Biomedical subjects
Publications and source records attributed to M R Lima.
The authors report a familial case of mosaicism for an extra ring 20, identified by fluorescence in situ hybridization (FISH), in a mother and her child. In spite of the fact that both patients had clinical abnormalities, the more severe phenotype present in the child was probably due to the higher percentage of abnormal cells. To our knowledge, this is the first report of a familial extra ring 20 mosaicism.
Diffusely adhering Escherichia coli (E. coli) strains (DAEC) represent a potential cause of diarrhoea in infants, and the detection of type three secretion system (TTSS) genes in DAEC would substantiate their pathogenic nature. In this work, four isolates of DAEC, recovered from stools of diarrhoeic children, were analysed by PCR, in order to detect the presence of TTSS genes. Primers targeted to the escC, escJ, escN and escV, some of the most conserved TTSS genes in enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC), were used in order to verify the occurrence of homologous genes in our DAEC isolates. By this approach, we were able to characterise DNA fragments corresponding to putative escJ and escN genes in all DAEC isolates. Furthermore, DNA fragments homologous to the escC and escV genes were also amplified from all isolates. Besides the similarity found among the DAEC esc homologues with EPEC and EHEC esc genes, the nucleotide sequence analysis of the flanking regions of the amplified DNA fragments suggests that the putative DAEC esc genes are organised in the same manner as observed in EPEC and in EHEC strains. The results described here provide strong evidence for the presence of a TTSS in the DAEC strains analysed, implicating a pathogenic nature of these isolates.
INTRODUCTION: Cardiovascular complications are the major cause of morbidity and mortality in Marfan syndrome (MS), a common connective tissue disorder. Currently it is considered that the prognosis and morphologic characteristics in infantile Marfan syndrome may be quite different from those reported in older patients. The objective of this study was to analyze the cardiovascular manifestations and evolution of the patients with Marfan syndrome followed at our pediatric cardiac unit. METHODS: The authors reviewed the clinical files of all the patients that fulfilled the diagnostic criteria for MS according to De Paepe et al. (1996). We analyzed the following parameters: gender, age at referral, race, family history, clinical examination, diagnostic exams, therapy and evolution. The patients were divided into two groups according to the age at diagnosis: infants (group 1) and older patients (group 2). RESULTS: Group 1 included 3 infants, two boys and one girl, sporadic cases, presenting congestive heart failure. The major cardiac diagnoses were aortic dilatation (1/3) and mitral valve prolapse with severe mitral regurgitation (2/3). Congenital heart disease was associated in two cases (patent ductus arteriosus and atrial septal defect). Two needed cardiac surgery at an early age and one was recently proposed for surgery. There were no deaths. Group 2 included 20 patients, 14 boys and 6 girls, first seen at a mean age of 8 years. Ten had a positive family history and none presented cardiac symptoms. The major cardiac manifestations were mitral valve prolapse (18/20) and aortic dilatation (17/20). There was no significant progression of the cardiac lesions, except for one case, during the 12 years of follow-up. CONCLUSION: Infantile MS presented high morbidity; mitral regurgitation was severe in two cases. All patients presented heart failure, two needing early operations. In classic MS evolution was favorable, and the commonest cardiac lesions were mitral valve prolapse and aortic dilatation. We emphasize the need for beta-blockers to prevent progression of aortic dilatation. The decision for surgery rests upon the severity of valve regurgitation and the rate of progression of aortic dilatation. It is important to inform patients and family about physical exercise, prevention of endocarditis, risks associated with pregnancy and genetic counseling.
A female is described with axial mesodermal dysplasia complex (AMDC) born to a consanguineous couple. This is thought to be the first description of a patient with AMDC born to consanguineous parents.
The cardiac manifestation usually associated with Tuberous Sclerosis is rhabdomyoma. The authors present a clinical case of Tuberous Sclerosis with the particular coexistence of congenital heart disease (mitral anomaly and pulmonary stenosis) and a single intracardiac rhabdomyoma that appeared at the age of four years.
A newborn male with the characteristic phenotype of classic rhizomelic chondrodysplasia punctata (RCDP) and with the usual and severe radiographic skeletal abnormalities is described. The parents were young, healthy, and not consanguineous; the mother had not used licit or illicit drugs, alcohol, or tobacco during pregnancy and had not been exposed to radiation or teratogenic chemicals. The clinical phenotype led us to study peroxisomal function. Plasmalogen content in erythrocytes, membrane, and fibroblasts; dihydroxyacetone phosphate acyltransferase (DHAP-AT), alkyldehydroxyaceton phosphate synthetase (a gift from Professor Henk van der Boch, Utrech) in fibroblasts; and phytanic and pristanic acids in plasma showed normal values. Immunocytofluorescence study with antibodies against peroxisomal membrane showed normal organelles. We found no reference in the literature of a case of RCDP with normal peroxisomal functions, but non-CDP has been described with peroxisomal dysfunction. This phenotype (RCDP) may be due to other metabolic error.
We have recently described that Trypanosoma cruzi parasites of the reticulotropic Y strain increase their resistance to antibody-induced clearance during their interaction with the vertebrate host immune system. In the present study, we observed that trypomastigotes of the myotropic CL strain isolated from normal host also display an increased resistance to immune clearance when compared to parasites obtained from immunosuppressed donors. Through fluorescence-activated cell sorting analysis, we have observed that the high expression of membrane-bound IgM antibodies on Y and CL trypomastigotes correlates with their enhanced resistance to Ig-induced clearance. Trypomastigotes from normal mice were essentially refractory to the in vitro binding of immunoglobulins, showing that their membrane structures were completely covered by IgM antibodies. These findings suggest that this isotype does not efficiently mediate immune clearance. Moreover, membrane-bound IgM antibodies limited the amount of IgG attached to the parasite and, as a consequence, impaired efficient immune clearance. Through this mechanism, trypomastigotes of T. cruzi could increase their persistence in the bloodstream thus favoring parasite transmission to its hematophagous host vector in the early acute phase of the disease.
