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At least 1,063 records · Page 59Linked to original sources
PubMed1976

Effect of lindane on radio-carbon (14C) incorporation by Rhizobium japonicum.

Experiments conducted in vitro with three levels (1, 2, and 5 ppm active ingredient) of the insecticide lindane (gamma-BHC) showed no effect on the growth of Rhizobium japonicum, but altered the incorporation of radio-carbon (14C-glucose) into the different constituents of the growing cells. While all the three levels of the insecticide significantly depressed the incorporation of radiocarbon in the alcohol-extractable fraction, with no effect on the alcohol-ether soluble fraction of the cells, the 2 and 5 ppm levels enhanced the incorporation rate in the cold-TCA soluble fraction, but reduced it in the hot-TCA soluble fraction. Only with the 5ppm level of the insecticide treatment an increase in the specific activity of the insoluble protein fraction of the cells was observed. The results indicated that lindane, at various concentrations, affected the carbon (glucose) metabolism of the Rhizobium cells.

Glucose↗
PubMed1997

Radio- and chemoprotection of bone marrow cells by opposite cell cycle-acting cytokines.

Cytokines such as interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-alpha), stem cell factor (SCF), and interleukin-12 (IL-12), among others, are presently known to exert a radioprotective effect on bone marrow (BM) precursor cells. IL-1, TNF-alpha, transforming growth factor-beta (TGF-beta), and macrophage inflammatory protein-1 alpha (MIP-1alpha) exert a chemoprotective effect on BM cells, while a putative role of IL-12 in this effect is still unknown. IL-1, SCF, and IL-12 are known to promote BM precursor cell cycling. Conversely, TNF-alpha, MIP-1alpha, and TGF-beta, the latter a radiosensitizer, induce cycle arrest in these cells. Cycling increases radioprotection, while arrest reduces chemical damage. IL-1 and TNF-alpha are unique in their ability to induce detoxifying mechanisms. The present communication overviews these effects. It also proposes a model, based on the induction of biochemical detoxifying mechanisms, aiming to explain BM cell radio- and chemoprotection by opposite cell cycle-acting cytokines.

Animals↗
PubMed1986

Exploration and avoidance learning after ibotenic acid and radio frequency lesions in the rat amygdala.

Open-field activity, avoidance behavior, and plasma corticosterone levels were studied after intraamygdala injections of 3.0 micrograms ibotenic acid (IBO) and radio-frequency (RF) lesions in the amygdala complex of male Wistar rats. The experiments were undertaken to evaluate the importance of amygdala neurons versus axons of passage in fear-motivated behavior. The IBO lesions led to increased open-field activity, but no impairments in active avoidance learning, nor changes in basal or experimental levels of plasma corticosterone. The RF lesions, on the other hand, led to an increase in experimental plasma corticosterone levels. In the one-way avoidance task the RF lesions, in contrast to the IBO lesions, led to significant impairments in the acquisition of the avoidance response. Although the long-term axon-sparing effect of IBO is questioned since cavities were detected in the affected areas 8 weeks after the injections, the differences in avoidance learning and in corticosterone levels between the RF and the IBO lesions indicate that the axons were functionally active at the time of testing (14-26 days postoperatively). The increase in open-field activity is attributed to the destruction of amygdala neurons and neurons in the overlying cortex, while an avoidance deficit seem to depend on the destruction of axons. On the basis of the behavioral results and the corticosterone data in these experiments, it is suggested that the behavioral changes are not attributable to a general reduction in the arousal of fear. However, since the IBO lesions did not affect the most medial parts of the amygdala complex including the central amygdala nucleus, the role of this nucleus in fear arousal has to be investigated further.

Amygdala↗
PubMed1987

Simultaneous radio- and chemotherapy of inoperable brain tumours.

