Effects of a Cycling versus Running HIIT Program on Fat Mass Loss and Gut Microbiota Composition in Men with Overweight/Obesity

PURPOSE

High-intensity interval training (HIIT) can efficiently decrease total and (intra-)abdominal fat mass (FM); however, the effects of running versus cycling HIIT programs on FM reduction have not been compared yet. In addition, the link between HIIT-induced FM reduction and gut microbiota must be better investigated. The aim of this study was to compare the effects of two 12-wk HIIT isoenergetic programs (cycling vs running) on body composition and fecal microbiota composition in nondieting men with overweight or obesity.

METHODS

Sixteen men (age, 54.2 ± 9.6 yr; body mass index, 29.9 ± 2.3 kg·m -2 ) were randomly assigned to the HIIT-BIKE (10 × 45 s at 80%-85% of maximal heart rate, 90-s active recovery) or HIIT-RUN (9 × 45 s at 80%-85% of maximal heart rate, 90-s active recovery) group (3 times per week). Dual-energy x-ray absorptiometry was used to determine body composition. Preintervention and postintervention fecal microbiota composition was analyzed by 16S rRNA gene sequencing, and diet was controlled.

RESULTS

Overall, body weight, and abdominal and visceral FM decreased over time ( P < 0.05). No difference was observed for weight, total body FM, and visceral FM between groups (% change). Conversely, abdominal FM loss was greater in the HIIT-RUN group (-16.1% vs -8.3%; P = 0.050). The α-diversity of gut microbiota did not vary between baseline and intervention end and between groups, but was associated with abdominal FM change ( r = -0.6; P = 0.02). The baseline microbiota profile and composition changes were correlated with total and abdominal/visceral FM losses.

CONCLUSIONS

Both cycling and running isoenergetic HIIT programs improved body composition in men with overweight/obesity. Baseline intestinal microbiota composition and its postintervention variations were correlated with FM reduction, strengthening the possible link between these parameters. The mechanisms underlying the greater abdominal FM loss in the HIIT-RUN group require additional investigations.

Pediatric refractory chronic immune thrombocytopenia: Identification, patients' characteristics, and outcome

Refractory chronic immune thrombocytopenia (r-cITP) is one of the most challenging situations in chronic immune thrombocytopenia (cITP). Pediatric r-cITP is inconsistently defined in literature, contributing to the scarcity of data. Moreover, no evidence is available to guide the choice of treatment. We compared seven definitions of r-cITP including five pediatric definitions in 886 patients with cITP (median [min-max] follow-up 5.3 [1.0-29.3] years). The pediatric definitions identified overlapping groups of various sizes (4%-20%) but with similar characteristics (higher proportion of immunopathological manifestations [IM] and systemic lupus erythematosus [SLE]), suggesting that they adequately captured the population of interest. Based on the 79 patients with r-cITP (median follow-up 3.1 [0-18.2] years) according to the CEREVANCE definition (≥3 second-line treatments), we showed that r-cITP occurred at a rate of 1.15% new patients per year and did not plateau over time. In multivariate analysis, older age was associated with r-cITP. One patient (1%) experienced two grade five bleeding events after meeting r-cITP criteria and while not receiving second-line treatment. The cumulative incidence of continuous complete remission (CCR) at 2 years after r-cITP diagnosis was 9%. In this analysis, splenectomy was associated with a higher cumulative incidence of CCR (hazard ratio: 5.43, 95% confidence interval: 1.48-19.84, p = 7.8 × 10-4). In sum, children with cITP may be diagnosed with r-cITP at any time point of the follow-up and are at increased risk of IM and SLE. Second-line treatments seem to be effective for preventing grade 5 bleeding. Splenectomy may be considered to achieve CCR.

Antinuclear antibody-associated autoimmune cytopenia in childhood is a risk factor for systemic lupus erythematosus

ABSTRACT

Autoimmune cytopenia (AIC) in children may be associated with positive antinuclear antibodies (ANA) and may progress to systemic lupus erythematosus (SLE). We evaluated the risk of progression to SLE of childhood-onset ANA-associated AIC. In the French national prospective OBS'CEREVANCE cohort, the long-term outcome of children with ANA-associated AIC (ANA titer ≥1/160) and a subgroup of children who developed SLE were described. ANA were positive in 355 of 1803 (20%) children with AIC. With a median follow-up of 5.8 (range, 0.1-29.6) years, 79 of 355 (22%) patients developed SLE at a median age of 14.5 (1.1-21.4) years; 20% of chronic immune thrombocytopenic purpura, 19% of autoimmune hemolytic anemia, and 45% of Evans syndrome. None of the patients with ANA-negative test developed SLE. Severe manifestations of SLE were observed in 21 patients, and 2 patients died. In multivariate analysis including patients with positive ANA within the first 3 months after AIC diagnosis, age >10 years at AIC diagnosis (relative risk [RR], 3.67; 95% confidence interval [CI], 1.18-11.4; P = .024) and ANA titer >1/160 (RR, 5.28; 95% CI, 1.20-23.17; P = .027) were associated with the occurrence of SLE after AIC diagnosis. ANA-associated AIC is a risk factor for progression to SLE, especially in children with an initial ANA titer >1/160 and an age >10 years at AIC diagnosis. ANA screening should be recommended in children with AIC, and patients with ANA should be monitored long-term for SLE, with special attention to the transition period. This trial was registered at www.ClinicalTrials.gov as #NCT05937828.

Fitness and metabolic response to exercise in young adult survivors of childhood lymphoma

PURPOSE

Childhood lymphoma survivors (CLSs) are at high risk of reduced daily activity. This work studied metabolic substrate use and cardiorespiratory function in response to exercise in CLSs.

METHODS

Twenty CLSs and 20 healthy adult controls matched for sex, age, and BMI took an incremental submaximal exercise test to determine fat/carbohydrate oxidation rates. Resting echocardiography and pulmonary functional tests were performed. Physical activity level, and blood metabolic and hormonal levels were measured.

RESULTS

CLSs reported more physical activity than controls (6317 ± 3815 vs. 4268 ± 4354 MET-minutes/week, p = 0.013), had higher resting heart rate (83 ± 14 vs. 71 ± 13 bpm, p = 0.006), and showed altered global longitudinal strain (- 17.5 ± 2.1 vs. - 19.8 ± 1.6%, p = 0.003). We observed no difference in maximal fat oxidation between the groups, but it was reached at lower relative exercise intensities in CLSs (Fatmax 17.4 ± 6.0 vs. 20.1 ± 4.1 mL/kg, p = 0.021). At V̇O₂ peak, CLSs developed lower relative exercise power (3.2 ± 0.9 vs. 4.0 ± 0.7 W/kg, p = 0.012).

CONCLUSION

CLSs reported higher levels of physical activity but they attained maximal fat oxidation at lower relative oxygen uptake and applied lower relative power at V̇O₂ peak. CLSs may thus have lower muscular efficiency, causing greater fatigability in response to exercise, possibly related to chemotherapy exposure during adolescence and childhood. Long-term follow-up is essential and regular physical activity needs to be sustained.

