Physiological and metabolic functions of melatonin

Melatonin is a lipophilic hormone, mainly produced and secreted at night by the pineal gland. Melatonin synthesis is under the control of postganglionic sympathetic fibers that innervates the pineal gland. Melatonin acts via high affinity G protein-coupled membrane receptors. To date, three different receptor subtypes have been identified in mammals: MT1 (Mel 1a) and MT2 (Mel 1b) and a putative binding site called MT3. The chronobiotic properties of the hormone for resynchronization of sleep and circadian rhythms disturbances has been demonstrated both in animal models or in clinical trials. Several other physiological effects of melatonin in different peripheral tissues have been described in the past years. In this way, it has been demonstrated that the hormone is involved in the regulation of seasonal reproduction, body weight and energy balance. This contribution has been focused to review some of the physiological functions of melatonin as well as the role of the hormone in the regulation of energy balance and its possible involvement in the development of obesity.

Technical note: Signal resolution increase and noise reduction in a CCD digitizer

Increasing output resolution is assumed to improve noise characteristics of a CCD digitizer. In this work, however, we have found that as the quantization step becomes lower than the analog noise (present in the signal before its conversion to digital) the noise reduction becomes significantly lower than expected. That is the case for values of sigma(an)/delta larger than 0.6, where sigma(an) is the standard deviation of the analog noise and delta is the quantization step. The procedure is applied to a commercially available CCD digitizer, and noise reduction by means of signal resolution increase is compared to that obtained by low pass filtering.

Influence of two polymorphisms of the tumoral necrosis factor-alpha gene on the obesity phenotype

Several populational-based studies have suggested an association between tumoral necrosis factor-alpha (TNF-alpha) polymorphisms and obesity-related phenotypes. Therefore, this study aimed at assessing the situation (frequency and associated phenotype) of two TNF-alpha common polymorphisms in a Spanish population. In a case-control design study, a group of Spanish subjects (n=313) were genotyped for the TNF-alpha G/A -308 and -238 polymorphisms. Obese subjects (cases) were compared with lean individuals (controls) according to body mass index (BMI; cases: BMI >30 kg/m2, controls: BMI <25 kg/m2). Waist-to-hip ratio, body composition and some metabolic indicators were assessed. The frequency of the -308A allele (0.14) and -238A allele (0.09) was similar to those previously reported in other Caucasian populations. Interestingly, cases with the -308A allele of the TNF-alpha gene have significantly higher hip and waist circumferences (p<0.05), BMI (p<0.01) and body fat mass (p<0.05) values than obese individuals carrying the -308G allele, but not the waist-to-hip ratio. No apparent influence of the -308A polymorphism on other metabolic indicators (insulin and leptin levels) was found. We could not detect any association between the substitution at position -238 polymorphism of the TNF-alpha gene and obesity anthropometrical phenotypes in this Spanish population, despite some differences in plasma leptin. These results support the hypothesis that the G/A -308 polymorphism of the TNF-alpha gene is associated with a higher BMI as well as hip ad waist circumferences, particularly on female bearers, while no influence on such measurements was found for the G/A -238 TNF-alpha gene polymorphism, but only an effect on leptinaemia.

Community-acquired febrile urinary tract infection in diabetics could deserve a different management: a case-control study

OBJECTIVE

To investigate if there are relevant differences in clinical, microbiological and outcome characteristics of community-acquired febrile urinary tract infection (UTI) between diabetic and nondiabetic patients.

DESIGN

A prospectively matched case-control study.

SETTING

An 800-bed tertiary care university-affiliated hospital.

SUBJECTS

A total of 108 patients (54 diabetic and 54 nondiabetic patients matched by age and gender) admitted between January 1996 and September 1999 with febrile UTI.

METHODS

Clinical, analytical, microbiological and outcome variables were analysed by means of McNemar test (categorical) or Wilcoxon matched pairs signed rank test (continuous).

RESULTS

Mean age (SD) in both groups was 67.9 (14.4) years. In comparison with controls, diabetic patients were more likely to have fever without localizing symptoms (27% vs. 9%, P </= 0.0001), diminished consciousness level at admission (25% vs. 10%, P = 0.03), aetiological microorganism different from Escherichia coli (17% vs. 0, P = 0.0004), and quinolone-resistant bacteria (17% vs. 3.7%, P = 0.07). Duration of fever after the onset of treatment was 1.75 (1) days in diabetics and 1.5 (1.1) days in nondiabetics (P = 0.17). However, diabetic patients had a longer hospitalization [5.2 (3.3) days] than nondiabetics [3.9 (2.6) days, P = 0.006].

CONCLUSIONS

In diabetic patients, febrile UTIs have clinical and microbiological peculiarities that may have diagnostic and therapeutic implications.

Effects of arachidonic acid on leptin secretion and expression in primary cultured rat adipocytes

Leptin, a hormone produced in adipocytes, is a key signal in the regulation of food intake and energy expenditure. Several studies have suggested that leptin can be regulated by macronutrients intake. Arachidonic acid is a dietary fatty acid known to affect cell metabolism. Controversial effects of this fatty acid on leptin have been reported. The aim of this experimental trial was to evaluate the effect of the arachidonic acid on basal and insulin-stimulated leptin secretion and expression in isolated rat adipocytes. Because insulin-stimulated glucose metabolism is an important regulator of leptin expression and secretion by the adipocytes, the effects of the arachidonic acid on indices of adipocyte metabolism were also examined. Isolated adipocytes were incubated with arachidonic acid (1-200 microM) in the absence and presence of insulin (1.6 nM). Leptin secretion and expression, glucose utilization and lactate production were determined at 96 h. The arachidonic acid (200 microM) inhibited both the basal and insulin stimulated leptin secretion and expression. Glucose utilization was not affected by the acid. Basal lactate production was increased by the fatty acid at the highest concentration used (200 microM), however lactate production in presence of insulin was not modified. Finally, the percentage of glucose carbon released as lactate was significantly increased (200 microM). These results suggest that the inhibitory effect of the arachidonic acid on leptin secretion and expression may be due, al least in part, to the increase in the anaerobic utilization of glucose.

