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Biomedical subjects

D Martinez

Publications and source records attributed to D Martinez.

At least 109 records · Page 6Linked to original sources
PubMed1993

In vitro infection of bovine brain endothelial cells by Cowdria ruminantium.

Endothelial cells from bovine brain capillaries (BBEC) were successfully infected with the Gardel stock of Cowdria ruminantium. Growth conditions of cowdria in BBEC and bovine umbilical endothelial cells (BUE) were identical with average intervals between passages of 8.6 and 8.9 days in BBEC (17 passages) and BUE (28 passages), respectively. The time required to complete the life cycle and the morphology of the parasite were identical in both types of cells. The demonstration that BBEC may be infected with C ruminantium offers the means to study the mechanism of infection of the blood brain barrier endothelium by this parasite.

Animals↗
PubMed1993

Development of a single dilution ELISA to detect antibody to Dermatophilus congolensis in goat and cattle sera.

A solid phase immunosorbent assay to detect antibodies to Dermatophilus congolensis in ruminant sera was developed to be used as a single dilution ELISA in large epidemiological surveys. Optimal conditions for the test are described. The use of blocking proteins to reduce non specific binding was necessary. Non fat dry cow milk and fetal calf serum were the only two efficient blocking agents out of six tested. Comparison of 4 antigenic fractions obtained after sonication and differential centrifugations of D. congolensis cultures showed that cell-wall (CW) or membrane (M) enriched preparations were more specific than a crude extract (CR) or a soluble (S) antigen. Whole spores and filaments performed poorly as antigens. The best sensitivity and specificity of the ELISA were obtained when the cut-off point of positivity was fixed at mean absorbance of negative sera + 2.58 sd. The specificity was then 97.6% either with M or CR antigen. The sensitivity was improved from 93.4% with CR to 98.2% with M antigen. Threshold values for a positive test varied between the 3 geographical areas tested. CW and M were also the most efficient antigens for discerning between serotypes of D. congolensis. The precision of the test was evaluated with CR antigen and expressed in residual expressed in residual coefficient of variation (CV). The precision was CV = 5.1% when each serum was titrated in duplicate and the antibody levels were expressed in absorbances. The expression of antibody levels in arbitrary standard units estimated from calibration curves reduced the precision (CV = 13.8%). Several methods were tested to decrease between plate variability but these did not greatly improve the reproducibility since it was shown that the main source of variation was within the plate.

Actinomycetales↗
PubMed1993

Heterologous and homologous protection against influenza A by DNA vaccination: optimization of DNA vectors.

We have recently shown that direct injection of DNA can be an effective vaccine strategy eliciting both humoral and cell-mediated immune responses. Vectors were designed specifically for vaccination by direct DNA injection and refined to improve plasmid production in Escherichia coli. The vectors consist of a pUC-19 backbone with the cytomegalovirus (CMV) IE1 enhancer, promoter, and intron A transcription regulatory elements and the BGH polyadenylation sequences driving the expression of the reporter gene CAT or influenza A nucleoprotein (NP) or hemagglutinin (HA). The respective vectors expressed high levels of chloramphenicol acetyltransferase (CAT) and NP in tissue culture, and yielded 14-15 mg of purified plasmid per liter of Escherichia coli culture. Immunization of mice with the NP and HA expression vectors resulted in protection from subsequent lethal challenges of influenza using either heterologous or homologous strains, respectively.

Animals↗
PubMed1993

Induction of RNA editing at heterologous sites by sequences in apolipoprotein B mRNA.

