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At least 721 records · Page 40Linked to original sources
PubMed1995

Commercial automated gel electrophoresis apparatus: application to DNA, band dispersion, nonlinear Ferguson curves, and isolation.

Recently available commercial automated gel electrophoresis apparatus with intermittent scanning of fluorescently labeled gel patterns (the HPGE-1000 apparatus of LabIntelligence, Menlo Park CA) was tested with regard to (i) its applicability to DNA in its native conformation, (ii) its ability to recognize the correct number of components, (iii) its capability to evaluate the width and shape of bands detected during electrophoresis, (iv) its ability to yield nonlinear Ferguson plots in a labor-saving fashion, and (v) its preparative potential. Ethidium homodimer (EtD) DNA (bp) ratios were systematically varied and the mobility of DNA fragments labeled at each ratio was measured in order to find a ratio which provided an unaltered mobility and presumably therefore an unaltered conformation of the fragment. That ratio was found to be 1/40 EtD/DNA (bp) or less. With such weak labeling of DNA, a representative fragment of 527 bp length requires a minimum load of 200 ng and a 2 micrograms load for a full-scale peak height. Using the baseline automatically selected by the software of the apparatus, the band areas of the 17 components of a DNA digest were consistently evaluated by the software, as evidenced by the proportionality between DNA length and area. The areas of the separated bands of DNA fragments of 1857 and 121 bp length were found to be constant with time of electrophoresis. The dispersion coefficient was found to decrease with agarose concentration in electrophoresis at 1 V/cm; however, at higher field strength, the band width of the 1857 bp fragment was surprisingly found to increase with gel concentration, presumably due to stretching.(ABSTRACT TRUNCATED AT 250 WORDS)

Buffers↗
PubMed1995

Nonlinear "Ferguson curves" by two runs of the commercial automated HPGE-1000 gel electrophoresis apparatus with intermittent scanning of fluorescence.

The exploitation of gel electrophoretic migration distance to gain information of molecular and gel fiber properties depends on the functions relating mobility with gel concentration. To the degree that these are nonlinear, the definition of those functions by past methods has been excessively laborious or, in application of gel concentration gradients, based on a number of assumptions. The recent commercial introduction of gel electrophoresis apparatus capable of intermittent scanning of the pattern promised to solve these problems. The present study shows that such apparatus allows for a precise definition of a nonlinear "Ferguson curve" (mobility vs. gel concentration) in two experiments, using different gel concentrations in the eight channels of the HPGE-1000 apparatus and 5-29 scans in each during the course of an electrophoretic run. Simultaneously, these Ferguson curves are obtained for five components of a DNA ladder ranging in DNA length from 121 to 1857 bp.

Autoanalysis↗
PubMed1996

Application of gels of 0.5 mm thickness to electrophoresis in the automated HPGE-1000 apparatus: improved resolution.

Gel electrophoresis in commercial automated apparatus (HPGE-1000, LabIntelligence, Menlo Park, CA) is conventially conducted in gels of 3 mm thickness at about 15 V/cm. Since the intermittent scanning of the gel allows one to measure band width as a function of migration time, resolution may be evaluated quantitatively. Comparing the value of resolution between two proteins in electrophoresis on agarose gels of 0.5 and 3.0 mm thickness and at various field strengths, it was found that within the given Joule heat dissipation capacity of the apparatus, resolution between the proteins is improved when the gel thickness is reduced from 3.0 to 0.5 mm, which allows for an increase in field strength from 15 V/cm, conventional for that apparatus, to 45 V/cm.

Autoanalysis↗
PubMed1998

An apparatus for membrane-confined analytical electrophoresis.

A membrane-confined analytical electrophoresis apparatus for measuring the solution charge of macromolecules has been described previously (T. M. Laue et al., Anal. Biochem. 1989, 182, 377-382). Presented here is a design for this apparatus, which permits the on-line acquisition and display of absorbance data from up to 512 positions along an analysis chamber. Concentration distributions of macromolecules in solution can be monitored in the chamber to provide steady-state electrophoresis, electrophoretic mobility and diffusion measurements. Buffer chambers press semipermeable membranes against the open ends of a fused-silica cuvette to form the analysis chamber. This configuration permits both the flow of buffer and the establishment of an electric field across the cuvette, while retaining macromolecules in the field of view. Though a gel may be included in the analysis chamber, none is required for gradient stabilization. The volume of sample required for analysis is 8 microL, most of which is recoverable. Experimental conditions can be varied during study by simply changing the circulating buffer and/or the electric field. The analysis and buffer chambers are held in an aluminum housing that sits in an aluminum water jacket. The water jacket provides temperature control, shielding from external electrical noise and also serves as an optical mask. Plans for the cell assembly, optical system and the computer interface for data acquisition are provided. The assembly and operation of the apparatus and the analysis of data are described.

