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Biomedical subjects

J R Duncan

Publications and source records attributed to J R Duncan.

At least 73 records · Page 4Linked to original sources
PubMed1988

Malignant fibrous histiocytoma in a cat.

A malignant histiocytoma of the carpus and distal portion of the right antebrachium of a cat was treated by forelimb amputation. The tumor remained in remission 35 months after surgery. The response to treatment in this cat and similar findings reported by others suggest that the biological behavior of malignant fibrous histiocytoma is such that prolonged remission, if not cure of the disease, can be achieved with early radical excision of the tumor.

Animals↗
PubMed1988

Further evidence that bovine IgM does not fix guinea pig complement.

In a study of sera from cattle vaccinated with 3 X 10(10) cfu of Brucella abortus strain 19, it was found that IgG1 antibody measured by an indirect ELISA was the only isotype to correlate with standard complement fixing antibody titers using heated serum samples and guinea pig serum as a source of complement. A supplement of normal unheated bovine serum resulted in IgM fixing guinea pig complement, giving data similar to those obtained with unheated serum in the complement fixation test.

Animals↗
PubMed1988

Antibody isotype response in adult cattle vaccinated with Brucella abortus S19.

In a chronological study of sera collected from eight adult cattle vaccinated with 3 X 10(-10) cfu of Brucella abortus S19, antibody of each of the four major isotypes was measured by indirect enzyme immunoassay (ELISA) and by direct and modified complement fixation tests (CFT). Six of the cattle gave antibody responses to the vaccine strain that commenced between days 5 and 8 for all the isotypes in the ELISA, peaked by 1 to 4 months and then declined to low levels by 10 months. Direct CFT and modified CFT titers were measurable by 7 or 8 days post-vaccination, and peaked by 1 month; direct CFT titers disappeared by 5 months while the modified CFT titers lingered for 10 months. Two animals gave cyclical direct CFT and modified CFT antibody responses, a cyclical IgG1 response, a low IgG2 and an elevated IgA response. The amplitude of the cycles was uniform over three cycles while the wavelength increased with time. A year post-vaccination, B. abortus S19 was isolated twice from milk from one of the animals (no attempt was made to culture B. abortus from the other). Sera from B. abortus naturally infected cattle were analysed for comparison.

Animals↗
PubMed1988

Enhanced prostaglandin synthesis as a mechanism for inhibition of melanoma cell growth by ascorbic acid.

Both ascorbic acid and the 1-series prostaglandins have been reported to be important regulators of cell growth and since ascorbic acid also increases the synthesis of the 1-series prostaglandins, it is possible that the effects of ascorbic acid on cell growth might be mediated by changes in 1-series prostaglandin synthesis induced by ascorbic acid. This study attempted to examine this possible relationship. The effects of ascorbic acid, prostaglandin E1 and the essential fatty acid precursors of the prostaglandins, linoleic acid and gamma-linolenic acid on the in vitro growth of transformed BL6 murine melanoma cells and untransformed monkey kidney (LLCMK) cells was determined. The effects of ascorbic acid addition on the growth inhibitory effect of the essential fatty acids and on the activity of delta-6-desaturase, a key enzyme in 1-series prostaglandin synthesis were also examined. Addition of ascorbic acid, prostaglandin E1 and both essential fatty acids was found to reduce BL6 growth while PGE1 and to a lesser extent the essential fatty acids reduced LLCMK cell growth. The growth inhibitory effect of the essential fatty acids was enhanced by ascorbic acid which was also found to stimulate delta-6-desaturase activity in BL6 cells. The growth inhibitory effect of ascorbic acid on BL6 cells may thus be mediated by changes in prostaglandin synthesis through an association with the metabolism of the essential fatty acid precursors of the prostaglandins.

Animals↗
PubMed1988

A possible relation between dietary zinc and cAMP in the regulation of tumour cell proliferation in the rat.

1. The possibility of an effect of zinc on the rate of tumour cell division, mediated through a regulation of cellular cAMP concentration, was investigated in the present study in rats. 2. Dietary Zn deficiency (less than 1.5 mg Zn/kg) but not Zn excess (500 mg Zn/kg) resulted in an increased cAMP concentration in transplanted hepatoma cells. Neither treatment had any effect on the cAMP concentration in regenerating liver or normal resting liver. Both the deficient and excess Zn diets resulted in a small reduction in tumour growth (not statistically significant). 3. The results seem to indicate that the relation investigated in the present study does not apply in the cell line used.

