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Biomedical subjects

A Maes

Publications and source records attributed to A Maes.

At least 91 records · Page 5Linked to original sources
PubMed1995

Coping style and preterm labor.

Psychometric tests (State-Trait Anxiety Index and Utrechtse Coping Lijst) were administered to 23 primigravidae hospitalized for preterm labor and to 22 controls in order to investigate whether women with and without preterm labor present a different coping style or (in) effectiveness of this coping and whether the coping style predicts duration of hospitalization and gestational age at delivery. No significant differences in trait anxiety nor in coping style were found between women with and women without preterm labor. However, within the group of women with preterm labor, coping mechanisms are important predictors of course and outcome of the preterm contractions. Palliative coping and social support seeking are protective mechanisms while active coping has an adverse effect upon outcome: an older gestational age at the moment of delivery is for 44% predicted by a higher social support seeking and a lower active coping.

Adaptation, Psychological↗
PubMed1994

Bone marrow trephines. Findings in patients with hairy cell leukaemia before and after treatment.

Bone marrow trephine biopsies from 20 patients with hairy cell leukaemia were reviewed at diagnosis and during therapy with alpha-interferon (IFN) and with 2-chlorodeoxyadenosine (2-CdA). At time of diagnosis the trephines revealed classical features of hairy cell leukaemia and profound alterations of haematopoiesis. All three lines showed dysplastic features with architectural, qualitative and quantitative changes. Review of consecutive trephine biopsies in patients that received IFN showed that a complete remission with disappearance of the tumour was never achieved and that the dysplastic features persisted. An improvement of haematopoiesis was noted, but recovery, especially of the myelopoiesis, was never completely achieved. By contrast, patients treated with 2-CdA de novo and previously treated with IFN achieved a complete remission in all but three cases. The trephine biopsies showed an improvement of haematopoiesis with progressive disappearance of the dysplastic features and a good recovery of myelopoiesis. A residual lymphocytosis was present, but as it was also present in age-matched control cases it could not be considered as a residual tumour. The disappearance of the leukaemic infiltrate probably constitutes a prerequisite for the recovery and normalization of haematopoiesis, while the dysplastic changes present at diagnosis could be the result of cytokine production by the leukaemic cells.

2-Chloroadenosine↗
PubMed1994

Histological alterations in chronically hypoperfused myocardium. Correlation with PET findings.

BACKGROUND: In patients with chronic coronary artery disease (CAD) and left ventricular dysfunction, flow/metabolic studies of the myocardium with positron emission tomography (PET) are able to distinguish viable but dysfunctional myocardium from irreversible ischemic injury and scar tissue. In this study, PET findings of blood flow and metabolism in chronically hypoperfused myocardium were correlated with histology. METHODS AND RESULTS: We studied 33 patients suffering from CAD. In each patient, myocardial blood flow and metabolism were measured with PET 1 or 2 days before revascularization. During surgery, transmural biopsies were taken from the left ventricular anterior wall and planimetrically scored for the degree of myolysis (sarcomere loss). The amount of connective tissue was calculated using morphometric techniques. Contrast ventriculography demonstrated abnormal wall motion in 23 patients. Fourteen patients with a mismatch pattern (decreased flow with preserved metabolism) in the biopsy region after quantitative analysis of the PET data showed 11 +/- 6 vol% fibrosis and 25 +/- 13% cells with sarcomere loss. The space formerly occupied by sarcomeres was mainly replaced by glycogen and mitochondria. A significant wall motion improvement was noted 3 months after surgery. Nine patients showed a match pattern (concordant flow/metabolism defects). The biopsies revealed 35 +/- 25% fibrosis and 24 +/- 15% glycogen-storing cells. The biopsies of the 10 patients with normal anterior wall motion showed 8 +/- 4% fibrosis and 12 +/- 8% glycogen-accumulating cells. CONCLUSIONS: It can be concluded that areas with impaired wall motion and a PET match pattern show extensive fibrosis. Regions with reduced flow and preserved FDG metabolism, however, contain predominantly viable cells. In these regions, significant recovery of wall motion is found after revascularization. Regions with normal wall motion contain predominantly viable cells. Cells with reduced contractile material and increased glycogen content are mainly found in areas with wall motion impairment but are also present in areas with normal wall motion and a severe stenosis of the coronary vessel.

Biopsy↗
PubMed1993

In vitro cytogenetic effects of 2450 MHz waves on human peripheral blood lymphocytes.

