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At least 289 records · Page 16Linked to original sources
PubMed1999

Baroreflex sensitivity predicts the induction of ventricular arrhythmias by cesium chloride in rabbits.

Previous studies have shown that the autonomic nervous system plays an important role in the genesis of ventricular tachycardia (VT) in patients with long QT syndrome, and in cesium chloride (Cs)-induced VT in animals. The present study investigated whether baroreflex sensitivity predicts the induction of VT by Cs in the rabbit in vivo. Monophasic action potentials (MAPs) of the left ventricular endocardium were recorded simultaneously with the surface ECG in 27 rabbits. Rabbits were divided into 4 groups based on the Cs-induced ventricular arrhythmias: (1) no ventricular premature contractions (No-VPC group), (2) single or paired VPC (VPC group), (3) monomorphic VT (MVT group), and (4) polymorphic VT (PVT group). Baroreflex sensitivity was significantly lower in the MVT and PVT groups than in the No-VPC and VPC groups. The plasma norepinephrine concentration before Cs injection was significantly higher in the MVT group than in the other 3 groups, and the norepinephrine concentration after Cs injection was significantly higher in the MVT and PVT groups than in the No-VPC and VPC groups. Baroreflex sensitivity was negatively correlated with the norepinephrine concentration before Cs injection. These results suggest that autonomic nervous system dysfunction, as defined by reduced baroreflex sensitivity, and elevated plasma norepinephrine concentrations predict increased susceptibility to Cs-induced VT.

Animal Diseases↗
PubMed2002

Optical parametric properties of ultraviolet-pumped cesium lithium borate crystals.

We report the optical parametric properties of cesium lithium borate (CLBO) crystals pumped by UV radiation of the fourth-harmonic generation at 266 nm and the third-harmonic generation at 355 nm of a picosecond Nd:YAG laser. A special optical design was used to avoid damage to the optical elements by the UV-pumped beam at 266 nm. The optical parametric generator (OPG)/optical parametric amplifier (OPA) of the 266-nm-pumped CLBO covers the tuning range from 347 nm in the UV to 1137 nm in the near IR. The 355-nm-pumped CLBO OPG/OPA, on the other hand, is tunable from 447 to 1725 nm. The experimental tuning curves for each CLBO OPG/OPA were measured and compared with the theoretical tuning curves. With a double-pass OPG configuration and a pumping intensity of approximately 6 GW/cm2, the maximum conversion efficiency, including both the signal and the idler, was approximately 11% for the 266-nm-pumped CLBO and is greater than 16% for the 355-nm-pumped CLBO without taking into account the surface losses from the uncoated elements. The bandwidth of this double-pass CLBO OPG at various wavelengths was measured and compared with other optical parametric systems. Because of the small angular dispersion of CLBO, the bandwidth of the OPG and OPA systems is exceptionally narrow, especially for the 266-nm-pumped system. Without the use of any dispersion element, the bandwidth of the 266-nm-pumped system can be as narrow as 0.22 nm at wavelengths far from the degenerate point. Comparison between the experimental bandwidth and the theoretical calculation shows that the bandwidth of the UV-pumped CLBO OPG/OPA is limited mainly by the divergence of the pump beam.

Borates↗
PubMedDate not supplied

Cesium-134 and strontium-85 in strawberry plants following wet aerial deposition.

The understanding of the processes that control the behavior of radionuclides in crops can support policymakers to take actions to protect the environment and safeguard human health. Data concerning the behavior of radionuclides in fruits are limited. Strawberry (Fragaria x ananassa Duchesne) plants were contaminated on the aboveground part by sprinkling an aqueous solution of 134Cs and 85Sr at three growing stages: predormancy, anthesis, and beginning of ripening. Intercepted activity was more affected by the posture and physical orientation of leaves rather than by leaf area or biomass. Fruit interception ranges from 0.2 to 1.2% of the sprinkled activity. Translocation coefficients from leaf to fruit are on the order of 10(-4) for 134Cs and 10(-5) for 85Sr. Translocation reaches its highest intensity between anthesis and ripening. If deposition occurs when plants are bearing fruits, the fruit activity will be affected by the activity initially deposited on the fruit surfaces. This is important for 85Sr as it is not translocated in the phloem. The loss of the dead leaves at the resumption of growth causes high plant decontamination, but a fraction of both radionuclides remains in the storage organs, roots, and shoots, which is retranslocated to fruits in the following spring. The values of the environmental half-time, t(w), after deposition at predormancy are 114 d for 134Cs and 109 d for 85Sr. Cesium-134 tends to be allocated to fruits, while 85Sr remains in leaves and crowns. Translocation of radionuclides to roots results in soil contamination.