Animals↗
PubMed1988

Intracellular movement of two mannose 6-phosphate receptors: return to the Golgi apparatus.

We have used Chinese hamster ovary (CHO) cells and a murine lymphoma cell line to study the recycling of the 215-kD and the 46-kD mannose 6-phosphate receptors to various regions of the Golgi to determine the site where the receptors first encounter newly synthesized lysosomal enzymes. For assessing return to the trans-most Golgi compartments containing sialyltransferase (trans-cisternae and trans-Golgi network), the oligosaccharides of receptor molecules on the cell surface were labeled with [3H]galactose at 4 degrees C. Upon warming to 37 degrees C, the [3H]galactose residues on both receptors were substituted with sialic acid with a t1/2 approximately 3 hrs. Other glycoproteins acquired sialic acid at least 8-10 times slower. Return of the receptors to the trans-Golgi cisternae containing galactosyltransferase could not be detected. Return to the cis/middle Golgi cisternae containing alpha-mannosidase I was measured by adding deoxymannojirimycin, a mannosidase I inhibitor, during the initial posttranslational passage of [3H]mannose-labeled glycoproteins through the Golgi, thereby preserving oligosaccharides which would be substrates for alpha-mannosidase I. After removal of the inhibitor, return to the early Golgi with subsequent passage through the Golgi complex was measured by determining the conversion of the oligosaccharides from high mannose to complex-type units. This conversion was very slow for the receptors and other glycoproteins (t1/2 approximately 20 h). Exposure of the receptors and other glycoproteins to the dMM-sensitive alpha-mannosidase without movement through the Golgi apparatus was determined by measuring the loss of mannose residues from these proteins. This loss was also slow. These results indicate that both Man-6-P receptors routinely return to the Golgi compartment which contains sialyltransferase and recycle through other regions of the Golgi region less frequently. We infer that the trans-Golgi network is the major site for lysosomal enzyme sorting in CHO and murine lymphoma cells.

Animals↗
PubMed1988

Effectiveness of natural and synthetic complexes of porin and O polysaccharide as vaccines against Brucella abortus in mice.

A single vaccination of mice with a complex of porin and smooth lipopolysaccharide (porin-S-LPS) extracted from virulent Brucella abortus 2308 provided significant protection (P less than 0.01 to P less than 0.001) against challenge with the same strain, equivalent to that achieved by vaccination with living attenuated B. abortus 19. The porin-S-LPS vaccine given without adjuvant or in several adjuvants (trehalose dimycolate and muramyl dipeptide; the pluronic polymer L-121 and muramyl dipeptide; or complexed with Quil A in immunostimulating complexes) provided equivalent protection. In contrast, one vaccination with porin complexed with rough LPS (porin-R-LPS) from a rough mutant of strain 2308 provided no protection with any adjuvant tested. In one experiment, two inoculations with the porin-R-LPS resulted in a low level of protection, probably owing to priming of the animals for production of O-polysaccharide-specific antibodies. However, one vaccination with rough-strain porin covalently bound to purified O polysaccharide conferred protection equal to that obtained with natural complexes of porin-S-LPS or with living strain 19. A synthetic vaccine containing long chains of O polysaccharide was more effective than one prepared with short chains. Protective vaccines caused the formation of increased concentrations of circulating O-polysaccharide-specific antibodies, although there were individual exceptions to the quantitative association between O-polysaccharide-specific antibodies and protection. Antibodies specific for porin or R-LPS were found in negligible quantities in vaccinated mice. These results provide additional evidence that the O polysaccharide will constitute an essential component of an effective subcellular vaccine against B. abortus and that O-polysaccharide-specific antibodies play an important role in protective immunity in brucellosis.

Adjuvants, Immunologic↗
PubMed1988

Intermediate filament staining in the cytologic and histologic diagnosis of canine skin and soft tissue tumors.