Between January 1980 and May 1985, 102 patients (68 men, 34 women, median age 47 years) with malignant brain tumours (35% glioblastoma multiforme, 30% astrocytoma grade III, 21% oligodendroglioma grade III) have been treated in our clinic. All tumours were inoperable because of their size and/or location. The diagnosis was confirmed histopathologically (stereotactic biopsy or subtotal resection). Seventy-five patients without previous radiotherapy received three courses of a concomitant radio- and chemotherapy with free intervals of 5 weeks between the courses of the therapy. Using lateral opposing fields the whole brain was irradiated with 60Co in daily fractions of 1.5 Gy up to 15 Gy per course of the treatment. Simultaneously, all patients received ifosfamide on five consecutive days in a dosage of 1.2 g/sqm body surface each day i.v. On days 1, 3 and 5, BCNU was given additionally in a daily dosage of 30 mg/sqm body surface i.v. After three courses, a total radiation dose of 45 Gy was administered to the whole brain. Directly after the last cycle of the combined treatment the primary tumour was boosted up to 50-60 Gy using smaller portals. Seventy-one of the 75 patients were amenable to statistical analysis. The overall tolerance was good. No severe haematological or gastrointestinal complications occurred. According to the criteria of the UICC, 12 complete remissions (CR) (i.e. 16.9%) and 35 partial remissions (PR) (i.e. 49.3%) were achieved. In 21 cases (i.e. 29.6%), the progression of the tumour could be stopped. Depending on the histopathological classification of the malignancies survival rates between 64.3% and 87.5% were achieved for one year.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2001

Pyrokinin/PBAN radio-receptor assay: development and application for the characterization of a putative receptor from the pheromone gland of Heliothis peltigera.

A radio-receptor assay (RRA) for the insect pyrokinin/PBAN family has been developed. The development involved examination of the ligand (3H-tyrosyl-PBAN28-33NH2)-receptor interaction under various incubation conditions and variations on sex pheromone gland membrane preparation. Application of the RRA for a partial characterization of the putative pyrokinin/PBAN receptor in the pheromone gland of H. peltigera revealed age-dependence of its expression. Pharmacological characterization revealed a high correlation between the binding-affinity to the receptor of various PBAN-derived peptides and their in vivo pheromonotropic bioactivity, and shed light on the interaction of backbone cyclic and linear ([Arg27,D-Phe30]PBAN28-33NH2) PBAN antagonists with the receptor.

Animals↗
PubMedDate not supplied

[Resection of a mediastinal parathyroid adenoma by video-assisted thoracoscopy radio-guided by a gamma probe. A case report].

We present a case of primary hyperparathyroidism in a 47 year old woman. The pre-operative 99mTc-sestaMIBI scan detected a single parathyroid adenoma located in the anterior or medium mediastinum. Surgery was carried out following 99mTc-sestaMIBI administration and using gamma probe radio-guided video-assisted thoracoscopy. The aim of this case report is to present this technique that allows adenoma resection with minimally invasive surgery. A reduction of surgical complications and an increase in the probability of surgical success could be obtained.

Adenoma↗
PubMed1996

Synovial osteochondromatosis of the distal radio-ulnar joint.

Synovial osteochondromatosis is an uncommon lesion characterized by cartilagenous and osseous metaplasia of joint synovium. It is typically monarticular, affecting large joints such as the knee and hip, although it has also been described in the ankle, elbow and shoulder. It is exceptionally rare in the hand, but has been reported involving the tenosynovium of the digits and the wrist. We report a rare case of synovial osteochondromatosis involving the distal radio-ulnar joint in a 16-year-old man.

Adolescent↗
PubMed1997

Parametric (integrated backscatter and attenuation) images constructed using backscattered radio frequency signals (25-56 MHz) from human aortae in vitro.

Quantitative ultrasonic tissue characterization using backscattered high-frequency intravascular ultrasound could provide a basis for the objective identification of lesions in vivo. Representation of local measurements of quantitative ultrasonic parameters in a conventional image format should facilitate their interpretation and thus increase their clinical utility. Toward this goal, the apparent integrated backscatter, the slope of attenuation (25-56 MHz) and the value of the attenuation on the linear fit at 37.5 MHz were measured using the backscattered radio frequency signals from in vitro human aortae. Local estimations of these ultrasonic parameters from both normal and atherosclerotic aortic segments were displayed in a B-scan format. The morphological features of these parametric images corresponded well to features of histological images of the same regions. The attenuation from 25-56 MHz of seven segments of the medial layer (both with and without overlying atheroma) were measured using the multinarrow-band backscatter method. The average attenuation in the media at 24 degrees C +/- 3 degrees C was 45 +/- 16 dB/cm at 25 MHz and 102 +/- 13 dB/cm at 50 MHz. This work represents progress toward the development of quantitative imaging methods for intravascular applications.

