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Bursopentin (BP(5), H-Cys(1)-Lys(2)-Arg(3)-Val(4)-Tyr(5)-OH), found in the bursa Fabricius of the chicken, is a pentapeptide that protects the organism from oxidative stress by reducing the intracellular generation of reactive oxygen species. Hydrogen abstraction, a common oxidative reaction occurring in proteins, often results in the formation of d amino acid residues. To study the effect of this phenomenon on the structure of bursopentin, each of its residues were converted from the l configuration to the d configuration, and the structures of these peptide epimers were compared to that of the wild-type bursopentin. The conformations, secondary structures, compactness and hydrogen bonding of bursopentin were compared to its epimers using molecular dynamics simulations and first principles quantum chemical computations. It was discovered that the repulsion between the side chains of Lys(2) and Arg(3) influenced the conformation of the peptide regardless of the configuration of these residues. Epimerisation of the Val(4) and Tyr(5) caused a reduction in the compactness of bursopentin. In all cases, the occurrence of a turn structure was relatively high, especially when Arg(3) was in the d configuration. Thermodynamic analysis of the epimerisation process showed that the formation of d amino acid residues is favourable.
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Living systems employ cilia to control and to sense the flow of fluids for many purposes, such as pumping, locomotion, feeding, and tissue morphogenesis. Beyond their use in biology, functional arrays of artificial cilia have been envisaged as a potential biomimetic strategy for inducing fluid flow and mixing in lab-on-a-chip devices. Here we report on fluid transport produced by magnetically actuated arrays of biomimetic cilia whose size approaches that of their biological counterparts, a scale at which advection and diffusion compete to determine mass transport. Our biomimetic cilia recreate the beat shape of embryonic nodal cilia, simultaneously generating two sharply segregated regimes of fluid flow: Above the cilia tips their motion causes directed, long-range fluid transport, whereas below the tips we show that the cilia beat generates an enhanced diffusivity capable of producing increased mixing rates. These two distinct types of flow occur simultaneously and are separated in space by less than 5 microm, approximately 20% of the biomimetic cilium length. While this suggests that our system may have applications as a versatile microfluidics device, we also focus on the biological implications of our findings. Our statistical analysis of particle transport identifying an enhanced diffusion regime provides novel evidence for the existence of mixing in ciliated systems, and we demonstrate that the directed transport regime is Poiseuille-Couette flow, the first analytical model consistent with biological measurements of fluid flow in the embryonic node.
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Cilios/fisiología , Imitación Molecular , Microscopía Electrónica de RastreoRESUMEN
Interfacial magnetism and metal-insulator transition at LaNiO[Formula: see text]-based oxide interfaces have triggered intense research efforts, because of the possible implications in future heterostructure device design and engineering. Experimental observation lack in some points a support from an atomistic view. In an effort to fill such gap, we hereby investigate the structural, electronic, and magnetic properties of (LaNiO[Formula: see text])[Formula: see text]/(CaMnO[Formula: see text])[Formula: see text] superlattices with varying LaNiO[Formula: see text] thickness (n) using density functional theory including a Hubbard-type effective on-site Coulomb term. We successfully capture and explain the metal-insulator transition and interfacial magnetic properties, such as magnetic alignments and induced Ni magnetic moments which were recently observed experimentally in nickelate-based heterostructures. In the superlattices modeled in our study, an insulating state is found for n=1 and a metallic character for n=2, 4, with major contribution from Ni and Mn 3d states. The insulating character originates from the disorder effect induced by sudden environment change for the octahedra at the interface, and associated to localized electronic states; on the other hand, for larger n, less localized interfacial states and increased polarity of the LaNiO[Formula: see text] layers contribute to metallicity. We discuss how the interplay between double and super-exchange interaction via complex structural and charge redistributions results in interfacial magnetism. While (LaNiO[Formula: see text])[Formula: see text]/(CaMnO[Formula: see text])[Formula: see text] superlattices are chosen as prototype and for their experimental feasibility, our approach is generally applicable to understand the intricate roles of interfacial states and exchange mechanism between magnetic ions towards the overall response of a magnetic interface or superlattice.
