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The carbonate leaching of scandium from the landfilled bauxite residue (red mud) of the Bogoslovsky Aluminum Plant (Russia) and samples of red mud (RM) after alkaline pretreatment has been investigated. The results of kinetic studies allowing to compare and evaluate the effectiveness of different conditions and intensification factors in the process of scandium leaching from RM in carbonate/bicarbonate media are presented. It was determined that for 2.0 mol L-1 Na2CO3 leaching solution ultrasonic treatment under gas (CO2) carbonation conditions in the pH range of 9.5-10.0 allows reducing the scandium leaching time by two times and reaching 40-45% scandium extraction. Leaching of RM in carbonate/bicarbonate media is accompanied by secondary processes (adsorption, hydrolysis, and coprecipitation) leading to a decrease in scandium extraction. The obtained results allow improving understanding of scandium chemical behavior in complex aqueous carbonate/bicarbonate systems and can be used for the optimization of the alternative carbonate process for scandium extraction from RM.
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OBJECTIVE The use of Gamma Knife radiosurgery (GKRS) as monotherapy in the treatment of uveal melanoma (UM) allows clinicians to achieve high local tumor control with low recurrence but does not prevent secondary enucleation due to glaucoma in cases of large tumors. The authors analyzed indications for tumor endoresection (ER), the time interval between irradiation and surgery, and the features and results of performing ER for UM after GKRS. METHODS Thirty-seven patients between 28 and 78 years of age (16 male and 11 female patients) with UM underwent GKRS with a dose of 70 to 80 Gy that was applied to the center of the tumor with complete immobilization of the eye during the procedure. Tumor resection with histological investigation was performed in 24 eyes (transscleral resection was performed in 3 eyes, and ER was performed in 21 eyes) at 3 to 97 days after GKRS, mainly during the first 2 or 3 weeks. As a rule, ER (21 eyes) was performed to treat large, centrally localized, or equatorial UMs with exudative macula-on retinal detachment that reduced vision. The average tumor height was 8.9 mm, and the average width was 13.7 mm at the base. ER for UM included phacoemulsification, microinvasive vitrectomy with transretinal tumor resection, laser photocoagulation, and application of a temporary silicone oil tamponade. Seven patients received intraocular injections of inhibitors of angiogenesis for the prevention and treatment of radiation neuroretinopathy. The follow-up period ranged from 8 to 41 months. RESULTS Preservation of the eyes without tumor recurrence was achieved in all 37 patients after GKRS (monotherapy and combined therapy). One patient died of liver metastases at 21 months after GKRS. In the ER group (21 eyes), drug-resistant glaucoma with low visual acuity appeared in 4 eyes (19%) with long-existing total exudative retinal detachment and delayed operations. Severe radiation neuroretinopathy with macular edema occurred in 4 of 21 cases (19%). Intraocular injections of inhibitors of angiogenesis significantly decreased retinal edema. Residual rhegmatogenous retinal detachment was revealed in 1 eye (4.8%). The conservation of the patient's primary vision or its improvement were observed in 11 eyes (52.4%). Useful vision more than 0.1 was achieved in 12 cases (57%), and more than 0.3 was achieved in 8 cases (38%). CONCLUSIONS As a result of this research, ER for UM after GKRS proved to be an effective method of combined eye-conserving treatment for large centrally localized or equatorial tumors at high risk of the emergence and development of toxic tumor syndrome. Perfect eye immobilization, timely ER, and multiple intraocular injections of inhibitors of angiogenesis saved not only the eye in all cases, but also useful vision in many cases. Close cooperation among radiosurgeons, ophthalmologists, and vitreoretinal surgeons is the key to effective treatment.
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Melanoma/patología , Melanoma/radioterapia , Radiocirugia , Neoplasias de la Úvea/patología , Neoplasias de la Úvea/radioterapia , Adulto , Anciano , Terapia Combinada , Femenino , Humanos , Masculino , Persona de Mediana Edad , Invasividad NeoplásicaRESUMEN
A number of intracranial tumors demonstrate some degree of enlargement after stereotactic radiosurgery (SRS). It necessitates differentiation of their regrowth and various treatment-induced effects. Introduction of low-dose standards for SRS of benign neoplasms significantly decreased the risk of the radiation-induced necrosis after -management of schwannomas and meningiomas. Although in such cases a transient increase of the mass volume within several months after irradiation is rather common, it usually followed by spontaneous shrinkage. Nevertheless, distinguishing tumor recurrence from radiation injury is often required in cases of malignant parenchymal brain neoplasms, such as metastases and gliomas. The diagnosis is frequently complicated by histopathological heterogeneity of the lesion with coexistent viable tumor and treatment-related changes. Several neuroimaging modalities, namely structural magnetic resonance imaging (MRI), diffusion-weighted imaging, diffusion tensor imaging, perfusion computed tomography (CT) and MRI, single-voxel and multivoxel proton magnetic resonance spectroscopy as well as single photon emission CT and positron emission tomography with various radioisotope tracers, may provide valuable diagnostic information. Each of these methods has advantages and limitations that may influence its usefulness and accuracy. Therefore, use of a multimodal radiological approach seems reasonable. Addition of functional and metabolic neuroimaging to regular structural MRI investigations during follow-up after SRS of parenchymal brain neoplasms may permit detailed evaluation of the treatment effects and early prediction of the response. If tissue sampling of irradiated intracranial lesions is required, it is preferably performed with the use of metabolic guidance. In conclusion, differentiation of tumor progression and radiation-induced effects after intracranial SRS is challenging. It should be based on a complex evaluation of the multiple clinical, radiosurgical, and radiological factors.