Impact of age at diagnosis, sex, and immunopathological manifestations in 886 patients with pediatric chronic immune thrombocytopenia

Pediatric chronic immune thrombocytopenia (cITP) is a heterogeneous condition in terms of bleeding severity, second-line treatment use, association with clinical and/or biological immunopathological manifestations (IMs), and progression to systemic lupus erythematosus (SLE). No risk factors for these outcomes are known. Specifically, whether age at ITP diagnosis, sex, or IMs impact cITP outcomes is unknown. We report the outcomes of patients with pediatric cITP from the French nationwide prospective cohort OBS'CEREVANCE. We used multivariate analyses to investigate the effect of age at ITP diagnosis, sex, and IMs on cITP outcomes. We included 886 patients with a median (min-max) follow-up duration of 5.3 (1.0-29.3) years. We identified an age cutoff that dichotomized the risk of the outcomes and defined two risk groups: patients with ITP diagnosed <10 years (children) and ≥ 10 years (adolescents). Adolescents had a two to four-fold higher risk of grade ≥3 bleeding, second-line treatment use, clinical and biological IMs, and SLE diagnosis. Moreover, female sex and biological IMs were independently associated with higher risks of biological IMs and SLE diagnosis, second-line treatment use, and SLE diagnosis, respectively. The combination of these three risk factors defined outcome-specific risk groups. Finally, we showed that patients clustered in mild and severe phenotypes, more frequent in children and adolescents, respectively. In conclusion, we identified that age at ITP diagnosis, sex, and biological IMs impacted the long-term outcomes of pediatric cITP. We defined risk groups for each outcome, which will help clinical management and further studies.

Isocaloric Diets with Different Protein-Carbohydrate Ratios: The Effect on Sleep, Melatonin Secretion and Subsequent Nutritional Response in Healthy Young Men

This study aimed to determine the short-term effect of two isocaloric diets differing in the ratio of protein−carbohydrate on melatonin levels, sleep, and subsequent dietary intake and physical activity in healthy young men. Twenty-four healthy men took part in a crossover design including two sessions of three days on isocaloric diets whether high-protein, low-carbohydrate (HPLC) or low-protein, high-carbohydrate (LPHC) followed by 24-h free living assessments. Sleep was measured by ambulatory polysomnography pre-post-intervention. Melatonin levels were assessed on the third night of each session on eight-point salivary sampling. Physical activity was monitored by accelerometry. On day 4, participants reported their 24-h ad-libitum dietary intake. LPHC resulted in better sleep quality and increased secretion of melatonin compared to HPLC. A significant difference was noted in sleep efficiency (p < 0.05) between the two sessions. This was mainly explained by a difference in sleep onset latency (p < 0.01) which was decreased during LPHC (PRE: 15.8 ± 7.8 min, POST: 11.4 ± 4.5 min, p < 0.001). Differences were also noted in sleep staging including time spent on REM (p < 0.05) and N1 (p < 0.05). More importantly, REM latency (PRE: 97.2 ± 19.9 min, POST 112.0 ± 20.7 min, p < 0.001) and cortical arousals (PRE: 7.2 ± 3.9 event/h, POST 8.5 ± 3.3 event/h) increased in response to HPLC diet but not LPHC. On day 4, 24-h ad-libitum energy intake was higher following HPLC compared to LPHC (+64 kcal, p < 0.05) and explained by increased snacking behavior (p < 0.01) especially from carbohydrates (p < 0.05). Increased carbohydrates intake was associated with increased cortical arousals.

Effect of morning versus evening exercise training on sleep, physical activity, fitness, fatigue and quality of life in overweight and obese adults

This study compares the effectiveness of a 12-week moderate exercise training program (METP), performed in the morning versus the evening, on sleep, physical activity, physical fitness, sleepiness, fatigue and health-related quality of life (HRQoL) in overweight and obese patients. Sedentary and inactive overweight/obese adults (n = 36) were included in METP and randomized into two groups: morning group (GM) and evening group (GE). Twenty-eight participants successfully completed METP (3 × 90 min exercise session per week for 12 weeks, completion rates >80%). Sleep, physical activity, and bedtime temperature were measured using accelerometry and infrared tympanic temperature during 3 separate weeks of the study (Week1, Week6, and Week12). Participants also took part in baseline and endpoint assessments including physical fitness as well as subjective physical activity, chronotype, sleep quality, sleepiness, fatigue and HRQoL. METP did not impact objective sleep quality differently between the two groups (morning vs evening). Bedtime and mid-sleep were advanced when METP was done in the morning whereas they were delayed when METP was practiced in the early evening (p = .003). Beside this finding, no valuable differences between the two groups were noted in all the remaining measures. METP resulted in improvements of body composition, cardiorespiratory and muscular endurance, as well as a favorable impact on subjective sleep quality, diurnal sleepiness, fatigue and HRQoL in both groups (all p < .05). Evening METP could be an effective alternative for overweight/obese adults when morning METP is not possible.

Sleep pattern and staging in elite adolescent rugby players during the in-season competitive phase compared to an age matched non-athlete population

Young athletes must contend with the constraints of elite sports on top of school commitments and the physiological processes associated with adolescence. This study assessed week and weekend sleep and schedule of activities in elite adolescent rugby players during the in-season competitive phase compared with age-matched non-athlete controls. 32 adolescents (GR: 16 elite rugby players, GC: 16 controls) from the same boarding school filled out a daily schedule of activities and a sleep diary, and wore a multichannel electroencephalogram for 14 days. They later filled out questionnaires on their sleep quality, sleepiness, and perceived stress. Both groups showed insufficient sleep duration during the week (<7 h). Only GC caught up on their sleep debt during the weekend (increased TIB, TST and time spent in REM sleep, all p < 0.001). Weekend TIB, TST and, N3 sleep remained similar to that for weekdays in GR. However, GR experienced lower sleep quality (decreased SE, increased WASO, all p < 0.01) and a decrease in REM sleep (p < 0.01). Schedules of activities showed an increase in time spent on overall activities during the weekend, mainly due to competition and sport-specific travel, which resulted in a decrease in sleep opportunity time compared with GC (p < 0.001). Δ sleep opportunity time (weekend-week) was associated with Δ TST (weekend-week), and Δ TST (weekend-week) was associated with sleepiness and perceived stress. Busy schedules during the competitive season decreased sleep opportunity time and prevented elite adolescent rugby players from catching up on their sleep at weekends.HIGHLIGHTS Adolescent rugby players have insufficient sleep during both week and weekend of the in-season competitive phaseCongested schedule prevented elite adolescent rugby players from catching up on their sleep at weekends.Sleep considerations are necessary when planning the weekend sporting schedules.

Large-Scale Assessment of Health-Related Physical Fitness in French Older Adults: Feasibility and Validity

Objectives: This study aims to assess the validity, internal consistency, implementation, and feasibility of a sequence of tests, the Vitality Test Battery, designed to measure physical fitness, at a large scale in French older adults.

Methods: A total of 528 volunteers (age ≥60 years) took the battery of 10 tests: 6-min walk, trunk strength, hand grip strength, medicine ball throwing, 30-s chair stand, flexibility, balance, plate tapping, ruler drop, and dual task.

Results: Internal consistency was high, with the Cronbach alpha coefficients at around 0.77, explaining 64% of the variance. The test–retest correlations (0.3–0.6) between the items were acceptable and displayed an internal consistency property. Although five components explained 65% of the variance, all the items were kept because their eigenvalues were near to 0.9. External consistency was validated by a significant decrease in fitness scores (p < 0.001) with age and body mass index.

Discussion: The Vitality Test Battery is a safe, valid tool for assessing physical fitness in persons aged over 60 years.

