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PubMed2002

High beta and electron dose from 192Ir: implications for "gamma" intravascular brachytherapy.

PURPOSE: Trains of multiple 192Ir seeds are used in many clinical trials for intravascular brachytherapy. 192Ir source is commonly considered as a gamma emitter, despite the understanding that this radionuclide also emits a wide range of electron and beta energies, with a similar range of energy. The high dose from betas and electrons in the submillimeter range due to unsealed ends of seed sources should be precisely quantified to fully understand the backdrop for complications associated with 192Ir coronary artery brachytherapy. METHODS AND MATERIALS: Monte Carlo simulations (MCNP4C code) were performed for a model 5-seed 192Ir train used in SCRIPPS, GAMMA, and the Washington Radiation for In-Stent Restenosis (WRIST) randomized clinical trials. A stack of radiochromic films was also used to measure the dose distributions for an actual 6-seed train. RESULTS: In the submillimeter range very close to the source, Monte Carlo results show that betas and electrons deposit a higher dose than 192Ir photons (gamma and X-rays) over the interseed gap. A high luminal dose from the combined effects of betas, electrons, and photons emitted from 192Ir can be deposited, particularly between seeds. When prescribing 15 Gy at 2 mm, the combined dose can be as high as 160 Gy at 0.5 mm. Different peak doses near the interseed gaps were noted, which may be due to variability of seed-end surfaces and nonuniformity of seed activity within a real multiseed train. Dose-volume histograms (DVH) of lumen surfaces were evaluated for an eccentric seed train. The DVH parameters indicating the extent of hot spots in the lumen wall, DV(10), DV(5), DV(2), and DV(1) (dose received by 10, 5, 2, 1% respectively of the total lumen surface), can be as high as 55, 76, 81, and 155 Gy for a lumen with 3-mm diameter, and 75, 80, 110, and 158 Gy for a narrow 2-mm lumen. CONCLUSION: 192Ir multiple seed trains used in the SCRIPPS, GAMMA, and WRIST trials can deposit a very high dose to the luminal wall. A particularly high electron and beta dose can be delivered near the interseed gap if the source is not centered in the catheter and lumen. The dose from 192Ir betas and electrons may partially explain adverse outcomes reported from 192Ir multiseed clinical trials. Improvement of the encapsulation design to filter out the betas and electrons should be seriously considered.

Beta Particles↗
PubMed2003

Beta dose-rate distributions in microscopic spherical tumors for intraperitoneal radioimmunotherapy.

PURPOSE: This work was designed to calculate the radial beta dose-rate profiles through microscopic spherical tumors. Its application is in the treatment of micrometastases in the peritoneal cavity by the intraperitoneal administration of radiolabeled immunoliposomes. METHODS AND MATERIALS: Using previously published data for the dose-rate as a function of distance from a point source of activity, dose-rate profiles through five sizes of tumors (radii: 10 microm, 50 microm, 100 microm, 500 microm, 1 mm) for six different radionuclides ((188)Re, (186)Re, (32)P, (90)Y, (67)Cu, (131)I) were calculated. Dose-rate profiles were calculated for two source geometries: (1) a large bath of radioactivity in which the tumor is submerged, and (2) surface-bound radioactivity that results from tumor targeting. RESULTS: The bath geometry produced profiles that were uniform for sufficiently small tumors. For high-energy emitters (i.e., (90)Y and (188)Re), uniformity was maintained up to a tumor radius of 100 microm. For lower energy emitters (i.e., (67)Cu and (131)I) deviations from uniformity start to appear at a tumor radius of 50 microm. Surface-bound radioactivity produced a much greater range of dose-rates within tumors of all sizes. Lower energy emitters bound to the surface of tumors produce higher dose-rates for very small micrometastases compared with high-energy emitters. Upon consideration of the simultaneous contributions from both source geometries, we believe that liposome-mediated radioimmunotherapy would benefit from the inclusion of a high-energy beta emitter, possibly as a component of a cocktail of radionuclides. CONCLUSIONS: The calculated dose-rate profiles provide a tool for making tumor control probability estimations for micrometastases and for assessing the potential benefit offered by a targeted approach over a nontargeted approach. These calculations also suggest that the inclusion of a high-energy beta emitter is appropriate for this treatment modality.

