Synthesis of soluble graphite and graphene.

Because of graphene's anticipated applications in electronics and its thermal, mechanical, and optical properties, many scientists and engineers are interested in this material. Graphene is an isolated layer of the π-stacked hexagonal allotrope of carbon known as graphite. The interlayer cohesive energy of graphite, or exfoliation energy, that results from van der Waals attractions over the interlayer spacing distance of 3.34 Å (61 meV/C atom) is many times weaker than the intralayer covalent bonding. Since graphene itself does not occur naturally, scientists and engineers are still learning how to isolate and manipulate individual layers of graphene. Some researchers have relied on the physical separation of the sheets, a process that can sometimes be as simple as peeling of sheets from crystalline graphite using Scotch tape. Other researchers have taken an ensemble approach, where they exploit the chemical conversion of graphite to the individual layers. The typical intermediary state is graphite oxide, which is often produced using strong oxidants under acidic conditions. Structurally, researchers hypothesize that acidic functional groups functionalize the oxidized material at the edges and a network of epoxy groups cover the sp(2)-bonded carbon network. The exfoliated material formed under these conditions can be used to form dispersions that are usually unstable. However, more importantly, irreversible defects form in the basal plane during oxidation and remain even after reduction of graphite oxide back to graphene-like material. As part of our interest in the dissolution of carbon nanomaterials, we have explored the derivatization of graphite following the same procedures that preserve the sp(2) bonding and the associated unique physical and electronic properties in the chemical processing of single-walled carbon nanotubes. In this Account, we describe efficient routes to exfoliate graphite either into graphitic nanoparticles or into graphene without resorting to oxidation. Our exfoliation process involves the intercalation of lithium into bulk graphite to yield graphene sheets reduced by the lithium. We can alkylate the resulting graphite salt reductively using solubilizing dodecyl groups. By probe microscopy, we show that these groups are attached covalently only at the graphitic edges.

The impact of traumatic pelvic fractures on sporting activity and quality of life.

BACKGROUND: Pelvic fractures (PFX) reflect high-energy trauma with high mortality and morbidity. AIM: We attempted to determine: whether there is a decrease in levels of sporting and physical activity in patients with operatively-treated PFX; risk factors for decreased sporting activity; any correlation between sporting activity and quality of life in this group. METHODS: Retrospective demographics on mechanism of injury, fracture type, associated injury and injury severity score, as well as prospective documentation of the level and frequency of sporting activity, were collected from adult patients treated operatively for a PFX between 2007 and 2010, using a specifically designed questionnaire. Quality of life before and after injury was also recorded using the EuroQol-5D health-outcome tool. RESULTS: 80 patients without pre-existing musculoskeletal disability were enrolled. The mean age was 44.9 years (18-65). The mean follow-up was 30.5 months (12-39). A decrease in level and frequency of sporting activity was observed. It was associated with lower-extremity associated injuries, but not with injury severity score, PFX severity, PFX type, age, or timing of follow-up. Sporting activity before injury predicted higher levels of sporting participation after injury. Decreased sporting activity after injury was associated with decreased EuroQol-SD score. CONCLUSIONS: Patients should be counselled on the likelihood of a reduction in sporting activities after surgically treated PFX. A larger multi-centre study is needed to further expand on the evidence of the true impact of PFX and its associated injuries on sporting activity.

Conductance switching in single molecules through conformational changes.

We tracked over time the conductance switching of single and bundled phenylene ethynylene oligomers isolated in matrices of alkanethiolate monolayers. The persistence times for isolated and bundled molecules in either the ON or OFF switch state range from seconds to tens of hours. When the surrounding matrix is well ordered, the rate at which the inserted molecules switch is low. Conversely, when the surrounding matrix is poorly ordered, the inserted molecules switch more often. We conclude that the switching is a result of conformational changes in the molecules or bundles, rather than electrostatic effects of charge transfer.

p53 mutation is a common genetic event in ovarian carcinoma.

