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Biomedical subjects

A Donn

Publications and source records attributed to A Donn.

At least 19 recordsLinked to original sources
PubMed2006

Deformation of press-fitted metallic resurfacing cups. Part 2: Finite element simulation.

The deformation of metallic acetabular cups employed for metal-on-metal hip resurfacing procedures was considered theoretically using the finite element method in the present study, following on the experimental investigation reported in Part 1. Three representative cups, characterized by the cup wall thickness as thin, intermediate, and thick, were considered. For the intermediate cup, the effects of both the size and the diametral interference on the cup deformation were investigated. Both two-dimensional axisymmetric and three-dimensional finite element models were developed to examine the important parameters during and after the press-fit procedure, and in particular the deformation of the metallic cup. The theoretical prediction of the cup deformation was in reasonable agreement with the corresponding experimental measurement reported in Part 1. The most significant factor influencing the cup deformation was the cup wall thickness. Both the size and the diametral interference were also shown to influence the cup deformation. It is important to ensure that the cup deformation does not significantly affect the clearance designed and optimized for tribological performances of metal-on-metal hip resurfacing prostheses. Furthermore the contact parameters at the cup and bone interface associated with the press fit were also discussed.

Acetabulum↗
PubMed1999

Modifications of receptor concentrations for adrenaline, steroid hormones, prostaglandin F2alpha and gonadotropins in hypophysis and ovary of dairy cows with ovarian cysts.

Receptor concentrations for adrenaline, steroid hormones, PGF2alpha, LH and FSH were measured in the hypophysis and ovary of dairy cows with ovarian cysts and the results were compared with those of healthy animals. Significant modifications were found in all receptor concentrations, either between follicular and luteal structures or between the hypophyseal and ovarian receptorial status. The correlations between catecholaminergic and steroidal systems have already been demonstrated, particularly those existing between beta-adrenoceptors and steroid hormone receptors. Particular attention has been given to the possibility that a derangement in neurogenic inputs may be at the basis of some ovarian pathologies. The results of the present study suggest that the modifications of the ovarian and hypophyseal receptorial status of healthy and affected cows could play an important role in the pathogenesis of ovarian cysts.

Animals↗
PubMed1997

Serological diagnosis of chlamydial abortion in sheep and goats: comparison of the complement fixation test and an enzyme-linked immunosorbent assay employing solubilised proteins as antigen.

A new ELISA for antibodies against chlamydial abortion of ewes which uses detergent solubilised proteins (dsp) of Chlamydia psittaci as antigen (Anderson, I.E., Herring, A.J., Jones, G.E., Low, J.C., Greig, A., 1995. Development and evaluation of an indirect ELISA to detect antibodies to abortion strains of Chlamydia psittaci in sheep sera. Vet. Microbiol., 43, pp. 1-12] was compared with the complement fixation test (CFT) in screening 1000 ovine and caprine sera obtained from selected flocks/herds ('flocks') and submitted to a veterinary diagnostic laboratory. Fifteen of the 17 'flocks' had a history of abortion while the remaining two did not and were classified as 'negative flocks'. Infection with Chlamydia was confirmed during the study period in five 'flocks' using direct immunofluorescence and the modified Ziehl Neelsen stain on pathological material. The dspELISA and CFT identified 37 and 45 positive sera on 158 samples tested from these 'flocks'. Chlamydia antibodies were not detected in one of the two negative flocks, in two other flocks where the cause of abortion was undetermined and in three flocks in which the causes of abortion were diagnosed as Listeriosis and/or Salmonellosis. One of the 'negative flocks' yielded two positive reactors by CFT and five by dspELISA, suggesting infection with a cross-reactive subtype of C. pecorum. Of the five 'flocks' in which a definitive diagnosis from pathological material was not possible, four were positive by both serological tests, suggesting that the abortions were due to Chlamydia. The fifth flock, though negative by dspELISA and marginally positive in two samples by CFT, had experienced confirmed chlamydial abortions in previous lambing seasons, but culling and tetracycline treatment have prevented further abortions in the study period. Overall, the proportions of samples positive by CFT and dspELISA were similar (9.1% and 8.8%). These studies confirmed the value of the dspELISA as a screening test for chlamydial abortion. Furthermore, the dspELISA compared to the CFT is easier to perform, does not require reagent titration at each testing and uses automated assessment of results.

