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At least 757 records · Page 42Linked to original sources
PubMed1985

Adaptation of a ciliary basal apparatus to cell shape changes in a contractile epithelium.

Cilia projecting from the surfaces of highly contractile myoepithelia in the sea anemone Metridium senile maintain their basal orientation, and their ability to propel water, at different states of mesentery contraction, despite substantial changes of myoepithelial cell diameter and length. The ciliary basal apparatus in each monociliated myoepithelial cell is structurally well adapted to provide a stable anchorage for the cilium whilst compensating for these shape changes. It is composed of a distal centriole (basal body), a proximal centriole, a striated rootlet 2-3 micron long which is composed of a bundle of 4-6 nm filaments, and an arched rootlet, also striated, which is composed of a relatively loose bundle of 9-11 nm filaments. A single basal foot projects from the side of the distal centriole in the same direction as the path of the cilium during an effective-stroke; its tip is a focus for many microtubules that radiate outward in all directions toward the cell membrane. The arched rootlet forms a single arch in the cell apex, also in the same plane as the path of the cilium during an effective-stroke. The central axis of the basal apparatus, that is through the distal centriole and the striated rootlet, passes through the apex of the arch. The arched rootlet is apparently flexible so that it can increase or decrease its span as the cell increases or decreases in diameter. In pharnyx and siphonoglyph cells from M. senile, which do not undergo great changes in diameter or length, there is no arched rootlet, and the striated rootlet is much longer. The broad structural diversity of the metazoan ciliary basal apparatus must to a large extent be related to the diversity of the structural and mechanical properties of the cells in which it occurs.

Animals↗
PubMed1980

Human-specific nuclear protein that associates with the polar region of the mitotic apparatus: distribution in a human/hamster hybrid cell.

We describe the first example of a predominantly nuclear protein which during mitosis becomes part of the mitotic apparatus. This protein has been termed the nuclear-mitotic apparatus (NuMA) protein. In interphase cells NuMA protein is restricted to the nucleus and is a constituent of isolated nuclear matrices, but in mitotic cells it is observed by indirect immunofluorescence microscopy to be concentrated at the polar regions of the mitotic apparatus. This mitotic localization is dependent on the integrity of the spindle, since treatments which disrupt the spindle result in dispersion of NuMA protein throughout the cell. Comparison to the subcellar distribution of tubulin at different stages of the cell cycle indicates that NuMA protein is distinct from the previously identified components of the mitotic spindle. Its association with the nuclear matrix and its localization during mitosis to the site of nuclear reassembly suggest the interesting possibility that NuMA protein could be representative of a class of proteins involved in the early events of nuclear reassembly. NuMA is present in the nuclei and mitotic spindle of all types of human cells that have been examined, but proteins of similar molecular weight (300,000 daltons in dissociating solvents) or immunological specificity are not detected in cells of other species (including monkey). However, the NuMA protein is synthesized in a human/Chinese hamster hybrid cell containing a reduced number of human chromosomes. Immunofluorescence studies of this hybrid cell showed that the distribution of NuMA protein is equivalent to that in human cells. These results suggest that the human gene coding for NuMA protein, unlike other genes coding for human specific nuclear proteins, can be expressed in human/hamster hybrid cells and that the cell hybrids will be useful in further characterization of NuMA protein.

Animals↗
PubMed1985

An all-glass apparatus for liver perfusion of lipophilic substrates. I. Construction and physical characteristics.

An all-glass apparatus for perfusing isolated rat livers was constructed for use in studies of the metabolism by, or action on, the liver of lipophilic substrates. Other designs, which generally include plastic connections or cannulae, can have unnecessarily complicated kinetics because of adsorption of the agent to the plastic parts. Two versions of an all-glass perfusion apparatus are described in detail. Both instruments operate on the same basic principle, but differ in size, total recirculating volume, pump rate, perfusion head pressures, maximum perfusate flow rate, maximum linear velocity in the perfusion head, and oxygenation efficiency. Although the maximum protein handling capacity differs for the two apparatuses, this capacity is so limited that it disallows the use of albumin in the perfusate.

Animals↗
PubMed1980

Improved stop-flow apparatus to measure permeability of human red cells and ghosts.

