Acute human schistosomiasis mansoni

The acute schistosomiasis is the toxemic disease that follow the Schistosoma cercariae active penetration trough screen in the immunologicaly naive vertebrate host. The clinical picture starts two to eight weeks after the first contact with the contaminated water. Susceptible patients present a syndrome comprising fever, diarrhea, toxemia and hepatosplenomegaly. Diagnosis is based on epidemiological and clinical features, presence of Schistosoma eggs in the feces, enlargement of abdominal lymph nodes by ultrasonography and by detection of high antibodies levels against the antigen keyhole limpet haemocyanin. Different rates of cure have been observed with specific medication and for the most severe clinical presentations the use of steroids reduces the systemic and allergic manifestations.

A Preliminary Analysis of Insects of Medico-legal Importance in Curitiba, State of Paraná

A survey of the carrion fauna was made at two sites in Curitiba, State of Paraná, with the objective of describing the insects associated with carrion and setting up a preliminary data-base for medico-legal purposes in south Brazil. Vertebrate exclusion experiments were carried out in each season between 1994 and 1995 with a 250 g laboratory-bred rat (Rattus norvegicus). Five stages of decomposition were identified: fresh, bloated, decaying, dry and adipocere-like. Some species showed seasonal and site preference and so could be used to identify the probable place and season where death took place. Sarconesia chlorogaster (Diptera, Calliphoridae) was restricted to an open field site and to cooler months. Hemilucilia semidiaphana (Diptera, Calliphoridae) and Pattonella resona (Diptera, Sarcophagidae) were restricted to the forest site and warmer months. Phaenicia eximia (Diptera, Calliphoridae) and Oxyletrum discicolle (Coleoptera, Silphidae) were present at both sites throughout the year and could be useful for population level analysis. Dissochaetus murray (Coleoptera, Cholevidae) was present throughout the year at the forest site and was associated with the adipocere-like stage. Ants played an important role producing post-mortem injuries to the carcasses. Insects of 32 species are reported as being useful in community level approaches

Differential regulation of the Hippo pathway by adherens junctions and apical-basal cell polarity modules.

Adherens junctions (AJs) and cell polarity complexes are key players in the establishment and maintenance of apical-basal cell polarity. Loss of AJs or basolateral polarity components promotes tumor formation and metastasis. Recent studies in vertebrate models show that loss of AJs or loss of the basolateral component Scribble (Scrib) cause deregulation of the Hippo tumor suppressor pathway and hyperactivation of its downstream effectors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). However, whether AJs and Scrib act through the same or independent mechanisms to regulate Hippo pathway activity is not known. Here, we dissect how disruption of AJs or loss of basolateral components affect the activity of the Drosophila YAP homolog Yorkie (Yki) during imaginal disc development. Surprisingly, disruption of AJs and loss of basolateral proteins produced very different effects on Yki activity. Yki activity was cell-autonomously decreased but non-cell-autonomously elevated in tissues where the AJ components E-cadherin (E-cad) or α-catenin (α-cat) were knocked down. In contrast, scrib knockdown caused a predominantly cell-autonomous activation of Yki. Moreover, disruption of AJs or basolateral proteins had different effects on cell polarity and tissue size. Simultaneous knockdown of α-cat and scrib induced both cell-autonomous and non-cell-autonomous Yki activity. In mammalian cells, knockdown of E-cad or α-cat caused nuclear accumulation and activation of YAP without overt effects on Scrib localization and vice versa. Therefore, our results indicate the existence of multiple, genetically separable inputs from AJs and cell polarity complexes into Yki/YAP regulation.

