Aflatoxins are natural scavengers of reactive oxygen species

The role of aflatoxins (AFs) in the biology of producing strains, Aspergillus sect. Flavi, is still a matter of debate. Over recent years, research has pointed to how environmental factors altering the redox balance in the fungal cell can switch on the synthesis of AF. Notably, it has been known for decades that oxidants promote AF synthesis. More recent evidence has indicated that AF synthesis is controlled at the transcriptional level: reactive species that accumulate in fungal cells in the stationary growth phase modulate the expression of aflR, the main regulator of AF synthesis—through the oxidative stress related transcription factor AP-1. Thus, AFs are largely synthesized and secreted when (i) the fungus has exploited most nutritional resources; (ii) the hyphal density is high; and (iii) reactive species are abundant in the environment. In this study, we show that AFs efficiently scavenge peroxides and extend the lifespan of E. coli grown under oxidative stress conditions. We hypothesize a novel role for AF as an antioxidant and suggest its biological purpose is to extend the lifespan of AFs-producing strains of Aspergillus sect. Flavi under highly oxidizing conditions such as when substrate resources are depleted, or within a host.

Balance impairment in kidney transplant recipients without concurrent peripheral neuropathy

Kidney transplant recipients (KTRs) present with compromised functional capacity, low levels of physical activity, muscle atrophy, and peripheral nerve dysfunction that may result in high postural instability. This study aimed to compare the static balance control of 19 KTRs with 19 healthy adults (HA). All participants completed the Romberg test on a stabilometric platform with eyes open (EO), eyes closed (EC) and during a dual task (DT) condition. Centre of pressure (COP) measures (COP velocity (COPv) and sway area (SA)), as well as position-based outcomes such as anterior-posterior (AP) and medio-lateral (ML) ranges of COP displacements were recorded. Independent ANCOVA revealed an overall lower performance of KTRs compared to HA (p<0.05) with the EC condition exhibiting the worst relative performance for KTRs, suggesting a poorer capacity of relying on proprioceptive information when maintaining the upright posture. The addition of a cognitive task did not further worsen balance performance in KTRs. As impaired postural control is one of the main predictors of falls in elderly subjects, these data might also indicate that this constitutes an equivalent risk factor for falling in middle-aged KTRs.

Effects of a Pilates exercise program on muscle strength, postural control and body composition: results from a pilot study in a group of post-menopausal women

Participation in exercise programs is heartily recommended for older adults since the level of physical fitness directly influences functional independence. The aim of this present study was to investigate the effects of supervised Pilates exercise training on the physical function, hypothesizing that a period of Pilates exercise training (PET) can increase overall muscle strength, body composition, and balance, during single and dual-task conditions, in a group of post-menopausal women. Twenty-five subjects, aged 59 to 66 years old, were recruited. Eligible participants were assessed prior and after 3 months of PET performed twice per week. Muscular strength was evaluated with handgrip strength (HGS) test, 30-s chair sit-to-stand test (30CST), and abdominal strength (AST) test. Postural control and dual-task performance were measured through a stabilometric platform while dynamic balance with 8 ft up and go test. Finally, body composition was assessed by means of dual-energy X-ray absorptiometry. Statistically significant improvements were detected on HGS (+8.22%), 30CST (+23.41%), 8 ft up and go test (-5.95%), AST (+30.81%), medio-lateral oscillations in open eyes and dual-task condition (-22.03% and -10.37%). Pilates was effective in increasing upper body, lower body, and abdominal muscle strength. No changes on body composition were detected. Results on this investigation indicated also that 12-week of mat Pilates is not sufficient to determine a clinical meaningful improvement on static balance in single and dual-task conditions.

The effects of Pilates exercise training on physical fitness and wellbeing in the elderly: A systematic review for future exercise prescription

This systematic review aims to summarize the effects of Pilates exercise training (PET) in elderly population on physical fitness, balance and fall prevention, and its effects on mood states, quality of life and independence in the daily living activities.

METHODS

Keyword "Pilates" associated with "elderly", "aging" and "old subjects" were identified as terms for the literature research in MEDLINE, Embase, PubMed, Scopus, PsycINFO and SPORTDiscus. Only studies published in peer-reviewed journals written in English language were considered. A meta-analysis was performed and effect sizes (ES) calculated.

RESULTS

10 studies were identified (6 RCTs and 4 uncontrolled trials); age ranged from 60 to 80years. Overall, PET showed large ES to improve muscle strength (ES=1.23), walking and gait performances (ES=1.39), activities of daily living, mood states and quality of life (ES=0.94), moderate to high effect on dynamic balance (ES=0.77), small effects on static balance (ES=0.34) and flexibility (ES=0.31), while a small effect on cardio-metabolic outcomes (ES=0.07).

CONCLUSIONS

PET should be taken into account as a way to improve quality of life in the elderly, due to the imparted benefits of fall prevention, physical fitness, and mood states. In this context, physicians might include PET as a tool for exercise prescriptions for the elderly.

Antioxidant effect of zinc supplementation on both plasma and cellular red-ox status markers in a group of elderly Italian population

OBJECTIVES

The aim of this work was to evaluate the effect of long term supplementation with two moderate dose of Zn on plasma and cellular red-ox status markers in elderly volunteers.

