Conductive composite fibres from reduced graphene oxide and polypyrrole nanoparticles.

Continuous composite fibres composed of polypyrrole (PPy) nanoparticles and reduced graphene oxide (rGO) at different mass ratios were fabricated using a single step wet-spinning approach. The electrical conductivity of the composite fibres increased significantly with the addition of rGO. The mechanical properties of the composite fibres also improved by the addition of rGO sheets compared to fibres containing only PPy. The ultimate tensile strength of the fibres increased with the proportion of rGO mass present. The elongation at break was greatest for the composite fibre containing equal mass ratios of PPy nanoparticles and rGO sheets. L929 fibroblasts seeded onto fibres showed no reduction in cell viability. To further assess toxicity, cells were exposed to media that had been used to extract any aqueous-soluble leachates from developed fibre. Overall, these composite fibres show promising mechanical and electrical properties while not significantly impeding cell growth, opening up a wide range of potential applications including nerve and muscle regeneration studies.

Processable conducting graphene/chitosan hydrogels for tissue engineering.

Composites of graphene in a chitosan-lactic acid matrix were prepared to create conductive hydrogels that are processable, exhibit tunable swelling properties and show excellent biocompatibility. The addition of graphene to the polymer matrix also resulted in significant improvements to the mechanical strength of the hydrogels, with the addition of just 3 wt% graphene resulting in tensile strengths increasing by over 200%. The composites could be easily processed into three-dimensional scaffolds with finely controlled dimensions using additive fabrication techniques and fibroblast cells demonstrate good adhesion and growth on their surfaces. These chitosan-graphene composites show great promise for use as conducting substrates for the growth of electro-responsive cells in tissue engineering.

Biocompatibility of choline salts as crosslinking agents for collagen based biomaterials.

A series of novel choline based salts, some of which can be described as ionic liquids, are prepared and evaluated for their biocompatibility; when combined with collagenous biomaterials they exhibit good cell viability and adhesion properties as required for biomedical implant applications.

Muscle strength and pressor response.

The purpose of this study was to determine if muscle strength influences the hyperemic response to dynamic exercise. Men with low (n=8) and high (n=9) maximal forearm strength performed dynamic handgrip exercise as the same absolute workload increased in a ramp function (0.5 kg x min (-1)). Forearm blood flow (FBF) was measured instantaneously by ultrasound Doppler and blood pressure was measured by auscultation. The pressor response to exercise was greater (P<0.05) for low strength men at workloads >1.5 kg allowing volumetric FBF (ml x min (-1)) and vascular conductance to increase in proportion to absolute workload similar to high strength men. When FBF was expressed relative to forearm volume (ml x min (-1).100 ml (-1)) the hyperemic response to exercise (slope of relative FBF vs. workload) was greater in low strength men (3.2+/-1.5 vs. 1.7+/-0.4 ml x min (-1).100 ml (-1) x kg (-1), P<0.05) as was relative FBF at workloads >1.5 kg. However, when relative FBF was compared across relative work intensity, no difference was found between low and high strength groups. Together, these findings suggest men with low strength require a greater pressor response to match blood flow to exercise intensity as compared to high strength men.

Pregnancy in renal transplant recipients: the Royal Free Hospital experience.