Adult BALB/c male mice were injected with a single dose of ethyl nitroso urea (ENU; 250 mg/kg, i.p.) and mated to C57BL/6, DBA/2 and A/J adult females 13 weeks later. F1 males were mated with BALB/c females and F2 females were than backcrossed to the F1 parents. One BALB/c male mouse thus treated gave origin to a mutant presenting hair and skin alterations similar to those of natural hairless mutants. The new mutation is located on chromosome 14 near the Es10 locus, and probably at the same locus for the hairless mutation. Similar to the hairless mouse, this new mutant has a normal phenotype at birth and after three weeks starts to loose hair which is never replaced. Additionally, the skin becomes thickened and wrinkled. One feature that distinguishes this mutant from other hairless mice is the peculiar enlargement of its axillary and cervical lymph nodes. The new mutant develops membranoproliferative glomerulonephritis similar to the rhino mouse, one of the hairless allele mutants already described in the literature, but with a much later onset.
This paper discusses current evidence for the relationship between polyclonal lymphocyte activation, specific immunosuppression with decreased resistance, and autoimmune pathology, that are all often found associated with infections by a variety of virus, bacteria and parasites. The central question of class determination of immune effector activities is considered in the context of the cellular targets for nonspecific mitogenic activities associated with infection. A model is presented to integrate these findings: mitogens produced by the microorganism or the infected cells are preferentially active on CD5 B cells; the resulting over-production of IL-10 will tend to bias all immune activities into a Th2-mode of effector functions, with high titers of polyclonal antibodies and little or no production of gamma IFN and other "inflammatory" lymphokines that often mediate resistance. In turn, these conditions allow for parasite persistence and the corresponding long-term disregulation of self-directed immune reactivities, resulting in autoimmunity in the chronic phase. This model would predict that selective immunization with the mitogenic principles involved in deregulation, could stand better chances than strategies of vaccination based on immunopotentiation against other, functionally neutral antigenic epitopes. It is argued, however, that the complexity of immune responses and their regulation, together with our ignorance on the genetic controls of class-determination, offer poor prospects for a scientifically-based, rational development of vaccines in the near future. It is suggested that empirically-based and technologically developed vaccines might succeed, while basic scientific approaches are reinforced and given the time to provide a better understanding of those processes.
In the present work we report that susceptibility to Crotalus durissus terrificus venom: varies according to the strain of inbred mouse used. The s.c. LD50 for Balb/c and C57BI/6 mice were 193 micrograms/kg and 171 micrograms/kg, whereas for A/J and DBA/J they were 78 micrograms/kg and 74 micrograms/kg, respectively. In addition, a direct correlation between susceptibility to C. d. terrificus venom and creatine kinase serum levels (CK) was observed.
Parasite infection causes marked perturbations in the host immune system, as shown by hypergammaglobulinemia, autoimmunity and immune depression, but there is little information on the number, specificities and performance of B cell clones activated in the course of infection. We have addressed these questions in a model of murine malaria induced by Plasmodium chabaudi, where primary infection results in very marked B cell responses that shift in Ig isotype pattern in immunoprotected animals, and where immunity can be transferred to naive recipients by injection of serum from late, but not early, infection. We have quantitated B cells responding to infection in two distinct functional compartments, namely blast cells and Ig-secreting cells, and compared normal with immune animals. We have also determined the frequencies of clonal specificities towards several autoantigens (DNA, myosin, transferrin and red cells), non-self protein or polysaccharide antigens (KLH, levan and dextran), and parasite antigens in both compartments, by measuring blast cell reactivities in limiting dilution analyses and Ig secretion in ELISASPOT assays. This experimental design allowed us to assess the specificity of the B cell responses, to compare the clonal composition of these two B cell compartments, and to evaluate putative specific response regulation at the step of terminal differentiation. Our results show that, in this particular experimental system: (i) B cell responses in primary infection are truly non-specific while immune animals show a greater ability to control the massive non-specific response; (ii) parasite specific B cells, particularly those committed to IgG production, are selectively stimulated in immune individuals; (iii) autoreactive B cells are not selectively stimulated, but increased autoantibody production may result from perturbation in the control of terminal differentiation in the respective clones; (iv) clones with specificity to some non-self antigens (e.g. KLH and dextran) are selectively engaged and regulated, which might have implications for the immunosuppression following infection.
Antigenic cross-reactivity was studied among the components of venoms from nine species of the genus Bothrops using species-specific antivenoms. Sera titration by DOT-ELISA detected similar levels of antibody when either homologous or heterologous antigens were used. Transblotted antigens, after SDS-PAGE fractionation, were also revealed by homologous and heterologous antivenoms. Antigens with mol. wt greater than 30,000 seemed to be the most cross-reactive. Antigens of about 24,000 mol. wt were poorly immunogenic. Antigens between 14-18,000 mol. wt cross-reacted only with B. moojeni, B. jararacussu, B. neuwiedi and B. pradoi venoms. Neutralization of the lethality of B. jararaca venom was observed by homologous and heterologous antivenoms.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.