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Biomedical subjects

P Brasseur

Publications and source records attributed to P Brasseur.

At least 91 records · Page 5Linked to original sources
PubMed1992

Babesia divergens vaccine.

A vaccine strategy against Babesia divergens bovine babesiosis was successfully developed after perfecting of an efficient in vitro culture. Crude supernatants and purified fractions were able to induce a vaccine protection in gerbils against B. divergens infection. More, supernatants induced an effective vaccine protection in cattle. The role of B. divergens exoantigens of 17, 37, 46, 70 and 90 kDa in the development of the immune response was clearly demonstrated in gerbils, cattle, and man.

Animals↗
PubMed1992

Multi-drug resistant falciparum malaria in Cameroon in 1987-1988. I. Stable figures of prevalence of chloroquine- and quinine-resistant isolates in the original foci.

The status of drug-resistant Plasmodium falciparum in Cameroon was determined in 1987-1988 in 221 children who were selected for chloroquine and quinine in vitro microtests. Resistance to quinine was found in 17% of 72 isolates from the southern part of the country, and in 7% of 87 isolates from the northern part of the country. The effective concentrations of 50% and 90% (EC50 and EC90) differed little from those observed in 1986. In southern Cameroon, 38 (51%) of 74 individuals harbored chloroquine-resistant isolates. The EC50 ranged from 8 to 553 nmol and the mean +/- SD EC50 was 154 +/- 148 nmol. In contrast, in the northern area, all but one of the 120 subjects studied had EC50 values below the cutoff limit of 80 nmol (mean = 20 nmol). In vivo 7-day assays performed with chloroquine at a dose of 25 mg/kg in 389 individuals from the southwestern part of the country clearly confirmed RII-RIII levels of resistance in 18-52% of the cases, depending on the location studied. In the northern area, in vivo 7-day assays at a chloroquine dose of 10 mg/kg showed 36 of 39 subjects studied to have drug-sensitive parasites. Based on these results, it appears that after a rapid emergence of resistance that occurred in southern Cameroon, the prevalence of chloroquine- and quinine-resistant parasites remained fairly stable from 1986 to 1988. The stable difference between the northern and southern areas is believed to be related to both the lower rate of transmission and lower chloroquine drug pressure in the north.

Animals↗
PubMed1992

Multi-drug resistant falciparum malaria in Cameroon in 1987-1988. II. Mefloquine resistance confirmed in vivo and in vitro and its correlation with quinine resistance.

To further document the phenomenon of Plasmodium falciparum resistance to mefloquine formerly described in Cameroon, complementary in vivo and in vitro studies were conducted. Two hundred six P. falciparum isolates were studied in vitro using an isotopic microassay with mefloquine solutions prepared daily. Using the cutoff limit of 30 nmol, 26 (20%) of 133 isolates from the northern part of the country were defined as being resistant to mefloquine. In contrast, only one of 73 isolates collected in the southern part of the country was resistant. In vivo 7-day assays were performed in the northern area in 57 asymptomatic P. falciparum carriers (age range 1-10 years) who were given a single 25 mg/kg dose of mefloquine (Lariam). Among 46 cases in which followup was possible, P. falciparum asexual parasites were cleared within five days in 38 cases, by days 6 and 7 in two cases, and remained detectable up to day 7 in six cases. Thus, these latter patients have a RII-RIII level of resistance by in vivo criteria. No resistance was found in 40 additional patients studied similarly in the southern region. These observations were made before any mefloquine drug pressure was exerted in the country, but results of cross-resistance and drug consumption studies support the hypothesis that in the northern region, where a close correlation (r = 0.67) was found between the response to quinine and mefloquine, the more frequent use of quinine may have induced a primary quinine resistance and a secondary mefloquine resistance (without chloroquine resistance).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Emission tomography for assessment of diffuse alcoholic liver disease.

A method of quantitative liver tomoscintigraphy (SPECT) was compared for accuracy with planar scintigraphy (PS) in a group of patients with diffuse alcoholic liver disease. SPECT sensitivity was also compared with that of transmission computed tomography (CT), US, aminopyrine breath test (ABT) and liver chemistries (LC). One hundred and fourteen alcoholic patients with proven liver disease and 17 patients free of liver disease were included. Seven quantitative scintigraphic features and a score, including all criteria were considered. With a specificity of 95%, the sensitivity was 79% in steatosis and 97% in cirrhosis. SPECT showed a better sensitivity than PS (SPECT 89%, PS 66%), especially in patients with steatosis. In the same subsets of patients, SPECT sensitivity also compared favorably with that of transmission CT (SPECT 92%, CT 65%), ultrasonography (SPECT 88%, US 53%) and ABT (SPECT 90%, ABT 63%).

