Sperm concentration, hyaluronic acid-binding capacity, aneuploidy and persistent histones in testicular cancer.

STUDY QUESTION: Are the quantitative and qualitative characteristics of semen samples of patients with testicular cancer (TC), prior to anticancer therapy, different from infertile oligozoospermic (IO) and normozoospermic (NZ) age-matched men? SUMMARY ANSWER: Sperm concentration in TC patients was significantly decreased with no difference in estimated numerical chromosome aberrations and nuclear decondensation compared with NZ men, while the infertile, oligozoospermic men had significantly poorer sperm qualitative characteristics versus the TC group overall and oligozoospermic patients with TC. WHAT IS KNOWN ALREADY: Spermatogenesis is altered in TC patients at the time of diagnosis. However, the mechanism responsible for the decreased semen quantity in patients with TC is not well understood. Anticancer treatment may have gonadotoxic side effects and post-treatment fertility cannot be predicted. Before commencing anticancer treatment, cryopreservation may be suggested to preserve fertility but there are no data regarding the risk of genetic aberrations in these sperms. STUDY DESIGN, SIZE, DURATION: This is a cross-sectional study examining semen from 28 patients with TC, 20 IO and 20 NZ age-matched men attending the Andrology Center and the Sperm Cryopreservation Laboratory of the Medical and Health Science Center, University of Debrecen. Semen samples from patients with TC were collected after orchidectomy, but prior to anticancer treatment. Semen samples from TC patients recruited over a period of 4 years were studied. Based on their sperm concentration, TC patients were subgrouped into an oligozoospermic TC (TCO) and a normozoospermic TC group. For statistical analysis, the normal group (NZ + IO) comprised non-tumorous NZ and IO men. PARTICIPANTS/MATERIALS/SETTING, METHOD: The ejaculates were assessed as per World Health Organization guidelines. Hyaluronic acid (HA)-binding capacity was the functional test. To determine the numerical chromosome aberrations, we used multi-color fluorescence in situ hybridization. Aniline blue (AB) staining was performed as a nuclear decondensation marker test. MAIN RESULTS AND THE ROLE OF CHANCE: The results did not reveal any significant difference in disomy of sex chromosomes and chromosome 17, diploidy and estimated numerical chromosome aberrations and AB staining results upon comparing the NZ and TC groups, although the sperm concentration (P < 0.001) and HA-binding capacity (P < 0.001) were lower in the TC group. Estimated numerical chromosome aberrations (P < 0.001), AB staining (P < 0.001) and HA-binding capacity (P = 0.019) were lower in the infertile, oligozoospermic group when compared with the patients with TC. The TCO group had significantly better results in every examined parameter than the infertile, oligozoospermic group. In the non-tumorous control group (NZ + IO), a significant (P < 0.001) correlation (Spearman's rho = r) was found between sperm concentration and aneuploidy rate (r = -0.642), AB staining (r = -0.876) and HA binding (r = 0.842); the HA-binding capacity was related to the aneuploidy rate (r = -0.678) and the AB staining (r = -0.811); and there was significant correlation between aneuploidy and AB staining (r = 0.559). In the TC group, apart from the negative correlation between sperm concentration and estimated chromosomal aberrations (r = -0.642), no other correlations were observed. LIMITATIONS, REASONS FOR CAUTION: Data on confounders influencing sperm characteristics, such as smoking, occupational or environmental hazards, alcoholism, co-morbidities and other andrological conditions, were not collected. WIDER IMPLICATIONS OF THE FINDINGS: This is the first study to demonstrate that sperm qualitative characteristics in anticancer therapy naïve oligozoospermic TC patients differ significantly from those in IO men and do not differ from those in NZ men. Our results need to be validated in similar groups of men and in other patient groups with cancer where cryopreservation is advisable. STUDY FUNDING/COMPETING INTERESTS: This research was supported by the European Union and the State of Hungary, co-financed by the European Social Fund in the framework of TÁMOP-4.2.4.A/2-11/1-2012-0001 'National Excellence Program'. The authors have no conflict of interest to declare.

