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Biomedical subjects

D R Cooper

Publications and source records attributed to D R Cooper.

At least 109 records · Page 6Linked to original sources
PubMed1978

Ex vivo removal of serum IgG in a patient with colon carcinoma: some biochemical, immunological and histological observations.

Plasma of a patient with metastatic colon carcinoma was perfused over Formalin and heat-killed S. aureus, in an extracorporeal filtration apparatus, in order to nonspecifically remove IgG and its complexes. Twenty ex vivo absorption procedures were done, over a five-month period, with a minimum of discomfort to the patient. Extracorporeal perfusion of plasma on S. aureus effectively reduced the levels of IgG and immune complexes in the perfused plasma. The nonspecific removal of IgG resulted in 1) slight biochemical alterations in the serum, 2) a transient reduction in the serum blocking activity and appearance of complement-dependent serum cytotoxicity, 3) an increase in the serum IgM levels, 4) a transient increase in the Ig surface-bearing lymphocytes and a decrease in "E" rosetting lymphocytes in the first 24-48 hours postperfusion, particularly during the early treatments, 5) an improvement in general condition of the patient and decrease in tumor size, and 6) histological changes in the tumor consistent with tumor destruction. The potential problems and clinical applications of procedures involving ex vivo specific or nonspecific immunoabsorbents are discussed.

Adenocarcinoma↗
PubMed1978

Ex-vivo removal of mammalian immunoglobulin G: method and immunological alterations.

We have described a clinically feasible method capable of rapidly and repeatedly removing mammalian IgG extracorporeally by adsorption onto heat-killed, formalin-stabilized Staphylococcus aureus Cowan-I. In dogs, 2-13 grams of IgG were removed in 60-70 minutes, lowering the serum concentration of IgG by 30-70 percent. Serum IgG levels returned to pre-run values within 48-72 hours and, in some cases, were higher than pre-run levels at 48-72 hours. Serum biochemical alterations were generally transient and relatively modest. Peripheral lymphocyte counts showed minimal changes but the percentage of erythrocyte rosette forming cells appeared to increase with successive runs. This method is safe and efficient, and can be repetitively performed at short intervals in dogs. This method may prove useful in diseases in which rapid removal of circulating IgG is desired.

Animals↗
PubMed1972

Effect of compounds of the urea-guanidinium class on renaturation and thermal stability of acid-soluble collagen.

The effects of guanidinium salts in decreasing the renaturation rate and lowering the thermal stability of acid-soluble calf-skin collagen have been compared with those of formamide and urea. With the exception of guanidinium sulphate at higher concentrations, no qualitative differences were apparent in the effects of these perturbants, which thus differed only in molar activity. Activity variation in the guanidinium salts reflected a net effect resulting from additivity of cation and anion contributions. As observed in other protein systems, lyotropic activity increased in the series formamide<urea<guanidinium ion, and in the guanidinium salts in the anion order fluoride<sulphate<chloride<bromide<nitrate<iodide. Low activities of guanidinium fluoride and sulphate were attributable to counter-effects of the anions, which acted as structural stabilizers. Changes in renaturation kinetics induced by either temperature or added perturbants appeared to conform with the Flory-Weaver model for the collagen transition. Additivity and non-specificity of the observed effects are discussed with particular reference to a common mechanism involving weak, non-saturated binding of perturbants at protein peptide groups.

Animals↗
PubMed1971

The effects of certain glycols, substituted glycols and related organic solvents on the thermal stability of soluble collagen.

The effects of a number of related diols, substituted diols and glycerol on the thermal stability of acid-soluble calf skin collagen were investigated. Thermal transition temperatures were determined by optical rotation measurement. Short-chain diols with terminal hydroxyl groups, i.e. ethylene glycol and propane-1,3-diol, stabilized the protein at all accessible concentrations. Stabilization was also observed with glycerol and diethylene glycol. Higher homologues in the diol series produced various effects, as did hydroxyl-group positional isomerism. Monoalkyl substitution of diols progressively lowered the denaturation temperature of collagen. Results are discussed in relation to possible mechanisms of perturbant action.

Animals↗
PubMed1971

The effects of glycols on the renaturation of soluble collagen.

The effects of a number of related glycols and substituted glycols on the renaturation kinetics of acid-soluble calf-skin collagen have been investigated. Optical rotation recovery was monitored at a fixed temperature in the presence of perturbants and the initial rates of reaction were determined. The effects of perturbants on stability of the native protein are compared with their action in the renaturing systems. The relationship between initial recovery rates and fixed-time [alpha]-values is shown to be dependent upon the renaturation temperature. The influence of perturbant concentration on recovery rates is discussed in terms of present theories of the mechanism of collagen renaturation.

Animals↗
PubMed1969

The decomposition of soluble collagen by gamma-irradiation.

1. The effect of gamma-irradiation in the range 1 krad-10 Mrads on freeze-dried acid-soluble collagen was studied. 2. The specific-rotation and reduced-viscosity recoveries after heating and cooling of the irradiated collagen in solution showed a high degree of dependence on irradiation dose, with reduced viscosity showing significantly less recovery than specific rotation on increasing the irradiation dose. 3. The dependence of reduced viscosity on concentration was greatly decreased with increased doses of gamma-irradiation. 4. The melting temperature measured by optical rotation also decreased as the irradiation dose was increased, and at low doses was distinctly biphasic. 5. Physical properties showed that the action of gamma-irradiation up to 10 Mrads occurred in two distinct phases, with the early changes being extremely sensitive to irradiation dose. 6. The action of the gamma-irradiation is discussed in terms of the structure of tropocollagen.

Collagen↗