Trends in frequency and in vitro susceptibilities to antifungal agents, including voriconazole and anidulafungin, of Candida bloodstream isolates. Results from a six-year study (1996-2001)

The frequency of isolation and antifungal susceptibility patterns to established and two new antifungal agents were determined for 218 Candida spp isolates causing bloodstream infection from 1996 to 2001. Overall, 41.7% of the candidemias were due to C. albicans, followed by C. parapsilosis (22%), C. tropicalis (16.1%), C. glabrata (11.9%), C. krusei (6%) and miscellaneous Candida spp (2.3%). Isolates of C. albicans C. parapsilosis and C. tropicalis (80% of isolates) were highly susceptible to fluconazole (94 to 100% at </= 8 microg/ml) and voriconazole (97 to 100% at </= 1 microg/ml). By comparison with the newer agents itraconazole was less active (77 to 97% at </=0.12 microg/ml). Only 77% and 15% of C. glabrata isolates were inhibited by fluconazole at </= 8 microg/ml and itraconazole at </=0.12 microg/ml, respectively. Voriconazole showed a remarkable in vitro potency against C. glabrata as well as C. krusei isolates (100% at </= 1 microg/ml). Anidulafungin was very active against Candida spp isolates (MIC90: </= 0.5 microg/ml), except C. parapsilosis (MIC90: 4 microg/ml) and two C. guilliermondii isolates (MIC: >/= 32 microg/ml).

A systematic review of socioeconomic differences in food habits in Europe: consumption of cheese and milk

OBJECTIVE

To assess differences in cheese and milk consumption across socioeconomic groups in representative samples from several European countries.

DESIGN

A meta-analysis of published and unpublished surveys of food habits performed in nine European countries between 1985 and 1999. Educational and occupational levels were used as indicators of socio-economic status.

RESULTS

A higher socioeconomic status was associated with a greater consumption of cheese. The pooled estimate of the difference in cheese consumption between women in the highest vs the lowest educational level was 9.0 g/day (95% CI: 7.1 to 11.0). The parallel observation in men was 6.8 g/day (95% CI: 3.4 to 10.1). Similar results were obtained using occupation as an indicator of socioeconomic status. The pooled estimates of the higher cheese consumption among subjects belonging to the highest (vs the lowest) occupational level were 5.1 g/day (95% CI: 3.7 to 6.5) in women and 4.6 g/day (95% CI: 2.1 to 7.0) in men. No statistically significant associations were found for milk consumption concerning educational or occupational level.

CONCLUSIONS

Our findings suggest that consumption of cheese is likely to be higher among subjects belonging to higher socioeconomic levels. We did not find enough evidence to support that milk intake is different according to educational or social levels.

[Causes of obesity]

The aetiology and treatment of obesity requires a knowledge of the mechanisms that control the homeostasis of the fuel substrates and adiposity. The processes of regulation adjust the supply of macronutrients and energy demands with the aim of maintaining a stable body mass. In the light of the most recent research, the hypothesis can be advanced that the control of body weight and its composition depends on an axis integrated by three self-regulated components: appetite, stores thermogenesis and fat deposits. The most important factors involved in obesity seem to be dietary habits diet and physical activity, which are affected by genes, which in their turn affect energy expenditure, the metabolism of energy substrates and food consumption. However, the growing rates of obesity cannot be explained exclusively by genetic causes, since they are in some cases associated with the consumption of diets with a high energy density or rich in fat, and by a growing sedentary life style in society, both in developed and developing countries. The study of genetics and life style involved in the increase of body weight and obesity can facilitate the implementation of preventive actions.

[Adipose tissue: a storage and secretory organ]

The adipose tissue plays a fundamental role in maintaining the energy balance in mammals. During periods of high energy intake, the adipocytes store energy in the form of fat (triglycerides), which can be mobilized as free fatty acids during energy deprivation. Adipose tissue can no longer be considered only as a passive tissue that simply stores energy. Some recent discoveries have made it evident that this is a very active endocrine tissue that secretes important molecules related to different processes such as the immune response (TNF alpha) the regulation of food intake and expenditure of energy (leptin, Acrp30/adipoQ) and the vascular function (angiotensin and plasminogen activator inhibitor type 1). Alterations in the growth, development and function of the adipose tissue might therefore be involved in the development of different pathologies such as obesity, insulin resistance and type 2 diabetes, hypertension and atherosclerosis. A deeper understanding of the adipose tissue (morphology, development-adipogenesis, role in the metabolism and in the regulation of body weight, endocrine functions.) is needed for an adequate study of the underlying aspects in the development of obesity.

[Distribution of macronutrients from the diet and regulation of weight and body composition: role of lipids intake in obesity]

The maintenance of a stable body weight and composition over time depends, amongst other factors, on the equilibrium in the balance between the intake and metabolic utilisation of the macronutrients in the diet. The organism appears to give greater priority to the adjustment of the oxidation of glucose and amino acids in relation to their ingestion than to the maintenance of the balance of fats. The system of homeostatic self-regulation of the lipid balance is not very efficient, besides which the capacity of storing of energy reserves in the adipose tissue is almost unlimited. Besides, fat appears to confer palatability and flavour on foodstuffs, which could lead to greater consumption. Excessive ingestion of fat is one of the factors that is most frequently associated with a high prevalence of obesity. Some studies indicate that some obese subjects show a reduced capacity for oxidising fatty acids. In this context, the reduction of lipid ingestion is one of the strategies most frequently recommended in the prevention of the epidemic of obesity. However, the role of the lipid intake of the diet in the prevalence and subsequent treatment of obesity is nowadays the subject of scientific controversy.