Alanine Transaminase↗
PubMed1991

Cytological and immunological responses to Babesia divergens in different hosts: ox, gerbil, man.

A continuous in vitro culture system for Babesia divergens was initiated from a human isolate. It was maintained through 305 subcultures for 3 years using a low concentration of serum and a low haematocrit, with no decrease in the initial virulence. This in vitro system enabled the routine culture of all human and bovine B. divergens isolates thus far tested, with a mean parasitaemia level of 30%-40%. Different cytological aspects observed in the same isolate by optical and electron microscopy were described in parasitized ox, gerbil and human erythrocytes. The sequence of B. divergens antibody responses was determined in man and ox, enabling the precise identification of major B. divergens antigens as candidates for vaccines.

Animals↗
PubMed1991

A cytopathic effect of Trichomonas vaginalis probably mediated by a mannose/N-acetyl-glucosamine binding lectin.

The pathogenic effect of a highly pathogenic strain of Trichomonas vaginalis on McCoy cell monolayers was investigated. Specific inhibition of the cytopathic effect by monosaccharides, such as N-acetyl-glucosamine (GlcNAc) and mannose (Man), was observed. Our preliminary results suggest that the pathogenicity of T. vaginalis depends on a lectin specifically sensitive to GlcNAc and to a lesser extent to Man. Although N-acetyl-mannosamine was found to be the most efficient inhibitor, this effect seems to be unrelated to the natural biological behaviour of the infested host.

Acetylglucosamine↗
PubMed1991

Analysis of immune responses of different hosts to Babesia divergens isolates from different geographic areas and capacity of culture-derived exoantigens to induce efficient cross-protection.

The immunoprecipitation of [35S]methionine-radiolabelled antigens from different Babesia divergens isolates by using bovine, gerbil, and human immune sera has shown that many B. divergens proteins contain epitopes shared between isolates. The cross-protective capacity of culture-derived soluble immunogens from the B. divergens Rouen 1987 isolate was tested against different B. divergens isolates. Results showed complete protection against the 7107b French isolate and substantial protection against the Weybridge 8843 English isolate (80% protection) and the Munich 87 German isolate (60% protection). In order to explain these vaccination results and to assess both the common and variable antigenicity of B. divergens, the antigenic patterns of the challenge isolates (Rouen 1987, 7107b, Weybridge 8843, and Munich 87) were compared by immunoprecipitation, using gerbil antisera raised against the Rouen 1987 vaccine isolate. Differences in the antigenic patterns and in the cross-protection of gerbils in these heterologous challenges were examined by studying the virulence and the antigenic status of each isolate.

Animals↗
PubMed1990

Identification of major Babesia divergens polypeptides that induce protection against homologous challenge in gerbils.

[35S]methionine-radiolabeled proteins from the Babesia divergens Rouen 1987 isolate were immunoprecipitated with immune sera from three potential hosts: human, ox, and gerbil. The results showed a constant humoral response against major babesial antigens. Similarly, immunoprecipitation of radiolabeled in vitro culture supernatant demonstrated that the exoantigens of 37, 46, 70, and 90 kDA were the immunodominant polypeptides, whatever the host. The effects of vaccination with concentrated supernatant from B. divergens Rouen 1987 in vitro cultures (30 to 40% parasitemia) were examined in gerbils inoculated with the homologous B. divergens isolate. Gerbils having received two or three injections of a whole vaccine dose (1.5 ml of parasitized culture supernatant equivalent [PCSE]) or of a 1:5 diluted vaccine dose (0.3 ml of PCSE) showed 100% survival after intraperitoneal challenge with 10(6) B. divergens-infected gerbil erythrocytes. Moreover, two or three injections of a 1:25 diluted vaccine dose (0.06 ml of PCSE) or 9% NaCl or 1.5 ml of unparasitized culture supernatant equivalent resulted in a mortality rate of 80 to 90% of the infected gerbils. Immunoprecipitation and immunofluorescence assays performed with antisera from vaccinated and control gerbils demonstrated that a single vaccine injection induced a humoral response, which increased slightly after the second or third injection. After challenge, antibody levels increased significantly, although the immunoprecipitation did not display any modification of Babesia antigen patterns.