Using the single-strand conformational polymorphism technique, we have screened 66 malignant ovarian tumors for p53 mutation in exons 5 to 8. Thirty-four of the tumors demonstrated a single-strand conformational polymorphism band shift in this region of the gene, including 6 in exon 5, 7 in exon 6, 12 in exon 7, and 10 in exon 8 (one of the tumors showed a shift for exons 7 and 8). All of the single-strand conformational polymorphism shifts have been further characterized by DNA sequencing, and 31 of 35 have been shown to represent genuine DNA alterations. These include 27 point mutations (23 missense, 2 nonsense, and 2 silent mutations), 3 deletions (a 2-base pair deletion introducing, by frameshift, a stop codon further downstream; a 3-base pair deletion; and an unusual 6-base pair deletion made up of separate 2-base pair and 4-base pair deletions), and a 4-base pair insertion (introducing a stop codon downstream). In total, 29 of the 66 (44%) carcinomas analyzed had mutations affecting the primary sequence of the p53 protein. p53 mutation was found in tumors of all International Federation of Gynecologists and Obstetricians stages, suggesting that it might be an earlier genetic event in the progression of epithelial ovarian tumors than previously thought. A significantly greater number of p53 mutations were seen in high-grade serous carcinomas than in those of endometrioid and mucinous types (0.02 > P > 0.01). Analysis of the distribution of point mutations showed no preference for any particular mutation type.

Effects of orthovanadate on salt and water effluxes from the gills of seawater eels, Anguilla anguilla.

Orthovanadate (5 . 10(-7) M) perfused through isolated gills at a constant rate increased the perfusion pressure by 40% but inhibited the effluxes of Na+ and Cl- by 40%. Water efflux was unaltered. Ouabain (10(-4) M) and rotenone (10(-4) M) influenced salt and water effluxes in the same way but did not alter perfusion pressures. Orthovanadate (10(-5) M) perfused at constant rate increased the pressure nearly 2.5-fold; under these conditions effluxes of Na+, Cl- and H2O were all increased approximately 2.5-fold.

Rapid diagnosis and identification of cross-over sites in patients with glucocorticoid remediable aldosteronism.

Glucocorticoid remediable aldosteronism (GRA) is an autosomal dominant cause of primary aldosteronism and high blood pressure resulting from a chimeric 11beta-hydroxylase/aldosterone synthase gene. Abnormal expression of aldosterone synthase causes primary aldosteronism, which can be inhibited by glucocorticoids. Diagnosis of GRA has depended on the identification of a restriction enzyme product in genomic DNA of affected individuals. Recently, a two-tube long PCR method was described that allowed diagnosis of GRA in a kindred in Australia. A similar long PCR method confirmed the diagnosis of GRA in members of five northeastern Scotland families previously identified by Southern blotting and detected affected members of five GRA families previously identified in Glasgow. A multiplex PCR protocol is described here that allows the control aldosterone synthase amplification and chimeric gene amplification to be carried out in the same tube. We describe the regions of cross-over in each of 10 kindreds identified in Scotland. To identify cross-over regions in each of the kindreds, the chimeric long PCR product was cloned and sequenced. Five cross-over sites were identified ranging from intron 2 to exon 4, indicating the reliability of the method in identifying chimeric genes resulting from different sites of cross-over.

In vitro antiproliferative activity of 4-substituted 2-(2-hydroxyphenyl)thiazolines on murine leukemia cells.

Two previously synthesized and two structurally novel thiazoline iron chelators are described. N4-Benzyl-N1,N8-bis[[2-(2-hydroxyphenyl)thiazolin-4-yl]carbonyl] homospermidine (5) proved to be the most potent antiproliferative and cytocidal compound in the series with in vitro IC50 values of 3 and 1 microM on L1210 and P388 murine cell lines. The N4-acetyl analogue 7 was considerably less active than 5 with IC50 and cell viability values that were similar to those of the structurally simple thiazolines 2 and 3. The antiproliferative activity of 3 and 7 could be substantially reduced or ablated by delivery to cell suspensions as a 1:1 molar mixture with FeCl3, while the activity of 5 was unaffected by Fe(III) chelation. As expected, 3 induced a G1/S cell cycle block at the 100 microM block consistent with interference with DNA synthesis while 10 microM 5 did not affect L1210 cell cycle distribution. Tritiated thymidine incorporation studies confirmed that 5 was incapable of interfering with DNA synthesis at concentrations below 40 microM. Alkaline elution studies indicate that 5 does not cause DNA strand breaks in vitro at concentrations of 10 microM. The N4-benzyl group of 5 appears to impart in vitro potency as the N4-acetyl analogue 7 lacks comparable in vitro antiproliferative and cytocidal activity.

Effects of oestrogen on the expression of a 4.4 kb mRNA in the ZR-75-1 human breast cancer cell line.

