bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating Incident Population Distribution from Prevalent Data
Authors: Chan Kwun Chuen Gary , Wang Mei‐Cheng
Published: February 2012

Summary A prevalent sample consists of individuals who have experienced disease incidence but not failure event at the sampling time. We discuss methods for estimating the distribution function of a random vector defined at baseline for an incident disease population when data are collected by prevalent sampling. Prevalent sampling design is often more focused and economical than incident study design for studying the survival distribution of a diseased population, but prevalent samples are biased by design. Subjects with longer survival time are more likely to be included in a prevalent cohort, and other baseline variables of interests that are correlated with survival time are also subject to sampling bias induced by the prevalent sampling scheme. Without recognition of the bias, applying empirical distribution function to estimate the population distribution of baseline variables can lead to serious bias. In this article, nonparametric and semiparametric methods are developed for distribution estimation of baseline variables using prevalent data.
Preparation and Electrical Properties of High‐TC Piezoelectric Ceramics of Strontium‐Substituted Bi(Ni1/2Ti1/2)O3–PbTiO3
Authors: Kang Huajun , Chen Jun , Liu Laijun , Hu Changzheng , Fang Liang , Xing Xianran
Published: February 2012

A piezoelectric system of (1−x)Bi(Ni1/2Ti1/2)O3–x(Pb(1−y)SryTiO3) (BNT–PST) is developed to have good high temperature piezoelectric properties with much improved resistivity. The crystal structure shows that the phase transformation from tetragonal phase to rhombohedral one is gradually shifted to the composition with high content of PT by the substitution of strontium. The problem of leakage current for the Bi(Ni,Ti)O3–PbTiO3 can be well resolved by introducing the dopant of strontium. Both dielectric loss and DC resistivity can be much reduced not only at room temperature but also high temperature. An optimum composition of 0.53Bi(Ni1/2Ti1/2)O3–0.47(Pb0.95Sr0.05)TiO3 is obtained to have a good potential application of high temperature piezoelectric (d33 = 205 pC/N, EC = 3.32 kV/mm, Pr = 41.2 μC/cm2). Strontium could be a useful dopant for the studies on the high temperature piezoelectric ceramics in future.
Synthesis and Size Control of Tetragonal Barium Titanate Nanopowders by Facile Solvothermal Method
Authors: Lee Hyun‐Wook , Moon San , Choi Chang‐Hak , Kim Do Kyung
Published: February 2012

A facile synthetic strategy was implemented to obtain nanosized barium titanate (BaTiO3) powders with tetragonal structure. The nanoparticles were synthesized using solvothermal process employing diethanolamine and triethanolamine to suppress the particle growth and the as‐prepared nanopowders were characterized using X‐ray diffraction, scanning electron microscopy, and high‐resolution dispersive Raman spectroscopy. It was found that the particle size can be easily tuned by adjusting the experimental parameters while retaining the tetragonality. The average diameters of the particles prepared with and without the organic amines were found to be 80 and 100 nm, respectively. All the synthesized BaTiO3 nanopowders exhibit a narrow size distribution with a uniform morphology. Rietveld refinement of the XRD patterns and Raman spectra revealed that the synthesized BaTiO3 nanopowders have tetragonal asymmetry dominant structures. A slight decrease in the tetragonality of the prepared powders with decrease in particle size is attributed to the presence of cubic shell layer and inner defects. The tetragonal‐dominant structure was also confirmed by normalizing the peak area of the Raman spectra.
Air, Water, and Surface Bacterial Contamination in a University‐Hospital Autopsy Room*
Authors: Maujean Géraldine , Malicier Daniel , Fanton Laurent
Published: February 2012

Abstract:  Today, little is known about the bacteriological environment of the autopsy room and its potential interest for medico‐legal practices. Seven hundred fifty microbiological samples were taken from surface (n = 660), air (n = 48), and water (n = 42) to evaluate it in a French University Forensic Department. Median bacterial counts were compared before and during autopsy for air samples, and before and after autopsy for surface samples, using Wilcoxon matched pairs signed ranks test. Bacterial identification relied on traditional phenotypic methods. Bacterial counts in the air were low before autopsy, increased significantly during procedure, and seemed more linked to the number of people in the room than to an important production of aerosol‐containing bacteria. Despite cleaning, human fecal flora was omnipresent on surfaces, which revealed insufficient disinfection. Bacteriological sampling is an easy way to monitor cleaning practices in postmortem rooms, but chiefly a way to improve the reliability of medico‐legal proofs of infectious deaths.
Maternal heart rate patterns in the first and second stages of labor
Authors: VAN VEEN TEELKIEN R. , BELFORT MICHAEL A. , KOFFORD SHALECE
Published: February 2012