[Obesity prevalence in Europe]

The prevalence of obesity is increasing in an alarming way, while that of other risk factors (hyperlipaemia, arterial hypertension.) are tending to diminish. Amongst all of the factors involved in its development, two are outstanding because of their potential for modification: an excessive calorie intake and a sedentary life style, in spite of the recommendations in favour of regularly practising physical exercise. The principal problem in studying the prevalence of obesity is the scarcity of studies that analyse it in a global form. In 1989 the first results of the MONICA project of the WHO were published, with the observation that the prevalence was higher for men than for women, and that it was greater in the Mediterranean countries and the east of Europe, in comparison with the north and centre-west. In 1997 a study was carried out by the Institute of European Food Studies (IEFS) in which 15,239 individuals participated proceeding from representative samples of the 15 Member States of the European Union. Its results showed that the higher prevalence of obesity was to be found in the United Kingdom (12%), followed by Spain (11%), while it was lower in Italy, France and Sweden (7%). By sex, the prevalence of obesity is somewhat greater amongst women, while overweightedness was greater amongst men. In Spain the distribution of overweightedness and obesity amongst the different socio-economic groups is similar to that of other regions, with the percentage of obesity being highest amongst the elderly, subjects of a lower socio-economic level and the inhabitants of the north and north-west of Spain.

[Methodology for the study of the regulation of body weight and/or the aetiology of obesity]

Obesity, one of the most serious health problems of developed societies, is the result of a positive energy balance maintained over time. The regulation of body weight and its maintenance seem to be regulated by an axis of three interdependent components: dietary intake, energy expenditure and adipogenesis, although it is necessary a deeper understanding of the processes involved in the oxidation of nutrients and in the energy balance. The metabolic processes are numerous and inter-related, it is however convenient to study them separately in such a way that it is possible to obtain a better knowledge of the complete system. Indeed, this is the procedure employed in the design of numerous experiments, be they on laboratory animals, cellular cultures, or even on human beings when the molecular mechanisms involved in the regulation of body weight are examined. Both in vitro methods (cellular and subcellular models) and in vivo ones have made it possible to increase knowledge of the mechanisms that control body weight. It is worth underlining the new strategies that the molecular era and provides us with, although the techniques that consider the human organism as a whole might have a notable influence on the development of new drugs, together with therapeutic management and the prevention of obesity.

Is azithromycin the first-choice macrolide for treatment of community-acquired pneumonia?

Combination treatment with a beta-lactam plus a macrolide may improve the outcome for elderly patients with community-acquired pneumonia (CAP). The prognoses and mortality rates for elderly patients with CAP who receive ceftriaxone combined with a 3-day course of azithromycin or a 10-day course of clarithromycin were compared in an open-label, prospective study. Of 896 assessable patients, 220 received clarithromycin and 383 received azithromycin. There were no significant differences between groups with regard to the severity score defined by the Pneumonia Patient Outcomes Research Team (PORT) study group; the incidence of bacteremia was also not significantly different. However, for patients treated with azithromycin, the length of hospital stay was shorter (mean+/-SD, 7.4+/-5 vs. 9.4+/-7 days; P<.01) and the mortality rate was lower (3.6% vs. 7.2%; P<.05), compared with those treated with clarithromycin. There might be a difference in the outcome for patients with CAP depending on the macrolide used. A shorter treatment course with azithromycin may result in better compliance with therapy.

C-reactive protein levels in community-acquired pneumonia

The diagnostic value of C-reactive protein (CRP) admission serum levels as an indicator of the aetiology of community-acquired pneumonia (CAP) was evaluated. A cohort of 1,222 patients with CAP was assessed. CRP levels were analysed in 258 patients with a single aetiological diagnosis. The mean CRP values in patients with pyogenic, atypical, viral and Legionella pneumophila pneumonia were: 16 mg x dL(-1), 13 mg x dL(-1), 14 mg x dL(-1) and 25 mg x dL(-1), respectively. CRP levels were not significantly different among patients outcome research team (PORT) groups (19 mg x dL(-1) in groups I-II, 16 mg x dL(-1) in group III and 16 mg x dL(-1) in groups IV-V). A cut-off point of 25 mg x dL(-1) had a sensibility, specificity, positive predictive value and negative predictive value of 0.6, 0.83, 0.3, and 0.94, respectively. After controlling for age and PORT score, the odds of having a CRP level >25 mg x dL(-1) was 6.9 times higher in patients with L. pneumophila pneumonia than in those with non-L. pneumophila pneumonia. Patients with Legionella pneumophila pneumonia had higher C-reactive protein levels than those with pneumonia of any other aetiology, independently of severity of infection. Being a cheap and readily available test, C-reactive protein may be a useful adjunctive procedure in the diagnosis of community-acquired pneumonia.

Bacteraemia in adults due to glucose non-fermentative Gram-negative bacilli other than P. aeruginosa

BACKGROUND

Glucose non-fermentative Gram-negative bacilli other than P. aeruginosa (NF) are emerging pathogens.

AIM

To evaluate the epidemiology, clinical characteristics, predictors of acquisition, and outcome of bacteraemia due to NF.

DESIGN

Retrospective analysis of prospectively recorded data.

METHODS

We reviewed episodes of NF bacteraemia in patients older than 14 years, recorded through a blood culture surveillance program. Patients were identified at the time of their bacteraemia and prospectively followed.

RESULTS

Between January 1991 and December 2000, 296 episodes of NF bacteraemia were detected: 87% were due to Acinetobacter sp., Pseudomonas sp. other than P. aeruginosa, or Stenotrophomonas maltophilia. The global incidence (0.87 cases per 1000 discharges) remained stable during the study period. Patients were of all ages and both sexes, and 282/296 (95.3%) had some predisposing underlying disease or condition, the most common being haematological malignancies without transplantation (85/296, 28.7%), treatment with steroids (78/296, 26.3%), and transplantation (bone marrow or solid organ) (70/296, 23.6%). Fifty (16.9%) were neutropenic. The most common sources of bacteraemia were central venous catheter infection (117/296, 39.5%) and unknown primary site (97/296, 32.8%). Sixty-one episodes (20.6%) were community-acquired and 235 (79.4%) were nosocomial. Forty-three patients (14.5%) died. Pneumonia (RR 1.5, 95%CI 1.1-14.2), age<65 (RR 3.1, 95%CI 1.4-10.3), hospitalization in the intensive care unit (ICU) (RR 3.2, 95%CI 1.3-9.8), rapidly fatal disease (RR 4.9, 95%CI 3.1-12.6), and severe sepsis (RR 9.8, 95%CI 1.6-19.7) were independent predictors of death. Factors predicting the probability that an episode of nosocomial bacteraemia was due to NF included: rapidly fatal disease (RR 1.23, 95%CI 1.02-4.1), age<65 (RR 2.05, 95%CI 1.4-3), hospitalization in the ICU (RR 2.06, 95%CI 1.4-3, and pneumonia (RR 2.1, 95%CI 1.05-4.8).