Determinants of COVID-19 vaccination intention in Central and Eastern Europe: A cross-sectional study in Poland, Romania, and Slovenia.

BACKGROUND: Identifying predictors of vaccination intention is critical to developing appropriate programs and campaigns targeting groups reluctant to be vaccinated. This study aimed to identify the determinants of vaccination intention at the beginning of the COVID-19 pandemic in three Central and Eastern European (CEE) countries: Poland, Romania, and Slovenia. METHODS: In this cross-sectional study, a sample of unvaccinated 1723 Poles, Romanians, and Slovenians completed an online survey (April 2021). Questions included measures of vaccination intention, attitudes towards vaccines, conspiracy mindset, preference for a type of vaccine, and trust in information sources. RESULTS: The results showed that mistrust of vaccine benefits and concerns about commercial profiteering negatively predicted vaccination intention. Conversely, trust in information from medical professionals and scientists, official sources, and traditional media was positively related to vaccination intention, while trust in digital media was negatively related to vaccination intention. In addition, preference for mRNA vaccine type was a positive significant predictor of vaccination intention. The differences between countries are discussed. CONCLUSIONS: The study results deliver suggestions for developing appropriate vaccine uptake programs and campaigns that should consider presenting the positive outcomes of vaccines via official sources and traditional media based on scientific evidence and medical professionals' knowledge.

Anti-cytokine autoantibodies preceding onset of autoimmune polyendocrine syndrome type I features in early childhood.

PURPOSE: Almost all patients with autoimmune polyendocrine syndrome (APS)-I have high titer neutralizing autoantibodies to type I interferons (IFN), especially IFN-ω and IFN-α2, whatever their clinical features and onset-ages. About 90 % also have antibodies to interleukin (IL)-17A, IL-17F and/or IL-22; they correlate with the chronic mucocutaneous candidiasis (CMC) that affects ~90 % of patients. Our aim was to explore how early the manifestations and endocrine and cytokine autoantibodies appear in young APS-I patients. That may hold clues to very early events in the autoimmunization process in these patients. METHODS: Clinical investigations and autoantibody measurements in 13 APS-I patients sampled before age 7 years, and 3 pre-symptomatic siblings with AIRE-mutations in both alleles. RESULTS: Antibody titers were already high against IFN-α2 and IFN-ω at age 6 months in one sibling-8 months before onset of APS-I-and also against IL-22 at 7 months in another (still unaffected at age 5 years). In 12 of the 13 APS-I patients, antibody levels were high against IFN-ω and/or IL-22 when first tested, but only modestly positive against IFN-ω in one patient who had only hypo-parathyroidism. Endocrine organ-specific antibodies were present at age 6 months in one sibling, and as early as 36 and 48 months in two of the six informative subjects. CONCLUSION: This is the first study to collate the onset of clinical features, cytokine and endocrine autoantibodies in APS-I infants and siblings. The highly restricted early autoantibody responses and clinical features they show are not easily explained by mere loss of broad-specific self-tolerance inducing mechanisms, but hint at some more sharply focused early event(s) in autoimmunization.

The future of primary paediatric care in Europe: reflections and Report of the EPA/UNEPSA Committee.

BACKGROUND: Changes in the scope of the field of paediatrics and the variability in primary paediatric care (PPC) and practice throughout Europe motivated the European Paediatric Association and Union of National European Paediatric Societies and Associations (EPA/UNEPSA) to establish a working group to discuss definitions of paediatric coverage in terms of age limits, find common denominators in the provision of PPC and examine the challenges and goals of 21st century paediatrics relevant to the continent. These issues were presented at the 2008 Europaediatrics in Istanbul, where a consensus declaration was drawn up and accepted by the EPA/UNEPSA Executive Committee. AIM: To present an outline of the essential elements of the 2008 EPA/UNEPSA Executive Committee consensus declaration. CONCLUSION: The definition of basic characteristics and the establishment of requirements for optimal PPC and practice are important steps in overcoming the differences among European countries and pave the way for an acceptable formulation of standardized high-quality paediatric medical care in Europe.

