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At least 937 records · Page 52Linked to original sources
PubMed2005

Basal cell carcinoma and World War II-era cathode ray oscilloscope exposure.

BACKGROUND: There is a high prevalence of skin cancer in World War II servicemen stationed in the Pacific theater as a result of various risk factors such as exposure to ultraviolet radiation and genetic predisposition. OBJECTIVE: We sought to describe whether a possible association exists between basal cell carcinoma (BCC) development and the use of high-voltage cathode ray tube (CRT) oscilloscopes manufactured around 1940 to 1955, which were a source of X-radiation. METHODS: We present a case series of 9 men aged 65 to 93 years who presented with similar head and neck distributions of BCC and a history of extensive use of early CRT oscilloscopes during and shortly after the World War II era. The patients were interviewed and their medical records reviewed to determine CRT exposure times and BCC location, subtype, and treatment. Representative BCC histologic sections were reviewed. RESULTS: A total of 230 BCCs of the head and neck region were identified and mapped. Questionnaires determined a minimum exposure of 600 (range, 624-9600) hours within a 60-cm distance of early CRT screens in all patients. The average number of aggressive histologic subtypes was 23.5%. The average number of Mohs micrographic surgery layers required to obtain negative margins was 1.99 compared with 1.63 in the control group treated by the same Mohs micrographic surgeon (P < .002). CONCLUSION: This descriptive study is the first to suggest that ionizing radiation from early CRT oscilloscopes may be a factor in the development of multiple BCCs of the head and neck with increased subclinical spread.

Aged↗
PubMed2005

Estimation of free radical formation by beta-ray irradiation in rat liver.

In vivo free radical reactions in rat liver as a result of exposure to low-dose beta-radiation was evaluated with electron paramagnetic resonance (EPR) spectroscopy by monitoring the reduction of the nitroxyl spin probe after intravenous administration. The EPR signal intensity of a nitroxyl probe as a function of time in bile flow was monitored by cannulating the bile duct through the cavity of an X-band EPR spectrometer. The results show that the rate of nitroxyl signal loss was higher in rats whose livers were exposed to beta-rays compared to unexposed rats. However, the rate of signal loss was lower in animals whose organs were exposed to air by opening the abdominal cavity. In vitro experiments also showed that the nitroxyl EPR signal loss was greater in an atmosphere of nitrogen than in air. Results suggest that under low levels of tissue oxygen, exposure to beta-rays results in nitroxyl signal loss, which may be mediated by free radical dependent pathways. When tissue oxygen were higher, hydrogen peroxide mediated oxidation of hydroxylamine may predominate resulting in a signal loss of smaller magnitudes. This study shows possible evidence of reactive oxygen species formation by low-dose beta-ray irradiation in a living animal.

Animals↗
PubMed2005

Formation of polyelectrolyte multilayers from polysaccharides at low ionic strength.

Layer-by-layer deposition of sodium carboxymethylcellulose (NaCMC) and chitosan (CHI) was used to create polyelectrolyte multilayers on ellipsoidal beta-FeOOH particles at low ionic strength. Using electro-optics, we investigated the formation of films in dependence on the polyelectrolyte charge density by controlling pH of the dipping solutions. We found out a linear growth of the CMC/CHI films when they are constructed from highly charged CHI (at pH 4.0) and weakly charged NaCMC (at pH 4.0 and 5.5). The hydrodynamic thickness of the film constructed at pH 4.0/4.0 is unusually large for a linearly growing film (ca. 220 nm after deposition of 8 bilayers), but it strongly decreases (ca. 4 times) with increasing ionization of NaCMC (at pH 5.5). In both cases, the multilayer buildup proceeded through a series of adsorption-desorption steps. This was explained by a partial loss of CHI from the film surface on exposure to the solution of longer NaCMC molecules. The irregular film growth correlated quite well with the variations in the electrical polarizability of the polymer-coated particles. This correlation enabled us to conclude that the adsorption of both polymers occurs only on the film surface, with no diffusion in and out of the film bulk during deposition of each CMC/CHI bilayer.

Adsorption↗
PubMed2006

Counterion release from adsorbed highly charged polyelectrolyte: an electrooptical study.

