Comparison of SVD methods to extract the foetal electrocardiogram from cutaneous electrode signals

The paper presents and compares three methods making use of the singular value decomposition (SVD) of a matrix to extract the foetal electrocardiogram (FECG) from cutaneously recorded electrode signals. The first method constructs a set of orthogonal foetal signals (the so-called principal foetal signals) from the recordings, but needs electrode positions far from the foetal heart, in addition to the abdominal electrodes that pick up a mixture of maternal and foetal electrocardiogram. An online adaptive algorithm has been developed such that a real-time implementation becomes feasible. The second method is a new online approach to a technique presented by van Oosterom. Although this method has some important drawbacks and is suboptimal as far as foetal signal-to-noise ratio is concerned. it is still very useful when only a foetal trigger is required, as the signal obtained is not a complete FECG, Finally, a third method is proposed, based on the generalised SVD and interpreted with the new concept of oriented signal-to-signal ratio. An online version is also presented for this method and some results are shown.     

Low rank updated LS-SVM classifiers for fast variable selection

Least squares support vector machine (LS-SVM) classifiers are a class of kernel methods whose solution follows from a set of linear equations. In this work we present low rank modifications to the LS-SVM classifiers that are useful for fast and efficient variable selection. The inclusion or removal of a candidate variable can be represented as a low rank modification to the kernel matrix (linear kernel) of the LS-SVM classifier. In this way, the LS-SVM solution can be updated rather than being recomputed, which improves the efficiency of the overall variable selection process. Relevant variables are selected according to a closed form of the leave-one-out (LOO) error estimator, which is obtained as a by-product of the low rank modifications. The proposed approach is applied to several benchmark data sets as well as two microarray data sets. When compared to other related algorithms used for variable selection, simulations applying our approach clearly show a lower computational complexity together with good stability on the generalization error.     

Photodynamic sterilization of red cells and its effect on contaminating white cells: viability and mechanism of cell death

BACKGROUND: Phthalocyanines are useful sensitizers for photodynamic sterilization of red cell concentrates. Various lipid-enveloped viruses can be inactivated with only limited red cell damage. Because white cells are involved in the immunomodulatory effects of blood transfusions, the study of the effect of photodynamic treatment on these cells is imperative. STUDY DESIGN AND METHODS: White cell-enriched red cell suspensions were photodynamically treated with either the hydrophobic Pc4 (HOSiPcOSi-(CH3)2(CH2)3N(CH3)2) or water-soluble aluminum phthalocyanine tetrasulfonate (AIPCS4) under virucidal conditions. Viability of white cell subpopulations on Days 0, 1, and 4 after treatment was determined by fluorescence-activated cell sorting by flow cytometric analysis of propidium iodide uptake. Apoptosis induction was studied by DNA ladder formation and staining for an early marker of apoptosis (annexin V). RESULTS: Treatment with Pc4 causes a significant decrease in cell viability of all white cells, as shown by prodidium iodide uptake. Monocytes and granulocytes are the most sensitive, and lymphocytes are relatively more resistant. Some of the cells die by apoptosis, which is induced within 30 minutes after treatment. Treatment with AIPCS4 damages only monocytes; other cell populations are not affected. CONCLUSIONS: Physicochemical properties of the photosensitizers partly determine their effect on white cells. Differences in intracellular localization are likely to be responsible for the effects observed.     

Small airway disease: comparison of tests in young smokers versus nonsmokers

A number of new tests for detection of small airway disease have been developed in the past several years. It is hoped that these will prove valuable as screening tests to detect those at risk of developing obstructive airway disease. We obtained data on the degree of discrimination of single breath nitrogen studies (CV/VC, CC/TLC, deltaN2/L), air-He studies (Vmax50), and the maximal midexpiratory flow (FEF25-75%) in detecting abnormalities in young smokers. Only the CV/VC and CC/TLC significantly separated smokers from nonsmokers, each revealing 20% abnormal values in smokers.     

Blood Group Chimerism as a Clue to Generalized Tissue Mosaicism

Blood group studies disclosed mosaicism of the red cells in a healthy male Negro donor who was subsequently also found to have mosaicism of skin and bone marrow with respect to XX-XY chromosomal constitution and whose skin showed unequal pigmentation. The two red cell populations were unequal in numbers with a ratio of approximately 10:1. The major population was group A, Jk^a negative and showed the sickling trait in wet films and by electrophoresis. The minor population was group B, Jk^a positive, did not sickle and contained only hemoglobin A. Both red cells were Le^a positive despite the fact that the propositus was a secretor. However, only A substance was secreted and it was demonstrated by salivary studies and with the help of complete family studies, that the minor genetic product which had produced the group B erythrocytes represented the gene contribution se se and was the source of Le^a substance sufficient to coat both red cell populations. The family studies showed that the propositus had received a 2 allele contribution from each parent and was therefore the result of double fertilization of a double egg nucleus presumably an ovum and a polar body.     

