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At least 109 records · Page 6Linked to original sources
PubMed1999

[Single-layer or double-layer suturing of the uterine incision in cesarean section?].

UNLABELLED: The aim of the study is to compare the early complications after '/' cesarean section due to the way of closure of a low transverse uterine incision--single layer or two layers. MATERIAL AND METHODS: We investigated retrospectively in the clinical data (history of birth) 450 women with cesarean section: 300 with single layer and 150--with two layers> The hysterotomy was closed by suture with cat-gut plain No. 2 or chromic No. 1 or No. 2. Results showed single layer repair of the uterus is connected with better postoperative prognosis: low rates of febrile morbidity and wound infection, shorter hospitalization time, better involution of the uterus, p < 0.05. We had no dehiscence and secondary bleeding in both ways of repair, so relaparotomy wasn't needed. CONCLUSION: Single-layer closure has advantages compared to two-layers closure that is why it is recommended for wider application.

Cesarean Section↗
PubMed2000

[Layer-to-layer distribution of neurons and macroglial cells in various zones of the cat auditory cortex (quantitative study)].

Quantitative analysis of layer-to-layer distribution of neurons and macrogliocytes in zones AI, AII, Ep and Ins of cat brain was performed in specimens stained after Einarson. Zones of auditory cortex were shown not to differ in density of neuron distribution. In every zone the neuron number in layers II, III and VI was significantly higher than in layers IV and V and in layers III and IV of zones AI and AII the number of neurons with macroglial satellites was almost twices higher than in the same layers of zones Ep and Ins. Fraction of neurons with different number of satellites shows significant diversities as well. In layers IV, V and VI of zones AI and AII both total number of macrogliocytes and perineuronal satellites was significantly higher than in zones Ep and Ins. The number of perineuronal satellitocytes correlates both with neuron axonal length and the level of the cell functional activity.

Animals↗
PubMed1990

Layer-by-layer analysis of macular diseases with objectively measured visual functions.

New methods were developed to measure layer-by-layer visual function in macular diseases objectively and quantitatively. A prototype apparatus for foveal cone densitometry that combines a modified fundus camera, independent optic pathways and a personal computer was assembled. Using a two-way density technique, the density and regeneration time of the foveal cone pigment can be measured objectively. Data on layer-by-layer visual function can be obtained when a-wave, b-wave and oscillatory potentials are recorded by focal macular electroretinography (FMERG). Since the retinal origin of each component is different, the comparative measurement of these components indicates which layer of the macula is disturbed. The simultaneous recording of FMERG and visual evoked response (VER) might be useful in determining which part of the visual pathway is impaired. These methods of measurement were reviewed and some examples of layer-by-layer analysis were shown.

Adult↗
PubMed1992

Formation of neuroblastic layers in chicken retinospheroids: the fibre layer of Chievitz secludes AChE-positive cells from mitotic cells.

The significance of the classical subdivision of the retinal primitive neuroepithelium into an outer and an inner neuroblastic layer by the transient fibre layer of Chievitz (LOC) is little understood. We examine here the formation of neuroblastic layers by regenerating fully laminated retinospheroids from dissociated cells of the embryonic chick eye margin in rotary culture. By tracing cellular processes with the fibre-specific F11-antibody in retinospheroids, we occasionally find, in addition to an outer and an inner plexiform layer, a cell-free F11-positive LOC homologue, subdividing the inner nuclear layer. Moreover, we demonstrate that the LOC precisely separates postmitotic AChE-positive cells of the inner retina from an AChE-negative outer part holding all BrdU-labelled mitotic cells. These in vitro data suggest that the inner neuroblastic layer is exclusively composed of AChE-positive cells, thus representing a primary differentiation zone of the retina.

Acetylcholinesterase↗
PubMed1997

A Golgi study of the short-axon interneurons of the cell layer and inner plexiform layer of the medial cortex of the lizard Podarcis hispanica.

The medial cortex of lizards is a three-layered brain region displaying cyto- and chemoarchitectonical, connectional, and ontogenetic characteristics that relate it to the hippocampal fascia dentata of mammals. Three interneuron types located in the cell layer and ten others in the inner plexiform layer (six in the juxtasomatic zone and four in the deep zone) are described in this study. The granuloid neurons, web-axon neurons, and deep-fusiform neurons lay within the cell layer. These neurons were scarce; they were probably gamma-aminobutyric acid (GABA)-, and parvalbumin-immunoreactive and presumably participated in feed forward as well as in feed back inhibition of the principal projection cells of the lizard medial cortex. In the juxtasomatic inner plexiform layer, the smooth vertical neurons, smooth horizontal neurons, small radial neurons, large radial neurons, pyramidal-like radial neurons, and spheroidal neurons were found. They were all probably GABA-, and parvalbumin-immunoreactive and were involved in feed forward inhibition of principal medial cortex cells. In the deep inner plexiform layer lay the giant-multipolar neurons, long-spined polymorphic neurons, periventricular neurons, and alveus-horizontal neurons. These neurons were probably GABA-immunoreactive and either neuropeptide- (somatostatin-neuropeptide Y) or parvalbumin-immunoreactive. They seemed to be involved in feed back or even occasionally in feed forward inhibition phenomena.

