Serum levels of creatine kinase (CK) isoenzymes (MM, MB, and BB) were measured by sensitive enzyme immunoassay (EIA) methods in 50 patients with Duchenne muscular dystrophy (DMD) and in 39 controls. MM, MB, and BB levels in DMD patients were higher than in controls, and these three levels decreased with advancing age of DMD patients. Serum MB levels showed a good correlation with serum levels of carbonic anhydrase III (CA-III), but correlated poorly with electrocardiographic findings, suggesting that the main origin of serum MB in DMD is skeletal muscle rather than cardiac muscle.

Enzymatic determinations in cerebrospinal fluid (CSF) of aspartate aminotransferase (AST), lactic dehydrogenase (LDH), gammaglutamyl transpeptidase (GGT), creatine phosphokinase (CPK) and creatine kinase BB (CK-BB) were performed in 16 patients with aseptic meningitis (AM), in 25 children with bacterial meningitis (BM) and in 15 patients with meningism. The activity of AST and GGT was significantly higher in patients with BM on admission compared with those with AM and meningism (p < 0.05 and p < 0.005, respectively) and decreased with therapy. The highest concentration of AST and LDH appeared in patients with poor outcome as well as in those with ventriculomegaly on neurosonography (p < 0.05). The concentration of CK-BB increased in all patient groups on admission and remained higher on termination of therapy. The present study confirms the high activity of AST and GGT in BM patients in the CSF whereas the increased activity of AST and LDH reflects the extent of brain injury. Nevertheless, the prognosis for individual patients cannot be established on the basis of enzyme activity alone, but depends on several factors.

Considering the important role of the phosphocreatine energy shuttle in contractile function of the heart we decided to study the different components of this shuttle in STZ-induced diabetic rat heart with a known diabetic related cardiomyopathy. Diabetes produced a gradual decline in total CK activity, reaching a maximum of 35-40% decrease after 4 weeks of diabetes, in both atria and ventricles. All of the CK isoenzymes including the mitochondrial CK (CKm) were reduced but to a different extent in these two tissues. The percentage reduction in diabetic ventricles was BB greater than MB greater than CKm greater than MM and in atria was CKm greater than BB greater than MB greater than MM. A major difference between atrium and ventricle was the greater loss of CKm in diabetic atria than diabetic ventricle (75% in atria vs 32% in ventricle). The B subunit seemed to be the one that was affected the most followed by CKm isoenzyme and then the M subunit. The bound myofibrillar CK isoenzyme, expressed as units of activity/mg of myofibrillar protein, was not affected by 4 weeks of diabetes. The high energy phosphates were also reduced in diabetic heart with a greater reduction in phosphocreatine (43-45%) and a smaller change in ATP (27%). Mitochondrial oxidative phosphorylation with alpha-ketoglutarate was reduced (55%) in diabetic heart, whereas, there was no difference when succinate was used as substrate. These changes were reversible by 4 weeks of insulin treatment. The loss of CKm, phosphocreatine and the reduction in mitochondrial oxidative phosphorylation, could result in an inefficient phosphocreatine energy shuttle which could contribute to the cardiac functional defects associated with diabetes.

Because of its chemical structure, risedronate was thought to form a complex with divalent cations, e.g., Ca(2+), and to be likely to show changes in the efficiency of absorbance from the gastrointestinal tract according to the presence of food. Therefore, we conducted a crossover study using healthy Japanese adults to examine the effects of food intake on absorption after the oral administration of risedronate and to choose the best timing of regimen for risedronate. Using single doses of 5 mg risedronate, the following four dose times were investigated: (a) in the morning under a fasting condition without breakfast; (b) 30 min before breakfast; (c) 30 min after breakfast; and (d) 3 h after breakfast. The results showed that the C(max) and AUC(0-24) of the plasma risedronate concentrations and its cumulative urinary excretions decreased in the following order: fasting without breakfast>>)30 min before breakfast>>)3 h after breakfast>>)30 min after breakfast. In other words, it was demonstrated that the absorption of risedronate decreases due to the effects of food. Several adverse events, whose causality with risedronate was unknown or possibly related, were observed, including headaches, diarrhea, increased CK-BB, and an increased urinary Beta(2)-microglobulin excretion rate, but none of these events was clinically significant, and none differed in frequency or severity from the events after a single oral administration. In consideration of the optimal practical timings required to administer risedronate for Japanese patients, therefore, it was found that ingesting the drug immediately after waking up in the morning, when the stomach is empty, was optimal, and that it was necessary to refrain from eating and drinking for at least 30 min after drug ingestion. Therefore, we determined that the optimal time for risedronate to be administered in Japanese patients is 30 min before breakfast.