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Increased blood pressure variability (BPV) and decreased inter-beat interval (heart rate, respectively) variability (IBIV, HRV respectively) are associated with cardiovascular disorders. The aim of this study was to evaluate the reproducibility of BPV and IBIV (HRV) in young healthy individuals. Blood pressure and inter-beat intervals (instantaneous values of heart rate, respectively) were recorded beat-to-beat at rest (5 min, Finapres, breathing at 0.33 Hz) in 152 subjects (19-24 years) 3 times in periods of one week. Systolic (SBPV(0.1r)/SBPV(0.1a)) and diastolic (DBPV(0.1r)/DBPV(0.1a)) blood pressure variability in relative (r.u.) and absolute (mmHg(2)/Hz) units and inter-beat interval (IBIV(0.1r)/IBIV(0.1a)), or heart rate (HRV(0.1r)/HRV(0.1a)) variability in relative (r.u.) and absolute (ms(2)/Hz, resp. mHz(2)) units were determined by the spectral method as spectral power at the frequency of 0.1 Hz and 0.33 Hz (SBPV(0.33r)/SBPV(0.33a), DBPV(0.33r)/DBPV(0.33a), IBIV(0.33r)/IBIV(0.33a), HRV(0.33r)/HRV(0.33a)). All indices of BPV and IBIV (resp. HRV) revealed a lower intraindividual than interindividual variability (ANOVA; p<0.001). The mean values of all indices in each subject significantly correlated with distribution of individual values in the same subject (Pearson's correlation coefficient; p<0.001). Blood pressure and inter-beat interval (heart rate) variability is an individual characteristic feature.
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Determinación de la Presión Sanguínea , Presión Sanguínea , Frecuencia Cardíaca , Determinación de la Presión Sanguínea/métodos , Femenino , Análisis de Fourier , Humanos , Masculino , Valor Predictivo de las Pruebas , Valores de Referencia , Reproducibilidad de los Resultados , Procesamiento de Señales Asistido por Computador , Factores de Tiempo , Adulto JovenRESUMEN
The aim of this study was a comparison of risk stratification for death in patients after myocardial infarction (MI) and of risk stratification for malignant arrhythmias in patients with implantable cardioverter-defibrillator (ICD). The individual risk factors and more complex approaches were used, which take into account that a borderline between a risky and non-risky value of each predictor is not clear-cut (fuzzification of a critical value) and that individual risk factors have different weight (area under receiver operating curve - AUC or Sommers' D - Dxy). The risk factors were baroreflex sensitivity, ejection fraction and the number of ventricular premature complexes/hour on Holter monitoring. Those factors were evaluated separately and they were involved into logit model and fuzzy models (Fuzzy, Fuzzy-AUC, and Fuzzy-Dxy). Two groups of patients were examined: a) 308 patients 7-21 days after MI (23 patients died within period of 24 month); b) 53 patients with left ventricular dysfunction examined before implantation of ICD (7 patients with malignant arrhythmia and electric discharge within 11 month after implantation). Our results obtained in MI patients demonstrated that the application of logit and fuzzy models was superior over the risk stratification based on algorithm where the decision making is dependent on one parameter. In patients with implanted defibrillator only logit method yielded statistically significant result, but its reliability was doubtful because all other tests were statistically insignificant. We recommend evaluating the data not only by tests based on logit model but also by tests based on fuzzy models.
