Effects of probiotic bacteria on diarrhea, lipid metabolism, and carcinogenesis: a review of papers published between 1988 and 1998.
(49/2732)
We reviewed the evidence from human intervention studies for the health effects of probiotic bacteria, ie, live bacteria that survive passage through the gastrointestinal tract and have beneficial effects on the host. Of the 49 studies reviewed, 26 dealt with the prevention or treatment of diarrheal disease, 9 with the prevention of cancer or of the formation of carcinogens, 7 with the lowering of serum cholesterol, and 7 with the stimulation of the immune system. The most widely studied probiotic bacteria were Lactobacillus GG (22 studies), Lactobacillus acidophilus (16 studies), Bifidobacterium bifidum (6 studies), and Enterococcus faecium (7 studies). Intake of Lactobacillus GG consistently shortened the diarrheal phase of rotavirus infection by 1 d. However, evidence for the prevention by Lactobacillus GG and other probiotics of diarrhea due to viral or bacterial infections was less strong. Effects of probiotics on the immune system are inconclusive because of the variety of outcome variables reported. Cholesterol lowering by L. acidophilus was shown in some but not all studies; cholesterol lowering by E. faecium seems to be transient. Two studies of one research group showed a smaller recurrence of bladder tumors in patients after treatment with Lactobacillus casei; these results await confirmation. The production of mutagens after a meal might be reduced by the concomitant intake of probiotics, but the relevance of this finding is unclear. In conclusion, consumption of foods containing Lactobacillus GG may shorten the course of rotavirus infection. Other health effects of probiotic bacteria have not been well established. Well-designed placebo-controlled studies with validated outcome variables are needed to determine the health effects of probiotics. (+info)
Modulatory effects of dietary lipids on immune system functions.
(50/2732)
Dietary lipid manipulation may affect a great number of immune parameters, such as lymphocyte proliferation, cytokine synthesis, natural killer (NK) cell activity, phagocytosis and so on. The immunomodulation induced by dietary fatty acids may be applied in the amelioration of inflammatory disorders, such as autoimmune diseases. However, the mechanisms that participate in these processes are still poorly understood. It is probable that modulation of immune system by fatty acids of the diet may occur by alteration of membrane fluidity, lipid peroxide formation, eicosanoid production or regulation of gene expression. However, recent studies have reported the effects of several free fatty acids on apoptosis induction of in vitro cultures. In fact, a possible explanation of the effects that fatty acids promote on the immune system cells could be associated with an apoptotic process performed in an irreversible way. In vivo studies have demonstrated the ability of fatty acids to alter the survival of animals fed diets containing oils and infected with a pathogenic bacterium. Experimental infection in animals fed dietary lipids produces a modification of resistance to micro-organisms. The present review analyses all of these parameters that dietary fatty acids are capable of altering in order to modify the immune response. Further studies will be needed to establish the mechanisms involved in immune system regulation, reduction of symptoms derived from autoimmune pathologies and so on. (+info)
Extracellular matrix moieties, cytokines, and enzymes: dynamic effects on immune cell behavior and inflammation.
(51/2732)
Tissue injury caused by infection or physical damage evokes inflammatory reactions and events that are necessary for regaining homeostasis. Central to these events is the translocation of leukocytes, including monocytes, neutrophils, and T lymphocytes, from the vascular system, through endothelium, and into the extracellular matrix (ECM) surrounding the injured tissue. This transition from the vasculature into the site of inflammation elicits remarkable changes in leukocyte behavior as cells adhere to and migrate across ECM before carrying out their effector functions. Growing evidence suggests that, through its interactions with cytokines and degradative enzymes, the ECM microenvironment has a specialized role in providing intrinsic signals for coordinating leukocyte actions. Recent advances also reveal that enzymatic modifications to ECM moieties and cytokines induce distinctive cellular responses, and are likely part of the mechanism regulating the perpetuation or arrest of inflammation. This article reviews the findings that have elucidated the dynamic relationships among these factors and how they communicate with immune cells during inflammation. (+info)
Molecular control of nitric oxide synthases in the cardiovascular system.
(52/2732)
Nitric oxide plays an important role in cardiovascular homeostasis. In this review, the regulation of the three nitric oxide synthase isoforms in the cardiovascular system are examined at molecular and cellular levels. In addition, recent information gleaned from the use of NOS knockout mice are discussed. (+info)
Environmental medicine, part one: the human burden of environmental toxins and their common health effects.
