Differentiation of Trypanosoma cruzi epimastigotes: metacyclogenesis and adhesion to substrate are triggered by nutritional stress

Differentiation of Trypanosoma cruzi epimastigotes to metacyclic trypomastigotes occurs in the insect rectum, after adhesion of the epimastigotes to the intestinal wall. We investigated the effect of the nutritional stress on the metacyclogenesis process in vitro by incubating epimastigotes in the chemically defined TAU3AAG medium supplemented with different nutrients. Addition of fetal bovine serum induced epimastigote growth but inhibited metacyclogenesis. In this medium, few parasites attached to the substrate. Ultrastructural analysis demonstrated reservosomes at the posterior end of the epimastigotes. Incubation of the cells in TAU3AAG medium containing gold-labeled transferrin resulted in high endocytosis of the marker by both adhered and free-swimming epimastigotes. No intracellular gold particles could be detected in trypomastigotes. Addition of transferrin gold complexes to adhered epimastigotes cultivated for 4 days in TAU3AAG medium resulted in decrease of both metacyclogenesis and adhesion to the substrate, as compared with parasites maintained in transferrin-free medium. Adhesion to the substrate is triggered by nutritional stress, and proteins accumulated in reservosomes are used as energy source during the differentiation. A close relationship exists among nutritional stress, endocytosis of nutrients, adhesion to the substrate, and cell differentiation in T. cruzi epimastigotes.     

Defined Nutrient Diets Alter Susceptibility to Clostridium difficile Associated Disease in a Murine Model

BackgroundClostridium difficile is a major identifiable and treatable cause of antibiotic-associated diarrhea. Poor nutritional status contributes to mortality through weakened host defenses against various pathogens. The primary goal of this study was to assess the contribution of a reduced protein diet to the outcomes of C. difficile infection in a murine model.MethodsC57BL/6 mice were fed a traditional house chow or a defined diet with either 20% protein or 2% protein and infected with C. difficile strain VPI10463. Animals were monitored for disease severity, clostridial shedding and fecal toxin levels. Select intestinal microbiota were measured in stool and C. difficile growth and toxin production were quantified ex vivo in intestinal contents from untreated or antibiotic-treated mice fed with the different diets.ResultsC. difficile infected mice fed with defined diets, particularly (and unexpectedly) with protein deficient diet, had increased survival, decreased weight loss, and decreased overall disease severity. C. difficile shedding and toxin in the stool of the traditional diet group was increased compared with either defined diet 1 day post infection. Mice fed with traditional diet had an increased intestinal Firmicutes to Bacteroidetes ratio following antibiotic exposure compared with either a 2% or 20% protein defined nutrient diet. Ex vivo inoculation of cecal contents from antibiotic-treated mice showed decreased toxin production and C. difficile growth in both defined diets compared with a traditional diet.ConclusionsLow protein diets, and defined nutrient diets in general, were found to be protective against CDI in mice. Associated diet-induced alterations in intestinal microbiota may influence colonization resistance and clostridial toxin production in a defined nutrient diet compared to a traditional diet, leading to increased survival. However, mechanisms which led to survival differences between 2% and 20% protein defined nutrient diets need to be further elucidated.     

Health and nutritional benefits from lactic acid bacteria

Abstract There are several potential health or nutritional benefits possible from some species of lactic acid bacteria. Among these are: improved nutritional value of food, control of intestinal infections, improved digestion of lactose, control of some types of cancer, and control of serum cholesterol levels. Some potential benefits may result from growth and action of the bacteria during the manufacture of cultured foods. Some may result from growth and action of certain species of the lactic acid bacteria in the intestinal tract following ingestion of foods containing them. In selecting a culture to produce a specific benefit it is necessary to consider not only the wide variation among species of the lactic acid bacteria but also that among strains within a given species. With the possible exception of improving lactose utilization by persons who are lactose maldigestors, no specific health or nutritional claims can yet be made for the lactic acid bacteria.     

Health and nutritional benefits from lactic acid bacteria

There are several potential health or nutritional benefits possible from some species of lactic acid bacteria. Among these are: improved nutritional value of food, control of intestinal infections, improved digestion of lactose, control of some types of cancer, and control of serum cholesterol levels. Some potential benefits may result from growth and action of the bacteria during the manufacture of cultured foods. Some may result from growth and action of certain species of the lactic acid bacteria in the intestinal tract following ingestion of foods containing them. In selecting a culture to produce a specific benefit it is necessary to consider not only the wide variation among species of the lactic acid bacteria but also that among strains within a given species. With the possible exception of improving lactose utilization by persons who are lactose maldigestors, no specific health or nutritional claims can yet be made for the lactic acid bacteria.     