Childhood Leukemia Survivors and Metabolic Response to Exercise: A Pilot Controlled Study

Background: Leukemia is the most common cancer in pediatrics, with many late effects such as higher risk of dyslipidemia, insulin resistance, obesity, and metabolic syndrome. The objective of this work was to investigate substrate oxidation during submaximal exercise in survivors of childhood acute leukemia. Methods: A total of 20 leukemia survivors and 20 healthy children were matched by sex, age, and Tanner stage. They all took a submaximal incremental exercise test to determine fat and carbohydrate oxidation rates. Results: Cardiorespiratory fitness was significantly lower in leukemia survivors, with lower relative VO₂ peaks (p < 0.001), lower heart rate values (p = 0.02), and lower exercise power (p = 0.012), whereas rest metabolism and body mass index did not differ between the two groups. During exercise, upward of heart rate relative to VO₂ peak was significantly higher (p < 0.001) in childhood leukemia survivors. We found lower carbohydrate and fat oxidation rates (p = 0.07) in leukemia survivors compared with healthy children, and also a significantly lower relative maximal fat oxidation rate (p = 0.014). Conclusion: Despite impaired physical fitness and metabolic response to exercise, childhood leukemia survivors remained sensitive to physical activity interventions, and could readily adapt to submaximal exercise intensity.

TNF blockade contributes to restore lipid oxidation during exercise in children with juvenile idiopathic arthritis

BACKGROUND

Children with juvenile idiopathic arthritis (JIA) have impaired physical abilities. TNF-α plays a crucial role in this pathogenesis, but it is also involved in the use of lipids and muscle health. Objective of this study was to explore substrate oxidation and impact of TNF blockade on energy metabolism in children with JIA as compared to healthy children.

METHODS

Fifteen non-TNF-blockaded and 15 TNF-blockaded children with JIA and 15 healthy controls were matched by sex, age, and Tanner stage. Participants completed a submaximal incremental exercise test on ergocycle to determine fat and carbohydrate oxidation rates by indirect calorimetry.

RESULTS

The maximal fat oxidation rate during exercise was lower in JIA children untreated by TNF blockade (134.3 ± 45.2 mg.min- 1) when compared to the controls (225.3 ± 92.9 mg.min- 1, p = 0.007); but was higher in JIA children under TNF blockade (163.2 ± 59.0 mg.min- 1, p = 0.31) when compared to JIA children untreated by TNF blockade. At the same relative exercise intensities, there was no difference in carbohydrate oxidation rate between three groups.

CONCLUSIONS

Lipid metabolism during exercise was found to be impaired in children with JIA. However, TNF treatment seems to improve the fat oxidation rate in this population.

TRIAL REGISTRATION

In ClinicalTrials.gov, reference number NCT02977416 , registered on 30 November 2016.

In vitro assessment of edoxaban anticoagulant effect in pediatric plasma

INTRODUCTION

Anticoagulant therapy in pediatric patients remains an issue and safer therapies, such as direct oral anticoagulants could overcome the limitations of conventional anticoagulant treatments in this population. Edoxaban, a factor Xa inhibitor, is used for the prevention and treatment of venous thromboembolism. Due to its pharmacokinetic characteristics, edoxaban is a promising candidate molecule for children. This study compared edoxaban in vitro effect in children and adults.

MATERIALS AND METHODS

Blood samples were prospectively collected from 87 adults and 97 children (n = 12: <2 year-old; n = 8: 2-4 year-old; n = 9: 5-7 year-old; n = 14: 8-9 year-old; n = 10: 10-13 year-old; n = 15: 14-15 year-old; and n = 29: 16-18 year-old). Plasma samples were supplemented in vitro with edoxaban to a final concentration of 50, 150 or 300 ng/mL, and then edoxaban effect on prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen (Clauss assay), specific anti-factor Xa activity and thrombin generation assay (TGA) (with 5pM tissue factor and 4 nM phospholipids) was evaluated.

RESULTS

PT, aPTT, and specific anti-Xa activity exhibited similar dose-dependent responses to edoxaban in the different age groups. The reduction of thrombin peak, the most edoxaban-sensitive TGA parameter, was similar in adults and children, but for the youngest group (<2 year-old) where the peak value reduction (median [Q1-Q3]) was higher than in adults (51% [44-59] versus 40% [32-46], p < 0.01; 74% [63-80] versus 65% [58-70], p < 0.05; and 84% [73-88] versus 76% [70-80], p < 0.05 for 50, 150 and 300 ng/mL edoxaban, respectively).

CONCLUSIONS

Edoxaban in vitro effect are comparable in children and adults except in the <2-year-old group.

Mass Transfers in a Fluidized Bed Bioreactor using Alginate Beads for a Future Bioartificial Liver

Fluidized bed bioreactor with alginate beads may be an alternative to hollow fiber cartridge to host hepatocytes for bioartificial liver purposes. After the bioreactor design and the characterization of fluid mechanics, the present study was aimed at analyzing bi-directional mass transfers of calibrated species between external fluid and empty beads. Static (batch) and dynamic (fluidized bed bioreactor) experimental conditions were analyzed. A simple modelling approach permitted the definition of mass transfer coefficients.

The motion of beads within the bioreactor clearly enhanced mass transfer kinetics, but did not alter the amount exchanged. The shear enhanced diffusion coefficient for VitB12 was 20 times higher in the fluidized bed bioreactor than under batch conditions, proving the efficiency of such a device.

Cholangiohepatitis in Dairy Cattle: 13 Cases

Background

The signalment, clinicopathologic, bacteriological, histopathological, ultrasonographic characteristics, and the treatment and outcomes of adult cattle with cholangiohepatitis are poorly defined.

Animals

Thirteen Holstein cows with cholangiohepatitis.

Methods

Retrospective study of medical records of cattle admitted to the CHUV and the AVC between 1992 and 2012 and 2000 and 2012, respectively, for cattle older than 3 months of age with a histopathological diagnosis of cholangiohepatitis. Cholangiohepatitis was defined as the presence of portal inflammation surrounding or infiltrating bile ducts, with or without epithelial damage, and extending into the adjacent lobules.

Results

At the time of diagnosis of cholangiohepatitis, cows had decreased appetite (n = 7) or were anorectic (n = 6), had fever (n = 5), and had tachycardia (n = 8). Icterus was detected in 5 cows. Yellow discoloration was identified on the skin of the udder (n = 3), conjunctiva (n = 2), and vulva (n = 1). There was leukocytosis (n = 6), neutrophilia (n = 9), and hyperfibrinogenemia (n = 8). Alteration in the serum biochemistry profile included hyperglobulinemia (n = 8), hypoalbuminemia (n = 10), increased activity of GGT (n = 12), AST (n = 8), and ALP (n = 10), and hyperbilirubinemia (n = 10). Histopathological diagnosis included mild, subacute, nonsuppurative cholangiohepatitis (n = 4), mild suppurative cholangiohepatitis (n = 4), mild mixed (neutrophilic and lymphocytic) cholangiohepatitis (n = 3), and moderate, chronic, nonsuppurative cholangiohepatitis (n = 1). Six cows were discharged from the hospital, and 7 were euthanized.

Conclusions and Clinical Importance

Cholangiohepatitis is a rare condition in adult cattle. Antemortem diagnosis can be challenging because clinical signs are unspecific.

