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F Esposito

Publications and source records attributed to F Esposito.

At least 109 records · Page 6Linked to original sources
PubMed1990

Isolation of cDNA fragments hybridizing to rat brain-specific mRNAs.

A cDNA minilibrary in pUC18 has been generated from 3-month-old rat brains. Two hundred clones were randomly selected and sequenced. Comparison with a nucleic acid and protein data bank revealed a number of cDNA fragments not homologous to any published sequence. Northern blot analyses of some of these clones yielded 5 brain-specific cDNA fragments. The full-length cDNA for one of these clones has been isolated and completely sequenced. It corresponds to an mRNA of about 1,500 nucleotides, which is present in brain and, to a lesser extent, in heart and skeletal muscle. Its expression is developmentally regulated in the rat brain from 14-day embryos to 3-month-old adults. A very recent comparison with the EMBL nucleotide sequence data bank showed that this mRNA codes for a brain-specific snRNP-associated protein.

Aging↗
PubMed1989

Immunotechniques for epidemiology of malaria: appropriate tools for integration of primary health care with malaria research and control.

Community-based malaria control with integrated primary health care appears to be the most feasible approach for endemic countries in their struggle against malaria. To plan and implement personal protection and vector control measures, there is the need for comprehensive information about local modes of transmission. Experience with insecticide-based vector control programmes and entomological data accumulated over the years has revealed vector systems of extraordinary heterogeneity, creating multifaceted transmission situations. The primary health care-system offers an appropriate structure to collect and evaluate microepidemiological information countrywide. Community and health workers trained and supervised by qualified personnel could be involved in the assessment of clinical, parasitological and entomological indices. Community participation is facilitated if personnel are taught the use of immunotechniques. Tests can be performed on dried material which allows samples to be stored for months without refrigeration, so that transport to and processing in a central laboratory are not subject to time constraints. This paper describes and discusses enzyme-linked immunosorbent assays to determine if antibodies to sporozoites are present in blood collected as dried spots and to identify the origin of bloodmeals using dried mosquito abdomens.

Animals↗
PubMed1989

Introduction to, and evaluation of, immunoassays in a malaria research institute in Tanzania.

Various immunoassays have been introduced into, and evaluated at, the Amani Medical Centre in north-east Tanzania. These include immunoblotting to identify mosquito bloodmeals, immunoradiometric and immunoenzymatic assays to assess the presence of circumsporozoite protein in mosquitoes, and enzyme-linked immunosorbent assays to measure antibodies to circumsporozoite antibody in people. The assays were shown to be reliable and practicable for use in the study of malaria epidemiology.

Humans↗
PubMed1989

Development of the human immune response against the major surface protein (gp190) of Plasmodium falciparum.

The 190-kilodalton glycoprotein (gp190) of Plasmodium falciparum, the precursor of the major surface proteins of merozoites, is considered a promising candidate for a blood stage malaria vaccine. DNA sequences specific for the gp190 of the two isolates K1 and MAD20 were subcloned and expressed in Escherichia coli. The panel of fusion proteins obtained represents about 80% of the polymorphic sequences observed so far within various isolates of P. falciparum. Sera from individuals living in a malaria-endemic area of West Africa were tested in immunoblots against the gp190 fusion proteins, and antibody reactivity was mapped to defined regions of the gp190. Depending on the age of the individual and on the presence of parasites in the blood, distinct regions of gp190 were differentially recognized by the respective antibodies. Similarly, the analysis of sera from German patients with acute malaria revealed a distinct pattern. When grouped according to age and to parasitemia, the reactivity of the sera of people living in malaria-endemic areas may indicate a correlation between certain gp190 regions and protective immune response.

Animals↗
PubMed1988

DNA sequence specificity of 4,5',8-trimethylpsoralen cross-linking. Effect of neighboring bases on cross-linking the 5'-TA dinucleotide.

The DNA sequence specificity for 4,5',8-trimethylpsoralen cross-linking of DNA has been examined using chemically synthesized DNA fragments containing all possible pyrimidine and purine base pair combinations. We confirm our previous findings that the 5'-TA dinucleotide represents a preferred cross-link site. Other dinucleotides that form cross-links are 5'-AT much greater than 5'-TG greater than 5'-GT. Although 5'-TA represents a preferred cross-link site, the rate of cross-linking can vary 3-4-fold depending on the base composition flanking the cross-linkable 5'-TA dinucleotide. In some cases, changes in DNA sequence 3 base pairs (bp) away from 5'-TA resulted in significant changes in the rate of cross-linking. We also see evidence for a long-range sequence context effect on the rate of cross-linking. A 30-bp fragment cross-linked at a relative rate of 2.9 compared to the rate of cross-linking of a 20-bp fragment when cloned contiguously in plasmid DNA. When cross-linked as separate fragments, the 30-bp fragment cross-linked at a relative rate of 1.9 compared to the 20-bp fragment. The results suggest that the reactivity of DNA to psoralens, and perhaps other intercalating drugs, is dependent on the dinucleotide sequence, the bases flanking the dinucleotide, and the long-range sequence context of the DNA.

