Effect of SUMO Modification on the Chromosomal Aneuploidy in Oocytes / 中国医学科学院学报

The chromosomal aneuploidy in oocytes is one of main causes of abortion and neonatal birth defects.It is mainly due to the premature separation of sister chromatid caused by the loss of Cohesin protein complex and the non-disjunction sister chromatids caused by abnormal microtubule dynamics aneuploidy.As a pathway of protein post-translational modification,SUMO modification(or SUMOylation)involves many physiological regulation processes including cell proliferation,differentiation,apoptosis,and cycle regulation.In the oocytes,SUMOylation can regulate the localization of Cohesin protein complex on the chromosome to affect the chromosomal aneuploidy in oocytes caused by premature separation of sister chromatid.On the other hand,SUMOylation can regulate the microtubule dynamics to affect the chromosomal aneuploidy in oocytes caused by non-disjunction sister chromatids.Therefore,SUMOylation plays an important role in regulating the chromosomal aneuploidy of oocytes;the exact mechanisms via which the SUMOylated substrates affect aneuploidy in oocytes remain unclear.This articles reviews the roles of SUMOylation in premature separation and non-isolated chromatid aneuploidy in oocyte from the effects of SUMOylationon Cohesin protein complex and microtubule dynamics.

Cytogenetic diagnosis of Roberts SC phocomelia syndrome: first report from Kashmir

There are several syndromes in which specific mitotic chromosomal abnormalities can be seen, like premature centromere separation, premature [sister] chromatid separation, and somatic aneuploidies. Identifications of such specific cytogenetic findings can be the key factor that leads towards the diagnosis of syndromes like Roberts SC phocomelia. The case presented here as Roberts SC phocomelia syndrome was identified as a child with multiple congenital anomalies and dysmorphic features. Conventional cytogenetic analysis of the case revealed premature sister chromatid separation. The premature centromeric separation was also confirmed by C banding analysis of the child. It is the first and the only case of Roberts SC phocomelia diagnosed from this part of the world. The present case report emphasizes the importance of conventional cytogenetics in the diagnosis of such syndromes

Chromosomal aberrations among Filipino health workers at the chemotherapy oncology wards/clinics of a tertiary government hospital

INTRODUCTION: Chromosomal mutations are casual events in neoplasia development. Biomarker cytogenetic assays can determine exposure to mutagenic agents in occupational settings. This study assessed early biological marker chromosomal aberrations among health workers in the chemotheraphy oncology wards/ clinics, exploring its association to the subjects' occupational, environmental and baseline profile.METHODS: This was an IRB approved cross-sectional exploratory study among hospital personnel working in the chemotherapy oncology facility of a tertiary government hospital, who underwent structured interview and blood extraction for cytogenetic assay after informed consent. Study funds only permitted assay of 44 specimens of 144 planned sample size, hence, Stata 6.0 only analyzed data from 44 subjects.RESULTS: All 44 subjects had varying exposure to chemotherapy drug infusions. Of these, 79% had 1.0 breaks per cell (hypersensitive). Predominantly chromatid breaks (CTB), chromatid gaps (CTG), sister chromatid exhanges (SCE) were seen. No significant association was shown between mutagenic sensitivity and baseline characteristics, but with small sample size.CONCLUSION: 21% borderline to hypersensitive mutagenic sensitivity among oncology workers at the tertiary government hospital is relatively significant, despite small sample size, connoting a must preventive promotive practice of chemotherapy administration in the workplace.

Chromosomal Instability in the Peripheral Blood Lymphocytes of an Ovarian Cancer Patient Undergoing Chemotherapy

Chemotherapy agents can induce chromosomal instability, including a variety of chromatid or chromosomal aberrations. However, only limited data is available on the effect of chemotherapy on the kinetics of chromosomal instability in peripheral blood lymphocytes. Here, we report the case of an ovarian cancer patient who showed chromosomal instability in peripheral blood lymphocytes while undergoing chemotherapy. Karyotypic analysis of peripheral blood 1 day after administration of cisplatin and etoposide showed chromosomal or chromatid aberrations, including gaps, breaks, and fragmentation. Chromosome study after completion of the first chemotherapy cycle showed normal karyotype. This finding suggests that chemotherapeutic agents can induce transient chromosomal instability in peripheral blood lymphocytes.

