PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Creatine”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed1998

31P NMR studies of creatine kinase flux in M-creatine kinase-deficient mouse heart.

Hearts of wild-type and cytosolic muscle creatine kinase (M-CK)-knockout mice were perfused with Krebs-Henseleit buffer containing 10 mM glucose and 5 mM pyruvate and studied during pacing at 400 and 600 beats/min and during K+ arrest. Phosphocreatine (PCr) and ATP concentrations in M-CK-deficient hearts were not significantly different from those in wild-type hearts. With the use of 31P NMR saturation transfer, the flux mediated predominantly by mitochondrial creatine kinase (Mi-CK) was clearly detected in M-CK-deficient hearts. Mi-CK flux was 4.8 +/- 0.6 and 4.5 +/- 0.6 mM/s during pacing at 400 and 600 beats/min, respectively, and was 3. 5 +/- 0.4 mM/s during cardiac arrest. In control hearts total CK flux was 7.8 +/- 1.1 and 6.6 +/- 1.3 mM/s during pacing at 400 and 600 beats/min, respectively, and decreased to 3.8 +/- 0.5 mM/s during arrest. It is suggested that the relative contribution of Mi-CK to the total NMR-measured CK flux in the wild-type heart is higher than that of the homodimeric M-CK isoform (MM-CK).

Adenosine Diphosphate↗
PubMed2004

Use of phosphocreatine kinetics to determine the influence of creatine on muscle mitochondrial respiration: an in vivo 31P-MRS study of oral creatine ingestion.

Recent human isolated muscle fiber studies suggest that phosphocreatine (PCr) and creatine (Cr) concentrations play a role in the regulation of mitochondrial respiration rate. To determine whether similar regulatory mechanisms are present in vivo, this study examined the relationship between skeletal muscle mitochondrial respiration rate and end-exercise PCr, Cr, PCr-to-Cr ratio (PCr/Cr), ADP, and pH by using (31)P-magnetic resonance spectroscopy in 16 men and women (36.9 +/- 4.6 yr). The initial PCr resynthesis rate and time constant (T(c)) were used as indicators of mitochondrial respiration after brief (10-12 s) and exhaustive (1-4 min) dynamic knee extension exercise performed in placebo and creatine-supplemented conditions. The results show that the initial PCr resynthesis rate has a strong relationship with end-exercise PCr, Cr, and PCr/Cr (r > 0.80, P < 0.001), a moderate relationship with end-exercise ADP (r = 0.77, P < 0.001), and no relationship with end-exercise pH (r = -0.14, P = 0.34). The PCr T(c) was not as strongly related to PCr, Cr, PCr/Cr, and ADP (r < 0.77, P < 0.001-0.18) and was significantly influenced by end-exercise pH (r = -0.43, P < 0.01). These findings suggest that end-exercise PCr and Cr should be taken into consideration when PCr recovery kinetics is used as an indicator of mitochondrial respiration and that the initial PCr resynthesis rate is a more reliable indicator of mitochondrial respiration compared with the PCr T(c).

Adenosine Diphosphate↗
PubMed1995

Measurement of serum troponin T, creatine kinase MB isoenzyme, and total creatine kinase following arduous physical training.

We have compared measurement of cardiac troponin T by enzyme linked immunosorbent assay with creatine kinase MB isoenzyme (CK-MB) concentration measurement in 219 Royal Marine commandos with no evidence of cardiovascular disease who have elevated creatine kinase (CK) produced by arduous physical training. CK was elevated up to 22.6 times and CK-MB mass up to 6.6 times the upper reference limit. Only two commandos had detectable cardiac troponin T, with neither exceeding the upper reference limit of 0.2 micrograms/L. At decision thresholds optimized for diagnosis of acute myocardial infarction in previous published work, 58.3% of the total CK activity, 13.8% of the CK-MB concentration/CK activity ratio and 1.6% of CK-MB concentration measurements showed elevated values but no elevations in cardiac troponin T occurred. Cardiac troponin T is currently the investigation of choice for the differential diagnosis of patients with an elevated CK due to skeletal muscle trauma to exclude myocardial damage.

Aspartate Aminotransferases↗
PubMed1989

Immunocytochemical localization of creatine kinase M in canine myocardial cells: most creatine kinase M is distributed in the A-band.

