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PubMed1998

The protein translocation apparatus contributes to determining the topology of an integral membrane protein in Escherichia coli.

The assembly of integral membrane proteins is determined by features of these proteins and the protein translocation apparatus. We used alkaline phosphatase fusions to the membrane protein MalF to investigate the role of the protein translocation machinery in the arrangement of proteins in the cytoplasmic membrane of Escherichia coli. In particular, we studied the effects of prlA mutations on membrane protein topology. These mutations lie in the secY gene, which encodes a core component of the protein translocation apparatus. We find that the topology of some of the fusion proteins is changed and, in one case, is completely inverted in prlA mutants. We discuss the mechanism of prlA-mediated export and the role of the protein translocation apparatus in contributing to membrane protein topology.

Bacterial Proteins↗
PubMed1977

Evaluation of Federal man tests for self-contained breathing apparatus.

The transient pulmonary responses to four short duration man tests used in the Federal approval of breathing apparatus were measured. The pulmonary ventilation dropped 30 percent in the first thirty seconds in the periods assigned for samples and readings which were immediately preceded by work. A physiological deficit was incurred during the short duration man tests which meant that less O2 and ventilation were required when compared to steady state responses shown on approval tests. The scheduled man test activities for short duration breathing apparatus should be revised and made more vigorous to match the intended use of escape apparatus.

Adult↗
PubMed1989

An apparatus and a method for determining the slip resistance of shoes and floors by simulation of human foot motions.

An apparatus to measure the coefficient of kinetic friction (mu k) between the shoe sole and the underfoot surface was constructed, and a method including criteria to evaluate the risk of slipping during walking was developed. The apparatus is a prototype stationary step simulator capable of simulating the movements of a human foot and the forces applied to the underfoot surface during an actual slip, and the drainage capability of the contact surface between the shoe sole and the flooring when different lubricants or contaminants are used. The apparatus consists of a movable artificial foot controlled by a computer with the aid of three hydraulic cylinders. The frictional force (F mu), the normal force (FN) and their ratio (mu k = F mu/FN) are measured with a two-way force platform when the foot slides along its surface. Two separate gait patterns, heel-side (mu k 1) and sole-slide (mu k 2) gait pattern, are used for the evaluations. The method classifies studied shoe, lubricant and underfoot surface combinations into five slip resistance classes according to the measured mu k 1. The slip resistance assessments are specified with some complementary safety criteria, e.g., the ratio mu k 1/mu k 2. The reliability of the developed measurement method was assessed in an international comparison test. According to available results discussed in this paper, our method seems to be valid and the slip resistance measurements seem to be repeatable.

Accidental Falls↗
PubMed1995

Dead space in the breathing apparatus; interaction with ventilation.

Dead space in breathing apparatus may cause increased ventilation and/or CO2 retention. Interactions between ventilation and dead space were tested in the breathing apparatus of three divers: a full face mask with an oro-nasal cup (AGA), a full face mask without an oro-nasal cup (EXO-26) but designed to minimize dead space, and one mouthpiece. Experiments were performed at three depths; 0, 30 and 45 m seawater (msw). The breathing gas was air except at 30 msw where it was 36 O2 in N2. Five certified SCUBA divers were exercised at three levels (0, 50 and 100 W). Ventilation and gas exchange were measured. The dead space in the AGA mask was not influenced by either depth or exercise (mean 0.201). The mean dead space of the EXO-26 was 0.341, but it increased with exercise (p < 0.001) and decreased with depth (p < 0.03). Since the dead space can vary with ventilation levels it is not sufficient to test breathing apparatus only at rest as is required by the US National Institute of Occupational Safety and Health. The mean ventilation with the EXO-26 was higher than with the AGA by 10% at 50 W (p < 0.05) and by 12% (p < 0.01) at 100 W. The same comparison for end-tidal CO2 showed mean increase by 0.30 kPa at the 100-W workload (P < 0.05); changes at other workloads were not statistically significant. Comparisons of the mean inspired PCO2 to the maximum values considered acceptable by various organizations showed that the mouthpiece was always acceptable, the AGA mask was marginally acceptable or better, while sometimes the EXO-26 was not acceptable.

Adult↗
PubMedDate not supplied

Portable biofeedback apparatus for treatment of anal sphincter dystonia in childhood soiling and constipation.

