Short-chain fatty acids (SCFAs) are bacterial fermentation products, which are chemically composed by a carboxylic acid moiety and a small hydrocarbon chain. Among them, acetic, propionic and butyric acids are the most studied, presenting, respectively, two, three and four carbons in their chemical structure. These metabolites are found in high concentrations in the intestinal tract, from where they are uptaken by intestinal epithelial cells (IECs). The SCFAs are partially used as a source of ATP by these cells. In addition, these molecules act as a link between the microbiota and the immune system by modulating different aspects of IECs and leukocytes development, survival and function through activation of G protein coupled receptors (FFAR2, FFAR3, GPR109a and Olfr78) and by modulation of the activity of enzymes and transcription factors including the histone acetyltransferase and deacetylase and the hypoxia-inducible factor. Considering that, it is not a surprise, the fact that these molecules and/or their targets are suggested to have an important role in the maintenance of intestinal homeostasis and that changes in components of this system are associated with pathological conditions including inflammatory bowel disease, obesity and others. The aim of this review is to present a clear and updated description of the effects of the SCFAs derived from bacteria on host immune system, as well as the molecular mechanisms involved on them.

In the present paper, the adsorption of cysteine on hematite, magnetite and ferrihydrite was studied using FT-IR, electron paramagnetic resonance (EPR), Mössbauer spectroscopy and X-ray diffractometry. Cysteine was dissolved in artificial seawater (two different pHs) which contains the major constituents. There were two main findings described in this paper. First, after the cysteine adsorption, the FT-IR spectroscopy and X-ray diffractometry data showed the formation of cystine. Second, the Mössbauer spectroscopy did not show any increase in the amount of Fe(2+) as expected due the oxidation of cysteine to cystine. An explanation could be that Fe(2+) was oxidized by the oxygen present in the seawater or there occurred a reduction of cystine by Fe(2+) generating cysteine and Fe(3+). The specific surface area and pH at point of zero charge of the iron oxides were influenced by adsorption of cysteine. When compared to other iron oxides, ferrihydrite adsorbed significantly (p < 0.05) more cysteine. The pH has a significant (p < 0.05) effect only on cysteine adsorption on hematite. The FT-IR spectroscopy results showed that cystine remains adsorbed on the surface of the iron oxides even after being mixed with KCl and the amine and carboxylic groups are involved in this interaction. X-ray diffractometry showed no changes on iron oxides mineralogy and the following precipitated substances were found along with the iron oxides after drying the samples: cysteine, cystine and seawater salts. The EPR spectroscopy showed that cysteine interacts with iron oxides, changing the relative amounts of iron oxides and hydroxide.

Short-chain fatty acids (SCFAs), predominantly acetic, propionic, and butyric acids, are bacterial metabolites with an important role in the maintenance of homeostasis due to their metabolic and immunomodulatory actions. Some evidence suggests that they may also be relevant during infections. Therefore, we aimed to investigate the effects of SCFAs in the effector functions of neutrophils to an opportunistic pathogenic bacterium, Aggregatibacter actinomycetemcomitans. Using a subcutaneous model to generate a mono, isolated infection of A. actinomycetemcomitans, we demonstrated that the presence of the SCFAs in situ did not affect leukocyte accumulation but altered the effector mechanisms of migrating neutrophils by downregulating the production of cytokines, their phagocytic capacity, and killing the bacteria, thus impairing the containment of A. actinomycetemcomitans. Similar effects were observed with bacteria-stimulated neutrophils incubated with SCFAs in vitro. These effects were independent of free-fatty acid receptor 2 (FFAR2) activation, the main SCFA receptor expressed on neutrophils, occurring possibly through inhibition of histone deacetylases because similar effects were obtained by using histone deacetylase inhibitors, such as SAHA, MS-275, and RGFP 966. Considering the findings of this study, we hypothesized that in an infectious condition, SCFAs may exert a detrimental effect on the host by inhibiting neutrophil's effector functions.

We documented 4 cases of severe acute respiratory syndrome coronavirus 2 reinfection by non–variant of concern strains among healthcare workers in Campinas, Brazil. We isolated infectious particles from nasopharyngeal secretions during both infection episodes. Improved and continued protection measures are necessary to mitigate the risk for reinfection among healthcare workers.

RESUMO -Objetivou-se, com este trabalho, avaliar a produção e a composição do leite de éguas Mangalarga Marchador e o ganho de peso dos potros lactentes. A produção de leite foi avaliada em oito éguas, pelo método da pesagem dos potros antes e depois das mamadas, em intervalos de duas horas, em doze observações diárias. A partir do somatório da quantidade de leite produzido nas observações, obteve-se a produção diária de leite. A produção de leite, analisado quanto aos teores de lactose, proteína, gordura e energia, foi avaliada aos 20, 40, 60, 80, 100, 120, 140 e 160 dias da lactação A produção média de leite variou de 9,95 kg/dia no 40 o dia a 7,48 kg/dia no final da lactação. A produção total de leite estimada foi igual a 1405,56 kg. A produção de leite, expressa em percentual do peso vivo (PV) das éguas, variou entre 2,3% do PV no 20 o dia e 1,8% do PV no final da lactação, sendo similar às quantidades de leite produzidas nos períodos diurno e noturno. Não foi observado efeito da idade das éguas na produção de leite. O ganho médio diário de peso dos potros ao longo do período de amamentação foi de 0,77 kg, com maiores valores nos meses iniciais do período de amamentação. O leite das éguas apresentou baixas concentrações de proteína, gordura e energia e altas de lactose, além de resposta quadrática decrescente, em função do período da lactação. Palavras-chave: lactação, eqüinos, exigências nutricionais Lactation in Mangalarga Marchador Mares: Yield production and Composition of Milk, and Weight Gain of Suckling FoalsABSTRACT -This work aims to evaluate yield production and composition of milk of Mangalarga Marchador mares and average weight gain of suckling foals. Milk yield was evaluated in eight mares by the weigh-suck-weigh method, at intervals of two hour, twelve times a day. Daily milk produced was estimated by summing of the twelve observations. Milk yield was performed at 20, 40, 60, 80, 100, 120, 140 and 160 days of lactation. The milk was analyzed for lactose, protein, fat and energy concentration. Daily milk production ranged from 9.95 kg at 40 th day to 7.48 kg no final da lactação (160 th day) Total estimate milk yield during the lactation was 1405.56 kg. Milk yield as a % LW of mares ranged from 2.3% LW at 20 th day to 1.8% LW at the end of lactation. Amounts of milk produced during daytime and nighttime was similar and mare age did not affect milk production. Average weight gain of foals during lactation period was 0.77 kg/day with higher values at first months of lactation period. Milk showed low concentration of protein, fat and energy, high levels of lactose, with a decreasing quadratic response in function of lactation period.