Phospholipid-mediated exfoliation as a facile preparation method for graphene suspensions

This paper deals with simple, inexpensive and ‘green’ methods of production for graphene in colloidal dispersion. Herein, we report on such a method by preparing aqueous graphene dispersions via ultrasonic exfoliation in the presence of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). The product predominantly consists of few-layer graphene flakes coated by DOPC with a lateral size of a few tens to hundreds of nm, as confirmed by Raman and X-ray photoelectron spectroscopies, thermogravimetric analysis (TGA), dynamic light scattering (DLS) and atomic force microscopy (AFM). The novelty of this method lies in its dependence on a typical soft matter property: the fluidity of the hydrophobic chains. Stiffer phospholipids such as 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC, which possesses two palmitoyl chains) or 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphocholine (POPC, one palmitoyl, one oleyl chain) are ineffective at dispersing graphene; however, in the presence of cholesterol these phospholipids also become effective mediators. The phospholipid coating renders the flakes compatible with biological environments.

A simple, inexpensive and ‘green’ method of production for graphene in colloidal dispersion.     

Point-of-care assays for autoantibodies to thyroid peroxidase and to thyroglobulin.

Point-of-care (POC) assays for autoantibodies to thyroid peroxidase (TPOAb) and to thyroglobulin (TgAb) are described. Both assays are based on the ability of autoantibodies in test samples (whole blood, plasma, or sera) to inhibit the binding of monoclonal antibodies to TPO or to Tg. The assays require no special equipment and give results in 10 minutes. Analysis of samples from healthy blood donors (n = 80), patients with autoimmune thyroid disease (n = 97) and nonthyroid autoimmune diseases (n = 20) showed that results with the POC tests compared well to those obtained by agglutination assay and enzyme-linked immunosorbent assay (ELISA). The reference immunoprecipitation assays (IPA) based on 125I-labeled TPO or Tg were more sensitive than the POC tests particularly in the case of TgAb measurements. However, no samples were found positive by POC test and negative by IPA emphasizing the high specificity of the POC assays. Our results suggest that POC testing for TPOAb and TgAb with assays such as those we describe could be useful in certain situations. These include prediction of postpartum thyroiditis and the development of interferon-alpha-related thyroid disease.     

Drug controlled of Cushing's syndrome. Combined aminoglutethimide and metyrapone therapy.

Eighteen patients with Cushing's syndrome (16 pituitary-dependent Cushing's disease, 1 ectopic ACTH syndrome, 1 primary adrenal adenoma) were given a combination of aminoglutethimide and metyrapone, with the object of controlling cortisol overproduction using less toxic doses than would be required with each drug alone. A preliminary trial of this combination using doses of aminoglutethimide of 1 g or more a day was assessed over 2 weeks. Control of cortisol overproduction and clinical improvement was achieved but side effects led to withdrawal of the drugs in 6 out of the 12 patients. A lower dose trial of this combination over 2 weeks, using 750 mg/day of aminoglutethimide also controlled cortisol overproduction and side effects led to drug withdrawal in only 2 out of 6 patients. Four of these patients were successfully controlled with even lower doses (500-750 mg/day of aminoglutethimide) for longer periods (26 days-1 year). This low regimen which consists of aminoglutethimide 500-750 mg daily, metyrapone 2 g daily, dexamethasone 0.5 mg b.d. and fludrocortisone 0.1 mg daily, is useful for preparing patients for operative treatments and may be used as a long-term treatment of milder cases.     

Fatal aortic rupture during balloon dilatation of recoarctation.

In an eight year old boy with a patch aortoplasty, the aorta ruptured during balloon angioplasty for recoarctation. At necropsy a 1.5 cm long, full thickness tear and a separate, smaller, intimal tear were found. Histological examination showed thinning of the elastic laminae of the aorta. Angioplasty for recoarctation may be dangerous in patients with a patch aortoplasty.     

Human monoclonal thyroid stimulating autoantibody

A monoclonal autoantibody (MAb) with powerful thyroid stimulating activity has been produced from lymphocytes from a patient with Graves' disease. The autoantibody and its Fab fragment bind to the thyroid stimulating hormone (TSH) receptor (TSHR) with high affinity, inhibit labelled TSH binding to the receptor and stimulate cyclic AMP production in Chinese hamster ovary cells transfected with TSHR. TSHR autoantibodies with TSH agonist or antagonist activities from patients' serum samples are effective inhibitors of labelled monoclonal autoantibody binding to TSHR. Thus, the human monoclonal autoantibody has all the characteristics of serum TSHR autoantibodies. Its availability has important implications for new studies on the pathogenesis of Graves' disease.     

