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Biomedical subjects

R Ducatelle

Publications and source records attributed to R Ducatelle.

At least 109 records · Page 6Linked to original sources
PubMed1997

Characterization of avian Chlamydia psittaci strains using omp1 restriction mapping and serovar-specific monoclonal antibodies.

In the present study, 60 avian Chlamydia psittaci isolates were characterized using restriction fragment length polymorphism as well as serovar-specific monoclonal antibodies, enabling a comparison between the two characterization methods. Sixty avian C. psittaci isolates were characterized by Alul restriction mapping of the major outer membrane protein gene omp1 obtained after amplification by the polymerase chain reaction. The 60 avian C. psittaci strains were also characterized using serovar-specific monoclonal antibodies in a microimmunofluorescence test. Digestion of 60 avian C. psittaci omp1 amplicons by Alul generated 5 of the 6 known distinct restriction patterns (A, B, D, E and F). Restriction pattern C was not observed. Serotyping revealed 4 avian C. psittaci serovars (A, B, C and D). None of the 60 isolates was typed as serovar E. AluI restriction patterns A, B, D and E corresponded in 98% of the cases to serovars A, B, C and D, respectively. One isolate, classified as serovar A, generated restriction pattern F instead of A. Genotyping enabled a more precise differentiation of avian C. psittaci serovar A strains. Serovar A strains were divided into two groups according to their Alul restriction pattern (A or F). For epidemiological studies, genotyping can thus be a highly valuable alternative to serotyping, especially when applied directly to the clinical samples.

Animals↗
PubMed1997

Administration of doxycycline hydrochloride via drinking water to turkeys under laboratory and field conditions.

A series of experiments were carried out in order to determine doxycycline hydrochloride (DoxHCl) plasma levels in 6-wk-old turkeys medicated via drinking water containing DoxHCl at a concentration of 250 mg/L under laboratory and field conditions. Maximal plasma concentration (Cmax) values of 5.7 (+/-1.0) microgram/mL and 4.9 (+/-1.4) micrograms/mL obtained after DoxHCl administration during 2 and 7 d, respectively, were not significantly different. A significant difference was found between the area under the plasma concentration-time profile, calculated between 0 and 168 h (AUC(0-168)), Cmax, and the minimal plasma concentration (Cmin) values obtained after medication with a DoxHCl solution at a concentration of 250 mg/L (431.9 +/- 96.6 micrograms.h/mL, 4.9 +/- 1.4 micrograms/mL and 0.7 +/- 0.3 microgram/mL) and after medication with a DoxHCl solution at a concentration of 750 mg/L (1,176.5 +/- 201.8 micrograms.h/mL, 12.5 +/- 2.7 micrograms/mL and 2.9 +/- 0.4 micrograms/mL), respectively. The increase in body weight was also significantly higher for turkeys medicated with a DoxHCl solution at a concentration of 750 mg/L (83.7 g/d) than for the lower concentration (35.6 g/d). The DoxHCl solution uptake significantly decreased with the increase of DoxHCl concentration. A Cmax value of 1.7 +/- 0.6 micrograms/mL and a Cmin value of 0.5 +/- 0.1 microgram/mL were observed during the field experiment. Water consumption under laboratory conditions was followed for tap water (70 +/- 50 mL/kg.d) and for a DoxHCl solution at a concentration of 250 mg/L supplemented with 1 g anhydrous citric acid/L (119 +/- 6 mL/kg.d) and revealed to be not significantly different. The variability was significantly higher for tap water than for the DoxHCl solution. The stability of the DoxHCl solution containing 1 g citric acid/L over 24 h was 99% expressed as the percentage of the initial concentration.

Administration, Oral↗
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↗
PubMed1996

Validation of a high-performance liquid chromatographic method for the determination of doxycycline in turkey plasma.

