年龄因素对健康人心率变异性的影响

目的探讨年龄因素对健康人心率变异性（ＨＲＶ）的影响。材料与方法将２３６例健康人分为五个年龄组，使用美国先进医用设备公司５．０版本ＨＲＶ软件做短时时域及频域ＨＲＶ分析。结果年龄因素对健康人ＨＲＶ短时时域和频域分析的多项指标产生显著影响，随着年龄增大，时域指标中的ＨＲＳＤ、ＳＤＡＮＮ、ｒＭＳＳＤ及ＰＮＮ５０均逐渐降低；随着年龄增长，频域指标中各频段下的绝对面积，即：ＶＬＦ、ＬＦ、ＭＦ及ＨＦ均逐渐降低；而频域指标中各频段下的相对面积，即：ＶＬＦＰ、ＬＦＰ、ＭＦＰ、ＨＦＰ随着年龄增长呈不同的发展趋势。ＬＦ／ＨＦ随着年龄的增加而逐渐升高。结论ＨＲＶ随着年龄的增加而下降，尤以迷走神经活性下降为显著。频域指标中各频段的相对面积较绝对面积能更敏感地反映交感、迷走神经张力的消长。     

Effects of age and chronic renal failure on the urinary excretion kinetics of famotidine in man

Summary The plasma and urine concentrations of famotidine, a new, potent H₂-receptor antagonist, have been measured in 16 healthy young adults, 8 healthy elderly people and 18 patients with varying degrees of renal dysfunction after intravenous administration.Both the plasma elimination and renal excretion of famotidine were decreased in the elderly volunteers and renal patients. The renal clearance of famotidine averaged 4.43 ml/min/kg (310 ml/min) in normal young volunteers, which exceeded the mean creatinine clearance 1.55 ml/min/kg (109 ml/min), suggesting net secretion is a significant mechanism for elimination of famotidine.The ratio of famotidine renal clearance to creatinine clearance decreased as creatinine clearance decreased; these results suggest that the deterioration in the secretion process was much faster than that in glomerular filtration and are incompatible with the intact nephron hypothesis. Nevertheless, both total body clearance and renal clearance were significantly correlated with creatinine clearance.The apparent half-life was also significantly correlated with creatinine clearance. Since famotidine is essentially free of dose-related adverse effects, dose adjustment in patients with mild renal insufficiency and in elderly people is not required; however, either a prolonged dosing interval or a decrease in daily dose during long-term therapy may be adapted for the patients with severe renal insufficiency to avoid accumulation and the potential undesirable effects.     

Assessment of Skin Barrier Function Using Transepidermal Water Loss: Effect of Age

To probe age-related changes in skin barrier function, transepidermal water loss (TEWL) rates have been measured in young (19–42 years) and old (69–85 years) subjects. TEWL was determined at ventral forearm skin sites, which had been occluded for 24 hr with polypropylene chambers. Baseline TEWL rates (J , which showed no dependence on age, were measured for each subject before and after the experiment. Following removal of the occlusive chamber, TEWL was monitored continuously from t = 0.5 min until its return to the baseline (preocclusion) level, which was typically in the range of 2–7 g/m²/hr. Initial TEWL rates (mean ± SD) were found to differ significantly between young (28.6 ± 7.5 g/m²/hr; n = 26) and old (36.9 ± 10.5 g/m²/hr; n = 18) subjects (P < 0.01). Relaxation of TEWL to J was significantly slower in the aged cohort, such that the characteristic time for diffusion of water in the stratum corneum was estimated to be (mean ± SD) 176 ± 59 min for the young subjects, compared to 360 ± 76 min for the old (P < 0.001.). Thus, the initial TEWL value following removal of occlusion is significantly greater, and the excessive stratum corneum hydration produced by occlusion is dissipated more slowly, in old skin than in young. A hypothesis to explain the slower relaxation of perturbed TEWL in old skin is proposed.     