Aorta, Thoracic↗
PubMed1997

A radio frequency domain complex cross-correlation model to estimate blood flow velocity and tissue motion by means of ultrasound.

This article introduces a mean frequency estimator based on a radio frequency (RF) domain complex cross-correlation model (C3M). The C3M estimator differs from the real cross-correlation model (CCM) estimator in two respects; it is an unbiased estimator of blood flow velocity and/or tissue motion independent of the bandwidth of the RF ultrasound signals, and it provides an estimate of the spatial bandwidth of the RF-signal. The estimators derived from the complex cross-correlation model (mean spatial frequency, mean temporal frequency, spatial bandwidth and signal-to-noise ratio) are based on three complex cross-correlation coefficients. A full derivation and mathematical description of both estimators (C3M and CCM), starting from a Gaussian model of the complex power spectral density distribution of sampled RF signals, are presented. In addition, a thorough performance evaluation of the C3M estimator in comparison with the CCM estimator is carried out by means of simulations to document the effect of signal-to-noise ratio, bandwidth and sample frequency. In the context of the specific simulation conditions considered, the quality of the C3M estimator is shown to offer the best performance (no bias, low standard deviation of the estimate). Taking into account the computational load and the robustness of the C3M estimator, it may be concluded that the C3M estimator combines high quality and modest complexity.

Blood Flow Velocity↗
PubMed1998

In vitro diagnosis of axillary lymph node metastases in breast cancer by spectrum analysis of radio frequency echo signals.

Axillary lymph node status is of particular importance for staging and managing breast cancer. Currently, axillary lymph node dissection is performed routinely in cases of invasive breast cancer because of the lack of accurate noninvasive methods for diagnosing lymph node metastasis. We investigated the diagnostic ability of ultrasonic tissue characterization based on spectrum analysis of backscattered echo signals to detect axillary lymph node metastasis in breast cancer in vitro compared with in vitro B-mode imaging. Immediately after surgery, individual lymph nodes were isolated from axillary tissue. Each lymph node was scanned in a water bath using a 10-MHz instrument, and radio frequency data and B-mode images were acquired. Spectral parameter values were calculated, and discriminant analysis was performed to classify metastatic and nonmetastatic lymph nodes. Forty histologically characterized axillary lymph nodes were enrolled in this study, including 25 nonmetastatic and 15 metastatic lymph nodes. A significant difference existed in the spectral parameter values (slope and intercept) for metastatic and nonmetastatic lymph nodes. Spectral parameter-based discriminant function classification of metastatic vs. nonmetastatic lymph nodes provided a sensitivity of 93.3%, specificity of 92.0%, and overall accuracy of 92.5%. In comparison, B-mode ultrasound images of in vitro lymph nodes provided a sensitivity of 73.3%, specificity of 84.0%, and overall accuracy of 80.0%. Receiver operating characteristic (ROC) analysis comparing the efficacy of both methods gave an ROC curve area of 0.9888 for spectral methods, which was greater than the area of 0.8980 for B-mode ultrasound. Hence, this in vitro study suggests that the diagnostic ability of spectrum analysis may prove to be markedly superior to that of B-mode ultrasound in detecting axillary lymph node metastasis in breast cancer. Because of these encouraging results, we intend to conduct an investigation of the ability of spectral methods to classify metastatic axillary lymph nodes in vivo.

Adult↗
PubMed2000

Classification of arterial plaque by spectral analysis of in vitro radio frequency intravascular ultrasound data.