Biofeedback is an effective treatment for anal sphincter dysfunction in many cases of childhood constipation and soiling. Conventional methodologies centre on clinic-based manometric apparatus but are compromised by equipment being thinly available and practice sessions often infrequent. To counter these shortcomings, we have designed a portable anorectal biofeedback apparatus (the Easograph) for domiciliary use. It can be lent to families, enabling carers to mediate what is an intrinsically sensitive procedure. In this paper, we provide a technical description of the device which is based on an inexpensive pressure transducer. Casework experience suggests it is reliable in operation and readily understood by users. In a pilot study of eight patients treated with the apparatus, five achieved bowel continence after lifelong soiling in one to eight weeks of daily practice. We believe this is an innovative approach that has good potential for treating faecal retentive and expulsive disorders in childhood associated with poor anal sphincter control.

Anal Canal↗
PubMed1985

Characterization and immunocytochemical distribution of calmodulin in higher plant endosperm cells: localization in the mitotic apparatus.

In this study we have examined the immunocytochemical distribution of calmodulin during mitosis of higher plant endosperm cells. Spindle development in these cells occurs without centrioles. Instead, asterlike microtubule converging centers appear to be involved in establishing spindle polarity. By indirect immunofluorescence and immunogold staining methods with anti-calmodulin antibodies, we found endosperm calmodulin to be associated with the mitotic apparatus, particularly with asterlike and/or polar microtubule converging centers and kinetochore microtubules, in an immunocytochemical pattern distinct from that of tubulin. In addition, endosperm calmodulin and calcium showed analogous distribution profiles during mitosis. Previous reports have demonstrated that calmodulin is associated with the mitotic apparatus in animal cells. The present observation that calmodulin is also associated with the mitotic apparatus in acentriolar, higher plant endosperm cells suggests that some of the regulatory mechanisms involved in spindle formation, microtubule disassembly, and chromosome movement in plant cells may be similar to those in animal cells. However, unlike animal cell calmodulin, endosperm calmodulin appears to associate with kinetochore microtubules throughout mitosis, which suggests a specialized role for higher plant calmodulin in the regulation of kinetochore microtubule dynamics.

Anaphase↗
PubMed1991

Sec15 protein, an essential component of the exocytotic apparatus, is associated with the plasma membrane and with a soluble 19.5S particle.

SEC15 encodes a 116-kD protein that is essential for vesicular traffic from the Golgi apparatus to the cell surface in yeast. Although the sequence predicts a largely hydrophilic protein, a portion (23%) of Sec15p is found in association with the plasma membrane. The remainder is not associated with a membrane but is found in a 19.5S particle which is not dissociated by 0.5 M NaCl. Sec15p may attach directly to the plasma membrane since it is not found on the Golgi apparatus nor on the secretory vesicle precursors to the plasma membrane. Loss of function of most of the late-acting sec gene products does not alter the distribution of Sec15p. However, the sec8-9 mutation and to a lesser extent the sec10-2 mutation result in a shift of Sec15p to the plasma membrane, suggesting a role for these gene products in the regulation of the Sec15p membrane attachment/detachment processes. Depletion of Sec15p by repression of synthesis indicates that the plasma membrane bound pool is the most stable. During the course of these studies we have found that two activities associated with the yeast Golgi apparatus, Kex2 endopeptidase and GDPase, are in separable subcompartments.

Cell Fractionation↗
PubMed1967

Flagellar motion and fine structure of the flagellar apparatus in Chlamydomonas.

The biflagellate alga Chlamydomonas reinhardi was studied with the light and electron microscopes to determine the behavior of flagella in the living cell and the structure of the basal apparatus of the flagella. During normal forward swimming the flagella beat synchronously in the same plane, as in the human swimmer's breast stroke. The form of beat is like that of cilia. Occasionally cells swim backward with the flagella undulating and trailing the cell. Thus the same flagellar apparatus produces two types of motion. The central pair of fibers of both flagella appear to lie in the same plane, which coincides with the plane of beat. The two basal bodies lie in a V configuration and are joined at the top by a striated fiber and at the bottom by two smaller fibers. From the area between the basal bodies four bands of microtubules, each containing four tubules, radiate in an X-shaped pattern, diverge, and pass under the cell membrane. Details of the complex arrangement of tubules near the basal bodies are described. It seems probable that the connecting fibers and the microtubules play structural roles and thereby maintain the alignment of the flagellar apparatus. The relation of striated fibers and microtubules to cilia and flagella is reviewed, particularly in phytoflagellates and protozoa. Structures observed in the transitional region between the basal body and flagellar shaft are described and their occurrence is reviewed. Details of structure of the flagellar shaft and flagellar tip are described, and the latter is reviewed in detail.

