Potential radioprotective effect of AT1 receptor antagonists against morphological and ultrastructural changes in the testes induced by ionizing radiation / Potencial efecto radioprotector de antagonistas del receptor AT1 contra los daños morfológicos y ultraestructurales en los testículos inducido por la radiación ionizante

Radiotherapy is a source of human exposure to ionizing radiation. This pure energy causes deleterious effects on tissues, which result from oxidative stress, a phenomenon in which there is the participation of the Renin-Angiotensin System (RAS). The male genital organs are extremely radiosensitive and the action of radiation in the testes can significantly affect spermatogenesis. In search of potential radioprotective for male genital system, this study investigated whether the AT1 receptor antagonists minimize radiation-induced damage to reproductive tissues, by decreasing oxidative stress. Male Wistar rats were divided into six groups: 0 Gray (Gy) (control), 5 Gy (single dose in the scrotal area), telmisartan, losartan, 5Gy+telmisartan and 5Gy+losartan. The treatment started the day after irradiation with losartan 34 mg/kg (two times/day) and telmisartan 12 mg/kg (one time/day) during 60 days. For ultrastructural analysis, the testis fragments were fixed in 2 % glutaraldehyde and 4 % paraformaldehyde in 0.1 M phosphate buffer, pH 7.3. The material was postfixed for 2 h in 1 % osmium tetroxide. For collagen evaluation, the sections were stained with Picrosirius-red method. Serum testosterone was determined. The date showed the deleterious effects of gamma radiation on testicular ultrastructure. Rich accumulation of collagen fibers in the interstitium was observed in the irradiated groups, especially the irradiated and nontreated testes. No significant difference was detected in serum testosterone concentration among the studied experimental groups. Treatments with telmisartan and losartan influenced the onset of attenuation on ultrastructural damages arising from ionizing radiation. Although the data strongly suggest that AT1 receptor antagonists may promote radioprotection to the testes, further studies with a longer duration of treatment are required for these potentially positive effects to be maximized and, therefore, to better characterize radioprotection to reproductive parameters.

El tratamiento radioterápico es una fuente de exposición del ser humano a la radiación ionizante. Esta energía pura causa efectos deletéreos en los tejidos, debido al estrés oxidativo, fenómeno donde hay participación del Sistema Renina-Angiotensina. Los órganos genitales masculinos son extremadamente radiosensibles y la acción de la radiación en los testículos puede afectar significativamente la espermatogénesis. En la búsqueda de potenciales radioprotectores, este estudio ha investigado fármacos antagonistas del receptor AT1 que minimizan los daños radioinduzidos en los tejidos reproductivos, por medio de la disminución del estrés oxidativo. Ratones Wistar machos fueron distribuidos en seis grupos: grupo 0 Gray (Gy) (control), grupo 5 Gy (dosis única en el área escrotal), grupo telmisartán, grupo losartán, grupo 5Gy+telmisartán y grupo 5Gy+losartán. El tratamiento empezó en el día siguiente a la irradiación con losartán 34 mg/kg (2x/día) y telmisartán 12 mg/kg (1x/día), durante 60 días. Para el análisis ultraestructural, los testículos se fijaron en glutaraldehido (2 %) y paraformaldehido (4 %) con tampón de fosfato 0,1 M, pH 7,3. El material fue post-fijado en tetróxido de osmio (1 %). Para evaluar el colágeno fue utilizado el método Picrosirius Red. Fue determinada la concentración sérica de testosterona. Los datos mostraron los efectos deletéreos de los rayos gamma sobre la ultraestructura testicular. Fue observada una rica deposición de colágeno en el intersticio en los grupos irradiados, especialmente en el irradiado y no tratado. Entre los grupos, no se detectó ninguna diferencia significativa en la concentración sérica de testosterona. Los tratamientos con telmisartán y losartán influenciaron el comienzo de la atenuación de los cambios en la ultraestructura testicular de la radiación. A pesar de que los datos sugieren que los antagonistas del receptor AT1 pueden promover radioprotección a los testículos, estudios complementarios con una duración de tratamiento más extendida son necesarios para que los efectos potencialmente positivos sean maximizados y, por supuesto, puedan mejorar la caracterizacion de la radioprotección a los parámetros reproductivos.