Beta Particles↗
PubMed2003

Vascular brachytherapy using a beta emitter source in diabetic patients with in-stent restenosis: angiographic and clinical outcomes.

PURPOSE: The management of diabetic patients with restenosis after percutaneous coronary intervention remains a significant challenge. Diabetic patients remain at significant risk of restenosis despite stent implantation. This retrospective analysis was performed to determine the extent to which vascular brachytherapy improves late clinical and angiographic outcomes in diabetic patients compared to conventional therapy and compared to patients' nondiabetic counterparts. METHODS: Pooled data from two studies (START [Stents and Radiation Trial] and START-40 trials) of patients (204 diabetic, 477 nondiabetic) receiving vascular brachytherapy (VBT) with a (90)Sr/(90)Y source after conventional percutaneous coronary intervention for in-stent restenosis comprise the study population. The radiation delivery system used in both studies was the Beta-Cath system. The prescribed dose at 2 mm from the centerline of the source axis was 18.4 Gy or 23 Gy, depending on vessel diameter. The reference vessel diameter, minimal lumen diameter, and percent diameter stenosis were measured before the intervention, at the conclusion of the procedure, and at the 8-month follow-up examination. The Breslow-Day test was used to formally assess the similarity of treatment effect between diabetic and nondiabetic patients. RESULTS: Target lesion and target vessel revascularization rates and angiographic restenosis rates in diabetic and nondiabetic patients treated with beta radiation or placebo were analyzed. Diabetic patients were more likely to have longer and more complex coronary lesions. In-hospital outcomes in diabetic and nondiabetic patients were similar, irrespective of treatment status. At 8 months, patients treated with beta radiation exhibited less target lesion revascularization (diabetic: 10.9% vs. 22.7%, p = 0.02; nondiabetic: 12.8% vs. 22.3%, p = 0.007) and less target vessel revascularization (diabetic: 14.7% vs. 25.3%, p = 0.06; nondiabetic: 16.6% vs. 23.6%, p = 0.06) compared to placebo. In-stent binary angiographic restenosis was lower in irradiated patients (diabetic: 19.4% vs. 37.3% for placebo, p = 0.01; nondiabetic: 12.9% vs. 43% for placebo, p < 0.001). However, restenosis beyond the stent site reduced the impact of VBT, regardless of diabetic status. The magnitude of the treatment effect for target lesion and target vessel revascularization rates was similar between diabetic and nondiabetic patients. CONCLUSIONS: Previously published institutional experiences have suggested that diabetic patients benefit from the use of VBT in the management of in-stent restenosis. This analysis now provides direct evidence to support the role of beta radiation VBT in this patient population. Diabetic patients undergoing this therapy are just as likely to benefit from it as their nondiabetic counterparts.

Beta Particles↗
PubMed2004

Successful reduction of in-stent restenosis in long lesions using beta-radiation--subanalysis from the RENO registry.

PURPOSE: Long lesions remain a challenging task in interventional cardiology, with a high propensity of restenosis, especially within the stented segment. Although intracoronary gamma-radiation has been proved to reduce diffuse in-stent restenosis in long lesions, such an effect remains to be determined using beta-radiation. METHODS AND MATERIALS: Of 1098 consecutive patients at 46 European centers treated with localized beta-radiation ((90)Sr, Novoste Beta-Cath System), 139 patients (mean age 61.5 +/- 10.7 years, 84% male, 22% with diabetes mellitus) with lesions treated using a >40-mm source length underwent radiation using a single 60-mm source train (34%) or a stepping/pullback procedure with a 30-mm (12%) or 40-mm (87%) source length after conventional interventional procedures. The mean lesion length was 35.3 +/- 17.9 mm. RESULTS: Technical success was achieved in 96% of cases. Geographic miss was noted in 9 patients (6.5%). The reference (placebo) group was obtained from the Washington Hospital Center for In-Stent Restenosis Trial (WRIST) and the WRIST Trial for long lesions (LONG WRIST) studies by selecting the cases (94 patients) that required a dummy source length >/=13 seeds (or >51 mm in length). Statistically significant improvement was noted in late angiographic restenosis (34.7% vs. 76.5%, p <0.0001), target vessel revascularization (14.9% vs. 60.6), and major adverse cardiac events (i.e., death, myocardial infarction, or total vessel revascularization) (17.9% vs. 64.9%, p <0.0001) at 6 months in reference to the nonradiation group. CONCLUSION: This subanalysis from the Radiation in Europe with Novoste study confirms the safety and efficacy of beta-radiation combined with conventional interventional procedures in patients with diffuse, long, in-stent restenosis