DESIGN, SETTING AND SUBJECTS

In a double blind study 108 healthy volunteers, aged 70-85 years, were enrolled. They were randomly divided in 3 groups of treatment, receiving placebo, 15 mg/day and 30 mg/day of Zn for 6 months. Red-ox status markers were assessed at baseline and after 6 months evaluating carotenoids, vitamin A and E in plasma; glutathione (GSH), thiol groups (RSH), malondialdehyde (MDA), percentage of haemolysis and methemoglobin in erythrocytes.

RESULTS

Zn supplementation had no significant effects on red-ox status markers except for vitamin A levels (from 1.94±0.44 to 2.18±0.48 μM in volunteers receiving 15 mg of Zn and from 1.95±0.46 to 2.26±0.56 μM in volunteers receiving 30 mg of Zn), which increased proportionally to zinc dose.

CONCLUSIONS

It appears that, differently from unhealthy populations, long-term supplementation with two moderate doses of Zn in a healthy elderly population, with an adequate Zn nutritive status and macro and micronutrients intakes in the range of normality, is an inefficient way to increase antioxidant defences.

Effects of consumption of whole grain foods rich in lignans in healthy postmenopausal women with moderate serum cholesterol: a pilot study

This study aims at investigating the effect of an experimental period of intake of whole grain foods rich in lignans as part of an habitual diet on the plasma and urinary excretion of enterolignans, the biomarkers of lipid metabolism and the immunological and antioxidant status in a group of postmenopausal women with moderate serum cholesterol. A randomized double-blind crossover study was completed on 13 subjects in 12-weeks after protocol approval of an ethical committee. The subjects consumed whole grain foods high in lignans (30 g/d of breakfast cereals or biscuits, etc., 80 g/d of whole grain pasta) or refined grain foods for 4 weeks, separated by a 2-weeks wash-out period. A modest hypocholesterolemic effect (p < 0.05) of the whole grain diet was observed and the intake of whole grain products rich in lignans was also associated with an increase in urinary enterodiol excretion (p < 0.05).

Plasma leptin and energy expenditure during prolonged, moderate intensity, treadmill exercise

BACKGROUND

Current literature shows conflicting results regarding the possible direct role of exercise on leptin concentrations, mainly because of a non-homogeneous level of energy expenditure (EE) and the lack of standardization of energy balance.

AIM

The aim of the study was to evaluate the effect of exercise duration and its corresponding EE on leptin levels, during prolonged treadmill exercise, in a well-controlled laboratory setting.

MATERIALS AND METHODS

Seven young trained males underwent a 4-h treadmill exercise. The starting intensity was set at 65% of maximal oxygen consumption. At the start of the test and throughout the exercise, venous blood samples were drawn for the assays of leptin, glucose, free fatty acids (FFA), cortisol, epinephrine (E) and norepinephrine (NE). Hourly and total EE was monitored with gas analysis.

RESULTS

Plasma leptin levels decreased from 1.10±0.15 to 0.85±0.26 μg/l (p<0.01) at the end of the exercise, reaching a significant reduction already after the second hour. FFA and cortisol showed a progressive significant increase, while glucose did not significantly change throughout the test. Plasma E and NE significantly increased at all sampling times compared to basal values (48.1±30.3 to 352.3±187.7 pg/ml, p<0.001 and 238.1±118.9 to 1798.7±413.5 pg/ml, p<0.001). The random-effects model for panel data analysis showed negative correlation between leptin, NE and the values of progressive EE (r2=0.745, p<0.05).

CONCLUSIONS

Our data demonstrate that, during a prolonged moderate intensity exercise, leptin decrease is significantly related to the total EE. Further, NE concentrations seem to play an important role in the inhibition of leptin secretion.

Physical activity attenuates the negative effect of low birth weight on leptin levels in European adolescents; the HELENA study

We examined whether physical activity (PA) influences the association between birth weight and serum leptin in adolescents. The study comprised a total of 538 adolescents (315 girls), aged 12.5-17.49 years, born at term (≥ 37 weeks of gestation). We measured serum leptin levels and time engaged in moderate-vigorous PA (MVPA) by accelerometry. There was an interaction effect between birth weight and meeting the PA recommendations (60 min/day MVPA) on leptin levels in girls (P = 0.023) but not in boys (P = 0.809). Birth weight was negatively associated with leptin levels in girls not meeting the PA recommendations (i.e. more than 60 min/day of MVPA) (β = -0.096, P = 0.009), whereas no significant association was observed in those meeting the PA recommendations (β = -0.061, P = 0.433). In conclusion, meeting the PA recommendations may attenuate the negative effect of low birth weight on serum leptin levels in European female adolescents.

Nasal dysfunction induced by chlorinate water in competitive swimmers

AIMS

Swimmers commonly complain of nasal symptoms probably due to mucosal irritation caused by chlorinated water. The aim of the present prospective study was to investigate changes in nasal function and cytology in a cohort of 15 volunteer competitive swimmers, as compared with a control group of 15 competitive athletes practicing other sports.

