Biomedical subjects

H Toledo

Publications and source records attributed to H Toledo.

15 recordsLinked to original sources

PubMed2001

A phase I clinical trial of a multi-epitope polypeptide TAB9 combined with Montanide ISA 720 adjuvant in non-HIV-1 infected human volunteers.

A phase I clinical trial was performed to examine the safety and immunogenicity of a multi-epitope polypeptide comprising the central 15 amino acids of the V3 loop from six HIV-1 isolates. This protein called TAB9 was emulsified in Montanide ISA720 (Seppic, Paris) and administered intramuscularly at doses of 0, 0.2 and 1 mg to 24 healthy, HIV-1 seronegative adult males. Three immunisations were given at months 0, 1 and 6 in a randomised, double blind, placebo controlled clinical trial. The placebo was generally well tolerated. However, severe local reactions were observed in TAB9 vaccinated subjects after the second and third inoculations. Seven out of eight volunteers from the lower dose group showed moderate or severe local inflammation, while four out of eight subjects from the higher dose group developed granulomas and sterile abscesses. In general, the reactogenicity depended on the number of inoculations given and the dose of TAB9. Both doses were immunogenic, all immunised volunteers seroconverted and antibodies were broadly reactive against the V3 peptides included in the protein. All vaccine's sera reacted against gp120 in Western blot and 50% of them also neutralised at least one out of five laboratory isolates tested. No differences between doses were found. Anti TAB9 lymphoproliferative responses were observed, being more intense in the high dose group. Due to the strong local reactions that were found in this study, a change in the formulation will be required for further trials with this vaccine candidate in humans.

AIDS Vaccines↗

PubMed2000

[Semont maneuver and vestibular rehabilitation exercises in the treatment of benign paroxysmal postural vertigo. A comparative study].

BACKGROUND: Benign paraoxysmal postural vertigo (BPPV) is one of the most frequent causes of peripheral dizziness. Treatment based on vestibular rehabilitation exercises (VRE) is effective in 90% of the cases in an interval of 3 to 4 weeks. This treatment however is often abandoned by the patient. The only therapeutic maneuvers (based on otolyte release) are equally effective but present a high medium term recurrence. AIM: To compare the efficacy of the Semont maneuver (SM), the VRE and the combination of both in the treatment of BPPV at three months of follow up. MATERIAL AND METHODS: Forty patients with the clinical and electronystagmographic diagnosis of BPPV were divided into three groups: 1. SM, 2. VRE and 3. SM + VRE. The results were compared in regard to the signs and symptoms observed in the three groups of patients at 15 days, one month and at three months of treatment. RESULTS: The SM was effective in 80% of the patients at 15 days of treatment versus 45% of those receiving only VRE. The third group of patients, receiving the combined treatment, demonstrated a cure in 100% of the cases when evaluated at three months while only 66% of the SM group were found to be asymptomatic at the same time period (p < 0.05). CONCLUSIONS: The SM is easy to perform, rapid and effective in the short term, however has high recurrence. The VRE are effective in the long term based on the patient persistence. Combination of the two treatment leads to symptom remission in 100% of the patients at three months of treatment.

Exercise↗

PubMed2000

[Acute myeloid leukemia in the adult. Results of the National Antineoplastic Drug Protocol at the Hospital del Salvador, 1990-1998].

BACKGROUND: The incidence of acute myeloid leukemia is 3 cases per 100,000 inhabitants/year and its five years event free survival is 15 to 20%. Since the incorporation of trans retinoic acid, event free survival of M3 acute myeloid leukemia is 80%. AIM: To report the results of acute myeloid leukemia treatment at the Hospital del Salvador, between 1990 and 1998. PATIENTS AND METHODS: The medical records of 117 patients (66 female, mean age 48.2 years), treated between 1990 and 1998 using PANDA protocol, were retrospectively reviewed. Immunophenotyping was done in 69 patients and cytogenetic studies were done in 65. RESULTS: Sixteen percent of patients had M3 acute myeloid leukemia. The most frequent phenotype was the association of DR, CD34 plus a panmyeloid marker. DR and CD34 were negative in seven of nine patients with M3 acute myeloid leukemia. Cariotype was abnormal in 78% of patients. Complete remission was achieved in 65% of cases with a 13% of failures. Early mortality was 21.3% and decreased to 6.1% in the last three years. Infections and coagulation disorders were the main causes of death. Mean survival was 10.5 months. Five years event free survival was 11%. In M3 acute myeloid leukemia, the figure is 50%. CONCLUSIONS: Treatment results are less effective than protocols that consider more aggressive chemotherapeutic protocols or bone marrow transplantation. The reduction in early mortality is due to a better management of febrile neutropenia.