A high-performance liquid chromatographic method for the analysis of doxycycline in turkey plasma samples using demeclocycline hydrochloride as the internal standard was developed, optimized and validated. A one-step extraction procedure and an isocratic HPLC method with UV detection were used. No interferences with endogenous compounds or with the anticoagulant were observed. Linear calibration curves (r2 > 0.99) were obtained in water and plasma between 0 and 600 micrograms ml-1. Good recoveries for doxycycline (> 66%) and demeclocycline (> 72%) were seen both in water and in plasma. The coefficient of variation was < 9.86% for within-day reproducibility and < 7.53% for the between-day reproducibility. The deviation between the mean value found and the true value was < 14.5% (accuracy). The limit of detection was 0.1 microgram ml-1 in plasma samples. A good stability of doxycycline was observed in water and in plasma samples after storage for six months at -20 degrees C (recovery > 91%).

Animals↗
PubMed1996

Detection of antibodies to Salmonella enteritidis in sera and yolks from experimentally and naturally infected chickens.

An indirect enzyme-linked immunosorbent assay (ELISA) based on the lipopolysaccharide (LPS) of Salmonella enteritidis phage type 4, was developed for the detection of antibodies to salmonella. Sera and yolks from chickens infected experimentally with S enteritidis showed strong positive reactions. Cross-reactions occurred with sera from chickens inoculated with S typhimurium or S gallinarum. Cross-reactions were weak with sera from chickens infected with five strains of other Enterobacteriaceae. The ELISA was tested with sera and yolks from commercial poultry flocks which were bacteriologically negative for salmonella or infected with salmonella serotypes belonging to serogroup D or to other serogroups. The serological reactions were strong in most flocks infected with S enteritidis and were weaker in flocks infected with S typhimurium. In some flocks infected with these serotypes no antibodies were detected. The correct setting of the cut-off value of the optical density in the ELISA makes it possible to discriminate between chickens which are infected with S enteritidis and chickens which are not infected with S enteritidis.

Animals↗
PubMed1996

Oxygenation activity of chicken blood phagocytes as measured by luminol- and lucigenin-dependent chemiluminescence.

Luminol- and lucigenin-dependent chemiluminescence (CL) was used to compare activation of the respiratory burst of chicken peripheral blood monocytes and heterophils after stimulation with various agents. Monocytes and heterophils were obtained from the blood of three specific-pathogen-free chickens at 14 months of age and purified by a two-step discontinuous Percoll gradient. All cells responded to phorbol 12-myristate 13-acetate (PMA), zymosan A and calcium ionophore A23187 producing CL. The time course of luminol- and lucigenin-dependent CL was similar for both monocytes and heterophils after stimulation with PMA or zymosan A. Heterophils at lower cell number than monocytes responded with similar or higher peak maximum (PM) values. At the concentrations of stimuli used, the order of mean PM values was: zymosan A > PMA > A23187. Addition of 4 x 10(-6) M N-formyl-1-L-methionyl-L-leucyl-L-phenylalanine (fMLP) showed weak but significant CL activity at 1 x 10(6) monocytes per tube with luminol and at 5 x 10(6) monocytes per tube with lucigenin. No significant response to fMLP was observed with heterophils. The results indicate that the respiratory burst of chicken monocytes and heterophils can be measured by CL.

Acridines↗
PubMed1996

Cross-protection between Actinobacillus pleuropneumoniae biotypes-serotypes in pigs.

