BACKGROUND & AIMS: :The environmental mobility of newly deposited radionuclides in surface soil is driven by complex biogeochemical relationships, which have significant impacts on transport pathways. The partition coefficient (Kd) is useful for characterizing the soil-solution exchange kinetics and is an important factor for predicting relative amounts of a radionuclide transported to groundwater compared to that remaining on soil surfaces and thus available for transport through erosion processes. Measurements of Kd for 238U are particularly useful because of the extensive use of 238U in military applications and associated testing, such as done at Los Alamos National Laboratory (LANL). Site-specific measurements of Kd for 238U are needed because Kd is highly dependent on local soil conditions and also on the fine soil fraction because 238U concentrates onto smaller soil particles, such as clays and soil organic material, which are most susceptible to wind erosion and contribute to inhalation exposure in off-site populations. We measured Kd for uranium in soils from two neighboring semiarid forest sites at LANL using a U.S. Environmental Protection Agency (EPA)-based protocol for both whole soil and the fine soil fraction (diameters<45 microm). The 7-d Kd values, which are those specified in the EPA protocol, ranged from 276-508 mL g-1 for whole soil and from 615-2249 mL g-1 for the fine soil fraction. Unexpectedly, the 30-d Kd values, measured to test for soil-solution exchange equilibrium, were more than two times the 7-d values. Rates of adsorption of 238U to soil from solution were derived using a 2-component (FAST and SLOW) exponential model. We found significant differences in Kd values among LANL sampling sites, between whole and fine soils, and between 7-d and 30-d Kd measurements. The significant variation in soil-solution exchange kinetics among the soils and soil sizes promotes the use of site-specific data for estimates of environmental transport rates and suggests possible differences in desorption rates from soil to solution (e.g., into groundwater or lung fluid). We also explore potential relationships between wind erosion, soil characteristics, and Kd values. Combined, our results highlight the need for a better mechanistic understanding of soil-solution partitioning kinetics for accurate risk assessment.

背景与目标： : 新沉积的放射性核素在表层土壤中的环境迁移率是由复杂的生物地球化学关系驱动的，这些关系对运输途径有重大影响。分配系数 (Kd) 可用于表征土壤溶液交换动力学，并且是预测输送到地下水的放射性核素与残留在土壤表面的放射性核素的相对量相比的重要因素，因此可用于通过侵蚀过程进行运输。238U的Kd测量特别有用，因为238U在军事应用和相关测试中广泛使用，例如在洛斯阿拉莫斯国家实验室 (LANL) 进行的。需要对238U进行特定地点的Kd测量，因为Kd高度依赖于当地土壤条件，也高度依赖于精细的土壤分数，因为238U集中在较小的土壤颗粒上，例如粘土和土壤有机材料，这些颗粒最容易受到风蚀的影响并有助于异地人群的吸入暴露。我们使用基于美国环境保护局 (EPA) 的协议，针对整个土壤和细土部分 (直径 <45微米)，测量了LANL两个相邻的半干旱森林站点土壤中铀的Kd。EPA协议中指定的7-d Kd值的范围为整个土壤的g-1为276-508 mL，而细土部分的g-1为615-2249 mL。出乎意料的是，为测试土壤溶液交换平衡而测得的30 d Kd值是7-d值的两倍以上。使用2组分 (快速和慢速) 指数模型得出溶液中238U对土壤的吸附率。我们发现LANL采样点之间，整个土壤和细土之间以及7-d和30d Kd测量值之间的Kd值存在显着差异。土壤之间的土壤溶液交换动力学和土壤大小的显着变化促进了使用特定地点的数据来估算环境迁移速率，并暗示了从土壤到溶液 (例如，进入地下水或肺液) 的解吸速率可能存在差异。我们还探讨了风蚀，土壤特征和Kd值之间的潜在关系。结合起来，我们的结果强调了需要对土壤溶液分配动力学进行更好的机械理解，以进行准确的风险评估。

