Biomedical subjects

B Amorena

Publications and source records attributed to B Amorena.

11 recordsLinked to original sources

PubMed1992

An efficient microtest to study adherence of bacteria to mammalian cells.

A simple, fast and highly reproducible microtest was developed for in vitro adherence studies. A rat epithelial cell line was investigated for the adherence of clinical and subclinical ovine and bovine Staphylococcus aureus strains isolated from mastitis. Staphylococcus aureus strains differed in their ability to adhere to epithelial cells, the degree of adherence being dependent on the concentration of bacteria used in the test.

Animals↗

PubMed1991

Infection of rabbit mammary glands with ovine mastitis bacterial strains.

An experimental model was developed in rabbits to study ovine mastitis. A total of 19 ovine mastitis bacterial strains (seven Staphylococcus aureus, four Staph. chromogenes, four Staph. hyicus and four Escherichia coli) were used for mammary gland infections. The histopathological results showed that the ovine mastitis types corresponded to experimental infections produced in the rabbit with the ovine strains. These results helped the grading of the bacterial species tested according to the severity of their effects on the mammary gland. The most pathogenic species was Staph. aureus, followed by E. coli, Staph. hyicus and Staph. chromogenes, in that order. There was, however, variation among strains within a given species (e.g. one out of seven Staph. aureus strains gave rise to a mild infection in sheep and rabbits). The procedure was simple and consisted of introducing bacterial suspensions through alternate teat ducts of does with the help of a cannula. It helped minimize the number of animals required in the experiments.

Animals↗

PubMed1990

Factors influencing the degree of in vitro bacterial adhesion to ovine mammary gland epithelial cells.

Bacterial adhesion to mammary gland epithelial cells (EC) may play a role in the pathogenesis of mastitis. In vitro adherence systems have been developed to study mastitis in cattle but little has been done in sheep. In this work, a method is described for obtaining mammary gland cell preparations containing greater than or equal to 65% EC from live or dead ewes, using a Ficoll-Hypaque flotation method (cell viability = 70-90%). An in vitro adhesion assay procedure was also developed to study the interaction between EC and ovine mastitis bacterial strains. It was observed that, under the test conditions, adherence increased as the incubation time was prolonged from 30 to 120 min (P less than 0.05). Adhesion was greater at incubation temperature of 37 degrees C than at 22 degrees C (P less than 0.001). An acidic pH (5.9) was associated with an increase in adhesion, when compared with a higher pH (7.2; P less than 0.05). Tween 20, Tween 80 and bovine serum albumin helped to eliminate a background of unbound bacteria from the test slides, but they also inhibited adhesion to some strains. Strain differences in adhesion and in ability to form a background were also observed. Some of these findings may have in vivo implications.

Animals↗

PubMed1990

Milk whey induction of agglutination in ovine and bovine mastitis Staphylococcus aureus.

A total of 59 mastitis staphylococcic strains were tested for growth agglutination upon supplementation of growth media with ovine and bovine milk whey and mammary secretions from dry cows. Differences were observed when comparing bacterial species or origins (ovine vs. bovine) of bacteria and whey. All of the ovine and bovine S. aureus strains tested, but only 4 among 22 other ovine mastitis staphylococcic strains, showed growth agglutination in Todd Hewitt broth (THB) supplemented with greater than or equal to 30% (v/v) ovine milk whey. None of the strains agglutinated during growth in regular THB medium. Ovine whey had an agglutination induction capacity higher than bovine whey (P less than 0.005), concerning the number of responsive ovine and bovine S. aureus strains. There were no differences between whey samples from different ewes with regard to their capacity to induce agglutination. Ovine S. aureus strains were more responsive than bovine strains of this bacterial species, concerning the number of responsive strains (P less than 0.001) to bovine whey (greater than or equal to 30% in THB), the proportion of responsive strains at low (10%) ovine whey concentration (P less than 0.001), and the strength of reaction (precipitation timing and clump size). Secretions from dry cows systematically induced agglutination in all of the bovine and ovine S. aureus strains tested.

Agglutination↗

PubMed1989

Blood biochemical polymorphisms as markers for genetic characteristics of wild Spanish and domestic rabbits.

Seventeen blood proteins were studied in a sample of 412 Spanish wild rabbits and in 598 domestic rabbits belonging to various breeds. The wild rabbit populations showed a high level of genetic polymorphism. Six loci were monomorphic, while the remaining ten loci were segregating for at least two alleles. Two of the loci that were polymorphic in the wild rabbits were monomorphic in the domestic ones. Wright's inbreeding coefficient in the total Spanish wild rabbit population was F = 5.66, indicating subdivision of the total population. Inbreeding coefficients, estimated by Kidd et al.'s method (Anim. Blood Grps, Biochem. Genet. 11: 21-38), differed significantly from zero, being 15.62%, in wild rabbits and 6-12% in domestic breeds, indicating consanguinity. Genetic distances between wild rabbit populations showed that factors other than geographic distance (e.g., bottlenecks, barriers such as rivers, mountains, etc.) may explain the result that a northern population forms a cluster with two central populations whereas the northeastern populations form a different cluster with another central population. Populations of the first cluster are more closely related to the captive populations than others. There are three population clusters of domestic rabbits, namely (1) New Zealand White and a hybrid combination; (2) Spanish Common, Butterfly, Burgundy, and Californian; and (3) Spanish Giant.