Base Sequence↗
PubMed1988

Prevalence and levels of antibodies to the circumsporozoite protein of Plasmodium falciparum in an endemic area and their relationship to resistance against malaria infection.

A study on malaria transmission, prevalence of infection and anti-sporozoite antibodies was carried out in Burkina Faso (West Africa). The prevalence and the levels of antibodies to (NANP)3 were found to be related to the entomological sporozoite inoculation rates measured at the same time in a defined area. The major inducer of anti-(NANP)3 antibody production under field conditions is sporozoite inoculation by infected mosquitoes. Levels of antibodies to (NANP)3 vary considerably with age and transmission season. High levels of anti-(NANP)3 antibodies raised under field conditions might offer protection against small inocula of sporozoites.

Adolescent↗
PubMed1987

Supercoiling in prokaryotic and eukaryotic DNA: changes in response to topological perturbation of plasmids in E. coli and SV40 in vitro, in nuclei and in CV-1 cells.

Changes in DNA linking number have been observed in plasmid DNA purified from E. coli cells after the cells were treated with chloroquine. Chloroquine, a DNA intercalating drug, unwinds the DNA, decreasing the levels of negative supercoiling. Following this in vivo topological perturbation, within minutes DNA gyrase decreases DNA linking number producing more negatively supercoiled DNA topoisomers. Following the removal of the drug from cells, within minutes topoisomerase 1 or DNA gyrase increases the linking number restoring the original level of supercoiling. Analogous changes in DNA linking number after addition of chloroquine are observed in purified plasmid DNA, and in purified SV40 minichromosomes in the presence of exogenous topoisomerase. Changes in linking number are also observed in SV40 chromosomes in isolated nuclei and in SV40 DNA purified from CV-1 cells following topological perturbation with chloroquine. These results suggest that eukaryotic cells may have mechanisms to maintain a defined level of DNA supercoiling.

Animals↗
PubMed1987

Detection and anatomical localization of Plasmodium falciparum circumsporozoite protein and sporozoites in the afrotropical malaria vector Anopheles gambiae s.l.

Salivary glands from Anopheles gambiae s.l. collected in Burkina Faso, West Africa, were analyzed by both microscopic examination and immunoradiometric assay to determine the Plasmodium falciparum sporozoite rates. Using the same mosquito samples, the immunoassay revealed positive salivary glands with low sporozoite loads, which were frequently missed by microscopy. A closer agreement between both techniques was found using salivary glands with high sporozoite loads. We also found a number of mosquitoes with uninfected salivary glands which harbored the circumsporozoite antigen in their thoraces. In a particular village these mosquitoes represented 43.5% of all sporozoite antigen carrying specimens.

Animals↗
PubMed1986

Structure and in vitro transcription of tRNA gene clusters containing the primers of MuLV reverse transcriptase.

Three genes coding for mouse tRNAPro have been isolated from a genomic library and characterized both structurally and functionally. Two of these (tPro52 and tPro53) code for the tRNA primer of reverse transcriptase of MuLV. The third one (tPro51) shows several differences (mutations and deletions) that probably prevent the folding of the matured transcript into the cloverleaf structure, and is therefore a pseudogene. This pseudogene gives rise to a RNA transcription product in vitro. tPro52 is clustered with a tRNALys gene and with a tRNAAla gene, which is strongly homologous to the rat identifier repeated sequence. tPro53 is clustered with a tRNAAsp and a tRNAGly gene. Other tRNA-hybridizing sequences are present in the lambda clones that contain tPro51 and tPro53.

Anticodon↗
PubMed1986

A new method for identification of the animal origin of mosquito bloodmeals by the immunobinding of peroxidase-anti-peroxidase complexes on nitrocellulose.

A method is described for identification of the animal origin of mosquito bloodmeals (MBM). The immunoassay is named DOT-PAP, it makes use of nitrocellulose as solid phase and of peroxidase-anti-peroxidase soluble complexes as detectors. DOT-PAP includes a built-in absorbing system to remove possible cross-reactivities. The sensitivity of the assay is higher than that of precipitin test or ELISA, and it dispenses with machineries for the reading of results. The method requires nanogram amounts of antigen, therefore it lends itself to the identification of incomplete MBM and of 28 h digested MBM as well. The assay can be applied to different hematophagous arthropods and the small volumes of antigen used allow to scan a vast array of possible animal sources on the same bloodmeal.

Animals↗