RESUMO
FcγRIIA binding to IgG subclasses with different levels of affinity is influenced by the polymorphism in the gene that encodes this receptor. The substitution of arginine (R) for histidine (H) in the 131 position defines three allelic patterns, H/H, R/R, and H/R, resulting in FcγRIIA-H/H131 affinity for IgG2 and higher affinity for IgG3 subclasses. Studies have shown the importance of genetic host factors in leishmaniasis and participation of FcγRs on the macrophage infection by amastigote forms and in the immune response to Leishmania sp. We analysed the influence of allelic diversity patterns of the receptor FcγRIIA on American tegumentary leishmaniasis (ATL). FcγRIIA-H/R131 polymorphism was determined by PCR followed by an allele-specific enzymatic digestion in 88 individuals with ATL and 98 healthy volunteer blood donors (control group). The genotypic and allelic distributions of FcγRIIA-H/R131 were similar among the studied groups as well in mild and severe clinical forms of ATL. Our results suggest no association between this allelic polymorphism and susceptibility or resistance to ATL, neither influencing the development of different clinical forms of this illness.
Assuntos
Leishmaniose Cutânea/genética , Polimorfismo Genético , Receptores de IgG/genética , Adolescente , Adulto , Idoso , Alelos , Estudos de Casos e Controles , Criança , Feminino , Frequência do Gene/genética , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
The objective of the study was to evaluate the frequency and clinical characteristics of ocular complications and their risk factors, as well as autologous serum tears (AST) for the treatment of dry eye in these patients. Data from the files of 124 patients who had undergone allogeneic haematopoietic progenitor cell transplantation (HPCT) were evaluated. In addition, 33 HPCT patients were examined and their data were compared with controls. Analysis of tears and AST was performed. Dry eye manifestation occurred in 32% of patients and was positively correlated with age over 27 years (P = 0.05), peripheral blood progenitor cell transplant (P = 0.002), chronic graft-versus-host disease (P = 0.0027), and chronic or acute myeloid leukaemia (P = 0.001). Dry mouth and Schirmer test < 5 mm were predictive factors for dry eye in HPCT patients (P = 0.002 and odds ratio 3.9 and P = 0.007, odds ratio = 5.9, respectively). Microbiological analysis revealed that six of 11 AST samples were contaminated after 30 days of use. The present study supports the role of potential risk factors for ocular complications and key elements to detect alterations in the tear film from HPCT patients. In addition, AST contamination must be considered after longer periods of use.
Assuntos
Síndromes do Olho Seco , Transplante de Células-Tronco Hematopoéticas/efeitos adversos , Soluções Oftálmicas/uso terapêutico , Soro , Adolescente , Adulto , Fatores Etários , Criança , Síndromes do Olho Seco/tratamento farmacológico , Síndromes do Olho Seco/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Soluções Oftálmicas/química , Soluções Oftálmicas/isolamento & purificação , Fatores de RiscoRESUMO
The merozoite surface protein-1 (MSP-1) is a major vaccine candidate for the asexual blood stage of malaria. We examined both the extent of sequence diversity in block 17, the 3' end of Msp-1 gene coding for a 19-kDa polypeptide (MSP-1(19)) putatively involved in red blood cell binding, and the patterns of linkage disequilibrium between polymorphic sites throughout the Msp-1 locus. The parasite population sample consisted of Plasmodium falciparum isolates collected between 1985 and 1998 in Rondjnia, an area of hypoendemic malaria transmission in the southwestern Brazilian Amazon. Results were summarized as follows. (1) Seven block-17 sequence variants or haplotypes were found among 130 isolates, including two new haplotypes (novel combinations of previously reported amino acid replacements), here named Brazil-1 (E-TSR-F) and Brazil-2 (Q-TSR-F). (2) As previously shown for other Msp-1 polymorphisms, frequencies of block-17 haplotypes displayed significant temporal variation. (3) Extensive linkage disequilibrium was demonstrated between neighboring dimorphic sites within block 17, as well as between polymorphisms at the 5' and 3' ends of Msp-1 (map distance range: 3.83-4.99 kb). (4) The overall patterns of linkage disequilibrium within Msp-1 remained stable over a period of nearly one decade, and examples of possible 'epidemic' expansion of parasites carrying particular Msp-1 alleles were found in the 1980s and 1990s. These results are discussed in relation to the population biology of P. falciparum and the development of malaria vaccines based on MSP-1.
