Validation of a paper chromatographic methodology as an alternative for determination of the radiochemical purity of Na18F.

UNLABELLED: The aim of the present work was to validate a paper chromatography system as an alternative way to determine the radiochemical purity of Na(18)F. METHODS: The evaluated parameters were specificity, limit of quantification, measurement interval, linearity, precision, accuracy, and robustness. RESULTS: The proposed method proved to be linear (P > 0.05; r(2) = 1.000), precise (relative SD, 8.6%), accurate (mean recovery, 95.9%; relative SD, 1.5%-1.8%), and robust under different conditions since no influence of the operative variables on the chromatographic performance was observed. CONCLUSION: This system can be used as a reliable alternative method to determine the radiochemical purity of Na(18)F samples that can be easily performed in PET radiopharmacies at low cost.

Radioactive treatment of a murine melanoma using a (32)P-patch.

OBJECTIVE: To evaluate the therapeutic effects of a (32)P-patch in the treatment of a murine melanoma. MATERIALS AND METHODS: Thirty male C57BL6 mice were divided into two groups: treated and control. Superficial tumors were induced in both groups by injecting B16F1 melanoma at about 10 cells/mouse subcutaneously. Tumors developed 10-15 days after transplantation and the (32)P-patch was applied on palpable tumors of the treated group. Tumor growth was followed up in both groups by measuring tumor size with a caliper. After the follow-up period, the animals were killed and tumor samples of the treated and control groups were collected for histological study by preparing paraffin sections stained with hematoxylin-eosin. RESULTS: The (32)P-patch showed the absence of radioactivity leakage in vitro and the homogeneous distribution of the radionuclide. The skin surface at the application site of the (32)P-patch appeared hairless, and erythema developed, but reversed to normal after a few days in the treated group. Control of tumor growth was achieved in the treated group compared with the control group, although complete remission did not occur. CONCLUSION: The (32)P-patch tested for the treatment of a murine melanoma model showed its efficacy, as tumor growth was retarded after application of the patch Nevertheless, adjustment of some therapeutic parameters and/or combining the patch with other treatment modalities may be necessary to achieve complete regression. The P-patch represents a powerful tool to individualize the treatment of melanoma.

Bioevaluation of 32P patch designed for the treatment of skin diseases.

OBJECTIVE: The objective of this study was to design and evaluate a 32P patch for the treatment of skin diseases. MATERIALS AND METHODS: The patch was prepared from chromic phosphate 32P and silicone. Bioelimination and biodistribution in healthy and treated animals, and the therapeutic efficacy of two treatment schemes (single dose and fractionated dose) in an animal model of skin cancer were studied. RESULTS: Based on the bioelimination and biodistribution studies, no leakage of 32P from the patch was observed. The treated tumors reduced their mean diameter compared to controls. The single-dose therapeutic scheme showed a higher number of complete and partial remissions compared to the fractionated scheme. These results were confirmed by histopathological analysis of the samples. CONCLUSION: The 32P patch was designed and produced according to specifications for the treatment of superficial lesions of the skin. Although the 32P patch is an open source, it behaves like a sealed one for use in brachytherapy treatments.

Quality control validation for exogenous natural surfactant labeled with 99mTc.

OBJECTIVE: Exogenous natural surfactant (ENS) labeled with 99mTc shows an elevated lung specificity allowing the acquisition of high-quality images for ventilation scintigraphy. METHODS: The methods for 99mTc-ENS quality control (physical properties, pH determination, radiochemical studies, and biologic studies) were evaluated and validated. RESULTS: The physical properties of the nonradioactive precursor and of the radiopharmaceutical were analyzed as general descriptors of the product. The pH of the radiopharmaceutical was determined by using pH test papers, a method described and validated in the United States Pharmacopeia. Chromatographic studies performed using the acetone/Whatman-1 paper system were validated as a method to evaluate the radiochemical purity of the 99mTc-ENS. Biodistribution studies on rats after intratracheal administration were validated as a method to estimate the radiopharmaceutical biodistribution in humans. CONCLUSION: The proposed method for 99mTc-ENS quality control studies and stability studies was evaluated and validated following international standards.

Effects of radiosynovectomy with p-32 colloid therapy in hemophilia and rheumatoid arthritis.