Nutritional responses to acute training sessions in young elite rugby players

BACKGROUND

Acute exercise has been shown to induce nutritional adaptations in obese and lean inactive youth but it remains unclear whether youth with a high level of physical activity experience such exercise-induced energy intake and appetite modifications.

METHODS

14 (15- to 16-year-old) male elite rugby players completed sessions on three separate occasions: (1) a control session (CON); (2) an exercise session (EX) and; (3) a rugby session (RUGBY). The energy induced by the rugby and exercise sessions was matched (Polar Team2 pro technology), and participants' energy intake, food preferences (ad libitum buffet meals) and appetite feelings (Visual Analogue Scales) were assessed throughout the experimental days.

RESULTS

The energy intake during lunch and snack time was not different between conditions. Dinner time energy intake was significantly increased after RUBGY compared to CON with respectively 969 ± 145 kcal and 777 ± 183 kcal (p < 0.05). The energy intake at dinner time was significantly increased during EX (1185 ± 199 kcal) compared to both CON (p < 0.001) and RUGBY (p < 0.01). None of the appetite feelings investigated were modified between sessions.

CONCLUSION

Adolescent elite rugby players regulate their energy intake differently depending on the nature of their training; independently of the energy expended. This demonstrates the need for energetic and nutritional education to optimize their physical fitness and performance.

Effects of sports drinks on the maintenance of physical performance during 3 tennis matches: a randomized controlled study

Background

Tennis tournaments often involve playing several consecutive matches interspersed with short periods of recovery.

Objective

The objective of this study was firstly to assess the impact of several successive tennis matches on the physical performance of competitive players and secondly to evaluate the potential of sports drinks to minimize the fatigue induced by repeated matches.

Methods

This was a crossover, randomized controlled study. Eight male regionally-ranked tennis players participated in this study. Players underwent a series of physical tests to assess their strength, speed, power and endurance following the completion of three tennis matches each of two hours duration played over three consecutive half-days (1.5 day period for each condition). In the first condition the players consumed a sports drink before, during and after each match; in the second, they drank an identical volume of placebo water. The results obtained were compared with the third ‘rest’ condition in which the subjects did not play any tennis. Main outcomes measured were maximal isometric strength and fatigability of knee and elbow extensors, 20-m sprint speed, jumping height, specific repeated sprint ability test and hand grip strength.

Results

The physical test results for the lower limbs showed no significant differences between the three conditions. Conversely, on the upper limbs the EMG data showed greater fatigue of the triceps brachii in the placebo condition compared to the rest condition, while the ingestion of sports drinks attenuated this fatigue.

Conclusions

This study has demonstrated for the first time that, when tennis players are adequately hydrated and ingest balanced meals between matches, then no large drop in physical performance is observed even during consecutive competitive matches.

Trial registration

ClinicalTrials.gov: NCT01353872.

Preoperative cow-side lactatemia measurement predicts negative outcome in Holstein dairy cattle with right abomasal disorders

The objectives of the current study were (1) to determine the gain in prognostic accuracy of preoperative l-lactate concentration (LAC) measured on farm on cows with right displaced abomasum (RDA) or abomasal volvulus (AV) for predicting negative outcome; and (2) to suggest clinically relevant thresholds for such use. A cohort of 102 cows with on-farm surgical diagnostic of RDA or AV was obtained from June 2009 through December 2011. Blood was drawn from coccygeal vessels before surgery and plasma LAC was immediately measured by using a portable clinical analyzer. Dairy producers were interviewed by phone 30 d following surgery and the outcome was determined: a positive outcome if the owner was satisfied of the overall evolution 30 d postoperatively, and a negative outcome if the cow was culled, died, or if the owner reported being unsatisfied 30 d postoperatively. The area under the curve of the receiver operating characteristic curve for LAC was 0.92 and was significantly greater than the area under the curve of the receiver operating characteristic curve of heart rate (HR; 0.77), indicating that LAC, in general, performed better than HR to predict a negative outcome. Furthermore, the ability to predict a negative outcome was significantly improved when LAC measurement was considered in addition to the already available HR data (area under the curve: 0.93 and 95% confidence interval: 0.87, 0.99). Important inflection points of the misclassification cost term function were noted at thresholds of 2 and 6 mmol/L, suggesting the potential utility of these cut-points. The 2 and 6 mmol/L thresholds had a sensitivity, specificity, positive predictive value, and negative predictive value for predicting a negative outcome of 76.2, 82.7, 53.3, and 93.1%, and of 28.6, 97.5, 75, and 84%, respectively. In terms of clinical interpretation, LAC ≤2 mmol/L appeared to be a good indicator of positive outcome and could be used to support a surgical treatment decision. The treatment decision for cows with LAC between 2 and 6 mmol/L, however, would depend on the economic context and the owner's attitude to risk in regard to potential return on its investment. Finally, performing a surgical correction on commercial cows with RDA or AV and a LAC ≥6 mmol/L appeared to be unjustified and these animals should be culled based on their high probability of negative outcome.

Are eating habits associated with physical fitness in primary school children?

OBJECTIVE

Children's eating habits have mainly been related to anthropometric characteristics but less is known about their association with physical fitness.

METHODS

278 French school children (131 boys and 147 girls) filled in eating habit questionnaires and completed anthropometric measurement (weight, height, skinfolds) and physical fitness tests. The 20-m Shuttle run test and the Squat Jump test were used to assess aerobic fitness and anaerobic (lower limb muscle power) fitness respectively.

RESULTS

Breakfast consumption was associated with both aerobic fitness (p<0.05) and lower limb muscle power (p<0.01) while snacking was negatively related to Squat Jump performances (p<0.05). There was no association between physical fitness and either the type of the consumed-beverages or TV watching during dinner and lunch meals. Cumulated unhealthy eating habits was negatively associated with CRF stages and lower limb muscle power performances (p<0.05).

CONCLUSION

French primary school children physical fitness is associated with their eating habits and decreases with the number of unhealthy eating behaviors cumulated.

[Megakaryoblastic acute leukemia: bone and joint manifestations in a 7-month-old child]

Acute megakaryoblastic leukemia accounts for approximately 3-10% of acute myeloid leukemia in children. Its diagnosis may be difficult because of associated myelofibrosis. We report the case of a 7-month-old child who presented hepatomegaly with bicytopenia. She also developed bone and joint pain with recurrent aseptic arthritis. We suggested the diagnosis of megakaryoblastic leukemia early but multiple bone marrow investigations had been processed without positive results because of sampling problems and lack of abnormal cells in the morphological, phenotypic, and cytogenetic examinations. We had a variety of indirect evidence for our assumption: the x-ray showing periosteal new bone, lytic lesions and metaphyseal bands, bone marrow aspirate smears with micromegakaryocytes, and bone marrow biopsy suggesting myelofibrosis. This was very suggestive of leukemia but we could not prove it and we finally found megakaryoblasts on bone marrow aspirate smears after more than 2 months of investigation and initiated a course of corticosteroids.

A case of infantile de novo primary antiphospholipid syndrome revealed by a neonatal arterial ischemic stroke

The few cases of antiphospholipid syndrome that have been reported in neonates are believed to have resulted from a transplacental transfer of antiphospholipid antibodies. Here we report on a boy with a neonatal stroke revealing a de novo primary antiphospholipid, the mother being free of antiphospholipid antibodies. Other thrombosis risk factors included primiparity, gestational diabetes, macrosomia, polyglobulia, and lipoprotein(a) >30 mg/dL. Anti-cardiolipin and anti-β(2)-glycoprotein I persisted more than 2 years. Under aspirin therapy, the child did not exhibit recurrence of thrombotic events or symptoms of autoimmunity after a follow-up of 3 years. Our case indicates that clinicians should consider a second retesting for anticardiolipin antibodies and anti-β(2)-glycoprotein I antibodies, even when children and mother neonatal tests are negative.

