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Biomedical subjects

P Mellor

Publications and source records attributed to P Mellor.

At least 19 recordsLinked to original sources
PubMed2006

Equine insect bite hypersensitivity: immunoblot analysis of IgE and IgG subclass responses to Culicoides nubeculosus salivary gland extract.

Insect bite hypersensitivity (IBH) is an allergic dermatitis of horses caused by IgE-mediated reactions to bites of Culicoides and sometimes Simulium spp. The allergens causing IBH are probably salivary gland proteins from these insects, but they have not yet been identified. The aim of our study was to identify the number and molecular weight of salivary gland extract (SGE) proteins derived from Culicoides nubeculosus which are able to bind IgE antibodies (ab) from the sera of IBH-affected horses. Additionally, we sought to investigate the IgG subclass (IgGa, IgGb and IgGT) reactivity to these proteins. Individual IgE and IgG subclass responses to proteins of C. nubeculosus SGE were evaluated by immunoblot in 42 IBH-affected and 26 healthy horses belonging to different groups (Icelandic horses born in Iceland, Icelandic horses and horses from different breeds born in mainland Europe). Additionally, the specific antibody response was studied before exposure to bites of Culicoides spp. and over a period of 3 years in a cohort of 10 Icelandic horses born in Iceland and imported to Switzerland. Ten IgE-binding protein bands with approximate molecular weights of 75, 66, 52, 48, 47, 32, 22/21, 19, 15, 13/12 kDa were found in the SGE. Five of these bands bound IgE from 50% or more of the horse sera. Thirty-nine of the 42 IBH-affected horses but only 2 of the 26 healthy horses showed IgE-binding to the SGE (p<0.000001). Similarly, more IBH-affected than healthy horses had IgGa ab binding to the Culicoides SGE (19/22 and 9/22, respectively, p<0.01). Sera of IBH-affected horses contained IgE, IgGa and IgGT but not IgGb ab against significantly more protein bands than the sera of the healthy horses. The cohort of 10 Icelandic horses confirmed these results and showed that Culicoides SGE specific IgE correlates with onset of IBH. IBH-affected horses that were born in Iceland had IgGa and IgGT ab (p< or =0.01) as well as IgE ab (p=0.06) against a significantly higher number of SGE proteins than IBH-affected horses born in mainland Europe. The present study shows that Culicoides SGE contains at least 10 potential allergens for IBH and that IBH-affected horses show a large variety of IgE-binding patterns in immunoblots. These findings are important for the future development of a specific immunotherapy with recombinant salivary gland allergens.

Animals↗
PubMed2006

Histiocytic sarcoma of the spleen in flat-coated retrievers with regenerative anaemia and hypoproteinaemia.

Three flat-coated retrievers with a regenerative anaemia were examined. They were hypoproteinaemic suggesting that the anaemia might be due to blood loss, but it was not possible to identify a site of haemorrhage. All three had splenomegaly with splenic abnormalities apparent on ultrasonography. Ultimately all three animals were shown to have a histiocytic sarcoma involving the spleen and other tissues. A fourth flat-coated retriever with anaemia, hypoproteinaemia and an abdominal mass was also diagnosed with a histiocytic sarcoma of the spleen following splenectomy. It is postulated that the dogs' anaemia was due to erythrophagocytosis, either directly by neoplastic cells or by reactive macrophages.

Anemia↗
PubMed2006

Hypercalcaemia associated with granulomatous lymphadenitis and elevated 1,25 dihydroxyvitamin D concentration in a dog.

A seven-year-old Labrador was presented with weight loss and mild generalised lymphadenopathy. Histopathology of an excised lymph node by the referring veterinarian demonstrated granulomatous lymphadenitis. At the time of referral, fine-needle aspirates of the lymph nodes confirmed the presence of ongoing granulomatous inflammation. Further investigations revealed marked hypercalcaemia, a low parathyroid hormone concentration, a parathyroid hormone related protein concentration within the reference range, and an elevated serum concentration of 1,25 dihydroxyvitamin D. An underlying cause of the granulomatous lymphadenitis could not be identified. The clinical signs, hypercalcaemia and elevated serum concentrations of 1,25 dihydroxyvitamin D resolved following prednisolone treatment. In contrast to dogs, hypercalcaemia occurred secondarily to granulomatous disease and elevated 1,25 dihydroxyvitamin D concentrations is a well-recognised condition in human beings. To the authors' knowledge, this is the first case report to describe elevated serum calcium and 1,25 dihydroxyvitamin D concentrations in a dog with histologically confirmed granulomatous disease.

Animals↗
PubMed2006

Evaluation of an in vitro sulphidoleukotriene release test for diagnosis of insect bite hypersensitivity in horses.

