Role of Langerhans cells in the immunity of leishmaniasis

Immune response induced against Leishmania parasites is influenced by several factors, one of the most important being the type of Antigen Presenting Cell (APC). Langerhans cells, a subpopulation of APC, are sentinel cells for detecting invader microorganisms; they reside in skin tissues at levels where the phlebotomine fly vector inoculates Leishmania parasites. Presence of microorganisms can induce activation of Langerhans cells, leading to their maturation and migration towards lymph nodes. There, Langerhans cells present antigens to T cells for their subsequent activation and specific differentiation into effector cells. Early after a Leishmania infection, few T cells have been observed at sites of infection, suggesting that infected macrophages have little opportunity to locate T cells specific for elimination of Leishmania parasites. However, Langerhans cells may be the cells available to provide signals for the stimulation of parasite-specific T-cell responses in the lymph node and for inducing T-cell migration to the infected skin. Herein, the main characteristics of Langerhans cells are reviewed, with special emphasis on their participation in cutaneous inflammatory response. The role of these cells in infections caused by protozoan parasites of the Leishmania genus is discussed.     

UV-B treated algae exhibiting different responses as a food source for Daphnia magna

The response of green algae Scenedesmus quadricauda and Selenastrumcapricornutum to different levels of UV-B radiation was studied.Daphnia magna, the next step in the food web, was fed with UV-Btreated algae. UV-B radiation induced the synthesis of UV absorbingsubstances and photosynthetic pigments, enhanced the level ofrespiratory potential and suppressed growth of the treated algae.Biomass production in S. quadricauda was higher than in S. capricornutum,but the production of photosynthetic pigments and relative amountsof UV absorbing substances as well as respiratory potentialwere more pronounced in S. capricornutum. A short-term feedingexperiment with D. magna showed that in general, females ingestedhigher numbers of cells of algae treated with a high UV-B dose,but the biomass of ingested algae did not differ significantly.The exception was S. capricornutum treated with a high UV-Bdose; a lower biomass was ingested, probably reflecting thesmaller UV-treated cells.     

Liquid chromatographic assay for riluzole in mouse plasma and central nervous system tissues

An isocratic, reversed-phase high-performance liquid chromatographic procedure (HPLC) was developed for determination of the neuroprotective agent riluzole in mice plasma, brain and spinal cord. The procedure is based on isolation of the compound and the internal standard from plasma and central nervous system tissues using a Bakerbond spe C8 cartridge, with satisfactory recovery and specificity. Separation was on a C18 column, coupled with an UV detector at 263 nm. The assay was linear over a wide range, with a lower limit of quantification of 100 ng ml(-1) or g(-1) using 0.1 ml of plasma and about 100mg of brain tissue. The precision and accuracy were within the acceptable limits for an HPLC assay. The method is currently used to support pharmacological studies of the activity of riluzole when given in combination with other potential neuroprotective agents in an animal model of familiar amyotrophic lateral sclerosis (SOD1-G93A transgenic mice).     

Biological activities of organic compounds adsorbed onto ambient air particles: comparison between the cities of Teplice and Prague during the summer and winter seasons 2000-2001