Animals↗

PubMed1987

Relationship between rabbit transferrin electrophoretic patterns and plasma iron concentrations.

Rabbit transferrin (Tf) was studied electrophoretically using 1141 blood samples from individuals belonging to seven populations (Spanish Common, Spanish Giant, Butterfly, Lyoné de Bourgogne, New Zealand White, Californian and New Zealand White X Californian hybrids). No Tf polymorphism was found by starch gel electrophoresis, but six patterns, differing in the presence and/or intensity of three bands ('a', anodic; 'b', intermediate; and 'c', cathodic) were observed by polyacrylamide gel electrophoresis. No genetic model could explain these patterns, since they reflect differences in plasma Tf iron content. The electrophoretic test allowed a direct observation of the relative in vivo levels of the different Tf molecular species; saturated (band 'a', Fe2Tf); semi-saturated (band 'b', Fe1Tf); and without iron (band 'c' Fe0Tf, apotransferrin). The degree of iron saturation of Tf varied among individuals and throughout the individual's life. Specifically, in pregnant females, Fe2Tf and Fe1Tf are generally observed, except in late pregnancy (from day 25 to parturition), when mainly apotransferrin is observed. Significantly, within 24 h post-partum, high levels of Fe2Tf are reached in the female's serum.

Animals↗

PubMed1987

Evidence for transferrin polymorphism in Spanish wild rabbits.

Serum samples from 412 Spanish wild rabbits were analysed by starch and polyacrylamide gel electrophoresis. Three different transferrin (Tf) phenotypes (A, AB and B) were observed by both methods. The occurrence of two codominant alleles (TfA and TfB with frequencies of 0.89 and 0.11 respectively) at an autosomal locus (Tf) was supported by the population data on genetic equilibrium. Electrophoretic mobility differences between the Tf variants A and B could not be explained by differences in sialic acid or iron contents. Each of the two Tf variants were shown to have two sialic acid residues by neuraminidase treatment. These variants had similar affinities for iron, and iron binding did not lead to the conversion of one variant into the other.

Alleles↗

PubMed1987

Linkage studies in blood biochemical polymorphic markers of rabbits.

Five erythrocyte proteins (Adenosine deaminase, Ada; 6-Phosphogluconate dehydrogenase, Pgd; Esterase 1, Es-1; Esterase 3, Es-3; NADH-Diaphorase 2, Dia-2) and a serum beta-globulin protein (Esterase 7, Est-7) were studied in rabbits using starch gel electrophoresis. Samples were obtained from 317 Spanish Common individuals (38 families, 317 individuals). For the analyses of linkage, Morton's sequential probability ratio test was applied. Clear evidence for linkage between Es-1 and Est-7 (theta 0.2) was obtained, and no evidence of linkage was obtained for the remaining pairwise combinations of loci studied.

Alleles↗

PubMed1980

Bovine lymphocyte antigens (BoLA): a serologic, genetic and histocompatibility analysis.

Eleven lymphocyte antigens have been defined in cattle using 81 lymphocytotoxic sera. These sera (typing reagents) were selected from over 1,000 normal sera, 35 alloimmune sera, and 111 samples of colostrum whey. Absorptions revealed that nine of the 11 antigens detected by these reagents are serologically independent. Segregation of the genes controlling these antigens was observed among 470 calves from mating of 56 heterozygous sires and 360 dams, indicating that each of the 11 antigens is controlled by one of 11 alleles at a single autosomal co-dominant locus BoLA-A (Bovine Lymphocyte Antigen, locus A). To determine the relation between BoLA antigens and histocompatibility, skin allografts were exchanged among four unrelated adult cows. Incompatibilities for the SD antigens, but not MLR or blood group antigens, were predictive of early rejection of allografts. Furthermore, graft recipients produced antibodies against the SD antigens of incompatible donors. These results indicate that the BoLA-A locus is part of the major histocompatibility complex (MHC) of cattle.

Absorption↗

PubMed1979

Analysis of alloantisera against bovine lymphocytes. Joint report of the 1st International Bovine Lymphocyte Antigen (BoLA) workshop.

The results and agreements of the 1 international BoLA workshop, held in Edinburgh, Scotland in August 1978, are reported. Most of these concern the results from a comparison test of 249 alloantisera to bovine lymphocytes, the antisera being contributed by 9 laboratories. These sera were compared directly in Edinburgh on a panel of lymphocytes from 130 cattle of 21 breeds. In the microlymphocytotoxicity test used 75% of the sera reacted. Sixty eight of these sera were grouped into clusters according to their reaction patterns against the lymphocyte panel. Eleven of these clusters were clearly defined and were given workshop BoLA designations. In addition 22 sera were assigned to subgroups of the agreed clusters. There was no evidence that the method of production of the sera had any effect on their specificity. Although genetic data was not available, the phenotypes of the test panel of lymphocytes are consistent with the clusters detecting antigens controlled by multiple alleles at a single autosomal locus. It was agreed to name the genetic region where this putative locus is located BoLA (bovine lymphocyte antigen).

Animals↗

PubMed1978

Serologically defined (SD) locus in cattle.

Using cytotoxic serums obtained from multiparous cows or by alloimmunization, we have detected 11 lymphocyte antigens controlled by codominant alleles at a serologically defined locus called BoLA-A (bovine lymphocyte antigens). This locus, along with the lymphocyte defined loci previously reported, establishes the existence of a major histocompatibility system of cattle.

Alleles↗