Influence of gestational age, heart rate, gender and time of day on fetal heart rate variability

From adult data, it is known that numerous factors, such as age, state of the autonomic nervous system, diurnal rhythms or mean R-R intervalmRR, influence heart rate variability (HRV). The aim of this study was the examination of the influence of gestational age,mRR, gender and time of day on fetal HRV. The analysis was based on 66 fetal magnetocardiograms (FMCGs) of 22 healthy fetuses between the 16th and 42nd week. FMCGs were recorded for 5 min using a multichannel biomagnetometer. On the basis of the time series of fetal R-R intervals,mRR as well as the standard deviationsdRR, root mean square of successive differencesrmssdRR and approximate entropyApEn were calculated. The influence of gestational age,mRR and gender onsdRR, rmssdRR andApEn was determined by regression analysis. The relationship between time of day and HRV was evaluated by visual inspection of scatterplots. The logarithmised HRV measures increased significantly with the logarithm of gestational age (regression coefficients:sdRR=1.28,rmssdRR=1.12,ApEn=1.30) andmRR (regression coefficients:sdRR=0.008,rmssdRR=0.011,ApEn=0.012) There was no significant influence of gender. With respect to time of day (between 0800 h and 1800 h), no dependency of the HRV measures was apparent. In summary, when fetal HRV is assessed, it is essential to take gestational age andmRR into account. In contrast, time of day, with respect to daytime, and gender need not be considered. In future studies, the influence of fetal activity state on HRV should be examined.     

Platelet adhesiveness, plasma fibrinogen, and fibrinolytic activity in juvenile-onset and maturity-onset diabetes mellitus.

The nature of vascular disease and its complications are different in juvenile-onset (JOD) and maturity-onset (MOD) diabetes mellitus. In order to explore the disturbances in the coagulation-fibrinolytic system, platelet adhesiveness, plasma fibrinogen, and euglobulin lysis time were estimated in 26 cases of MOD. Two groups of age- and sex-matched controls were also studied. Platelet adhesiveness and plasma fibrinogen were essentially normal while euglobulin lysis time was significantly decreased in the JOD group. The MOD group, on the other hand, showed a reversed pattern in the form of enhanced platelet adhesiveness and plasma fibrinogen and no compensatory increase in fibrinolysis.     

Activated thromboplastin time, plasma heparin and plasma fibrinogen using the Fibrintimer 10

After a thorough study, and having chosen the machine that is to equip an average sized haemostasis laboratory, the installation then requires certain steps (the reorganisation of work, better adapted reagents, a change of normality, a fine tuning of the technics, the time to get used to the machine). In this perspective, this work describes the regulation of the technic to determine the heparin activity on the Fibrintimer 10 (F 10) by chronometry (thrombin clotting time with variable concentration), a study of the repeatability and reproducibility of activated partial thromboplastin time (APTT), plasma heparin (HEP) and fibrinogen on the Fibrintimer 10, a study of the correlation between the results we got with the F 10 and the thermostat water-bath for the APTT and the HEP and between those we got on the F 10 and the fibrometer for the fibrinogen. The F 10 has allowed us to save more time whilst keeping the same technics and reagents. The determination of the heparin activity, by thrombin clotting time with variable concentration, gives us a method which is quick, cheap and useful for the following-up of the patients undergoing a treatment with standard heparin. The reproducibility and repeatability prove to be good for the 3 tests in our operatory conditions as well as the correlations between the results we get with both methods.     

The relationship of the dilute whole blood lysis time to the fibrinolytic activity of blood: effect of change in plasma fibrinogen

The rate of digestion of fibrin was measured in vitro by an isotopic technique in 140 blood samples of differing fibrinogen concentration; the assessment of fibrinolytic activity thus obtained was compared with a standard method of measurement, the dilute whole blood lysis time. The lysis time was related exponentially to the fibrinolytic activity as measured by the isotopic technique, and further was influenced markedly by alteration in the plasma fibrinogen concentration. The relevance of these observations to the use of lysis time methods for the measurement of fibrinolytic activity is discussed.     

