A. De Lorenzo

Hormonal responses to whole-body vibration in men

Abstract The aim of this study was to evaluate the acute responses of blood hormone concentrations and neuromuscular performance following whole-body vibration (WBV) treatment. Fourteen male subjects [mean (SD) age 25 (4.6) years] were exposed to vertical sinusoidal WBV, 10 times for 60 s, with 60 s rest between the vibration sets (a rest period lasting 6 min was allowed after 5 vibration sets). Neuromuscular performance tests consisting of counter-movement jumps and maximal dynamic leg presses on a slide machine, performed with an extra load of 160% of the subjects body mass, and with both legs were administered before and immediately after the WBV treatment. The average velocity, acceleration, average force, and power were calculated and the root mean square electromyogram (EMGrms) were recorded from the vastus lateralis and rectus femoris muscles simultaneously during the leg-press measurement. Blood samples were also collected, and plasma concentrations of testosterone (T), growth hormone (GH) and cortisol (C) were measured. The results showed a significant increase in the plasma concentration of T and GH, whereas C levels decreased. An increase in the mechanical power output of the leg extensor muscles was observed together with a reduction in EMGrms activity. Neuromuscular efficiency improved, as indicated by the decrease in the ratio between EMGrms and power. Jumping performance, which was measured using the counter-movement jump test, was also enhanced. Thus, it can be argued that the biological mechanism produced by vibration is similar to the effect produced by explosive power training (jumping and bouncing). The enhancement of explosive power could have been induced by an increase in the synchronisation activity of the motor units, and/or improved co-ordination of the synergistic muscles and increased inhibition of the antagonists. These results suggest that WBV treatment leads to acute responses of hormonal profile and neuromuscular performance. It is therefore likely that the effect of WBV treatment elicited a biological adaptation that is connected to a neural potentiation effect, similar to those reported to occur following resistance and explosive power training. In conclusion, it is suggested that WBV influences proprioceptive feedback mechanisms and specific neural components, leading to an improvement of neuromuscular performance. Moreover, since the hormonal responses, characterised by an increase in T and GH concentration and a decrease in C concentration, and the increase in neuromuscular effectiveness were simultaneous but independent, it is speculated that the two phenomena might have common underlying mechanisms.

The effect of oral administration of Lactobacillus GG on antibiotic‐associated gastrointestinal side‐effects during Helicobacter pylori eradication therapy

One‐week triple therapy is currently considered the golden standard against Helicobacter pylori. However, gastrointestinal side‐effects are among the major pitfalls in such regimens. Probiotic supplementation might help to prevent or reduce such drug‐related manifestations.

The validity of predicted body fat percentage from body mass index and from impedance in samples of five European populations

Objectives: To test and compare the validity of a body mass index (BMI)-based prediction equation and an impedance-based prediction equation for body fat percentage among various European population groups.Design: Cross-sectional observational study.Settings: The study was performed in five different European centres: Maastricht and Wageningen (The Netherlands), Milan and Rome (Italy) and Tampere (Finland), where body composition studies are routinely performed.Subjects: A total of 234 females and 182 males, aged 18–70 y, BMI 17.0–41.9 kg/m2.Methods: The reference method for body fat percentage (BF%REF) was either dual-energy X-ray absorptiometry (DXA) or densitometry (underwater weighing). Body fat percentage (BF%) was also predicted from BMI, age and sex (BF%BMI) or with a hand-held impedance analyser that uses in addition to arm impedance weight, height, age and sex as predictors (BF%IMP).Results: The overall mean (±s.e.) bias (measured minus predicted) for BF%BMI was 0.2±0.3 (NS) and−0.7±0.3 (NS) in females and males, respectively. The bias of BF%IMP was 0.2±0.2 (NS) and 1.0±0.4 (P<0.01) for females and males, respectively. There were significant differences in biases among the centres. The biases were correlated with level of BF% and with age. After correction for differences in age and BF% between the centres the bias of BF%BMI was not significantly different from zero in each centre and was not different among the centres anymore. The bias of BF%IMP decreased after correction and was significant from zero and significant from the other centres only in males from Tampere. Generally, individual biases can be high, leading to a considerably misclassification of obesity. The individual misclassification was generally higher with the BMI-based prediction.Conclusions: The prediction formulas give generally good estimates of BF% on a group level in the five population samples, except for the males from Tampere. More comparative studies should be conducted to get better insight in the generalisation of prediction methods and formulas. Individual results and classifications have to be interpreted with caution.European Journal of Clinical Nutrition (2001) 55, 973–979

