Effects of temperature and doxorubicin exposure on keratinocyte damage in vitro

Cancer chemotherapy treatment often leads to hair loss, which may be prevented by cooling the scalp during drug administration. The current hypothesis for the hair preservative effect of scalp cooling is that cooling of the scalp skin reduces blood flow (perfusion) and chemical reaction rates. Reduced perfusion leads to less drugs available for uptake, whereas the reduced temperature decreases uptake of and damage by chemotherapy. Altogether, less damage is exerted to the hair cells, and the hair is preserved. However, the two mechanisms in the hypothesis have not been quantified yet. To quantify the effect of reduced drug damage caused by falling temperatures, we investigated the effect of local drug concentration and local tissue temperature on hair cell damage using in vitro experiments on keratinocytes. Cells were exposed for 4 h to a wide range of doxorubicin concentrations. During exposure, cells were kept at different temperatures. Cell viability was determined after 3 d using a viability test. Control samples were used to establish a concentration–viability curve. Results show that cell survival is significantly higher in cooled cells (T < 22° C) than in non-cooled cells (T = 37° C), but no significant differences are visible between T = 10° C and T = 22° C. Based on this result and previous work, we can conclude that there is an optimal temperature in scalp cooling. Further cooling will only result in unnecessary discomfort for the patient and should therefore be avoided

Effect of starch-based biomaterials on the in vitro proliferation and viability of osteoblast-like cells

The cytotoxicity of starch-based polymers was investigated using different methodologies. Poly-L-lactic acid (PLLA) was used as a control for comparison purposes. Extracts of four different starch-based blends (corn starch and ethylene vinyl alcohol (SEVA-C), corn starch and cellulose acetate (SCA), corn starch and polycaprolactone (SPCL) and starch and poly-lactic acid (SPLA70) were prepared in culture medium and their toxicity was analysed. Osteoblast-like cells (SaOs-2) were incubated with the extracts and cell viability was assessed using the MTT test and a lactate dehydrogenase (LDH) assay. In addition DNA and total protein were quantified in order to evaluate cell proliferation. Cells were also cultured in direct contact with the polymers for 3 and 7 days and observed in light and scanning electron microscopy (SEM). LDH and DNA quantification revealed to be the most sensitive tests to assess respectively cell viability and cell proliferation after incubation with starch-based materials and PLLA. SCA was the starch blend with higher cytotoxicity index although similar to PLLA polymer. Cell adhesion tests confirmed the worst performance of the blend of starch with cellulose acetate but also showed that SPCL does not perform as well as it could be expected. All the other materials were shown to present a comparable behaviour in terms of cell adhesion showing slight differences in morphology that seem to disappear for longer culture times. The results of this study suggest that not only the extract of the materials but also their three-dimensional form has to be biologically tested in order to analyse material-associated parameters that are not possible to consider within the degradation extract. In this study, the majority of the starch-based biomaterials presented very promising results in terms of cytotoxicity, comparable to the currently used biodegradable PLLA which might lead the biocompatibility evaluation of those novel biomaterials to other studies.Fundação para a Ciência e a Tecnologia (FCT

Helicobacter pylori Adapts to Chronic Infection and Gastric Disease via pH-Responsive BabA-Mediated Adherence

International audienceThe BabA adhesin mediates high-affinity binding of Helicobacter pylori to the ABO blood group antigen-glycosylated gastric mucosa. Here we show that BabA is acid responsive-binding is reduced at low pH and restored by acid neutralization. Acid responsiveness differs among strains; often correlates with different intragastric regions and evolves during chronic infection and disease progression; and depends on pH sensor sequences in BabA and on pH reversible formation of high-affinity binding BabA multimers. We propose that BabA's extraordinary reversible acid responsiveness enables tight mucosal bacterial adherence while also allowing an effective escape from epithelial cells and mucus that are shed into the acidic bactericidal lumen and that bio-selection and changes in BabA binding properties through mutation and recombination with babA-related genes are selected by differences among individuals and by changes in gastric acidity over time. These processes generate diverse H. pylori subpopulations, in which BabA's adaptive evolution contributes to H. pylori persistence and overt gastric disease

International Society of Sports Nutrition Position Stand: Probiotics.

