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Biomedical subjects

D A Higgins

Publications and source records attributed to D A Higgins.

At least 55 records · Page 3Linked to original sources
PubMed1984

A comparison of the antibody responses of badgers (Meles meles) and rabbits (Oryctolagus cuniculus) to some common antigens.

The primary and secondary antibody responses of rabbits and badgers were compared after intravenous inoculation of inactivated influenza A virus, sheep erythrocytes (SRBCs), bovine serum albumin (BSA) or bacteriophage psi X174. BSA was also given as a primary injection by the intramuscular route in solution or in Freund's incomplete or complete adjuvant, followed by an intravenous secondary inoculation without adjuvant. Antibody responses were monitored by: haemagglutination inhibition and neutralization tests for influenza virus; direct and antiglobulin haemagglutination tests for SRBCs; indirect haemagglutination test and the Farr method for antigen-binding capacity (ABC) for BSA; neutralization of psi X174. Rabbits gave good responses to all antigens, but the response of badgers was generally poor. After intravenous administration, badgers gave a good response only to psi X174, but even then they produced less antibody than rabbits receiving 100 times less antigen; the immune elimination of phage was more rapid and antibody appeared about 48 h earlier in rabbits than in badgers. Intramuscular administration of BSA and the use of adjuvants improved the badgers' response, with greatest improvement in ABC. These results indicate that badgers display relatively poor immune responses to a variety of antigens.

Animals↗
PubMed1983

Lymphocyte markers in the bovine foetus.

The ontogeny of lymphocyte surface markers was studied in thymus, retropharyngeal lymph nodes, spleen, bone marrow, and liver of 48 bovine foetuses, 80-280 days of gestation. The markers examined were the spontaneous (E) rosette against sheep erythrocytes (SRBCs) in foetal calf serum (E/FCS), in medium supplemented with gelatin (E/CFG), and in medium supplemented with dextran (E/dextran), the erythrocyte-antibody (EA) rosette for immunoglobulin (Fc) receptors, the erythrocyte-antibody-complement (EAC) rosette for complement receptors, and the immunofluorescence test (IFT) for surface-membrane immunoglobulins (SmIg). E-rosette-forming cells (RFCs) occurred in the thymus in substantial numbers throughout the period studied, in spleen and lymph nodes only after 160 days, and in bone marrow and liver rarely. The dynamics of E rosettes formed in the three supplements suggested that each supplement might be supporting rosette formation by different populations of cells, albeit considerable overlap might be expected. Organ distribution and development of EA and EAC RFCs did not parallel the expected ontogeny of any class of lymphocytes. Cells carrying SmIg developed mainly in spleen and lymph nodes. Towards the end of gestation some cells in liver also had SmIg.

Animals↗
PubMed1981

Correlation between enhanced E-rosette formation and spontaneous incorporation of thymidine by bovine thymus lymphocytes.

Bovine thymus lymphocytes were centrifuged at low speed through 27% BSA and separated into five equal fractions. Enhanced formation of E rosettes and 10-20 fold increases in spontaneous uptake of tritiated (3H) thymidine occurred among the buoyant cell populations with less or no increases among cells from lower fractions. It is suggested that BSA stimulates blastogenesis and that the increases capacity for E-rosette formation is due to cell surface alterations among the activated cells or cells affected by their products.

Animals↗
PubMed1977

Bovine lymphocytes: enhanced E-rosette formation after storage or gradient centrifugation.

Incubation of bovine thymus lymphocytes with SRBCs for 1 hr or more at 0 degrees C during the E-rosette test gave higher rosette counts than tests receiving no such incubation. Further enhancement was seen if lymphocytes were stored in foetal calf serum (FCS) or BSA solutions at 4 degrees C for 18 hr prior to rosette tests. Best enhancement due to storage in BSA was seen when cells were subsequently tested in FCS. However, after storage in BSA many rosettes occurred when tests were done in BSA, Albeit few rosettes occurred in BSA without prior storage. Less enhancement was seen after storage in sodium metrizoate (NaM). Enhancement in FCS and 10% BSA occurred after 1 day, but not 2 or more days, of storage at 4 degrees C, but was not seen when cells were stored at 37 degrees C. Rosette formation was about doubled by centrifugation of lymphocytes through BSA gradients prior to rosette tests; centrifugation through NaM gradients had no such effect. It is suggested that rosette formation is a property of an immature bovine T cell, and that on storage some cells develop and subsequently lose the ability to form rosettes.