小儿肝的年龄解剖学研究

分六个年龄组观察了180个(男98,女82)小儿肝的形态、度量、位置及体表投影.小儿肝相对较大,右叶大于左叶,下界位置较低并逐渐上移.在右锁骨中线的肋弓下一般均可触到.小儿肝重随其年龄(身高)的增长而增长,其增长速度相对较慢,尤以Ⅶ组小儿更明显.     

Serum total IgE levels in a representative sample of a Greek population

The distribution of IgE in a large randomly stratified Greek population sample was determined in 1187 subjects (793 men and 394 women) aged between 20 and 60 years. Skin prick testing was performed and serum total IgE expressed in iu/ml was measured by Phadebas PRIST: the data are presented as the geometric mean. Subjects were classified as atopic (257 men, 118 women) and nonatopic (536 men, 276 women) according to the results of skin testing with various aeroallergens. At any age, atopic males (120.5 vs 38 iu/ml) and females (99.8 vs 29.3 iu/ml) had higher mean IgE levels, as compared to nonatopic subjects ( P <0.0001). In our adult nonatopic sample, IgE levels did not differ with age ( P >0.05). At any age, nonatopic males had higher (38 iu/ml) mean IgE levels than nonatopic females (29.3 iu/ml) ( P <0.05). The comparison of normal IgE values (nonatopic subjects) from this study with those reported by other investigators revealed that Greek adult males and females had higher IgE levels than populations from other nations. Our results represent the first report on reference values regarding serum total IgE in Greek adults.     

大鼠孤束核内NT-LI成分生后发育和衰老变化的光镜和电镜观察

用免疫细胞化学和电镜相结合技术,在光镜和电镜水平对生后4天、15天、30天、90天、300天和760天6组大鼠孤束核内神经降压肽样免疫反应(NT-LI)成分的生后发育和衰老变化进行了定量研究。光镜下孤束核内NT-LI胞体和终末主要分布于最后区平面,多见于背侧亚核、内侧亚核和连合核内。电镜下内侧亚核内可见NT-LI胞体、树突、轴突及终末。6组大鼠孤束核内NT-LI细胞均数和内侧亚核内NT-LI终末密度及其突触密度均以生后4天至15天间增长最快,NT-LI细胞数在生后15天达到最高,NT-LI终末及突触密度在生后90天达到最高。三者在生后300天时均明显减少。发育期内侧亚核内NT-LI终末构成的突触以Gray Ⅰ型为主,至老年期则变为Gray Ⅱ型占优势。发育期内侧亚核内以含清亮囊泡伴颗粒囊泡的NT-LI终末为主,老年期此类终末明显减少。只含清亮囊泡的NT-LI终末从生后至老年变化不明显。     

Melanotic Neuroectodermal Tumor of Infancy Occurring in the Left Thigh of a 6-Month-Old Female Infant

We report an exceptional case of melanotic neuro-ectodermal tumor of infancy (MNTI) occurring in the soft tissue of the left thigh of a 6-month-old female infant. The tumor consisted mainly of small round cells (neuroblasts) arranged in cords and nests that were separated by broad fibrovascular areas. In addition, there were a few medium-sized tumor cells containing melanin pigment (melano-cytic cells) that in electron microscopy contained melanosomes as well as tonofilaments. Both tumor cell types immunostained for neuron-specific enolase (NSE) and vimentin, and the melanocytic cells reacted additionally with the antikeratin antibody KL1. Within the tumor stroma, neurofilament- and S-100-protein-positive neural cells and vimentin- and desmin-positive myofibroblasts were seen. Although densecore granules were demonstrated ultrastructurally in some neuroblasts, no immunostaining for chromogranin A, Leu-7, serotonin, or regulatory peptides was found. MNTI located in an extremity can be confused with malignant small round and blue cell tumors of childhood. The distinction between MNTI and these tumors is of clinical significance because MNTI, in most cases, is a benign tumor that, in contrast to the latter, can be cured by complete excision. The presence of a biphasic cell population with neuroblasts and melanocytic cells must be considered the main diagnostic feature of MNTI.     