METHODS

Olfactory threshold for n-butanol was measured in a population of competitive swimmers. Changes in nasal function and cytology were compared between the two groups of volunteer competitive athletes.

RESULTS

There were no significant differences between the two groups in terms of mean 20-Item Sino-Nasal Outcome Test scores, peak nasal inspiratory flow, pulmonary peak expiratory flow, or total nasal resistance on anterior active rhinomanometry. Nasal mucociliary transport time (MCTt) was significantly shorter for the non-swimmers than for the swimmers. The mean olfactory threshold for n-butanol in the swimmers was significantly lower than in the other group of athletes.

CONCLUSIONS

Data seem to confirm the utility of MCTt in studying nasal mucosa damage caused by chlorinated water. The present results also support the hypothesis of a role for the olfactory threshold in evaluating damage to the olfactory mucosa exposed to chlorinated water.

Nasal functional modifications after physical exercise: olfactory threshold and peak nasal inspiratory flow

STATEMENT OF PROBLEM

The respiratory nasal effects of physical exercise have been extensively investigated; on the other hand there are no data regarding olfactory threshold modification after aerobic physical exercise.

METHODS

The present prospective study investigated the modifications in nasal respiratory flows and olfactory thresholds after controlled aerobic physical exercise in a cohort of 15 adult, healthy volunteers. The Peak Nasal Inspiratory Flow (PNIF), and the Sniffin’ Sticks olfactory threshold test were used for our determinations.

MAIN RESULTS

The mean PNIF after physical exercise was significantly higher than the mean PNIF value found before physical exercise. Statistical analysis ruled out any significant difference between mean olfactory thresholds pre vs post physical exercise.

PRINCIPAL CONCLUSIONS

These outcomes confirmed PNIF sensitivity and reliability also in determining the changes in nasal patency occurring after physical exercise. The active vasoconstriction of nasal mucosa associated with the reduction of blood flow to the olfactory epithelium due to physical exercise may be compensated for by the increase of olfactory molecules that reach the olfactory mucosa because of nasal mucosal shrinkage: this mechanism could explain the stability of mean olfactory threshold after physical exercise.

Validity of self-reported body weight and height among women including patients with eating disorders

The main objective of this study was to evaluate the accuracy of self-reported weight and height among women with eating disorders. The study sample consisted of 271 women aged 18-50 yrs: 73 anorexic patients (AN) with a body mass index (BMI) of <18.50 kg/m2, 54 normal weight bulimic or rehabilitated patients (BU/RE: 18.5<BMI<25), 38 overweight/ obese women (OW/OB: BMI> or =25 kg/m2) and 106 normal weight women without an eating disorder (NW: 18.5<BMI<25). Their self-reported body weight (BW) and height were recorded during an interview, and measured using standard procedures, and their self-reported and measured BMI was calculated (kg/m2). In comparison with the measured data, the AN patients tended to overestimate their body weight by 0.48+/-2.05 kg (p<0.05), whereas the OW/OB and BU/RE patients underestimated it (OW/OB: -1.52+/-3.21 kg, p=0.006; BU/RE: -1.12+/-2.60 kg, p=0.003). All of the groups overestimated height by at least 1 cm, and the OW/OB group overestimated it by 2.31+/-2.94 (p=0.00000). These differences were reflected in the significant underestimate of BMI by all groups except the AN patients. Pearson's correlation coefficients between the self-reported and measured variables ranged from 0.95 to 0.98. The results of a Bland & Altman analysis showed that the underestimates of weight and BMI were related to the magnitude of the values (BW: r=-0.24, p<0.000078; BMI: r=-0.37, p<0.00000), the differences being greater with increasing values of weight and BMI; sensitivity as greater for the AN patients. The self-reported data led to a significant misclassification of body mass categories, especially among the BU/RE and OW/OB subjects. Our results show that the over-reporting of height and under-reporting of body weight led to significant underestimates of BMI. The AN subjects seemed to know their weight quite well, whereas the BU/RE and OW/OB women significantly underestimated it. On the basis of these findings, measured weight and height should always be preferred to self-reported values.

Relationship between stress hormones and immune response during high-altitude exposure in women

We previously confirmed that high altitude (HA) exposure can modify the number and function of immune cells, leading to a disruption in the homeostatic regulation of T helper1 (Th1)/T helper2 (Th2) immune responses. Our aim was to evaluate possible relationships between the stress response and immunological parameters during HA exposure. Thirteen healthy women spent 21 days at 5050 m. Before (SL1), the first and the 21st day at HA (HA1 and HA2, respectively), and the day after returning at sea level (SL2), we collected blood samples for immunologic parameters, and 24-h urine samples for norepinephrine, epinephrine, and cortisol. Norepinephrine and cortisol significantly increased (p<0.01) at HA1 and HA2 compared to SL1, while epinephrine did not change. At HA1, CD3+ T-cell fell significantly (p<0.001) with respect to SL1, owing to a significant (p<0.001) CD4+ T-cell reduction, while CD16+ and CD56+ increased (p<0.001) at HA2 compared to SL1. The expression of interferon-gamma (IFN-gamma) decreased (p<0.0005) at HA1 and HA2 with respect to SL1. At HA1 different lymphocyte subset (CD3+, CD4+, CD19+) were well correlated with epinephrine (p<0.05), whereas in analyzing the combined data (SL1-HA1-HA2-SL2), CD3+ (r=-0.310), CD4+ (r=-0.332), CD16+ (r=0.404), and CD56+ (r=0.373) demonstrated moderate but significant correlations (p<0.05) with norepinephrine. Moreover, norepinephrine levels were inversely correlated (r=-0.591; p<0.001) with IFN-gamma expression, a typical Th1 cytokine. We suggest that the sympatho-adrenal axis may have a role on the immunologic adaptations observed during HA exposure, and specifically on the observed impairment of the Th1/Th2 immune balance.