The localization of creatine kinase (CK) M in canine myocardium was immunocytochemically studied by a direct immunoperoxidase method. Specific antiserum against CK-M was produced in rabbits immunized with canine CK-MM. An anti-CK-M Fab'-horseradish peroxidase conjugate was prepared by the maleimide method. Frozen sections prepared from fixed canine myocardium were stained with the conjugate and observed by light and electron microscopy. In light microscopy of longitudinal sections, CK-M showed a cross-striated pattern consisting of distinct broad and narrow brown bands. Immunoelectron microscopy revealed that the regions of the broad and narrow brown bands corresponded to the A-band and the Z-line, respectively. Most CK-M in the A-band was associated with the thick fibers, and a small amount of CK-M was found in the M-line. These findings suggest that ATP regeneration from the ADP produced by myosin ATPase is related to the participation of this CK associated with the thick fibers rather than that of the M-line-bound CK. Creatine kinase M was also found in the sarcolemmal membrane, the membranes of the sarcoplasmic reticulum, and the mitochondrial outer and inner membranes. This report provides new information for understanding the physiological role of the phosphorylcreatine shuttle in the myocardial energy transport system.

Animals↗
PubMed2000

Brain creatine depletion: guanidinoacetate methyltransferase deficiency (improving with creatine supplementation).

The authors describe an Italian child with guanidinoacetate methyltransferase deficiency, neurologic regression, movement disorders, and epilepsy during the first year of life. Brain MRI showed pallidal and periaqueductal alterations. In vivo 1H-MRS showed brain creatine depletion. The assessment of guanidinoacetic acid concentration in biologic fluids confirmed the diagnosis. Clinical, biochemical, and neuroradiologic improvement followed creatine supplementation.

Brain Chemistry↗
PubMed1979

Influence of indicating enzyme reaction on apparent creatine kinase activity creatine kinase in serum, VII.

Comparison of the indicative systems yeast glucose-6-phosphate dehydrogenase/NADP+, leuconostoc glucose-6-phosphate dehydrogenase/NADP+ and leuconostoc glucose-6-phosphate dehydrogenase/NAD+ showed excellent correlation and no differences in apparent creatine kinase activity with the two methods using NADP+. By using NAD+ with the leuconostoc enzyme enzyme relative recovery of apparent creatine kinase activity is lower due to interference of other serum constituents. The mean value of the relative differences versus methods using NADP+ was 5.8% in our experiments.

Creatine Kinase↗
PubMed1983

Evaluation of the optimized bioluminescent assay for the determination of total creatine kinase and creatine kinase MB activities.

A very sensitive, optimized bioluminescent assay for certain kinase and creatine kinase MB activities is tested. We evaluated reagent blanks, sensitivity, precision and compared the results with those of the spectrophotometric immunoinhibition test. The main advantage of the new method is a detection limit of less than 1 U/l which, together with a high precision (s = 0.1 at detection limit), allows determinations of the creatine kinase MB activity even in normal sera in about 20 minutes. A disadvantage of the manual procedure is that it may be necessary to include up to five pipetting steps.

Creatine Kinase↗
PubMed1991

Elevated creatine phosphokinase and creatine phosphokinase-MB in acute laryngitis.

Elevated creatine phosphokinase (684 mU/ml) and creatine phosphokinase-MB (3.5%, 23.9 mU/ml) were observed in a 66 year old female with acute laryngitis. The patient had received L-thyroxine because of hypothyroidism for 10 years and her T3 and TSH levels were normal. Acute myocardial infarction was denied by repeated EKG findings. The mechanisms of the enzyme abnormality were discussed.

Aged↗
PubMed2003

Creatine monohydrate supplemented in swine finishing diets and fresh pork quality: III. Evaluating the cumulative effect of creatine monohydrate and alpha-lipoic acid.

