Research progress in biological effects of low-dose radiation / 中国辐射卫生

The biological effects of low-dose radiation (LDR) are still a research hotspot in the field of radiobiology. As research deepens on LDR-induced biological effects and the mechanisms, growing evidence shows that LDR produces distinct biological effects from high-dose radiation, which questions the linear non-threshold model. This article reviews LDR-induced bystander effect, hormesis, adaptive response, and hyper-radiosensitivity, as well as the mechanisms, in order to provide a reference for the transformation of basic research on LDR-related biological effects to clinical application.

Pterostilbeno Reduz o Estresse Oxidativo no Pulmão e no Ventrículo Direito Induzido por Infarto do Miocárdio Experimental / Pterostilbene Reduces Experimental Myocardial Infarction-Induced Oxidative Stress in Lung and Right Ventricle

Resumo Fundamento O pterostilbeno (PS), um composto polifenólico natural e antioxidante, surge como uma intervenção promissora para minimizar danos do infarto agudo do miocárdio (IAM). Objetivo Este estudo teve como objetivo avaliar o desempenho do PS na promoção da homeostase redox nos pulmões e no ventrículo direito (VD) de animais infartados. Métodos Ratos Wistar machos (60 dias de idade) foram randomizados em três grupos: SHAM, IAM (infarto) e IAM+PS (IAM + pterostilbeno). Sete dias após o procedimento de IAM, os ratos foram tratados com PS (100 mg/kg/dia) por gavagem por oito dias. Os animais foram depois sacrificados e os pulmões e VD foram coletados para análise do balanço redox (diferenças foram consideradas significativas quando p<0,05). Resultados Nossos resultados mostram que o IAM desencadeia a interrupção redox no VD e nos pulmões, o que pode contribuir para danos induzido pelo IAM nesses órgãos. Consistentemente, o PS mitigou o estresse oxidativo e restaurou as defesas antioxidantes (Glutationa - GSH nos pulmões: SHAM = 0,79 ± 0,07; IAM = 0,67 ± 0,05; IAM + PS = 0,86 ± 0,14; p<0,05), indicando seu papel protetor neste cenário. Conclusão Nosso trabalho evidencia o potencial do uso de PS como abordagem terapêutica adjuvante após IAM para proteção dos tecidos pulmonares e cardíacos direitos.

Abstract Background Pterostilbene (PS), a natural and antioxidant polyphenolic compound emerges as a promising intervention in improving the myocardial infarction (MI) damages. Objetives This study aimed to evaluate PS actions in promoting redox homeostasis in lungs and right ventricle (RV) of infarcted animals. Methods Male Wistar rats (60 day-old) were randomized into three groups: SHAM, MI (infarcted), and MI+PS (MI+pterostilbene). Seven days after MI procedure, rats were treated with PS (100 mg/kg/day) via gavage for eight days. Animals were euthanized and the lungs and RV were harvested for analyses of redox balance (Differences were considered significant when p<0.05). Results Our results show that MI triggers a redox disruption scenario in RV and lungs, which can contribute to MI-induced damage on these organs. Consistently, PS mitigated oxidative stress and restored antioxidant defenses (GSH in lungs: SHAM= 0.79±0.07; MI=0.67±0.05; MI+PS=0.86±0.14; p<0.05), indicating its protective role in this scenario. Conclusions Our work evidences the PS potential use as an adjuvant therapeutic approach after MI focusing on protecting pulmonary and right-sided heart tissues.