DISCUSSION

NF bacteraemia mainly affects patients with malignant haematological disease, with and without transplantation, and patients in the ICU. The most common known source is a central venous catheter, though many sources are unknown. Mortality is relatively low, and depends on the severity of the underlying disease.

A nosocomial outbreak of influenza during a period without influenza epidemic activity

The objective of this study was to describe a nosocomial outbreak of influenza during a period without influenza epidemic activity in the community. Outbreak investigation was carried out in an infectious diseases ward of a tertiary hospital. Presence of two or more of the following symptoms were used to define influenza: cough, sore throat, myalgia and fever. Epidemiological survey, direct immunofluorescence, viral culture, polymerase chain reaction, haemagglutination-inhibition test in throat swabs and serology for respiratory viruses were performed. Twenty-nine of 57 healthcare workers (HCW) (51%) and eight of 23 hospitalised patients (34%) fulfilled the case definition. Sixteen HCW (55%) and three inpatients (37%) had a definitive diagnosis of influenza A virus infection (subtype H1N1). Among the symptomatic HCW, 93% had not been vaccinated against influenza that season. Affected inpatients were isolated and admissions in the ward were cancelled for 2 weeks. Symptomatic HCW were sent home for 1 week. On the seventeenth day of the outbreak the last case was declared. The incidence of cases in this outbreak of influenza, which occurred during a period without influenza epidemic activity in the community, was notably high. Epidemiological data suggest transmission from healthcare workers to inpatients. Most healthcare workers were not vaccinated against influenza. Vaccination programmes should be reinforced among healthcare workers.

Determinants of the adherence to an "a priori" defined Mediterranean dietary pattern

BACKGROUND

A prospective cohort study with university level participants was initiated to study the effect of Mediterranean diet on health.

AIMS

The objective of this study was to identify possible lifestyle and socioeconomic variables associated with the consumption of a Mediterranean dietary pattern (MDP).

METHOD

This analysis includes 1587 males and 2260 females. MDP was defined "a priori" by summing the standardized residuals of nutrients and foods after adjusting a regression model using total energy intake as the independent variable. Multiple regression and non-parametric locally weighted regression models were adjusted with the relative adherence to the MDP as the dependent variable in males and females.

RESULTS

Women were more compliant than men with the MDP (Coefficient regression (b) = 4.1; Confidence Interval (CI) 95 % = 3.2 to 4.9). The compliance with the MDP was significantly poorer among younger participants both in men and women (p < 0.001 in men and in women). Participants who were more physically active were more likely to fulfill the traditional MDP (p = 0.01 in men and p < 0.001 in women).

CONCLUSIONS

Our findings provide evidence supporting the progressive departure from the traditional MDP in younger and highly educated subjects of the Mediterranean area. A more active life-style is associated with a better compliance with the MDP.

The risk of obesity and the Trp64Arg polymorphism of the beta(3)-adrenergic receptor: effect modification by age

AIM

To examine the association between the risk of obesity and the Trp64Arg polymorphism of the beta(3)-adrenergic receptor gene.

METHODS

A case-control study was conducted. The case series encompassed 159 subjects with a body mass index >30 kg/m(2) (obesity) and no other major diseases except for type 2 diabetes, and the controls were 154 healthy subjects with a body mass index <25 kg/m(2). 313 Spanish subjects between 20 and 60 years of age were screened for the Trp64Arg mutation.

RESULTS

The prevalence of the Trp64Arg mutation was similar among cases (19.5%) and control subjects (16.2%). The association between the risk of obesity and the Trp64Arg mutation was estimated using multivariate logistic regression. A higher odds ratio of 3.84 (95% CI 1.33-11.12) for the mutation was found among younger individuals (20-35 years), while no increased risk was apparent among older participants (35-60 years). Moreover, when the model was adjusted for gender, age, and leisure-time physical activity, the product-term for interaction (effect modification) between age and the presence of the Trp64Arg mutation was statistically significant (likelihood ratio test p = 0.035).

CONCLUSION

Individuals aged 20-35 years who are Trp64Arg carriers had a substantially higher risk of developing obesity, independent of their sex or leisure-time physical activity.

Factors associated with unknown aetiology in patients with community-acquired pneumonia

Despite comprehensive diagnostic work-up, the aetiology of community-acquired pneumonia (CAP) remains undetermined in 30-60% of cases. The authors studied factors associated with undiagnosed pneumonia. Patients hospitalised with CAP and being evaluated by two blood cultures, at least one valid lower respiratory tract sample, and serology on admission were prospectively recorded. Patients who had received antimicrobial pretreatment were excluded. Patients with definite or probable aetiology were compared to those with undetermined aetiology by uni- and multivariable analysis. A total 204 patients were eligible for the study. The aetiology remained undetermined in 82 (40%) patients, whereas a definite aetiology could be established in 89 (44%) and a probable one in 33 (16%). In multivariable analysis, factors associated with undetermined aetiology included age >70 yrs, renal and cardiac comorbidity, and nonalveolar infiltrates on the chest radiograph. There was no association of undiagnosed pneumonia with mortality. Age and host factors were associated with unknown aetiology of community-acquired pneumonia. Some of these cases may also represent fluid volume overload mimicking pneumonia.

Obesity and immunocompetence

The increasing worldwide prevalence of obesity is a major health problem since excessive body weight constitutes a risk factor in a number of chronic diseases. It has been reported that obese individuals are more susceptible to infection than lean subjects; however, the underlying factors are not fully understood. Limited and often controversial information exists comparing immunocompetence in obese and nonobese subjects as well as the cellular and molecular mechanisms involved, although much evidence supports a link between adipose tissue metabolism and immunocompetent cell functions. The complexity and heterogeneity of nutritional status and immune system interactions require an integral study of the immunocompetent cells, their subsets and products, as well as specific and non-specific inducer/regulatory systems in situations of human obesity. Additional research is needed to determine the clinical implications of these alterations on immunity and whether various interventions such as weight loss, exercise or nutrient supplementation could help to ameliorate them.