Genetic Data Showing Evolutionary Links between Leishmania and Endotrypanum

Striking similarities at the morphological, molecular and biological levels exist between many trypanosomatids isolated from sylvatic insects and/or vertebrate reservoir hosts that make the identification of medically important parasites demanding. Some molecular data have pointed to the relationship between some Leishmania species and Endotrypanum, which has an important epidemiological significance and can be helpful to understand the evolution of those parasites. In this study, we have demonstrated a close genetic relationship between Endotrypanum and two new leishmanial species, L. (V.) colombiensis and L. (V.) equatorensis. We have used (a) numerical zymotaxonomy and (b) the variability of the internal transcribed spacers of the rRNA genes to examine relationships in this group. The evolutionary trees obtained revealed high genetic similarity between L. (V.) colombiensis, L. (V.) equatorensis and Endotrypanum, forming a tight cluster of parasites. Based on further results of (c) minicircle kDNA heterogeneity analysis and (d) measurement of the sialidase activity these parasites were also grouped together.

An Investigation on the Ecology of Triatoma vitticeps (Stal, 1859) and its Possible Role in the Transmission of Trypanosoma cruzi, in the Locality of Triunfo, Santa Maria Madalena Municipal District, State of Rio de Janeiro, Brazil

From January 1989 to April 1995, 465 specimens of Triatoma vitticeps were collected in the locality of Triunfo, 2nd District of Santa Maria Madalena municipal district, State of Rio de Janeiro. The bugs were found indoors by local residents with predominance of adults. The flight activity was high in hot months when the incidence in the domicile also increased. Two hundred and two bugs (111 alive and 91 dead) were examined for Trypanosoma cruzi infection. This was detected in 31 of the dead bugs (34%) and 88 (79%) of the live bugs examined. With a view to investigate the possible vertebrate hosts of the T. cruzi isolates, the blood of 122 mammals was examined through Giemsa-stained smears, hemocultures and xenodiagnosis. T. cruzi was detected in three specimens of Didelphis marsupialis and T. (M.) theileri was detected in one specimen of Bos taurus. The parasites were isolated from triatomine feces, xenoculture and hemoculture. No evidence of human infection was detected in 58 inhabitants examined, as evaluated by indirect imunofluorescence technique using T. cruzi epimastigotes as antigens. These results show that T. vitticeps is still a sylvatic species although nymphs have been found inside the domicile. Thus, an epidemiological vigilance is necessary to know the behaviour of this species following the continuous modifications promoted by the presence of man.

Trypanosoma cruzi: Maintenance in Culture Modify Gene and Antigenic Expression of Metacyclic Trypomastigotes

In this study we examined whether the maintenance of Trypanosoma cruzi by long-time in axenic culture produces changes in gene expression and antigenic profiles. The studies were made with a Dm30L-clone from a low-virulent strain and a non-cloned virulent EP-strain of T. cruzi. Both parasites were maintained, for at least seven years, by successive alternate passage triatomine/mouse (triatomine condition), or by serial passage in axenic medium (culture condition). The comparison of the [35S]methionine metabolic labeling products of virulent and non-virulent parasites by 2D-SDS-PAGE, clearly indicates that the expression of metacyclic trypomastigotes (but not of epimastigotes) proteins have been altered by laboratory maintenance conditions. Western blot analysis of EP and Dm30L-epimastigotes using a serum anti-epimastigotes revealed that although most of antigens are conserved, four antigens are characteristics of triatomine condition parasites and three other are characteristics of culture condition parasites. Anti-metacyclics serum revealed significative differences in EP- and Dm30L-metacyclic trypomastigotes from triatomine condition. However, avirulent metacyclic forms were antigenically very similar. These results suggest that besides a possible selection of avirulent subpopulation from T. cruzi strains genetically heterogeneous when maintained by long time in axenic culture, changes in virulence might be due to post-translational modifications of the antigens induced by the absence of the natural alternability (vertebrate-invertebrate) in the life-cycle of T. cruzi

Chromatic pupil responses: preferential activation of the melanopsin-mediated versus outer photoreceptor-mediated pupil light reflex.

