PubMed Health⌕ Search

Biomedical subjects

J Bohner

Publications and source records attributed to J Bohner.

At least 37 records · Page 2Linked to original sources
PubMed1983

Creatine kinase variants. Report on the workshop conference of the German Society for Clinical Chemistry held on September 19 to 21, 1982 in Tübingen, FRG.

It was the aim of the workshop to summarize present knowledge of the variant creatine kinases in human blood. Discussion was centered on the nature, measurement, and clinical significance of these variants. On the basis of the presented results, the different creatine kinase variants can be classified as follows: Normal size variants (80000 Daltons). These originate from postsynthetic modifications of the three dimeric isoenzymes creatine kinase-MM, MB or BB. The M subunit can be transformed by a serum constituent and these modifications result in at least three different creatine kinase-MM and two creatine kinase-MB variants, which still show catalytic activity. The mechanism of the postsynthetic alterations of creatine kinase-BB seems to be more complex: In vitro incubation of this isoenzyme even in a non-serum matrix changes its electrophoretic mobility and decreases activity. In vivo there is evidence that on the one hand intact creatine kinase-BB molecules are directly removed from the circulation. On the other hand, however, inactive creatine kinase-BB-protein is reported to occur in serum. Variants with higher molecular weights (greater than 200000 Daltons). These are termed macro creatine kinases. Macro creatine kinase type 1 comprises the immunoglobulin-bound creatine kinase isoenzymes. Of these immune complexes, IgG-linked creatine kinase-BB is well known and has been described in detail, whereas the occurrence of creatine kinase-MM-containing macro creatine kinases is still questionable. Macro creatine kinase type 1 is found in the blood of about 2% of all hospitalized patients. It occurs mainly in elderly women, but it is not known whether it has any special clinical significance. Macro creatine kinase type 2 is the term for an oligomeric form of mitochondrial creatine kinase released after breakdown of mitochondria in liver, heart and some tumours. After treatment with urea this oligomeric form is converted into a normal sized, dimeric creatine kinase-MiMi. Macro creatine kinase type 2 is found exclusively in seriously ill patients, and may occur in more than 3% of all hospitalized patients. This classification of the creatine kinase variants seems logical, since it takes into account the nature of the creatine kinase variants, and it permits the classification of all atypical creatine kinases described in the literature. As quantification and differentiation now become possible, further experimental and clinical investigations should provide the information necessary for a better understanding of the physiology and pathobiochemistry of these multiple forms of creatine kinase.

Creatine Kinase↗
PubMed1982

Macro creatine kinase: determination and differentiation of two types by their activation energies.

Determination of the MB isoenzyme of creatine kinase in patients with acute myocardial infarction may be disturbed by the presence of macro creatine kinase. The relative molecular mass of this form of creatine kinase in human serum is at least threefold that of the ordinary enzyme, and it is more thermostable. Here we describe our method for determination of macro creatine kinases and an easy-to-perform test for differentiating two forms of macro creatine kinase, based on their distinct activation energies. The activation energies of serum enzymes are mostly in the range of 40-65 kJ/mol of substrate. Unlike normal cytoplasmatic creatine kinases and IgG-linked CK-BB (macro creatine kinase type 1) a second form of macro creatine kinase (macro creatine kinase type 2) shows activation energies greater than 80 kJ/mol of substrate. The exact composition of macro creatine kinase type 2 is still unknown, but there is good reason to believe that it is of mitochondrial origin.

Activation Analysis↗
PubMed1982

Macro creatine kinases: results of isoenzyme electrophoresis and differentiation of the immunoglobulin-bound type by radioassay.

In 2.9% of sera from 1253 unselected patients we detected two different types of macromolecular creatine kinases (CK; EC 2.7.3.2). One macro type was represented by immunoglobulin-linked CK: in sera containing macro CK-BB isoenzyme, 125I-labeled CK-BB was bound with high affinity to the immunoglobulin fraction. Furthermore, during electrophoresis, macro CK-BB mostly migrated between CK-MB and CK-MM, and was fixed to Protein A from Staphylococcus aureus. We therefore propose radioelectrophoresis as a specific, highly sensitive, and simple method for detecting this type of macro CK. This form occurs predominantly in elderly women, is not correlated to any specific disease, and persists in blood over a long period of time. In contrast, a second type (macro-CK type 2) never bound radiolabeled CK isoenzymes, and was not adsorbed to Protein A. Electrophoretic migration of this macro-CK type 2 was generally cathodic to CK-MM. We observed this type in severely ill patients, frequently those suffering from malignant tumors. Clinical observations and biochemical data suggest that macro-CK type 2 is of mitochondrial origin.

Age Factors↗
PubMed1981

Stability of macro creatine kinases and creatine kinase isoenzymes compared: heat inactivation test for determination of thermostable creatine kinases.

Creatine kinase isoenzymes showed decreasing thermal stability and increasing lability towards pH changes in the order: MM, MB, and BB. The three isoenzymes exhibited their highest stability between pH 6.5 and 7.0. At 37 degrees C and an almost physiological pH of 7.5 the decay constants were 0.025, 0.164 and 0.580 h-1 (MM, MB, and BB isoenzyme), respectively. In contrast to free creatine kinase BB, immunoglobulin-linked creatine kinase BB (macro creatine kinase BB, type 1 macro creatine kinase) showed a markedly higher stability; this accounts for the persistence of creatine kinase BB activity in macro creatine kinasaemia. In addition we identified a second type of macro creatine kinase in patients' sera, which is also thermostable. A simple heat inactivation test (20 minutes, 45 degrees C, immunoinhibition of the M-subunits) differentiates thermostable macro creatine kinases from thermolabile creatine kinases and thus completes isoenzyme diagnosis.

