The effects of creatine supplementation on thermoregulation and isokinetic muscular performance following acute (3-day) supplementation

AIM

The purpose of this investigation was to determine the effects of 3 d of creatine supplementation on thermoregulation and isokinetic muscular performance.

METHODS

Fourteen males performed two exercise bouts following 3 d of creatine supplementation and placebo. Subjects exercised for 60 min at 60-65% of VO2max in the heat followed by isokinetic muscular performance at 60, 180, and 300°·s(-1). Dependent variables for pre- and postexercise included nude body weight, urine specific gravity, and serum creatinine levels. Total body water, extracellular water and intracellular water were measured pre-exercise. Core temperature was assessed every 5 min during exercise. Peak torque and Fatigue Index were used to assess isokinetic muscular performance.

RESULTS

Core temperature increased during the run for both conditions. Total body water and extracellular water were significantly greater (P<0.05) following creatine supplementation. No significant difference (P>0.05) was found between conditions for intracellular water, nude body weight, urine specific gravity, and serum creatinine. Pre-exercise scores for urine specific gravity and serum creatinine were significantly less (P<0.05) versus post-exercise. No significant differences (P>0.05) were found in peak torque values or Fatigue Index between conditions for each velocity. A significant (P<0.05) overall velocity effect was found for both flexion and extension. As velocity increased, mean peak torque values decreased.

CONCLUSION

Three d of creatine supplementation does not affect thermoregulation during submaximal exercise in the heat and is not enough to elicit an ergogenic effect for isokinetic muscle performance following endurance activity.

Metastases outside the abdomen (MOA) are associated with initial high tumor burden (TB) in gastrointestinal stromal tumors (GIST)

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Background: In GIST MOA are rare events (8–10%) with a prognostic and predictive impact (JCO 2005;23:5795). To stage GIST, NCCN recommends either CT or abdominal MRI + chest imaging, suggesting PET scan only if early response assessment is needed. Therefore, MOA may be missed by standard work up. We evaluated if TB (largest tumor diameter > 12 centimetres) at diagnosis was associated to a higher incidence of MOA. Methods: From 01/02 to 12/05, 66 pts affected by GIST were either treated or followed-up at our hospital. Routine initial work up consisted in: chest CT + CT or MRI abdominal scan. Pet scan was performed if: uncertainties after standard imaging, to monitor “neoadjuvant” therapy or within clinical trials. Identified MOA if unique, would be considered for fine needle biopsy whilst multiple MOA would be monitored by most appropriate imaging technique. Results: Twenty-three pts (34%) had TB between 13 and 31 centimetres. At diagnosis 10 pts (15%) had MOA located in: lung (7 pts), bone (2 pts) subcutaneous tissue (1 pts). In this unfavourable group 9 pts (14%) were affected by tumors larger than 12 cm. Pts without MOA were 56 (85%) of whom 14 (21%) had TB. The association between initial TB and MOA was statistically significant (p<0.001). Conclusions: In this small series, high tumor burden is positively correlated to MOA. If these data should be confirmed, initial diagnostic work up could usefully include both chest CT and PET scan in abdominal mass beyond 12 centimetres wide. A precocious recognition of MOA would allow to better control therapeutic response and to better identify high-risk patients.

No significant financial relationships to disclose.

Increase of creatine kinase value (CK) correlates with muscoloskeletal complaints (MSC) in GIST patients during imatinib therapy

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Background: MSC-pain, muscle cramps, myalgias, arthralgias-are commonly associated with imatinib therapy, affecting 25% to 50% of patients. The cause is still unknown. MSC is usually mild to moderate and manageable without reduction of imatinib dose. Calcium and magnesium supplements have occasionally provided some relief. It is rather difficult to quantify MSC and patients who deserve interruption or analgesia on the base of symptoms alone. Since CK values are commonly elevated during imatinib therapy, we evaluate CK as a surrogate marker of MSC. Methods: Since 2002, 40 patients (pts) affected by advanced GIST were treated with imatinib 400 mg/day until progressive disease when dosage would be increased to 800 mg/day. Toxicity (CTC 2.0) and blood chemical values were prospectively collected on a monthly basis. Results: G1–2 MSC was observed in 22 pts (55%). We had to stop therapy in one patient only for one week because of uncontrolled MSC. CK was abnormal in 23 pts (57%). 13 pts (32%) had CK values up to twice upper normal value (UNV); 8 pts (20%) above thrice the UNV and 2 pts (5%) above 5 times the UNV. Among 10 pts having MSC G2, seven had CK above thrice UNV. The 2 pts experiencing MSC G3 had also CK above 5 times UNV. Conclusions: CK increase reflects MSC in a great majority of the patients who experienced this rather common imatinib side effect. To consider CK into standard clinical chemistry work up of patients on imatinib allows clinicians to add an objective measure of MSC.

No significant financial relationships to disclose.

Glucose-6-phosphate dehydrogenase deficiency and Gilbert syndrome: a gene interaction underlies severe jaundice without severe hemolysis

The authors describe the paradoxical clinical phenotype of an undetected severe hemolysis in parallel with the development of severe jaundice in a 13-year-old male suffering from a confirmed interaction of glucose-6-phosphate dehydrogenase deficiency (Mediterranean variant, 563 C/T) and Gilbert syndrome [variant (TA)7/(TA)7]. The child had 2 acute hemolytic episodes at the age of 10 and 13 years following infections of unknown origin. Both episodes were characterized by considerably high bilirubin levels (1st episode: 10.8 mg/dL, 2nd episode: 17.8 mg/dL) associated with unexpectably mild hemolysis indices (1st episode hemoglobin levels, 11.1 g/dL; reticulocyte counts, 2.5%; 2nd episode hemoglobin values, 12.7 g/dL; reticulocyte counts, 2.5%). During the steady-state condition of the child, hemoglobin values were within the normal ranges for his age (14.2 g/dL) and bilirubin levels were slightly elevated (1.70 mg/dL, indirect 1.5 mg/dL). The interaction of the two genetic abnormalities in the causation of this odd clinical phenotype is discussed.