Aged↗
PubMed2000

Design and dosimetry of a novel 90Y beta source to prevent restenosis after angioplasty.

PURPOSE: Post-dilatation irradiation of the vessel wall is currently under investigation for prevention of restenosis after balloon dilatation. For the irradiation, special sources were designed for animal experiments which would give equivalent irradiation conditions and doses to the vessel wall that would later be employed for human application. METHODS AND MATERIALS: For the planned irradiations, a specially designed yttrium-wire of 0.45-mm diameter coated with a thin shrink tube to prevent contamination was deployed. Several leakage tests applied before and after application proved that the irradiation source was leakproof. Dosimetry was performed by using 0.1-mm-thick thermoluminescent dosimeters (TLD-100) calibrated against a primary standard. A shielding transport and application container was designed to facilitate the handling of the source during use, while reducing exposure of the medical personnel. RESULTS: The designed source proves to be flexible for the insertion into proximal coronary vessels, and positioning at the site of stenosis. It provides an optimum protection of the animal and requires little radiation protection efforts on behalf of the medical staff. Dosimetric calculations and measurements showed that a centering of the source inside the vessel could be achieved with a maximum deviation of 50% between maximum and average dose levels. CONCLUSION: A yttrium-90 beta brachytherapy source was designed which provides high flexibility within proximal coronary arteries, ensures an adequate centering inside the artery, and provides irradiation conditions to the vessel wall of the experimental animal comparable to the application inside a human artery.

Angioplasty, Balloon, Coronary↗
PubMed2000

Intraarterial beta irradiation induces smooth muscle cell apoptosis and reduces medial cellularity in a hypercholesterolemic rabbit restenosis model.

PURPOSE: Ionizing radiation has been shown to be a powerful inhibitor of neointimal hyperplasia following arterial injury in several animal models of post-percutaneous transluminal coronary angioplasty (post-PTCA) restenosis. This was previously shown to be associated with a reduction in smooth muscle cell (SMC) mitotic activity. This study evaluated the effect of intraarterial beta irradiation on the arterial wall SMC density and apoptosis. METHODS AND MATERIALS: Twenty-five carotid and 7 iliac arteries of hypercholesterolemic New Zealand white rabbits were injured using the Baumgartner technique. The impact of an 18 Gy beta radiation dose administered after balloon injury was studied and compared to a nonirradiated injured control group. The medial SMC density as well as the percentage of apoptotic cells were determined at 8 days, 21 days, and 6 weeks after injury using an automated computer-based software. Apoptotic cells were identified using in situ end-labeling of fragmented DNA. RESULTS: The values for medial apoptosis in control vs. irradiated arteries were: 0.014 +/- 0.023 vs. 0.23 +/- 0.28%, p = NS, at 8 days; 0.012 +/- 0.018 vs. 0.07 +/- 0.07%, p = 0.05, at 21 days; and 0 +/- 0 vs. 0.16 +/- 0.11%, p = 0.03, at 6 weeks. The overall incidence of medial apoptotic cells at all time points was 0.01 +/- 0.017 vs. 0.13 +/- 0.14% in controls and irradiated arteries respectively, p = 0.004. Medial SMC density was significantly decreased in irradiated arteries in comparison with controls (p < 0.01 at all time-points). CONCLUSIONS: Intraarterial beta irradiation stimulates medial SMC apoptosis in balloon-injured arteries. This, together with a decrease in SMC mitotic activity, contributes to a decrease in the arterial wall cellularity.

Animals↗
PubMed2000

Beta versus gamma for catheter-based intravascular brachytherapy: dosimetric perspectives in the presence of metallic stents and calcified plaques.