Influence of age and gender on the jaw-stretch and blink reflexes

The aim of this study is to investigate the influence of age and gender on jaw-stretch and blink reflexes (BR). Thirty “young” (26.5±0.7 years) and thirty “old” (47.8±1.8 years) healthy adults were included. Short-latency stretch reflex responses were evoked in the masseter and temporalis muscles by fast jaw-stretches, and BR in orbicularis oculi muscle were evoked by painful electrical pulses (0.5 ms duration), delivered by a concentric electrode placed on the left lower forehead close to the supraorbital foramen. For the jaw-stretch reflex, the pre-stimulus EMG activity in the old subjects was significantly lower than that of the young subjects in the right and left masseter and temporalis muscles (P<0.006), whereas there was no difference in the results between males and females. The normalized peak-to-peak amplitude of the EMG in the left masseter and left and right temporalis muscles was significantly lower in the old subjects compared with the young subjects (P<0.02). Females had significantly higher normalized peak-to-peak EMG amplitudes compared with males in the right masseter and left temporalis muscles (P<0.05). The old subjects had significantly lower root mean square (RMS) (P=0.01) and average (P<0.02) BR values in the right and left orbicularis oculi muscles, and lower area under the curve (AUC) (P=0.02) values in the left orbicularis oculi muscle compared with the young subjects. Female subjects had significantly lower AUC (P=0.02) in the left orbicularis oculi muscle compared with males. The old subjects had significantly later offset (P<0.003) and longer duration (P<0.001) in the left orbicularis oculi compared with the young subjects. The results of the present study demonstrated a significant effect of both age and gender on stretch and BR and suggested that these variables should be taken into consideration in the interpretation of brainstem reflexes in basic and clinical studies.     

A rapid screening test for reduced fibrinolytic activity of plasma: streptokinase activated lysis time.

A simple screening method for determining the fibrinolytic activity of plasma is described. A streptokinase activated system is used, which measures the result of the interplay of all components of the fibrinolytic system with the exception of activators, which are added in excess. Mean lysis time and standard deviation with this method is 6.9 +/- 1.4 min. The sensitivity of the method in detecting minor delays in clot lysis time is demonstrated.     

Relationships among gender,age, time,and temperature in methamphetamine-induced striatal dopaminergic neurotoxicity

A neurotoxic regimen of methamphetamine (MA—40 mg/kg ip) administered at 0 (control—MA vehicle), 0.5 and 72 h prior to determinations of striatal dopamine (DA) and DOPAC (3,4-dihydroxyphenylacetic acid)/DA ratios were compared among juvenile and adult female and male mice. Adult females and males showed similar depletions in striatal DA at 0.5 h post-MA, but males showed greater DA depletions and DOPAC/DA ratios at 72 h post-MA. Juvenile mice showed neither sex differences, nor any MA neurotoxicity upon striatal DA or DOPAC/DA ratios. Following MA, body temperatures increased in all mice, but increases in adult males were greater than adult females; juveniles showed no sex differences and body temperature increases were similar to that of adult males. MA-evoked DA output was greater in adult compared to juvenile males and a biologically effective regimen of testosterone to juvenile males neither increased MA-evoked DA output nor decreased MA-induced striatal DA like that observed in adult males. These results demonstrate: (1) Unlike adults, juvenile mice show neither a sex difference for MA-induced neurotoxicity or body temperature increases, nor MA neurotoxicity, (2) Initial effects of MA (0.5 h) in adult females and males are similar, but at 72 h post-MA females show no further striatal DA depletion, (3) Increased striatal DA depletion within adult versus juvenile males may be related to initially higher MA-evoked DA responses, and (4) Testosterone fails to convert juvenile males into adults with regard to MA effects.     

The impact of age, weight and gender on BDNF levels in human platelets and plasma

Brain-derived neurotrophic factor (BDNF) is a key mediator of neuronal plasticity in the adult. BDNF is known to be stored in human platelets and to circulate in plasma, but the regulation and function of BDNF in peripheral blood is still poorly understood. In this prospective study, we have examined 140 healthy, non-allergic adults (20-60 years old) to elucidate the impact of age and physical parameters on BDNF levels in human platelets and plasma. There was a wide concentration range of BDNF in serum (median: 22.6 ng/ml), platelets (median: 92.7 pg/10(6) platelets) and plasma (median: 92.5 pg/ml). BDNF levels in plasma decreased significantly with increasing age or weight, whereas platelet levels did not. When matched for weight, there were no significant gender differences regarding BDNF plasma levels. However, women displayed significantly lower platelet BDNF levels than men. In addition, platelet BDNF levels changed during the menstrual cycle. In conclusion, we demonstrate that parameters such as age or gender have a specific impact on stored and circulating BDNF levels in peripheral blood.     