Electric Conductivity↗
PubMed2006

Venom apparatus of the endoparasitoid wasp Opius caricivorae Fischer (Hymenoptera: Braconidae): morphology and ultrastructure.

The morphology and ultrastructure of the venom apparatus of the endoparasitoid wasp, Opius caricivorae Fischer (Hymenoptera: Braconidae), were observed using light and electron microscopes. The venom apparatus consists of one venom reservoir and several gland filaments. The gland filaments join together at the end of the reservoir and consist of an outer single layer of secretory cells, a layer of degenerated epidermal cells, and an inner intima that encloses the lumen. The secretory cells are organelle rich, with abundant rough endoplasmic reticulum, mitochondria, and vacuole, in which vesicular organelles secrete the components of venom. The reservoir consists of a muscular sheath, secretory cells, and squamous cells. The intima has an unevenly thickened chitinous coat. The vesicular organelles of the reservoir secretory cells differ from those of the gland filament: the microvilli being much longer and radiating in all directions. The venom reservoir not only serves to store but also secretes the venom. Virus-like particles were discovered in the secretory cells of the gland filaments. The structural features of venom apparatus of this species are discussed in a biological context.

Animals↗
PubMed1986

Morphology and function of the feeding apparatus of the lungfish, Lepidosiren paradoxa (Dipnoi).

The feeding mechanism of the South American lungfish, Lepidosiren paradoxa retains many primitive teleostome characteristics. In particular, the process of initial prey capture shares four salient functional features with other primitive vertebrates: 1) prey capture by suction feeding, 2) cranial elevation at the cranio-vertebral joint during the mouth opening phase of the strike, 3) the hyoid apparatus plays a major role in mediating expansion of the oral cavity and is one biomechanical pathway involved in depressing the mandible, and 4) peak hyoid excursion occurs after maximum gape is achieved. Lepidosiren also possesses four key morphological and functional specializations of the feeding mechanism: 1) tooth plates, 2) an enlarged cranial rib serving as a site for the origin of muscles depressing the hyoid apparatus, 3) a depressor mandibulae muscle, apparently not homologous to that of amphibians, and 4) a complex sequence of manipulation and chewing of prey in the oral cavity prior to swallowing. The depressor mandibulae is always active during mouth opening, in contrast to some previous suggestions. Chewing cycles include alternating adduction and transport phases. Between each adduction, food may be transported in or out of the buccal cavity to position it between the tooth plates. The depressor mandibulae muscle is active in a double-burst pattern during chewing, with the larger second burst serving to open the mouth during prey transport. Swallowing is characterized by prolonged activity in the hyoid constrictor musculature and the geniothoracicus. Lepidosiren uses hydraulic transport achieved by movements of the hyoid apparatus to position prey within the oral cavity. This function is analogous to that of the tongue in many tetrapods.

Animals↗
PubMed1984

Long-term measurement of muscle function in the dog hindlimb using a new apparatus.

The objective of this study was to develop an apparatus for reliable, reproducible, and minimally invasive measurements of long-term, myoneural function. Twenty conditioned dogs were anesthetized and placed supine with one hindlimb secured in a boot apparatus. The hindpaw was attached to a force transducer that was connected to a recorder for continuous monitoring of torque. Muscles within the anterolateral compartment were stimulated by percutaneous electrodes over the peroneal nerve near the fibular head. This elicited isometric dorsiflexion of the hindpaw. Twitch and tetanic torques correlated positively with dog weight whereas other skeletal-muscle function parameters (time to peak tension, one-half relaxation time, and endurance) were independent of dog weight. Muscle function results were consistent with an overall compartmental composition of 30% Type I and 70% Type II fibers. Repetitive testing of twitch and tetanic torques in the dog legs yielded coefficients of variance of 3-4% (intraday) and 7% (interday). Thus, about one-half of the interday variability may be accounted for by diet, exercise, and other physiological conditions that change daily. The apparatus was also used to detect myoneural degeneration following tourniquet ischemia. The results indicate that this procedure for evaluating muscle function yields reliable and quantitative results noninvasively, and thus allows long-term testing of muscle function in normal and diseased hindlimbs of dogs.