PURPOSE: Both beta and gamma emitters are currently used in the catheter-based intravascular brachytherapy. The dosimetric effects due to the presence of metallic stents and calcified plaques have not been fully addressed. This work compares these effects for two most commonly used beta and gamma sources ( (90)Sr and (192)Ir). MATERIALS AND METHODS: An EGS4 Monte Carlo package was used to calculate dose in water for a (90)Sr (supplied by NOVOSTE) and an (192)Ir (Supplied by BEST) source, with or without the presence of a calcified plaque or a metallic stent. Plaques of different shape (shell and disk), size and density, and two types of stainless-steel stents (ring or mesh stent) were studied. The ring stent consists of identical rings stacked along the long axis of the sources. The gap between two rings is 0.3 mm. The mesh stents are made of identical square (0.1 x 0.1 or 0.2 x 0.2 mm(2)) holes separated from each other by stainless-steel wire. The cross section of wire for both ring and mesh stents is 0.1 x 0.1 mm(2). A dose perturbation factor (DPF), defined as the ratio of the doses with and without the presence of a plaque or a stent, was introduced to quantify the effects. A carefully chosen set of EGS4 transport parameters for the small geometry in question was used in the calculation. RESULTS: The radial and axial dose distributions calculated in water were found to agree with the published measurements to within 3%. The dose perturbations due to the presence of calcified plaques or metallic stents were found far more significant for the (90)Sr source than those for the (192)Ir source. Up to 30% dose reduction behind a plaque were observed for the (90)Sr source, while the dose reduction for the (192)Ir source was found to be negligible. The dose enhancement inside a plaque was as high as 10% for the beta source or 6% for the gamma source. In the presence of a stent, the DPF was in the range of 1.15-0.75 for the beta source, while it was almost equal to 1.0 for the gamma source. CONCLUSION: The dose perturbation due to the presence of a calcified plaque or a metallic stent is significant for the beta source. The dose reduction in the region beyond a plaque or a stent could be more than 20%. For the gamma source, the dose effect behind a plaque or a stent is practically negligible. These dosimetric differences between the beta and gamma sources in the presence of a calcified plaque or metallic stent should be considered in the dose prescription of intravascular brachytherapy.

Beta Particles↗
PubMed2003

Skin tumor promotion by Vitamin E in mice: amplification by ionizing radiation and Vitamin C.

We have shown previously that Vitamin E acts as a tumor promoter in 7,12-dimethylbenz(a)anthracene (DMBA) initiated mouse skin. We now show that high concentrations (80 micromol) of Vitamin E are required for promotion, and that 10-fold lower concentrations do not promote tumor formation. The same high concentration of the water-soluble anti-oxidant Vitamin C did not act as a tumor promoter, but did amplify the promoting effect of high, but not low, concentrations of Vitamin E. Oxidizing free radicals generated by beta-radiation exposure of the skin at the time of Vitamin E treatment also enhanced promotion by high (but not low) concentrations of Vitamin E. The results are consistent with a process whereby tumor promotion by the lipid-soluble Vitamin E occurs as a result of alpha-tocopherol acting as a free radical scavenger, with the formation and subsequent transfer of the alpha-tocopherol free radical center to the surrounding lipids, resulting in lipid oxidations.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2002

The effect of ionizing radiation on some derivatives of 1,4-dihydropyridine in the solid state.

The effect of gamma and beta radiation in doses between 10 and 100 kGy on physico-chemical properties of four derivatives of 1,4-dihydropyridine (nifedipine, nitrendipine, felodipine and nimodipine) in the solid state was analysed. A number of qualitative and quantitative methods such as UV, IR, TLC, GLC, DSC, EPR as well as organoleptic and gravimetric analysis were used to determine and analyse any changes resulting from irradiation. In order to determine the effectiveness of sterilization with ionizing radiation of doses from 10 to 25 kGy, various microbiological tests were used. It was established that only doses 10-20 kGy of both kinds of radiation ensure total sterilization without any degradation of physico-chemical properties of the compounds studied. For the doses 50-100 kGy a decrease in the content of the compounds, appearance of the products of their decomposition and changes in the melting point and IR spectra appeared. Felodipine (with chlorophenyl substituent) was found to be much more sensitive to ionising radiation than nifedipine, nitrendipine and nimodipine (all with nitrophenyl substituent).