Animals↗
PubMed1977

Bovine lymphocytes: recognition of cells forming spontaneous (E) rosettes.

About 20% of thymus lymphocytes from neonatal calves formed spontaneous (E) rosettes with SRBCs in medium consisting of 50-100% foetal calf serum (FCS); other media were less satisfactory. FCS was necessary both to allow rosette formation to occur and to maintain stability of the rosettes once formed. Rosettes were stable at 0 degrees C but unstable at 18 degrees C and 37 degrees C. Dead thymus cell (sodium azide treated) did not form rosettes. Treatment of thymus cells with antiserum to bovine Ig-inhibited rosette formation, but this inhibition was considered non-specific since it also occurred with normal rabbit serum. Treatment of SRBCs with neuraminidase slightly enhanced rosette formation by thymus cells, but did not induce peripheral blood lymphocytes to form rosettes. Rosette formation did not occur under a variety of conditions with normal or neuraminidase-treated human, horse, pig, rabbit, guinea-pig, chicken or autologous RBCs. SRBC rosette forming cells were also found in lymph nodes (2-14%) and spleen (less than 5%), but rarely or never in peripheral blood and bone marrow of calves and adults. In foetuses at 80 days of gestation, 49% of thymus cells formed E rosettes. Foetal lymph node cells formed E rosettes at 160 days and spleen at 180 days. Cells with membrane-bound Ig were observed by IFT; their distribution did not coincide with the occurrence of E rosettes. E-rosette formation might be a marker for a subpopulation of bovine T cells.

Animals↗
PubMed1976

Some effects of silical treatment on Marek's disease.

Treatment of newly hatched chicks with silica by the intraperitoneal route delayed the onset of mortalities due to the JM strain of Marek's disease (MD' virus inoculated at 6 days of age. During the 88-day observation period fewer silica-treated chicks died of MD, but this difference was not usually statistically significant. Silica treatment had no effect on the susceptibility of 4-week-old birds. Silica treatment reduced the antibody response to MD but, in general, not significantly. The antibody response to bovine serum albumin was significantly enhanced if measured by the indirect hemagglutination test but not if measured by the agar gel diffusion test, whereas the response to Brucella abortus was enhanced significantly in N-line (MD-resistant) chicks but not significantly in P-line (MD-susceptible) chicks. Five days after infection, silica-treated chicks had significantly less fluorescing antigen in thymus and bursa than did untreated chicks; no difference was observed in the spleen. After silica treatment the glass-adherent cell population in the buffy coat was increased by up to 10-fold compared with untreated chicks. It is suggested that silica treatment induced macrophage proliferation, with subsequent restriction of MD virus spread, yet allowed an adjuvant-type effect with other antigens.

Animals↗
PubMed1976

Fractionation of fowl immunoglobulins.

Serum, Na2SO4-precipitated serum immunoglobulins and bile from 12-week-old fowls, and serum from day-old chicks, were fractionated by Sephadex G-200 gel filtration, DEAE Sephadex A-50 ion exchange chromatography and ultracentrifugation through 10-40 per cent sucrose gradients. Elution of IgM, IgG, IgA and albumin was monitored by examination of fractions in agar gel diffusion against antisera specific to these proteins. Serum and bile from 12-week-old fowls contained IgM and IgA in two molecular sizes and a single molecular size of IgG. Day-old chick serum contained IgM estimated to be 7S, a polymerised form of IgG in addition to the normal 7S component, and a small molecular weight protein antigenically related to IgA. Most of the albumin in bile was of lower molecular weight than serum albumin, while heavy forms of albumin were detected in ultracentrifugation of bile and day-old chick serum.

Animals↗
PubMed1975

Fowl immunoglobulins: quantitation and antibody activity during Marek's disease in genetically resistant and susceptible birds.

