Effects of Iron Supplementation on Metabolism in Calves Receiving Whole Milk.

The objective of this study was to determine the effects of feeding a protein-iron complex (PIC) to calves. Specifically, the aim was to understand how it influences productive performance and indicators of iron metabolism, hematology and biochemical and parameters during feeding with whole milk before weaning. The study was carried out on 20 Polish Holstein Friesian calves. The calves were then divided into a control group (CON), fed with full milk (n = 10), and an experimental group (MFe), who received a PIC additive in milk at 16 g/day (n = 10). In order to determine the production parameters, the calves were weighed at the beginning (i.e., on the 7th day of life) and at the end of the experiment (42nd day of life) using an electronic platform scale. Production parameters such as average weight gain (AWG), feed conversion ratio (FCR), and growth rate (GR) were assessed. Blood was collected from an external jugular vein (vena jugularis externa) on the 7th, 14th, 28th, and 42nd days of life. The mean daily gains in body weight (ADG), growth rate (GR), and the feed conversion ratio were highest in the experimental group, MFe. Therefore, it can be concluded that the addition of a protein-iron complex entailed a significant impact on the iron metabolism indicators in the MFe experimental group.

Postzygotic mosaicism of a novel PTPN11 mutation in monozygotic twins discordant for metachondromatosis.

Genetic mosaicism caused by postzygotic mutations is of a great interest due to its role in human disease. Monozygotic twins arising from a single zygote are considered as genetically identical, and any differences likely to be caused by postzygotic events. Thus, phenotypically discordant monozygotic twins offer a unique opportunity to study genotype-phenotype correlation. Here, we present a three-generation family starting from a pair of monozygotic twins discordant for metachondromatosis due to postzygotic p.(Gln175His) variant in the PTPN11 gene. Both phenotypically discordant monozygotic twins harbor p.(Gln175His), however significant differences in mosaic ratio is observed not only between twins, but also within different tissue types within one individual. Phenotypic manifestation of p.(Gln175His) in examined family clearly depends on allele variant fraction (VAF). Individuals harboring constitutional mutation (VAF 50%) present typical metachondromatosis. Milder phenotype is observed in twin harboring high-level mosaicism in the tissue of ectodermal origin (VAF 45%), but not in a blood (VAF 5%). Finally, her twin sister harboring low-level mosaicism in blood (VAF 2%) and nonblood (VAF 12%) tissues is phenotypically normal. Our results provide insights into biological role of mosaicism in disease and further support the usefulness of nonblood tissues as an optimal source of DNA for the identification of postzygotic mutations in phenotypically discordant monozygotic twins.

Efficacy and safety of sirolimus therapy in familial hypoinsulinemic hypoglycemia caused by AKT2 mutation inherited from the mosaic father.

Activating mutation in the insulin signal-transducing kinase AKT2 results in severe hypoinsulinemic hypoketotic hypoglycemia and a characteristic phenotype of possible overgrowth and, sometimes, acanthosis nigricans. Herein, we describe a metabolic and hormonal profile before and during treatment with sirolimus in two brothers with AKT2 mutation inherited from the mosaic father, who showed low-level mosaicism in sperm. The boys, aged 1 and 14, who had severe non-insulin-dependent hypoketotic hypoglycemia and a typical dysmorphism, were admitted to endocrinology department for the analysis of their metabolic parameters: lipids, lactate, ammonia, glucose, insulin, c-peptide, and hormones (GH, IGF1, IGFBP3, TSH, fT4, cortisol, ACTH) before and during treatment with sirolimus. Previously, they had been treated with high-carbohydrate diet. The brothers were started on sirolimus with subsequent normalization of glycemia and reduced carbohydrate feedings overnight. The lowest fasting glucose levels improved from 20 mg/dl to 45 mg/dl in both sibs. The BMI of both brothers significantly dropped. After 6 months of sirolimus therapy we did not observe any laboratory or clinical side effects of the treatment.

The Role of ER Stress-Related Phenomena in the Biology of Malignant Peripheral Nerve Sheath Tumors.

