Consumption of sugar-sweetened soft drinks and risk of metabolic syndrome and its components: results of the ELSA-Brasil study (2008-2010 and 2012-2014).

AIM: To estimate the association between consumption of sugar-sweetened soft drinks and unsweetened fruit juice with metabolic syndrome (MetS) and its components in participants of the Brazilian Longitudinal Adult Health Study (ELSA-Brasil) after 4 years of follow-up. METHODS: We used data from ELSA-Brasil cohort (N = 15,105). The sample consisted of 6,124 civil servants free of the MetS at baseline (35 to 74 years, both sexes). The consumption of sugar-sweetened soft drinks and unsweetened fruit juice was estimated by a food frequency questionnaire previously validated. The outcome was MetS and its components (Joint Interim Statement criteria). To test the association between beverage consumption at baseline (2008-2010) and MetS and its components at follow-up (2012-2014), we used Poisson regression models with robust variance adjusting for potential confounders. RESULTS: After 4-year follow-up, the higher consumption of sugar-sweetened soft drinks (≥ 1 serving/day = 250 mL/day) increased the relative risk of MetS (RR = 1.22; 95% CI 1.04-1.45), high fasting glucose (RR = 1.23; 95% CI 1.01-1.48), and high blood pressure (RR = 1.23; 95% CI 1.00-1.54). Moderate consumption of this beverage (0.4 to < 1 serving/day) increased the relative risk of high waist circumference (WC) (RR = 1.21; 95% CI 1.02-1.42). After adjustment for confounding variables, the consumption of unsweetened fruit juice was not associated with the MetS and its components. CONCLUSION: Higher sugar-sweetened soft drinks consumption was associated with a higher risk relative of MetS, high fasting glucose, and high blood pressure, while moderate consumption of this beverage increased the relative risk of high WC in Brazilian adults.

In situ experiment to evaluate biochemical responses in the freshwater mussel Diplodon chilensis under anthropogenic eutrophication conditions.

An in-situ experiment was performed to study metabolic responses of the freshwater mussel Diplodon chilensis to water contaminated by leachates from an open dump and cattle activity, in order to analyze both the effects of those contaminants on aquatic environments and the potential use of a native bivalve to evaluate the effects of anthropic influence and eutrophication. Bivalves from a reference site were cage-transplanted to a control site (site A) and to a temporal water pond (site B) over 30 and 60 periods. Water quality analyses revealed that the site B was affected by anthropogenic influence. Mussel's hemocytes from site B showed 50% lower reactive oxygen species production and 130% higher lysosomal membrane stability in the site B mussels. In addition, no oxidative stress was evident in gills, despite the elevated copper and iron concentrations recorded in the site B water samples (CuB = 0.3350 ± 0.0636 mg. L-1vs. CuA = 0.0045 ± 0.0007 mg. L-1; FeB = 3.8650 ± 0.4031 mg. L-1vs. FeA = 0.0365 ± 0.0049 mg. L-1). In contrast, the adductor muscle accumulated more Fe (~10-20-fold) than the gills and showed signs of oxidative stress, e.g. superoxide dismutase activity and TBARS levels were increased by 10% were 34%, respectively, in the site B compared with the site A after 60 days of exposure. Additionally, the adductor muscle showed signs of anaerobic metabolism activation. Cu is accumulated in gills from both sites' individuals, at 60 days, in concordance with the increase in the activity of the cu-containing enzyme cytochrome-c-oxidase. There was a reduction in the overall condition and digestive gland index in bivalves exposed at site B, associated with diminished levels of lipid and protein contents. Metal-pollution and eutrophication affects D. chilensis metabolism and is associated to tissue-specific exposure, anaerobic metabolism and general energetic condition depletion.

A case study on the re-establishment of the cyanolichen symbiosis: where do the compatible photobionts come from?