骨髓单个核细胞移植对心肌修复相关因子的调节作用

目的:干细胞移植后可以通过分化为心肌细胞、减少心肌重构等方面发挥改善心功能的作用。观察急性心肌梗死后进行骨髓单个核细胞移植对相关细胞因子的调节作用,探讨干细胞发挥改善心脏重构的可能机制。方法:实验于2006-01/2007-02在福建省高血压研究所完成。①实验材料:清洁级SD大鼠由上海实验动物公司提供。②实验方法:取SD大鼠骨髓,分离出单个核细胞,以DAPI标记骨髓单个核细胞。取体质量200～250g雄性SD大鼠24只,建立急性心肌梗死模型后,随机分为2组,实验组从股静脉注入同种异体大鼠骨髓单个核细胞1.0×107,对照组注入等量的生理盐水。③实验评估:于移植后4周采用免疫组组织化学法检测DAPI阳性细胞、肌钙蛋白阳性细胞、基质细胞源性因子1、转化生长因子β及大鼠心功能改变。结果:24只大鼠均进入结果分析。移植后4周实验组基质细胞源性因子1表达较对照组明显升高,转化生长因子β表达较对照组下降;实验组在免疫荧光显微镜下可观察到DAPI和肌钙蛋白阳性细胞,心功能较对照组明显改善。结论:骨髓单个核细胞移植改善急性心肌梗死大鼠心功能的同时伴有基质细胞源性因子1表达增加及转化生长因子β表达下降。     

Free intracellular Ca2+ concentration and growth hormone (GH) release from purified rat somatotrophs. III. Mechanism of action of GH-releasing factor and somatostatin.

GH-releasing factor (GRF)-stimulated GH release is dependent on a biphasic increase in free intracellular Ca2+ concentration [( Ca2+]i), resulting from an influx of Ca2+ into somatotrophs, while the inhibitory action of somatostatin (SRIF) on basal and GRF-induced GH release results from its ability to lower [Ca2+]i by inhibiting Ca2+ influx. This study was carried out to investigate the mechanism by which GRF and SRIF regulate [Ca2+]i to control GH release. The roles of ion channels, cAMP-dependent processes, and protein kinase-C (PKC) were investigated by measuring changes in [Ca2+]i, 45Ca influx, and GH release when purified rat somatotrophs were exposed to high K+, cAMP analogs, prostaglandin E2, as well as the PKC activators 1,2-dioctanoyl-glycerol and phorbol 12-myristate 13-acetate. High K+ depolarization produced a rapid and transient increase in [Ca2+]i, while cAMP and prostaglandin E2 led to a sustained elevated [Ca2+]i. PKC activators produced a transient increase in [Ca2+]i, followed by a decrease to below baseline. All secretagogues tested raised [Ca2+]i by stimulating Ca2+ influx through L-type voltage-sensitive Ca2+ channels (VSCC), since the increases in [Ca2+]i were blocked by incubation in Ca2(+)-free medium and by the dihydropyridine Ca2+ antagonist nifedipine. SRIF lowered [Ca2+]i by blocking the Ca2+ influx stimulated by all of these GH secretagogues except high K+. These results are consistent with the model in which GRF initiates its action by increasing Na+ conductance to depolarize the somatotroph via cAMP. This depolarization would stimulate Ca2+ influx through VSCC, which would result in the first phase of the GRF-dependent increase in [Ca2+]i. This increase in [Ca2+]i would stimulate Ca2+ removal from the cytosol by activating Ca-ATPase via Ca-calmodulin and/or PKC. This would result in the lowering of [Ca2+]i to the plateau level of the second phase of the GRF response. SRIF prevents the GRF-induced increase in [Ca2+]i by increasing K+ conductance and, thus, hyperpolarizing the cell. Hyperpolarization would close VSCC, leading to a decrease in Ca2+ influx, with a subsequent drop in [Ca2+]i.     

The effect of anticonvulsant therapy on serum levels of 25-hydroxy-vitamin D, calcium, and parathyroid hormone.

In 20 female patients treated for 2 to 37 years (mean :12) with anticonvulsant drugs, low serum levels of 25-hydroxy-vitamin D (25-OH-D; 6.4 +/- 3.2 ng/ml M +/- SD), relative hypocalcemia (9.2 +/- 0.4 mg/100 ml) and high levels of parathyroid hormone (PTH 277 +/- 165 pg/ml) were found compared to an age-matched control group (respectively 8.6 +/- 3.2 ng/ml, 9.6 +/- 0.3 mg/100 ml and 183 +/- 95 pg/ml) living in the same psychiatric clinic. A significant negative correlation was found between total duration of treatment and either serum 25-OH-D or serum calcium. After treatment with an oral vitamin D3 supplement (2000 IU/day) for 3 weeks, the serum 25-OH-D levels, although increased, remained lower than normal in the epileptic group and neither hypocalcemia nor their secondary hyperparathyroidism were corrected. These data confirm the occurrence of vitamin D deficiency in patients treated with anticonvulsant drugs resulting in hypocalcemia and secondary hyperparathyroidism.