[Survey of physical activity and doping in a sample of 6,915 students aged 14-18 years]

AIM

Promoting physical activity is one of the main goals of health-promotion policies. The period of adolescence is characterised by a high rate of abandonment of any physical activity. In this age range, moreover, the risk of assuming substances in order to improve muscular-mass or athletic results is concrete. This study quantifies the involvement in physical activities and substance assumption in a sample of 6915 students aged 14 to 18 years and living in 7 different areas, mostly in northern Italy.

METHODS

The survey's tool is an adapted and modified vision of the Youth Risk Behaviour Surveillance questionnaire, created by US Centers for Disease Control and Prevention (CDC).

RESULTS

The study showed a high percentage of the sample not involved in any form of physical activity out of school (33.8%), more among girls (44.1%) than boys (21.2%). Between 14 and 18 years, a continuous reduction of involvement in physical activity is evident, while the percentage of totally physically inactive subjects rises from 30.1% to 43%. Finally, 5.6% in our sample admitted to have been using substances to improve muscular-mass or athletic results at least once in the past.

CONCLUSION

According to this study, only a minority of the interviewed adolescents is involved in a regular physical activity. In males, using substances to improve physical strength showed to be rather diffused. Specific health promotion projects are suggested.

How shunting inhibition affects the discharge of lumbar motoneurones: a dynamic clamp study in anaesthetized cats

In the present work, dynamic clamp was used to inject a current that mimicked tonic synaptic activity in the soma of cat lumbar motoneurones with a microelectrode. The reversal potential of this current could be set at the resting potential so as to prevent membrane depolarization or hyperpolarization. The only effect of the dynamic clamp was then to elicit a constant and calibrated increase of the motoneurone input conductance. The effect of the resulting shunt was investigated on repetitive discharges elicited by current pulses. Shunting inhibition reduced very substantially the firing frequency in the primary range without changing the slope of the current-frequency curves. The shift of the I-f curve was proportional to the conductance increase imposed by the dynamic clamp and depended on an intrinsic property of the motoneurone that we called the shunt potential. The shunt potential ranged between 11 and 37 mV above the resting potential, indicating that the sensitivity of motoneurones to shunting inhibition was quite variable. The shunt potential was always near or above the action potential voltage threshold. A theoretical model allowed us to interpret these experimental results. The shunt potential was shown to be a weighted time average of membrane voltage. The weighting factor is the phase response function of the neurone that peaks at the end of the interspike interval. The shunt potential indicates whether mixed synaptic inputs have an excitatory or inhibitory effect on the ongoing discharge of the motoneurone.

[Evaluation of the efficacy of the "Spazi Giovani" of family clinics. Results of 3 ASL services of the City of Milan]

"Spazio Giovani" is a service offered once a week by many Family Counselling Services and aimed at addressing the needs of tenagers and young people who can access it free of charge and without booking an appointment. This kind of services started in the Eighties to address the needs of young people who were sexually active and often not accessing conventional services. The objective of this study has been to assess how attitudes for unprotected sex and at risk sex behaviours decrease in a population attending the Youth Corner on a regular basis in comparison with the same attitudes and behaviours in a group of first-time users of the service over a six month period. The research, involving 301 teen and young females showed significant differences in protected behaviours between the two groups. No significant differences in attitudes were put in evidence by the study.

Positive proprioceptive feedback elicited by isometric contractions of ankle flexors on pretibial motoneurons in cats