BACKGROUND

beta-blocker (BB) use reduces infarct size in spontaneously occurring nonreperfused infarcts but probably does not change infarct size in patients treated with reperfusion therapy. A recent observational study suggested that BB use concurrent with percutaneous coronary intervention (PCI) decreased the risk of creatine kinase (CK)-MB elevation. The cogency of such a conclusion is dependent on the ability to risk-adjust for the multiple differences in patients treated with and without BBs.

RESULTS

Using propensity score and multivariate regression analyses, 6200 consecutive patients were analyzed to assess the relationship between BB use before PCI and per protocol-measured CK and CK-MB rise. There were several highly significant (P<0.001) differences between patients with and without BB treatment (eg, age, prior infarction, unstable angina). Maximum CK and CK-MB levels were higher in patients taking BBs (CK median, 95 U [interquartile range: 61, 175]; CK-MB, 3 U [2, 5]) than in patients not taking BBs (CK, 91 U [60, 157]; CK-MB, 3 U [2, 4]) (P=0.011 and P=0.021 for CK and CK-MB, respectively). After adjustment for significant differences in baseline characteristics there was no difference in either maximum CK rise (P=0.21) or maximum CK-MB rise (P=0.99).

CONCLUSIONS

The results of this large observation study do not support the contention that BB use before PCI decreases myocardial injury.

OBJECTIVE

The aim was to investigate the redistribution of isoenzymes, clinically important markers of myocardial necrosis, in the diabetic heart and compare it with that investigated in other types of cardiomyopathies.

METHODS

Myocardial isoenzyme activity of creatine kinase (CK), lactate dehydrogenase (LD) and aspartate aminotransferase (AST) was measured in animals with diabetic, hereditary, and catecholamine cardiomyopathies.

METHODS

Diabetic rats (4 and 8 weeks after intravenous streptozotocin, n = 21), Bio 14.6 hamsters (30, 90, 160 and 240 days old, n = 29), and rats injected with isoprenaline (0.25, 0.5 and 1.0 mg.kg-1.d-1 for 3 weeks, n = 20) were used. Controls were age matched intact animals (n = 8-11).

RESULTS

Total CK and CK MM activity decreased in all groups. CK MB and BB decreased by 62 and 52% in diabetic rats, but increased by 40 and 33% in Bio hamsters and by 9 and 96% in isoprenaline treated rats. Thus the CK-B subunit decreased by 61% in diabetics and increased by 33 and 38% in Bio and isoprenaline groups, while the CK-M subunit decreased in all groups. Mitochondrial CK decreased in diabetic and isoprenaline groups. Total LD activity increased in diabetics and decreased in Bio. LD-H subunit increased by 21% in diabetics and decreased by 19 and 18% in Bio and isoprenaline groups. Accordingly the proportion of LD-M subunit, an index of anaerobic metabolism, decreased in diabetics and increased in Bio and isoprenaline groups. Changes in CK-M and CK-B subunits and the LD-M proportion in diabetic heart were normalised by insulin. Total AST activity decreased in diabetics because of the reduction in mitochondrial AST.

CONCLUSIONS

Increased LD-M proportion and CK-B observed in Bio and isoprenaline groups may be a metabolic "compensation" to decreased myocardial perfusion and substrate. Decreased LD-M proportion and CK-B in the diabetic heart was insulin dependent and may indicate either lack of "compensation" to myocardial ischaemia or absence of ischaemia per se. Decreased myocardial CK and CK MB activity possibly causes underestimation of enzymatically assessed infarct size in the diabetic heart.