BACKGROUND: For women with end-stage renal failure of child-bearing age, renal transplantation offers a chance to start a family. Pregnancies in renal transplant recipients involve risks for graft and fetus, and need to be carefully managed. AIM: To identify graft, fetal and maternal outcomes in our patients, and compare our results with those of the large national transplant registries. DESIGN: Retrospective case-note review. METHODS: We assessed the outcomes of 48 pregnancies in 24 renal transplant recipients. Obstetric data and renal parameters were examined in 27-30 pregnancies that progressed to delivery. RESULTS: Mean time from transplantation to pregnancy was 6.5 years, with an unfavourable outcome in patients who conceived within 1 year. There was a 41% incidence of fetal growth restriction (FGR), and 33% of infants were small for gestational age. FGR was associated with maternal hypertension, a pre-pregnancy serum creatinine (SCr) >/= 133 micro mol/l (1.5 mg/dl), calcineurin inhibitors and the use of cardioselective beta blockers. Two patients with pre-pregnancy SCr > 200 micro mol/l lost their grafts within 3 years of delivery. A permanent significant decline in graft function occurred in 20%, by 6 months post delivery. DISCUSSION: FGR with SGA infants occurs frequently. Atenolol should be avoided in pregnancy and Metoprolol should not be combined with calcineurin inhibitors. Pregnancy appeared to have a deleterious effect on graft function in patients with SCr > 155 micro mol (1.75 mg/dl). Patients with pre-pregnancy SCr 200 micro mol/l are at greatest risk.

Analysis of pesticide runoff from mid-Texas estuaries and risk assessment implications for marine phytoplankton.

During 1993, estuarine surface water samples were collected from the mid-Texas coast (Corpus Christi to Port Lavaca, TX). Agricultural watershed areas as well as tidal creeks immediately downstream were chosen as sampling sites along with adjoining bay sampling stations. Collections were made throughout the growing season (February to October 1993) before and after periods of significant (> 1.25 cm) rainfall. All samples were initially screened for the presence of pesticides using enzyme-linked immunosorbent assay (ELISA) test kits (EnviroGard) for triazine herbicides and carbamate insecticides. All samples were extracted and then analyzed using gas chromatography (GC) for quantification of atrazine. Only samples testing positive for carbamate insecticides via ELISA were further extracted for GC analysis to quantify aldicarb and carbofuran. Additionally, laboratory toxicity tests using phytoplankton were examined from published, peer-reviewed literature and compared with the atrazine field levels found in Texas. Results of ELISA screening indicated the presence of triazine herbicides in nearly all samples (>93%). GC analysis further confirmed the presence of atrazine concentrations ranging from <0.01-62.5 microg/L. Screening tests also found detectable levels of carbamate insecticides (aldicarb and carbofuran) that were also confirmed and quantified by GC. Comparison of measured concentrations of atrazine compared with published toxicity tests results indicated that there was a potential environmental risk for marine/estuarine phytoplankton in surface waters of Texas estuaries, particularly when the chronic nature of atrazine exposure is considered.

Post-mortem calpain-system kinetics in lamb: Effects of clenbuterol and preslaughter exercise.

The effect of dietary supplementation with clenbuterol for either 8 days or 55 days in lambs was studied. The 55-day treatment was combined with an immediate preslaughter exercise regime. The effect of these treatments on post-mortem calpain system activities, meat ageing and meat quality was studied. Neither short-nor long-term supplementation had an effect on the rate of pH fall post mortem. Short-term supplementation had no effect on the initial nor the final shear force values but these were higher at intermediate times. In contrast, prolonged supplementation increased shear force values at all times post mortem. Preslaughter exercise, while influencing the rate of pH decrease in both control and supplemented groups, did not affect meat tenderness. After short-term clenbuterol-supplementation, the in-vitro µ-calpain activity was significantly lower in the supplemented group at 6 and 24 hr post mortem, while m-calpain and calpastatin activities were largely unaffected. In contrast, 55-day clenbuterol supplementation resulted in significantly higher levels of calpastatin activity at all times post mortem. These data imply that clenbuterol results in toughened meat due to alterations in the calpain/calpastatin system, the mechanisms of which are dependent upon the duration of supplementation.

Accidental poisonings involving carbon monoxide, heating systems, and confined spaces.

Eleven incidents of carbon monoxide (CO) intoxication resulting in sixteen fatalities are reported. All of the cases involved heating systems as either the source or the means of distributing the CO. Blood samples were analyzed for ethanol and CO. Elevated blood CO saturations were found in 14 of the 16 victims while none of the victims had a blood ethanol concentration greater than 0.10% (w/v).