OBJECTIVE: To weight the rod-, cone-, and melanopsin-mediated activation of the retinal ganglion cells, which drive the pupil light reflex by varying the light stimulus wavelength, intensity, and duration. DESIGN: Experimental study. PARTICIPANTS: Forty-three subjects with normal eyes and 3 patients with neuroretinal visual loss. METHODS: A novel stimulus paradigm was developed using either a long wavelength (red) or short wavelength (blue) light given as a continuous Ganzfeld stimulus with stepwise increases over a 2 log-unit range. The pupillary movement before, during, and after the light stimulus was recorded in real time with an infrared illuminated video camera. MAIN OUTCOME MEASURES: The percent pupil contraction of the transient and sustained pupil response to a low- (1 cd/m(2)), medium- (10 cd/m(2)), and high-intensity (100 cd/m(2)) red- and blue-light stimulus was calculated for 1 eye of each subject. From the 43 normal eyes, median and 25th, 75th, 5th, and 95th percentile values were obtained for each stimulus condition. RESULTS: In normal eyes at lower intensities, blue light evoked much greater pupil responses compared with red light when matched for photopic luminance. The transient pupil contraction was generally greater than the sustained contraction, and this disparity was greatest at the lowest light intensity and least apparent with bright (100 cd/m(2)) blue light. A patient with primarily rod dysfunction (nonrecordable scotopic electroretinogram) showed significantly reduced pupil responses to blue light at lower intensities. A patient with achromatopsia and an almost normal visual field showed selective reduction of the pupil response to red-light stimulation. A patient with ganglion cell dysfunction owing to anterior ischemic optic neuropathy demonstrated global loss of pupil responses to red and blue light in the affected eye. CONCLUSIONS: Pupil responses that differ as a function of light intensity and wavelength support the hypothesis that selected stimulus conditions can produce pupil responses that reflect phototransduction primarily mediated by rods, cones, or melanopsin. Use of chromatic pupil responses may be a novel way to diagnose and monitor diseases affecting either the outer or inner retina.

Haematophagy and cleptohaematophagy of Clerada apicicornis (Hemiptera: Lygaeidae), a potential biological control agent of Rhodnius prolixus (Hemiptera: Reduviidae)

Because of its ability to prey on Triatominae in rural houses, Clerada apicicornis has been suggested as a potential biological control agent of Rhodnius prolixus. It has also been suggested as a potential vector of mammalian trypanosomes such as Trypanosoma cruzi, because of its ability to take blood directly from mammals. To help resolve these conflicting ideas, we assessed the haematophagic behaviour of C. apicicornis by carrying out feeding trials on laboratory animals. Cleptohaematophagic behaviour was also assessed by allowing C. apicicornis to feed on R. prolixus previously engorged with avian blood. The low proportion of blood meals taken directly from laboratory animals indicates a facultative haematophagy in this species, whereas a greater proportion of nymphs and adults were able to obtain vertebrate blood by predation on engorged R. prolixus. The results suggest that C. apicicornis is unlikely to be effective as a biological control agent, but is also unlikely to have a significant role in the transmission of vertebrate pathogens.

A checklist of arthropods associated with pig carrion and human corpses in Southeastern Brazil

Necrophagous insects, mainly Diptera and Coleoptera, are attracted to specific stages of carcass decomposition, in a process of faunistic succession. They are very important in estimating the postmortem interval, the time interval between the death and the discovery of the body. In studies done with pig carcasses exposed to natural conditions in an urban forest (Santa Genebra Reservation), located in Campinas, State of São Paulo, southeastern Brazil, 4 out of 36 families of insects collected - Calliphoridae, Sarcophagidae, Muscidae (Diptera) and Dermestidae (Coleoptera) - were considered of forensic importance, because several species were collected in large numbers both visiting and breeding in pig carcasses. Several species were also observed and collected on human corpses at the Institute of Legal Medicine. The species belonged to 17 different families, 6 being of forensic importance because they were reared from human corpses or pig carcasses: Calliphoridae, Sarcophagidae, Muscidae, Piophilidae (Diptera), Dermestidae, Silphidae and Cleridae (Coleoptera). The most important species were: Diptera - Chrysomya albiceps, Chrysomya putoria, Hemilucilia segmentaria, Hemilucilia semidiaphana (Calliphoridae), Pattonella intermutans (Sarcophagidae), Ophyra chalcogaster (Muscidae), Piophila casei (Piophilidae); Coleoptera - Dermestes maculatus (Dermestidae), Oxyletrum disciolle (Silphidae) and Necrobia rufipes (Cleridae).