Determination of the creatine kinase isoenzyme pattern in 62 biopsy samples obtained from patients with neuromuscular disease revealed changes mainly in Duchenne muscular dystrophy. The BB isoenzyme was detected in 10 out of 17 cases with Duchenne muscular dystrophy and the relative amount of MB+BB isoenzyme was significantly increased in this group (P less than 0.005). In serum the MB isoenzyme was detected in all 28 cases with progressive muscular dystrophy and frequently also in other neuromuscular diseases. Among 152 control samples the MB isoenzyme was detected only in 2 cases. It is suggested that the finding of MB isoenzyme in the serum with normal or only slightly elevated total CK activity may be a further proof of neuromuscular disorder, but the finding is not specific for any particular disease.

This study investigated the safety and neuroprotective effect of moderate hypothermia in children with severe traumatic brain injury (TBI). Twenty-two children suffering from TBI were randomly divided into groups treated with moderate hypothermia (intracranial temperature of 34.5 +/- 0.2 degrees C, maintained for 72 h, n = 12) or normothermia (intracranial temperature of 38.0 +/- 0.5, n = 10). The cerebrospinal fluid levels of neuron-specific enolase (NSE), S-100, brain-specific creatine kinase (CK-BB), and intracranial pressure (ICP) levels were used to assess the protective effects. The variations in pH and electrolyte balance were also examined. The results indicated that the peak ICP level in the normothermia group (26.30 +/- 1.08 mm Hg) was reached 48 h after TBI. The ICP level in the moderate hypothermia group was lower than in the control group at every time point examined (p < 0.01). Furthermore, at 24, 48, and 72 h, the NSE, S-100, and CK-BB levels in the moderate hypothermia group were also lower than that of the normothermia group (p < 0.01). In the moderate hypothermia group, the pH and electrolyte balance at the end of the monitoring period were normal, but the heart rates were lower (p < 0.05). There were a total of three deaths (13.6%) in this study: one in the moderate hypothermia group (8.3%) and two in the normothermia group (20%). In conclusion, moderate hypothermia provided neuronal protection for children with severe TBI, and maintaining the intracranial temperature at 34.5 degrees C for 72 h was safe in this clinical setting.

In previous conventional reports sperm and seminal plasma were not well separated and therefore it was highly probable that isoform (CK-BB) of seminal plasma was determined together with that of sperm. The authors developed a method to purify sperm specimen free from seminal plasma. Human sperm was purified by means of the continuous-step density gradient centrifugation with an inner column and the subsequent modified swim-up procedure. CK isoforms in the purified sperm and the seminal plasma were analyzed by ion exchange chromatography and electrophoresis. The purified sperm contained mitochondrial CK-MiMi as well as cytosolic CK, of which isoform was almost occupied by CK-MM but CK-BB was not detected. On the other hand, CK isoform in the seminal plasma was detected as CK-BB alone. CK activity in human sperm and seminal plasma were 2.0 +/- 0.7 x 10(-6) IU/10(6) sperm and 661 +/- 360 IU/L, respectively. CK activity in the seminal plasma gave no correlation with the semen parameters.

Biochemical changes in the creatine kinase isoenzyme compositions in single muscle fibres of different types in rats were induced by endurance running training. Single muscle fibres were dissected from the soleus and extensor digitorum longus muscles of Wistar-strain male rats trained on a motor-driven treadmill for 16 weeks. Each fibre was typed histochemically (SO, slow-twitch oxidative; FOG, fast-twitch oxidative glycolytic; FG, fast-twitch glycolytic), and the activities of total creatine kinase and its four isoenzymes (CK-MM, -MB, -BB, and mitochondrial creatine kinase) were measured. The endurance training did not affect the total creatine kinase activity, but resulted in significantly increased activities of CK-MB and CK-BB in SO and FOG fibres, and the mitochondrial enzyme activity in FOG and FG fibres. Endurance training induced biochemical changes in the isoenzyme compositions, specifically in FOG fibres. These results suggest that changes in creatine kinase isoenzymes with endurance training reflect changes in the energy metabolism in the different muscle fibres, supporting the hypothesis that the different isoenzymes play different roles in energy transduction.