Creatine Kinase↗
PubMed1981

Macro creatine kinase BB: evidence for specific binding between creatine kinase BB and immunoglobulin G.

In the sera of four female patients with proven IgG-linked creatine kinase BB (macro creatine kinase BB) we studied the nature of the binding between creatine kinase isoenzymes and immunoglobulin G. The specificity towards the isoenzyme bound, the recombination of the complex after treatment with acid buffer, the site of the binding between both partners and an apparently monoclonal nature of the immunoglobulin G involved in the complex indicate that a specific antigen-antibody reaction is responsible for the existence of macro creatine kinase BB in the sera investigated.

Antigen-Antibody Complex↗
PubMed1980

[Macroamylasemia. Immunoglobulin a-amylase-complexes as rare cause of hyperamylasemia (author's transl)].

A 56 year old diabetic woman with persistent hyperamylasemia, with an extremely low renal clearance of amylase and without signs of pancreatic disease was found to have an abnormally large serum amylase. This macroamylase had a molecular size of 450,000 Daltons in gel filtration and could be dissociated at low pH values. By the use of chromatographic, electrophoretic and immuno-chemical tests, it was possible to identify the macroamylase as a complex formed by immunoglobin A (IgA kappa) along with normal pancreatic and parotic amylase. The immunoglobulins had a high affinity for human pancreatic and salivary amylase as well as for hog pancreatic amylase. It remains unclear if the amylase binding immunoglobulins are autoantibodies. The finding of macroamylasemia should prevent patients from being subjected to superflous investigation and meaningless treatment.

Amylases↗
PubMed1979

[Macro-creatine kinase; circulating immunoglobulin enzyme complexes as cause of elevated CK-activities (author's transl)].

We report a case of a woman (58 years old) with persistent and elevated CK activities and without corresponding clinical signs. For seven months CK-B activity was determined above normal by an inhibition test. By exclusion chromatography, ion-exchange chromatography, electrophoresis of CK isoenzymes and immunological methods we were able to explain this phenomenon as Macro CK consisting of immunoglobulin G bound CK-BB.

Chromatography, Gel↗
PubMed1979

Serum creatine kinase BB linked to immunoglobulin G.

We describe an atypical form of creatine kinase in the serum of a woman after myocardial infarction. Electrophoresis on agarose gel showed a single fraction between CK-MM and CK-MB isoenzymes. After ion-exchange chromatography on DEAE-Sephadex A-50 we isolated the atypical CK and CK-BB as detected by electrophoresis of the eluted fractions. Results of our immunological investigations and exclusion chromatography clearly demonstrate that the atypical CK consists of complexes with high molecular masses formed by CK-BB isoenzyme and immunoglobulin G. The clinical significance, if any, of this Macro CK has yet to be determined.

Brain↗
PubMed1979

[Properties and significance of macro-creatine kinases (author's transl)].

Sera from seven-patients with an unusual high ratio of creatine kinase-MB versus total creatine kinase, as found in the immunoinhibition test, were investigated. In every case, the electrophoretic separation of the isoenzymes showed a slow moving band, and exclusion chromatography showed the presence of macro-creatine kinase. Further chromatographic, electrophoretic and immunological investigations indicated that the macro-creatine kinases in six cases are complexes of creatine kinase-BB linked to immunoglobulin G.

Aged↗
PubMed1978

[Familial coincidence of hypertrophic cardiomyopathies and thyroxine-binding globulin deficiency (athyropexinemia) (author's transl)].

A twenty-five year old man was found to have simultaneous total deficiency of thyroxine-binding globulin ("thyropexin") and hereditary hypertrophic obstructive cardiomyopathy (HOCM). The thyroxine-binding capacity (RT3U), thyroid hormone levels, PB127I, PB131I and TBG (RIA) in serum were very low and TBG cap was zero. Trapping of radioiodine in the thyroid was enhanced. Clinically, the patient appeared euthyroid. The case seems to be similar to another one described earlier by Ingbar. An investigation of the family showed that in one uncle and two nephews of the patient thyropexin was absent whilst the mother, one sister and one female cousin had partial thyropexin deficiencies. One of these nephews also suffers from asymmetric septal hypertrophy (ASH), the mother of the propositus has a non-obstructive hypertrophic cardiomyopathy (HCM).

Adult↗
PubMed1976

[Anaerobic serum ultrafiltration--a new method for determination of protein-binding rates of drugs under physiological conditions (author's transl)].

Only the free and not the protein-bound fraction of a drug shows pharmacologic activity. Therefore the rates of drug-binding to serum proteins are of great importance for clinical and pharmacological purposes. A basis prerequisite for accurate measurements are experimental designs giving the possibility of keeping the most important factors influencing the protein-binding rate within physiological ranges. In vivo these factors are, among others, the concentration of albumin, the absorption of different exogenous and endogenous substances to albumin, the type and the amount of ions present, the total ionic strength, the pH-value and hence the pCO2 as well as the temperature. An experimental set-up was described giving the possibility of keeping all these factors absolutely constant under in vivo conditions by means of a newly developed and simply to handle ultrafiltration device. From withdrawing the blood sample from the vein to the complete separation of the protein-bound fraction the blood sample can be processed under strictly anaerobic conditions (to prevent loss of CO2!). Compared to common methods generally used for the determination of protein-binding rates, such as equilibrium dialysis, column chromatography and ultracentrifugation, this new procedure saves a considerable amount of time. Within 1 h up to 8 samples can be processed in a single device. Besides short filtration times there is no need for any additional sample preparation such as buffering or adding antibacterial substances, etc.

Blood Proteins↗