(53/2732)
Chemical compounds ubiquitous in our food, air, and water are now found in every person. The bioaccumulation of these compounds in some individuals can lead to a variety of metabolic and systemic dysfunctions, and in some cases outright disease states. The systems most affected by these xenobiotic compounds include the immune, neurological, and endocrine systems. Toxicity in these systems can lead to immune dysfunction, autoimmunity, asthma, allergies, cancers, cognitive deficit, mood changes, neurological illnesses, changes in libido, reproductive dysfunction, and glucose dysregulation. Chemicals and their effects on these systems are reviewed in this article. Subsequent articles in this series will focus on therapeutic regimens to combat the toxic effects of these and other compounds. (+info)
Genetics of mosquito vector competence.
(54/2732)
Mosquito-borne diseases are responsible for significant human morbidity and mortality throughout the world. Efforts to control mosquito-borne diseases have been impeded, in part, by the development of drug-resistant parasites, insecticide-resistant mosquitoes, and environmental concerns over the application of insecticides. Therefore, there is a need to develop novel disease control strategies that can complement or replace existing control methods. One such strategy is to generate pathogen-resistant mosquitoes from those that are susceptible. To this end, efforts have focused on isolating and characterizing genes that influence mosquito vector competence. It has been known for over 70 years that there is a genetic basis for the susceptibility of mosquitoes to parasites, but until the advent of powerful molecular biological tools and protocols, it was difficult to assess the interactions of pathogens with their host tissues within the mosquito at a molecular level. Moreover, it has been only recently that the molecular mechanisms responsible for pathogen destruction, such as melanotic encapsulation and immune peptide production, have been investigated. The molecular characterization of genes that influence vector competence is becoming routine, and with the development of the Sindbis virus transducing system, potential antipathogen genes now can be introduced into the mosquito and their effect on parasite development can be assessed in vivo. With the recent successes in the field of mosquito germ line transformation, it seems likely that the generation of a pathogen-resistant mosquito population from a susceptible population soon will become a reality. (+info)
Newer approaches in increasing life span.
(55/2732)
Based on ideal conditions technical life span of human kind is approximately 110-120 years. Although number of studies including calorie restriction and antiparkinsonism drug (deprenyl) have indicated increased life span in animals, it is premature to expect them to increase life span in man. However, current studies like activation of immune system with DHEA in man and anticipation of antioxidant therapy contributing to increased life span are encouraging. Practice of meditation particularly TM and balanced diet might be contributory. (+info)
Follicular hormonal environment and embryo quality in women with endometriosis.
(56/2732)
The use of in-vitro fertilization (IVF) as a therapeutic tool in patients with endometriosis has provided information about the disease and, in particular, aspects of the reproductive process in humans, particularly folliculogenesis, fertilization, embryo development and implantation. Retrospective analyses of IVF and oocyte donation programmes showed impaired implantation in patients with endometriosis. Otherwise, the observation that embryo development was blocked more frequently in cases of endometriosis, suggested that impaired embryo quality may be responsible for the reduced implantation rates. Similarly, women with the disease undergoing oocyte donation had the same chance of implantation as patients without endometriosis, suggesting that the endometrial milieu is not affected in patients with endometriosis. The quality of the oocyte may, therefore, be altered in patients with endometriosis. To investigate this, we studied steroid secretion in women undergoing IVF. Progesterone concentrations in follicular fluid increased with the severity of the disease and an increase in progesterone accumulation in vitro was observed in basal and human chorionic gonadotrophin (HCG)-induced granulosa cell cultures. We postulated that the pattern of progesterone secretion may be related to the release of cytokines by ovarian and/or immune cells. To test this, we measured interleukin (IL)-1, IL-6 and vascular endothelial growth factor (VEGF) concentrations in serum, follicular fluid and granulosa cell cultures. IL-6 concentrations in serum were increased in natural cycles in women with endometriosis and showed a significant decrease in stimulated cycles in IVF. Also, IL-6 concentrations were increased in the follicular fluid of women with endometriosis and released in higher amounts by granulosa-luteal cells from patients with endometriosis. VEGF was accumulated in lower concentrations in the follicular fluid of endometriosis patients. These observations show that the follicular environment is different in cases with endometriosis and suggest that infertility in patients with endometriosis may be related to alterations within the oocyte which, in turn, result in embryos of lower quality, and with a reduced ability to implant. (+info)