Monocentric Derivative Y Chromosome with Duplication of the SRY Gene in an Azoospermic Male

Structural abnormalities of the Y chromosome affect normal testicular differentiation and spermatogenesis. The present case showed a rare monocentric derivative Y chromosome with partial duplication of Yp including the SRY gene and deletion of Yq12 heterochromatin. The karyotype was 46,X,der(Y) (pter-->q11.23::p11.2-->pter).ish der(Y)(DYZ3+,DYZ1-,SRY++), confirmed through a FISH study. Even though the patient possessed an abnormal Y chromosome, testicular biopsy showed normal testicular volumes in the proband, with gonadal hormonal levels in the normal range but bilateral varicocele and hypospermatogenesis. We speculate that the abnormal Y chromosome arose from sister chromatids during Y chromosome recombination or intra chromosomal NAHR (non-allelic homologous recombination) during meiosis in the patient's father or in the very early stages of embryogenesis. The derivative Y chromosome might interfere in the meiotic stage of spermatogenesis, leading to the developmental arrest of germ cells. The present case illustrates that the infertility phenotype can have various causes. Also, it emphasizes the importance of accurate and various genetic analyses and could aid in male infertility treatment.

Pathways and genes of DNA double-strand break repair associated with head and neck cancer

DNA double-strand breaks (DSBs) occur commonly in the all living and in cycling cells. They constitute one of the most severe form of DNA damage, because they affect both strand of DNA. DSBs result in cell death or a genetic alterations including deletion, loss of heterozygosity, translocation, and chromosome loss. DSBs arise from endogenous sources like metabolic products and reactive oxygen, and also exogenous factors like ionizing radiation. Defective DNA DSBs can lead to toxicity and large scale sequence rearrangement that can cause cancer and promote premature aging. There are two major pathways for their repair: homologous recombination(HR) and non-homologous end-joining(NHEJ). The HR pathway is a known "error-free" repair mechanism, in which a homologous sister chromatid serves as a template. NHEJ, on the other hand, is a "error-prone" pathway, in which the two termini of the broken DNA molecule are used to form compatible ends that are directly ligated. This review aims to provide a fundamental understanding of how HR and NHEJ pathways operate, cause genome instability, and what kind of genes during the pathways are associated with head and neck cancer.

Pathways and genes of DNA double-strand break repair associated with head and neck cancer

DNA double-strand breaks (DSBs) occur commonly in the all living and in cycling cells. They constitute one of the most severe form of DNA damage, because they affect both strand of DNA. DSBs result in cell death or a genetic alterations including deletion, loss of heterozygosity, translocation, and chromosome loss. DSBs arise from endogenous sources like metabolic products and reactive oxygen, and also exogenous factors like ionizing radiation. Defective DNA DSBs can lead to toxicity and large scale sequence rearrangement that can cause cancer and promote premature aging. There are two major pathways for their repair: homologous recombination(HR) and non-homologous end-joining(NHEJ). The HR pathway is a known "error-free" repair mechanism, in which a homologous sister chromatid serves as a template. NHEJ, on the other hand, is a "error-prone" pathway, in which the two termini of the broken DNA molecule are used to form compatible ends that are directly ligated. This review aims to provide a fundamental understanding of how HR and NHEJ pathways operate, cause genome instability, and what kind of genes during the pathways are associated with head and neck cancer.

Human oocyte chromosome analysis: complicated cases and major pitfalls.

Human oocytes that remained unfertilized in programmes of assisted reproduction have been analysed cytogenetically for more than 20 years to assess the incidence of aneuploidy in female gametes. However, the results obtained so far are not indisputable as a consequence of difficulties in evaluating oocyte chromosome preparations. Because of the lack of guidelines, we decided to summarize for the first time, the possible pitfalls in human oocyte chromosome analysis. Therefore, we screened the material from our previous studies and compiled representative, complicated cases with recommendations for their cytogenetic classification. We point out that maturity and size of the oocyte are important parameters and that fixation artefacts, as well as the particular structure of oocyte chromosomes, may predispose one to misinterpretations. Moreover, phenomena related to oocyte activation and fertilization are illustrated and explained. This compilation may help to avoid major problems in future studies and contribute to a more precise, and uniform assessment of human oocyte chromosomes.

