Sterilizing elastomeric chains without losing mechanical properties. Is it possible?

OBJECTIVE: To investigate the effects of different sterilization/disinfection methods on the mechanical properties of orthodontic elastomeric chains. METHODS: Segments of elastomeric chains with 5 links each were sent for sterilization by cobalt 60 (Co60) (20 KGy) gamma ray technology. After the procedure, the elastomeric chains were contaminated with clinical samples of Streptococcus mutans. Subsequently, the elastomeric chains were submitted to sterilization/disinfection tests carried out by means of different methods, forming six study groups, as follows: Group 1 (control - without contamination), Group 2 (70°GL alcohol), Group 3 (autoclave), Group 4 (ultraviolet), Group 5 (peracetic acid) and Group 6 (glutaraldehyde). After sterilization/disinfection, the effectiveness of these methods, by Colony forming units per mL (CFU/mL), and the mechanical properties of the material were assessed. Student's t-test was used to assess the number of CFUs while ANOVA and Tukey's test were used to assess elastic strength. RESULTS: Ultraviolet treatment was not completely effective for sterilization. No loss of mechanical properties occurred with the use of the different sterilization methods (p > 0.05). CONCLUSION: Biological control of elastomeric chains does not affect their mechanical properties. .

OBJETIVO: verificar os efeitos de diferentes métodos de esterilização/desinfecção nas propriedades mecânicas de elásticos ortodônticos em cadeia. MÉTODOS: segmentos de elástico em cadeia com 5 elos cada foram enviados para esterilização em radiação gama com cobalto 60 (20 KGy). Após esterilização, esses foram contaminados com amostras clínicas de Streptococcus mutans. Passado esse período, foram submetidos aos testes de esterilização/desinfecção por diferentes métodos, formando seis grupos de estudo, assim denominados: Grupo 1 (controle - sem ter sido contaminado), Grupo 2 (álcool 70°GL), Grupo 3 (autoclave), Grupo 4 (ultravioleta), Grupo 5 (ácido peracético) e Grupo 6 (glutaraldeído). Após esterilização/desinfecção, avaliou-se a efetividade desses métodos, por meio de contagem de unidades formadoras de colônias por mL (UFC/mL), e as propriedades mecânicas desses materiais. Utilizou-se o teste t de Student para avaliar o número de UFC, além do ANOVA e, posteriormente, do teste de Tukey para avaliação da força. RESULTADOS: verificou-se que o ultravioleta não obteve eficácia total quanto à esterilização. E não ocorreu perda das propriedades mecânicas dos elásticos, com os diferentes métodos de esterilização utilizados (p > 0,05). CONCLUSÃO: o controle biológico de elásticos em cadeia não interfere nas suas propriedades mecânicas. .

Effects of radiation and alpha-tocopherol on saliva flow rate, amylase activity, total protein and electrolyte levels in oral cavity cancer.

OBJECTIVE: The objective of the present study was to evaluate early and late effects of radiation and a-tocopherol on the secretion rate of saliva and on selected saliva salivary parameters in oral cavity cancer patients. PATIENTS & METHODS: Eighty-nine histologically confirmed oral cavity cancer patients (OCC) were enrolled in the study. Resting whole saliva was collected before, during and at the end of the radiation therapy (RT) and simultaneous supplementation with alpha - tocopherol to the radiation treated patients (RT + AT). RESULTS: Salivary flow rate, pH, amylase activity, total protein, sodium and potassium were analyzed. Increased pH, potassium and decreased flow rate, amylase activity, protein content and sodium were observed in 6 weeks of radiation treated patients when compared to OCC patients. A significant improvement of those parameters was observed on alpha - tocopherol supplementation in RT + AT patients. CONCLUSION: Supplementation with alpha - tocopherol improves the salivary flow rate thereby, maintains salivary parameters.

Radiation dose to contralateral breast during treatment of breast malignancy by radiotherapy.

