Echinacea plants as antioxidant and antibacterial agents: From traditional medicine to biotechnological applications

The genus Echinacea consists of 11 taxa of herbaceous and perennial flowering plants. In particular, Echinacea purpurea (L.) Moench is widely cultivated all over the United States, Canada, and in Europe, exclusively in Germany, for its beauty and reported medicinal properties. Echinacea extracts have been used traditionally as wound healing to improve the immune system and to treat respiratory symptoms caused by bacterial infections. Echinacea extracts have demonstrated antioxidant and antimicrobial activities, and to be safe. This survey aims at reviewing the medicinal properties of Echinacea species, their cultivation, chemical composition, and the potential uses of these plants as antioxidant and antibacterial agents in foods and in a clinical context. Moreover, the factors affecting the chemical composition of Echinacea spp. are also covered.

Modelling T-cell-mediated suppression dependent on interactions in multicellular conjugates

Tolerance to peripheral body antigens involves multiple mechanisms, namely T-cell-mediated suppression of potentially autoimmune cells. Recent in vivo and in vitro evidence indicates that regulatory T cells suppress the response of effector T cells by a mechanism that requires the simultaneous conjugation of regulatory and effector T cells with the same antigen-presenting cell (APC). Despite this strong requirement, it is not yet clear what happens while both cells are conjugated. Several hypotheses are discussed in the literature. Suppression may result from simple competition of regulatory and effector cells for activation resources on the APC; regulatory T cells may deliver an inhibitory signal to effector T cells in the same conjugate; or effector T cells may acquire the regulatory phenotype during their interaction with regulatory T cells. The present article tries to further our understanding of T-cell-mediated suppression, and to narrow-down the number of candidate mechanisms. We propose the first general formalism describing the formation of multicellular conjugates of T cells and APCs. Using this formalism we derive three particular models, representing alternative mechanisms of T-cell-mediated suppression. For each model, we make phase plane and bifurcation analysis, and identify their pros and cons in terms of the relationship with the large body of experimental observations on T-cell-mediated suppression. We argue that accounting for the quantitative details of adoptive transfers of tolerance requires models with bistable regimes in which either regulatory cells or effectors cells dominate the steady state. From this analysis, we conclude that the most plausible mechanism of T-cell-mediated suppression requires that regulatory T cells actively inhibit the growth of effector T cells, and that the maintenance of the population of regulatory T cells is dependent on the effector T cells. The regulatory T cell population may depend on a growth factor produced by effector T cells and/or on a continuous differentiation of effector cells to the regulatory phenotype.

Suitability of collagenase treatment for the radioautographic identification of newly synthesized collagen labeled with 3H-glycine or 3H-proline

Sections of Carnoy-fixed tissues from young rats and adult mice were incubated for 5 hr at 37°C in a 0.1% solution of Clostridium histolyticum collagenase purified by ion exchange chromatography. This treatment causes collagenous fibers as well as dentinal and bone matrices to lose their ability to stain red with the van Gieson technique and pink with eosin. In view of the high specificity of the enzyme, it is assumed that the stained component of these tissues is collagen. Immediately after injection of 3H-glycine or 3H-proline, radioautography shows the label in the cytoplasm of several cell types: osteoblasts of femur and alveolar bone, odontoblasts of growing molar and incisor teeth. and fibroblasts of the periodontal membrane. Later, the label appears outside the cells, that is, in bone matrix, dentinal matrix and intercellular spaces of periodontal membrane, respectively. Collagenase treatment extracts about half of the label which is present in the cells soon after injection, all or nearly all the label which appears later in bone and dentinal matrix, but only a fraction of that which appears in the intercellular spaces of the periodontal membrane. It is concluded that the radioactivity which occurs in osteoblasts, odontoblasts and some fibroblasts soon after injection of 3H-glycine and 3H-proline is composed in about equal parts of collagen and of other protein(s). In bone and dentinal matrix collagen alone seems to be deposited, whereas in the periodontal membrane collagen is laid down in association with other protein(s).

