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Biomedical subjects

L Maes

Publications and source records attributed to L Maes.

At least 37 records · Page 2Linked to original sources
PubMed1999

Design, synthesis, and evaluation of inhibitors of trypanosomal and leishmanial dihydrofolate reductase.

This paper concerns the design, synthesis, and evaluation of inhibitors of leishmanial and trypanosomal dihydrofolate reductase. Initially study was made of the structures of the leishmanial and human enzyme active sites to see if there were significant differences which could be exploited for selective drug design. Then a series of compounds were synthesized based on 5-benzyl-2, 4-diaminopyrimidines. These compounds were assayed against the protozoan and human enzymes and showed selectivity for the protozoan enzymes. The structural data was then used to rationalize the enzyme assay data. Compounds were also tested against the clinically relevant forms of the intact parasite. Activity was seen against the trypanosomes for a number of compounds. The compounds were in general less active against Leishmania. This latter result may be due to uptake problems. Two of the compounds also showed some in vivo activity in a model of African trypanosomiasis.

Animals↗
PubMed1999

Economic benefits of prophylaxis with diclazuril against subclinical coccidiosis in lambs reared indoors.

One hundred and twenty weaned male lambs, naturally infected with Eimeria species, were used to assess the economic benefits of the prophylactic administration of diclazuril. They were randomly divided into four groups of 30 lambs on the basis of their bodyweight and output of oocysts. The groups were either left untreated (group 1), treated orally with a simple dose of diclazuril at 1 mg/kg (group 2), with two doses two weeks apart (group 3), or with sulphadimethoxine at 50 mg/kg for five consecutive days (group 4). No clinical signs of coccidiosis were observed in any of the groups. The output of oocysts was significantly reduced on day 7 after treatment in group 2, on days 7, 14 and 28 in group 3 and on days 7 and 14 in group 4. No significant differences were found between the treated and untreated groups for bodyweight, carcase weight and carcase classification. The mean fattening period was shorter for the treated lambs (52 and 55 days) than for the untreated controls (60 days). The average growth rate of the lambs treated twice with diclazuril and with sulphadimethoxine was improved and the feed conversion rates of the lambs treated once or twice with diclazuril were 7 per cent and 16 per cent better than that of the untreated lambs.

Animal Husbandry↗
PubMed1999

Issues for cardiovascular disease risk factor development in Europe.

A review of U.S. and European clinical trials and cardiovascular prevention studies indicates a strong relation among cardiovascular disease risk factors and between metabolic factors and health behaviors established in youth. Social and behavioral determinants of risk are best modified by strategies applied in schools, families, and whole communities to provide a firm base for primordial prevention of risk factor development. This is illustrated with results from a European intervention trial and from observational studies in the young.

Adolescent↗
PubMed1999

Effects of a low-intensity worksite-based nutrition intervention.

Male employees from four local worksites were recruited to participate in a short-term and low-intensity nutrition intervention which focused on promoting low-fat dietary habits. The sites were randomized to control conditions or to the intervention programme that consisted of an individualized health risk appraisal, group sessions, mass media activities and environmental changes. Participants were seen before and three months after intervention to measure blood lipids, nutrition knowledge and dietary changes. Eighty-three per cent of all eligible subjects were screened (n = 770) and follow-up measures were obtained for 82%. The score for nutrition knowledge improved significantly in the intervention group. There was also a net reduction in the intake of total calories and in the percentage of energy from total fat. Reported intake of carbohydrates and proteins increased. For all employees assessed, there were no changes in mean total cholesterol level or fatty acid composition. Only among participants with hypercholesterolemia was a significant reduction in blood cholesterol observed. This low-intensity intervention programme achieved some self-reported dietary changes and was successful (at least in part because statistical regression needs to be considered) in obtaining a more short-term beneficial cholesterol level in employees at higher cardiovascular risk.

Adult↗
PubMed1999

Determinants of smoking behaviour among adolescents in Semarang, Indonesia.