The adsorption of sodium poly(4-styrene sulfonate) on oppositely charged beta-FeOOH particles is studied by electrooptics. The focus of this paper is on the release of condensed counterions from adsorbed polyelectrolyte upon surface charge overcompensation. The fraction of condensed Na+ counterions on the adsorbed polyion surface is estimated according to the theory of Sens and Joanny and it is compared with the fraction of condensed counterions on nonadsorbed polyelectrolyte. The relaxation frequency of the electrooptical effect from the polymer-coated particle is found to depend on the polyelectrolyte molecular weight. This is attributed to polarization of the layer from condensed counterions on the polyion surface, being responsible for creation of the effect from particles covered with highly charged polyelectrolyte. The number of the adsorbed chains is calculated also assuming counterion condensation on the adsorbed polyelectrolyte and semiquantative agreement is found with the result obtained from the condensed counterion polarizability of the polymer-coated particle. Our findings are in line with theoretical predictions that the fraction of condensed counterions remains unchanged due to the adsorption of highly charged polyelectrolyte onto weakly charged substrate.

Journal Article↗
PubMed2005

An EPR and ENDOR study of gamma- and beta-radiation sterilization in poly (lactide-co-glycolide) polymers and microspheres.

EPR/ENDOR spectroscopy was used to characterise the free radicals generated in a series of PLGA raw polymers and microspheres (with lactide:glycolide compositions of (75:25), (65:35) and (50:50)) after exposure to gamma (gamma-) and electron beam (beta-) irradiation at room temperature. Both sets of irradiated samples produced analogous EPR spectra, indicating that the type and distribution of free radicals generated by gamma-irradiation are similar to those generated by beta-irradiation. The radicals were identified by EPR simulations as the chain scission species -(CHO-(approximately 27% abundance),-C(CH(3))O- ( approximately 23% abundance) and the terminal-C(CH(3))-OR fragment (approximately 50% abundance), and these assignments were supported by the ENDOR analysis. The latter two radical species were demonstrated to originate from the lactide component of the PLGA polymer. Overall systematically higher radical concentrations were found as the lactide content of the PLGA raw polymer and microspheres increases (ie., 75:25 > 65:35 > 50:50) for both gamma- and beta-irradiation. However, while the relative concentrations of free radicals was similar in the raw polymer samples after exposure to gamma- or beta-irradiation, a substantial difference was found for the microsphere samples; an approximate doubling of the radical content was found in the gamma-irradiated PLGA microspheres compared to the identical beta-irradiated microspheres.

Beta Particles↗
PubMed2005

Low dose beta-emitter source induces sexual reproduction instead of fragmentation in an earthworm, Enchytraeus japonensis.

We examined whether background radiation, or radiation at a slightly higher level, plays a role in the reproduction of a terrestrial earthworm. Enchytraeus japonensis a recently described terrestrial oligochaete, reproduces asexually by fragmentation and subsequent regeneration. Following radiation exposure in which the worms were subjected to a 32P beta-emitter source at 15 times the background dose rate (4.5 microGy/h), a statistically significant decrease in the number of fragmentations was observed as compared with the sham controls. At that time, in a stained preparation with haematoxylin and eosin (HE), sexual reproduction occurred instead of asexual fragmentation, and mature oocytes were observed in the body of grown worms. However, increasing the radiation dose rate by 30 microGy/h resulted in the complete disappearance of the radiation-induced effects, i.e., fragmentation again occurred after 14 h. The results of this study indicate that a lower dose of radiation may be essential to achieve sexual reproduction, inducing an inhibition of fragmentation (asexual reproduction), but at higher, more cytotoxic doses of radiation these effects are negated.

Animals↗
PubMed2004

Combining the radiosensitive Beta MicroProbe to nuclear magnetic resonance: theoretical approach for in vivo studies in small animals.

In vivo small animal imaging with multiple modalities has become an important tool in modern biomedical research. Indeed, combining exploratory techniques allows simultaneous recording of complementary data, which is required to elucidate complex physiopathological mechanisms. In this field, because of strict technical constraints in vivo, an exciting challenge remains in the combination of Nuclear Magnetic Resonance (NMR) and Positron Emission Tomography (PET). Coupling NMR with a radiosensitive Beta MicroProbe offers therefore a very interesting technical alternative. Here, we assessed the feasibility of this new combination by theoretically evaluating the ability of the Beta MicroProbe to monitor radioactivity in a magnet. To that aim, we modelled with Geant4 the effect of an intense magnetic field on the probe field of view and showed that the field should not have an impact on the global efficiency of the probe.

