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Biomedical subjects

L Maes

Publications and source records attributed to L Maes.

At least 55 records · Page 3Linked to original sources
PubMed1990

Comparative efficacy of closantel and triclabendazole against Fasciola hepatica in experimentally infected sheep.

The effect of closantel (10 mg/kg orally) and triclabendazole (10 mg/kg orally) on the reappearance of a patent infection of Fasciola hepatica was studied in experimentally infected sheep. The treatments resulted in the interruption of faecal egg output for 11 weeks with triclabendazole and 13 weeks with closantel. Necropsy of untreated control animals revealed a mean burden of 360 flukes with a mean (+/- se) surface area of 171 +/- 64.3 mm2, whereas the fluke burdens in the closantel and triclabendazole-treated animals 14 weeks after treatment were 61 (83 per cent reduction) and 21 (94 per cent reduction), respectively. The surface areas of the flukes in the triclabendazole-group were comparable with the untreated controls (141 +/- 51.8 mm2), but the flukes in the closantel group were markedly smaller (43.1 +/- 26.9 mm2). It is concluded that closantel has, in epidemiological terms, a potency comparable with that of triclabendazole, despite its slightly lower efficacy against the very immature stages.

Animals↗
PubMed1990

The relationships between the cortisol responses to dexamethasone and to L-5-HTP, and the availability of L-tryptophan in depressed females.

In order to investigate the relationships between the hypothalamic-pituitary-adrenal (HPA)-axis activity, the central serotonergic neurotransmission, and the peripheral metabolism of l-tryptophan (L-TRP), the authors measured the following: the postdexamethasone cortisol values, the cortisol responses to 125 mg 5-hydroxy-L-tryptophan (L-5-HTP) orally, and the total L-TRP/competing amino acids (CAA) ratio in 64 depressed females. Severely depressed females showed significantly lower values for L-TRP/CAA, significantly higher postdexamethasone cortisol values, and cortisol responses to L-5-HTP as compared with minor depressives. Dexamethasone nonsuppressors showed significantly lower L-TRP/CAA values as compared with suppressors. The cortisol responses to dexamethasone were significantly and negatively correlated with the availability of L-TRP. The cortisol responses to L-5-HTP were not related to either the availability of L-TRP or to the postdexamethasone cortisol values.

5-Hydroxytryptophan↗
PubMed1990

A revised interpretation of postdexamethasone ACTH and cortisol findings in unipolar depressed females.

Baseline 8 a.m. adrenocorticotropic hormone (ACTH) and cortisol levels and the postdexamethasone ACTH/cortisol values at 8 a.m. and 4 p.m. were determined in 86 depressed females diagnosed using DSM-III criteria. Postdexamethasone ACTH and cortisol values were significantly correlated with their baseline levels. We have shown that regression analysis should be used to assess dexamethasone-induced changes as the residual ACTH and cortisol responses, with the relative effects of the baseline data on the hormone responses being partialed out. The residual ACTH and cortisol values were significantly increased in the most severely depressed females as compared to minor depressives. The residual ACTH responses were markedly correlated with the residual cortisol responses. Cortisol nonsuppression during a depressive episode appeared to be determined by an augmented ACTH escape from dexamethasone suppression. The residual ACTH and cortisol responses could prove to be the most sensitive reflection of the disorder in the negative feedback by dexamethasone on the pituitary. In clinical practice, the ratio ln (postdexamethasone ACTH): ln (basal ACTH) can be used, since this ratio is linearly correlated with the residual ACTH responses.

Adrenocorticotropic Hormone↗
PubMed1990

Clinical subtypes of unipolar depression: Part I. A validation of the vital and nonvital clusters.

Cluster analyses were carried out on a sample of 100 depressed females. The study was based on the 14 items relevant to depressive phenomenology of the Structured Clinical Interview for DSM-III-R (SCID). Our findings support the existence of two classes, i.e., a vital (melancholic) vs. a nonvital cluster. The vital cluster is characterized by the following symptoms: a distinct quality of depressed mood, nonreactivity, early morning awakening, anorexia-weight loss, and cognitive and psychomotor disturbances. Patients belonging to the vital cluster exhibit disorders in the hypothalamic-pituitary-adrenal and thyroid axes and a markedly decreased availability of L-tryptophan to the brain. The vital depressives score significantly higher on the Hamilton Rating Scale for Depression as compared to those suffering from nonvital depression. The cluster-analytically derived class of vital depression and the DSM-III subtype of melancholia tend to be quite similar. Our findings support the isolation and the descriptive validity of a vital (melancholic) depressive syndrome.

Adult↗
PubMed1990

Clinical subtypes of unipolar depression: Part II. Quantitative and qualitative clinical differences between the vital and nonvital depression groups.

