Simultaneous Stress and Field Control of Sustainable Switching of Ferroelectric Phases

In ferroelectrics, manifestation of a strong electromechanical coupling is attributed to both engineered domain morphology and phase transformations. However, realization of large sustainable and reversible strains and polarization rotation has been limited by fatigue, nonlinearity and hysteresis losses. Here, we demonstrate that large strain and polarization rotation can be generated for over 40 × 10⁶ cycles with little fatigue by realization of a reversible ferroelectric-ferroelectric phase transition in [011] cut Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PMN-PT) relaxor ferroelectric single crystal. Direct tuning of this effect through combination of stress and applied electric field, confirmed both macroscopically and microscopically with x-ray and Raman scattering, reveals the local symmetry while sweeping through the transition with a low applied electric field (<0.2 MV/m) under mechanical stress. The observed change in local symmetry as determined by x-ray scattering confirms a proposed polarization rotation mechanism corresponding to a transition between rhombohedral and orthorhombic phases. These results shed more light onto the nature of this reversible transformation between two ferroelectric phases and advance towards the development of a wide range of ferroic and multiferroic devices.

Background elimination and interferometric capability in optical coherence tomography by a nonlinear optical gating based on type-II second-harmonic generation

A novel method that uses nonlinear optical gating to control background illumination in optical coherence tomography is presented. With this method, the user can adjust the amount of undesired backscattering or eliminate it completely, which enables dark-field measurements. The interferometric capability of the method in a nonlinear optical regime is demonstrated with the coupling of three overlapping input waves to yield Fizeau fringes. The measurement of a 265 nm step is performed to validate this method, which was originally conceived for 3D MEMS characterization.

L-cysteine suppresses ghrelin and reduces appetite in rodents and humans

BACKGROUND

High-protein diets promote weight loss and subsequent weight maintenance, but are difficult to adhere to. The mechanisms by which protein exerts these effects remain unclear. However, the amino acids produced by protein digestion may have a role in driving protein-induced satiety.

METHODS

We tested the effects of a range of amino acids on food intake in rodents and identified l-cysteine as the most anorexigenic. Using rodents we further studied the effect of l-cysteine on food intake, behaviour and energy expenditure. We proceeded to investigate its effect on neuronal activation in the hypothalamus and brainstem before investigating its effect on gastric emptying and gut hormone release. The effect of l-cysteine on appetite scores and gut hormone release was then investigated in humans.

RESULTS

l-Cysteine dose-dependently decreased food intake in both rats and mice following oral gavage and intraperitoneal administration. This effect did not appear to be secondary to behavioural or aversive side effects. l-Cysteine increased neuronal activation in the area postrema and delayed gastric emptying. It suppressed plasma acyl ghrelin levels and did not reduce food intake in transgenic ghrelin-overexpressing mice. Repeated l-cysteine administration decreased food intake in rats and obese mice. l-Cysteine reduced hunger and plasma acyl ghrelin levels in humans.

CONCLUSIONS

Further work is required to determine the chronic effect of l-cysteine in rodents and humans on appetite and body weight, and whether l-cysteine contributes towards protein-induced satiety.

Fragility fractures of the ankle in the frail elderly patient

Conventional methods of treating ankle fractures in the elderly are associated with high rates of complication. We describe the results of treating these injuries in 48 frail elderly patients with a long calcaneotalotibial nail.

The mean age of the group was 82 years (61 to 96) and 41 (85%) were women. All were frail, with multiple medical comorbidities and their mean American Society of Anaesthesiologists score was 3 (3 to 4). None could walk independently before their operation. All the fractures were displaced and unstable; the majority (94%, 45 of 48) were low-energy injuries and 40% (19 of 48) were open.

The overall mortality at six months was 35%. Of the surviving patients, 90% returned to their pre-injury level of function. The mean pre- and post-operative Olerud and Molander questionnaire scores were 62 and 57 respectively. Complications included superficial infection (4%, two of 48); deep infection (2%, one of 48); a broken or loose distal locking screw (6%, three of 48); valgus malunion (4%, two of 48); and one below-knee amputation following an unsuccessful vascular operation. There were no cases of nonunion, nail breakage or peri-prosthetic fracture.