Animals↗
PubMed2006

Competitive displacement binding assay on rat brain sections and using a beta-imager: application to mu-opioid ligands.

A new approach of competitive displacement binding assay using brain sections and a beta-imager is presented to estimate binding parameters such as affinity and selectivity of new compounds or to characterize receptor families or subtypes of receptors in small brain regions. This method includes a preliminary saturation assay intended to define the optimal concentration of displaceable radio-labeled ligand followed by the determination of displacement constants (IC(50) and K(i)) in cerebral regions rich in studied receptor. The technique application was demonstrated in seven rat brain structures, using displacement of the selective tritiated mu-opioid ligand [(3)H]-DAMGO by six opioid ligands: a specific agonist (DAMGO), less specific agonists (morphine, remifentanil), a non-specific antagonist with good affinity for mu receptors (naloxone) and ligands specific of other opioid subtypes (naltrindole, U50.488). Radioactivity counts were collected during 48 h. The assay-validation was performed by measuring intra- and inter-assay variation on determinations and by comparing presently obtained K(i) values with data from recognised methodologies. Both prove the accuracy of the proposed method.

Analgesics, Opioid↗
PubMed2004

Recanalization of arterial thrombus, and inhibition with beta-radiation in a new murine carotid occlusion model: MRNA expression of angiopoietins, metalloproteinases, and their inhibitors.

BACKGROUND: Recanalization is an important physiologic phenomenon because it can efficiently reestablish circulation after thrombosis. We attempted to characterize molecular events related to recanalization or organization of arterial thrombus in a new murine model by studying genes reported to be involved in angiogenesis or neointima formation. METHODS: Platinum coils, radioactive phosphorus 32 coils or not, were implanted in the carotid artery in mice to cause thrombotic occlusion. The outcome of the occlusion was followed up with transmyocardial angiography and pathologic analysis at 2, 6, or 15 days. Angiographic results were compared with the Pearson chi2 test. Messenger RNA expression of von Willebrand factor (vWF); smooth muscle alpha-actin (SMA+); platelet endothelial cell adhesion molecule-1 (PECAM-1); vascular endothelium cadherin (VE-Cad); endothelial nitric oxide synthase (eNOS); vascular cell adhesion molecule-1 (VCAM-1); tumor necrosis factor alpha (TNF-alpha); matrix metalloproteinase (MMP-9, MMP-12, and MMP-14), and tissue inhibitors of MMPs (TIMPs: TIMP-1, TIMP-2, TIMP-3, TIMP-4); angiopoietins (Ang-1, Ang-2); and receptors Tie-1 and Tie-2, were analyzed with reverse transcriptase polymerase chain reaction 2, 6, and 15 days after surgery. Levels of mRNA expression were compared with analysis of variance and the Student t test. RESULTS: Carotid arteries implanted with nonradioactive 0.015-caliber coils were occluded in 84% of arteries on day 2, but in only 57% of arteries on day 15, which confirms that recanalization occurred in this model. Arteries implanted with 0.015-caliber 32P coils did not become recanalized, and 100% were occluded on day 15 (n = 13; P = .006). Recanalization was associated with endothelial-like cell-lined channels, whereas persistent occlusion was caused by complete filling of the lumen with conjunctive tissue. Coil occlusion, with or without recanalization, was followed by decreased expression of vWf, VE-Cad, eNOS, VCAM-1, MMP-2, TIMP-1, and TIMP-2; stable expression of PECAM-1, SMA+, and TIMP-3; and overexpression of Ang-1 and Ang-2, MMP-9, MMP-14, and TIMP-4. Statistically significant differences when arteries were implanted with 32P coils included decreased expression of TIMP-4 (P = .011) and increased expression of MMP-9 (P = .02). CONCLUSION: Recanalization and organization of arterial thrombus is associated with expression of genes involved in angiogenesis and neointima formation. Recanalization can be prevented with beta-radiation, but molecular mechanisms remain to be refined. CLINICAL RELEVANCE: A better understanding of molecular mechanisms involved in angiogenesis has permitted its regulation as a new option in treatment of various diseases. Inhibition of angiogenesis may help control diseases such as cancer, arthritis, or diabetes retinopathy. On the other hand, stimulation of angiogenesis may palliate conditions associated with insufficient blood supply, such as ischemic heart disease or critical limb ischemia. Yet little is known regarding recanalization (to be differentiated from thrombolysis), a cellular process that occurs concurrently with thrombus "organization." Recanalization is an important physiologic phenomenon because it can efficiently reestablish antegrade circulation after thrombosis both in veins and in arteries, and could be modulated for therapeutic purposes. Thus our efforts at better understanding of mechanisms involved in recanalization could be used, in addition to its promotion to recover flow after thrombotic occlusions, to prevent its occurrence after endovascular interventions designed to permanently occlude aneurysms.