Influence of postovulatory ageing on balanced predivision of sister chromatid in mouse oocytes / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the impact of postovulatory ageing to balanced predivision of oocyte sister chromatid.</p><p><b>METHODS</b>The mouse oocytes were cultured 0-72 h. Then chromosome 16 was detected by fluorescence in situ hybridization (FISH). The oocyte spindle and chromosome configuration were examined by immunocytochemistry.</p><p><b>RESULTS</b>For freshly ovulated mouse oocyte, the balanced predivision of sister chromatid occurred only at 7%. However, for oocytes cultured for 24 h, 48 h and 72 h in vitro, the balanced predivision of sister chromatid occurred up to at 32%, 51% or 62% respectively (P< 0.01). The abnormal cell spindle and chromosome configuration occurred at 9% of freshly ovulated oocytes, but it increased to 63%, 83% and 98% when the oocytes were cultured in vitro for 24 h, 48 h or 72 h respectively (P< 0.01).</p><p><b>CONCLUSION</b>The occurrence of balanced predivision of oocyte sister chromatid may result during postovulatory ageing, and may be related to change of oocyte spindle and chromosome configuration.</p>

Expression of Anaphase Promoting Complex in Surgically Resected Squamous Cell Carcinoma and Adenocarcinoma of the Lung

BACKGROUND: The anaphase promoting complex (APC) promotes the degradation of mitotic cyclins as well as other substrates involved in sister chromatid adhesion. This study was carried out to examine the relationship between the APC expression and the clinicopathological variables, in an attempt to determine the role of the APC in the proliferation of lung cancer and to evaluate the possibility of an aberrant APC function in surgically resected squamous cell carcinomas and adenocarcinomas of the lung. METHODS: Immunohistochemical staining was performed for APC, Ki-67, cyclin B1, Cdc2, MMP-2 and VEGF in 55 cases of squamous cell carcinoma and 34 cases of adenocarcinoma of the lung, using the avidin-biotin-peroxidase method. RESULTS: The immunohistochemical stains for APC revealed a positive reaction in 49 cases (55.1%). The APC expression level was higher in the cyclin B1-positive group (p= 0.01), the Cdc2-positive group (p=0.001), the MMP-2-positive group (p=0.03), the group with lymph node metastasis (61.4% vs 48.9%), and the group with stage II/III cancer (60.7%) compared with those with stage I (42.9%). CONCLUSIONS: The APC may have an aberrant function, such as a change in its role in controlling the cell cycle, and might be associated with the invasiveness and proliferation of tumor cells.

Identification of hRad21-Binding Sites in Human Chromosome

The aim of this study is to identify hRad21-binding sites in human chromosome, the core component of cohesin complex that held sister chromatids together. After chromatin immunoprecipitation with an hRad21 antibody, it was cloned the recovered DNA and sequenced 30 independent clones. Among them, 20 clones (67%) contained repetitive elements including short interspersed transposable elements (SINE or Alu elements), long terminal repeat (LTR) and long interspersed transposable elements (LINE), fourteen of these twenty (70%) repeats clones had Alu elements, which could be categorized as the old and the young Alu Subfamily, eleven of the fourteen (73%) Alu elements belonged to the old Alu Subfamily, and only three Alu elements were categorized as young Alu subfamily. There is no CpG island within these selected clones. Association of hRad21 with Alu was confirmed by chromatin immunoprecipitation-PCR using conserved Alu primers. The primers were designed in the flanking region of Alu, and the specific Alu element was shown in the selected clone. From these experiments, it was demonstrated that hRad21 could bind to SINE, LTRs, and LINE as well as Alu.