An improved stop-flow apparatus has been designed and constructed to measure the permeability characteristics of human red cells, which can be inferred from the time course of red cell volume changes following a sudden change in cellular environment produced by a raped mixing device. The improved apparatus is directly coupled to a computer which automates the subtraction and averaging procedures that have been developed to minimize the noise generated in the system by the cessation of red cell forward motion when the flow is suddenly stopped. Real time data acquisition also makes it possible to increase the number of data points by an order of magnitude, thus improving accuracy significantly. The apparatus has been tested by measurements of the human red cell hydraulic permeability coefficient. Data are presented to validate the subtraction procedure. Experiments have also been carried out on red cell ghosts which indicate that the hydraulic conductivity of the ghost is similar to that of the undisturbed red cell.

Adult↗
PubMed1989

A thin-layer multistrip agarose gel electrophoresis apparatus for Ferguson plot analysis at the sub-microgram load level.

A method for the simultaneous horizontal agarose gel electrophoresis on thin-layer strips of different gel concentrations was developed for the purpose of generating Ferguson plots at the sub-microgram load level. Seven independent gel strips on a common GelBond support were formed by filling channels created by a comb-shaped spacer (polycarbonate) in a vertical multistrip cassette. Electrophoresis on a horizontal Peltier-cooled surface employed commercial apparatus (E-C Apparatus Corp.) with a modified cover which is airtight and holds anodic and cathodic voltage measurement probes for each strip. The application of the apparatus to Ferguson plot analysis in a single experiment was exemplified on the RNA-containing turnip crinkle virus (TCV) at a load of 50 ng/gel strip, using an optimized silver staining method (a modification of a procedure of FMC Corp. BioProducts) for detection. Within the range of 3.5 to 12.5 V/cm, the plot was found to be independent of field strength. Mobility is also independent of the concentration of detergent (CHAPS) up to 10 mM.

Electrophoresis↗
PubMed1987

A washing apparatus for microcentrifugation assays.

The use of centrifugation techniques for separating labeled compounds that are bound to tissue fractions from unbound substrate is widespread in biochemistry. An apparatus is described for simultaneously washing 24 microcentrifuge tubes. The apparatus provides for removing solutions from the tubes and filling tubes with washing solution. This apparatus permits the rapid and reproducible analysis of large numbers of samples.

Cell Fractionation↗
PubMed1995

A novel apparatus that permits multiple routes for infusions and body-fluid collections in a freely-moving animal.

A novel apparatus is described for simultaneous performance of multi-channel infusions/body-fluid collections and multichannel electrical recordings/stimulations in a freely behaving animals. This apparatus consists of a cylindrical cage and other devices described below. Electrical contacts are achieved via a slip-ring commutator. A rotation detector detects the turning of the animal in the cage, and a controller rotates the floor under the animal in the opposite direction by means of a stepping motor. Thus, excessive twisting of the fluid tubing between the animal and experimental equipment is released by rotation of the floor. Floor rotation starts when the animal turns in either direction and exceeds a present number of rotations. When the turning exceeds certain rates, the floor is rotated with higher angular velocities. This floor rotation little affected sleep-wake activities, brain temperature, food and water intake, and general behavior of the rat. Thus, multi-channel fluid routes have been realized; and by excluding the swivel apparatus from the fluid lines, advantages such as no fluid leakage at the swivel, no extra dead volume, and low torque to rotate the device have been gained.

Animals↗
PubMed1981

Performance of decorticated rats in a two-choice visual discrimination apparatus.

Normal rats and rats with 98.8% (S.D. +/- 1.4) of neocortex surgically removed were trained in a two-choice discrimination apparatus for food reward. The animals were first trained to run the apparatus with identical non-patterned goal box doors followed by discrimination and reversal training using horizontal and vertical striped panels attached to the doors. These patterned stimuli were matched for total luminous flux and contour length and control procedures were included for unintended discriminative cues from other sensory modalities. The two groups did not differ in the number of trials taken to complete preliminary training but the decorticates were significantly faster at running the apparatus than the normals. All animals solved the visual discrimination and were able to reverse it. There were no significant differences between the groups in trials taken to acquire the visual discrimination except at the very highest criterion levels employed, though reversal of the discrimination was more difficult for the lesioned group. The preliminary training data are taken as further evidence that total decortication does not necessarily impair instrumental performance for food reward and that this lesion does not introduce any limiting sensory or motor deficit in the alleyway situation. It would also appear that neocortex is not essential for the solution of a horizontal/vertical stripe problem. It is not clear, however, that such a solution necessarily depends on a true pattern discrimination, and both lesioned and normal animals may have been employing strategies based on local cues within the two patterned stimuli. The appropriateness of the total decorticate preparation for a resolution of the problem of cortical vs subcortical substrates of residual vision following visual cortex lesions is discussed. The possibility that undamaged neocortical tissue remaining after visual cortex lesions may inhibit the full expression of residual subcortical function is raised by these data.