Phylogeny of the kinetoplastida: taxonomic problems and insights into the evolution of parasitism

To further investigate phylogeny of kinetoplastid protozoa, the sequences of small subunit (18S) ribosomal RNA of nine bodonid isolates and ten isolates of insect trypanosomatids have been determined. The root of the kinetoplastid tree was attached to the branch of Bodo designis and/or Cruzella marina. The suborder Trypanosomatina appeared as a monophyletic group, while the suborder Bodonina was paraphyletic. Among bodonid lineages, parasitic organisms were intermingled with free-living ones, implying multiple transitions to parasitism and supporting the `vertebrate-first hypothesis'. The tree indicated that the genera Cryptobia and Bodo are artificial taxa. Separation of fish cryptobias and Trypanoplasma borreli as different genera was not supported. In trypanosomatids, the genera Leptomonas and Blastocrithidia were polyphyletic, similar to the genera Herpetomonas and Crithidia and in contrast to the monophyletic genera Trypanosoma and Phytomonas. This analysis has shown that the morphological classification of kinetoplastids does not in general reflect their genetic affinities and needs a revision.

Morphological aspects of Schistosoma mansoni adult worms isolated from nourished and undernourished mice: a comparative analysis by confocal laser scanning microscopy

Malnutrition hampers the course of schistosomiasis mansoni infection just as normal growth of adult worms. A comparative morphometric study on adult specimens (male and female) recovered from undernourished (fed with a low protein diet - regional basic diet) and nourished (rodent commercial laboratory food, NUVILAB) white mice was performed. Tomographic images and morphometric analysis of the oral and ventral suckers, reproductive system and tegument were obtained by means of confocal laser scanning microscopy. Undernourished male specimens presented smaller morphometric values (length and width) of the reproductive system (first, third and last testicular lobes) and thickness of the tegument than controls. Besides that, it was demonstrated that the dorsal surface of the male worms bears large tubercles unevenly distributed, but kept grouped and flat. At the subtegumental region, vacuolated areas were detected. It was concluded that the inadequate nutritional status of the vertebrate host has a negative influence mainly in the reproductive system and topographical somatic development of male adult Schistosoma mansoni, inducing some alterations on the structure of the parasite.

Activity of Tabanids (Insecta: Diptera: Tabanidae) Attacking the Reptiles Caiman crocodilus (Linn.) (Alligatoridae) and Eunectes murinus (Linn.) (Boidae), in the Central Amazon, Brazil

Tabanid females are better known as hematophagous on man and other mammals, and linked to mechanical transmission of parasites. The association between tabanids and reptiles is poorly known, but has been gaining more corroboration through experiments and occasional observation in the tropics. The present study was conducted at a military base (CIGS/BI-2), situated 54 km from Manaus, Amazonas, in a small stream in a clearing (02°45'33"S; 59°51'03"W). Observations were made monthly, from April 1997 to March 1998, during two consecutive days. At the same time, other vertebrate animals were offered, including humans. However in this paper only data obtained on a common caiman, Caiman crocodilus (Linn.), and an anaconda, Eunectes murinus (Linn.), in diurnal observations from 05:30 a.m. to 18:30 p.m., will be discussed. A total of 254 tabanid specimens were collected, 40 from the anaconda and 214 from the caiman. Four tabanid species were recorded on these two reptiles: Stenotabanus cretatus Fairchild, S. bequaerti Rafael et al., Phaeotabanus nigriflavus (Kröber) and Tabanus occidentalis Linn. Diurnal activities showed species-specific patterns. The first three species occurred only in the dry season. T. occidentalis occurred during the whole observation period, and with increased frequency at the end of the dry season. We observed preferences for body area and related behavior of the host. Observations on the attack of tabanids on one dead caiman are also presented.