Pretibial flexor motoneurons were recorded intracellularly in anesthetized cats during unfused isometric contractions of a subpopulation of motor units from either tibialis anterior (TA) or extensor digitorum longus (EDL) muscles. The contractions elicited excitatory postsynaptic potentials in 23 of 28 pretibial flexor motoneurons. No effect was observed in the remaining motoneurons. In control experiments, the effects of electrical stimulation of afferents within the TA nerve were investigated to help identify afferents responsible for the contraction-induced positive feedback. This feedback was ascribed to actions of Ia fibers because the pattern of the contraction-induced excitatory potentials was consistent with the known pattern of Ia discharge; in control experiments, electrical stimulation of group I fibers elicited only monosynaptic excitatory potentials; and the distribution of both the contraction-induced positive feedback among motor nuclei as well as the electrically evoked Ia excitatory monosynaptic potentials were restricted to homonymous and synergic motoneurons. Observation of the Ia contraction-induced positive feedback was facilitated by the absence of Ib autogenic inhibition. This contraction-induced Ia excitatory feedback in ankle flexors might either reinforce Ia-induced reflexes when these muscles are lengthened or help to lift the leg over an obstacle.

[Assessment of eating disorders-related risk in a cohort of adolescents living in Northern Italy. Results from a multicenter study]

BACKGROUND

Clinical evidence and epidemiological research show an increasing number of subjects trying to become lean and reaching consequently harmful weight conditions. Aim of this paper is to assess the risk for eating disorders during adolescence.

METHODS

In a multicentric study high school students of 5 different districts of Northern Italy have been asked to fill up anonymously the Italian version of the American YRBSS (Youth Risk Behaviour Surveillance System) questionnaire. For each school a section has been selected and between January and March 1999, students of every level have been involved. The data enrollected have been analysed using EpiInfo6.

RESULTS

The study involved 4135 adolescents (57% girls and 43% boys) coming from 260 classes and 47 different schools. The proportion of boys perceiving themselves as overweight and underweight was the same (22%), while the proportion of girls considering themselves overweight raised up to 42%. The majority of the girls (53%) is trying to slim making use of physical activity (48%), diets (32%), vomiting (8%) and drugs (5%).

CONCLUSIONS

Our data suggest that specific projects focusing on primary and secondary prevention of eating disorders should be considered for high schools. In addition, further studies are suggested to understand characteristics and behaviours related to eating disorders.

[Tobacco habits in a cohort of 4,135 adolescents attending high school in northern Italy. Results of a multicenter study]

Assuming that adolescence--a high risk age as far as this behavior is concerned--is the crucial stage for prevention procedures, we don't know much about Italian adolescents' tobacco related behaviors, regardless of the fact that tobacco smoking is one of the most relevant problems of Public Health. The goal of this research has been assessing, through a multicentric study using an anonymous questionnaire, how spread is this behavior among 4135 students attending high school in five different areas of Northern Italy. The research points out a remarkable spreading of the phenomenon and suggests to anticipate prevention procedures during compulsory education, taking in account gender features.

Maternal serum screening for trisomy 18 in the first trimester of pregnancy

The aim of this study was to evaluate the feasibility of first-trimester biochemical screening for trisomy 18, by using pregnancy-associated plasma protein A (PAPP-A) and free beta human chorionic gonadotropin (hCG) in combination with maternal age. Maternal serum levels of PAPP-A and free beta-hCG were assayed retrospectively in stored sera from 323 singleton pregnancies at 8-13 weeks' gestation. These samples included 23 trisomy 18 pregnancies and 300 unaffected controls, diagnosed either at chorionic villus sampling or at mid-trimester amniocentesis. The median MOM in affected pregnancies was 0.25 for PAPP-A and 0.34 for free beta-hCG. Statistically significant reductions were found in the mean levels of both PAPP-A (t test: P < 0.000001) and free beta-hCG (p < 0.000001) in trisomy 18 affected pregnancies when compared with the unaffected samples. Screening for trisomy 18 using a combination of maternal age, PAPP-A and free beta-hCG would achieve a detection rate of 76.6 per cent for a false-positive rate of 0.5 per cent. These results suggest that first-trimester biochemical screening for trisomy 18 might be possible. Further investigations in a general population are needed before introducing such screening into clinical practice.