Objective. To analyze typical maternal heart rate (MHR) patterns in the first and second stages of labor. Design. Observational study. Setting. Tertiary care community hospital. Population. Normal term parturients with epidural anesthesia. Methods. Confirmed MHR and uterine activity were simultaneously recorded. The average MHR was analyzed 10 seconds before, as well as at the peak of, each contraction and/or pushing effort. Each woman contributed one datapoint at each time point to the analysis. Main outcome measure. Change in MHR during contractions. Results. First stage: 7.6±2.1 contractions per woman (n=18) were analyzed. Average MHR decreased during contractions: from 83±13 to 74±10bpm; p<0.001). In 56% (10/18) of the women, ‘early’ type decelerations were seen in at least 50% of contractions. Second stage: 3.5±1.5 contractions per woman. All women (n=15) showed MHR accelerations during every pushing effort (ΔMHR: +35±13bpm; 88±14 to 123±17bpm; p<0.001). MHR was persistently >100bpm in three women (17%) in the first stage, and in four women (27%) in the second stage. Peak MHR >140bpm occurred during pushing in 20%. Conclusion. Decreases in MHR during contractions in the first stage of labor can mimic fetal heart rate (FHR) accelerations as well as early type decelerations. Thus, first stage tracings with a low baseline and early type decelerations may be maternal in origin and FHR should be independently confirmed in such tracings. Because second stage MHR accelerations generally show greater amplitude than FHR accelerations, tracings with repetitive accelerations during contractions (especially when Δ >20bpm) should be considered MHR until proven otherwise.
A genetic approach to estimating natal dispersal distances and self‐recruitment in resident rainforest birds
Authors: Woltmann Stefan , Sherry Thomas W. , Kreiser Brian R.
Published: February 2012

Natal dispersal is a fundamental component of the ecology and evolutionary history of birds, yet is often prohibitively difficult to study. We characterized natal dispersal for the first time in a bird using molecular genetic parentage analyses in a tropical rainforest understory species, the chestnut‐backed antbird (Thamnophilidae:Myrmeciza exsul). Median natal dispersal distance was ∼800 m (mean = 931 ± 84 (SE) m, n = 48), with ∼90% of all distances < 1500 m. We found no evidence of sex‐biased dispersal. An index of self‐recruitment (i.e. individuals establishing a territory within the population of origin) was higher in sites largely or entirely surrounded by non‐forest, suggesting birds are reluctant to disperse out of preferred forest habitat. Via simulations, we confirmed that the genetic data had sufficient resolution to correctly identify parent‐offspring dyads, but lacked resolution to identify other relationships (full‐sib and half‐sib) with confidence. Chestnut‐backed antbirds have measurable self‐recruitment rates caused by short natal dispersal distances, and self‐recruitment may be amplified by reluctance to disperse out of sites bordered by non‐forest. Some tropical forest understory birds have naturally short dispersal distances, and our results have implications for understanding how species will be affected by fragmented landscapes and for the design of reserves.
Crystal structure of a ring‐cleaving cyclohexane‐1,2‐dione hydrolase, a novel member of the thiamine diphosphate enzyme family
Authors: Steinbach Alma , Fraas Sonja , Harder Jens , Warkentin Eberhard , Kroneck Peter M. H. , Ermler Ulrich
Published: February 2012

The thiamine diphosphate (ThDP) dependent flavoenzyme cyclohexane‐1,2‐dione hydrolase (CDH) (EC 3.7.1.11) catalyses a key step of a novel anaerobic degradation pathway for alicyclic alcohols by converting cyclohexane‐1,2‐dione (CDO) to 6‐oxohexanoate and further to adipate using NAD+ as electron acceptor. To gain insights into the molecular basis of these reactions CDH from denitrifying anaerobe Azoarcus sp. strain 22Lin was structurally characterized at 1.26 Å resolution. Notably, the active site funnel is rearranged in an unprecedented manner providing the structural basis for the specific binding and cleavage of an alicyclic compound. Crucial features include a decreased and displaced funnel entrance, a semi‐circularly shaped loop segment preceding the C‐terminal arm and the attachment of the C‐terminal arm to other subunits of the CDH tetramer. Its structural scaffold and the ThDP activation is related to that observed for other members of the ThDP enzyme family. The selective binding of the competitive inhibitor 2‐methyl‐2,4‐pentane‐diol (MPD) to the open funnel of CDH reveals an asymmetry of the two active sites found also in the dimer of several other ThDP dependent enzymes. The substrate binding site is characterized by polar and non‐polar moieties reflected in the structures of MPD and CDO and by three prominent histidine residues (His28, His31 and His76) that most probably play a crucial role in substrate activation. The NAD+ dependent oxidation of 6‐oxohexanoate remains enigmatic as the redox‐active cofactor FAD seems not to participate in catalysis, and no obvious NAD+ binding site is found. Based on the structural data both reactions are discussed.

Database
 Structural data are available in the Protein Data Bank database under accession number 2PGO

Structured digital abstract

 CDH and CDH bind by x‐ray crystallography (View interaction)
Deposition of Silicon Carbide and Nitride‐Based Coatings by Atmospheric Plasma Spraying
Authors: Károly Zoltán , Bartha Cecília , Mohai Ilona , Balázsi Csaba , Sajó István E. , Szépvölgyi János
Published: February 2012

In this work atmospheric plasma spraying of SiC and Si3N4 was investigated. Plasma spraying of these ceramics raises several problems since they would tend to decompose instead of melting at elevated temperatures during the process. To circumvent this problem the nonoxide ceramics were deposited as a composite powder mixed with nonoxide ceramic particles resulting in a ceramic/ceramic composite structure. Our findings were that using such a composite feedstock powder both oxidation and decomposition of the nonoxide particles could be avoided. A vitrified phase was also developed in the coating.
Synthesis and Characterization of Ceramic Membranes (W‐Type Zeolite Membranes)
Authors: Mohammadi Toraj , Maghsoodloorad Hojjatollah
Published: February 2012