The BOADICEA model of genetic susceptibility to breast and ovarian cancers: updates and extensions.

Multiple genetic loci confer susceptibility to breast and ovarian cancers. We have previously developed a model (BOADICEA) under which susceptibility to breast cancer is explained by mutations in BRCA1 and BRCA2, as well as by the joint multiplicative effects of many genes (polygenic component). We have now updated BOADICEA using additional family data from two UK population-based studies of breast cancer and family data from BRCA1 and BRCA2 carriers identified by 22 population-based studies of breast or ovarian cancer. The combined data set includes 2785 families (301 BRCA1 positive and 236 BRCA2 positive). Incidences were smoothed using locally weighted regression techniques to avoid large variations between adjacent intervals. A birth cohort effect on the cancer risks was implemented, whereby each individual was assumed to develop cancer according to calendar period-specific incidences. The fitted model predicts that the average breast cancer risks in carriers increase in more recent birth cohorts. For example, the average cumulative breast cancer risk to age 70 years among BRCA1 carriers is 50% for women born in 1920-1929 and 58% among women born after 1950. The model was further extended to take into account the risks of male breast, prostate and pancreatic cancer, and to allow for the risk of multiple cancers. BOADICEA can be used to predict carrier probabilities and cancer risks to individuals with any family history, and has been implemented in a user-friendly Web-based program (http://www.srl.cam.ac.uk/genepi/boadicea/boadicea_home.html).

Diagnostic significance of HLA-DQ typing in patients with previous coeliac disease diagnosis based on histology alone.

BACKGROUND: Coeliac disease is strongly associated with human leukocyte antigen (HLA)-DQ2 or DQ8 genotypes. The diagnosis is based on demonstrating crypt-hyperplastic villous atrophy, endomysial or transglutaminase antibodies and correlation of disease activity with gluten intake. AIM: To evaluate the clinical utility of HLA-DQ typing, when coeliac disease diagnosis had previously been established solely by histology. METHODS: HLA-DQ alleles, endomysial and transglutaminase antibodies were investigated and histology slides reviewed in 70 patients diagnosed 2-25 years earlier by small-intestinal biopsy but without measuring endomysial or transglutaminase antibodies. Patients without DQ2 or DQ8 or without unequivocal villous atrophy were followed-up on free diet by using serology and biopsies. RESULTS: All 40 endomysial/transglutaminase antibodies positive patients carried DQ2 or DQ8, and 39 of them had severe villous atrophy. Only 56% of patients without endomysial or transglutaminase antibodies positivity had DQ2 or DQ8 (P < 0.001). Seropositivity and relapse developed in 4 of 11 DQ2 positive but in none of 15 DQ2 and DQ8 negative patients on long-term gluten exposure. CONCLUSIONS: Coeliac disease diagnosis based solely on histology is not always reliable. HLA-DQ typing is important in identifying DQ2 and DQ8 negative subjects who need revision of their diagnosis, but it does not have additive diagnostic value if endomysial positivity is already known.

Breast and ovarian cancer risks to carriers of the BRCA1 5382insC and 185delAG and BRCA2 6174delT mutations: a combined analysis of 22 population based studies.

A recent report estimated the breast cancer risks in carriers of the three Ashkenazi founder mutations to be higher than previously published estimates derived from population based studies. In an attempt to confirm this, the breast and ovarian cancer risks associated with the three Ashkenazi founder mutations were estimated using families included in a previous meta-analysis of populatrion based studies. The estimated breast cancer risks for each of the founder BRCA1 and BRCA2 mutations were similar to the corresponding estimates based on all BRCA1 or BRCA2 mutations in the meta-analysis. These estimates appear to be consistent with the observed prevalence of the mutations in the Ashkenazi Jewish population.