AIMS: External beam radiotherapy is being used regularly to treat the breast malignancy postoperatively. The contribution of collimator leakage and scatter radiation dose to contralateral breast is of concern because of high radio sensitivity of breast tissue for carcinogenesis. This becomes more important when the treated cancer breast patient is younger than 45 years and therefore the contralateral breast must be treated as organ at risk. Quantification of contralateral dose during primary breast irradiation is helpful to estimate the risk of radiation induced secondary breast malignancy. MATERIALS AND METHODS: In present study contralateral breast dose was measured in 30 cancer breast patients undergoing external beam therapy by Co-60 teletherapy machine. Postoperative radiotherapy was delivered by medial and lateral tangential fields on alternate days in addition to supraclavicle field daily with 200 cGy/F to a total dose of 5000 cGy in 25 fractions. CaSO4: Dy thermoluminescence dosimeter discs were employed for these measurements. Three TLD discs were put on the surface of skin of contralateral breast, one at the level of nipple and two at 3 cms away from nipple on both side along the midline for each field. At the end treatment of each filed, TLD discs were removed and measured for dose after 24 h on Thelmador-6000 TLD reader. RESULTS: The dose at the contralateral breast nipple was to be 152.5 to 254.75 cGy for total primary breast dose of 5000 cGy in 25 equal fractions which amounted to 3.05-6.05% of total dose to diseased breast. Further it was observed that the maximum contribution of contralateral breast dose was due to medical tangential half blocked field. CONCLUSION: CaSO4; Dy thermoluminescence dosimetry is quite easy, accurate and convenient method to measure the contralateral breast dose.

Single institutional retrospective analysis: treatment of choroidal melanomas with cobalt-60 brachytherapy

Purpose: To evaluate the autcome pf patients with choroidal melanoma treated with conservative therapy with brachytherapy (episcleral Co-60 plaque therapy) at the "Hospital do Cancer"São Paulo, Brazil. Methods: We evaluated 102 patients consecutively treated from January, 1999 to June, 1999. Median age, maximum tumor base diameter and apex size were 55.5 years, 9.75 and 5mm, respectively. Dose s at the base of the tumor, including 1 mm of sclera, ranged from 157 to 487 Gy (median 284.5 Gy) and to the apex from 37 to 220 Gy (median 106 Gy). Results: The crude eye preservation rate with conservative therapy alone was 78.5 percent. Five-year overall actuarial survival rate was 92.2 percent and eye conservation rate was 78 percent. Side effects were mostly and uncomplicated retinopathy in 39/102 patients (38.2 percent); macular degeneration or scarring led to poor central vision in 31/102 patients (30.3) of cases. Conclusion: Our experience with cobalt-60 plaque brachytherapy achieved a satisfatory rate of local tumor control, despite the oversized base diameters of theated tumors.

Tumor regression dynamics with external radiotherapy in cancer cervix and its implications.

BACKGROUND: To study the external radiotherapy (EXTRT) regression patterns in cancer of the cervix. AIMS: Evaluate EXTRT tumor regression doses (TRD) for 50% (TRD50), 80% response (TRD80), normalized dose response gradient (g50) and slope (slope50) with clinical outcome. SETTINGS AND DESIGN: Patients, treated solely with radiotherapy and enrolled for other prospective studies having weekly tumor regressions recorded were considered. MATERIAL AND METHODS: Seventy-seven patients received 50Gy of EXTRT at 2 Gy/fraction followed by 18Gy of high-dose rate intracavitary brachytherapy at 6 Gy/fraction. Loco-regional regressions were assessed clinically at weekly intervals during EXTRT to generate EXTRT dose-response curves. STATISTICAL ANALYSIS USED: Student's t test, logistic regression, Kaplan Meier and Cox's proportional hazard model. Scatter plots were fitted using cubic fit. RESULTS: Age (P=0.052) and absence or presence of gross residual tumor (AGRT and PGRT respectively) following EXTRT (P<0.001) were the only determinants for complete response (CR) at 1 month following completion of radiotherapy. EXTRT tumor regression sigmoid curves obtained for various patient characteristics differed only for those with AGRT and PGRT with differences in TRD50, (P<0.001); TRD80 (P<0.001) and slope50 (P=0.001). Response status to EXTRT was a prognosticator for loco-regional disease free survival (LDFS) (AGRT vs. PGRT; P=0.046). On multivariate analysis, both TRD50 and TRD80 emerged as significant predictors for tumor status at end of EXTRT while TRD80 was the sole determinant of LDFS. CONCLUSION: Extent of tumor regression to EXTRT is an important predictor for treatment outcome in cancer cervix as evident from TRD50 and TRD80 values of EXTRT tumor regression curves.