[Effects of a combined weight-bearing and non-weight-bearing ( warm water) exercise program on bone mass and quality in postmenopausal women with low bone-mineral density]

AIMS

To evaluate the effects of a combined weight- and non weight-bearing (water) exercise program on bone mass and quality in postmenopausal women with low bone mineral density.

MATERIALS AND METHODS

125 post-menopausal women with osteopenia/osteoporosis underwent a bone mass (Dual-Energy X-ray Absorbimetry, DEXA) and bone tissue quality (phalangeal osteosonography) evaluation. 58 of the participants took part in an 11-month specific exercise program (E). The other represented a control group (C) that did not exercise. At the end of the exercise program all the participants were re-evaluated.

RESULTS

Concerning bone mass, within and between groups data analysis showed that t-score, measured at neck of femur, significantly increased in E (p < 0.05). No differences were instead detected for all the other parameters. With respect to osteosonography, group C showed a significant decrease of all bone quality parameters (p < 0.05), whereas E showed no differences after the exercise program.

CONCLUSIONS

The results showed that a specific exercise program targeting osteoporosis is useful to reduce the physiological bone loss and to maintain a good bone quality in a group of postmenopausal women with low bone mineral density.

Effect of zinc supplementation on vitamin status of middle-aged and older European adults: the ZENITH study

OBJECTIVE

To assess the effects of zinc supplementation on vitamin status in middle-aged and older volunteers.

SUBJECTS/METHODS

Three hundred and eighty-seven healthy middle-aged (55-70 years) and older (70-85 years) men and women, randomly allocated to three groups to receive 15 or 30 mg Zn/day or placebo for 6 months. Dietary intake was assessed by means of a validated 4-day recall record. Fasting blood samples were simultaneously analysed for levels of plasma retinol and alpha-tocopherol by high-performance liquid chromatography. Erythrocyte folates were measured by a competitive immunoassay with direct chemiluminescence detection on an automatized immunoanalyser. Biochemical measurements were performed at baseline and after 3 and 6 months of zinc supplementation.

RESULTS

Plasma vitamin A levels were significantly increased proportionally with zinc dose and period of treatment, particularly at 6 months (for 15 mg Zn/day, P<0.05; for 30 mg Zn/day, P<0.0001); no significant changes were observed in the placebo group. There was no effect of zinc supplementation on vitamin E/cholesterol ratio and erythrocyte folates.

CONCLUSIONS

Our results show that a long-term zinc supplementation increases plasma vitamin A levels in middle-aged and older people of similar characteristics to those involved in this study. Moreover, supplementation influences serum zinc levels but does not affect erythrocyte zinc concentration and both plasma vitamin E and erythrocyte folate status.

Descriptive data on lifestyle, anthropometric status and mental health in italian elderly people

OBJECTIVE

The objective of this paper is to provide descriptive information on anthropometric status, pathological conditions, cognitive impairment and lifestyle in apparently healthy elderly Italian people.

DESIGN, SETTING AND SUBJECTS

In order to recruit the volunteers for the ZENITH study, 359 Italian participants (167 men and 192 women), aged between 70 and 85 years, free living in Rome, were selected. Volunteers underwent a full clinical examination, anthropometric measurements (height, weight), a lifestyle questionnaire and mental health assessment (cognitive impairment and depression).

RESULTS

The prevalence of overweight and obesity was high (57% and 22% in men; 43% and 27% in women). Obesity was associated with low socio-economic profile in about 40% of participants. Although the sample was selected by family doctors and was apparently healthy, after medical screening the presence of several pathologies, particularly diabetes in 21% of participants was observed. There was a low prevalence of cognitive impairment in 4% of men and 7% of women and possible depression in 9% of men and 19% of women. The lifestyle questionnaire showed that most of their time was spent in light activities such as reading, watching TV or playing cards and significant differences between sex and BMI categories were observed (P=0.000).

CONCLUSION

The results confirm the increasingly sedentary lifestyle of modern populations and demonstrate the need for sensitive and individualised strategies to design appropriate health promotion and disease prevention programs for older adults.

Zinc intake and status in middle-aged and older European subjects: the ZENITH study

OBJECTIVE

Inadequate intakes of micronutrients in elderly negatively affect the nutritional status. Zinc is an essential micronutrient in the elderly, especially in relation to its impact on immune function, bone mass, cognitive function and oxidative stress. However, data are lacking on zinc intake and status during normal ageing. In this study, we evaluate the intake and status of zinc in late middle-aged and older free-living subjects.