This study examines whether the differences in the cluster-analytically generated classes--nonvital versus vital depression--are dimensional (quantitative) rather than categorical (qualitative). To this end, we used various pattern-recognition methods based on principal component analysis (PCA), e.g., display methods (PC plotting), eigenanalysis, and SIMCA (statistical isolinear multiple components analyses). We found several arguments supporting the dimensional hypothesis that the nonvital and vital classes constitute relevant stages (continuous categories) in the continuum of illness-severity. Nevertheless, we found some arguments supporting the categorical hypothesis that the cluster-analytically generated classes are qualitatively different with reference to the similarity of the vital symptoms. Our findings suggest that a nosological or categorical classification is possible from the moment that one component (i.e., the vital component) is quantitatively prominent to the extent that it has become qualitative. As the overall severity of illness increases, vital symptoms emerge which, grouped together, shape a new symptom profile (i.e., vital depression). Thus, our results favor the hypothesis that there are simultaneous quantitative (dimensional: overall severity of illness) and qualitative (categorical: vital symptoms) differences between the nonvital and vital depression groups.

Adult↗
PubMed1990

Clinical subtypes of unipolar depression: Part III. Quantitative differences in various biological markers between the cluster-analytically generated nonvital and vital depression classes.

The hypothalamic-pituitary-adrenal (HPA) axis, the hypothalamic-pituitary-thyroid (HPT) axis, and the availability of L-tryptophan (L-TRP) to the brain were studied in their relationships to (1) 14 depressive symptoms measured by the Structured Clinical Interview for DSM-III-R--Patient Version (SCID) and (2) the cluster-analytically generated vital/nonvital classes. The following biological parameters were measured in 100 depressed females: free thyroxine (FT4), baseline thyroid stimulating hormone (TSH), predexamethasone and postdexamethasone cortisol and adrenocorticotropic hormone (ACTH) values, the circulating levels of total L-TRP, and the L-TRP/sum of competing amino acids ratio. We found that the psychopathological correlates of disorders in the HPA/HPT axis and of a decreased availability of L-TRP were vital symptoms, i.e., distinct quality of mood, nonreactivity, early morning awakening, anorexia-weight loss, and psychomotor disorders. There was no significant relationship between those biological markers and the nonvital symptoms of the SCID inventory for depressive symptoms. However, we did not validate our SCID clustering in vital and nonvital classes by qualitative differences in the biological variables. It was concluded that our nonvital/vital clusters should be regarded as continuous categories with regard to the biological markers studied; these clusters constitute relevant stages in the continuum of progressing biological dysfunction.

Adrenocorticotropic Hormone↗
PubMed1990

Symptom profiles of biological markers in depression: a multivariate study.

The dexamethasone suppression test (DST), the thyrotropin releasing hormone (TRH) test, and the ratio of plasma L-tryptophan to competing amino acids (L-TRP/CAA) were studied in relation to the 21 items of the Hamilton Depression Rating Scale (HDRS) in 123 depressed patients categorized according to DSM-III. The relationships between the biological data and the items or item clusters of the HDRS were assessed by multivariate analyses. The psychopathological correlates of increased post-dexamethasone cortisol and decreased thyroid stimulating hormone (TSH) responsivity to TRH were middle and delayed insomnia and weight loss. The symptom correlates of decreased availability of L-TRP to the brain were psychic anxiety, depersonalization, obsessions and paranoid symptoms. Core depressive symptoms, i.e. depression, loss of interest, feelings of guilt and suicidal thoughts, were not related to the biological markers.

Adult↗
PubMed1989

Ultrastructural evaluation of the effects of diclazuril on the endogenous stages of Eimeria maxima and E. brunetti in experimentally inoculated chickens.

The ultrastructural morphology of the different endogenous stages of Eimeria maxima and E. brunetti was evaluated after oral treatment of inoculated chickens with a single dose of 5 mg/kg diclazuril. The drug induced no ultrastructural change in the growth or differentiation of the various schizont stages of both Eimeria spp. In E. maxima, the micromorphological appearance of micro- and macrogamonts developing from the blast from to maturation also remained unaffected by drug treatment. However, in all fertilized macrogamonts the normal pattern of oocyst wall establishment was completely disturbed, resulting in the formation of an abnormally thickened, incomplete oocyst wall and the necrosis of the zygote. In E. brunetti, the growth and nuclear division during microgametogenesis were not affected but differentiation was clearly abnormal. In comparison with the controls, this abnormal differentiation was characterized by a less extensive enlargement of the parasite surface area, aberrant morphological configurations of condensed heterochromatin, intracytoplasmic flagella formation, and glycogen accumulation. Finally, the complete degeneration of all microgamonts ensued. The growth and differentiation leading to mature macrogamonts was not disturbed; however, subsequent oocyst wall formation was largely precluded and the macrogamonts proceeded to degenerate completely. We conclude that diclazuril treatment primarily affected particular stages in the sexual development of both Eimeria spp., resulting in the complete eradication of these coccidian species.

