Comparative study of DNA damage and repair in head and neck cancer after radiation treatment.

We compared DNA damage and the efficacy of its repair after genotoxic treatment with gamma-radiation of lymphocytes and tissue cells isolated from patients with squamous cell carcinoma of head and neck (HNSCC) and healthy donors. Thirty-seven subjects with HNSCC and 35 healthy donors were enrolled in the study. The extent of DNA damage including oxidative lesions and efficiency of the repair were examined by alkaline comet assay. HNSCC cancer cells were more sensitive to genotoxic treatment and displayed impaired DNA repair. In particular, lesions caused by gamma-radiation were repaired less effectively in metastasis of HNSCC than in healthy controls. The differences in radiation sensitivity of cancer and control cells suggested that DNA repair might be critical for HNSCC treatment. We conclude that gamma-radiation might be considered as an effective therapeutic strategy for head and neck cancers, including patients in advanced stage of the disease with clear evidence of metastasis.

Role of impaired DNA repair in genotoxic susceptibility of patients with head and neck cancer.

DNA repair is critical for genotoxic susceptibility and cancer development. Forty-seven patients with head and neck squamous cell carcinoma (HNSCC) and 38 healthy controls were enrolled in this study. Among the patients, 16 subjects had metastasis of HNSCC. The extent of DNA damage, including oxidative lesions, and efficiency of repair after genotoxic treatment with hydrogen peroxide were examined using the alkaline comet assay. HNSCC cells were sensitive to genotoxic treatment and displayed impaired DNA repair. In particular, lesions caused by hydrogen peroxide were repaired less effectively in cancer cells from patients with metastasis than in cells from healthy controls. We suggest that impaired DNA repair might play a role in genotoxic susceptibility of patients with head and neck cancer. Finally, as a consequence of this finding we have shown that treatment with DNA-reactive drugs could be considered as an effective therapy strategy for head and neck cancer.

DNA damage and repair of head and neck cancer cells after radio- and chemotherapy.

DNA repair is critical for successful chemo- and radiotherapy of human tumours, because their genotoxic sensitivity may vary in different types of cancer cells. In this study we have compared DNA damage and the efficiency of its repair after genotoxic treatment with hydrogen peroxide, cisplatin and gamma-radiation of head and neck squamous cell carcinoma (HNSCC). Lymphocytes and tissue cells from biopsies of 37 cancer patients and 35 healthy donors as well as the HTB-43 larynx cancer cell line were employed. The cell sensitivity to genotoxic treatment was estimated by the MTT survival assay. The extent of DNA damage and efficiency of its repair was examined by the alkaline comet assay. Among the examined treatments, we found that HNSCC cells were the most sensitive to gamma-radiation and displayed impaired DNA repair. In particular, DNA damage was repaired less effectively in cells from HNSCC metastasis than healthy controls. In conclusion, our results suggest that the different genotoxic sensitivity of HNSCC cells may depend on their DNA repair capacity what in turn may be connected with the effectiveness of head and neck cancer therapy.

DNA damage and repair in children with Down's syndrome.

Down's syndrome (DS) is associated with the presence of a third 21 chromosome and is generally considered as a non-cancer-prone genetic disease. However, leukaemias occur more frequently in children with the syndrome than in general population and there is an open question, whether the presence of an additional chromosome may contribute to genomic instability, which, in turn, may play a role in a higher susceptibility to cancer and leukaemias in particular. In order to assess genomic instability associated with the presence of a third 21 chromosome, we determined the level of endogenous DNA damage and susceptibility to a genotoxic stress-inducing factor, hydrogen peroxide and N-methyl-N'-nitro-N-nitrosoguanidyne (MNNG) as well as the ability to remove DNA damage in the peripheral blood lymphocytes of children with DS and healthy kids. The level of DNA damage and the kinetics of DNA repair were evaluated by alkaline comet assay. Oxidative DNA damage was assayed with DNA repair enzymes: endonuclease III-like NTH1 and formamidopyrimidine-DNA glycosylase. The cells taken from children with DS did not display an effective DNA repair after treatment with 10 mM hydrogen peroxide. No difference in the sensitivity to DNA-damaging agents and the efficacy of DNA repair due to age and gender in DS children was observed. These results suggest that children with DS may be characterized by the increased sensitivity to the DNA-damaging agents impaired cellular reaction to DNA damage, which, in turn, may increase the probability of cancers in these children. Therefore, a special care to avoid exposure to potential mutagenic factor my be considered in these children.

