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Biomedical subjects

F Esposito

Publications and source records attributed to F Esposito.

At least 127 records · Page 7Linked to original sources
PubMed1986

Field observations on the use of anti-sporozoite monoclonal antibodies for determination of infection rates in malaria vectors.

Samples of indoor-resting Anopheles gambiae s.1. from Mali and Burkina Faso (West Africa) were processed in order to compare Plasmodium falciparum sporozoite rates obtained by immunoradiometric assay (IRMA) with circumsporozoite (CS) monoclonal antibody and by microscope examination of salivary glands. The immunological method provided sporozoite rates always higher than those obtained by microscope examination. This result does not appear to be related to cross-reactions involving non-sporozoite antigens. A small fraction of IRMA-positive mosquitoes is necessarily negative by microscope, since these mosquitoes actually contain the CS antigen only in the abdomen, presumably in connection with the presence of fully mature oocysts. However, the frequency of these mosquitoes cannot explain in itself an average ratio of 1:2 between microscope and IRMA sporozoite rates. A more important source of difference appears to depend on the detection of positive mosquitoes with low sporozoite numbers which remain more frequently undetected by microscope examination. Failure of salivary gland penetration by sporozoites is also considered as a possible source of discrepancy between the two methods.

Animals↗
PubMed1985

Pseudouridine excretion and transfer RNA primers for reverse transcriptase in tumors of retroviral origin.

To evaluate the relationship between pseudouridine increase in biological fluids and retroviral cell transformation, we have studied the effect of retrovirus infection and/or transformation on the rate of pseudouridine excretion by chick embryo fibroblasts. The results show that: pseudouridine excretion by chick embryo fibroblasts transformed by Rous sarcoma virus is several times higher than that of normal cells; this increased excretion precedes by many hours the appearance of the morphological signs of transformation and it is always present when neosynthesized infectious viral particles are released into the culture medium; and pseudouridine excretion was also increased in cells infected by a mutant of Rous sarcoma virus (RAV-1) which, lacking the src gene, does not transform the cells but replicates normally. To investigate if pseudouridine overproduction is related to an altered turnover rate of specific transfer RNA (tRNA) species which functions as primer of retrovirus reverse transcriptase, the concentration of non-acylated proline-accepting tRNA and non-acylated tryptophan-accepting tRNA, primers of reverse transcriptase of murine leukemia virus and of Rous sarcoma virus, respectively, has been measured, the former in normal and transformed AKR thymus and the latter in normal fibroblasts and in fibroblasts infected by Rous sarcoma virus or by its nontransforming mutant. The results show that in both systems a significant increase of the primer tRNA species occurs in the infected or transformed cells.

Animals↗
PubMed1983

Determination of pseudouridine and other nucleosides in human blood serum by high-performance liquid chromatography.

A specific, sensitive, and rapid method to measure pseudouridine in human blood serum is described. The method is based on the following steps: (i) deproteinization of serum samples by filtration on membrane cones or by acetonitrile; (ii) purification of nucleosides and concentration of the sample by affinity chromatography on phenylboronate gel followed by lyophilization; and (iii) separation of nucleosides and their quantitation by reverse-phase high-performance liquid chromatography. The pseudouridine mean value in 30 normal subjects was 2.52 +/- 0.28 nmol/ml. The procedure also allows the identification of inosine, uridine, guanosine, and adenosine. Nevertheless, the presence in human blood serum of enzymatic activities which convert adenosine to inosine and cytidine to uridine prevents the precise quantitation of these nucleosides. All the compounds were identified by comparing their retention times and absorbance ratios (A280/A254) with those of pure compounds, as well as by cochromatography.

Chromatography, High Pressure Liquid↗
PubMed1983

Modified nucleosides in body fluids of tumor-bearing patients.

The catabolism of nucleic acids, particularly tRNA, produces a variety of modified nucleosides which are not reutilized by mammalian cells. Investigation of these compounds in body fluids, mainly urine, has recently provided evidence of altered metabolic situations in tumor-bearing patients. The factors involved in the alterations of modified nucleosides formation are connected with altered tRNA-modifying enzymes and/or altered turnover of subpopulations of tRNA. A common pattern in tumor cells or tissues is the presence of isoaccepting tRNA species containing aberrant nucleoside modifications. Several modified nucleosides have been detected and quantitated by HPLC analysis of the urine of normal subjects and cancer patients. Results obtained, in the authors' laboratory, among others, indicate a possible correlation between urinary excretion of these compounds and the course of the disease, with implications for the follow-up of therapeutic treatment. Particular reference should be made to psi, which appears to be a suitable marker for monitoring these subjects. The data from the authors' laboratory also show that the analysis of modified nucleosides in blood may be considered a useful tool in the search for proper markers associated with the cancer status. In this respect psi is suggested as a biochemical indicator for cancer patients.

Chromatography, High Pressure Liquid↗
PubMed1983

[Echographic evaluation of portal flow].

Authors analyze clinical possibilities offered by the combination of pulsed Doppler/B mode in automatic ultrasound equipment in evaluating portal vein flow. In 60% of cases the system gave informations about flow in right (452 +/- 21 cm3/min) and in left (348 +/- 27 cm3/min) portal vein branches. Measurement failure causes and methods to avoid them are discussed.

Adolescent↗
PubMed1979

Specific contact-dependent cell-to-cell communication during preconjugant interactions of the ciliate Euplotes crassus.

A system has been developed to study cellular interactions between cells of complementary mating types prior to mating in the ciliate, Euplotes crassus. The presumptive mates were distinguished by using singlet and doublet cells of appropriate mating types in the mixtures. Cells of a given mating type were prelabelled with [3H]leucine and mixed with unlabelled complementary cells. Exchange of [3H]leucine-labelled material from donor to recipient cells was monitored through the various stages of the preconjugant interaction. A label transfer between the mating type complementary cells was detected from the beginning of the visible mating reaction, which occurs after a waiting period from the time of cell mixing and involves ciliary agglutination prior to cell body fusion. Complementary cells which were prevented from physically contacting each other and cells which were not competent to mate appeared unable to take up the labelled material. It is suggested that this material consists of some substance(s) playing an important role in the preconjugant cell-to-cell interactions of E. crassus.

Animals↗