Animals↗
PubMed1981

Continuous flow bead-bed dissolution apparatus for suppositories.

A bead-bed dissolution apparatus for suppositories was evaluated by measuring the release of benzocaine from various vehicles. During dissolution, suppositories soften, deform, disintegrate, and eventually pass through a phase change from a solid to an oil. The control of the interfacial area during dissolution is a key factor in obtaining experimentally reproducible release data. The proposed suppository dissolution apparatus was designed to provide greater constancy of the exposed suppository area for dissolution. The apparatus consisted of a glass bead-bed containing the suppository. A continuous flow of liquid was passed through the bead-bed at a constant rate. Direct contact of the suppository was maintained with the dissolution medium, confining the suppository within the beads.

Benzocaine↗
PubMed1991

A new method of dissolution in vitro, the "Bio-Dis" apparatus: comparison with the rotating bottle method and in vitro: in vivo correlations.

The aim was to study a new method of dissolution in vitro, the "Bio-Dis" apparatus, and to compare it with the classical rotating bottle method. Several theophylline controlled-release drug dosage forms were studied. Dissolution testing was performed in increasing pH in standard conditions and after treatment with peanut oil in order to simulate high fat meals and to correlate the in vitro percent dissolved with the in vivo results obtained. The in vivo study was carried out on three groups of healthy volunteers receiving each dosage form in a randomized order just before a high fat breakfast or in the fasting state. The in vitro percent dissolved obtained was compared with those published results obtained with rotating bottles. A linear relationship was established between these results. From the in vivo absorbed percentages calculated according to the Wagner-Nelson method, a linear relation was found between the in vivo percent absorbed and the in vitro percent dissolved in the different conditions. The relationships observed are similar for all the forms under both conditions. The "Bio-Dis" offers advantages over the rotating bottle method. The study reported allows this dissolution apparatus to be proposed as an alternative to the rotating bottle apparatus.

Biological Availability↗
PubMed1984

Automatic milking apparatus for the insufficient venous drainage of the replanted digit.

An automatic milking apparatus composed of a finger attachment and a pump to push out the air was devised in order to perform the forced drainage from replanted digits with insufficient venous drainage. Seven replanted digits with insufficient venous drainage after replantation were applied, and remarkable improvement was found in five digits. An interesting case is reported in which a replanted digit without venous anastomosis survived as a consequence of applying the milking apparatus. The advantages of our milking apparatus are also discussed.

Amputation, Traumatic↗
PubMed2003

Motion correction in MRI using an apparatus for dynamic angular position tracking (ADAPT).

Motion during MRI examinations is a serious problem that degrades the quality of the data (images) acquired. Motion can be corrected during the postprocessing of the data; however, this approach is suboptimal and is typically limited to in-plane or translational motion. An apparatus for dynamic angular position tracking (ADAPT) for prospective angular motion correction has been developed. This application is capable of "tracking" the scanned region of interest by performing dynamic adjustments of orientation of the scanning plane. The operation of the apparatus is based on deuterium MR spectroscopy and does not rely on the use of magnetic field gradients. Orientation-sensitive deuterium quadrupolar interaction in a single crystal attached to a subject is used to monitor the angular position in magnetic fields. Measurements are performed with an independent spectrometer channel in the background of the MRI scans. This apparatus is very cost- and time-efficient because it utilizes the hardware already available on many spectrometers and can be used in parallel with MRI scans. Potentially, rotations by a fraction of one degree can be easily corrected and the angular position information can be rapidly updated.

Artifacts↗
PubMed1993

Optimization of nonradioisotopic single strand conformation polymorphism analysis with a conventional minislab gel electrophoresis apparatus.