Detección de daño genotóxico en niños expuestos a metales pesadosen Alto Lima - La Paz / Detection of genotoxic harm in niños expuestos to metals pesadosen high Alto Lima - La Paz

Muchos estudios epidemiológicos han demostrado que la exposición ocupacional o accidental al plomo está asociado con una incidencia mayor a tumores renales y cáncer de pulmón y estómago. En varios estudios in vivo se observó un aumento de aberraciones cromosómicas y frecuencia de intercambio entre cromátides hermanas (ICH) en linfocitos de trabajadores expuestos a plomo 1. Utilizando célulashumanas expuestas a plomo in vitro han sugerido que los iónes plomo disminuyen la fidelidad de la síntesiso reparación del ADN 2. El deterioro del ADN y los efectos genotóxicos pueden ser magnificados cuando la reparación es inhibida, como se demostró en unestudio sobre la inducción de ICH por LUV en células expuestas a diferentes niveles de plomo.

Progress in the research of aneuploidy genesis / 中华医学遗传学杂志

Aneuploidy is an important point at issue in human reproductive biology, accounting for both a major proportion of miscarriages and various congenital malformation syndromes among newborns. Despite its high incidence and severe clinical consequences, very little is known about how aneuploidy originates in human. On the other hand, remarkable progress has been made in the research of meiosis. The failure of any process in meiosis can result in chromosome mal-disjunction. The alteration in recombination and the premature separation of sister chromatids are two important processes on which more intensive researches have been done. In addition, mtDNA mutation and sexual dimorphism in aneuploidy genesis have also attracted more and more researchers' attention.

Relationship between Expression of Anaphase-promoting Complex and Prognostic Factors in Invasive Ductal Carcinoma of Breast

BACKGROUND: The role of the anaphase-promoting complex (APC) is to promote the degradation of mitotic cyclins and other substrates involved in sister chromatid adhesions. The APC appears to be responsible for the degradation of cyclin B and may have a potential role in the loss of control concerning cell proliferation in mammalian cells. However, a direct link between the defects in the APC components and oncogenesis has not been estabilished. This study investigates the relationship between APC expression and variable prognostic factors in invasive ductal carcinoma of the breast. METHODS: We evaluated 108 cases of invasive ductal carcinoma surgically resected from January, 1996 to May, 2000 at Wonju Christian Hospital, Wonju College of Medicine, Yonsei University. Immunohistochemical stains for APC, estrogen receptor, and Ki-67 were done in paraffin sections using the avidin-biotin complex method. The results were compared with clinical and pathologic parameters and flow cytometric DNA analysis factors. RESULTS: Forty cases (37.0%) showed immunopositive reactions for APC. The APC positivity in histologic grades 1, 2, and 3 were 28 cases (84.4%), 33 cases (60.0%), and 7 cases (35.0%), respectively (p=0.0011). The APC expressions in cases with the number of mitosis of less than 10, 10-19, and more than 20 per 10 high power fields, were noted in 37 cases (75.5%), 26 cases (63.4%), and 5 cases (27.8%), respectively (p=0.0016). The mean value of the Ki-67 labeling index was 221.7 in the APC-positive group and 317.9 in the APC-negative group (p= 0.0091). DNA flow cytometric analysis revealed higher APC expressions in cases with diploid patterns (p=0.0095). The APC expression rate increased significantly with decreasing histologic grade, with decreasing mitotic activity, in cases with a low Ki-67 labeling index, and those in the diploid group (p<0.05). The APC expression was not statistically correlated with clinical stage, tumor size, and estrogen receptor status. CONCLUSIONS: These findings suggest that positive APC expression may be considered as a good prognostic factor of invasive ductal carcinoma, and loss of APC expression may be related with the progression of breast cancer.