Treatment of metabolic syndrome by combination of physical activity and diet needs an optimal protein intake: a randomized controlled trial

BACKGROUND

The recommended dietary allowance (RDA) for protein intake has been set at 1.0-1.3 g/kg/day for senior. To date, no consensus exists on the lower threshold intake (LTI = RDA/1.3) for the protein intake (PI) needed in senior patients ongoing both combined caloric restriction and physical activity treatment for metabolic syndrome. Considering that age, caloric restriction and exercise are three increasing factors of protein need, this study was dedicated to determine the minimal PI in this situation, through the determination of albuminemia that is the blood marker of protein homeostasis.

METHODS

Twenty eight subjects (19 M, 9 F, 61.8 ± 6.5 years, BMI 33.4 ± 4.1 kg/m²) with metabolic syndrome completed a three-week residential programme (Day 0 to Day 21) controlled for nutrition (energy balance of -500 kcal/day) and physical activity (3.5 hours/day). Patients were randomly assigned in two groups: Normal-PI (NPI: 1.0 g/kg/day) and High-PI (HPI: 1.2 g/kg/day). Then, patients returned home and were followed for six months. Albuminemia was measured at D0, D21, D90 and D180.

RESULTS

At baseline, PI was spontaneously 1.0 g/kg/day for both groups. Albuminemia was 40.6 g/l for NPI and 40.8 g/l for HPI. A marginal protein under-nutrition appeared in NPI with a decreased albuminemia at D90 below 35 g/l (34.3 versus 41.5 g/l for HPI, p < 0.05), whereas albuminemia remained stable in HPI.

CONCLUSION

During the treatment based on restricted diet and exercise in senior people with metabolic syndrome, the lower threshold intake for protein must be set at 1.2 g/kg/day to maintain blood protein homeostasis.

Risk factors associated with transmission of Mycobacterium avium subsp. paratuberculosis to calves within dairy herd: a systematic review

BACKGROUND

Paratuberculosis has a worldwide distribution and many countries have implemented control programs to prevent transmission among and within herds. For these programs to be efficient, knowledge of the risk factors involved in transmission is essential.

OBJECTIVES

Systematically review the scientific literature concerning risk factors associated with Mycobacterium avium subsp. paratuberculosis (MAP) transmission to dairy calves.

STUDY DESIGN

Systematic review.

METHODS

An electronic search was done in PubMed and CAB to retrieve references relevant to answer at least 1 of the 5 questions concerning neonatal environment, colostrum, milk, housing of calves, and contact of calves with adult cow feces as risk factors in MAP transmission. A 1st screening was done using titles only, then abstracts, and finally full-length articles were reviewed for relevance. From the articles selected, risk factors and presence of a significant association between these risk factors and MAP transmission were recorded.

RESULTS

Twenty-three articles from 11 different countries and published in 12 different journals were reviewed. The most common study design was cross-sectional (n = 16). The case definition and diagnostic tests used were very variable among studies, but serum ELISA was used in most studies (n = 14). The study unit was the herd in 18 studies.

CONCLUSIONS AND CLINICAL IMPORTANCE

The contact of calves with adult cow feces is the most important risk factor in MAP transmission. The 5 categories of risk factors are linked to one another.

Effect of a 6-month school-based physical activity program on body composition and physical fitness in lean and obese schoolchildren

Few studies have investigated the impact of school-based physical activity interventions on anthropometric characteristics concomitantly with aerobic and anaerobic capacities in young children. The present study aimed to assess the effect of a 6-month physical activity program on body composition and physical fitness among primary schoolchildren. Four hundred fifty-seven children aged 6 to 10 years were randomly assigned to the intervention group (229 children) or observational group (228 children). Participants' height and weight were assessed, and obesity was determined using French reference curves for BMI. The sum of the four skinfolds and fat-free mass were determined. Ground tests were used to assess aerobic (20-m shuttle run test) and anaerobic (cycling peak power) fitness before and after a 6-month physical activity intervention. The anthropometric modifications obtained over the 6 months cannot be attributed to the intervention as the ANOVA revealed no group effect (intervention vs. group). However, anaerobic and aerobic fitness were significantly improved, thanks to the program in both lean and obese children. A 6-month school-based physical activity intervention in 6- to 10-year-old children did not yield positive anthropometric improvements, but appears effective in terms of aerobic and anaerobic physical fitness. Two physical activity sessions per week in addition to standard physical education classes in primary schoolchildren bring effective results for the prevention of childhood obesity.

Blood lipids and adipokines concentrations during a 6-month nutritional and physical activity intervention for metabolic syndrome treatment

Background

To report changes in body weight, total and central fat mass, metabolic, hormonal and inflammatory parameters in overweight people who participated in a six months weight loss intervention associating diet management and exercise.

Subjects and Methods

Fourteen subjects (10 M, 4 F, mean age 62.9 ± 6.9 years, BMI 30.4+/- 3.8 kg/m²) presenting the characteristics of the Metabolic Syndrome (MS) were included in the survey. They followed a three weeks (D0 to D20) cure in a medical establishment and a six months (D20 to M3 and M6) follow up at home. During the cure, they receive a balanced diet corresponding to 500 Kcal deficit vs their dayly energy expenditure (DEE) and they exercised 2 to 3 hours per day.

At D0, D20, M3 and M6, body composition (lean mass, total and central fat mass) was analyzed with DEXA, blood pressure was taken and blood was collected to evaluate glycaemia, triglycerides, total, LDL and HDL cholesterol, insulin, leptin and adiponectin levels, CRP and pro-inflammatory interleukines IL1, IL.6 and TNFalpha.

Results

All parameters listed above except the cytokine were improved at D20, so that 4 subjects among 14 still presented the MS. After returning to home, these parameters remained stable.

Conclusion

The efficacy of therapeutic lifestyle modifications with education and exercise and diet was demonstrated, but the compliance to the new healthy lifestyle initiated during the cure was not optimal.

The impact of eating habits on anthropometric characteristics in French primary school children

BACKGROUND

Obesity is increasing worldwide, reaching alarming proportions. Eating habits have changed over time and nowadays children and adolescents' environment favours the adoption of unhealthy eating behaviours leading to metabolic impairment.

OBJECTIVE

To explore the impact of eating risk factors and their cumulative effect on anthropometric characteristics in French primary school children.

METHODS

A total of 278 healthy French children (7.50 ± 0.67 years old) and their legal representatives agreed to take part in this study. Parents were asked to fill in an eating habits clinical questionnaire with questions about skipping breakfast, snacking between meals, eating in front of the TV and sugar-sweetened beverage consumption. On the basis of the answers, children were classified into four categories as a function of the number of eating risk factors they presented. Body mass index (BMI), the sum of four skinfolds (Σ4 skinfolds: tricipital, bicipital, sub-scapular and supra-iliac) and waist circumference (WC) were measured. BMI was transformed into z-BMI for each child.

