Augmented Inverse Probability Weighted Estimator for Cox Missing Covariate Regression

This article investigates an augmented inverse selection probability weighted estimator for Cox regression parameter estimation when covariate variables are incomplete. This estimator extends the Horvitz and Thompson (1952, Journal of the American Statistical Association 47, 663-685) weighted estimator. This estimator is doubly robust because it is consistent as long as either the selection probability model or the joint distribution of covariates is correctly specified. The augmentation term of the estimating equation depends on the baseline cumulative hazard and on a conditional distribution that can be implemented by using an EM-type algorithm. This method is compared with some previously proposed estimators via simulation studies. The method is applied to a real example.     

Membrane destabilizations supporting electropermeabilization

The cell membrane can be permeabilized when subjected to calibrated short electric pulses. This membrane alteration can be reversible, leaving cell viability unaffected. This set of events is called Electropermeabilization. This is now used in clinical applications to introduce hydrophilic drugs into the cytoplasm. While an empirical control of the electrical parameters is obtained, our knowledge of the molecular mechanisms supporting the membrane alteration is very limited. This paper gives a critical review of the limits of the models which are proposed by taking into account the different experimental approaches.     

A procedure for differential staining of cartilage and bone in whole formalin-fixed vertebrates.

This paper describes a modification of the Simons and Van Horn (1971) procedure for rendering cartilage blue, bone red, and soft tissue translucent or transparent in whole vertebrate specimens. Alcian blue and alizarin red S are used to stain cartilage and bone respectively. In our procedure formalin is used as a fixative. This is a significant modification because formalin is the common fixative for museum specimens. This clearing and staining procedure is thus readily applicable to comparative studies in anatomy, embryology and systematic zoology.     

Molecular forms of human growth hormone (HGH) secreted by cultured fetal pituitary cells]

Cultures of foetal human pituitary cells excrete and synthetize different molecular forms of proteins with HGH immunological activity. These cells incorporate tritiated-leucine in these proteins. Gel chromatography on sephadex using different length of column allow us to separate: One form excluded in front of the dead volume and which has a high molecular weight. This form is not dissociated by treatment with urea 8 M, guanidine 6 M and dithiothreitol. Nor this form is modified by treatment by ribonuclease. One form excluded within the dead volume and which is probably a dimere. This form is no more modified by the different treatments. One form which is excluded like a monomere--it is the more important form--. This form is dissociated in fragments of lower molecular weight by urea 8 M. This dissociation is partially reversible by dialysis.     

广西南宁盆地的脊椎动物化石及下第三系

<正> 南宁盆地脊椎动物化石地点目前所知不下七处。本文着重记述了1974和1979年笔者采自邕宁县五塘公社莲塘村的石炭兽化石,并对盆地东部下第三系作一初步划分。本文首次报道南宁盆地发现脊椎动物化石,对研究石炭兽的演化、发展和分布,对盆地第三系地层的划分和对比,提供了新的依据。一、化石地点及地层概况莲塘村位于南宁市东北约32公里、五塘圩东5公里、邕宾(南宁—宾阳)公路南侧。石炭兽化石产于莲塘村东约300米远的小煤窑、距地表8.3米深的褐煤层顶板(灰色泥质粉砂岩)中。     

Substrate inhibition or activation kinetics of the beta-galactosidase from the extreme thermoacidophile archaebacterium Caldariella acidophila

The kinetics of the hydrolysis of p-nitrophenyl-beta-D-galactopyranoside (pNPG) by a thermophile, beta-galactosidase, was studied at different temperatures. This enzyme was isolated from the thermophilic microorganism archaebacterium Caldariella acidophila. The hydrolysis of pNPG by beta-galactosidase does not follow Michaelis-Menten law. This enzyme is inhibited by excess substrate at low temperatures and it is activated by excess substrate at high temperatures. A minimum mechanistic model is proposed to explain the behaviour. This model assumes the binding of an additional substrate molecule on the glycosidyl enzyme intermediate. This model is in good agreement with the postulated mechanism for beta-galactosidase from Escherichia coli. The kinetic parameters are calculated at six different temperatures.     

Crystallization kinetics of homopolymers: overall crystallization: a review

This paper is a brief review of the overall crystallization kinetics of synthetic homopolymers. The basic experimental results are presented and compared with theory that is currently available. It is found, surprisingly, that the more sophisticated theories do no better in explaining experimental results than does the free-growth approximation. This is contrary to what is observed for the crystallization of low molecular weight substances. The reason can be attributed to entanglements and other topological defects that are present in the pure melt and are relegated to the non-crystalline regions as crystallization progresses. This results in a more protracted crystallization than is predicted and is yet to be included in theory.     