Anatomy, Artistic↗
PubMed2005

Interaction of heme proteins with poly(propyleneimine) dendrimers in layer-by-layer assembly films under different pH conditions.

With the isoelectric point at pH 7.4, hemoglobin (Hb) has net positive surface charges at pH 5.0 and overall negative charges at pH 9.0, and is essentially neutral at pH 7.0. The fifth-generation poly(propyleneimine) (PPI) dendrimer is usually positively charged in aqueous solution. The {PPI/Hb}n films under different pH conditions have been successfully fabricated on various solid surfaces by the layer-by-layer assembly technique, and the growth of films was monitored by ultraviolet-visible (UV-vis) spectroscopy, quartz crystal microbalance (QCM), and cyclic voltammetry (CV). Not only was the negatively charged Hb at pH 9.0 alternately adsorbed with positively charged PPI onto solid substrates by electrostatic attraction between them, but the positively charged Hb at pH 5.0 was also successfully assembled with like charged PPI into layer-by-layer {PPI/Hb(pH 5.0)}n films. For the latter, the localized electrostatic interaction or the charge reversal of proteins on PPI surface may be the main driving force. For {PPI/Hb(pH 7.0)}n films, however, the hydrophobic/hydrophilic interaction may play a more important role in the assembly, making the amount of adsorbed Hb even less than that of {PPI/Hb(pH 5.0)}n films. For comparison, negatively charged catalase (Cat) at pH 8.0 was used to assemble layer-by-layer films with positive PPI, but {PPI/Cat}n films showed quite different properties from {PPI/Hb}n films. UV-vis and infrared (IR) spectroscopy, QCM, ellipsometry, and voltammetry were utilized to characterize the {PPI/protein}n films. The results suggest that the proteins in the multilayer films retain their near-native structure and display good voltammetric response for heme Fe(III)/Fe(II) redox couples at underlying pyrolytic graphite (PG) electrodes. Electrocatalysis of oxygen and hydrogen peroxide based on direct electrochemistry of heme proteins at {PPI/protein}n film electrodes was also demonstrated.

Animals↗
PubMed2006

Neocortical kindling is associated with opposing alterations in dendritic morphology in neocortical layer V and striatum from neocortical layer III.

Previous research has shown that seizures kindled in the corpus callosum result in a persistent enhancement of the callosal-neocortical evoked response but only a transient reduction in layer III pyramidal cell morphology. To date, there are no reports on the direct effects of repeated seizures on dendritic morphology in layer V, the pyramidal layer thought to mediate the kindling-induced enhanced evoked response. This experiment examined the effect of repeated seizures elicited from the corpus callosum, at the level of the frontal neocortex, on the morphology of sensorimotor frontal (Fr1) and occipital (OC1) neocortical layer V, as well as striatal and neuronal dendrites, in male rats. After 25 days of electrically elicited seizures or handling control, rats were sacrificed either 2 days or 3 weeks following the last seizure and processed for Golgi-Cox staining. Analysis of the impregnated pyramidal cell dendrites indicated a significant increase in the amount of dendritic length and branching in rats 2 days, but a decrease 3 weeks, following the last seizure. There was no effect at the distant occipital site. The differential effect between layer V pyramidal neurons and layer III pyramidal neurons suggests that these areas play different roles in the expression of seizures and the adaptation of the brain to the persistent effect of kindling.

Animals↗
PubMed2001

The Study of Layer-by-Layer Ultrathin Films by the Dynamic Contact Angle Method.

The self-assembly film fabricated via the layer-by-layer technique was studied by the dynamic contact angle (DCA) method (wilhelmy plate method). The used polyelectrolytes are poly(diallyl-dimethylammonium chloride) (PDDA), poly(etheleneimine) (PEI), diphenylamine-4-diazonium-formaldehyde resin (DR), 2-nitro-N-methyl-4-diazonium-formaldehyde resin (NDR), and poly(sodium-p-styrenesulfonate) (PSS). For the self-assembly systems of PDDA/PSS, PEI/PSS, DR/PSS, and NDR/PSS, their individual contact angle fluctuates regularly with the fabrication of each layer, while the magnitude of different systems' contact angle depends on the participant polycation. The re-organization of components and the adjacent layer interpenetration are presented here to explain this phenomena. We also found that DR or NDR can adsorb itself via the layer-by-layer method to form multilayer film, and the hydrophobic interaction is put forward to effect this process. Moreover, the procedure of washing and drying after adsorption was studied and considered as a prerequisite for the successful fabrication, especially of the same charge carried components. Copyright 2001 Academic Press.