Short- and long-term effects of zinc treatment on lacrimal gland histopathology and tear functions tests in radioiodine-administered rats / Efeitos de curto e longo prazo do tratamento com zinco na histopatologia da glândula lacrimal e funções lacrimais em ratos que receberam iodo radioativo

ABSTRACT Purpose: To investigate the short-term (1 week) and long-term (8 weeks) protective effects of zinc administration on radioiodine (RAI)-induced lacrimal gland damage of rats. Methods: A total of 40 rats were divided into two groups: an RAI group (n=20), which was administrated a single dose of 3 mCi of 131I and 1 mL physiologic saline for 7 days by gastric gavage, and a zinc group (n=20), which received a single dose of 3 mCi of 131I and 1 mL of physiologic saline containing zinc sulfate at a concentration of 10 mg/kg concentration for 7 days by gastric gavage. All rats underwent tear function tests before and 1 week after RAI administration. About 1 week after irradiation, half of the animals in each group were sacrificed and the extraorbital lacrimal glands were removed for histopathological examination. The remaining animals of the groups underwent the same procedures at 8 weeks after irradiation. Results: In the RAI and zinc groups, the mean tear production was 3.75 ± 1.55 and 3.65 ± 1.53 mm at baseline, 2.10 ± 1.07 and 3.30 ± 1.34 mm at week 1 (p=0.004), and 3.22 ± 1.48 and 3.50 ± 1.78 mm at week 8, respectively; further, the mean corneal fluorescein staining scores were 4.65 ± 2.16 and 4.80 ± 2.21 points at baseline, 7.85 ± 1.90 and 5.45 ± 2.06 points at week 1 (p=0.001), and 5.44 ± 2.13 and 4.90 ± 2.08 at week 8, respectively. The histopathological changes in rat lacrimal glands at weeks 1 and 8 were consistent with the tear function test results. Conclusions: Zinc treatment seems to be protective against RAI-induced lacrimal gland damage of rats, particularly in the acute period.

RESUMO Objetivo: Investigar se o tratamento com zinco tem efeito protetor, no curto prazo (1 semana) e longo prazo (8 semanas), sobre os danos induzidos na glândula lacrimal por iodo radiotativo (RAI) em ratos. Métodos: Quarenta ratos foram divididos em dois grupos. No grupo RAI (n=20) foi administrada uma única dose de 3 mCi 131I e 1 cc de solução salina fisiológica durante 7 dias, por gavagem gástrica. O grupo zinco (n=20) recebeu uma dose única de 3 mCi 131I e 1 cc de solução salina fisiológica contendo sulfato de zinco na concentração de 10 mg/kg durante 7 dias por gavagem gástrica. Os testes de função lacrimal foram realizadas para todos os animais antes e após uma semana da administração da RAI. Em seguida, após 1 semana da administração, metade dos animais de cada grupo foi sacrificada e as glândulas lacrimais extraorbitais foram removidas para exame histopatológico. Os animais remanescentes dos grupos foram submetidos aos mesmos procedimentos após 8 semanas a radiação. Resultados: As médias de produção lacrimal foram de 3,75 ± 1,55 e 3,65 ± 1,53 mm na linha de base, 2,10 ± 1,07 e 3,30 ± 1,34 mm na 1a semana (p=0,004), e 3,22 ± 1,48 e 3,50 ± 1,78 mm na 8a semana, para os grupos RAI e zinco, respectivamente. As pontuações médias de coloração fluoresceína foram 4,65 ± 2,16 e 4,80 ± 2,21 no início do estudo, 7,85 ± 1,90 e 5,45 ± 2,06 na primeira semana (p=0,001), 5,44 ± 2,13 e 4,90 ± 2,08 pontos na 8a semana, para os grupos RAI e zinco, respectivamente. As alterações histopatológicas das glândulas lacrimais em 1 e 8 semanas foram consistentes com os testes de função lacrimal resultados. Conclusões: O tratamento de zinco parece ser protetor sobre os danos glândula lacrimal induzidos por RAI em ratos, especialmente no período agudo.

