How identical would cloned children be? An understanding essential to the ethical debate. (1/486)

The ban on human cloning in many countries worldwide is founded on an assumption that cloned children will be identical to each other and to their nuclear donor. This paper explores the scientific basis for this assumption, considering both the principles and practice of cloning in animals and comparing genetic and epigenetic variation in potential human clones with that in monozygotic twins.  (+info)

Immunocytogenetic detection of normal and abnormal oocytes in human fetal ovarian tissue in culture. (2/486)

This study aimed to: (i) determine whether oocytes are present in cultures of human fetal ovary; (ii) identify whether meiotic anomalies are evident; and (iii) assess whether preparation or culture conditions influence oocyte survival and meiotic progression. Ovaries were collected from fetuses after termination at 13-16 weeks. Oocyte assessment utilized antibodies specific for synaptonemal complex proteins (associated with chromosomes only during meiosis), and antibodies to centromeric proteins. Fragments of tissue were cultured in minimal essential medium + 10% serum +/- follicle stimulating hormone (100 mIU/ml). The sera were fetal calf serum (FCS), FCS for embryonic stem cells (ES-FCS) and human female serum. The numbers and stages of oocytes were assessed after 7-40 days, and particular arrangements of chromosome synapsis identified. Results in fresh tissue included oocytes at leptotene, zygotene, pachytene and diplotene in three of five samples. Four specimens remained viable in vitro, and three had detectable oocytes after culture. The numbers of oocytes and the proportions of zygotene and pachytene cells increased with time in culture. The proportion of degenerate cells in culture was initially higher than in fresh samples, but declined subsequently. More oocytes were detected in ES-FCS and human serum than in FCS. We conclude that human oocytes survive in culture and that progression through prophase I continues.  (+info)

Danish National In-Vitro Fertilization Registry 1994 and 1995: a controlled study of births, malformations and cytogenetic findings. (3/486)

This paper reports data from the Danish in-vitro fertilization (IVF) registry from 1994 to 1995 including data on treatments and the results of these (perinatal outcome, cytogenetic findings and fetal malformations) in comparison with a control group matched for maternal age, parity, multiplicity and year of birth. There were 1756 deliveries of 2245 children (24.3% twins, 1.8% triplets). The rate of prematurity among IVF children was 23.8% (NS) [singletons 7. 3% (P < 0.05), twins 41.2% and triplets 93.5%], 23.6% weighed <2500 g [singletons 7% (P < 0.05), twins 42.2% and triplets 87.1%]. The perinatal mortality rate was 21.8 in the study group compared to 17. 4 in the control group (NS). In total, 13.2% of all clinical pregnancies and 15.4% of the pregnancies that resulted in a delivery had a prenatal genetic examination. Of all examined, 3.5% had an abnormal karyotype. In total, 107 (4.8%) children in the study group and 103 (4.6%) in the control group were born with malformations (NS), compared to 2.8% in the background population. Our results indicate that it is the characteristics of the patients and multiplicity of pregnancy, rather than the assisted reproductive technology that determines the fetal risks of IVF pregnancies compared to the background population.  (+info)

AlphaIFN-induced hematologic and cytogenetic remission in chronic eosinophilic leukemia with t(1;5). (4/486)

Chronic eosinophilic leukemia (CEL) is a myeloproliferative disease characterized by excessive eosinophilic proliferation with clonal cytogenetic abnormalities. The most frequent cytogenetic abnormality is a break in the q 31-35 region of chromosome 5, where genes encoding for IL-3, IL-5 and GM-CSF (all cytokines involved in eosinophilopoiesis) are located. We report the case of a patient with CEL with t(1;5) (q23;q31), who obtained complete hematologic and major cytogenetic response after two years of alpha-interferon (alpha-IFN) therapy. Two other cases of complete response to alpha-IFN are reported in the literature. A trial with alpha-IFN could be considered as front line treatment in this rare disease.  (+info)

CD56+CD7+ stem cell leukemia/lymphoma with D2-Jdelta1 rearrangement. (5/486)

OBJECT: We describe the characteristics of three patients with CD56+CD7+ stem cell leukemia/lymphoma. METHODS: These blasts were analyzed for morphologic, karyotypic, immunophenotypic, and immunogenotypic features using Southern blot and polymerase chain reaction analysis. MATERIALS: Peripheral blood, bone marrow aspirates, or biopsied mediastinal tumor specimens of three CD56+CD7+ stem cell leukemia/lymphoma patients were investigated. RESULTS: The bone marrow of all patients showed myeloperoxidase (MPO) negative blast cells with basophilic cytoplasm and distinct nucleoli with no azurophilic granules. The blasts of two patients were classified as acute lymphoblastic leukemia (L2). The liver, spleen, and lymph nodes were unaffected in all patients. All had an aggressive clinical course. The blasts were strongly positive for both CD7 and CD56 but negative for other T-lineage associated antigens, including CD1, CD2, surface membrane CD3, cytoplasmic CD3c (2/2), CD4, CD5 and CD8. The additional antigens were recognized as follows: CD19 (1/3 cases) as a B lineage, CD33 (1/3) as a myeloid marker, CD34 (2/3) as a stem cell, CD38 (1/1) and HLA-DR (2/3). When the patients relapsed, the phenotypes changed to blasts positive for CD5, CD10 and CD13 in patient 1, CD5 in patient 2, and CD33 in patient 3. MPO, however, remained negative. Cytogenetic analysis showed no common abnormal karyotype. All had a common D2-Jdelta1 induced by T-cell specific enhancer. Rearrangement of TCR beta and gamma genes occurred in patient 2, and IgH and TCR beta underwent rearrangement in patient 3. CONCLUSION: Although a more comprehensive case analysis is necessary, these data suggest the possibility that the blasts of the present cases come from a common lymphoid precursor (T, NK, and B cell) or from a NKT precursor as the fourth lymphoid lineage.  (+info)