Position statement: The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of probiotic supplementation to optimize the health, performance, and recovery of athletes. Based on the current available literature, the conclusions of the ISSN are as follows: 1)Probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host (FAO/WHO).2)Probiotic administration has been linked to a multitude of health benefits, with gut and immune health being the most researched applications.3)Despite the existence of shared, core mechanisms for probiotic function, health benefits of probiotics are strain- and dose-dependent.4)Athletes have varying gut microbiota compositions that appear to reflect the activity level of the host in comparison to sedentary people, with the differences linked primarily to the volume of exercise and amount of protein consumption. Whether differences in gut microbiota composition affect probiotic efficacy is unknown.5)The main function of the gut is to digest food and absorb nutrients. In athletic populations, certain probiotics strains can increase absorption of key nutrients such as amino acids from protein, and affect the pharmacology and physiological properties of multiple food components.6)Immune depression in athletes worsens with excessive training load, psychological stress, disturbed sleep, and environmental extremes, all of which can contribute to an increased risk of respiratory tract infections. In certain situations, including exposure to crowds, foreign travel and poor hygiene at home, and training or competition venues, athletes' exposure to pathogens may be elevated leading to increased rates of infections. Approximately 70% of the immune system is located in the gut and probiotic supplementation has been shown to promote a healthy immune response. In an athletic population, specific probiotic strains can reduce the number of episodes, severity and duration of upper respiratory tract infections.7)Intense, prolonged exercise, especially in the heat, has been shown to increase gut permeability which potentially can result in systemic toxemia. Specific probiotic strains can improve the integrity of the gut-barrier function in athletes.8)Administration of selected anti-inflammatory probiotic strains have been linked to improved recovery from muscle-damaging exercise.9)The minimal effective dose and method of administration (potency per serving, single vs. split dose, delivery form) of a specific probiotic strain depends on validation studies for this particular strain. Products that contain probiotics must include the genus, species, and strain of each live microorganism on its label as well as the total estimated quantity of each probiotic strain at the end of the product's shelf life, as measured by colony forming units (CFU) or live cells.10)Preclinical and early human research has shown potential probiotic benefits relevant to an athletic population that include improved body composition and lean body mass, normalizing age-related declines in testosterone levels, reductions in cortisol levels indicating improved responses to a physical or mental stressor, reduction of exercise-induced lactate, and increased neurotransmitter synthesis, cognition and mood. However, these potential benefits require validation in more rigorous human studies and in an athletic population

The Helicobacter pylori Genome Project : insights into H. pylori population structure from analysis of a worldwide collection of complete genomes

Helicobacter pylori, a dominant member of the gastric microbiota, shares co-evolutionary history with humans. This has led to the development of genetically distinct H. pylori subpopulations associated with the geographic origin of the host and with differential gastric disease risk. Here, we provide insights into H. pylori population structure as a part of the Helicobacter pylori Genome Project (HpGP), a multi-disciplinary initiative aimed at elucidating H. pylori pathogenesis and identifying new therapeutic targets. We collected 1011 well-characterized clinical strains from 50 countries and generated high-quality genome sequences. We analysed core genome diversity and population structure of the HpGP dataset and 255 worldwide reference genomes to outline the ancestral contribution to Eurasian, African, and American populations. We found evidence of substantial contribution of population hpNorthAsia and subpopulation hspUral in Northern European H. pylori. The genomes of H. pylori isolated from northern and southern Indigenous Americans differed in that bacteria isolated in northern Indigenous communities were more similar to North Asian H. pylori while the southern had higher relatedness to hpEastAsia. Notably, we also found a highly clonal yet geographically dispersed North American subpopulation, which is negative for the cag pathogenicity island, and present in 7% of sequenced US genomes. We expect the HpGP dataset and the corresponding strains to become a major asset for H. pylori genomics

Poly(amidoamine)s with potential as drug carriers: degradation and cellular toxicity

Poly(amidoamine)s were synthesized by polyaddition reaction: to bis-acryloylpiperazine of piperazine (1), or N,N'-bis(2-hydroxyethyl)ethylenediamine (2), and to 2,2-bis(acrylamido)acetic acid of piperazine (3). Compound 2 was also end-capped with 4-hydroxythiophenol, thus introducing a terminal moiety suitable for radio-iodination using the chloramine T method (4). Such polymers behave as bases in aqueous solution, and their net average charge alters considerably as the pH changes from 7.4 to 5.5. This results in a change in polymer conformation which may prove useful in the design of polymeric drug delivery systems. However, their suitability for use in the organism will depend on polymer toxicity and also on their rate of biodegradation. Here we studied the biological properties of the above poly(amidoamine)s with a view to optimizing the synthesis of novel drug carriers. The general cytotoxicity of compounds 1, 2, 3, and 4 was examined in vitro using two human cell lines, hepatoma (HepG2) and a lymphoblastoid leukaemia (CCRF). Several different methods [the tetrazolium (MTT) test, [3H]leucine or [3H]thymidine incorporation, or counting cell numbers] were used to measure cell viability. Compounds 1, 2, and 4 were much less toxic to both cell lines than equivalent concentrations of the polycationic poly-L-lysine, and in no case did viability fall below 50% (concentrations up to 2 mg/ml). Although compound 2 was not markedly toxic to HepG2 cells, concentration-dependent toxicity was observed against CCRF cells. In this case, the polymer concentration decreasing viability by 59% (ID50) was approximately 50 micrograms/ml for compound 2 compared with an ID50 of approximately 10 micrograms/ml for poly-L-lysine. The rate of hydrolytic degradation of compound 2 was examined using viscometric measurements and gel permeation chromatography (GPC). After incubation at pH 7.5 and 8.0 for 24 h, polymer intrinsic viscosity was decreased by approximately 50% and GPC elution profiles showed a simultaneous increase in polymer retention time, indicating a fall in molecular weight. Hydrolytic degradation progressed much more slowly at pH 5.5. Compound 4 was also incubated with a mixture of isolated rat liver lysosomal enzymes (tritosomes) at pH 5.5, but no increase in the rate of degradation was observed