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Biomedical subjects

M R Brandon

Publications and source records attributed to M R Brandon.

140 records · Page 8Linked to original sources
PubMed1975

The effect of glucocorticoid on immunoglobulin secretion into colostrum in cows.

The effect of corticosteroid-induced parturition on transfer of immunoglobulin into mammary secretion of cows has been studied. Seven non-lactating cows in late gestation were injected intramuscularly with a long-acting synthetic glucocorticoid and the concentrations of IgG-1 and IgG-2 were followed in blood serum and mammary secretion which were collected before and after parturition. Within 1 week of injection the udder became distended with secretion identical in appearance to mature milk. In contrast to the situation in normal cows approaching parturition, both the concentration of IgG-1 in secretion and the selective index of IgG-1 decreased after the glucocorticoid injection. A feature of the results were absence in treated cows of the characteristic decrease in serum concentration of IgG-1 just before parturition. It is concluded that glucocorticoid treatment of cows in late pregnancy results in a decreased availability of colostral immunoglobulin to the newborn calf.

Analysis of Variance↗
PubMed1975

Effect of ionic strength and ionic composition of assay buffers on the interaction of thyroxine with plasma proteins.

When plasma proteins are diluted with buffer the ionic strength and ionic composition of that buffer affects the interactions between thyroxine (T4) and its plasma protein-binding sites. Increases in phosphate, chloride or barbiturate ion concentration from 50 to 200 mmol/l caused a significant decrease in the affinity of plasma proteins for T4, and a concurrent increase in the concentration of unbound T4. These results cannot be completely accounted for by changes in ionic strength since at the same ionic strength different anions caused quantitatively different effects on unbound T4 concentration. The degree of depression of T4 binding by the three anions studied was in the order barbiturate greater than chloride greater than phosphate. The results of a systematic study on the composition of diluent buffer systems indicated that when a 50 mM-sodium phosphate-100 mM-NaCl buffer (pH 7-4) was used as a plasma diluent, there were unlikely to be gross changes in the T4-binding properties of plasma proteins with dilution.

Barbiturates↗
PubMedDate not supplied

Localization and purification of SBU-4--a pregnancy specific protein of the ovine uterus.

In order to elucidate the function of molecules of the ovine maternal-fetal interface a monoclonal antibody was produced to intact interplacentomal trophoblast membranes. Extensive immunohistological studies revealed that the monoclonal antibody recognizes a protein designated SBU-4 which originates in the intercaruncular regions of the gravid sheep uterus at about the time of implantation and increases in concentration throughout gestation. The data suggest that SBU-4 is produced by endometrial epithelial cells and that adjacent uninucleate cells of the trophoblast acquire the antigen by endocytosis. Initial biochemical analysis of the purified SBU-4 molecule prepared by monoclonal antibody immunoaffinity chromatography indicates that SBU-4 is high molecular weight glycoprotein complex comprising several sub-units.

Animals↗
PubMedDate not supplied

Ultrastructural immunogold investigation of the function and diversity of binucleate cells in the ovine placenta using a monoclonal antibody.

Ultrastructural immunogold labelling of ovine placentomes demonstrated that the molecule recognized by the monoclonal antibody SBU-3 is restricted to the fetal binucleate cell granules and Golgi body, and granules of similar size in the syncytium. Quantitative examination shows that the percentage of placentomal mature binucleate cells that are SBU-3-positive increases rapidly from a low level at 29 days of pregnancy to a plateau at virtually 100 per cent from 41 days to term, whereas interplacentomal binucleate cells rarely show label at any stage. There were no detectable differences in ultrastructure between SBU-3-positive or -negative binucleate cells. These results corroborate the hypothesis of syncytium formation by migration of binucleate cells and indicate local control of SBU-3 production and its possible role in villus formation.

Animals↗
PubMedDate not supplied

Characterization of a sheep trophoblast-derived antigen first appearing at implantation.

A monoclonal antibody designated SBU-3 was produced by the fusion of mouse NS-1 myeloma cells with spleen cells from a BALB/c mouse immunized with sheep trophoblast microvilli. Lee et al (1985) have reported the immunohistological staining of sheep trophoblast with SBU-3 showing that, as early as 21 days of gestation, the monoclonal antibody recognizes an antigen restricted to the binucleate cells of the trophoblast which are located only at sites of invasion of the underlying uterine tissue. Subsequently the antigen appears in the maternal syncytial layer. Immunoprecipitation of 125I-labelled microvilli by SBU-3, characterization of the antigen on immunoblots, and biochemical analysis all suggest that this monoclonal antibody specifically recognizes a carbohydrate epitope on a series of glycoproteins of molecular weights between 30 000 and 200 000. SBU-3 antigen is present in allantoic fluid but is not detectable in any fetal or adult tissue studied, including maternal and fetal sera. It is suggested that this antigen may have a role in the placentation process.

Animals↗
PubMedDate not supplied

Transferrin receptor on endothelium of brain capillaries.

The blood/brain barrier prevents the passive diffusion of proteins and metabolites from cerebral blood vessels into tissue spaces around neuronal and glial cells. To provide nutrients for these cells, transport mechanisms must exist and indeed have been demonstrated for metabolites. We now show that monoclonal antibodies against rat and human transferrin receptors label blood capillaries in the brain but not in other tissues. In the rat this labelling occurs after injection of antibody into the blood, thus the receptors seem to be accessible at the endothelial surface. It is possible that transferrin receptors are expressed on these cells to allow transport of transferrin (and thus iron) into brain tissues.

Animals↗
PubMedDate not supplied

Identification of cysteine-containing peptides during the peptide mapping of recombinant proteins.

Confirmation of a protein's cysteine content and of its location within the amino acid sequence is crucial in investigating the structural integrity of recombinant proteins. A combination of thiol-specific chemistry and peptide mapping by reversed-phase microbore HPLC was used to confirm the presence and map the location of cysteine residues in the primary sequences of recombinant porcine growth hormone and human tumor necrosis factor alpha. Recombinant proteins were conjugated with a hydrophobic iodoacetamide derivative, dimethylaminoazo-benzene iodoacetamide, and digested with trypsin. The peptide fragments were separated on a C8 microbore reversed-phase column using a linear acetonitrile gradient. The peptides containing the cysteine residues were selectively identified by monitoring with a diode-array detector at 215 nm with the reference wavelength set at 450 nm. Cysteine-containing peptides could be readily distinguished as inverted "negative" peaks relative to the baseline and noncysteine-containing peptides. Isolated peptide fragments were then sequenced in order to confirm the location of the cysteines in the proteins. This approach offers the benefits of selectively and rapidly identifying, from a single chromatrophic step, the cysteine-containing peptides of proteins. Furthermore, the use of the labeling reagent renders the cysteine-containing peptides more hydrophobic, thereby making them easier to separate from noncysteine-containing peptides.

Amino Acid Sequence↗