OBJECTIVES: To determine the smoking prevalence and to examine the determinants of smoking behaviour among male adolescents in Semarang, Indonesia. DESIGN: A random sample of schools in Semarang (population 1.5 million) was obtained using a stratified sampling procedure (strata based on type of school and district). A total of 149 schools were selected (response rate 72%). Within the schools 186 classes were selected, targeting the 11, 13, 15, and 17 year olds. An anonymous, self administered questionnaire was filled in by all students present at the day of the survey (total sample size 6276). OUTCOME MEASURES: Smoking prevalence, exposure to family and peer smoking, and other variables that may be related to smoking. Logistic regression was used to examine the determinants of smoking behaviour. Only male students were included in the analysis. RESULTS: Smoking increased dramatically between the ages of 11 and 17, from 8.2% to 38.7%. The variance explained by the regression model increased from 19.8% for 11 year olds to 53% for 17 year olds. The smoking behaviour of best friends was the most powerful determinant of smoking, and this was consistent across the age groups. Best friends' attitudes towards smoking and older brothers' smoking behaviour were also important determinants of smoking. CONCLUSIONS: Smoking prevalence among male adolescents in Semarang, Indonesia is high. Effective smoking prevention programmes should take into account the dominant influence of peers in the onset and maintenance of smoking behaviour. In general, school related items had a less important role in predicting smoking behaviour than expected.

Adolescent↗
PubMed1998

A general approach to the synthesis of polyamine linked-monoindolylmaleimides, a new series of trypanothione reductase inhibitors.

A simplified approach to the synthesis of 2-polyamine linked-monoindolylmaleimides has been achieved, leading to a new series of trypanothione reductase inhibitors. The conditions of access to N,2-bis(polyamine)-3-monoindolylmaleimides and N,N'-bis(monoindolylmaleimide) polyamines are described. Measured inhibitory activities towards trypanothione reductase from Tryanosoma cruzi show the importance of both aromatic moieties and polyamine chains for trypanothione reductase recognition.

Animals↗
PubMed1997

Duration of protective immunity in experimental canine babesiosis after homologous and heterologous challenge.

Three Beagle dogs were monitored clinically and serologically for 55 weeks following an experimental primo-infection and two challenge infections with a heterologous strain of Babesia canis. There was no cross-protection when dogs were challenged with the heterologous strain after 7 months, but there was complete protection when challenged a second time with this heterologous strain 5 months later. Although the serological profile using indirect immunofluorescence showed the same trend whether homologous or heterologus antigen was used, antibody titres generally reached higher values for homologous antigen. Seropositivity in itself was no guarantee for protective immunity against heterologous challenge.

Animals↗
PubMed1996

Prophylactic treatment of experimental canine babesiosis (Babesia canis) with doxycycline.

Doxycycline provided satisfactory prophylaxis against experimental infection with a highly pathogenic strain of Babesia canis. Rectal temperature, parasitaemia, packed cell volume and serology were monitored for evaluation of the prophylactic effect. Although a daily dose of 5 mg kg-1 of doxycycline did not completely prevent clinical disease, symptoms remained moderate and a full recovery was obtained within 1 week. At a dose of 20 mg kg-1 day-1 no clinical symptoms were observed, but asymptomatic infection could not be ruled out.

Animals↗
PubMed1996

2-Amino diphenylsulfides as inhibitors of trypanothione reductase: modification of the side chain.

A molecular modeling study meant to detect pharmacophore-like patterns in the active site of trypanothione reductase (TR) offered hints about the opportunity of synthesizing and testing diphenylsulfide derivatives with prolonged or branched polyamino side chains as putative TR inhibitors. The inhibition results within the synthesized series confirmed the main working hypothesis inspired by the molecular modeling study. The different compounds were tested in vitro on the enzyme and on Trypanosoma cruzi and Trypanosoma brucei trypomastigotes as well as in vivo in infected mice.

Animals↗
PubMed1996

Naphthylisoquinoline alkaloids exhibit strong growth-inhibiting activities against Plasmodium falciparum and P. berghei in vitro--structure-activity relationships of dioncophylline C.

The growth-inhibiting activities of naturally occurring naphthylisoquinoline alkaloids against asexual blood stages of Plasmodium falciparum (NF 54, clone A1A9) and P. berghei (Anka) were studied in vitro. Three of the alkaloids [7-epi-dioncophylline A (8b), dioncolactone A (4), and 5'-O-demethyl-8-O-methyl-7-epidioncophylline A (11)] displayed good activities against both parasites, with median inhibitory concentrations (IC50) of 1-5 micrograms/ml. Dioncophylline C (2), however, was even better, with IC50 of 0.014 microgram/ml (P. falciparum) and 0.015 microgram/ml (P. berghei) and therefore regarded as a promising lead for studies of structure-activity relationships. The free N- and 8-OH-functions were shown to be prerequisites for the outstanding activity of this molecule against P. falciparum, the presence of at least one free phenolic OH-function appearing to be essential for any activity. Initial experiments with derivatives of ancistrocladine (1) show that, in contrast to 2, N-derivatization of this alkaloid leads to increased activity against P. falciparum.