Angiography↗
PubMed2006

Altered lipid, apolipoprotein, and lipoprotein profiles in inflammatory bowel disease: consequences on the cholesterol efflux capacity of serum using Fu5AH cell system.

Epidemiological data suggest a link between chronic inflammation condition and atherosclerosis. Infection and inflammation can also impair lipoprotein metabolism and produce a wide variety of changes in plasma concentrations of lipids and lipoproteins. Twenty-one patients with inflammatory bowel diseases (IBDs) and 28 healthy subjects were recruited. Serum concentrations of lipids, lipoproteins, apolipoproteins, leptin, ghrelin, and inflammation markers (C-reactive protein and serum amyloid A) were measured, and subjects' lipoproteins were characterized. The ability of patients with serum IBD to efflux free cell cholesterol was measured. Serum cholesterol, high-density lipoprotein cholesterol, apolipoprotein (apo) A-I, apoC-II, apoC-III bound to apoB, phospholipid, and phospholipids not bound to apoB levels were significantly lower, whereas serum triglyceride, serum amyloid A, and C-reactive protein levels were significantly higher in patients with active IBD. Apolipoprotein A-I immunoreactivity (pre-beta small particles and small alpha-high-density lipoprotein particles) is decreased in patients with IBD. In contrast, apoE immunoreactivity (slow/small apoE containing lipoprotein particles [LpE particle]) increased in these patients. The efflux capacity of serum from patients with IBD using [(3)H]-cholesterol-labeled Fu5AH cells was reduced (P < .005). Our results demonstrate that, in subjects with active IBD, inflammation leads to alterations in lipid, apolipoprotein, and lipoprotein profiles and reduced cholesterol efflux. These changes are similar to those proposed to promote atherogenesis and may contribute to the development of cardiovascular events.

Adult↗
PubMedDate not supplied

Intravascular probe for detection of vulnerable plaque.

PURPOSE: Coronary angiography defines geometry of lumen of artery. However, perhaps 70% of heart attacks occur when minimally obstructive thin capped fibroatheroma rupture, causing thrombus and arterial occlusion. We have developed an intravascular imaging detector to identify vulnerable coronary artery plaque. PROCEDURE: Detector measures beta or conversion electron emissions from plaque-binding radiotracers. Detector assembly fits into a 2-mm diameter catheter and overcomes technical constraints of size, sensitivity, and conformance to intravascular environment. RESULTS: Device was tested by stepping test point sources past detector to verify function. System resolution is 6.7 mm and sensitivity is 400 cps/microCi one mm from detector. CONCLUSION: This prototype is a first step in imaging of labeled vulnerable plaque in coronary arteries. This type of system may assist in development of targeted and cost effective therapies to lower incidence of acute coronary artery diseases (CAD) such as unstable angina, acute myocardial infarction, and sudden cardiac death.

Beta Particles↗
PubMed2004

Clinical quality assurance for endovascular brachytherapy devices.