Effects of Trecadrine, a beta3-adrenergic agonist, on leptin secretion, glucose and lipid metabolism in isolated rat adipocytes

OBJECTIVE

Leptin, a hormone produced in adipocytes, is a key signal in the regulation of food intake and energy expenditure. Beta-adrenergic agonists have been shown to inhibit leptin gene expression and leptin secretion. The mechanisms underlying the inhibitory effects of beta-adrenergic agonists have not been established. In this study, we examined the effects of Trecadrine, a novel beta3-adrenergic agonist, on basal and insulin-stimulated leptin secretion in isolated rat adipocytes. Because insulin-stimulated glucose metabolism is an important regulator of leptin expression and secretion by the adipocytes, the effects of Trecadrine on indices of adipocyte metabolism were also examined.

MEASUREMENTS

Isolated adipocytes were incubated with Trecadrine (10(-8)-10(-4) M) in the absence or presence of insulin (1.6 nM). Leptin secretion, glucose utilization, lactate production, glucose incorporation into CO(2) and triglyceride, as well as lipolysis (glycerol release) were determined.

RESULTS

Trecadrine induced a concentration-dependent inhibition of basal leptin secretion. Trecadrine also decreased insulin-stimulated leptin secretion; however, the effect was not as pronounced as in the absence of insulin. Treatment of adipocytes with Trecadrine increased basal glucose utilization and produced a further increase in insulin-stimulated glucose utilization. Basal lactate production was also increased by Trecadrine; however, the proportion (percentage) of glucose carbon released as lactate was unaffected. In the presence of insulin, absolute lactate production was unaffected by Trecadrine at 96 h. However, the percentage of glucose carbon released as lactate was significantly decreased by insulin treatment, and was further decreased by the co-treatment with Trecadrine. Trecadrine induced a dose-dependent increase of the absolute amount of glucose incorporated into triglyceride. However, the percentage of glucose utilized that was incorporated into triglyceride was unaffected by Trecadrine. Trecadrine did not modify the proportion of glucose utilized that was oxidized to CO(2). Trecadrine increased glycerol release after 96 h of treatment. Glycerol release was negatively correlated with leptin secretion.

CONCLUSIONS

These results suggest that alterations of glucose metabolism are not directly involved in the effects of beta3-adrenergic agonists to inhibit leptin expression and secretion. The inverse relationship between leptin secretion and the increase of glycerol levels, which is an index of the activation of cAMP-dependent protein kinases, suggests that activation of the cAMP signaling pathway mediates the inhibitory effects of Trecadrine on leptin gene expression and secretion.

Beta(2)-adrenergic receptor mutation and abdominal obesity risk: effect modification by gender and HDL-cholesterol

OBJECTIVE AND DESIGN

A case-control study was conducted to examine the association between the 27Glu polymorphism of the beta(2)-adrenergic receptor gene (ADRB2) and the risk of abdominal obesity (defined by a waist/hip ratio: WHR higher than 0.85).

METHODS

The case series encompassed 112 obese subjects with body mass index (BMI) > 30 kg/m(2) and WHR > 0.85 and no other major disease except for type 2 diabetes, while the controls were 127 healthy subjects, BMI < 25 kg/m(2) and WHR < 0.85.

RESULTS

The association between the risk of abdominal obesity and the 27Glu polymorphism was estimated using multivariate logistic regression. A higher crude odds ratio (OR) of 4.08 (95 % confidence interval: 0.98-16.3) for the 27Glu allele was found among men, while no increased risk was apparent among female participants. Moreover, when the model was adjusted for age, male subjects carriers of the 27Glu allele had a significant ten-fold higher risk of abdominal obesity (OR = 10.31; 95 % CI: 1.4-76.8) and the product-term for the interaction (effect modification) between gender and the ADRB2 mutation was near to the limits of statistical significance (Likelihood ratio test p = 0.056). Interestingly, we also found an effect modification with higher OR among individuals with low HDL-cholesterol (< 1.5 mmol/l) after adjustment for age and gender (OR = 2.87 95 % CI 1.09-7.50) and the product-term for interaction between the 27Glu allele and HDL-cholesterol was statistically significant (Likelihood ratio test p = 0.003).

CONCLUSIONS

Our results showed that the 27Glu allele of the ADRB2 gene appears to be a risk factor for abdominal obesity among male subjects, specially among those with lower HDL-cholesterol levels.

Down-regulation of heart HFABP and UCP2 gene expression in diet-induced (cafeteria) obese rats

Long-term exposure to hypercaloric high fat diet induced marked tissue fatty acid accumulation and may influence cell function. Previous results in our laboratory showed that uncoupling proteins (UCPs) and fatty acid-binding protein (FABP) gene expression are changed in adipose tissue and skeletal muscle tissue in diet-induced (cafeteria) obese animals. The aim of this study was to examine heart FABP (HFABP) and UCP2 gene expressions in dietary obese rats. Rats fed on a high-fat diet for 65 days had significantly higher fat stores and body weight than control rats. Interestingly, we found that both HFABP and UCP2 mRNA levels were significantly reduced in cafeteria-obese rats when compared to control animals. Moreover, a statistically significant correlation was observed between the two gene expression levels. The down-regulation of heart HFABP and UCP2 parallels the lower lipid utilization which may account for an enhanced fat deposition. It is plausible that these two genes are regulated by the same family of transcription factors.