BACKGROUND & AIMS: OBJECTIVE:Bone loss and periosteal expansion is found after menopause. The accelerated early postmenopausal bone loss is not permanent but if the same accounts for the periosteal expansion is unknown. METHODS:Bone mineral density (BMD) and skeletal structure of the distal forearm were followed from menopause and on average 24 years (range 18-28) by single-photon absorptiometry at 12 occasions in a population-based sample of 81 Caucasian women with no medication or disease affecting bone metabolism. A Strength Index based on areal BMD and bone structure was calculated. Postmenopausal serum-estradiol levels and incident distal radius fractures were registered. Data are presented as means with 95% confidence interval (95% CI). RESULTS:The annual BMD loss in three periods, 0-8, 8-16 and 16-28 years after menopause, was 2.0% (1.6, 2.4), 1.0% (0.6, 1.4) and 1.0% (0.7, 1.3), respectively. The annual periosteal expansion was 1.0% (0.8, 1.3), 0.0% (-0.3, 0.3) and 0.0% (-0.2, 0.2), respectively. Mean post-menopausal oestrogen levels correlated moderately with annual loss in aBMD (r=0.51, p<0.001) but less with the annual changes in bone width (r= -0.22, p=0.06). CONCLUSION:Postmenopausal periosteal expansion in the distal forearm seems to occur only in the first postmenopausal decade.

背景与目标：

BACKGROUND & AIMS: :Samples sizes are calculated for case-control studies where 1:1 matching has been employed, and where the goal is the interval estimation of the odds ratio. The optimal sample size is defined to be the smallest value for which a 100(1 - alpha)% confidence interval for the log odds ratio will not exceed a specified width 2 delta with specified probability (1 - gamma). This approach is similar in spirit to the power-based approach for sample size determination when significance testing is the goal. Tables of sample sizes are presented for various choices of parameters. We also find considerable disagreement with a published method based on expected numbers of discordant pairs.

背景与目标： : 为案例对照研究计算样本大小，其中采用了1:1匹配，目标是比值比的区间估计。最佳样本量被定义为最小值，对数优势比的100(1-α) % 置信区间将不超过具有指定概率 (1-γ) 的指定宽度2增量。当显著性测试是目标时，这种方法在精神上类似于基于功率的方法来确定样本量。给出了各种参数选择的样本大小表。我们还发现，基于不一致对的预期数量，与已发布的方法存在很大分歧。

BACKGROUND & AIMS: :It is not known how the volume of the cell nucleus is set, nor how the ratio of nuclear volume to cell volume (N/C) is determined. Here, we have measured the size of the nucleus in growing cells of the budding yeast Saccharomyces cerevisiae. Analysis of mutant yeast strains spanning a range of cell sizes revealed that the ratio of average nuclear volume to average cell volume was quite consistent, with nuclear volume being approximately 7% that of cell volume. At the single cell level, nuclear and cell size were strongly correlated in growing wild-type cells, as determined by three different microscopic approaches. Even in G1-phase, nuclear volume grew, although it did not grow quite as fast as overall cell volume. DNA content did not appear to have any immediate, direct influence on nuclear size, in that nuclear size did not increase sharply during S-phase. The maintenance of nuclear size did not require continuous growth or ribosome biogenesis, as starvation and rapamycin treatment had little immediate impact on nuclear size. Blocking the nuclear export of new ribosomal subunits, among other proteins and RNAs, with leptomycin B also had no obvious effect on nuclear size. Nuclear expansion must now be factored into conceptual and mathematical models of budding yeast growth and division. These results raise questions as to the unknown force(s) that expand the nucleus as yeast cells grow.

