Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C1275122 (TEM)
 21,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A novel TEM-derived plasmid-encoded beta-lactamase, resistant to inhibition by clavulanic acid, has been identified in a clinical strain of Escherichia coli found in Scotland. The beta-lactamase gene was carried on an 81-kb plasmid that conferred no other resistances. The novel enzyme conferred resistance to the amoxycillin/clavulanic acid combination on the host bacterium. The beta-lactamase has a pI of 5.25 and lies between the PSE-4 and SAR-1 beta-lactamases on an isoelectric focusing gel. This beta-lactamase has a Mr value of 25,000, similar to the TEM-1 enzyme and a comparable substrate profile. Its most significant difference is that it is inhibited by clavulanic acid 100-fold less efficiently than the TEM-1 enzyme. The enzyme was confirmed to be derived from the TEM enzymes by probing the plasmid DNA with an intragenic gene probe for TEM-1. This is the first report of a clinical bacterium carrying a TEM-enzyme that confers resistance to clavulanic acid combinations and we have designated the beta-lactamase as TRC-1.
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PMID:TRC-1: emergence of a clavulanic acid-resistant TEM beta-lactamase in a clinical strain. 131 62

The development of a coaxial TEM (transverse electromagnetic) deep-heating, non-contacting applicator employing two axially spaced concentric sleeves is described which has electrostatic characteristics and has been named the ESA. Thermal data obtained with the FDA/CDRH elliptic-shaped human torso phantom (with fat overlay) showed nearly uniform heating (+/- 10%) throughout the inner cross-section. Saline tank measurements on a torso cross-section confirmed similar SAR uniformity. Animal experiments with a pig, both with and without blood flow, verified deep-heating and suggested that some preferential central heating occurred. The absence of excessive surface heating indicated that the major portion of the E-field excitation is axially aligned. The non-contacting applicator does not require a water bolus, and experiments showed that moderate patient movement had minor effect on performance.
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PMID:Loosely coupled coaxial TEM applicators for deep-heating. 272 69

The design of a clinical deep-body hyperthermia system based on the 'coaxial TEM' applicator is presented. The 'coaxial TEM' applicator produces a radiative circumferential RF field, and the adjustable aperture width of this applicator allows the optimization of field dimensions and penetration depth. A new type of open water bolus, in which the patient is almost freely floating, avoids physical stresses on the patient, provides an optimal coupling of the EM energy into the patient, and may limit aberrant heating. A convenient patient position is possible with this system and discomfort is expected to be minimal. Preliminary phantom experiments with the clinical applicator resulted in typical SAR distributions of a radiative circumferential field applicator with the central interference at maximum.
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PMID:Design of a clinical deep-body hyperthermia system based on the 'coaxial TEM' applicator. 368 Oct 41

A 2.45-GHz microwave exposure facility was developed for long-term TEM irradiation of cellular monolayers. Culture flasks with cells attached to the inside bottom surface were filled with medium, submerged in a 60 X 60 X 12-cm water bath on the field central axis, and exposed in the far-field 2 m below the ceiling-mounted antenna. A quarter-wave transformer plate increased the power transmitted into the water bath, and treatment temperatures were maintained by closed circulation with an external temperature control reservoir. Power density mapped below the quarter-wave plate indicated uniform TEM fields in the 25 X 25-cm region where flasks were located. With 1 kW of forward power to the antenna, the SAR [W/kg] = 45 exp(-0.607d) where d [cm] is the depth in water at any point within this area.
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PMID:Far-field 2.45 GHz irradiation system for cellular monolayers in vitro. 385 49

Between August 1989 and July 1992 a total of 22 patients (64 treatments) with inoperable or recurrent deep seated pelvic tumours were treated with regional hyperthermia and radiotherapy. The 70 Mhz Coaxial TEM applicator with its characteristic open waterbolus was used as heating device. The main objective of this pilot study was to evaluate the feasibility, toxicity and temperature data. The results showed that the major treatment limiting factors were insufficient power and systemic stress. Local pain was observed in only 10% of all treatments. Most of the treatments resulted in elevated systemic temperatures with the overall mean maximum oesophagus temperature reaching 38.9 +/- 0.7 degrees C, however, in only 6% of these treatments this was found to be treatment limiting. From the measured data the following intratumoral temperatures were calculated: T90 = 39.9 +/- 1.0 degrees C; T50 = 40.7 +/- 1.0 degrees C; T10 = 41.4 +/- 1.0 degrees C. In addition, the overall mean average normal tissue temperatures were determined: Trectum = 40.8 +/- 0.7 degrees C; Tvagina = 41.3 +/- 0.9 degrees C; Turethra = 40.8 +/- 0.9 degrees C. The temperatures in normal tissue were frequently higher than in tumour, indicating that a large volume was heated. The open waterbolus allows strong cooling, but the strategy was changed during the study: higher systemic temperatures were allowed to improve the pelvic temperatures. This pilot study proved that the open waterbolus is clinically a success, because it offers patient comfort and SAR-steering by patient repositioning, and that regional hyperthermia with the Coaxial TEM is feasible.
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PMID:Regional hyperthermia of pelvic tumours using the Utrecht 'Coaxial TEM' system: a feasibility study. 779 Jul 33