In this article, effects of synthesis parameters (synthesis temperature, synthesis time, and number of layers) on W‐type zeolite membranes synthesized over flat SUS supports for O2/SF6 gas separation were experimentally investigated. Experiments were carried out at these levels of synthesis temperature: 165°C, 185°C, and 200°C; synthesis time: 6, 12, and 18 h and number of layers: 1 and 2. Permeation measurements, XRD and SEM analysis were used for characterization of the synthesized membranes. The results showed that increasing synthesis temperature from 165°C up to 185°C increases separation factor of O2/SF6, however, further increasing decreases the separation performance. The same trend was observed for synthesis time for the single layer synthesized zeolite W membrane, although for the double layer synthesized zeolite W membrane, separation factor increased with increasing synthesis time. Repetition of layering has a net positive effect on separation factor of O2/SF6, and negative effect on permeation flux through the membranes. This behavior was attributed to the dual effect of synthesis temperature and synthesis time on selectivity. More zeolite crystals are deposited and larger crystals are formed at higher synthesis temperatures and longer synthesis times. Well W‐type zeolite membrane was synthesized at 185°C for 18 h with two repeating layers with a high separation factor of 20.1.
Dynamically evolving Mg ii broad absorption line flow in SDSS J133356.02+001229.1
Authors: Vivek M. , Srianand R. , Mahabal A. , Kuriakose V. C.
Published: February 2012

We report a dynamically evolving low-ionization broad absorption line (BAL) flow in the QSO SDSS J133356.02+001229.1 (at zem∼ 0.9197). These observations are part of our ongoing monitoring of low-ionization BAL QSOs with the 2-m telescope at IUCAA Girawali Observatory (IGO). The broad Mg ii absorption with an ejection velocity of 1.7 × 104 km s−1, found in the Sloan Digital Sky Survey (SDSS) spectra, has disappeared completely in our IGO spectra. We found an emerging new component at an ejection velocity of 2.8 × 104 km s−1. During our monitoring period this component has shown strong evolution both in its velocity width and optical depth and nearly disappeared in our latest observations. Acceleration of a low-velocity component seen in SDSS spectrum to a higher velocity is unlikely as the Mg ii column densities are always observed to be higher for the new component. We argue that the observed variations may not be related to ionization changes and are consistent with absorption produced by multistreaming flow transiting across our line of sight. We find a possible connection between flux variation of the QSO and N(Mg ii) of the newly emerged component. This could mean the ejection being triggered by changes in the accretion disc or dust reddening due to the outflowing gas.
Nursing care for patients on the edge of life in nursing homes: obstacles are overshadowing opportunities
Authors: Hov Reidun , Hedelin Birgitta , Athlin Elsy
Published: February 2012

Background.  Patients in nursing homes have comprehensive needs for nursing care and medical treatment. Most patients benefit from the treatment, but some are ‘on the edge of life’‐in a borderland between living and dying with an unpredictable outcome, and questions are sometimes raised whether to withhold/withdraw curative treatment.

Aim.  The aim was to describe nurses’ conceptions of good nursing care, and how this could be carried out for patients on the edge of life in nursing homes.

Design.  In order to discover variations in the nurses’ understandings a phenomenographic approach was chosen. Phenomenography is concerned with qualitatively different ways of conceiving a phenomenon.

Methods.  Fourteen nurses from two nursing homes were individually interviewed twice. A phenomenographic analysis was used.

Results.  The outcome‐space included two main categories. The first, ‘good nursing care is to meet patients’ needs for dignity,’ included three description‐categories: needs for ‘preparedness’, ‘human relationship’ and ‘bodily comfort and safety’. The second, ‘opportunities were overshadowed by obstacles’ in carrying out nursing care encompassed three description‐categories: ‘organisational factors,’‘relational factors’ and ‘personal factors’.

Conclusions.  This study shows nurses’ conceptions of the importance of good nursing care for comforting patients on the edge of life.

Implications for practice.  Several obstacles related to resources, communication, cooperation and nurses' professional strength and power need to be overcome if good nursing care can be performed.
Cell adhesiveness and the cell cycle: correlation in synchronized Balb/c 3T3 cells
Authors: Elvin P. , Evans C. W.
Published: February 2012

The adhesiveness of Balb/c 3T3 cells partially synchronized either by drug treatment or by the mitotic cell shake‐off procedure was assessed by following the aggregation kinetics of aliquots of the cells suspended under defined conditions within the confines of a cone and plate viscometer. M phase cells synchronized by either method were significantly more adherent than appropriate control cells. Cells arrested in S phase following drug treatment were found to be poorly adhesive whereas G1 phase cells prepared by allowing drug treated M phase cells to proceed through mitosis or by treating them with L‐histidinol did not differ in their adhesiveness from appropriate control cells. The adhesiveness of control cell populations was found to vary with the extent of re‐feeding indicating a possible metabolic dependency of cell adhesion. It is suggested that although M phase cells are poorly adherent to the substrate they are nevertheless considerably adherent in an aggregation system. There was no apparent correlation of the observed increase in intercellular adhesion with any particular stage of M phase (prophase, metaphase, anaphase, telophase). We propose that Balb/c 3T3 cells show an increase in cell‐cell adhesiveness as they proceed into M phase and that this is maintained until after division is complete. Our suggestion that certain cell types may interact differently with each other and with the substrate in different stages of the cell cycle could have in vivo relevance in those processes such as tumour spread where considerable cell division is involved.
Effects of actinomycin D and cycloheximide on the nucleolar ultrastructure of porcine oocytes
Authors: Crozet N.
Published: February 2012