Cytogenetic analyses were performed on human peripheral blood lymphocytes exposed to 2450 MHz microwaves during 30 and 120 min at a constant temperature of 36.1 degrees C (body temperature). The temperature was kept constant by means of a temperature probe put in the blood sample which gives feedback to a microcomputer that controls the microwave supply. We found a marked increase in the frequency of chromosome aberrations (including dicentric chromosomes and acentric fragments) and micronuclei. On the other hand the microwave exposure did not influence the cell kinetics nor the sister chromatid exchange (SCE) frequency.

Adult↗
PubMed1993

Stable chromosome aberrations 25 years after severe accidental radiation exposure.

A thorough cytogenetic analysis using G-banding was performed on 100 peripheral blood lymphocytes from an individual who had been accidentally exposed to radiation more than 25 years previously. More than 60% of the analysed cells were found to possess one or more stable chromosome aberrations (e.g. reciprocal translocations). Chromosomes 1 and 11 were more involved in these aberrations than would be expected from the relative chromosome lengths. No identical stable aberrations were found, suggesting that, 25 years after near-lethal exposure, haemopoietic stem cells display substantial diversity.

Accidents↗
PubMed1993

Influence of blood storage after in vitro exposure on the yield of micronuclei observed in human lymphocytes.

In a cooperative study, four laboratories evaluated the micronucleus test in irradiated and non-irradiated lymphocytes with respect to time of storage, the difference between X-ray and gamma exposure and inter-observer variance. The results were compared with parallel studies on dicentric aberrations. No significant differences between laboratories, with respect to storage time or between gamma and X-irradiation were observed for micronuclei and dicentrics using analysis of variance. However, micronuclei are not suitable for an assessment of exposure inhomogeneity because of a significant overdispersion already in controls and homogeneously irradiated samples.

Belgium↗
PubMed1992

The relative importance of the components used for ultraviolet A protection in broad-spectrum sunscreens.

The need for effective ultraviolet A (UVA) protection is increasing. Broad-spectrum sunscreens are being used to protect the skin against aging and in the treatment of photodermatoses, where UVA protection can be vital. They are also used by patients taking photosensitizing drugs, such as 8-methoxypsoralen, to protect their skin against solar UVA. This raises the question of what components in broad-spectrum sunscreens are the most necessary for optimal UVA protection. In the present study, the components that can be used are compared and evaluated using an animal method with the inhibition of skin edema induced by 8-methoxypsoralen plus UVA as the biological end point. The results of this method indicate that powders do not provide any significant UVA protection. This could be due to the use of 8-methoxypsoralen in the test so that particularly the shorter UVA range is evaluated. Powders reflect mainly the longer UVA wavelengths. The UVA protection as measured with this method seems to be similar for the benzophenone derivative and for the dibenzoylmethane derivative. The UVA protection factors obtained are compared with those obtained in human skin using phototoxic erythema and UVA-induced tanning as parameters.

Animals↗
PubMed1990

Imaging of acute myocardial infarction in pigs with Indium-111 monoclonal antimyosin scintigraphy and MRI.

Indium-111 antimyosin F(ab')2 was used in a series of scintigraphic studies on experimentally induced myocardial infarctions in pigs. Antimyosin distribution recorded by planar images of in vivo pigs and by single photon emission computed tomography (SPECT) of excised hearts delineated areas of myocardial necrosis if infarct volume exceeded 3.3 cm3. Scintigraphic images were compared with magnetic resonance images (MRI) obtained from excised hearts and with photographs of slices of the hearts. Infarct size and localization determined with antimyosin were compared. The MR images, with or without gadolinium-DTPA (Gd-DTPA), of the in vivo pigs were all false-negative; some myocardial wall thinning and high bloodpool signals were visible. Results show that both the antimyosin and the MR technique are specific methods for the visualization of induced myocardial necrosis in this animal model. However, the use of antimyosin is limited to a period ranging from 24 to 72 hours after infarction.

Animals↗
PubMed1983

C heterochromatin variation in couples with recurrent early abortions.

The possible influence of the high polymorphic C heterochromatic regions of human chromosomes 1, 9, 16, and Y on meiotic chromosome segregation was investigated. Faulty chromosome segregation may be the result of either an abnormal quantity of C heterochromatin on the homologues, or disequilibrium between the homologues. The aim of our study was to determine whether either a variation in the amounts of total C heterochromatin or differences in the amounts of C heterochromatin between homologues could lead to faulty chromosome segregation. The study was performed on C banded metaphases obtained from peripheral lymphocyte cultures of 15 couples with recurrent early abortions and 15 control couples, all Caucasians. Analysis of variance was first performed on separate metaphases to measure intra-individual, inter-individual, and between population variation in a hierarchical model. Since the significant intra-individual differences covered the other parameters we performed, secondly, a one way analysis of variance on the mean values of metaphases per person in order to measure the inter-individual and between population variation. The results did not show a relationship between C heterochromatin lengths and occurrence of recurrent abortions.

