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At least 19 recordsLinked to original sources
PubMed1978

Comparative pressure measurements in the oesophagus by means of in situ tip-transducers and external transducer systems.

Basal gastro-oesophageal sphincter pressures and peak peristaltic pressure amplitudes in the oesophageal body 5 and 15 cm proximal to the gastro-oesophageal sphincter were measured with three different set ups in six healthy volunteers. The in situ tip-transducer measurements were compared to two different external pressure transducers in a perfused catheter system and to an external pressure transducer in a non-perfused catheter system. The in situ tip-transducer recorded higher sphincter pressures and peristaltic amplitudes than those recorded by the perfused and non-perfused systems (P less than 0.01). There was no difference between the pressures recorded by perfused systems in conjunction with the different external transducers. The perfused systems recorded sphincter pressures higher than those recorded by the non-perfused systems (P less than 0.02 and P less than 0.01), whereas the non-perfused system recorded higher peristaltic pressure amplitudes than those recorded by the perfused systems (P less 0.01 and P less than 0.01). The importance of the bend of the in situ tip-transducer was shown experimentally. It is concluded that the ideal system for recording oesophageal pressures is a perfused catheter set-up with minimal compliance. The probe with three side holes at the same level ensures registrations of the lowest occlusion pressure at the measuring point.

Adult↗
PubMed1975

Appearance of transducing particles and the fate of host DNA after infection of Salmonella typhimurium with P22-mutants with increased transducing ability (HT-mutants).

The kinetics of production of transducing particles for different bacterial markers were followed by premature lysis of Salmonella typhimurium cells infected with P22 phages. The were compared for cells infected with wild type phage or with HT-mutants which show increased transduction frequencies. Measuring the sedimentation velocity of bacterial DNA of cells infected with wild type or HT-phages, it was shown that: a) there is no cutting of DNA at random; b) original fragments necessary for packaging host DNA into transducing particles cannot be smaller than 10 phage-genome lengths; c) cutting of transducing fragments leads immediately to the right length; d) there is no loss of precipitable DNA due to phage infection.

DNA, Bacterial↗
PubMed1975

The properties of bird feathers as converse piezoelectric transducers and as receptors of microwave radiation. I. Bird feathers as converse piezoelectric transducers.

An investigation was made of the properties of bird feathers as piezoelectric transducers in the audiofrequency range and as dielectric receptors of electromagnetic radiation in the microwave region. In the first case, cartridges of the ceramic and magnetic type and an electromagnetic transducer probe were used as detecting devices. Results show piezoelectric resonances in the 1 to 20-kHz region for the calami of feathers.

Animals↗
PubMed1976

Isolation and characterization of the specialized transducing bacteriophages phi80dargF and lambdah80cI857 dargF: specific cleavage of arginine transducing deoxyribonucleic acid by the endonucleases EcoRI and SmaR.

The directed transposition of argF to the tonB locus of the Escherichia coli chromosome and the subsequent isolation of the specialized transducing phage phi80dargF is described. The structure of this phage has been has been determined. A hybrid lambdah80cI857dargF phage has been constructed. Deoxyribonucleic acid isolated from these and their parent bacteriophages has been specifically cleaved by the endonucleases EcoRI and SmaR; the unique deoxyribonucleic acid fragments thus obtained have been resolved and analyzed by electrophoresis in agarose gel.

Arginine↗
PubMed1978

Bacteriophage P22-mediated specialized transduction in Salmonella typhimurium: identification of different types of specialized transducing particles.

The temperate bacteriophage P22 mediates both generalized and specialized transduction in Salmonella typhimurium. Specialized transduction by phage P22 is different from, and less restricted than, the well characterized specialized transduction by phage lambda, due to differences in the phage DNA packaging mechanism. Phage lysates produced by induction of lysogenic strains contain very high frequencies of supQ newD- and proA,B-specialized transducing particles (10(-2)/PFU and 10(-3)/PFU, respectively), most of which are produced by independent aberrant excision events of various types. In a model, 12 different modes of transduction mechanisms were characterized by: (i) the structure of the specialized transducing genomes after injection into a new host cell, i.e., linear or circular, and (ii) the requirements for the transduction process, i.e., host recombination functions, phage integration functions, or presence of a prophage. By using different recipient strains and phage helper strains, it was possible to show that most specialized transducing particles (ca. 99%) contain linear genomes that cannot circularize upon injection into a new host cell and that require the presence of an integrated prophage as a site for a recombinational event to give rise to a transductant. Only 0.1% of all specialized transducing particles were shown to transduce by integration, suggesting that transducing genomes containing terminally redundant ends represent only a minor fraction of all transducing particles that are produced. However, it should be pointed out that the frequency (approximately 10(-5)/PFU) of these specialized transducing genomes that can circularize upon injection into a new host cell is as high as or even higher than the frequency of specialized transducing particles of phage lambda. The remaining approximately 1% of all specialized transducing particles can transduce by any one of the other mechanisms described.