Significance of purine salvage in circumventing the action of antimetabolites in rat hepatoma cells.

The flux activities of de novo and salvage purine synthesis were compared in rat hepatoma 3924A cells in various growth phases. The initial rate assays of [14C]adenine, [14C]hypoxanthine, and [14C]guanine incorporation yielded Michaelis-Menten kinetics with Kms of 5, 7, and 7 microM, respectively. After replating plateau phase cells in lag and log phases the activity of purine de novo pathway increased 4.5- to 8-fold with a preferential rise in guanylate synthesis, whereas purine salvage activities increased only 1.6- to 2.1-fold. However, for the syntheses of IMP, AMP, and GMP, the activities of purine salvage pathways were 2- to 7-fold, 5- to 28-fold, and 2- to 32-fold higher than those of the de novo purine pathway. Treatment of cells with acivicin, an inhibitor of the activity of amidophosphoribosyltransferase, phosphoribosylformylglycinamidine synthase, and GMP synthase, inhibited the flux activities of de novo purine, adenylate, and guanylate syntheses to 37, 73, and 3% of the controls and decreased the concentration of GTP to 42%; the concentration of ATP did not change and that of 5-phosphoribosyl 1-pyrophosphate increased 3.1-fold. Under these conditions the activities of salvage synthesis from hypoxanthine and guanine were enhanced 2.5-fold. Treatment of hepatoma cells with IMP dehydrogenase inhibitors, tiazofurin, ribavirin, and 4-carbamoylimidazolium 5-olate, to block de novo guanylate synthesis accelerated the flux activity of guanine salvage pathway. The higher capacity of purine salvage pathway than that of the de novo one and the further rise of the activity in response to the drugs targeted against the de novo pathway highlight the important role salvage synthesis might play in circumventing the impact of antimetabolites of de novo purine synthesis in cancer chemotherapy.

Effects of some sugar alcohol derivatives on mutation and induction of sister chromatid exchanges.

The mutagenicity of various alkylating sugar alcohol derivatives in the Salmonella-microsome assay was studied, and the effects of these compounds on the colony-forming ability and the frequency of sister chromatid exchange (SCE) in Chinese hamster cells were determined. Cytostatic drugs under clinical trial [Elobromol (DBD), Myelobromol (DBM), Lycurim (LY), Zitostop (ZI)], others in preclinical analysis [dianhydrogalactitol (DAG), 3,4-diacetyldianhydrogalactitol (DiacDAG), 3,4-disuccinyldianhydrogalactitol (DisuDAG)], and compounds without any known antitumor effect in transplantable tumors [1-bromo-3,6-anhydrodulcitol (BAD), 1,2-epoxi-3,6-anhydrodulcitol (EAD)] were examined. All the tested compounds except DisuDAG were directly mutagenic in Salmonella strains TA 1535 and TA 100. The mutagenic effect of the chemicals was not influenced by S9 mix from rat liver, with the exception of ZI and DiacDAG. DisuDAG appeared nonmutagenic in strains TA 1535 and TA 100 exposed to microsomal enzymes from rat liver, lung, and kidney and mouse and hamster liver, nor was DisuDAG mutagenic in strains TA 1537, TA 1538, and TA 98 in either the presence or the absence of rat liver S9 mix. Mouse urine, after a single administration of DisuDAG to the animal, proved to be mutagenic in strain TA 1535. This effect can be attributed to the presence of DAG and EAD which could be identified by thin-layer chromatography of urine, thus establishing the premutagenic character of DisuDAG. All sugar alcohol derivatives increased the frequency of SCE. Doses required to double the control SCE frequency were in the sublethal range of the survival curve for DBD, DBM, LY, DAG, and DiacDAG. Doses higher than the sublethal ones were required of ZI, DisuDAG, BAD, and EAD to achieve a 2-fold increase in SCE frequency. On the basis of these doses, the relative potencies for SCE induction of the compounds were as follows: EAD less than BAD less than DisuDAG less than ZI less than DiacDAG less than DAG less than DBD less than DBM less than LY. Within this range, there was a 2 million-fold difference in the SCE production of these chemically related compounds.