Adolescent↗

PubMed1998

Molecular cloning, sequencing, and expression of a chemoreceptor gene from Leptospirillum ferrooxidans.

We have cloned and sequenced a 2,262-bp chromosomal DNA fragment from the chemolithoautotrophic acidophilic bacterium Leptospirillum ferrooxidans. This DNA contained an open reading frame for a 577-amino-acid protein showing several characteristics of the bacterial chemoreceptors and, therefore, we named this gene lcrI for Leptospirillum chemotaxis receptor I. This is the first sequence reported for a gene from L. ferrooxidans encoding a protein. The lcrI gene showed both sigma 28-like and sigma 70-like putative promoters. The LcrI deduced protein contained two hydrophobic regions most likely corresponding to the two transmembrane regions present in all of the methyl-accepting chemotaxis proteins (MCPs) which make them fold with both periplasmic and cytoplasmic domains. We have proposed a cytoplasmic domain for LcrI, which also contains the highly conserved domain (HCD region), present in all of the chemotactic receptors, and two probable methylation sites. The in vitro expression of a DNA plasmid containing the 2,262-bp fragment showed the synthesis of a 58-kDa protein which was immunoprecipitated by antibodies against the Tar protein (an MCP from Escherichia coli), confirming some degree of antigenic conservation. In addition, this 58-kDa protein was expressed in E. coli, being associated with its cytoplasmic membrane fraction. It was not possible to determine a chemotactic receptor function for LcrI expressed in E. coli. This was most likely due to the fact that the periplasmic pH of E. coli, which differs by 3 to 4 pH units from that of acidophilic chemolithotrophs, does not allow the right conformation for the LcrI periplasmic domain.

Amino Acid Sequence↗

PubMed1997

Defective neutrophil function in workers occupationally exposed to hexachlorobenzene.

In this work we have studied the respiratory burst and chemotaxis of polymorphonuclear leukocytes from 51 workers exposed to chlorinated compounds, which were compared with those of non-exposed, age- and sex-matched individuals. These two neutrophil functions were significantly reduced as compared to controls. No correlation was observed between the length of exposure, hexachlorobenzene (HCB) blood concentrations and neutrophil chemotaxis or the extent of nitroblue tetrazolium reduction.

Adult↗

PubMed1994

BiP is a substrate for src kinase in vitro.

In a study to investigate the ability of chaperones to modulate src kinase activity, it was observed that BiP, a member of the HSP70 family found in the endoplasmic reticulum, is an excellent substrate for src kinase in vitro. The reaction requires polylysine and the results suggest that two tyrosine residues are phosphorylated. Although there is no evidence for this reaction in vivo, it does provide a very efficient method to label BiP.

Carrier Proteins↗

PubMed1993

Dissociation of glucose-regulated protein Grp78 and Grp78-IgE Fc complexes by ATP.

Recent studies have shown that ATP can dissociate dimers of the glucose-regulated protein Grp78 to monomers. In the present study, we have used purified recombinant Grp78 from Escherichia coli to investigate this reaction in more detail. During the course of the Grp78 dimer-monomer conversion, a stable Grp78 monomer-ATP complex is formed. Upon removal of the ATP, the Grp78 dimer is reformed. ADP, nonhydrolyzable ATP analogues, and GTP do not effect the dissociation of Grp78 dimers. A cell line that overproduces IgE Fc has been used to examine the nature of the Grp78-IgE Fc complexes present and the effect of ATP on them. Grp78-IgE Fc complexes ranging from 100 kDa to 300 kDa were observed by sucrose gradient analysis, suggesting that aggregate forms of Grp78 may be present in some of these complexes. Treatment of the extracts with ATP resulted in release of a Grp78 monomer from the complex. These results suggest that the dissociation of Grp78 oligomers by ATP may be involved in the function of Grp78 in protein translocation through the endoplasmic reticulum.