[Isolated sarcoidosis of the neck--a report of two cases]. / Izolowana sarkoidoza szyi--opis dwóch przypadków.

Although the first description of sarcoidosis comes from 1877, its etiology still has not been determined. Its frequency in Europe is estimated at 10-80 new cases per 100 thousand people. Sarcoidosis is a granulomatous disease, manifesting mostly in enlargement of lymph nodes of a pulmonary hilus, in changes in pulmonary parenchyma and skin, eyeball, spleen and liver. Changes in about 30% cases also occur in lymph nodes of other regions (neck or retroperitoneal lymph nodes). Changes in salivary glands and heart have also been reported. Isolated sarcoidosis of peripheral lymph nodes occurs rarely. The paper presents two cases of the isolated sarcoidosis of neck lymph nodes. One of them relates to a 70-year-old woman, in which a lymph node sarcoidosis preceded by several months the occurrence of a typical systemic sarcoidosis engaging pulmonary hiluses. The other case is a 30-year-old man, in which the isolated sarcoidosis of lymph nodes was originally diagnosed as a tumor of a submandibular salivary gland. The difficulties in diagnostics of the isolated neck sarcoidosis is discussed as well as its atypical course in both described cases.

[Diagnostic problems in a case of the pyriform sinus carcinoma in a man]. / Trudnosci diagnostyczne w przypadku raka zachylka gruszkowatego u mezczyzny.

Despite a use of many diagnostic tools to assess the stage of the carcinoma of hypopharynx and larynx various problems can still arise. A 45 years old man was admitted with an initial diagnosis of carcinoma of the hypopharynx with metastases to neck lymphnodes (Tin situ N1). Computed tomography of the neck revealed pathologic remodeling of the thyroid cartilage. An oncologist decided to commence a chemotherapy. After 4 cycles of chemotherapy a second CT scan revealed a suspected neoplastic infiltration of the cricoid and thyroid cartilages. After that the patients was disqualified from both radio- and chemotherapy. The consulting laryngologist did not find any pathologies in the larynx and hypopharynx. On palpation there were no enlarged neck lymph nodes. The second specimen taken from the right pyriform sinus was a loosen fragment of the epithelium with the Ca male differentiatum G3. The positron emission tomography imaging found a suspected site 11 mm in diameter situated in front of the carotid vessels. The neoplastic infiltration of the larynx was not confirmed. The patient started the radiotherapy. We are of the opinion that in the presented case the erroneous interpretation of the CT scan was a likely consequence of the improper setting of a window of brightness and contrast. Strong artifacts are also observed in 3D imaging. Another cause of the diagnostic problems could stem form an unfinished calcification of the cartilages which produced an image of irregular areas of calcification and rarely diagnosed T in situ in a pyriform sinus.

[Ameloblastoma of the maxillary sinus--a case report]. / Szkliwiak zatoki szczekowej--opis przypadku.

Ameloblastoma (adamantinoma) is a benign neoplasm deriving from the enamel organ. Its etiology has not been ultimately determined. It constitutes about 1% of all head and neck tumours, and about 11% of teeth-originating tumours. Usually it occurs in the mandible near premolar and molar teeth, more rarely in its anterior part. About 20% of described cases of ameloblastoma relate to the jaw, its very rare location is gingiva or cheak tunica mucosa. The essay presents a case of ameloblastoma of a maxillary sinus in a 65-year-old man. The diagnostic and treatment algorithm in ameloblastoma is discussed.

Protective action of melatonin against oxidative DNA damage: chemical inactivation versus base-excision repair.