BACKGROUND AND AIMS: In order to re-establish lichen symbiosis, fungal spores must first germinate and then associate with a compatible photobiont. To detect possible establishment limitations in a sexually reproducing cyanolichen species, we studied ascospore germination, photobiont growth and photobiont association patterns in Pectenia plumbea. METHODS: Germination tests were made with ascospores from 500 apothecia under different treatments, and photobiont growth was analysed in 192 isolates obtained from 24 thalli. We determined the genotype identity [tRNALeu (UAA) intron] of the Nostoc cyanobionts from 30 P. plumbea thalli from one population. We also sequenced cyanobionts of 41 specimens of other cyanolichen species and 58 Nostoc free-living colonies cultured from the bark substrate. KEY RESULTS: Not a single fungal ascospore germinated and none of the photobiont isolates produced motile hormogonia. Genetic analyses revealed that P. plumbea shares Nostoc genotypes with two other cyanolichen species of the same habitat, but these photobionts were hardly present in the bark substrate. CONCLUSIONS: Due to the inability of both symbionts to thrive independently, the establishment of P. plumbea seems to depend on Dendriscocaulon umhausense, the only cyanolichen species in the same habitat that reproduces asexually and acts as a source of appropriate cyanobionts. This provides support to the hypothesis about facilitation among lichens.

Improved robustness of an ethanologenic yeast strain through adaptive evolution in acetic acid is associated with its enzymatic antioxidant ability.

AIMS: To investigate multiple tolerance of Saccharomyces cerevisiae obtained through a laboratory strategy of adaptive evolution in acetic acid, its relation with enzymatic ROS detoxification and bioethanol 2G production. METHODS AND RESULTS: After adaptive evolution in acetic acid, a clone (Y8A) was selected for its tolerance to high acetic acid concentrations (13 g l-1 ) in batch cultures. Y8A was resistant to multiple stresses: osmotic, thermic, oxidative, saline, ethanol, organic acid, phenolic compounds and slow freeze-thawing cycles. Also, Y8A was able to maintain redox homeostasis under oxidative stress, whereas the isogenic parental strain (Y8) could not, indicating higher basal activity levels of antioxidative enzyme Catalase (CAT) and Gluthatione S-transferase (GST) in Y8A. Y8A reached higher bioethanol levels in a fermentation medium containing up to 8 g l-1 of acetic acid when compared to parental strain Y8. CONCLUSIONS: A multiple-stress-tolerant clone was obtained using adaptive evolution in acetic acid. Stress cross-tolerance could be explained by its enzymatic antioxidative capacity, namely CAT and GST. SIGNIFICANCE AND IMPACT OF THE STUDY: We demonstrate that adaptive evolution used in S. cerevisiae was a useful strategy to obtain a yeast clone tolerant to multiple stresses. At the same time, our findings support the idea that tolerance to oxidative stress is the common basis for stress cotolerance, which is related to an increase in the specific enzymes CAT and GST but not in Superoxide dismutase, emphasizing the fact that detoxification of H2 O2 and not O2 ˙ is a key condition for multiple stress tolerance in S. cerevisiae.

Trace metals and oxidative status in soft tissues of caged mussels (Aulacomya atra) on the North Patagonian coastline.

This study investigated metal accumulation and oxidative effects in mantle, gill and digestive gland of the ribbed mussel Aulacomya atra from the Argentinean North Patagonian coastline. Mussels were transplanted over an 18-month period from a site with low anthropogenic impact to a harbor site with higher seawater concentration of aluminum, chromium, copper, manganese, nickel and zinc. Total trace metal concentration in seawater did not change throughout the 18-month transplant in either site. A. atra bioaccumulated metals in digestive gland, gills and mantle at different levels. Digestive gland had the highest concentration of metals, especially towards the end of the transplant experiment in the harbor area. Mussels transplanted to the harbor site experienced an upregulation in their antioxidant system, which likely explains the lack of oxidative damage to lipids despite higher metal accumulation. These results demonstrate that A. atra selectively accumulates metals from the water column and their prooxidant effects depend on the tissue antioxidant defenses and the exposure time.

Effects of glyphosate on growth rate, metabolic rate and energy reserves of early juvenile crayfish, Cherax quadricarinatus M.