Malignant peripheral nerve sheath tumors (MPNST) are rare but one of the most aggressive types of cancer. Currently, there are no effective chemotherapy strategies for these malignancies. The inactivation of the neurofibromatosis type I (NF1) gene, followed by loss of TP53, is an early stage in MPNST carcinogenesis. NF1 is a negative regulator of the Ras proteins family, which are key factors in regulating cell growth, homeostasis and survival. Cell cycle dysregulation induces a stress phenotype, such as proteotoxic stress, metabolic stress, and oxidative stress, which should result in cell death. However, in the case of neoplastic cells, we observe not only the avoidance of apoptosis, but also the impact of stress factors on the treatment effectiveness. This review focuses on the pathomechanisms underlying MPNST cells physiology, and discusses the possible ways to develop a successful treatment based on the molecular background of the disease.

Brain Tissue Low-Level Mosaicism for MTOR Mutation Causes Smith-Kingsmore Phenotype with Recurrent Hypoglycemia-A Novel Phenotype and a Further Proof for Testing of an Affected Tissue.

De novo somatic variants in genes encoding components of the PI3K-AKT3-mTOR pathway, including MTOR, have been linked to hemimegalencephaly or focal cortical dysplasia. Similarly to other malformations of cortical development, this condition presents with developmental delay and intractable epilepsy, often necessitating surgical treatment. We describe a first patient with the Smith-Kingsmore syndrome phenotype with recurrent hypoglycemia caused by low-level mosaic MTOR mutation restricted to the brain. We provide discussion on different aspects of somatic mosaicism. Deep exome sequencing combined with a variant search in multiple tissues and careful phenotyping may constitute a key to the diagnosis of the causes of rare brain anomalies.

New Tetrahydroacridine Hybrids with Dichlorobenzoic Acid Moiety Demonstrating Multifunctional Potential for the Treatment of Alzheimer's Disease.

A series of new tetrahydroacridine and 3,5-dichlorobenzoic acid hybrids with different spacers were designed, synthesized, and evaluated for their ability to inhibit both cholinesterase enzymes. Compounds 3a, 3b, 3f, and 3g exhibited selective butyrylcholinesterase (EqBuChE) inhibition with IC50 values ranging from 24 to 607 nM. Among them, compound 3b was the most active (IC50 = 24 nM). Additionally, 3c (IC50 for EeAChE = 25 nM and IC50 for EqBuChE = 123 nM) displayed dual cholinesterase inhibitory activity and was the most active compound against acetylcholinesterase (AChE). Active compound 3c was also tested for the ability to inhibit Aß aggregation. Theoretical physicochemical properties of the compounds were calculated using ACD Labs Percepta and Chemaxon. A Lineweaver-Burk plot and docking study showed that 3c targeted both the catalytic active site (CAS) and the peripheral anionic site (PAS) of AChE. Moreover, 3c appears to possess neuroprotective activity and could be considered a free-radical scavenger. In addition, 3c did not cause DNA damage and was found to be less toxic than tacrine after oral administration; it also demonstrated little inhibitory activity towards hyaluronidase (HYAL), which may indicate that it possesses anti-inflammatory properties. The screening for new in vivo interactions between 3c and known receptors was realized by yeast three-hybrid technology (Y3H).

The Role of the ER-Induced UPR Pathway and the Efficacy of Its Inhibitors and Inducers in the Inhibition of Tumor Progression.

Cancer is the second most frequent cause of death worldwide. It is considered to be one of the most dangerous diseases, and there is still no effective treatment for many types of cancer. Since cancerous cells have a high proliferation rate, it is pivotal for their proper functioning to have the well-functioning protein machinery. Correct protein processing and folding are crucial to maintain tumor homeostasis. Endoplasmic reticulum (ER) stress is one of the leading factors that cause disturbances in these processes. It is induced by impaired function of the ER and accumulation of unfolded proteins. Induction of ER stress affects many molecular pathways that cause the unfolded protein response (UPR). This is the way in which cells can adapt to the new conditions, but when ER stress cannot be resolved, the UPR induces cell death. The molecular mechanisms of this double-edged sword process are involved in the transition of the UPR either in a cell protection mechanism or in apoptosis. However, this process remains poorly understood but seems to be crucial in the treatment of many diseases that are related to ER stress. Hence, understanding the ER stress response, especially in the aspect of pathological consequences of UPR, has the potential to allow us to develop novel therapies and new diagnostic and prognostic markers for cancer.