First trimester screening for Down's syndrome using maternal serum PAPP-A and free beta-hCG in combination with fetal nuchal translucency thickness

The aim of this study was to evaluate the potential effectiveness of maternal serum pregnancy-associated plasma protein A (PAPP-A) and free beta-hCG in combination with nuchal translucency thickness in first trimester screening for Down's syndrome. Maternal serum levels of PAPP-A and free beta-hCG were assayed in stored sera from 32 Down's syndrome and 200 unaffected pregnancies. Fetal nuchal translucency was measured by ultrasound at the time of blood sampling. Screening of Down's syndrome using a combination of maternal age, PAPP-A, free beta-hCG and nuchal translucency would achieve a detection rate of 75.8% for a false positive rate of 5%.

Comparison between two methods of standardization for gestational age differences in fetal nuchal translucency measurement in first-trimester screening for trisomy 21

Our purpose was to compare two different methods of expressing nuchal translucency (NT) measurements in first-trimester screening for trisomy 21: the difference in millimeters from the median of nuchal translucency (delta value: delta NT) and the multiple of the expected median (MoM). Fetal nuchal translucency was measured in 32 fetuses with trisomy 21 and in 3180 normal fetuses at 9-13 weeks' gestation. For each fetus, the measured nuchal translucency was expressed both as a delta value and MoM. The effectiveness of the MoM-Gaussian vs. the delta value method in modifying the age-specific risk for trisomy 21 was compared by using both the maternal age distribution of our study population and the age distribution of a general obstetric population. The use of the MoM-Gaussian approach led to a reduction in the false-positive rate at a given detection rate, both in the study population (by 1.2-15.2%) and in the general population (by 0.4-2.4%). Our results suggest that the use of the MoM-Gaussian method might confer a potential advantage on the screening performance of nuchal translucency in combination with maternal age by decreasing the false-positive rate. Further studies in larger unselected populations will be needed to confirm the effectiveness of this approach.

A rare case of cytogenetic discrepancy between extraembryonic and fetal tissue

We present a case of false-negative discrepancy between extraembryonic and fetal tissue sampled at 14 weeks of amenorrhoea when ultrasound examination showed morphological anomalies of the fetus. The same cytogenetic characteristic was confirmed on tissue samples after abortion.

[The use of Rossavik's mathematical model in determining individual intrauterine growth curves. Our experience]

OBJECTIVE

To evaluate the performance of Rossavik growth models, derived from II trimester ultrasound measurements, to predict growth in normally growing fetuses.

DESIGN

Comparison between observed measurements after 25 weeks and those predicted by Rossavik growth models determined from the data collected in 2 ultrasound examinations at approximately 16 weeks and 24 weeks.

SETTING

Teaching hospital obstetric unit, in Florence.

SUBJECTS

Thirty women who delivered normal term fetuses in our unit, between January 1991 and December 1992.

MAIN OUTCOME MEASURES

Determination of the expected growth curve after 25 weeks from the appropriate growth models, for these fetal parameters: biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL). The differences between sonographic measurement of each parameter, at various time points, and predicted values were expressed as a percentage of the predicted values. Head circumference and weight measured in each infant were also compared with the predicted values at term.

RESULTS

Mean percent deviation values were comprised between -0.02% (+/- 2 SD: 3.9%) for BPD and +0.75% (+/- 2 SD: 4.6%) for FL. Pearson's correlation coefficients between predicted and observed fetal parameters, ranged from 0.89 for AC and 0.94 for BPD. For HC and estimated weight at birth, the percent deviations were 0.84% (+/- 2 SD: 5.6%) and 1.23% (+/- 2 SD: 10.5%), respectively. The mean percent deviations for all parameters, were not significantly different from zero.

CONCLUSIONS

Our results confirm the accuracy of Rossavik growth model in predicting growth after 25 weeks in normally growing fetuses.

[Infibulation practice: clinical aspects in an adolescent outside the community]

Because of the increase arrival of extra-community people, now it is easy to meet with new pathologies or with old ones that we believed disappeared. We describe a case of infibulation practice observed in a thirteen year old coloured adolescent. She was admitted for an unknown-provenance fever.