背景与目标： : 尚不知道如何设置细胞核的体积，也不知道如何确定核体积与细胞体积的比率 (N/C)。在这里，我们测量了发芽酵母酿酒酵母生长细胞中核的大小。对跨越一系列细胞大小的突变酵母菌株的分析表明，平均核体积与平均细胞体积的比率相当一致，核体积约为细胞体积的7%。在单细胞水平上，由三种不同的显微镜方法确定，在生长的野生型细胞中，核和细胞大小密切相关。即使在G1-phase中，核体积也有所增长，尽管它的增长速度不如整体细胞体积快。DNA含量似乎对核大小没有任何直接的直接影响，因为核大小在S期没有急剧增加。维持核大小不需要连续生长或核糖体生物发生，因为饥饿和雷帕霉素治疗对核大小几乎没有直接影响。除其他蛋白质和rna外，用letomycin B阻止新的核糖体亚基的核输出也对核大小没有明显影响。现在必须将核扩张纳入发芽酵母生长和分裂的概念和数学模型中。这些结果引起了人们对随着酵母细胞生长而扩大细胞核的未知力的质疑。

BACKGROUND & AIMS: BACKGROUND:Cystatin C is a low-molecular-weight protein that is freely filtered by the glomerulus and catabolized after reabsorption by the proximal tubular cells in healthy subjects. Urinary cystatin C is a potential biomarker for tubular damage including acute kidney injury (AKI) in the acute phase when patients are submitted to the intensive care unit. METHODS:The aim of this study was to perform a method validation of urinary analysis of cystatin C by particle-enhanced turbidimetric immunoassay (PETIA) on a high-throughput chemical analyzer. Total assay time was 10 min. The antigen excess, linearity, lower limit of quantification (LoQ), recovery, assay precision, stability, and interference caused by hemoglobin were evaluated. RESULTS:The LoQ was calculated to 0.020 mg/l with a coefficient of variation (CV) ≤ 10%. No hook effect was observed and the assay was linear over the studied interval less than 0.020-0.950 mg/l with a regression of R² = 0.9994. The assay had a recovery between 93-100% and the assay precision had a total CV of less than 3.5%. Cystatin C was stable for 3 days in room temperature and 14 days in +4C. The assay did not show any major interference with hemoglobin at a hemoglobin concentration of 10 g/L. The reference interval for urine cystatin C was less than 0.166 mg/l. CONCLUSION:The urinary cystatin C PETIA showed good precision and performance characteristics including short test turnaround times that are necessary qualifications for a biomarker at a routine laboratory.

背景与目标：

BACKGROUND & AIMS: :Previously, expected satiety (ES) has been measured using software and two-dimensional pictures presented on a computer screen. In this context, ES is an excellent predictor of self-selected portions, when quantified using similar images and similar software. In the present study we sought to establish the veracity of ES as a predictor of behaviours associated with real foods. Participants (N=30) used computer software to assess their ES and ideal portion of three familiar foods. A real bowl of one food (pasta and sauce) was then presented and participants self-selected an ideal portion size. They then consumed the portion ad libitum. Additional measures of appetite, expected and actual liking, novelty, and reward, were also taken. Importantly, our screen-based measures of expected satiety and ideal portion size were both significantly related to intake (p<.05). By contrast, measures of liking were relatively poor predictors (p>.05). In addition, consistent with previous studies, the majority (90%) of participants engaged in plate cleaning. Of these, 29.6% consumed more when prompted by the experimenter. Together, these findings further validate the use of screen-based measures to explore determinants of portion-size selection and energy intake in humans.

背景与目标： : 以前，已使用软件和计算机屏幕上显示的二维图片来测量预期的饱腹感。在这种情况下，当使用相似的图像和相似的软件进行量化时，ES是自选部分的出色预测因子。在本研究中，我们试图建立ES的准确性，作为与真实食物相关的行为的预测指标。参与者 (N = 30) 使用计算机软件评估他们的ES和三种熟悉食物的理想部分。然后提出了一碗真正的一种食物 (面食和酱汁)，参与者自行选择了理想的份量。然后，他们随意消费该部分。还采取了其他食欲，预期和实际喜好，新颖性和奖励措施。重要的是，我们基于屏幕的预期饱腹感和理想份量的测量都与摄入量显着相关 (p<.05)。相比之下，喜好的度量指标相对较差 (p>.05)。此外，与先前的研究一致，大多数 (90%) 参与者从事板材清洁。其中，当实验者提示时，29.6% 消耗更多。总之，这些发现进一步验证了使用基于屏幕的措施来探索人体部分大小选择和能量摄入的决定因素。