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Arritmias Cardíacas/prevención & control , Cardioversión Eléctrica/instrumentación , Lógica Difusa , Modelos Logísticos , Infarto del Miocardio/mortalidad , Anciano , Algoritmos , Arritmias Cardíacas/fisiopatología , Barorreflejo , Desfibriladores Implantables , Electrocardiografía Ambulatoria , Indicadores de Salud , Humanos , Persona de Mediana Edad , Infarto del Miocardio/fisiopatología , Pronóstico , Curva ROC , Reproducibilidad de los Resultados , Medición de Riesgo , Factores de Riesgo , Volumen Sistólico , Factores de Tiempo , Complejos Prematuros Ventriculares/fisiopatologíaRESUMEN
The aim of this study was to evaluate the association of A1166C polymorphism in angiotensin II type 1 receptor (AT(1)R) gene with baroreflex sensitivity (BRS in ms/mm Hg; BRSf in mHz/mm Hg) in man. BRS and BRSf were determined by a spectral method in 135 subjects (19-26 years) at a frequency of 0.1 Hz. Genotypes were detected by means of polymerase chain reaction and restriction analysis using enzyme DdeI. We compared BRS and BRSf among genotypes of this polymorphism. The frequency of genotypes of AT(1)R A1166C polymorphism was: 45.9 % (AA, n=62), 45.9 % (AC, n=62), 8.2 % (CC, n=11). Differences in BRS (p<0.05) and BRSf (p<0.01) among genotypes of this single nucleotide polymorphism were found (Kruskal-Wallis: BRS - AA: 7.9+/-3.3, AC: 8.6+/-3.6, CC: 5.9+/-2.3 ms/mm Hg; BRSf - AA: 12.0+/-4.0, AC: 12.0+/-5.0, CC: 8.0+/-3.0 mHz/mm Hg). Compared to carriers of other genotypes (AA+AC) the homozygotes with the less frequent allele (CC) showed significantly lower BRSf (Mann-Whitney: BRSf - AA+AC: 12.0+/-4.0, CC: 8.0+/-3.0 mHz/mm Hg; p<0.01) and borderline lower BRS (BRS - AA+AC: 8.2+/-3.5, CC: 5.9+/-2.5 ms/mm Hg; p=0.07). We found a significant association of A1166C polymorphism in AT(1) receptor gene with baroreflex sensitivity. Homozygosity for the less frequent allele was associated with decreased baroreflex sensitivity.
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Barorreflejo/genética , Presión Sanguínea/genética , Frecuencia Cardíaca/genética , Polimorfismo de Nucleótido Simple , Receptor de Angiotensina Tipo 1/genética , Adulto , Determinación de la Presión Sanguínea , República Checa , Femenino , Frecuencia de los Genes , Genotipo , Homocigoto , Humanos , Masculino , Oportunidad Relativa , Fenotipo , Medición de Riesgo , Factores de Riesgo , Procesamiento de Señales Asistido por Computador , Adulto JovenRESUMEN
Non-invasive methods of determination of baroreflex sensitivity (BRS, ms/mmHg) are based on beat-to-beat systolic blood pressure and inter-beat interval recording. Sequential methods and spectral methods at spontaneous breathing include transient superposition of breathing and 0.1 Hz rhythms. Previously, a cross-spectral method of analysis was used, at constant breathing rate using a metronome set at 0.33 Hz, enabling separate determination of BRS at 0.1 Hz (BRS(0.1Hz)) and respiratory rhythms (BRS(0.33Hz)). The aim of the present study was to evaluate the role of breathing in the spectral method of BRS determination with respect to age and hypertension. Such information would be important in evaluation of BRS at pathological conditions associated with extremely low BRS levels. Blood pressure was recorded by Finapres (5 minutes, controlled breathing at 0.33 Hz) in 118 healthy young subjects (YS: mean age 21.0+/-1.3 years), 26 hypertensive patients (HT: mean age 48.6+/-10.3 years) with 26 age-matched controls (CHT: mean age 46.3+/-8.6 years). A comparison of BRS(0.1Hz) and BRS(0.33Hz) was made. Statistically significant correlations were found between BRS(0.1Hz) and BRS(0.33Hz) in all groups: YS: r=0.52, p<0.01, HT: r=0.47, p<0.05, and CHT: r=0.70, p<0.01. The regression equations indicated the existence of a breathing-dependent component unrelated to BRS (YS: BRS(0.33Hz)=2.63+1.14*BRS(0.1Hz); HT: BRS(0.33Hz)=3.19+0.91*BRS(0.1Hz); and CHT: BRS(0.33Hz)=1.88+ +1.01*BRS(0.1Hz); differences between the slopes and the slope of identity line were insignificant). The ratios of BRS(0.1Hz) to BRS(0.33Hz) were significantly lower than 1 (p<0.01) in all groups (YS: 0.876+/-0.419, HT: 0.628+/-0.278, and CHT: 0.782+/-0.260). Thus, BRS evaluated at the breathing rate overestimates the real baroreflex sensitivity. This is more pronounced at low values of BRS, which is more important in patients with pathologic low BRS. For diagnostic purposes we recommend the evaluation of BRS at the frequency of 0.1 Hz using metronome-controlled breathing at a frequency that is substantially higher than 0.1 Hz and is not a multiple of 0.1 Hz to eliminate respiratory baroreflex-non-related influence and resonance effect on heart rate fluctuations.