We have developed a means of nonradioisotopic single strand conformation polymorphism (nonRI-SSCP) analysis and applied it to the detection of a point mutation in the human tumor suppressor gene, p53. The method does not require any particular facilities or apparatus, such as a laboratory for radioactive materials, a large gel unit for sequencing, or a semiautomated electrophoresis system. This technique comprises amplification of DNA fragments by the PCR technique with specific oligonucleotide primers, denaturation, and electrophoresis on neutral polyacrylamide gels in a conventional minislab apparatus. The SSCP patterns on electrophoresis were detected with a commercially available silver stain method. We also evaluated various electrophoretic conditions for nonRI-SSCP analysis, such as the gel concentration and buffer components. A tris/glycine buffer system gave better resolution of SSCP bands. The SSCP patterns of different sized DNAs could be analyzed in a gradient polyacrylamide gel. Thus, nonRI-SSCP analysis with a conventional minislab gel electrophoresis apparatus can be satisfactorily substituted for a commonly used RI-SSCP technique.

Base Sequence↗
PubMed1994

Caffeine-induced calcium release in sea urchin eggs and the effect of continuous versus pulsed application on the mitotic apparatus.

Unfertilized and fertilized eggs of the sea urchins Strongylocentrotus purpuratus and Lytechinus pictus, injected with the fluorescent probe calcium green dextran (Molecular Probes, Inc.) and monitored with single cell fluorimetry, rarely responded to 10 mM caffeine, but with 20 mM caffeine they produced a transient rise in intracellular calcium. Unfertilized eggs of both species produced a sharp peak approximately 2/3 the height of the normal fertilization peak, with the L. pictus response usually slightly lower and more variable. Image-intensified video microscopy of S. purpuratus eggs showed that this release originated in the center of the egg as well as in the cortex. When caffeine was applied to fertilized eggs within 10-15 min after the fertilization peak, during the period of elevated calcium, the size of the resulting calcium release increased with the elapsed time between the peak and the time of caffeine application. For example, there was no release when caffeine was applied at the height of the peak. When caffeine was washed out after the calcium level returned to baseline, there was a secondary peak (in the absence of caffeine) whose size decreased in proportion to the elapsed time. The source of this secondary calcium release is not known. Caffeine applied after the fertilization peak had returned to baseline produced a transient peak that was not followed by a secondary peak. The caffeine response gradually increased during the cell cycle. Although 10 mM caffeine did not produce a measurable calcium release, light microscopy of fixed and sectioned material showed that fertilized eggs incubated throughout the cell cycle in 7-10 mM caffeine-sea water had greatly reduced numbers of microtubules. Eggs treated at prometaphase with 10 mM caffeine rapidly lost a formed mitotic apparatus by shortening of the spindle and movement of the two centrosomes to the metaphase plate. Within 15 min all the mitotic apparatus-associated vesicles, which are known to sequester calcium, aggregated into two dense spheres of packed membranes located at the sites of the former asters. Microtubules and asters rapidly recovered when caffeine was removed. These observations suggest: (1) that the caffeine-sensitive store contributes to the fertilization calcium release and is an important sink for calcium after the fertilization peak, (2) that the caffeine-sensitive store in unfertilized eggs is located in the central part of the egg as well as in the cortex, and (3) that the caffeine-sensitive store is associated with the membrane system of the mitotic apparatus and may serve as a regulator of microtubule polymerization.

Animals↗
PubMed1997

Agrin-induced postsynaptic-like apparatus in skeletal muscle fibers in vivo.

We find that when extrajunctional regions of denervated soleus muscles in adult rats are transfected with cDNA encoding rat agrin isoform Y4Z8, which is normally secreted by motor neurons at adult neuromuscular junctions, the myofibers express and secrete the neural agrin. Muscle fibers in the vicinity of transfection form at their surface specialized areas having extracellular, plasma membrane, and cytoplasmic protein aggregates, narrow and deep plasma membrane infoldings, and an accumulation of myonuclei, all of which are characteristic of the postsynaptic apparatus at neuromuscular junctions. We conclude that at ectopic neuromuscular junctions that form in the extrajunctional region of denervated adult soleus muscles after implantation of a foreign nerve, a single neural-derived factor, agrin, is sufficient not only to cause protein aggregation in the early stages of postsynaptic apparatus formation, as predicted by the agrin hypothesis, but also to bring about changes in conformation of the muscle fiber surface and distribution of organelles which appear as the apparatus reaches maturity.