A maximal effort trial in obese women carrying the beta2-adrenoceptor Gln27Glu polymorphism

The aim of this study was to observe the relationship of the beta2-adrenoceptor (ADRB2) gene polymorphism Gln27Glu in a group of obese female subjects submitted to an acute physical activity test. Six Glu27/Glu27 obese women were compared with six Gln27/Gln27 obese women (coupled by age, BMI, waist circumference, percentage of fat mass and absence of smoking). These groups were selected after having genotyped 91 obese subjects (BMI>30 kg/m2, age 20-60). Polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) were used to genotype the obese population. The physical activity challenge consisted of a Maximal effort trial (VO2 max) following the Bruce protocol on a walking treadmill. The frequency for the Glu allele was 0.42, which is similar to other Caucasian populations. In basal conditions, subjects with the Glu27/Glu27 genotype showed a higher value of plasma insulin, while circulating glucose levels were similar in both groups. Also, diastolic arterial pressure was higher in the Glu27/Glu27 obese women. After the VO2 max trial, the Glu27 group had a significantly higher respiratory exchange ratio than the Gln27 group suggesting a lower post- exercise fat oxidation. These results provide evidence about a possible impact of the Gln27Glu polymorphism in the ADRB2 gene concerning a better response to exercise in obese Gln27 female subjects, in which basal insulinemia may play a role.

Inhibition of chaotic escape from a potential well by incommensurate escape-suppressing excitations

Theoretical results are presented concerning the reduction of chaotic escape from a potential well by means of a harmonic parametric excitation that satisfies an ultrasubharmonic resonance condition with the escape-inducing excitation. The possibility of incommensurate escape-suppressing excitations is demonstrated by studying rational approximations to the irrational escape-suppressing frequency. The analytical predictions for the suitable amplitudes and initial phases of the escape-suppressing excitation are tested against numerical simulations based on a high-resolution grid of initial conditions. These numerical results indicate that the reduction of escape is reliably achieved for small amplitudes and at, and only at, the predicted initial phases. For the case of irrational escape-suppressing frequencies, the effective escape-reducing initial phases are found to lie close to the accumulation points of the set of suitable initial phases that are associated with the complete series of convergents up to the convergent giving the chosen rational approximation.

No evidence for an association between genetic polymorphisms of beta(2)- and beta(3)-adrenergic receptor genes with body mass index in Aymara natives from Chile

OBJECTIVE

We assessed the association between Gln27Glu and Trp64Arg genetic polymorphisms of the beta(2) (ADRB2) and beta(3) (ADRB3) adrenergic receptor genes with body mass index and other cardiovascular risk factors.

METHODS

In a cross-sectional study, adult Aymara subjects (n = 152) living in the Andean regions of northern Chile were characterized with respect to their ADRB2 and ADRB3 genotypes, body mass index, plasma leptin and insulin levels, fasting glucose concentration, blood pressure, and plasma lipid profile.

RESULTS

The frequency of the Glu27 allele of the ADRB2 gene was estimated to be 0.04, and the allele frequency of the Arg64 variant of the ADRB3 gene was estimated as 0.13. No associations were found between the Trp64Arg polymorphism of the ADRB3 gene and body mass index or other cardiovascular risk factors. The small number of subjects with the allele encoding Glu27 in the ADRB2 gene seriously limited the analysis of the association between genotype and phenotype with the use of this polymorphism, although no clear associations were found.

CONCLUSION

We found insufficient evidence to support an association between polymorphisms Gln27Glu and Trp64Arg of the ADRB2 and ADRB3 genes, respectively, with body mass index and other cardiovascular risks in the rural Aymara population from Chile.

Interactions between an alpha2-adrenergic antagonist and a beta3-adrenergic agonist on the expression of UCP2 and UCP3 in rats

This experimental trial was devised to assess whether selective beta3-adrenergic receptor (AR) stimulation and simultaneous blockade of alpha2-AR would affect thermoregulation. With this purpose, the individual and combined administration of a beta-AR agonist, trecadrine, and an alpha2-AR antagonist, yohimbine, were evaluated. Yohimbine produced a marked decrease (p < 0.001) in body temperature one hour after administration (5 mg kg(-1), i.p.) and blocked the thermogenic effect of trecadrine (1 mg kg(-1), i.p.) when simultaneously administered. Uncoupling protein-2 expression in skeletal muscle was downregulated (p < 0.05) by trecadrine, while yohimbine had no effect. White adipose tissue UCP2 and muscle UCP3 were not modified by either trecadrine or yohimbine administration. Liver UCP2 mRNA expression was significantly decreased by yohimbine (p < 0.05). However, this downregulation does not seem to explain the reduction in temperature produced by yohimbine given the fact that trecadrine produced a similar downregulation of hepatic UCP2 (p < 0.05). The present work indicates that alpha2-AR antagonism blocks the thermogenic effects mediated by beta3-AR stimulation, contrary to our expectations, suggesting a possible interplay between both mechanisms. Moreover, these effects are not apparently explained by changes in UCP2 and UCP3.

Changes in UCP2, PPARgamma2, and c/EBPalpha gene expression induced by a neuropeptide Y (NPY) related receptor antagonist in overweight rats

Neuropeptide Y (NPY), a peptide released by nervous cells, appears to contribute to adiposity regulation by increasing food intake and inhibiting lipolysis. New NPY receptor related antagonists such as S.A.0204 are being developed as potential anti-obesity drugs affecting adipocyte lipid metabolism and thermogenesis. In this sense, those animals fed on a high-energy yielding (cafeteria) diet decreased body fat weight as compared to overweight controls, when they were administered with S.A.0204, and increased body temperature, which statistically correlated with high UCP2 mRNA expression levels in white adipose tissue. In addition, the in vivo NPY-antagonist administration was able to prevent white adipose tissue growth in animals fed the cafeteria (high-fat) diet by impairing PPARy and CIEBPalpha mRNA expression in white fat cells. In summary, this novel NPY related-antagonist S.A.0204 may regulate body fat deposition by affecting both energy dissipation and white adipose tissue deposition, representing a potential new pharmacological strategy for obesity management.

Mediterranean diet and stroke: objectives and design of the SUN project. Seguimiento Universidad de Navarra

PURPOSE

The Mediterranean diet has been postulated as a protective factor against different diseases including stroke. Thus, an epidemiological study in a Mediterranean country, such as Spain, focused on diet may offer new insights of the potential benefits of this nutritional pattern to prevent the onset of cerebrovascular diseases.

METHODS

The SUN ("Seguimiento Universidad de Navarra") project is a prospective study among Spanish university alumni, aimed to identify the dietary determinants of stroke, coronary disease and other disorders. Two pilot studies have been developed. The first pilot study was focused on the understanding of the questionnaire. The second study used a random sample to assess the response proportion and the feasibility of using a mailing system for following-up the cohort. The first informative results are expected to be available after the first four years of following-up the cohort (2005). Here, we report the description of the baseline diet of the first participants in the cohort using data from 1,587 men and 2,260 women.