An RNA editing mechanism modifies apolipoprotein B (apo-B) mRNA in the intestine by converting cytosine at nucleotide (nt) 6666 to uracil. To define the sequence requirements for editing, mutant apo-B RNAs were analyzed for the ability to be edited in vitro by enterocyte extracts. Editing was detected by a sensitive and linear primer extension assay. An upstream region (nt 6648 to 6661) which affected the efficiency of editing was identified. RNAs with mutations in this efficiency sequence were edited at 22 to 160% of wild-type levels. Point mutations in a downstream 11-nt mooring sequence (nt 6671 to 6681) abolished editing, confirming previous studies (R. R. Shah, T. J. Knott, J. E. Legros, N. Navaratnam, J. C. Greeve, and J. Scott, J. Biol. Chem. 266:16301-16304, 1991). The optimal distance between the editing site and the mooring sequence is 5 nt, but a C positioned 8 nt upstream is edited even when nt 6666 contains U. The efficiency and mooring sequences were inserted individually and together adjacent to a heterologous C in apo-B mRNA. The mooring sequence alone induced editing of the C at nt 6597 both in vitro and in transfected rat hepatoma cells. Editing at nt 6597 was specific, was independent of editing at nt 6666, and was stimulated to wild-type levels when the efficiency sequence was also inserted. Introduction of the mooring sequence into a heterologous mRNA, luciferase mRNA, induced editing of an upstream cytidine. Although UV cross-linking studies have previously shown that proteins of 60 to 66 kDa cross-link to apo-B mRNA, these proteins did not cross-link to the luciferase translocation mutants.

Animals↗
PubMed1993

Heartwater in Guadeloupe and in the Caribbean.

A sero-epidemiological survey for heartwater was organized in 1992 in the Lesser Antilles, from Grenada to Saint Martin. Blood from about one percent of the ruminant livestock of the islands was randomly sampled and the sera were tested with an indirect ELISA. The percentage of positive sera was found to be 30% in Guadeloupe, 25% in Antigua, 2.2% in St.Martin, 1.3% in St. Kitts & Nevis, 3.8% in Montserrat, 1.7% in Dominica, 1.5% in St.Lucia, 1.5% in St.Vincent, 3.5% in Barbados, 2.9% in Grenada and 7% in Martinique. Ruminants from Guadeloupe and Antigua are known to be infected with heartwater. The low percentage of positive sera and the absence of clinical cases in the other islands strongly suggest that positive sera in these islands are probably due to non-specific cross reactions between Cowdria and other micro-organisms (possibly Ehrlichia) which remain to be isolated. In particular, the high percentages of positive sheep sera in Martinique (15%) and Montserrat (11%) should be further investigated.

Animals↗
PubMed1993

Detection of antibodies to Cowdria ruminantium in the serum of domestic ruminants by indirect ELISA.

A solid phase enzyme immunoassay for the detection of antibodies to Cowdria ruminantium in the serum of domestic ruminants was developed by using microorganisms cultivated on bovine umbilical endothelial cells as antigen. When the culture showed 90% lysis, the supernatant was centrifuged, sonicated and coated on polystyrene microtiter plates. Antibodies were detected as early as 9 days after experimental immunization of goats. The sensitivity of the ELISA calculated with 73 ruminant sera ranged between 97.3% and 98.6%. The overall specificity of the test was 97% (N = 2925). However, the specificity was far lower for sheep (94.4%, N = 881) than for goats (98.6%, N = 651) and cattle (97.8%, N = 1393). Crossreactivity which could explain some of the false positive reactions, was found between Cowdria antigen and sera raised against Ehrlichia bovis (1 bovine positive out of 2 inoculated) or E. ovina (2 sheep out of 2 inoculated became positive) but not with E. phagocytophila. The intra-assay and inter-assay variability were 7.5% and 7.8% respectively, indicating a good reproducibility of the ELISA.

Animals↗
PubMed1993

The sero-diagnosis of heartwater: a comparison of five tests.

Five serological tests, the indirect and competitive ELISA, the indirect fluorescent antibody (IFA) test with 2 different antigens and the Western blot technique were compared and applied to sera that were known to be either negative or positive against Cowdria ruminantium or that were collected from animals in heartwater-free regions. No false positive reactions were recorded with any of the tests against the known negative sera. Except for minor variations in the sensitivity of the 5 tests, there was good correlation between them. Their specificity, however, remains in dispute since in all 5 tests extensive cross-reactions were recorded with antibodies in response to an as yet unidentified agent, probably Ehrlichia.

Animals↗
PubMed1993

Epidemiological studies on dermatophilosis in the Caribbean.