Factors affecting the binding of disopyramide to serum proteins.

We investigated the influence of the following factors on the binding of disopyramide to serum proteins: method of drug quantification [enzyme immunoassay (EMIT) compared with liquid chromatography (HPLC)], separation technique (ultrafiltration vs equilibrium dialysis), temperature, pH, and total concentration of disopyramide. EMIT and HPLC measurements of disopyramide in ultrafiltrates prepared from 50 sera agreed well: EMIT = 1.046 HPLC + 0.042, (r = 0.928, SEE = 0.04 mg/L). Free disopyramide concentrations in ultrafiltrates of dialyzed sera were similar to those measured in the corresponding dialysates by the EMIT method for 30 patients' sera: ultrafiltrate of serum retentate = 1.053 dialysate + 0.042. Concentrations of free [14C]disopyramide were little affected by temperature. The concentration of free disopyramide decreased as the pH was increased from 7.0 to 7.8. The concentration of free disopyramide, as determined by ultrafiltration, is strongly and directly related to total drug concentration. In the sera of 50 cardiac patients receiving chronic therapy with disopyramide and with total disopyramide concentrations of 0.5 to 5.8 mg/L, the proportion of free disopyramide ranged from 16 to 54%.

A fatal overdose with colchicine.

A colchicine blood concentration 250 microgram/L was determined in a 39-year-old white female 2 hours following the ingestion of an oral overdose of the drug. At death, 40 hours following ingestion, no drug was detected. Colchicine was extracted from buffered blood using dichloromethane. The evaporated extract was redissolved in 0.1 N HCl and analyzed using a high performance liquid chromatograph equipped with an octadecylsilane reversed phase column.

Detection of drugs using XAD-2 resin. III:A routine screening procedure for bile.

The ability of bile to concentrate drugs and metabolites coupled with its general availability make it suitable for analysis and often the fluid of choice in postmorten cases requiring drug screening. Bile (5 to 10 ml) was diluted with water, sulfuric acid was added, and the mixture was autoclaved. The precipitated bile salts were easily removed by filtration and the filtrate (pH adjusted to 8.0 to 8.5) extracted with XAD-2 resin. Drugs were eluted with a mixture of ethyl acetate/1,2-dichloroethane and analyzed with thin-layer chromatography. Varying the dilution of bile improved the recovery of morphine, codeine, methadone, amobarbital, and phenobarbital. Excessive dilution, however, caused a washing phenomenon and reduced recovery of some drugs, as shown with morphine and codeine. The procedure described is useful for the rapid screening of bile specimens for drugs.

A congenital oesophagotracheal fistula in a two-year-old dog.

A congenital oesophagotracheal fistula in a two-year-old dog is reported. An account is given of the clinical symptoms, radiographic appearance, the supportive therapy, surgical correction and the post mortem findings.

Scattered and reflected light intensities above the atmosphere.

A calculational method is described that was developed for use in predicting the angular distribution of the upwelling flux of sunlight scattered by the atmosphere and reflected by the ground. Monte Carlo calculations of the radiation escaping the top of a plane-parallel model atmosphere were used as input in a computer procedure that integrates the reflected intensities over the sunlit portion of the top of the earth's atmosphere, which is visible by a receiver located on a spacecraft. Calculations were performed for a model maritime atmosphere, with and without low-altitude cloud layer, and a model continental atmosphere, which includes treatment of the effects of aerosol, Rayleigh scattering, and ozone absorption. The ground surface was assumed to be a Lambert reflector. The results of the Monte Carlo calculation for five wavelengths between 370 nm and 780 nm were compared with measured data from the Ames Research Center earth albedo experiment on the OSO-3 satellite. Agreement between calculated and measured values was sufficiently good to warrant the conclusion that reasonable estimates of the angular distribution of the radiation reaching a near-earth spacecraft from different atmospheric conditions could be calculated.