Five-week-old birds of resistant (N) and susceptible (P) genetic lines were inoculated with the JM strain of Marek's disease (MD) virus. MD occurred only in P-line birds; one-third had died by the end of the experiment (63 days after inoculation). Sera were examined for antibodies (precipitating, virus neutralizing,and fluorescing), and immunoglobulins were measured. Antibodies were associated with immunoglobulin classes by density gradient centrifugation and utilization of specific antisera to gowl immunoglobulins in indirect immunofluorescence. Precipitating antibodies were found in both lines; they first appeared 7 days after inoculation in P-line birds and 14 days after inoculation in N-line birds, but thereafter there was no difference between the two genetic lines. A peak of neutralizing antibody occurred in both lines between 6 and 12 days. Thereafter neutralizing antibodies increased gradually throughout the experiment. Neutralizing antibody levels were at this stage often higher in N-line than in P-line birds. The fluorescent antibody test showed transient immunoglobulin (Ig) M antibody from 7 to 9 days in N-line birds and 5 to 12 days in P-line birds; this corresponded with the initial peak of neutralizing antibody. Antibodies were seen from 7 to 8 days after inoculation and increased gradually durin gthe experiment, generally paralleling the secondary increase in neutralizing antibodies. Ultracentrifugation confirmed the presence of IgM and IgG antibodies as described. Antibodies of the IgA class were not found. The alterations in serum immunoglobulin levels occurred in three phrases: (i) 1 to 9 days postinfection, there was an increase in IgM and IgA compared with uninfected control birds; (ii) 10 to 20 days postinfection, Ig M and IgA levels were lower than in control birds; and (iii) 21 days postinfection, until the end of experiment, IgA returned to normal levels, IgG increased to about eight times higher than in control birds, and IgM in P-line birds returned to normal levels and in N-line birds reached and maintained levels about double those of control birds. Another experiment was designed to examine the separate effects of moving and inoculation of uninfected kidney cells and virus-infected kidney cells. The changes in immunoglobulins observed in the first experiment occurred only after infection with MD virus and were not related to movement or handling stress. It was concluded that no significant primary difference exists in the humoral immune system between fowls resistant and susceptible to MD; all differences could be related to the immunosuppressive effects of MD, which are greater in susceptible birds apparently due to the greater lymphoid tissue damage in these strains.

Animals↗
PubMed1975

Fowl Immunoglobulins: Quantitation in Birds Genetically Resistant and Susceptible to Marek's Disease.

The development of serum immunoglobulins was observed in chicks genetically resistant (N line) and susceptible (P line) to Marek's disease (MD), in conditions free from infection with MD. IgG was present at hatching at about 5.0 mg/ml and decreased to about 0.5 mg/ml by 12 to 15 days. Active production of IgG was apparent at about 20 days of age and reached levels of 2.0 to 3.0 mg/ml by 67 days. Low levels of IgM were present at hatching, and a gradual increase was seen to 1.0 to 2.0 mg/ml by 67 days. IgA was not detectable at hatching; it appeared in N-line birds at 5 days and in P-line birds at 13 days, and by 67 days was about 0.10 to 0.13 mg/ml. After 30 to 40 days, immunoglobulin levels were generally higher in N-line than in P-line birds. However, it was concluded that no primary immunoglobin deficiency existed sufficient to explain the susceptibility of the P-line birds to MD.

Journal Article↗
PubMed1974

Genetic influences affecting the occurrence of a diabetes mellitus-like disease in mice infected with the encephalomyocarditis virus.

The M variant of encephalomyocarditis virus produces a diabetes mellitus-like disease in DBA/2 mice but not in animals of the C3H strain. Fewer than one-third of infected F(1) (DBA/2 x C3H) progeny exhibit the disease, whereas the prevalence in backcrosses (F(1) x DBA/2, F(1) x C3H) is comparable to the parental inbred strain. Thus, the mode of inheritance of the diabetic predisposition appears to be polygenic. DBA/2 animals develop striking inflammatory and necrotizing lesions of the islets of Langerhans; in contrast, alterations of the insular tissue in the C3H mice are minimal. Although metabolic abnormalities appear to be consequent to lesions of beta cells, the factors influencing the severity of these insular changes are incompletely understood.

Animals↗
PubMed1972

Characterization of the haemagglutinin and neuraminidase antigens of some recent avian type A influenzavirus isolates from Hong Kong.

During 1969 type A influenzaviruses were isolated from three outbreaks of disease among domestic ducks in Hong Kong. The isolates were characterized in haemagglutination inhibition and neuraminidase inhibition tests with antisera to prototype avian and human influenza strains. A/duck/Hong Kong/46/69 and 120/69 contained haemagglutinin and neuraminidase antigens related to those of A/turkey/Wisconsin/66. The neuraminidases of these Hong Kong isolates, like that of turkey/Wisconsin/66, were antigenically closely related to those of human Asian influenzaviruses. A/duck/Hong Kong/826/69 contained haemagglutinin and neuraminidase antigens related to those of chicken/Scotland/59 and tern/South Africa/61, respectively. The duck influenza A isolates represent the first viruses of their antigenic variety to be isolated in South-East Asia. The possible epidemiological significance of the duck/Hong Kong/69 strains is discussed.

Animals↗