Development and validation of a food frequency questionnaire for assessing dietary calcium intake in the general population

The aim of this study was to develop and evaluate a food frequency questionnaire (FFQ) for assessing dietary calcium intake in the general population, since all available questionnaires at present are age- and/or gender-specific. A total of 1001 individuals (including children, adults, and elderly people of both genders) were randomly recruited throughout Greece. Estimates of calcium intake from the 30-item FFQ were compared with those from a multi-pass 24-h recall. The FFQ underestimated mean calcium intake compared to the 24-h recall by (mean±SD) –133±333 mg/day or –5.4±47.6% (P<0.001). The two methods were strongly correlated (r=0.639, P<0.001), but the 95% limits of agreement for individual assessment were rather wide, as the FFQ could provide estimates of calcium intake from 533 mg/day above to 799 mg/day below the 24-h recall. Actual values for surrogate FFQ quartiles manifested a progressive increase, with significant differences between mean calcium intakes (P<0.001). The FFQ could identify individuals who consumed less calcium than 800 mg/day or less than the age-specific adequate intake with a relatively high sensitivity (82.8 and 95.5%, respectively), but low specificity (54.9 and 34.1%, respectively). Cross-classification analysis indicated that only 17 subjects (1.7%) were grossly misclassified (lowest quartile for one method and highest quartile for the other), while 827 subjects (82.6%) were correctly classified (into the same or adjacent quartiles). The FFQ could be used in population-based epidemiological studies or screening programs involving individuals of all ages and both genders, where the discrimination of subjects with relatively low (<500 mg/day) and relatively high (>1000 mg/day) calcium intakes is of primary interest. Results, however, do not support its use for the quantitative assessment of individual calcium intakes.     

Analysis of SAA1 gene polymorphisms in the Greek population: rheumatoid arthritis and FMF patients relative to normal controls. Homogeneous distribution and low incidence of AA amyloidosis.

OBJECTIVE: To address whether or not the rarity of amyloidosis in Greek patients with rheumatoid arthritis (RA) is related to specific alleles of single nucleotide polymorphisms (SNPs) in the 5'-flanking region and the exon 3 of the SSA1 gene. METHODS: The genotypes of the -13T/C SNP in the 5'-flanking region of the SAA1 gene and the two SNPs within exon 3 of SAA1 (2995C/T and 3010C/T polymorphisms) were determined in 88 Greek patients with RA, 14 patients with familial Mediterranean fever (FMF) and 110 healthy controls. Linkage disequilibrium and haplotype frequencies involving -13T/C, 2995C/T and 3010C/T in these populations were tested and estimated, respectively. RESULTS: The genotypic distribution and allelic frequencies were similar in all groups tested. SNPs 2995 and 3010 were in linkage disequilibrium for all study populations (p < 0.05), whereas SNP -13 was not in linkage disequilibrium with either 2995 or 3010 (p > or = 0.05). Two major haplotypes presented in all patients with RA and FMF and controls: -13C; 2995T; 3010C (-13C; alpha) and -13C; 2995C; 3010T (-13C; beta). The -13T allele was linked with the gamma haplotype in Greek patients with RA and controls. The frequency of the -13T allele was found to be very rare in all groups tested. CONCLUSIONS: In conclusion, the rarity of the putative amyloidogenic -13T allele in Greek populations may be related to low prevalence of AA amyloidosis development in Greek RA patients.     

Experimental verification of a model describing the occupied volume by polymers in solution

A relation is proposed which yields the occupied volume by macromolecular chains in solution. The experimental verification of the model is carried out by a viscometric study of the ternary system polymer A/polymer B/solvent. More precisely the viscometric study permits the determination of the critical concentration c^** corresponding to the incipient overlap of spherical coils.     

