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21.
Detection of chromosomes and estimation of aneuploidy in human spermatozoa using fluorescence in-situ hybridization 总被引:11,自引:0,他引:11
The development and application of fluorescence in-situ hybridization
(FISH) has opened the way for comprehensive studies on numerical chromosome
abnormalities in human spermatozoa. FISH can be rapidly applied to large
numbers of spermatozoa and thus overcomes the major limitation of
karyotyping spermatozoa after penetration of zona-free hamster oocytes. The
simultaneous hybridization of two or more chromosome-specific probes to
spermatozoa and subsequent detection of the bound probes using different
fluorescent detection systems enables two or more chromosomes to be
localized simultaneously in the same spermatozoon and provides a technique
for undertaking reasonable estimates of aneuploidy. The most commonly used
probes are those which bind to the centromeric region of specific
chromosomes. Most studies to date have concentrated on estimating
aneuploidy in spermatozoa from normospermic men, although reports are
beginning to appear on aneuploidy in spermatozoa from subfertile and
infertile men. Multi- probe FISH studies have generally reported disomy
(hyperhaploidy) estimates of 0.05-0.2% per chromosome. There is preliminary
evidence that some chromosomes such as X, Y and 21 are predisposed towards
higher rates of non-disjunction during spermatogenesis. There are also
suggestions of inter-donor variability in aneuploidy frequencies for
specific chromosomes, although this requires confirmation in larger
studies. While FISH is clearly a powerful technique that has many
applications in reproductive medicine, it must also be realized that it
does have limitations and the technology itself is still evolving and has
yet to be fully validated on spermatozoa.
相似文献
22.
Stark AR Carlo WA Tyson JE Papile LA Wright LL Shankaran S Donovan EF Oh W Bauer CR Saha S Poole WK Stoll BJ;National Institute of Child Health Human Development Neonatal Research Network 《The New England journal of medicine》2001,344(2):95-101
BACKGROUND: Early administration of high doses of dexamethasone may reduce the risk of chronic lung disease in premature infants but can cause complications. Whether moderate doses would be as effective but safer is not known. METHODS: We randomly assigned 220 infants with a birth weight of 501 to 1000 g who were treated with mechanical ventilation within 12 hours after birth to receive dexamethasone or placebo with either routine ventilatory support or permissive hypercapnia. The dexamethasone was administered within 24 hours after birth at a dose of 0.15 mg per kilogram of body weight per day for three days, followed by a tapering of the dose over a period of seven days. The primary outcome was death or chronic lung disease at 36 weeks' postmenstrual age. RESULTS: The relative risk of death or chronic lung disease in the dexamethasone-treated infants, as compared with those who received placebo, was 0.9 (95 percent confidence interval, 0.8 to 1.1). Since the effect of dexamethasone treatment did not vary according to the ventilatory approach, the two dexamethasone groups and the two placebo groups were combined. The infants in the dexamethasone group were less likely than those in the placebo group to be receiving oxygen supplementation 28 days after birth (P=0.004) or open-label dexamethasone (P=0.01), were more likely to have hypertension (P<0.001), and were more likely to be receiving insulin treatment for hyperglycemia (P=0.02). During the first 14 days, spontaneous gastrointestinal perforation occurred in a larger proportion of infants in the dexamethasone group (13 percent, vs. 4 percent in the placebo group; P=0.02). The dexamethasone-treated infants had a lower weight (P=0.02) and a smaller head circumference (P=0.04) at 36 weeks' postmenstrual age. CONCLUSIONS: In preterm infants, early administration of dexamethasone at a moderate dose has no effect on death or chronic lung disease and is associated with gastrointestinal perforation and decreased growth. 相似文献
23.
