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At least 739 records · Page 41Linked to original sources
PubMed1980

An improved apparatus for blood perfusion of the canine cerebral vasculature.

An improved perfusion apparatus is described which consists of a membrane oxygenator, roller pump, reservoir, heat exchanger, blood filter, and inert tubing. Heparinized blood may be used and is delivered at flow rates from 10 to 250 ml/min. Dogs are anesthetized with halothane and their cerebral arterial blood supply isolated by the method of Gilboe et al. (8). When the canine brain is perfused for 5 hr using the described apparatus, the rates of cerebral oxygen and glucose consumption are 5.19 +/- 0.12 mg/100 g/min and 39.9 +/- 6.5 mumol/100 g/min, respectively. Of the total glucose consumed by the brain, about 1/4 is contributed by the erythrocytes. An equivalent of about 9% of the consumed glucose is returned to the blood as lactate. Electron microscopic examination of cerebral cortex samples reveals no differences between 5-hr perfused brain and appropriate nonperfused controls. It is concluded that the apparatus is a useful system for organ perfusion and that the canine brain perfused by this method remains physiologically and metabolically active for at least 5 hr.

Animals↗
PubMed1991

Trichophyton rubrum invasion of human hair apparatus in tinea capitis and tinea barbae: light- and electron microscopic study.

We have previously reported morphological changes of Trichophyton violaceum and Microsporum canis in hair apparatuses in tinea capitis. To investigate the morphology of Trichophyton rubrum in the human hair apparatus, two cases of tinea capitis and one case of tinea barbae were examined by light- and electron microscopy. The fungal elements, which were located in the lower keratogenous zone, showed non-septate hyphae in the outer part of the hair cortex. With the upward development of the hair layers, some hyphae invaded the keratinized hair cuticle and keratinized inner root sheath and were transformed into arthrospores. Some hyphae remaining in the hair cortex were also transformed into arthrospores, while other hyphae in the hair cortex did not survive, but degenerated. In T. rubrum hair infection, there is a distinct relationship between the morphological changes of the fungi and the hair cell differentiation as seen in T. violaceum and M. canis infections. However, T. rubrum displays unique morphological changes, which are different from those of T. violaceum and M. canis, in hair apparatuses.

Adult↗
PubMed2004

Effects of lindane on the photosynthetic apparatus of the cyanobacterium Anabaena: fluorescence induction studies and immunolocalization of ferredoxin-NADP+ reductase.

INTENTION, GOAL, SCOPE, BACKGROUND: Cyanobacteria have the natural ability to degrade moderate amounts of organic pollutants. However, when pollutant concentration exceeds the level of tolerance, bleaching of the cells and death occur within 24 hours. Under stress conditions, cyanobacterial response includes the short-term adaptation of the photosynthetic apparatus to light quality, named state transitions. Moreover, prolonged stresses produce changes in the functional organization of phycobilisomes and in the core-complexes of both photosystems, which can result in large changes in the PS II fluorescence yield. The localization of ferredoxin-NADP+ reductase (FNR) at the ends of some peripheral rods of the cyanobacterial phycobilisomes, makes this protein a useful marker to check phycobilisome integrity. OBJECTIVE: The goal of this work is to improve the knowledge of the mechanism of action of a very potent pesticide, lindane (gamma-hexaclorociclohexane), in the cyanobacterium Anabaena sp., which can be considered a potential candidate for bioremediation of pesticides. We have studied the effect of lindane on the photosynthetic apparatus of Anabaena using fluorescence induction studies. As ferredoxin-NADP+ reductase plays a key role in the response to oxidative stress in several systems, changes in synthesis, degradation and activity of FNR were analyzed. Immunolocalization of this enzyme was used as a marker of phycobilisome integrity. The knowledge of the changes caused by lindane in the photosynthetic apparatus is essential for rational further design of genetically-modified cyanobacteria with improved biorremediation abilities. METHODS: Polyphasic chlorophyll a fluorescence rise measurements (OJIP) have been used to evaluate the vitality and stress adaptation of the nitrogen-fixing cyanobacterium Anabaena PCC 7119 in the presence of increasing concentrations of lindane. Effects of the pesticide on the ultrastructure have been investigated by electron microscopy, and FNR has been used as a marker of phycobilisome integrity. RESULTS AND DISCUSSION: Cultures of Anabaena sp. treated with moderate amounts of lindane showed a decrease in growth rate followed by a recovery after 72 hours of pesticide treatment. Concentrations of lindane below 5 ppm increased the photosynthetic performance and activity of the cells. Higher amounts of pesticide caused a decrease in these activities which seems to be due to a non-competitive inhibition of PS II. Active PS II units are converted into non-QA reducing, so called heat sink centers. Specific activity and amount of FNR in lindane-treated cells were similar to the values measured in control cultures. Release of FNR from the thylakoid after 48 hours of exposure to 5 ppm of lindane towards the cytoplasm was detected by immunogold labeling and electron microscopy. CONCLUSIONS: From these results, we conclude that the photosynthetic performance and activity of the cells are slightly increased in the presence of lindane up to 5 ppm. Moreover, in those conditions, lindane did not produce significant changes in the synthesis, degradation or activity of FNR. The high capability of Anabaena to tolerate lindane makes this cyanobacterium a good candidate for phytoremediation of polluted areas. RECOMMENDATION AND OUTLOOK: The results of this study show that cultures of Anabaena PCC 7119 tolerate lindane up to 5 ppm, without significant changes in the photosynthetic vitality index of the cells. However, a slight increase in phycobiliprotein synthesis is observed, which is related to total protein content. This change might be due to degradation of proteins less stable than phycobiliproteins. An identification of the proteins with altered expression pattern in the presence of the pesticide remains the subject of further work and will provide valuable information for the preparation of strains which are highly tolerant to lindane.