Melatonin is a hormone-like substance that has a variety of beneficial properties as regulator of the circadian rhythm and as anti-inflammatory and anti-cancer agent. The latter activity can be linked with the ability of melatonin to protect DNA against oxidative damage. It may exert such action either by scavenging reactive oxygen species or their primary sources, or by stimulating the repair of oxidative damage in DNA. Since such type of DNA damage is reflected in oxidative base modifications that are primarily repaired by base-excision repair (BER), we tried to investigate in the present work whether melatonin could influence this DNA-repair system. We also investigated the ability of melatonin to inactivate hydrogen peroxide, a potent source of reactive oxygen species. Melatonin at 50 microM and its direct metabolite N(1)-acetyl-N(2)-formyl-5-methoxykynuramine reduced DNA damage induced by hydrogen peroxide at approximately the same ratio. Melatonin stimulated the repair of DNA damage induced by hydrogen peroxide, as assessed by the alkaline comet assay. However, melatonin at 50 microM had no impact on the activity in vitro of three glycosylases playing a pivotal role in BER: Endo III, Fpg and ANPG 80. On the other hand, melatonin chemically inactivated hydrogen peroxide, reducing its potential to damage DNA. And finally, melatonin did not influence the repair of an a-basic (AP) site by cellular extracts, as was evaluated by a functional BER assay in vitro. In conclusion, melatonin can have a protective effect against oxidative DNA damage by chemical inactivation of a DNA-damaging agent as well as by stimulating DNA repair, but key factors in BER, viz. glycosylases and AP-endonucleases, do not seem to be affected by melatonin. Further study with other components of the BER machinery and studies aimed at other DNA-repair systems are needed to clarify the mechanism underlying the stimulation of DNA repair by melatonin.

DNA damage and repair in gastric cancer--a correlation with the hOGG1 and RAD51 genes polymorphisms.

The cell's susceptibility to mutagens and its ability to repair DNA lesions are important for cancer induction, promotion and progression. Both the mutagens' sensitivity and the efficacy of DNA repair may be affected by variation in several genes, including DNA repair genes. The hOGG1 gene encodes glycosylase of base excision repair and RAD51 specifies a key protein in homologues recombination repair. Both can be involved in the repair of oxidative DNA lesions, which can contribute to stomach cancer. In the present work we determined the level of basal and oxidative DNA damage and the kinetics of removal of DNA damage induced by hydrogen peroxide in peripheral blood lymphocytes of 30 gastric cancer patients and 30 healthy individuals. The metrics from DNA damage and repair study were correlated with the genotypes of common polymorphisms of the hOGG1 and RAD51 genes: a G-->C transversion at 1245 position of the hOGG1 gene producing a Ser-->Cys substitution at the codon 326 (the Ser326Cys polymorphism) and a G-->C substitution at position 135 (5'-untranslated region) of the RAD51 gene (the G135C polymorphism). DNA damage and repair were evaluated by alkaline single cell gel electrophoresis (comet assay) assisted by DNA repair enzymes: endonuclease III (Nth) and formamidopyrimidine-DNA glycosylase (Fpg), preferentially recognizing oxidized DNA bases. The genotypes of the polymorphism were determined by restriction fragment length polymorphism PCR. We observed a strong association between gastric cancer occurrence, impaired DNA repair in human lymphocytes and the G/C genotype of the G135C polymorphism of the RAD51 gene. Moreover, there was a strong correlation between that genotype and stomach cancer occurrence in subjects with high level of oxidatively damaged DNA. We did not observe any correlation between the Ser1245Cys polymorphism of the hOGG1 gene and gastric cancer, including subjects with impaired DNA repair and/or high levels of endogenous oxidative DNA lesions. Therefore, our result suggest that the G135C polymorphism of the RAD51 gene may be linked with gastric cancer by the modulation of the cellular response to oxidative stress and this polymorphism may be a useful additional marker in this disease along with the genetic or/and environmental indicators of oxidative stress.

Helicobacter pylori infection can modulate the susceptibility of gastric mucosa cells to MNNG.

The pathogenesis of stomach cells can be associated with their susceptibility to exogenous dietary irritants, like nitrosamines such as dimethylnitrosamines (DMNA), and to the effects of non-dietary factors, including Helicobacter pylori infection. We used N-methyl-N'-nitro N-nitrosoguanidyne (MNNG) as a surrogate agent that induces a spectrum of DNA damage similar to DMNA. Using the alkaline comet assay, we showed that antioxidants--vitamins C and E, quercetin, and melatonin--reduced the genotoxic effect of MNNG in H. pylori-infected and non-infected human gastric mucosa cells (GMCs). To compare the sensitivity of the stomach and the blood, the experiment was also carried out in peripheral blood. We observed a higher level of DNA damage induced by MNNG in H. pylori-infected than in noninfected GMCs. We did not note any difference in the efficacy of the repair of the damage in either type of GMC. H. pylori infection may play an important role in the pathogenesis of GMCs, as it can modulate their susceptibility to dietary mutagens/carcinogens, thus contributing to gastric cancer.