Eukaryota↗
PubMed1967

The mechanism of action of colchicine. Colchicine binding to sea urchin eggs and the mitotic apparatus.

Colchicine forms a complex in vivo with a protein present in fertilized or unfertilized sea urchin eggs; similar binding was obtained in vitro with the soluble fraction from egg homogenates. Kinetic parameters and binding equilibrium constant were essentially the same in vivo and in vitro. The binding site protein was shown to have a sedimentation constant of 6S by zone centrifugation. The protein was present in extracts of the isolated mitotic apparatus at a concentration which was several times higher than in whole-egg homogenates. It was extracted from the mitotic apparatus at low ionic strength under conditions which lead to the disappearance of microtubules. No binding could be detected to the 27S protein, previously described by Kane, which is a major protein component of the isolated mitotic apparatus. The properties of the colchicine-bindinG protein, (binding constant, sedimentation constant, Sephadex elution volume) are similar to those obtained with the protein from mammalian cells, sea-urchin sperm tails, and brain tissue, and thus support the conclusion that the protein is a subunit of microtubules.

Animals↗
PubMed1970

Evidence for the participation of the Golgi apparatus in the intracellular transport of nascent albumin in the liver cell.

A comparative biochemical and radioautographic in vivo study was performed to identify the site of synthesis and route of migration of albumin in the parenchymal liver cell after labeling with leucine-(14)C or leucine-(3)H via the portal vein. Free cytoplasmic ribosomes, membrane-bound ribosomes, rough- and smooth-surfaced microsomes, and Golgi membranes were isolated. The purity of the Golgi fraction was examined morphologically and biochemically. After administration of leucine-(14)C, labeled albumin was extracted, and the sequence of transport was followed from one fraction to the other. Approximately 2 min after the intravenous injection, bound ribosomes displayed a maximal rate of leucine-(14)C incorporation into albumin. 4 min later, a peak was reached for rough microsomes. Corresponding maximal activities for smooth microsomes were recorded at 15 min, and for the Golgi apparatus at approximately 20 min. The relative amount of albumin, calculated on a membrane protein basis, was higher in the Golgi fraction than in the microsomes. By radioautography the silver grains were preferentially localized over the rough-surfaced endoplasmic reticulum at the 5 min interval. Apparent activity in the Golgi zone was noted 9 min after the injection; at 15 and 20 min, the majority of the grains were found in this location. Many of the grains associated with the Golgi apparatus were located over Golgi vacuoles containing 300-800 A electron-opaque bodies. It is concluded that albumin is synthesized on bound ribosomes, subsequently is transferred to the cavities of rough-surfaced endoplasmic reticulum, and then undergoes migration to the smooth-surfaced endoplasmic reticulum and the Golgi apparatus. In the latter organelle, albumin can be expected to be segregated together with very low density lipoprotein in vacuoles known to move toward the sinusoidal portion of the cell and release their content to the blood.

Animals↗
PubMed1977

Changes of the cell surface and of the digestive apparatus of Dictyostelium discoideum during the staruation period triggering aggregation.

The effects of starvation on the cell morphology of Dictyostelium discoideum were studied with different cytochemical techniques, and with a morphometric method by which the surface areas of the cell membrane and of the digestive system can be determined. During the first 2 h, the cell membrane becomes very wrinkled and many phagocytic cups and filopods are formed. These changes are in accord with the 40 percent increase in the cell surface area to cytoplasmic volume ratio observed, which is mainly due to a strong decrease in the cytoplasmic volume. At this time of starvation, cells are able to ingest twice as many yeast as during growth. Afterwards, while the phagocytic ability decreases, the phagocytic cups disappear, and all the cells become bristled with many thin filopods. In spite of these morphological changes, no quantitative or topological differences have been observed concerning the polysaccharide content of the plasma membrane, whether it was stained with phosphotungstic acid, silver proteinate, or ruthenium red. During this time, the digestive vacuoles imbricate one into the other. Part of the vacuoles are degraded by this process, thus leading to an atrophy of the digestive apparatus. The digestive apparatus is progressively replaced by an autophagic system. Polysaccharide stainings and morphological observations show that the cytosegresomes seem to originate from the food vacuoles which flatten and sequester portions of cytoplasm. After 5 h of starvation, the digestive system is entirely transformed into an autophagic apparatus. The cell population appears to be homogeneous with respect to these changes. Therefore, potential precursors of prestalk and prespore cells were not observed.