Birth factors and laterality: Effects of birth order,parental age,and birth stress on four indices of lateral preference

As an alternative to genetic theories of handedness, some theorists have offered an environmental mechanism, associated with birth stress, for the appearance of left-handedness. They suggest that brain damage as a result of birth difficulties can lead to a switch in hand preference from the right side to the left side. Consequently, one should find more left-handers in groups where the probability of the occurrence of birth stress is greater. Three studies are presented which explore the laterality of not only hand but also foot, eye, and ear, in a total of 5161 individuals, in an attempt to assess any relationship to birth stress. Maternal age seems to predict deviations from dextrality, dependent on the sex of the offspring, while paternal age and birth order do not. The use of a direct measure of conditions predisposing toward birth stress suggests that these results depend on prenatal or perinatal environmental trauma rather than chromosomal factors.This research was supported by grants from the Medical Research Council of Canada and from the Natural Sciences and Engineering Research Council of Canada, and represents an equal and shared contribution of both authors.     

Using linked markers to infer the age of a mutation

Advances in sequencing and genotyping technologies over the last decade have enabled geneticists to easily characterize genetic variation at the nucleotide level. Hundreds of genes harboring mutations associated with genetic disease have now been identified by positional cloning. Using variation at closely linked genetic markers, it is possible to predict the times in the past at which particular mutations arose. Such studies suggest that many of the rare mutations underlying human genetic disorders are relatively young. Studies of variation at genetic markers linked to particular mutations can provide insights into human geographic history, and historical patterns of natural selection and disease, that are not available from other sources. We review two approaches for estimating allele age using variation at linked genetic markers. A phylogenetic approach aims to reconstruct the gene tree underlying a sample of chromosomes carrying a particular mutation, obtaining a “direct” estimate of allele age from the age of the root of this tree. A population genetic approach relies on models of demography, mutation, and/or recombination to estimate allele age without explicitly reconstructing the gene tree. Phylogenetic methods are best suited for studies of ancient mutations, while population genetic methods are better suited for studies of recent mutations. Methods that rely on recombination to infer the ages of alleles can be fine‐tuned by choosing linked markers at optimal map distances to maximize the information available about allele age. A limitation of methods that rely on recombination is the frequent lack of a fine‐scale linkage map. Maximum likelihood and Bayesian methods for estimating allele age that rely on intensive numerical computation are described, as well as “composite” likelihood and moment‐based methods that lead to simple estimators. The former provide more accurate estimates (particularly for large samples of chromosomes) and should be employed if computationally practical. Hum Mutat 18:87–100, 2001. © 2001 Wiley‐Liss, Inc.     

Influence of age on serum protein binding of propranolol

Summary The extent of propranolol protein binding was determined in three different age groups of healthy drug-free caucasian males. Volunteers selected for study were 6–15 years old, 25–36 years old and 68–76 years old. Ten milliliters of blood were obtained via venipuncture and collected in glass tubes from the subjects after an overnight fast. Binding determinations were performed by equilibrium dialysis using radiolabelled propranolol. Serum albumin and ₁-acid glycoprotein concentrations were determined in all subjects by radial immunodiffusion. The results obtained showed wide intersubject variability in the binding ratio of propranolol and serum concentrations of ₁-acid glycoprotein. Mean albumin serum concentration was found to be significantly lower in the elderly group as compared to the adult and pediatric groups (p<0.02). A positive correlation was found between the binding ratio of propranolol and the serum concentration of ₁-acid glycoprotein in all the subjects (r=+0.66,p<0.005). No significant correlation was found between the binding ratio of propranolol and the serum concentration of albumin (r=–0.03,p<0.88). These data suggest that the extent of propranolol binding is influenced primarily by serum concentrations of ₁-acid glycoprotein and not by differences in age.