Animals↗
PubMed1989

Sex-linked differences in cortisol, ACTH and prolactin responses to 5-hydroxy-tryptophan in healthy controls and minor and major depressed patients.

Some researchers have found that the administration of 5-hydroxytryptophan (5-HTP) results in increased cortisol secretion in major depressives but not in healthy controls. Other authors observed gender-related differences in cortisol responses to 5-HTP in major depressives. In order to investigate the pituitary/adrenal responsivity to 5-HTP, the authors measured cortisol, adrenocorticotropic hormone (ACTH) and prolactin (PRL) in 30 healthy controls and in 90 depressed patients; the hormone levels were determined in baseline conditions and 60, 90 and 120 min after 125 mg L-5-HTP (orally, non-enteric coated). We found that healthy men had significantly higher cortisol responses to L-5-HTP than healthy women. In the major depressives with melancholia and/or psychotic features these differences were reversed: women exhibited significantly higher cortisol and PRL responses than men. In the female group the most severely depressed patients had increased cortisol and PRL responses to L-5-HTP. The amplitudes of the cortisol, ACTH and PRL responses to L-5-HTP were significantly and positively correlated. It was concluded that the central serotonergic regulation of ACTH and PRL is significantly different between the sexes and between healthy controls, minor depressives and severely depressed patients.

5-Hydroxytryptophan↗
PubMed1988

[Safety of a new anticoccidial agent, clazuril, during reproduction in carrier pigeons].

In a six-month study, the safety of repeated treatments with clazuril, a new anticoccidial agent for the treatment of pigeons, was evaluated during 4 to 5 consecutive reproduction cycles. Clazuril was administered weekly at the recommended therapeutic dose level of 2.5 mg/pigeon and at twice this dose. The results were compared to placebo treatment. Evaluation was based on the following parameters: reproductive behaviour, egg laying, fertilisation, embryonic mortality, hatching, percentage of weaning and time interval between consecutive reproductive cycles. Maternal-paternal toxicity (body weight evolution, feather coat) and tolerance in newborn pigeons (general behaviour, daily gain in body weight, feathering, skeletal anomalies) were also evaluated. In all the treatment groups, reproductive performance was comparable and no drug- or dose-related side-effects were observed. Fertilisation, embryonic mortality and the time-interval between the consecutive reproductive cycles remained within the normal physiological range. Hatched pigeons showed a satisfactory daily weight gain and deaths among these birds were exceptional. Tolerance of clazuril in adult as well as in day-old pigeons was exceptionally good and body weight evolution, feathering and mortality were not adversely affected. No drug-related pathological findings or skeletal anomalies were detected in the animals at autopsy. It can be concluded that repeated treatments with clazuril are entirely harmless for pigeons during reproduction, even at double the therapeutic dose level. Clazuril is well tolerated by newborn and growing pigeons, which means that pigeon house group treatments during reproduction may be performed without any risk.

Acetonitriles↗
PubMed1988

In vivo action of the anticoccidial diclazuril (Clinacox) on the developmental stages of Eimeria tenella: a histological study.

Diclazuril, a new benzeneacetonitrile anticoccidial, has potent activity against various stages of Eimeria tenella. A single treatment of experimentally infected chickens during the prepatent phase (up to day 5) results in a complete interruption of the life cycle and oocyst shedding. The first- and second-generation schizonts show extensive degenerative changes that finally result in a complete loss of the parasitic stage. The degeneration is characterized by loss of internal structure, the appearance of many intracytoplasmic vacuoles, and incomplete merogony. The merozoites themselves show similar degenerative changes, including the presence of numerous small vacuoles in the cytoplasm. Diclazuril is also effective against both the micro- and macrogametocytes that have a ballooned appearance and loose their internal structure completely. In the macrogametocytes, wall-forming bodies either do not develop or disappear rapidly. Development of typical caecal lesions is prevented when treatment with diclazuril is initiated before large numbers of second-generation schizonts appear, i.e., day 3. It is concluded that diclazuril is lethal against both the asexual and the sexual stages of E. tenella. At the proposed use level of 1 ppm in the feed, the life cycle is interrupted at a very early stage and lesion development and oocyst shedding are completely prevented.

Animals↗
PubMed1988

In vivo action of the anticoccidial diclazuril (Clinacox) on the developmental stages of Eimeria tenella: an ultrastructural evaluation.