Imatinib (STI571) inhibits DNA repair in human leukemia oncogenic tyrosine kinase-expressing cells.

BCR/ABL oncogene, as a result of chromosome aberration t(9;22), is the pathogenic principle of almost 95% of human chronic myeloid leukemia (CML). Imatinib (STI571) is a highly selective inhibitor of BCR/ABL oncogenic tyrosine kinase used in leukemia treatment. It has been suggested that BCR/ABL may contribute to the resistance of leukemic cells to drug and radiation through stimulation of DNA repair in these cells. To evaluate further the influence of STI571 on DNA repair we studied the efficacy of this process in BCR/ABL-positive and -negative cells using single cell electrophoresis (comet assay). In our experiments, K562 human chronic myeloid leukemia cells expressing BCR/ABL and CCRF-CEM human acute lymphoblastic leukemia cells without BCR/ABL expression were employed. The cells were exposed for 1 h at 37 degrees C to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) at 5 microM, mitomycin C (MMC) at 50 microM or to gamma-radiation at 15 Gy with or without a 24 h preincubation at 1 microM of STI571. The MTT cells survival after 4 days of culture showed that STI571 enhanced the cytotoxity of the examined compounds in the K562 line. Further it was found, that the inhibitor decreased the efficacy of DNA repair challenged by each agent, but only in the K562 expressing BCR/ABL. Due to the variety of DNA damage induced by the employed agents in this study we can speculate, that BCR/ABL may stimulate multiple pathways of DNA repair. These results extend our previous studies performed on BCR/ABL-transformed mouse cells onto human cells. It is shown that BCR/ABL stimulated DNA repair in human leukemia cells. In conclusion we report that STI571 was found to inhibit DNA repair and abrogate BCR/ABL-positive human leukemia cells therapeutic resistance.

[Head shaking test (HSN) using to diagnose vestibule damage]. / Test szybkich pólobrotów glowa (HSN--head shaking test) zastosowany w rozpoznawaniu uszkodzen narzadu przedsionkowego.

INTRODUCTION: There is described a transient nystagmus provoked by shaking the head in the horizontal plane for a few seconds in both normal subjects and patients that is called Head Shaking Test (HSN) as a diagnostic tool for vestibular dysfunction. HSN is generally accepted that is generated by an asymmetrical peripheral vestibular input and a central velocity storage mechanism, which integrate and extend the peripheral vestibular signals. Purposes 1. Creation of own modification method of stimulation and registration HSN 2. Estimation of HSN test value to show asymmetrical function of vestibular system 3. Establish possibility of HSN test to localization of damage vestibular system 4. Verification this test to use it as screening test MATERIAL AND METHODS: Studied group was consisted of 111 subjects that consist of 68 women and 43 men with mean age 52,4 years. All patients and controls were submitted to audiological tests and vestibular examinations According to the results of the otoneurological tests, patients were divided into: 36 with peripheral vestibular disease, 37 with central vestibular disease, 6 with both peripheral and central vestibular disease and 32 control persons. Own modified HSN test was described. Frequency of movements was approximately 2 Hz determined by metronome. HSN was recorded using ENG apparatus produced by Hartmann. RESULTS: In the first study stage incidence of HSN-H and HSN-V related to localization of vestibular organ damage, symmetric and asymmetric reaction in tested. It was observed more incidence of HSN-H and HSN-V in patients with peripheral and central lesion of vestibular system than in control group. Estimation of HSN incidence related to kinetic test--acceleration-deceleration rotary test shows the same HSN frequency in compared groups, with symmetric or asymmetric reaction in rotary test. HSN frequency related to caloric test (canal paresis) showed statistic differences between normal and canal paresis reaction in caloric test. Analysis incidence of HSN-V revealed no significant differences between examined groups. In the second studied stage the sensitivity and specificity were examined. CONCLUSIONS: 1. It is possible to make HSN test using metronome and ENG recording 2. HSN test may be use to reveal asymmetry of vestibular function. 3. HSN is helpful to diagnose peripheral and central lesion to some extent. 4. HSN is not useful as screening test

[The role of a psychologist in a rehabilitation of the patients with laryngeal cancer after total laryngectomy with implantation of the voice prostheses]. / Rola psychologa w rehabilitacji pacjentów po laryngektomii calkowitej z powodu raka krtani z zastosowaniem protez glosowych.