Alkaloids↗
PubMed1996

[Illegal drug use by secondary school children in Belgium: north-south differences].

The study "Health Behaviour of Youngsters" regularly provides comparative data on health behaviour and related lifestyle of pupils from 11 to 18 years old. This study is based on repeated surveys among randomised representative samples of pupils, following the international standardised protocol from the WHO cross-national survey "Health Behaviour in School-aged Children". In Belgium, results from the 1990 survey (sample = 3528) show differences in illegal drugs use between the South (French-speaking) and the North (Flemish-speaking). For example, among the 17 year olds, 9.8% of the French-speaking pupils and 5.5% of the Flemish-speaking have already tried illegal drug(s) and in the same age groups, 2.9% and 1.5%, respectively declare to be regular users. The first hypotheses concerning those differences take into account the socio-economic and cultural environment as well as methodological problems inherent to these surveys.

Adolescent↗
PubMed1995

Clinical and serological observations on experimental infections with Babesia canis and its diagnosis using the IFAT.

Naive Beagle dogs (n = 5) were experimentally inoculated with two stocks of Babesia canis. Dogs were examined regularly for parasitaemia and for antibodies, using the indirect immunofluorescent antibody test (IFAT). This test proved to be useful for the diagnosis of babesiosis. After primo-infection dogs seem to develop a certain degree of immunity, although this immunity is neither absolute nor of long duration. Treatment of infected dogs with imidocarb (6 mg/kg) cleared the infection, but did not prevent the production of IFAT-antibodies. An infected dog treated with long acting oxytetracycline (20 mg/kg) became a subclinical, chronic carrier of the disease.

Animals↗
PubMed1993

IMOL 881, a new trypanocidal compound.

A new drug molecule (IMOL 881) was synthesized and is showing interesting trypanocidal properties. The test results on animal models indicate activity against several trypanosome species, both in the veterinary and in the human medicine application fields. The species tested so far include: T. evansi, T. equiperdum, T. gambiense and T. rhodesiense. The good activity combined with a relatively low toxicity results in a high therapeutic index (> 100). In addition to its curative properties, the drug also seems to exhibit a prophylactic potential, as evidenced by tests on drug treated mice, subsequently infected with T. evansi.

Animals↗
PubMed1992

A clinical and biological validation of the DSM-III melancholia diagnosis in men: results of pattern recognition methods.

Pattern recognition methods were carried out on a sample of 80 depressed men, assessed by means of 14 items relevant to depressive symptomatology of the Structured Clinical Interview for DSM-III-R. 1985 edition (SCID). A cluster analysis generated two classes, which were described as a vital (n = 35) and a nonvital cluster (n = 45). Vital depressives were characterized by psychomotor disorders, loss of energy, cognitive disturbances, a distinct quality of mood, early morning awakening and nonreactivity (the "vital" symptoms). Our findings support the descriptive validity of the DSM-III melancholia diagnostic category, although the DSM-III criteria are too conservative and include nonrelevant symptoms (e.g., diurnal variation, anorexia-weight loss) whilst excluding some important items (e.g., loss of energy, cognitive disorders). Vital depressed men were significantly older, more severely depressed and they exhibited biological disturbances (abnormal dexamethasone suppression test, lower basal thyroid secreting hormone) as opposed to nonvital depressives. There are several arguments to support the possibility that both clusters constitute relevant stages in the overall severity of illness continuum, whilst showing qualitative differences with regard to the vital symptoms. In other words, both clusters are continuous categories within the overall severity of illness continuum and form discrete categories with regard to the vital symptoms. By merging the dimensional and categorical hypotheses, we were able to construct a new integrated threshold model: unipolar depression in men is probably a homogeneous disease with reference to overall severity of illness, but--as severity increases--vital symptoms emerge, grouping together into a distinct profile, i.e., vital depression.

Adult↗
PubMed1992

[Dental hygiene in 10-to-18-year-old youths in Flanders. Results of a school survey].