Assuntos
Variação Genética , Desequilíbrio de Ligação , Proteína 1 de Superfície de Merozoito/genética , Plasmodium falciparum/genética , Alelos , Sequência de Aminoácidos , Animais , Brasil/epidemiologia , Haplótipos , Humanos , Vacinas Antimaláricas , Dados de Sequência Molecular , Plasmodium falciparum/classificação , Reação em Cadeia da Polimerase/métodos , Fatores de TempoRESUMO
The polymorphic merozoite surface protein-2 (MSP-2) of Plasmodium falciparum is a major malaria-vaccine candidate. In the present study, PCR and hybridization with allelic-specific probes were used to type the Msp-2 gene from isolates from hypo-endemic Brazil (N = 113), meso-endemic Vietnam (N = 208) and holo-endemic Tanzania (N = 67). The typing methods were designed to group isolates into the dimorphic allelic families FC27 and IC1 and to detect possible between-family recombination events. The analysis was complemented by a comparison of 156 Msp-2 sequences from the GenBank database with 12 additional sequences obtained during the present study. Statistically significant differences were detected in pair-wise comparisons of the distribution of Msp-2 allelic types in Brazil and Vietnam, and in Brazil and Tanzania, but not in Vietnam and Tanzania. The extent of allelic diversity in the Msp-2 gene, as estimated by the total number of different alleles found in a given parasite population and the mean multiplicity of infections, clearly paralleled the levels of malaria endemicity in the study areas. However, no correlation between age and multiplicity of infections was found in the subjects. The patterns of Msp-2 diversity in Brazil appeared to be temporally stable, since no significant difference was observed in the distribution of Msp-2 allelic types among isolates collected, 10--13 years apart, in the same area of Rondônia. Despite the extensive sequence diversity found in Msp-2 alleles, especially in the central repetitive region of the molecule, several instances of identical or nearly identical alleles were found among isolates from different countries and regions, possibly as a result of extensive homoplasy. No recombinant allele was detected by molecular typing in any of the study sites, and the GenBank database included only 12 recombinant sequences (representing 7% of all reported Msp-2 sequences), all of them with an IC1-type 5' end and an FC27-type 3' end. A single, putative, crossover site was characterised for all recombinant alleles. Most of the allelic diversity observed was therefore attributable to variation in the repetitive region of the gene, instead of recombination between alleles of dimorphic families (as commonly found, for example, in the Msp-1 gene). The implications of these findings for studies on the genetic and antigenic diversity of malarial parasites are discussed.
Assuntos
Alelos , Antígenos de Protozoários/genética , Vacinas Antimaláricas/genética , Malária Falciparum/prevenção & controle , Plasmodium falciparum/genética , Proteínas de Protozoários/genética , Adolescente , Adulto , Idoso , Animais , Brasil/epidemiologia , Criança , Pré-Escolar , DNA de Protozoário/análise , Doenças Endêmicas , Feminino , Variação Genética , Humanos , Lactente , Malária Falciparum/epidemiologia , Masculino , Pessoa de Meia-Idade , Sondas de Oligonucleotídeos , Plasmodium falciparum/imunologia , Reação em Cadeia da Polimerase , Polimorfismo Genético , Análise de Sequência de DNA , Estatísticas não Paramétricas , Tanzânia/epidemiologia , Vietnã/epidemiologiaRESUMO
PURPOSE: To investigate whether elevated erythrocyte Na+/Li+ countertransport (Na+/Li+ CT) activity is present in patients with proliferative diabetic retinopathy (PDR). METHODS: The rate of Na+/Li+ CT activity assayed in 21 patients with type 1 diabetes mellitus (DM) presenting PDR was compared with 10 patients with nonproliferative retinopathy (NPDR) and with 11 patients with normal fundi. Twelve normal volunteers with no family history of hypertension were used as a control group. The albumin excretion rate was determined by nephelometry, and the glomerular filtration rate was measured by the plasma clearance of eidetic acid labeled with chromium-51. RESULTS: Patients with PDR showed higher diastolic blood pressure levels (mean +/- SD) compared with those with NPDR or normal fundi (95 +/- 13 versus 90 +/- 09 and 82 +/- 19 mm Hg, P = 0.02, respectively). The albumin excretion rate was higher [geometric mean (range)], and the glomerular filtration rate was lower (mean +/- SD) in patients with PDR than in those with NPDR or normal fundi [333 (2 to 5140) versus 32 (5.9 to 2200) and 6 (1.5 to 306) microg/min, P = 0.01, and 63 +/- 33 versus 99 +/- 37 and 93 +/- 43 ml/min, P = 0.02, respectively]. The mean Na+/Li+ CT in patients with PDR was significantly higher than in patients with NPDR or normal fundi and control group (0.46 +/-0.20 versus 0.32 +/- 0.12, 0.32 +/- 11, and 0.21 +/- 0.07 mM/L red blood cells (RBC)/h, respectively, P = 0.0001). In a multiple logistic regression analysis, with PDR as the dependent variable, Na+/Li+ CT (odds ratio [OR]: 4.7, confidence interval [CI]: 1.2-17.6, P = 0.02), diastolic blood pressure (OR, 3.4; CI, 1.3 to 9.6; P = 0.018), and glomerular filtration rate (OR, 5.1; CI, 1.6-17.7; P = 0.007) were the only variables that were maintained in the equation, indicating that they were the main determinants of PDR. CONCLUSIONS: Patients with type 1 DM and proliferative retinopathy have elevated erythrocyte Na+/Li+ CT.