Prebiotics and lipid metabolism.

Prebiotics are defined as nondigestible food ingredients that beneficially affect the host by selectively stimulating the growth or the activity of one or a limited number of bacteria (bifidobacteria, lactobacilli) in the colon. Dietary fructans are nutritionally interesting oligosaccharides that strictly conform to the definition of prebiotics and (in view of experimental studies in animals and of less numerous studies in humans) exhibit interesting serum or hepatic lipid lowering properties. Other nondigestible/fermentable nutrients, which also modulate intestinal flora activity, exhibit cholesterol or triglyceride lowering effects. Are changes in intestinal bacterial flora composition or fermentation activity responsible for those effects? What is the future of prebiotics in the nutritional control of lipidaemia and cardiovascular disease risk in humans? Those questions only receive partial response in the present review because studies of the systemic effects of prebiotics are still in their infancy, and require fundamental research devoted to elucidating the biochemical and physiological events that allow prebiotics to exert systemic effects on lipid metabolism.     

Effects of Codonopis bulleynana forest ex diels on Deferribacteres in constipation predominant intestine tumor: Differential analysis

As a complicated micro-ecosystem, gut microbes are closely related to metabolic disease, immune disease and tumor (such as constipation. Long-term constipation would cause intestinal mucosal injury, enteritis, ileus, etc., thus inducing intestine cancer). In this research, intestine cancer model group and Codonopsis foetens treatment group were successfully constructed, and the variation of intestinal microbes were analyzed by 16S rRNA sequence. Results showed that there were changes in bacteria abundance of Firmicutes, Bacteroidetes, Proteobacteria, Deferribacteres, Tenericutes, and Actinobacteria, etc. Codonopsis foetens could directly or indirectly affect the growth and metabolism of Deferribacteres by altering the nutritional ingredient and pH value of intestine “medium”, thus affecting the occurrence and development of intestinal microbes.     

Beyond diversity: functional microbiomics of the human colon

Molecular tools have revealed wide microbial diversity in the human alimentary tract. Most intestinal microorganisms have not been cultured and the in situ functions of distinct groups of the intestinal microbiota are largely unknown but pivotal to understanding the role of these microorganisms in health and disease. Promising strategies to gain more insight into the functionality of the complex microbial communities in the human alimentary tract, including fermentation processes in the colon, are discussed. These research approaches could provide a basis for the definition of a healthy gut based on key properties of microbial functionality. This will also enable the development of direct nutritional strategies for intestinal disease prevention and health promotion.     

The nutritional dual-burden in developing countries--how is it assessed and what are the health implications?

This paper focuses on the phenomenon of the nutritional dual-burden in the developing world. Nutritional dual-burden is defined as the coexistence of under-and-over nutrition in the same population/group, the same household/family, or the same person. In this paper we aim: a) to describe the different types of nutritional dual-burden, b) to identify the anthropometric indicators generally used to classify the nutritional dual-burden, c) to focus our attention on a dual-burden group (the Maya from Merida, Yucatan, Mexico), d) to illustrate problems in the categorization of the dual-burden, and e) to suggest possible health implications. Our results show that, for our sample, the prevalence of individual dual-burden among children is very low, but is very high among the mothers and for mother-child pairs (household dual-burden). Most importantly, the criteria used to assess the nutritional status of the individuals and of the families will play an important role in the estimated prevalence of nutritional dual-burden, and this will have practical impacts for health intervention programs.     

Implications of parasite-nutrition interactions from a world perspective

Parasitic intestinal infections are among the most common in Africa, Asia, and Latin America. Although the mortality and morbidity caused by intestinal parasitic infections are relatively low, the absolute number of deaths and cases of disease is rather high in relation to other bacterial and viral infections. Scientific evidence for a causal relationship between intestinal parasitic infections and malnutrition is only fragmentary. The overdispersed frequency distribution of helminth parasites in the human population and the stability of giardiasis in some individuals may help only to define the potential target groups for immediate medical intervention, i.e., those patients heavily parasitized and/or severely malnourished. Long-term preventive intervention should include prenatal control of malnutrition, breast feeding and proper weaning food practices, oral rehydration for acute diarrhea, and immunization and possibly control of parasitic infections. Solid arguments in favor of the latter are expected to emerge from the field studies on intestinal parasitic infections and nutrition designed in 1981 by the World Health Organization and the United Nations Children's Emergency Fund. The results of these studies that will be carried out in several countries should serve as a guide for future parasite control projects and nutritional policies, including supplementary feeding programs.     

