Detection of reactive oxygen species (ROS) and apoptosis in human fragmented embryos

In human in-vitro fertilization (IVF)-embryo transfer, the in-vitro culture environment differs from in-vivo conditions in that the oxygen concentration is higher, and in such conditions the mouse embryos show a higher concentration of reactive oxygen species (ROS) in simple culture media. ROS are believed to cause damage to cell membranes and DNA fragmentation in somatic cells. This study was conducted to ascertain the level of H2O2 concentration within embryos and the morphological features of cell damage induced by H2O2. A total of 62 human oocytes and embryos (31 fragmented, 15 non-fragmented embryos, 16 unfertilized oocytes) was obtained from the IVF-embryo transfer programme. The relative intensity of H2O2 concentrations within embryos was measured using 2',7'-dichlorodihydrofluorescein diacetate by Quanti cell 500 fluorescence imaging and DNA fragmentation was observed with transmission electron microscopy and an in-situ apoptosis detection kit. The H2O2 concentrations were significantly higher in fragmented embryos (72.21 +/- 9.62, mean +/- SEM) compared to non-fragmented embryos (31.30 +/- 3.50, P < 0.05) and unfertilized oocytes (30.75 +/- 2.67, P < 0.05). Apoptosis was observed only in fragmented embryos, and was absent in non-fragmented embryos. Electron microscopic findings confirmed apoptotic bodies and cytoplasmic condensation in the fragmented blastomeres. We conclude that there is a direct relationship between increased H2O2 concentration and apoptosis, and that further studies should be undertaken to confirm these findings.      

Use of a non-radioactive hybridisation assay for direct detection of gram-negative bacteria carrying TEM beta-lactamase genes in infected urine

DNA in infected urines from 81 patients with urinary tract infection was hybridised directly with a non-radioactive DNA probe specific for bacterial genes coding for TEM-type beta-lactamase. The results were assessed by means of a computerised image analysis system and compared with those obtained following isolation of the infecting organism, conventional sensitivity testing and isoelectric focusing (IEF) procedures for the detection of TEM-type beta-lactamase. Of the 27 ampicillin-resistant gram-negative organisms isolated in pure culture from the urines, 14 were shown by both hybridisation and IEF to carry a gene for TEM beta-lactamase production. Only four discordant results were obtained: three "false positive" direct hybridisation results, one due to urine pigmentation, and one, possibly, to a TEM beta-lactamase gene which was not being expressed, and one "false negative" result due to insufficient cell numbers in the urine. The system is capable of screening large numbers of samples and is applicable to any gene for which a suitable DNA probe is available.     

Reciprocal expression of lin-41 and the microRNAs let-7 and mir-125 during mouse embryogenesis.

In C. elegans, heterochronic genes control the timing of cell fate determination during development. Two heterochronic genes, let-7 and lin-4, encode microRNAs (miRNAs) that down-regulate a third heterochronic gene lin-41 by binding to complementary sites in its 3'UTR. let-7 and lin-4 are conserved in mammals. Here we report the cloning and sequencing of mammalian lin-41 orthologs. We find that mouse and human lin-41 genes contain predicted conserved complementary sites for let-7 and the lin-4 ortholog, mir-125, in their 3'UTRs. Mouse lin-41 (Mlin-41) is temporally expressed in developing mouse embryos, most dramatically in the limb buds. Mlin-41 is down-regulated during mid-embryogenesis at the time when mouse let-7c and mir-125 RNA levels are up-regulated. Our results suggest that mammalian lin-41 is temporally regulated by miRNAs in order to direct key developmental events such as limb formation.     

Purification of DNA for the transfection of a Spodoptera frugiperda cell line

Spodoptera frugiperda (Sf-9) cells have been widely used in baculovirus expression systems, transient gene expression studies and transgenic cell lines. These applications commonly require the transfection of bacterial plasmid DNA. One of the most reliable methods of preparing transfection-quality plasmid DNA is cesium chloride (CsCl) density gradient centrifugation. However, the traditional CsCl DNA purification is a long and laborious process. We have made a series of modifications to the traditional method that makes it faster, safer and easier. In the current study we demonstrate that DNA prepared by our modified CsCl method was also better for the transfection of Sf-9 cells than DNA prepared by the traditional CsCl method.     

Family history and risk of breast cancer.

The risk of breast cancer in first degree relatives of patients with breast cancer can be derived from family history and is dependent upon the age at diagnosis in the index patient. For the relatives of index patients older than 55, the relative risk is 1.57, if less than 55 the relative risk is 2.29, and 3.85 if less than 45 (95% confidence limits 0.83 to 2.68, 1.18 to 4.01, and 1.67 to 3.85, respectively). First degree relatives of patients with bilateral breast cancer have a 6.43-fold increase in risk (95% confidence limits 1.32 to 18.77). The genetic contribution to overall lifetime liability to breast cancer in the relatives declines rapidly with increasing age of onset of breast cancer in the index patient from 37% at 20 years to 8% by 45 years. This information can be used in clinical practice for counselling and the establishment of screening programmes.     

