Biomedical subjects
D Maes
Publications and source records attributed to D Maes.
Lower bounds for the asymptotic rate of dispersion in generalized Taylor diffusion.
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Malignant melanoma of the glans penis.
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Antireflux in adults: a long-term follow-up.
The long-term results after antireflux operation in 47 adults are presented. Reflux was eliminated in all but 3 cases. Preoperatively most patients complained of urinary tract infection with or without fever, but sometimes investigation for hypertension or urolithiasis also led to the diagnosis. Postoperatively 70% of the patients are free of symptoms and infection. Renal scarring in pyelonephritic patients seems to stop after intervention. In all patients with a normal preoperative creatinine level, this level stays normal after the intervention. However, in 6 of 7 patients with a creatinine level of greater than 1.5 mg% before operation, the intervention could not stop the evolution toward terminal renal failure.
The spatial distribution of zinc and cobalt in single human head hairs.
The concentration patterns of indigenous zinc and of zinc and cobalt absorbed from radiotracer solutions have been measured via flameless AA and radioactivity assay, respectively, in individual human head hairs. Patterns for indigenous zinc were found to be relatively flat and featureless. Patterns for absorbed zinc (like those for indigenous and absorbed copper in the same subjects) showed increasing concentrations with increasing distance from the root, plus zones of locally increased concentrations at positions different from those for zones of increased copper concentrations. In bleached hair, indigenous zinc concentrations were decreased, and absorbed zinc and cobalt concentrations were increased compared to values in normal hair. The data for absorbed zinc and cobalt were interpreted in terms of a variable concentration of metal-binding sites in the hair structure, coupled with an increased porosity induced by hair bleaching. The flat patterns for the indigenous zinc content were interpreted as indicating the importance of dietary zinc and incorporation via the follicle, and the unimportance of external contamination as the source of this zinc. The forensic implications of the data have been discussed.
The absorption of arsenic into single human head hairs.
Single head hairs from several subjects have been soaked in arsenic radiotracer solution and the arsenic absorbed on 2-mm hair segments has been determined by radioactivity assay. The absorption patterns were characterized for some subjects by regions of high uptake where (in other hairs from the same subject) regions of low uptake of copper and zinc were found, and vice versa. These data have been interpreted in terms of varying densities of binding sites in the hair structure, with specific chemical character. Arsenic absorption patterns for other subjects were highly structured, showing zones of very high and very low absorption. The dangers of interpreting similar patterns for the indigenous arsenic content of hair in terms of the dates on which elevated arsenic ingestion took place have been discussed.
The spatial distribution of copper in individual human hairs.
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Herd factors associated with the seroprevalences of four major respiratory pathogens in slaughter pigs from farrow-to-finish pig herds.
The objective of this study was to investigate sero-epidemiological aspects of Mycoplasma hyopneumoniae (Mh), influenza H1N1 and H3N2 viruses and Aujeszky disease virus (ADV) in fattening pigs from 150 randomly selected farrow-to-finish pig herds. Different herd factors were examined as potential risk indicators for the percentage of pigs with antibodies against the 4 pathogens. The median within-herd seroprevalences of the pathogens were: Mh 76%, H1N1 100%, H3N2 40% and ADV 53%. There was a positive association between the seroprevalences of both influenza viruses, and a negative association between the seroprevalences of ADV and H1N1. The percentage of pigs seropositive for Mh increased with the purchase of gilts and with the season (slaughter date in March-April). The within-herd seroprevalences of both influenza viruses were higher in the case of a higher density of pig herds in the municipality. A higher number of fattening pigs per pen additionally increased the risk of being seropositive for H3N2. The percentage of pigs with anti-gE-antibodies against the wild type ADV increased with higher airspace stocking density in the finishing unit, increasing herd size, increasing number of pig herds in the municipality and slaughter date in March-April. Increased seroprevalences for these 4 respiratory pathogens were mostly associated with pig density in the herd and its vicinity, the winter period, and with the purchase of gilts. Purchase of gilts, number of fattening pigs per pen and airspace stocking density are risk factors that can be managed directly by farmers striving to attain a high respiratory health status of pigs.
Herd factors associated with the seroprevalences of Actinobacillus pleuropneumoniae serovars 2, 3 and 9 in slaughter pigs from farrow-to-finish pig herds.