Effects of L-Glutamine oral supplementation on prostate of irradiated rats

ABSTRACT Objectives To investigate the protective effect of L-Glutamine in animals undergone to ventral radiation when the target organ is not the prostate. Materials and Methods Wistar rats were divided into groups of 10 animals each: Controls (C), maintained under standard conditions and not exposed to radiation, Radiated group (R) undergone to abdominal radiation only and Radiated plus supplemented by L-glutamine group (R+G). The animals of group R+G were supplemented with L-glutamine at the beginning of the experiment until death in the 22nd day. The ventral prostate was dissected and processed for morphometrical analysis. The epithelial height, collagen density and acinar area were objectively assessed in histological sections. Results Epithelial height was significantly reduced in R group in comparison to C group (p= 0.005). However, there was no statistical difference between the C and R+G groups. Collagen surface density in the C and R groups were not statistically different, but a significant difference was observed when comparing groups R+G and R (p= 0.040). The R+G group values did not differ significantly from C group. The acinar prostate area of group R was similar to that of C (p= 0.971), but in R+G it was significantly reduced when compared with the C (p= 0.038) and R (p= 0.001) groups. Conclusions Pelvic radiation promotes structural modifications in ventral prostate of rats, which can be reduced by L-Glutamine.

Evaluation of a novel decorporation approach to prevent radioactivity uptake by using acidosis in experimental animals.

With an aim to devise a prophylactic and/or therapeutic approach for preventing internalization of radiothallium (201Tl), and more importantly by implication, its chemical analogue radiocesium (137Cs) during any nuclear emergency, different ex vivo and in vivo animal models were created to determine the role of pH in absorption of 201Tl across jejunum/muscle tissue and whole body retention of 201Tl respectively. Movement of Tl+ under simulated pH conditions proved that pH had direct influence on its absorption. Oral intake of acidified water or parenteral administration of lactic acid was able to reduce the body burden of 201Tl by up to 12 and 50% respectively. The results indicate that acidification of gut, within physiological range may be used as an option for decorporation/inhibition of incorporation of radiothallium and radiocesium, particularly in cases of mass casualty.

Analysis of the cytoprotective effect of amifostine on the irradiated inner ear of guinea pigs: an experimental study / Análise do efeito citoprotetor da amifostina na orelha interna irradiada de cobaias: estudo experimental

Radiation can cause damage to the inner ear, from a simple hearing loss all the way to profound deafness. Amifostine is a cytoprotective substance extensively used during radio-chemotherapy for malignant tumors. AIM: the objective of the present investigation was to establish the antioxidant and radioprotective effects of amifostine on the organ of Corti of albino guinea pigs irradiated in the head and neck region. MATERIALS AND METHODS: An experimental study conducted on four groups of guinea pigs were used; One group received only amifostine, one group was submitted to a single dose of 350 cGy and the other two were similarly irradiated but received amifostine doses of 100 or 200 mg/kg. All animals were slaughtered 30 days after the experiment, their bullae were removed and the damaged outer hair cells were counted. RESULT: The extent of injury was lower in the outer hair cells of the two groups treated with amifostine compared to the group that was only irradiated. There was no difference between the group treated with 100 and 200 mg/kg of amifostine. The group that received only amifostine had no cochlear damage. CONCLUSION: Amifostine is an effective cytoprotective substance in the Organ of Corti of irradiated guinea pigs.

A radiação pode causar lesão na orelha interna podendo provocar surdez sensório-neural e inclusive levar à anacusia. A amifostina é uma substância citoprotetora seletiva de tecidos sadios, amplamente utilizada durante a radio e quimioterapia de tumores malignos. OBJETIVO: O objetivo deste estudo experimental foi verificar se existe efeito antioxidante e radioprotetor da amifostina no órgão de Corti de cobaias albinas irradiadas em região de cabeça e pescoço. MATERIAL E MÉTODO: O estudo realizado envolveu quatro grupos de animais: um grupo foi submetido à irradiação em dose única de 350cGy. Dois grupos receberam a mesma dose de radiação, porém receberam doses de 100 e 200mg/kg de amifostina, 30 minutos antes da irradiação. Um grupo recebeu apenas amifostina, na dose de 200mg/Kg. Todas as cobaias foram sacrificadas 30 dias após o experimento e suas bulas retiradas para estudo em microscópio de varredura. RESULTADO: O grau de lesão das células ciliadas externas foi menor nos dois grupos que receberam a amifostina que no grupo apenas irradiado. Não foi encontrada diferença de proteção entre os grupos que receberam doses de 100 e 200mg/kg de amifostina. Não houve lesão no grupo que recebeu apenas amifostina. CONCLUSÃO: Amifostina mostrou ser um radioprotetor do órgão de Corti de cobaias albinas irradiadas.