Animals↗
PubMed1990

Impairment of Plasmodium falciparum-specific antibody response in severe malaria.

Serum antibody response to plasmodial antigens was investigated in 97 Thai patients with Plasmodium falciparum malaria. No difference in immunoglobulin G (IgG) antibody levels was detected between groups without or with cerebral manifestations of malaria (n = 40). In patients with the most severe form of the disease, i.e., those who died despite adequate therapy (n = 12), antibody detected in the immunofluorescent-antibody test was found at lower levels than in those who recovered (geometric means: IgG = 1/420 versus 1/3,800; IgM = 1/15 versus 1/70); similarly, precipitating malarial antibodies were present in only 1 of these 12 patients, while they were detectable in 65 of the remaining 85 patients (76.5%). In contrast, anticytomegalovirus antibody levels were similar in the different groups of patients. Results show that depression of antibody response may extend to antiplasmodial responses during severe malaria. The link between fatality and a low level of antibody production suggests that an appropriate immune response to malarial antigens may be required to achieve recovery with drug treatment and provides a new direction for malaria therapy research.

Adolescent↗
PubMed1990

[Breast tumor with myoepithelial cells. Apropos of a case report].

A case of malignant myoepithelioma of the breast is reported. Mammographic and echographic features are not typical. Diagnosis of this rare lesion mainly relies on histological and immunocytological findings. This potentially malignant tumor must be totally resected given the risk of recurrence. To the author's knowledge, this is the third report of a breast myoepithelioma that has metastasized.

Adult↗
PubMed1988

Rat model for human cryptosporidiosis.

Effective treatment for Cryptosporidium infection in immunocompromised patients has yet to be found. We report a rodent model of persistent Cryptosporidium infection. Sprague-Dawley rats were injected subcutaneously twice a week for 8 weeks with 25 mg of hydrocortisone acetate. Fed a regular low-protein diet for 9 weeks, they were challenged once with 10(5) calf Cryptosporidium oocysts 5 weeks after the start of the hydrocortisone acetate regimen. Oocyst shedding was evaluated in feces daily by using a carbolfuchsin-staining method. Rats shed oocysts from days 2 to 9 after ingestion and developed a persistent infection for more than 38 days. Excretion was lower after subsequent parasite challenges, suggesting that a degree of protection developed progressively. The results suggest that this experimental model provides a procedure for screening candidate therapeutic agents.

Animals↗
PubMed1988

Patterns of in vitro resistance to chloroquine, quinine, and mefloquine of Plasmodium falciparum in Cameroon, 1985-1986.

The drug sensitivity of 246 Plasmodium falciparum isolates was studied in vitro in five areas of Cameroon at the end of 1985. Results demonstrate that parasites resistant either to chloroquine, quinine, or mefloquine, or to two of these drugs, were prevalent in four of the areas investigated, but the drug response pattern varies widely from one area to another. The recent explosive emergence of chloroquine resistance in the south of the country, where both prevalences and levels are very high (up to 86%), contrasts with only moderate levels of resistance in the north. This may be related to differences in transmission by mosquitoes between Sahel and forest areas. Quinine resistance was observed in 24% of the isolates studied in vitro and was frequently associated with chloroquine resistance. The presence of isolates responding poorly to mefloquine, observed mainly in northern Cameroon, suggests that resistance may occur in areas where the drug has never been used.

Adolescent↗
PubMed1988

Low prevalence of P. falciparum in-vivo resistance to chloroquine in northern Cameroon in 1986.

The response to chloroquine of 49 Plasmodium falciparum isolates from the Northern dry areas of Cameroon was assessed by 7 day in-vivo assays. Twenty seven patients were treated with the standard 25 mg/kg dose, and 22 received a reduced, but frequently used, 10 mg/kg dose. The results of these in vivo assays are in agreement with in-vitro data showing a low prevalence and a low degree of chloroquine resistance. In contrast with P. falciparum isolates from Southern Cameroon, no case of RII or RIII resistance was detected in the North. Clearance of parasite was delayed in 4 of the 22 patients treated with 10 mg/kg, and for one of them parasites remained up to day 7 despite subnormal but appropriate chloroquine blood concentrations.

Adolescent↗