Cesium Radioisotopes↗
PubMed1990

Radical surgery compared with intracavitary cesium followed by radical surgery in cervical carcinoma stage IB. Analysis of patients less than or equal to 45 years of age with small tumors with regard to treatment results and ovarian preservation in the primary surgery group.

Forty-nine patients aged less than or equal to 45 years, with cervical carcinoma stage IB (less than or equal to 3 cm) were treated with either primary radical surgery (n = 26), or intracavitary irradiation followed by radical surgery (n = 23). With primary surgery, ovarian function had been preserved in 15 of the 25 patients, who were alive and well. Seven of the primary surgery patients were irradiated postoperatively and 2 others with a central recurrence were cured by irradiation. One other patient, who was not irradiated postoperatively, had an intestinal metastasis and died of the disease. If any of the adverse prognostic factors (as reported in the literature) had been considered as an indication for postoperative irradiation, 17 patients instead of 7 would have been irradiated after primary radical surgery. In the comparable group of 23 patients treated by intracavitary irradiation and radical surgery (and in 4 cases postoperative irradiation as well) there was no recurrence. There was no significant statistical difference between the treatment results in the cesium + surgery group and those who underwent primary radical surgery. Young patients with early cervical carcinoma without prognostic indicators for postoperative irradiation can benefit from primary radical surgery, because their ovarian function can be preserved.

Adenocarcinoma↗
PubMed1987

Purification of Cryptosporidium oocysts and sporozoites by cesium chloride and Percoll gradients.

The lack of an adequate system for the in vitro cultivation of Cryptosporidium spp. has forced researchers to work on infected feces or tissues. Molecular and immunological analyses of Cryptosporidium stages must be preceded by complex preparatory steps involving the concentration, storage, purification, excystation of oocysts, and purification of sporozoites. This paper describes two new procedures for the purification of Cryptosporidium. The first, consisting of pretreatment of oocysts with sodium hypochlorite followed by concentration using a Percoll gradient, is suitable for nucleic acid analyses. The second, a concentration of untreated oocysts using a Cesium chloride gradient, is suitable for biochemical and immunological studies, but requires "fresh" oocysts.

Animals↗
PubMed1999

Histopathological and cellular studies of a case of cutaneous radiation syndrome after accidental chronic exposure to a cesium source.

This study was designed for the histopathological, cellular and biochemical characterization of a skin lesion removed surgically from a young male several months after accidental exposure to cesium-137, with an emphasis on expression of transforming growth factor beta1 (TGFB1) and tumor necrosis factor alpha (TNFA) and the occurrence of apoptosis. Under a hypertrophic epidermis, a highly inhomogeneous inflammatory dermis was observed, together with fibroblastic proliferation in necrotic areas. Immunostaining revealed overexpression of TGFB1 and TNFA inside the keratinocytes of the hypertrophic epidermis as well as in the cytoplasm of the fibroblasts and connective tissue of the mixed fibrotic and necrotic dermis. Inside this dermis, the TUNEL assay revealed areas containing numerous apoptotic fibroblasts next to areas of normal viable cells. Overexpression of TGFB1 was found in the conditioned medium and cellular fractions of both hypertrophic keratinocytes and fibrotic fibroblasts. This overexpression lasted for at least three passages in tissue culture. The present observations were consistent with the central role of TGFB1 in the determination of chronic radiation-induced damage to the skin and a significant involvement of TNFA. In addition, programmed cell death appeared to take place during the remodeling of the mixed fibrotic and necrotic tissue.