DESIGN

Dietary zinc intake and zinc status in 188 middle-aged subjects from Clermont-Ferrand (Fr) and Coleraine (UK), and in 199 older subjects from Grenoble (Fr) and Roma (It) were assessed at the entry in the ZENITH study.

RESULTS

In relation to the zinc RDA for people older than 55 y, zinc intakes in most of the middle-aged and older subjects (more than 96%) in the present study were adequate. Older people had significantly lower (P < 0.01) energy intakes as compared to middle-aged. Zinc intake expressed per MJ was also significantly (P < 0.01) higher in older people compared to middle-aged. Erythrocyte and urinary zinc concentrations were significantly (P < 0.001) higher in middle-aged subjects compared to older ones. The prevalence of biological Zn deficiency in free-living ageing European people was low (<5%).

CONCLUSION

The results of the present study showed a relatively low prevalence of zinc deficiencies in healthy free-living late middle-age and older subjects. These results should be useful for health professionals to have reference data on zinc intake and status for a healthy ageing.

Completion of screening for latent tuberculosis infection among immigrants

The objective of our study was to evaluate the sociodemographic factors associated with completion of screening for latent tuberculosis infection (LTBI) among undocumented immigrants in Brescia, Italy. Screening for LTBI was offered to 649 immigrants; 213 (33%) immigrants completed the first step of screening; only 44% (55/124) of individuals with a positive tuberculin skin test result started treatment for LTBI. The univariate analysis showed that being unmarried, of Senegalese nationality and being interviewed by a health-care worker with the same native language as the immigrant were significantly associated with completion of screening for LTBI. In the multiple logistic regression, being interviewed in the native language of the health-care worker (OR 2.5, 95% CI 1.3-4.8, P = 0.004) and being of Senegalese origin (OR 2.3, 95% CI 1.4-3.6, P = 0.0005) were independently associated with adherence to LTBI screening. Our results suggest that knowledge of the sociodemographic characteristics of immigrants, and the participation of health-care workers of the same cultural origin as the immigrant during the visits, can be an important tool to improve completion of screening for LTBI.

Effect of licorice on the reduction of body fat mass in healthy subjects

The history of licorice, as a medicinal plant, is very old and has been used in many societies throughout the millennia. The active principle, glycyrrhetinic acid, is responsible for sodium retention and hypertension, which is the most common side-effect. We show an effect of licorice in reducing body fat mass. We studied 15 normal-weight subjects (7 males, age 22-26 yr, and 8 females, age 21-26 yr), who consumed for 2 months 3.5 g a day of a commercial preparation of licorice. Body fat mass (BFM, expressed as percentage of total body weight, by skinfold thickness and by bioelectrical impedance analysis, BIA) and extracellular water (ECW, percentage of total body water, by BIA) were measured. Body mass index (BMI) did not change. ECW increased (males: 41.8+/-2.0 before vs 47.0+/-2.3 after, p<0.001; females: 48.2+/-1.4 before vs 49.4+/-2.1 after, p<0.05). BFM was reduced by licorice: (male: before 12.0+/-2.1 vs after 10.8+/-2.9%, p<0.02; female: before 24.9+/-5.1 vs after 22.1+/-5.4, p<0.02); plasma renin activity (PRA) and aldosterone were suppressed. Licorice was able to reduce body fat mass and to suppress aldosterone, without any change in BMI. Since the subjects were consuming the same amount of calories during the study, we suggest that licorice can reduce fat by inhibiting 11beta-hydroxysteroid dehydrogenase Type 1 at the level of fat cells.

Effects of prolonged high-altitude exposure on peripheral adrenergic receptors in young healthy volunteers

The regulation of adrenergic receptors during hypoxia is complex, and the results of published reports have not been consistent. In the present study blood cell adrenoceptor characteristics at sea level (SL) before and after prolonged exposure to high altitude (HA) were measured in seven trained young male lowlanders. Sympathoadrenal activity and clinical haemodynamic parameters were also evaluated before departure (SLB), after 1 week (HA1) and 4 weeks (HA4) at HA and 1 week after return to sea level (SLA). As compared to pre-departure sea level values, urinary norepinephrine excretion increased significantly during altitude exposure [SLB: 10.26 (3.04) microg x 3 h(-1); HA1: 23.2 (4.19) microg x 3 h(-1); HA4: 20.3 (8.68) microg x 3 h(-1)] and fell to pre-ascent values 1 week after return to sea level [SLA: 9 (2.91) microg x 3 h(-1)]. In contrast, mean urinary epinephrine levels did not increase over time at HA. Both systolic and diastolic blood pressures, as well as heart rate, were increased during HA exposure. The circadian blood pressure and heart rate rhythms were preserved during all phases of altitude exposure. Mean maximal binding (Bmax) of the alpha2-adrenoceptor antagonist [3H]rauwolscine to platelet membranes was significantly reduced (P < 0.001) after exposure to chronic hypoxia [SLB: 172.6 (48.5) fmol x mg(-1) protein versus SLA: 136.8 (56.1) fmol x mg(-1) protein] without change in the dissociation constant (K(D)). Neither the lymphomonocyte beta2-adrenoceptor Bmax [SLB: 38.5 (13.6) fmol x mg(-1) protein, versus SLA: 32.4 (12.1) fmol mg(-1) protein] nor the K(D) for [3H]dihydroalprenolol was affected by chronic hypoxia. Cyclic AMP (adenosine 3',5'-cyclic monophoshate) generation in lymphomonocytes by maximal isoproterenol stimulation was not modified after prolonged HA exposure. In conclusion, the down-regulation of alpha2-adrenoceptors appears to be an important component of the adrenergic system response to HA exposure.

