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Biomedical subjects

A Bartoloni

Publications and source records attributed to A Bartoloni.

At least 91 records · Page 5Linked to original sources
PubMed1990

Antimicrobial agent susceptibility patterns of staphylococci isolated in urban and rural areas of Bolivia.

Staphylococcal strains obtained from cutaneous swabs of hospital staff and school students of Camiri and Boyuibe and healthy people living in Javillo, Bolivia, were tested for their in-vitro antimicrobial susceptibility. The highest percentages of resistance to the antibiotics tested were found in staphylococcal strains isolated from hospital personnel. All the S. aureus strains from these subjects were resistant to penicillin. Coagulase-negative staphylococci from hospital personnel evidenced a high rate of multiresistant strains, mainly to penicillin, ampicillin, tetracycline, and chloramphenicol. The staphylococcal strains isolated in the rural population of Javillo were highly susceptible to all the antibiotics tested.

Anti-Bacterial Agents↗
PubMed1989

Mutants of pertussis toxin suitable for vaccine development.

Immunization with chemically detoxified pertussis toxin can prevent severe whooping cough with an efficacy similar to that of the cellular pertussis vaccine, which normally gives unwanted side effects. To avoid the reversion to toxicity and the loss of immunogenicity that may follow chemical treatment of pertussis toxin, inactive toxins were constructed by genetic manipulation. A number of genetically engineered alleles of the pertussis toxin genes, constructed by replacing either one or two key amino acids within the enzymatically active S1 subunit, were introduced into the chromosome of strains of Bordetella pertussis, B. parapertussis, and B. bronchiseptica. These strains produce mutant pertussis toxin molecules that are nontoxic and immunogenic and that protect mice from the intracerebral challenge with virulent Bordetella pertussis. Such molecules are ideal for the development of new and safer vaccines against whooping cough.

Animals↗
PubMed1989

Human T cell clones define S1 subunit as the most immunogenic moiety of pertussis toxin and determine its epitope map.

Human T lymphocyte clones specific for pertussis toxin (PT) were used to analyze the fine specificity of the response to PT, the basic component of new acellular vaccines against whooping cough. The majority (83%) of the clones specific for PT recognized S1, the subunit that in animal models has been shown to be highly immunogenic. To map T cell epitopes on S1, 18 S1-specific clones were tested for recognition of recombinant fragments representing NH2-terminal and COOH-terminal deletions of S1 and two recombinant S1 subunits containing amino acid substitutions. This approach led to the identification of three regions of the protein as the sequences containing T cell antigenic sites: 1-42, 181-211, and 212-235. Synthetic peptides were eventually used for a finer localization of the T cell epitopes. Two peptides, one of 13 residues (27-39) at the NH2 terminus and one of 24 residues (171-194) at the COOH terminus, stimulated proliferation of three and four clones, respectively. Both peptides are recognized in association with HLA DR1 molecules. These results stress the role of S1 in the immune response to PT and provide data useful for the development of a recombinant or synthetic antipertussis vaccine containing T cell epitopes from S1.

Amino Acid Sequence↗
PubMed1989

Studies of the antigenic structure of two cross-reacting proteins, pertussis and cholera toxins, using synthetic peptides.

Peptide fragments of pertussis toxin subunit 1 (PT-S1) have been synthesized in order to investigate their antigenic and immunogenic activity, and to evaluate their possible use as components of a new vaccine. Two peptides (sequence 73-82, EAERAGRGTG and sequence 107-116, YVDTYGDNAG) were selected for their predictable exposure on the surface of the molecule, and a third (8-18, YRYDSRPPEDV) for its homology with the sequence 6-16 of cholera toxin subunit A (CT-A 6-16) (YRADSRPPDEI). Antipeptide polyclonal antibodies produced in rabbits, were tested in different immunoassays for their ability to interact with toxin proteins. All of them proved interactive with recombinant PT-S1 (rPT-S1); CT-A interact not only, as expected, with anti 8-18 antibodies, due to the high homology between the two toxins in this region, but also, unexpectedly, with anti 107-116 antibodies, in spite of the lack of homology of this peptide with the entire CT. We also found a direct cross-reactivity between the two toxins: anti PT and anti rPT-S1 antibodies interacted with CT-A, whereas anti CT antibodies did not recognize PT. Antipertussis antibodies also recognized the peptide 8-18, which therefore represents at least a part of an antigenic determinant of the toxin, while no interaction could be evidenced between anti-cholera antibodies and any of the peptides, thus demonstrating important differences in the antigenic structures of the two toxins. None of the antipeptide antibodies examined showed protective activity against the toxins in a Chinese hamster ovary (CHO) cell test.

Amino Acid Sequence↗
PubMed1989

Parasitological observations on three Bolivian localities including rural communities, cities and institutions.

Three hundred of 381 subjects examined from the Camiri, Boyuibe and Gutierrez areas (Santa Cruz Department) harboured one to six species of intestinal helminths and/or protozoa. High infection rates were found in Camiri in the orphanage (43 of 44 persons) and in the Military Hospital (10 of 10 persons), as well as in Itanambicua (97.4%), a rural community close to the city (38 of 39 persons). No significant differences were noted between the overall parasitic prevalences observed in rural and urban environments, but the frequency of species was different. Indiscriminate defaecation, the habit of living in close association with animals, overcrowding, and especially lack of health education, are some of the factors responsible for the parasitic situation observed.

Adolescent↗
PubMed1989

The influence of ofloxacin versus trimethoprim-sulfamethoxazole on the aerobic flora in granulocytopenic subjects.