Adsorption↗
PubMed1992

Electromagnetic midsagittal articulometer systems for transducing speech articulatory movements.

This paper describes two electromagnetic midsagittal articulometer (EMMA) systems that were developed for transducing articulatory movements during speech production. Alternating magnetic fields are generated by transmitter coils that are mounted in an assembly that fits on the head of a speaker. The fields induce alternating voltages in a number of small transducer coils that are attached to articulators in the midline plane, inside and outside the vocal tract. The transducers are connected by fine lead wires to receiver electronics whose output voltages are processed to yield measures of transducer locations as a function of time. Measurement error can arise with this method, because as the articulators move and change shape, the transducers can undergo a varying amount of rotational misalignment with respect to the transmitter axes; both systems are designed to correct for transducer misalignment. For this purpose, one system uses two transmitters and biaxial transducers; the other uses three transmitters and single-axis transducers. The systems have been compared with one another in terms of their performance, human subjects compatibility, and ease of use. Both systems can produce useful midsagittal-plane data on articular movement, and each one has a specific set of advantages and limitations. (Two commercially available systems are also described briefly for comparison purposes). If appropriate experimental controls are used, the three-transmitter system is preferable for practical reasons.

Biomechanical Phenomena↗
PubMed1979

Effects of gas density on the frequency response of gas-filled pressure transducers.

The effects of gas density on the frequency responses of four pressure transducers were determined at gas densities from 1.2 to 25.0 g/l. Transducers tested included three sensitive differential types used with pneumotachographs to measure respiratory flow (Validyne DP-45 and DP-103; Medistor P-11) and a transducer commonly used to measure esophageal pressure (Statham P23Dd). Three different responses were obtained. The Validyne DP-103 was overdamped and its response was essentially independent of gas density. The frequency response of this transducer is adequate for use with quiet breathing only. The Validyne DP-45 and Medistor P-11 responses were underdamped. The resonant peaks of these transducers decreased markedly in frequency as the gas density increased. The Statham P23Dd was also underdamped; however, its resonant frequency increased as gas density increased. An esophageal balloon did not alter the frequency response characteristics of this tubing-transducer system. Both increases in length and decreases in diameter of connecting tubing reduced the frequency of resonant peaks of underdamped pressure transducers.

Atmospheric Pressure↗
PubMed1976

Effect of transducer placement on echocardiographic mitral valve systolic motion.

The influence of transducer position and angulation upon the mitral systolic echo was studied in 100 presumably healthy females. Echocardiographic studies were performed from the second, third, fourth and fifth intercostal spaces (ICS). The role of the sound beam's path relative to cardiac motion was assessed by analyzing the recorded mitral valve pattern as a function of transducer orientation, independent of the absolute ICS used. With the transducer directed caudally when both mitral leaflets and left atrium were recorded, holosystolic or midsystolic posterior motion of the mitral valve leaflet echo was seen in 59% of the subjects. These patterns, recorded this way, were not related to phonocardiographic signs suggesting mitral valve prolapse. Best correlation with phonocardiographic findings was obtained when the echocardiographic examination was performed with the transducer either perpendicular to the chest in the sagittal plane, or pointing slightly cephalad ('perpendicular' position). With the transducer in 'perpendicular' position, both holosystolic and midsystolic posterior motion of the mitral systolic echo, deviating more than 2 mm from a line joining the C and D points, were highly related statistically to phonocardiographic findings suggesting mitral valve prolapse. This study demonstrates that transducer position and angulation on the chest wall are important determinants of echocardiographic appearance of mitral valve during systole. Only the 'perpendicular' transducer position should be used when analyzing echocardiograms for the presence of mitral valve prolapse.

Echocardiography↗
PubMed1976

Specialized transducing phages derived from phage P22 that carry the pro AB region of the host, Salmonella typhimurium: genetic evidence for their structure and mode of transduction.

Two independently isolated specialized transducing phages, P22pro-1 and P22pro-3, have been studied. Lysates of P22pro-1 contain a majority of transducing phages which can go through the lytic cycle only in mixed infection; these defective phages transduce by lysogenization in mixed infection and by substitution in single infection. A few of the transducing phages in P22pro-1 lysates appear to be non-defective, being able to form plaques and to transduce by lysogenization in single infection. Transduction by P22pro-3 lysates is effected by non-defective transducing phages, which transduce by lysogenization; these lysates also contain a majority of defective phages which do not co-operate in mixed infection. The P22pro-1 genome is thought to contain an insertion of bacterial DNA longer than the terminal repetition present in P22 wild type, so that at maturation a population of differently defective phages is produced. The exact structure of the P22pro-3 genome is open to conjecture, but it seems clear that the insertion of bacterial DNA is smaller than that in P22pro-1. Both P22pro-1 and P22pro-3 are defective in integration at ataA under non-selective conditions, although both integrate on medium that lacks proline.

