V3 peptide binding pattern and HIV-1 transmission route in Rio de Janeiro

To characterize antibody binding to a panel of V3 loop peptides representing diverse HIV-1 neutralization epitopes, 149 HIV-1 infected individuals from Rio de Janeiro (RJ) were investigated. Results were analyzed with respect to risk factors for infection and other epidemiological and clinical data. Peptide reactivity was not associated with sex, clinical status, CD4 counts, antigenemia or ß2-microglobulin serum level. A segregation of peptide reactivity according to route of infection was encountered. This finding suggests that more then one viral strain may be circulating in RJ, in subjects with different risk factors for HIV-1 infection. An investigation of prevalent HIV-1 genotypes, serotypes and immunotypes may be of importance for the design and selection of potential vaccines to be used in Brazil as well as for the selection of populations to be included in future vaccine efficacy trials.

A GBP 130 derived peptide from Plasmodium falciparum binds to human erythrocytes and inhibits merozoite invasion in vitro

The malarial GBP 130 protein binds weakly to intact human erythrocytes; the binding sites seem to be located in the repeat region and this region's antibodies block the merozoite invasion. A peptide from this region (residues from 701 to 720) which binds to human erythrocytes was identified. This peptide named 2220 did not bind to sialic acid; the binding site on human erythrocyte was affected by treatment with trypsin but not by chymotrypsin. The peptide was able to inhibit Plasmodium falciparum merozoite invasion of erythrocytes. The residues F701, K703, L705, T706, E713 (FYKILTNTDPNDEVERDNAD) were found to be critical for peptide binding to erythrocytes.

Hemopressin: a novel bioactive peptide derived from the alpha1-chain of hemoglobin

Hemopressin (PVNFKFLSH), a novel bioactive peptide derived from the alpha1-chain of hemoglobin, was originally isolated from rat brain homogenates. Hemopressin causes hypotension in anesthetized rats and is metabolized in vivo and in vitro by endopeptidase 24.15 (EP24.15), neurolysin (EP24.16), and angiotensin-converting enzyme (ACE). Hemopressin also exerts an antinociceptive action in experimental inflammatory hyperalgesia induced by carrageenin or bradykinin via a mechanism that is independent of opioids. These findings suggest that this peptide may have important regulatory physiological actions in vivo.

Immunostimulatory property of a synthetic peptide belonging to the soluble ATP diphosphohydro-lase isoform (SmATPDase 2) and immunolocalisation of this protein in the Schistosoma mansoni egg

A peptide (SmB2LJ; r175-194) that belongs to a conserved domain from Schistosoma mansoni SmATPDase 2 and is shared with potato apyrase, as predicted by in silico analysis as antigenic, was synthesised and its immunostimulatory property was analysed. When inoculated in BALB/c mice, this peptide induced high levels of SmB2LJ-specific IgG1 and IgG2a subtypes, as detected by enzyme linked immunosorbent assay. In addition, dot blots were found to be positive for immune sera against potato apyrase and SmB2LJ. These results suggest that the conserved domain r175-194 from the S. mansoni SmATPDase 2 is antigenic. Western blots were performed and the anti-SmB2LJ antibody recognised in adult worm (soluble worm antigen preparation) or soluble egg antigen antigenic preparations two bands of approximately 63 and 55 kDa, molecular masses similar to those predicted for adult worm SmATPDase 2. This finding strongly suggests the expression of this same isoform in S. mansoni eggs. To assess localisation of SmATPDase 2, confocal fluorescence microscopy was performed using cryostat sections of infected mouse liver and polyclonal antiserum against SmB2LJ. Positive reactions were identified on the external surface from the miracidium in von Lichtenberg's envelope and, in the outer side of the egg-shell, showing that this soluble isoform is secreted from the S. mansoni eggs.

Ablação curativa da fibrilação atrial: comparação entre sedação profunda e anestesia geral