Four groups of hysterectomy-derived and colostrum-deprived pigs were intranasally inoculated with an Actinobacillus pleuropneumoniae biotype 1-serotype 2 strain (producing RTX toxins ApxII and ApxIII. 6 pigs), an A. pleuropneumoniae biotype 1-serotype 10 strain (producing ApxI. 5 pigs), an A. pleuropneumoniae biotype 2-serotype 2 strain (producing ApxII, 5 pigs) or saline (controls, 7 pigs). All pigs were exposed to A. pleuropneumoniae biotype 1-serotype 2 endobronchial challenge. After challenge, severe clinical signs were observed in all control pigs, one pig immunized with the A. pleuropneumoniae biotype 1-serotype 10 strain and two pigs immunized with the A. pleuropneumoniae biotype 2-serotype 2 strain. These pigs died within 36 h after challenge and 20 to 50% of the lungs were macroscopically affected. In the other pigs, clinical signs were mild or absent and no or only small, focal lung lesions were observed when euthanized at 48 h after challenge. At the time challenge neutralizing antibodies against ApxI only. ApxII only and both ApxII and III were present in sera of pigs immunized with the A. pleuropneumoniae biotype 1-serotype 10 strain, the A. pleuropneumoniae biotype 2-serotype 2 strain and the A. pleuropneumoniae biotype 1-serotype 2 strain, respectively. These results indicate that immune mechanisms other than Apx neutralizing antibodies were involved in partial cross-protection of pigs immunized against A. pleuropneumoniae biotype 1-serotype 10 and challenged with the A. pleuropneumoniae biotype 1-serotype 2.

Actinobacillus Infections↗
PubMed1996

Secreted antigens as virulence associated markers in Streptococcus bovis strains from pigeons.

SDS-PAGE and Western blot analysis were performed on the culture supernatant of 7 pigeon S. bovis reference strains belonging to the serotypes 1, 2, 3 and 5. The culture supernatant of highly virulent serotype 1, 2 and 5 strains contained four antigens that were absent in low virulent serotype 3 strains, notably a 185 kDa minor protein band (A) and a triplet (T1) of 70 kDa. The less virulent serotype 3 strains on the other hand contained protein triplets, that had a molecular mass of either 68 kDa (T2) or 74 kDa (T3). The prevalence of A, T1, T2 and T3 was examined in 68 S. bovis strains isolated from healthy pigeons and in 68 S. bovis strains isolated from pigeons that died of S. bovis septicaemia. Six supernatant phenotypes were identified: A-T1 (32 strains), A- T2 (10 strains), A- T3 (7 strains), A+ T1 (84 strains), A+ T2 (1 strain) and A+ T3 (2 strains). Ninety-four percent of the strains lacking the A and T1 proteins were isolated from healthy pigeons, and only 6% were isolated from septicaemia. Strains expressing A and/or T1, however, were isolated form septicaemia in 57% of the cases. These observations may indicate that the A and/or T1 proteins are associated with virulence.

Animals↗
PubMed1996

World Health Organisation--supervised interlaboratory comparison of ELISAs for the serological detection of Salmonella enterica serotype Enteritidis in chickens.

A collaborative exercise, supervised by the World Health Organisation, was set up to compare ELISAs used for the serological detection of Salmonella enteritica serotype Enteritidis in chickens. The aim was to ascertain how far agreement could be reached on the interpretation of optical density readings for high titre, intermediate titre and low titre sera. Two sets of sera were sent to 14 participants. The first set compared high, medium and low titre sera raised in specified-pathogen-free and commercial broiler breeder chickens. The second set comprised 20 sera of different antibody titres raised in commercial birds reared under laboratory conditions and sent blind. Both indirect and double-antibody sandwich blocking ELISAs were used with a number of different detecting antigens. With a few exceptions good agreement was reached on the interpretation of results obtained from high and low titre sera from the optical density obtained with a single serum dilution. Differences were observed in the interpretation of medium titre sera. The results suggested that most ELISAs produce reasonably comparable results and that practical problems may arise from interpretation of the results mainly as a result of the choice of the criteria used for differentiating sera obtained from infected and uninfected chickens. These problems are discussed.

Animals↗
PubMed1996

Klippel-Trenaunay syndrome in a Border collie.