Effect of melatonin and time of administration on irradiation-induced damage to rat testes

The effect of ionizing irradiation on testes and the protective effects of melatonin were investigated by immunohistochemical and electron microscopic methods. Eighty-two adult male Wistar rats were divided into 10 groups. The rats in the irradiated groups were exposed to a sublethal irradiation dose of 8 Gy, either to the total body or abdominopelvic region using a 60Co source at a focus of 80 cm away from the skin in the morning or evening together with vehicle (20% ethanol) or melatonin administered 24 h before (10 mg/kg), immediately before (20 mg/kg) and 24 h after irradiation (10 mg/kg), all ip. Caspace-3 immunoreactivity was increased in the irradiated group compared to control (P < 0.05). Melatonin-treated groups showed less apoptosis as indicated by a considerable decrease in caspace-3 immunoreactivity (P < 0.05). Electron microscopic examination showed that all spermatogenic cells, especially primary spermatocytes, displayed prominent degeneration in the groups submitted to total body and abdominopelvic irradiation. However, melatonin administration considerably inhibited these degenerative changes, especially in rats who received abdominopelvic irradiation. Total body and abdominopelvic irradiation induced identical apoptosis and testicular damage. Chronobiological assessment revealed that biologic rhythm does not alter the inductive effect of irradiation. These data indicate that melatonin protects against total body and abdominopelvic irradiation. Melatonin was more effective in the evening abdominopelvic irradiation and melatonin-treated group than in the total body irradiation and melatonin-treated group.

Reduced incidence and severity of acute radiation mucositis by WF10 (IMMUNOKINE) as adjunct to standard of cure in the management of head & neck cancer patients.

OBJECTIVE: To evaluate the role of WF10-immunotherapy in reducing oro-pharyngeal complications in head and neck cancer chemoradiotherapy. MATERIAL AND METHOD: Thirteen patients were enrolled and assigned either to WF10- (n = 6) or control group (n = 7). After completion of their initial (neoadjuvant) chemotherapy, patients received WF10 intravenous infusions at 0.5 mL/kg body weight/day for five consecutive days and repeated every 3 weeks, concomitantly to standard radiotherapy (6,600-7,500 cGy, 200 cGy/day). Control patients received radiotherapy alone. RESULTS: Patients in the WF10-group had a lower incidence of oro-pharyngeal complications grade > 2, including oral mucositis (1 vs. 5), dysphagia (2 vs. 7), oral pain (3 vs. 5), taste alteration (4 vs. 6) and weight loss (2 vs. 4). The statistical significances were achieved for the parameters of oral mucositis (p = 0. 048) and dysphagia (p = 0.009). CONCLUSION: WF10 appears to reduce severity of oro-pharyngeal complications associated with standard chemoradiotherapy for head and neck cancer.

Otoproteção da amifostina aos efeitos ototóxicos da cisplatina: estudo em cobaias albinas por emissões otoacústicas produtos de distorção e microscopia eletrônica de varredura