A calcaneotalotibial nail is an excellent device for treating an unstable fracture of the ankle in the frail elderly patient. It allows the patient to mobilise immediately and minimises the risk of bone or wound problems. A long nail which crosses the isthmus of the tibia avoids the risk of peri-prosthetic fracture associated with shorter devices.

Cite this article: Bone Joint J 2014; 96-B:817–22.

Hepcidin levels in diabetes mellitus and polycystic ovary syndrome

AIM

Increased body iron is associated with insulin resistance. Hepcidin is the key hormone that negatively regulates iron homeostasis. We hypothesized that individuals with insulin resistance have inadequate hepcidin levels for their iron load.

METHODS

Serum concentrations of the active form of hepcidin (hepcidin-25) and hepcidin:ferritin ratio were evaluated in participants with Type 2 diabetes (n = 33, control subjects matched for age, gender and BMI, n = 33) and participants with polycystic ovary syndrome (n = 27, control subjects matched for age and BMI, n = 16). To investigate whether any changes observed were associated with insulin resistance rather than insulin deficiency or hyperglycaemia per se, the same measurements were made in participants with Type 1 diabetes (n = 28, control subjects matched for age, gender and BMI, n = 30). Finally, the relationship between homeostasis model assessment of insulin resistance and serum hepcidin:ferritin ratio was explored in overweight or obese participants without diabetes (n = 16).

RESULTS

Participants with Type 2 diabetes had significantly lower hepcidin and hepcidin:ferritin ratio than control subjects (P < 0.05 and P < 0.01, respectively). Participants with polycystic ovary syndrome had a significantly lower hepcidin:ferritin ratio than control subjects (P < 0.05). There was no significant difference in hepcidin or hepcidin:ferritin ratio between participants with Type 1 diabetes and control subjects (P = 0.88 and P = 0.94). Serum hepcidin:ferritin ratio inversely correlated with homeostasis model assessment of insulin resistance (r = -0.59, P < 0.05).

CONCLUSION

Insulin resistance, but not insulin deficiency or hyperglycaemia per se, is associated with inadequate hepcidin levels. Reduced hepcidin concentrations may cause increased body iron stores in insulin-resistant states.

Lancefield group G Streptococcus dysgalactiae subsp. equisimilis: an unusual aetiology of perianal streptococcal dermatitis acquired from heterosexual oral-anal intercourse

Perianal streptococcal dermatitis (PSD) is an uncommon superficial cutaneous infection of the perianal area, almost exclusively described in children and mainly caused by group A streptococci. We report here a case of PSD caused by Streptococcus dysgalactiae subsp. equisimilis, Lancefield group G, in an adult man due to heterosexual oral-anal sexual contact.

[Raman spectroscopy applied to analytical quality control of injectable drugs: analytical evaluation and comparative economic versus HPLC and UV / visible-FTIR]

In France, central IV admixture of chemotherapy (CT) treatments at the hospital is now required by law. We have previously shown that the shaping of Therapeutic Objects (TOs) could profit from an Analytical Quality Assurance (AQA), closely linked to the batch release, for the three key parameters: identity, purity, and initial concentration of the compound of interest. In the course of recent and diversified works, we showed the technical superiority of non-intrusive Raman Spectroscopy (RS) vs. any other analytical option and, especially for both HPLC and vibrational method using a UV/visible-FTIR coupling. An interconnected qualitative and economic assessment strongly helps to enrich these relevant works. The study compares in operational situation, the performance of three analytical methods used for the AQC of TOs. We used: a) a set of evaluation criteria, b) the depreciation tables of the machinery, c) the cost of disposables, d) the weight of equipment and technical installations, e) the basic accounting unit (unit of work) and its composite costs (Euros), which vary according to the technical options, the weight of both human resources and disposables; finally, different combinations are described. So, the unit of work can take 12 different values between 1 and 5.5 Euros, and we provide various recommendations. A qualitative evaluation grid constantly places the SR technology as superior or equal to the 2 other techniques currently available. Our results demonstrated: a) the major interest of the non-intrusive AQC performed by RS, especially when it is not possible to analyze a TO with existing methods e.g. elastomeric portable pumps, and b) the high potential for this technique to be a strong contributor to the security of the medication circuit, and to fight the iatrogenic effects of drugs especially in the hospital. It also contributes to the protection of all actors in healthcare and of their working environment.