BACKGROUND & AIMS: :There is an unresolved debate in the scientific community about the shape of the quasistatic displacement pulse produced by nonlinear acoustic wave propagation in an elastic solid with quadratic nonlinearity. Early analytical and experimental studies suggested that the quasistatic pulse exhibits a right-triangular shape with the peak displacement of the leading edge being proportional to the length of the tone burst. In contrast, more recent theoretical, analytical, numerical, and experimental studies suggested that the quasistatic displacement pulse has a flat-top shape where the peak displacement is proportional to the propagation distance. This study presents rigorous mathematical analyses and numerical simulations of the quasistatic displacement pulse. In the case of semi-infinite solids, it is confirmed that the time-domain shape of the quasistatic pulse generated by a longitudinal plane wave is not a right-angle triangle. In the case of finite-size solids, the finite axial dimension of the specimen cannot simply be modeled with a linear reflection coefficient that neglects the nonlinear interaction between the combined incident and reflected fields. More profoundly, the quasistatic pulse generated by a transducer of finite aperture suffers more severe divergence than both the fundamental and second order harmonic pulses generated by the same transducer.

背景与目标： : 关于在具有二次非线性的弹性固体中由非线性声波传播产生的准静态位移脉冲的形状，科学界存在尚未解决的争论。早期的分析和实验研究表明，准静态脉冲呈直角三角形，前缘的峰值位移与音调爆发的长度成正比。相反，最近的理论，分析，数值和实验研究表明，准静态位移脉冲具有平顶形状，其中峰值位移与传播距离成正比。这项研究对准静态位移脉冲进行了严格的数学分析和数值模拟。在半无限固体的情况下，证实了由纵向平面波产生的准静态脉冲的时域形状不是直角三角形。在有限尺寸固体的情况下，不能简单地使用线性反射系数来建模样品的有限轴向尺寸，该线性反射系数忽略了组合入射场和反射场之间的非线性相互作用。更深刻地说，由有限孔径的换能器产生的准静态脉冲比由同一换能器产生的基波和二阶谐波脉冲遭受更严重的发散。

BACKGROUND & AIMS: :Intra-group social stability is important for the long-term productivity and health of social organisms. We evaluated the effect of group size on group stability in the face of repeated social perturbations using a cooperatively breeding fish, Neolamprologus pulcher In a laboratory study, we compared both the social and physiological responses of individuals from small versus large groups to the repeated removal and replacement of the most dominant group member (the breeder male), either with a new male (treatment condition) or with the same male (control condition). Individuals living in large groups were overall more resistant to instability but were seemingly slower to recover from perturbation. Members of small groups were more vulnerable to instability but recovered faster. Breeder females in smaller groups also showed greater physiological preparedness for instability following social perturbations. In sum, we discover both behavioral and physiological evidence that living in larger groups helps to dampen the impacts of social instability in this system.

背景与目标： : 群体内部社会稳定对社会有机体的长期生产力和健康至关重要。在实验室研究中，我们使用合作繁殖的鱼类Neolamprologus pulcher评估了面对反复社会扰动的群体规模对群体稳定性的影响，我们比较了小组和大组个体的社会和生理反应，以及大多数优势组成员 (育种者男性) 的反复移除和替换，无论是新的男性 (治疗条件) 还是相同的男性 (控制条件)。总体而言，生活在大群体中的个体对不稳定的抵抗力更强，但从扰动中恢复的速度似乎较慢。小团体的成员更容易受到不稳定的影响，但恢复得更快。较小群体的育种者雌性在社会扰动后也表现出更大的生理准备，以应对不稳定。总而言之，我们发现了行为和生理证据，表明生活在较大的群体中有助于减轻该系统中社会不稳定的影响。