High frequency of germ-line BRCA2 mutations among Hungarian male breast cancer patients without family history.

To determine the contribution of BRCA1 and BRCA2 mutations to the pathogenesis of male breast cancer in Hungary, the country with the highest male breast cancer mortality rates in continental Europe, a series of 18 male breast cancer patients and three patients with gynecomastia was analyzed for germ-line mutations in both BRCA1 and BRCA2. Although no germ-line BRCA1 mutation was observed, 6 of the 18 male breast cancer cases (33%) carried truncating mutations in the BRCA2 gene. Unexpectedly, none of them reported a family history for breast/ovarian cancer. Four of six truncating mutations were novel, and two mutations were recurrent. Four patients (22%) had a family history of breast/ovarian cancer in at least one first- or second-degree relative; however, no BRCA2 mutation was identified among them. No mutation was identified in either of the genes in the gynecomastias. These results provide evidence for a strong genetic component of male breast cancer in Hungary.

Consortium study on 1280 breast carcinomas: allelic loss on chromosome 17 targets subregions associated with family history and clinical parameters.

The pattern of loss of heterozygosity (LOH) on chromosome 17 in human breast cancer is complicated and shows many different regions of loss. In an attempt to narrow down the relevant regions of LOH on chromosome 17, we have studied the deletion pattern and its association with clinical parameters in 1280 breast carcinoma-venous blood lymphocyte pairs. In total, 42 different chromosome 17 loci were investigated, and between 25 and 625 cases were analyzed at each locus. The frequency of LOH observed on the p arm was much higher than that observed on the q arm. The opposite effect was observed in 52 ovarian cancer cases investigated, with less LOH on 17p than on 17q. Patterns of loss consistent with interstitial and terminal deletions, as well as loss of either the p or q arm or monosomy 17 were observed. To determine whether loss at particular loci may be associated with biological features of breast tumors, clinical data including age of onset, family history of breast cancer, tumor histopathology, tumor size, estrogen receptor (ER) status, and occurrence of lymph node or distant metastases were collected for each case. Overall, large-sized, ER-negative, lymph node-positive ductal tumors showed the highest frequencies of LOH, with ER-negative and ductal tumors showing LOH for markers along the majority of the chromosome. Eight regions of chromosome 17 appear to be associated with human breast cancer, two on 17p and six on 17q. These regions were not necessarily in the areas exhibiting the highest frequencies of LOH but were defined by interstitial and terminal deletions in multiple independent cases. Seven of these regions showed statistically significant differences in LOH associated with clinical parameters. These data strongly suggest that loci on chromosome 17 may determine aspects of tumor presentation and disease behavior in human breast cancer and pinpoint candidate tumor suppressor gene loci.

Founder BRCA1 mutations and two novel germline BRCA2 mutations in breast and/or ovarian cancer families from North-Eastern Poland.

Germline mutations in the BRCA1 and BRCA2 genes account for the majority of high-risk breast/ovarian cancer families, depending on the population studied. Previously, BRCA1 mutations were described in women from Western Poland. To further characterize the spectrum of BRCA1 mutations and the impact of BRCA2 mutations in Poland, we have analyzed 25 high-risk breast and/or ovarian cancer families from North-Eastern Poland for mutations in all coding exons of the BRCA1 and BRCA2 genes, using combined heteroduplex analysis/SSCP followed by direct DNA sequence analysis. Out of 25 probands a total of five (20%) carried three recurrent BRCA1 mutations (300T>G, 3819del5, 5382insC). The 300T>G mutation accounted for 60% (3/5) of BRCA1 mutations and allelotyping suggested a common founder of this mutation. No unique mutations were found. In addition, we identified three BRCA2 (12%) mutations, one recurrent 4075delGT, and two novel frameshift mutations, 7327ins/dupl19 and 9068delA. We conclude that 30% of high-risk families from North-Eastern Poland may be due to recurrent BRCA1 and unique BRCA2 mutations. Intriguingly, the BRCA1 mutation spectrum seems to be different within subregions of Poland.

