Biomedical subjects

J P Laclette

Publications and source records attributed to J P Laclette.

At least 19 recordsLinked to original sources

PubMed2006

Taxonomic study of the Phyllosoma complex and other triatomine (Insecta: Hemiptera: Reduviidae) species of epidemiological importance in the transmission of Chagas disease: using ITS-2 and mtCytB sequences.

The purpose of this work was to clarify the taxonomy and phylogenetic relationship of the Phyllosoma complex and other important vectors in Mexico. The internal transcribed spacer 2 (ITS-2) of rDNA and the cytochrome B gene of mtDNA (mtCytB) were analyzed for the following species of triatomine: Triatoma bassolsae, T. longipennis, T. mazzottii, T. mexicana, T. pallidipennis, T. picturata, and T. phyllosoma belonging to the Phyllosoma complex, as well as T. dimidiata, T. rubida, T. infestans, and Rhodnius prolixus. The results obtained with the analysis of the ITS-2 sequences showed that the Phyllosoma complex species could not be phylogenetically separated, since T. bassolsae and T. pallidipennis, as well as T. phyllosoma and T. mazzottii were indistinguishable. In contrast, the mtCytB gene separates each one of these triatomine species. The results support the proximity of all seven species currently included in the Phyllosoma complex as well as the exclusion of T. dimidiata. For the first time T. lecticularia and T. rubida were analyzed and were also shown to be related to the Phyllosoma complex.

Animals↗

PubMed2006

Biocompatibility and toxicological studies of carbon nanotubes doped with nitrogen.

In this report, we compare the toxicological effects between pure carbon multiwalled nanotubes (MWNTs) and N-doped multiwalled carbon (CNx) nanotubes. Different doses of tubes were administered in various ways to mice: nasal, oral, intratracheal, and intraperitoneal. We have found that when MWNTs were injected into the mice's trachea, the mice could die by dyspnea depending on the MWNTs doses. However, CNx nanotubes never caused the death of any mouse. We always found that CNx nanotubes were far more tolerated by the mice when compared to MWNTs. Extremely high concentrations of CNx nanotubes administrated directly into the mice's trachea only induced granulomatous inflammatory responses. Importantly, all other routes of administration did not induce signs of distress or tissue changes on any treated mouse. We therefore believe that CNx nanotubes are less harmful than MWNTs or SWNTs and might be more advantageous for bioapplications.

Administration, Inhalation↗

PubMed2003

Identification of CD4+ T cell epitopes of Taenia solium paramyosin.

T cell mediated response is involved in a protective immune response against experimental cysticercosis conferred by immunization with Taenia solium paramyosin (TPmy) to BALB/c mice. In this study, we analysed the TPmy amino acid sequence for predicted CD4+ T cells epitopes. Five different regions of this protein showed that the residues anchor to bind the I-Ad molecule, synthetic peptides containing these epitopes were evaluated for their ability to induce lymphoproliferative responses of spleen cells from TPmy immunized mice. Among them, Tp176 (amino acids 176-192 sequence DDLQRQMADANSAKSRL) was the immunodominant T cell epitope of TPmy. Delineation of this epitope should facilitate analysis of the role of CD4+ T cell response in experimental cysticercosis.

Amino Acid Sequence↗

PubMed2002

Bacterial 16S rRNA gene analysis revealed that bacteria related to Arcobacter spp. constitute an abundant and common component of the oyster microbiota (Tiostrea chilensis).

To explore the bacterial microbiota in Chilean oyster (Tiostrea chilensis), a molecular approach that permits detection of different bacteria, independently of their capacity to grow in culture media, was used. Bacterial diversity was assessed by analysis of both the 16S rDNA and the 16S-23S intergenic region, obtained by PCR amplifications of DNA extracted from depurated oysters. RFLP of the PCR amplified 16S rDNA showed a prevailing pattern in most of the individuals analyzed, indicating that a few bacterial species were relatively abundant and common in oysters. Cloning and sequencing of the 16S rDNA with the prevailing RFLP pattern indicated that this rRNA was most closely related to Arcobacter spp. However, analysis by the size of the amplified 16S-23S rRNA intergenic regions revealed not Arcobacter spp. but Staphylococcus spp. related bacteria as a major and common component in oyster. These different results may be caused by the absence of target for one of the primers employed for amplification of the intergenic region. Neither of the two bacteria species found in large abundance was recovered after culturing under aerobic, anaerobic, or microaerophilic conditions. This result, however, is expected because the number of bacteria recovered after cultivation was less than 0.01% of the total. All together, these observations suggest that Arcobacter-related strains are probably abundant and common in the Chilean oyster bacterial microbiota.

