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Djelovanje Radiofrekvencijskog Elektromagnetskog Zračenja na Spermatogenez u Sisavaca

Prema podacima dostupnima javnosti, smatra se da je u Hrvatskoj broj aktivnih mobilnih linija dosegao broj od oko 4 milijuna, dok se u cijelome svijetu taj broj penje na vrtoglave 2 milijarde. Zbog toga se postavlja pitanje djelovanja radiofrekvencijskog (RF) zračenja na zdravlje čovjeka, posebno na reprodukcijsko zdravlje i eventualne posljedice na zdravlje budućeg potomstva. Svrha ovog članka je pregled dosadašnjih istraživanja utjecaja RF zračenja mobilnih telefona na muški reprodukcijski sustav. Neka istraživanja provedena u uvjetima in vivo i in vitro pokazala su da RF zračenje može utjecati na stanicu i pojedine stanične dijelove. Dio istraživanja je pokazao da RF zračenje može utjecati na reprodukcijski sustav sisavaca i na stanice spermatogeneze. Budući da je spermatogeneza u normalnim fiziološkim uvjetima uravnotežen proces diobe, sazrijevanja i pohrane stanica, podložan je i osjetljiv na vanjske podražaje. Posebno osjetljive strukture u stanici su proteini koji čine stanični kostur, odnosno citoskelet. Citoskelet je strukturalni i funkcionalni dio stanice koji, između ostaloga, ima važnu ulogu u pokretanju spermija te sudjeluje u morfološkim i funkcionalnim promjenama stanica tijekom spermatogeneze.

Abstract

This article discusses the availability and completeness of medical data on workers from the AREVA NC Pierrelatte nuclear plant and their possible use in epidemiological research on cardiovascular and metabolic disorders related to internal exposure to uranium. We created a computer database from files on 394 eligible workers included in an ongoing nested case-control study from a larger cohort of 2897 French nuclear workers. For each worker, we collected records of previous employment, job positions, job descriptions, medical visits, and blood test results from medical history. The dataset counts 9,471 medical examinations and 12,735 blood test results. For almost all of the parameters relevant for research on cardiovascular risk, data completeness and availability is over 90 %, but it varies with time and improves in the latest time period. In the absence of biobanks, collecting and computerising available good-quality occupational medicine archive data constitutes a valuable alternative for epidemiological and aetiological research in occupational health. Biobanks rarely contain biological samples over an entire worker’s carrier and medical data from nuclear industry archives might make up for unavailable biomarkers that could provide information on cardiovascular and metabolic diseases

Long-Term Follow-Up Study of Genome Damage Elimination in Patients with Testicular Seminoma Exposed to Ionising Radiation during Radiotherapy

The rate of genome damage elimination after therapeutic exposure to ionising radiation was estimated in stage I testicular seminoma patients monitored over a seven-year follow-up. DNA damage elimination in peripheral lymphocytes of ten subjects was analysed by the chromosome aberration assay. Seven years after the end of radiotherapy, significantly increased frequency of ring and dicentric chromosomes was still detected in comparison with baseline values. These results indicate the induction of genome instability. Long-term follow-up studies of cancer patients after radiotherapy could give us valuable information on the rate of genome damage elimination after exposure to ionising radiation and about the duration and manifestation of genome instability. This may be used in health risk assessment related to the possible development of secondary neoplasia. Studies such as this could have a great value both for oncology and radiation protection management protocols, especially after accidental overexposures.

Non-Thermal Biomarkers of Exposure to Radiofrequency/Microwave Radiation

This article gives a review or several hypotheses on the biological effects of non-thermal radiofrequency/microwave (RF/MW) radiation and discusses our own findings from animal and in vitro studies performed over the last decade. We have found that RF/MW radiation disturbs cell proliferation and leads to cell differentiation in the bone marrow, which is reflected in the peripheral blood of rats. Repeated RF/MW radiation can also temporarily disrupt melatonin turnover. The observed changes seem to be a sign of adaptation to stress caused by irradiation rather than of malfunction. The article looks further into the basic mechanisms of RF/MW biological action, including cell growth parameters, colony-forming ability, viability, and the polar and apolar protein cytoskeleton structures. The observed reversible cell changes significantly obstructed cell growth. In contrast to the apolar intermediate proteins, the intracellular polar microtubule and actin fibres were damaged by radiation in a time-dependent manner. These significantly altered parameters can be considered as the biomarkers of exposure. Future research should combine dosimetry, experimental studies, and epidemiological data.