海南汉族人群九个纤维蛋白原基因多态性及其与血浆纤维蛋白原水平的关系

目的 调查海南汉族健康人群αTaqⅠ和βBclⅠ、HinfⅠA／C、448G／A、βBsmA ⅠG／C、＋1689T／G、-148C／T、-249C／T、-455G／A多态性的等位基因频率及其与血浆纤维蛋白原（fibrinogen，Fg）水平的关系。方法 用比浊法测定238名健康个体的血浆Fg浓度，用PCR-限制性片段长度多态性方法及测序法分析多态性基因型，并用协方差分析比较9个位点的基因型与血浆Fg水平的关系。结果 海南汉族人群αTaqⅠ、βBclⅠ、HinfⅠA／C、C448、βBsmAⅠG／C、＋1689T／G、-148C／T、-249C／T、-455G／A稀有位点的等位基因频率分别为0．445、0．239、0．134、0．235、0．273、0．241、0．265、0．441、0．254，9个位点之间存在连锁不平衡；在总人群中，-455GA和AA基因型、-148CT和TT基因型、αTaqⅠT1T1基因型组的血浆Fg水平比野生型组高（P值均〈0．01）；在男性人群中，-455GA和AA基因型、-148CT和TT基因型、αTaqⅠT1T1、αTaqⅠT1T2基因型组的血浆Fg水平比野生型组高（P值均〈0．01）。在女性人群中，携带稀有位点A^-455、T^-148、αTaⅠT1的基因型组与野生型组之间的血浆赡水平差异无统计学意义。结论 在9个多态性位点之间存在连锁不平衡；A^-455、T^-148、αTaqⅠT1位点与血浆Fg水平增高关联，β-Fg-455G／A、-148C／T及α-TaqⅠ多态性与男性血浆Fg水平关联。     

Influence of age,sex and somatic variables on the motor performance of pre-school children

Abstract

Background: Biological factors can affect the motor development process of children. However, the magnitude of these effects throughout the developmental process remains fairly unknown.

Aim: To determine the influence of age, sex and selected somatic measures on the motor performance of pre-school children.

Subjects and methods: Three hundred and sixty-seven pre-schoolers (172 boys and 195 girls), aged from 3–5 years old, were recruited from 10 public pre-schools located in the district of Viana do Castelo, Portugal. The children’s motor performance was assessed by five motor sub-tests of Peabody Developmental Motor Scales-2: grasping, visuo-motor integration, stationary, locomotion and object manipulation sub-tests. Age, sex, height, weight and BMI were considered as hypothetical predictors of motor performance. Pearson’s correlation test and multiple linear regression analysis were used to explore the magnitude of the relationship between motor sub-tests and the hypothetical predictors.

Results: Depending on the motor sub-test and age group, the models predicted motor performance from a minimum of 3.6% to a maximum of 34.4%. Age in months and sex stood out as the main predictors of motor performance.

Conclusions: The relationship between motor performance and selected biological factors varied with age and with the specificity of the motor test.     

Influence of oral intake of retinoids on the human plasma fibrinolytic system

Retinoic acid and some of its derivatives cause a specific induction of tissue-type plasminogen activator (t-PA) synthesis in cells cultured in vitro as well as in experimental animals. In the present study we have evaluated the effect of the oral intake of β-carotene and of isotretinoin (13-cis-retinoic acid) or acitretinoin (acitretin) on the human fibrinolytic system. In the placebo-controlled cross-over β-carotene study 18 healthy volunteers received β-carotene at a dose of 250 mg/day for 4 days. Euglobulin fibrinolytic activity (EFA) was 0.98±0.47 U/ml (mean±SD, n=18) and 0.79±0.26 U/ml before and after intake, respectively. t-PA antigen values in plasma were 5.0±1.8 ng/ml and 3.9±1.4 ng/ml, respectively. PAW activity levels were 12±15 and 13±13 ng/ml, respectively. Paired t-test analysis on values before and after intake could not reveal any significant difference.In the prospective retinoid study plasma was obtained from 12 patients (with acne-related or psoriasis-related skin disorders) before and 1 month after daily oral intake of 20 to 60mg isotretinoin (13-cis-retinoic acid) or acitretinoin (acitretin). In these patients mean values (±SD) for EFA were 2.9±4.8 and 3.0±5.7 U/ml before and during treatment, respectively; t-PA antigen values were 2.6±1.3 and 3.3±1.6 ng/ml before and during treatment, respectively and values of 4.4±4.0 and 6.1±6.4 ng/ml were found for PAI-1 activity before and during treatment, respectively. Paired t-test analysis revealed a significant increase (p=0.027) in t-PA antigen during therapy. No changes were observed in EFA or PAI-1 activity.In conclusion, these results suggest that the retinoids isotretinoin and acitretinoin, but not β-carotene, can have a minor but significant influence on circulating t-PA antigen in human plasma. The present data indicate that, in an effort to modulate pharmacologically the fibrinolytic potential in plasma, it may be interesting to perform further in vivo studies with other retinoids, showing in vitro a more potent t-PA inducing activity relative to their PAI-1 inducing activity.     