RESULTS

The outcome of our pilot studies ensure the feasibility of a mail-based cohort. In the baseline assessment, we found a high consumption of olive oil (18.5 g/person/day), red wine (28.8 g/person/day), legumes (102.5 g/person/day), vegetables (507.8 g/person/ day) and fruits (316.7 g/person/day), with a great between-subject variability. Also, the values for cereals (170.4g/person/day), dairy products (239.3 g/person/day) and meat and meat products consumption (186 g/person/ day) in this cohort were estimated. The coefficients of variation ranged in women from 56 (for vegetables) to 240% (for red wine) and in men from 62 to 180% (for these same two items), reflecting a wide heterogeneity in the diet of participants.

CONCLUSIONS

Although the participation was not high (22% according to the estimates of the pilot study), it was comparable to the proportion found in large previous cohorts such as the Nurses-II Health Study (24%). The sharp contrast in dietary habits between the US and Spain together with the high between-subjects variability we have found in our Spanish cohort provides an exceptional opportunity to assess the aspects of the Mediterranean diet, which may be protective against stroke and other neurological disorders.

Influence of dietary protein type and iron source on the absorption of amino acids and minerals

The apparent digestibility coefficient (ADC) of amino acids and the balance of minerals (calcium, phosphorus, magnesium and iron) has been determined in rats fed four diets differing in the protein type (casein or soy protein) and iron source (ferrous sulphate or lactate) in order to study the possible interactions of these nutrients. The availability of amino acids, especially essential amino acids, was greater in the diet made with animal protein (casein). The iron source also affected the absorption of most amino acids in all the diets assayed with ferrous sulphate being greater. The balance of iron, magnesium and phosphorus was higher in the diets containing animal protein. The retention of calcium and magnesium was significantly greater when ferrous sulphate was used as iron source. These results demonstrate the important interaction between amino acids and minerals and between the minerals themselves, which must be carefully studied when selecting different types of protein or mineral sources in human or animal nutrition.

Effects of leptin resistance on acute fuel metabolism after a high carbohydrate load in lean and overweight young men

OBJECTIVE

Six lean (BMI = 20.8 +/- 0.7) and seven overweight (BMI = 30.8 +/- 1.7) young men (18-27 years old) were studied to investigate the acute effect of a high-carbohydrate meal on leptin levels and its relation to energy expenditure as well as to protein, carbohydrate and fat oxidation.

METHODS

Study participants were given a high-carbohydrate meal (17% as protein, 80% as carbohydrates and 3% as lipids) covering 40% of their estimated daily energy requirements. Serum leptin. insulin. glucose, free fatty acids and triglycerides levels were measured before meal intake and during the frour postprandial hours. Furthermore, energy expenditure (EE), protein, carbohydrate and lipid oxidation were measured in fasted and fed conditions.

RESULTS

Fasting leptin was found to be positively correlated with circulating insulin concentrations (r = .748; p = 0.011) and body fat in kg (r = .827; p = 0.001). During the measured postprandial period no statistically significant changes were found in leptin levels as compared with pre-meal values in either lean or overweight men, nor differences in leptin changes between both groups. After load intake, carbohydrate oxidation was lower in overweight individuals (p < 0.05). while no significant differences were observed in protein oxidation. Cumulative lipid oxidation was found to be negatively associated with post-meal leptin values, being significantly lower in the overweight as compared with lean men (p < 0.05). This study demonstrates that the acute postprandial fuel substrate utilization is altered in overweight men with a lower carbohydrate oxidation and a strong inhibition of lipid oxidation, which could be attributed to some leptin resistance.

CONCLUSION

These data also suggest that short-term meal-related metabolic responses may explain the long-term body adiposity if they are sustained over long intervals.

Absence of platelet response after eradication of Helicobacter pylori infection in patients with chronic idiopathic thrombocytopenic purpura

Eradication of Helicobacter pylori infection has been associated with the correction of thrombocytopenia in patients with idiopathic thrombocytopenic purpura (ITP). We have analysed the response to eradication of H. pylori in a series of 56 adult patients with chronic ITP. Forty patients had H. pylori infection (71%) that was eradicated in 23 of 32 evaluable patients (72%). Platelet counts did not significantly vary according to H. pylori treatment outcome. Three of 56 patients (5%) achieved a partial response attributable to H. pylori eradication. Therefore, detection of H. pylori infection should not be routinely included in the initial work-up of ITP.

Variability of genetic alterations in different sites of head and neck cancer

OBJECTIVE

Tumors arising from different sites of the head and neck area have different clinical behavior. However, most of the studies on genetic alterations in head and neck squamous cell carcinomas do not make a distinction between the sites within this area. The objective of this study is to compare the genetic alterations in three different sites of the head and neck (larynx, oropharynx, and hypopharynx).

STUDY DESIGN

Prospective study.

METHODS

Thirty-eight laryngeal, 29 oropharyngeal, and 37 hypopharyngeal carcinomas were studied. DNA from tumor and healthy tissue was evaluated for amplification of the oncogenes at 11q13 region (CCND1, FGF3, FGF4 and EMS1) and of the oncogenes MYC and ERBB1; for integration of the human papillomavirus (HPV) types 6b and 16; for loss of heterozygosity (LOH) at p53 and NAT2; and for the cellular DNA content.

RESULTS

FGF3 and FGF4 showed a significantly higher frequency of amplification in hypopharyngeal tumors (P =.006 and P =.0002, respectively). CCND1 amplification had a nearly statistically significant (P =.072) higher frequency of amplification in hypopharyngeal tumors. Aneuploid tumors were found in a significantly lower proportion in the larynx (P =.03) compared with the other sites. For the other genetic alterations, no significant differences among the three sites were found.

CONCLUSIONS

These results suggest that cancers originating from different sites in the head and neck may have different tumor biology. Therefore, they should be considered as different entities.