Beta Particles↗
PubMed2000

The effects of intracoronary brachytherapy on the natural history of postangioplasty dissections.

OBJECTIVES: The aim of this study was to determine the natural history of postangioplasty intravascular ultrasound (IVUS)-detected dissections and to assess the influence of intracoronary beta-radiation on dissection resolution. BACKGROUND: Intracoronary radiotherapy is considered to impair exaggerated vessel healing. Conversely, excessive healing impairment may increase the risk of complications due to unhealed dissection. Alternatively, residual dissection may represent an innocent marker of adequate therapy. METHODS: Immediate postangioplasty and six-month follow-up IVUS studies of 94 patients in the IVUS substudy of the MultiVitamins and Probucol (MVP) trial and 26 nonstented patients in the Beta Energy Restenosis Trial (BERT) were analyzed for the presence or absence of dissection. RESULTS: Of the 28 patients with postangioplasty dissections in MVP, only one had evidence of residual dissection at six months (95% confidence interval [CI] for failure rate 0.2%; 20.2%). Conversely, 9 of 16 dissections had healed in BERT (95% CI for failure rate 30.6%; 79.2%) (p < 0.0002). Nevertheless, an index based on dissection arc and length demonstrated improvement in the irradiated patients. Irradiated patients with residual dissections showed significant increase in lumen area at six-months (5.10 +/- 0.98 to 7.11 +/- 2.61 mm2, p < 0.02) not noted when there was resolution of the dissection (6.03 +/- 2.38 to 6.36 +/- 3.33 mm2, p = NS). In both groups the external elastic membrane area was unchanged at follow-up. CONCLUSIONS: Resolution appears to be the natural history of IVUS-detected dissections in most cases. Significant resolution of dissection occurs following intracoronary beta-radiation as reflected in reduced dissection index at six-months in these patients, although significant impairment of vessel wall healing was noted.

Aortic Dissection↗
PubMed2001

Geographical miss during catheter-based intracoronary beta-radiation: incidence and implications in the BRIE study. Beta-Radiation In Europe.

OBJECTIVES: We sought to determine the incidence and causes of geographical miss (GM) and to evaluate its impact on edge restenosis after intracoronary beta-radiation therapy. BACKGROUND: Edge restenosis is a limitation of intracoronary beta-radiation therapy. Geographical miss is the situation in which the radiation source does not fully cover the injured segment and may lead to edge restenosis. METHODS: We analyzed 175 vessels treated according to the Beta-Radiation In Europe (BRIE) study protocol. The effective irradiated segment (EIRS) and both edges were studied with quantitative coronary angiography. The edges of the EIRS that were injured constituted the GM edges. Restenosis was defined as diameter stenosis >50% at follow-up. Geographical miss was determined by simultaneous electrocardiographic-matched, side-by-side projection of the source and balloons deflated at the injury site, in identical angiographic projections surrounded by contrast. RESULTS: Geographical miss affected 41.2% of the edges and increased edge restenosis significantly compared with non-GM edges (16.3% vs. 4.3%, respectively, p = 0.004). Restenosis was increased both in the proximal (p = 0.05) and distal (p = 0.02) GM edges compared with noninjured edges. Geographical miss associated with stent injury significantly increased edge restenosis (p = 0.006), whereas GM related to balloon injury did not significantly increase edge restenosis (p = 0.35). The restenosis in the EIRS was similar between vessels with and without GM (24.3% and 21.6%, respectively, p = 0.8). CONCLUSIONS: Geographical miss is strongly associated with restenosis at the edges of the EIRS. This effect is more prominent when caused by stenting. Geographical miss does not increase restenosis in the EIRS.

Adult↗
PubMed2002

Geographical miss during intracoronary irradiation: impact on restenosis and determination of required safety margin length.