Early juveniles of the crayfish Cherax quadricarinatus were exposed for 60 days to 10 and 40 mg/L of pure glyphosate (acid form) in freshwater. Mortality was 33 % at the highest concentration, while no differences in molting were noted among treatments. After the first month of exposure, weight gain was significantly (p < 0.05) reduced in the 40 mg/L group. At the end of the assay, lipid levels in muscle, as well as protein level in both hepatopancreas and muscle were significantly (p < 0.05) reduced. These results suggest long-term utilization of both lipid and protein as main energetic reserves, likely in response to the chronic stress associated with herbicide exposure. Besides, the lower pyruvate kinase activity in muscle suggests a possible metabolic depression in this tissue. The hemolymphatic ASAT:ALAT ratio showed higher levels than the control at the highest glyphosate concentration, indicating possible damage to several tissues.

Effect of interleukin-6 receptor blockade on the balance between regulatory T cells and T helper type 17 cells in rheumatoid arthritis patients.

A new paradigm has emerged relating the pathogenesis of rheumatoid arthritis (RA), focused on the balance between T helper type 17 cells and regulatory T cells (T(regs) ). In humans, both subpopulations depend on transforming growth factor (TGF)-ß for their induction, but in the presence of inflammatory cytokines, such as interleukin (IL)-6, the generation of Th17 is favoured. Tocilizumab is a therapeutic antibody targeting the IL-6 receptor (IL-6R), which has demonstrated encouraging results in RA. The aim of this study was to evaluate the effect of tocilizumab on Th1 cells, Th17 cells, IL-17 and interferon (IFN)-γ double secretors Th17/Th1 cells, and T(regs) in RA patients. Eight RA patients received tocilizumab monthly for 24 weeks and blood samples were obtained every 8 weeks to study T cell populations by flow cytometry. The frequency of Th17 cells, Th1 cells and Th17/Th1 cells was evaluated in peripheral blood mononuclear cells (PBMCs) activated in vitro with a polyclonal stimulus. T(regs) were identified by their expression of forkhead box protein 3 (FoxP3) and CD25 by direct staining of PBMCs. Although no changes were detected in the frequency of Th1 or Th17 cells, the percentages of peripheral T(regs) increased after therapy. In addition, the infrequent Th17/Th1 subpopulation showed a significant increment in tocilizumab-treated patients. In conclusion, tocilizumab was able to skew the balance between Th17 cells and T(regs) towards a more protective status, which may contribute to the clinical improvement observed in RA patients.

Identification of a novel water-soluble activator of wild-type and F508del CFTR: GPact-11a.

One of the major therapeutic strategy in cystic fibrosis aims at developing modulators of cystic fibrosis transmembrane conductance regulator (CFTR) channels. We recently discovered methylglyoxal alpha-aminoazaheterocycle adducts, as a new family of CFTR inhibitors. In a structure-activity relationship study, we have now identified GPact-11a, a compound able not to inhibit but to activate CFTR. Here, we present the effect of GPact-11a on CFTR activity using in vitro (iodide efflux, fluorescence imaging and patch-clamp recordings), ex vivo (short-circuit current measurements) and in vivo (salivary secretion) experiments. We report that GPact-11a: 1) is an activator of CFTR in several airway epithelial cell lines; 2) activates rescued F508del-CFTR in nasal, tracheal, bronchial, pancreatic cell lines and in human CF ciliated epithelial cells, freshly dissociated from lung samples; 3) stimulates ex vivo the colonic chloride secretion and increases in vivo the salivary secretion in cftr(+/+) but not cftr(-/-) mice; and 4) is selective for CFTR because its effect is inhibited by CFTR(inh)-172, GlyH-101, glibenclamide and GPinh-5a. To conclude, this work identifies a selective activator of wild-type and rescued F508del-CFTR. This nontoxic and water-soluble agent represents a good candidate, alone or in combination with a F508del-CFTR corrector, for the development of a CFTR modulator in cystic fibrosis.

Contamination of N-poor wastewater with emerging pollutants does not affect the performance of purple phototrophic bacteria and the subsequent resource recovery potential.