Journal Article↗
PubMed2006

The influence of the atmospheric boundary layer on nocturnal layers of noctuids and other moths migrating over southern Britain.

Insects migrating at high altitude over southern Britain have been continuously monitored by automatically operating, vertical-looking radars over a period of several years. During some occasions in the summer months, the migrants were observed to form well-defined layer concentrations, typically at heights of 200-400 m, in the stable night-time atmosphere. Under these conditions, insects are likely to have control over their vertical movements and are selecting flight heights that are favourable for long-range migration. We therefore investigated the factors influencing the formation of these insect layers by comparing radar measurements of the vertical distribution of insect density with meteorological profiles generated by the UK Meteorological Office's (UKMO) Unified Model (UM). Radar-derived measurements of mass and displacement speed, along with data from Rothamsted Insect Survey light traps, provided information on the identity of the migrants. We present here three case studies where noctuid and pyralid moths contributed substantially to the observed layers. The major meteorological factors influencing the layer concentrations appeared to be: (a) the altitude of the warmest air, (b) heights corresponding to temperature preferences or thresholds for sustained migration and (c) on nights when air temperatures are relatively high, wind-speed maxima associated with the nocturnal jet. Back-trajectories indicated that layer duration may have been determined by the distance to the coast. Overall, the unique combination of meteorological data from the UM and insect data from entomological radar described here show considerable promise for systematic studies of high-altitude insect layering.

Altitude↗
PubMedDate not supplied

Layer-by-layer microfluidics for biomimetic three-dimensional structures.

Due to the complex structures of living systems, with size scales spanning from the micron to millimeter range, the use of microtechnology to recreate in vivo-like architecture has exciting potential applications. However, most microscale systems are two-dimensional, and few three-dimensional (3-D) systems are being explored. We have developed a versatile technique, combining surface engineering with layer-by-layer microfluidics technology, to create a 3-D microscale hierarchical tissue-like structure. The process involves immobilization of a cell-matrix assembly, cell-matrix contraction, and pressure-driven microfluidic delivery. An aminopropyltriethoxysilane-glutaraldehyde activated chip is used to effectively immobilize the cell-matrix assemblies while maintaining cell viability. Pressure-driven microfluidics is applied to transport cells-matrices with controlled flow rates, determined from dynamic flow imaging. By taking advantage of the contraction of the biopolymer matrices by cells, layer-by-layer microfluidics can be used to build multilayers of cell-matrix inside a microchannel and the thickness of each layer can be controlled down to microscale dimensions. Confocal and electron microscopy images of the final structure show a hierarchical layered cellular configuration composed of heterogeneous biomimetic materials. For a model system, a biomimetic arterial structure is formed using three types of vascular cells to mimic the 3-tunic structure found in vivo. This approach provides solutions to fabricate hierarchical "neotissues" with controlled microarchitectures and 3-D configurations of multiple cell types.

Biomimetic Materials↗
PubMed2006

Amperometric glucose biosensor based on layer-by-layer assembly of multilayer films composed of chitosan, gold nanoparticles and glucose oxidase modified Pt electrode.

A new strategy for fabricating glucose biosensor was presented by layer-by-layer assembled chitosan (CS)/gold nanoparticles (GNp)/glucose oxidase (GOD) multilayer films modified Pt electrode. First, a cleaned Pt electrode was immersed in poly(allylamine) (PAA), and then transferred to GNp, followed by the adsorption of GOD (GOD/GNp/PAA/Pt). Second, the GOD/GNp/PAA/Pt electrode was immersed in CS, and then transferred to GNp, followed by the adsorption of GOD (GOD/GNp/CS/GOD/GNp/PAA/Pt). Third, different layers of multilayer films modified Pt electrodes were assembled by repeating the second process. Film assembling and characterization were studied by quart crystal microbalance, and properties of the resulting glucose biosensors were measured by electrochemical measurements. The results confirmed that the assembling process of multilayer films was simple to operate, the immobilized GOD displayed an excellent catalytic property to glucose, and GNp in the biosensing interface efficiently improved the electron transfer between analyte and electrode surface. The amperometric response of the biosensors uniformly increased from one to six layers of multilayer films, and then reached saturation after the seven layers. Among the resulting biosensors, the biosensor based on the six layers of multilayer films was best. It showed a wide linear range of 0.5-16 mM, with a detection limit of 7.0 microM estimated at a signal-to-noise ratio of 3, fast response time (within 8s). Moreover, it exhibited good reproducibility, long-term stability and interference free. This method can be used for constructing other thin films, which is a universal immobilization method for biosensor fabrication.