OBJETIVO: Comparar sedação profunda com anestesia geral para ablação curativa de fibrilação atrial. MÉTODOS: Estudo prospectivo, aleatório, com 32 pacientes, idades entre 18 e 65 anos, ASA 2 e 3, IMC d" 30kg/m², distribuídos em dois grupos: sedação profunda (G1) e anestesia geral (G2). Todos receberam midazolan (0,5mg/kg) venoso. O G1 recebeu propofol (1mg/kg) e máscara facial de O2, seguido da infusão contínua de propofol (25-50mg/kg/min) e remifentanil (0,01-0,05µg/kg/min). O G2 recebeu propofol (2mg/kg) e máscara laríngea com tubo de drenagem, seguido da infusão contínua de propofol (60-100mg/kg/min) e remifentanil (0,06-0,1µg/kg/min). Foram comparados: frequência cardíaca, pressão arterial invasiva, complicações, recidiva (desfecho) em três meses e gasometrias. RESULTADOS: Os pacientes do G1 apresentaram gasometrias arteriais com níveis de PaCO2 maiores e pH menores (p=0,001) e maior incidência de tosse. Ocorreu diminuição da PAM e FC no G2. Exceto a tosse, as complicações e recidivas foram semelhantes em ambos os grupos. CONCLUSÃO: Ambas as técnicas podem ser utilizadas para a ablação curativa da fibrilação atrial. A anestesia geral proporcionou menores alterações respiratórias e maior imobilidade do paciente.

Pressão arterial e concentração plasmática do peptídeo atrial natriurético e do peptídeo natriurético tipo B, em gestações complicadas pela pré-eclâmpsia

OBJETIVO: o estudo busca determinar a existência de associação entre a elevação da pressão arterial e os níveis plasmáticos dos peptídeos natriuréticos ANP e BNP, na gestação complicada pela pré-eclâmpsia. MÉTODOS: em estudo transversal caso-controle, pareado por idade gestacional, 25 grávidas normotensas e 61 portadoras de pré-eclâmpsia foram avaliadas quanto ao nível da pressão arterial e às concentrações plasmáticas dos peptídeos natriuréticos ANP e BNP. Exames clínico e laboratoriais foram realizados para o diagnóstico de pré-eclâmpsia, sendo a pressão arterial medida de forma não invasiva. As dosagens hormonais foram obtidas por radioimunoensaio, após extração em colunas Sep-pak C18. Os valores médios das concentrações plasmáticas do ANP e BNP foram comparados entre grupos com pressão arterial progressivamente maiores. A correlação entre os valores da pressão arterial e os níveis plasmáticos do ANP e BNP no sangue materno foi também investigada pela de análise de regressão no grupo completo de gestantes e em grupos específicos excluindo-se a hipertensão anterior à gestação e, em seguida, excluindo-se aquelas sem hipertensão prévia. RESULTADOS: os valores plasmáticos de ANP foram 41.5±7.3, 78.4±13.1 e 89.2±13.4 pg/mL (p<0,00001) e os de BNP plasmático foram 79.5±15.8, 176.7±42.2 e 208.3±63.5 pg/mL (p=0,005), respectivamente, para os grupos de pressão arterial média =107 mmHg, 107-139 mmHg e =140 mmHg. Verificou-se correlação positiva entre as concentrações plasmáticas do ANP e os níveis pressóricos na pré-eclâmpsia, independente da existência de estado hipertensivo prévio à gestação (p<0,0001 para pré-eclâmpsia e p<0,01 para pré-eclampsia sobreposta à hipertensão arterial crônica), ao passo que as dosagens de BNP não se mostraram associadas à pressão arterial no grupo com hipertensão arterial prévia à gestação (p=0,004 para pré-eclâmpsia e p=0,18 para pré-eclampsia sobreposta à hipertensão arterial crônica). CONCLUSÃO: o agravamento da hipertensão na pré-eclâmpsia correlacionou-se com as concentrações séricas do ANP e BNP, embora os valores do BNP possam ser influenciados pela existência de estado hipertensivo prévio.

Óxido nítrico e peptídeo atrial natriurético na predição de complicações da gestação

OBJETIVO: verificar a acurácia das dosagens séricas maternas do peptídeo atrial natriurético (ANP) e óxido nítrico (NO) para predição de complicações da gravidez. MÉTODOS: a casuística compreendeu 49 mulheres primigestas. As gestantes foram incluídas no estudo na 18ªsemana, momento em que foi coletada a amostra sangüínea para a realização das dosagens séricas. O ANP foi dosado pelo método de radioimunoensaio, utilizando kits Euro-dianostica (2000), considerando anormais valores superiores a 237,4 pg/mL (percentil 95). A dosagem do NO foi realizada pelo método de quimiluminescência, sendo considerados como anormais valores superiores a 17,8 µmol/L (percentil 95). Para análise estatística, utilizaram-se o teste t não pareado para a análise das variáveis quantitativas contínuas de distribuição normal; o teste de Mann-Whitney para amostras quantitativas não-paramétricas; o teste exato de Fisher na avaliação dos parâmentros qualitativos; e o teste de Pearson na avaliação das correlações. RESULTADOS: os dados não mostraram diferença significativa na concentração sérica do ANP, considerando o grupo que apresentou complicações gestacionais e/ou perinatais (média de 139,3±77,1 pg/mL) e o grupo controle (média de 119,6±47,0 pg/mlL), e nem na concentração sérica do NO, entre o grupo com complicações gestacionais e/ou perinatais (média de 11,1±4,6 µmol/L) e o grupo controle (média de 10,0±3,4 µmol/L). CONCLUSÕES: os resultados mostram que o ANP e o NO não foram bons indicadores de complicações da gestação.