Presence of glyphosate can harm the germination of bean seeds treated with biostimulant / Presença de glifosato pode prejudicar a germinação de sementes de feijoeiro tratadas com bioestimulante

It is possible to cultivate common beans for a third harvest in one agricultural year due to varietal characteristics. For calendar adequacy, performing desiccation and planting often occur almost simultaneously. Germination performance of many plant species can improve with biostimulant use on seeds, however the interaction with herbicide residual molecules is unknown. The hypothesis is that seeds treated with a biostimulant in soil with glyphosate residues can eliminate the advantage of the biostimulant or increase the damage caused by the herbicide. The aim of this study was to evaluate the effect of different glyphosate reduce doses and the interaction with biostimulant on bean seed germination and vigor. The experiment was conducted using a completely randomized 2 x 5 factorial block designing factorial 2 x 5, corresponding to the presence and absence of biostimulant and five different doses of glyphosate reduce rates, with four repetitions. The conducted evaluations were first count germination, germination test, accelerated aging, cold test, root and shoot length, root and shoot dry matter and electrical conductivity. It can be concluded that the biostimulant treatment on bean seeds increased germination, seed vigor and early seedling growth, but glyphosate presence reduced those advantages, increasing electrical conductivity. However, the herbicide presence provided higher germination on the accelerated aging test.

Devido às características de variedades de feijoeiro comum, é possível seu cultivo como terceira safra em um ano agrícola. Para adequação ao calendário, a prática de dessecação e plantio muitas vezes ocorrem quase simultaneamente. A utilização de bioestimulantes em sementes pode aumentar o desempenho germinativo de diversas espécies de plantas, no entanto a sua interação com moléculas residuais de herbicidas é desconhecido. A hipótese é que o uso de sementes tratadas com bioestimulante em solos com resíduos de glifosato pode eliminar as vantagens do primeiro ou amentar os danos causados pelo herbicida. O objetivo do trabalho foi avaliar o efeito de subdoses de glifosato e bioestimulante em sementes de feijoeiro. O experimento foi realizado em blocos inteiramente casualizados em fatorial 2x5, correspondendo a ausência e presença de bioestimulante e cinco subdoses de glifosato, com quatro repetições. As avaliações foram primeira contagem de germinação, teste de germinação, envelhecimento acelerado, teste de frio, comprimento de parte aérea e de raiz, massa seca de parte aérea e de raiz e condutividade elétrica. Conclui-se que o tratamento de sementes de feijoeiro com bioestimulante eleva a germinação, o vigor de sementes e o crescimento inicial de plântulas, porém a presença de glifosato elimina essas vantagens, revelando maior condutividade elétrica. No entanto, a presença do herbicida proporciona maior germinação no teste de envelhecimento acelerado.

Mitochondrial Toxins and Healthy Lifestyle Meet at the Crossroad of Hormesis

Mitochondrial function is crucial for the maintenance of cellular homeostasis under physiological and stress conditions. Thus, chronic exposure to environmental chemicals that affect mitochondrial function can have harmful effects on humans. We argue that the concept of hormesis should be revisited to explain the non-linear responses to mitochondrial toxins at a low-dose range and develop practical methods to protect humans from the negative effects of mitochondrial toxins. Of the most concern to humans are lipophilic chemical mixtures and heavy metals, owing to their physical properties. Even though these chemicals tend to demonstrate no safe level in humans, a non-linear dose-response has been also observed. Stress response activation, i.e., hormesis, can explain this non-linearity. Recently, hormesis has reemerged as a unifying concept because diverse stressors can induce similar stress responses. Besides potentially harmful environmental chemicals, healthy lifestyle interventions such as exercise, calorie restriction (especially glucose), cognitive stimulation, and phytochemical intake also activate stress responses. This conceptual link can lead to the development of practical methods that counterbalance the harm of mitochondrial toxins. Unlike chemical hormesis with its safety issues, the activation of stress responses via lifestyle modification can be safely used to combat the negative effects of mitochondrial toxins.