This study is part of the cross-national Survey on Health and Lifestyles in School-aged children--a WHO collaborative study (HELENA). The aim of this report was to describe the oral health habits (oral hygiene, use of dental floss and fluoride, consumption of sugar snacks) in schoolchildren aged 10 to 18 in the Flemish-speaking community of Belgium. Toothbrushing was consistently less frequent among boys than among girls. There is a negative correlation between the frequency of toothbrushing and the consumption of soft drinks in both sexes, and between toothbrushing and sweets consumption in girls. The use of dental floss is still very rare. Efforts must be continued to reduce the consumption of sweets and soft drinks. No differences in oral health habits were noted among children from different school types. Parental profession did not influence oral health habits in this study.

Adolescent↗
PubMed1991

Risk assessment of antibiotic residues of beta-lactams and macrolides in food products with regard to their immuno-allergic potential.

In human medicine drug allergy is a well-established side-effect of the therapeutic use of antibiotics, especially the beta-lactams. Side-effects caused by macrolides are uncommon and only a very few of these seem to be caused by allergic mechanisms. Clinically, drug allergy is characterized by a spectrum of reactions ranging from mild skin rashes to angio-oedema or life-threatening anaphylaxis. Concern has been expressed that antibiotic residues in meat and other foods might be responsible for similar hypersensitivity reactions in a small number of individuals. This review assesses the potential risk of such reactions in general, but focuses on allergy to penicillin and macrolide residues in particular. In relation to the risk of primary sensitization, it is unlikely that residues could contribute to the overall immune response in view of the very low levels that are likely to be encountered in comparison with the high levels received during therapeutic use. No evidence has been found that any individual has become sensitized by residues of either penicillins or macrolides. Furthermore, the oral route is much less sensitizing than parenteral administration and immunochemical studies with penicillin indicate that hapten-protein complexes formed in vivo are unlikely to be immunogenic because of their low dose, low epitope density and binding to autologous carrier proteins. For performed allergens, the epitope density was also too low to be immunogenic. Because of the ubiquitous nature of penicillin-producing moulds in nature and the extensive use of beta-lactam antibiotics in human medicine, it is unlikely that epidemiological studies could be undertaken that could allow quantification of the minimal risk. The risk of allergic reactions in pre-sensitized individuals can be assessed similarly and again it is concluded that factors such as dose, oral administration and low epitope density make it unlikely that a significantly antigenic derivative could be formed. However, a review of the literature on penicillin hypersensitivity revealed a very small number of previously sensitized individuals from whom there is reasonable clinical and documentary evidence that penicillin residues in milk triggered an allergic reaction, usually a rash. Although these cases are very rare (less than 10 cases reported in the last 25 years), they illustrate the continuing need to control antibiotic residues vigilantly. Animal models have not proved useful for predicting the risk of hypersensitivity reactions to drugs, since allergy in man is determined by genetic and other factors and no validated methods exist to determine a no-effect level.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Effect of diclazuril (Clinacox) on the development of protective immunity against Eimeria tenella: laboratory trial in broiler chickens.

The effect of diclazuril, fed to chickens at 1 ppm in the feed, was studied to determine whether the drug interfered with the development of immunity to Eimeria tenella. Group A was not treated, Groups B and C received diclazuril from Day 1 until Day 15, after which time the medicated feed was replaced by blank feed for the remainder of the experiment from Day 16 until Day 42. Immunization was performed in Groups A and B by artificial trickle infections with 2,000 sporulated oocysts per bird on Days 4, 6, 8, 11, and 13. On Day 29, a challenge infection was given using 200,000 oocysts per bird. The unmedicated birds (Group A) developed subclinical coccidiosis after the trickle infections with excretion of oocysts and a slightly decreased growth performance. At challenge, a good protective unimmunity was present, reflected by a good growth performance and a low oocyst excretion. The unimmunized birds (Group C) developed a severe clinical disease after challenge with high oocyst output, increased mortality, and poor growth performance. The diclazuril-medicated, trickle-infected birds (Group B) were well protected, both against the immunizing trickle infections and the challenge infection. After challenge, no clinical disease developed, although some lesions and oocyst excretion were present. It is concluded that, under the conditions of the trial, diclazuril did not significantly interfere with protective immunity formation against E. tenella.

Animals↗