Aerobic exercise training improves insulin sensitivity without changes in body weight, body fat, adiponectin, and inflammatory markers in overweight and obese girls

The aim of this study was to examine the effect of aerobic exercise training on insulin sensitivity in overweight and obese girls. Nineteen overweight and obese girls (mean +/- SD: age, 13.1+/-1.8 years; body mass index, 26.8+/-3.9 kg/m(2)) volunteered for this study. Body composition (dual-energy x-ray absorptiometry), insulin sensitivity (oral glucose tolerance test and homeostasis model assessment estimate of insulin resistance; n=15), adiponectin, C-reactive protein (CRP), interleukin (IL) 6, insulin-like growth factor-1, soluble intercellular adhesion molecule-1 and soluble vascular cell adhesion molecule-1 serum levels, and blood lipids and lipoproteins were assessed before and after 12 weeks of aerobic training. Cardiorespiratory fitness increased by 18.8% (P<.05) as a result of training. The area under the insulin concentration curve (insulin area under the curve) decreased by 23.3% (12781.7+/-7454.2 vs 9799.0+/-4918.6 microU.min/mL before and after intervention, respectively; P=.03). Insulin sensitivity was improved without changes in body weight (pre-intervention, 67.9+/-14.5 kg; post-intervention, 68.3+/-14.0 kg) or percent body fat (pre-intervention, 41.4% +/- 4.8%; post-intervention, 40.7%+/-5.2%). The lower limb fat-free mass increased by 6.2% (P<.01) as a result of training, and changes in lower limb fat-free mass were correlated with changes in the insulin area under the curve (r= -.68; P< .01). Serum adiponectin, IL-6, and CRP concentrations did not change (pre-intervention vs post-intervention: adiponectin, 9.57+/-3.01 vs 9.08+/-2.32 microg/mL; IL-6, 1.67+/-1.29 vs 1.65+/-1.25 pg/mL, CRP, 3.21+/-2.48 vs 2.73+/-1.88 mg/L) whereas insulin-like growth factor-1 was lower after training (pre-intervention, 453.8 +/- 159.3 ng/mL; post-intervention, 403.2+/- 155.1 ng/mL; P<.05). In conclusion, 12 weeks of aerobic training improved insulin sensitivity in overweight and obese girls without change in body weight, percent body fat, and circulating concentrations of adiponectin, IL-6, CRP, and other inflammatory markers. These findings suggest that increased physical activity may ameliorate the metabolic abnormalities associated with obesity in children with a mechanism other than the parameters cited earlier.     

Body mass index, calcium intake, and physical activity affect calcaneal ultrasound in healthy Greek males in an age-dependent and parameter-specific manner

Quantitative ultrasound (QUS) is a peripheral bone densitometry technique that is rapidly gaining in popularity for the assessment of skeletal status. This study was carried out to examine the effect of anthropometric, dietary, physical activity, and other lifestyle factors on QUS parameters in healthy Greek males of various ages, including children (n = 192), adults (n = 106), and elderly (n = 86) subjects. Calcaneal QUS measurements were performed with the Sahara device (Hologic), which measures broadband ultrasound attenuation (BUA) and speed of sound (SOS) through the os calcis. A composite parameter, the quantitative ultrasound index (QUI), and an estimate of heel bone mineral density (eBMD) were also derived. BUA correlated positively with height, weight, and body mass index, as well as waist and hip circumferences (P < 0.001), but this was not the case for SOS. QUI and eBMD were inconsistently related with anthropometric characteristics. Overweight and obese males had significantly higher BUA than normal-weight subjects (P < 0.05), but similar SOS, QUI, and eBMD; this held true for all age groups. Boys participating in organized physical activities had significantly higher SOS, QUI, and eBMD than those who did not (P < 0.05), although BUA was similar in the two groups; no differences according to organized physical activity were detected in adults and the elderly. On the other hand, adult men devoting at least some time to non-organized physical activities had significantly higher QUS values than their non-exercising peers (P < 0.05); no such effects, however, were seen in children and the elderly. Adult men with calcium intakes above 800mg/day had significantly higher SOS, QUI, and eBMD than those consuming less calcium (P < 0.05), and also tended towards higher BUA (P = 0.079); no such differences were observed among children and elderly men. The effects of physical activity and calcium intake on heel QUS persisted even after controlling for body size. Overall, body weight was the sole significant positive determinant of BUA ( = 0.373; t = 6.589; P < 0.001), explaining approximately 14% of the total variance, while age was the sole significant negative determinant of SOS ( = –0.198; t = –3.321; P = 0.001), albeit explaining only less than 4% of the total variance. In conclusion, body size, dietary calcium intake, and physical activity patterns seem to inconsistently and age-dependently influence heel QUS among healthy Greek males in a parameter-specific manner.     