Animals↗

PubMed2002

The taenia solium glucose transporters TGTP1 and TGTP2 are not immunologically recognized by cysticercotic humans and swine.

Cysticercosis caused by the metacestode of the tapeworm Taenia solium causes economic losses in pork meat production, as well as being a human health hazard in some parts of the world. In order to determine if the glucose transporters TGTPI and TGTP2 are recognized by antibodies in the sera from cysticercotic humans and pigs, western blot assays were carried out using membrane fractions of insect cells expressing the two T. solium glucose transporters. Results demonstrated a complete lack of recognition of both TGTPs. These results are unexpected, because at least one transporter is present on the apical surface of the cysticercus tegument.

Animals↗

PubMed2001

Heat shock and stress response of Taenia solium and T. crassiceps (Cestoda).

Heat shock and stress responses are documented for the first time in larval stages of the cestodes Taenia solium and Taenia crassiceps. Radioactive metabolic labelling after in vitro incubation of cysts at 43 degrees C, revealed the induction of heat shock proteins. In T. crassiceps, the major heat shock proteins were 80, 70 and 60 kDa. After prolonged incubation, a set of low molecular weight heat shock proteins (27, 31, 33 and 38 kDa), were also induced. In vitro incubation of cysts at 4 degrees C, induced the synthesis of stress proteins ranging from 31 to 80 kDa, indicating the parasite is also able to respond to cold shock. T. solium cysts exposure to temperature stress also resulted in an increased synthesis of 2 major heat shock proteins of 80 and 70 kDa. Western blots using the excretory-secretory products of T. solium showed that 2 heat shock proteins were recognized by antibodies in the sera of cysticercotic patients: one of 66 kDa and another migrating close to the run front. The T. solium 66 kDa protein was also recognized by specific antibodies directed to a 60 kDa bacterial heat shock protein, suggesting that it belongs to this family of proteins.

Animals↗

PubMed2001

Human T and B cell epitope mapping of Taenia solium paramyosin.

Taenia solium paramyosin is an immunodominant antigen in human and porcine cysticercosis that has shown promise as a vaccine candidate against schistosomiasis and some filariasis. There are few studies to identify the immunologically relevant regions of paramyosin. In this work, we characterize the humoral and cellular response of neurocysticercotic patients against T. solium paramyosin. Western blots using different recombinant fragments of T. solium paramyosin, showed that the sera from neurocysticercotic patients were strongly reactive against the carboxyl end region, with poor recognition of the central and amino regions. In contrast, the cellular immune response of patients did not show preferential recognition of any region of paramyosin.

Animals↗

PubMed2001

Characterization and protective potential of the immune response to Taenia solium paramyosin in a murine model of cysticercosis.

Paramyosin has been proposed as a vaccine candidate in schistosomiasis and filariasis. However, limited information is available about its protective potential against cysticercosis and the immune response it induces. Immunization of mice with recombinant full-length paramyosin of Taenia solium (TPmy) results in about a 52% reduction in parasite burden after a subsequent challenge by intraperitoneal inoculation of Taenia crassiceps cysticerci. Immunization assays using recombinant fragments of TPmy, corresponding approximately to thirds on the amino, central, or carboxyl regions, suggest that protective epitopes are located mostly in the amino-end third. Proliferation assays using T cells obtained from mice immunized with the full-length recombinant TPmy also showed a preferential response to the amino-terminal fragment. In contrast, antibodies in the sera from these mice predominantly recognize epitopes located in the carboxyl-terminal fragment, being the immunoglobulin G1 subclass, the predominant antibody isotype. Characterization of the cellular immune response induced against the protective amino-terminal fragment reveals production of gamma interferon and interleukin-2, but not interleukin-4, suggesting a Th1-like profile.

Animals↗

PubMed2001

Cellular immune response and Th1/Th2 cytokines in human neurocysticercosis: lack of immune suppression.

Some reports have suggested that human neurocysticercosis (NCC) induces immunosuppression. To test this hypothesis, we performed a study on active cases of NCC who had not received cestocidal or immunosuppressive treatments. We examined blood counts and specific T cell markers (CD3, CD4, and CD8) by flow cytometry and found no differences between patients with NCC and healthy individuals. Both groups responded to concanavalin A (Con A), and patients with NCC responded more to a parasite crude antigen than uninfected individuals. Peripheral blood mononuclear cells were examined for interleukin (IL)-2, interferon-gamma, IL-10, and IL-4 mRNA. Regardless of infection status, more than 60% of individuals synthesized IL-2 mRNA and, less frequently, the other cytokines. These data suggest that immunosuppression does not occur in NCC patients.