Low-dose radiation and Alzheimer's disease: Neuronal effects and a potential modality for therapy? / 中华放射医学与防护杂志

Exposure to low-dose radiation (LDR,mostly less than 100 mGy) may reduce the vulnerability of exposed tissues to subsequent high-dose radiation (HDR)-induced damage,a phenomenon known as adaptive responses,which occurs via mechanisms including anti-inflammation and anti-oxidation.Alzheimer's disease (AD) is a type of dementia that causes problems with memory,thinking,and behavior.Using the available literature,this review will examine whether there is any effect of LDR on AD.The available evidence shows that although LDR can alter the expression of some genes related to AD such as Apbb1,Lrp1,and Il1α,these alterations do not cause AD-like syndromes in animals,suggesting that LDR may also simultaneously upregulate several protective mechanisms that prevent the eventual development of AD.Furthermore,LDR seems capable of improving the symptoms of AD,as evidenced by the experience of an 81-year-old female AD patient.This patient was diagnosed with AD more than 10 years ago and gradually progressed to advanced AD in 2015,despite routine treatment.The patient then received about 12 computed tomography scans (about 40 mGy each) up until Nov.2017,which significantly improved her quality of life and reduced several AD symptoms.The improvement in this patient's medical condition led to a few recent clinical trials investigating the effects of LDR on AD.To date,there is no efficient therapy available for AD,thus whether exposure to LDR at 100 mGy can provide a preventive or therapeutic effect for AD is an important issue.If LDR is a potential treatment for AD,as suggested by this reported case,this non-invasive approach would also bear the merit that it would be unlikely to cause a significant radiation health risk,as the LDR could be delivered locally to the head without any impact on other organs.

Hormetic Effects of Yttrium on Male Sprague-Dawley Rats / 生物医学与环境科学（英文）

To evaluate hormesis induced by Yttrium (Y) nitrate in male rats, Y was offered to F0 mother rats and F1 offspring at concentrations of 0, 20, 80, and 320 ppm daily from gestational day (GD) 0 through postnatal day 70 (PND 70). The F1 offspring were evaluated with respect to motor function, learning and memory, and histopathology. Administration of Y improved motor function in a dose dependent manner. In the 20 ppm group, body weight and spatial learning and memory were increased, while the latter was decreased in the 320 ppm group. Additionally, in the 20 ppm and 80 ppm, but not the 320 ppm groups, Y reduced the anogenital distance, which indicated an anti-androgen effect. These results suggest that Y follows a hormetic concentration-related trend with an inverted U-shape.

Aspirina en dosis ultrabajas y hormesis / Aspirin in ultra-low doses and hormesis

La relación entre hormesis y Homeopatía resulta hoy en día controvertida. Por un lado, sus primeros fundamentos fueron enunciados con el objeto de explicar los efectos de la Homeopatía. Por otro lado, la mayoría de los trabajos realizados que muestran efectos horméticos fueron realizados a concentraciones mucho mayores que las utilizadas en Homeopatía. El presente trabajo muestra varios puntos de contacto entre la Homeopatía y el concepto de hormesis, y muestra la relación que existe entre los trabajos realizados sobre los efectos de la aspirina 15CH y los distintos tipos de hormesis.

Hormesis of drugs for infectious diseases / 药学学报

Hormesis, a biphasic dose-response phenomenon characterized by low-dose stimulation and high-dose inhibition, is a common feature of medicines but neglected sometime. Understanding of hormesis is essential for drug discovery and clinical application. Assessing hormetic range needs a proper experiment design including the number of doses and dose spacing, especially in the low dose zone. This article provides the shapes of hormetic dose-response curves, underlying mechanisms and the significance of hormesis for drugs of infectious diseases to facilitate drugs development and clinical applications.

Caffeic acid improves cell viability and protects against DNA damage: involvement of reactive oxygen species and extracellular signal-regulated kinase

Hormesis is an adaptive response to a variety of oxidative stresses that renders cells resistant to harmful doses of stressing agents. Caffeic acid (CaA) is an important antioxidant that has protective effects against DNA damage caused by reactive oxygen species (ROS). However, whether CaA-induced protection is a hormetic effect remains unknown, as is the molecular mechanism that is involved. We found that a low concentration (10 μM) of CaA increased human liver L-02 cell viability, attenuated hydrogen peroxide (H2O2)-mediated decreases in cell viability, and decreased the extent of H2O2-induced DNA double-strand breaks (DSBs). In L-02 cells exposed to H2O2, CaA treatment reduced ROS levels, which might have played a protective role. CaA also activated the extracellular signal-regulated kinase (ERK) signal pathway in a time-dependent manner. Inhibition of ERK by its inhibitor U0126 or by its specific small interfering RNA (siRNA) blocked the CaA-induced improvement in cell viability and the protective effects against H2O2-mediated DNA damage. This study adds to the understanding of the antioxidant effects of CaA by identifying a novel molecular mechanism of enhanced cell viability and protection against DNA damage.