Animals↗
PubMedDate not supplied

Accuracy of an automatic impedance apparatus in a population with secretory otitis media: principles in the evaluation of tympanometrical findings.

INTRODUCTION: The primary demand for a screening procedure for secretory otitis media (SOM) is to identify an objective test with sufficient sensitivity and specificity to meet the needs of the screening program. This study was designed to estimate the value of a portable automatic impedance apparatus to meet these needs. SUBJECTS AND METHODS: Two hundred twenty children with unilateral or bilateral SOM were evaluated in a double-blind, cross-sectional study. All have fulfilled two of the following three criteria for surgical intervention: (1) SOM by physical examination, (2) greater than 20 dB hearing impairment, and/or (3) adenoid symptoms. All ears were evaluated using tympanometry, following which myringotomy was performed. RESULTS: Otomicroscopy showed fluid behind the tympanic membrane in 393 ears. All underwent myringotomy. Thirteen percent (51 ears) were empty. Of the otomicroscopic findings consistent with SOM, 82% had B curves, 6% had C2 curves, 8% had C1 curves, and 4% had A curves. Both C2 and B curves were considered abnormal. Sensitivity of the apparatus is 94.4% and of the specificity is 52.9%. There was no statistical correlation between tympanometrical findings and fluid viscosity. RESULTS: A test intended for screening has to be simple, easy, and quick to perform. Furthermore, the test should have high sensitivity. The automatic impedance apparatus is able to meet these demands; however, the individual results have to be confirmed by another method, eg, otomicroscopy, pure-tone audiometry, and/or manual tympanometry.

Acoustic Impedance Tests↗
PubMed1984

Frog palate mucociliary apparatus: structure, function, and response to formaldehyde gas.

The upper respiratory tract mucociliary apparatus represents one of the first defenses against inhaled noxious materials. The frog palate has been widely used as a model to investigate the mode of action of this apparatus and to study its response to irritant gases. Video analysis was used here for the determination of mucus flow rate and flow patterns, ciliary beat frequency, and the nature of ciliary activity in the in vitro frog palate preparation. The results of studies of time-lapse video recordings were used in conjunction with light microscopic and ultrastructural morphologic investigations to determine functional interactions between cilia, the epiphase, and the periciliary fluid. It was concluded that the cilia enter the epiphase during the effector stroke, that waves may be produced on the under surface of this layer, and that the periciliary fluid is less viscous than, and moves in the same direction as, the epiphase. The response of the frog palate mucociliary apparatus to formaldehyde gas was also studied using an in vitro exposure system. There were distinct concentration-related responses to formaldehyde with initial stimulation, and at higher concentrations, subsequent inhibition of mucociliary function. Stimulation of mucus flow rate was due to increased ciliary activity, while inhibition of flow, which preceded ciliastasis, was attributed to direct effect of formaldehyde on the superficial mucus layer. Ciliastasis on the other hand was considered to provide evidence that the formaldehyde had penetrated the mucus layer and induced direct toxic effects on the underlying epithelial cells.

Animals↗
PubMed1981

Phylogenetic significance of the flagellar apparatus in protostelids (Eumycetozoa).

The ultrastructure of the flagellar apparatuses of four species of protostelids is described. All four species have the same three major groups of rootlet microtubules in common, microtubule arrays (MTA) 2, 3, and 4. Variation is found in the number of centrioles per flagellar apparatus, presence or absence of two other microtubule arrays, MTA 1 and MTA 5, types of connectives linking the centrioles to the MTAs, nature of the transitional elements of the flagella, and the association of the flagellar apparatus with the nucleus. It is concluded on the basis of this study and comparison with earlier studies on protostelids, myxomycetes, and other amoeboflagellates that the flagellate species of protostelids are monophyletic. The significance of this to the phylogeny of protostelids and related mycetozoans is discussed.

Animals↗
PubMed1979

Postsynaptic membrane and spine apparatus: proximity in dendritic spines.