Ontogeny of intestinal nutrient transport

Children born prematurely lack the ability to digest and to absorb nutrients at rates compatible with their nutritional needs. As a result, total parenteral nutrition may need to be given. While this nutritional support may be lifesaving, the baby who receives this therapy is exposed to the risks of possible sepsis, catheter dysfunction, and liver disease. The rodent model of postnatal development provides a useful framework to investigate some of the cellular features of human intestinal development. The up-regulation of intestinal gene expression and precocious development of intestinal nutrient absorption can be achieved by providing growth factor(s) or by modifying the composition of the maternal diet during pregnancy and nursing or the weaning diet of the infant. Accelerating the digestive and absorptive functions of the intestine would thereby allow for the maintenance of infant nutrition through oral food intake, and might possibly eliminate the need for, and risks of, total parenteral nutrition. Accordingly, this review was undertaken to focus on the adaptive processes available to the intestine, to identify what might be the signals for and mechanisms of the modified nutrient absorption, and to speculate on approaches that need to be studied as means to possibly accelerate the adaptive processes in ways which would be beneficial to the newborn young.     

The gene encoding vasoactive intestinal peptide is located on human chromosome 6p21→6qter

Summary Vasoactive intestinal peptide (VIP) is a regulatory neuropeptide involved in a wide variety of functions, among them vasodilation, smooth muscle relaxation, sweat secretion, gastrointestinal peristalsis, and pancreatic function. A deficient VIP-innervation of sweat glands was recently described as a possible pathogenic factor in sweating of cystic fibrosis (CF) patients. To investigate a possible role for a defective VIP-gene in cystic fibrosis, we have used a panel of rodent-human hybrid cells, retaining defined complements of human chromosomes to localize the VIP-gene to the human chromosome region 6p216qter. As the CF gene was recently mapped to chromosome 7, we conclude that the VIP-gene is not the primary gene defect in this disease.     

Malnutrition and its association with intestinal parasitism among children from a village in the Colombian Amazonian region

Intestinal parasites and malnutrition cause high morbidity among children in developing countries. A study to establish the associations between intestinal parasitism and undernourishment was undertaken in a village in the Colombian Amazon region. Two hundred thirty seven children each provided four stool samples for parasitic analysis. Anthropometric indices were calculated based on height and weight (HAZ), weight and age (WAZ) and height and weight (WHZ) using the international growth standards recommended by the World Health Organization. Of the 237 children, 86.1% were carrying parasites, 54% had 2 or more parasites, 30% were stunted, 10% were underweight, and 2.5% were wasting. HAZ and WAZ indices were inversely related to age and number of parasites. Socioeconomic status was positively correlated with the number of parasites and inversely related to the HAZ index (p < 0.05). In conclusion, frequencies of undernourishment and intestinal parasites among the sample population were higher than the national average for Colombia. As previous studies have indicated, age, intestinal parasitism and socio-economic level are variables significantly related to nutritional state.     

益生菌在炎症性肠病治疗中的研究进展

益生菌（Probiotics）是一类能够促进肠道微生物菌群平衡,对宿主健康或生理功能产生有益作用的活性微生物。目前广泛应用于生命健康领域、科学研究、生物工程、工农业以及食品安全。大量国内外研究表明益生菌在降血压、降血糖、降血脂、抗过敏、抗炎、调节免疫、维持肠道菌群平衡等方面具有积极作用。炎症性肠病的病因和发病机制尚未完全明确,现多认为与遗传、环境、感染、免疫以及肠道微生物多因素相互作用有关。益生菌通过多种机制介导,在临床治疗炎症性肠病中扮演着重要角色。     

Health and disease: Exploring the relation between parasitic infections,child nutrition status,and markets

Research in bioarchaeology and among living people provides insight into the biological and biocultural consequences of subsistence, political, and economic transitions. Central to this effort is examining infectious disease, such as diarrheal disease, respiratory infections, and parasitic infections because they are an important source of nutritional and energetic stress in both past and current groups. Although infection may not always result in overt disease, frequent exposure results in biological stress with a negative effect on child growth and, by extension, health. The goal of this article is to examine the association between a common class of infectious disease, soil-transmitted helminth worms, and nutritional status among youth living in communities that vary with respect to their distance from a commercial center. In 2007, anthropometric measurements and parasitological surveys were collected for 338 2–14-year-old children and adolescents living in lowland Bolivia as part of the Tsimane' Amazonian Panel Study. Associations between the presence of helminth infections and markers of both short- and long-term nutritional status were overall weak. Youth living in communities distant from the commercial center were more likely to be positive for multiple parasite species than youth in near communities, but youth in mid-distance communities had lower infection rates. This article demonstrates the challenge of identifying associations between nutritional and disease stress when individual and household factors are nested in a larger context of socioeconomic and environmental change. Increased collaboration between bioarchaeology and human biology should continue to examine the connections between stress and disease across time. Am J Phys Anthropol 155:221–228, 2014. © 2014 Wiley Periodicals, Inc.     