Ofloxacin (300 mg twice a day) and trimethoprim-sulfamethoxazole (TMP-SMZ) (160 mg trimethoprim and 800 mg sulfamethoxazole twice a day) were given prophylactically to 19 adult patients with acute leukemia undergoing induction chemotherapy. The influence of the two regimens on the bacterial aerobic flora was evaluated. Both of the prophylactic regimens conditioned the aerobic microflora of the patients. Both groups acquired new microorganisms, prevalently gram-positive cocci, but also gram-negative bacteria with the TMP-SMZ regimen. Both treatment groups acquired yeasts.

Adult↗
PubMed1989

In vitro antimicrobial sensitivity of staphylococci isolated in the Santa Cruz region of Bolivia.

The in vitro antimicrobial susceptibility of staphylococci isolated in two different communities, Camiri and Javillo, of the Santa Cruz region in south-eastern Bolivia was tested by the agar diffusion technique and by a micro dilution susceptibility test to determine the Minimum Inhibitory Concentrations. Staphylococcal strains isolated from hospital staff of the Camiri Hospital were compared to that isolated from healthy people of Javillo, a very small community isolated in the jungle. In the Camiri Hospital, staphylococci showed a high prevalence of penicillin resistance, 100% for S. aureus strains and 73.5% for coagulase-negative staphylococci. Among coagulase-negative strains we found a high rate of multiresistant strains, mainly to ampicillin, tetracycline and chloramphenicol. In the rural population of Javillo we found staphylococcal strains highly susceptible to all the antibiotics tested.

Axilla↗
PubMed1989

Prevalence of antibody to hepatitis A virus in the Santa Cruz region of Bolivia.

Several epidemiological studies have shown the worldwide distribution of hepatitis A with the highest prevalence of anti-HAV antibodies in developing countries (Papaevangelou 1984). There is no information about the epidemiology of hepatitis A in Bolivia. The goal of this study was to evaluate the anti-HAV antibody prevalence in the Santa Cruz region, southeastern Bolivia.

Age Factors↗
PubMed1988

Subunit S1 of pertussis toxin: mapping of the regions essential for ADP-ribosyltransferase activity.

The toxicity of pertussis toxin is mediated by the ADP-ribosyltransferase activity of subunit S1. To understand the structure-function relationship of subunit S1 and guide the construction of nontoxic molecules suitable for vaccines, we constructed and expressed in Escherichia coli a series of amino-terminal and carboxyl-terminal deletion mutants as well as a number of molecules containing amino acid substitutions. The shortest peptide still retaining enzymatic activity contains amino acids 2-179. Within this region we identified three mutants in which amino acid substitutions abolish the enzymatic activity. Mutation of amino acids 8 and 9 or 50 and 53, located within the region of the S1 subunit of pertussis toxin homologous to cholera toxin, causes loss of enzymatic activity. Outside this homology region, substitution of Glu-129 with glycine or aspartic acid also eliminates the enzymatic activity of the S1 subunit. In this respect, Glu-129 resembles the glutamic acid that is crucial for the catalytic activity of diphtheria and Pseudomonas toxins. Once introduced into the Bordetella pertussis chromosome, the above mutations should lead to the synthesis of nontoxic pertussis toxin molecules suitable for vaccine production.

Amino Acid Sequence↗
PubMed1988

Engineering bacterial toxin for the development of new vaccine against pertussis.

Bordetella pertussis is the causative agent of whooping cough. The cellular pertussis vaccine introduced in the forties is highly effective and is widely used, but its reactogenicity has led to public concern regarding its safety. The attempts to reduce the side effects associated with pertussis immunization have led to the preparation of acellular B. pertussis products: one composed of detoxified pertussis toxin (PT) and filamentous haemagglutinin (FHA), another one composed only of detoxified PT and a third vaccine composed of detoxified PT, FHA and serotypes 1, 3 of fimbriae. In our laboratories we have approached the study of pertussis toxin, the molecule present in all the proposed acellular pertussis vaccines and one of the main virulence factors of B. Pertussis, with the aim of producing new acellular pertussis vaccines by using recombinant DNA techniques.

Antibodies, Monoclonal↗
PubMed1987

Expression and immunological properties of the five subunits of pertussis toxin.

Pertussis toxin, a protein composed of five different subunits, is responsible for the pathogenicity of Bordetella pertussis and is the main component of a new vaccine against whooping cough. The genes coding for the five subunits, recently cloned and sequenced, are organized as an operon. We approached the problem of expression of the five genes in Escherichia coli and, although we obtained high levels of transcription of the native pertussis toxin genes, the amount of proteins produced was very low or undetectable. To obtain suitable expression of each of the five subunits, we fused their genes to the gene coding for the DNA polymerase of MS2 in the expression vector pEx31. A total of 5 to 30 mg of purified fusion proteins could be obtained from 1 liter of culture. The purified fusion proteins were used to immunize rabbits to obtain sera against each of the five subunits. These sera, although able to recognize the toxin in an enzyme-linked immunosorbent assay and the corresponding subunits in Western blots, were not able to protect CHO cells from the action of pertussis toxin. Mice immunized with the five subunits were not protected from an intracerebral challenge with B. pertussis. Subunits S2 and S3, which are 67% homologous, were shown to cross-react immunologically. The fused subunit S1 was able to ADP-ribosylate transducin as efficiently as the native pertussis toxin.

Adenosine Diphosphate Ribose↗