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Neoplasias Encefálicas/secundario , Neoplasias Encefálicas/cirugía , Traumatismos por Radiación/diagnóstico , Radiocirugia/efectos adversos , Progresión de la Enfermedad , Humanos , Procesamiento de Imagen Asistido por Computador , Recurrencia Local de Neoplasia/diagnóstico , Neuroimagen , Traumatismos por Radiación/etiología , Factores de Tiempo , Tomografía Computarizada de Emisión de Fotón ÚnicoRESUMEN
Outcome of urgent reoperation for major regional complication after removal of intracranial tumor was evaluated retrospectively in 100 consecutive patients treated since 1983. Urgent reoperation was performed from 3 to 240 hours (mean 74 hours) after primary surgery for 32 meningiomas, 23 pituitary adenomas, 22 gliomas, 13 vestibular schwannomas, and 10 other intracranial neoplasms. Mean Glasgow Coma Scale (GCS) score before reoperation was 8. Brain edema was the most frequent operative finding at reoperation (31 patients), followed by extradural hematoma (25) and brain ischemia (24). Removal of various types of intracranial hematomas was the most common surgical procedure at reoperation (47 cases). Final outcome was considered favorable in 54 patients, who were discharged without major neurological deficit, and unfavorable in 46, with severe disability or vegetative state in four and death in 42. Multivariate analysis showed statistically significant association with the outcome for histological type of the tumor (p < 0.0001), clinical state at admission (p < 0.001), GCS score before urgent reoperation (p = 0.001), time interval between primary surgery and urgent reoperation (p < 0.01), and patient age (p < 0.05). Therefore, the outcome after urgent reoperation due to major regional complications after removal of intracranial tumor is determined mainly by the clinical condition of the patient and characteristics of the tumor, and less influenced by the type of complication.
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Neoplasias Encefálicas/cirugía , Servicios Médicos de Urgencia/estadística & datos numéricos , Procedimientos Neuroquirúrgicos/efectos adversos , Procedimientos Neuroquirúrgicos/mortalidad , Complicaciones Posoperatorias/mortalidad , Adulto , Edema Encefálico/etiología , Edema Encefálico/fisiopatología , Edema Encefálico/cirugía , Isquemia Encefálica/etiología , Isquemia Encefálica/fisiopatología , Isquemia Encefálica/cirugía , Servicios Médicos de Urgencia/tendencias , Femenino , Hematoma Epidural Craneal/etiología , Hematoma Epidural Craneal/fisiopatología , Hematoma Epidural Craneal/cirugía , Humanos , Masculino , Persona de Mediana Edad , Monitoreo Fisiológico/normas , Cuidados Posoperatorios/normas , Complicaciones Posoperatorias/fisiopatología , Pronóstico , Reoperación/estadística & datos numéricos , Reoperación/tendencias , Estudios Retrospectivos , Factores de Tiempo , Resultado del TratamientoRESUMEN
A 21-year-old female was admitted with complaints of severe impairment of vision. The visual acuity was 0.02 in both eyes along with residual visual fields and central scotomas. Neuroimaging disclosed a chiasmatic-hypothalamic glioma. Surgery was performed with partial removal of the intrachiasmatic part of the intrinsic tumor. The histological diagnosis was fibrillary astrocytoma. Progressive recovery of vision began in the first week after surgery. Adjuvant treatment included one course of fractionated radiation therapy and six courses of chemotherapy. Complete recovery of visual acuity occurred after 10 months, and the visual fields were restored after an additional 6 months. Her vision has been stable during 2 years of follow up. The prognosis for recovery of vision after treatment of optic pathway gliomas mainly depends on the severity of visual loss at admission and is negatively influenced by intrinsic tumor growth, symmetrical extension, and involvement of the chiasm. Despite the presence of all these factors in the present case, multimodality management resulted in the complete recovery of visual functions. Surgery may be indicated in cases of intrinsic chiasmatic gliomas complicated by severe visual loss.