[An outbreak of acute schistosomiasis at Porto de Galinhas beach, Pernambuco, Brazil]

We recently confirmed several cases of acute schistosomiasis in Porto de Galinhas beach, Northeast Brazil. A total of 662 patients were diagnosed by parasitological and clinical examinations. The infection likely occurred during the September 7 national holiday, when heavy rainfall flooded the Ipojuca River and people were infected when the water covered their yards. Families were continuously exposed to infection for a period of three weeks until the water had completely dried up. Previous investigation suggests that snail vectors were introduced as a result of landfill in marshy areas. The swamp-flooding of such areas facilitated the emergence of slums surrounded by snail breeding sites. Heavy rainfall caused open-air sewage ditches to overflow, allowing for infection of snails by Schistosoma mansoni. Thus, continuous floods were responsible for the spread of human infection. Clinical and laboratory results identified 62% of acute cases of S. mansoni. Complementary studies are being conducted to define the impact and epidemiological meaning of the acute schistosomiasis outbreak.

A model of the immune network with B-T cell co-operation. I--Prototypical structures and dynamics

Hitherto, "second generation" network models of the immune system have all been restricted to B-lymphocytes and the Ig molecules they produce. These models have not so far been able to provide a convincing mechanism for the distinction between a "Central Immune System" (CIS) composed of a connected network of lymphocyte clones which couple with "self" antigens in a tolerant mode, and a "Peripheral Immune System" (PIS) composed of clones with little or no supra-clonal organization and which produce classical immune responses when interacting with "non-self" antigens. Here, we present a new network model which explicitly incorporates B-T cell co-operation. In this model, B-cell activation is dependent on T-cell help, and activated T-cells are down-regulated by engagement of their TCRs by soluble Ig. We discuss the underlying biology on which we base the system of ordinary differential equations which defines the present network model. We then illustrate some basic features of the model by examining several prototypical situations with a small number of clones. Depending on the idiotypic connectivity structure, the model exhibits two distinct modes of coupling with antigens: an "immune response" mode in which T- and B-cell clones grow exponentially; and a "tolerant" mode in which T-cell clones are controlled by inclusion of all TCRs in the repertoire of an idiotypic B-cell network. Finally, we discuss the simplifying assumptions of the present model and argue that its range of validity is indeed the region of the state-space of the system where the discrimination between the CIS and the PIS take place.

A mathematical analysis of TCR serial triggering and down-regulation

Despite the increasing knowledge on the pathways involved in TCR signal transduction and T cell activation, the molecular mechanism of TCR triggering by ligand, MHC-peptide complexes, is still elusive and controversial. The present paper addresses the controversy on the early events of TCR engagement and triggering. Mathematical modelling techniques are applied to experimental data to infer plausible molecular mechanisms of TCR triggering and down-regulation. A similar approach has been followed by Bachmann et al. (Eur. J. Immunol. 1998, 28: 2571 - 2579), who concluded that the TCR triggering requires the formation of MHC-TCR dimers or trimers. We report here the failure to generalize this conclusion to the data reported by Valitutti et al. (Nature 1995, 375: 148 - 151). We show that there are several kinetic features in these experimental curves of TCR down-regulation that cannot be explained by the simple model proposed by Bachmann et al. unless some phenomenological extensions are considered. These extensions are: (1) a ligand independent turnover of the TCR; (2) a transient accumulation of triggered TCR; (3) a high order of TCR triggering kinetics; and (4) two pools of membrane TCR in dynamic equilibrium.

Rethinking "shape space": evidence from simulated docking suggests that steric shape complementarity is not limiting for antibody-antigen recognition and idiotypic interactions

The concept of "shape space" is based on the assumption that the relevant properties of individual molecules can be adequately specified by a finite list of N parameters; and that cij, the affinity between molecules i and j, can be specified by an equation of the form: cij = f(xi, xj), where xi and xj are N-dimensional vectors representing the absolute positions of molecules i and j in an objective, referential "shape space", and f is an appropriate function. We have performed simulated docking of the combining sites of immunoglobulin molecules, based on their crystallographic structures. The results suggest that shape complementarity cannot account for the specificity of idiotypic interactions, since in the simulations each pair of docked proteins had a buried surface area as great as that occurring in known complexes. It therefore seems likely that the atomic interactions accounting for the specificity of immunoglobulin recognition are highly relational. This casts doubt on the basic assumptions underlying the shape-space concept, at least in the simple form hitherto used in theoretical modelling of the immune system. In order to be realistic, the dimensionality N would have to be high (more than 20), and the function f would be irregular and discontinuous. Alternatively, if the equation cij = f(xi, xj) is interpreted as a purely formal construction in an abstract "inversion space", its validity is entirely relative to the empirical affinity matrix on which the construction is based. We conclude that at present there is no sure way of adequately characterizing the internal structure of idiotypic affinity matrices; and that models of the immune system should therefore aim at being generic and robust with respect to the structure of the idiotypic affinity matrices of unselected immunoglobulins.