To test whether radio-frequency analysis of coronary plaques predicts the histological classification, r.f. data were collected using a 30 MHz intravascular ultrasound scanner. Two hundred ninety-nine regions-of-interest from eight postmortem coronary arteries were selected and identified by histology as falling into one of seven different tissue types. These are loose fibrous tissue (n = 78), moderate fibrous tissue (n = 27), dense fibrous tissue (n = 33), microcalcification (n = 14), calcified plaque (n = 55), lipid/fibrous mixture (n = 51) and homogeneous areas of lipid pool (n = 29). On the basis of a previous study, four spectral parameters were calculated for each of the regions-of-interest: maximum power (dB), mean power (dB), spectral slope (dB/MHz) over the bandwidth 18-35 MHz and the intercept of the spectral slope with the 0 Hz axis (dB). A minimum-distance classifier using the Mahalanobis (1948) distance was applied to the data. Following resubstitution of the training data into the classifier, the total correctly classified was 54%. The data were reclassified using three broader tissue groups: (1) calcified plaque, (2) lipid pool and (3) a mixed fibrous category, incorporating loose fibrous tissue, moderate fibrous tissue, dense fibrous tissue, lipid/fibrous mixture and microcalcification. The total correctly classified was 86%. Using "leave-one-out" cross-validation, the classification rates were 48% for seven tissue subgroups and 83% for three broader categories of tissue type.

Cadaver↗
PubMed1989

Radio-gas chromatography.

Radio-gas chromatography (RGC) is a technique that combines the advantages of radioisotope tracer techniques with those of gas chromatography. The constitution and performance of RGC systems in common use are described. The relationships between the chromatographic resolution and detection sensitivity are discussed in a simplified form. Recent developments in RGC systems during the last decade are reviewed. A new detector system, named synchronized accumulating radioisotope detector, which makes it possible to improve the detection sensitivity without decreasing the chromatographic resolution, is discussed. Applications of RGC in the life sciences are briefly presented.

Chemistry, Clinical↗
PubMed1985

Determination of circulating ethyl loflazepate metabolites in the baboon by radio-high-performance liquid chromatography with injection of crude plasma samples: comparison with solvent extraction and thin-layer chromatography.

Circulating ethyl loflazepate metabolites in the baboon were determined, following a single oral administration of the 14C-labelled drug, by radio-high-performance liquid chromatography with injection of crude plasma samples and by selective extraction with thin-layer chromatographic analysis of the radioactive components. Metabolites identified by comparing their chromatographic behaviour with synthetic standards were loflazepate, descarboxyloflazepate and 3-hydroxydescarboxyloflazepate. Loflazepate represented about 70% of the circulating radioactivity; the two other metabolites were present in amounts too small to allow accurate quantification. The parent drug was not present in the blood. Comparison of high-performance liquid chromatography with solvent extraction demonstrated the inaccuracy of the latter to be caused by the conversion of loflazepate to descarboxyloflazepate.

Animals↗
PubMed1997

Determination of unchanged [18F]dopamine in human and non-human primate plasma during positron emission tomography studies: a new solid-phase extraction method comparable to radio-thin-layer chromatography analysis.

Routine determination of [18F]DOPA and its metabolites in plasma is essential for assessment and quantification of presynaptic dopamine function in vivo using a modeling approach with positron emission tomography (PET). The determination of unchanged [18F]DOPA from human and non-human primate plasma using solid-phase extraction (SPE) with Sep-Pak cartridges during PET dopaminergic studies is described here. The results from the studies showed that this new approach in comparsion to a method such as thin-layer chromatography (TLC) possessed a simplicity, rapidity and accuracy as well as good correlation between the two techniques (p<0.0001). A proposed procedure involving radioanalysis on alumina plates (Al2O3) was also developed with an excellent correlation compared to the conventional C18 plates (r=0.96). Thus it could be concluded that the SPE on either C18 or alumina cartridges (Waters) compared to radio-TLC analysis on C18 and alumina systems, appears to be a useful analytical method suitable for correcting the input arterial function in routine clinical PET neurotransmission studies.

Adult↗
PubMed2003

RP-HPLC separation of the diastereomers of technetium-99m labelled tropanes and identity confirmation using radio-LC-MS.