Blunted growth hormone response to maximal exercise in middle-aged versus young subjects and no effect of endurance training

The purpose of this study was to evaluate the GH response to exercise and the effects of endurance training on this response in early middle-aged men. Seven healthy middle-aged [M; 42.0+/-2.4 (+/-SD) yr old] and five young (Y; 21.2+/-1.1 yr old) competition cyclists were investigated before and after 4 months of intensive endurance training. Subjects performed an exhaustive incremental exercise test (50 watts for 3 min) with gas exchange measurement, and blood samples for lactate, glucose, and GH determinations were drawn before exercise, at the end of the exercise, and in the recovery phase (1, 3, 5, 10, 15, 20, and 30 min). Basal insulin-like growth factor I was also determined. At exhaustion no differences were found in relative maximal heart rate or blood lactate and glucose peaks. On the contrary, the two groups had markedly different GH responses; in fact, the peak GH response to exhaustive exercise was much lower in M than in Y (8.1+/-1.3 vs. 57.1+/-15.5 microg/L; P<0.01). The training, similar in subjects of the same group, increased progressively from 182 to 300 km/week (+64.8%) in M and from 350 to 600 km/week (+71.4%) in Y. After the training, the percent increase in maximal oxygen consumption was similar in the two groups (M, +15.2%; Y, +17.5%), confirming that the efficiency of the training performed was comparable. In neither group did training have any effect on the GH peak response to exercise, confirming the blunted GH response in M compared to Y (6.7+/-1.0 vs. 61.0+/-12.9 microg/L; P<0.01). Similarly, insulin-like growth factor I concentrations were not significantly affected by training. In conclusion, active middle-aged subjects, compared with the young, showed a blunted GH response to a physiological stimulus such as exercise, indicating that the age-related decline in GH secretion appears in early middle age. This response was not modified by training in either early middle-aged or young subjects.

Sodium regulating hormones at high altitude: basal and post-exercise levels

High altitude (HA)-induced diuresis is associated with marked changes in sodium and water regulating hormones, particularly the renin-angiotensin-aldosterone system (RAAS) and atrial natriuretic hormone (ANH). These hormones are also strongly stimulated by physical exercise, which is a major component of daily activity at HA. In spite of the numerous studies in literature, a clear relationship between hormonal changes, HA diuresis, and physical exercise has not yet been established. We therefore evaluated the response of sodium regulating hormones to exhaustive exercise in a group of seven males exposed to prolonged HA hypoxia. The study was divided into four phases: sea level (SL1), after 7 (P1) and after 21 (P2) days at 5050 m (Italian National Research Council Pyramid Laboratory, Nepal), and back at sea level (SL2). At each phase plasma hematocrit (Ht), total body water (TBW), 24-hr sodium excretion (uNa), and urinary volume (uV) were evaluated together with PRA, plasma aldosterone, and ANH, in samples drawn basally from patients in upright position, and at the end of graded step-wise (30 W/2 min) maximal exercise. Levels of uNa and uV were raised at P1 and then declined at P2, with a parallel decrease in TBW and an increase in Ht. Basal PRA and aldosterone levels were suppressed both at P1 and P2 (from 1.9 +/- 0.4 to 0.08 +/- 0.03 and 0.5 +/- 0.1 ng/mL/3 h, and from 7.9 +/- 1.8 to 3.9 +/- 0.4 and 4.5 +/- 0.4 ng/dL, respectively; P < .05). Exhaustive exercise at HA did not induce any significant response in PRA and aldosterone, unlike SL1. Otherwise at P1 ANH levels remained unchanged both basally and during exercise, while at P2 they decreased significantly vs. SL1, both basally and after exercise (from 13.3 +/- 5.7 to 3.5 +/- 1.2 and from 40.2 +/- 10.2 to 17.5 +/- 8.3, respectively; P < .05). Our data show that PRA and aldosterone levels were constantly suppressed at HA and were unresponsive to exercise, whereas the ANH response was significantly stimulated during acute HA exposure, but not during chronic exposure. This suggests that hypoxia-induced chemoreceptor stimulation may cause the natriuretic phenomenon through direct suppression of the RAAS.