A Cisplatina é uma potente droga antineoplásica, largamente utilizada para o tratamento do câncer, tanto em adultos quanto em crianças. Dentre seus efeitos colaterais, a ototoxicidade se apresenta como um dos mais importantes e leva à perda auditiva irreversível, bilateral, para as altas freqüências (4KHz -8KHz). Estudos têm tentado identificar drogas que, associadas à cisplatina, possam atuar como otoprotetores. Sabe-se que o mecanismo da ototoxicidade pela cisplatina está relacionado a alterações nos mecanismos antioxidantes das células ciliadas, principalmente as células ciliadas externas da cóclea. A amifostina tem conhecida ação antioxidante, com conhecido efeito otoprotetor aos efeitos lesivos da radioterapia. OBJETIVO: Nossa proposta foi avaliar através de emissões otoacústicas, por produtos de distorção (EOAPD) e por microscopia eletrônica de varredura (MEV), a existência de possível efeito otoprotetor da amifostina no tratamento com cisplatina. FORMA DE ESTUDO: Experimental. MATERIAL E MÉTODO: O estudo foi realizado em cobaias albinas, que foram divididas em três grupos: Grupo 1: 6 animais -12 orelhas - cisplatina 8,0 mg/Kg/dia (via intraperitoneal) por três dias; Grupo 2: 6 animais - 12 orelhas - amifostina 100 mg/Kg/ dia (via intraperitoneal) e 90 minutos após, cisplatina 8,0 mg/Kg/dia (via intraperitoneal) por três dias; Grupo 3: 03 animais - 06 orelhas - amifostina 100 mg/Kg/dia (via intraperitoneal) por três dias. RESULTADO: Encontramos EOAPD presentes e células ciliadas externas presentes, sem lesão anatômica a MEV, nos grupos 2 e 3. Concluímos que a amifostina, por sua ação antioxidante, atua como otoprotetor a ototoxicidade pela cisplatina. No entanto, seu uso não é recomendável nos casos de tumores potencialmente curáveis, por não se saber exatamente a influência da cisplatina na eficácia da quimioterapia.

Amifostine and hematologic effects.

Amifostine is a protective agent of normal tissue from adverse effects of radiochemotherapy. It is the prodrug that is dephosphorylated by alkaline phosphatase on plasma membrane into the active form named WR-1065. More than 90 per cent of the drug is cleared from plasma in 6 minutes and the peak tissue concentration is 10-30 minutes after intravenous administration. Amifostine has the selective property to protect normal tissue but not cancer cells by mainly scavenging free radicals induced by radiation and chemocytotoxic agents. Both preclinical and clinical studies of this drug provide the significant protection of hematopoietic progentitors from a broad range of cytotoxic agents such as cyclophosphamide, cisplatin, vinblastine, carboplatin, mitomycin-C, fotemustine, doxorubicin, daunorubicin and radiation as well. Moreover, this drug can protect other normal organs or tissues including kidney, salivary gland, liver, heart, lung and small intestine. Amifostine is quite safe, the two major side effects are vomiting and hypotension, and the minor effects are flushing, sneezing, dizziness, chills, metallic taste etc. The drug was approved by the FDA of U.S.A. for use as a cytoprotectant in cyclophosphamide and cisplatin treatment for advanced ovarian cancer and non small cell lung cancer.

Modification of radiosensitivity of chlorpromazine with biological metal ions in Thiobacillus ferrooxidans.

Effect of chlorpromazine with biological metal ions, viz. calcium, magnesium, zink and copper was studied on T. ferrooxidans cell system. Chlorpromazine, calcium and magnesium alone could produce radioprotection. Maximum radioprotection was exhibited by chlorpromazine at lower concentration while copper and zink offered radiosensitization. However, combination of chlorpromazine with all biological metal ions exhibited radiosensitization. Dose modifying factor by chlorpromazine at lower concentration (0.025 mM) was 0.754 while in combination with Ca2+, Mg2+, Cu2+ and Zn2+ was 1.08, 1.25, 1.37 and 1.389 respectively. The possible interaction between chlorpromazine and biological metal ions is discussed at cellular membrane level.

The efficacy of chemically-stabilized chlorite-matrix (TCDO) in the management of late postradiation cystitis.

Carcinoma of the uterine cervix is the most common cancer of women in Thailand. The most frequent complication after pelvic radiation for uterine cancer is radiation cystitis. The management of severe late postradiation cystis is far from satisfactory. The objective of this study was to evaluate the efficacy of chemically-stabilized chlorite-matrix (TCDO) in patients with severe radiation cystitis. This study was conducted at the Department of Obstetrics and Gynecology, Ramathibodi Hospital and the Department of Radiology, Siriraj Hospital between September 1997 and September 1998. Twenty patients with grade 3 radiation cystitis after radiotherapy were enrolled into this study. TCDO was administered at a dose of 0.5 ml/kg body weight per day on 5 consecutive days as intravenous infusion over 4 hours. The response rate after the first cycle was 80 per cent with 30 per cent of the patients showing complete response. The follow-up time (13 patients) ranging from 1-9 months revealed no recurrent bleeding. There were no side effects from TCDO therapy. The result suggests good efficacy of TCDO in the treatment of postradiation cystitis.