Sirt3 regulates the level of mitochondrial DNA repair activity through deacetylation of NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 in colorectal cancer.

Colorectal cancer (CRC) is one of the most common malignant tumors. One of the factors increasing the risk of its occurrence may be the reduced efficiency of repairing DNA damage, both nuclear and mitochondrial. The main mechanism for repairing oxidative damage is the BER system (in mitochondria mtBER), whose key proteins NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 obtain full efficiency only at the appropriate level of acetylation. Sirtuin 3 is a key protein for mitochondrial homeostasis, regulating a number of metabolic processes related mainly to the control of the level of reactive oxygen species. Because Sirt3 possesses acetylase activity, it can modulate the level of activity of mtBER proteins by their deacetylation. The conducted study showed that the tested proteins NEIL1, NEIL2, OGG1, MUTYH, APE1 and LIG3 are the substrate for the enzymatic deacetylation activity of Sirt3, which may lead to modulation of the risk of CRC, and in cancer cells may be a potential therapeutic target enhancing the action of cytostatic drugs.

Multivalent Metallosupramolecular Assemblies as Effective DNA Binding Agents.

We report the implementation of coordination chemistry onto the generation of new types of metallosupramolecular complexes with laterally appended cationic moieties for DNA binding in buffered aqueous media. Utilization of an N,N,O-type coordination pocket along with an octahedral zinc(II) metal ion allowed us to obtain mono- and tetranuclear complexes in both solution and solid state, as confirmed by NMR spectroscopy and single-crystal X-ray diffraction, respectively. By using isothermal titration calorimetry and gel electrophoresis, multiply charged cationic assemblies were observed to effectively bind to DNA through multivalent electrostatic interactions. Furthermore, we observed a correlation between the multivalency of the compounds employed and the effectiveness of DNA binding.

Impact of the Ser326Cys polymorphism of the OGG1 gene on the level of oxidative DNA damage in patients with colorectal cancer.

As a result of reactive oxygen species operation, cell damage occurs in both cellular organelles and molecules, including DNA. Oxidative damage within the genetic material can lead to accumulation of mutations and consequently to cancer transformation. OGG1 glycosylase, a component of the Base Excision Repair (BER) system, is one of the enzymes that prevents excessive accumulation of 8-oxoguanine (8-oxG), the most common compound formed by oxidative DNA damage. In case of structural changes of OGG1 resulting from polymorphic variants, we can observe a significant increase in the concentration of 8-oxG. Linking individual polymorphisms to DNA repair systems with increased risk of colorectal cancer will allow patients to be classified as high risk and included in a prophylactic program. The aim of the study was to determine the level of oxidative DNA damage and to analyze the distribution of Ser326Cys polymorphism of the OGG1 gene in a group of patients with colorectal cancer and in a control group in the Polish population. MATERIAL AND METHODOLOGY: DNA was isolated from the blood of 174 patients with colorectal cancer. The control group consisted of 176 healthy individuals. The level of oxidative damage was determined by analyzing the amount of 8-oxguanine using the HT 8-oxo-dG ELISA II Kit. Genotyping was performed via the TaqMan method. RESULTS: The obtained results indicate that Ser326Cys polymorphism of the OGG1 gene increases the risk of RJG and is associated with significantly increased levels of 8-oxoguanine. CONCLUSIONS: Based on the results obtained, we conclude that Ser326Cys polymorphism of the OGG1 gene may modulate the risk of colorectal cancer by increasing the level of oxidative DNA damage.

An association of the MCP-1 and CCR2 single nucleotide polymorphisms with colorectal cancer prevalence.