Preliminary observations on polar body extrusion and pronuclear formation in human oocytes using time-lapse video cinematography 总被引:10,自引:17,他引:10
Payne D; Flaherty SP; Barry MF; Matthews CD 《Human reproduction (Oxford, England)》1997,12(3):532-541
In this study, we have used time-lapse video cinematography to study
fertilization in 50 human oocytes that had undergone intracytoplasmic sperm
injection (ICSI). Time-lapse recording commenced shortly after ICSI and
proceeded for 17-20 h. Oocytes were cultured in an environmental chamber
which was maintained under standard culture conditions. Overall, 38 oocytes
(76%) were fertilized normally, and the fertilization rate and embryo
quality were not significantly different from 487 sibling oocytes cultured
in a conventional incubator. Normal fertilization followed a defined course
of events, although the timing of these events varied markedly between
oocytes. In 35 of the 38 fertilized oocytes (92%), there were circular
waves of granulation within the ooplasm which had a periodicity of 20-53
min. The sperm head decondensed during this granulation phase. The second
polar body was then extruded, and this was followed by the central
formation of the male pronucleus. The female pronucleus formed in the
cytoplasm adjacent to the second polar body at the same time as, or
slightly after, the male pronucleus, and was subsequently drawn towards the
male pronucleus until the two abutted. Both pronuclei then increased in
size, the nucleoli moved around within the pronuclei and some nucleoli
coalesced. During pronuclear growth, the organelles contracted from the
cortex towards the centre of the oocyte, leaving a clear cortical zone. The
oocyte decreased in diameter from 112 to 106 microm (P < 0.0001) during
the course of the observation period. The female pronucleus was
significantly smaller in diameter than the male pronucleus (24.1 and 22.4
microm respectively, P = 0.008) and contained fewer nucleoli (4.2 and 7.0
respectively, P < 0.0001). After time-lapse recording, oocytes were
cultured for 48 h prior to embryo transfer or cryopreservation. Embryo
quality was related to fertilization events and periodicity of the
cytoplasmic wave, and it was found that good quality embryos arose from
oocytes that had more uniform timing from injection to pronuclear abuttal
and tended to have a longer cytoplasmic wave. In conclusion, we have shown
that time-lapse video cinematography is an excellent tool for studying
fertilization and early embryo development, and have demonstrated that
human fertilization comprises numerous complex dynamic events.
相似文献
24.
Beta cell destruction has been shown to occur when rodent or human islets are exposed in vitro to inflammatory cytokines, such as interleukin-1beta (IL-1beta), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). Other cytokines such as interleukin-4 (IL-4) or interleukin-10 (IL-10), when given to NOD mice, prevent insulin-dependent diabetes mellitus (IDDM). In this study, we have employed immunofluorescence histochemistry to study the expression of IFN-gamma and IL-4 in the pancreas of female NOD mice at various time-points (days 0, 4, 7, 11 and at onset of diabetes) following disease acceleration with cyclophosphamide (Cy). Dual-label confocal and light microscopy were employed to determine the precise cellular sources of the two cytokines. IL-4 immunolabelling was observed in a few immune cells at days 0, 4, and 7 within the pancreatic islets but in larger numbers at day 11 and at onset of diabetes. The cytokine was co-localized predominantly in CD4 cells, while only a small minority of CD8 cells and macrophages also expressed IL-4. At days 0, 4, 7 and 11, weak to moderate immunolabelling for IL-4 was also observed in beta cells. In contrast, immunolabelling for IFN-gamma within the islets was not observed until day 11 and this labelling persisted at onset of diabetes. It was immunolocalized in macrophages and to a lesser extent in CD4 cells. Only a few CD8 cells were immunopositive for IFN-gamma. At day 11, a proportion of beta cells showed weak immunolabelling for IFN-gamma. During the study period, immunolabelling for IFN-gamma was also observed in a proportion of endothelial cells located in the intra-islet and exocrine regions of Cy and diluent-treated mice. From day 11 onwards, both the cytokines were observed in some of the peri-vascular regions. Our results demonstrate that during Cy-induced diabetes, there is increasing expression of both IL-4 and IFN-gamma in specific immune cells within the inflamed islets in the late prediabetic stage and at onset of diabetes. Further studies are required to correlate our protein immunohistochemical findings with in situ cytokine gene expression and to determine whether there is a clear Th1 cytokine protein bias at clinical onset of diabetes and immediately preceding it. 相似文献
25.
Shankaran S Laptook AR Ehrenkranz RA Tyson JE McDonald SA Donovan EF Fanaroff AA Poole WK Wright LL Higgins RD Finer NN Carlo WA Duara S Oh W Cotten CM Stevenson DK Stoll BJ Lemons JA Guillet R Jobe AH;National Institute of Child Health Human Development Neonatal Research Network 《The New England journal of medicine》2005,353(15):1574-1584
26.