Astragalus species: Insights on its chemical composition toward pharmacological applications

Astragalus L. is widely distributed throughout the temperate regions of Europe, Asia, and North America. The genus is widely used in folk medicine and in dietary supplements, as well as in cosmetics, teas, coffee, vegetable gums, and as forage for animals. The major phytoconstituents of Astragalus species with beneficial properties are saponins, flavonoids, and polysaccharides. Astragalus extracts and their isolated components exhibited promising in vitro and in vivo biological activities, including antiaging, antiinfective, cytoprotective, antiinflammatory, antioxidant, antitumor, antidiabesity, and immune-enhancing properties. Considering their proven therapeutic potential, the aim of this work is to give a comprehensive summary of the Astragalus spp. and their active components, in an attempt to provide new insight for further clinical development of these xenobiotics. This is the first review that briefly describes their ethnopharmacology, composition, biological, and toxicological properties.

Three-cell interactions in T cell-mediated suppression? A mathematical analysis of its quantitative implications

Aiming to further our understanding of T cell-mediated suppression, we investigate the plausibility of the hypothesis that regulatory T cells suppress other T cells (target cells), while both cells are conjugated with one APC. We use a mathematical model to analyze the proliferation inhibition scored during in vitro suppression assays. This model is a radical simplification of cell culture reality, assuming that thymidine incorporation is proportional to the number of target cells that would instantaneously form conjugates with APCs that are free of regulatory cells. According to this model the inhibition index should be mainly determined by the number of regulatory cells per APC and should be insensitive to the number of target cells. We reanalyzed several published data sets, confirming this expectation. Furthermore, we demonstrate that the instantaneous inhibition index has an absolute limit as a function of the number of regulatory cells per APC. By calculating this limit we find that the model can explain the data under two non-mutually exclusive conditions. First, only approximately 15% of APCs used in the suppression assays form conjugates with T cells. Second, the growth of the regulatory cell population depends on the target cells, such that the number of regulatory cells per APC increases when they are cocultured with target cells and overcomes its limit. However, if neither of these testable conditions is fulfilled, then one could conclude that suppression in vitro does not require the formation of multicellular conjugates.

A model of the immune network with B-T cell co-operation. II--The simulation of ontogenesis

This paper is based on a new model of the immune network which explicitly incorporates B-T cell co-operation. A major feature of this model is the simplifying assumption that inhibition by anti-TCR soluble Ig is the only possible down-regulatory influence on activated T-cells. This model is capable of coupling with antigens in both an "immune response" mode and a "tolerant" mode. In the present paper, we simulate the ontogenesis of the immune system by metadynamical recruitment of T- and B-cell clones from the thymus and the bone marrow, seeking to identify the conditions under which each of these modes of antigen coupling occurs. Achieving the tolerant mode depends principally on four parameters: a high value of SB, the rate of bone-marrow production of B-cells; a relatively high efficiency of T-help through mIg-TCR recognition compared with (MHC + peptide)-TCR interaction; and a relatively high value of the product PR.NA, where PR is the average probability that an Ig recognizes another molecule and NA is the number of antigens which are present throughout ontogeny. Analysis of the conditions under which these two modes can coexist, shows that this is possible when a sufficiently numerous set of founder antigens couple in a tolerant mode, whereas isolated antigens first presented once development is completed couple in an immune response mode. The present model thus provides a possible mechanism for the distinction (hitherto purely descriptive) between a Central Immune System organized as a network and responsible for tolerance, and a Peripheral Immune System responsible for immune responses.