Effect of Lactobacillus GG Supplementation on Antibiotic-Associated Gastrointestinal Side Effects during Helicobacter pylori Eradication Therapy: A Pilot Study

Background: One-week triple therapy is currently regarded as the reference of anti-Helicobacter pylori treatment. However, antibiotic-associated gastrointestinal side effects are among the major pitfalls of such regimens. Probiotic supplementation may be regarded as a therapeutic tool to prevent or reduce these troublesome drug-related manifestations. Aim: To determine whether the addition of the probiotic Lactobacillus GG to an anti-H. pylori standard triple therapy could help to prevent or minimize the occurrence of gastrointestinal side effects. Methods: One hundred and twenty healthy asymptomatic subjects screened positive for H. pylori infection and deciding to receive eradication therapy were randomized either to 1-week pantoprazole (40 mg b.i.d.), clarithromycin (500 mg b.i.d.), tinidazole (500 mg b.i.d.) or to the same regimen supplemented with Lactobacillus GG for 14 days. Patients filled in validated questionnaires during follow-up to determine the type and severity of side effects and to judge overall tolerability. Results: Bloating, diarrhea and taste disturbances were the most frequent side effects during the eradication week and were significantly reduced in the Lactobacillus GG-supplemented group (RR = 0.4, CI 0.2–0.8; RR = 0.3, CI 0.1–0.8; RR = 0.3, CI 0.1–0.7, respectively). The same pattern was observed throughout the follow-up period. Overall assessment of treatment tolerability showed a significant trend in favor of the Lactobacillus GG-supplemented group (p = 0.03). Conclusions:Lactobacillus GG supplementation beneficially affects H. pylori therapy-related side effects and overall treatment tolerance.

Extradigestive manifestations of Helicobacter pylori gastric infection

In the past year, several studies have been carried out on the association between Helicobacter pylori infection and a miscellany of extradigestive diseases, such as cardiovascular, immunological, and various other pathologies. In particular, a higher prevalence of H pylori infection in patients affected by ischaemic heart disease has been described and there is growing evidence for an association between H pylori and some autoimmune diseases. Moreover, recent studies have shown that various helicobacter species have been detected in human bile; if confirmed, this finding could revise the diagnostic and therapeutic approach to diseases of the biliary tract.

Review article: breath testing for human liver function assessment

Carbon‐labelled breath tests were proposed as tools for the evaluation of human liver function 30 years ago, but have never become part of clinical routine. One reason for this is the complex role of the liver in metabolic regulation, making it difficult to provide essential information for the management of patients with liver disease with a single test and to satisfy the hepatology community. As a result, a battery of breath tests have been developed. Depending on the test compound administered, different metabolic pathways (microsomal, cytosolic, mitochondrial) can be examined. Most available data come from microsomal function tests, whilst information about cytosolic and mitochondrial liver function is more limited. However, breath tests have shown promise in some studies, in particular to predict the outcome of patients with chronic liver disease or to monitor hepatic function after treatment. Whilst we await new substrates that can be used to measure liver function in a more valid manner, and large prospective studies to assess the usefulness of available test compounds, the aim of this review is to describe how far we have come in this controversial and unresolved issue.

How fat is obese

Abstract.The aim of the study was a comparison between body fat measurements and body mass index. We analyzed the data of 890 subjects, 596 females and 294 males, ranging in age from 18 to 83 years, in body mass index (BMI) from 14 to 54 kg/m2, and in body fat percentage (BF%) from 4% to 57%. A considerable number of subjects, both males and females, could not be classified as obese based on their BMI alone. Such a misclassification is undesirable, especially in general practice, and it calls for diagnostic criteria other than the BMI alone to be used for obesity.

The hormetic role of dietary antioxidants in free radical-related diseases.