In early antral follicles 0.5 mm in diameter, pig oocytes were intensively engaged in rRNA synthesis. Actinomycin D caused degranulation of their nucleoli which became entirely compact; the fibrillar centers that remained adjacent to the nucleolar surface also increased in size. In contrast, oocytes from preantral follicles treated under the same conditions failed to complete nucleolar compaction and were engaged in a special process of vacuolation. The rate of [3H]‐uridine incorporation, evaluated by light‐optical autoradiography, indicated that, even at high concentrations, cycloheximide impaired nucleolar transcriptional activity of the oocytes without suppressing it. The nucleoli of such treated oocytes were either unchanged or incompletely transformed, fibrillo‐granular regions remaining adjacent to large compact areas. This study provides evidence that the process of nucleolar compaction in pig oocytes depends directly on the inhibition of rRNA synthesis. This process, which only occurs in oocytes from antral follicles, might represent an important step in the acquisition of oocyte capacity to initiate meiotic maturation.
Human spermatozoa with large heads and multiple flagella: a quantitative ultrastructural study of 6 cases
Authors: Escalier D.
Published: February 2012

Macrocephalic spermatozoa of six men were studied. In all cases, sperm concentration, proportion of live spermatozoa and sperm motility were very low. A range of ultrastructural abnormalities was found, essentially comprising a threefold increase in nuclear volume and acrosomal hyperdevelopment and malformation. There were on average 3.6 flagella for each sperm head found in the semen, some tails were separate from heads. The various defects appeared with great constancy in all of the six cases: this homogeneity indicated the existence of a defined semen profile whose most significant expression was sterility. In four of the cases large incidences of different flagellar abnormalities were also noted; whether these flagellar abnormalities are intrinsic to the above profile is not clear. Although the increase in nuclear volume suggests a disturbance in meiosis, its association with defective nuclear elongation would also indicate the existence of one or more anomalies of spermiogenesis. These results were discussed in relation to abnormalities already reported in other species either spontaneously in cases of mutations, or by experimental inhibition of microtubular structures.
Freeze‐fracture characterization of the outermost Golgi cisterna (OGC) in rat pancreatic acinar cells
Authors: Sesso A. , Nicolosi M. F. , Catena R. S.
Published: February 2012

The outermost Golgi cisterna (OGC) frequently exhibits 55 nm diameter protuberances in P fracture faces and corresponding depressions, or pits, in E faces. When these protuberances (pits) appear regularly disposed, OGC faces are recognizable at relatively low electron microscopic magnifications. The mean particle width is less in OGC (6.4 nm) than in rough ER (7.9 nm) P faces, while particle number per unit area is respectively 70% and 100% greater in OGC P and E faces than in corresponding ER faces. The rather small OGC P face particles are better resolved at a relatively low shadowing angle. These differences in particle size (for P faces) and density between OGC and rough ER faces are detectable by inspection and may be used in the recognition of OGC faces devoid of protuberances (in P faces) and pits (in E faces). Fusion of presumably rough ER‐derived microvesicles form short double‐bossed tubular elements which constitute the OGC initial structure. These tubules enlarge by addition of microvesicle membrane and contents forming a characteristic sheet‐like bossed structure.
Immunoelectron microscopic localization of snRNPs
Authors: Spector D. L. , Schrier W. H. , Busch H.
Published: February 2012

Small nuclear ribonucleoprotein particles (snRNPs) were identified in nuclear sonicates of Novikoff hepatoma ascites cells and in intact Novikoff hepatoma and PtK2 cells by immunofluorescence and immunoelectron microscopy. Auto‐antibodies (anti‐Sm and anti‐RNP) obtained from patients with systemic lupus erythematosus an autoimmune disease, were used to localize snRNP particles. The Sm antibody is specific for U1, U2, U4, U5 and U6 containing snRNPs. The RNP antibody is specific for only U1 containing snRNPs. Isolated particles, 120 +/‐ 10 A in diameter, were found to be associated with ferritin‐conjugated goat anti‐human antibodies coupled to Sm antibodies. In addition, these particles (snRNPs) were occasionally associated with larger particles measuring 230 +/‐ 10 A in diameter which are presumed to be hnRNP particles. Double label immunofluorescence and immunoelectron microscopy have shown Sm and RNP antibodies to colocalize in PtK2 cells. However, the perinucleolar chromatin and juxtanuclear envelope chromatin was devoid of RNP immunostaining. Therefore, U1 containing snRNPs do not appear to be in these regions. The Sm antibody localizes in a nuclear network including the perinucleolar chromatin and juxtanuclear envelope chromatin. Cells treated with the drug DRB (5,6‐dichloro‐1‐beta‐D‐ribofuranosylbenzimidazole), which inhibits hnRNA synthesis, show an altered pattern of Sm immunostaining. Such cells contain large clusters of snRNPs which do not extend to the perinucleolar chromatin or perinuclear lamina chromatin. Nuclear matrix preparations maintain an snRNP nuclear network as visualized by Sm immunofluorescence. It is notable that the size and density of the immunostained particles in the nuclear network during interphase, is similar to that of interchromatinic granules.
Location of RNase activity in nuclear residual structures
Authors: Herzberg M. , Nathanel T. , Bibor‐Hardy V. , Wreschner D.
Published: February 2012