Mitochondrial lineages reveal intense gene flow between Iberian wild boars and South Iberian pig breeds

The phylogeography of wild boars (WB) and domestic pigs (Sus scrofa) has contributed important insights into where and when domestication occurred. The geographic distribution of two core haplotypes (E1a and E1c) of the main European phylogenetic clade suggests that Central Europe was an early domestication centre, although the complexity of the pattern does not exclude the possibility that multiple domestication events occurred in different regions. To investigate the relationships among WB and domestic pig breeds in Iberia, a fragment of the mitochondrial DNA control region from a large sample (n=409) of WB and local pig breeds was co-analysed with published sequences from other European populations. The Iberian sample revealed a high frequency of a sub-cluster (E1c) of the European haplogroup E1 in 77% of total Iberian samples, 96% of WB, 90% of Alentejano (Portugal) and 87% of Iberian breed pigs (Spain; Black Hairy, Black Hairless and Red varieties). Low genetic distance (F'(ST) = 0.105) was observed between Alentejano (Portugal) and Iberian breed pigs (Spain). Alentejano and Iberian breed pigs showed low genetic distances to both Iberian and Central European WB (average F'(ST) =0.345 and 0.215, respectively). This pattern suggests that early pig husbandry in the Iberian Peninsula did not solely rely on imported Central European stock, but also included the recruitment of local WB.

The ontogeny of class-regulation of CD4+ T lymphocyte populations

The differential class-regulation of CD4+ T lymphocyte populations is believed to play a major role in determining the qualitative behaviour of the immune system, and in the fate of immune responses in particular. In this article we propose a model for the dynamics of the Th1 and Th2 subpopulations. We put forward the concept of an 'antigenic niche' which allows us to postulate that the key feature underlying the regulation of Th differentiation pathways is the population dynamics of the lymphocytes themselves. Using this model we are able to account for a number of well established experimental observations which were hitherto apparently unrelated and poorly understood. This suggests that our simplified model might be capturing some essential features of the immune system.

Synthesis of ceramic pigments from industrial wastes: Red mud and electroplating sludge

The perception of industrial waste has changed, in the last decades, from an economic and environmental problem to a potential raw material. In this work, the synthesis of a stable pigment was prepared by combining two hazardous and unexplored wastes: red mud (RM, rich in Fe) and electroplating sludge (ES, rich in Ni/Cr). The wastes were mixed in different proportions and calcined at 1200 °C. Black and brown pigments were obtained from the mixture of RM/ES in 1:3 and 1:1 wt proportions, respectively. The color was given by the chrome-iron-nickel spinels, based on Ni^{2+ 3}T_1g(³F) transitions (≈13,000 cm^-1), Cr^{3+ 4}A_2g → ⁴T_1g(⁴F) transitions (≈24,400 cm^-1) and Fe³⁺ (≈15,000-≈22,500 cm^-1). The achieved coloring strength and thermal stability on various ceramic glazes render excellent prospects for the industrial application of such waste-based pigments.

Piper diospyrifolium Kunth.: Chemical analysis and antimicrobial (intrinsic and combined) activities

The secular use of plants in popular medicine has emerged as a source for the discovery of new compounds capable of curing infections. Among microbial resistance to commercial drugs, species such as Piper diospyrifolium Kunth, which are used in popular therapy, are targets for pharmacological studies. With this in mind, antimicrobial experiments with the essential oil from the P. diospyrifolium (PDEO) species were performed and its constituents were elucidated. The oil compounds were identified by gas chromatography coupled to mass spectrometry (GC/MS). The broth microdilution method with colorimetric readings for bacterial tests (Escherichia coli and Staphylococcus aureus) and spectrophotometric readings for fungal tests (Candida albicans and Candida tropicalis), whose data were used to create a cell viability curve and calculate its IC₅₀ against fungal cells, were used to determine the minimum inhibitory concentration of the oil and its combined action with commercial drugs. The oil's minimal fungicidal concentration and its action over fungal morphological transition were analyzed by subculture and microculture, respectively. Chemical analysis revealed Z-Carpacin, Pogostol and E-Caryophyllene as the most abundant compounds. Results from the intrinsic analysis were considered clinically irrelevant, however the oil presented a synergistic effect against multiresistant E. coli and S. aureus strains when associated with gentamicin, and against the standard and isolated C. tropicalis strains with fluconazole. A fungicidal effect was observed against the C. albicans isolate. Candida spp. hyphae inhibition was verified for all strains at the highest tested concentrations. The P. diospyrifolium essential oil presented a promising effect when associated with commercial drugs and against a fungal virulence factor. Thus, the oil presented active compounds which may help the development of new drugs, however, new studies are needed in order to clarify the oil's mechanism of action, as well as to identify its active constituents.