Propagation of emerging pollutants (EPs) in wastewater treatment plants has become a warning sign, especially for novel resource-recovery concepts. The fate of EPs on purple phototrophic bacteria (PPB)-based systems has not yet been determined. This work analyzes the performance of a photo-anaerobic membrane bioreactor treating a low-N wastewater contaminated with 25 EPs. The chemical oxygen demand (COD), N and P removal efficiencies were stable (76 ±â€¯8, 62 ±â€¯15 and 36 ±â€¯8 %, respectively) for EPs loading rate ranging from 50 to 200 ng L-1 d-1. The PPB community adapted to changes in both the EPs concentration and the organic loading rate (OLR) and maintained dominance with >85 % of total 16S gene copies. Indeed, an increment of the OLR caused an increase of the biomass growth and activity concomitantly with a higher EPs removal efficiency (30 ±â€¯13 vs 54 ±â€¯11 % removal for OLR of 307 ±â€¯4 and 590 ±â€¯8 mgCOD L-1 d-1, respectively). Biodegradation is the main mechanism of EPs removal due to low EPs accumulation on the biomass, the membrane or the reactor walls. Low EPs adsorption avoided biomass contamination, resulting in no effect on its biological methane potential. These results support the use of PPB technologies for resource recovery with low EPs contamination of the products.

Modulation of established murine collagen-induced arthritis by a single inoculation of short-term lipopolysaccharide-stimulated dendritic cells.

BACKGROUND: The use of regulatory or immature dendritic cells (DCs) as tools for modulating experimental rheumatoid arthritis is very recent. Tumour necrosis factor (TNF)-stimulated DCs have been shown to restore tolerance in experimental autoimmune encephalomyelitis and collagen-induced arthritis (CIA). OBJECTIVE: We investigated the capacity of short-term lipopolysaccharide (LPS)-stimulated DCs pulsed with type II collagen (CII) to induce tolerance against established CIA. METHODS: Bone marrow-derived DCs were generated in the presence of granulocyte monocyte colony-stimulating factor (GM-CSF). After CIA induction, mice were injected at day 35 with a single dose of 4- or 24-h LPS-stimulated DCs that had been loaded with CII (4hLPS/CII/DCs or 24hLPS/CII/DCs). Arthritis progression was monitored by clinical and histological evaluations. RESULTS: Flow cytometry of 4hLPS/CII/DCs showed intermediate CD40 and CD86 expression, lower than that of 24hLPS/CII/DCs (fully mature) and higher than that of CII/DCs (immature). A functional assay showed that 4hLPS/CII/DCs display increased endocytosis ability with respect to 24hLPS/CII/DCs, indicating a semimature state. The single inoculation of 4hLPS/CII/DCs in mice with established CIA reduced disease severity significantly over time. Histological evaluation of mice treated with 4hLPS/CII/DCs revealed diminished inflammatory synovitis, cartilage damage and fibrosis. Co-cultures of DCs with splenocytes from CIA mice showed that collagen-specific interferon (IFN)gamma production was dramatically inhibited by 4hLPS/CII/DCs. 4hLPS/CII/DCs were high IL10 producers, which could explain the inhibition of arthritis progression in mice receiving this treatment because neither antibodies nor regulatory CD4+CD25+Foxp3+ T lymphocytes were demonstrated to be involved. CONCLUSION: Short-term LPS-modulated DCs inoculation interferes with CIA progression when loaded with CII.

Assessment of the IgG index in dogs by indirect immunoenzimatic assays as diagnostic tool for inflammatory diseases of central nervous system.

The IgG index measures the intrathecal immunoglobulin production and it is a useful tool for diagnosis of inflammatory diseases involving the central nervous system. This index is based on the precise quantification of albumin and IgG in canine cerebrospinal fluid and serum. Here, we report the development of an indirect competitive ELISAs for the detection of both antigens. Thirty-two dogs were included in this study, divided into three experimental groups. Group A was composed of 22 healthy animals, as determined by standard clinical examination. In group B, six animals, presented neurological pathologies associated with endogenous IgG production and, in group C four animals presented neurological diseases or symptoms not associated with intrathecal IgG production. Cerebrospinal fluid and serum samples were obtained from these animals. As expected, by using the indirect ELISAs proposed here, the IgG indexes obtained in healthy animals (A) were 0.371+/-0.252 (SD). In B and C, the values (3.002+/-1.897; 0.36+/-0.306, respectively), were in agreement with the pathologic conditions of the individuals in each group. Thus, the immunometric competition ELISA methods proposed here allow the discrimination of abnormal intrathecal IgG production, in a variety of inflammatory pathologic conditions of the central nervous system.