Algamica: revisions to a key-based computerized counting program for free-living,attached, and benthic algae

A computerized counting program for algae and other microscopic bodies, named Algamica, is presented here. This program is a revised version of the original computer counting program of Hamilton published in 1990. This DOS-based software can enumerate all types of microscopic algae (i.e. phytoplankton, periphyton, diatoms), for which adequate expression of results are provided. Automated calculations of densities, biovolumes, surface areas and carbon biomass are available at the termination of each sample count. A simple counter for other micro-organisms is also available. A comprehensive guide manual file has been added to allow for a friendly first contact with the program and its options. This software conforms to current enumeration methodology. This version is available for PC computers, from website Algamica.ibelgique.com. Minimum required memory is 200 KB.     

Immunological study of a population of hemophiliacs treated with non-commercial fractions

We studied lymphocyte subpopulations, serum beta 2 microglobulin, and viral markers in 115 hemophiliacs who are followed and treated at our center. The only clinical or biological anomaly observed is hypergammaglobulinemia. This frequent finding is independent of hemophilia type and of the intensity of substitutive treatment. This group is characterized by the fact that the patients are treated only by locally prepared coagulation fractions, essentially cryoprecipitates for hemophiliacs A, and not containing any derivative of commercial origin. This series is compared to other recent reports, some of which present a high incidence of immunologic anomalies.     

Analysis of an east tennessee oak hickory forest by canonical correlation of species and environmental parameters

Summary A new multivariate analytical technique, canonical group correlation (CGC) is developed to correlate abiotic and biotic characterization of communities. This technique is applied to the plant communities of a 97.5 ha oak-hickory watershed. This analysis has validated inferences drawn in earlier studies which used only species data. We have concluded that the dominant factors discriminating the four distinct types of vegetation which exist in the region being studied are age and slope position. Slope position is inferred to be correlated with a moisture gradient. This information is depicted by the location of the four community types in two canonical spaces. One space is determined by vegetational parameters (species composition), the other by environmental parameters. A linear transformation between the two spaces is derived. This transformation can be used to predict successional development.Research supported by the Eastern Deciduous Forest Biome, US-IBP, funded by the National Sciences Foundation under Interagency Agreement AG-199, 40-193-69 with the Atomic Energy Commission, Oak Ridge National Laboratory. This is Contribution No. 291 from the Eastern Deciduous Forest Biome, US-IBP, and Publication No. 1054, Environmental Sciences Division, Oak Ridge National Laboratory.Nomenclature follows Little (1953).     

Conservation analysis in biochemical networks: computational issues for software writers

Large scale genomic studies are generating significant amounts of data on the structure of cellular networks. This is in contrast to kinetic data, which is frequently absent, unreliable or fragmentary. There is, therefore, a desire by many in the community to investigate the potential rewards of analyzing the more readily available topological data. This brief review is concerned with a particular property of biological networks, namely structural conservations (e.g. moiety conserved cycles). There has been much discussion in the literature on these cycles but a review on the computational issues related to conserved cycles has been missing. This review is concerned with the detection and characterization of conservation relations in arbitrary networks and related issues, which impinge on simulation simulation software writers. This review will not address flux balance constraints or small-world type analyses in any significant detail.     

Induction of DNA synthesis in isolated nuclei by cytoplasmic factors from spontaneously proliferating and mitogen-activated lymphoid cells

Cytoplasmic extracts, prepared from continuously proliferating lymphoblastoid cells, as well as mitogen-activated normal lymphocytes, contain an extractable factor capable of inducing DNA synthesis in isolated quiescent nuclei. This factor is not detectable in resting cells. It is nondialyzable, precipitable by 30-50% saturated ammonium sulfate, and inactivated by trypsin. It is heat sensitive, but stable to cold and lyophilization. The molecular weight of the factor is greater than 100,000. This cytoplasmic activator of nuclear DNA replication is not released from the cell, and has no effect on intact cells. This suggests that it serves as an intracellular mitogenic signal in replicating cells.     

A PAF-acetylhydrolase activity in Tetrahymena pyriformis cells

Our study provides evidence for the existence of an acylhydrolase activity in Tetrahymena pyriformis cells, capable of hydrolyzing the sn-2 ester bond of the PAF molecule. This activity is mainly distributed in the microsomal fraction (76.5% of total) and has properties similar to the mammalian PAF-acetylhydrolase since it is Ca(2+)-independent, acid-labile, is inhibited by DFP and PMSF but it is not affected by egg yolk phosphatidylcholine. This microsomal acylhydrolase has apparent Km and Vmax values of 1.56 microM and 373 pmols.mg.min respectively. This is the first report of the existence of a PAF-acetylhydrolase activity in a non-mammalian cell.     

Time Space Translation: A Hox Mechanism for Vertebrate A-P Patterning

The vertebrate A-P axis is a time axis. The head is made first and more and more posterior levels are made at later and later stages. This is different to the situation in most other animals, for example, in Drosophila. Central to this timing is Hox temporal collinearity (see below). This occurs rarely in the animal kingdom but is characteristic of vertebrates and is used to generate the primary axial Hox pattern using time space translation and to integrate successive derived patterns (see below). This is thus a different situation than in Drosophila, where the primary pattern guiding Hox spatial collinearity is generated externally, by the gap and segmentation genes.     