A survey of 1,000 cases referred for cytogenetic study to King Khalid University Hospital, Saudi Arabia. (6/486)

We reviewed cytogenetic studies that have been done in 1,000 consecutive non-oncology samples that were referred to the Cytogenetics Unit at King Khalid University Hospital, Riyadh, Saudi Arabia. The cases were grouped according to the referral diagnosis and the requested cytogenetic service. The frequency of the different types of numerical and structural abnormalities was determined and the relative frequency of cases with abnormal karyotype was calculated in each group. This study should assist physicians in Saudi Arabia and surrounding countries by increasing the awareness of the frequency of cytogenetic abnormality in different diagnostic groups. It also gives figures for comparison with other countries and research centers.  (+info)

Biodosimetry results obtained by various cytogenetic methods and electron spin resonance spectrometry among inhabitants of a radionuclide contaminated area around the siberian chemical plant (Tomsk-7). (7/486)

On April 6, 1993, near the town of Tomsk (Russia) there was an accident at the Siberian Chemical Plant (SCP) which resulted in extensive contamination of an area of 250 km(2) to the north of SCP with long-lived radionuclides such as (239)Pu, (137)Cs and (90)Sr. Cytogenetic methods and electron spin resonance (ESR) spectrometry of tooth enamel were used to estimate the radiation doses received by the population. The ESR signal intensity and the chromosomal aberration frequency in lymphocytes of the tooth donors showed a good correlation. The data showed that 15% of the inhabitants of the Samus settlement received a radiation dose >90 cGy. The exceptions were results of an examination of fishermen, where ESR gave high values (80-210 cGy) but both the chromosome assay and the cytokinesis block micronucleus method gave lower ones (8-52 cGy). A large increase in chromosome damage was observed in people born between 1961 and 1969. It was found that during these years several serious accidents at the Siberian Chemical Plant had occurred causing radiation pollution of the area. The number of cells with chromosome aberrations was significantly less among the people arriving in Samus after 1980. We found good correlations between the level of carotene consumption and a decrease in frequency of both micronuclei in binucleated lymphocytes (r = 0.68, P < 0.01) and chromatid aberrations (r = 0.61, P < 0.01) among the inhabitants. We also examined the inhabitants of Samus for opisthorchis infection, which was present in 30% of the population. The Samus inhabitants affected by Opisthorchis felineus showed significantly increased levels of micronuclei in binucleated lymphocytes and chromatid aberrations as compared with the controls.  (+info)

Processing of DNA damage induced by hydrogen peroxide and methyl methanesulfonate in human lymphocytes: analysis by alkaline single cell gel electrophoresis and cytogenetic methods. (8/486)

The persistence of induced DNA damage in human lymphocytes after mitogen stimulation and its relationship to subsequent cytogenetic alterations were investigated. The analysis of single-strand breaks and alkali-labile sites by single cell gel electrophoresis (SCGE) showed the almost complete repair of damage induced in resting lymphocytes by methyl methanesulfonate (MMS, 140-210 microM) and hydrogen peroxide (H(2)O(2), 25-100 microM) during the first 16 h of culture. On the other hand, DNA damage was shown to persist to a large extent when cells were cultured in the presence of the repair inhibitor cytosine beta-D-arabinofuranoside (Ara-C) (1 microg/ml). Although highly effective in the induction of DNA lesions detectable by SCGE, both agents failed to significantly increase the rate of micronucleus formation in cytokinesis-blocked cells harvested 66 h after treatment. However, when Ara-C was present during the first 16 h of culture, micronuclei were significantly increased at all doses. Conversely, sister chromatid exchange (SCE) rates were increased by chemical treatments to a higher extent in cultures without Ara-C. Delayed treatments, 16 h after mitogen stimulation, led to a significant induction of micronuclei in the case of MMS but not with H2O(2). These results suggest that only a minor fraction of DNA damage induced in resting lymphocytes is available for fixation through misreplication, because of its effective repair prior to S phase. However, the processing of damage through recombination pathways can lead to increased SCE rates in treated cells. These features of the processing of DNA damage in human lymphocytes should be taken into account when structural cytogenetic alterations in cultured lymphocytes are used in monitoring human exposure to genotoxic agents.  (+info)