The effect of caffeine on cutaneous postocclusive reactive hyperaemia.

BACKGROUND: Caffeine is reported to be the most widely used pharmacologically active substance. It causes mental stimulation and increases blood pressure. Acute systolic and diastolic blood pressure response to caffeine attenuates in the course of regular caffeine use; tolerance to cardiovascular responses develops in some people. For some hypertension-prone people coffee ingestion may be harmful, and for others it may be beneficial. The aim of our work was to evaluate the effect of caffeine on postocclusive reactive hyperaemia (PORH), a test of microvascular function, and at the same time to monitor the central effects of caffeine on blood pressure and heart rate. METHODS: Heart rate, arterial pressure, and cutaneous laser-Doppler (LD) flux were monitored in 32 healthy volunteers (aged 25.2 ± 4.3 years) before and after they ingested 200 mg of caffeine. LD flux was measured on a finger at rest and after the release of an 8-minute occlusion of digital arteries above the place of LD flux measurement. All parameters obtained after the ingestion of caffeine were compared to the values obtained before caffeine and to the values obtained after a placebo. RESULTS: We found slightly increased arterial pressure as well as decreased heart rate and resting LD flux (Dunnett's test, p<0.05) after the ingestion of caffeine. Caffeine significantly reduced the PORH response (Dunnett's test, p<0.01). The power of the low-frequency oscillations (0.06-0.15 Hz) of LD flux, representing vascular myogenic activity, increased significantly after the ingestion of caffeine at rest and during the PORH response. A correlation was found between the number of cups of coffee regularly consumed and resting LD flux values (R = 0.492, p = 0.00422), peak LD flux values during PORH (R = 0.458, p = 0.00847), and the PORH area (R = 0.506, p = 0.00313) after caffeine consumption. CONCLUSIONS: From the results, we can conclude that caffeine affects cutaneous microvascular function during rest and during a PORH response, and that it increases blood pressure and decreases heart rate.

Serum anti-Müllerian hormone as a predictive marker of polycystic ovarian syndrome.

BACKGROUND: The anti-Müllerian hormone (AMH) is a dimeric protein secreted by the female ovaries and has two fundamental roles in follicle genesis. It delays the entrance of the primordial follicle into the pool of follicles in growth and diminishes the sensitivity of the ovarian follicle towards follicle-stimulating hormone (FSH). The purpose of this work was to study the AMH (nv 2.0-6.8 ng/mL) as a marker during assisted reproductive technology (ART), in order to identify cases of infertility due to polycystic ovarian syndrome (PCOS). This syndrome affects 10% of women with infertility problems, and a new biological marker could be useful to general practitioners of internal medicine to help generate the suspicion of PCOS so that they can refer the patient to the gynecologist for confirmation. METHODS: This study enrolled 236 patients aged 26-46 years undergoing assisted reproductive technology at the Institute for Maternal and Child Health, Trieste, Italy. On the third day of the ovarian cycle, the patients were given doses of AMH, FSH, and luteinizing hormone (LH, in cases of AMH < 2.0-6.8 ng/mL). A control pelvic ultrasound was also carried out. RESULTS: We identified 57 patients who were starting in vitro fertilization or embryo transfer with AMH values within the normal range (3.64 ± 1.51 ng/mL), 77 with values below normal (1.38 ± 0.32 ng/mL), and 96 cases with undetectable values of AMH. Six patients had very high AMH levels (10.0 ± 2.28 ng/mL) and, of these, five were found to have PCOS on pelvic ultrasound examination (P < 0.05). We also found inverse correlations between AMH levels and age (r = -0.52) and between AMH and FSH levels (r = -0.32). CONCLUSION: In clinical practice it is common to encounter patients who turn to medicine in search of a cure for female infertility. In our experience, AMH two or three times the normal amount (10 ± 2.28 ng/mL), is a good indication of PCOS and infertility.

Fractal behaviour of heart rate variability reflects severity in stroke patients.

