Biomedical subjects

L Leon

Publications and source records attributed to L Leon.

At least 37 records · Page 2Linked to original sources

PubMed1993

Comparative study of different immunoserological techniques for the detection of antibodies against transmissible gastroenteritis (TGE) coronavirus.

In order to carry out a sero-epidemiological survey of transmissible gastroenteritis (TGE) infection in a high-density pig-breeding area the Murcia region, Spain), the sensitivity and the specificity of 5 different techniques were compared. Twenty-four sera from non-infected and infected pigs were analyzed by the following tests: in vitro neutralization, indirect ELISA with concentrated virus, indirect ELISA with purified virus, immunocapture ELISA and VELCIA (virus-enzyme linked cell immunoassay). All sera from infected pigs were detected as positive only by seroneutralization, ELISA with purified virus and VELCIA (sensitivity 100%). False-positive sera were detected with several tests (ELISA with purified virus and concentrated virus, ELISA immunocapture with a specificity of 88, 88 and 76% respectively). Only VELCIA provided a specificity as high as that obtained with seroneutralization (100%).

Animals↗

PubMed1992

Pathogenicity and antigen detection of the Nouzilly strain of transmissible gastroenteritis coronavirus, in 1-week-old piglets.

We compared the pathogenicity and the sites of multiplication of the attenuated Nouzilly strain, with the highly passaged Purdue-115 and the virulent Gep II strains of transmissible gastroenteritis (TGE) coronavirus, in 1-week-old weaned piglets. The immunohistochemical peroxidase technique, with an antiviral nucleoprotein monoclonal antibody, was used for the localization of the multiplication sites, in the intestine and other organs. The Gep II and the Purdue-115 strains, administered orally to piglets, caused clinical signs and lesions of TGE. These strains multiplied within the intestinal tract in the enterocytes of the jejunum and ileum, Peyer's patches and mesenteric lymph nodes. In view of the small numbers of infected cells in the tonsils, spleen, kidney, liver and lung, these tissues are not considered to be preferential multiplication sites. The attenuated Nouzilly strain multiplies only in the ileum and the mesenteric lymph nodes. The variation in the tropism for particular parts of the intestine (with the preferential localization of the virus in the ileum rather than the jejunum), could be related to the high degree of attenuation of the Nouzilly strain.

Animals↗

PubMed1992

Sero-epidemiological survey of porcine respiratory coronavirus (PRCV) infection in breeding herds in southeastern Spain.

In 1987 we conducted a sero-epidemiological survey in the Murcia Region (South-East Spain) to discover the prevalence and spread of PRCV-infection among breeding pigs and farms and determine the association between herd size and geographical zone with PRCV-infection. The Murcia Region was divided into four geographical zones and the farms classified by size in four categories. The random sample was statistically representative of both the breeding stock and farms in each geographical zone. We analysed 6,000 breeding pigs from 480 farms. The immunological techniques employed were indirect ELISA and blocking ELISA. The prevalence (P +/- IC) of PRCV-seropositive breeding pigs and infected breeding farms was 14.53 +/- 0.89% and 21.87 +/- 7.83% respectively. On 55% of the infected farms, the prevalence of seropositive breeding pigs was 60-100%. PRCV-infection appears spread throughout the four geographical zones of the Murcia Region. However, a significant association (p less than 0.01) was observed between geographical zone and the prevalence of PRCV-infection. A herd size of greater than 50 breeding pigs had a greater risk (p less than 0.01) of PRCV-infection.

Animals↗

PubMed1991

Trypanosoma cruzi in the opossum Didelphis marsupialis: parasitological and serological follow-up of the acute infection.

The opossum Didelphis marsupialis is known to be among the most important wild reservoirs of Trypanosoma cruzi and one in which the trypanosome may go through both the usual vertebrate intracellular cycle in its tissues and an extracellular cycle in the lumen of its scent glands. The species is highly resistant to heavy inocula and, depending on the parasite strain, experimental infections may be permanent or self limited. Aiming to understand the mechanisms involved in this parasite-host interaction we made a study of the acute phase of infection with different T. cruzi strains. Strains F, G-49 and G-327 produced durable infections with relatively high parasitemia and invasion of the scent glands, while equivalent inocula of the Y strain resulted in scanty parasitemia of short duration, no invasion of the SG, and no evidence of persistent parasitism. A smaller inoculum of G-49 produced only subpatent though persistent parasitemia and no invasion of the scent glands. The humoral immune response was less marked in the Y group; among the other groups IgM and IgG antibodies increased to high levels, higher in the G-49 group. The increase in IgG coincided with a drop of parasitemia to subpatent levels. Two opossums inoculated directly in the scent glands with culture forms of the Y strain had a short-lived subpatent parasitemia, but the parasites remained in the glands and serum Ig antibodies reached high levels. Immunoblot analysis showed that the sera of the inoculated opossums recognized few T. cruzi antigens (more in the F strain) in comparison with those of mice. However, with the only exception of those subcutaneously inoculated with the Y strain and including two naturally infected specimens, all the opossum's sera recognized a 90-kDa peptide in all T. cruzi strains. Our results confirm that opossums are able to selectively eliminate some strains of T. cruzi and indicate that the mechanism involved in this selection is probably not related to the humoral immune response. In infections by strains that are able to establish a permanent foothold in opossum tissues, there are indications that IgG antibodies participate in the control of the parasite population of the acute phase but are unable to prevent the chronic phase. It was once more demonstrated that the opossum infected scent glands function as diffusion chambers for parasite antigens but that, on the other hand, the parasites are here protected against the mechanisms developed by the host to control their population.