A preliminary study on the early diagnosis of myelodysplastic syndromes / 中华血液学杂志

<p><b>OBJECTIVE</b>To evaluate the four techniques for clonal analysis in the early diagnosis of myelodysplastic syndromes (MDS).</p><p><b>METHODS</b>Four techniques for clonal analysis were performed in bone marrow samples from fifty patients with suspected MDS: (1) Conventional cytogenetics (CC) for clonal chromosomal abnormalities; (2) BrdU-sister chromatid differentiation (BrdU-SCD) for cell cycle analysis; (3) Fluorescence in situ hybridization (FISH) for trisomy 8; (4) PCR-SSCP for N-ras mutation.</p><p><b>RESULTS</b>The diagnosis of forty-five patients was compatible with FAB criteria of MDS, the other five patients didn't fully meet the FAB criteria. They had either only one lineage dyspoiesis or no any obvious dysplastic features and two of them were diagnosed as suspicious refractory anemia (RA), one as anemia with hypercellular bone marrow and two as chronic aplastic anemia. The results of the four techniques performed in them showed that four patients had clonal karyotype abnormalities, two had prolonged cell cycle, three had trisomy 8 of different proportions, and one had N-ras mutation. Thus, they were all diagnosed as RA.</p><p><b>CONCLUSION</b>The untypical MDS patients can be diagnosed early by examination with combining several clonal analysis techniques.</p>

Cytogenetic damage related to low levels of methyl mercury contamination in the Brazilian Amazon

The mercury rejected in the water system, from mining operations and lixiviation of soils after deforestation, is considered to be the main contributors to the contamination of the ecosystem in the Amazon Basin. The objectives of the present study were to examine cytogenetic functions in peripheral lymphocytes within a population living on the banks of the Tapajós River with respect to methylmercury (MeHg) contamination, using hair mercury as a biological indicator of exposure. Our investigation shows a clear relation between methylmercury contamination and cytogenetic damage in lymphocytes at levels well below 50 micrograms/gram, the level at which initial clinical signs and symptoms of mercury poisoning occur. The first apparent biological effect with increasing MeHg hair level was the impairment of lymphocyte proliferation measured as mitotic index (MI). The relation between mercury concentration in hair and MI suggests that this parameter, an indicator of changes in lymphocytes and their ability to respond to culture conditions, may be an early marker of cytotoxicity and genotoxicity in humans and should be taken into account in the preliminary evaluation of the risks to populations exposed in vivo. This is the first report showing clear cytotoxic effects of long-term exposure to MeHg. Although the results strongly suggest that, under the conditions examined here, MeHg is both a spindle poison and a clastogen, the biological significance of these observations are as yet unknown. A long-term follow-up of these subjects should be undertaken.

Bleomycin sensitivity in patients with familial and sporadic polyposis: a pilot study

Human peripheral blood lymphocytes from 10 patients with familial adenomatous polyposis (FAP) showed a significantly higher incidence of chromatid breaks when compared to cells from 10 normal individuals, after exposure to bleomycin (BLM) during the G2 phase. However, no significant increase in bleomycin sensitivity was observed in lymphocytes from 10 patients with sporadic adenomatous polyps (AP) vs. 10 normal individuals (P = 0.67). Individuals that exhibited an average number of chromatid breaks per cell higher than 0.80 were considered sensitive to the drug. No control showed susceptibility to BLM, as compared to 3 out of 20 patients.

Chromosome Aberrations and Sister Chromatid Exchanges of Hospital Workers Exposed to Radiation / 예방의학회지

In order to evaluate the cytogenetic hazard among hospital workers potentially exposed to low dose of radiation, the analysis of chromosome aberrations(CA) and sister chromatid exchanges(SCE) in lymphocytes were performed in 79 hospital workers and 79 non-exposed workers. The mean frequency of chromosomal exchange and deletion(respectively, 0.20X10-2/cell and 0.39X10(-2)/cell) in the exposed group were significantly higher than those(0.07X10(-2)/cell and 0.23X10-2/cell) in control group. The frequency of sister chromatid exchanges was 5.04/cell in the control vs. 6.57/cell in the exposed group. There were also significant differences in the mean frequencies of CA and SCE adjusted for age, sex, smoking, drinking between two groups. There were no evidence of significant increase of CA and SCE according to the department or duration of employment. But the frequency of cells having chromosome aberration was significantly higher in the exposed group than in the control group related to duration of employment. There was no dose-effect relationship between the cumulative doses and the frequency of CA and SCE. But in the case of last 1 yr cumulative dose, there were evidence of significant dose-dependant increase of chromosome type CA and percentage of cells with aberration. The result suggest that there is cytogenetic hazard in risk group like hospital workers handling low dose radiation. And the analysis CA and SCE are useful biological indicators for the exposure of low dose level of radiation.