Screening and genetic counselling for relatives of patients with breast cancer in a family cancer clinic.

Family history is the major risk factor in the aetiology of breast cancer. Breast screening is currently available to women from the age of 50 to 64 through the National Breast Screening Programme. There is, however, an equivalent risk of developing breast cancer below 50 for first degree relatives of women diagnosed with breast cancer premenopausally. We have estimated the risk of breast cancer for relatives of women affected at different ages and used these to establish a family cancer clinic offering breast screening based on individual risk. In three years we have seen 851 patients. Compliance for annual radiology was in excess of 83% over this period and of five cancers detected one had a lump at presentation, two developed interval breast lumps, and two were asymptomatic.     

Changes in fibrinogen adsorbed to segmented polyurethanes and hydroxyethylmethacrylate-ethylmethacrylate copolymers.

Fibrinogen adsorption from blood to biomaterials may regulate platelet adhesion and thrombus formation because of fibrinogen's central role in the coagulation cascade and its ability to bind specifically to the platelet membrane glycoprotein (GP) IIb-IIIa. Adsorption of fibrinogen from blood plasma to many materials exhibits a maximum with respect to plasma dilution and exposure time (the Vroman effect). In this study fibrinogen adsorption to several polymers was examined to ascertain the influence of controlled changes in surface chemistry on the Vroman effect. The materials included hydroxyethylmethacrylate-ethylmethacrylate (HEMA/EMA) copolymers, Biomer, and a series of segmented polyurethanes (PEUs), two of which contained fluorinated chain extenders. Each material exhibited maximal adsorption of fibrinogen at intermediate plasma concentrations. Little effect of soft-segment type or molecular weight was observed and no significant differences in fibrinogen adsorption to the fluorinated PEUs were seen. Changes in the strength of fibrinogen attachment to these materials with time after adsorption were also assessed. Fibrinogen adsorbed for 1 min was displaced more readily by blood plasma than that adsorbed for 1 h, regardless of the material. The more hydrophobic polymers exhibited greater retention of adsorbed fibrinogen. In addition, the fraction of fibrinogen retained by polyethylene depended on the amount of fibrinogen adsorbed to the surface, being greatest when the surface loading was the least. These studies indicate that spreading or transition of adsorbed fibrinogen molecules from a weakly to tightly bound state is a general consequence of protein adsorption to solid surfaces.     

Complex coronary angioplasty: a technique for dilatation of bifurcation stenoses

Bifurcation stenoses have been recognized to be at "high risk" for acute closure during percutaneous transluminal coronary angioplasty. Use of the traditional single balloon technique in such situations often results in acute closure or worsening of the stenosis in the other branch. A technique utilizing simultaneous inflation of two balloons, ("kissing balloon" technique) has been utilized to avoid this complication. A double balloon technique has been developed using sequential inflations rather than simultaneous inflations to preserve the integrity of both branches while avoiding the arterial trauma produced by inflating two balloons in a small artery simultaneously. Twelve of 13 bifurcation stenoses were successfully treated with this sequential inflation double balloon technique. (Primary success rate = 92%).     

Age-related headache characteristics

A computerized headache interview was completed by 255 children, adolescents, and adults. Children did not differ from adults in the frequency of auras or prodromes. Young children were more likely than older patients to have brief headaches and headaches that tended to occur on weekdays, and to feel "great" after a headache. They were less likely than older patients to acknowledge multiple kinds of headaches, headaches located on one side of the head or posteriorly, and such concomitant occurrences as blurring, photophobia, irritability, frustration-anger, light-headedness, trouble with concentration, numbness-tingling, and lack of appetite. We do not know how much these differences can be attributed to age-related differences in language, physiology, or medical care selection factors.     

The C. elegans microRNA let-7 binds to imperfect let-7 complementary sites from the lin-41 3'UTR

Caenorhabditis elegans let-7, a founding member of the microRNA family, is predicted to bind to six sites in the 3'UTR of the mRNA of its target gene, lin-41, to down-regulate LIN-41. Here, we demonstrate that wild-type let-7 microRNA binds in vitro to RNA from the lin-41 3'UTR. This interaction is dependent on two conserved let-7 complementary sites (LCSs). A 27-nucleotide sequence between the LCSs is also necessary for down-regulation in vivo. LCS mutations compensatory to the lesion in let-7(n2853) can partially restore lin-41 3'UTR function in a let-7(n2853) background, providing the first experimental evidence for an animal miRNA binding directly to its validated target in vivo.