Abortion, Habitual↗
PubMedDate not supplied

A battery of DNA effect biomarkers to evaluate environmental exposure of Flemish adolescents.

The present paper deals with the evaluation of a battery of genotoxicity biomarkers in healthy Flemish adolescents and their relation with common pollutants occurring in their life environment. DNA damage as reflected by the comet assay appeared to be most sensitive to ozone (partial r(2) = 0.102, p < 0.00001), and to a lesser extent to ortho-cresol (partial r(2) = 0.055; p = 0.001) and 1-hydroxy-pyrene (1-OH-pyrene, partial r(2) = 0.031; p = 0.013). 8-hydroxy-deoxyguanosine (8-OHdG) was only related to ortho-cresol (r(2) = 0.069; p < 0.007). Interestingly, the comet assay results and urinary 8-OHdG concentrations were positively correlated with a Pearson r = 0.21 (p = 0.003, N = 200). Logistic regression models revealed significant relations between chromatid breaks and 1-OH-pyrene (relative risk (RR): 1.58; p = 0.008), and t,t-muconic acid (RR: 1.71; p = 0.014). There was no correlation between micronucleus formation or occurrence of chromosomal or chromatid breaks on the one hand and comet or 8-OHdG results on the other hand. Thus, in this study the comet assay on whole blood samples and urine 8-OHdG measurements especially appeared sensitive biomarkers for assessing the genetic effects of environmental pollutants to which adolescents may be exposed.

8-Hydroxy-2'-Deoxyguanosine↗
PubMedDate not supplied

Health risk assessment of dioxin emissions from municipal waste incinerators: the Neerlandquarter (Wilrijk, Belgium).

Two municipal waste incinerators in the vicinity of a residential area close to the city of Antwerp caused concern to local habitants. Risk assessment was performed combining chemical, toxicological measurements and model calculations. As the first step in risk assessment an inventory was made of historic emissions from both incinerators with emphasis on dioxins. The operational atmospheric transport and deposition model for priority substances (OPS) was used to calculate the deposition of dioxins in the vicinity of incinerators. The observed soil contamination pattern did not correspond to the calculated deposition pattern, indicating that other sources may contribute at least partly to the local PCDD/PCDF contamination of the area. Dioxin exposure of people in the Neerlandquarter as a function of the food consumption behavior was calculated using a mathematical model (VLIER-HUMAAN) combined with transfer factors. According to the results of these calculations, just residing in the impact area does not result in a meaningful risk. Only if locally produced food was consumed (milk, meat and vegetables), exposure in the Neerlandquarter was enhanced compared to the average dioxin exposure estimated for the Flemish population. Exposure in 1997 was below the exposure in 1980. As a consequence of different eating habits and lower bodyweight, children are subjected to significantly higher exposure than adults. Adverse health outcomes from dioxin exposure in the past cannot be excluded. There was no evidence for enhanced exposure to genotoxicants based on a comparison of chromosomal damage to blood cells of children from the study area to those from a control group.

Adolescent↗
PubMedDate not supplied

Functional recovery of subepicardial myocardial tissue in transmural myocardial infarction after successful reperfusion: an important contribution to the improvement of regional and global left ventricular function.

BACKGROUND: The transmural extent of myocardial necrosis after an acute coronary artery occlusion can vary considerably. The contribution of residual subepicardial viable myocardium to global left ventricular function is largely unknown. METHODS AND RESULTS: We studied 12 patients with single-vessel disease 1 week after successful reperfusion of a first transmural anterior myocardial infarction (MI). With PET, myocardial blood flow (MBF) and glucose metabolism were measured regionally, and the viability was graded as normal, mismatch, or match with severely (<50% of normal) or intermediately (50% to 80% of normal) impaired MBF. Magnetic resonance tagging was used to regionally quantify fiber strains, wall thickening, and ejection fraction in patients 1 week and 3 months after the MI and in age-matched healthy volunteers. From 1 week to 3 months, subepicardial fiber shortening improved significantly in the match region (MBF <50%, -5.1+/-7.0% to -9.9+/-8. 7%; MBF of 50% to 80%, -7.1+/-7.6% to -14.9+/-7.9%). This was associated with an improvement in regional ejection fraction in the infarcted myocardium (29.6+/-21.8% to 43.5+/-15.5%, P<0.0001) and in normal regions (54.3+/-15.1% to 56.5+/-13.1%, P=0.013), contributing to an increase in global ejection fraction from 44.2+/-22.2% to 49. 3+/-17.9% (P<0.0001). CONCLUSIONS: Functional recovery of viable subepicardial regions is a mechanism of late improvement in regional and global ejection fraction after a so-called transmural MI.

Aged↗