Search results for "microbiology"
showing 10 items of 7546 documents
Extinct type of human parvovirus B19 persists in tonsillar B cells
2017
Parvovirus B19 (B19V) DNA persists lifelong in human tissues, but the cell type harbouring it remains unclear. We here explore B19V DNA distribution in B, T and monocyte cell lineages of recently excised tonsillar tissues from 77 individuals with an age range of 2–69 years. We show that B19V DNA is most frequent and abundant among B cells, and within them we find a B19V genotype that vanished from circulation >40 years ago. Since re-infection or re-activation are unlikely with this virus type, this finding supports the maintenance of pathogen-specific humoral immune responses as a consequence of B-cell long-term survival rather than continuous replenishment of the memory pool. Moreover, we …
Activity of the α-glucoside transporter Agt1 in Saccharomyces cerevisiae cells during dehydration-rehydration events
2018
Microbial cells can enter a state of anhydrobiosis under desiccating conditions. One of the main determinants of viability during dehydration-rehydration cycles is structural integrity of the plasma membrane. Whereas much is known about phase transitions of the lipid bilayer, there is a paucity of information on changes in activity of plasma membrane proteins during dehydration-rehydration events. We selected the α-glucoside transporter Agt1 to gain insights into stress mechanisms/responses and ecophysiology during anhydrobiosis. As intracellular water content of S. cerevisiae strain 14 (a strain with moderate tolerance to dehydration-rehydration) was reduced to 1.5 g water/g dry weight, th…
Biotechnological impact of stress response on wine yeast.
2016
Wine yeast deals with many stress conditions during its biotechnological use. Biomass production and its dehydration produce major oxidative stress, while hyperosmotic shock, ethanol toxicity and starvation are relevant during grape juice fermentation. Most stress response mechanisms described in laboratory strains of Saccharomyces cerevisiae are useful for understanding the molecular machinery devoted to deal with harsh conditions during industrial wine yeast uses. However, the particularities of these strains themselves, and the media and conditions employed, need to be specifically looked at when studying protection mechanisms.
Oxidative stress in the oral cavity is driven by individualspecific bacterial communities
2018
The term “bacterial dysbiosis” is being used quite extensively in metagenomic studies, however, the identification of harmful bacteria often fails due to large overlap between the bacterial species found in healthy volunteers and patients. We hypothesized that the pathogenic oral bacteria are individual-specific and they correlate with oxidative stress markers in saliva which reflect the inflammatory processes in the oral cavity. Temporally direct and lagged correlations between the markers and bacterial taxa were computed individually for 26 volunteers who provided saliva samples during one month (21.2 ± 2.7 samples/volunteer, 551 samples in total). The volunteers’ microbiomes differed sig…
Anti-erosive effect of calcium carbonate suspensions
2018
Background This study aimed to investigate the ability of different concentrations of calcium carbonate (CaCO3) suspensions to control enamel surface loss. Material and methods Seventy-five enamel slabs were embedded, ground and polished in a pneumatic grinder-polisher machine. Reference areas were created with UPVC tape and the specimens were randomly allocated into five groups (n = 15) for exposure to hydrochloric acid solution to simulate gastric juice (0.01 M, pH 2) for 2 minutes. The samples were then exposed to suspensions containing 0.0001, 0.001, 0.01 or 0.1 mmol/L CaCO3 for 1 minute. Artificial saliva was used as control. The samples were subjected to a total of five erosive cycles…
The membrane-associated MUC1 improves adhesion of salivary MUC5B on buccal cells. Application to development of an in vitro cellular model of oral ep…
2015
Objectives: The mucosal pellicle is a thin layer of salivary proteins, mostly MUC5B mucins, anchored to epithelial oral cells. This pellicle is involved in protection of oral mucosae against abrasion, pathogenic microorganisms or chemical xenobiotics. The present study aimed at studying the involvement of MUC1 in mucosal pellicle formation and more specifically in salivary MUC5B binding using a cell-based model of oral epithelium. DESIGN: MUC1 mRNAs were not detected in TR146 cells, and therefore a stable cell line named TR146/MUC1 expressing this protein was developed by transfection. TR146 and TR146/MUC1 were incubated with human saliva in order to evaluate retention of MUC5B by epithelia…
Oral manifestations, salivary flow rates and Candida species in Thai HIV-infected patients
2019
Background Effects of various Highly Active Antiretroviral Therapy (HAART) regimens on oral heath are unclear. Objectives: We aimed to evaluate effects of HAART on oral manifestations, salivary flow rates (SFR) and Candida species in HIV-infected patients who took mostly non-protease inhibitor-based HAART regimens. Material and methods A cross-sectional study was performed on HIV-infected patients taking and never taken HAART who attended Thai Red Cross AIDS Research Centre (n = 48). Non-HIV subjects were recruited as control (n = 20). Oral conditions and salivary flow rates were evaluated using oral examination and measurement of unstimulated and stimulated saliva. In addition, Candida col…
Modeling the heat inactivation of foodborne pathogens in milk powder : High relevance of the substrate water activity
2017
International audience; Due to the ability of foodborne pathogens to survive in low moisture foods, the decontamination of these products is an important issue in food hygiene. Up to now, such decontamination has mostly been achieved through empirical methods. The intention of this work is to establish a more rational use of heat treatment cycles. The effects of thermal treatment cycles on the inactivation of dried Salmonella Typhimurium, Salmonella Senftenberg, Cronobacter sakazakii and Escherichia coli were assessed. Bacteria were mixed with whole milk powder and dried down to different water activity levels (0.11, 0.25, 0.44 and 0.58). The rate of inactivated bacteria was determined afte…
Retrospective study on the hygienic quality of fresh ricotta cheeses produced in Sicily, Italy
2018
The present work was carried out to investigate the microbiological profile of Sicilian ewes’ ricotta cheeses during fifteen years of investigations (2002-2016). The samples were collected between those conferred to the Istituto Zooprofilattico Sperimentale della Sicilia (IZSSi) Adelmo Mirri, Palermo (Italy), by the competent authority during official control, by food business operator in HACCP systems and in research projects. Enterobacteriaceae, Escherichia coli and coagulase-positive staphylococci (CPS) were found only in some samples. Bacillus cereus was detected in c.a. 16% of samples but the level of contaminations did not reach the threshold that leads to significant toxin production…
mcr-1- like detection in commensal Escherichia coli and Salmonella spp. from food-producing animals at slaughter in Europe
2017
International audience; We evaluate here the presence of the mcr-1-like and mcr-2 genes in Escherichia coli and Salmonella spp. isolated from healthy food-producing animals at slaughter between 2002 and 2014 in Europe. Isolates were retrieved from cattle, pig and chicken from 11 European countries of production. The susceptibility to colistin and antibiotics used in human medicine was determined by agar dilution. Colistin-resistant isolates were PCR-screened for mcr genes. mcr-positive isolates were typed by Pulsed-Field Gel Electrophoresis (PFGE) and Multi-Locus Sequence Typing. Among the 10,206 E. coli and 1774 Salmonella spp. isolated from cattle, pigs and chickens, 148 E. coli and 92 Sa…