THE AIM OF THE STUDY: We evaluated the connection between the presence of the -2518 A/G MCP-1 as well as 190 G/A CCR2 polymorphic variants and colorectal cancer (CRC) occurrence. MATERIAL AND METHODS: Study group consisted of subjects with different stages of CRC as well as healthy controls. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. RESULTS: W observed an association between the colorectal cancer and the GG genotype of the -2518 A/G MCP-1 single nucleotide polymorphism. No statistically significant correlation was found between CRC and the 190 G/A CCR2 polymorphism. CONCLUSION: The results of this study support the hypothesis that polymorphism in the MCP-1 gene may contribute to the etiology of colorectal cancer.

Altered Expression of miRNAs Is Related to Larynx Cancer TNM Stage and Patients' Smoking Status.

It has been reported that microRNAs (miRNAs) are responsible for acquiring all the hallmarks of cancer cells, as well as have a significant impact on the clinical management of cancers at every stage, including prognosis, remission, relapse, and metastasis. In this study, we investigated the association of miR-29a-3p, miR-202-3p, miR-3713, miR-4768-3p, and miR-548aa expression with clinicopathologic features in patients suffering from laryngeal cancer (LC) and determined the potential role of studied miRNAs in the progression of LC. The study group consisted of 48 patients with untreated primary tumors of head and neck cancer localized in the larynx. Expression of the selected miRNAs was verified by the qRT-PCR technique. We showed that the expression of miR-29a as well as miR-548aa was positively correlated with tumor stage and lymph node metastasis, whereas the expression of miR-4768-3p was negatively correlated with lymph node metastasis. Furthermore, we investigated that exposure to cigarette smoke altered miRNA expression profile in LC. The expression level of miR-202-3p was significantly increased in smoking patients compared with nonsmokers, whereas the miR-4768-3p, miR-548aa, and miR-3713 were markedly decreased. Our research contributed toward better elucidating the mechanisms underlying the progression of LC as well as the use of miRNAs inhibitors as novel agents against progression and metastasis of LC.

Evaluation of polymorphisms in microRNA biosynthesis genes and risk of laryngeal cancer in the Polish population.

MicroRNAs are the largest group of short regulatory RNAs. They regulate genes participating in many physiological and pathological processes. The role of micro RNAs in cancer development is also considerable. Therefore, the aim of this study was to evaluate the relationship between DROSHA (rs6877842) and DGCR8 (rs417309, rs1640299) gene polymorphisms with risk of occurrence of laryngeal cancer. The study included 100 patients and 100 healthy subjects. Genomic DNA was extracted from formalin-fixed, paraffin-embedded tissues. Analysis of the gene polymorphisms was performed using TaqMan SNP Genotyping Assay. The rs417309 AA genotype was found to be correlated with increased risk of larynx cancer. The rs1640299 TG and rs6877842 CG heterozygotes were significantly inversely associated with the presence of larynx cancer. Additionally, rs417309 AA genotype increased the risk of larynx cancer in the T1 stage, and the rs1640299 TG heterozygote occurred more frequently in the control group than those in the T3 and T4 stage. The rs417309 and rs1640299 polymorphisms of the DGCR8 gene as well as rs6877842 of the DROSHA gene might be associated with a risk of laryngeal cancer occurrence in the Polish population.

Association of Polymorphic Variants of miRNA Processing Genes with Larynx Cancer Risk in a Polish Population.

Laryngeal cancer (LC) is one of the most prevalent types of head and neck cancer. An increasing interest has been focused on the role of microRNA (miRNAs) in LC development. The study group consisted of 135 larynx cancer patients and 170 cancer-free individuals. Nine polymorphisms of pre-miRNA processing genes, DROSHA (rs6877842), DGCR8 (rs3757, rs417309, and rs1640299), RAN (rs14035), XPO5 (rs11077), DICER1 (rs13078 and rs3742330) and TARBP2 (rs784567), were performed by TaqMan SNP Genotyping Assay. It was found that the frequency of the GT and the TT polymorphic variants of XPO5 gene were higher in LC patients than in controls (p < 0.0001 and p = 0.000183, resp.). In turn, the frequency of the CT genotype of RAN gene was higher in controls than in LC patients (p < 0.0001). The TT and the AG of DICER1 gene (p = 0.034697 for rs13078 and p = 0.0004 for rs3742330) as well as the AG and the GG genotypes of TARBP2 gene (p = 0.008335 and p < 0.0001, resp.) were associated with higher risk of LC occurrence. Our data suggested that polymorphisms of miRNA processing genes might be useful as predictive factors for the LC development.