BACKGROUND AND PURPOSE: Endovascular brachytherapy is still an important therapy modality with a high number of treated patients per year. Quality assurance of devices used has been addressed already in several publications (AAPM, DGMP, ESTRO, NCS). However, there are no clear recommendations given on test procedures and related equipment. Our experience with four different devices containing beta- ((32)P, (90)Sr/Y) and gamma-sources ((192)Ir), which were used in clinical routine during the last 3 years is described. PATIENTS AND METHODS: The incoming check includes leakage radiation, missing catheter interlock, positioning test, timer check, interrupt button check, power-off test and verification of the manual retraction facility. Dose profiles are measured using GafChromic film. Source strength verification is performed using well type chambers or air-kerma measurements. In addition, the proposed reference absorbed dose rate at 2 mm distance from the source centre is measured with a dedicated film dosimetry technique where two additional films are exposed to two known doses in a (60)Co field for calibration. RESULTS: Dosimetrical parameters (dose profiles, source strength) are found to be within +/-10% of the manufacturers specifications. The reference dose rate measured with film is on average +3.1% for 13 (90)Sr seed trains, +8.1% for three (32)P wire sources and -3.7% for one (192)Ir seed ribbon compared to the source certificate. The activity of 30 individual (32)P wire sources measured by using a calibrated well type chamber showed a deviation of mean -0.3%, the activity of 16 (192)Ir seed ribbons determined with air kerma measurements a deviation of mean 2.8%. CONCLUSIONS: The QA programme introduced in our department provides methods to verify all relevant parameters proposed by international recommendations. Film dosimetry can be used as independent verification of the reference dose rate within a 10% limit.

Beta Particles↗
PubMed2004

Optimal source position for irradiation of coronary bifurcations in endovascular brachytherapy with catheter based beta or iridium-192 sources.

BACKGROUND AND PURPOSE: Intracoronary brachytherapy after percutaneous transluminal coronary angioplasty (PTCA) is usually performed with catheter-based treatment techniques in a straight vessel segment. There is a growing interest for treatment of bifurcations, which requires consecutive positioning of the source in main vessel and side branch. MATERIALS AND METHODS: In-house developed software (IC-BT doseplan) is used to explore the optimal positioning of the source in modelled bifurcations with different shape for the source types available in our hospital, i.e. (90)Sr/(90)Y, (32)P and (192)Ir. The results were summarised in look-up tables. The usefulness of these look-up tables was tested on various clinical examples. RESULTS: Tabulated results for the modelled bifurcations yield an estimation of the distance between the sources (gap width) in relation to the geometry and source type: (90)Sr/(90)Y gap range 3-8.5 mm, (32)P gap range 2-7 mm and (192)Ir gap range 3.5-8 mm. The average dose relative to 2 mm from the source axis is: (90)Sr/(90)Y, (mean+/-SD) 120+/-40%; (32)P, 125+/-50% and (192)Ir, 120+/-22%. The look-up tables also provide the coarse location and value of maximum and minimum dose: (90)Sr/(90)Y, 220-60%, (32)P, 230-55% and (192)Ir, 170-85%. It appeared that the look-up tables provide a good approximation of the optimal gap width in the clinical examples. CONCLUSIONS: Tabulated optimal gap widths are very useful for quick estimation of the required gap width for a given bifurcation and source type, in case the prescribed dose in both vessels is the same. In unfavourable geometries there is a risk of local underdosage. Individual treatment planning using a program such as IC-BT doseplan is then recommended.

Angioplasty, Balloon, Coronary↗
PubMed2005

Randomized blinded clinical trial of intracoronary brachytherapy with 90Sr/Y beta-radiation for the prevention of restenosis after stent implantation in native coronary arteries in diabetic patients.