Effects of high-altitude chronic hypoxia on platelet alpha 2-receptors in man

During chronic high-altitude (HA) exposure, basal and exercise-induced noradrenaline (NA) increases do not parallel blood pressure (BP) changes observed; unlike beta-adrenergic receptors, to our knowledge no data are available on alpha-receptors. We studied platelet alpha 2- and leucocyte beta-receptors and basal catecholamine levels in 11 trained climbers before and after they had spent a 15-day period at a height of over 4400 m. In six of the climbers we also evaluated catecholamines after maximal bicycle ergometer exercise. After chronic high-altitude exposure, a significant decrease was found in platelet alpha 2-receptor density and affinity [Bmax from 92.6 +/- 6.7 to 54.6 +/- 4.2 fmol mg-1 protein (P < 0.001) and KD from 1.271 +/- 0.034 to 1.724 +/- 0.077 nmol L-1 (P < 0.05)], although no changes to beta-receptors were observed. No changes were found in basal pre- and post-expedition NA and adrenaline (A), and there was only a slight decrease in post-expedition NA after maximal exercise. Our results suggest that prolonged exposure to hypoxia induces a down-regulation of alpha 2-receptors, which may be a contributory factor in the regulation of the physiological vascular response to acclimatization.

A new method for monitoring hydration at high altitude by bioimpedance analysis

Our study evaluated the performance of a graphical method for monitoring the fluid variation at high altitude in seven adult Caucasian male subjects (average age 25 yr, average height 177 cm). The graphical approach is called the Resistance-Reactance (RXc) graph method and is based on standard bioimpedance analysis (tetrapolar, 50 kHz frequency). Measurements were taken at sea level before the expedition, at 5050 m after 1 wk and 3 wk, and again at sea level after descent. Plasma and urine electrolytes, osmolalities, and the free-water clearance were determined by standard methods. All climbers had baseline impedance vectors within the reference 95% tolerance ellipse for the Italian male population. The high altitude dehydration caused a significant lengthening of vectors, which after descent underwent a significant shortening and returned close to the baseline values. Average urine volume increased by 1.4 l.d-1 in the first week and average body weight decreased by 4.4 kg after 3 wk. The RXc graph method could be useful in the planning of the individual climber's appropriate dehydration and fluid intake at altitude since a feedback control of the hydration is allowed without any assumption of body composition.

Cardiovascular neural regulation during and after prolonged high altitude exposure

Eight young healthy male subjects, members of a Himalayan expedition, underwent 24 h Holter monitoring before departure, after 1 and 4 weeks at high altitude (5000 m) and after return to sea level. At high altitude, the circadian reciprocal changes in low and high frequency (LF, HF) were absent, with no significant reduction in the LF to HF ratio over the 24 h; moreover, the proportion of adjacent R-R intervals that differed by more than 50 ms (pNN50) decreased significantly and remained lower after return to sea level. Urine catecholamines increased at high altitude, but only norepinephrine, after 1 week of exposure, rose significantly. Upon return to sea level the density, but not the affinity, of [alpha]2-adrenergic receptors on platelets decreased significantly compared to pre-expedition values. At high altitude increased sympathetic activity was indicated by elevation of urine norepinephrine and by the loss of circadian rhythm in spectral components. The simultaneous reduction of HF and pNN50 demonstrated decreased vagal tone. The persistence of increased sympathetic activity could explain the downregulation of adrenergic receptors after prolonged high altitude exposure.

[Pharmacologic treatment of constitutional short stature]

The term constitutional short stature is used to describe clinical situations characterized by low stature, assessed using special growth nomograms, but which are not due to specific endocrine alterations, nor to genetic causes or skeletal dysmorphisms, nor secondary to specific organ pathologies or chronic diseases. On the basis of this definition, our paper also includes the so-called normal variants of short stature (familial short stature and constitutional delay of growth) and intrauterine growth retardation. The endocrine and auxological features of constitutional short stature are described in the literature and provide an adequate basis for the use of therapies which include, in addition to growth hormone, substances capable of stimulating the endogenous secretion of the hormone (L-dopa, bromocriptine, clonidine, GHRH, pyridostigmine), or anabolic hormones. Biosynthetic growth hormone therapy is without doubt the most widely used, both on account of the extensive clinical experience and due to the easy availability of the drug made possible by the use of the biosynthetic molecule. Many subjects affected by constitutional short stature show a good response to hGH therapy, whereas others do not benefit by this treatment. New therapies using GHRH and neurodrugs, which are certainly easier to handle and less expensive, represent a new approach to the therapy of constitutional short stature but this condition still requires further investigation.

Lack of effect of im diazepam administration on hGH and hPRL secretion in normal and acromegalic subjects

The usefulness of diazepam as a provocative stimulus for hGH secretion has been suggested as a simple, reliable test in clinical hGH assessment of pituitary disorders. We have investigated the effects of diazepam (10 mg im) on plasma hGH and hPRL in 5 normal and 7 acromegalic subjects. No significant variations in hGH and hPRL levels have been observed in any of the studied subjects. These findings indicate that the drug is ineffective on hGH and hPRL release and that it cannot be considered a valid provocative test either in normal or acromegalic subjects.