Non-linear parameters obtained from heart rate variability (HRV) analysis has recently been recognized to provide valuable information for physiological interpretation of heart rate fluctuation. Among the numerous non-linear parameters related to the fractal behaviour of the HRV signal, two classes have gained wide interest in the last years: the beta exponent based on the 1/f-like relationship, starting from the spectral power, and that based on fractal dimension. In order to evaluate the relationship between lesion's severity and fractal behaviour, 20 first-ever stroke subjects and 10 healthy subjects were studied. Patients were divided in two groups according to single or multiple medium cerebral artery lesions. All subjects underwent 24-hour Holter recording analysed by fractal and 1/f-like techniques. Differently from methods usually used in literature to evaluate the fractal dimension (FD), in this work the FD was extracted by using the Higuchi's algorithm that permits to calculate the parameter directly from the HRV sequences in the time domain. Results show that fractal analysis contains relevant information related to different HRV dynamics that permits to separate normal subjects from stroke patients. FD is also able to distinguish between normal and stroke subjects with different lesion's severity.

Correlation between the immunological condition and the results of immunoenzymatic tests in diagnosing infectious mononucleosis.

BACKGROUND AND AIM OF THE WORK: A symptom-based diagnosis of infectious mononucleosis is not sufficiently accurate, since some clinical symptoms of infectious mononucleosis are also detected in other virally induced diseases. Moreover, not all patients suffering from infectious mononucleosis show circulating atypical lymphocytes, which are considered characteristic of this disease. Therefore, when this disorder is suspected, serum analyses are carried out to detect the presence of certain immunoglobulins associated with infectious mononucleosis in the patient's blood. The aim of this study was to evaluate the sensitivity and the specificity of a rapid test detecting heterophil antibodies in diagnosing infectious mononucleosis in a paediatric population. METHODS: We considered 163 paediatric patients with suspected infectious mononucleosis and we tested their serums to detect heterophil antibodies (using an inexpensive and rapid test) and specific immunoglobulins directed against Epstein-Barr virus (EBV) (these assays are known to be characterized by high sensitivity and specificity, but are more expensive and time-consuming). RESULTS: By comparing the results of the rapid test with those of the other assays, we found that the sensitivity of the first test was 61.8%, whereas its specificity was sufficiently high (about 90%). CONCLUSIONS: We show that, in paediatric patients, the detection of heterophil antibodies is not a very sensitive test, therefore the determination of immunoglobulins against specific antigens of EBV is recommended.

Effect of hypobaric hypoxia on heart rate variability during exercise: a pilot field study.

The influence of hypoxia on heart rate variability (HRV) has been studied under resting conditions with mixed results. Differences have been found in physiological responses to normobaric versus hypobaric hypoxia. Our aim was to study the influence of hypobaric hypoxia on HRV during physical exercise to determine whether HRV changes due to the exercise-induced heart rate (HR) increase or whether hypoxia itself exerts an influence. We tested nine healthy non-acclimatised white males (age = 43 +/- 7 years) at 400 and 4,200 m during exercises. At 400 m HRV was measured at 50% and 75% maximal oxygen uptake (VO(2) max). At 4,200 m HR was kept equal as during exercise at 400 m by adjusting the intensity of step testing. The Poincaré plot as a non-linear method of HRV analysis was used, where the shape of the ellipse depending on HRV is expressed by two parameters, SD1 and SD2 (correlating to parasympathetic activity and both sympathetic and parasympathetic activity, respectively). We established a decrease in SD2 and an insignificant decrease in SD1 at medium HR at 4,200 m compared to 400 m. Both parameters showed similar tendencies during high-intensity exercise. Our results indicate that hypobaric hypoxia itself exerts an influence on HRV at a moderate HR.

Antiphospholipid antibodies and lipoprotein(a) in obese children.

AIM: Antiphospholipid (aPL) antibodies, Lipoprotein(a) [Lp(a)] and obesity are considered three independent risk factors for development of cardiovascular diseases. We investigate the presence of aPL antibodies and the Lp(a) concentration in 190 obese and 30 healthy children divided into prepubertal and pubertal, compared with healthy adults. RESULTS: aPL antibodies were detected in 2.65% of prepubertal and in 2.59% of pubertal obese children. Considering results obtained by Lp(a) test, 4.4% of prepubertal and 5.2% of pubertal obese children and 17.5% of healthy adults were at risk for development of cardiovascular diseases. CONCLUSION: The presence of various prothrombotic risk factors increases the probability of developing thrombosis. Considering aPL antibodies there is no statistically significant difference among the different considered groups; therefore each category has the same risk factor. The Lp(a) distribution in adults is significantly different from the Lp(a) distribution in prepubertal (p = 0.012) and pubertal (p = 0.029) obese children. There is no significant difference among prepubertal subjects (p = 0.632) as well as pubertal subjects (p = 0.465), independently from the BMI. These results suggest the control of BMI in young population to avoid the presence of the obesity as another independent prothrombotic risk factor to be added to aPL and Lp(a) in the future adulthood.