OBJECTIVE: The goal of this study was to evaluate the incidence and effects of underdosage of injured segments during intracoronary irradiation and to define the minimal length of safety margin required to avoid mismatched source placement. BACKGROUND: Underdosage of injured segments due to misplacement of active source has been suggested as the underlying mechanism for the occurrence of edge restenosis. METHODS: Baseline angiograms of 112 vessels in 109 patients with in-stent restenosis undergoing coronary reintervention followed by intracoronary irradiation ((192)Ir: Checkmate, Cordis, Miami, Florida; (32)P: Gallileo, Guidant, Houston, Texas; (90)Sr/Y: Beta-Cath, Novoste, Norcross, Georgia) were analyzed. The distances between the outermost injury and outermost end of "reference isodose length" (RIL), defined as a segment with >/=90% of reference dose at 1 mm vessel wall depth, were measured. "Safety margin" was defined as the distance between the outermost injury and outermost end of the RIL, "geographical miss" (GM) as a complete injured segment not being covered by the RIL, and "restenosis" as the percent diameter stenosis >50%. RESULTS: Baseline angiographic analysis was performed for 224 edges in 112 vessels. Geographical miss was found in 46 (20.6%) edges. The incidence of target lesion restenosis within the 78 vessels with available follow-up was 43.3% for patients with GM versus 14.9% for patients with no GM (p = 0.005). Analysis of various injured segments exposed highest restenosis rates in injured segments with negligible irradiation (27.8%) in comparison with injured segments with dose fall-off (16.7%) or injured segments with full-dose irradiation (7.7%) (p = 0.006). Receiver operating curve analysis revealed a safety margin of 10 mm required per vessel (i.e., 5-mm safety margin/edge) to achieve 95% specificity of GM. CONCLUSIONS: Geographical miss is associated with a higher incidence of restenosis at the corresponding edges. Restenosis was more pronounced in injured segments with negligible irradiation than in injured segments at the dose fall-off zones. We recommend a safety margin of 10 mm per vessel to minimize GM.

Beta Particles↗
PubMed2003

Intravascular brachytherapy for native coronary ostial in-stent restenotic lesions.

OBJECTIVES: We analyzed the effects of vascular brachytherapy (VBT) on ostial in-stent restenosis (ISR). BACKGROUND: In-stent restenosis has a high recurrence rate after percutaneous reintervention. The recurrence rate of ostial ISR lesions and the impact of VBT remain unknown. METHODS: We evaluated 133 patients with native coronary ostial ISR from a pooled database of 990 patients enrolled in randomized VBT trials. Independent quantitative angiography was performed at baseline and follow-up in 45 gamma, 27 beta, and 61 placebo patients. RESULTS: Binary restenosis was significantly higher in placebo than radiated patients (75.4% vs. 17.8% in gamma vs. 22.2% in beta, p < 0.0001). The treatment effect of both gamma (odds ratio [OR] 0.06; 95% confidence interval [CI] 0.02 to 0.17) and beta VBT (OR 0.10; 95% CI 0.03 to 0.31) was maintained after controlling for differences in baseline lesion length. Proximal and distal radiation edge restenosis rates were similar among the groups. Vascular brachytherapy of true aorto-ostial lesions (n = 34) was similarly beneficial: restenosis rates of placebo versus gamma or beta patients of 83.3% versus 6.7% versus 28.6%, p = 0.0002. CONCLUSIONS: Conventional treatment of ostial ISR is associated with a recurrence rate of over 75%. Vascular brachytherapy with either gamma or beta sources results in significant and similar reductions in restenosis compared with placebo. Similar benefits after VBT prevail in true aorto-ostial lesions.

Aorta↗
PubMed1986

Pulse radiolytic study of alpha-tocopherol radical mechanisms in ethanolic solution.

Pulse radiolytic studies of alpha-tocopherol (alpha TH) oxidation-reduction processes were carried out with low doses (5 Gy) of high-energy electrons in O2-, N2-, and air-saturated ethanolic solutions. Depending on the concentration of oxygen in solution, two different radicals, A . and B ., were observed. The first, A ., was obtained under N2 and results from alpha TH reaction with solvated electron (k alpha TH + e-solv = 3.4 X 10(8) mol-1 liter s-1) and with H3C-CH-OH, (R.) (k alpha TH + R. = 5 X 10(5) mol-1 liter s-1). B., observed under O2, is produced by alpha TH reaction with RO2 . peroxyl radicals (k alpha TH + RO2 . = 9.5 X 10(4) mol-1 liter s-1).