Assuntos
Antiporters/metabolismo , Diabetes Mellitus Tipo 1/sangue , Retinopatia Diabética/sangue , Eritrócitos/metabolismo , Lítio/sangue , Sódio/sangue , Adolescente , Adulto , Pressão Sanguínea , Feminino , Taxa de Filtração Glomerular , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
The polymorphic, merozoite surface protein-1 (MSP-1) of Plasmodium falciparum, an antigen of the parasite's asexual blood-stages, is a major malaria-vaccine candidate. Nucleotide sequences of each variable domain or block of this antigen may be grouped into one of three possible allelic types (K1, MAD20 and RO33), and 24 major types of the msp-1 gene may be defined, as unique combinations of allelic types in these variable blocks. Isolates collected from the Brazilian Amazon, over a period of 14 years, have now been investigated, by PCR-based typing of the msp-1 gene. Thirteen of the 24 possible gene-types were identified, and 336 P. falciparum clones were fully typed among 239 isolates. Most parasites (87%) belonged to one of the seven most frequent gene-types. Marked temporal variation in the distribution of msp-1 variants was found when comparing parasites sampled in the same sites at intervals of at least 5 years. Spatial variations were also found when comparing parasites from both neighbouring and distant sites within the Amazon Basin. The between-population variance in the frequencies of msp-1 allelic types found in Brazil, as estimated by Wright's FST statistic, is of similar magnitude to that found in previous world-wide comparisons. The potential implications of these findings for the development of an MSP-1-based, multivalent malaria vaccine are discussed.
Assuntos
Proteína 1 de Superfície de Merozoito/genética , Plasmodium falciparum/genética , Alelos , Animais , Brasil , Variação Genética , Humanos , Plasmodium falciparum/classificação , Reação em Cadeia da Polimerase/métodos , Fatores de TempoRESUMO
The polymorphic merozoite surface protein (MSP-1) of Plasmodium falciparum is a major asexual blood-stage malaria vaccine candidate. The impact of allelic diversity on recognition of MSP-1 during the immune response remains to be investigated in areas of hypoendemicity such as the Brazilian Amazon region. In this study, PCR was used to type variable regions, blocks 2, 4, and 10, of the msp-1 gene and to characterize major gene types (unique combinations of allelic types in variable blocks) in P. falciparum isolates collected across the Amazon basin over a period of 12 years. Twelve of the 24 possible gene types were found among 181 isolates, and 68 (38%) of them had more than one gene type. Temporal, but not spatial, variation was found in the distribution of MSP-1 gene types in the Amazon. Interestingly, some gene types occurred more frequently than expected from random assortment of allelic types in different blocks, as previously found in other areas of endemicity. We also compared the antibody recognition of polymorphic (block 2), dimorphic (block 6), and conserved (block 3) regions of MSP-1 in Amazonian malaria patients and clinically immune Africans, using a panel of recombinant peptides. Results were summarized as follows. (i) All blocks were targeted by naturally acquired cytophilic antibodies of the subclasses IgG1 and IgG3, but the balance between IgG1 and IgG3 depended on the subjects' cumulative exposure to malaria. (ii) The balance between IgG1 and IgG3 subclasses and the duration of antibody responses differed in relation to distinct MSP-1 peptides. (iii) Antibody responses to variable blocks 2 and 6 were predominantly type specific, but variant-specific antibodies that target isolate-specific repetitive motifs within block 2 were more frequent in Amazonian patients than in previously studied African populations.