The effect of sucrose ingestion on autonomic nervous system function in young subjects during acute moderate hypoxia.

Cardiac arrhythmias are associated with an increase in sympathetic activity (reflected in increased heart rate) and a simultaneous decrease in rhythmical fluctuations of sympathetic activity [reflected in decreased heart rate variability (HRV)]. As hypoxia is a well known trigger for cardiac arrhythmias, and carbohydrate loading a known sympatho-excitatory stimulus, the present study investigated if carbohydrate loading affects the cardiac response to acute hypoxic challenge. Fourteen subjects ingested a sucrose solution or an equal volume of water and spectral analysis of HRV was used to determine HRV components in normoxia and acute, normobaric hypoxia. Compared to the control condition, ingestion of carbohydrates increased heart rate, spectral power of nLF (P < 0.02) and LF/HF ratio (P < 0.003), and decreased spectral power of nHF (P < 0.03) during hypoxia. Carbohydrate ingestion thus intensified cardiac autonomic modulation during acute hypoxia and may therefore act as a beneficial protective mechanism against the disturbances of cardiac rhythm in hypoxic conditions.

Carbohydrate ingestion improves oxygen delivery in acute hypoxia.

It is generally accepted that an increase in blood CO(2) increases ventilation. We also know that during carbohydrate metabolism a larger amount of CO(2) is produced than during metabolism of lipids or proteins. The aim of the present study was therefore to assess whether carbohydrate ingestion can increase CO(2) production enough to stimulate ventilation, which could in turn increase arterial oxygenation and alleviate the symptoms of hypoxia in a hypoxic environment. Fourteen subjects participated in two trials, which consisted of two normoxic and an acute hypoxic period (F(i(O(2))) = 12.86%). Following the first control normoxic period, the subjects ingested either a 10% water solution of sucrose (CHO; 4 kcal/kg body mass) or an equal volume of water (control). Hemoglobin saturation, heart rate, and ventilation parameters were monitored throughout the experiment. In contrast to the control trial, CO(2) production (V(CO(2)); L), ventilation (V; L/min), and heart rate were all significantly (p < 0.001) increased in the CHO trial during the second normoxic exposure; these parameters were also significantly elevated during the hypoxic exposure, as compared to the control trial. Carbohydrate ingestion 40 min prior to acute hypoxic exposure significantly (p < 0.001) improved hemoglobin saturation by 4%. The results suggest that ingestion of carbohydrates can improve arterial oxygenation during acute hypoxic exposure.

Linear and nonlinear assessment of heart rate variability in nonacclimatized middleaged subjects at different hypoxic levels.

Studies of autonomic cardiac nervous system activity during acute exposure to hypobaric hypoxia have suggested a depression of autonomic functions and a shift in the sympatho-vagal balance towards relatively more sympathetic and less parasympathetic activity at higher hypoxic levels . This study was performed on nine non-acclimatized middle-aged healthy men (age 43.7 +/- 7.3 years), to evaluate the linear (autoregressive spectra) and non-linear (Poincaré plot, b coefficient, fractal dimension) heart rate variability (HRV) parameters at rest in supine position at three different altitudes: 400 m, 3200 m and 4200 m. A statistically significant increase of heart rate (HR) was detected at both higher altitudes in comparison with the reference level as well as comparing the values observed at 3200 m and 4200 m, respectively. Acute exposure to both hypoxic levels (3200 m and 4200 m) induced a shift of sympatho-vagal balance towards more sympathetic and less parasympathetic activity in comparison to the basal condition at 400 m asl, as indicated by autoregressive LF and HF spectral components and in particular by LF/HF ratio. The non-linear ss coefficient values demonstrated a statistically significant decrease of the complexity of the system at both hypoxic conditions as effect of hypobaric hypoxia on ANS activity of myocardium. However this fact was not confirmed by the fractal dimension parameter.

A problem solving in driving tests which method for carbohydratedeficient transferrin (cdt) in adolescents affected by celiac disease?