BACKGROUND & AIMS: OBJECTIVES:We aimed to establish which of sitting height (SH) and total height (Ht) is most appropriately used in the scaling of adult body mass (BM), waist circumference (WC), and forced vital capacity (FVC), considering likely explanations and proposing a suitable index for each. METHODS:Data were from the US Third National Health and Nutrition Survey for white and black American women and men aged 20 to 50 years. Statistical analysis involved mainly correlation coefficients, the multiple regression of BM, WC, or FVC on SH and leg length (LL), and fitting of allometric regression equations relating each of BM, WC, and FVC to SH or Ht. RESULTS:BM and WC correlated more strongly with SH than with Ht, and FVC correlated more strongly with Ht. Associations with LL were negative for WC, negative or nonsignificant for BM, and positive for FVC. Using round-number exponents for Ht and SH, the allometric relationships indicated that appropriate indices are BM/SH3 , WC/SH, and FVC/Ht2 . CONCLUSIONS:Contrary to usual practice, BM and WC are better scaled in relation to SH than to Ht. FVC is slightly better scaled in relation to Ht, as is conventional. Interpretations involve the small influence of LL on BM and the influence both of gluteo-femoral fatness on measured SH and of childhood health and nutrition on adult LL, WC, and FVC. It is evident that SH should be measured more often for research purposes.

背景与目标：

BACKGROUND & AIMS: PURPOSE:Quantitative relationships between treatment-induced changes in tumor size and circulating tumor cell (CTC) counts, and their links to overall survival (OS), are lacking. We present a population modeling framework identifying and quantifying such relationships, based on longitudinal data collected in patients with metastatic colorectal cancer (mCRC) to evaluate the value of tumor size and CTC counts as predictors of OS. EXPERIMENTAL DESIGN:A pharmacometric approach (i.e., population pharmacodynamic modeling) was used to characterize the changes in tumor size and CTC count and evaluate them as predictors of OS in 451 patients with mCRC treated with chemotherapy and targeted therapy in a prospectively randomized phase III study (CAIRO2). RESULTS:A tumor size model of tumor quiescence and drug resistance was used to characterize the tumor size time-course, and was, in addition to the total normalized dose (i.e., of all administered drugs) in a given cycle, related to the CTC counts through a negative binomial model (CTC model). Tumor size changes did not contribute additional predictive value when the mean CTC count was a predictor of OS. Treatment reduced the typical mean count from 1.43 to 0.477 (HR = 3.94). The modeling framework was applied to explore whether dose modifications (increased and reduced) would result in a CTC count below 1/7.5 mL after 1 to 2 weeks of treatment. CONCLUSIONS:Time-varying CTC counts can be useful for early predicting OS in patients with mCRC, and may therefore have potential for model-based treatment individualization. Although tumor size was connected to CTC, its link to OS was weaker.

背景与目标：

BACKGROUND & AIMS: The signal recognition particle (SRP) controls the transport of secretory proteins into and across lipid bilayers. SRP-like ribonucleoprotein complexes exist in all organisms, including plants. We characterized the rice SRP RNA and its primary RNA binding protein, SRP19. The secondary structure of the rice SRP RNA was similar to that found in other eukaryotes; however, as in other plant SRP RNAs, a GUUUCA hexamer sequence replaced the highly conserved GNRA-tetranucleotide loop motif at the apex of helix 8. The small domain of the rice SRP RNA was reduced considerably. Structurally, rice SRP19 lacked two small region that can be present in other SRP19 homologues. Conservative structure prediction and site-directed mutagenesis of rice and human SRP19 polypeptides indicated that binding to the SRP RNAs occurred via a loop that is present in the N-domain of both proteins. Rice SRP19 protein was able to form a stable complex with the rice SRP RNA in vitro. Furthermore, heterologous ribonucleoprotein complexes with components of the human SRP were assembled, thus confirming a high degree of structural and functional conservation between plant and mammalian SRP components.