The capital of the Czech Republic, Prague, appears today to be one of the most polluted residential areas in the country, whereas air pollution in the Northern Bohemia region (the former "Black Triangle Region") has substantially decreased during the last decade, especially with respect to the gaseous pollutant SO(2). This study evaluated the biological activities of complex mixtures of organic compounds adsorbed onto ambient air particles (PM10) collected during the summer and winter seasons of 2000-2001 at three monitoring sites--Teplice (TP), Prague-Smíchov (PRG-SM) (city centre) and Prague-Libus (PRG-LB) (suburban area). The following short-term in vitro assays with strikingly different endpoints were used: a bacterial mutagenicity test using the Salmonella typhimurium tester strain TA98 and YG1041, an acellular assay (CT DNA) combined with 32P-postlabelling to evaluate DNA adduct-forming potency and the chick embryotoxicity screening test (CHEST). The results of the mutagenicity test with the YG1041 strain, the acellular genotoxicity (DNA adducts) and the embryotoxicity tests responded to the amount of eight carcinogenic polycyclic aromatic hydrocarbons (PAHs) analysed in the EOM (dichloromethane extractable organic matter) samples tested. Nevertheless, the biological effects of the EOM did not differ between locations. The highest biological activity of the ambient air in terms of organic compounds associated with particles (per unit volume of air) was seen in the Prague city centre during both summer and winter seasons. At this location, B[a]P concentration ranged from 0.1 to 8.9 ng/m(3) (mean 0.3 and 3.6 ng/m(3) for summer and winter seasons, respectively), 13 PAHs ranged from 11 to 343 ng/m(3) (mean 52 and 160 ng/m(3) for summer and winter seasons, respectively). Generally, using in vitro tests, higher ambient air activity was found in the winter season as compared with the summer season at all three monitoring sites (TA98 +S9, approximately 4-fold; YG1041 -S9, approximately 5-fold; YG1041 +S9, approximately 8-fold; CT DNA +S9, approximately 10-fold; CHEST, approximately 10-fold; B[a]P, carcinogenic PAHs and total PAHs analysed, more than 10-fold). The different proportions of individual PAHs found in the summer and winter samples suggested traffic as a major emission source in the summer and, additionally, residential heating in the winter season at all three monitoring sites. The DNA adduct patterns resulting from the in vitro acellular assay also demonstrated similar major emission sources at all three locations. The study shows that particle-bound carcinogenic-PAH concentrations may be taken as an index for the biologically active (mutagenic, genotoxic, embryotoxic) components in air particulate samples. Therefore, high-quality monitoring data of carcinogenic PAHs may be useful for epidemiological studies of the impact of air pollution on the health of the population and for helping decision makers to improve our environment.     

Changes in midgut and brain proteins in Morimus funereus larvae depending on nutritive substrate

The response of Morimus funereus larvae to total starvation and refeeding with qualitatively different nutritive substrates (artificial diets supplemented with yeast as a source of B complex vitamins or with a digestibility reducer-tannic acid) was examined in this paper. Refeeding resulted in a compensatory increase of larval growth. Feeding and refeeding with qualitatively different nutritive substrates affected both quality and quantity of midgut and brain proteins. The observed differences suggest the possible switching of enzyme isoforms in M. funereus midgut and changes in synthesis/secretion of neurohormones, depending on food presence and its nutritional value.     

Prognostic value of cytokines in SIRS general medical patients

We studied 174 patients with SIRS criteria, 45 with sepsis, eight with severe sepsis and 13 with septic shock. Serum TNF-alpha, IL-6, IL-8 and IL-10 levels were raised in SIRS patients, even in those cases in which an infection could not be documented, and more intensely in severe sepsis and in patients who died (11%). The slope of the regression line between IL-10 and TNF-alpha was sharper in patients with severe sepsis and in those who died; an imbalance between pro- and anti-inflammatory cytokines may be related to poor prognosis. Increased IL-6 and IL-10, decreased muscle mass, raised BUN and low body temperature were all independently related to prognosis.     

ITS 2 sequences heterogeneity in Phlebotomus sergenti and Phlebotomus similis (Diptera,Psychodidae): possible consequences in their ability to transmit Leishmania tropica

An intraspecific study on Phlebotomus sergenti, the main and only proven vector of Leishmania tropica among the members of the subgenus Paraphlebotomus was performed. The internal transcribed spacer 2 (ITS2) sequences of 12 populations from 10 countries (Cyprus, Egypt, Italy, Lebanon, Morocco, Pakistan, Portugal, Spain, Syria, and Turkey) were compared. Samples also included three species closely related to P. sergenti: Phlebotomus similis (three populations from Greece and Malta), Phlebotomus jacusieli and Phlebotomus kazeruni. Our results confirm the validity of the taxa morphologically characterised, and imply the revision of their distribution areas, which are explained through biogeographical events. At the Miocene time, a migration route, north of the Paratethys sea would have been followed by P. similis to colonise the north of the Caucasus, Crimea, Balkans including Greece and its islands, and western Turkey. Phlebotomus sergenti would have followed an Asiatic dispersion as well as a western migration route south of the Tethys sea to colonise North Africa and western Europe. This hypothesis seems to be well supported by high degree of variation observed in the present study, which is not related to colonisation or to intra-populational variation. Two groups can be individualised, one oriental and one western in connection with ecology, host preferences and distribution of L. tropica. We hypothesise that they could be correlated with differences in vectorial capacities.     