A flexible and fast regional hyperthermia treatment planning system for the Coaxial TEM System has been devised and is presented. Using Hounsfield Unit based thresholding and manually outlining of the tumour, a 40 cm CT data set (slice thickness 5 mm) is segmented and down scaled to a resolution of 1 cm, requiring only 30 min. The SAR model is based on the finite-difference time-domain (FDTD) method. The number of time steps to achieve numerical stability has been determined and was found to be 7000. Various optimizations of the SAR model have been applied, resulting in a relatively short computation time of 3.7 h (memory requirements 121 MB) on a Pentium III, 450 MHz standard personal computer, running GNU/Linux. The model has been validated using absolute value(Ez) measurements in a standard phantom inserted in the Coaxial TEM Applicator under different conditions and a good agreement was found. Hyperthermia treatment planning in combination with the homemade visualization tools have provided much insight in the regional hyperthermia treatment with the Coaxial TEM Applicator.
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PMID:Development of a regional hyperthermia treatment planning system. 1134 27

Local pain is the main factor that limits regional hyperthermia treatment. Using the SAR model of the regional hyperthermia treatment planning system, the capability of absorbing blocks to reduce peripheral hot spots was investigated. The effect of rectangular absorbers of various size and salinity on an elliptical phantom in the Coaxial TEM was evaluated. The computed results were compared with SAR values measured in the phantom. Absorbers of 9 x 9 x 4 cm3 and a salinity of 18 gram l(-1) provide a SAR reduction in the muscle equivalent material, centrally under the absorber of at least 50% at a depth of up to 3 cm. The effect on the central (i.e. tumour) region is less than 20%. Larger absorbers have a more global effect and cause more attenuation in the central region. The attenuating effect depends strongly on the thickness of the fat layer between muscle and absorber. More than 2 cm fat limits the effective use of absorbers. Absorbers can induce a significant increase of SAR in muscle and fat near their edges. This effect also depends on absorber size and salinity and the thickness of the fat layer. The effect of an absorber was also evaluated with a patient anatomy, yielding results in agreement with the phantom experiments.
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PMID:The use of absorbing structures during regional hyperthermia treatment. 1134 29

The main objective of this paper is to carefully study the fields induced in flasks exposed to RF electromagnetic fields. The study focuses on the widely used 60 mm Petri dishes and rectangular T-75 flasks for the two following cases: 1) cells in homogeneous suspension and 2) cell monolayers. The dependence of the coupling and the homogeneity of the SAR distribution on frequency (0.7 GHz to 2.5 GHz), polarization (E, H and k polarizations) and the amount of medium (1.9 mm to 4.7 mm medium height) is studied. In addition, the effects of the environment, meniscus and field impedance as well as the distortion of the incident field are discussed. Based on these results, advantages and disadvantages of different fundamental designs of apparatus used in the past are compared. These are TEM cells, HF chambers, radial transmission lines (RTL), waveguides and wire patch cells. Furthermore, the major optimization parameters are identified for the development of highly optimized exposure systems, enabling the conduct of high quality experiments.
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PMID:Basis for optimization of in vitro exposure apparatus for health hazard evaluations of mobile communications. 1174 72

Several authors have reported that the meniscus as occurring at the walls of Petri dishes and flasks (solid-liquid interface) can significantly affect the SAR distribution in the entire dish and flask, while others have ignored this effect. In this study, this effect has been comprehensively analyzed by numerical means supported by theoretical considerations. The focus is on E polarization, which results in the most homogeneous exposure for monolayer cell cultures and therefore is the most often applied polarization in exposure setups for risk assessment studies. This includes setups based on TEM cells, waveguides, radial transmission lines (RTL), and HF chambers. The conclusion of this study is that the meniscus and its size have a significant effect on the strength and homogeneity of the induced SAR distribution. Hence, the meniscus needs to be accounted for in the determination of the averaged SAR as well as in the uncertainty assessment. It has also been demonstrated that a voxel size of less than 0.2 mm is needed to predict the SAR values for a monolayer of cells accurately.
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PMID:Effect of the meniscus at the solid/liquid interface on the SAR distribution in Petri dishes and flasks. 1252 76

A study was performed on regional hyperthermia for patients with locally advanced prostate carcinoma. The primary objective was to analyse the thermometry data with an emphasis on the possibility of replacing invasive thermometry by tumour-related intra-luminal thermometry. Fourteen patients were treated with a combination of conformal external beam radiotherapy (70 Gy) and hyperthermia. Hyperthermia was delivered using the Coaxial TEM system, one treatment per week, to a total of five treatments. Thermometry was performed in bladder, urethra, rectum and esophagus. Invasive thermometry in the prostate was carried out during one or two treatments for each patient by placing transperineally a central and a peripheral catheter. Heterogeneous temperature distributions were measured in the prostate. The mean average invasive temperature range was 1.1 degrees C. Due to the temperature heterogeneity and a limited number of thermometry sensors (mean 7, range 2-13), large variability between treatments and patients existed regarding achieved temperatures and dose. The mean invasive T90 was 40.2 +/- 0.6 degrees C and T50 was 40.8 +/- 0.6 degrees C. The mean Cum min T90>40.5 degrees C per treatment was 22 (range 0-50). Importantly, intra-luminal temperatures did not reliably predict invasively measured temperatures. Invasive thermometry, therefore, remains compulsory to calculate a thermal dose for an individual patient. Changes in temperature during treatment, measured by the urethral sensors, corresponded well with changes in temperature measured by the individual invasive sensors. Similar comparison of rectal temperature changes with intra-prostatic temperature changes was not as predictive. The similarity in temperature changes between the urethral and interstial sites, suggests that urethral temperatures are sufficient for treatment optimization. The SAR profile did not correspond with the temperature profile indicating heterogeneous perfusion. Although regional hyperthermia in combination with external beam radiotherapy for locally advanced prostate carcinoma is clinically feasible, the question on the importance of invasive thermometry remains.
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PMID:Comparison of intra-luminal versus intra-tumoural temperature measurements in patients with locally advanced prostate cancer treated with the coaxial TEM system: report of a feasibility study. 1294 64


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