Chromosome Mapping↗
PubMed1977

[An extraluminal strain gage force transducer: its construction and implantation (author's transl)].

1. Extraluminal strain gage force transducers have been designed and constructed in this laboratory. This device was originally developed to measure contractile force of the heart by Walton et al in 1950, however, we concentrated our effort upon durability and waterproof of the transducer in the present study. 2. Strain gages which were made for measuring large strain were prepared and bonded onto the both surfaces of CuBe strips with epoxy lesin. Water proof was then made by applying silicone (KE 45 RTV), which was excellent in waterproof, insulation and flexibility. The silicone was also found no significant influence upon the surrounding tissues as a foreign body. 3. The transducer constructed in this way had useful life for 3-6 months after implantation. Chronically implanted transducer units offer several advantages: they provide prolanged observation of gastrointestinal mechanical activity directly in conscious animals. They can be sutured on the outer surface of the gastrointestinal tract and do not interfere flow of intraluminal contents. They can measure separate contractile force of the circular and longitudinal muscle layers. 4. Major limination of the transducer is difficulty to determine if a given sequence of movements are mixing or propulsion of the contents. Application of these transducers is currently limited in animal only.

Animals↗
PubMed1976

Chronic measurement of epidural pressure with an induction-powered oscillator transducer.

An induction-powered oscillator transducer (IPOT) was designed for the chronic measurement of epidural pressure. The transducer was completely implantable so all pressure measurements were made through the intact skin. The IPOT had a linear pressure range from -50 to +200 cm H2O, was sensitive to 1 mm H2O and had a zero drift of less than 1 mm H2O/day under full load. Zero drift was minimized by using a hermetically-sealed metal bellows transducing element which was chemically treated to prevent corrosion and creep. The correlation between epidural pressure and intraventricular pressure was determined during the first 24 hours after implantation in six dogs. Epidural pressure was found to be a linear function of intraventricular fluid pressure. Epidural pressure and intraventricular pressure were essential equal provided the epidural wedge pressure was minimized by proper insertion of the transducer. The correlation between epidural pressure and intraventricular pressure was determined after chronic implantation in five dogs. Epidural pressure was a linear function of intraventricular pressure in the chronically implanted dogs, but epidural pressure was not equal to intraventricular pressure. After chronic implantation, the epidural pressure transducer was not responsive to changes in intraventricular pressure because of mechanical changes in the dura. The dura became stiff and non-compliant. Maximum correlation between epidural pressure and intraventricular fluid pressure in chronic implantations will depend on judicious material selection and mechanical design at the transducer-dura interface.

Animals↗
PubMed1979

The origin of the DNA in transducing particles of bacteriophage Mu. Density gradient analyses of intact phages.

The origin of DNA in transducing particles of bacteriophage Mu was investigated by density labelling techniques. Unlabelled plaque-forming and leu+-transducing particles were of about the same density. Preinfection labelling of DNA with 5-bromodeoxyuridine increased the density of the transducing particles, but not that of the infective ones. Postinfection labelling increased the density of the infective particles twice as much as that of the transducing particles. We conclude that half of the transducing DNA is synthesized before infection and half is synthesized after infection, similar to the results obtained with P1kc transducing phages (Ikeda and Tomizawa, 1965).

Bacteriophage mu↗
PubMed1992

Primary structure of an archaebacterial transducer, a methyl-accepting protein associated with sensory rhodopsin I.

