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Biomedical subjects

W Gruber

Publications and source records attributed to W Gruber.

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

Creatine kinase in serum: 5. Effect of thiols on isoenzyme activity during storage at various temperatures.

We studied changes in the activity of human creatine kinase isoenzymes (native MM in serum, MM, MB, and BB preparations in serum matrix) on storage in the presence of 0, 10, 20, and 50 mmol of N-acetyl cysteine, 2-mercaptoethanol, and 1-thioglycerol per liter of serum at 37, 30, 25, 4, and -20 degrees C. We also assessed the stability of the thiols under the same conditions. We generally confirmed increasing stability in the sequence: BB, MB, and MM isoenzyme. Above 30 degrees C irreversible inactivation is very rapid, even in the presence of thiols. At lower temperatures endogenous MM is sufficiently stable; thus, the use of protective thiols can be restricted to sera expected to contain isoenzymes MB or BB. Our studies lead us to prefer use of 50 mmol of N-acetyl cysteine per liter of serum. The other thiols cause turbidity to develop earlier and their decomposittion products diminish the activity more. The initial activity of the MB and BB preparations increased by as much as 2.3- and 1.8-fold on storage with thiols. This effect was not observed with either endogenous MB and MM or with the MM prepartion.

Creatine Kinase↗
PubMed1977

Isolation of pH-optima and apparent Michaelis constants of highly purified enzymes from human and animal sources. Comparison of enzymes of human and animal origin, I.

Enzymes from animal sources are frequently used for quality control of enzyme activity determination in clinical chemistry. For this purpose they should be very similar to human enzymes. It is shown that preparations of enzymes of diagnostic interest from human and porcine organs, purified in exactly the same way, have very similar pH-optima and apparent Michaelis constants for their substrates.

Alanine Transaminase↗
PubMed1977

Cross reactivity of rabbit antibodies against purified animal enzymes. Comparison of enzymes of human and animal origin, II.

Enzyme preparations used for quality control of enzyme activity determinations in clinical chemistry should be very similar to human enzymes. Antibodies against e.g. porcine enzymes show cross reactivity with the corresponding human enzymes, indicating partial identity of the enzyme proteins. As the enzyme-antibody precipitates retain catalytic activity the similarity between the enzyme proteins is not limited to the catalytic sites.

Animals↗
PubMed1977

Comparison of control materials containing animal and human enzymes. Comparison of enzymes of human and animal origin, III.

Highly purified enzymes of diagnostic interest from human and animal organs, dissolved in pooled human serum and in bovine serum albumin solution, were compared with respect to their response to alterations in routine clinical chemical assay conditions. Their response to changes in temperature, substrate concentration and pH-value was the same. In addition, the storage stability in each matrix was identical in the lyophilized and the reconstituted state, whereas some enzymes were remarkably less stable in the pooled human serum than in bovine serum albumin. This better stability, the better availability and decreased infectious nature of the material lead to the conclusion that animal enzymes in bovine serum albumin matrix are the material of choice for the quality control of enzyme activity determinations in clinical chemistry.

Animals↗
PubMed1977

Creatine kinase in serum: 3. Further study of adenylate kinase inhibitors.

In search of an appropriate inhibitor to suppress the interference of adenylate kinase with the creatine kinase assay, we found that the combination diadenosine pentaphosphate (10 mumol/liter) and AMP (5 mmol/liter) is a better inhibitor than is fluoride (25 mmol/liter). The latter inhibits adenylate kinase uncompetitively and weakly (Ki = 2.5 mmol/liter), and must be incorporated in the starting reagent, and at 30 degrees C it becoms fully effective only after a lag phase of 6 min. In this concentration, fluoride inhibits adenylate kinase from erythrocytes, muscle, liver or platelets by 94, 92, 88, and 87%, respectively, and creatine kinase by 8%. Bromide and chloride also inhibit creatine kinase. Attempts to replace AMP by a specific inhibitor of liver adenylate kinase failed. Homologs of diadenosine pentaphosphate with either fewer or more phosphoryl groups in the polyphosphate bridge inhibited even more weakly than did the pentaphosphate. Platelets can significantly contribute to adenylate kinase activity in serum. The inhibitor combination inhibited adenylate kinase from platelets by 90%.

Adenine Nucleotides↗
PubMed1977

Relation between concentrations of free glycerol and triglycerides in human sera.

The concentrations of total glycerol, unesterified glycerol, and glycerol deriving from triglycerides (triacylglycerols) were measured in 468 fresh human sera from unselected outpatients of a municipal hospital. The distribution mode of free glycerol was log-normal; that of triglycerides was neither normal nor log-normal. A weak but statistically approved correlation between these variables was demonstrated. A comparison of triglyceride concentrations corrected for unesterified glycerol with those based on total glycerol shows that, for the triglycerides determination, analysis for total glycerol and substraction of 0.11 mmol/liter from the resulting value appears to be justified in clinical routine. Subtraction of individual sample-blank values is unnecessary. In a triglyceride concentration range from 1.71 to 2.85 mmol/liter the 95 percentile for the possible error of this procedure ranges from + 0.04 to - 0.08 mmol/liter.

Glycerol↗
PubMed1976

Intra-amniotic administration of 15(S)-15-methyl-prostaglandin F2alpha for the induction of midtrimester abortion.