Respuesta completa al tratamiento en un caso de seminoma del mediastino / Complete response to treatment in a medisastinal seminoma

Se reportó el caso de un paciente con diagnóstico de seminoma del mediastino, en el Hospital Provincial Oncológico "María Curie" donde se le aplicó un esquema de tratamiento de poliquimioterapia con cisplatino, adriamicina, vincristina y bleomicín, con posterioridad recibió tratamiento radiante externo con Co 60 y se obtuvo una respuesta favorable y desaparición de todos los síntomas.

Estudio de la radiación dispersa en implante de titanio, en cobaltoterapia / Backscatter radiation at bone-titanium implants in radiotherapy procedures

El conocimiento de la contribución de la radiación dispersa en pacientes que reciben terapia de radiaciones y que poseen implantes metálicos en la zona irradiada, resulta importante a fin de realizar un adecuado tratamiento, y evitar, en ciertos casos, posibles rechazos. Se simuló la incidencia de un haz de rayos gama generados por una fuente puntual de Co-60, en un fantoma de agua conteniendo en un caso una placa de titanio de 4mm de espesor ubicada a una profundidad de 3 cm, y en otro caso un marco consistente en dos barras del mismo material, de 4mm de radio. La simulación se realizó mediante el Código EGS4, para campos de 4 x 4 cm y 6 x 6 cm, a fin de reducir los tiempos de cálculo y sin pérdida de generalidad. En el caso de la placa, se observó un aumento de dosis en la cara frontal de aproximadamente un 9 por ciento, así como una disminución en la cara posterior de un 13 por ciento, para un número de trayectorias del orden de 10. El efecto de la radiación dispersa observado se extiende aproximadamente hasta 2 mm de las interfaces. Mas allá de estos, la mayor atenuación introducida por los implantes se ve parcialmente compensada por la radiación secundaria proveniente de la zona metálica, la cual se traduce en un campo gama de baja energía que decae multiexponecialmente, y que determina una reducción neta de dosis asintótica con el valor esperado por atenuación. En el caso de las barras metálicas, se obtuvo el perfil de dosis correspondiente, observándose una reducción máxima de un 12 por ciento detrás de las barras

Adjuvant therapy in invasive thymoma: an audit of cases treated over an 8 year period.

Invasive thymomas comprise 0.1%-0.2% of all malignancies in India. This report is an audit of 11 cases (10 males and 1 female) at a mean age of 36.6 years (range 25-52 years) of invasive thymoma accrued over an eight year period treated by combined modality treatment. Nine of these presented with myaesthenia gravis. All patients underwent initial surgery (3 partial and 8 total resections) and postoperative radiotherapy. Two of the three partially resected patients received one course of chemotherapy prior to radiotherapy consisting of cyclophosphamide, vincristine, procarbazine and prednisolone. At a median follow up of 28 months (range 2-87) there have been no local relapses, one distant metastasis and one death due to uncontrolled myaesthenia. The treatment strategies with invasive thymomas would depend upon the extent of resection. Postoperative radiotherapy appears to be indicated in all cases, however the role of chemotherapy may be limited to those with partial resection.

Epidermoid carcinoma of the hand: report of a case

The case of a 71 year old man who presented with an advanced epidermoid carcinoma of the dorsum of the hand, is reported. The patient was treated with radiotherapy as an alternative to amputation. Irradiation consisted of a combination of Co-60 photons and 6 Mev electrons. The cosmetic and functional results were excellent and the patient has been free of hand tumor for two and one-half years

Role of radiotherapy in cavernous hemangioma liver.

OBJECTIVE: To study the effectiveness of local radiotherapy for controlling cavernous hemangioma of liver. METHODS: This is a retrospective analysis of four diagnosed cases of cavernous hemangiomas of the liver treated with radiotherapy. Hepatic irradiation was given in a tumor dose of 30 Gy in 15 fractions over 3 weeks period. RESULTS: Three of the four cases showed a complete clinical regression of the liver lesions over a period of 8-14 months, but in one case there was only 75% regression of the mass at 12 months of follow up. CONCLUSIONS: Localized radiotherapy is effective in the treatment of giant cavernous hemangiomas of the liver and a tumor dose of 30 Gy is optimum with minimal morbidity.