Formalin-fixed histologic and acetone-fixed cytologic preparations from 87 surgically removed subcutaneous and soft tissue canine tumors were examined for immunoreactivity to cytokeratin, desmin, and vimentin. The avidin-biotin complex (ABC) technique demonstrated immunoreactivity in both preparations, but the intensity and specificity of the reactions were dependent on the primary antibody. Polyclonal antibodies to cytokeratin were more consistent in immunoreactivity than were polyclonal desmin or vimentin antibodies. The monoclonal antibody proved more satisfactory for demonstrating vimentin than the polyclonal antibody. Greater dilutions of primary antibodies may be used on cytologic preparations than on histologic sections. Evaluation of cytologic preparations may be inconclusive due to background staining, scant cellularity, or poor cytoplasmic preservation.

Animals↗
PubMed1988

Evaluation of the serological response of sheep in one flock to Mycobacterium paratuberculosis by crossed immunoelectrophoresis.

Sera from 74 sheep culled from one flock on the basis of performance and response to immunological tests for paratuberculosis or maedi visna were used to evaluate the serological response to a sonicated antigen of Mycobacterium paratuberculosis by crossed immunoelectrophoresis. A total of seven precipitating components was demonstrated. Four components (A,C,V,W) were detected in low frequency only with sera from animals with paratuberculosis while two components (X,Y) were detected in high frequency with sera from animals with or without paratuberculosis. One component (D) was observed in high frequency with sera from animals with paratuberculosis. The magnitude of the serological response to the D component as measured by crossed immunoelectrophoresis correlated well with bacterial load and generally agreed with the quantitative assessment by agar gel immunodiffusion. A development time for crossed immunoelectrophoresis of 24-72 hours after electrophoresis was required to achieve correlation with agar gel immunodiffusion.

Animals↗
PubMed1987

Improved isolation of rat microsomal cytochrome b5 reductase.

Cytochrome b5 reductase (E.C. 1.6.2.2.) has been isolated using a modification of the methods of Takesue and Omura [J. Biochem., 67 (1970) 267], Mihara and Sato [J. Biochem., 71 (1972) 725; and J. Biochem., 78 (1975) 1057]. The methodology involves the isolation of cytochrome b5 reductase from rat liver microsomes using the techniques of lysosomal solubilisation, ammonium sulphate fractionation, gel chromatography and dialysis. This modified method results in a greatly increased yield of enzyme. The purity of the isolated enzyme is shown by disc gel electrophoresis.

Ammonium Sulfate↗
PubMed1987

Basophilic leukaemia in a dog.

Leukaemia in an 11-year-old bitch was characterized by the presence in the peripheral blood and bone marrow of cells with lobulated nuclei and numerous metachromatic cytoplasmic granules. The results of cytochemical stains for peroxidase and naphthol AS-D chloracetate esterase activity were negative. Ultrastructurally, the cytoplasmic granules were finely granular with no membranous coils or crystalline lattice structures. Based on these findings, the neoplastic cells were classified as basophils.

Animals↗
PubMed1987

Nuclear segmentation, ultrastructure, and cytochemistry of blood cells from dogs with Pelger-Huët anomaly.

Nuclear segmentation, ultrastructural features and cytochemical staining reactions of blood cells from 7 dogs with the heterozygous form of Pelger-Huët (P-H) anomaly were investigated. Significant nuclear hyposegmentation of granulocytes, monocytes and megakaryocytes was found, indicating a common stem cell defect in the nuclear segmentation or lobulation process. Neutrophils and eosinophils from female P-H dogs lacked sex chromatin drumsticks. Other than the suggestion of nuclear hyposegmentation and the presence of coarse heterochromatin, no ultrastructural abnormalities were discerned. Cytochemical staining by a-naphthyl acetate esterase, alkaline phosphatase, naphthol ASD chloroacetate esterase, periodic acid-Schiff, peroxidase and Sudan black B techniques gave similar results for P-H and control dog leukocytes and platelets.

Animals↗
PubMed1987

Bovine IgM: does it fix guinea pig complement in the absence of bovine complement components?