The objective of this study was to evaluate short-duration supplementation of alpha-lipoic acid (ALA) and creatine monohydrate (CMH) to improve fresh pork quality. Forty-eight commercial hybrid barrows were blocked by BW and randomly allotted to one of four treatments: 1) no CMH or ALA; 2) supplementation of 24 g of CMH(-1) x pig(-1) x d(-1); 3) supplementation of 600 mg ALA(-1) x pig(-1) x d(-1); or 4) combined CMH and ALA supplements. Twelve pigs per treatment were individually penned with ad libitum access to water and a finishing diet. Treatments were hand-fed to individual pigs daily (divided into three equal doses) for 5 d before slaughter at 113 kg BW in two separate groups of 24 pigs each. Intramuscular pH was recorded at 45 min postmortem and again at 24 h in the ham semimembranosus (SM) and the longissimus muscle (LM) between the 10th and 11th rib. A Meatcheck (SFK Technology, Peosta, IA) conductivity probe was inserted in the same anatomical locations as pH measurement, providing an index value (PY) from 0 to 100 (a higher index value indicates more intact muscle cells and higher water-holding capacity). Color (L, a, b values) measurements were obtained at 24 h postmortem on the ham gluteus medius (GM), SM, and LM. Two 2.54-cm-thick loin chops were removed from the loin for determination of Warner-Bratzler shear force and glycolytic potential. The intact SM and the posterior portion of the boneless loin were vacuum-packaged and stored for 7 d to determine purge loss. Creatine-supplemented pigs had a higher (P = 0.03) PY value in the SM (66.67) at 45 min postmortem than either ALA, singularly (63.50), or in the combined CMH/ALA (62.27) treatments. (A higher PY index indicates superior water-holding capacity.) Lipoic acid supplementation resulted in the highest pH at 45 min (P = 0.029). These results justify further evaluation of the potential positive influence of supplementing alpha-lipoic acid to improve pork quality.

Animal Feed↗
PubMed2005

[Effect of temperature of fluid infusion on diamine oxidase, MB isoenzyme of creatine kinase, creatine-kinase and lactate dehydrogenase in hemorrhagic shock rabbits].

OBJECTIVE: To investigate the effects of different temperatures of fluid infusion on diamine oxidase(DAO), MB isoenzyme of creatine kinase (CK-MB), creatine kinase (CK) and lactate dehydrogenase (LDH) in rabbit with hemorrhagic shock so as to provide a clue to improve the nursing care in patients with hemorrhagic shock. METHODS: An animal model of controlled hemorrhagic shock in rabbits as previously reported was used in this randomized experiment. Twenty-three rabbits were randomized to a warm fluid infusion group (n=8), a ambient-temperature fluid infusion group (n=7), and a cold fluid infusion group (n=8). The rabbits were then resuscitated with Ringer's lactate solution three times of that of blood loss. DAO and values of myocardial enzyme were measured before shock, during shock and 1 hour, 2 hours and 4 hours after fluid infusion, respectively. RESULTS: There was no significant difference in DAO and values of myocardial enzymes among groups, though there was a lower value in DAO and values of myocardial enzymes at 1 hour to 4 hours after warm fluid infusion. CONCLUSION: Our data indicate that warm fluid infusion in rabbit model of controlled hemorrhagic shock has some beneficial effect on some biochemical values. In view of this result, temperature of fluid infusion in nursing care for patients with hemorrhagic shock should pay more attention to.

Amine Oxidase (Copper-Containing)↗
PubMed1992

Testing for creatine kinase and creatine kinase-2 in Ontario: reference ranges and assay types.

In 1991, 246 and 136 Ontario laboratories performed total creatine kinase (CK; EC 2.7.3.2) and creatine kinase-2 (CK-2) assays, respectively. A questionnaire mailed to these laboratories requested information about the types of assay used, the origin of their reference ranges, and the source of their instruments and reagents. All laboratories used current test formulations for CK, although seven laboratories did not assay at 37 degrees C. For CK, 69% of all laboratories reported different upper reference limits for men and women (5th-95th percentiles: 160-250 and 115-215 U/L, respectively); 31% reported similar ranges for both sexes. Fifty-six percent derived their own ranges; the remainder used either kit inserts or literature references, and nearly 60% of this latter group claimed to have validated these suggested ranges before use. For 6% of all laboratories, their pediatric ranges were similar to their adult ranges. For CK-2, only 32% used their own reference range; the remainder used kit inserts or literature references, but only 49% of this group validated these ranges before use. Reference limits (5th-95th percentiles) for CK-2 were as follows: activity 6-24 U/L; fraction of CK, 0.022-0.06; and, for mass assays, 5-10 micrograms/L and relative index 0.015-0.04.

Creatine Kinase↗
PubMed1991

Serum creatine kinase and creatine kinase-MB isoenzyme activities in perinatally asphyxiated newborns.

