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Biomedical subjects

J C Bennett

Publications and source records attributed to J C Bennett.

At least 55 records · Page 3Linked to original sources
PubMed1990

Nonintervention into siblings' fighting as a catalyst for learned helplessness.

The hypothesis that siblings fight simply to attract adults' attention has enjoyed much speculation and some study of children's fighting in recent years. Current research indicates that refusing to intervene causes fighting to wane, supposedly because children will adequately solve problems by themselves if left to do so. The phenomenon of learned helplessness, in which lethargy and despair result from an inability to escape pain, has been applied to battered spouses. This work tests the hypothesis that nonintervention into siblings' fighting is more likely to allow one child to establish superiority over another and that fighting stops because the defeated learns helplessness in the manner of an abused spouse. Implications and alternative methods of dealing with fighting are explored.

Aggression↗
PubMed1989

Analysis of the spectrin binding domains of globin.

This study describes the results of binding studies between human spectrin and peptides obtained by trypsin digestion of human globin. The globin digest when passed through an affinity column of spectrin-coupled sepharose retained one peptide from both alpha and beta chains of globin. The absorbed peptides were eluted with 4 M guanidine hydrochloride and separated on a reverse phase column by high pressure liquid chromatography. Their amino acid sequence was determined and their position located in the globin molecule.

Amino Acid Sequence↗
PubMed1988

Conversion of the beckman liquid phase sequencer to a gas-liquid phase sequencer.

As an effective aid to extend the microsequencing capabilities the Beckman protein/peptide sequenator Series 890C has been successfully converted to a gas-liquid system, in which coupling buffer 25% trimethylamine was employed as a gas, and heptafluorobutyric acid as a liquid. The system has been found to be efficient for microsequencing (less than 100 pmol). The details of mechanical, plumbing, and other minor changes are described in this paper along with the results of sequencing proteins and peptides, directly and from blots.

Amino Acid Sequence↗
PubMed1987

Heterogeneity of binding of monoclonal IgA to staphylococcal protein A is related to the IgA polymerization state.

The human IgA2-lambda myeloma protein Fel consists of covalent dimers and monomers which are partially self-associated. Affinity chromatography of this protein on staphylococcal protein A-Sepharose revealed that approximately 8% of the protein was retained and eluted by acid buffer. Although retained protein Fel was highly aggregated, in the presence of dissociating agents mostly monomeric form was found. Affinity rechromatography and electrophoresis of both fractions from affinity chromatography revealed that the retained fraction possessed substantially higher affinity for SpA than did the nonretained one. This could be due to the multivalency of protein Fel aggregates.

Antibodies, Monoclonal↗
PubMed1986

Purification of spectrin and its subunits by high-performance liquid chromatography.

Technological and methodological advances in the techniques of structural and biological studies of proteins have reduced the required amount of sample. In conjunction with these advances, high-performance liquid chromatography (HPLC) has emerged as a technique of high utility for the purification of complex molecules. Using a combination of size-exclusion and reversed-phase HPLC and ionic buffers containing sodium dodecyl sulfate, the red cell membrane-associated high-molecular-weight polypeptide spectrin and its subunits have been purified. The system described in this paper is fast, reproducible and quantitative.

Chromatography, High Pressure Liquid↗
PubMed1986

The stoichiometry of J chain in human secretory dimeric IgA.

Dimeric human secretory IgA was completely reduced with mercaptoethanol and alkylated with [14C]iodoacetamide. The component polypeptide chains were separated by high performance gel filtration in 5 M guanidine HCl into two fractions: one containing secretory component (SC) + heavy (H) chains; and the second containing light (L) + J chains. L and J chains were subsequently separated by polyacrylamide gel electrophoresis in sodium dodecyl sulfate (SDS) or in alkaline urea. Calculations of the J chain stoichiometry in the dimeric secretory IgA (S-IgA) molecule were based on: the measurement of the ratio of radioactivities of SC + H chain and L + J chain-fractions or L chain- and J chain-fractions; the known stoichiometry of SC, H and L chains; and the known number of half-cystine residues in the component polypeptide chains of S-IgA molecule. The data demonstrated that one molecule of dimeric S-IgA contains approx. one J chain.

Chemical Phenomena↗
PubMed1986

Interleukin 1-like factor produced by a hybrid of an adherent mouse spleen cell and a thymoma cell.

A hybrid cell line (DCH-5) constructed from an adherent cell of mouse spleen and the thymoma BW5147, and selected for adherence to hydrophobic surfaces, secretes a factor which augments the mitogenic response of thymocytes. Properties of the factor were compared with those of a P388D1 and J774.1 macrophage-derived interleukin 1 (IL-1). On polyacrylamide gel electrophoresis in Tris-glycinate buffer the IL-1-like factor of DCH-5 cells was heterogeneous and its components were more negatively charged than components of macrophage-derived IL-1. Charge differences between these factors were also confirmed by isoelectric focusing (IEF) (pI of IL-1 was 5.4, pI of the IL-1-like factor was 3.5). SDS-PAGE and gel filtration demonstrated that both factors consisted of several components of near molar masses (approximately 17 kg/mol). Gel filtration showed that in PBS the IL-1-like factor of DCH-5 cells was partially aggregated. Antibodies specific to IL-1 inhibited the activity of the IL-1-like factor of DCH-5 cells. Thus, mouse DCH-5 cells provide a new source of IL-1-like factor which might be useful for further elucidation of the heterogeneity of interleukins.

Animals↗
PubMed1986

Biochemical characterization of Fc gamma receptors of mouse DCH-5 cell line.

Fc gamma receptors (Fc gamma R) were isolated from the culture medium of a mouse hybrid cell line (DCH-5) known as an over-expressor of Fc gamma R, established from a mouse adherent spleen cell and the thymoma cell BW 5147. Proteins adsorbed to insolubilized IgG were separated on Sephacryl S-200. The main fraction with maximum FcR activity was isolated and characterized as a glycoprotein with an effective molar mass of about 55 kg/mol. Under non-denaturing conditions, the protein existed as a non-covalently linked dimer. Isoelectric focussing in agarose gel showed two bands with pI = 5.2 and pI = 5.3. The amino acid composition of this fraction was similar to that of pig and human Fc gamma R, and also of rabbit FcR for polymeric Ig. The sugar composition of the fraction (about 34% w/w) resembled that of the C1q component of complement and some membrane glycoproteins.

Amino Acid Sequence↗