Abortion, Veterinary↗
PubMed1995

Ultrastructural and replicative features of foot-and-mouth disease virus in persistently infected BHK-21 cells.

Persistent foot-and-mouth disease (FMD) virus infection in vitro has been studied in a chronically infected cloned BHK-21 cell line. Virus growth during serial cell passages was followed by infectivity assay and immunocytochemical staining. Only a small percentage of cells (0.006-6%) was found to harbour virus during persistence. Light and electron microscopy showed the presence of cytoplasmic protuberances ("blebs") at the surface of persistently infected cells. The curing of cell cultures was achieved by passaging them in the presence of polyvalent immune serum. The absence of virus in cured cells was confirmed by infectivity assay and immunocytochemistry. This finding, together with the low percentage of infected cells in cultures confirms that persistently infected BHK-21 cells satisfy the definitions of a carrier culture. The characteristics of the in vitro system and its relevance to the study of FMD carrier state in vivo are discussed.

Animals↗
PubMed1995

Detection of foot-and-mouth disease virus-infected cattle by assessment of antibody response in oropharyngeal fluids.

The detection of foot-and-mouth disease virus (FMDV)-persistent carriers among convalescent ruminants is of paramount importance in the aftermath of a field outbreak. To this purpose, FMDV-specific antibody should be investigated first, since virus isolation procedures from such carriers are seriously constrained. The complexity of the overall picture may be compounded by possible emergency vaccinations in the affected areas at the beginning of the outbreak. In this case, it is suggested that mucosal rather than serum antibody be investigated. In fact, we showed that FMDV-infected cattle regularly mount an antibody response in oropharyngeal fluids, in contrast to vaccinated cattle. Antibody could be revealed by neutralization assays and/or an immunoglobulin A (IgA)-specific kinetic enzyme-linked immunosorbent assay (ELISA). Cattle vaccinated once seldom showed a mucosal antibody response, which could be only detected by a total immunoglobulin-specific kinetic ELISA. Very few, if any, cattle showed a mucosal IgA response after repeated vaccinations. Our kinetic, IgA-specific ELISA generally allowed an early detection of FMDV-infected cattle; in particular, it proved to be more sensitive than the usual indirect, antigen-trapping ELISA in experiments on saliva samples.

Animals↗
PubMed1994

Improved detection of persistent foot-and-mouth disease infection in cattle by the polymerase chain reaction.

Persistent foot-and-mouth disease (FMD) infection of cattle was established by exposure to infected pigs. Oesophageal-pharyngeal fluid samples collected ante-mortem and tissue samples obtained post-mortem were tested for virus by conventional means and for viral RNA by the polymerase chain reaction (PCR). The results showed that the PCR was superior for detecting the carrier state in tissue samples. A high neutralising activity in tissues probably influenced the yields of virus obtained by infectivity assay.

Animals↗
PubMed1992

Preparation and use of a monoclonal antibody to detect Chlamydia psittaci antigen in paraffin-embedded tissue sections.

A murine monoclonal antibody prepared against an ovine abortion isolate of Chlamydia psittaci (A22/Teramo) revealed specific binding to a 57 kDa chlamydial antigen in immunoblotting studies. The monoclonal antibody was able to detect intracytoplasmic chlamydial inclusions and scattered elementary bodies in infected McCoy cell culture, and on formalin-fixed paraffin-embedded tissue sections both from experimentally infected mice and from fetal membranes of cases of ovine enzootic abortion.

Animals↗
PubMed1992

Multiple myeloma presenting as vortex crystalline keratopathy and complicated by endocapsular hematoma.

The crystalline keratopathy of multiple myeloma may involve the corneal epithelium, but has not previously been described in a vortex epithelial distribution. Endocapsular hematomas have been described in the period immediately after extracapsular cataract extraction, but not later on or in association with systemic disease. We report a pseudophakic patient who developed a vortex epithelial crystalline keratopathy as a presenting sign of multiple myeloma, and who subsequently developed a spontaneous endocapsular hematoma.