In the chicken, a high degree of heterogeneity at the protein level has been reported for the creatine kinase-type B (B-CK). Here we show that the two B-CK isoproteins, Ba- and Bb-CK, are encoded by two mRNAs, which are derived from a single copy gene by a stochastic alternative splicing mechanism. The transcription of the single hnRNA is directed by a complex promoter region containing a stretch of sequences which is highly conserved among all the B-CK genes known to date. This stretch encompasses a putative binding site for the TA-rich DNA-binding protein (Hobson, G. M., Mitchell, M. T., Molloy, G. R., and Pearson, M. L. (1988) Nucleic Acids Res. 16, 8925-8944) which is located in the distal part of the promoter region, while the proximal portion containing the TATA-box used in vivo is not conserved between chicken and mammals. The two isoproteins arising from this gene contain distinct N-terminal portions. According to comparative analysis, Bb-CK is the form which is homologous to the mammalian B-CKs, whereas Ba-CK shows some sequence features unique among all other vertebrate cytosolic creatine kinases characterized so far.

Postnatally the rat brain synthesizes catalytic forms of muscle type (MM) and heart type (MB) creatine kinase (CK), besides the supposedly sole type vertebrate brain-specific (BB) CK. We intended to demonstrate that in Rhode Island chicken brain, cytosolic (c) CK isoenzymatic transitions. (for example BB-CK is followed by the appearance of MB-CK and MM-CK during muscle differentiation), can also occur during development and aging. Cytosolic post 125000 x g, mitochondrial CK-free, brain samples were obtained for zone electrophoresis separation and identification of catalytically active cCK isoforms. BB-CK was never found during chicken brain ontogeny. Against the accepted view, an opposite isoenzyme transition pattern from MM through BB-CK was found in the chicken embryonic brain from the very early stages of development up to day 2 post-hatching. At very early stages of chicken brain ontogeny constitutive MM- and MB-CK isoenzymes were present before the advent of creatine. It seems to be that typical and atypical brain MM- and MB-CK could be working as ATPases in the absence of creatine before embryonic stage 28 (day 5.5) and/or such CK isoforms may begin to form part of the slow component b in developing early neurons and later in the nuclei of glial cells to be used by the CK/phosphocreatine (PC) system as the neural tissues mature. The post-hatching transition pattern showed simultaneous expression of more than one CK isoenzyme within the same neural sample as in post-natal rat brain, presumably due to regional differential transphosphorylation requirements. Strain-dependent enzymatic specific activities have been reported in several species. Since equivalent values of brain CK specific activity were obtained previously from the embryonic plateau phase of CK activity during White Leghorn development, and those from Rhode Island brain neurons cultured 11 days, we compared if, in vivo, a similar brain CK specific activity pattern was physiologically equivalent during Rhode Island and White Leghorn chicken ontogeny. We found quantitatively different strain-specific CK specific activity patterns during this period. Rhode Island brain CK activity values were approximately 4.5-fold those of White Leghorn ones. This indicates that production of energy from anaerobic metabolism and transphosphorylation by the CK/PC system to synthesize ATP more efficiently is strain-specific. In Rhode Islands, there was an age-dependent increase of CK specific activity, mostly in older animals (440% above the value found during the embryonic plateau), when the Krebs cycle and glycolysis lose capacity. During adult life and aging, under physiological conditions, the three CK isoenzymes may participate in diverse functions of the different cell compartments of brain glia and neurons with regard to their high and fluctuating energy demands that are not completely covered by anaerobic and aerobic glycolisis.