BACKGROUND: We report a double-blind, randomized clinical trial of intracoronary beta-radiation for prevention of restenosis after stent implantation in native coronary de novo lesions in diabetic patients. METHODS: After successful stent implantation in native coronary de novo lesions, 106 lesions in 89 diabetic patients were randomly allocated to treatment with beta-radiation with 18 Gy at 1 mm vessel depth (n = 53) or placebo treatment (n = 53). RESULTS: Angiographic analysis at 9 month follow-up revealed a late lumen loss of 0.7+/-0.9 mm in the radiotherapy group versus 1.2+/-0.8 mm in the control group at the injured segment (P = 0.006), 0.9+/-1.0 versus 1.3+/-0.7 mm at the radiated segment (P = 0.02), and 0.9+/-1.0 versus 1.3+/-0.7 mm at the target segment (P = 0.04) (defined as active source length plus 5mm on proximal and distal sites). Binary restenosis rates were significantly lower in the radiation group in all subsegments (injured segment: 10.9 versus 37.3%, P = 0.003; radiated segment: 21.7 versus 49.0%, P = 0.005; target segment: 23.9 versus 49.0%, P = 0.01). Target lesion revascularization for restenosis was required in nine lesions (17.6%) in the radiotherapy group versus 18 (34.0%) in the placebo group (P = 0.05). Late thrombosis occurred in four radiated patients (after premature discontinuation of antiplatelet therapy in all), resulting in a major adverse clinical event rate of 37.2% in the brachytherapy group versus 38.6% in the placebo group (P = ns). CONCLUSIONS: In diabetic patients with de novo coronary lesions, intracoronary radiation after stent implantation significantly reduced restenosis. However, this clinical benefit was reduced by the frequent occurrence of late thrombosis.

Aged↗
PubMed2006

Randomized comparison between intracoronary beta-radiation brachytherapy and implantation of paclitaxel-eluting stents for the treatment of diffuse in-stent restenosis.

BACKGROUND AND PURPOSE: Intracoronary brachytherapy was the primary therapeutic option for the treatment of in-stent restenosis (ISR) during the last years. Especially for the treatment of diffuse ISR (lesions >10mm), beta-source brachytherapy was significantly superior to singular balloon angioplasty. Despite lacking clinical database, the implantation of drug eluting stents recently became a common procedure for the treatment of ISR. This randomized trial aimed to compare the efficacy of beta-brachytherapy with beta-radioisotopes (90)Sr/(90)Y and paclitaxel-eluting stent implantation for the treatment of diffuse ISR. MATERIAL AND METHODS: Thirty-seven patients with diffuse ISR were randomly assigned to beta-brachytherapy after balloon angioplasty (Beta-Cath in 17 patients) or paclitaxel-eluting stent implantation (Taxus-Express2 in 20 patients). Six-month clinical follow-up was obtained for all patients, while angiographic follow-up was available for 30 patients. RESULTS: Binary ISR (restenosis >50%) within target segment was observed in three patients treated with Beta-Cath, of which one needed target segment revascularisation for recurrent ISR, whereas no significant restenosis occurred in the patients treated with Taxus-Express2 (P=0.037). No further major adverse cardiac (target segment revascularisation, myocardial infarction, death) was found in either group (P=NS). Stent implantation was the more time-saving (31+/-11 min versus 60+/-23 min, P<0.001) procedure. CONCLUSIONS: Although this trial revealed a significant reduction of binary restenosis in the Taxus-Express2 arm, we found no difference in clinical outcome after implantation of paclitaxel-eluting stents for the treatment of diffuse ISR when compared to beta-brachytherapy.

Angioplasty, Balloon, Coronary↗
PubMed2005

Intraoperative electrons.

Intraoperative radiotherapy (IORT) has been used for many years for treating patients with various locally-advanced malignancies, usually combined with external-beam radiation therapy (EBRT). Long-term results confirm that IORT improves local control, which is generally associated with increased survival. Recently, electron-beam IORT has been used as the sole treatment for patients with earlier-stage cancers, especially for breast tumors, with extremely promising results. Most of this work has been done at the European Institute of Oncology in Milan. We report the rationale and techniques of the use of electron intraoperative treatment (ELIOT) and the results of our different clinical studies. In our opinion, ELIOT may be an excellent alternative to EBRT for the treatment of patients with early-stage breast cancer. However, intensive long-term follow-up is needed to fully evaluate local control and possible side effects.

Beta Particles↗
PubMed1985

An update on therapeutic uses of radiotracers in neoplastic disease.

The key to delivering radiation to a lesion by means of internally administered radiopharmaceuticals is specificity of localization (a high lesion-background ratio). Factors that may limit this localization are pointed out. Potential alteration of the residence time within the lesion and use of radiation-sensitizing agents may bring new applications for radionuclides in therapy. The most common therapeutic applications of radiopharmaceuticals are outlined.

Beta Particles↗