RESULTS

ANOVA and unpaired t-test provided significantly higher z-BMI, Σ4 skinfolds and WC in children who were used to skipping breakfast, snacking, watching TV while eating and consuming sugar-sweetened beverages. The more children accumulated eating risk factors, the higher were their z-BMI, Σ4 skinfolds and WC (MANOVA: P < 0.001).

CONCLUSIONS

Eating habits appear to be associated with anthropometric characteristics in French primary school children. Anthropometric values (z-BMI, Σ4 skinfolds and WC) increased with the number of eating risk factors they presented.

Squat jump performance during growth in both sexes: comparison with cycling power

The purpose of this cross-sectional study was to investigate leg muscle power and compare two activities (jumping and cycling) in 383 girls and 407 boys ages 9-19 years. Results in anthropometric characteristics and jumping performance were comparable until midadolescence, and sex differences were observed. Lean leg volume (LLV) was the reason for most of the variance (76% in girls and 88% in boys) in jumping performance. However the LLV exponent was higher than expected in boys but not girls. Therefore, unidentified qualitative changes of muscle function during growth in boys must be considered. The squat jump index (SJI) was highly correlated to cycling peak power (CPP; N = 790, r = .94, p < .001). Although prediction error of CPP from SJI was less than 5% when considering each sex-and-age group, individual errors mounted to 40%. Due to its practicability, SJI is recommended in large-scale developmental prospective studies. However, cycling and jumping protocols are not interchangeable when measuring peak power values.

Cycling peak power in obese and lean 6- to 8-year-old girls and boys

The purpose of this study was to investigate the possible effect of the difference in percentage body fat (%BF) and fat-free mass (FFM) on cycling peak power (CPP) in 6- to 8-year-old obese and lean untrained girls and boys. Obese (35 girls, 35 boys) and lean (35 girls, 35 boys) children were measured for obesity, %BF, calculated from skinfold measurements. FFM was calculated as body mass (BM) minus body fat. A force–velocity test on a cycle ergometer was used to measure CPP. CPP was related to anthropometric variables using standard and allometric models. CPP in absolute terms was higher in obese children than in lean children irrespective of gender. BM-related CPP was significantly lower in obese children than in lean ones, whereas no effect of obesity appeared on FFM-related CPP. Velocity at CPP (Vopt) was significantly lower and force at CPP (Fopt) was significantly higher in girls than in boys. Muscle power production was unaffected by obesity in children. Low BM-related CPP could explain the difficulty of taking up physical activities that are body-mass related in obese children. Gender difference for Vopt and Fopt shows that girls and boys may have different maturation patterns affecting CPP.

Upper Body Contribution During Leg Cycling Peak Power in Teenage Boys and Girls

This study investigated gender differences in upper-body contribution to cycle muscle power in 23 adolescents. All subjects performed two 5-s and one 20-s cycling sprint, using two protocols: with handgrip (WG) and without handgrip (WOG). Maximal handgrip strength was assessed for each individual. Absolute peak and mean cycling power was corrected for total fat-free mass (FFM) and for lean leg volume (LLV). Males showed higher cycling performance than females. Peak power and 20-s mean power (flywheel inertia included), but not optimal velocity, were higher WG than WOG. Especially for peak power, absolute differences between both protocols were higher in males than in females, and were significantly related to handgrip strength. The significant contribution of the upper body suggested that, for standardisation of cycle muscle power, total FFM is a more relevant variable compared with LLV. Furthermore, in adolescents, the higher contribution of the upper body musculature in males partly explained gender differences in peak power.

Purpura thrombotique thrombocytopénique acquis auto-immun chez l'enfant : à propos d'1 cas

Thrombotic thrombocytopenic purpura (TTP), when accompanied by regenerative anaemia with schizocytosis, thrombopenia and neurological manifestations, is a disease whose main characteristic is the absence of the von Willebrand factor (vWF) cleaving protease. The two types of TTP are distinguishable by the presence or absence of antiprotease inhibitors, which are, respectively, either acquired or constitutional. The acquired autoimmune form is most frequently observed in adults.

OBSERVATION

An adolescent with a previous history of moderate, isolated thrombopenia first showed symptoms of TTP at the age of 14. Positive antiprotease inhibitors in combination with a degeneration of protease activity confirmed the diagnosis of acquired autoimmune TTP. A treatment consisting of daily plasma exchange led to rapid improvement; however, a failed attempt to space out plasma exchanges necessitated the introduction of 4 weekly injections of Rituximab beginning on day 40, which was successful. Indeed, since the second injection of Rituximab on day 51, the number of platelets stabilized at a normal level, thereby allowing for the complete cessation of plasma exchange. At this writing - day 89 - the patient remains in persistent remission.

CONCLUSION

Given the different therapeutic and prognostic implications of the 2 types of TTP in child patients, it is mandatory to end at an accurate biological diagnosis: whereas the constitutional form is effectively treated with plasma injections, the acquired form, while initially requiring plasma exchange, often necessitates the use of immunosuppressors during acute or relapse phase. The present study concerns a paediatric case of acquired TTP treated successfully with Rituximab during an acute dependant phase.

Gender differences in peak muscle performance during growth

Gender-related differences in maximal leg muscle power were examined in 496 females and 426 males aged 8 to 20 years. Cycling peak power (CPP, including the force required to accelerate the flywheel of the cycle ergometer) was measured during three sprints. Optimal velocity (Vopt, velocity at CPP) was also determined. No gender-differences were observed in anthropometric characteristics and cycling performance between 8- and 14-year-old. From age 14, however, males showed a higher CPP than females, but also a higher lean leg volume (LLV, assessed by anthropometry). Allometric relationship between CPP and LLV (CPP = a . LLV ( b)) showed a clear gender-differentiation between 14- and 16-year-old: LLV exponent (b) was 1.05 in males vs. 0.74 in females. From 16 years onwards, analysis of covariance (ANCOVA) showed that the slopes of the CPP-LLV relationship were similar in both genders, but the intercepts differed. In other words, for a similar LLV, males showed greater CPP than females. It was suggested that this sex-related difference was due to total body fat increase, and more specifically lower-limb fat increase during puberty in girls, whilst the boys experienced increased lean body mass. Considering that the same gender-related difference was observed for optimal velocity adjusted for leg length, other factors such as fibre type variability or (and) neuromuscular activation might also be partly responsible for the higher peak muscle performance observed in males.

Modalities of submaximal exercises on ratings of perceived exertion by young girls: a pilot study

This pilot study compared the rating of perceived exertion scores (RPE) in young girls for two modalities of exercises (running vs cycling) performed at the same absolute heart rate. 23 girls, ages 8 to 11 years, from a gymnastic club performed graded, intermittent, and submaximal running and cycling exercises at a similar absolute heart rate (+/-5 bpm). These exercises consisted of three stages of 3 min. duration separated by 1-min. recovery intervals. RPE was estimated using the Children's Effort Rating Table scale at the end of each stage of each exercise. Mean ratings were only significantly different during cycling, compared to running for the Stage 3 (cycling 5.3+/-2.7 and running 7.0+/-1.9, p < .05). During low exercise intensity, measured as heart rate, the modality of exercise does not seem to affect RPE. In contrast, with high heart rates, RPE are higher during cycling than running, so it is necessary to take account of the type of exercise.

Short-term peak power changes in adolescents of similar anthropometric characteristics

PURPOSE

The present study was undertaken to examine changes of cycling peak power (P(max)), optimal pedaling frequency (Vopt), and optimal pedaling force (Fopt) with age in subjects with the same lean leg volume (LLV), leg length (LL), and percentage body fat (%BF).