Cáncer de tiroides / Thyroides neoplasm

El presente trabajo refiere la experiencia de 112 casos de cáncer tiroideo estudiados, tratados y evaluados en el Servicio de Cirugía de Cabeza y Cuello del Hospital Nacional Guillermo Almenara Irigoyen, durante un período de 20 años, desde 1965 hasta 1985. En este estudio se analizan las diferentes variedades del cáncer de la tiroides, demostrando la alta incidencia del cáncer bien diferenciado tiroideo, llegando a más del 80 por ciento. Con menor frecuencia se presentó el cáncer indiferenciado o anaplásico, y más raramente aún el cáncer medular. En la etapa inicial de la enfermedad, Estadío I, se presenta poco más del 21 por ciento. En el Estadío II se presentó el 37.5 por ciento de los casos; igual frecuencia en el Estadío III. En etapa diseminada de la enfermedad, Estadío IV se presentó el 3.57 por ciento. El tratamiento principalmente realizado fue la cirugía, desde la lobectomía total ampliada al itsmo, hasta una tiroidectomía sub-total y total. Para las metástasis cervicales se realizaron las disecciones radiales del cuello, de tipo estandar y con la cobaltoterapia, así mismo a las neoplasias que infiltraban la tráquea y los músculos pre-tiroideos. Es importante señalar que en el cáncer tiroideo en Estadío I bien diferenciado tanto papilar como folicular, la curación y sobrevida a 5, 10, 15 y más años, llegó al 100 por ciento, solamente con el tratamiento quirúrgico.

Cancer del cuello uterino: tratamiento radiante y complicaciones / Cervix uteri cancer: radiation therapy and coomplications

Se estudiaron 114 pacientes con cancer de cuello uterino entre 1988 y 1991, los cuales fueron tratados en el servicio de Oncologia del Hospital Provincial Docente Clinicoquirurgico de Santa Clara mediante tratamiento radiante con cobalto-60 en forma de teleterapia y braquiterapia. El grupo mas afectado se encontro entre los 50-59 anos, la variedad histica mas frecuente correspondio al carcinoma epidermoide, y la etapa clinica mas comun fue la II. En la mayoria de los casos se aplicaron dosis de 2001 a 3000 cGy con teleterapia externa en los puntos A y B, previo a la braquiterapia; despues se completo los puntos B con teleterapia. La mayoria de los pacientes recibieron 80 Gy en el punto A y mas de 60 en el B. Las complicaciones inmediatas mas frecuentes fueron la proctitis y la enterocolitis, y entre las tardias, las fistulas y la estenosis vaginal

Melanoma de úvea: tratamento por placas radiativas episclerais primeira experiência brasileira / Uveal melanoma: episcleral plaque radiotherapy first brazilian experience

O artigo descreve a evolução de dez pacientes portadores de melanoma uveal tratados por placas de cobalto-60 episclerais, desde dezembro de 1988, no Hospital A. C. Camargo, da Fundação Antonio Prudente, São Paulo. O tamanho das lesões variou de quatro a 11mm em altura e 11 a 16mm na base. A dose de radiação aplicada variou de 8.000 a 10.000 cGy no ápice e de 24.000 a 39.000 cGy na base. Observou-se redução de altura da lesão em nove pacientes (90 porcento), em seis (60 porcento) a base reduziu concomitantemente e em 1 (10 porcento) não houve alteração do tamanho da lesão nos primeiros sete meses após terapia. Os pacientes foram acompanhados por um período mínimo de quatro e máximo de 27 meses. Os autores discutem as indicações, método e resultados deste tipo de terapia.

Cobaltoterapia en cáncer cutáneo / Cobalt theraphy in skin cancer

Se presenta la experiencia personal en 5 pacientes portadores de cáncer cutáneo con diagnóstico de Carcinoma basocelular, que fueron dsometidos a tratamiento radioterápico con Cobalto 60 utilizando filtros compensadores de cera "Bolus". Todos recibieron tratamiento completo y se les controló por espacio de 5 años

Studies on the use of cobalt-60 irradiation to control infectivity of Toxoplasma gondii cysts.