Acid Phosphatase↗
PubMed2006

Focusing optics of a parallel beam CCD optical tomography apparatus for 3D radiation gel dosimetry.

Optical tomography of gel dosimeters is a promising and cost-effective avenue for quality control of radiotherapy treatments such as intensity-modulated radiotherapy (IMRT). Systems based on a laser coupled to a photodiode have so far shown the best results within the context of optical scanning of radiosensitive gels, but are very slow ( approximately 9 min per slice) and poorly suited to measurements that require many slices. Here, we describe a fast, three-dimensional (3D) optical computed tomography (optical-CT) apparatus, based on a broad, collimated beam, obtained from a high power LED and detected by a charged coupled detector (CCD). The main advantages of such a system are (i) an acquisition speed approximately two orders of magnitude higher than a laser-based system when 3D data are required, and (ii) a greater simplicity of design. This paper advances our previous work by introducing a new design of focusing optics, which take information from a suitably positioned focal plane and project an image onto the CCD. An analysis of the ray optics is presented, which explains the roles of telecentricity, focusing, acceptance angle and depth-of-field (DOF) in the formation of projections. A discussion of the approximation involved in measuring the line integrals required for filtered backprojection reconstruction is given. Experimental results demonstrate (i) the effect on projections of changing the position of the focal plane of the apparatus, (ii) how to measure the acceptance angle of the optics, and (iii) the ability of the new scanner to image both absorbing and scattering gel phantoms. The quality of reconstructed images is very promising and suggests that the new apparatus may be useful in a clinical setting for fast and accurate 3D dosimetry.

Equipment Design↗
PubMed2005

An inexpensive apparatus for growing photosynthetic microorganisms in exotic atmospheres.

Given the need for a light source, cyanobacteria and other photosynthetic microorganisms can be difficult and expensive to grow in large quantities. Lighted growth chambers and incubators typically cost 50-100% more than standard microbiological incubators. Self-shading of cells in liquid cultures prevents the growth of dense suspensions. Growing liquid cultures on a shaker table or lighted shaker incubator achieves greater cell densities, but adds considerably to the cost. For experiments in which gases other than air are required, the cost for conventional incubators increases even more. We describe an apparatus for growing photosynthetic organisms in exotic atmospheres that can be built relatively inexpensively (approximately 100 dollars U.S.) using parts available from typical hardware or department stores (e.g., Wal-mart or K-mart). The apparatus uses microfiltered air (or other gases) to aerate, agitate, and mix liquid cultures, thus achieving very high cell densities (A750 > 3). Because gases are delivered to individual culture tubes, a variety of gas mixes can be used without the need for enclosed chambers. The apparatus works with liquid cultures of unicellular and filamentous species, and also works with agar slants.

Atmosphere↗
PubMed1978

Dr Nooth and his apparatus. The role of carbon dioxide in medicine in the late eighteenth century.

The two earliest inhalers devised for the administration of ether anaesthesia in the U.K. (Hooper's and Squire's apparatus) both incorporated the bottom part of a Nooth's apparatus. This, which was once a household object, is now remembered only as a footnote in one or two specialist histories, and Nooth himself, who was a most distinguished and respected medical man in his day, is almost completely forgotten. Yet there are many aspects of Nooth's life that are of great interest, and his apparatus was one of the very first to be designed to produce, for medicinal purposes, what may inclusively be called carbonated waters; and, surprisingly, there are strong links of coincidence between the histories of artificial mineral waters and of anesthesia, and the personalia involved in each.

Anesthesia, Inhalation↗
PubMed2005

Rapid analysis of 2,4-D in soil samples by modified Soxhlet apparatus using HPLC with UV detection.

The 2,4-dichlorophenoxy acetic acid (2,4-D) is used as a systemic herbicide to control broadleaf weeds in wheat, corn, range land/pasture land, sorghum, and barley. In this study, a fast and efficient method is developed by selection of modified extraction apparatus and high-performance liquid chromatography (HPLC)-UV conditions for the determination of 2,4-D in soil samples. The method is applied to the study of soil samples collected from the agricultural field. The herbicide is extracted from soil samples by acetonitrile in a modified Soxhlet apparatus. The advantages of the apparatus are that it uses small volume of organic solvent, reduced time of extraction, and better recovery of the analyte. The extract is filtered using a very fine microfiber paper. The total extract is concentrated in a rotatory evaporator, dried under ultrahigh pure N2, and finally reconstituted in 1 mL of acetonitrile. HPLC-UV at 228 nm is used for analysis. The herbicide is identified and quantitated using the HPLC system. The method is validated by the analysis of spiked soil samples. Recoveries obtained varied from 85% to 100% for spiked soil samples. The limit of quantitation (LOQ) and the limit of detection (LOD) are 0.010 and 0.005 parts per million (ppm), respectively, for spiked soil samples. The LOQ and LOD are 0.006 and 0.003 ppm for unspiked soil samples. The measured concentrations of 2,4-D in spiked soil samples are between 0.010 and 0.020 ppm with an average of 0.016 +/- 0.003 ppm. For unspiked soil samples it is between 0.006 ppm and 0.012 ppm with an average of 0.009 +/- 0.002 ppm. The measured concentrations of 2,4-D in soil samples are generally low and do not exceed the regulatory agencies guidelines.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1990