Prevalence of physical activity during leisure time in the European Union

PURPOSE

To estimate the prevalence of physical activity during leisure time in adults from the 15 member states of the European Union and the relationship with sociodemographic variables.

METHODS

A representative sample, with approximately 1000 adults, aged 15 and upward, was selected from each member state to complete a questionnaire on attitudes to physical activity, body weight, and health by a face-to-face interview, summing a total of 15,239 subjects. The amount of leisure-time physical activity was quantified by assigning metabolic equivalents (METs) to each activity. Multiple linear regression models with MET-h.wk(-1) as the dependent variable were fitted.

RESULTS

Northern European countries showed higher levels of physical activity than southern ones. The highest prevalence (91.9%) was found in Finland, and the lowest (40.7%) in Portugal. A higher percentage of men practiced any leisure-time physical activity and also showed higher mean of MET-h.wk(-1). In both genders, the multivariate models showed a significant trend to higher leisure time activity in participants with higher educational levels and in nonsmokers. Also, an inverse association between body mass index and leisure-time physical activity was found.

CONCLUSION

The prevalence of any physical activity during leisure time in the adult European population was similar to the U.S. estimates. Nevertheless, the amount of activity is low, and a wide disparity between countries exists. To our knowledge, this is the first study determining the prevalence and amount of leisure-time physical activity, which is the first step to define strategies to persuade populations to increase their physical activity.

Effects of the whole seed and a protein isolate of faba bean (Vicia faba) on the cholesterol metabolism of hypercholesterolaemic rats

The aim of the present work was to analyse the hypocholesterolaemic efficiency of a Vicia faba-protein isolate in relation to the intact legume. In addition, the mechanisms underlying the effects of this isolate were investigated. Hypercholesterolaemic rats were divided into three groups and fed high-fat diets rich in cholesterol-containing casein, whole seeds of Vicia faba or the protein isolate of faba beans as protein source, for 2 weeks ad libitum. The protein isolate was prepared by isoelectric precipitation and spray dried. Analyses of serum, liver and faeces, as well as of the activity of hepatic 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase, were assessed by enzymatic methods. The rats fed on Vicia faba diets showed significantly lower body weights and energy intakes than rats fed on casein diets. The whole-seed diet induced a significant reduction in plasma triacylglycerol. Feeding rats on diets containing faba bean seeds, or the protein isolate, induced a significant decrease in plasma (LDL+VLDL)-cholesterol but not in HDL-cholesterol. Hepatic cholesterol and triacylglycerol were also reduced. The hypocholesterolaemic effects of Vicia faba were not the result of a reduction in cholesterol synthesis as assessed from HMG-CoA reductase activity, but the result of an increase in steroid faecal excretion. The faba bean-protein isolate obtained under our experimental conditions was useful in improving the metabolic alterations induced by feeding with a hypercholesterolaemic diet compared with casein. The effectiveness of the whole seeds was higher than that of the protein isolate.

Rapid in vivo PGC-1 mRNA upregulation in brown adipose tissue of Wistar rats by a beta(3)-adrenergic agonist and lack of effect of leptin

Peroxisome proliferator-activated receptor-gamma coactivator-1 (PGC-1) is highly expressed in brown adipose tissue (BAT) and plays an important role in adaptive thermogenesis. The aim of this study was to assess the acute effect of a beta(3)-adrenergic agonist (Trecadrine) and leptin on the expression of PGC-1 and PPARgamma2 mRNA in BAT. Trecadrine produced a marked increase (4.5-fold) in PGC-1 mRNA compared to controls (P<0.001) without changes in PPARgamma2 mRNA, whereas leptin administration did not alter either PGC-1 or PPARgamma2 expression. These results show that selective stimulation of the beta(3)-adrenoceptor rapidly upregulates the expression of PGC-1 in brown adipocytes without a concomitant increase in PPARgamma2. Moreover, our results show that PGC-1 and PPARgamma2 expression in BAT seems not to be acutely regulated by leptin.

Obesity and immune function relationships

The immunological processes involved in the collaborative defence of organisms are affected by nutritional status. Thus, a positive chronic imbalance between energy intake and expenditure leads to situations of obesity, which may influence unspecific and specific immune responses mediated by humoral and cell mediated mechanisms. Furthermore, several lines of evidence have supported a link between adipose tissue and immunocompetent cells. This interaction is illustrated in obesity, where excess adiposity and impaired immune function have been described in both humans and genetically obese rodents. However, limited and often controversial information exist comparing immunity in obese and non-obese subjects as well as about the cellular and molecular mechanisms implicated. In general terms, clinical and epidemiological data support the evidence that the incidence and severity of specific types of infectious illnesses are higher in obese persons as compared to lean individuals together with the occurrence of poor antibody responses to antigens in overweight subjects. Leptin might play a key role in linking nutritional status with T-cell function. The complexities and heterogeneity of the host defences concerning the immune response in different nutritional circumstances affecting the energy balance require an integral study of the immunocompetent cells, their subsets and products as well as specific and unspecific inducer/regulator systems. In this context, more research is needed to clarify the clinical implications of the alterations induced by obesity on the immune function.

Time-dependent effects of a high-energy-yielding diet on the regulation of specific white adipose tissue genes

White adipose tissue development is regulated by many factors, including the energy content of food and the genetic background. Nevertheless, little is known about possible differential effects of high-fat palatable diets when fed for short or long-time periods. Thus, the expression of certain genes involved with lipid metabolism (peroxisome proliferator-activated receptor gamma, PPARgamma2; retinoic receptors; fatty acid binding protein, aP2 and uncoupling proteins, UCP) may be affected by those dietary manipulations (high-energy-yielding diet and time duration of feeding). High-fat feeding for 8 days decreased mRNA UCP3 levels compared to control fed animals, while feeding for 30 days increased them over controls. Similar findings occurred for PPARgamma2 and aP2. Furthermore, statistically significant associations were found among PPARgamma2, aP2 and UCP3 mRNA levels. These data suggest a physiological time-dependent response seeking to prevent excessive fat deposition when animals are fed for short-term with a high amount of dietary fat, which was followed by an adaptive period to the high-energy content of diet throughout a coregulation among certain lipid metabolism related genes: PPARgamma2, aP2, UCP3.