A single 5-mg/kg oral dose of diclazuril affected both the asexual and sexual development of Eimeria tenella in experimentally inoculated chickens. In second-generation schizonts, early growth and nuclear divisions progressed normally, but a marked inhibition of merozoite formation was observed. Exogenesis of merozoites was largely prevented, whereas production of micronemes, amylopectin granules, and dense bodies and the formation of rhoptries, conoid, and pellicle continued. All these subcellular organelles accumulated, together with differentiated nuclei, within the main cytoplasmic mass. In the end, complete necrosis of the schizonts occurred. In macrogamonts, dilation of the rough endoplasmic reticulum around type II wall-forming bodies, fusion of type II wall-forming body contents, disturbance of the normal parallel arrangement of rough endoplasmic reticulum, and disruption of row formation of amylopectin granules became evident. In the microgamonts, normal evagination of microgametes was prevented; the flagellar complex formed within the main cytoplasmic mass and the differentiated nuclei remained present within the parasite body. The macro- and microgamonts also ended up in a stage of complete necrosis. These data indicate that diclazuril treatment primarily affects the normal differentiation of the respective endogenous stages during parasite development. This leads to complete degeneration of schizonts and gamonts indicating the lethal effect of this new anticoccidial compound.

Animals↗
PubMed1988

ELISA assay for melarsoprol.

A sensitive ELISA method has been developed for measuring the trypanocidal drug melarsoprol. The test allows for the detection of the drug in human sera and in cerebrospinal fluid at the ng/ml level. Preliminary analyses on patient sera and CSF confirm the feasibility of the method. Further application of the test will enable to conduct the necessary pharmacokinetic and metabolic studies; the drug monitoring should hopefully result in improved treatment schedules minimizing the undesired side effects, e.g. lethal encephalopathies.

Arsenicals↗
PubMed1988

Action of the anticoccidial clazuril on the endogenous stages of Eimeria labbeana and E columbarum in experimentally infected pigeons.

Racing pigeons were artificially infected with a mixed inoculum of Eimeria labbeana (85 per cent) and E columbarum (15 per cent) and treated orally with 2.5 mg clazuril either on day 1, 2, 3, 4, 5, 6 or 7 after infection. The impact of the treatment on the different developmental stages was evaluated by oocyst output and by histological examination of the duodenum and jejunum. The life cycle always became completely interrupted, but maximal effects were noted when treatment was given on day 4, 5 or 6 after infection. Treatment during patency completely interrupted oocyst excretion within three days after dosing. Degenerative changes in schizonts and gametocytes were always observed. The histology revealed a reduced number and abnormal structure of developing merozoites; a ballooned aspect and presence of numerous small vacuoles in the microgametocytes; the absence of typical wall-forming bodies in macrogametocytes and a complete absence of oocysts. It is concluded that clazuril has a coccidiocidal effect on the asexual and sexual developmental stages of both Eimeria species, resulting in a complete interruption of the life cycle.

Acetonitriles↗
PubMed1988

Flukicidal action of closantel against immature and mature Fasciola hepatica in experimentally infected rats and sheep.

The relative importance of peak level- and residual level-related flukicidal activity of closantel against immature and mature Fasciola hepatica was evaluated in a comparative efficacy trial using two animal species with a different plasma elimination pattern, that is, the rat and the sheep with an elimination half-life of less than one week and of two to three weeks, respectively. The rats were dosed orally with closantel at 20 mg kg-1 at two, four, six, eight and 10 weeks; the sheep at 10 mg kg-1 at eight, 10 and 12 weeks after artificial infection. Necropsy was performed either one week after treatment or 12 weeks after infection. Efficacy rates and the length of the recovered flukes were evaluated. It was demonstrated that the flukicidal effect of closantel is directly related to its peak plasma levels and less to its residual plasma concentrations. In the rat, a high efficacy (P less than 0.001) could be demonstrated against immature stages of four weeks or older. The two-week immature stages were less markedly affected. No significant differences in efficacy and size of the flukes were noted between the animals autopsied one week after treatment and those autopsied 12 weeks after infection. In the sheep, the efficacy against six-week and eight-week-old immature stages varied between 70.3 and 76.8 per cent and between 92.8 and 96.5 per cent, respectively. As in the rats, no marked differences in efficacy were noted between the animals autopsied one week after treatment and those autopsied 12 weeks after infection.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Regeneration of the femoral artery following experimental end-to-end anastomosis in the rat. An ultrastructural follow-up.

An experimental end-to-end anastomosis of the common femoral artery was performed in 45 adult Wistar rats. The vessel wall condition was assessed at 10 min, 3 days, 1, 2, 4, and 8 weeks following surgery by scanning and transmission electron microscopy. The microsurgical procedure inflicts extensive trauma in all layers of the arterial wall, with a desendothelialization largely surpassing the surgical field. Reendothelialization was completed at 2 weeks. Apparently, and as compared to less damaging vessel wall manipulations, such deep medial and wide endothelial lesions do not retard vessel wall healing to normal functionality. Moreover, the formation of primary atherogenic structures by smooth muscle cell migration to the intima seems restricted.

Animals↗