A methylated membrane protein of 97 kDa was suggested on the basis of mutant analysis to transduce signals from the phototaxis receptor sensory rhodopsin I to the flagellar motor in Halobacterium halobium. Here we report isolation of the proposed transducer protein, cloning of its gene based on partial protein sequences, the complete gene sequence, and analysis of the encoded primary structure. The 1611-base-pair gene termination codon overlaps the initiator ATG of the sopI gene, which encodes the sensory rhodopsin I apoprotein. The predicted size of 57 kDa for the methylated protein indicates an aberrant electrophoretic migration on SDS/polyacrylamide gels, as occurs with other acidic halophilic proteins. Putative promotor elements are located in an A+T-rich region upstream of the gene. Comparison of the translated nucleotide sequence with N-terminal sequence of the purified protein shows the protein is synthesized without a processed leader peptide and the N-terminal methionine is removed in the mature protein. The deduced protein sequence predicts two transmembrane helices near the N terminal that would anchor the protein to the membrane. Beyond this hydrophobic region of 46 residues, the remainder of the protein (536-amino acid residues total) is hydrophilic. The C-terminal 270 residues contain a region homologous to the signaling domains of eubacterial transducers (e.g., Escherichia coli Tsr protein), flanked by two regions homologous to the methylation domains of the transducer family. The protein differs from E. coli Tsr in that it does not have an extramembranous-receptor binding domain but instead has a more extended cytoplasmic region. Coexpression of the methyl-accepting protein gene (designated htrI) and sopI restores sensory rhodopsin I phototaxis to a mutant (Pho81) that contains a deletion in the htrI/sopI region. These results extend the eubacterial transducer family to the archaebacteria and substantiate the proposal that the methylated membrane protein functions as a signal-transducing relay between sensory rhodopsin I and cytoplasmic sensory-pathway components.

Amino Acid Sequence↗
PubMed1992

Mechano-electrical transducer currents in hair cells of the cultured neonatal mouse cochlea.

The first step towards the generation of the receptor potential in hair cells is the gating of the transducer channels and subsequent flow of transducer current, induced by deflection of the stereocilia. We describe properties of the transducer current in outer hair cells of neonatal mice. Less extensive observations on inner hair cells suggest that their transducer currents have similar characteristics. The hair bundles were stimulated by force from a fluid jet. The transducer currents in outer hair cells are the largest found so far in any hair cell, with a chord conductance of up to 9.2 nS at -84 mV. The transfer function suggests that the channel has at least two closed states and one open state. The permeabilities for sodium, potassium and caesium are similar, consistent with the channel being a fairly non-selective cation channel. At negative potentials the currents adapt in most cells, although never as completely as in hair cells of lower vertebrates. If the unit conductance of the transducer channel is similar to that of the turtle's auditory hair cells (100 pS), then there are about 90 channels per hair bundle, or one channel between every pair of adjacent stereocilia in neighbouring rows.

Animals↗
PubMed1992

A miniature piezoelectric polymer transducer for in vitro measurement of the dynamic contact stress distribution.

Previous studies of contact pressure measurement between articular surfaces have been mostly limited to static techniques. The purpose of our study was to develop a new dynamic technique for a direct measurement of the local contact stresses, and to apply the new method to an in vitro cadaver study of the patellofemoral joint pressures. The miniature transducer consists of a 2 mm diameter and 28 microns thick piece of piezoelectric polymer film sandwiched between two stainless steel electrodes of similar diameter. A water-resistant capsule consisting of Teflon film and Hysol epoxy was applied around the transducer. The transducer was 3 mm in diameter and 0.7 mm in thickness. A 3 mm well was made at six locations in the patella, corresponding to superior, middle, and inferior regions of both facets. Six transducers were cemented within each well, flush with the articular cartilage. The transducers were calibrated in situ before and after the experiment. The femur was rigidly fixed to the loading apparatus and the tibia was allowed to flex and extend through a 90 degrees range of motion using an Instron and a pulley system connected to the quadriceps tendon. Q angles of 0, 5, 10 and 15 degrees were established by adjusting the direction of the quadriceps tendon. Stresses ranging from 0.1-1.3 MPa were recorded at various locations. These values varied in flexion and extension. An overall decrease in these stresses was noted after tuberosity elevation up to 1.5 cm, following which increased values up to 1.8 MPa were recorded mostly in the superior section.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomechanical Phenomena↗
PubMed1979

Comparability and reproducibility of apex cardiogram recorded with six different transducer systems.

A comparison was made in 7 dogs of the results obtained by 6 different apex cardiographic transducers applied before, during, and after controlled infusion of angiotensin and isoprenaline. The electrocardiogram, internal phonocardiogram, aortic and left ventricular pressure using a Telco micromanometer, and apex cardiogram were recorded simultaneously on magnetic tape and paper. Digital computer techniques were used to derive various measurements. The comparison of the 6 transducer systems was made expecially with respect to measurements derived from the normalised derivative, calculated using total as well as developed pressure or displacement. Measurements derived from left ventricular pressure were very reproducible. Differences in results of 'contractility' indices varied between 0.5 and 1.9 per cent. Indices from the apex cardiogram using 6 different transducer systems showed variations up to 20 per cent, with mean values varying between 3.2 and 8.1 per cent. There was a systematic deviation for one transducer system, which was responsible for a significant part of the observed variability. It may be concluded that in order to assure maximal reproducibility, technical characteristics of the apex cardiograph transducer should be taken into account and an optimal recording technique should be used.

Angiotensins↗