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Barorreflejo , Determinación de la Presión Sanguínea/métodos , Presión Sanguínea , Frecuencia Cardíaca , Hipertensión/fisiopatología , Modelos Cardiovasculares , Mecánica Respiratoria , Adulto , Factores de Edad , Humanos , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Factores de Tiempo , Adulto JovenRESUMEN
In our previous studies, a decreased blood pressure was reported in children treated by anthracycline (AC). The aim of this study was to assess the long-term effects of AC anticancer therapy in 45 subjects aged 13-22 years by repeated 24-hour Holter monitoring of blood pressure. Sixty four aged-matched subjects served as controls. The differences between mean values of systolic (SBP) and diastolic blood pressure (DBP) in each hour of both groups were evaluated by Mann-Whitney test. Also the parameters of the least-squares fit of the sinusoidal curve in each subject were estimated (M - mesor, midline-estimating, a mean value of sinusoidal curve corresponds to 24-hours mean pressure; A - amplitude, double amplitude corresponds to night-day difference; Acr - acrophase is a time of maximal value of a sinusoidal curve). SBP and DBP was significantly lower only during night hours in anthracycline patients 19-22 years old. Also M was lower in this age subgroup of patients comparing to age matched controls (SBP: 112+/-6 mm Hg versus 117+/-7 mm Hg, p<0.05; DBP: 67+/-3 mm Hg versus 69+/-6 mm Hg, p<0.05), A was not different, Acr in patients was shifted one hour earlier (SBP: 2.4 p.m. versus 3.6 p.m., p<0.05; DBP: 2.1 p.m. versus 3.3 p.m., p<0.01). This corresponds to the shift of the morning blood-pressure increase seen on 24-hours blood pressure profiles. M correlated with age in controls (SBP: r=0.374, p<0.01; regression coefficient b=1.34 mm Hg/1 year; DBP: r=0.365, p<0.01; b=0.95 mm Hg/1 year), but not in patients (SBP: r=0.182, DBP: r=0.064). A and Acr were age-independent in all subjects. It is concluded that blood pressure in 19-22 years old AC patients is lower during night hours, the age-dependent increase of blood pressure seen in healthy controls between 13 and 22 years of age does not occur in patients. This finding is consistent with the long-lasting impairment of the sympathetic nervous system caused by anthracyclines.
