Current trends and perspectives in nutrition and cancer prevention.

There is an increasing evidence that dietary phytochemicals may play important roles as chemopreventive or chemotherapeutic agents in prevention of many diseases, including tumors. The purpose of this study was to examine antimutagenic effects and effect on the immune response of representative series of substances which commonly occur in human diet. Using the Ames bacterial mutagenicity test and in vivo chemiluminescence test, we investigated antigenotoxic and immunomodulatory effects of juices and vegetable homogenates (carrot + cauliflower, cauliflower, red cabbage, broccoli, onion, garlic) on the genotoxicity of AFB1 and pyrolysates of aminoacids. Using the Ames test and in vivo micronucleus, the chemiluminescence test, the blastic transformation test and the comet assay we examined antimutagenic effects of chemically identified chemoprotective substances in the pure form (resveratrol, diallylsulphide, phenethyl isothiocyanate, ellagic acid, epigallocatechin gallate, genistein and curcumin) on mutagenicity induced by three reference mutagens: aflatoxin B1 (AFB1), 2-amino-3-metylimidazo[4,5,-f] chinolin (IQ) and N-nitroso- N-metylurea (MNU) and effect of phytochemicals on the immunosuppression caused by these mutagens. All complete vegetable homogenates and substances of plant origin tested, showed a clear antimutagenic and immunomodulatory activities on mutagenicity and immunosuppression induced by reference mutagens. Only in the Ames test the effect of some phytochemicals against direct mutagen MNU was lower compared to indirect mutagens AFB1 and IQ. Similarly, resveratrol and epigallocatechin gallate had no inhibitory effect on mutagenicity MNU in the Ames test.

[Genomic imprinting and human pathology]. / Imprinting genu a lidské patologie.

Genomic imprinting is an epigenetic form of regulation of gene expression. Imprinted genes are transcribed from one allele of specific parental origin. Such genes are normally involved in embryonic growth and behavioral development. Deregulation of imprinted genes has been observed in a number of human diseases as gestation trophoblastic disease, Prader-Willi, Angelmann and Beckwith-Wiedemann syndromes and plays significant role in the carcinogenesis. Review of recent knowledge on mechanism and regulation of imprinting is presented in this paper.

[Prenatal cytogenetic diagnosis at the Department of Medical Genetics GENNET-Klimentská]. / Prenatální cytogenetická diagnostika na oddelení lékarské genetiky GENNET--Klimentská.

OBJECTIVE: Analysis of data from prenatal cytogenetic studies performed during 10 years. DESIGN: Retrospective analysis of cytogenetic results. SETTING: Cytogenetic laboratory, Department of Clinical Genetics GENNET, Prague. METHODS: Cytogenetic analysis of cultivated amniotic cells. RESULTS: 180 chromosomal pathologies, including 110 numerical and 70 structural, were diagnosed in 5743 samples of amniotic fluid. Relatively high number of structural aberrations was found also in groups of patients examined because of increased maternal age, abnormal values of biochemical markers and abnormal ultrasound findings. Chromosomal abnormalities in individual groups of patients, risk figures for de novo balanced structural aberrations, additional marker chromosomes and some mosaic findings as the management following the prenatal diagnosis of this abnormalities are discussed. CONCLUSION: On the basis of the great number of familiar structural aberrations in our material is recommended to pay attention to the detection of such anomalies also in groups of patients where numerical chromosomal changes are namely expected.

[Screening for Down's syndrome: results at the Klimentská Polyclinic Screening Center 1992-1994]. / Screening Downova syndromu: výsledky screeningového centra polikliniky klimentská v letech 1992-1994.

Between January 1992 and March 1994 in Klimentska Screening Centre 635 second trimester amniocenteses were performed because of the risk of a chromosomal aberration. 416 (66 per cent) procedures were recommended because of the mother's age over 35 years and 219 ones (34 per cent) because of a positive screening test. Maternal serum alpha-fetoprotein and human chorionic gonadotrophin were used as screening markers in most cases. Five trisomy 21 cases in the advanced age group were detected. Serum markers were assessed in three older mothers with an affected foetus after amniocentesis. All were ex post screen positive. Three trisomy 21 foetuses of mothers younger than 35 years were detected in the screen positive group. Recent advances in screening for Down's syndrome and other congenital defects are discussed.

[Recent advances in clinical cytogenetics]. / Novinky v klinické cytogenetice.