The new possibilities of voice rehabilitation in patients with laryngeal cancer who undergo total laryngectomy have been opened with the surgical insertion of voice prostheses after performing of the tracheoesophageal shunt. This method enables to achieve a voice of better quality which leads to improved patients' general well-being. The cornerstone of the rehabilitation after an implantation of voice prosthesis is an appropriate psychosocial attitude of a patient towards combating of a cancer and his motivation for a verbal communication. In this review we have characterized both a role of the psychologist in the diagnostic and therapeutic team and psychological attitudes of the patients with cancer. These problems were illustrated by the clinical cases.

Personal experiences with vestibular evoked myogenic potentials as a modern method of diagnosing vestibular organ lesion and monitoring treatment.

Vestibular evoked myogenic potentials (VEMPs) appear to represent a new and promising technique for the assessment of vestibulospinal reflex function. The primary aims of the study described in this article were (1) to record VEMPs in normal volunteers using available equipment and to establish a range of norms of VEMP parameter values (latency, amplitude); (2) to confirm the saccular origin of VEMPs; (3) to assess the diagnostic significance of VEMPs; and (4) to evaluate the usefulness of VEMPs in monitoring therapeutic results. The study population consisted of 252 patients representing various diagnoses of hearing loss and vestibular organ lesion. Twenty-three patients were treated with an antihomotoxic remedy, and some received placebo. The results of this study demonstrated that VEMPs are helpful in evaluating the physiological and pathological equilibrium system and in monitoring reflex reactions after treatment.

[Objective examination of vestibular organs to differentiate the location of damage]. / Obiektywne badania narzadu przedsionkowego w róznicowaniu lokalizacji uszkodzenia.

The purpose of study was estimation of vestibular organ function based on results of caloric tests with computer analysis of ENG recordings, vestibular evoked myogenic potentials (VEMPs), comparison of compatibility of obtained evaluation in both ENG and VEMP and also attempt to localize vestibular organ lesion according to objective tests. Studied population consisted of 76 persons divided to three groups related to ENG results. The group I formed ills with unilateral canal paresis, group II consisted of patients with vestibular excitability abolition and group III was made up of healthy volunteers. All persons were carried out pure tone audiometry, word recognition test, extra threshold audiometry, bicaloric tests and registration of VEMPs and in chosen cases had MRI. Results of study suggested that VEMPs present valuable and supplementary method in vestibular lesion topodiagnosis.

The DNA-damaging potential of tamoxifen in breast cancer and normal cells.

Tamoxifen (TAM) is a non-steroidal anti-estrogen used widely in the treatment and chemoprevention of breast cancer. TAM treatment can lead to DNA damage, but the mechanism of this process is not fully understood and the experimental data are often inconclusive. We compared the DNA-damaging potential of TAM in normal human peripheral blood lymphocytes and MCF-7 breast cancer cells by using the comet assay. In order to assess whether oxidative DNA damage may contribute to TAM-induced lesions, we employed two DNA repair enzymes: endonuclease III (Endo III) and formamidopyrimidine-DNA glycosylase (Fpg). The kinetics of repair of DNA damage was also measured. In order to evaluate the involvement of free radicals in the genotoxicity of TAM we pre-treated the cells with nitrone spin traps: DMPO and POBN. The use of common antioxidants: vitamin C, amifostine and genistein, helped to assess the contribution of free radicals. TAM damaged DNA in both normal and cancer cells, inducing mainly DNA strand breaks but not alkali-labile sites. The drug at 5 and 10 microM induced DNA double strand breaks (DSBs) in lymphocytes and at 10 microM in MCF-7 cells. We observed complete repair of DSBs in cancer cells by contrast with incomplete repair of these lesions in lymphocytes. In both types of cells TAM induced oxidized purines and pyrimidines. Incubation of the cells with nitrone spin traps and antioxidants decreased, with exception of amifostine in MCF-7 cells, the extents of DNA damage in both kinds of cells, but the results were more distinct in cancer cells. Our results indicate that TAM can be genotoxic for normal and cancer cells by free radicals generation. It seems to have a higher genotoxic potential for normal cells, which can be the result of incomplete repair of DNA DSBs. Free radicals scavengers can modulate TAM-induced DNA damage interfering with its antitumour activity in cancer cells.