Frequent methylation of p16INK4A and p14ARF genes implicated in the evolution of chronic myeloid leukaemia from its chronic to accelerated phase.

The frequency and mechanism of p16(INK4A) and p14(ARF) gene alterations were studied in cell samples from 30 patients with Philadelphia (Ph) chromosome-positive chronic myeloid leukaemia (CML), both at diagnosis and at the onset of the accelerated phase (AP) of the disease. No alterations in the p16(INK4A) or p14(ARF) genes were found in any of the chronic phase (CP) samples. DNA sequencing analyses detected p16(INK4A) or p14(ARF) mutations in 17 AP samples. All mutations were heterozygous without loss of the other allele. Aberrant methylation of the p16(INK4A) or p14(ARF) promoters was found in 14 of 30 AP samples. The most common situation was the simultaneous methylation of both promoters. Our data indicate that p16(INK4A) and p14(ARF) are primary targets for inactivation by promoter methylation in the acceleration of CML. Transcriptional silencing of the p16(INK4A) and p14(ARF) genes may be important in the conversion of CML from the CP to the AP.

Sequence alterations can mask each other's presence during screening with SSCP or heteroduplex analysis: BRCA genes as examples.

For mutation detection, various screening techniques are widely used because DNA sequencing, the gold-standard method, is still considered to be expensive and laborious for high-throughput screening. Single-strand conformation polymorphism (SSCP) analysis, heteroduplex analysis (HA) and their variant techniques are popular and frequently used for this purpose. It is widely accepted that when searching for unknown sequence variations, any revealed distinct pattern should always be sequenced. We give examples here of the BRCA1 and BRCA2 genes where the SSCP/HA techniques can produce ambiguous predictions if used to detect known genetic variants compared to positive controls. Using direct DNA sequencing, we provide evidence that in such cases, mutations or polymorphisms can mask each other's presence. This phenomenon can often influence the results of any DNA testing because genetic variations such as single-nucleotide polymorphisms occur frequently in the human genome. We suggest that even in the case of known electrophoretic patterns of well-characterized genetic alterations, every sequence alteration should be confirmed by direct DNA sequencing, especially if genetic testing is carried out for diagnostic purposes.

Co-expression of c-abl and c-myb oncogenes in Philadelphia chromosome-negative, bcr-negative chronic myeloid leukaemia.

Three cases of Philadelphia (Ph) chromosome-negative, bcr-negative chronic myeloid leukaemia (CML) have been investigated for oncogene expression by Northern blot and cytoplasmic RNA dot blot hybridization. Considerably high levels of expression of c-abl and c-myb were observed in all cases. In the Ph-negative cells the normal 6.0 and 7.0 kb c-abl and 3.8 kb c-myb transcripts were found. No amplification of c-abl or c-myb oncogenes was detected in the DNAs of Ph-negative CML cells. Data suggest that co-operation between the overexpressed c-abl and c-myb oncogenes is causally related to Ph-negative bcr-negative CML.

Allele loss of tumour suppressor genes on chromosome 17 in human testicular germ cell tumours.

The molecular genetics of testicular germ cell tumours (TGCT) are still largely unknown. We investigated 20 TGCT tumours for allelic losses (LOH) of tumour supressor genes BRCA1, TP53 and of THRA1 on chromosome 17. We observed an overall loss of 50% for the whole chromosome. Detailed deletion mapping revealed no losses for the BRCA1 gene, 42% LOH for THRA1 and 11% allelic loss for the region telomeric to BRCA1. We observed 11% LOH for TP53. Our results suggest that allelic losses of BRCA1 and TP53 genes do not play a pivotal role in TGCT but that dysfunction of THRA1 or tumour suppressor gene(s) in this region may have an impact in the development of this cancer.