We report here the partial isolation of an RNase activity which copurifies with the nuclear residual structure prepared from both rat liver and Herpes‐infected BHK cells. After the successive treatment of purified nuclei with DNase, low salt and high salt, the RNase activity is found both in the high salt soluble supernatant fraction and in the residual nuclear structure. Triton X‐100 treatment of this structure solubilizes the RNase activity. From this we conclude that some of the RNase activity associated with the nuclear residual structure may be located in either the phospholipidic or protein moieties that were extracted with Triton X‐100. This RNase cuts rRNA non‐randomly into characteristic degradation products. Its molecular weight, on a glycerol gradient, was determined to be 25,000.
Role of Ca2+ in the secretion of milk caseins in lactating rabbit mammary epithelial cells
Authors: Ollivier‐Bousquet M.
Published: February 2012

Prolactin and arachidonic acid increase milk casein secretion in mammary gland slices. These effects do not necessitate Ca2+ in the incubation medium. Prolactin does not modify the influx or the efflux of 45Ca2+. The Ca2+ channel blocking agent D600 (6 micrograms/ml) decreases the stimulatory effect of prolactin on casein secretion, but does not interfere in the stimulatory effect of arachidonic acid. The calmodulin inhibitor trifluoperazine (100 microM) inhibits stimulation of casein secretion by both prolactin and arachidonic acid. From these data, it is concluded that a flow of Ca2+ from the outside into the cell is not a requisite for the stimulation of casein secretion. However, stimulation by prolactin, but not stimulation by arachidonic acid, requires Ca2+ movement through calcium pathways. Intracellular transport of Ca2+ seems necessary for the stimulation of secretion.
Ultrastructural morphometry of the human sperm flagellum with a stereological analysis of the lengths of the dense fibres
Authors: Serres C. , Escalier D. , David G.
Published: February 2012

The dimensions of the various regions of the flagellum and the length of each of the dense fibres has been determined by transmission electron microscopy of a large number of spermatozoa from ten men. The overall mean length of the flagellum was 60.5 micron, and its diameter diminished from 0.88 micron in the midpiece to 0.17 micron at the terminal filament. The midpiece and terminal filament as measured in longitudinal sections had variable lengths among spermatozoa (3.4 +/‐ 0.5 (S.D.) micron and 3.1 +/‐ 1.0 micron respectively). Stereological analysis was used to estimate the length of the principal piece (53 micron) and the dense fibres. These latter fibres were of unequal length and extended along 60% of the length of the principal piece. They fell into 3 groups with respect to their lengths: (i) fibres 3 and 8 were short (6 micron); (ii) fibres 4, 2 and 7 were of medium length (17, 18 and 21 micron respectively); and (iii) the longest fibres were 5, 6, 9 (31, 32 and 31 micron respectively) and fibre 1 which was a little longer (35 micron). Although there was variation in the length of the various fibres among spermatozoa, the order of their termination was relatively constant. The relationship between these quantitative data regarding the structural characteristics of the dense fibres and the shape of the flagellar wave is discussed.
Immunocytochemical localization of factor VIII/von Willebrand factor antigen in human platelets
Authors: Jeanneau C. , Sultan Y.
Published: February 2012

Specific antibodies against anti‐human FVIII/vW protein were isolated by affinity chromatography on glutaraldehyde‐activated gel (Ultrogel AcA22). They were coupled directly with peroxidase or visualized with anti‐rabbit IgG (sheep)‐peroxidase (Institut Pasteur). Fab fragments of the same specific antibodies were prepared to enhance the intracellular penetration and coupled to peroxidase. In washed human platelets, staining was observed on the plasma membrane and in the canalicular system, whereas in previous studies whole specific antibodies incubated with fixed platelets showed the labeling only on the plasma membrane. After thrombin activation, the release of granules containing FVIII/vW protein was better visualized in the surface canalicular system. This localization was discussed in regard to the exocytosis process: membrane fusion, granule labeling.
Retention of indoles in the pineal organ of the bird (Melopsittacus undulatus, Shaw) during its preparation for radioautographic study
Authors: Balemans M. , Juillard M. T. , Van Benthem J. , Collin J. P.
Published: February 2012

Since high‐resolution radioautography (dipping technique) might be very useful for the study of indole metabolism in the pineal cells, the retention of [3H]‐indoles has to be examined during the preparation of specimens for electron microscopy (EM). The pineal organ of the parakeet (Melopsittacus undulatus) was used in the present work. 1) Indole metabolism: following uptake of [3H]‐5‐hydroxytryptophan ([3H]‐HW) in vivo and [3H]‐5‐hydroxytryptamine ([3H]‐HT) in vitro in similar seasonal and nycthemeral conditions—all the known pineal indolic metabolites were recovered by thin layer chromatography. [3H]‐5‐methoxyindoles were also formed from [3H]‐melatonin ([3H]‐aMT). 2) The radioactivity of fluids used in the processing of pineal organs in EM was determined by liquid scintillation counting: (a) no exogenous [3H]‐indoles could be revealed in EM solutions after [3H]‐HW in vivo uptake. (b) 8.8 to 13.4% of [3H]‐indoles were washed out by glutaraldehyde after [3H]‐HT in vitro uptake. (c) most of the 5‐methoxyindoles after in vitro uptake of [3H]‐aMT were lost in glutaraldehyde. Our chromatography procedures did not permit the identification of [3H]‐indoles extracted by the glutaraldehyde fixative. In previous experiments, [3H]‐HW and [3H]‐HT uptake showed the presence of selective radioautographic reactions in the cells of the receptor line; however, silver grains were scarce and diffusely distributed in the pineal parenchyma after [3H]‐aMT uptake.
Lipid studies on Candida tropicalis grown on alkane
Authors: Gilewicz M. , Bertrand J. C. , Parra C.
Published: February 2012

