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S Roels

Publications and source records attributed to S Roels.

At least 37 records · Page 2Linked to original sources
PubMed2000

Proliferation, DNA ploidy, p53 overexpression and nuclear DNA fragmentation in six equine melanocytic tumours.

Melanocytic tumours are a well-known clinical and pathological entity in horses, but further phenotypic characterization of these tumours is lacking. Six melanocytic tumours from five horses (two metastatic and four benign) were examined by Ki67, PCNA and p53 immunostaining, DNA nick end labelling (Tunel) and Feulgen staining. The stainings were evaluated using quantitative image analysis. The resulting parameters of growth fraction (Ki67), S-phase index (PCNA), p53 index, apoptotic index, DNA index, nuclear diameter, ploidy balance, proliferation index (Feulgen) and hyperploidy were analysed. The metastatic melanomas showed overexpression of p53 in a large portion of the cells. Apoptosis was also found in the metastatic melanomas. No differences were found in growth fraction, S-phase index (PCNA) nor in DNA configuration between the metastatic and the benign tumours. No immunohistochemical evidence of mutant p53 could be found in the tumours. In conclusion, melanocytic tumours in horses seem to have different phenotypic characteristics in comparison with melanocytic tumours in dogs, cats and humans, especially with respect to proliferative activity of the benign tumours. Therefore, markers put forward in these other species for predicting the clinical behaviour of the melanomas seem to be of no value in the horse. Moreover, quantitative DNA changes or p53 mutations do not seem to be involved in tumourogenesis in these cases.

Animals↗
PubMed1999

The multiply-regulated gabA gene encoding the GABA permease of Aspergillus nidulans: a score of exons.

We describe the cloning, sequence and expression of gabA, encoding the gamma-amino-n-butyrate (GABA) permease of the fungus Aspergillus nidulans. Sequence changes were determined for three up-promoter (gabI ) and six gabA loss-of-function mutations. The predicted protein contains 517 residues and shows 30.3% overall identity with a putative GABA permease of Arabidopsis thaliana, 29.6% identity with the yeast choline transporter and 23.4% identity with the yeast UGA4 GABA permease. Structural predictions favour 11-12 transmembrane domains. Comparison of the genomic and cDNA sequences shows the presence of 19 introns, an unusually large number of introns for, we believe, any fungal gene. In agreement with the wealth of genetic data available, transcript level analyses demonstrate that gabA is subject to carbon catabolite and nitrogen metabolite repression, omega-amino acid induction and regulation in response to ambient pH (being acid-expressed). In agreement with this, we report consensus binding sites 5' to the coding region, six each for CreA and AREA and one for PacC, the transcription factors mediating carbon catabolite and nitrogen metabolite repression and response to ambient pH respectively.

Amino Acid Sequence↗
PubMed1999

PCNA and Ki67 proliferation markers as criteria for prediction of clinical behaviour of melanocytic tumours in cats and dogs.

Melanocytic tumours in domestic animals vary from benign to highly malignant. Diagnosis and prognosis are mainly based on the somewhat uncertain interpretation of cytological signs of malignancy in histological sections. The purpose of the present retrospective study was to compare the accuracy of prognosis based on the classical morphological criteria with that provided by quantitative computerized analysis of proliferation-associated antigens. Twenty-seven melanocytic tumours (20 canine and seven feline) from 24 animals (20 dogs and four cats) were examined. These comprised eight tumours histologically classified as benign melanoma (BM) (seven canine, one feline), 16 classified as primary malignant melanoma (PMM) (13 canine, three feline) and three classified as metastatic melanoma (MMM) (three feline). Tumour size, predominant histological cell type, invasive growth and clinical outcome were recorded for each case. In addition, the proliferation (phase) index and growth fraction were measured, after bleaching, by means of quantitative image analysis of tissue sections immunolabelled for proliferating cell nuclear antigen (PCNA) and MIB-1 (Ki67). Lesions classified histologically as benign or malignant, differed significantly (Copyright P<0.001) in respect of Ki67 and PCNA positivity. No such difference could be shown between PMM and MMM. High growth fraction (measured by the Ki67 positive cells) and macroscopic invasive growth were associated with decreased survival time (P=0.027 and P=0.024, respectively). Moreover, the established cytological classification also proved to be associated with the survival time (P<0.001). The results suggest that Ki67 is a potentially important prognostic factor in melanomas of the cat and dog. Other criteria, including tumour size, predominant cell type and intensity of PCNA expression, were not of significant prognostic value (P>0.05).

Animals↗
PubMed1998

Acute pancreatitis in chickens due to non-virulent Newcastle disease virus.