Anabaena↗
PubMed2006

An apparatus for studying the response of cultured endothelial cells to stresses.

In order to simulate the hemodynamic environment of human arteries in vivo, we designed a laminar flow apparatus which can precisely simulate the normal stress and shear stress to which cultured endothelial cells are exposed. Under both normal and abnormal physiological conditions, this apparatus can accurately control and adjust the values of normal stress and shear stress and the frequency of pulse waves, as well as the amplitude of pulsatile flow. This in vitro apparatus provides an experimental platform for studying the response of the biological characteristics of cultured endothelial cells in a hemodynamic environment.

Blood Flow Velocity↗
PubMed2005

A comparative study of extraction apparatus in HPLC analysis of ochratoxin A in muscle.

Ochratoxin A (OTA) is a secondary fungal metabolite produced by several moulds, mainly by Aspergillus ochraceus and by Penicillium verrucosum, that occurs in meat products. The aim of this work was to optimize an efficient extraction procedure for the determination of OTA in muscle tissue in order to assess its occurrence in meat samples. Three different apparatus, a Waring blender, a switching apparatus, and an ultrasonic processor, were evaluated to verify the efficiency of extraction. The analytical methods proposed involve the extraction with chloroform-orthophosphoric acid, cleanup through an immunoaffinity column, high-performance liquid chromatography/fluorescence detection for separation and identification of OTA, and confirmation with liquid chromatography/FD after methylation of OTA in muscle tissue. The limit of quantification of the proposed method was 0.04 microg kg(-1). Recoveries of OTA, using switching apparatus, ranged from 90.3 to 103.2% for chicken muscle spiked at 2.4 and 0.48 microg kg(-1), respectively, with a within-day relative standard deviation of 17 and 15.3%. The proposed method was applied to 38 chicken, swine, and turkey muscle samples and the presence of OTA was confirmed in five samples. Finally, the estimated daily intake of OTA in this study was between 23 pg kg(-1) body weight per day for swine samples and 18 pg kg(-1) body weight per day for turkey samples.

Animals↗
PubMed2006

Roles of the sister chromatid cohesion apparatus in gene expression, development, and human syndromes.