Food consumption by young adults living in Ribeirão Preto, SP, 2002/2004.

There is evidence showing a close relationship between diet and the occurrence of non-communicable chronic diseases. The present study assessed food consumption in a 2002/2004 cohort of young adults born in 1978/79 in Ribeirão Preto, SP, Brazil. The composition of the habitual diet consumed by a sample of 2063 individuals aged 23-25 years was analyzed using a validated semi-quantitative food frequency questionnaire based on studies of prevention of non-communicable chronic diseases. The Dietsys software was used for dietary calculations. In terms of WHO/2003 recommendations, there was a high mean daily consumption of energy from fat (consumption: 35.4%; recommendation: 15-30%), a low mean intake of energy from carbohydrates (47.5%; 55-75%) and a low mean consumption of total fibers (15.2 g; >25 g). Mean intake of energy from fatty acids (10%; <10%) and protein (15.6%; 10-15%) was within recommended limits. When compared to the recommendations of the food pyramid adapted to the Brazilian population, adequate intake was observed only regarding the meat group (consumption: 1.9 portions; recommended: 1-2). There was a low consumption of vegetables (2.9; 4-5), fruits (1.2; 3-5), breads (3.6; 6-9), and dairy products (1.7; 3), with excessive fat and sugar intake (5.7; 1-2). We conclude that the inadequate food consumption observed in this young population may be associated with the development of excess weight and may contribute to the triggering of non-communicable chronic diseases.

First Report of Fusarium Wilt of Flue-Cured Tobacco Caused by Fusarium oxysporum f. sp. batatas in Spain.

Tobacco (Nicotiana tabaccum L.) is among the most important crops in La Vera Region (Cáceres, west-central Spain) where, since 2001, flue-cured tobacco plants showing typical symptoms of a vascular disease associated to the cyst nematode (Globodera tabacum) complex have been frequently observed (2). Symptoms observed were wilting, yellowing, and drying of the leaves, usually on one side of the plant; stunted and distorted leaves with curved midribs due to the unequal growth; and brown vascular discoloration of stems and midribs. Several diseased plants were collected during the summers of 2003 and 2004, and F. oxysporum was consistently isolated from sections of necrotic midribs. To confirm the pathogenicity of F. oxysporum isolates, plants of flue-cured tobacco (cv. Ct-681) were inoculated. Since Fusarium wilt of tobacco may be caused by F. oxysporum f. sp. vasinfectum or F. oxysporum f. sp. batatas (1), plants of cotton (cv. Acala) and sweet potato (cvs. Nemagold and Nancy Hall) were also inoculated to determine the forma specialis designation. Twenty plants per cultivar and isolate were inoculated with six isolates at the two to four true-leaf stage by pouring into the substrate 200 ml of a conidial suspension (1 × 105 CFU/ml). After inoculation, plants were incubated in a growth chamber at 28°C (day) and 24°C (night) with a 16-h photoperiod. All six F. oxysporum isolates were pathogenic to tobacco and sweet potato, but there were differences among isolates in time from inoculation to appearance of first disease symptoms (7 to 15 days after inoculation in tobacco and sweet potato) and also in disease severity 30 days after inoculation (60 to 100% wilt or mortality in tobacco and 50 to 100% in sweet potato). F. oxysporum was reisolated from stems of inoculated plants. No disease symptom was observed in cotton plants 60 days after inoculation, and F. oxysporum was not reisolated from them. Results of inoculation on the differential hosts indicated that disease symptoms in tobacco were caused by F. oxysporum f. sp. batatas. To our knowledge, this is the first report of F. oxysporum f. sp. batatas causing disease in flue-cured tobacco in Spain. References: (1) G. M. Armstrong and J. K. Armstrong. Phytopathology 58:1242, 1968. (2) G. Espárrago and I. Blanco. Plant Dis. 86:1402, 2002.

[Neonatal polysomnography in newborn infants with severe birth asphyxia]. / Polisomnografía neonatal en el recién nacido con asfixia grave al nacer.