A non-virulent Newcastle disease virus (strain APMV-1 96/89 VB) was isolated from a broiler chicken from a backyard flock. Using monoclonal antibodies, the virus was shown to be different from the vaccinal virus strains Hitchner, La Sota and Ulster. The virus was shown to replicate in the pancreas of one-day-old specific pathogen-free chickens infected orally, and the histological lesions observed in the pancreas of chickens inoculated with the fourth chicken passage of the virus five to nine days after infection were consistent with an acute pancreatitis.

Animals↗
PubMed1998

Verrucous endocarditis due to Escherichia coli in a Persian cat.

Verrucous endocarditis of the aortic valves was diagnosed postmortem in a Persian cat that died after showing clinical signs of dyspnoea, hypothermia and anorexia. Bacterial colonies were evident on Giemsa-stained sections of the valves and Escherichia coli was isolated from the endocarditis lesions.

Animals↗
PubMed1998

Malignant melanoma of the nictitating membrane in a cat (Felis vulgaris).

A case of malignant melanoma of the nictitating membrane in a 10-year-old cat is described. The primary unilateral tumour mass appeared to originate from the surface of the nictitating membrane, with infiltrative growth in the orbital cavity, resulting in exophthalmia. No ocular involvement was noted. Metastatic spread was seen in the cerebrum and the lungs. To our knowledge, this is the first reported case of a metastasizing melanoma originating from the nictitating membrane in a cat.

Animals↗
PubMed1998

Successful treatment of an equine preputial fibrosarcoma using 5-fluorouracil/evaluation of the treatment using quantitative PCNA and Ki67 (MIB 1) immunostaining. (case report).

An 18-month-old cross-bred Fjord pony colt presenting a fibrosarcoma of the prepuce with severe infiltrative growth, was treated by topical application of 5-fluorouracil. Biopsies were taken before and after a treatment period of 2 months. As a control, preputial tissue from a healthy horse was biopsied. Tissue sections were stained immunohistochemically for Proliferating Cell Nuclear Antigen (PCNA) and Proliferation related factor--Ki67 (MIB1). Using computerized quantitative image analysis of these sections, Mitotic index (PCNA), Growth Fraction (Ki67) and total nuclear area percentage of the dermis were calculated. The Mitotic index, growth fraction and total nuclear area percentage were significantly (P < 0.001) reduced at the end of the treatment period compared to the initial biopsy tissue, but they still were significantly higher than the control values, due to a remnant inflammatory reaction to the cytostatic drug. After treatment of the lesion, the pony fully recovered with no visible residual lesions on the prepuce. On follow-up 6 months after treatment, the horse showed no signs of recurrence. The success of the present treatment should encourage further clinical trials in cases of malignant fibrous tumours of skin in horses. The quantitative analysis of cell proliferation in biopsies can be used to evaluate treatment follow-up.

Animals↗
PubMed1997

Treatment of a dog with an insulinoma-related peripheral polyneuropathy with corticosteroids.

A crossbreed dog with a history of a chronic progressive tetraparesis had an insulinoma-related peripheral polyneuropathy. Frequent feeding and treatment with corticosteroids resulted in recovery from a non-ambulatory to an almost completely normal clinical state, despite the persistence of hypoglycaemia and hyperinsulinism. After euthanasia for uncontrollable seizures, the presence of a beta-cell carcinoma of the pancreas and extensive axonal degeneration of the peripheral nerves was confirmed by histopathological examination. These findings may indicate an immune-mediated pathogenesis for insulinoma-related peripheral polyneuropathy.

Animals↗
PubMed1997

Juvenile nephropathy in a Weimaraner dog.

A case of juvenile nephropathy in a two-year-old Weimaraner bitch is reported. Although Juvenile nephropathy has been described in several breeds of dogs, this is the first report in a Weimaraner. Clinical aspects, blood analysis, renal pathology and extrarenal changes are described. The renal changes consisted of tubular as well as glomerular lesions, similar to those described in the miniature schnauzer. The main extrarenal lesion was degeneration and necrosis of subendocardial myocytes in the left atrial wall associated with an inflammatory reaction and focal necrotising arteritis.

Animals↗
PubMed1997

A Bacillus subtilis gene encoding a protein similar to nucleotide sugar transferases influences cell shape and viability.

Bacillus subtilis gene ypfP, which is located at 196 degrees on the genetic map, shows similarity to both the monogalactosyldiacylglycerol synthase gene of Cucumis sativus, which encodes a galactosyltransferase, and the murG genes of B. subtilis, Escherichia coli, Haemophilus influenzae, and Synechocystis sp. strain PCC6803, which encode N-acetylglucosaminyltransferases involved in peptidoglycan biosynthesis. Cells containing a null mutation of ypfP are shorter and rounder than wild-type cells during growth in Luria-Bertani medium and glucose minimal medium. In addition, the mutant cells preferentially undergo lysis when grown on solid Luria-Bertani medium.

Acyltransferases↗
PubMed1996

Quantitative image analysis as an alternative to chemical analysis for follow-up of liver biopsies from a toucan with hemochromatosis. A technique with potential value for the follow-up of hemochromatosis in humans.