Adenosine Triphosphate↗

PubMed1992

Chemotaxis of Leptospirillum ferrooxidans and other acidophilic chemolithotrophs: comparison with the Escherichia coli chemosensory system.

Ni2+, Fe2+ and Cu2+ were attractants and aspartate was an apparent repellent for Leptospirillum ferrooxidans, a behaviour opposite to that for Escherichia coli. Membranes from L. ferrooxidans contained proteins with a molecular mass in the range of 80 kDa which were methylated in vitro. Methylation was stimulated in the presence of a membrane-free extract from E. coli, showing the response pattern expected for L. ferrooxidans, increased methylation by Ni2+, and demethylation by aspartate. This suggests the existence of sensory transducers having a common methylation domain with the E. coli methyl-accepting chemotaxis proteins. Total chromosomal DNA digests from L. ferrooxidans, Thiobacillus ferrooxidans and T. thiooxidans hybridized with probes containing different domains of the tar gene from E. coli, implying the presence of tar type genes in the acidophilic bacteria studied.

Bacterial Proteins↗

PubMed1992

Interactions of liver Grp78 and Escherichia coli recombinant Grp78 with ATP: multiple species and disaggregation.

The hamster gene encoding the 78-kDa glucose-regulated protein (Grp78) was expressed in Escherichia coli as a fusion protein with glutathione S-transferase. After induction with isopropyl beta-D-thiogalactopyranoside, the recombinant Grp78 was purified to homogeneity by affinity column chromatography of the fusion protein followed by thrombin cleavage. The purified recombinant protein was compared with liver Grp78 for its ability to interact with ATP. Like liver Grp78, the recombinant protein contained a weak ATPase activity and a Ca(2+)-stimulated autophosphorylation activity. However, unlike liver Grp78, in which the autophosphorylation reaction is stimulated less than 50% by CaCl2, the reaction with the recombinant Grp78 was stimulated about 15-fold in the presence of Ca2+. Although the liver protein showed at least four isoforms after two-dimensional gel electrophoresis, the recombinant Grp78 had one major species corresponding to the most basic form seen in liver. Both the liver Grp78 and the recombinant protein existed primarily as monomers and dimers. A small amount of oligomers was also present in the liver Grp78. When either protein was incubated with ATP, there was a conversion of the higher molecular weight species to the monomeric form.

Adenosine Triphosphatases↗

PubMed1992

Autophosphorylation of 70 kDa heat shock proteins.

Several members of the 70 kDa heat shock protein group are known to be phosphorylated in vivo and have recently been found to undergo a Ca(2+)-stimulated autophosphorylation. The characteristics of the autophosphorylation reaction with Escherichia coli DnaK the mitochondrial and chloroplast homologs, and the endoplasmic reticulum Bip/Grp78 are discussed. Some common features are a requirement for Ca2+, inhibition by Mg2+ and phosphorylation solely on a threonine residue. Although the role of autophosphorylation of these proteins is not clear, it is known that the level of phosphorylation of some Hsp70 proteins in vivo is responsive to stress and other cellular conditions.

Calcium↗

PubMed1991

Calcium-dependent autophosphorylation of the glucose-regulated protein, Grp78.

The characteristics of phosphorylation of the 78-kDa glucose-regulated protein (Grp78), also known as the immunoglobulin heavy chain binding protein, were studied in vitro and in vivo. The purified protein from either calf liver or bovine kidney cells (MDBK) could be phosphorylated in vitro with [gamma-32P]ATP, in a reaction that is stimulated by Ca2+ and inhibited by the Ca(2+)-chelator ethylene glycol bis(beta-aminoethyl ether)N,N'-tetraacetic acid (EGTA). In the presence of EGTA, excess Ca2+ increased the rate of phosphorylation about 18-fold. Based on EGTA/Ca2+ titrations, the optimal Ca2+ concentration for phosphorylation was estimated to be 10-50 microM. Other divalent cations such as Mg2+, Mn2+, and Zn2+ were found to be inhibitory as was the Ca2+ antagonist lanthanum (La3+). The in vivo phosphorylation of Grp78 was studied in MDBK cells labeled with 32Pi. In the presence of inducers of Grp78 synthesis, such as ionomycin, tunicamycin, or 2-deoxyglucose, there was a large increase in the level of Grp78 in the cells but a decrease in the amount of phosphorylated protein. Two-dimensional gel analysis of Grp78 purified from bovine liver and MDBK cells identified at least four isoforms. After in vivo and in vitro phosphorylation of Grp78 all the acidic isoforms contained radioactivity but not the most basic isoform. Phosphoamino acid analysis of Grp78 showed that serine and threonine were phosphorylated in vivo and only threonine was phosphorylated in vitro.