METHOD

A total of 132 males aged 9.5-16.5 volunteered for this study. The population was divided into prepubertal (G1), pubertal (G2), and postpubertal (G3) groups. Within G1, G2, and G3, although the subjects were divided into three different age subgroups, there were no significant differences for LLV, %BF, and LL.

RESULTS

Results showed that within G1, G2, and G3, P(max) increased significantly with age. Optimal velocity (Vopt) increased significantly with age in G1, whereas optimal force (Fopt) increased significantly with age into the other groups (G2 and G3).

CONCLUSION

This study demonstrated that when anthropometric characteristics were controlled (LLV, LL, and %BF), P(max) and its two components (Vopt and Fopt) still increased with age. This indicates that other factors of qualitative nature have to be considered when determining P(max), Vopt, and Fopt.

Measurement error in short-term power testing in young people

The aim of this study was to examine the consistency or reproducibility of measuring cycling peak power in children and adults. Twenty-seven pre-pubertal girls and boys and 27 female and male physical education students (age 9.8 +/- 0.5 and 24.4 +/- 4.3 years, respectively; mean +/- s) participated in the study. All participants performed five tests over 15 days and underwent a habituation session before the study. Each test included four sprints against four different braking forces. We found that braking forces of 7.5% of body weight in children and 10% of body weight in adults were too high for most of the participants to elicit maximal cycling power. Unlike the children, the physical education students improved their performance between session 1 and session 2 (1025 +/- 219 vs 1069 +/- 243 W; P < 0.001). Therefore, to obtain reproducible measures of cycling peak power, a habituation session including a complete test protocol (i.e. warm-up plus three sprints) is highly recommended. When the protocol included three sprints in children and at least two sprints in adults, measurement of cycling peak power was found to be highly reliable (test-retest coefficient of variation approximately 3%). Finally, to avoid performance fluctuations, especially over several consecutive evaluations (e.g. longitudinal studies), it is necessary to maintain high motivation in children.

Peak power in obese and nonobese adolescents: effects of gender and braking force

PURPOSE

The aim of this study was to determine the cycling peak power (CPP) of obese compared with nonobese adolescents and to identify possible effects of braking force (BF) and gender on CPP. To adjust for differences in body size, we used ratio standard and allometric model.

METHODS

Obese (26 girls, 18 boys) and nonobese (30 girls, 20 boys) adolescents participated. Fat-free mass (FFM) was determined by dual-energy x-ray absorptiometry (DEXA) in obese and by anthropometric method in nonobese groups. A force-velocity test was used to measure peak power (flywheel inertia included) for BF corresponding to applied load: 25, 50, and 75 g x kg(-1) body mass (BM). The highest peak power was defined as CPP.

RESULTS

CPP was independent of BF in nonobese adolescents but dependent in obese adolescents. The optimal braking load is approximately 6.5% FFM. Absolute CPP was higher in obese than nonobese adolescents. Related to BM, CPP was significantly lower in obese than nonobese adolescents, using the standard ratio or the allometric model. These differences disappeared when CPP was related to FFM. Multiple stepwise regression showed that FFM was the most important explanatory variable of the variance of CPP (72%) in obese and nonobese adolescents. No significant difference between obese and nonobese adolescents occurred when Fopt was related to FFM (standard or power function ratios used). There was no gender effect on CPP, and the manner of expressing CPP did not affect the results. However, girls showed a higher FFM-related Fopt than boys, using standard and power function ratios.

CONCLUSION

There was no significant difference between obese and nonobese girls and boys for anaerobic performance (CPP and Fopt) when FFM was taken into account.

Short-term muscle power during growth and maturation

During growth and maturation, the study of very brief high-intensity exercise has not received the same attention from researchers as, for instance, aerobic function. In anaerobic tasks or sports events such as sprint cycling, jumping or running, the children's performance is distinctly lower than that of adults. This partly reflects children's lesser ability to generate mechanical energy from chemical energy sources during short-term intensive activity. For many years, various attempts have been made to quantify the anaerobic energy yield in maximal-intensity exercise, but many assumptions have had to be made with respect to mechanical efficiency, lactate turnover, dilution space for lactate, and so on. During childhood and adolescence, direct measurements of the rate or capacity of anaerobic pathways for energy turnover presents several ethical and methodological difficulties. Thus, rather than measure energy supply, paediatric exercise scientists have concentrated on measuring short-term muscle power (STMP) by means of standardised tests. Previously, investigators have used various protocols such as short-term cycling power tests, vertical jump tests or running tests. Cycling ergometer tests are the most common. There is, however, no ideal test, and so it is important to acknowledge the limitations of each test. Progress has been made in assessing instantaneous cycling STMP from a single exercise bout. Several investigators have reported STMP increases with age and have suggested that late pubertal period may accentuate anaerobic glycolysis. Mass-related STMP was shown to increase dramatically during childhood and adolescence, whereas the corresponding increase in peak blood lactate was considerably lower. The latter results support the hypothesis that the difference observed between children and adolescents during STMP testing is more related to neuromuscular factors, hormonal factors and improved motor coordination, rather than being an indicator of reduced lactate-producing glycolysis mechanism. Evidence suggesting a causal link between the ability to generate lactate during exercise and sexual maturation is weak. Despite the majority of research being focused on short-term power output, the study of anaerobic function warrants more investigation. Spectacular progress is being made at the moment in the development of molecular biology tools that can be used in, for example, the genetic dissection of human performance phenotypes. Noninvasive power tools like magnetic resonance imaging and magnetic resonance spectroscopy are presently used to determine possible differences in phosphorus compounds between fast and slow fibre types. Undoubtedly these tools will lead to more information in the near future regarding STMP capabilities of the growing child.

Effects of age and recovery duration on peak power output during repeated cycling sprints

The aim of the present study was to investigate the effects of age and recovery duration on the time course of cycling peak power and blood lactate concentration ([La]) during repeated bouts of short-term high-intensity exercise. Eleven prepubescent boys (9.6 +/- 0.7 yr), nine pubescent boys (15.0 +/- 0.7 yr) and ten men (20.4 +/- 0.8 yr) performed ten consecutive 10 s cycling sprints separated by either 30 s (R30), 1 min (R1), or 5 min (R5) passive recovery intervals against a friction load corresponding to 50 % of their optimal force (50 % Ffopt). Peak power produced at 50 % Ffopt (PP50) was calculated at each sprint including the flywheel inertia of the bicycle. Arterialized capillary blood samples were collected at rest and during the sprint exercises to measure the time course of [La]. In the prepubescent boys, whatever recovery intervals, PP50 remained unchanged during the ten 10 s sprint exercises. In the pubescent boys, PP50 decreased significantly by 18.5 % (p < 0.001) with R30 and by 15.3 % (p < 0.01) with R1 from the first to the tenth sprint but remained unchanged with R5. In the men, PP50 decreased respectively by 28.5 % (p < 0.001) and 11.3 % (p < 0.01) with R30 and R1 and slightly diminished with R5. For each recovery interval, the increase in blood [La] over the ten sprints was significantly lower in the prepubescent boys compared with the pubescent boys and the men. To conclude, the prepubescent boys sustained their PP50 during the ten 10 s sprint exercises with only 30 s recovery intervals. In contrast, the pubescent boys and the men needed 5 min recovery intervals. It was suggested that the faster recovery of PP50 in the prepubescent boys was due to their lower muscle glycolytic activity and their higher muscle oxidative capacity allowing a faster resynthesis in phosphocreatine.