Resistance to heavy metal toxicity in organisms under chronic exposure.

The rate of changes of heavy metal ions concentrations in the organism or biological system will determine the choice of strategy of realization of heavy metal ions effect and, consequently, the biological effect itself. Which of the possible strategies will dominate, depend on the rate of changes of concentration of heavy metal ions in biological systems, functional activity of organism at the moment of metal action and on metals chemical properties. Keeping this view, the present review deals with the concept of time-based alterations of concentration of heavy metal ions (TACMI) in biological systems. On the basis of TACMI concept formation of organism resistance to metal ions action could be explained. In the event of slow increase of its concentration in organism, it produces induction of metallothioneins, other stress-proteins and relative changes in the whole metabolic system. This, first of all, results in formation of new specific epigenotypes, which provide higher resistance (hormesis effect) not only to metal ions that induced this effect, but also to such stress-factors as high temperature (at least, for micro-algae cells).

Age-dependent fecundity of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) with sublethal doses of gammacyhalothrin

Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) was exposed to gammacyhalothrin to study the stimulatory effect of low concentrations of this pyrethroid. The doses studied were 23.4375, 11.7188, 5.8594, 2.9297, 1.4648, 0.7324 mg.litre-1 and water, as control. The third, fourth, and fifth instars of P. nigrispinus were shorter with all the doses of this insecticide. The survival and longevity of this predator was highest with the lowest doses. The oviposition period of P. nigrispinus decreased as the doses increased. The lowest pre-and postoviposition periods were found with 11.7188 mg.litre-1 of gammacyhalothrin. The dose 0.7324 mg.litre-1 increased the clutch interval. The egg viability was similar between the treatments. The number of eggs per clutch, clutches per female, incubation period, and female body weight were not affected. The hormesis response could be used as a tool for IPM programs, allowing the manipulating parameters of this predator in synergism with this insecticide.

Estudou-se o efeito estimulatório de baixas concentrações de gamacihalotrin sobre Podisus nigrispinus (Dallas)(Heteroptera: Pentatomidae). As doses de gamacihalotrin estudadas foram: 23,4375, 11,7188, 5,8594, 2,9297, 1,4648, 0,7324 mg.litro-1 e água (controle). Todas as doses estudadas de gamacihalotrin reduziram o período de desenvolvimento do 3º, 4º e 5º ínstares de P. nigrispinus. A sobrevivência e a longevidade do predador foram mais altas quando foi exposto a baixas doses. O período de oviposição de P. nigrispinus reduziu á medida que foram aumentadas as doses de gamacihalotrin. A dose de 11,7188 mg.litro-1 de gamacihalotrin causou os mais curtos períodos de pré-oviposição e pós-oviposição. O intervalo entre posturas aumentou com a dose de 0,7324 mg.litro-1 de gamacihalotrin. A viabilidade de ovos não foi afetada pelo piretróide. O número de ovos por postura, posturas por fêmea, período de incubação e peso corpóreo de fêmea não foram afetados pelas doses testadas de gamacyhalotrin.

Hormesis response of marine and freshwater luminescent bacteria to metal exposure

The stimulatory effect of low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used luminescence bioassay. This paper aims to study the hormesis phenomenon in both marine and freshwater luminescent bacteria, named Photobacterium phosphorem and Vibrio qinghaiensis. The effects of Cu (II), Zn (II), Cd (II) and Cr (VI) on luminescence of these two bacteria were studied for 0 to 75 minutes exposure by establishing dose- and time-response curves. A clear hormesis phenomenon was observed in all four testing metals at low concentrations under the condition of luminescence assays.