Adult↗
PubMed1975

[Curative cesium therapy of small size breast cancers].

224 breast cancers of less than 5 cm diameter were treated by curative cesium therapy with 8 000 rads a tumor in 8 weeks. 125 had had a previous tumorectomy. Survival at 5 years ranges from 76 to 94 p. cent of cases according to the stage, with 85 p. cent for all the cases. 8 out of 10 healed women at 5 years have their breast preserved, which 15 of primary importance.

Breast Neoplasms↗
PubMed1975

[Comparative 131-cesium scintigraphic and electrocardiographic studies of patients following the acute phase of myocardial infarct].

The determination of the extent and site of morphological changes in heart muscle, while still living, after a healed myocardial infarction is of a doubtless theoretical and practical interest. Certain possibilities, in that respect, are revealed by the myocardium scintigraphy with131 cesium. The authors present the results from the scintigraphic and electrocardiographic investigations of 45 patients with a past history of myocardial infarcticn examined in a period of 1 to 6 months post the infarction.

Acute Disease↗
PubMed2002

[Characteristics of mitochondria and myocardium ultrastructure of rats following chronic incorporation of cesium radionuclides 137 Cs].

Ultrastructure, tissue respiration and oxidative phosphorilation were studies in the myocardium of animals after chronic natural irradiation by 137Cs in quantities that can in reality threaten population of radionuclide-polluted regions. Decline in the respiratory activity of the myocardium and ultrastructural disorders can be attributed to the effects of ions of radioactive Cs which is also a potassium antagonist. A hypothesis has been put forward according to which cesium blocks potassium channels in mitochondria and thus changes the volume and configuration of internal mitochondrial membranes, and impacts the respiratory processes. In the opinion of the authors, these changes characterize the mitochondrial phase of apoptosis which, in the event of chronic exposure to radionuclides, is a compensatory-adaptive mechanism eliminating the least immutable subpopulation of cardiomyocites.

Animals↗
PubMed1976

[Improvement of gynecologic radium therapy through the afterloading method using cesium 137].

For all centers performing gynecological contact irradiation the use of afterloading techniques is urgently required, since they eliminate any radiation exposure to the personnel. The radio-therapist may position and control the empty applicators still free from radiation withoug haste. This procedure diminishes the occurrence of overdosages and underdosages. The care for the patients is possible without radiation exposure, and the morbidity of contact therapy can be reduced by occasional mobilization of the patient, the applicator without sources remaining at its place. The fully automatic apparatus "Curietron" using cesium-137 sources (0.662 MeV gamma emission, half-life period 26.6 years) with an equivalent source activity (factor 2.6) yields the dose distribution demanded in the gynecologic field which in practice is identical to that of Ra-226 (medium gamma emission 1 MeV, half-life period 1620 years). With similar dose distribution, a biological and therapeutical effect alike to Ra-226 may be expected from Cs-137. In comparison with Ra-226, the following advantages of Cs-137 may be mentioned: Lower half-value thickness of 5.5 mm lead (low expenses for radioprotection), less danger with handling (no emanation of radioactive gases), and lower contamination risks in case of breaking. The measured dose distributions at equivalent source activity and similar geometry of the applicators revealed the possibility with regard of all techniques of gynecologic irradiation utilized in our field of arriving at similar relative and absolute dose distributions by means of the Cs-137 afterloading technique. Whilst short-term afterloading irradiation with highly active sources, their radiobiological effectiveness being not yet ascertained, has to be tested at appropriate scientific centers, it is necessary to demand afterloading techniques with dosages and duration of irradiations approved over decades for all centers of gynecological contact therapy because of radiation protection.

Cesium Radioisotopes↗
PubMed1992

[Early afterdepolarization and cesium chloride induced ventricular arrhythmias].

This study is to demonstrate the role of early afterdepolarization (EAD) in the cesium chloride induced long QT interval and ventricular arrhythmias by recording monophasic action potential (MAP) of right ventricular endocardium with contact electrode in 12 closed chest dogs. The results suggested that EAD could produce triggered premature ventricular beats and ventricular tachycardias (VT) in situ. The first ectopic ventricular beat of EAD induced VT usually appears close to the peak of the U wave. Short-long-short interval sequence preceding episodes of VT occurred in 89.6% of VT.