The lipid composition of whole cells and microsomal fraction of Candida tropicalis grown on alkane, glucose and glycerol have been examined. Small quantitative variations in the total lipid content are detected; the differences observed in both triacylglycerols and phospholipids are related to the substrates used to the growth.
Sodium butyrate‐induced adhesion in mastocytoma cells
Authors: Matsuhisa T. , Mori Y. , Tamura H.
Published: February 2012

Sodium butyrate induced adhesion of cultured mastocytoma p‐815 cells to the surface of a standard tissue culture grade petri dish. The ratio of the number of adherent cells to that of total cells (adherent plus floating cells) was dependent on the serum concentration and on the dose of sodium butyrate. During approximately the first 6 hr after the addition of sodium butyrate, no cells adhered. The optimum conditions for adhesion were provided by 2 mM sodium butyrate and 15% fetal calf serum, 44 hr after addition of this compound. Morphologically, adherent cells consisted of spindle‐shaped and round cells: the latter clustered to the former. Low concentrations of actinomycin D (0.005 microgram/mL) and of cycloheximide (0.5 microgram/mL) inhibited cell adhesion. Adherent cells were easily detached by 0.25% trypsin‐0.02% EDTA but not by EDTA alone. Adherent mastocytoma cells which were cultured in the presence of 2 mM sodium butyrate, re‐adhered to the surface of the dish. The ratio of adhesion in the second dish, however, was very low (35% after 2 hr incubation). Radioactive iodinated surface proteins of butyrate‐treated adherent cells showed two new bands (70,000 and 92,000 D) which were not detected in control cells, but there was no difference in the extent of labeling of high molecular weight protein (250,000 D) between butyrate‐treated and control cells.
Interactions between human fibroblasts and HeLa cells in vitro
Authors: Delinassios J. G. , Kottaridis S. D.
Published: February 2012

Affinity toward each other was demonstrated in co‐cultures between HeLa cells and fibroblasts originating from human tumor stromal or normal tissues. Both cell types in the mixed cultures (ratio 1:1, 1:2, 2:1) proliferated normally as shown by 3H‐thymidine labeling index estimation for up to 48 hr of co‐culture. At ratios of fibroblasts: HeLa lower than 1:10, fibroblasts were eventually eliminated after serial passaging. It was shown that 3H‐nucleotides could be transferred between heterologous cells in either direction. Contact of cells was essential for this phenomenon. Transfer of the label from HeLa to fibroblasts required a longer interaction time and was evidently lower than the transfer from fibroblasts to HeLa. 3H‐thymidine incorporated into the DNA of either cell type could not be transferred from one cell to another. The model provides a means for studying neoplastic X normal (or tumour stromal) cell interactions in vitro.
Simultaneous visualization of acetylcholinesterase activity and acetylcholine receptor clusters at neuromuscular synapses in vivo and in vitro
Authors: Do Thi A. , De La Porte S. , Koenig J.
Published: February 2012

Our double labelling method allows the junctional AChE and AChR distributions to be stained in the same preparation. This method which provides good definition of the fine morphology of synaptic structure and is capable of revealing a very weak AChE activity is of a particular value in studies of synaptogenesis.
Expression of hepatitis B virus (HBV) genome in the oocytes of two species of amphibians
Authors: Larive‐Zerbani A. , Gallien C. L. , Pourcel C.
Published: February 2012

Xenopus laevis and Pleurodeles waltlii oocyte nuclei are injected with a recombinant plasmid pCP 10, carrying two hepatitis B virus (HBV) genomes in a tandem arrangement. Transcription occurs in oocytes of both species and production of viral RNAs is demonstrated; better quantitative results are obtained with P. waltlii oocytes. Two viral proteins are detected: Hepatitis B surface antigen (Ag HBs) and Hepatitis B core antigen (Ag HBc). These proteins can be shown only in oocyte homogenates, and not in the incubation media. Another viral marker (Ag HBe) was not detected.
Ultrastructural investigations on two lymphoid cell lines from Niemann‐Pick disease type B
Authors: Bes J. C. , Salvayre R. , Levade T. , Caratero C. , Planel H.
Published: February 2012

Lymphoid cell lines (LCL) were established by Epstein‐Barr Virus (EBV) transformation of blood B‐lymphocytes from two different patients affected with Niemann‐Pick disease (NPD) type B. Those lines were severely deficient in sphingomyelinase activity (8% and 10% residual activity). Ultrastructural investigations showed in both these lines the presence of numerous osmiophilic, dense and pleiomorphic inclusions characteristic of lysosomal storage (due to the accumulation of amphiphilic lipids) similar to those observed in tissues from NPD.
Coordination between enzyme specificity and intracellular compartmentation in the control of protein‐bound oligosaccharide biosynthesis
Authors: Schachter H.
Published: February 2012