We have reported previously that at dendritic spine synapses, the spine apparatus is associated with the synaptic spinule. In this report this association is shown, in serial thin sections, to involve intimate physical proximity between the postsynaptic density and membranous structures that are part of, or extend from, the spine apparatus itself. Because of the variegated shapes of synaptic spinules, the spine apparatus-postsynaptic density relation suggests participation in membrane distribution or synaptic remodeling phenomena.

Animals↗
PubMed1983

Accumulation of [3H]fucose-labelled glycoproteins in the Golgi apparatus of dorsal root ganglion neurons during inhibition of fast axonal transport caused by exposure of the ganglion to Co2+-containing or Ca2+-free medium.

Previous in vitro studies have established that Co2+-containing or Ca2+-free media interfere with the initiation of the fast axonal transport of proteins. The present study has used light- and electron-microscope radioautography to compare the distribution of [3H]fucose-labelled glycoproteins in neuronal cell bodies of control dorsal root ganglia and ganglia incubated for 16-17 h in Ca2+-free medium or in medium containing 0.18 mM Co2+. The radioautographic reaction in control cell bodies was diffusely scattered throughout the cytoplasm; grain counts revealed that 22% of the reaction was associated with elements of the Golgi apparatus and 78% was over other organelles and the remainder of the cytoplasm. In most experimental cell bodies, 78% of the silver grains were clustered over elements of the Golgi complex whereas other organelles and the remainder of the cytoplasm were comparatively much less labelled; structural alterations of the Golgi apparatus were also produced by the modified media. In parallel studies where the radioactivity in nerve trunks and ganglia was measured by liquid scintillation counting, it was found that the Ca2+-free medium and the Co2+-containing medium both reduced by approximately 80% the quantity of [3H]fucose-labelled glycoproteins which were carried by the fast axonal transport system; they did so without interfering with the incorporation of [3H]fucose into glycoproteins. The results indicate that in the presence of Co2+ or in the absence of Ca2+ the proteins which are destined for fast axonal transport accumulate at the Golgi apparatus of neuronal cell bodies. These results thus suggest that Ca2+ is required for proteins to leave the Golgi region in transit to the fast axonal transport system.

Animals↗
PubMed1990

Preservation versus severance of the subvalvular apparatus in mitral valve replacement: an experimental study.

Preservation of the subvalvular apparatus in mitral valve replacement has been suggested to improve postoperative left ventricular performance. As it is difficult to quantify the change in left ventricular performance clinically, an experimental model was devised to demonstrate the contribution of the subvalvular apparatus to left ventricular function. In eight dogs mitral valve replacement (St. Jude prostheses) was performed, preserving the subvalvular apparatus by plicating the leaflets with the prosthesis on the mitral annulus. Left ventricular function was assessed during volume loading with blood before and after cutting the chordae tendineae by means of electrocautery applied via flexible wires slung around the chordae and exteriorized through the left ventricular wall. Left ventricular internal diameters were measured by sonomicrometry. End-diastolic volume (LVedV) and stroke volume were determined by dye dilution and left ventricular pressure (LVP) by cathter tip manometer. The results showed that after cutting the chordae the heart rate did not differ from the pre-cut values at any LVedP. The peak left ventricular pressure was only significantly reduced at an LVedP of 5 mmHg and minor axis diameters were only increased at an LVedP of 9-12 mmHg. Significant changes were observed, however, in LV dP/dtmax (= maximum rise of LVP) (-15%), major axis end-diastolic diameter (+10%) and systolic shortening (-40%), end-diastolic volume (+18%) and ejection fraction (-16%) at any LVedP, and stroke volume (-24%) at any LVedV.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

A serosa-searing apparatus for producing gastric ulcer in rats.

Chronic ulcer models produced by serosa-searing method are very similar histologically to the ulcer healing process occurring in humans. In an effort to produce a serosa-searing chronic ulcer model in rats, we devised a new balance-type apparatus. This searing apparatus is capable of changing adequately both temperature and duration of time. Furthermore, the pressure which serves to bring the searing iron tip into contact with the stomach serosa surface can also be precisely changed. Optimal conditions for reproducing the serosa-searing ulcer model were at 65 degrees C and in 5 sec. Moreover, in order to evaluate the effects of pressure, various pressure levels (A: 5 g, 17.68 g/cm2; B: 10 g, 35.37 g/cm2; C: 15 g, 53.05 g/cm2; D: 20 g, 70.74 g/cm2; E: 25 g, 88.42 g/cm2; F: 30 g, 106.10 g/cm2; G: 35 g, 123.79 g/cm2 (+/- 1 g, 0.149 g/cm2)) of 5-sec duration at 65 +/- 0.1 degrees C were used. Macroscopically, gastric mucosal lesions were most clearly observed in a pressure-related manner 7 days after the procedure. Histologically, definite deep ulcerations (UI-III or UI-IV) were observed at pressure level C (15 g, 53.05 g/cm2) or more. The highest incidence (87%) of histological gastric ulcers (UI-IV) was observed in pressure level E (25 g, 88.42 g/cm2). The healing process was observed at 40 to 60 days postoperatively. At 100 days after the procedure, recurrences were observed both macroscopically and histologically. In conclusion, this new apparatus is very useful for reproducing a chronic ulcer model for observing the healing and recurrence process.