Adult↗

PubMed2000

Epitope mapping on N-terminal region of taenia solium paramyosin.

Epitope mapping of the amino-terminal 20aa sequence from Taenia solium paramyosin (TPmy), an immunodominant protein involved in the complex host-parasite relationship in human and porcine cysticercosis is reported. A 12-mer random peptide phage display library was screened with antibodies raised against a synthetic peptide corresponding to the amino-terminal 20aa sequence of TPmy, its highly immunodominant region. In total, 57 clones isolated in two panning conditions were analyzed, of which a single group of 14 sequences found in 25 clones shared a consensus motif showing structural similarity with the antigen Arg10-Thr16 region.

Amino Acid Sequence↗

PubMed2000

Phylogenetic relationships of Acanthocephala based on analysis of 18S ribosomal RNA gene sequences.

Acanthocephala (thorny-headed worms) is a phylum of endoparasites of vertebrates and arthropods, included among the most phylogenetically basal tripoblastic pseudocoelomates. The phylum is divided into three classes: Archiacanthocephala, Palaeacanthocephala, and Eoacanthocephala. These classes are distinguished by morphological characters such as location of lacunar canals, persistence of ligament sacs in females, number and type of cement glands in males, number and size of proboscis hooks, host taxonomy, and ecology. To understand better the phylogenetic relationships within Acanthocephala, and between Acanthocephala and Rotifera, we sequenced the nearly complete 18S rRNA genes of nine species from the three classes of Acanthocephala and four species of Rotifera from the classes Bdelloidea and Monogononta. Phylogenetic relationships were inferred by maximum-likelihood analyses of these new sequences and others previously determined. The analyses showed that Acanthocephala is the sister group to a clade including Eoacanthocephala and Palaeacanthocephala. Archiacanthocephala exhibited a slower rate of evolution at the nucleotide level, as evidenced by shorter branch lengths for the group. We found statistically significant support for the monophyly of Rotifera, represented in our analysis by species from the clade Eurotatoria, which includes the classes Bdelloidea and Monogononta. Eurotatoria also appears as the sister group to Acanthocephala.

Acanthocephala↗

PubMed2000

Cloning and characterization of Entamoeba histolytica antigens recognized by human secretory IgA antibodies.

To identify the Entamoeba histolytica antigens capable of inducing secretory IgA (sIgA) responses in humans, a cDNA library from the strain HM1:IMSS was immuno-screened with saliva from patients with intestinal amebiasis or amebic liver abscess. Clones isolated with sIgA antibodies from patients with intestinal amebiasis corresponded to the known serine-rich protein isoform, a 29 kDa cysteine-rich protein and 1-alpha elongation factor. Clones corresponding to enolase, cyclophilin, ribosomal protein L23a, and an Hsp70 family protein were isolated with sIgA from a patient with amebic liver abscess. A glutamic acid-rich peptide (EhGARP) positive with sIgA from a patient with amebic liver abscess was also isolated; for EhGARP, no homologs were found in the protein databases. The antigens isolated are potentially useful in the development of an oral vaccine or new diagnostic tools for amebiasis.

Amino Acid Sequence↗

PubMed2000

Taenia solium disease in humans and pigs: an ancient parasitosis disease rooted in developing countries and emerging as a major health problem of global dimensions.

This article reviews current knowledge on human and porcine cysticercosis caused by Taenia solium. It highlights the conditions favorable for its prevalence and transmission, as well as current trends in research on its natural history, epidemiology, immunopathology, diagnosis, treatment and prevention. Our opinions on the most urgent needs for further research are also presented.

Animals↗

PubMed1999

Phylogenetic analysis of the homologous proteins of the terminal complement complex supports the emergence of C6 and C7 followed by C8 and C9.

The plasma complement system comprises several activation pathways that share a common terminal route involving the assembly of the terminal complement complex (TCC), formed by C5b-C9. The order of emergence of the homologous components of TCC (C6, C7, C8alpha, C8beta, and C9) has been determined by phylogenetic analyses of their amino acid sequences. Using all the sequence data available for C6-C9 proteins, as well as for perforins, the results suggested that these TCC components originated from a single ancestral gene and that C6 and C7 were the earliest to emerge. Our evidence supports the notion that the ancestral gene had a complex modular composition. A series of gene duplications in combination with a tendency to lose modules resulted in successive complement proteins with decreasing modular complexity. C9 and perforin apparently are the result of different selective conditions to acquire pore-forming function. Thus C9 and perforin are examples of evolutionary parallelism.