The sister chromatid cohesion apparatus mediates physical pairing of duplicated chromosomes. This pairing is essential for appropriate distribution of chromosomes into the daughter cells upon cell division. Recent evidence shows that the cohesion apparatus, which is a significant structural component of chromosomes during interphase, also affects gene expression and development. The Cornelia de Lange (CdLS) and Roberts/SC phocomelia (RBS/SC) genetic syndromes in humans are caused by mutations affecting components of the cohesion apparatus. Studies in Drosophila suggest that effects on gene expression are most likely responsible for developmental alterations in CdLS. Effects on chromatid cohesion are apparent in RBS/SC syndrome, but data from yeast and Drosophila point to the likelihood that changes in expression of genes located in heterochromatin could contribute to the developmental deficits.

Abnormalities, Multiple↗
PubMed1986

Potential in-hospital modes of transmission of Legionella pneumophila. Demonstration experiments for dissemination by showers, humidifiers, and rinsing of ventilation bag apparatus.

The mode of transmission of nosocomial legionellosis remains uncertain. Aerosolization of Legionella pneumophila by showers, humidifiers, and respiratory equipment rinsed in tap water was evaluated using plate-settling culture and air aspirator methods. All protocols simulated the actual hospital setting including use of humidifier equipment used in hospital patient rooms and water from faucets and showerheads in hospitals with nosocomial Legionnaires' disease. Protocols for humidifier and shower experiments mimicked the procedure actually used in hospitals by health care personnel. Showering failed to produce aerosols of L. pneumophila; however, portable humidifiers readily generated aerosols of L. pneumophila that disseminated throughout a two-bed patient room. Intensity of aerosolization directly correlated with the degree of L. pneumophila contamination of the tap water used to fill the humidifier. Rinsing of ventilation bag apparatus with tap water led to isolation of L. pneumophila from culture plates after the ventilation bags were squeezed. Thus, L. pneumophila could be aerosolized or directly instilled into a patient's bronchial tree following routine measures for cleaning ventilation bag apparatus with tap water. On the basis of these results, the use of humidifiers filled with tap water has been discontinued and sterile water is recommended for rinsing ventilation bag apparatus and tubing.

Aerosols↗
PubMed1978

A simplified polyacrylamide gel electrophoresis apparatus for simultaneous application of multiple buffer systems or detergent combinations.

A previous design of an apparatus for the simultaneous fractionation by polyacrylamide gel electrophoresis in 10 different buffer systems (1) was replaced by a greatly simplified new design, employing small, cylindrical buffer partitions within the lower buffer reservoir and/or upper buffer reservoir of a conventional, temperature-regulated polyacrylamide gel electrophoresis apparatus for cylindrical gels. The apparatus was tested in application to the problem of simultaneous polyacrylamide gel electrophoresis in different buffer systems with the purpose of optimizing the operative pH for a particular fractionation problem. It was also applied to fractionations in a single buffer system to which various combinations of ionic and nonionic detergents were admixed.

Adenylyl Cyclases↗
PubMed1983

A highly simplified horizontal electrophoretic apparatus including a handmade power supply and its application.

An extremely simplified electrophoretic apparatus and power supply have been introduced for horizontal (flat-bed) electrophoresis and isoelectrofocusing. The electrophoretic apparatus consisted of a buffer tray with a plastic food container in which a gel glass plate attached to two removable bar electrodes with rubber bands was submerged. The removable bar electrode consisted of an acrylic bar plate containing holes to which platinum wire was attached. The power supply simply contained a bridge diode, fuse, capacitor, and output terminals which were also assembled in a small plastic food container. Since the output electric potential of the power supply was constant pulse dc 90 V (in the absence of a capacitor) or 140 V (in the presence of a capacitor) at 100 V ac input, the following equation was experimentally derived to control the electrophoretic current: I (mA) = aD + b, I (mA) = kF. In these, I, a, D, k, and F were electrophoretic current, constant, distance between positive and negative electrodes, constant, and dilution factor of the electrophoretic buffer which was proportional to buffer concentration, respectively. These equations indicate that electrophoretic current can be controlled by the changes of electrode distance and buffer dilution. The latter equation was theoretically derived from the theory of electrolyte conductance and Ohm's law and was simulated with a microcomputer. With the apparatus and power supply, agarose gel electrophoresis of DNA and discontinuous polyacrylamide gel electrophoresis of protein samples were successfully carried out. The construction and assembly of the system can be easily carried out in a laboratory without any special tools and machines. The high cost performance, compactness, and simplicity were superior points of this system. The applicability of the equation I = kF to tube gel and vertical slab gel electrophoresis was tested. The rheostat usage made it easy for the power supply to change dc-output potential without spoiling its cost performance. A convenient sample slot-former and gel preparation with it are also described.