Bioactive Compounds as Potential Agents for Sexually Transmitted Diseases Management: A Review to Explore Molecular Mechanisms of Action

Sexually transmitted diseases (STDs) are produced by pathogens like bacteria, fungi, parasites, and viruses, and may generate severe health problems such as cancer, ulcers, and even problems in the newborn. This narrative review aims to present updated information about the use of natural bioactive compounds for the prevention and treatment of sexually transmitted infections. A search of the literature was performed using databases and search engines such as PubMed, Scopus, Google Scholar and Science Direct. From the pharmacotherapeutic management point of view, any strategies for prevention should contain medical approaches. The bioactive compounds obtained from natural products have shown biological effects against different microorganisms for the treatment of these diseases. The main results showed antimicrobial, antiprotozoal, antifungal and antiviral effects such as HIV. Also, the molecular mechanisms, signalling pathways and action targets of natural compounds were highlighted, thus justifying bacterial and antifungal inhibition, apoptosis or reduction of viral replication. From the data of our study, we can conclude that natural compounds may be a significant source for adjuvant drugs / complementary therapies in the treatment of STDs. With all these benefits, the future must conduct extensive clinical trials and the development of pharmaceutical nanotechnologies for a greater therapeutic effect.

Allelic penetrance approach as a tool to model two-locus interaction in complex binary traits

Many binary phenotypes do not follow a classical Mendelian inheritance pattern. Interaction between genetic and environmental factors is thought to contribute to the incomplete penetrance phenomena often observed in these complex binary traits. Several two-locus models for penetrance have been proposed to aid the genetic dissection of binary traits. Such models assume linear genetic effects of both loci in different mathematical scales of penetrance, resembling the analytical framework of quantitative traits. However, changes in phenotypic scale are difficult to envisage in binary traits and limited genetic interpretation is extractable from current modeling of penetrance. To overcome this limitation, we derived an allelic penetrance approach that attributes incomplete penetrance to the stochastic expression of the alleles controlling the phenotype, the genetic background and environmental factors. We applied this approach to formulate dominance and recessiveness in a single diallelic locus and to model different genetic mechanisms for the joint action of two diallelic loci. We fit the models to data on the genetic susceptibility of mice following infections with Listeria monocytogenes and Plasmodium berghei. These models gain in genetic interpretation, because they specify the alleles that are responsible for the genetic (inter)action and their genetic nature (dominant or recessive), and predict genotypic combinations determining the phenotype. Further, we show via computer simulations that the proposed models produce penetrance patterns not captured by traditional two-locus models. This approach provides a new analysis framework for dissecting mechanisms of interlocus joint action in binary traits using genetic crosses.

Natural and induced tolerance in an immune network model

It has been proposed that the immune system can be partitioned into central and peripheral immune systems. Recently, Carneiro et al. (1996a, b) proposed a network, model incorporating B and T lymphocytes that explicitly accounts for that partition. This model however, had some limitations that are tackled here. Two main changes were introduced: the average idiotypic connectivity is now an explicit function of time based on empirical evidence; and the activation of T lymphocytes by antigen is described by a log-bell shaped dose response curve. The new model, which also accounts for the CIS and PIS distinction, shows more reasonable results since the frequencies of tolerant, immune or autoimmune responses to an antigen are now correct. The model provides a new interpretation for tolerance induction during the neonatal period, and for the adult tolerance by low or high doses of antigen. It predicts that natural tolerance for antigens available during the neonatal period can be kept indefinitely upon their removal, while tolerance induced in the adult stages is rapidly lost upon transient removal of the antigen. A semiquantitative analysis of the model provides a simple explanation for the different results in terms of the frequency at which a limited set of canonical connectivity structures emerge during ontogenesis.