The development of cytogenetics in recent years revealed some new and even surprising findings some of which seem to be at variance with accepted rules of this discipline. The submitted paper gives a review of contemporary knowledge of the problem of imprinting, somatic mosaicism, micro-deletion syndromes, unbalanced aberrations without phenotypic manifestations and it mentions also some aspects of fragile X.

The possible mutagenic effect of the occupation of TV announcer.

In a group of TV announcers, a significant increase in the number of classical aberrations was detected in peripheral blood: 7.5 +/- 3.477% in comparison with 3 control groups (A - 7 healthy women matched for sex, age and place of residence, B - 9 members of TV technical staff, C - 9 actors and actresses) with a mean aberration level of 2.96 +/- 1.136. SCE numbers were not increased in the TV announcers compared to controls. An increased frequency of reproduction failure has also been noticed in TV announcers (females). A decrease in the level of aberrant cells was noticed when the announcer had been on holiday, although this was not statistically significant. The possible mutagens in the working environment of TV announcers are discussed; there is a suspicion that azodyes, present in cosmetics or other chemicals, may be the mutagenic factor.

Effect of environmental factors on induced chromosomal aberrations in newborns.

Repeated blood collection was performed in newborns living in 3 distinct areas of the country with different levels of chemical pollution in the environment. Both the classical and SCE techniques were used in parallel. Blood samples from mothers and 1-year-old infants in the same area were also analysed to compare age-dependent sensitivity to mutagens. Cells with classical aberrations increased significantly according to higher chemical pollution, the levels of SCEs were not significantly changed. No age-dependent difference in sensitivity to chemical mutagens was found.

Terminal deletion with stable acentric fragment of 1q in a child with congenital malformations.

The terminal deletion with stable acentric fragment of 1q was found in a girl with multiple congenital malformations and severe mental retardation. The karyotype of both parents was normal, and the aberration appears de novo. The medium did not influence the expression of the aberration.

Chromosomal aberrations and sister-chromatid exchanges (SCEs) in patients undergoing long-term Imuran therapy.

13 patients treated daily for an extended time with Imuran and prednisone and 4 patients treated in the same way with Imuran only were cytogenetically analysed for the induction of structural chromosomal aberrations and SCEs. There was an increase in the number of aberrations and SCEs in nearly all patients analysed. However, we did not find any dose-dependent cumulative effect on chromosomal damage, with the exception of 1 patient tested in a small group of 4 patients involved in a prospective cytogenetic study, who showed a significant time-dependent increase in the number of aberrations.

Chromosomal aberrations and SCE in lymphocytes of children revaccinated against smallpox.

Chromosomal changes were analysed in the peripheral lymphocytes of 14 twelve-year-old children before and 3 months and 10 months after smallpox revaccination (group A), and in peripheral lymphocytes of 8 children of the same age before and 1.5 and 8 months after revaccination (group B). A significantly increased number of aberrant cells was found after 1.5 and 3 months. In the blood samples collected 8 and 10 months after revaccination there was a decrease in the number of aberrant cells which, however, did not reach the control level. Sister chromatid exchanges (SCE) were counted in 5 children 1.5 and 8 months after revaccination, and their numbers did not differ from controls.

The Prader-Willi syndrome with a 15/3 translocation.

A de novo translocation of 15q to 3p with complete monosomy of 15p and partial monosomy of 15q was detected by trypsin banding on peripheral lymphocytes of a 5-year-old boy with Prader-Willi syndrome (severe mental retardation, dyslalia, cryptorchidism, and muscular hypotonia). The pathogenic role of chromosome 15 abnormalities in the aetiology of this syndrome is discussed.

Mutagenic effect of epichlorohydrin. II. Analysis of chromosomal aberrations in lymphocytes of persons occupationally exposed to epichlorohydrin.

A prospective cytogenetic study was conducted in 35 workers occupationally exposed to epichlorohydrin (ECHH). Blood samples for cytogenetic analysis were collected before the exposure (to serve as a control) and after the first and second years of ECHH exposure; the cultivation time was 56--58 h. Four slides from each worker were prepared, coded and two of them separately analysed in two collaborating cytogenetic laboratories. About 50 cells were analysed on each slide, giving a total 16,674 scored cells. The percentage of cells with chromosomal aberrations in blood samples of workers was 1.37 before exposure, 1.91 after the first year and 2.69 after the second year of exposure. The difference between percentages of aberrant cells before and after two years of occupational exposure was highly significant (P less than 0.0001). There was particularly observed an increase of chromatid and chomosomal breaks after exposure, simultaneously with an increased number of breaks per 100 cells. These results are concordant with previously reported cytogenetic data found in experiments with mammals and human cells in vitro.