A cDNA library has been constructed from the poly(A)+ mRNA of oestrogen-stimulated ZR-75-1 human breast cancer cells. Screening by differential hybridization has identified eight clones which are stimulated between 4- and 16-fold by oestrogen. Two clones (pLIV-1) that are stimulated 4-fold, hybridize to three different mRNA species. A further five recombinants encode for a mRNA 600 bp long which is induced greater than 16-fold and have been shown to cross-hybridize to the oestrogen-responsive clone, pS2, isolated from the MCF-7 breast cancer cell line. Oestradiol was shown to be without detectable effect upon the expression of mRNA for dihydrofolate reductase, which is reported to be oestrogen regulated in MCF-7 cells. Actin gene expression is also unresponsive to oestradiol in ZR-75-1 cells. These results suggest that pLIV-1 represents a previously unidentified mRNA that may be involved in the oestrogen-regulated growth of ZR-75-1 human breast cancer cells.

In vitro antiproliferative activity of 2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylic acid and its methyl ester on L1210 and P388 murine neoplasms.

The activity of three iron chelators, methyl [2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylate] (MTL); 2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylic acid (TFAL); and 2-hydroxyphenyl-imido-ethyl-ether (Imidate), regarding antiproliferative, cytocidal, and cell-cycle effects are reported and compared with hydroxyurea (HU). In vitro, against L1210 and P388 murine neoplasms, MTL and TFAL displayed substantially greater antiproliferative activity than HU, although Imidate displayed no appreciable activity. MTL also induced a statistically more complete G1/S cell-boundary block than did HU at equimolar concentrations (100 microM). The IC50 values produced by MTL and TFAL were low enough (less than or equal to 20 microM) to warrant further testing of these chelators as potential antineoplastic agents.

The uptake from fresh water and subsequent clearance of a vanadium burden by the common eel (Anguilla anguilla).

The uptake of 48V vanadium from a solution of 10(-5) M 48V-orthovanadate by fresh-water elvers and the subsequent depletion of the vanadium burden was studied. At the end of the 8-week loading period, the levels of 48V were still increasing in the liver, kidney, bone and carcase. The uptake rate for the whole fish over the 8-week period was 760 pg atom/h/100 g body wt and the depletion rate over the following 5 weeks in clean water was about one tenth of this. Liver contained the highest amount of 48V at the end of the 8-week loading period, calculated as equivalent to 1.1 x 10(-4) g atom V/kg wet wt, and this level was unchanged at the end of the 5-week depletion period. Less than 1% of the carcase 48V was present in the fraction of MW under 2000.

Antenatal screening for carriers of cystic fibrosis: randomised trial of stepwise v couple screening.

OBJECTIVE: To perform a rigorous comparative evaluation of stepwise and couple approaches to antenatal carrier screening for cystic fibrosis. DESIGN: Pragmatic randomised trial. SETTING: Hospital antenatal clinic serving a regional population. SUBJECTS: 2002 women (couples) attending for booking antenatal visit at less than 17 weeks' gestation with no family history of cystic fibrosis. INTERVENTIONS: Offering counselling and carrier testing for cystic fibrosis, either to women in the first instance (stepwise) or to couples (couple screening). MAIN OUTCOME MEASURES: Uptake rates; anxiety; knowledge of cystic fibrosis and carrier status (both partners); attitudes to health, pregnancy, the baby, and screening (both partners); and uptake of carrier testing by relatives. RESULTS: Uptake of screening was the same for both approaches (90%). After delivery most women remembered test results and their meaning, but 53/253 (21%) of those with negative results of couple testing had forgotten that repeat testing would be advisable if they had a pregnancy with a new partner. With stepwise screening women identified as carriers had high levels of anxiety when results were received (mean anxiety score 52.3). This dissipated with a reassuring partner's result (carriers' mean anxiety score 36.1) to levels similar to those receiving negative results from couple screening. Of those receiving negative results, women who had stepwise screening were significantly less anxious than those who had couple screening (mean score with result 32.1 v 35.4, 95% confidence interval for difference -4.7 to -2.1). CONCLUSIONS: Couple screening allows carriers to avoid transient high levels of anxiety, but is associated with more anxiety and false reassurance among most screenees who will test negative. Stepwise screening gives carriers and their relatives genetic information and is, in our opinion, the better method.

The Scottish molecular genetics consortium--15 years on.

Remarkable advances have been made in recent years in our knowledge of the human genome. Genes for disorders such as Huntington disease, cystic fibrosis and Duchenne muscular dystrophy have been mapped and mutations identified. Simple molecular tests are now available for the diagnosis of these and many other conditions. As a result, in the last 15 years the whole new field of molecular pathology has been introduced to the Health Service of the United Kingdom and now there are nearly 40 diagnostic laboratories offering tests for a wide range of genetic disease. Scotland was at the forefront in the introduction of molecular diagnostics to Clinical Genetics Services and as early as 1985 plans were made to provide laboratories in Aberdeen, Dundee, Edinburgh and Glasgow. The four laboratories, the clinical genetics staff in each centre and the officials of the National Services Division now form the Scottish Molecular Genetics Consortium the objective of which is to provide testing for a wide range of disorders, to introduce new tests as genes are identified and to carry this out in a cooperative and coordinated manner.