OBJECTIVE: To compare the reliability of quantitative image analysis of histologic sections versus chemical analysis for determination of the iron content of serial liver biopsies taken at regular intervals after the onset of treatment, in a case of hemochromatosis in a channel-billed toucan treated with deferoxaminemesilate in combination with a low-iron diet. STUDY DESIGN: Two different image analysis systems were used, one developed for working with black-and-white pictures and another capable of processing colored images. Using Pearson's correlation test, the results with both quantitative image analysis systems were compared to the results obtained by chemical analysis. RESULTS: There was a good correlation between the results of chemical analysis and those obtained with each of the two image analysis systems (0.86 and 0.89, respectively, with a confidence interval of 95%). The results of these serial liver biopsies indicated that the bird responded well to treatment. CONCLUSION: Quantitative image analysis can be used to evaluate follow-up of this disease in toucans as an alternative to chemical determination of the iron content in biopsies of the liver. this technique may have potential value in follow-up of hemochromatosis in humans.

Animals↗
PubMed1995

Accumulation of protoporphyrin isomers I and III, and multiple decarboxylation products of uroporphyrin in a case of porphyria in a slaughtered pig.

Pathological and biochemical examinations were made on tissues from a case of porphyria in a slaughtered pig. Bones, kidneys, teeth and lymph nodes showed a mahogany discoloration. Histologically, the pigment was negative on staining for iron (Gomori) and showed a strong red-orange fluorescence under UV light proving it to be porphyrin. Biochemical studies on the kidney, lymph nodes, bone and bone marrow revealed a 'mixed' erythropoietic protoporphyria-coproporphyria. This indicates that the case presented probably represented both a uroporphyrinogen decarboxylase and uroporphyrinogen-III-cosynthase dysfunction.

Abattoirs↗
PubMed1995

Adjacent and divergently oriented operons under the control of the sporulation regulatory protein GerE in Bacillus subtilis.

The DNA-binding protein GerE is the latest-acting regulatory protein in the mother cell line of gene expression during sporulation in Bacillus subtilis. GerE directs the transcription of several genes that encode structural components of the protein coat that encases the mature spore. We report on the identification and characterization of a cluster of additional genes whose transcription is dependent on GerE. These genes, which are located in the replication terminus region of the chromosome (181 degrees on the genetic map), are arranged in adjacent and divergently oriented operons called cgeAB and cgeCDE, which consist of two and at least three genes, respectively. CgeD, the product of the second member of the cgeCDE operon, is strikingly similar to the product of a B. subtilis gene (ipa-63d) of unknown function and is similar at its amino terminus to certain glycosyl transferases involved in polysaccharide biosynthesis. Strains with mutations in the cgeAB and cgeCDE operons produce spores with altered surface properties, on which basis we propose that proteins encoded by these operons influence maturation of the outermost layer of the spore, perhaps by glycosylation of coat proteins at the spore surface.

Amino Acid Sequence↗
PubMed1994

An unusual outbreak of Streptococcus bovis septicaemia in racing pigeons (Columba livia).

In December 1991, an outbreak of Streptococcus bovis septicaemia occurred in a Belgian pigeon loft where 25 male and 25 female racing pigeons were housed. The main clinical signs included inability to fly and poor breeding results. None of the female pigeons and only one male pigeon was able to fly. Nine affected pigeons were necropsied. Histologically a tenosynovitis of the tendon of the deep pectoral muscle was observed in most of them and S bovis was isolated from the canalis triosseus or the shoulder joints of five of the nine pigeons. The pigeons were successfully treated with ampicillin administered in the drinking water for seven days.

Animals↗
PubMed1994

Subcellular localization of proteins involved in the assembly of the spore coat of Bacillus subtilis.

Spores of the bacterium Bacillus subtilis are encased in a two-layered protein shell, which consists of an electron-translucent, lamellar inner coat, and an electron-dense outer coat. The coat protein CotE is both a structural component of the coat and a morphogenetic protein that is required for the assembly of the outer coat. We now show that CotE is located in the outer coat of the mature spore and that at an intermediate stage of sporulation, when the developing spore (the forespore) is present as a free protoplast within the sporangium, CotE is localized in a ring that surrounds the forespore but is separated from it by a small gap. We propose that the ring is the site of assembly of the outer coat and that the gap is the site of formation of the inner coat. Assembly of the ring depends on the sporulation protein SpoIVA, which sits close to or on the surface of the outer membrane that encircles the forespore. We propose that SpoIVA creates a basement layer around the forespore on which coat assembly takes place. The subcellular localization and assembly of CotE and other coat proteins are therefore determined by the capacity of SpoIVA to recognize and adhere to a specific surface within the sporangium, the outer membrane of the forespore.

Bacillus subtilis↗