Mucosal epithelium in health and disease

The intestinal epithelium has emerged as one of the links between the innate and adaptive immune systems. Novel roles have been elucidated for its participation in antigen uptake and presentation, costimulatory signaling, and intestinal homeostasis. Its concomitant interaction with immune cells and commensal flora demonstrates the epithelium's multifaceted responsibility in protecting against intestinal pathology while maintaining immune competence. Its functional capacity is now more clearly defined in disease states such as celiac disease, Crohn's disease, and ulcerative colitis and in maintaining intestinal integrity through toll-like receptor signaling pathways.     

后生元(postbiotics):调节肝硬化患者肠道菌群及疾病进程的新策略

肝硬化是慢性肝炎发展的终末阶段,患者出现有不同程度的肠道菌群失调,并伴有肠道屏障功能的缺失和菌群移位,是引发肝硬化并发症的重要原因。尽管益生菌能在多个层面保护肠道屏障功能,但其在肝硬化肠道菌群紊乱中的疗效并不明确。现在的研究发现一些益生菌的组分或代谢产物有着与益生活菌类似的益生功效,包括稳定肠道菌群、加强肠上皮屏障功能和调节肠黏膜免疫反应等,其重要的优点是具有明确的分子结构和显著的生物活性,可能是未来调节肝硬化肠道菌群及疾病进程的新方向。本文主要总结了肝硬化肠道菌群失调对于肝硬化并发症及疾病进程的影响,探讨了益生菌的作用及局限性,并重点讨论后生元在调控肝硬化肠道菌群及疾病进程中的应用前景。     

Functional amino acids in nutrition and health

The recent years have witnessed growing interest in biochemistry, physiology and nutrition of amino acids (AA) in growth, health and disease of humans and other animals. This results from the discoveries of AA in cell signaling involving protein kinases, G protein-coupled receptors, and gaseous molecules (i.e., NO, CO and H₂S). In addition, nutritional studies have shown that dietary supplementation with several AA (e.g., arginine, glutamine, glutamate, leucine, and proline) modulates gene expression, enhances growth of the small intestine and skeletal muscle, or reduces excessive body fat. These seminal findings led to the new concept of functional AA, which are defined as those AA that participate in and regulate key metabolic pathways to improve health, survival, growth, development, lactation, and reproduction of the organisms. Functional AA hold great promise in prevention and treatment of metabolic diseases (e.g., obesity, diabetes, and cardiovascular disorders), intrauterine growth restriction, infertility, intestinal and neurological dysfunction, and infectious disease (including viral infections).     

双歧杆菌四联活菌片 对重症脑卒中患者肠道功能的影响

目的探讨双歧杆菌四联活菌片对重症脑卒中患者肠道菌群及肠黏膜屏障功能的影响。方法选择重庆市人民医院2017年1月至2017年11月收治的100例重症脑卒中患者,随机将入选患者分为治疗组和对照组各50例。治疗组在常规肠内营养(EN)治疗基础上联用双歧杆菌四联活菌片治疗,对照组给予常规EN治疗。比较两组患者治疗前后营养状况、肠道菌群数量和肠黏膜屏障功能。比较两组患者治疗后消化道并发症发生率。结果治疗前,两组患者营养状况、肠道菌群数量和肠黏膜屏障功能差异无统计学意义(P0.05)。治疗后,两组患者营养状况指标白蛋白(ALB)、血红蛋白(Hb)和三头肌肌围(MAMC)水平,肠道有益菌(双歧杆菌、乳杆菌和拟杆菌)数量均有所上升,肠黏膜屏障功能指标二胺氧化酶(DAO)、D-乳酸水平及肠道有害菌数量(小梭菌和肠球菌)均降低。与对照组相比,治疗组患者ALB、Hb和MAMC水平,肠道双歧杆菌、乳杆菌和拟杆菌数量均显著升高,DAO、D-乳酸水平和小梭菌、肠球菌数量均显著降低,差异有统计学意义(P0.05)。治疗组患者消化道并发症发生率均低于对照组(P0.05)。结论双歧杆菌四联活菌片能够显著改善脑卒中患者的营养状况,有效调节菌群失衡,改善肠黏膜屏障功能,降低并发症发生。