A new brain metalloendopeptidase which degrades the Alzheimer ß-amyloid 1-40 peptide producing soluble fragments without neurotoxic effects

A new metalloendopeptidase was purified to apparent homogeneity from a homogenate of normal human brain using successive steps of chromatography on DEAE-Trisacryl, hydroxylapatite and Sephacryl S-200. The purified enzyme cleaved the Gly33-Leu34 bond of the 25-35 neurotoxic sequence of the Alzheimer ß-amyloid 1-40 peptide producing soluble fragments without neurotoxic effects. This enzyme activity was only inhibited by divalent cation chelators such as EDTA, EGTA and o-phenanthroline (1 mM) and was insensitive to phosphoramidon and captopril (1 µM concentration), specific inhibitors of neutral endopeptidase (EC 3.4.24.11) and angiotensin-converting enzyme (EC 3.4.15.1), respectively. The high affinity of this human brain endopeptidase for ß-amyloid 1-40 peptide (Km = 5 µM) suggests that it may play a physiological role in the degradation of this substance produced by normal cellular metabolism. It may also be hypothesized that the abnormal accumulation of the amyloid ß-protein in Alzheimer's disease may be initiated by a defect or an inactivation of this enzyme.

The C-peptide response to a standard mixed meal in a group of Brazilian type 1 diabetic patients

In order to analyze the different parameters used in the interpretation of C-peptide response in a functional test, we compared a group of 26 type 1 diabetics aged 21.1 ± 8.2 years, with a diabetes duration of 7.9 ± 6.7 months, with a group of 24 non-diabetic subjects aged 25.0 ± 4.4 years. A standard mixed meal of 317 kcal was used as a stimulus. Blood sampling for C-peptide determinations was performed at regular intervals. Although all the studied C-peptide variables were significantly lower in the diabetic group (P<0.0001), some overlapping of parameters was observed between the two groups. The highest degree of overlapping was found for basal value (BV) (30.8%) and percent increase (42.31%), and the lowest for incremental area, absolute increase, peak value (PV) (3.8%), and total area (7.7%) (c2 = 31.6, P<0.0001). We did not observe a definite pattern in the time of maximum response among the 21 diabetics who showed an increase in C-peptide levels after the stimulus. In this group, however, there was a highly significant number of late responses (120 min) (c2 = 5.7, P<0.002). Although BV showed a significant correlation with PV (rS = 0.95, P<0.0001), the basal levels of C-peptide did not differentiate the groups with and without response to the stimulus. We conclude that the diabetic group studied showed delayed and reduced C-peptide responses, and that the functional test can be an important tool for the evaluation of residual ß cell function.

Partial sequence and toxic effects of granulitoxin, a neurotoxic peptide from the sea anemone Bunodosoma granulifera

A neurotoxic peptide, granulitoxin (GRX), was isolated from the sea anemone Bunodosoma granulifera. The N-terminal amino acid sequence of GRX is AKTGILDSDGPTVAGNSLSGT and its molecular mass is 4958 Da by electrospray mass spectrometry. This sequence presents a partial degree of homology with other toxins from sea anemones such as Bunodosoma caissarum, Anthopleura fuscoviridis and Anemonia sulcata. However, important differences were found: the first six amino acids of the sequence are different, Arg-14 was replaced by Ala and no cysteine residues were present in the partial sequence, while two cysteine residues were present in the first 21 amino acids of other toxins described above. Purified GRX injected ip (800 µg/kg) into mice produced severe neurotoxic effects such as circular movements, aggressive behavior, dyspnea, tonic-clonic convulsion and death. The 2-h LD50 of GRX was 400 ± 83 µg/kg.

Liposomes: from biophysics to the design of peptide vaccines

Liposomes (lipid-based vesicles) have been widely studied as drug delivery systems due to their relative safety, their structural versatility concerning size, composition and bilayer fluidity, and their ability to incorporate almost any molecule regardless of its structure. Liposomes are successful in inducing potent in vivo immunity to incorporated antigens and are now being employed in numerous immunization procedures. This is a brief overview of the structural, biophysical and pharmacological properties of liposomes and of the current strategies in the design of liposomes as vaccine delivery systems.