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Antraciclinas/efectos adversos , Antibióticos Antineoplásicos/efectos adversos , Presión Sanguínea/efectos de los fármacos , Ritmo Circadiano , Sobrevivientes , Adolescente , Factores de Edad , Estudios de Casos y Controles , Electrocardiografía Ambulatoria , Femenino , Humanos , Análisis de los Mínimos Cuadrados , Masculino , Sistema Nervioso Simpático/efectos de los fármacos , Sistema Nervioso Simpático/fisiopatología , Resultado del Tratamiento , Adulto JovenRESUMEN
It has been known for many years that baroreflex sensitivity is lowered in hypertensive patients. There are several known factors implicating this association, e.g. high blood pressure leads to remodeling of the carotid arterial wall, to its stiffness and to a diminished activation of baroreceptors; leptin released from a fatty tissue activates the sympathetic nervous system etc. On the other hand, low baroreflex sensitivity (BRS, usually quantified in ms/mmHg) can be inborn. Studies on primary hypertension in children and adolescents have brought new information about the role of baroreflex in the development of an early stage of primary hypertension. BRS lower than 3.9 ms/mmHg was found in 5 % of healthy subjects. This value approaches the critical value for the risk of sudden cardiac death in patients after myocardial infarction and corresponds to the value present in hypertensive patients. A decreased BRS and BRSf (baroreflex sensitivity expressed in mHz/mmHg, index independent of the mean cardiac interval), was found not only in children with hypertension, but also in those with white-coat hypertension. This is in accordance with a single interpretation. The decrease of BRS/BRSf precedes a pathological blood pressure increase. The contribution of obesity and BRS/BRSf to the development of hypertension in adolescents was also compared. Both factors reach a sensitivity and a specificity between 60 % and 65 %, but there is no correlation between the values of the body mass index and BRS either in the group of hypertensive patients or in healthy controls. If a receiver operating curve (sensitivity versus specificity) is plotted for both values together using logistic regression analysis, a sensitivity higher than 70 % and a specificity over 80 % are reached. This means that low baroreflex sensitivity is an independent risk factor for the development of primary hypertension. Studies demonstrate that adolescents with increased blood pressure and with BRS under 7 ms/mmHg should be given care and intensively motivated to change their lifestyle including a change in diet and increase in physical activity.
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Barorreflejo , Hipertensión/fisiopatología , Adolescente , Monitoreo Ambulatorio de la Presión Arterial , Humanos , Hipertensión/genética , Factores de RiesgoRESUMEN
We studied the relationship between blood pressure (BP), body mass index (BMI, kg/m(2)) and baroreflex sensitivity (BRS, ms/mmHg) in adolescents. We examined 34 subjects aged 16.2+/-2.4 years who had repeatedly high causal BP (H) and 52 controls (C) aged 16.4+/-2.2 years. Forty-four C and 22 H were of normal weight (BMI between 19-23.9), and 8 C and 12 H were overweight (BMI between 24-30). Systolic BP was recorded beat-to-beat for 5 min (Finapres, controlled breathing 0.33 Hz). BRS was determined by the cross-spectral method. The predicting power of BMI and BRS for hypertension was evaluated by sensitivity, specificity, and receiver operating curve (ROC - plot of sensitivity versus specificity). H compared with C had lower BRS (p<0.01) and higher BMI (p<0.05). Multiple logistic regression analysis (p<0.001) revealed that a decreased BRS (p<0.05) and an increased BMI (p<0.01) were independently associated with an increased risk of hypertension. No correlation between BMI and BRS was found either in H or in C. Following optimal critical values by ROC, the sensitivity, specificity and area under ROC were determined for: BMI - 22.2 kg/m(2), 61.8 %, 69.2 %, 66.0 %; BRS - 7.1 ms/mmHg, 67.7 %, 69.2 %, 70.0 %; BMI and BRS - 0.439 a.u., 73.5 %, 82.7 %, and 77.3 %. Decreased BRS and overweight were found to be independent risk factors for hypertension.
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Barorreflejo , Presión Sanguínea , Índice de Masa Corporal , Hipertensión/etiología , Sobrepeso/complicaciones , Adolescente , Adulto , Factores de Edad , Estudios de Casos y Controles , Niño , Femenino , Humanos , Hipertensión/fisiopatología , Modelos Logísticos , Masculino , Sobrepeso/fisiopatología , Valor Predictivo de las Pruebas , Curva ROC , Medición de Riesgo , Factores de Riesgo , Sensibilidad y Especificidad , SístoleRESUMEN
Correctly indicated physical exercise performed and controlled on a regular basis is an inseparable part of treatment and rehabilitation of patients with left ventricular dysfunction. In order to guarantee the best effect and safety of physical exercise, it is necessary to adopt a differential approach to its prescription to patients with different degrees of functional damage. In addition, a number of conditions should be fulfilled, among which, in the first place, the determination of functional classification of patients used in practice and described in the relevant literature (NYHA, AMA, Goldman, Weber). Physical exercise cannot be differentiated only with respect to the degree of dysfunction; other conditioning factors should be taken into consideration, too, among which the relative contraindication of physical strain, somatic condition, physical exercise anamnesis and others (i.e. sex, age, motivation, etc.), causing a high degree of patient heterogeneity. Also described are additional conditions for differentiation and correct application of physical training, which involve the selection of suitable types of exercise and their energetic demands, adequate intensity, frequency and duration; it is also important to determine the available effective and safe methods, programmes and means of training. The article contains examples of the above conditions, as well as classification of physical exercise into functional classes NYHA I-IV. In conclusion, the authors point out the necessity of differentiation of physical training and of cooperation of the cardiologist with the physiotherapist in its indication, implementation and monitoring.