Agrin↗
PubMed1994

Can fibroblast growth factors substitute for bovine pituitary extracts in culture systems for hair apparatus cells?

The effects of acidic and basic fibroblast growth factors (aFGF and bFGF, respectively) on proliferation and differentiation of cultured hair apparatus cells were examined using bovine pituitary extract (BPE)-free media. The importance of FGFs as growth factors in BPE was also examined. Both FGFs and BPE stimulated cell proliferation and induced cell differentiation into several subpopulations corresponding to those of in vivo cell layers of the hair apparatus. Heparin enhanced the mitogenic activity of aFGF, but it did no affect that of bFGF. Heparin also partially inhibited or postponed the occurrence of cell differentiation induced by aFGF. Both aFGF- and bFGF-like proteins were detected in BPE by Western immunoblotting. BPE treated with anti-aFGF and/or anti-bFGF antibodies retained a significant mitogenic activity, although the mitogenic activities of FGFs were inhibited by their own specific antibodies. These results suggest that growth factors other than FGFs for cultured hair apparatus cells exist in BPE, although FGFs might substitute for BPE in this culture system as they stimulated cell proliferation and induced cell differentiation.

Animals↗
PubMed1992

Effects of cepharanthine and minoxidil on proliferation, differentiation and keratinization of cultured cells from the murine hair apparatus.

The effects of cepharanthine and minoxidil on proliferation, differentiation and keratinization of cultured cells from the murine hair apparatus were examined electron microscopically. Both cepharanthine and minoxidil stimulated cell proliferation and delayed initiation of differentiation and keratinization of the cultured cells. On day 6, most control cells (87%) cultured in a 0.03 mM calcium medium without cepharanthine and minoxidil were differentiated into several subpopulations corresponding to those of in vivo cell layers of the hair apparatus, while most of the cells cultured with cepharanthine (71%) or minoxidil (70%) were still immature. On day 13, the number of degenerated cells increased (63%) in the control culture, whereas in the culture treated with cepharanthine or minoxidil, cell degeneration scarcely occurred (5% and 8%, respectively). Differentiated cells having tonofilaments were often observed in the cepharanthine- and minoxidil-treated cultures (76% and 72%, respectively). Elevation of extracellular calcium up to 1.0 mM induced keratinization (34%) in the control culture on day 6, while no keratinized cells were observed in the cepharanthine- or minoxidil-treated culture. On day 13 keratinization similarly occurred in the cultures with cepharanthine (30%) or minoxidil (48%). These results show that both cepharanthine and minoxidil may directly influence proliferation, differentiation and keratinization of cultured cells from the hair apparatus.

Alkaloids↗
PubMed1987

An inexpensive dual-excitation apparatus for fluorescence microscopy.

Ion sensitive indicator molecules can be employed in conjunction with fluorescence microscopy in single cells to measure rapid changes in the intracellular concentration of several ionic species. A number of these probes (e.g. fura-2) require the capability of measuring emission intensity at two excitation wavelengths to quantitate properly intracellular ion concentration. We have developed a simple dual-excitation apparatus for use in such applications. The apparatus switches the excitation filter within 150 ms. This economical apparatus is well suited in situations where the ionic concentration of interest is changing relatively slowly. Moreover, by synchronizing the device's action with an external stimulus, rapid and reproducible ionic changes in excitable tissue also can be measured.

Animals↗
PubMed1988

Evaluation of endoscopic hemostasis using an improved clipping apparatus.

Endoscopic clipping hemostasis (ECH) is an effective method to control bleeding. However, ordinary clipping apparatuses have not been widely adopted because of several disadvantages. Accordingly, we developed an improved ECH apparatus that can be used during a general endoscopic examination without requiring an assistant. It is not only easy to operate but also ensures safe and effective hemostasis. The ECH apparatus was employed in 80 patients between February 1983 and August 1987 at the Sakura National Hospital. Fifty-one of the patients had upper gastrointestinal bleeding; in 29, preventive clipping was performed after polypectomy. Permanent hemostasis was maintained in 43 (84.3%) of the patients with upper gastrointestinal bleeding, and no bleeding was recognized in any of the 29 patients treated with prophylactic clipping following polypectomy.

Endoscopes↗