Mouse brains harboring the Chinese NT strain of Toxoplasma gondii cysts were homogenized with normal saline and irradiated with cobalt-60 gamma rays at various doses. The homogenate was introduced intraperitoneally into NIH mice or per os into kittens. Loss of infectivity was confirmed according to the following criteria: no cyst found in mouse brain impression smears on the 50th day after inoculation; no oocyst found in feces of kittens 3-15 days after inoculation; subinoculation in mice and a negative IHA test. All bioassays, parasitological examinations and serological tests in the control group gave positive results. Activity of radioactive source: 10 KCi; uniform dosage: 1238 rad/min; dose range of irradiation: 0.1-1.0 KGy. Minimal effective dose of gamma rays to control infectivity of T. gondii cysts was 0.55 KGy. Infectivity of bradyzoites irradiated with gamma rays at a dose of 0.45 KGy decreased by 10,000 times. Minimal effective dose of gamma rays to control infectivity of American ME-49 and Ts-2 strain, is slightly higher (0.6KGy) than that of NT strain. These studies present useful data for practical use of cobalt-60 to control infectivity of T. gondii in meat products.

Hyperfractionation in advanced head and neck cancer.

This preliminary study was undertaken to observe tumour response and normal tissue tolerance to hyperfractionation. This study showed encouraging locoregional control rate in advanced head and neck cancer. Responses T4 tumors are poor and are prone to recur. This indicates that probably greater dose is needed to control T4 disease. We used 7920 cGy for T4 and late T3 status tumour. This dose is well tolerated by patients. Control of T4 tumours may further be increased by increasing total dose, but in view of inadequate clear cut numerical data of tissue tolerance derived by L-Q = Linear Quadratic formula which is still under clinical trial, further increase in total dose cannot be overemphasized. Longer follow up is necessary to assess the long term control rate and late tissue reaction. There is a need of randomized controlled clinical trial to compare hyperfractionation and conventional fractionation. In next phase we are undertaking randomized study of twice daily, daily and weekly fractionation in advanced head and neck cancer.

Adenocarcinoma indiferenciado de trompa de falopio derecha. Reporte de un caso / Indiferenciated adenocarcinoma of the right fallopian tube. Report of a case

Es motivo de la presentación, comentar el caso de una paciente joven, que consultó por cuadro álgico pelviano intenso, de rápida evolución y masa palpable a ese nivel, compatible con origen anexial derecho, con diagnóstico de: "abdomen agudo quirúrgico" es llevada a laparatomía exploradora y resección completa de masa tumoral con la patología ya citada. Completó el tratamiento con Telecobaltoterapia, por compromiso sigmoideo, hasta 4,500 CGy en campo pelviano amplio, incluyendo cadenas lumboaórticas, más un esfuerzo pelviano de 600 RADS en campos anterior y posterior. Recibió poliquimioterapia con esquema CAP (Ciclosfosfamida 600 mg/m2, adriamicina 50 mg/m2 y DDP 75 mg/m2 en dos (2) días E.V. por seis (6) ciclos con mínima toxicidad, permaneciendo hasta la fecha, libre de enfernedad clínica, radiológica y patológicamente comprobada, por "second lool" negativo

Fuente lineal radiactiva en cancer cervicouterino / Radiactive lineal source in cervico uterine cancer

Se dan a conocer los beneficios de una fuente lineal radiactiva aplicada a 110 pacientes con carcinoma cervicouterino invasor, atendidas en el servicio de oncología del Hospital 20 de Noviembre de la Ciudad de México, en el lapso de 1981-1984. La fuente lineal se elaboraba para cada enferma colocando las cápsulas de sodio longitudinalmente dentro del aplicador intrauterino de plástico flexible, insertado en el centro de un cilindro vaginal de acrilico, otorgando dosis de 5,000 a 6,000 rads a puntos A de Manchester; asimismo, se empleó telecobalto a la pelvis, dosis de 4,000 a 5,000 rads. La supervivencia obtenida a 5 años de control fue: 86.66% en la etapa clínica I-B, 75% en la II-A, 70.27% en la II-B y 42% en la etapa III-B, consignando una subrevida superior en las últimas tres etapas de un 7 a 8% que cuando utilizamos radio intrauterino y en colpostatos. Las conclusiones son: aplicación intrauterina de la fuente lineal en forma sencilla, bajo costo en la producción de cilindros vaginales y aplicadores intrauterinos, su fácil manufactura y mejores resultados de curabilidad