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Terapia por Ejercicio , Disfunción Ventricular Izquierda/rehabilitación , Tolerancia al Ejercicio , Humanos , Disfunción Ventricular Izquierda/clasificación , Disfunción Ventricular Izquierda/fisiopatologíaRESUMEN
UNLABELLED: The analysis of short-term blood pressure regulation in children, adolescents and young adults 1 to 18 years after the treatment with anthracyclines known to have cardiotoxic side effects for oncological diseases was the aim of the present study. Thirty-one subjects treated with anthracyclines (PA) and 11 subjects treated with different antitumour drugs (P0) were investigated twice (the interval between two investigations 1-9 years). Three hundred and thirty-nine healthy subjects served as controls (C). Systolic (SBP), diastolic blood pressures (DBP) in the finger arteries and inter-beat interval (IBI) were recorded beat-to-beat (FINAPRES, Ohmeda, metronome controlled breathing, 5 minute recording); the values were corrected by auscultatory blood pressure measurements. Baroreflex sensitivity (BRS, ms/mmHg) was determined by a spectral method. As the investigated subjects were of different ages, the measured values were standardised on the age of 16 years by linear regression, and only standardised values (IBI16, SBP16, DBP16 and BRS16) were further analysed. No differences were found between PA, P0 and C in BRS16 and IBI16. SBP16 and DBP16 were significantly lower in PA (102.1+/-8.3/59.7+/-7.1 versus C: 114.1+/-12.4/69.0+/-9.5 mmHg; p<0.001/p<0.001; mean from two investigations). SBP16 but not DBP16 was also lower in P0 (102.7+/-12.6/64.5+/-9.7 mmHg; p<0.01/no significant) than in C. The correlation coefficient between SBP16 and period after treatment in PA was -0.11 (no significant) and -0.06 in DBP16 (no significant). Thus, there is not seen a trend to normalisation. CONCLUSION: The anthracycline antitumour therapy in children decreases blood pressure and within 18 years after the treatment there is not observed a trend toward normal values. BRS was not influenced by the anthracycline therapy.
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Antraciclinas/uso terapéutico , Barorreflejo/fisiología , Presión Sanguínea/fisiología , Enfermedad de Hodgkin/tratamiento farmacológico , Linfoma no Hodgkin/tratamiento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamiento farmacológico , Adolescente , Arterias/efectos de los fármacos , Arterias/patología , Monitores de Presión Sanguínea , Índice de Masa Corporal , Estudios de Casos y Controles , Niño , Preescolar , Femenino , Frecuencia Cardíaca , Enfermedad de Hodgkin/metabolismo , Enfermedad de Hodgkin/patología , Humanos , Lactante , Linfoma no Hodgkin/metabolismo , Linfoma no Hodgkin/patología , Masculino , Leucemia-Linfoma Linfoblástico de Células Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologíaRESUMEN
Re-evaluation of all functions of baroreflex by means of a simple mathematical model of circulation was the aim of the present study. The following states are modelled: 1. Rest. 2. Immediately after baroreceptor denervation. 3. Several days after denervation. 4. Physical exercise before denervation. 5. Physical exercise several days after denervation. Despite the same cardiac contractility and the same vasodilatation in working muscles as before denervation the cardiac output is by one third lower after baroreceptor denervation. In conclusion, a model simulation revealed the common regulation of blood pressure and blood volume by baroreflex and kidneys as a primary function of baroreflex.
