Markov chain approach to analyze the dynamics of pathogen fecal shedding--example of Listeria monocytogenes shedding in a herd of dairy cattle

Fecal shedding is an important mechanism of spreading of a number of human and animal pathogens. Understanding of the dynamics of pathogen fecal shedding is critical to be able to control or prevent the spread of diseases caused by these pathogens. The objective of this study was to develop a model for analysis of the dynamics of pathogen fecal shedding. Fecal shedding of Listeria monocytogenes in dairy cattle was used as a model system. A Markov chain model (MCM) with two states, shedding and non-shedding, has been developed for overall L. monocytogenes fecal shedding (all L. monocytogenes subtypes) and fecal shedding of three L. monocytogenes subtypes (ribotypes 1058A, 1039E and 1042B) using data from one study farm. The matrices of conditional probabilities of transition between shedding and non-shedding states for different sets of covariates have been estimated by application of logistic regression. The covariate-specific matrices of conditional probabilities, describing the presence of different risk factors, were used to estimate (i) the stationary prevalence of dairy cows that shed any L. monocytogenes subtype or ribotypes 1058A, 1039E, and 1042B, (ii) the duration of overall and subtype specific fecal shedding, and (iii) the duration of periods without shedding. A non-homogeneous MCM was constructed to study how the prevalence of fecal shedders changes over time. The model was validated with data from the study farm and published literature. The results of our modeling work indicated that (i) the prevalence of L. monocytogenes fecal shedders varies over time and can be higher than 90%, (ii) L. monocytogenes subtypes exhibit different dynamics of fecal shedding, (iii) the dynamics of L. monocytogenes fecal shedding are highly associated with contamination of silage (fermented feed) and cows' exposure to stress, and (iv) the developed approach can be readily used to study the dynamics of fecal shedding in other pathogen-host-environment systems.     

Novel hydroxamic acid-related phosphinates: inhibition of neutral aminopeptidase N (APN)

Here we describe the inhibitory activity toward neutral aminopeptidase of three new families of phosphinate inhibitors related in structure to hydroxamic acids. These compounds, even as racemic mixtures, are good inhibitors of APN and show strong structure activity relationship (SAR) depending on the substituents in P1 and P1' positions.     

Physiology of temperature regulation: comparative aspects

Few environmental factors have a larger influence on animal energetics than temperature, a fact that makes thermoregulation a very important process for survival. In general, endothermic species, i.e., mammals and birds, maintain a constant body temperature (Tb) in fluctuating environmental temperatures using autonomic and behavioural mechanisms. Most of the knowledge on thermoregulatory physiology has emerged from studies using mammalian species, particularly rats. However, studies with all vertebrate groups are essential for a more complete understanding of the mechanisms involved in the regulation of Tb. Ectothermic vertebrates-fish, amphibians and reptiles-thermoregulate essentially by behavioural mechanisms. With few exceptions, both endotherms and ectotherms develop fever (a regulated increase in Tb) in response to exogenous pyrogens, and regulated hypothermia (anapyrexia) in response to hypoxia. This review focuses on the mechanisms, particularly neuromediators and regions in the central nervous system, involved in thermoregulation in vertebrates, in conditions of euthermia, fever and anapyrexia.     

Comparative studies on structure of the floral nectaries and the abundance of nectar production of Prunus laurocerasus L.

Protoplasma - There is very scanty information concerning the floral nectary structure and nectar secretion in Prunus laurocerasus L. Therefore, the aim of the study was to determine the...     

Derivatives of the cationic plant alkaloids berberine and palmatine amplify protonophorous activity of fatty acids in model membranes and mitochondria

Previously it has been shown by our group that berberine and palmatine, penetrating cations of plant origin, when conjugated with plastoquinone (SkQBerb and SkQPalm), can accumulate in isolated mitochondria or in mitochondria of living cells and effectively protect them from oxidative damage. In the present work, we demonstrate that SkQBerb, SkQPalm, and their analogs lacking the plastoquinone moiety (C₁₀Berb and C₁₀Palm) operate as mitochondria-targeted compounds facilitating protonophorous effect of free fatty acids. These compounds induce proton transport mediated by small concentrations of added fatty acids both in planar and liposomal model lipid membranes. In mitochondria, such an effect can be carried out by endogenous fatty acids and the adenine nucleotide translocase.     

