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Biomedical subjects

E Dixon

Publications and source records attributed to E Dixon.

At least 37 records · Page 2Linked to original sources
PubMed1988

Bovine type XII collagen: amino acid sequence of a 10 kDa pepsin fragment from periodontal ligament reveals a high degree of homology with the chicken alpha 1(XII) sequence.

A 10 kDa collagenous peptide, derived from a 30 kDa disulfide bonded fragment, was purified from bovine periodontal ligament. Amino acid sequence analysis of tryptic peptides demonstrated a 92.8% homology with the chicken alpha 1(XII) cDNA derived sequence, demonstrating for the first time the presence of type XII collagen in a mammalian species and in an adult tissue.

Amino Acid Sequence↗
PubMed1985

Properties of pig mature erythrocyte hexokinase.

Previous studies have demonstrated the presence of two type III hexokinase isozymes in pig mature erythrocytes. The prevalence of a specific isozyme species is an age-dependent phenomenon. The mature erythrocyte of young adult pigs (less than 6 mo old) possess an isozyme that has an apparent Km for glucose that is lower than in adult pigs. The data in this report suggest several basic differences between the two isozymes. D-Mannoheptulose, a structural analogue of glucose, was observed to differentially inhibit the isozymes. The young adult isozyme tended to be heat sensitive when compared with adult isozymes. Carboxypeptidase B and trypsin inhibited the activity of both isozymes, but the young adult isozyme was most dramatically affected by carboxypeptidase B. When the two isozymes were incubated in the presence of two sulfhydryl group inhibitors, HgCl2 and 5,5'-dithiobis [2-nitrobenzoic acid] (DTNB), the young adult isozyme exhibited the greater inhibition in the presence of DTNB. The data suggest that the young adult isozyme exhibited pronounced differences in activity when incubated in the presence of DTNB and carboxypeptidase B. These two agents may be used as probes to further characterize the properties of the two isozymes.

Age Factors↗
PubMed1981

Erythrocyte metabolism: kinetic and electrophoretic analyses of pig red cell hexokinase.

The mature erythrocyte of the pig has been observed to possess the slowest metabolic rate of any mammalian cell type. Previous studies in this laboratory suggested that the hexokinase isolated from these cells was inhibited by glucose in concentrations in excess of 0.2 mM. In the present study, the enzyme was isolated by utilizing DEAE-Sephadex A-50, ammonium sulfate precipitation, DEAE-cellulose (DE-52), and Sephadex G-100 gel-filtration. Studies on the hexokinase isolated from the pig mature erythrocyte by the above procedures revealed two distinct isozymes of hexokinase that do not behave kinetically and electrophoretically as those previously found in other mammalian red blood cells. The isozyme isolated from the erythrocyte of the young adult pig (less than six months of age) migrated at a slower electrophoretic rate than the one isolated from the adult pig (more than six months of age). Coupled with the observed difference in electrophoretic mobilities were changes in the apparent Km values as well as Vmax as a function of substrate concentration. In spite of the changes observed in relation to glucose, the apparent Km for Mg-ATP-2 was not altered during development. Diphosphoglycerate (DPG) was observed to be a "linear-mixed" inhibitor of both isozymes with respect to Mg-ATP-2. An experimental designed to determined the type of inhibition by DPG on the type I isozyme isolated from the horse erythrocyte revealed competitive inhibition with the Mg-ATP-2 site. Free Mg activated both isozymes in low concentrations (less than 2.5 mM) but inhibited the enzymatic activity as the concentration was elevated. The data suggest that both the young adult and the adult pig erythrocyte possess two distinct type III isozymes of hexokinase.

Adenosine Triphosphate↗
PubMed1981

The interaction between (Ca2+ + Mg2+)-ATPase and the soluble activator (calmodulin) in erythrocytes containing haemoglobin S.

In normal erythrocytes, a membrane-bound (Ca2+ + Mg2+)-ATPase is stimulated by a soluble activator, calmodulin. Since cells containing Hb S accumulate excessive Ca2+, the defect could lie in either the (Ca2+ + Mg2+)-ATPase or calmodulin. To decide between these two possibilities, we prepared (Ca2+ + Mg2+)-ATPase from erythrocytes of normal (AA), sickle cell trait (AS) and sickle cell disease (SS) individuals. Calmodulin was prepared from haemolysates from AA and SS erythrocytes. The enzyme prepared from SS ghosts had lower specific activity than that from AA membranes. Furthermore, calmodulin from either source did not stimulate the ATPase of SS erythrocytes. Enzyme from AS cells had specific activity similar to that of enzyme prepared from SS membranes. The enzymatic activity of a mixed cell population obtained from an SS patient 8 d following exchange-transfusion was proportional to the per cent Hb A. These results indicate that calmodulin is unable to interact with the enzyme site on the SS membrane. This inability is believed to be due to a specific property of the membrane and not an abnormality of calmodulin itself.

Anemia, Sickle Cell↗
PubMed1978

Perthes' disease of the hip in three regions of England.

Throughout 1976 orthopaedic surgeons in three regions of England forwarded details of all new patients with Perthes' disease attending outpatient clinics or admitted as inpatients. The incidence in the Mersey region (11.1 per 100 000 children under fifteen years) was twice that in Wessex (5.5) with Trent having an intermediate incidence (7.6). The ratio of male to female incidence varied between the regions as did the age distribution of male cases. These findings point to the importance of environmental factors in the aetiology of the disease, and suggest the need for further epidemiological studies.

Adolescent↗
PubMed1977

Reduced dose of Rho(D) immune globulin following induced first-trimester abortion.

A double-blind study of women after first-trimester abortion supports the efficacy of low-dose Rho(D) immune globulin (human) in the prevention of Rh sensitization. Twenty-seven per cent of patients demonstrated a fetomaternal blood leak based on Kleihauer-Betke stains. In follow-up testing, the percentage of positive titers and the absolute titer of detectable antibody at various intervals were related to the dose of administered immune globulin. This study confirmed the possible risk of sensitization in Rh-negative postabortal women and suggests the practical use of single low-dose immune globulin preparations in prevention.

Abortion, Induced↗