Computers↗
PubMed1992

Application of a novel apparatus, the quartz chemical analyzer, to the determination of endotoxin in blood.

A novel apparatus called a quartz chemical analyzer (QCA) has been developed using a quartz crystal resonator. This apparatus measures sample viscosity changes based on resonant frequency changes of the quartz crystal. The apparatus was used to determine bacterial endotoxin concentrations by monitoring the gelation reaction of Limulus amebocyte lysate. The QCA determined endotoxin concentrations with good accuracy and reproducibility in the range of 0.001-3 EU/ml for endotoxin standard (JP XII). For endotoxin determination in human whole blood and plasma samples, the inhibitory reaction was eliminated by pretreatment of a fourfold dilution at 60 degrees C and incubation for 30 min. There are many advantages of the QCA method compared with the turbidimetric and chromogenic methods. For example, QCA can measure sample viscosity changes with high sensitivity and accuracy because QCA detects minor resonant frequency changes and the frequency data give a numerical value for easy quantitation. QCA can examine turbid samples, and the required quantities of samples and reagents are small, since the quartz crystal detects sample viscosity changes directly. The endotoxin determination time may be shortened by raising the reaction temperature, and QCA can detect other types of coagulation reactions.

Antithrombin III↗
PubMed1992

A new system for bilayer lipid membrane capacitance measurements: method, apparatus and applications.

A new method and a new apparatus for capacitance measurements on bilayer lipid membranes are described. The membrane is charged and discharged with a constant current during the measurement. The charge-discharge cycle duration, which is proportional to the membrane capacitance, is measured. The measured time period is converted into a binary number by digital systems and then this number is either further converted into a constant capacity-proportional voltage or read out by the computer. The apparatus makes it possible to measure the capacitances of voltage-polarized membranes. Application of the apparatus to capacitance measurements of bilayer lipid membranes during their potential on the capacitance is presented. The capacitances of membranes stimulated by rectangular voltage pulses and of those stimulated by a linearly varying potential were reported.

Lipid Bilayers↗
PubMed1989

Control of development of the oral apparatus of Paramecium during sexual reproduction: an embryological perspective.

This study shows that development of the new soma during sexual reproduction in ciliates can be conceptualized on the same basis as embryogenesis in multicellular organisms. In conjugating Paramecium, development of a new oral apparatus takes place during fertilization and the first three divisions of the zygotic nucleus and completes well before the postsexual cell undergoes the first cell fission. The control of oral development is analyzed by microsurgical removal of the zygotic nucleus or the postzygotic nuclei from conjugants. The enucleated exconjugants can pass through an early hurdle in oral development (the initiation of oral membranelle assembly) and subsequently develop an oral apparatus. Such oral apparatuses nevertheless exhibit structural and functional abnormalities including fragmentation and misalignment of oral membranelles, absence of the postoral microtubular bundle, reduction in the length of buccal cavity, and impaired phagocytosis. Other stomatogenic aspects, such as the arrangement of basal bodies in the oral membranelles, remain unaffected. The two groups of exconjugants, one derived from cells enucleated at the zygotic stage, and the other at the postzygotic stage, exhibit the same types of oral abnormality. We conclude that (i) the zygotic nucleus is not essential for the initiation of oral membranelle assembly. The existence of zygotic signals for subsequent oral development is not ruled out, but these are insufficient. (ii) Postzygotic nuclei, as well as maternal nuclei (the old somatic nucleus and meiotic derivatives of the germ nucleus), control oral development. This reveals a parallelism between postsexual development in ciliates and the early embryology of multicellular organisms, in their reliance on information provided by maternal, as well as early postzygotic nuclei. (iii) The activity of the old somatic nucleus alone is not sufficient for the later stages of oral development. Probably, some stomatogenic functions of the old somatic nucleus normally utilized for the later stages of oral development in binary fission are inactivated during sexual reproduction. Alternatively, the old somatic nucleus may rely on some critical conditions prescribed by the postzygotic nuclei in order to act.