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The relationship between age and circadian blood pressure (BP) variation was the aim of the present study. One hundred and eighty-seven subjects (130 males, 57 females), 20-77 years old, were recruited for seven-day BP monitoring. Colin medical instruments (Komaki, Japan) were used for ambulatory BP monitoring (oscillation method, 30-minute interval between measurements). A sinusoidal curve was fitted (minimum square method) and the mean value and amplitude of the curve (double amplitude corresponds to the night-day difference) were evaluated on every day of monitoring. The average 7-day values of the mean (M) and of double amplitude (2A) for systolic BP (SBP), diastolic BP (DBP), and heart rate (HR) were determined in each subject. The mean values of M (+/-SD) for the whole group were: SBP- 127+/-8, DBP - 79+/-6 mmHg, HR - 70+/-6 bpm; of 2A: SBP - 21+/-7, DBP - 15+/-5 mmHg, HR - 15+/-6 bpm. A linear relationship between M of SBP and age (r=0.341, p< 0.001) and DBP and age (r=0.384, p<0.001) was found (difference between 20 and 77 years: SBP - 16, DBP - 12 mmHg). 2A of SBP and DBP was increasing with age up to 35 years, then the curve remained relatively flat up to 55 years (maximum at 45 years), and then it decreased again (difference between 45 and 77 years: SBP - 13mmHg, DBP - 12 mmHg). Heart rate M and 2A were age-independent. The mean values of SBP and DBP were increasing with age up to 75 years, but the night-day difference of SBP and DBP reached its maximum value at 45 years and then decreased.
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The mapping of time structures, chronomes, constitutes an endeavor spawned by chronobiology: chronomics. This cartography in time shows signatures on the surface of the earth, cycles, also accumulating in life on the earth's surface. We append a glossary of these and other cycles, the names being coined in the light of approximate cycle length. These findings are transdisciplinary, in view of their broad representation and critical importance in the biosphere. Suggestions of mechanisms are derived from an analytical statistical documentation of characteristics with superposed epochs and superposed cycles and other "remove-and-replace" approaches. These approaches use the spontaneously changing presence or absence of an environmental, cyclic or other factor for the study of any corresponding changes in the biosphere. We illustrate the indispensability of the mapping of rhythm characteristics in broader structures, chronomes, along several or all available different time scales. We present results from a cooperative cartography of about 10, about 20, and about 50-year rhythms in the context of a broad endeavor concerned with the Biosphere and the Cosmos, the BIOCOS project. The participants in this project are our co-authors worldwide, beyond Brno and Minneapolis; the studies of human blood pressure and heart rate around the clock and along the week may provide the evidence for those influences that Mendel sought in meteorology and climatology.
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The aim of the study was to assess the time structure (chronome) of sudden cardiac death (SCD) in Austria. The daily incidence of SCD (ICD-10 I46.1) in Austria was obtained for the 4-year span from Jan 2002 to Dec 2005. Data were available separately for men and women. This data series was analyzed by linear-nonlinear rhythmometry. The major feature is the detection of a cis-half-year that is validated nonlinearly, the estimated period of the cis-half-year is 0.408 year (95% CI: 0.389, 0.426). It is concluded that the chronobiological analysis of sudden cardiac death in Austria showed the variability of total incidence with the period of a cis-half-year.
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The objective of this study was to find if there was a relationship between the time when cardiovascular rehabilitation was running in the patients after myocardial infarction and an average daily value of systolic and diastolic blood pressure at 7-day ambulatory blood pressure monitoring.Systolic and diastolic pressures significantly increased in patients who underwent cardiovascular rehabilitation in the morning from 9.00 a.m. to 10.15 a.m., and significantly decreased in those who did their physical exercise in the afternoon from 1.30 p.m. to 2.45 p.m., compared to their blood pressure values on days without rehabilitation.