Purified bovine isotypes IgM, IgG1, IgG2, and IgA (secretory), affinity purified with Brucella abortus, were tested in a complement fixation test (CFT) for their ability to activate guinea pig complement directly or in the presence of 'normal' bovine serum. Only IgG1 fixed guinea pig complement in the direct test and approximately 250 ng of antibody was required to activate 50% of 3 CH50 units with a standard amount of antigen. Addition of 'normal' bovine serum as an additional source of complement resulted in activation of guinea pig complement by IgM, IgG2 and secretory IgA at levels of approximately 1200, 700 and 2250 ng, respectively for 50% of 3 CH50 units. Addition of 'normal' bovine serum did not enhance complement activation by bovine IgG1.

Animals↗
PubMed1987

Lipoarabinomannan and lipid-free arabinomannan antigens of Mycobacterium paratuberculosis.

Lipoarabinomannan (LAM) and lipid-free arabinomannan (AM) were prepared from Mycobacterium paratuberculosis. Purification of LAM was done by ultracentrifugation of the phenol-water-extracted crude polysaccharide, followed by affinity and anion exchange chromatography. AM was purified from the supernatant of the ultracentrifuged polysaccharide or from alkaline-extracted material by gel filtration and anion exchange chromatography. Chemical analysis revealed arabinose and mannose in LAM (1.4:1) and AM (3.5:1) and the presence of palmitic, stearic, and tuberculostearic acids for a total of 7.8% lipid in LAM. Traces of phosphorus were found in the AMs, particularly LAM (0.05%). Nuclear magnetic resonance confirmed the presence of alpha-arabinosyl residues and the acylated nature of LAM. LAM exhibited lipid-dependent aggregation, as indicated by a Triton-induced decrease in molecular weight. By using bovine sera, LAM was found to be active in the complement fixation test, whereas AM was inactive and inhibited this activity. Thus, the presence of AM in crude polysaccharide could explain the variable complement fixation results. Triton-dissociated LAM exhibited a precipitin (Cl) in common with that of AM, confirming shared determinants. LAM in its lipid-dependent aggregated form, however, exhibited a second precipitin (C2), which may be due to the disparity in antigen size or a novel epitope. The lipid content of LAM rendered it 100 times more effective for coating plates in the enzyme immunoassay than lipid-free AM.

Antibodies, Bacterial↗
PubMed1986

Food hypersensitivity in a cat.

Food hypersensitivity was diagnosed in a 4-year-old Siamese cat. Clinical signs included intense erythema, with alopecia, excoriations, erosions, and crusts involving the ventral portion of the abdomen, inguinal region, medial aspect of each thigh, and cranial and lateral aspects of all 4 limbs. The cat was intensely pruritic. Histologically, there was cutaneous mast cell hyperplasia and diffuse infiltration of eosinophils in the dermis. Blood eosinophilia also was found. Clinical signs resolved after exclusive feeding of a hypoallergenic diet.

Animals↗
PubMed1986

Hematologic values in calves infected with Sarcocystis cruzi.

Calves were inoculated with 2 X 10(5) Sarcocystis cruzi sporocysts. Red cell mass decreased dramatically between Days 21 and 35 post-infection and plasma volume increased concurrently, so that blood volume did not change significantly. Mild reticulocytosis and increased pyrimidine 5' nucleotidase activity in erythrocytes occurred between Days 35 and 42. Antiglobulin tests with anti-bovine IgG, IgM and C3 were negative, with the exception of a positive test for C3 in 1 of 6 infected calves.

5'-Nucleotidase↗
PubMed1986

Alloantibody-induced platelet serotonin release is blocked by antibody to the platelet PLA1 antigen.

Anti-platelet antibodies are known to activate the platelet release mechanism, usually measured by [14C]serotonin secretion. We have made immunoglobulin preparations of antibodies to HLA antigens, blood group A and platelet-specific PlA1 antigen on the platelet surface and have defined the optimal conditions for [14C]serotonin secretion by washed platelets. For optimal [14C]serotonin release, platelets were washed in apyrase and suspended in Tyrode-albumin with Ca++ and Mg++ and fibrinogen. Anti-PlA1 at high concentration did not cause [14C]serotonin release and inhibited serotonin release by other alloantibodies to antigens on the platelet surface. This was shown to be a result of the inhibition of fibrinogen binding to the platelet by bound anti-PlA1.

ABO Blood-Group System↗