This cross-sectional epidemiologic study was conducted in 150 randomly selected farrow-to-finish pig herds to investigate descriptive epidemiological characteristics of infections with three different serovars of Actinobacillus pleuropneumoniae, and to identify risk factors for the within-herd seroprevalences of these serovars. Different farm characteristics (n = 28) were examined as potential risk factors for the percentage of pigs with antibodies against serovars 2, 3 and 9. The presence of antibodies was measured using an indirect ELISA. Logistic regression analyses were used to assess the associations between the potential risk factors and the proportion of seropositive pigs. The median within-herd seroprevalences were 95% (range: 0-100%), 100% (range: 10-100%), and 35% (range: 0-100%) for serovars 2, 3, and 9, respectively. There was a positive association (P < 0.001) between each of these serovars. The within-herd seroprevalence of serovar 2 was significantly higher in farms that purchased gilts from > or = 2 origin herds (OR = 2.33; P < 0.05) and in farms with poor biosecurity measures (OR = 4.62; P < 0.05). The proportion of pigs seropositive for serovar 3 was significantly higher when tested pigs were slaughtered in May-August and in November-December (OR = 5.96; P < 0.001), in herds without a growing unit (OR = 2.63; P < 0.01), and in herds with a direct air-entry into the finishing unit (OR = 1.92; P < 0.05). The within-herd seroprevalence of serovar 9 increased significantly in herds with poor biosecurity measures (OR = 1.76; P < 0.05). The study documented that infections with A. pleuropneumoniae serovars 2, 3, and 9 were very common in the selected herds, and that the sero-epidemiological characteristics and risk factors showed some variation depending on the serovar. The purchase policy of gilts and biosecurity measures are risk factors that can be improved fairly easily on pig farms.
Protection against endogenous and UVB-induced oxidative damage in stratum corneum lipids by an antioxidant-containing cosmetic formulation.
A 16-week human clinical study was carried out to determine the ability of antioxidants in a cosmetic vehicle to inhibit the induction of lipid peroxidation in stratum corneum lipids. The study consisted of a twice daily application of material for 12 weeks followed by a 4-week regression phase. Stratum corneum lipids were collected and then exposed to 500 mJ/cm2 of ultraviolet B (UVB) radiation in order to avoid excessive erythemal damage to the subjects. Lipid peroxides were assayed by a methylene blue derivative assay and expressed per unit area of skin. During the treatment period, decreases in the level of lipid peroxides were observed on the sites treated with the compositions containing antioxidants, as compared to the untreated sites, and expressed as percent differences. Decreases were observed in endogenous as well as UV-induced lipid peroxides followed by a return to baseline levels. These results demonstrate that antioxidants in a topical cosmetic formulation were effective in protecting human stratum corneum lipids against endogenous oxidation or if challenged by 500 mJ/cm2 UVB.
The induction of terminal differentiation markers by the cAMP pathway in human HaCaT keratinocytes.
The terminal differentiation of human epidermal keratinocytes is a complex morphological and biochemical shift from a mitotically active cell to an inert protein cross-linked envelope. This transition is a clearly predetermined cell death mechanism, but it is unlike many other programmed cell deaths in that it is not apoptotic. To explore and contrast the mechanism by which keratinocytes are committed to differentiation rather than apoptosis, we focused on the cyclic adenosine monophosphate (cAMP) signaling pathway using selective modulators of intracellular cAMP levels. Markers of differentiation were assayed by Western blotting. Raising intracelluar cAMP levels by treating HaCaT cells with forskolin, a diterpene, or with isobutylmethylxanthine, a phosphodiesterase inhibitor, and isoproterenol, a beta-adrenergic receptor agonist that selectively activates adenylate cyclase, increased the levels of the differentiation markers keratin K1 and K10, involucrin and transglutaminase. H89 and KT5720, both inhibitors of cAMP-dependent protein kinase, suppressed the expression of keratins K1 and K10. These observations are in line with the defined role for cAMP in the control of keratinocyte differentiation.
Correlation between in vitro cyclic adenosine monophosphate phosphodiesterase inhibition and in vivo anti-inflammatory effect.
We tested the hypothesis that topical adenosine monophosphate phosphodiesterase (cAMP PDE) inhibitors are anti-inflammatory. These can be shown by a correlation between PDE inhibitory and anti-inflammatory function of a series of known PDE inhibitors. The effect of various cAMP PDE inhibitors on PDEs isolated from HaCaT cells was first investigated. These compounds were then tested as anti-irritants against topical 8% Balsam of Peru. A direct correlation was observed between the in vitro EC(50) values for PDE inhibition and the in vivo anti-inflammatory potential with a correlation coefficient of r = 0.79. These results stress the value of PDE inhibitors as anti-inflammatory agents in topical use, and also demonstrate that the in vitro PDE assay can be used to predict in vivo anti-inflammatory potential.