In a series of 93 emergency patients, 58 were classified as concussions on a clinical basis. Thirteen of the patients with concussion had increased levels of creatine kinase isoenzyme BB (CK-BB) in their cerebrospinal fluid (CSF). We performed a prospective, follow-up investigation comparing 10 patients with a CK-BB increase and 10 patients without a CK-BB increase after concussion. Within 24 hours, at 6 months and 3 years after concussion, each patient was subject to a special interview to obtain pre-concussional baseline data and post-concussional follow-up data concerning their complaints and capacity for daily activities. We found a definite change towards increasing disability in 8 of the 10 patients with a raised CK-BB, and in only 1 of the 10 patients with normal levels of CK-BB. A careful neuropsychological examination confirmed inferior performance in tests especially sensitive to brain injury in patients with a CK-BB increase. Our results suggest that increased levels of CK-BB after concussion signify a more severe injury which is not found in the clinical examination during the first days after the accident, and that these patients are a high-risk group for the development of post-concussional problems and symptoms.

Previous two-site immunometric assays for creatine kinase (CK; EC 2.7.3.2) MB isoenzyme have been based on formation of a "sandwich" complex involving CK-MB and antibodies that recognize the CK-MM and the CK-BB isoenzymes. Single-incubation model assays of CK-MB with these antibodies were susceptible to interferences by CK-MM and CK-BB. We produced two anti-CK-MB monoclonal antibodies and studied their suitability for two-site assays. Both antibodies were compatible with anti-CK-MM and anti-CK-BB, but not with each other. Using anti-CK-MB as the tracer antibody eliminated the interference by both CK-MM and CK-BB. Labeling anti-CK-MB with acridinium ester and immobilizing anti-CK-BB on paramagnetic particles, we developed a rapid and highly sensitive chemiluminescent/magnetic separation CK-MB assay. As little as 1 microgram of CK-MB per liter was detectable after 10- or 30-min incubation at room temperature, and the standard curve was linear up to 400 micrograms/L. Results for serum samples by the new assay correlated well (r = 0.94) with those by Corning electrophoretic and the Hybritech Tandem-E immunoenzymometric CK-MB methods. Sera containing macro CK-1 or high concentrations of CK-MM and CK-BB did not interfere. The combined advantages of a more-specific antibody, paramagnetic solid phase, and chemiluminescent label endow this two-site CK-MB assay with performance characteristics and ease of use superior to those of previous assays.

A method for the purification of brain-type creatine kinase (B-CK) from several tissues of the chicken, e.g., brain, retina, gizzard and heart was developed involving (1) an affinity chromatography step on Sepharose Blue from which B-CK was specifically eluted by ADP and (2) a subsequent anion exchange chromatography step on a fast protein liquid chromatography Mono-Q column. Two distinct peaks with B-CK activity, both purified to greater than or equal to 99% homogeneity and displaying specific enzyme activities of 300-400 mumol CP/min/mg 1t pH 7.0 and 25 degrees C, were eluted by a salt gradient at a plateau of 150 mmol/l NaCl. The ratio of the two B-CK peaks varied in a tissue-dependent manner, indicating that in chicken the dimerization of native BB-CK from the two major B-CK subunit species is tissue-specific and nonrandom in neural tissues. The fast, efficient and convenient method for the purification of B-CK at small or large scale, operating at yields of 50-70%, makes the purification of this rather labile enzyme from small amounts of tissues possible and greatly facilitates the subsequent characterization of both major and minor dimeric BB-CK subspecies present in these different tissues.

Serial measurements of serum creatine kinase isoenzymes were done from birth to 15 days of age in healthy premature infants, infants with perinatal or neonatal asphyxia and infants without asphyxia but with miscellaneous problems. Serum brain-specific fraction of creatine kinase (CK-BB) activity was higher in cord than in maternal serum (P < 0.01). In healthy infants, the serum activity of heart- and muscle-specific fractions of creatine kinase increased after birth, reached a plateau between 12 and 48 hr, and then declined, whereas the serum CK-BB decreased rapidly after birth and remained stable between 6 hr and 15 days. Compared to controls, infants with severe asphyxia and neurologic damage had a significant rise in serum CK-BB (P < 0.001). When the peak CK-BB level exceeded 35 IU/liter the mortality was high (83%). The increase in CK-BB was not observed in infants who received pentobarbital shortly after the episode of asphyxia. Diseases of the lung, kidneys, gastrointestinal tract, and abruptio placentae were not associated with increases of serum creatine kinase isoenzymes.