Animals↗
PubMed2003

Improved apparatus for solid-liquid multi-stage counter-current extraction.

An improved apparatus for solid-liquid multi-stage counter-current extraction (SLME) was developed. The apparatus has a set of 24 extraction vessels. Each extraction vessel unit is composed of a piston-cylinder in which the solid phase is placed, and a cup-cylinder in which the liquid phase is set. Of the 24 extraction vessels, 20 were used for the separation stage, and the other 4 were used for the back-extraction stage. (+/-)-Troger's base was selected as a racemic model compound for the continuous enantioseparation by the apparatus, and a cellulose derivative was used as the chiral separator. After 50 cycles of the operation (in 9 h), 0.1 g of (-)-enantiomer (85% in purity) was recovered from the solid phase by back-extraction with ethanol, whereas 1.1 g of (+)-isomer (75% in purity) was collected from the liquid phase (ethanol).

Chromatography, High Pressure Liquid↗
PubMed2006

The involvement of LHCII-associated polyamines in the response of the photosynthetic apparatus to low temperature.

The influence of low temperature on the structure and function of the photosynthetic apparatus was investigated in Phaseolus vulgaris L. Ten-day-old plants (grown at 26 degrees C) have been exposed to low temperature (6 degrees C) for 52 h and, then, transferred to the initial temperature (26 degrees C) for additional 30 h. Biochemical and physico-chemical measurements performed in the low temperature-treated plants showed that the response of the photosynthetic apparatus to low temperature is affected by the changes occurring in the pattern of LHCII-associated putrescine (Put) and spermine (Spm) which adjust the size of LHCII. The decrease of Put/Spm ratio, mainly due to the reduction in the quantity of LHCII-associated Put led to an increase of the LHCII, especially of the oligomeric forms. These alterations in the structure of the photosynthetic apparatus combined with the reduction in the photosynthetic electron transfer rate resulted in the inactivation of active reaction centers and the increase of dissipated energy which diminished the photosynthetic efficiency and the maximal photosynthetic rate. The transfer of plants at 26 degrees C after the low temperature treatment showed that, structurally and functionally, the photosynthetic mechanism recovered quite fast to the initial condition.

Cold Temperature↗
PubMed2005

A nose-only apparatus for airborne delivery of Mycobacterium tuberculosis to mice: calibration of biological parameters.

Mycobacterium tuberculosis is the main cause of tuberculosis and is still a public health concern worldwide. This mycobacterium is transmitted through aerosols from human beings suffering from pulmonary tuberculosis to susceptible persons. To study this natural route of infection, we designed a new nose-only aerosol apparatus--system of aerosolisation of microorganisms (SAM)--in a carefully designed biohazard facility. For safety reasons, Mycobacterium smegmatis was first used to calibrate several parameters, such as inoculum density, atmospheric conditions (i.e. hygrometry) and particle size distribution. We present evidence that our apparatus is totally adapted to airborne delivery; the particle size of generated aerosol ranges from 1 to 7 microm, which is ideal for an infection by inhalation. We found that 99% of generated particles (<7 microm) could be retained by the respiratory tract, and among these particles, 62-79% (<3.3 microm) were able to reach pulmonary compartments. The next step was to simultaneously challenge 48 mice with M. tuberculosis in a highly reproducible way. We showed that a moderate dose (4 log10 colony-forming units (CFU) per mice) of M. tuberculosis was capable of causing progressive lung pathology and death in mice 30 days post-aerosolisation. Therefore, our apparatus, once calibrated, is easy to handle, safe, and can be used with any pathogen, which is spread by aerosol.

Aerosols↗