Identification of hematopoietic progenitor cells in human amniotic fluid before the 12th week of gestation

Due to technical difficulties in performing amniocentesis before the 12th week of pregnancy, very little is known about the components of human amniotic fluid before that time. Amniocentesis was performed between the 7th-11th week of gestation in 25 informed and consenting patients, who had to undergo therapeutic interruption of pregnancy. The cells from the amniotic fluid were stained, counted on a hemocytometer, and checked for vitality. The origin of these cells was determined from cellular cultures the intracellular content of the hemoglobin and the chloroacetate esterase content of the hemoglobin and the chloroacetate esterase contents were also studied. Taking advantage of the "in vitro" adhesive properties of these cells to the bone marrow stromal feeder layer, we obtained clonal growth of an erythroid nature from 18 out of 33 samples. At the 17th week of gestation, an increased number of cells and a decrease in their vitality was found. Between the 7th and 12th week, the cellular composition of the fluid was totally different from that found later in the pregnancy. Small nucleated, round cells were identified as hematopoietic progenitor cells. At the beginning of the 11th week, a cellular population, typically used to perform prenatal diagnosis of chromosomal abnormalities from the 14th week of pregnancy appeared. Since hematopoietic progenitor cells were found in the amniotic fluid before the 12th week of gestation, these cells most probably come from the hematopoietic cells of the yolk sac through the thin membrane of the yolk sac at this time.

Evaluation of maternal serum alpha-fetoprotein and ultrasound examination to screen fetal chromosomal abnormalities

Maternal serum alpha-fetoprotein (MSAFP), anatomic anomalies and precocious defects of foetal growth were shown as possible "indicators" of foetal chromosomal pathology, in particular Down's syndrome, and thus suggested for prenatal screening of risk patients for this chromosomal abnormalities. The Authors carried out a retrospective study on 1472 patients who underwent amniocentesis for prenatal diagnosis. Between the 15th and the 20th week, a dosage of MSAFP was effected, in order to evaluate if the serum concentration of this substance could predict Down's syndrome. A contemporary study by echographic monitoring was effected on 500 patients from the 1st trimester of pregnancy, in order to detect possible foetal growth retardation precociously and to determine the karyotype in these cases. Results are very interesting and suggest both the dosage of MSAFP and the ecographic monitoring for prenatal screening of trisomy 21, especially in maternal age classes younger than 40 years, where the cost/benefit ratio of screening for maternal age is less favourable.

Alpha-fetoprotein in obstetrics. Experience of a prenatal diagnosis center

For several years the determination of maternal serum alpha-fetoprotein (MSAFP) levels has been utilized to screen the patients at increased risk for foetal neural tube defects. In this way, various problems have been more and more dealed, from the definition of "cut-off" levels which could be guarantee an acceptable rate of diagnoses, limiting however the number of normal pregnancies which undergo further ascertainments, to the search of indoneous protocols of diagnostic approach in cases of high MSAFP levels. The wide clinical use of MSAFP determination has lead to the availability of a large number of data in various classes of obstetrics population, and to search for new diagnostic chances offered by this metodology. Among these, a great interest has been pointed out to the use of MSAFP determination to screen for Down's syndrome foetuses and to utilize MSAFP as a predictive index of perinatal pathology. The Authors describe their own experience in these diagnostic fields.

High maternal serum alpha-fetoprotein levels during the 2nd trimester of pregnancy: diagnostic approach

The limit of the classic diagnostic protocols following the evidence of high maternal serum alpha-fetoprotein levels is represented by the high number of amniocenteses performed and that, in the most part of cases, give false negative results. Now days the introduction of high resolution ecographic equipments allows to us, in many cases, to clarify the diagnostic without further examinations. The Authors propose a diagnostic protocol that include the execution of high resolution ultrasound at the second withdrawal of serum alpha-fetoprotein, limiting the use of amniocentesis only when is necessary to determine the fetal karyotype. An high sensibility diagnostic system with a favourable cost/benefit ratio results from this approach.