A Border collie was presented at the age of 9 weeks with several lesions of the right forelimb, including a reddish-blue haemangiomatous macula in the medio-dorsal part of the elbow, multiple, scattered small cavernous haemangioma-like lesions at the plantar part of the foot and a general hypertrophy of the limb. X-rays of the limb showed osteolysis. On skin biopsy, telangiectatic veins were observed. The rest of the body did not show any skin lesions or hypertrophy. The dog was otherwise healthy. Due to the extension of the lesions and worsening of the limb swelling, it was decided to amputate the affected limb. The dog remained healthy for 2 weeks, but then passed through episodes of anaemia, and finally died suddenly with signs of shock. Dissection of the limb after amputation revealed hypoplasia and aplasia of the deep venous system in the lower part of the leg. No arterio-venous shunts were noticed. ln man, this syndrome, characterised by an insufficiently developed deep venous system associated with local overgrowth of the limb and cutaneous telangiectasia, is known as Klippel-Trenaunay syndrome.

Journal Article↗
PubMed1996

Pharmacokinetics and bioavailability of doxycycline in turkeys.

The pharmacokinetic parameters of doxycycline (DOX) were determined in 3 day, 3-, 6- and 12-week-old fasted turkeys, after a single intravenous (i.v.) dose of 25 mg doxycycline. HCl/kg body weight. Doxycycline disposition fitted an open two-compartment model. The mean (+/-SD) elimination half-life was 10.6 +/- 0.7, 10.8 +/- 1.5, 7.9 +/- 1.4 and 10.0 +/- 0.9 h in 3 day, 3-, 6- and 12-week-old turkeys, respectively. Mean (+/- SD) total body clearance was 0.19 (+/-0.01), 0.27 (+/-0.03), 0.11 (+/-0.03) and 0.06 (+/-0.01) L/h.kg in 3 day, 3-, 6- and 12-week-old turkeys, respectively. The steady-state volume of distribution was 1.77 (+/-0.2), 2.1 (+/-0.2), 0.7 (+/-0.4) and 0.5 (+/-0.2) L/kg in turkeys of the above mentioned ages, respectively. The AUC value significantly increased with the age of the turkeys. An oral doxycycline solution at a single dose of 25 mg/kg of body weight was administered to 3 day. 3-, 6- and 12-week-old turkeys. The maximal plasma concentrations in fasted turkeys were 3.8, 5.6, 7.4 and 5.7 micrograms/mL. with tmax values of 4.7, 1.5, 2.8 and 5.4 h, for the different ages, respectively. In fed turkeys the Cmax values were 2.5, 6.1, 4.8 and 3.0 micrograms/mL. with tmax values of 4.2, 5.3, 4.5 and 7.5 h, respectively. The absolute bioavailability in fasted turkeys varied between 25.0 +/- 9.0% (for 12-week-old birds) and 63.5 +/- 7.1% (for 3-week-old birds). The relative bioavailability varied between 40.0 +/- 13.0% (for 12-week-old birds) and 83.7 +/- 14.3% (for 3-week-old birds).

Administration, Oral↗
PubMed1996

Ultrastructural changes in avian Chlamydia psittaci serovar A-, B-, and D-infected Buffalo Green Monkey cells.

In order to find an explanation for the observed differences in levels of pathogenicity in turkeys of Chlamydia psittaci 84/55 (avian serovar A), 89/1326 (avian serovar B), 92/1293 (avian serovar D), and the Texas Turkey strain (avian serovar D) (P.B. Wyrick, J. Choong, S.T. Knight, D. Goyeau, E.S. Stuart, and A.B. MacDonald, Immunol. Infect. Dis. 4:131-141, 1994), the reproductive cycles of organisms of the four strains were studied in Buffalo Green Monkey cells by transmission electron microscopy, immunoelectron microscopy, and flow cytometry. Organisms of strains most pathogenic in turkeys, namely, the serovar A strain and the 92/1293 serovar D strain, (i) replicated faster, since at 50 h postinoculation significantly larger inclusions with more numerous infectious organisms were observed than with the less pathogenic strains; (ii) were often found devoid of inclusion membranes scattered throughout the cytoplasms; and (iii) induced severe degenerative changes in Buffalo Green Monkey cells. By immunoelectron microscopy and flow cytometry, chlamydial antigens could not be detected in the plasma membranes of infected host cells. However, the presence of chlamydial antigens in inclusion membranes was demonstrated by immunoelectron microscopy.