Animals↗
PubMed1989

A mechanical apparatus with microprocessor controlled stress profile for cyclic compression of cultured articular cartilage explants.

An apparatus was designed for mechanical compression of cultured articular cartilage explants with acylindrical plain-ended loading head (diameter 2-5 mm) driven by a stepping motor. A load cell under the culture dish was applied for feedback regulation utilizing a microprocessor-based control unit. The operating programs allowed either continuous or cyclic loading, the latter with adjustable loading/resting ratio. The improvements in the present design compared with previously described apparatuses for similar purposes include: (1) the accurately controlled compression by a load cell and a rapid feedback circuit; (2) the wide range of selectable stresses (25 kPa-12.5 MPa) with both continuous and cyclic loading modes; (3) the ability to handle cycles as short as 1 s with 15 ms peak loading phase. Using a 4 s cycle and 0.5 MPa load for 1.5 h resulted in a significantly enhanced incorporation of radiosulphate in cultured bovine articular cartilage explants, suggesting a stimulation of proteoglycan synthesis. Light and scanning electron microscopic examinations revealed a slight depression and superficial alterations in cartilage structure at the impact site following high pressures. We expect that this apparatus will help in revealing how articular cartilage tissue and chondrocytes respond to external mechanical stimuli.

Animals↗
PubMed1995

A new dynamic testing apparatus to study glenohumeral joint motion.

A dynamic shoulder testing apparatus has been developed to examine unconstrained glenohumeral joint motion in human cadaveric full upper extremities. Six computer-controlled hydraulic cylinders are used to simulate muscle action, while the corresponding tendon excursions and six-degree of freedom joint motion are measured. Trials showed that the testing apparatus creates highly reproducible glenohumeral joint motion in the scapular plane. The apparatus can be used to examine the function of the shoulder musculature and capsuloligamentous structures during normal and pathologic motion at the glenohumeral joint.

Computers↗
PubMed1986

An improved incubation apparatus for Western blots used for the detection of antinuclear antibodies.

To facilitate the use of Western blots for the detection of antibodies, we have developed an incubation apparatus. The use of this apparatus simplifies the incubation of blots with antisera, permits the testing of large numbers of sera and eliminates artefacts caused by the use of loose strips. The introduction of a pressure bag in the lower lid of the apparatus secures a steady pressure over the entire blot, a feature lacking in currently available commercial equipment. The detection of antinuclear antibodies is presented as an example of the use of this incubator.

Antigen-Antibody Complex↗
PubMed1995

Use of the Pannell-Milstein roller bottle apparatus to produce high concentrations of the CSF-1, the mouse macrophage growth factor.

A simple roller bottle apparatus for growing B cell hybridomas in dialysis tubing yields high concentrations of monoclonal antibodies (Pannell and Milstein, J. Immunol. Methods (1992) 146, 43-48). Here we describe an adaptation of this apparatus for the simple production of high concentrations of the mouse macrophage specific growth factor, CSF-1. This apparatus appears to have general applicability for the production of other secreted cytokines.

Agar↗
PubMed1992

Apparatus for the mechanical testing of maxillofacial prosthetic adhesives.

The use of adhesives to retain facial prosthesis remains controversial. This controversy arises in part from a lack of information on the biomechanical performance of this group of materials. No standard exists for maxillofacial prosthetic adhesives. This study describes the rationale for and design of an apparatus for testing maxillofacial and other skin adhesives. The apparatus provides for tensile, torsion, and combined tensile-torsion tests in a hard machine test. The results of the calibration studies of the apparatus are discussed.

Adhesiveness↗
PubMed1983

A restraining apparatus for Chelonians.

A restraining system for the head and neck of tortoises or turtles is described which, when associated with a standard electrode carrier, can be used as a stereotaxic apparatus for Chelonians. The apparatus designed has two basic systems: one for holding the neck, the other for holding the head. They are associated with a standard electrode carrier in a common platform. Restraining apparatus.

Animals↗