Dermatophilosis is one of the most important diseases of domestic ruminants in the Caribbean islands where the clinical disease has been shown to be associated with the presence of the tick Amblyomma variegatum. Seroepidemiological studies were conducted to clarify the epidemiology of the disease in the region with a particular attention paid to the role of A. variegatum. A bank of 1300 cattle sera from the Lesser Antilles was screened by ELISA for the presence of antibodies to Dermatophilus congolensis. It appeared that seropositive animals do exist in islands non infested by A. variegatum and where dermatophilosis is never or seldom seen. Moreover, there was no significant difference in prevalence of seropositive animals between tick-infested and non infested areas of Martinique and Saint Lucia, 2 islands partly infested by the tick, and where dermatophilosis is only seen in tick-infested areas. Prevalence was low in small islands with a dry climate. This confirms experimental data showing that A. variegatum is not necessary for the transmission of D. congolensis which is widespread in most of the islands. High concentrations of prostaglandin E2 (between 151 and 377 ng/ml) and prostacyclin (between 124 and 134 ng/ml) found in the saliva of females A. variegatum strongly suggest that the tick could favour the development of the lesions through an immunomodulating activity of its saliva. However, despite some success in reproducing dermatophilosis on goats simultaneously infested with adult A. variegatum and scarified with Dermatophilus, no difference was observed between naturally resistant Creole cattle and very susceptible Brahman animals using the same model. The lesions of dermatophilosis remained very mild on animals of both breeds.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomycetales Infections↗
PubMed1993

[Epidemiology of Cowdria infection in Senegal. II. Results of sero-epidemiological follow-up studies].

The authors report the results of sero-epidemiological monitoring of Zebu, Diakoré and Ndama cattle in the Sahel, Niayes and North Guinea zones, respectively. Calves aged 0-3 or 3-6 months were subjected to blood sampling every three months for a period of 20 months. In the Niayes and North Guinea zones, the immunofluorescence test showed that about 70% of 0-1 month old calves reacted positively to the Cowdria ruminantium antigen, whereas the prevalence was 92% between 3 and 6 months. After the age of 6 months, the results were 100% positive. In the Sahelian area, the prevalence of the infection was null. Results obtained with a sample of about 100 adult cattle from the Sahel, Niayes, North Sudan and North Guinea zones, showed a good correlation between positivity rates and the size of Amblyomma variegatum populations.

Animals↗
PubMed1992

A vaccine carrier derived from Neisseria meningitidis with mitogenic activity for lymphocytes.

Protein carriers vary in their ability to increase the immunogenicity of poorly immunogenic or T-lymphocyte-independent antigens. We examined one such carrier, the outer membrane protein complex derived from Neisseria meningitidis serogroup B strain B11, in an attempt to determine why this outer membrane protein complex was more immunogenic in young infants and in relevant animal models than two other carriers used in conjugates made with Haemophilus influenzae type b polysaccharide, a T-cell-independent antigen. A single protein of the outer membrane protein complex, the class 2 porin protein, was purified and shown to function as a T-helper lymphocyte carrier protein. Unexpectedly, it was also found to have mitogenic activity for lymphocytes that was not due to lipopolysaccharide. This mitogenic activity appears to date to be unique to this carrier protein of the carrier proteins tested and may contribute to the ability of the H. influenzae type b conjugate vaccine made with the outer membrane protein complex to generate IgG anti-polysaccharide antibody responses in mice and infant monkeys and protective immune responses in infants less than 6 months of age.

Animals↗
PubMed1992

Case report 745: Synovial lipoma arborescens.

A case is presented of lipoma arborescens of the knee with an atypical, sudden onset. Arthrography and ultrasound confirmed a synovially based lesion in the suprapatellar pouch. CT enabled a preoperative diagnosis of lipoma arborescens to be made, which was confirmed by surgical excision of a fronded fatty mass. Histological studies showed hyperplastic villi with mature adipose cells in the subsynovial layer. Resection of the synovium is considered curative, with only one case of recurrence after synovectomy having been reported [4].

Diagnostic Imaging↗
PubMed1992

Invasive maxillary aspergillosis after dental extraction. Case report and review of the literature.

Paranasal sinus aspergillosis has usually been considered a rare disease, but it is seen more frequently in both immunocompromised and immunocompetent persons. Invasion may reach the sinuses via the nose or from the mouth after dental procedures. Even though the infection is usually limited to one or more sinuses, it may in certain cases extend to vascular or intracranial structures with a fatal outcome. In these cases, aggressive treatment is justified. We report a case of maxillary sinus aspergillosis that developed after dental extraction. Attention should be given to this possibility even after an apparently uncomplicated dental extraction.

Adult↗
PubMed1992

Cross-sectional epidemiology of phlebitis and catheter-related infections.