Abstract

Although ionising radiation has proven beneficial in the diagnosis and therapy of a number of diseases, one should keep in mind that irradiating healthy tissue may increase the risk of cancer. In order to justify an exposure to radiation, both the benefits and the risks must be evaluated and compared. The deleterious effects of medium and high doses are well known, but it is much less clear what effects arise from low doses (below 0.1 Gy), which is why such risk estimates are extremely important. This review presents the current state, important assumptions and steps being made in deriving cancer risk estimates for low dose exposures.

photoreceptor in skin and its role in photoimmunology. J Exp Med 1983;158:84-98. United States Environmental Protection Agency (US EPA). Stay Healthy in the Sun, information about UV radiation for meteorologists. Washington: US EPA; 1998. Lisac I. Sunčevo zračenje i UV indeks [Solar UV radiation and UV index, in Croatian]. Gospodarstvo i okoliš 1998;23:381-4. Vujnović V, Lisac I. Prostiranje Sunčeva zračenja kroz atmosferu i eritemalno učinkovito ultraljubičasto zračenje u Hrvatskoj [Solar radiation transfer through the atmosphere and erythermally effective UV radiation

Total Occupational Exposure During Characterisation, Conditioning, and Securing of Radioactive Sealed Sources: A New Dosimetric Concept Using Active Electronic Dosimeters

Radiation dosimetry in protection against ionising radiation involves research of all possible pathways through which natural or man-made radioactive materials can contaminate a habitat and actually harm its biota. It also takes into account natural and artificial (man-made) electromagnetic ionizing radiation (γ and x radiation). This article presents a dosimetric study assessing exposure to man-made ionising radiation of local environment and total occupational exposure of two professional workers involved in characterisation, conditioning, and securing of unused radioactive sealed sources. The purpose of the study was to validate a new active electronic dosimeter (AED) of type ALARA OD and to develop a new monitoring method by tracing the external occupational exposure over real time. This method is used to continuously measure and record external radiation doses and, which is a novelty, establish dose rates receiving pattern as a function of real time. Occupational whole body dosimetric results obtained with AED were compared with results obtained with passive dosimetry (film badge and thermoluminiscence). Air, dust, and silicon sand samples were analysed by gamma-spectrometry to estimate internal exposure of the two workers to 222Rn due to inhalation or ingestion of dust and sand in indoor air. In order to establish total occupational exposure, control radon measurement was performed in the immediate environment and the external Hazard index (Hex) was calculated.

Side Effects of Adjuvant Radiotherapy in Men with Testicular Seminoma Stage I

In this study we followed up the side effects of adjuvant radiotherapy in patients with testicular seminoma stage I over a period from 13 to 84 months (median 28 months). The most frequent side effects during radiotherapy were gastrointestinal (nausea/vomiting), psychological, cognitive, and minor sexual problems.

The reported side effects were treated by antiemetics and anxiolytics. After radiotherapy, the side effects persisted in 6 % of patients, but only a few of them required additional treatment. Healthy children were born to 76 % of patients in the 18 to 39 years age group. This study shows that adjuvant radiotherapy of the para-aortic lymph nodes with the total dosage of 24 Gy in 16 daily fractions administered to testicular seminoma patients causes acceptable side effects, does not adversely affect quality of life and fertility, if the approach to treatment is individual and family consulting is provided. This makes adjuvant radiotherapy of the para-aortic lymph nodes an acceptable treatment for testicular seminoma stage I patients.