Animals↗
PubMed1996

Influence of Actinobacillus pleuropneumoniae and its metabolites on porcine alveolar epithelial cells.

The effect of Actinobacillus pleuropneumoniae and its metabolites on the viability of porcine alveolar epithelial cells was studied by using a neutral-red uptake test. Alveolar epithelial cells were obtained from 5-week-old colostrum-deprived pigs. The purity of these cells as assessed by the modified Papanicolaou stain was 90 to 95%. Incubation of these cells with 10(6) CFU of a biotype 1 serotype 1 strain resulted in death of the alveolar epithelial cells within 1.5 h. A cytotoxic effect was also seen when alveolar epithelial cells were incubated with sterile culture supernatants of biotype 1 serotype 1, biotype 1 serotype 10, and biotype 2 serotype 2 strains or with ApxI, ApxII, or ApxIII produced by recombinant Escherichia coli. Incubation of alveolar epithelial cells with a knockout mutant of the biotype 1 serotype 1 parent strain which is unable to secrete Apx toxins or with its supernatant did not result in death of these cells. These results indicate that cytotoxicity is at least in part due to production of Apx toxins.

Actinobacillus pleuropneumoniae↗
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

Chlamydia psittaci infections: a review with emphasis on avian chlamydiosis.

In the first part of this article the general characteristics of Chlamydia psittaci namely the history, taxonomy, morphology, reproductive cycle, metabolism and genetics are reviewed. For the taxonomy in particular, a considerable amount of new information has become available in recent years, following the application of monoclonal antibodies and restriction enzymes. Using these techniques isolates of Chlamydia psittaci from birds have been subdivided in different serovars, a number of isolates have been classified in a new species (Chlamydia pecorum) and isolates from animals have been classified as Chlamydia trachomatis. In the second part of the article, the current knowledge on avian chlamydiosis is summarized. Emphasis is put on clinical signs, lesions, pathogenesis, epizootiology, immunity, diagnosis, prevention and treatment. Also the public health considerations are reviewed. It is concluded that the diagnosis of avian chlamydiosis is laborious and that there is still a need for more accurate, simple and rapid diagnostic tools, both for antigen and antibody detection in various species of birds.

Animals↗
PubMed1995

Intracellular survival and multiplication of virulent and less virulent strains of Streptococcus bovis in pigeon macrophages.

The intracellular fate of pigeon S. bovis strains ingested by macrophages was studied in vivo and in vitro. During in vivo experiments, histological and electron microscopical examinations demonstrated numerous cocci, which appeared to be actively multiplying, within splenic macrophages of pigeons experimentally inoculated with a highly virulent S. bovis serotype 1 strain. In pigeons inoculated with a low virulence serotype 3 strain, intracellular cocci were only occasionally observed. For in vitro experiments, pigeon peritoneal macrophages were inoculated with a S. bovis serotype 1 or serotype 3 strain and incubated. Following an initial decrease, an increase in the number of intracellular bacteria was observed in tests performed with the S. bovis serotype 1 strain, demonstrating intracellular multiplication. Macrophages in these experiments had all died after 7 h of incubation, possibly indicating that the intracellular replication of S. bovis resulted in the release of substances toxic for macrophages. In experiments performed with the S. bovis serotype 3 strain, the number of intracellular bacteria continuously decreased, reflecting killing of organisms. Significant changes in the number of adhering macrophages in S. bovis serotype 3 inoculated cultures were not observed. These results indicate S. bovis in pigeons is a facultative intracellular bacterium and intracellular multiplication may be involved in virulence.

Ampicillin↗