Molecular cytogenetic characterization and origin of two de novo duplication 9p cases

We report on two additional cases with duplication of 9p, minor with facial anomalies and developmental delay. Using fluorescence in situ hybridization and single-copy probes, we showed that the first case was a direct duplication, whereas the second case was inverted. The extent of the direct duplication was defined as 9p12 --> p24 by microdissection and microcloning of the aberrant chromosome and subsequent chromosome-specific comparative genomic hybridization. DNA polymorphism analysis with eight microsatellite markers revealed that the origin of the dup(9p) was maternal in the first case, whereas it was paternal in the second.

Molecular genetics of Turner syndrome: correlation with clinical phenotype and response to growth hormone therapy

To correlate the origin of the retained X in Turner syndrome with phenotype, pre-treatment height and response to recombinant human growth hormone (rhGH) therapy, systematic clinical assessment and molecular studies were carried out in 33 Greek children with Turner syndrome and their parents including 18 children with 45,X and 15 with X-mosaicism. Microsatellite markers on X chromosomes (DXS101 and DXS337) revealed that the intact X was paternal (Xp) in 15/30 and maternal (Xm) in 15/30 children, while 3/33 families were non-informative. No significant relationship was found between parental origin of the retained X and birth weight/length/gestational age, blepharoptosis, pterygium colli, webbed neck, low hairline, abnormal ears, lymphoedema, short 4th metacarpal, shield chest, widely spaced nipples, cubitus valgus, pigmented naevi, streak gonads, and cardiovascular/renal anomalies. With regard to the children's pre-treatment height, there was a significant correlation with maternal height and target height in both Xm and Xp groups. No differences were found between Xm and Xp groups and the improvement of growth velocity (GV) during the first and second year of rhGH administration, while for both groups GV significantly improved with rhGH by the end of the first and the second year. To our knowledge, this is the first attempt to correlate the parental origin of Turner syndrome with the response to rhGH therapy.

Supernumerary marker chromosomes (SMCs) in Turner syndrome are mostly derived from the Y chromosome

DNA and FISH (fluorescence in situ hybridization) analysis were carried out in 12 patients with stigmata of Turner syndrome to determine whether the Supernumerary Marker Chromosome (SMC) found cytogenetically in each of these patients was derived from the Y chromosome. The presence of a Y chromosome in these patients may predispose them to develop gonadoblastoma. PCR-Southern blot analysis, followed by FISH, was used to detect the presence of Y chromosome material. The Sex determining Region Y (SRY), Testis Specific Protein Y-encoded (TSPY) and Y-chromosome RNA Recognition Motif (YRRM) genes, which map at Yp11.31, Yp11.1-11.2 and Yp11.2/Yq11.21-11.23, respectively, were selected as markers, because they span the whole Y chromosome, and more importantly, they are considered to be involved in the development of gonadoblastoma. It was shown that in 12 patients, all of whom had an SMC, the SMC of 11 was derived from the Y chromosome. Furthermore, the presence of the SRY, TSPY and YRRM gene sequences was determined and FISH analysis confirmed the Y origin of the SMCs. The methodology described in this report is a rapid, reliable and sensitive approach which may be easily applied to determine the Y origin of an SMC carried in Turner syndrome. The identification of an SMC is important for the clinical management and prognostic counseling of these patients with Turner syndrome.

High nitrate content in drinking water: cytogenetic effects in exposed children

The potential genotoxicity of nitrates and nitrites-contaminants of drinking water that have been implicated in carcinogenesis-was investigated in this study. Sister chromatid exchanges and frequency of chromatid/chromosome aberrations were studied in peripheral blood lymphocytes of 70 children who were 12-15 y of age. These children were permanent residents in geographical areas of Greece, where elevated concentrations of nitrates (i.e., 55.70-87.98 mg/l) existed in drinking water. The control group comprised 20 healthy children who resided in areas with very low nitrate concentrations (i.e., 0.7 mg/l). A significant increase in the mean number of chromatid/chromosome breaks was observed in children exposed to nitrate concentrations that exceeded 70.5 mg/l (p < .01), but there was no significant increase in the mean number of sister chromatid exchanges per cell. The results indicate that chronic administration of elevated concentrations of nitrate in drinking water has the capability of inducing cytogenetic effects.

Sister chromatid exchanges in peripheral lymphocytes in newborns treated with phototherapy and vitamin E

A study was undertaken to determine whether blue fluorescent light might affect the sister chromatid exchange (SCE) frequency of peripheral lymphocytes in icteric newborns undergoing continuous phototherapy treatment (72 h). Also, the potential preventive effect of vitamin E on SCE frequency was studied in a subgroup of 11 preterm and 9 fullterm newborns after daily administration of vitamin E (46.44 mumol/kg/d, im). The results revealed that only the preterm icteric newborns showed an increase in mean SCE frequency of peripheral lymphocytes after phototherapy (9%, p = 0.02), but in no case did the highest SCEs/cell ratio exceed the normal values. No correlation was found between the average SCE rate and birth weight, gestational age or bilirubin levels. Also, no difference in SCEs was observed between newborns treated or untreated with vitamin E.