Regional aortic compliance studied by magnetic resonance imaging: the effects of age, training, and coronary artery disease.

Arterial compliance was measured in 70 healthy volunteers, 13 athletes, and 17 patients with coronary artery disease. Magnetic resonance images were acquired at end diastole and end systole through the ascending aorta, the aortic arch, and the descending thoracic aorta. Regional compliance was derived from the change in luminal area in a slice of known thickness and from the pulse pressure. Total arterial compliance was also measured from the left ventricular stroke volume and the pulse pressure. In the volunteers, mean (SD) regional compliance (microliters/mm Hg) was greatest in the ascending aorta (37 (18], lower in the arch (31 (15], and lowest in the descending aorta (18 (8], and it decreased with age. Compliance in the athletes was significantly higher than in their age matched controls (41 (16) versus 22 (11) microliters/mm Hg). In the patients with coronary artery disease it was significantly lower (12 (4) v 18 (10] than in age matched controls. Total arterial compliance also fell with age in those with coronary artery disease although there was more variation. The results suggest a possible role for compliance in the assessment of cardiovascular fitness and the detection of coronary artery disease.     

Hyperprolactinemia--a review of recent clinical advances

Since the radioimmunoassay for serum prolactin became available eight years ago, prolactin has become a hormone of considerable clinical interest. An elevated serum prolactin concentration is the most frequent hormone marker for pituitary tumors. Secreted in excess, prolactin causes dysfunction of the hypothalamic-pituitary axis, the gonads, and the adrenal cortex. In women, menstrual disturbances, galactorrhea, infertility, and hirsutism result. Impotence, oligospermia, and decreased libido are common in men. These metabolic abnormalities attributed to prolactin excess are corrected when prolactin concentrations are lowered by either medical or surgical therapy. The availability of effective therapy mandates early recognition and proper management of the patient with hyperprolactinemia.     

The self-priming action of LHRH increases the low pituitary LH and FSH response caused by ovarian factors: observations in vitro

Pituitary glands taken from intact rats on day 2 of dioestrus and incubated with LHRH show a biphasic pattern of LH and FSH release. Initially the release of the gonadotrophins is low (first-phase or lag-phase response), but increases during further incubation with LHRH (second-phase or primed-state response). Removal of the influence of an unidentified ovarian factor either by ovariectomy or prolonged incubation in medium only leads to an increased (lag-phase) response to LHRH. The development of the increased response after prolonged incubation was prevented by the addition of cycloheximide to the media, implicating that this process is dependent upon the synthesis of protein. Steroid-free material (bovine follicular fluid or rat ovarian extracts) prevented the development of this process. In addition, it was shown that steroid-free rat ovarian extracts were also able to induce the development of a lag phase in pituitary glands from ovariectomized rats. Finally, it was found that steroid-free ovarian extracts reversed the self-priming effect of LHRH. The biological activity which reduced the responsiveness of the pituitary gland towards stimulation by LHRH was eliminated after the use of protein-denaturating techniques such as increased temperature or addition of methanol. The presence of this activity in ovaries, did not vary during the oestrous cycle, contrary to inhibin-like activity. Hence the ovarian factor responsible for the low lag-phase response is a protein which is probably not identical to inhibin. It is concluded that a non-steroidal ovarian factor reduces the responsiveness of the anterior pituitary gland to LHRH.(ABSTRACT TRUNCATED AT 250 WORDS)     

Do patients with moderately impaired gastrointestinal function requiring enteral nutrition need a predigested nitrogen source? A prospective crossover controlled clinical trial.

This prospective double blind randomised seven day crossover controlled clinical trial was carried out to determine whether enterally fed patients with moderately impaired gastrointestinal function require a predigested nitrogen (N) source compared with whole protein. Twelve malnourished patients with varying gastrointestinal abnormalities, who required enteral feeding, received 2.25 l of one of two isocaloric isonitrogenous enteral diets (1 kcal/ml, 4.8 g nitrogen/l) containing either predominantly medium chain peptides (tetra or higher peptides) or whole protein as the nitrogen source. Nitrogen absorption and balance were calculated from dietary intake and analysis of 24 hour total urinary and faecal nitrogen for the last five days of each study period. There was no significant difference in either stool weight (110 (SEM) (49) v 111 (32) g/d), nitrogen absorption (91 (2) v 89 (2)%) or nitrogen balance (+1.0 (1.3) v +0.6 (1.4) g nitrogen/d) between the peptide and whole protein nitrogen sources when all patients are considered. There was, however, evidence to suggest a nutritional advantage from administering an enteral diet whose nitrogen source comprises oligopeptides, rather than whole protein, to a subgroup of patients with small bowel disease.