Adenosine Triphosphate↗

PubMed1990

In vivo and in vitro methylation of the elongation factor EF-Tu from Euglena gracilis chloroplast.

Based on amino acid sequence similarities between the methylated elongation factor EF-Tu from Escherichia coli and the EF-Tu from Euglena gracilis chloroplast, we predicted that the latter could also be methylated in the presence of an appropriate methyltransferase. We found that, as reported for the eubacterial homologous protein, the organellar factor could be methylated in vivo and in vitro to yield monomethyllysine.

Amino Acid Sequence↗

PubMed1988

Methylation of proteins from the translational apparatus: an overview.

Several of the translational apparatus proteins are methylated in all kinds of organisms. Although most of the modified proteins play key roles during protein biosynthesis, the biological function of these chemical modifications still remains elusive. Our recent data indicate a highly conserved pattern of ribosomal protein methylation in eubacteria, with methylated proteins being both structurally and functionally homologous in several microorganisms. Chloroplast ribosomes also appear to have a rather eubacterial pattern of ribosomal protein methylation. On the other hand, there is an apparently ubiquitous methylation of some of the translational factors in several organisms. These findings suggest an important, albeit unknown role for the post-synthetic methylation of the translational machinery. The analysis of the sequences of known methylation target sites and the search of similar sites in other proteins of known sequence, allows to predict those ribosomal proteins or translational factors that may be subjected to post-translational modifications with one or more methyl groups. Although a definitive answer with respect to the biological role of these N-methylations is still missing, a direct correlation between the methylation of some proteins and their biological activity is just beginning to emerge.

Amino Acid Sequence↗

PubMed1987

Lactitol, a second-generation disaccharide for treatment of chronic portal-systemic encephalopathy. A double-blind, crossover, randomized clinical trial.

A double-blind crossover trial was performed to test the therapeutic usefulness and safety of lactitol, a beta-galactoside sorbitol, against lactose in 18 patients with chronic portal-systemic encephalopathy (PSE). The study included four periods: two for washout and two for lactitol and lactose administration. During washout periods, which lasted two weeks each, patients were stabilized with neomycin plus milk of magnesia. Lactitol and lactose were administered during four weeks each. Ten patients were randomly assigned to receive lactose (group A) and eight patients to receive lactitol (group B) first. PSE parameters, ie, mental state, number connection test performance, asterixis and blood ammonia levels were assessed fortnightly. Electroencephalographic tracings and stool pHs were evaluated at the end of each study period. After the first administration of lactose and lactitol, no statistically significant differences in PSE parameters were found. At the same stage, a significant stool acidification (P less than 0.05) was detected. It is concluded that lactitol seems to be safe and efficacious in treating patients with chronic PSE.

Clinical Trials as Topic↗

PubMed1985

In vitro methylation of the elongation factor EF-Tu from Escherichia coli.

The in vitro methylation of the elongation factor EF-Tu from Escherichia coli was investigated. The methylation of newly synthesized EF-Tu was obtained using lambda rifd 18 DNA as template and S-adenosyl [methyl-3H]methionine as methyl donor. About 3 mol methyl residues were incorporated for every 10 mol EF-Tu synthesized. Analysis of the nature of the methyl-containing residues by protein hydrolysis followed by paper chromatography showed that both mono- and dimethyllysine were present. The methylation of EF-Tu was also studied separately from its synthesis by using cell-free systems with artificially undermethylated components.

Cell-Free System↗