Growth and enterotoxin A production by Staphylococcus aureus S6 in Manchego type cheese

(from cow, goat and sheep) was inoculated with Staphylococcus aureus strain S6, which is generally considered to be a strong enterotoxin B producer and a weak enterotoxin A producer. It was then used to make Manchego type cheese as prepared industrially. Two concentrations of starter culture (1% and 0.1%) were tested. Staphylococcal growth was good in both but better in the more dilute culture. Staphylococcal enterotoxin B was not detected at any stage of the ripening process of any cheese tested. However enterotoxin A was detected in both starter concentrations, reaching as high as 769 ng/100 g of cheese in the 0.1% starter batches.     

Twitching motility and biofilm formation are associated with tonB1 in Xylella fastidiosa

A mutation in the Xylella fastidiosa tonB1 gene resulted in loss of twitching motility and in significantly less biofilm formation as compared with a wild type. The altered motility and biofilm phenotypes were restored by complementation with a functional copy of the gene. The mutation affected virulence as measured by Pierce's disease symptoms on grapevines. The role of TonB1 in twitching and biofilm formation appears to be independent of the characteristic iron-uptake function of this protein. This is the first report demonstrating a functional role for a tonB homolog in X. fastidiosa .     

Changes in the number of leukocytes and lymphocyte subpopulations induced by exercise in sedentary young people

The influence of physical exercise on the quantification of leukocytes and lymphocyte subpopulations has been studied. These cells were obtained from blood taken from eleven healthy young men and women who follow a sedentary life style, before and after vigorous exercise (running). The results indicate that physical activity increases the number of white blood cells and the concentrations of circulating lymphocytes. The proportion of T-lymphocytes, estimated as rosette forming cells with sheep red blood cells after cold incubation, is constant, whereas a corresponding increase in cells with receptors for C3b or Ig-Fc is also observed. The data indicate that physical activity leads to an irregular intravascular discharge in stored cells.     

Recent developments in data acquisition,treatment and analysis with ion mobility-mass spectrometry for lipidomics

Lipids are involved in many biological processes and their study is constantly increasing. To identify a lipid among thousand requires of reliable methods and techniques. Ion Mobility (IM) can be coupled with Mass Spectrometry (MS) to increase analytical selectivity in lipid analysis of lipids. IM-MS has experienced an enormous development in several aspects, including instrumentation, sensitivity, amount of information collected and lipid identification capabilities. This review summarizes the latest developments in IM-MS analyses for lipidomics and focuses on the current acquisition modes in IM-MS, the approaches for the pre-treatment of the acquired data and the subsequent data analysis. Methods and tools for the calculation of Collision Cross Section (CCS) values of analytes are also reviewed. CCS values are commonly studied to support the identification of lipids, providing a quasi-orthogonal property that increases the confidence level in the annotation of compounds and can be matched in CCS databases. The information contained in this review might be of help to new users of IM-MS to decide the adequate instrumentation and software to perform IM-MS experiments for lipid analyses, but also for other experienced researchers that can reconsider their routines and protocols.     

Mannose toxicity in Ehrlich ascites tumor cells

Mannosephosphate isomerase (MPI) showed a higher activity than hexokinase (HKM) in its ability to phosphorylate mannose in the spleen, thymus, brain, liver, striated muscles, kidneys, and testes from BALB/c mice. This led to a HKM/MPI ratio of less than 1 in all the organs and tissues mentioned. In contrast, Ehrlich ascites tumor cells obtained from the peritoneum of BALB/c mice had low MPI activity (half of the HKM activity and, therefore, a ratio of 2). Mannose, which is nontoxic to nontumor cells at a concentration of 0.1 M, induced marked in vitro mortality of the tumor cells. Incubation of Ehrlich ascites tumor cells with mannose resulted in a high accumulation of mannose-6-phosphate and a marked depletion of ATP which did not appear when the cells were incubated with glucose. These facts may explain the selective mortality caused by mannose in the tumor cells studied.     

Soluble suppressor of T cell proliferation in primary in vitro response to murine minor histocompatibility antigens

Normal mouse lymphocytes are not capable of mounting a primary cytotoxic T cell response to Mls encoded, non H-2, allodeterminants, although a strong lymphoproliferative response is observed in primary MLR between Mls incompatible cells. In this study it is reported that in the supernatant of primary cultures between AKR macrophages and CBA/H lymphocytes (H-2 identical, incompatible for Mls and other minor antigens) a suppressor of T cell proliferation in MLR is detected. By contrast, a suppressor is not detected in supernatants from primary cultures between BALB/C macrophages and CBA/H lymphocytes (H-2 incompatible, Mls identical), B10.BR macrophages and CBA/H macrophages and CBA/H lymphocytes (syngeneic) suggesting that the production of the suppressor factor occurs only when an Mls incompatibility exists. The suppressive activity of the Mls incompatible culture supernatant upon MLR between incompatible macrophages and lymphocytes is neither antigen specific nor Mls or H-2 restricted, nor is it due to an irreversible toxic effect on T lymphocytes or macrophages. The inhibition of T cell proliferation could be explained by inhibition of IL 2 production, by blocking its union to T cells or by a combination of both effects. Our findings could help explain previous observations that lymphocytes from mice preimmunized with Mls incompatible cells have a depressed proliferative response as well as depressed cytotoxicity against alloantigens.     

Effects of physical exercise and aging on ascorbic acid and superoxide anion levels in peritoneal macrophages from mice and guinea pigs

The relationship of physical activity and aging, two processes with a high production of oxygen-free radicals to the ascorbate and superoxide anion (O ₂ ^- ) contents of peritoneal macrophages was studied in two animal species: guinea-pig (in which ascorbic acid is a vitamin) and mouse (in which ascorbic acid is not a vitamin). The effects of exhaustive exercise were examined in young and old animals. The results show that macrophages from old animals have a lower ascorbate content than those from young ones, whereas with exercise the ascorbate content increased in both old and young animals. This increase was higher in young than in old animals, and more evident in mice than in guinea-pigs. Aging also resulted in an increase in the O ₂ ^- levels of macrophages. With exercise these levels decreased in young mice but increased in young guinea-pigs. In old animals the exhaustive exercise did not change the O ₂ ^- levels. The results suggest in general a lack of correlation between the intracellular ascorbate and O ₂ ^- levels in relation to both physical exercise and aging.Abbreviations PBS phosphate buffered saline - NBT nitroblue tetrazolium - PEC peritoneal exudate cells - PMN polymorphonuclear