INTRODUCTION: Neonatal polysomnography studies (electroencephalogram, electrooculography, body movements, cardiorespiratory frequencies) were performed in 101 newborn full-term infants diagnosed with severe birth asphyxia. PATIENTS AND METHODS: To analyse results, the sample was divided into two groups, depending on whether hypoxic-ischaemic encephalopathy (HIE) had occurred or not. The results of the polysomnography studies were correlated with those from the full-term neurological examination and the sequelae from the neurological development during the first two years of life. RESULTS: Significant correlations were obtained among the variables that were studied. The normality observed in the electrophysiological study in the group of patients with severe asphyxia without HIE was associated with a full-term neurological examination and with a neurological development that has progressed in a satisfactory manner. In the group of patients with grade II HIE there was a predominance of severe alterations in the full-term neonatal polysomnography study, which were significantly correlated with the pathological full-term neurological examinations and serious sequelae from neurological development. CONCLUSIONS: It has been proved that neonatal polysomnography studies are a valuable aid in evaluating the neurological status of newborn infants in a critical condition and in predicting the sequelae of neurological development in the first two years of life. Further research should be aimed at determining the effects exerted by the daily administration of medication (sedatives, anaesthetics and antiepileptic agents) in critical newborn infants on electrical activity in the brain and the cyclic structuring of the different phases of sleep.

Stabilization of lipid/DNA complexes during the freezing step of the lyophilization process: the particle isolation hypothesis.

The instability of nonviral vectors in aqueous suspensions has stimulated an interest in developing lyophilized formulations for use in gene therapy. Previous work has demonstrated a strong correlation between the maintenance of particle size and retention of transfection rates. Our earlier work has shown that aggregation of nonviral vectors typically occurs during the freezing step of the lyophilization process, and that high concentrations of sugars are capable of maintaining particle size. This study extends these observations, and demonstrates that glass formation is not the mechanism by which sugars protect lipid/DNA complexes during freezing. We also show that polymers (e.g., hydroxyethyl starch) are not capable of preventing aggregation despite their ability to form glasses at relatively high subzero temperatures. Instead, our data suggest that it is the separation of individual particles within the unfrozen fraction that prevents aggregation during freezing, i.e., the particle isolation hypothesis. Furthermore, we suggest that the relatively low surface tension of mono- and disaccharides, as compared to starch, allows phase-separated particles to remain dispersed within the unfrozen excipient solution, which preserves particle size and transfection rates during freezing.

[Functional impairment in elderly patients hospitalised in an Internal Medicine unit]. / Deterioro de la capacidad funcional en pacientes ancianos ingresados en un Servicio de Medicina Interna.

To determine the functional status in elderly patients after a hospitalisation in an Internal Medicine unit. We prospectively studied patients aged 80 or above hospitalised in the Hospital Provincial de Ciudad Real in an Internal Medicine unit, between February and July, 2003. The functional status was determined by Barthel Index. We examined 206 patients (77.4%). They showed a previous Barthel Index of 70.9; one of 48.9 in the hospitalisation stage and one of 58.6 when discharged (p<0.001). We noticed a Barthel Index when discharged which was lower than the previous Barthel one in 73.8% patients. Hospitalisation implies a great functional impairment in the functional status elderly patients. It would be convenient, therefore, to identify the risk factors to be able to set some guidelines for a preventive model.

How does hexachlorobenzene treatment affect liver uroporphyrinogen decarboxylase?

The aims of the present work were: (1) to investigate whether the strong decrease of liver uroporphyrinogen decarboxylase (UroD) activity observed in experimental porphyria cutanea tarda is due to alteration of the enzymatic protein and (2) to improve the knowledge about the normal liver enzyme. With these purposes, several physicochemical studies for enzymatic characterization were carried out comparatively on the 12-fold purified liver enzyme of both normal and hexachlorobenzene porphyric rat. The study shows that the enzyme from porphyric rats has a higher activation energy, lower reactivity index and lower optimum pH than the normal one. In addition, it did not reach the Vmax at any of the substrate concentrations assayed (up to 28 microM uroporphyrinogen III), while the normal enzyme reached the plateau around 14 microM. The porphyric enzyme appears to be more protected than the normal against the inhibitory action of several metals, particularly Cu2+ and Pb2+, and against thermal inactivation. Zn2+ did not affect enzymatic activity, whereas Cu2+, Hg2+, Fe2+, Pb2+, and Cd2+ lowered the activities of both normal and porphyric enzyme in a dose-related way. It was also observed that the larger the atomic radius in its hydrated state, the lower the effect of the metal. Neither glutathione nor dithiothreitol significantly altered enzymatic activity in the range of concentrations assayed. beta-Mercaptoethanol had diverse effects, as regards both the concentration assayed and the enzymatic sample used. Assays with cystine showed a dual behaviour of both normal and porphyric enzymatic activity. Western blots for both preparations revealed a single band (65 kDa) with a similar intensity. This study show that hexachlorobenzene treatment modifies the physicochemical properties of liver UroD leading to a sharp decrease of its activity, without affecting its antigenic reactivity probably as a consequence of changes at the conformational level promoted by the binding of its reported inhibitor.

