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Biomedical subjects

J P McCue

Publications and source records attributed to J P McCue.

10 recordsLinked to original sources
PubMed1988

Changes induced in antibodies by isolation methods.

IgG was isolated from plasma at low temperatures using the Cohn fractionation method, and then processed to three different products in order to evaluate how chemical and physical manipulations affect antibodies. Evaluation of the antibodies was done by measuring their ability to bind human immunodeficiency virus, cytomegalovirus, Herpes simplex virus, and rubella virus. In addition, the IgG products were compared by crossed immunoelectrophoresis, and circular dichroism and ultra violet spectroscopy. It was found that exposure of purified IgG to physiological pH altered the molecular conformation of IgG and induced various degrees of irreversible loss in antibody binding to viruses. These observations indicate that more efficacious antibodies may be obtained for clinical use if isolation at their isoelectric point is avoided.

Chemical Precipitation↗
PubMed1980

Platelet lesion of collection.

In the early stages of blood collection for transfusion, whole blood is subjected to trauma from the anticoagulant. The blood--anticoagulant mixture does not attain a pH at which platelets can remain functional (approximately pH 6.0) until about 25% of the unit has been collected. We have examined platelet ultrastructure and in vitro aggregation responses to adenosine diphosphate (ADP) and epinephrine (EPN), to assess the platelet trauma of collection into citrate-phosphate-dextrose. For comparison blood was collected by 2 methods: one was conventional (CC), the other metered anticoagulant into the blood as it was collected (MC). Platelets from CC blood showed disruption of organelles and depletion of the dense bodies, whereas platelets from MC blood showed no ultrastructural damage. In addition, biphasic aggregation in response to ADP or EPN was seen in MC platelets but not in CC platelets.

Adenosine Diphosphate↗
PubMed1979

Changes in oxygen radical scavenging by human blood cell lysates concurrent with viral infections.

The higher superoxide dismutase (SOD) levels found in human blood cells when Nitro Blue Tetrazolium (NBT) rather than Cytochrome C was used as the colorimetric detector of superoxide (O-2) was investigated. the NBT was found to react with oxygen radicals other than O-2, thus providing measurement of total oxygen radical scavenging ability. Also investigated was the biomodal distribution of SOD activity in lymphocytes and granulocytes from a randomly selected human populace. Human lymphocytes rapidly increased their SOD activity by two- to four-fold during respiratory viral distress. The response to certain infections was probably responsible for the bimodal distribution of SOD activity in the general populace. It was concluded that the chemical events that prepare lymphocytes and granulocytes for their role in defense against infections begin long before these cells are sequestered from circulation by the infections.

Adult↗
PubMed1977

Oxidation of procarbazine in the presence of Ti(IV).

The air oxidation of procarbazine in the presence of Ti(IV) was examined as a model system for the effects titanium has on oxidative processes and intermediates involving molecular oxygen. It was found that Ti(IV) inhibited oxidation when the substrate, procarbazine, was coordinated to titanium. This inhibition was most prominent (reduction of overall rate constant by a factor of 10(2)) in its interference with Cu(II) catalyzed oxidation of the substrate whole oxidation by the neutral species O2 was only slightly inhibited (factor of 2). However, when Mn(II) was used to catalyze the oxidation of procarbazine by air, titanium enhanced the catalytic effect of Mn(II) by a factor of 10(2). This enhancement was found to be due to Ti(IV) catalysis of the air oxidation of Mn(II), and the effect was found to be inhibited by catalase but not superoxide dismutase or peroxidase. These results are discussed in terms of a Ti(IV) ability to activate molecular oxygen and its ability to form oxygen free-radical complexes.

Air↗
PubMedDate not supplied

Reversal of the storage lesion of CPD bank blood: a problem in clinical medicine.

The effect of phosphate buffer on the course of pH, ATP, and 2,3-PDG of CPD red blood cells stored at three temperatures was observed. Basic phosphate at an equilibrated level of 10 mM (as iP) maintained pH above 7.00 and ATP and 2,3-DPG above 70 per cent of initial value in cells stored at 37 C for 24 hours. In contrast however, at 25 and 4 C no buffering was obtained with basic phosphate concentrations up to 50 mM, but values for both ATP and 2,3-DPG were higher in phosphate treated aliquots than in controls throughout storage. When the pH of blood stored at 4 C was adjusted into the range 7.15 to 7.25 with tromethamine and the level of iP raised to 10 mM by addition of Na2HPO4 on day seven, it was found that ATP and 2,3-DPG levels were maintained at 90 and 120 per cent, while control levels fell to 60 and 12 per cent, respectively at 21 days. The process described parallels the normal repair of damaged red blood cells of bank blood that occurs in vivo following transfusion.

Adenosine Diphosphate↗
PubMedDate not supplied

Three generations of immunoglobulin G preparations for clinical use.

The first purified human immunoglobulin G (IgG) preparation used clinically was immune serum globulin (ISG), which was prepared in the 1940s by E. J. Cohn's group. It was originally formulated in water with 0.3 M glycine at pH 6.8 and was 70%-80% monomeric. ISG was safe when given intramuscularly and efficacious for measles and hepatitis prophylaxis. The next generation of purified IgG began in the 1960s with chemically modified preparations suitable for intravenous administration. The first such IgG intravenous preparation (IGIV) in the United States was IGIV pH 6.8 (Gamimune, Cutter Biological), in which the anticomplement activity found in ISG was removed by reduction and alkylation of disulfide bridges. This product was originally formulated as a 5% IgG solution in water (pH 6.8) with 0.2 M glycine in 10% maltose for stabilization. It remained stable for at least 2.5 years at 5 degrees C, was 80%-90% monomeric, had virtually no anticomplement activity, was safe given intravenously, and was efficacious for prophylaxis in agammaglobulinemic patients. A third generation of purified IgG has since been developed; IGIV pH 4.25, (Gamimune N, Cutter Biological), which was isolated by the Cohn method from human plasma and is safe for intravenous use, is a 5% solution of IgG in water (pH 4.25) with 10% maltose. The product is greater than 99% IgG, greater than 95% monomeric, and has greater than 90% less anticomplement activity than ISG.

Agammaglobulinemia↗
PubMedDate not supplied

Changes in red blood cell membrane phosphate concentration during blood bank storage.

The change in red blood cell membrane phosphate concentration of standard CPD whole blood stored in Fenwal blood bags at 4 C was measured daily for two weeks. Membrane phosphate concentrations increased rapidly when stored pH fell to 6.95. At the same time, the rate of K+ leakage from the cells increased, and transport of inorganic phosphate across the membrane decreased. It is concluded that gross uptake of phosphorus by the red blood cell membrane during blood bank storage may be in part responsible for physical changes in the membrane.

Adenosine Triphosphate↗