背景与目标： 信号识别颗粒 (SRP) 控制分泌蛋白进入脂质双层和跨脂质双层的运输。SRP样核糖核蛋白复合物存在于所有生物中，包括植物。我们表征了水稻SRP RNA及其主要RNA结合蛋白srp19。水稻SRP RNA的二级结构与其他真核生物相似; 然而，与其他植物SRP RNA一样，GUUUCA六聚体序列取代了螺旋8顶点处高度保守的GNRA-四核苷酸环基序。水稻SRP RNA的小结构域大大减少。从结构上讲，水稻SRP19缺少其他SRP19同源物中可能存在的两个小区域。水稻和人SRP19多肽的保守结构预测和定点诱变表明，与SRP rna的结合是通过两种蛋白质的N域中都存在的环发生的。水稻SRP19蛋白能够与水稻SRP RNA在体外形成稳定的复合物。此外，还组装了具有人类SRP成分的异源核糖核蛋白复合物，从而证实了植物和哺乳动物SRP成分之间高度的结构和功能保守性。

BACKGROUND & AIMS: BACKGROUND:Necropsy studies demonstrate that coronary artery disease (CAD) is frequently complex and eccentric. However, angiography provides only a silhouette of the vessel lumen. Intravascular ultrasound is a new tomographic imaging method for evaluation of coronary dimensions and wall morphology. Few data exist regarding intravascular ultrasound in patients with CAD, and no data exist for subjects with normal coronaries. METHODS AND RESULTS:We used a multielement 5.5F, 20-MHz ultrasound catheter to examine eight normal subjects and 43 patients with CAD. We assessed the safety of coronary ultrasound and the effect of vessel eccentricity on comparison of minimum luminal diameter by angiography and ultrasound. Normal and atherosclerotic wall morphology and stenosis severity were also evaluated by intravascular ultrasound. The only untoward effect was transient coronary spasm in five patients. At 33 sites in normal subjects, the lumen was nearly circular, yielding a close correlation between angiographic and ultrasonic minimum diameter (r = 0.92). At 90 sites in patients with CAD, ultrasound demonstrated a concentric cross section; correlation was also close (r = 0.93). However, at 72 eccentric sites, correlation was not as close (r = 0.77). For 41 stenoses, correlation between angiography and ultrasound for area reduction was moderate (r = 0.63). In normal subjects, wall morphology revealed a thin (0.30 mm or less) intimal leading edge and subadjacent sonolucent zone (0.20 mm or less). Patients with CAD exhibited increased thickness and echogenicity of the leading edge, thickened sonolucent zones, and/or attenuation of ultrasound transmission. CONCLUSIONS:These data establish that intravascular ultrasound is feasible and safe and yields luminal measurements that correlate generally with angiography. Differences between angiographic and ultrasound measures of lumen size in eccentric vessels probably reflect the dissimilar perspectives of tomographic and silhouette imaging techniques. Intravascular ultrasound provides detailed images of normal and abnormal wall morphology not previously possible in vivo.

背景与目标：

BACKGROUND & AIMS: STUDY OBJECTIVE:The aim was to demonstrate the ability of diltiazem to protect the ischaemic myocardium in the course of coronary reperfusion, and to establish if an interaction with neutrophils is implied. DESIGN:Ischaemia was induced by occluding the left anterior descending coronary artery for 90 min followed by 6 h of reperfusion with a residual critical stenosis left in place. Three groups were studied: group 1 (control) received a saline perfusion; group 2 was given a bolus injection of 400 micrograms.kg-1 of diltiazem 10 min before reperfusion, followed by 4 micrograms.kg-1.min-1 perfusion until termination of experiment; group 3 was made neutropenic by injecting a neutrophil antiserum produced in rabbits and was then treated with diltiazem, as in the second group. SUBJECTS:60 mongrel dogs of either sex were allocated at random into one of the three groups the day before the experiment. MEASUREMENTS AND MAIN RESULTS:Diltiazem plasma concentrations ranged from 68.6(SEM 10.0) to 102.5(15.2) micrograms.litre-1 during the study. Transmural collateral blood flow, measured with 153Gd microspheres 15 min after occlusion, and area at risk, evaluated by Evans blue perfusion, did not differ among the three groups. Infarct size, estimated by triphenyltetrazolium staining of heart slices and expressed as a percentage of area at risk, was less (p less than 0.05) in the diltiazem [20.5(5.2)%] and diltiazem plus neutropenia [17.6(5.4)%] groups compared to controls [39.8(6.9)%] but neutropenia added no significant benefit to diltiazem alone. The animals treated with diltiazem alone had lower serum creatine kinase levels than controls, at 5719(891) v 14,333(2885) IU.litre-1, p less than 0.05. The neutrophilia seen in controls was virtually absent in diltiazem dogs. Myocardial neutrophil accumulation estimated by scintigraphy of 111In labelled autologous neutrophils was much less in diltiazem than in control dogs, at 3948(1228) v 11,021(2081) 111In-neutrophil.g-1 of infarct, p less than 0.02. CONCLUSIONS:Diltiazem given during reperfusion reduces infarct size by a mechanism that includes an inhibition of neutrophil accumulation in the post-ischaemic myocardium.