Acute Disease↗

PubMed1988

Two years of cyclophosphamide and 5-fluorouracil as adjuvant chemotherapy for stage II and III breast carcinoma.

The results after 6 years of a prospective clinical trial of adjuvant chemotherapy with a regimen of two drugs--cyclophosphamide and 5-fluorouracil (CF)-- for 2 years in 97 women with stage II or III breast cancer are reported. Eligible patients were free from distant metastases. All patients began adjuvant therapy within 4 weeks of surgery; therapy consisted of radical, modified, or extended radical mastectomy. No postoperative radiotherapy was given. The results are compared with a historical control group from previous consecutive patients treated by surgery alone. Patients were stratified by age (younger than 50 or older than or equal to 50) and nodal status (one to three positive axillary nodes vs. four or more positive nodes). The estimated 6-year survival was 60% for CF patients vs. 31% for control patients (P = 0.001). The estimated 6-year disease-free survival was 53.6 and 30.3% for CF and control, respectively (P = 0.007). There was a trend toward longer disease-free survival (DFS) and survival (S) in patients treated with CF, but this was not significant in all the subgroups. Disease-free survival was statistically significant in the subgroup of women greater than or equal to 50 years old with one to three positive nodes (P = 0.038); survival in the patients less than or equal to 49 years old with four or more positive nodes (P = 0.0036); and in patients greater than or equal to 50 years old with one to three lymph nodes involvement (P = 0.038).

Adult↗

PubMed1985

Ambulatory electrocardiographic correlates of ventricular inducibility during programmed electrical stimulation.

To determine the relation between spontaneous and induced ventricular arrhythmias, ambulatory electrocardiographic (Holter) monitoring and programmed electrical stimulation were performed in 48 adult patients with suspected life-threatening ventricular arrhythmias. Nine had no inducible arrhythmia, 11 demonstrated 1 to 2 beats of intraventricular reentry, 19 exhibited non-sustained ventricular tachycardia and 9 exhibited sustained ventricular tachycardia during electrophysiologic studies. Patients without arrhythmia inducibility had a high incidence of multiformity (56%) and bigeminy (44%), but a low incidence of either couplets (11%) or spontaneous ventricular tachycardia (11%) on Holter monitoring. An increasing incidence of all "complex" ectopic features was found with increasing degrees of ventricular inducibility. In patients with inducible sustained ventricular tachycardia, multiformity was present in 100%, bigeminy and couplets in 89% and spontaneous ventricular tachycardia in 78%. Premature ventricular complex frequency, couplet frequency and the repetition index (the ratio of couplets to premature ventricular complexes) were also found to be directly correlated with the degree of ventricular inducibility. Three quantitative arrhythmia variables were identified which predicted ventricular tachycardia inducibility. Seven (78%) of 9 patients with a mean premature ventricular complex frequency of 100 or more/1,000 normal beats, 11 (85%) of 13 with a mean couplet frequency of 1 or more/1,000 normal beats and 19 (83%) of 23 with a mean repetition index value of 15 or more/1,000 premature ventricular complexes proved to have inducible ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1985

Role of iron in jejunal uptake of cadmium in the newborn rat.

There is evidence that suckling animals and children have a greater capacity for intestinal transport of both essential and nonessential metals than do adults of the species. It has also been observed in experiments using adult animals that the intestinal transport of iron and the nonessential metal cadmium interact with one another. In the study reported here, the influence of tissue iron status on jejunal uptake of cadmium was investigated in suckling, adolescent, and young adult rats using an in situ incubation technique. In the presence of 0.4 mM FeSO4, intestinal uptake of cadmium was significantly decreased in 14-d-old pups. Access to an iron-deficient diet reduced tissue iron levels in 28- and 42-d-old but not in 14-d-old rats. Intestinal uptake of cadmium was significantly greater in 28- and 42-d-old rats placed on the iron-deficient diet but did not change in 14-d-old rats compared to controls. In suckling rats injected with iron dextran over a six-d period, a significant decrease in intestinal uptake of both cadmium and iron was observed compared to controls. The results of the present study suggest that intestinal cadmium transport in the suckling, as well as the adolescent and young adult rat, interacts with, at least in part, the pathway responsible for iron transport.

Aging↗

PubMed1985