This study aimed at evaluating the relationships among pathologies and methods employed to detect transglutaminase (tTG) and carbohydrate-deficient transferrin (CDT) in 33 celiac subjects presenting either high or low levels of tTG. Elevated tTG values were associated with increased CDT levels. A significant correlation was found between CDT and tTG values (r=0.57; p>0.0001). In the absence of wider studies and assessments on the interferences between methods used for these dosages and in presence of pathologies as carbohydrate-deficient glycoprotein syndrome (CDGs), this account assumes a possible correlation with celiac disease and suggests that the CDT test should not be used in celiac patients to authorize the return of the driving license after its withdrawal due to alcohol abuse [1, 2, 3].

Linear and non-linear assessment of heart rate variability in congenital central hypoventilation syndrome.

Congenital central hypoventilation syndrome (CCHS) is characterised by the failure of the autonomic control of breathing and is defined as a multi-system disorder with symptoms of diffuse autonomic nervous system dysfunction. The present study, considering the heart rate variability (HRV) parameters as expression of cardiac autonomic nervous system activity, reports higher heart rate (HR) levels and reduced HRV, at rest in supine position, in CCHS patient in comparison with controls. The CCHS subject presented lower values of HF spectral component and SD1 Poincaré plot parameter, indicating a decrease of vagal cardiac influence. Also the LF component and SD2 parameter were reduced, while the LF/HF ratio presented a higher value as expression of sympatho-vagal dysregulation with dominant sympathetic activity and prevalent vagal withdrawal. The fractal dimension and beta values suggest lower cardiac complexity and a probable lack of integrity of autonomic control mechanisms in CCHS subject in comparison to controls.

Parametric evaluation of heart rate variability during the menstrual cycle in young women.

Evaluation of heart rate variability (HRV) is based on analysis of consecutive R-R intervals and may provide quantitative information on the modulation of cardiac vagal and sympathetic efferent activities. In particular, power spectral analysis as well as the fractal dimension of HRV represent non-invasive measures that reflect brain-heart interaction in different physiopathological conditions. This study was performed to investigate the relationship between autonomic nervous cardiac influence and three phases (menses, follicular phase and luteal phase) of the menstrual cycle. Heart rate (HR) was recorded in 6 eumenorrheic young females, continuously for 20 min, at rest. From the tachograms, fractal dimension, FFT spectra and beta coefficient were evaluated. The components of two spectral bands were calculated: 0.040 Hz - 0.150 Hz (low frequency, LF), and 0.150 Hz - 0.80 Hz (high frequency, HF). The results indicate no correlation between HR and follicular as well as luteal phase of the menstrual cycle. Total power and HF spectral component increase, whereas LF spectral component decreases in the luteal phase compared to the follicular one. The fractal dimension does not show significant differences among the three phases. Beta coefficient decreases during luteal phase in respect of follicular one and menses. In conclusion, these results indicate in healthy young women a correlation between female sex hormones (17 beta-oestradiol, progesterone and pituitary gonadotrophins) concentrations and some HRV parameters with higher HR variability during the luteal phase.

Linear and non-linear parameters of heart rate variability during static and dynamic exercise in a high-performance dinghy sailor.

The analysis of heart rate variability (HRV) is recognized as a powerful non-invasive tool to evaluate the influence of autonomic nervous system on the heart and the heart-brain interaction. It is well-known that relatively high HRV is correlated to health condition while low HRV corresponds to cardiovascular disease or could be caused by mental stress, depression or exercise. In order to investigate heart-brain interaction we compare linear and non linear parameters calculated from HRV signals recorded in the same subject at similar heart rate (HR) values, during two different conditions, i.e. static exercise during sailing and dynamic exercise on cycloergometer. In the study, performed in one high-performance would class dinghy sailor, the HR was recorded at rest and during the two types of exercise. For the analysis, tachogram tracts with similar HR values were considered. The power spectral densities in very-low, low (LF) and high (HF) frequency bands were evaluated as well as the LF/HF ratio, the two standard deviations (SD1 and SD2) of the Poincaré plot, the beta values and the fractal dimension (FD). The results indicate a decrease of HRV, LF, HF, SD1 and SD2 parameters, as well as an increase of beta and FD during both types of exercise compared to rest. However, the higher values of LF, LF/HF ratio and SD2 as well as the lower value of FD in upwind sailing in comparison to dynamic exercise on cycloergometer, at similar HR, suggest a different sympatho-vagal modulation on cardiac function and therefore a different heart-brain interaction in these isometric and isotonic exercises.