OBJECTIVES: To describe the characteristics and the problems arising from the use of vascular catheterization in a general hospital and to identify avoidable risk factors associated with catheter-related infections. DESIGN: Cross-sectional, including the entire hospitalized population. SETTING: A university-affiliated hospital. RESULTS: Three-hundred fifty-three intravascular catheters were implanted in 315 of a total of 1,838 hospitalized patients (17.1%, confidence interval [CI] = 15.7-18.5). Of the 353 intravascular catheters, 26 (7.3%) were intra-arterial, 273 (77.3%) were peripheral, and 54 (15.3%) were central. The median (range) duration of the catheterization was 3 (1-11) days for arterial catheters, 1 (1-24) for peripheral catheters, and 5 (1-130) for central catheters. Fifty-three (15%, CI = 11.5-19.5) showed signs of infection. Independent risk factors associated with infection were the presence of infection located elsewhere (odds ratio [OR] = 8.7, CI = 4.13-18.3, p less than .0001), inappropriate catheter care (OR = 5.3, CI = 2.5-11.2, p less than .0001), inappropriate length of catheter use (OR = 3.5, CI = 1.4-9.02, p less than .01), and duration of hospitalization exceeding 14 days (OR = 2.6, CI = 0.9-7.83, p = .07). CONCLUSION: The risk factors associated with catheter-related infections suggest that many are preventable by improved protocols for management. This hypothesis can easily be tested.

Adolescent↗
PubMed1992

Experience with hemoperfusion for organophosphate poisoning.

OBJECTIVE: To evaluate the usefulness of extracorporeal clearance techniques in the treatment of organophosphate poisoning, particularly hemoperfusion. DESIGN: Retrospective study. SETTING: An ICU of a general hospital. PATIENTS: Ten patients with organophosphate poisoning initially received classic treatment with gastric lavage and washing of the whole skin surface, as well as the administration of cathartics, activated charcoal, atropine, and obidoxime or pralidoxime. All patients underwent one to three hemoperfusions. MEASUREMENTS AND MAIN RESULTS: Plasma insecticide concentrations and cholinesterase activity were determined daily. Two to three biopsies of fat tissue were carried out at 1- to 2-wk intervals. The amount of the insecticide removed during hemoperfusions was also determined. Five patients presented with a prolonged nicotinic syndrome. Two of these patients showed sequelae of delayed neurotoxicity. Another two of the five patients died and the remaining patient recovered without sequelae. In none of the patients could > 0.1% of the total absorbed poison be removed by hemoperfusion. No changes in symptoms were observed after these procedures. Fat tissue concentrations of the insecticide were 20 to 50 times higher than the concentrations in plasma. Atropine decreased the intestinal transit time, and 10 days after poisoning, a powerful cathartic treatment indicated the persistence of gut content, which probably caused prolonged absorption of the toxin. CONCLUSIONS: Extracorporeal cleansing mechanisms did not remove any clinically important amount of insecticide from our patients due to the high lipid solubility of these agents and no changes in symptoms were observed after these methods. The use of atropine decreases bowel peristalsis. Early use of powerful cathartics could avoid protracted absorption of the poison stored in the gut, although the potential benefits of this therapy require confirmation by the performance of prospective, controlled investigations.

Adult↗
PubMed1992

Distribution of heartwater in the Caribbean determined on the basis of detection of antibodies to the conserved 32-kilodalton protein of Cowdria ruminantium.

A competitive enzyme-linked immunosorbent assay (cELISA) was developed to detect immunoglobulin G antibodies to the major 32-kDa protein of Cowdria ruminantium. A total of 1,804 serum samples collected from cattle on 19 islands in the eastern Caribbean Basin were tested by this cELISA. A total of 133 serum samples from 10 islands (Antigua, Dominica, Grenada, Guadeloupe, Martinique, Montserrat, St. Kitts, St. Lucia, St. Martin, and St. Vincent) were found to be positive. The presence of antibodies to C. ruminantium in cattle on these islands was confirmed by immunofluorescence and Western blotting (immunoblotting). In earlier studies, C. ruminantium has been demonstrated only on Guadeloupe, Antigua, and Marie Galante. This study shows that the causative agent of heartwater is now firmly established in the Caribbean.

Animals↗