Abstract

Basal cell carcinoma (BCC) is the most common cancer among Caucasians. It generally occurs on sun-exposed areas of the body, mostly on the head and neck (80%), trunk (15%), rarely on arms and legs. Basal cell carcinoma is a good example of a disease caused by a combination of genetic and environmental factors. Ultraviolet (UV) radiation plays a dual role in the development of BCC: it causes DNA damage and immunosuppression. UVA and UVB rays damage the DNA via various mechanisms. UVB radiation directly damages DNA within skin cells, causing cytosine → thymine mutations at dipyrimidine sites, whereas UVA radiation is 10.000 times less mutagenic, but it is significantly more present in the natural UV radiation. Also, UVA photons have lower energy than UVB photons and do not induce mutations. UV radiation exerts immune suppression by decreasing the antigen presenting cells ability and by producing immunosuppressive cytokines, such as interleukin-10 (IL-10) and tumor necrosis factor alpha (TNF-α). Mediators of UV-induced immunosuppression are DNA and cis-urocanic acid. Several studies showed a significant association between the development of BCC and sun-exposure during childhood and adolescence, and a strong relation with family history of skin cancer. Exposure to ionizing radiation increases the risk of nonmelanoma skin cancers by three times, while the risk is proportional to the radiation dose. Chemical carcinogens, such as arsenic, tar, psoralen, and pesticides, increase risks for nonmelanoma skin cancers, predominantly for squamous cell carcinoma (SCC). Regarding genetic predisposition, there is glutathione S-transferase (GST) as an important part of cellular defense against endogenous and exogenous chemicals. Several polymorphisms in GST family members have been associated with impaired detoxification, thus influencing the risk for some cancers, including nonmelanoma skin cancers. Cytochrome P450 enzymes are involved in detoxification of photosensitizing agents, and thus involved in BCC carcinogenesis. PTCH is a tumor suppressor gene first identified in patients with Gorlin syndrome. Abnormal activation of this gene and its pathways result in various types of tumorigenesis. BCC is associated with homozygous PTCH gene deletion. With regard to acquired genetic mutations, it was found that aggressive BCCs are significantly associated with increased p53 protein expression, probably representing the mutated form, although that assertion could not be established with certainty. Considering the apparently limited contribution of DNA damage and chromosome instability to the expression of BCC phenotype, the relevance of p53 mutations for BCC growth remains to be demonstrated. Data on the role of Bcl-2 gene family in the development of BCC are scarce. It is unclear whether Bcl-2 has a functional role in the development of BCC, or it only indicates the level of gene expression in tumor stem cells. Activation of Ras gene may play an important role during early stages in the development of nonmelanoma skin cancers, and it is often found on UV-exposed skin in BCC, actinic keratosis and SCC. Concerning immunologic factors, studies have shown that tumor necrosis factor-α (TNF-α) is the critical mast cell product involved in ultraviolet-induced immunosuppression: mast cells contain high quantities of TNF-α which is released after activation; the level of TNF-α is increased in the skin exposed to UV radiation disrupting the morphology and function of Langerhans cells, the principal antigen-presenting cells of the skin. An animal study suggests that the degree of susceptibility to ultraviolet-B-induced local immunosuppression depends on TNF-α level within the epidermis after UVB. It has been established that mast cell-derived histamine stimulates prostaglandin E2 (PGE2) production from keratinocytes. PGE2 alters the cytokine balance in favor of the immunosuppressive interleukin-10 (IL-10) against the immunostimulatory IL-12; histamine also increases suppressor T-cell function by binding to the H2 receptors, which in turn release higher levels of immune suppressive cytokines including IL-10 and induce apoptosis of antigen-presenting cells. All this results in a shift of the immune response from T helper 1 (Th1) cytokine profile to T helper 2 (Th2) cytokine profile, inhibiting antigen-presenting cells to induce antitumor activity.

Abstract

Individual sensitivity to ionising radiation (IR) is the result of interaction between exposure, DNA damage, and its repair, which is why polymorphisms in DNA repair genes could play an important role. We examined the association between DNA damage, expressed as micronuclei (MNi), nuclear buds (NBs), and nucleoplasmic bridges (NPBs) and single nucleotide polymorphisms in selected DNA repair genes (APE1, hOGG1, XRCC1, XRCC3, XPD, PARP1, MGMT genes; representative of the different DNA repair pathways operating in mammals) in 77 hospital workers chronically exposed to low doses of IR, and 70 matched controls. A significantly higher MNi frequency was found in the exposed group (16.2±10.4 vs. 11.5±9.4; P=0.003) and the effect appeared to be independent from the principal confounding factor. Exposed individuals with hOGG1, XRCC1, PARP1, and MGMT wild-type alleles or APEX1, as well as XPD (rs13181) heterozygous showed a significantly higher MNi frequency than controls with the same genotypes. Genetic polymorphism analysis and cytogenetic dosimetry have proven to be a powerful tool complementary to physical dosimetry in regular health surveillance programmes.