Quantitative ultrasound calcaneus measurements: normative data for the Greek population

Quantitative ultrasound (QUS) is a peripheral bone densitometry technique that is rapidly gaining in popularity, and is widely used worldwide for the assessment of skeletal status. This, however, generally occurs in the absence of adequate clinical guidelines. As accurate interpretation of the results and correct classification in individual fracture risk assessment are of great value, the present study was carried out to establish a reference database for calcaneal QUS measurements across age group and gender in Greece. A total of 1205 subjects (821 females and 384 males) from three age groups (409 children, 341 adults and 455 elderly) were recruited. QUS measurements were performed at the heel with the Sahara device, which measures broadband ultrasound attenuation (BUA) and speed of sound (SOS), and then combines these variables into a single parameter, the quantitative ultrasound index (QUI). Overall, gender-related differences were more pronounced among the elderly, while age-related differences were more pronounced among females. Elderly men had higher QUS parameters than women of peer age, but no major gender differences were observed in children and adults. In males, only BUA showed a variation with age, being higher in adult and elderly men compared to boys. On the other hand, all QUS parameters varied significantly with age in females, the general trends being mildly positive from childhood to adulthood, when peak levels were observed, and negative thereafter. The results for the Greek population were in the range reported previously for other populations, but some discrepancies were evident, probably resulting from ethno-specific characteristics and different QUS instrumentation. Importantly, using the manufacturers or the local database as the reference population for computing T-scores led to significantly different classification of subjects into conventional categories of risk. These data could be useful as a guide for comparing the results of individual studies, as well as for the assessment of Greek men and women at risk of fracture.     

Effect of maltose-containing sports drinks on exercise performance

This study examined the effect of maltose-containing sports drinks on exercise performance. Ten subjects completed 4 trials. Each trial consisted of a glycogen depletion protocol, followed by a 15-min refueling, after which subjects performed an 1-h performance test while consuming one of the experimental drinks (HGlu, glucose; HMal, maltose; MalMix, sucrose, maltose, and maltodextrin; Plac, placebo). Drinks provided 0.65 g/kg body weight carbohydrates during refueling and 0.2 g/kg every 15 min during the performance test. Although no significant differences were found in performance (HGlu: 67.2 +/- 2.0; HMal: 68.6 +/- 1.7; MalMix: 66.7 +/- 2.0; Plac: 69.4 +/- 3.0 min, P> 0.05), subjects completed the MalMix trial 3.9%; faster than the Plac. Carbohydrate drinks caused comparable plasma glucose values that were significantly higher during refueling and at the end of exercise, compared to Plac. The data suggest that although carbohydrate drinks help to maintain plasma glucose at a higher level, no differences in performance could be detected after glycogen-depleting exercise.     

Improved insulin sensitivity after a single bout of exercise is curvilinearly related to exercise energy expenditure

A single bout of moderate-intensity exercise increases whole-body insulin sensitivity for 12-48 h post-exercise; however, the relationship between exercise energy expenditure and the improvement in insulin sensitivity is not known. We hypothesized that the exercise-induced increase in whole-body insulin sensitivity, assessed with HOMA(IR) (homoeostasis model assessment of insulin resistance), is directly related to the energy expended during exercise. We studied 30 recreationally active non-obese men (age, 27+/-5 years; body mass index, 24+/-2 kg/m(2)) in the post-absorptive state on two separate occasions: once after exercising at 60% of VO(22peak) (peak oxygen consumption) for 30-120 min on the preceding afternoon (expending a total of 1.28-5.76 MJ) and once after an equivalent period of rest. Blood samples were obtained the following morning. Exercise-induced changes in HOMA(IR) were curvilinearly related to exercise energy expenditure (r=-0.666, P=0.001) with a threshold of approx. 3.77 MJ (900 kcal) for improvements in HOMA(IR) to be manifested. In particular, HOMA(IR) was reduced by 32+/-24% (P=0.003) in subjects who expended more than 3.77 MJ during exercise, but did not change for those who expended fewer than 3.77 MJ (-2+/-21%; P=0.301). Furthermore, the magnitude of change in HOMA(IR) after exercise was directly associated with baseline (i.e. resting) HOMA(IR) (r=-0.508, P=0.004); this relationship persisted in multivariate analysis. We conclude that improved whole-body insulin resistance after a single bout of exercise is curvilinearly related to exercise energy expenditure, and requires unfeasible amounts of exercise for most sedentary individuals.