Sex differences in motor characteristics of elementary school children included/not included in swimming training

The aim of the study was to assess the development of motor abilities in elementary school fifth- to eighth-graders (age 11-14 years) according to sex, age and physical activity. Study sample included 312 subjects divided according to age and sex into four groups: male subjects aged 11-12 (n = 93) and 13-14 years (n = 84); and female subjects aged 11-12 (n = 65) and 13-14 years (n = 70). Then, differences in basic motor abilities between children included (experimental group) and those not included (control group) in swimming training were analyzed. In male fifth- and sixth-graders, experimental group was superior to control group in the variables of trunk repetitive strength, sprint, flexibility and coordination, while in male seventh- and eighth-graders experimental group showed better performance than control group in agility, aerobic endurance and explosive throw and jump strength. In female fifth- and sixth-graders, experimental group proved superior to control group in the variables of explosive strength, coordination, trunk strength and aerobic endurance, whereas in female seventh- and eighth-graders experimental group had better performance in coordination, endurance, explosive strength, speed and flexibility. Discriminative analysis of motor variables between male and female subjects revealed male subjects to be superior in explosive strength, throw strength in particular, coordination and aerobic endurance, whereas female subjects showed better performance in the variables of flexibility and movement frequency, leg movement in particular. Study results showed the formation of appropriate motor system determining achievement of top results in swimming to be influenced by swimming training from age 11 to 14. In male children, motor system was found to integrate coordination/agility, aerobic endurance and explosive strength, whereas in female children it integrated coordination in terms of cortical movement regulation, aerobic endurance, explosive strength and psychomotor speed.     

Target of Rapamycin (TOR)-like 1 Kinase Is Involved in the Control of Polyphosphate Levels and Acidocalcisome Maintenance in Trypanosoma brucei

Target of rapamycin (TOR) kinases are highly conserved protein kinases that integrate signals from nutrients and growth factors to coordinate cell growth and cell cycle progression. It has been previously described that two TOR kinases control cell growth in the protozoan parasite Trypanosoma brucei, the causative agent of African trypanosomiasis. Here we studied an unusual TOR-like protein named TbTOR-like 1 containing a PDZ domain and found exclusively in kinetoplastids. TbTOR-like 1 localizes to unique cytosolic granules. After hyperosmotic stress, the localization of the protein shifts to the cell periphery, different from other organelle markers. Ablation of TbTOR-like 1 causes a progressive inhibition of cell proliferation, producing parasites accumulating in the S/G₂ phase of the cell cycle. TbTOR-like 1 knocked down cells have an increased area occupied by acidic vacuoles, known as acidocalcisomes, and are enriched in polyphosphate and pyrophosphate. These results suggest that TbTOR-like 1 might be involved in the control of acidocalcisome and polyphosphate metabolism in T. brucei.     

A Targeted LC‐MS Strategy for Low‐Abundant HLA Class‐I‐Presented Peptide Detection Identifies Novel Human Papillomavirus T‐Cell Epitopes

For rational design of therapeutic vaccines, detailed knowledge about target epitopes that are endogenously processed and truly presented on infected or transformed cells is essential. Many potential target epitopes (viral or mutation‐derived), are presented at low abundance. Therefore, direct detection of these peptides remains a challenge. This study presents a method for the isolation and LC‐MS³‐based targeted detection of low‐abundant human leukocyte antigen (HLA) class‐I‐presented peptides from transformed cells. Human papillomavirus (HPV) was used as a model system, as the HPV oncoproteins E6 and E7 are attractive therapeutic vaccination targets and expressed in all transformed cells, but present at low abundance due to viral immune evasion mechanisms. The presented approach included preselection of target antigen‐derived peptides by in silico predictions and in vitro binding assays. The peptide purification process was tailored to minimize contaminants after immunoprecipitation of HLA‐peptide complexes, while keeping high isolation yields of low‐abundant target peptides. The subsequent targeted LC‐MS³ detection allowed for increased sensitivity, which resulted in successful detection of the known HLA‐A2‐restricted epitope E7_11–19 and ten additional E7‐derived peptides on the surface of HPV16‐transformed cells. T‐cell reactivity was shown for all the 11 detected peptides in ELISpot assays, which shows that detection by our approach has high predictive value for immunogenicity. The presented strategy is suitable for validating even low‐abundant candidate epitopes to be true immunotherapy targets.