Serum creatine kinase (CK) and creatine kinase-MB isoenzyme (CK-MB) activities were studied prospectively in serial blood samples obtained from 23 perinatally asphyxiated negroid newborns and 12 healthy controls during the first 100 h of life. The asphyxiated infants had significantly elevated mean CK and absolute CK-MB but no fractional CK-MB activities. Peak mean CK and CK-MB values (U.l-1) were 789.17 (+/- 220), P less than 0.01 and 16.36 (+/- 3.0) P less than 0.001 respectively at the 6-8 post-partum period. The healthy controls, on the other hand, showed a steady decline in the activities of these enzymes from birth. The vaginally and operatively delivered asphyxiated infants showed significantly higher CK and CK-MB activities than their respective non-asphyxiated controls, but no increase in fractional CK-MB was recorded in any of the groups. The elevation in absolute and fractional CK-MB 42.0 U.l-1 (5.1%) in respect of the infants with TTI (transient tricuspid incompetence) was significant (P less than 0.05) when compared with the controls with features of TTN (transient tachypnoea of the newborn) in the 6-8 h post-partum period. One of the infants with TTI at autopsy had hypoxic myocardial injury. The specificity of CK-MB, as a marker of myocardial injury in asphyxiated negroid neonates, is plausible but remains uncertain. Until the lack of rise of CK and CK-MB in healthy negroid newborns is confirmed in a larger series with further studies on MM, BB and MB isoenzymes, caution is urged in the interpretation of elevated CK and CK-MB activities in asphyxiated negroid newborns.

Apgar Score↗
PubMed1990

A unique chicken B-creatine kinase gene gives rise to two B-creatine kinase isoproteins with distinct N termini by alternative splicing.

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.

Amino Acid Sequence↗
PubMed1990

Mitochondrial creatine kinase from chicken brain. Purification, biophysical characterization, and generation of heterodimeric and heterooctameric molecules with subunits of other creatine kinase isoenzymes.

In a recent study it has been shown that mitochondrial creatine kinase from chicken brain (Mia-CK) and heart (Mib-CK) are two distinct isoenzymes differing in ten out of the thirty N-terminal amino acids (Hossle, J.P., Schlegel, J., Wegmann, G., Wyss, M., Böhlen, P., Eppenberger, H.M., Wallimann, T., and Perriard J.C. (1988) Biochem. Biophys. Res. Commun. 151, 408-416). The present article describes the purification and biophysical characterization of the mitochondrial creatine kinase isoenzyme from chicken brain (Mia-CK). Gel permeation chromatography, direct mass measurements of individual molecules by scanning transmission electron microscopy, and analytical ultracentrifugation confirmed the existence of two different oligomeric forms, dimeric and octameric Mia-CK, with molecular masses of 85 kDa and 306-352 kDa and with sedimentation constants of 4.9-5.3 and 11.6-12.0 S, respectively. In addition, it was tested if Mia- and Mib-CK can form heterodimeric and heterooctameric molecules with subunits of other CK isoenzymes. By denaturation in urea or guanidine hydrochloride and subsequent renaturation, MiaMib-CK and surprisingly also MiaM-CK heterodimers could be generated. In contrast, no heterodimers were obtained between Mib- and M- or B-CK. Furthermore, reoctamerization of a mixture of Mia- and Mib-CK homodimers led to the formation of MiaMib-CK heterooctamers. In these heterooctamers, the Mia- and Mib-CK homodimers remained the fundamental building blocks. No subunit exchange between adjacent dimers within the heterooctamer could be observed even after storage for 3 months at 4 degrees C. The relevance of these data on the structural organization of the Mi-CK octamer and on the physiological aspects of tissue-specific isoenzyme expression are discussed.

Amino Acid Sequence↗
PubMed1989

Re-evaluation of the diagnostic utility of serum total creatine kinase and creatine kinase-2 in myocardial infarction.