The -2518 A/G MCP-1 polymorphism as a risk factor of inflammatory bowel disease.

UNLABELLED: Inflammatory bowel diseases (IBD) are disorders originated from immune disturbances. The AIM OF THE STUDY was to evaluate the association between the -2518 A/G MCP-1 polymorphism and the risk of IBD development. MATERIAL AND METHODS: Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Study group consisted of 197 subjects with IBD (120 with ulcerative colitis and 77 with Crohn's disease) as well as 210 healthy controls. RESULTS: The presence of the -2518 G/G MCP-1 genotype in the investigated groups seems to be connected with higher risk of inflammatory bowel disease as well as Crohn's disease only (OR 2.26; 95% CI 1.44-3.54 and OR 2.08; 95% CI 1.21-3.46, respectively). CONCLUSIONS: Our data showed that the -2518 A/G MCP-1 polymorphism might be associated with the IBD occurrence and might be used as predictive factor of these diseases in a Polish population.

The lL-8 and IL-13 gene polymorphisms in inflammatory bowel disease and colorectal cancer.

Inflammatory bowel diseases (IBD) and colorectal cancer (CRC) are disorders that originate from immune disturbances. In our study, we evaluated the association between the -251 T/A interleukin (IL)-8 and the -1112 C/T IL-13 polymorphisms, the risk of IBD, and CRC development. Genotypes were determined by PCR-restriction fragment length polymorphism in 191 patients with CRC, 150 subjects with IBD, and 205 healthy controls. We found an association between CRC and the presence of the -251 TA genotype and A allele of the IL-8 gene (odds ratios [ORs] 2.28 and 1.65). A similar relationship was observed between these polymorphic variants and ulcerative colitis (OR 2.05 for the -251 TA genotype and OR 1.47 for the -251 A allele) as well as Crohn's disease (ORs 3.11 and 1.56, respectively). Our research also revealed that the CT and TT genotypes of the IL-13 -1112 C/T polymorphism may be connected with a higher risk of CRC (ORs 2.28 and 1.65). The same genotypes affected the susceptibility of IBD (ORs 2.26 and 3.72). Our data showed that the IL-8 -251 T/A and IL-13 -1112 C/T polymorphisms might be associated with the IBD and CRC occurrence and might be used as predictive factors of these diseases in a Polish population.

Evaluation of DNA double strand breaks repair efficiency in head and neck cancer.

Head and neck cancers (head and neck squamous cell carcinomas [HNSCC]) are a heterogeneous group of neoplasms with varying presenting symptoms, treatment, and expected outcome. There is a need to find an effective way of its treatment at the molecular level. Thus, we should identify the mechanism of cancer cell response to damaging agents' activity, especially at DNA level. Our major goal was to evaluate the efficacy of DNA double strand breaks (DSBs) repair in HTB-43 and SCC-25 cancer cell lines as well as lymphocytes taken from HNSCC patients and healthy donors. The DNA repair efficiency was measured by neutral comet assay as well as extrachromosomal assay for DNA DSBs repair (TAK assay). We determined the levels of two main pathways of DNA DSBs-nonhomologous end joining (NHEJ) and homologous recombination repair (HRR). Neutral comet assay was used for evaluation of DNA DSBs repair after treatment with genotoxic agents. DNA DSBs induced by gamma radiation were repaired slower in lymphocytes from HNSCC patients than in lymphocytes from healthy controls. HTB-43 and SCC-25 cancer cell lines have higher efficacy of NHEJ and HRR than lymphocytes taken from patients as well as control subjects. Our results confirm the necessity of further studies on the mechanisms of DNA DSBs repair to provide insight into the molecular basis of head and neck cancer, which will allow us to improve methods of HNSCC treatment.