WR2721 (amifostina) e radioproteçäo da medula óssea / WR2721 (amifostina) and bone marrow radioprotection

A medula óssea é bastante radiosensível e dependendo da intensidade, suas alteraçöes podem causar a morte de indivíduos expostos, pela Síndrome Aguda da Radiaçäo.Constitui-se também num tecido crítico para a interaçäo de drogas e radiaçäo, durante o tratamento de doenças malignas, às vezes, limitando tais procedimentos. No presente artigo säo abordadas as características do radioprotetor amifostina e seu papel na proteçäo da medula óssea irradiada.

Radioprotective efficacy of HT + AET in encapsulated form.

Entrapment of 5-hydroxyl-L-tryptophan (HT) in erythrocyte ghost prepared by hypotonic method and high voltage electric discharge method are nearly same. Release of HT with beta-aminoethylisothiuronium bromide hydrobromide (HT + AET) in in vitro system is rapid but only a portion of the entrapped amount is released. Release of HT + AET in serum marginally increases at 2 hr. Compared to release in in vitro medium the release in serum is less. Survival studies with Swiss albino mice indicates that compared to HT alone, the combination of HT + AET shows about 9 times percentage survival. The same combination in the encapsulated form show comparable percentage survival though the amount needed is 1/200th times compared to free form.

Radioprotective effect of leaf extract of Indian medicinal plant Ocimum sanctum.

Water or aqueous ethanol extract of O. sanctum was given ip, either as a single dose or multiple doses, before a whole-body exposure to 11 Gy(LD100/30) of 60Co gamma radiation in albino mice. The water extract was more effective and less toxic than the aqueous ethanol extract. An optimum ip dose of 50 mg/kg (< 1/100 LD50) of the water extract, at 10 mg/kg/day for 5 consecutive days, gave the maximum survival. Increasing the dose per treatment or the number of treatments did not increase protection. Intraperitoneal administration gave the best protection (70% survival). Other routes (im, iv and po) were less effective and produced 37-47% survival. The optimum dose (ip) gave a dose modifying factor of 1.28. Since the extract may contain a number of chemical compounds, it is not possible to attribute the observed protection to any particular compound at present.

Use of hydroxylamine in improving radio protection of a combination of 5-hydroxy L-tryptophan and a thiol compound (AET) in small mammals.

Radioprotective effectiveness has been evaluated by 30 day survival studies and protection to bone-marrow cells in mice after radiation exposure and this has been further established by 24 hr deoxycytidine excretion in urine of rats following 5 Gy whole body gamma irradiation and protection to superoxide dismutase enzyme in marrow cells and red blood corpuscles. Radioprotective effectiveness as well as the duration of radioprotection have been improved by the administration (ip) of hydroxylamine (20 mg/kg), a decarboxylase inhibitor, prior to the use of a combination of 5-hydroxy L-tryptophan (5-HTP, 70 mg/kg) and 2-aminoethylisothiuronium bromide hydrobromide (AET, 20 mg/kg) ip in small mammals before whole body gamma irradiation.

Protection to glycolysis by a combination of 5-hydroxy-L-tryptophan and 2-aminoethylisothiuronium bromide hydrobromide in lethally irradiated rats.

Rate of glycolysis in vivo at different time intervals following 8 Gy [LD100(30)] whole body gamma radiation (WBGR) was evaluated by estimating liver glycogen, blood sugar, serum lactic dehydrogenase (LDH) and blood lactic acid concentration in adult male Sprague Dawley rats. Within 1 hr of radiation exposure, a significant fall in liver glycogen was observed in rats fed food and water ad libitum. The glycogen content increased after 24 hr and had returned to control level on 7th day after radiation exposure. Blood sugar, serum LDH and blood lactate levels increased significantly as compared to non irradiated controls. Pretreatment with 5-hydroxy-L-tryptophan (5-HTP; 100 mg/kg) + 2-aminoethylisothiuronium bromide hydrobromide (AET; 20 mg/kg) ip 30 min before 8 Gy WBGR, modified these values and restored them to normal level on 7th day post-irradiation.