Cigarette smoke-induced lipid peroxidation in human skin and its inhibition by topically applied antioxidants.
Cigarette smoke, whether indirect or direct stream, is an environmental pollutant which presents an increasing health problem. In order to determine damage to human skin at the biochemical level, volar forearms were exposed to cigarette smoke for fifteen minutes and then assayed for the presence of stratum corneum lipid peroxides. A time-dependent increase was observed over a 24-hour post-exposure period. At 24 h, the average baseline level of lipid peroxides was 14.9 nmol/unit area of skin as compared to 32.0 nmol/unit area of skin for the smoke-exposed arms. In addition, when topical antioxidants were pre-applied to the skin and then exposed to cigarette smoke, an average decrease of 40.9% in lipid peroxide values was observed. These data demonstrate that peroxidation was induced in human skin by cigarette smoke and subsequently inhibited by the presence of antioxidants.
Normal human keratinocytes pretreated with damaged mRNA are resistant to UVB damage and exhibit increased DNA repair.
Treatment of normal human keratinocytes with UVC-irradiated rabbit globin mRNA 24 h before and after UVB exposure increased the survival of the human keratinocytes. We also observed that UVC-damaged mRNA reduced the formation of sunburn cells in skin models. We next tested the effects of UVC-damaged mRNA on cellular repair of DNA. DNA repair was evaluated using 2 assay methods. The first method used a damaged plasmid that is transfected back into the cell where it is repaired by the host cell repair mechanism. In these experiments, we observed that externally added UVC-damaged rabbit globin mRNA enhanced the repair of a plasmid transfected into the host keratinocyte cells. The second method used to determine the effects on DNA repair was direct immunostaining for thymidine-thymidine dimers (TT dimers) in histological sections of the skin models. Skin models were irradiated with UVB and then fixed immediately or after 24 h and stained for TT dimers. UVB irradiation immediately caused an increase in the number of stained keratinocytes in the skin. The number of stained cells decreased in skin fixed 24 h after UVB. This is due to repair of the TT dimers and their removal. Sections of skin models pretreated with UV-damaged mRNA exhibit greater removal of these TT dimers after 24 h. The above evidence suggests that damaged mRNA can trigger a host cell DNA repair pathway.
Floating right heart thrombi and pulmonary embolism: diagnosis, outcome and therapeutic management.
The aim of this study was to analyze clinical and echographic findings and to assess therapeutic management in 14 floating right atrial thrombi diagnosed with systematic echocardiography in 200 consecutive patients with proven pulmonary embolism. Auscultatory findings were abnormal in 7 cases, 4 of them showing signs of tricuspid obstruction. Echocardiography displayed a mobile ovoid, polycyclic or worm-like right atrial mass, always associated with signs of cor pulmonale. Four patients (29%) died, 2 of them before any treatment could be started. Regarding the remaining 10 patients with favorable outcome, surgical embolectomy was carried out in 7. Our data suggest that echocardiographic examination is necessary in all suspected pulmonary embolisms and has to be done quickly for emergency treatment in patients with floating right atrial thrombus.
Evaluation of cross-protection afforded by a Salmonella Choleraesuis vaccine against Salmonella infections in pigs under field conditions.
This field study investigated the efficacy of a Salmonella Choleraesuis live vaccine (Argus SC) to reduce the number of infections with Salmonella. Twelve groups of about 380 pigs each were randomly allocated to either vaccination (V) or no vaccination (C). The vaccine was applied orally at 3 and 16 weeks. Forty pigs per group were blood sampled at 3, 10, 16, and 24 weeks to detect possible antibodies against Salmonella. The prevalence of Salmonella in the lymph nodes was the major variable. In the V groups, only 0.6% of the lymph nodes were positive, whereas 7.2% were positive in the C groups (p < 0.001). The percentage of seropositive pigs at 24 weeks (cut-off OD > 10) was 26% and 9% in the V and C groups, respectively (p < 0.001). The present study documented that vaccination with a live modified S. Choleraesuis vaccine is a useful tool to lower the prevalence of Salmonella in swine herds.
A test for antioxidant activity in cosmetic formulations.
The aim of this study was to develop a technique to assay for the activity of antioxidants in a finished cosmetic product. This was accomplished by adapting the Randox Assay for Total Antioxidant Status kit so that diluted samples could be evaluated by kinetic as well as end-point determinations. Using this technique, we found that a finished product had an IC(50) of 0.07 gm of product and a relative antioxidant activity concentration of 52.7 nmoles/mg.