背景与目标：

BACKGROUND & AIMS: BACKGROUND:Calcium may be mobilized from the maternal skeleton during pregnancy, which may be influenced by several factors. OBJECTIVE:The objective was to investigate changes in bone mineral status and size during pregnancy and to consider the influences of body weight and calcium intake. DESIGN:Thirty-four British women were studied before pregnancy and 2 wk postpartum (Preg). Eighty-four nonpregnant, nonlactating (NPNL) women were studied over a corresponding time. Bone mineral content (BMC), bone area (BA), areal bone mineral density (aBMD), and BA-adjusted BMC of the whole-body, lumbar spine, radius, and hip were measured by dual-energy X-ray absorptiometry. RESULTS:The Preg group experienced significant decreases in BMC, aBMD, and BA-adjusted BMC at the whole-body, spine, and total hip of between 1% and 4%. Whole-body BMC increased in the NPNL group, and aBMD and BA-adjusted BMC decreased at the spine and hip by 0.5% to 1%. Whole-body BMC decreased in the Preg group by -2.16 +/- 0.46%, equivalent to -2.71 +/- 0.43% relative to the NPNL group (P < or = 0.001). Weight change was a positive predictor of skeletal change at the spine, hip, and radius in both groups. Differences between the Preg and NPNL groups in change in BA-adjusted BMC, after correction for weight change and other influences, were as follows (P < or = 0.01): whole-body, -1.70 +/- 0.25%; spine, -3.03 +/- 0.72%; and total hip, -1.87 +/- 0.60%. Calcium intake was not a significant predictor of skeletal change in either group. CONCLUSIONS:Pregnancy is associated with decreases in whole-body and regional bone mineral status sufficient to make a sizeable contribution to maternal and fetal calcium economy. Calcium intake is not a significant predictor of the skeletal response to pregnancy in well-nourished women.

背景与目标：

BACKGROUND & AIMS: :Brief exposure to moderate intensity static magnetic fields has been shown to produce a transient alteration in physiological function in a variety of biological systems, primarily those related to changes in intracellular Ca(2+). In the present study GH3 cells were cultured during continuous exposure to a 0.5 T field, for periods of up to 5 weeks. Following a 1-week exposure, cell growth declined by 22% and returned to control levels in 1 week. This was not statistically significant but, with a 4-week exposure, a statistically significant decline in growth of 51% was observed and return to control levels did not occur for 4 weeks. Cell diameter, on the other hand, significantly increased following 3 weeks of exposure and did not return to control levels for 3 weeks after termination of exposure. Ca(2+)-dependent changes in the dynamic reorganization of the actin cytoskeleton are suggested as the probable explanation for these observations.

背景与目标： : 已显示，短暂暴露于中等强度的静态磁场会在各种生物系统中产生生理功能的瞬时改变，主要是与细胞内Ca(2) 变化有关的那些改变。在本研究中，在连续暴露于0.5 T场期间培养GH3细胞长达5周。暴露1周后，细胞生长下降22%，并在1周内恢复到对照水平。这在统计学上并不显着，但是在暴露4周的情况下，观察到51% 的生长在统计学上显着下降，并且在4周内未恢复到对照水平。另一方面，暴露3周后细胞直径显着增加，并且在暴露终止后3周内未恢复到对照水平。建议将肌动蛋白细胞骨架动态重组中的Ca(2) 依赖性变化作为这些观察结果的可能解释。