To determine the practicability of administering 15(S)-15-methyl-prostaglandin F2alpha-tromethamine (15(S)-15-Me-PGF2alpha) intra-amniotically for the induction of midtrimester abortion, initially 2.5 mg. of 15(S)-15-Me-PGF2alpha was administered to 20 physically healthy gravid women, and was repeated after 24 hours in those patients who had not aborted. Within 24 hours, 65% aborted, and within 36 hours, 95% aborted. Although 67% experienced emesis, no serious complications occurred. This abortion rate is similar to that obtained with the recommended dose schedule of the dosage of prostaglandin F2alpha approved by the Food and Drug Administration and those reported with intra-amniotic administration of either hypertonic saline or urea when augmented with high, continuous, intravenous infusions of oxytocin. While the study intra-amniotic dose schedule appeared to be practicable, large, comparative studies will be necessary to determine the most satisfactory dose schedule and whether this method is more acceptable than other available methods.

Abortion, Induced↗
PubMed1976

[Prostaglandins compared with oxytocin for induction of labour at term (author's transl)].

12 cases of induction of labour with prostaglandin F2 alpha and 8 with prostaglandin E2 were compared with 14 cases in which induction was undertaken with oxytocin. All inductions were successful, the induction--delivery intervals being slightly shorter in the prostaglandin groups than in the oxytocin group. Both with prostaglandin F2 alpha and with prostaglandin E2 the cardiotocogram showed uterine hyperactivity in most of the cases with an unexpected, episodically-occurring increase in basal uterine tone and remarkable tachysystoly. Uterine hyper-activity led to fetal heart rate alterations of the "dip 2" type in about 50% of the cases. According to these results prostaglandins cannot be considered superior to oxytocin for the induction of labour at term.

Female↗
PubMed1976

Creatine kinase in serum: 2. Interference of adenylate kinase with the assay.

Interference of adenylate kinase with Oliver's method [Biochem. J. 61, 116 (1955)] for creatine kinase is usually suppressed by including an adenylate kinase inhibitor, AMP. We studied the kinetics and compared the inhibition capacities of AMP and diadenosine pentaphosphate. Both are competitive inhibitors, AMP being markedly weaker, with a Ki of about 300 mumol/liter for adenylate kinase from erythrocyte, muscle, and liver. AMP also weakly inhibitis creatine kinase. Diadenosine pentaphosphate inhibits erythrocyte and muscle adenylate kinase strongly (Ki about 0.03 mumol/liter), the liver isoenzyme less strongly (Ki about 3 mumol/liter), and has no effect on creatine kinase up to 100 mumol/liter. All three adenylate kinases may be present in a patinet's serum, causing sample blanks to be high in a creatine kinase assay that lacks inhibitors. In acute hepatic damage, liver adenylate kinase activity in serum can be grossly increased. Use of sufficient diadenosine pentaphosphate alone for complete inhibition is relatively expensive. Consequently, we recommend a combination of both inhibitors. Diadenosine pentaphosphate, 10 mumol, combined with 5 mmol of AMP per liter inhibits adenylate kinase from erythrocytes and muscle by 97% and from liver by 95%.

Acute Disease↗
PubMed1976

Creatine kinase in serum: 1. Determination of optimum reaction conditions.

To establish optimum conditions for creatine kinase (EC 2.7.3.2) activity measurement with the creatine phosphate in equilibrium creatine reaction, we re-examined all kinetics factors relevant to an optimal and standardized enzyme assay at 30 and 25 degrees C. We determined the pH optimum in vaious buffers, considering the effect of the type and concentration of the buffer, as well as the influence of various buffer anions on the activity. The relation between activity and substrate concentration was shown and the apparent Michaelis constants of creatine kinase for creatine phosphate and ADP were evaluated. We tested the effect on creatine kinase measurement of the concentration of substrates (glucose and NADP+) in the auxillary and indicator reactions, especially the influence of the added auxiliary (hexokinase) and indicator (glucose-6-phosphate dehydrogenase) enzymes on the lag phase, at different temperatures. The NADP+ concentration proved to be the factor limiting the duration of constant reaction rate. We studied the inhibition of creatine kinase and adenylate kinase by AMP and established a convenient AMP concentration. For reactivation of creatine kinase, N-acetyl cysteine as sulfhydryl compound was introduced. Finally, we examined the relationship between activity and temperature.

Blood Glucose↗
PubMed1976

Evaluation of intramuscular 15(s)-15-methyl prostaglandin F2 alpha tromethamine salt for induction of abortion, medications to attenuate side effects, and intracervical laminaria tents.

Sixty gravidas 8 to 20 menstrual weeks' gestation were studied to evaluate (1) the efficacy of intramuscularly administered 15(S)-15-methyl prostaglandin F2alpha tromethamine (15(S)-Me-PGF2alpha) as an abortifacient; (2) the effectiveness of prochlorperazine and Lomotil for attenuation of vomiting and diarrhea; and (3) the practicability of augmenting this prostaglandin dose schedule with intracervical laminaria tents. Group I subjects received 250 mug of 15(S)-Me-PGF2alpha intramuscularly every 2 hours for the initial 24 hours and 500 mug for the next 24-hour period. Group II received the same dose schedule of prostaglandin and prearranged doses of prochlorperazine and Lomotil. Group III received the same dose schedule of prostaglandin after intracervical laminaria tents had been inserted, and prochlorperazine and Lomotil were administered by the prearranged dose schedule. It appears that (1) the 15(S)-Me-PGF2alpha was effective in inducing abortion; (2) a significant decrease in body temperature occurred; (3) the abortifacient effectiveness of this prostaglandin dose schedule was not altered by the regimen of prochlorperazine and Lomotil; (4) only diarrhea was significantly attenuated with the regimen of prochlorperazine and Lomotil; and (5) laminaria augmentation was not useful.

Abortion, Induced↗