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BIOCOS, the project aimed at studying BIOlogical systems in their COSmos, has obtained a great deal of expertise in the fields of blood pressure (BP) and heart rate (HR) monitoring and of marker rhythmometry for the purposes of screening, diagnosis, treatment, and prognosis. Prolonging the monitoring reduces the uncertainty in the estimation of circadian parameters; the current recommendation of BIOCOS requires monitoring for at least 7 days. The BIOCOS approach consists of a parametric and a non-parametric analysis of the data, in which the results from the individual subject are being compared with gender- and age-specified reference values in health.Chronobiological designs can offer important new information regarding the optimization of treatment by timing its administration as a function of circadian and other rhythms.New technological developments are needed to close the loop between the monitoring of blood pressure and the administration of antihypertensive drugs.
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UNLABELLED: The aim of this study is to analyse the acute effect of water-pipe smoking on heart rate, blood pressure and the baroreflex control of heart rate. SUBJECTS AND METHODS: Non-invasive continuous methods were used for investigating inter-beat interval (IBI; ms), systolic blood pressure (SBP; mm Hg), diastolic blood pressure (DBP; mm Hg), pulse pressure (PP; mm Hg), mean blood pressure (MBP; mm Hg); baroreflex sensitivity in ms/mm Hg (BRS) and baroreflex sensitivity in Hz/mm Hg (BRSf), were determined by spectral analysis, in 20 normotensive volunteers age of 27+/-6 years (mean+/-S.D.) who served as their own control. The measurements were taken twice. The first measurement was taken before the water-pipe smoking session (this is after >12 h of smoking cessation with a complete stopping of alcohol, coffee or tea consumption). The second measurement was taken during a 5 min period immediately after that session. (In the smoking session the volunteer smokes 5 g Maassel (fruit flavoured tobacco) for a period of 45 min). RESULTS: The inter-beat interval decreased (846+/-100 to 709+/-109 ms, p=0.0003), SBP increased (110+/-13 to 123+/-12 mm Hg, p=0.004), DBP increased (67+/-11 to 81+/-11 mm Hg, p=0.0002), PP decreased (43+/-10 to 41+/-9 mm Hg, p=0.46 ns), MBP increased (82+/-10 to 95+/-11 mm Hg, p=0.0001), BRS decreased (9.16+/-4 to 5.67+/-3 ms/mm Hg, p=0.003) and BRSf (0.013+/-0.005 to 0.011+/-0.004 Hz/mm Hg, p=0.3 ns). CONCLUSIONS: Water-pipe smoking induced a high increase in heart rate, SBP, DBP, MBP and markedly impaired BRS. All of those markers are known as risk factors in cardiovascular diseases, hence it is concluded that water-pipe smoking is not as harmless as is thought.
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Barorreflejo/fisiología , Frecuencia Cardíaca/fisiología , Fumar/fisiopatología , Adulto , Barorreflejo/efectos de los fármacos , Presión Sanguínea/fisiología , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Masculino , Estadísticas no ParamétricasRESUMEN
The reproducibility of baroreflex sensitivity (BRS in ms/mmHg; BRSf in mHz/mmHg) determined with respect to the coherence between the variability in systolic blood pressure (SBP) and inter-beat intervals (IBI) or heart rate (HR) was tested. SBP and IBI were recorded beat-to-beat for 5 min (Finapres, breathing at 0.33 Hz) in 116 subjects (aged 19-24 years) sitting at rest three times in periods of one week. BRS and BRSf was determined by a cross-spectral method in a frequency range of 0.067-0.133 Hz. Eight indices were evaluated: BRS(0.1 Hz) /BRSf(0.1 Hz) - the value at a frequency of 0.1 Hz; BRS(COHmax)/BRSf(COHmax) - the value at maximum coherence; BRS(Wcoh)/BRSf - weighted value with respect to coherence values in the whole frequency range; BRS(WPcoh)/BRS(WPcoh) - weighted value with respect to coherence for frequencies with coherence above 0.5. All indices revealed a lower intraindividual than interindividual variability (p<0.001). The individual mean values of BRS or BRSf correlated (p<0.001) with standard deviation of their individual values for all indices. Baroreflex sensitivity is an individual characteristic feature with the highest reproducibility at its low values in spite of its resting variation. Reproducibility is not influenced by modification of the spectral method used.