Regular consumption of cruciferous vegetables or spices is associated with a reduced incidence of cancer and reduction of markers for neurodegenerative damage. Furthermore, greater health benefit may be obtained from raw as opposed to cooked vegetables. Nutritional interventions, by increasing dietary intake of fruits and vegetables, can retard and even reverse age-related declines in brain function and cognitive performance. The mechanisms through which dietary supplementation with antioxidants may be useful to prevent free radical-related diseases is related to their ability to counteract toxic production of both reactive oxygen and nitrogen species, along with the up-regulation of vitagenes, such as members of the heat shock protein (Hsp) family heme oxygenase-1 and Hsp70. The most prominent dietary factor that affects the risk of many different chronic diseases is energy intake - excessive calorie intake increases the risk. Reducing energy intake by controlled caloric restriction or intermittent fasting increases lifespan and protects various tissues against diseases, in part, by hormetic mechanisms that increase cellular stress resistance. This biphasic dose-response relationship, referred to here as hormesis, display low-dose stimulation and a high-dose inhibition. Despite the current interest in hormesis by the toxicology community, quantitatively similar U-shaped dose responses have long been recognized by researchers to be involved with factors affecting memory, learning, and performance, as well as nutritional antioxidants and oxidative stress-mediated degenerative reactions. Dietary polyphenols present strong cytoprotective effects, however under uncontrolled nutritional supplementation gene induction effects and the interaction with detoxification responses can have negative consequences through the generation of more reactive and harmful intermediates.

Measured and predicted resting metabolic rate in Italian males and females, aged 18-59 y.

Objectives: To determine the resting metabolic rate in a sample of the Italian population, and to evaluate the validity of predictive equations for resting metabolic rate (RMR) from the literature in normal and obese subjects.Design: Cross-sectional observational study.Settings: Department of Human Physiology and Nutrition, University ‘Tor Vergata’, Rome.Subjects: A total of 320 healthy subjects, 127 males and 193 females, aged 18–59 y.Methods: Weight, height and resting metabolic rate by indirect calorimetry were measured. Resting metabolic rate was also predicted using equations from the literature.Results: Resting metabolic rate (mean±s.d.) in normal weight subjects was 7983±1007 kJ/24 h (males) and 6127±907 kJ/24 h (females). Measured RMR and predicted RMR values using various equations from the literature were significantly different in males and females, except for the Harris–Benedict equation and the Schofield equations. Also, in overweight and obese subjects the prediction error was generally larger compared to normal-weight subjects for all formulas except for the Harris–Benedict and Schofield formulas. In overweight and obese males but not in females, RMR was lower than in normal-weight subjects after correcting for weight and age differences. Stepwise multiple regression of resting metabolic rate against weight, height and age in males and females did not reveal a prediction formula with a lower prediction error than the Harris–Benedict or Schofield formulas and thus was not further explored.Conclusions: The Harris–Benedict formula and the Schofield formula provide a valid estimation of resting metabolic rate at a group level in both normal-weight and overweight Italians. However, the individual error can be so high that for individual use a measured value has to be preferred over an estimated value.European Journal of Clinical Nutrition (2001) 55, 208–214

Body composition during normal pregnancy: reference ranges

Abstract.Maternal body composition undergoes a deep adaptative change during the course of pregnancy. Fat mass, fat-free mass, and total body water (TBW) increase in different ways and their effects on pregnancy outcome represent a field of major interest in perinatal medicine. The aim of this study was to evaluate the changes in maternal body composition [maternal weight, TBW, intracellular water (ICW) and extracellular water (ECW)] during healthy pregnancy by using bioimpedance analysis (BIA). A total of 170 healthy pregnant women, aged 22–44 years, volunteered to participate in our study. The BIA measurements were carried out with a Tefal BIA scale determining resistance and reactance. Lukaski’s multiple-regression equation was used to estimate TBW and ICW and ECW were computed using the prediction formula of Segal. The evaluations were performed at 10–38 weeks’ gestation, every 3–4 weeks, and hematocrit was determined at every time interval. Analysis of variance and multiple comparisons of Bonferroni were performed to compare variables among the different study intervals. Second-order polynomial interpolation was used to obtain percentile values for each bioimpedance parameter. Percentile bioimpedance values of the healthy population are provided at each study time, by showing the mean value and the 5th, 25th, 75th, 95th percentiles. Moreover, normal reference ranges for TBW are provided for each gestational age, in relation to maternal weight gain. Reactance, TBW, and ICW enhance slightly during the course of gestation. Tetrapolar BIA could be an easy and practical tool for evaluating changes of maternal body components during pregnancy. It could also provide indirect proof of the normal hemodilution occurring in normal pregnancies. Moreover, fat mass deposition, and not only fluid retention, seems to be responsible for the mother’s gestational weight gain, since reactance is an indirect parameter in estimating fat mass amount.