An unusual surface peroxiredoxin protects invasive Entamoeba histolytica from oxidant attack 总被引:4,自引:0,他引:4
Choi MH Sajed D Poole L Hirata K Herdman S Torian BE Reed SL 《Molecular and biochemical parasitology》2005,143(1):80-89
Peroxiredoxins are an important class of antioxidant enzymes found from Archaea to humans, which reduce and thereby detoxify peroxides and peroxynitrites. The major thiol-containing surface antigen of the invasive ameba, Entamoeba histolytica, is a peroxiredoxin and is likely to be important during the transition from the anaerobic environment of the large intestine to human tissues. The closely related species, Entamoeba dispar, is incapable of invasion and more sensitive to hydrogen peroxide, yet also has a peroxiredoxin. We cloned and expressed the two active recombinant enzymes and found that their activity was similar by a fluorometric stopped-flow assay, giving a Km of <10 microM for hydrogen peroxide. Three monoclonal antibodies produced to recombinant E. histolytica peroxiredoxin cross-reacted with Entamoeba dispar.E. histolytica contains as much as 50 times more peroxiredoxin than E. dispar as demonstrated by a sensitive capture ELISA. In addition, the peroxiredoxin is present largely on the outer surface of the cell, in contrast to E. dispar. This unusual peroxiredoxin localizes to the site of parasite-host cell contact where it can effectively counteract oxidants generated by host cells, thus facilitating invasion. 相似文献
27.
The calcification of cartilage matrix in endochondral bone formation occurs in an extracellular matrix composed of fibrils of type II collagen with which type X collagen is closely associated. Also present within this matrix are the large proteoglycans containing chondroitin sulfate which aggregate with hyaluronic acid. In addition, the matrix contains matrix vesicles containing alkaline phosphatase. There is probably a concentration of calcium as a result of its binding to the many chondroitin sulfate chains. At the time of calcification, these proteoglycans become focally concentrated in sites where mineral is deposited. This would result in an even greater focal concentration of calcium. Release of inorganic phosphate, as a result of the activity of alkaline phosphatase, can lead to the displacement of proteoglycan bound calcium and its precipitation. The C-propeptide of type II collagen becomes concentrated in the mineralizing sites, prior to which it is mainly associated with type II collagen fibrils and is present in dilated cisternae of the enlarged hypertrophic chondrocytes. The synthesis of type II collagen and the C-propeptide, together with alkaline phosphatase, are regulated by the vitamin D metabolites 24,25(OH)2 cholecalciferol and 1,25 (OH)2 cholecalciferol. At the time of calcification, type X collagen remains associated with type II collagen fibrils. It may play a role in preventing the initial calcification of these fibrils focusing mineral formation in focal interfibrillar sites. This process of calcification is clearly very complex, and involves different interacting matrix molecules and is carefully regulated at the cellular level. 相似文献
28.
Jane F. Gibson Robert K. Poole Martin N. Hughes John F. Rees 《Archives of environmental contamination and toxicology》1986,15(5):519-523
The toxicity and possible accumulation of ruthenium nitrosyl complexes by marine bacteria and test organisms have been studied, A range of these complexes show no toxic effects towardsEscherichia coli K12 at concentrations of mM and below. Yeasts are more sensitive, showing effects on growth at 10 M. The ruthenium nitrosyl complexes tested are unable to permeate the cytoplasmic membrane ofE. coli. This may account for their lack of toxicity. However, these compounds did not have significant inhibitory effects on Mg2+-ATPase activity in cell-extracts, I50 values lying in the range 2 to 125 mol(mg protein)–1. Marine bacteria are capable of taking up ruthenium complexes from simulated effluent, but this cannot be demonstrated in the presence of sediment which competes effectively for binding of complexes. There is minimal likelihood of concentration of ruthenium compounds from effluents by marine bacteria. 相似文献
29.
Efflux-mediated multiresistance in Gram-negative bacteria 总被引:8,自引:0,他引:8
K. Poole 《Clinical microbiology and infection》2004,10(1):12-26
30.