Metabolic response of cerambycid beetle (Morimus funereus) larvae to starvation and food quality

The response of xylophagous Morimus funereus larvae to a direct change of diet demonstrated that the larvae from nutrient-poor substrates, e.g. oak, are very sensitive to such a change. Depending on dietary protein quality and quantity, an increase of proteolytic activity, i.e. an intensified protein metabolism accompanied by changes in body mass gain, was observed. At the same time, amylolytic activity was usually decreased. In the larvae reared on Robert's diet, sensitivity to the switch in diet was lower at the level of proteolytic enzymes that remained at the control level, while amylolytic activity was elevated. If the switch to a new diet was preceded by 7-day-starvation that disturbed nutritional homeostasis, the response of the larvae was similar to that recorded upon a direct switch only after short-term feeding (24 h) upon starvation. Differences in the response to changes in the diet of the larvae from nature, those reared under laboratory conditions and those of different physiological status could be ascribed to plasticity in the expression of the genes coding for proteases and their isoenzymes, as well as to the multi-functionality of some neurosecretory neurons, synthetic products that participate in the regulation of digestive enzyme activities.     

Experimental transmission of Leishmania tropica to hamsters and mice by the bite of Phlebotomus sergenti

Phlebotomus sergenti is a natural vector of Leishmania tropica. However, the ability of P. sergenti to transmit L. tropica by bite has not been proven experimentally yet. We have transmitted L. tropica to golden hamsters and BALB/c mice by the bite of P. sergenti. Sand flies and Leishmania both originated from an anthroponotic cutaneous leishmaniasis focus in Urfa, Turkey. P. sergenti females from a laboratory colony were infected by feeding on lesions of needle-inoculated hamsters or mice. Gravid females were allowed to refeed on uninfected hosts 9-15 d after the infective feeding. At the second feeding, some infected females took a full blood meal, while others only a partial one; some females failed to feed at all. The ability of infected females to take a blood meal did not correlate with the parasite transmissibility. In four BALB/c mice, lesions developed after 1-6 months. In two albino hamsters (Mesocricetus auratus), lesions developed 1 month after the infective feeding, and Leishmania could be reisolated from these sites. Another hamster did not develop a lesion; however, the feeding site and the adjacent ear were PCR positive 1 year after infective feeding. Our results show that dissemination to other parts of host body occurs in L. tropica after sand fly bite. Experimental transmission of the parasite confirms that P. sergenti is a natural vector of L. tropica.     

Coexistence of antibodies to tick-borne agents of babesiosis and Lyme borreliosis in patients from Cotia county,State of São Paulo,Brazil

This paper reports a case of coinfection caused by pathogens of Lyme disease and babesiosis in brothers. This was the first case of borreliosis in Brazil, acquired in Cotia County, State of S o Paulo, Brazil. Both children had tick bite history, presented erythema migrans, fever, arthralgia, mialgia, and developed positive serology (ELISA and Western-blotting) directed to Borrelia burgdorferi G 39/40 and Babesia bovis antigens, mainly of IgM class antibodies, suggestive of acute disease. Also, high frequencies of antibodies to B. bovis was observed in a group of 59 Brazilian patients with Lyme borreliosis (25.4%), when compared with that obtained in a normal control group (10.2%) (chi-square = 5.6; p < 0.05). Interestingly, both children presented the highest titers for IgM antibodies directed to both infective diseases, among all patients with Lyme borreliosis.