Air↗
PubMedDate not supplied

Postnatal growth, neurobehavioral and neurophysiologic changes of prenatal low-dose beta-radiation from tritiated water in mice.

Pregnant adult C57BL/6J mice were randomly assigned to four groups: one sham and three irradiated groups that were exposed to -irradiation from tritiated water (HTO) by a single intraperitoneal injection on Day 12.5 of gestation. The offspring received cumulative doses of 0.036, 0.071, and 0.213 Gy, respectively. The litters were observed for postnatal growth (body weight, brain weight), the development of four physiologic milestones (pinna detachment, eye opening, testes decent, vaginal opening), the acquisition age of several reflexes (cliff avoidance, air righting) and sensory functions (auditory startle, thermal reflex), movement and coordination functions and activity (pivoting, foot splay, continuous corridor activity), learning and memory performance (shock avoidance, conditioning reflex), and the density of CA1-CA4 hippocampal pyramidal neurons. Modest but significant dose-dependent neuronal death and functional impairment were seen in both 0.071 and 0.213 Gy groups. In conclusion, even prenatal low-dose beta-radiation may impair murine central nervous system (CNS) development suggesting the potential importance of minimizing environmental exposure during human pregnancy.

Animals↗
PubMed1995

Mandibular reconstruction by secondary reimplantation of resected segments: a preliminary report.

This paper presents a new method of reconstructing the mandible after ablative surgery for cancer. This method uses autogenous grafts consisting of the respected part of the mandible, which is hollowed out, defatted in chloroform/methanol, sterilized with ethylene oxide, irradiated with beta-radiation (dose 25 kGy), and stored for 7-10 months. At reimplantation, they were filled with compressed, autogenous, particulate cancellous bone. All grafts took, and four of six host-graft junctions healed.

Aged↗
PubMed2001

A simplified method for determination of radioactive iron in whole-blood samples.

For studies on iron absorption in man radioisotopes represent an easy and simple tool However, measurement of the orbital electron emitting radioiron, 55Fe, in blood is difficult and insufficiently described in the literature. The present study describes a relatively simple method for simultaneous determination of 55Fe and 59Fe in blood, using a dry-ashing procedure and recrystallization of the remaining iron. The detection limit of the method permits measurements of 0.1 Bq/ml blood thus allowing detection of less than 1% absorption from a 40 kBq dose, which is ethically acceptable in humans. The overall recovery of radioiron from blood is more than 90%, and the coefficient of variation, as judged by the variation in the ratio 55Fe/59Fe is in the order of 4%. Combined with whole-body counting of 59Fe and direct gamma-counting of 59Fe on blood samples, this method represents a sensitive method for studying the intestinal absorption of 55Fe and 59Fe in man and at the same time allows estimation of the amount of radioiron located in the vascular compartment.

Beta Particles↗
PubMed1992

Polysaccharide storage myopathy associated with recurrent exertional rhabdomyolysis in horses.

A polysaccharide storage myopathy is described in nine Quarterhorses, Quarterhorse crossbreds, American Paints and Appaloosa horses which had a history of recurrent exertional rhabdomyolysis. Muscle biopsies were characterized by high muscle glycogen concentrations with up to 5% of type 2 muscle fibers containing inclusions which stained positively with the periodic acid Schiff (PAS) stain. The inclusions were classified as an acid mucopolysaccharide, based on their histochemical staining characteristics. Ultrastructural studies revealed that the inclusions were composed of beta glycogen particles interspersed among arrays of filamentous material. In addition, many type 2 fibers contained multiple subsarcolemmal vacuoles. These vacuoles stained lightly with eosin and did not stain positively with PAS. Centrofascicular atrophy and necrosis of scattered type 2 fibers were present in biopsies from some horses. No glyco(geno)lytic enzyme deficiencies were identified using a biochemical screening test for anaerobic glycolysis. Attempts to measure branching enzyme activities in both affected and control samples were unsuccessful, employing methods developed for human muscle. The polysaccharide accumulation in these horses may represent a hereto yet undefined metabolic disorder of skeletal muscle.

Animals↗