This laboratory has developed schemes for the control of biosynthesis of N‐ and O‐glycosyl oligosaccharides based on studies in cell‐free systems of glycosyl‐transferase substrate specificities. These schemes are based on assumptions that may not be universally correct. For example, we have ignored the possible compartmentation of reactions in different cells or in different organelles within a cell. Recent evidence has indicated that the Golgi apparatus has at least three functionally distinct regions (cis, medial and trans). The addition of galactosyl and sialyl residues to the antennae of complex and hybrid N‐glycans probably occurs entirely within the trans‐cisternae while the N‐acetylglucosaminyl‐transferases which initiate these antennae appear to be located in a denser region of the Golgi (cis and/or medial cisternae). We have constructed a modified scheme for the biosynthesis of the antennae of N‐glycans. This scheme combines our substrate specificity data (H. Schachter, S. Narasimhan, P. Gleeson and G. Vella, 1983, Can. J. Biochem. Cell Biol., 61, 1049‐1066) with compartmentation data. It provides a basis for understanding the control of glycoprotein synthesis in normal tissues and in certain lectin‐resistant mutant cell lines.
Prevention by retinoic acid of anionic site redistribution on the surface of cultured human sarcoma cells
Authors: Lotan R. , Meromsky L. , Marikovsky Y.
Published: February 2012

The distribution of cell surface negatively‐charged macromolecules was determined electron microscopically on untreated and on retinoic acid (RA)‐treated cultured human osteosarcoma Hs791 and chondrosarcoma Hs705 cells using cationized ferritin (CF), an electron‐dense marker of anionic sites. Labeling on the surface of prefixed cells was continuous and uniform whether they were grown in the absence or presence of RA. In contrast, CF distribution on unfixed cells was markedly affected by RA; CF labeling of untreated cells occurred in patches and clusters whereas the label on RA‐treated cells was continuous, as on prefixed cells. CF labeling of unfixed cells decreased considerably after incubation of the cells either with hyaluronidase or neuraminidase. There was also a reduction in patching and clustering. Changes induced by RA in the apparent membrane microviscosity, in neuraminidase‐releasable sialic acid, or in transglutaminase activity could not be related to the effect of RA on CF‐induced anionic site redistribution since these characteristics were modulated differently in the two cell lines. In contrast, RA increased the sialylation of specific cell surface membrane glycoproteins on both cell types. These results suggest that RA prevents redistribution of cell surface sialoglycoconjugates and glycosaminoglycans by CF. This effect may be the result of increased sialylation of specific surface components and may be related causally to the suppression of the transformed phenotype in the sarcoma cells.
Localization of soluble endogenous lectins and their ligands at specific extracellular sites
Authors: Barondes S. H. , Cerra R. F. , Cooper D. N. , Haywood‐Reid P. L. , Roberson M. M.
Published: February 2012

Soluble lectins of chicken, rat, frog, and the cellular slime mold, Dictyostelium discoideum, were purified and specific antibodies raised against these proteins were used to immunohistochemically localize the lectins in and around the tissues in which they were synthesized. Within cells, some of these soluble lectins (chicken‐lactose‐lectin‐II in intestinal goblet cells, discoidin II in prespore cells) appear to be concentrated within vesicles whereas others (e.g., rat beta‐galactoside lectin in pulmonary alveolar and smooth muscle cells) appear to be free in the cytoplasm. All of these lectins are eventually secreted to extracellular sites in developing or adult tissues. The sites include mucin (chicken‐lactose‐lectin‐II in intestine); developing extracellular matrix (chicken‐lactose‐lectin‐I in muscle; Xenopus laevis lectin in blastula stage embryos); slime (discoidin I); developing spore coat (discoidin II); and a specialized extracellular matrix, elastic fibers (rat beta‐galactoside lectin in lung). In cases where this has been studied in detail (discoidin I, discoidin II, and chicken‐lactose‐lectin‐II), the lectin is associated with a complementary extracellular ligand, at least transiently. Lectin‐ligand interactions presumably confer specialized properties in these particular extracellular domains.
GalNAc/Gal‐specific rat liver lectins: their role in cellular recognition
Authors: Kolb‐Bachofen V. , Schlepper‐Schäfer J. , Roos P. , Hülsmann D. , Kolb H.
Published: February 2012

By investigating the presence and distribution of GalNAc/Gal‐specific receptors on liver cells in vitro and in vivo, we provided evidence that the hepatocyte is not the only liver cell expressing receptor activity but that receptors of similar specificity are found on liver macrophages and also on endothelial cells. The receptor distribution in the plasma membrane is strinkingly different between the three cell types, as judged from the binding pattern of colloidal gold particles coated with asialofetuin or lactosylated serum albumin. Binding to hepatocytes occurs as single particles statistically distributed, binding to liver macrophages in a clustered arrangement all over the cell membrane and binding to endothelial cells also in a clustered arrangement but restricted to coated pits only. The different receptor distribution results in different binding and uptake abilities. Whereas hepatocytes bind and take up molecules and small particles (5 nm) only, the clustered receptor arrangement of endothelial cells and macrophages enables them to effectively bind and ingest larger particles. Ligands larger than 35 nm can be taken up by the macrophages only. The different receptor arrangement results also in different capacities of cell contact formation. Although in vitro liver macrophages and hepatocytes can both bind desialylated cells the macrophage needs much less galactosyl groups exposed on erythrocytes to establish stable contacts than the hepatocyte. The contacts formed by hepatocytes stay reversible for 30 min at 37 degrees C, whereas the contacts formed by the liver macrophages become irreversible after 10 min at 37 degrees C.(ABSTRACT TRUNCATED AT 250 WORDS)
Recognitory bacterial surface lectins which mediate its mannose‐specific adherence to eukaryotic cells
Authors: Eshdat Y. , Sharon N.
Published: February 2012