Most of the creatine kinase (CK:EC 2.7.3.2) activity is present in skeletal muscle and myocardium. However, some activity in other organs has been reported. Theoretically, the destruction of organs that contain CK activity should release soluble enzymes into the general circulation. The effects of various destructive processes on serum creatine kinase isoenzymes in 70 patients were studied. The MB isoenzyme was demonstrated in 17 of 70 patients (24%), and the BB isoenzyme in 12 of 70 patients (17%). MB activity ranged from 3 to 12 U/l, or 0.7% to 10% of the total CK activity. BB activity ranged from 2.5 to 21 U/l, or 0.4% to 18.6% of the total CK activity. Interpretation of the results of CK isoenzyme studies should be made very carefully, especially if laboratories use CK-MB methods that measure MB and BB in combination. The diagnosis of myocardial injury should never be based solely on the presence of creatine kinase MB isoenzyme in the serum, but should be supported by additional clinical and laboratory data.

Hippocalcin (Hpca) is a Ca(2+)-binding protein that is expressed in neurons and contributes to neuronal plasticity. We purified a 48 kDa Hpca-associated protein from rat brain and identified it to be the creatine kinase B (CKB) subunit, which constitutes brain-type creatine kinase (BB-CK). Hpca specifically bound to CKB in a Ca(2+)-dependent manner, but not to the muscle-type creatine kinase M subunit. The N-terminal region of Hpca was required for binding to CKB. Hpca mediated Ca(2+)-dependent partial translocation of CKB (approximately 10-15% of total creatine kinase activity) to membranes. N-myristoylation of Hpca was critical for membrane translocation, but not for binding to CKB. In cultured hippocampal neurons, ionomycin treatment led to colocalization of Hpca and CKB adjacent to the plasma membrane. These results indicate that Hpca associates with BB-CK and that together they translocate to membrane compartments in a Ca(2+)-dependent manner.

Male Sprague-Dawley rats administered with an acute sublethal dose of carbofuran (1.5 mg/kg, s.c.) developed the signs of peak hypercholinergic activity during 30-60 min. At this time, in hemidiaphragm muscle, a significant decrease in ATP (28%) and phosphocreatine (PC) (29%) occurred without concurrent change in AMP and creatine (CR). A significant decrease in the levels of total adenine nucleotides (ATP + ADP + AMP) (20%) and total creatine compounds (PC + CR) (17%) was evident. The decline in the corresponding ratios of ATP/ADP (26%), ATP/AMP (39%), and PC/CR (20%) was therefore suggestive of greater utilization of ATP and PC in response to their increased demand for high-frequency muscle fasciculations. The energy charge = ATP + 1/2 ADP/(ATP + ADP + AMP), an index of high-energy phosphate adequacy in hemidiaphragm, remained unchanged. A significant (p less than 0.01) increase in serum magnesium with no concurrent change in calcium was also evident. The observed higher activity (152%) of total CK (EC 2.7.3.2) in the serum induced by carbofuran was possibly a reflection of more than a twofold increase in CK-BB isoenzyme (CK-1) and 141% increase in CK-MM isoenzyme (CK-3), which also strengthens our findings of enhanced synthesis of ATP and PC. Increased levels of CK-MM isoenzyme in the brain (253%) and hemidiaphragm (195%); and depletion of CK-BB isoenzyme in the hemidiaphragm (0%), heart (42%), and brain (77%), and of CK-MB isoenzyme (CK-2) in the brain (4%) and hemidiaphragm (14%), appeared to be the major contributory factors leading to enhanced serum CK activity.