Allelic imbalance and microsatellite instability in BRCA1 associated breast and ovarian tumors.

We have investigated the involvement of microsatellite instability (MSI) and allelic imbalance (AI) at chromosome 13q and 17 in 41 breast and 41 ovarian carcinomas and their association with BRCA1 and BRCA2 gene mutations. MSI was detected in 20% of ovarian and 7% of breast tumors. AI at the BRCA1 locus was detected in 59% and 32% of ovarian and breast tumors, respectively. At the BRCA2 locus, AI rates were 49% and 44% for ovarian and breast tumors, respectively. Germline BRCA1 mutations, identified in 5 (12%) ovarian tumors and in one (2%) breast tumor were not associated with MSI. In only 2/5 BRCA1 positive tumors loss of the wild-type allele was observed. We conclude that BRCA1 mutation status is not associated with MSI and that MSI found in a fraction of ovarian tumors may reflect possible mutations in one of the DNA mismatch repair genes.

Expression of key enzymes of purine and pyrimidine metabolism in a hepatocyte-derived cell line at different phases of the growth cycle.

The effect of growth phase on enzymatic activities of the de novo and salvage pathways for purine and pyrimidine nucleotide synthesis was studied in a hepatocyte-derived cell line from the rat. The cells were in lag phase after plating for 36 h; log phase started at 48 h and persisted up to 120 h of culture. Then the cells stopped growing and entered into plateau phase (144 h). In non-proliferating cells (144 h of culture) the basal activities of the enzymes of purine de novo biosynthesis were 1.7- to 6.8-fold higher than in normal rat liver, those of pyrimidine de novo synthesis showed 0.6- to 30-fold increase in activity. The purine salvage enzymes were unchanged, and the pyrimidine salvage enzymes were 3.1- to 7.4-fold higher compared to normal liver. During the growth cycle all enzymes except the purine salvage enzymes, which did not change, showed a peak in activity at 72 h of culture (log phase). The increase in activity in log phase compared to plateau phase was 1.3- to 2.4-fold for purine de novo synthetic enzymes, 1.1- to 2.4-fold for pyrimidine de novo enzymes, and 1.4- to 4.7-fold for pyrimidine salvage enzymes. The specific activities of the enzymes in exponentially growing cells were comparable either to that in 24-h regenerating liver, or to that in hepatomas of low or medium growth rate. It was concluded that the enzymatic pattern and metabolic state of the cells shared some features with regenerating liver, others with tumors, although they were not tumorigenic after transplantation into athymic nude mice.

Carcinogenicity and genotoxicity of the herbicide 2,4,5-trichlorophenoxyethanol (TCPE) contaminated with dioxin.

In an earlier study 2,4,5-trichlorophenoxythanol (TCPE) contaminated with dioxin, a component of the Hungarian herbicide Buvinol, was found to be hepatocarcinogenic. In the present work, the hepatocarcinogenicity of TCPE was compared to its possible genotoxicity in vitro, using the Salmonella/microsome test for mutagenicity and for its DNA-damaging effect, the induction of sister chromatid exchanges (SCE) in Chinese hamster cells in vitro. It was found that purified TCPE (with 0.1 ppm dioxin content) was under no conditions mutagenic by the Ames test, i.e., it belongs to the group of false-negative chemicals. TCPE was, however, genotoxic; its DNA-damaging effect was demonstrated by an increase in the frequency of SCE, while pure dioxin of corresponding amount was ineffective. However, elevated SCE frequency and the toxicity on bacteria and mammalian cells by TCPE were significantly decreased by the metabolic activation system (S-9 mix) isolated from liver. This observation indicates that in the detoxication of TCPE in vitro, a key role is to be attributed to the hepatic microsomal enzymes. It is presumed that TCPE is hepatocarcinogenic only in a dose range which has exhausted the detoxicating capacity of the liver.