The effects of thalidomide treatment on autoimmune-prone NZB and MRL mice are consistent with stimulation of the central immune system

We describe here some immunomodulatory effects of thalidomide on autoimmune-prone mice. The highly increased synthesis of splenic IgM in NZB mice, of splenic and lymph node IgG of different subclasses in MRL/n mice, and of splenic and lymph node IgG1 in MRL/lpr mice was markedly inhibited by thalidomide treatment. After a single treatment with 3 mg of thalidomide, the following changes were observed in NZB mice: (i) an initial decrease in the numbers of large CD5+ microhigh, and in the numbers of total CD5+ micro-, CD5- microhigh, CD5+ microhigh lymphocyte populations of the pleural cavity followed by a late increase in the numbers of large cells of the three cell populations; (ii) a consistent increase in the numbers of a CD5low microlow pleural lymphoid population; (iii) a consistent reduction in the numbers of splenic large CD5+ B cells and an oscillatory increase in the number of cells with CD5- phenotype; (iv) a late reduction in the numbers of splenic total CD5+ B cells. These results are consistent with the notion that thalidomide controls a disease-associated expansion of B cells in autoimmune prone mouse strains through a stimulatory effect of the drug on the immune system.

Functional diversity of natural IgM

This paper proposes a method for the quantitative characterization of repertoire diversity of an unknown mixture of antibodies on the basis of its reactivity profile in the quantitative immunoblot (QIB). The QIB is calibrated by measuring the reactivity profiles of supernatants of known 'diversity' (i.e. known numbers of B cell clones). We define a quantitative 'index of variability' (IV) which decreases regularly as the diversity increases and the profiles tend towards a common 'convergence profile'. The calibration procedure is consolidated by a mathematical model based on the Poisson distribution; this theoretical model accounts correctly for the observed convergence behavior. On the basis of this calibration curve, it is possible to estimate the diversity of an unknown antibody mixture from a measure of its IV. We conclude that the functional diversity of natural serum IgM in mice can be estimated at approximately 16,000 clones.

[Prevalence of dyslipidemias in adults in laboratory tests from Salvador, Brazil]

PURPOSE

To determine the prevalence of dyslipidemia in non-hospital laboratory tests of adults from Salvador, Brazil.

METHODS

The study was carried out in subjects from a probabilistic sample of 25% of a total of 104 local laboratories that used the same enzymatic method for lipid analysis with the quality control as recommended by the Brazilian Society of Clinical Analyses. These represented 93% of all non-hospital laboratories of Salvador in 1995. The odd months of 1995 were selected for sampling in the present study. Criteria for dyslipidemias were: total cholesterol > or = 240; LDL > or = 160; HDL < 35 and triglycerides > or = 200 mg/dl. Prevalence rates and their 95% confidence intervals (CI) and chi 2 test were used in the analyses.

RESULTS

Tests from two of the 26 laboratories were not used in the analyses due to file problems or refusal. 7,392 adults were screened, 65% female. We observed prevalence (95% CI) of hypercholesterolemia in 30.0 (27.8; 32.2)%, high LDL in 30.1 (30.8; 35.4)% and hypertriglyceridemia in 30.4 (29.0; 31.4)% of the females. As to the male subjects, prevalences were; 24.0 (20.5; 27.5)% for hypercholesterolemia, 26.1 (22.4; 29.3)% for high LDL, 27.6 (25.7; 29.5)% for hypertriglyceridemia. All gender differences were significant. Low HDL occurred in 15.9 (14.2; 17.8)% of males and in 8.0 (7.1; 8.9)% of females.

CONCLUSION

Dyslipidemia is an important risk factor observed in non-hospital laboratory tests of men and women in Salvador. Our data may provide physicians and other health care professionals with objective information to encourage life-style changes.

A microparticle blood analogue suspension matching blood rheology

The handling of blood in vitro is demanding because of ethical, economical and safety issues. Although several Newtonian and non-Newtonian blood analogues are found in the literature, few studies have used particles to mimic red blood cells (RBCs) and built an analogue with similar rheological properties of blood. This work reports the development of a blood analogue suspension composed of polydimethylsiloxane (PDMS) microparticles with an average diameter of ∼7 μm. High throughput production of PDMS particles is possible using a multi-stage membrane emulsification process; up to ∼6 mL of microparticles are manufactured in 3 hours. PDMS particles at a concentration of around 21% (w/w) at 20 °C present steady, oscillatory and extensional rheologies very similar to those of blood under physiological conditions (37 °C and ∼41% hematocrit), making them a good candidate whole blood analogue. Also, flow studies were performed in microchannels with contraction to study the cell-free layer (CFL) formation and particle deformation, achieving good qualitative results. Using the procedure developed, it is possible to obtain blood analogue fluids with a shelf life of at least 6 months.