Ultrastructural Injury and Its Mechanism of Cultured Cardiac Myocytes under Anoxia-Reoxygenation / 대한해부학회지

Abrupt reoxygenation (or reperfusion) after anoxia (or ischemia)-induced injury resulted in the loss of contractile property, destruction of cell organelles, and ultimately, cell death in cardiac myocytes. This phenomenon has been called 'oxygen paradox' or 'reperfusion injury'. The purpose of this study was to investigate the changes of fine structures and enzyme activities associated with oxygen paradox during 60 min. of anoxia, followed by a 30 min. of reoxygenation. Cardiac myocytes were dissociated from neonatal rat ventricles and cultured for three days. While they were exposed to anoxia and reoxygenation, the cardiac myocytes were investigated through beating counts, enzyme cytochemistry, immunofluorescence, electron microscopy for morphological study. Activity staining and Western blot for Cu, Zn-SOD, NADPH-diaphorase stain and nitrite concentration mesurement for nitric oxide synthase, and catalase activity measurement were performed. After 60 min. of anoxia, the beating rate increased remarkably. Swollen mitochondria with amorphous dense clumps, mild contracture of myofibrils and retraction of cytoplasmic processes were observed in cardiac myocytes. Under confocal microscope, weak reaction of Mn-SOD and myosin were observed, whereas reaction of Cu, Zn-SOD was enhanced in perinuclear region. Cu, Zn-SOD and catalase activity in cardiac myocytes increased markedly. Nitric oxide synthase activity increased gradually with time. After 30 min. of reoxygenation following 60 min anoxia, structural changes of myocardial cells was more pronounced than in the cells of anoxic group. Beating rate was variable but decreased gradually. Myocardial cells showed evidence of severe structural alterations, including marginal clumping of chromatids, varying-sized bleb formation, many vacuoles, mitochondrial matrix exposed to cytoplasm and fragmen-tation of cristae, myofibrillar hypercontracture. Decline of immunocytochemical reaction of Mn-SOD, myosin and Cu, Zn-SOD were observed under confocal microscope. The declines of activity and quantity of Cu, Zn-SOD were severe compared to control. In contrast, nitric oxide synthase activity significantly increased. Catalase activity was lower than in anoxic group, but still higher than in control activity. These results suggested that there were two possible mechanisms for the drastic morphological changes induced by anoxia-reoxygenation; 1) direct effect of oxygen free radicals, and 2) reaction of nitric oxide with superoxide radicals, which resulted in generation of toxic metabolites of nitric oxide, exacerbated myocardial cellular damages.

Clastogenic effects of different Ureaplasma urealyticum serovars on human chromosomes

The possibility that Ureaplasma urealyticum might play an important role in human infertility was first raised more than 20 years ago, but this association remains speculative. Considering the hypothesis that the pathogenicity of Ureaplasma urealyticum may depend on its serotypes, the clastogenic effcts of different strains of Ureaplasma urealyticum, at concentrations of 10(3) CCU (color changing units)/ml, 10(4) CCU/ml and 10(5) CCU/ml, were evaluated in vitro in short-term cultures of human lyphocytes. Total or partial mitotic inhibition was produced by Ureaplasma urealyticum serotypes 2,3 and 10 independent of the concentration (10(3) CCU/ml, 10(4) CCU/ml or 10 (5) CCU/ml) of the microorganisms employed. In contrast, the clastogenic effects observed with serotypes 1,7 and 12 varied according to the concentration employed in the test. Mitotic alterations were observed in Ureaplasma urealyticum serotypes 5,6,7,8,9,11 and 12. Chromatid gaps (53.0 percent) and chromatid breaks (13.9 percent) were the most frequent types of alterations observed. The results of this in vitro assay demonstrated that the clastogenic effects varied with the Ureaplasma urealyticum serotypes evaluated.