Anaerobic cycling performance characteristics in prepubescent, adolescent and young adult females

The purpose of this study was to determine whether the relationships between short-term power and body dimensions in young females were similar whatever the age of the individuals. A cohort of 189 prepubescent (mean age 9.5 years), adolescent (mean age 14.4 years) and young adult (mean age 18.2 years) females performed three all-out sprints on a friction-loaded cycle ergometer against three braking forces corresponding to applied loads of 25, 50 and 75 g.kg-1 body mass (BM). For each sprint, peak power including flywheel inertia was calculated. Results showed that a braking load of 75 g.kg-1 BM was too high for prepubescent and adolescent girls. Therefore, when measuring short-term cycling performance in heterogeneous female populations, a braking load of 50 g.kg-1 BM (0.495 N.kg-1 BM) is recommended. During growth, cycling peak power (CPP; defined as the highest peak power obtained during the three sprints) increased, as did total BM, fat-free mass (FFM) and lean leg volume (LLV) (P < 0.001). Analysis of covariance revealed that the slopes of the linear relationships between CPP and biometric characteristics were similar in the three groups (P > 0.7 for the CPP/BM and CPP/FFM relationships, and P > 0.2 for the CPP/LLV relationship). However, the adjusted means were always significantly higher in young women (P < 0.001) compared with both of the other groups. Although differences in performance during anaerobic cycling in growing females are primarily dependent upon body dimensions, other as yet undetermined factors may be involved during late adolescence.

Design of a fluidized bed bioartificial liver

The aim of this study was to design a bioreactor for extracorporeal liver supply containing alginate beads in a fluidized bed regimen. The objective was to achieve a satisfactory mixing into the bioreactor to promote the potential exchanges and mass transfers. First, we checked whether both present phases (solid: alginate beads; liquid: saline solution at 20 degrees C) might allow for this fluidization. Then the optimal design was defined as a function of the required operating conditions, bead volume, and perfusion flow rate; the bioreactor cross section and height especially needed to be adjusted. The efficient fluidization, under optimized conditions, was proven through the follow-up of the head losses generated by the fluidized bed. Criteria for scaling up were also determined.

Dimensional changes cannot account for all differences in short-term cycling power during growth

The purpose of this study was to determine to what extent anthropometric characteristics account for cycling peak power during growth. Five hundred and six male subjects aged 7.5-18 years performed three brief maximal sprints on a friction-loaded cycle ergometer. Cycling peak power (CPP) was calculated including the flywheel inertia of the device. Fat-free mass (FFM) and lean leg volume (LLV) were assessed by anthropometry. Anthropometric characteristics increased significantly during growth (p<0.001) but plateaued from about 16 years of age (p > 0.3). The same pattern was observed for CPP, while the time to reach CPP decreased during growth. CPP correlated as highly with LLV as with FFM and both parameters may therefore be interchanged. However, in non weight-bearing exercises, such as cycling, it seems more relevant to "normalise" leg power for LLV. Multiple stepwise regression, using an allometric model, showed that a large part of the variance of CPP was explained by LLV (88.2%, p<0.001). However, age and time to reach peak power also contributed significantly (approximately 3 %, p < 0.001). The prediction of CPP revealed that FFM and age contributed to 92.2% of the total variance of CPP. Because of its practicability, fat-free mass is particularly useful in prospective studies. Although the effects of dimensional changes in CPP during growth are obvious, undetermined qualitative changes of muscle function during maturation must be considered.

Testing peak cycling performance: effects of braking force during growth

The purpose of this study was to investigate the relationship between cycling peak power (CPP; flywheel inertia included) and the applied braking force (F(B)) on a friction-loaded cycle ergometer in male children, adolescents, and adults. A total of 520 male subjects aged 8-20 yr performed three brief maximal sprints against three F(B): 0.245, 0.491, and 0.736 N x kg(-1) body mass (BM) (corresponding applied loads: 25 [F(B)25], 50 [F(B)50], and 75 [F(B)75] g x kg(-1) BM). For each F(B), peak power (PP) was measured (PP25, PP50 and PP75). For each subject, the highest PP was defined as CPP. Results showed that PP was dependent on F(B). In young adults PP25 underestimated CPP by more than 10%, and consequently, F(B)25 seemed to be too low for this population. However, in children, PP75 underestimated CPP by about 20%. A F(B) of 0.736 N x kg(-1) BM was definitively too high for the pediatric population. Therefore, the optimal F(B), even corrected for BM, was lower in children than in adults. The influence of growth and maturation on the force-generating capacity of the leg muscles may explain this difference. In this study, however, it was shown that the difference between PP50 and CPP was independent of age for the whole population investigated. Consequently, when flywheel inertia is included, one cycling sprint with a F(B) of 0.495 N x kg(-1) BM (corresponding applied load: 50 g x kg(-1) BM) is a feasible method for testing both children, adolescents, or young adults.

A new concept of bioartificial liver based on a fluidized bed bioreactor

Many bioartificial livers have been developed, but most of them suffer from difficulty when being scaled up and from poor efficiency of mass transfer between the plasma and the immobilized hepatocytes. We present a new concept of bioartificial liver based on the fluidized bed motion of hepatocytes entrapped in alginate beads. The bioreactor is designed to offer stable behavior. The maximum fluid perfusion velocity is determined to avoid any bead release from the bioreactor. The fluidized bed height depends on the amount of beads and the velocity employed. Under the optimized operating conditions, the mass transfer between perfusion fluid and beads is very efficient; only 10 min are necessary to reach concentration equilibrium. Hence, this fluidized bed bioartificial liver appears to be a promising tool for a liver support system in the treatment of acute liver failure.

Development of obesity in Zucker rats. Early insulin resistance in muscles but normal sensitivity in white adipose tissue

Euglycemic-hyperinsulinemic clamps were performed on 4- and 12-wk-old anesthetized lean and obese Zucker rats. During the clamp studies, total glucose production and utilization were assessed with a 3-[3H]glucose perfusion, whereas local glucose utilization was determined by measuring 2-deoxy-1-[3H]glucose 6-phosphate accumulation in various tissues. In the basal state, 4 wk-old obese rats were hyperinsulinemic (159 +/- 8 vs. 82 +/- 9 microU/ml), whereas glucose turnover rate was similar to that observed in lean rats (14.9 +/- 1.9 vs. 12.5 +/- 1.9 mg X min-1 X kg-1). Glucose utilization was identical in skeletal muscles, whereas it was increased in white adipose tissue of obese rats (22 +/- 4 vs. 8 +/- 2 ng X min-1 X mg-1). At plasma insulin level of 500 microU/ml, glucose production was totally suppressed in both groups, whereas overall glucose utilization was slightly less in 4-wk-old obese than in lean rats. This was due to a reduced stimulation of glucose utilization in skeletal muscles and brown adipose tissue. In contrast, glucose utilization in periovarian white adipose tissue was similarly increased in lean and obese rats. For a maximal insulin concentration (1500 microU/ml), all the differences were abolished between lean and obese young Zucker rats. In older (12-wk-old) obese rats, glucose utilization in various tissues was markedly reduced at maximal insulin level compared with that observed in age-matched lean animals.(ABSTRACT TRUNCATED AT 250 WORDS)