Low-dose Radiation-induced Hormetic Effect in the Rat Ovarian Follicle / 체질인류학회지

Hormesis is the generally-favorable biological responses to low exposures to toxins and other stressors. Radiation hormesis is the theory that ionizing radiation is benign at low levels of exposure, and that doses at the level of natural background radiation can be beneficial. The purpose of this study is to reveal the hormetic effect of low-dose radiation of ionizing radiation on the ovarian follicles of 4-week old female mice. Mice were grouped into control group, 2 cGy irradiated group, 2 cGy and 2 Gy irradiated group (2 cGY pre-exposure group), and 2 Gy irradited group. Mice were sacrificed by cervical dislocation 24 hours after irradiation, removed ovaries, fixed in neutral formaldehyde solution for 24 hours, embedded with paraffin, stained with hematoxylin and eosin and TUNEL immunohistochemically, and observed light microscopically the atretic follicles and normal follicles in various follicular developmental stages. In this experiment, the ratrio of atretic follicles to entire follicles in an ovary increased significantly in 2 Gyirradiated group compared with 2 cGY pre-exposure group, and the ratio of normal follicles to the entire follicles in an ovary in all the developmental stages were increased significantly in the 2 cGY pre-exposure group compared with 2 Gy-irradiated group. These results mean that low-dose radiation pre-exposure can induce the hormetic effect in the developing ovarian follicle.

Desenvolvimento e Reprodução do Predador Podisus distinctus (Stal) (Heteroptera: Pentatomidae) Frente a Doses Subletais de Permetrina / Development and Reproduction of the Predator Podisus distinctus (Stal) (Heteroptera: Pentatomidae) Exposed to Sublethal Doses of Permethrin

Development and reproduction were studied in the predator Podisus distinctus (Stal) subjected to sublethal doses of the insecticide permethrin under laboratory conditions. Third instar nymphs were subjected to topical application of permethrin at the doses of 0, 0.0172, 0.172, 1.72, 17.2 e 172 ppb. The only parameter statisticaly different was egg viability. This parameter had the gratest increase at the dose 0.172 ppb provinding evidence for the phenomenon of hormesis.

Desenvolvimento e reprodução foram estudados no predador Podisus distinctus (Stal) submetido a doses subletais do inseticida permetrina em condições de laboratório. Ninfas de 3° instar foram submetidas a aplicação tópica de permetrina nas doses de 0; 0,0172; 0,172; 1,72; 17,2 e 172 ppb. O único parâmetro significativamente afetado foi a viabilidade de ovos. Esse parâmetro teve um máximo de estímulo na dose 0,172 ppb provendo evidência do fenômeno de hormese.

The effect with inhalation of radon water (Ikeda mineral spring) of a half life time on tissue perfusion / 日本温泉気候物理医学会雑誌

We previously found experimentally that the subcutaneous tissue perfusion rate was increased by about 16% upon inhalation of high concentration radon (13, 764-23, 743Bq/l).<br>To clarify the effect of a lower concentration of radon water by mass spectrometry, the subcutaneous tissue perfusion rate was determined experimentally in rabbits using fourth-day radon water of a 3, 519-6, 710Bq/l concentration taken from a mineral spring.<br>The subcutaneous tissue perfusion rate with inhalation of the radon water was 15.81±3.10ml/100g/min (mean±SD, n=10), which was similar to that with inhalation with physiological saline solution (15.96±3.09ml/1008/min, n=16). However, the subcutaneous tissue perfusion rate with inhalation of more highly concentrated, first-day, radon water (8, 641-17, 366Bq/l) was 20.76±3.58ml/100g/min (n=16), being significantly higher (p<0.01) than that with water at lower radon concentration.<br>Further studies are needed on the effect of radon water in relation to the hormesis with low dose of radiation.