Cell surface protein were found to play a role in the sugar‐specific molecular mechanism by which bacteria adhere to mammalian cells. We have demonstrated that at least three different types of lectin‐like proteins mediate the mannose‐sensitive adherence of gram negative bacteria to epithelial cells. One group of such lectins was shown in our study to be associated with the bacterial flagellum. Flagella isolated from Escherichia coli 7343 and Serratia marcescens 8347 exhibited mannose‐sensitive agglutination of yeast cells; however, the flagella of the two bacteria differ in the molecular structure of their protein subunits. Another class of lectins comprises the bacterial fimbriae (also known as type 1 pili), which were previously shown to facilitate the mannose‐sensitive adherence of various bacteria to mammalian cells. Fimbriae isolated from E. coli 346 were reversibly dissociated by saturated guanidine hydrochloride to their protein subunits. The dissociated subunits retained in part their mannose‐binding ability, and were reassembled into fimbriae‐like structures by removal of the denaturant under specific conditions. Mannose‐sensitive yeast agglutinating activity of E. coli 2699, as well as of its isolated outer membranes devoid of fimbriae or flagella, was abolished by pretreatment with trypsin. It is therefore believed that the mannose‐sensitive adherence of these bacteria is mediated also by lectin‐like proteins associated directly with the outer membrane.
Cell cycle mutants of mammalian cells in culture. Present interest and limits to the study of thermodependent mutants
Authors: Evrard C.
Published: February 2012

Mammalian variants with a defect altering the cell cycle progression have been selected, characterized to different extents and preliminary genetic analysis has been carried out. The difficulties encountered in their study are discussed below. Up to now, they have limited the genetic approach to the cell cycle.
Culture of chondrocytes in medium supplemented with fetal calf serum or a serum substitute: Ultroser G
Authors: Ronot X. , Sene C. , Boschetti E. , Hartmann D. J. , Adolphe M.
Published: February 2012

Fetal calf serum and a serum substitute, Ultroser G, were compared for their effects on the growth curves, clonal growth and cell cycle progression of rabbit chondrocytes in primary culture and during at least three cell passages and included a screen for the maintenance of cartilage‐like differentiation i.e. the presence of type II collagen. Proliferation was also compared with another serum substitute, Nu‐Serum. Ultroser G is shown to be equivalent to fetal calf serum as far as chondrocyte proliferation is concerned, clonal growth is improved and biosynthesis of type II collagen is maintained in primary culture.
Polarity reversal of inside‐out thyroid follicles cultured within collagen gel: reexpression of specific functions
Authors: Chambard M. , Verrier B. , Gabrion J. , Mauchamp J.
Published: February 2012

Isolated porcine thyroid cells cultured in suspension in Eagle Minimum Essential Medium supplemented with calf serum (5‐20%) reorganize to form vesicles, i.e. closed structures in which all cells have an inverted polarity as compared to that found in follicles: the apical membranes are bathed by the culture medium. Under these conditions, cells neither concentrate iodide nor respond to acute thyrotropin (TSH) stimulation. When embedded in collagen gel, these vesicles undergo polarity reversal to form follicles. We describe here the change in the orientation of cell polarity and the subsequent reappearance of specific thyroid functions. Six hr after embedding, membrane areas in contact with collagen fibers show basal characteristics. At this time, cells begin to concentrate iodide and to respond to acute TSH stimulation (iodide efflux and increased cAMP levels). Most cells form follicles 24 hr after embedding, but 48 hr are required for the transformation of all vesicles into follicles. This occurs without opening of the tight junctions. Iodide organification is detected 24 hr after embedding, when periodic acid‐Schiff positive material, identified as thyroglobulin by immunofluorescence, accumulates in the lumen. Iodide concentration and organification, as well as response to TSH stimulation reach maximal levels after 3 days in the collagen matrix. After a 5‐day culture in the collagen matrix in the absence of TSH, cell activity can be stimulated by chronic treatment with low hormone concentrations (10‐100 microU/ml). As shown with thyroid cells grown in monolayer on permeable substrates (Chambard M., et al., 1983, J. Cell Biol. 96, 1172‐1177), iodide uptake and cAMP‐mediated TSH responses are expressed when the halogen and the hormone have direct access to the basal membrane. Organification, on the contrary, requires a closed apical compartment.
Follicle cell tubular system in the prawn Macrobrachium rosenbergii: a route for exchanges between haemolymph and vitellogenic oocytes?
Authors: Jugan P. , Zerbib C.
Published: February 2012

The epithelial cells of the ovary follicles have been studied in the prawn Macrobrachium rosenbergii using electron microscope and horseradish peroxidase. A network of circumvoluted and anastomosed tubules, measuring about 0.15 micron in diameter, communicates with the extracellular spaces. This tubular network is a structure which extensively increases the permeability of the follicular epithelium.
Pushing the signal hypothesis: what are the limits?
Authors: Hortsch M. , Meyer D. I.
Published: February 2012

Recent advances in understanding the in vitro translocation of nascent polypeptides across the endoplasmic reticulum (ER) membrane have established a molecular basis for the initial reactions predicted by the signal hypothesis. The first two events involve a transient arrest of nascent chain elongation, followed by a docking maneuver with the ER membrane which releases this block. It is not clear, however, that such signal sequence‐mediated transfer occurs in the case of all proteins, or for that matter in all cell‐free translation systems.