REASONS FOR PERFORMING STUDY: Insect bite hypersensitivity (IBH) is an IgE-mediated allergic dermatitis caused by bites of Culicoides and Simulium species, and improved means of diagnosis are required. OBJECTIVES: The cellular antigen simulation test (CAST) with C. nubeculosus and S. vittatum extracts was assessed in a population of IBH-affected and healthy horses. Variations in test results over a one year period and possible cross-reactivity between different insect extracts was studied. METHODS: A total of 314 mature horses were studied using the CAST. Influence of severity of clinical signs, gender and age were evaluated, and 32 horses were tested repeatedly over one year. The kappa reliability test was used to assess agreement of the test results with different insect extracts. RESULTS: Horses with IBH had significantly higher sLT release than controls with C. nubeculosus and S. vittatum. The highest diagnostic sensitivity and specificity levels were attained when using adult C. nubeculosus extracts with the CAST (78% and 97%, respectively), suggesting that most horses with IBH are sensitised against Culicoides allergens. A proportion of IBH-affected horses was found to be sensitised to allergens of Simulium spp. in addition to those of C. nubeculosus. The CAST with C. nubeculosus had positive and negative predictive values > or = 80% for a true prevalence of IBH of 12-52%. In the follow-up study, the proportion of IBH-affected horses with a positive test result ranged from 90% in November to 68% in March. Severity of clinical signs or age did not influence test results significantly. However, IBH-affected males achieved significantly more positive test results than IBH-affected females. CONCLUSIONS: The CAST with adult C. nubeculosus has high specificity and good sensitivity for diagnosis of IBH. Horses with IBH are mainly sensitised to Culicoides allergens, and some horses are additionally also sensitised to allergens in Simulium spp. POTENTIAL RELEVANCE: The CAST is likely to be a useful test for diagnosis of IBH, even allowing the identification of IBH-affected but asymptomatic horses. This test may also help in further characterisation of allergens involved in this condition.

Animals↗
PubMed1996

Expression of the major core structural protein (VP7) of bluetongue virus, by a recombinant capripox virus, provides partial protection of sheep against a virulent heterotypic bluetongue virus challenge.

A recombinant capripox virus was constructed containing a cDNA copy of genome segment 7 of bluetongue virus (BTV) serotype 1 from South Africa (BTV 1SA), which expressed high levels of the major BTV core protein VP7 in infected lamb testis (LT) cells. Sheep vaccinated with this recombinant virus developed antibodies to VP7 (detected by ELISA) but no neutralizing antibodies to either the homologous or heterologous BTV serotype, prior to challenge (BTV 1 or BTV 3, respectively). Following challenge with a virulent heterotypic strain of BTV (BTV3 SA), all of the animals developed clinical signs of disease, indicating that they were infected and that the challenge virus did replicate. While all of the control animals died, six of the eight animals that were vaccinated with the recombinant capripox virus expressing VP7 recovered fully. This is the first report of a significant level of cross serotype protection against the lethal effects of a challenge with virulent BTV, produced by vaccination with a single BTV core protein, which did not generate a neutralizing antibody response.

Animals↗
PubMed1993

Contamination of genetically engineered CHO-cells by epizootic haemorrhagic disease virus (EHDV).

The characterization of a contaminating virus which was detected in genetically-engineered Chinese hamster ovary (CHO) cells during the production of biologicals is described in the present paper. Under electron microscopy, the contaminating virus had a morphology resembling that of an orbivirus. The relationship was confirmed by nucleic acid analysis which showed a RNA segment pattern characteristic of orbiviruses. With an immunoperoxidase staining of monolayer cells and through sero-neutralization tests the virus was identified as being identical to Epizootic Haemorrhagic Disease Virus (EHDV), isolate 318 (untyped) from Bahrain. Potential sources of the contaminating virus and feasible procedures to avoid adventitous virus infections in cell cultures are discussed.

Animals↗
PubMed1985

Further data on the distribution of biting midges in southern Europe and the Mediterranean area, with special reference to Culicoides imicola.

Studies on the Culicoides midges of Spain and Turkey suggest that the range of C. imicola may extend to about 40 degrees N. However, catches of midges from mainland Greece, Sicily and Italy failed to reveal the presence of this species. These findings are discussed in the light of the possibility of the occurrence of bluetongue (BT) disease in these areas, consequent upon windborne spread of infected vectors from countries where the disease is endemic.

Animals↗
PubMed1985

Oral infection of Culicoides (Diptera, Ceratopogonidae) with viral agents, using fine glass needles.

Oral infection of haematophagous insects with arboviruses to test their vector competence can be a difficult procedure in the laboratory since "wild caught" insects often prove reluctant to feed, once captured. This paper describes a technique using virus-charged glass needles to infect Culicoides spp. orally with bluetongue virus (BTV). C. variipennis, a known vector of BTV, was found to support virus multiplication with this technique, giving results comparable to those obtained using standard oral infection procedures. Other species of Culicoides that had previously been difficult or impossible to infect orally in the laboratory also engorged upon virus suspensions. The technique provides a means of assessing the vector competence of these and other similar Culicoides species.

Administration, Oral↗
PubMed1979

Home treatment in haemophilia: clinical, social and economic advantages.

Twenty-eight severely affected haemophiliacs were observed for 3 months under treatment as hospital out-patients and for the subsequent 9 months while treating themselves at home. Delay in receiving treatment and financial costs were both clearly reduced by home treatment, the patients recovered from individual bleeds more quickly and reported a greater sense of personal freedom and independence. The amount of treatment required did not materially change and no untoward effects were noted; the use of analgesics tended to be less.

Adolescent↗