history traits, e.g., indicated by higher investment in reproduction in the initial stage of its invasion. On the other hand, such energy allocation to production of gonads should negatively impact somatic growth rate. The aim of this article was to explore this phenomenon in a non-native population of Amur sleeper inhabiting artificial reservoir on a large lowland river in Central Europe. Through analysis of the population age structure, sex-dependent growth rate and life-history traits we assessed investment in reproduction and its possible relationship with growth pattern as well as compared the results with literature data from native and introduced range. Samples collected monthly from April 2005 to March 2006 were used to estimate sex ratio, GSI, fecundity, eggs diameter frequency over the year, duration of spawning season, and mode of spawning. Age structure was calculated from scales and the same data were also used to back-calculate standard length (SL) at age. The population in the Włocławski Reservoir was represented by eight age groups, and its life span was one of the longest recorded both in its natural range and introduced areas. The weight–length relationship showed that the Amur sleeper grew isometrically and there was no difference between females and males. Although the Amur sleeper growth rate was relatively slow in the Włocławski Reservoir, its increment in the first year of life was comparable to that in other introduced areas and higher than in its natural range. The female age of maturation (1+) found in the reservoir was earlier than observed in its natural range as well as in most introduced areas (2+, 3+). Female length at maturation was similar to that reported elsewhere. The back-calculated standard length (SL) of females and males showed that in the first two age classes (1 and 2) males achieved larger SL than females. Meanwhile, at age 3, 4 and 5, females were larger than males but these differences were insignificant, except for class 5. For both sexes the average annual increment of SL decreased with age but in females the increment was always higher than in males (P < 0.05). The growth rate differences between females and males resulted possibly from their unequal investment in reproduction. Multiple spawning in the Włocławski Reservoir lasted from April to the end of August and was almost 3 months longer than in other regions. Thus, this higher investment in reproduction displayed by, e.g., earlier maturation of females and longer spawning season in the Włocławski Reservoir, may contribute to invasive success of Amur sleeper in newly colonized areas; however, the costs of this strategy result in slower growth in older age classes.     

Colorimetric evaluation of the time-killing assay for Citropin 1.1, lipopeptide Palm-KK-NH2, and Temporin A

Nowadays, there are a number of colorimetric techniques available for the determination of a time killing assay in a manner much easier and faster than those previously more commonly used, which were much more time-consuming and laborious colony counting procedures. Here, an attempt has been made to test the antimicrobial peptides of Citropin 1.1, Palm-KK-NH2, and Temporin A on a reference strain of Staphylococcus aureus using resazurin as the cell viability reagent. Staphylococcus aureus was exposed to the test compounds over varying periods of time and the metabolic activity measured, with a profile of antimicrobial activity then established. The results are in agreement with data from previous literature, thus confirming the relevance of the application of resazurin for the testing of antimicrobial agents.     

Mammary gland and radiation: Knowns and unknowns

Effective breast cancer management and decreasing breast cancer fatalities is contingent upon reliable diagnostic procedures and treatment modalities, including those based on ionizing radiation. On the one hand, ionizing radiation is widely used for cancer diagnostics and therapy, on the other hand it is genotoxic cancer-causing agent. Here we discuss recent studies on the effects of low (diagnostic) and high (treatment) doses of ionizing radiation on healthy breast cells, breast cancer cells, and cancer cells resistant to common drug therapies.     

Behavioral Characterization of the Effects of Cannabis Smoke and Anandamide in Rats

Cannabis is the most widely used illicit drug in the world. Delta-9-tetrahydrocannabinol (Δ9-THC) is the main psychoactive component of cannabis and its effects have been well-studied. However, cannabis contains many other cannabinoids that affect brain function. Therefore, these studies investigated the effect of cannabis smoke exposure on locomotor activity, rearing, anxiety-like behavior, and the development of dependence in rats. It was also investigated if cannabis smoke exposure leads to tolerance to the locomotor-suppressant effects of the endogenous cannabinoid anandamide. Cannabis smoke was generated by burning 5.7% Δ9-THC cannabis cigarettes in a smoking machine. The effect of cannabis smoke on the behavior of rats in a small and large open field and an elevated plus maze was evaluated. Cannabis smoke exposure induced a brief increase in locomotor activity followed by a prolonged decrease in locomotor activity and rearing in the 30-min small open field test. The cannabinoid receptor type 1 (CB₁) receptor antagonist rimonabant increased locomotor activity and prevented the smoke-induced decrease in rearing. Smoke exposure also increased locomotor activity in the 5-min large open field test and the elevated plus maze test. The smoke exposed rats spent more time in the center zone of the large open field, which is indicative of a decrease in anxiety-like behavior. A high dose of anandamide decreased locomotor activity and rearing in the small open field and this was not prevented by rimonabant or pre-exposure to cannabis smoke. Serum Δ9-THC levels were 225 ng/ml after smoke exposure, which is similar to levels in humans after smoking cannabis. Exposure to cannabis smoke led to dependence as indicated by more rimonabant-precipitated somatic withdrawal signs in the cannabis smoke exposed rats than in the air-control rats. In conclusion, chronic cannabis smoke exposure in rats leads to clinically relevant Δ9-THC levels, dependence, and has a biphasic effect on locomotor activity.