Thyroid function and thyroxine metabolism in hexachlorobenzene-induced porphyria.

The effects of hexachlorobenzene (HCB) administration on the development of porphyria and on changes in thyroid function and thyroid hormone metabolism were examined. Female Wistar rats were treated with HCB for 1 or 8 weeks. At both treatment times liver weight was notably increased with a slight change in thyroid weight at 8 weeks. Serum thyroxine (T4) levels were depressed, whereas levels of triiodothyronine (T3) were not depressed significantly at both treatment times. One or eight weeks of HCB treatment did not alter the incorporation and distribution of [125I] into intrathyroidal aminoacids. A 50% reduction in protein bound iodine (PB[125I]) was seen in both groups of animals. HCB altered [125I]T4 metabolism in rat liver slices, increasing T4 dehalogenation. HCB administration for 1 week did not affect urinary excretion of porphyrins or their precursors, or hepatic porphyrin content. The activity of aminolaevulinate synthase was not affected, but there was a 25% and 51% inhibition in porphyrinogen carboxy-lyase (PCL) activity for the uroporphyrinogen disappearance or the coproporphyrinogen formation respectively. After 8 weeks of HCB administration the rats showed a characteristic porphyria. Our results show that HCB treatment increased hepatic thyroxine metabolism, without alterations in thyroid hormone synthesis. Serum T4 and PCL activity behaved differently in both time- and dose-dependent studies, with serum T4 being the more sensitive parameter which responded at earlier times and lower doses.

Trypanosoma cruzi: H2 complex and genetic background influence on the humoral immune response against epimastigotes.

Using A.SW, A.CA, B10.S and B10.M congenic mouse strains, we measured the IgG specific humoral immune responses against sonicated and live Trypanosoma cruzi epimastigotes. Genes located in the A background (A.SW and A.CA strains) mediate higher IgG responses against the parasite antigenic complexes than those located in the B background (strains B10.S and B10.M), regardless of the H2 haplotypes. Thus, non H2 genetic elements seem to be more important in determining differences in the total IgG immune response against T. cruzi. Whether a detectable H2 effect, in favor of the H2(s) haplotype, occurred in the A or B background, was contingent on the immunisation protocol used. Thus, the H2(s) haplotype mediates a higher IgG response in the A background, if immunised with live epimastigotes, and in the B background against sonicated epimastigotes. Most likely this represents a complex sequence of events, controlled by non-MHC genes, involving antigen handling and processing and depending on the physical form of antigen delivery.

Tc45, a dimorphic Trypanosoma cruzi immunogen with variable chromosomal localization, is calreticulin.

We demonstrate that Tc45, a polypeptide described as an immunogenetically restricted Trypanosoma cruzi antigen in mice, is calreticulin, a dimorphic molecule encoded by genes with variable chromosomal distribution. Previously we showed that IgG from A.SW (H2s) mice immunized with T. cruzi trypomastigotes or epimastigotes and sera from infected humans recognize Tc45, a 45 kD parasite polypeptide. Herein we describe the cloning, sequencing, and expression of the Tc45 gene. A 98% homology in the deduced amino acid sequence was found with a T. cruzi calreticulin-like molecule and 41% with Leishmania donovani and human calreticulin. In the T. cruzi CL Brener clone and in the Tulahuén strain, the gene is located in two and four chromosomes, respectively. Calreticulin was detected in several T. cruzi clones, in the Tulahuén strain, and in T. rangeli, displaying alternative 43 and 46 kD forms.