AIM: The aim of this study was to assess the effects of treatment with our locally produced P-32 colloidal suspension on knee synovitic inflammations of hemophilic and rheumatoid arthritis (RA) patients, as well as to compare results with chemical synovectomy or corticoid intra-articular injections and evaluate the cost-benefit ratio. MATERIALS AND METHODS: Thirty-six hemophilic male patients, 4-28 years of age and sent by the Hemophilic Foundation (Buenos Aires, Argentina), were enrolled for knee radiosynovectomy (RS) with P-32 colloid (26 patients), or the antibiotic rifampicin with the cooperation of orthopaedists (10 patients). Parents' informed consent was obtained. The following procedures were performed: routine blood tests, X-ray, ultrasound, a 3-phase bone scan, plus monthly methylene diphosphonate (MDP) controls. Patients were included in this study only if several knee episodes had occurred. Exclusion criteria included bone destruction and big Baker's cyst. Twelve RA patients were included, with similar selection criteria: 6 RA patients received P-32 therapy, and the other 6 patients intra-articular corticoids. Clinical, blind evaluation (state of joint involvement, pain, motility, requirements of antihemophilic factors, corticoids, or analgesics) was registered in follow-up charts. If required, joint aspiration was carried out. Intra-articular instillation of saline plus flushing was done before the needle was withdrawn. P- 32 Bremsstrahlung emission was used in the gamma camera for early and late imaging to confirm the absence of leakage. For intra-articular chemical injections therapy, 4 MBq of Tc-99m MAA (macroaggregates) was used. Immobilization and relative rest for 72 hours followed the procedures. RESULTS: There were neither local or systemic effects, nor leakage during P-32 treatment. Intra-articular rifampicin and corticoids procedures required frequent injections. Comparison of regions of interest (ROIs) in treated knees during soft-tissue scintigraphies in pre- and post-third MDP control showed knee improvement. The follow-up evaluation demonstrated an increase in joint motion, diminished volume, and less requirement and frequency of the use of antihemophilic factors (AHF) in 80% of the radiosynovectomies (21 of 26), thus lowering health costs. Five female RA patients (5 of 6) had decreased joint swelling and pains, resulting in increased joint motion. CONCLUSIONS: Radiosynovectomy in RA showed a 3-month pain palliative effect. One intra-articular knee radiosynoviorthesis in haemophilic patients provides a more than 3- month relief of symptoms after treatment with locally produced P-32 (11 patients). This turned out to be a safe, economic alternative procedure in emerging nations where the availability of AHF is difficult and expensive.

Braquiterapia de tumores sólidos: uso del fosfato crómico coloidal / Brachytherapy of solid tumors: use of chromic phosphate coloid

Con el propósito de evaluar la efectividad de una dosis única de [33P]-Fosfato Crómico (Phosphocol(TM)) para el tratamiento de tumores sólidos, se realizaron estudios de bioeliminación, biodistribución y acción terapéutica en ratas portadoreas de tumores experimentales químicamente inducidos. Los resultados demuestran que el porcentaje de eliminación total es de 29.76 + 9.60 por ciento, siendo la eliminación por vía fecal de 23.28 + 8.81 por ciento y la urinaria de 6.48 + 2.11 por ciento. Los estudios de biodistribución revelan que el 51.61 + 5.82 por ciento de la actividad inyectada se encuentra en el tumor, mientras que en órganos donde existen células reticuloendoteliales, se encontró que el porcentaje de actividad es de 13.09 + 5.15 por ciento en hígado y de 2.88 + 1.23 por ciento en pulmón. Por otra parte, los estudios de acción terapéutica demuestran que el porcentaje de regresión tumoral (P.R.T.) es de 61.0 por ciento para los tumores inyectados. Cabe destacar que 4 de los animales tratados mostraron perfiles de bioeliminación, en los cuales, la misma aumentó abruptamente en algún momento del estudio. Estos resultados demuestran que no es recomendable el uso de este tipo de coloides en el tratamiento de tumores sólidos con moderado grado de vascularización, debido a que puede existir movilización del mismo y en consecuencia iradiación de otros órganos no afectados al tratamiento.

Braquiterapia de tumores sólidos: uso del fosfato crómico coloidal / Brachytherapy of solid tumors: use of chromic phosphate coloid

Con el propósito de evaluar la efectividad de una dosis única de [33P]-Fosfato Crómico (Phosphocol(TM)) para el tratamiento de tumores sólidos, se realizaron estudios de bioeliminación, biodistribución y acción terapéutica en ratas portadoreas de tumores experimentales químicamente inducidos. Los resultados demuestran que el porcentaje de eliminación total es de 29.76 + 9.60 por ciento, siendo la eliminación por vía fecal de 23.28 + 8.81 por ciento y la urinaria de 6.48 + 2.11 por ciento. Los estudios de biodistribución revelan que el 51.61 + 5.82 por ciento de la actividad inyectada se encuentra en el tumor, mientras que en órganos donde existen células reticuloendoteliales, se encontró que el porcentaje de actividad es de 13.09 + 5.15 por ciento en hígado y de 2.88 + 1.23 por ciento en pulmón. Por otra parte, los estudios de acción terapéutica demuestran que el porcentaje de regresión tumoral (P.R.T.) es de 61.0 por ciento para los tumores inyectados. Cabe destacar que 4 de los animales tratados mostraron perfiles de bioeliminación, en los cuales, la misma aumentó abruptamente en algún momento del estudio. Estos resultados demuestran que no es recomendable el uso de este tipo de coloides en el tratamiento de tumores sólidos con moderado grado de vascularización, debido a que puede existir movilización del mismo y en consecuencia iradiación de otros órganos no afectados al tratamiento. (AU)