Action Potentials↗
PubMed2004

[Case of chronic radiation sickness with subsequent leukemia in track driver subjected to long-external gamma-irradiation (cesium-137)].

The article deals with consequences seen in track driver after prolonged exposure to radiation caused by "lost" gamma-source (cesium-137) that long remained in receptacle of the vehicle's left door. Radiation dose averaged 8 Gy. The authors presented clinical manifestations, changes in peripheral blood and bone marrow, cytogenetic data by progression of radiation hemopoiesis hypoplasy to myelodysplastic syndrome and to acute leukaemia.

Adult↗
PubMed1992

[Effects of tetrodoxin and verapamil on triggered activities induced by cesium chloride in cat heart in vivo].

Cesium chloride (CsCl, 0.5 mmol.kg-1, iv) decreased sinus rate, shortened monophasic action potential duration (MAPD), and induced early after depolarization (EAD) in cat heart in vivo. Tetrodotoxin (TTX, 8 micrograms.kg-1, iv) suppressed the prolonged MAPD. TTX and verapamil (Ver, 0.5 mg.kg-1, iv) decreased the EAD amplitude and suppressed the sustained ventricular tachycardia induced by repeated injection of CsCl. These results suggested that the normal inward sodium "window" current and slow inward current (Isi) carried by calcium or sodium appear to be essential for the occurrence of EAD and triggered arrhythmia if repolarization outward potassium current are blocked.

Action Potentials↗
PubMed1991

Electrophysiological effects of cesium and tetraethylammonium in canine cardiac Purkinje fibers.

Cesium (Cs) and tetraethylammonium (TEA) have been shown to increase action potential duration. However, action potential duration is known to be influenced by the rate of stimulation. In this study, the effect of stimulation rate on action potential characteristics was studied in Cs-treated and TEA-loaded canine Purkinje fiber preparations. Action potentials of Purkinje fibers from Cs-treated and TEA-loaded preparations had longer durations than action potentials of Purkinje fibers from normal preparations. Greater prolongation of action potential duration was observed when the rate of stimulation was reduced in Purkinje fibers from Cs-treated and TEA-loaded preparations than those from normal preparations. Whereas the increase in action potential duration of Purkinje fibers from Cs-treated preparations was accompanied by a significant membrane depolarization, no change in membrane potential was observed in Purkinje fibers from TEA-loaded preparations. In some Cs-treated and TEA-loaded preparations, the prolonged duration observed at slow stimulation rates was associated with the appearance of early afterdepolarizations. Lidocaine and cromakalim, agents known to reduce action potential duration in normal Purkinje fibers, also shortened action potential duration in Purkinje fibers from both Cs-treated and TEA-loaded preparations. However, lidocaine and cromakalim caused a significant membrane depolarization in Cs-treated Purkinje fibers but not in TEA-loaded Purkinje fibers. Our results suggested that although Cs and TEA are capable of producing rate-dependent prolongation of action potential duration and the occurrence of bradycardia-dependent early afterdepolarization, differences exist in Cs-treated Purkinje fibers in terms of the appearance of membrane depolarization at reduced stimulation rate and in the presence of lidocaine and cromakalim.

Action Potentials↗
PubMedDate not supplied

Effects of ingestion of radioactive cesium on behavioral indices in rats.

The experiments were carried out on 35 male (M) and female (F) rats contaminated by ingestion of Cesium--137(Cs) for 38 or 84 days; the total Cs activity was 288 Bq 460 Bq, and respectively. The duration of forced swimming decreased significantly in the contaminated groups as compared with controls (n = 16). The active avoidance reaction in the shuttle-box shows an increase in F groups and a decrease in M groups. The total latency time of the same reaction was lower in F and M treated rats on the first day of learning. The score of aggressive behavior rose significantly, especially in group F. These results can be explained by the sex dependence of Cs accumulation and by the neurotoxic action of the radionuclide on several central neural areas including monoaminergic and endocrine mechanisms.

Administration, Oral↗