The diagnostic utility of total creatine kinase activity (I), creatine kinase-2 isoenzyme activity (II), and II as a percentage of I, was examined by receiver-operating characteristic curve and likelihood ratio (LR) analyses in 310 persons admitted to the Coronary Care Unit (151 proven cases of myocardial infarction and 159 non-myocardial infarction controls), from whom blood was sampled at 6-h intervals for 48 h after the onset of chest pain. I was ineffective either as a "rule-in" or as a "rule-out" test within the first 6 h of the onset of chest pain; thereafter, it was an effective test. II was the most effective test during the entire 48-h period. III was more effective than I in the first 24-h period, but was less effective than I during the next 24-h period. The decision threshold for high test sensitivities varies with time over the entire 48-h period, but remains constant for high test specificities. It is essential to tabulate the LR(+) and LR(-) values for both test sensitivity and specificity at constant values to determine the utility of each test at each time interval for respectively ruling out or ruling in a diagnosis of myocardial infarction.

Creatine Kinase↗
PubMed1988

Native mitochondrial creatine kinase forms octameric structures. II. Characterization of dimers and octamers by ultracentrifugation, direct mass measurements by scanning transmission electron microscopy, and image analysis of single mitochondrial creatine kinase octamers.

Electron micrographs of negatively stained and metal-shadowed mitochondrial creatine kinase (Mi-CK) molecules purified as described by Schlegel et al. (Schlegel, J., Zurbriggen, B., Wegmann, E., Wyss, M., Eppenberger, H. M., and Wallimann, T. (1988) J. Biol Chem. 263, 16942-16953) revealed a homogeneous population (greater than or equal to 95%) of distinctly sized square-shaped, octameric particles with a side length of 10 nm that frequently exhibited a pronounced 4-fold axis of symmetry. The cube-like molecules consist of four dimers that are arranged around a stain-accumulating central cavity of 2.5-3 nm in diameter. This interpretation is supported by single particle averaging including correlation analysis by computer. Upon prolonged storage or high dilution, the cube-like octamers tended to dissociate into "banana-shaped" dimers. Sedimentation velocity and sedimentation equilibrium experiments yielded an s value of 12.8-13.5 S and an Mr of 328,000 +/- 25,000 for the octameric cubes. An s value of 5.0 S and a Mr of 83,000 +/- 8,000 was found under conditions which revealed banana-shaped dimers. These dimers proved to be very stable, as their dissociation into monomers of 45 kDa (s value = 2.0 S) required 6 M guanidine HCl. Thus, the oligomeric structures observed in the electron microscope are identified as Mi-CK dimers (banana-shaped structures) and cubical Mi-CK octamers assembled from four Mi-CK dimers. The octameric nature of native Mi-CK and the formation of Mi-CK dimers were confirmed by direct mass measurements of individual molecules by scanning transmission electron microscopy yielding a molecular mass of 340 +/- 55 kDa for the octamer and 89 +/- 27 kDa for the dimer. A structural model of Mi-CK octamers and the possible interaction with ATP/ADP-translocator molecules as well as with the outer mitochondrial membrane is proposed. The implications with respect to the physiological function of Mi-CK as an energy-channeling molecule at the producing side of the phosphoryl creatine shuttle are discussed.

Animals↗
PubMed1979

Developmental regulation of creatine kinase isoenzymes in myogenic cell cultures from chicken. Levels of mRNA for creatine kinase subunits M and B.

During the first 2 days of culture of myogenic chicken cells only minute amounts of mRNA for a subunit of creatine kinase, M-CK, could be found in cultures from the 3rd and 4th day; however, a dramatic increase of mRNA for the muscle-specific M-CK was observed. The mRNA for B-CK, another subunit of creatine kinase, was readily detectable in young cultures increased up to the 3rd day in culture but decreased significantly 1 day later. The comparison of the ratios of mRNA concentrations for M-CK and B-CK in polysomal and total cellular RNA did not reveal significant differences in polysomal and total cellular RNA from 24-, 48-, and 68-h cultures, indicating that specific accumulation of a nonpolysomal form containing translatable mRNA for M-CK prior to its appearance in the polysomes does not seem to represent a major mechanism of regulation. In RNA from cells grown in 5-bromo-2'-deoxyuridine (BrdUrd) for 3 days and subcultured into the same medium for another 3 days only mRNA for B-CK was found. If cells, however, were subcultured into standard medium both mRNAs, the one for B-CK and the one for M-CK could be detected. BrdUrd inhibition seems to affect only the mRNA for M-CK and not the one for B-CK. Removal of BrdUrd from the cultures probably allows new transcription or processing of mRNA for M-CK, or both.

Animals↗