Progressive exercise testing in closed head-injured subjects: comparison of exercise apparatus in assessment of a physical conditioning program.

Progressive exercise tests were performed on 12 closed head-injured subjects to determine 1) whether results differ when tests are performed on a treadmill, a bicycle ergometer, or mechanical stairs and 2) whether a 3-month general physical conditioning program results in an improvement in exercise performance. The subjects performed progressive exercise tests on each apparatus on entry into a residential transitional rehabilitation program and approximately 3 months later following participation in a physical conditioning program. On both the initial and 3-month exercise tests, maximal oxygen consumption (VO2 max) was significantly greater on the treadmill and the mechanical stairs than on the bicycle ergometer. The mean VO2 max was 74% of the predicted value on the initial exercise test and rose to 85% of the predicted value after the 3-month physical conditioning program. Oxygen consumption per kilogram of body weight at a given power output on a given apparatus showed no statistically significant difference between the initial and 3-month tests, indicating no change in exercise efficiency. On the 3-month test, a statistically significant decrease was noted in heart rate at rest and after the 4-minute period of recovery from maximal exercise on any given apparatus. The data obtained in this study indicate that 1) the treadmill and mechanical stairs are more suitable than the bicycle ergometer for assessing maximal exercise performance and 2) improved physical fitness following a physical conditioning program is associated with an improvement in cardiovascular function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2001

A simple apparatus for accelerating recovery from inhaled volatile anesthetics.

UNLABELLED: Hyperpnea increases anesthetic elimination but is difficult to implement with current anesthetic circuits without decreasing arterial PCO2. To circumvent this, we modified a standard resuscitation bag to maintain isocapnia during hyperpnea without rebreathing by passively matching inspired PCO2 to minute ventilation. We evaluated the feasibility of using this apparatus to accelerate recovery from anesthesia in a pilot study in four isoflurane-anesthetized dogs. The apparatus was easy to use, and all dogs tolerated being ventilated with it. Under our experimental conditions, isocapnic hyperpnea reduced the time to extubation by 62%, from an average of 17.5 to 6.6 min (P = 0.012), but not time from extubation to standing unaided. This apparatus may provide a practical means of applying isocapnic hyperpnea to shorten recovery time from volatile anesthetics. IMPLICATIONS: A simple modification to a standard resuscitation bag allows one to increase ventilation without decreasing blood carbon dioxide levels. In dogs, we confirmed that this circuit can be used to accelerate the elimination of and recovery from volatile anesthetics.

Anesthesia Recovery Period↗
PubMed1998

Clinical applicability of the sweep frequency measuring apparatus for diagnosis of middle ear diseases.

OBJECTIVE: To develop a measuring apparatus that has the ability to sweep both frequency and external auditory meatus static pressure and can display measurement results in a three-dimensional expression. To measure the middle ear dynamic characteristics of normal-hearing subjects and of patients with this apparatus. DESIGN: Investigate 275 ears of 153 normal-hearing subjects and 72 ears with middle ear diseases. RESULTS: The measurement results show fairly distinctive patterns depending on the middle ear conditions, i.e., normal, ossicular chain separation, ossicular chain fixation, secretory otitis media, tympanic membrane perforation, and tympanic membrane atelectasis. The evaluation of patients with ossicular diseases revealed that the rate of correct diagnosis of ossicular chain separation is 84% and that of ossicular chain fixation is 74%. These diagnoses were confirmed by surgery. CONCLUSION: Displaying the measurement results in a three-dimensional expression is helpful to make correct diagnosis in clinical practice. It is especially easy to make a distinction between the ossicular chain separation and ossicular chain fixation. Therefore, it is concluded that this apparatus has a high degree of clinical applicability to the diagnosis of these diseases.

Acoustic Impedance Tests↗