A field study of age and gender differences in habitual adult sleep

The sleep of 52 healthy paid subjects (23 male) divided into three age-bands (20–34, 35–49 and 50–70 y) were recorded at night in their homes for a total of 190 subject-nights while following their normal daily activities and habitual sleep-wake schedule. There was a shortening in both nocturnal total sleep period and total sleep time (TST) with age, the oldest group sleeping 46 min less than the youngest. Also, the mid-point of sleep occurred 32 min earlier in the oldest group compared with the youngest group. The reduction in TST with age was due, in part, to increased wake periods within sleep. The youngest subjects showed more Movement Time which progressively decreased with age while the amount of stage 1 increased with age. The amount of slow-wave sleep (SWS, stages 3+4) was reduced, stage 4 was more than halved, while REM was slightly reduced with age. There were far fewer significant gender differences in the sleep variables: males, particularly in the middle and oldest age bands, had more stage 1 than females, while females had more SWS, particularly stage 3, than males. In general, despite relatively limited subject selection criteria, there was good agreement with previous laboratory-based normative sleep values for the effect of age and gender.     

An investigation of methods to prevent fibrinogen degradation during processing of plasma samples containing the fibrinolytic agents,APSAC and t-PA

Artefactual depletion of fibrinogen may occur in plasma obtained from patients receiving thrombolytic agents if free plasmin is present and allowed to act during processing of the samples.The present studies, in vitro, examined the protection afforded to fibrinogen by the exogenous inhibitors aprotinin and ϵ-aminocaproic acid (EACA) when added to human plasma containing levels of anisoylated lys-plasminogens-treptokinase activator complex (APSAC) or tissue-type plasminogen activator (t-PA) equivalent to the maximum concentrations expected in acute myocardial infarction patients. At ambient temperature (25°C), a high concentration of aprotinin (3000 KIU/ml, 64 μM) protected fibrinogen concentrations for up to 3 h but lower concentrations of aprotinin were inadequate. Complete fibrinogen protection at 25°C could not be achieved at any concentration of EACA up to 300 mM.We conclude that if fibrinogen is to be measured during thrombolytic therapy then the addition of a high concentration of aprotinin immediately after blood sampling (3000 KIU/ml plasma) is the simplest method to prevent laboratory artefacts occurring during less than optimal processing conditions.     

Following the time course of face gender and expression processing: A task-dependent ERP study

The effects of task demands and the interaction between gender and expression in face perception were studied using event-related potentials (ERPs). Participants performed three different tasks with male and female faces that were emotionally inexpressive or that showed happy or angry expressions. In two of the tasks (gender and expression categorization) facial properties were task-relevant while in a third task (symbol discrimination) facial information was irrelevant. Effects of expression were observed on the visual P100 component under all task conditions, suggesting the operation of an automatic process that is not influenced by task demands. The earliest interaction between expression and gender was observed later in the face-sensitive N170 component. This component showed differential modulations by specific combinations of gender and expression (e.g., angry male vs. angry female faces). Main effects of expression and task were observed in a later occipito-temporal component peaking around 230 ms post-stimulus onset (EPN or early posterior negativity). Less positive amplitudes in the presence of angry faces and during performance of the gender and expression tasks were observed. Finally, task demands also modulated a positive component peaking around 400 ms (LPC, or late positive complex) that showed enhanced amplitude for the gender task. The pattern of results obtained here adds new evidence about the sequence of operations involved in face processing and the interaction of facial properties (gender and expression) in response to different task demands.