Aged↗
PubMed1991

The use of fluorescein-conjugated monoclonal antibodies, cell culture and transmission electron microscopy to detect Chlamydia psittaci and associated lesions in experimentally infected mice.

An immunofluorescence test based on a monoclonal antibody (mAb) was used to demonstrate chlamydiae in formalin-fixed and paraffin wax-embedded tissues from 10 adult mice experimentally infected by the oral route with Chlamydia psittaci isolated from the fetal membranes of an aborted ovine fetus. Samples of lung, jejunum and spleen were examined by bright-field microscopy, immunofluorescence and transmission electron microscopy, and were cultured for chlamydia in McCoy cells. These tissues were compared with those of two control mice. All infected mice had splenic hyperplasia and two had pneumonia. The lung appeared to be the target organ for C. psittaci administered by the oral route. Chlamydiae were identified in the lungs of five mice by immunofluorescence, bright-field and transmission electron microscopy. Chlamydiae were cultured from the jejunum of two mice and the spleen of one, but could not be identified at these sites by other methods. Immunofluorescence with an anti-chlamydia mAb was useful for detecting chlamydial antigen in formalin-fixed paraffin wax-embedded samples.

Animals↗
PubMed1990

In vivo measurement of posterior chamber intraocular lens decentration and tilt.

We report what to our knowledge is the first extensive in vivo clinical study of intraocular lens decentration and tilt. Measurements of posterior chamber intraocular lenses, all implanted by the same surgeon in 89 eyes, showed that decentration and tilt consistently differed between right and left eyes. Lenses tended to decenter superotemporally and tilt with their superonasal edges tipped forward. Decentration magnitude relative to the cornea light reflex axis and line of sight averaged 0.64 mm, with decentration increasing slightly with increased axial length. Average tilt was 6.75 degrees, and the average tilt-induced astigmatism was 0.27 diopter. Tilt magnitude decreased with increased axial length, as did tilt-induced astigmatism and plus sphere.

Adult↗
PubMed1980

Wide field specular microscopy. Clinical and research applications.

Through the use of a scanning mirror system, the field of view has been expanded to as much as 0.9 mm in diameter. Both contact and non-contact specular microscopy are possible, each having advantages. In a research application, wound healing in rabbit endothelium is documented by time lapse photography. The study demonstrates the capability to return to an area of interest provided there is a landmark. Clinical applications and advantages over conventional specular microscopy are discussed.

Animals↗
PubMed1976

Aphakic bullous keratopathy treated with prosthokeratoplasty. An analysis of 34 consecutive cases.

Thirty-four eyes with advanced aphakic bullous keratopathy were treated with the Cardona keratoprosthesis as a primary procedure. There were three extrusions (9%), two of which were associated with infections; two other conditions were worsened (6%) as a result of a late permanent vitreous hemorrhage or possibly an infection. Twenty-eight eyes (82%) showed a notable improvement during follow-up periods that ranged from 6 to 72 months. The advantages and limitations of this technique are compared to those of penetrating keratoplasty.

Aged↗
PubMed1975

Ultrastructural variation in granular dystrophy of the cornea.

Corneal deposits of granular dystrophy were studies in six corneas from five patients. Two additional corneas from two patients with lattice dystrophy were used for comparison. The diagnoses were confirmed by light and electron microscopy. Three types of ultrastructural features were distinguished in the electron-dense rod-shaped deposits of granular dystrophy, i.e., Type 1 with homogenous structure, Type 2 with fibrillar constituents, and Type 3 with a moth-eaten or sponge-like appearance. In polarization microscopy of Congo-red stained sections, the Type 2 tended to show an increased birefringence without green dichroism, while the other types were less birefringent than the stroma. Three different components were found immediately around the deposits, i.e., 1. normal collagen fibrils, 2. finely filamentous substance, and 3. areas of thin fibrils (70-100 A in diameter). While the second component appeared non-specific, the third component was found only in two corneas, superimposed on the lesions of granular dystrophy, and showed light and electron microscopic characteristics of the lesions of amyloid as well as of lattice dystrophy.

Aged↗