Effects of pirenzepine on plasma insulin, glucagon and pancreatic polypeptide levels in normal man

The secretion of various pancreatic hormones (insulin, glucagon and pancreatic polypeptide) is affected to a different extent by the cholinergic system. In 7 healthy subjects the effects of treatment for 1 week with pirenzepine, an anticholinergic drug selective for muscarinic receptors, on basal secretion of these hormones and on that induced by i.v. glucose (IVGTT) and arginine were evaluated. The drug did not reduce basal levels of insulin and glucagon whereas it caused an appreciable reduction in basal pancreatic polypeptide (PP). The responses of insulin and blood glucose to IVGTT and to arginine were not changed by treatment, nor was that of plasma glucagon to arginine. The infusion of arginine did induce an increase in PP level, which reached a statistically significant maximum at 90 min. This response was not particularly different after administration of pirenzepine. Thus, the results confirm the finding that arginine stimulates PP secretion in vivo and that pirenzepine reduces the basal level of the hormone, whereas it did not appear to affect the response to arginine. The findings exclude any direct action of the drug on insulin or glucagon secretion or on glucose metabolism in general.

Effects of sodium DL-lactate on insulin secretion in anesthetized dogs

The effect of sodium DL-lactate administration on insulin release in anesthetized dogs has been studied. Eleven mongrel dogs were infused with sodium DL-lactate for 20 min at the rate of 20 mg/kg . min. Lactate infusion produced simultaneous increases in blood glucose and plasma insulin levels in the pancreaticoduodenal vein. To determine whether lactate stimulated insulin secretion directly, sodium DL-lactate was rapidly injected into the pancreatic artery of six dogs; this pulse induced a significant increase in insulin release from pancreatic B-cells, even in the absence of a measurable change in blood glucose. Diazoxide, when infused in six dogs, blocked lactate-induced insulin secretion. These findings indicate that lactate, as do other circulating energy fuels, may play a role in the physiologic control of insulin secretion.

Studies on metabolic alterations after a mixed meal and during a 39-hour fast in thyrotoxicosis

In order to determine the endocrine and metabolic state of thyrotoxicosis we measured blood glucose and plasma insulin response to ingestion of a mixed meal in 19 euthyroid and 9 hyperthyroid subjects. Moreover concentrations of glucose, free fatty acids (FFA), glycerol, acetoacetate (AcAc) beta-hydroxybutyrate (beta-OHB), insulin and human growth hormone (hGH) were determined in the blood of both healthy and hyperthyroid patients after an overnight and a 39-h fast. In another group of thyrotoxics the overnight fasting respiratory quotient (RQ) was measured. After a mixed meal blood glucose and plasma insulin changes of FFA, AcAc and beta-OHB was significantly higher in thyrotoxics, whereas hGH increase did not appear significantly greater in these subjects. There was no statistical difference between the respiratory quotient mean values found in hyperthyroid and in control subjects. In conclusion, these data indicate that in thyrotoxicosis absolute insulin response to a mixed meal is normal and that food deprivation considerably increase lipid mobilization from adipose tissue and causes an exaggerated starvation ketosis. The RQ mean valoue suggests that in the hyperthyroid state lipid-derived fuel as well as carbohydrate-derived fuel contributes to the increased oxygen consumption.

Metabolic and endocrine responses to a standard mixed meal. A physiologic study

In order to study endocrine and metabolic responses to normal food ingestion, 8 'healthy' subjects received a standard mixed meal which reflected the composition of Western diet (CHO 47%, protein 23%, fat 26%, alcohol 4%), in 20 min. Before and after the meal, in each subject glucose, lactate, FFA, insulin, C-peptide, glucagon and HGH were determined. The results showed that glycemic and insulinemic responses were not very different from those observed after the classical oral glucose tolerance test. Plasma FFA and blood lactate decreased progressively after the meal. Plasma glucagon and HGH showed opposite changes: pancreatic glucagon rose and HGH slightly declined after composite food ingestion.

The effect of propranolol on hypoglycaemia. Observations in five insulinoma patients

Five hypoglycaemic hyperinsulinaemic patients (three with proven benign insulinoma, one with proven metastasizing insulinoma, one with probable insulinoma not found at surgery) were treated with propranolol for a variable time ranging from two weeks to one year. Three patients showed favourable clinical results and a significant increase of the mean basal blood glucose level was found while two patients showed no improvement of the frequency of neuroglycopenic episodes and no significant increase of their mean blood glucose level. No patient showed a significant decrease in mean basal IRI concentration. A decrease of insulinaemic responses was observed during oral and intravenous glucose tolerance tests, a prolonged fast, and tolbutamide and glucagon tests performed in some patients. The results suggest that propranolol may induce in certain patients an improvement of basal clinical status through not understood effects (probably hepatic), which leave the peripheral concentrations of insulin unchanged, whereas inhibition of insulin secretion may represent the main way by which the improvement of metabolic situation during physiological or pharmacological stimulation may have been achieved.

Plasma insulin response to glibornuride in thyrotoxicosis

The glycemic and insulinemic response to i.v. glibornuride injection has been studied in a group of 8 euthyroid subjects and in a group of 9 thyrotoxic patients before and after reserpine treatment. In thyrotoxic patients sulfonylurea did not lower blood glucose more than in normal subjects. The plasma insulin response, however, was definitely higher than that of the controls in the first few minutes; after the 20th minute, however, levels of insulinemia were not appreciably different in the two groups. Insulin delivery rate was greater in hyperthyroid patients than in the controls. Administration of reserpine for a few days, did not modify either insulin response or blood glucose fall in thyrotoxic patients.