Lactate involvement in neuron-glia metabolic interaction: (13)C-NMR spectroscopy contribution

Glucose is commonly admitted to be the main substrate for brain energy requirement. However, it has been recently proposed that lactate, generated from glucose via glycolysis, would be the oxidative substrate for neurons, particularly during neuronal activation, according to a mechanism called the astrocyte-neuron lactate shuttle hypothesis (ANLSH). In that mechanism, glutamate released in the synaptic cleft during brain activation is taken up by astrocytes. This uptake, via the glutamate/Na(+) transporter, induces the entry of sodium, which is then excluded from the astrocytes via the Na(+)/K(+) ATPase. This exclusion consumes ATP, which stimulates glycolysis and thus lactate formation in astrocytes. This lactate is then transferred to neurons where it is utilized as oxidative substrate. This review tries to gather the recent evidences that support this hypothesis and presents the contribution of NMR to this matter.     

The Lakes Handbook, Volume II. Lake Restoration and Rehabilitation. Edited by P. E. O'Sullivan and C. S. Reynolds. Blackwell Science Ltd, Oxford, UK, 2005, 560 pp. ISBN 0-632-04795-X (hardback). {pound}125.00.

This is the second of a two-volume set, assembled from the contributionsof many authors. As is true of Volume I, many of the contributorsare luminaries, and the topical coverage is relatively comprehensive.This volume is divided into sections that treat regional studies,human impact on specific lake types, lake and catchment modelsand legal frameworks. Owing     

Fatigue estimation using a novel multi-fractal detrended fluctuation analysis-based approach

This paper presents a novel multi-fractal detrended fluctuation analysis-based approach for fatigue estimation. This approach exploits the statistical self-similarity and long-range correlation of surface electromyography signals at different time scales in which the myoelectric manifestation of fatigue is more significant compared to the influence of varying force, muscle length (joint angle), and innervation zone. This approach provides a fatigue index which outperforms the conventional median frequency during cyclic and random contractions. This type of analysis is promising an efficient framework for analysis of surface electromyography signals with several potential applications.     

Doing justice on two fronts: the liberal dilemma in immigration

Two hearts beat in every liberal breast. One is the heart of non-discrimination – the commitment to propounding equal chances for all. Such a principle, built around individuals and their free choices, ought to be applicable everywhere and to everyone. This perspective currently dominates human-rights discourse and is associated with the ‘global left’ and with the politics of ‘recognition’. The second liberal heart is communitarian social justice. Redistribution, effected primarily through the state, is owed the poor and exploited, and it can be accomplished best in one's own society, for one's own countrymen. This vision has lost a great deal of ground, especially among elites and critical intellectuals. This view is associated with the ‘sovereignty left’ and with the politics of ‘redistributive justice’. This paper examines the manifestations of these tensions in recent US immigration debates, particularly over issues of labour market competition between immigrants and the domestic poor.     

Direct observation of long-strand DNA conformational changing in microchannel flow and microfluidic hybridization assay

Conformational control of macromolecules is useful for efficient chemical and biochemical reactions. This article reports a direct observation method for macromolecules, such as long-strand DNA, in microchannel flow as well as a simple method for stretching DNA strands by microfluidics. Stretching and orientation of DNA molecules by control of flow within a microchannel was observed by optical microscopy. This DNA stretching is explained by coil-stretch transition of polymer molecules. This technique is useful for creating chemical reactions with macromolecules. It offers high selectivity and efficiency that are impossible to achieve in bulk solution. We also demonstrate that our microfluidic stretching method can accomplish efficient hybridization of long-strand DNA. This method will be useful for direct hybridization assay of long-strand DNA.     

Agonist-induced phosphorylation of an immunologically ras-related protein in human erythroleukemia cells

Monoclonal antibody M90 recognizes a specific epitope of the ras-encoded p21 protein. This region comprises amino acids 107-130 containing the residues 116-119, which are related to GTP binding. This antibody strongly reacts on Western Blots with a 22kDa protein from human erythroleukemia (HEL) cells. Treatment of HEL cells with iloprost, an agonist that increases cellular cyclic AMP levels, produces the appearance of a protein with an apparent molecular mass of 24kDa. This protein is also recognized by antiserum M90 on Western Blots; its appearance parallels a decrease of the 22kDa protein, and it can be labeled with 32P. This effect is also observed with dibutyryl cyclic AMP, which indicates phosphorylation of the 22kDa protein by cyclic AMP-dependent protein kinase. This phosphorylation produces an electrophoretic mobility change of the 22kDa protein to a 24kDa region on gels. The change of mobility of the 22kDa protein induced by iloprost in HEL cells is also observed when the protein is labeled with [35S]methionine and immunoprecipitated with antiserum M90. This information indicates a coupling mechanism involving phosphorylation of an oncogene product in HEL cells.