Avian erythrocytes have functional mitochondria, opening novel perspectives for birds as animal models in the study of ageing.

BACKGROUND: In contrast to mammalian erythrocytes, which have lost their nucleus and mitochondria during maturation, the erythrocytes of almost all other vertebrate species are nucleated throughout their lifespan. Little research has been done however to test for the presence and functionality of mitochondria in these cells, especially for birds. Here, we investigated those two points in erythrocytes of one common avian model: the zebra finch (Taeniopygia guttata). RESULTS: Transmission electron microscopy showed the presence of mitochondria in erythrocytes of this small passerine bird, especially after removal of haemoglobin interferences. High-resolution respirometry revealed increased or decreased rates of oxygen consumption by erythrocytes in response to the addition of respiratory chain substrates or inhibitors, respectively. Fluorometric assays confirmed the production of mitochondrial superoxide by avian erythrocytes. Interestingly, measurements of plasmatic oxidative markers indicated lower oxidative stress in blood of the zebra finch compared to a size-matched mammalian model, the mouse. CONCLUSIONS: Altogether, those findings demonstrate that avian erythrocytes possess functional mitochondria in terms of respiratory activities and reactive oxygen species (ROS) production. Interestingly, since blood oxidative stress was lower for our avian model compared to a size-matched mammalian, our results also challenge the idea that mitochondrial ROS production could have been one actor leading to this loss during the course of evolution. Opportunities to assess mitochondrial functioning in avian erythrocytes open new perspectives in the use of birds as models for longitudinal studies of ageing via lifelong blood sampling of the same subjects.

Morphologic and morphometric analysis of Hepatozoon spp. (Apicomplexa, Hepatozoidae) of snakes

Hepatozoon species are the most abundant hemoparasites of snakes. Its identification has been based mainly on the morphologic characterization of the gamonts in the peripheral blood of the vertebrate host and also of the cysts found in the internal organs of the vertebrate and invertebrate hosts. Using a computerized image analysis system, we studied five species of Hepatozoon from recently captured snakes in Botucatu, State of São Paulo, Brazil, to evaluate the importance of the morphology and morphometry of the gamonts for the characterization of Hepatozoon species and to analyze the morphologic changes induced in the erythrocytes by the parasite. The studied species were H. terzii of Boa constrictor amarali, Hepatozoon sp. of Crotalus durissusterrificus, H. philodryasi of Philodryas patagoniensis, and H. migonei and H. cyclagrasi of Hydrodynastes gigas. We observed three different groups, one of them including the species H. terzii, H. philodryasi and Hepatozoon sp. of C. durissus terrificus; and the other two consisting of H. migonei and H. cyclagrasi. Degree of alterations in the erythrocytes was variable and it may be useful for characterization of Hepatozoon species.

Genetic markers between Biomphalaria glabrata snails susceptible and resistant to Schistosoma mansoni infection

The analysis of the genetic variability related to susceptibility to Schistosoma mansoni infection in the vector of the genus Biomphalaria is important in terms of a better understanding of the epidemiology of schistosomiasis itself, the possible pathological implications of this interaction in vertebrate hosts, and the formulation of new strategies and approaches for disease control. In the present study, the genetic variability of B. glabrata strains found to be resistant or susceptible to S. mansoni infection was investigated using DNA amplification by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). The amplification products were analyzed on 8% polyacrylamide gel and stained with silver. We selected 10 primers, since they have previously been useful to detect polymorphism among B. glabrata and/or B. tenagophila. The results showed polymorphisms with 5 primers. Polymorphic bands observed only in the susceptible strain. The RAPD-PCR methodology represents an adequate approach for the analysis of genetic polymorphisms. The understanding of the genetic polymorphisms associated to resistance may contribute to the future identification of genomic sequences related to the resistance/susceptibility of Biomphalaria to the larval forms of S. mansoni and to the development of new strategies for the control of schistosomiasis.