Search PubMed⌕ Search

Biomedical subjects

D A Nealon

Publications and source records attributed to D A Nealon.

32 records · Page 2Linked to original sources
PubMed1979

Interaction between human IgG and human creatine kinase isoenzyme-1 in serum: a route for the intravascular catabolism of creatine kinase-1?

In vitro incubation, at 37 degrees C, of human creatine kinase isoenzyme-1 (isoenzyme BB) and human immunoglobulin G in a buffer results in the formation of a complex of high relative molecular mass (Mr approximately 825,000), which contains both proteins. This complex also forms in vitro if creatine kinase isoenzyme-1 is incubated with fresh human serum. The creatine kinase activity of the complex obtained from either incubation is extremely labile, even in the presence of a chelating agent and a thioglycerol. We present evidence for the existence of this complex in the sera of patients who have detectable serum creatine kinase isoenzyme-1 activity. Sera with high activities of creatine kinase isoenzyme-2 do not appear to have this complex. We therefore speculate that complexing of creatine kinase isoenzyme-1 with serum immunoglobulin G may be a pathway of enzyme degradation.

Creatine Kinase↗
PubMed1977

Stability of commonly used thiols and of human creatine kinase isoenzymes during storage at various temperature in various media.

We assessed the stability--at 20, 4 --20, and --80 degrees C--of 2-mercaptoethanol, dithioerythritol, and dithiothreitol, and of semi-purified creatine kinase isoenzymes of human origin in the presence and absence of the three compounds. The isoenzymes plus the sulfhydryl compounds were also assessed an aqueous buffer, in heat-inactivated pooled sera, or in fresh pooled sera with low endogenous total creatine kinase. We also examined the influence of thawing conditions from--20 or--80 degrees C, of fast freezing, and of exposure to fluorescent light. At 20 and 4 degrees C some--SH groups are oxidized. At--20 and--80 degrees C this loss is diminished. It is a function of both temperature and diluent. For stability, creative kinase isoenzymes stored at any temperature require the presence of a suitable sulfhydryl compound. Periodic addition of fresh sulfhydryl solutions stabilized creatine kinase isoenzymes suspended in the two protein-based diluents by 10-30%; for those in an aqueous buffer such additions decreased the activity to stored creatine kinase isoenzymes. Fast freezing does not increase recovery of creatine kinase isoenzyme activity over slow freezing at--80 or--20 degrees C. Thawing should be done as infrequently as possible and should be done rapidly, at 37 degrees C, for the residual enzyme activity to be maximal.

Creatine Kinase↗
PubMed1975

Lability of human creatine kinase isoenzymes at 37 degrees C: a complication of electrophoretic separation.

The activity of the brain specific isoenzyme of creatine kinase is shown to fall off rapidly at 37 degrees C, particularly in the presence of albumin. Dithiothreitol cannot reverse this lability. The implications of this finding suggest that electrophoretic techniques which use incubation methods to detect the brain specific isoenzyme of creatine kinase may underestimate the true activity.

Brain↗
PubMed1975

Separation of creatine kinase isoenzymes in serum by ion-exchange column chromatography (Mercer's method, modified to increase sensitivity).

We describe our experience with Mercer's method [Clin. Chem. 20, 36 (1974)] for separating isoenzymes of creatine kinase (EC 2.7.3.2) in serum by ion-exchange chromatography. By using diethylaminoethyl cellulose rather than diethylaminoethyl Sephadex in the column and by changing the ionic strength of the eluting buffer, we could detect a significant proportion of the MB isoenzyme of serum creatine kinase at normal activities of creatine kinase in serum, even in the absence of cardiac disease.

Cellulose↗
PubMed1974

Efficacy of trimethoprim and sulfamethoxazole in the prevention and treatment of Pneumocystis carinii pneumonitis.

A combination of trimethoprim and sulfamethoxazole was effective in the prevention and treatment of Pneumocystis carinii pneumonitis in cortisonetreated rats. Although all of 15 untreated rats died with P. carinii pneumonitis, none of 15 given trimethoprim-sulfamethoxazole prophylactically acquired the infection. After P. carinii pneumonitis was established, 9 of 14 rats recovered after treatment with trimethoprim-sulfamethoxazole compared with only 2 of 14 treated with pentamidine isethionate. Rifampin and clindamycin, separately or in combination with pentamidine, were ineffective in the prevention and treatment of P. carinii infection.

Alkanesulfonates↗
PubMedDate not supplied

Is heparinized plasma suitable for use in routine biochemistry?

Using lithium heparin plasma and serum, we compared the values of 27 biochemical analyses performed with a Kodak Ektachem 500 analyzer. For 16 of the 27 tests, we observed statistical differences between the mean results obtained from the analysis of heparinized plasma and those obtained from the analysis of serum (Student t-test; P < .001). However, none of these differences were medically significant. When the concentration of lithium heparin was increased to three and five times normal (reflecting incomplete Vacutainer tube filling), alanine aminotransferase, amylase, aspartate aminotransferase, lipase, and potassium all exhibited some changes compared with serum. Therefore, heparin may be used to shorten the turnaround time in the routine biochemistry laboratory, but the anticoagulant tubes should be completely filled to prevent spurious intraindividual variations in serial specimen analysis.

Adult↗
PubMedDate not supplied

Stability of twenty-five analytes in human serum at 22 degrees C, 4 degrees C, and -20 degrees C.

The stability of 25 analytes from serum of healthy donors was determined at room temperature, 4 degrees C, and -20 degrees C over 48 h, 14 days, and 4 months, respectively. Glucose, blood urea nitrogen, sodium, potassium, chloride, creatinine, calcium, phosphorus, uric acid, total protein, albumin, triglycerides, lipase, total creatine kinase, gamma-glutamyltransferase, iron, magnesium, and cholesterol were stable at all three temperatures for the specified times. Carbon dioxide, aspartate and alanine aminotransferases, lactate dehydrogenase, amylase, alkaline phosphatase, and high-density lipoprotein cholesterol demonstrated some loss over time. Proper storage temperatures and times must be considered for these analytes if measurement is not to take place immediately after specimen collection.

Adult↗