The distribution of phosphoglycerate mutase (EC 5.4.2.1, PGM), 2,3-bisphosphoglycerate phosphatase (EC 3.1.3.13, BPGP) and creatine kinase (EC 2.7.3.2, CK) activity and isoenzymes in various regions of adult human brain and in brain tumours (astrocytomas, anaplastic astrocytomas, glioblastomas and meningiomas) has been determined using electrophoresis. PGM and cytosolic CK exist in mammalian tissues as three isoenzymes that result from the homodimeric and heterodimeric combinations of two subunits [types M (muscle) and B (brain)] coded by separated genes. In addition, a dimeric form and an octameric form of mitochondrial CK exist in mammals. Type BB-PGM was the major PGM isoenzyme found in normal brain, although type MB-PGM and type MM-PGM were also detected. All brain tumours possessed lower PGM activity than normal brain, and meningiomas showed higher BPGP activity. In astrocytic tumours, the proportion of type MB- and type MM-PGM decreased, and in meningiomas these isoenzymes were not detected. Type BB-CK and mitochondrial CK were the only CK isoenzymes detected in normal brain. Astrocytomas possessed lower CK activity than anaplastic astrocytomas and glioblastomas and, in addition, tended to possess lower CK content than normal brain. No qualitative changes of the normal CK isoenzyme pattern were observed in the tumours.

Creatine kinase (CK; EC 2.7.3.2) isoenzyme BB extracted from brains of rats reportedly undergoes modification at 37 degrees C, leaving an electrophoretic variant that accounts for most of the residual CK activity. This variant, called CK-BB', migrates on electrophoresis similarly to creatine kinase isoenzyme MB. Using electrophoresis and immunoinhibition with antiserum to creatine kinase isoenzyme MM, we found CK-BB to be the only identifiable cytoplasmic isoenzyme in surgical samples from human brain and intestine. In contrast, we found that some samples of brain obtained at autopsy contain CK-BB'. We also found that CK-BB extracted from human brain was converted to CK-BB' upon incubation in serum or plasma at 37 degrees C. We found a similar development of CK-BB' in incubation mixtures of serum or plasma containing CK-BB obtained from surgical samples of human intestine. The development of CK-BB' during infarction of the gastrointestinal system may thus be a source of false-positive CK-MB in the laboratory verification of myocardial infarction when electrophoresis is used as the only method to identify CK isoenzymes.

The brain type (BB) isoenzyme of creatine kinase (CK) is a very sensitive marker of estrogen action in rat uterus and in experimental mammary tumors. In order to detect useful markers for estrogen dependent human breast cancer cell proliferation we measured CK levels and isoenzyme composition in the CG5 cells, an estrogen supersensitive variant of the MCF-7 human breast cancer cell line. Under basal conditions, CK-BB accounted for 10%-15% of total enzymatic activity, while the MM isoenzyme represented the overwhelming component. In cells cultured in the presence of 5% charcoal-treated fetal calf serum, physiological concentrations (0.1-1 nM) of estradiol increased CK-BB levels in a dose- and time-related fashion. The effect was specific for estrogens and was prevented by antiestrogens. Our results show that CK-BB is estrogen regulated in the CG5 cells and suggest a possible role for this enzyme as an additional marker of the hormonal responsiveness of breast cancer.

Creatine kinase BB (CK-BB) isoenzyme was measured by radioimmunoassay in serum and in cerebrospinal fluid from 61 patients with various neurological disorders. Statistically significant elevations of CK-BB isoenzyme in the serum were observed in patients with acute cerebrovascular accidents and in those with seizures and a prolonged alteration in level of consciousness. Statistically significant elevations of CK-BB isoenzyme in the cerebrospinal fluid were also found in patients who had suffered acute cerebrovascular accidents. Some patients with central nervous system infections, acute demyelinating disease, certain drug overdoses, head trauma, and complex migraine also had elevations of serum and CSF CK-BB isoenzyme. In 2 patients with elevations of CK-BB isoenzyme, the elevations in serum occurred later than those detected in the cerebrospinal fluid. If CK-BB elevations determined by radioimmunoassay can be demonstrated to be quantitatively related to the extent of brain damage, then these determinations in conjunction with experimental animal models and newer radiological techniques should allow evaluation, in an objective and precise manner, of measures designed to decrease that damage.