Amino Acid Sequence↗

PubMed1999

Formation of calcareous corpuscles in the lumen of excretory canals of Taenia solium cysticerci.

Platyhelminths, like many other organisms, are capable of producing mineral concretions. In cestodes these are referred to as calcareous corpuscles. Studies on these concretions in different cestodes both in vivo and in vitro have resulted in a number of hypotheses on their origin, formation, and structure. Calcareous corpuscles are believed to be of cellular origin, although the kind of cell involved and the mechanisms of mineralization remain under discussion. In the present paper we show that formation of calcareous corpuscles in cysticerci of Taenia solium is not of intracellular origin, as described for other cestodes, but occurs extracellularly in the lumen of protonephridial ducts in a way similar to that proposed for trematodes. This finding enhances the function of the protonephridial ducts, at least in the larvae of T. solium, to the roles formerly ascribed to the calcareous corpuscles.

Animals↗

PubMed1998

Phylogenetic relationships of platyhelminthes based on 18S ribosomal gene sequences.

Nucleotide sequences of 18S ribosomal RNA from 71 species of Platyhelminthes, the flatworms, were analyzed using maximum likelihood, and the resulting phylogenetic trees were compared with previous phylogenetic hypotheses. Analyses including 15 outgroup species belonging to eight other phyla show that Platyhelminthes are monophyletic with the exception of a sequence putatively from Acoela sp., Lecithoepitheliata, Polycladida, Tricladida, Trematoda (Aspidobothrii + Digenea), Monogenea, and Cestoda (Gyrocotylidea + Amphilinidea + Eucestoda) are monophyletic groups. Catenulids form the sister group to the rest of platyhelminths, whereas a complex clade formed by Acoela, Tricladida, "Dalyellioida", and perhaps "Typhloplanoida" is sister to Neodermata. "Typhloplanoida" does not appear to be monophyletic; Fecampiida does not appear to belong within "Dalyellioida," nor Kalyptorhynchia within "Typhloplanoida." Trematoda is the sister group to the rest of Neodermata, and Monogenea is sister group to Cestoda. Within Trematoda, Aspidobothrii is the sister group of Digenea and Heronimidae is the most basal family in Digenea. Our trees support the hypothesis that parasitism evolved at least twice in Platyhelminthes, once in the ancestor to Neodermata and again in the ancestor of Fecampiida, independently to the ancestor of putatively parasitic "Dalyellioida."

Animals↗

PubMed1998

Molecular and functional characterization and tissue localization of 2 glucose transporter homologues (TGTP1 and TGTP2) from the tapeworm Taenia solium.

Tapeworms absorb and consume large quantities of glucose through their syncytial tegument, storing the excess as glycogen. Although some studies on the metabolism of glucose in several tapeworms are available, the proteins that mediate its uptake and distribution in their tissue have not been identified. We describe the isolation and characterization of cDNA clones encoding 2 facilitated diffusion glucose transporters (TGTP1 and TGTP2) from Taenia solium, the causal agent of human and porcine cysticercosis. Radio-isotope labelled hexose uptake mediated by TGTP1 expressed in Xenopus oocytes is inhibited by the natural stereoisomers D-glucose and D-mannose but not by L-glucose. Transport by TGTP1 is sensitive to classical inhibitors of facilitated diffusion such as phloretin and cytochalasin B, and insensitive to ouabain. TGTP2 did not function in Xenopus oocytes. Localization studies using specific anti-TGTP1 and anti-TGTP2 antibodies show that TGTP1 is abundant in a number of structures underlying the tegument in adult parasites and larvae, whereas TGTP2 appears to be localized only on the tegumentary surface of the larvae and is not detected in adults.

Amino Acid Sequence↗

PubMed1998

Host cells in the spiral canal of Taenia solium (Cestoda) cysticerci.

The presence of host inflammatory cells inside the spiral canal of all viable Taenia solium cysts obtained from naturally infected pigs is described. Cells can penetrate into the vicinity of suckers and rostellum, although most appear damaged, suggesting that conditions in the canal are deleterious for them. These observations extend the localization of host inflammatory infiltrate to this intricate microniche, which may offer new approaches for the treatment of cysticercosis, based on a scolex-targeted action. The presence of host cells in the canal of cysts also poses the problem of the resulting contamination with host materials in studies using cysts extracts. As an example, host DNA contamination is readily detectable in genomic DNA isolated from T. solium and Taenia taeniaeformis cysts, as demonstrated by polymerase chain reaction amplification and subsequent sequencing of a segment of the 18S ribosomal gene.

Animals↗