Repeated freezing and thawing of peripheral blood and DNA in suspension: effects on DNA yield and integrity.

The possibility of DNA degradation is of concern to all involved in the storage of DNA, whether for diagnostic or research purposes. Many DNA banks are at present maintained at low temperatures, but optimum conditions for storage and handling have yet to be fully assessed. Both DNA and fresh blood have been subjected to repeated cycles of freezing and thawing and DNA extracted from the blood. DNA yield has been established and integrity examined by digestion, electrophoresis, and Southern blot analysis using DNA fingerprinting techniques. No degradation of DNA could be detected using these techniques; however, DNA yield was shown to be adversely affected by freezing, with yield reduced by more than 25% in blood samples frozen only once.

The transport of orthovanadate and similar oxyanions in relation to salt and water transport across the isolated intestine of the common eel, Anguilla anguilla.

An intestinal preparation from the common eel (Anguilla anguilla) was characterized for both mucosal to serosal and serosal to mucosal transport of water, alanine, sodium and chloride. The preparation showed a net outflux of water and a net influx of alanine, and no net fluxes of sodium or chloride. The influxes of all four substances and the outflux of water were inhibited by ouabain, while the outfluxes of alanine, sodium and chloride were increased by ouabain. Influxes and outfluxes of the oxyanions orthovanadate, phosphate, arsenate, sulphate, selenate and chromate were measured over a range of concentrations from 10(-8) M to 10(-4) M. The entry of each anion was dependent on the mucosal concentration, not saturable within the concentration range used or competitive with chloride. There were no net fluxes of these anions and pertechnecate from solutions containing equal mucosal and serosal concentrations of the anion.

Evaluation of laboratory methods for cystic fibrosis carrier screening: reliability, sensitivity, specificity, and costs.

We report a comparative evaluation of three different laboratory methods for screening large numbers of mouthwash DNA samples for common cystic fibrosis mutations. Sensitivity, specificity, and costs of ARMS (allele refractory mutation detection system), dot blotting, and a deletion/digest/PAGE method (multiplex PCR of exons 10 and 11, digest with HincII followed by polyacrylamide gel electrophoresis (PAGE)) were assessed. ARMS was the most reliable and sensitive method and so was considered more suitable than the cheaper deletion/digest/PAGE. As well as being less reliable than ARMS, the dot blotting method assessed was considerably more costly. ARMS was the best laboratory method for CF screening tested.

Linkage in a family with X-linked Charcot-Marie-Tooth disease.

The gene for the X-linked form of Charcot-Marie-Tooth disease (CMT Peroneal Muscular Atrophy, X-linked: McKusick No. 30280) has been shown in a single family to be linked to DXYS1 with a lod score of 4.55 at a recombination fraction of 0.03 and to PGK1 with a lod score of 3.34 at zero recombination. This is in agreement with previous work based on several families. Pooled data from this family and 7 previously reported families give a maximum lod score of 12.04 at theta max of 0.05 for linkage between CMTX and DXYS1 loci.

Thrombosis, markers of thrombotic risk, indwelling central venous catheters and antithrombotic prophylaxis using low-dose warfarin in subjects with malignant disease.

Markers of thrombotic risk--fibrinogen, factor VIII and immunoglobulin G (IgG) anticardiolipin titres--were measured, and the presence of lupus anticoagulant and factor V Leiden were assessed in 84 patients with a solid or haematological malignancy. These patients were monitored, following the insertion of an indwelling venous catheter, for thrombosis. Fifty-five were given prophylactic low-dose warfarin. Over a mean of 15 weeks there were 10 (12%) thrombotic events in 10 patients. Seven were on warfarin. Haemorrhagic problems occurred in three (5%), all on warfarin. Of the 84 patients, 86% had raised fibrinogen levels, 37% elevated factor VIII and 44% raised anticardiolipin levels. Lupus anticoagulant was present in five and three were heterozygous for factor V Leiden. A high prevalence of a range of prothrombotic changes was confirmed and the frequent presence of low-titre anticardiolipin antibody in subjects with malignancy demonstrated. However, none of these parameters predicted the development of thrombosis (P > 0.05).