99mTc-TRODAT-1 (technetium(V)-oxo-2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3.2.1]oct-2-yl]methyl](2-mercaptoethyl)amino]ethyl]]amino]-ethanethiolato(3-)) and 99mTc-TRODAT-M, the 4-methylphenyl derivative of 99mTc-TRODAT-1, are at this moment being evaluated in clinical trials as imaging agents for the central nervous dopamine transporter system. Both compounds are formed as a mixture of two major diastereomers. As the tracer concentration in preparations for clinical investigations is very low (30-150 pmol/ml), identification of these 99mTc-complexes was, up to now, carried out indirectly using X-ray diffraction analysis of the corresponding rhenium complexes which can be synthesized in gram amounts. In this study, we developed a convenient and practical reversed phase HPLC-method for purification and isolation of the respective diastereomers of 99mTc-TRODAT-1 and three of its derivatives using mixtures of solvents which are compatible with biological studies, i.e. aqueous buffers and ethanol. Furthermore, direct identity confirmation of the 99mTc-complexes using radio-LC-MS was successfully elaborated.

Chromatography, High Pressure Liquid↗
PubMed1993

[Triquetro-lunar instability. The role of the radio-styloidian index].

Based on a series of 13 isolated triquetro-lunar instabilities, the authors underline the excess of the radio styloidian index measured radiologically. They found a significant difference (p < 0.001) when comparing this series with a group of 100 normal wrists. A similar comparative study of 13 triquetro-lunar instabilities secondary to perilunar dislocations and of a series of 16 hyperlax wrists did not reveal any significant difference. The same applies to a similar parallel study of the ulnar variance index measurements when comparing the various groups with the control group. After reviewing the mechanism of lesions, and disorders of the wrist's axial forces, caused by changes in the ulnar lengths, ulnar styloid overshooting is designated as a risk factor for isolated triquetro-lunar instabilities. Finally, the authors insist on the necessity of proper reduction of radial low end fractures and detachments, and on the shortening of the long ulna, as a "complementary" procedure when treating isolated triquetro-lunar instabilities.

Adolescent↗
PubMed1992

[Radio-carpal amputation and prosthesis].

Radio-carpal amputation was rejected for a long time because of the difficulties of fitting both myoelectrical and mechanical prostheses, only allowing a purely aesthetic prosthesis. As a result of miniaturization of control systems and the progress in computers, we believe that this now constitutes the best site for amputation whenever it is possible. Preservation of the antero-posterior bony contours of the radius allows the use of short sockets attached by a system of clips. In this way, flexion-extension of the elbow is left free and the movements of pronation and supination can be used. Liberation of the proximal joints facilitates integration of the prosthetic hand.

Amputation, Surgical↗
PubMed1993

[Radio-carpal and medio-carpal arthroscopy in instability of the wrist].

Forty-one arthroscopies were performed on previously asymptomatic wrists following trauma. In about 25% of the wrists there was only one specific ligamentous lesion. In 75% however a combination of 2 or several distinct lesions was observed. These lesions, localised on the ulnar aspect of the mid-carpal joint, are more complex than those on the radio-carpal joint on the radial aspect of the carpus. These observations would tend to confirm our present day knowledge of wrist biomechanics but disagree with the currently proposed concepts of instability by several American authors. "Instability" seems to be inadequate to define complex lesions, more adequate would be the simple description of a "dysfunctional state" of the wrist complex. This statement must be related to the position of the carpal bones, which do not show any significant change despite the tears shown. The arthroscopy appears to range first in a series of diagnostic tools. However it concerns mainly the ligamentous layers facing the interior of the joint while lacking information about time elapsed since the actual trauma. We therefore state that arthroscopy may decrease but not exclude diagnostic failures. Type and risk of therapeutic decisions are also appreciated with increased accuracy. No doubt there still remain discrepancies when clinical, arthrographic and arthroscopic examination are compared, which indicates the complementary nature of the technics of investigation, especially in the light of the current state of the biomechanic sciences of the wrist.

Adolescent↗