Association of -1112 c/t promoter region polymorphism of the interleukin 13 gene with occurrence of colorectal cancer.

Colorectal carcinoma is one of the leading causes of death from cancer amongst adults. Considering its molecular background, cytokines are the key component of the inflammatory microenvironment of these tumors. Investigations that enable better understanding of colorectal cancer concerning the molecular level, may provide important tools for genetic screening of disease high-risk groups, as well as molecular diagnostics for the non-invasive detection of cancer in its early stages.THE AIM OF THE STUDY was to evaluate the association between colorectal cancer and the -1112 C/T single nucleotide polymorphism (SNP) of the interleukin-13 gene. MATERIAL AND METHODS. The study group comprised 150 cancer patients and 170 healthy subject genotypes from the Polish population. Analysis was performed by PCR-restriction fragment length polymorphism (PCR-RFLP). RESULTS. We showed that the CT genotype is connected with a higher risk of colon cancer occurrence (OR 2.51; 95% CI 1.57-4.02; p < 0.0001). We also correlated the polymorphic variants of the IL-13 gene with the clinical characteristics of colorectal cancer patients. We observed no association between the investigated polymorphism and colorectal cancer progression, evaluated by tumor stage, as well as lymph node metastasis. CONCLUSIONS. The presented study suggested the possibility of a connection between the IL-13 gene polymorphism (-1112 C/T) and colorectal cancer risk in the Polish population.

Polymorphisms of the XRCC3 C722T and the RAD51 G135C genes and the risk of head and neck cancer in a Polish population.

Genetic variations in DNA repair genes may affect an individual's susceptibility to head and neck cancer. We performed a case-control study to test the association between head and neck cancer risk and two polymorphisms: the C722T of the XRCC3 and the G135C of the RAD51-genes of DNA double strand break (DSB) repair by homologous recombination (HRR). Genotypes were determined by PCR-restriction fragment length polymorphism (PCR-RFLP). DNA was isolated from peripheral blood lymphocytes of a group of 288 patients consisting of 97 subjects with precancerous hyperplastic laryngeal lesions (PHLL) and 191 subjects with head and neck squamous cell carcinoma (HNSCC) as well as 353 healthy control donors. We found an association between PHLL and the 722CT (OR 6.67; 95% CI 3.02-14.74) as well as 722TT (OR 4.65; 95% CI 2.30-9.43) variants of the XRCC3 gene. Similar relation was observed between these genotypes and HNSCC (OR 2.59; 95% CI 1.61-4.16 and OR 5.54; 95% CI 3.22-9.52, respectively). Moreover, we also observed an association between PHLL (OR 6.04; 95% CI 3.69-9.90) and HNSCC (OR 6.04; 95% CI 3.69-9.90) and the 135GC variant of the RAD51 gene. The gene-gene interaction between XRCC3 and RAD51 polymorphic variants may contribute to higher prevalence of PHLL. The increased risk of this disease was observed in case of the combination of the 722CT/135GC (OR 3.81; 95% CI 1.55-9.75) as well as the 722TT/135GC genotypes (OR 5.33; 95% CI 1.96-14.47). The presence of the same genes combinations plays a part in higher probability of HNSCC occurrence (OR 2.42; 95% CI 1.22-4.79 for 722CT/135GC and OR 3.63; 95% CI 1.69-7.76 for 722TT/135GC). We also found an association between these XRCC3 or RAD51 polymorphic variants and smoking status in PHLL (ORs 2.85-10.28 and 1.82-7.35, respectively) and HNSCC patients (ORs 2.94-13.93 and 1.36-3.94, respectively) as well as alcohol intake among PHLL (ORs 3.44-6.12 and 3.52-8.43, respectively) and HNSCC subjects (ORs 2.71-7.01 and 2.33-4.62, respectively). In conclusion our data showed that the C722T and the G135C polymorphisms of the XRCC3 and the RAD51 genes might be associated with HNSCC. Finally we suggested that these polymorphisms might be used as predictive factor of precancerous lesion for head and neck cancer in a Polish population.

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.