Biosensing Techniques↗
PubMed2002

Layer-by-layer self-assembly of supramolecular and biomolecular films.

In this paper, we give a short account on recent studies of layer-by-layer self-assembly of supramolecular and biomolecular films. Such films are built up from layers of macro-ions with opposing charge. A simple film can be obtained by alternating the adsorption of two components: a flexible, synthetic polycation chains and a supramolecular or biomolecular moiety. We focus on three examples, in which the second component consists either of a supramolecular metal-organic complex (MOC), a nucleic acid, or a biological membrane patch (purple membrane). While the flexible polvcation chains (as well as eventual annealing layers) ensure a uniform build-up of the chain, the second macromolecular component may be used to functionalize the films. The combination of layer-by-layer self-assembly and biotechnologically relevant macromolecules may lead to new devices or biomaterial applications. To this end, precise studies of the deposition process and the film structure are needed. Here, we focus on interface sensitive scattering techniques for the structural analysis.

Adsorption↗
PubMedDate not supplied

Effect of the polycation nature on the structure of layer-by-layer electrostatically self-assembled multilayers of polyphenol oxidase.

Self-assembled multilayers comprised of alternate layers of polyphenol oxidase (PPO) and poly(allylamine) (PAH) or PPO and poly(diallyldimethylamine) (PDDA), deposited on a 3-mercaptopropanesulfonic acid (MPS)-modified gold surface, were studied "in-situ" (under water) by means of ellipsometry and quartz crystal microbalance (QCM), and "ex-situ" (in open air) by ellipsometry and fourier transform infrared reflection-absorption spectroscopy (FT-IRRAS). Optical ellipsometric properties of (PAH)(n)(PPO)(n) and (PDDA)(n)(PPO)(n) multilayers were obtained at two wavelengths, employing an isotropic single-layer model with the substrate parameters measured after thiol adsorption. Film thickness as well as ellipsometric mass values based on the de Feijter equation were also evaluated. The quartz crystal impedance analysis showed that self-assembled multilayers behaved as acoustically thin films, and therefore, the shifts observed in the film inductive impedance parameter were interpreted in terms of gravimetric mass. The enzyme mass up-take in each adsorption step was determined on PAH or on PDDA topmost layer. A comparative study between the ellipsometric thickness and acoustic mass values allowed us to obtain average values of "apparent" densities of (2.1 +/- 0.1) and (2.4 +/- 0.1) g cm(-3) for (PAH)(n)(PPO)(n) and (PDDA)(n)(PPO)(n) multilayers, respectively. The content of water included in the open polymer-enzyme structure was evaluated by comparison of QCM and ellipsometric mass values. FT-IRRAS spectra of each layer in (PAH)(n)(PPO)(n) and (PDDA)(n)(PPO)(n) films were recorded, and the intensity ratio of the amide bands was evaluated to obtain information about layer-by-layer enzyme conformation. An enzyme/polycation distribution model for (PAH)(n)(PPO)(n)and (PDDA)(n)(PPO)(n) multilayer structures is presented on the basis of combined ellipsometric, QCM, and FT-IRRAS results.

Catechol Oxidase↗
PubMedDate not supplied

Layer-by-layer assembly to modify poly(l-lactic acid) surface toward improving its cytocompatibility to human endothelial cells.

A novel technique to introduce free amino groups onto polyester scaffolds via aminolyzing the ester groups with diamine has been developed recently. Positively charged chitosan was then deposited onto the aminolyzed poly(l-lactic acid) (PLLA) membrane surface in a layer-by-layer assembly manner using poly(styrene sulfonate, sodium salt) (PSS) as a negatively charged polyelectrolyte. The layer-by-layer deposition process of PSS and chitosan was monitored by UV-vis absorbance spectroscopy, energy transfer by fluorescence spectroscopy, and advancing contact angle measurements. The existed chitosan obviously improved the cytocompatibility of PLLA to human endothelial cells. The cell attachment, activity, and proliferation on the PLLA membranes assembled with three or five bilayers of PSS/chitosan with chitosan as the outermost layer were better than those with one bilayer of PSS/chitosan or the control PLLA. The cells also showed morphology of an elongated shape with abundant cytoplasm, and a confluent cell layer was reached after being cultured for 4 days. Measurement of von Willebrand factor secreted by these endothelial cells (ECs) verified the endothelial function. Hence, better ECs compatible PLLA were produced.

Cells, Cultured↗