Magnetoelastic Effects in Doubly Clamped Electroplated Co77Fe23 Microbeam Resonators.

Magnetostrictive Co77Fe23 films are fully suspended to produce free-standing, clamped-clamped, microbeam resonators. A negative or positive shift in the resonant frequency is observed for magnetic fields applied parallel or perpendicular to the length of the beam, respectively, confirming the magnetoelastic nature of the shift. Notably, the resonance shifts linearly with higher-bias fields oriented perpendicular to the beam's length. Domain imaging elucidates the distinction in the reversal processes along the easy and hard axes. Together, these results suggest that through modification of the magnetic anisotropy, the frequency shift and angular dependence can be tuned, producing highly magnetic-field-sensitive resonators.

SpyRings Declassified: A Blueprint for Using Isopeptide-Mediated Cyclization to Enhance Enzyme Thermal Resilience.

Enzymes often have marginal stability, with unfolding typically leading to irreversible denaturation. This sensitivity is a major barrier, both for de novo enzyme development and for expanding enzyme impact beyond the laboratory. Seeking an approach to enhance resilience to denaturation that could be applied to a range of different enzymes, we developed SpyRing cyclization. SpyRings contain genetically encoded SpyTag (13 amino acids) on the N-terminus and SpyCatcher (12kDa) on the C-terminus of the enzyme, so that the Spy partners spontaneously react together through an irreversible isopeptide bond. SpyRing cyclization gave major increases in thermal resilience, including on a model for enzyme evolution, ß-lactamase, and an industrially important enzyme in agriculture and nutrition, phytase. We outline the SpyRing rationale, including comparison of SpyRing cyclization to other cyclization strategies. The cloning strategy is presented for the simple insertion of enzyme genes for recombinant expression. We discuss structure-based approaches to select suitable enzyme cyclization targets. Approaches to evaluate the cyclization reaction and its effect on enzyme resilience are described. We also highlight the use of differential scanning calorimetry to understand how SpyRing cyclization promotes enzyme refolding. Efficiently searching sequence space will continue to be important for enzyme improvement, but the SpyRing platform may be a valuable rational adjunct for conferring resilience.

Giant Controllable Magnetization Changes Induced by Structural Phase Transitions in a Metamagnetic Artificial Multiferroic.

The realization of a controllable metamagnetic transition from AFM to FM ordering would open the door to a plethora of new spintronics based devices that, rather than reorienting spins in a ferromagnet, harness direct control of a materials intrinsic magnetic ordering. In this study FeRh films with drastically reduced transition temperatures and a large magneto-thermal hysteresis were produced for magnetocaloric and spintronics applications. Remarkably, giant controllable magnetization changes (measured to be as high has ~25%) are realized by manipulating the strain transfer from the external lattice when subjected to two structural phase transitions of BaTiO3 (001) single crystal substrate. These magnetization changes are the largest seen to date to be controllably induced in the FeRh system. Using polarized neutron reflectometry we reveal how just a slight in plane surface strain change at ~290C results in a massive magnetic transformation in the bottom half of the film clearly demonstrating a strong lattice-spin coupling in FeRh. By means of these substrate induced strain changes we show a way to reproducibly explore the effects of temperature and strain on the relative stabilities of the FM and AFM phases in multi-domain metamagnetic systems. This study also demonstrates for the first time the depth dependent nature of a controllable magnetic order using strain in an artificial multiferroic heterostructure.

Direct evidence of anomalous interfacial magnetization in metamagnetic Pd doped FeRh thin films.

Palladium doped iron rhodium is a magnetic material of significant interest for it's close to room temperature magnetostructural phase transition from antiferromagnetic (AF) to ferromagnetic (FM) ordering. Here we report on the peculiarities of the magnetization distribution in thin films of FeRh(Pd) probed by Polarized Neutron Reflectometry. Remarkably, we've found thin interfacial regions with strong magnetization that have unique thermomagnetic properties as compared to the rest of the system. These regions exist at the top and bottom interfaces of the films while the central regions behave similarly to the bulk with a clear AF-FM order transition. Further we explore the impact of an additional Pt interlayer introduced in the middle of the FeRh(Pd) film and reveal that it serves to replicate the strong interfacial magnetization found at the top and bottom interfaces. These results are of great value both in understanding the fundamental physics of such an order transition, and in considering FeRh(Pd) for magnetic media and spintronics applications.

Liver metastases from breast cancer: Surgical resection or not? A case-matched control study in highly selected patients.

AIM: To determine whether, in a highly selected patient population, medical treatment combined with surgical resection of liver metastases from breast cancer is associated with improved survival compared with medical treatment alone. PATIENTS AND METHODS: Between 1988 and 2007, 100 liver resections for metastatic breast cancer were performed at Institut Curie, 51 of which met the criteria for inclusion in this case-control study. With the exception of bone metastases, patients with other distant metastasis sites were excluded. Surgery was only performed in patients with stable disease or disease responding to medical treatment evaluated by imaging evaluation. Surgical cases were individually matched with 51 patients receiving medical treatment only. All patients had 4 or fewer resectable liver metastases. The study group was matched with the control group for age, year of breast cancer diagnosis, time to metastasis, TNM stage, hormone receptor status and breast cancer tumour pathology. RESULTS: Univariate analysis confirmed a survival advantage for patients lacking bone metastases and axillary lymphadenopathy at the time of breast cancer diagnosis and for surgically treated patients. Multivariate analysis indicated that surgery and the absence of bone metastases were associated with a better prognosis. A multivariate Cox model adapted for paired data showed a RR = 3.04 (CI: 1.87-4.92) (p < 0.0001) in favour of surgical treatment. CONCLUSION: Surgical resection of liver metastases from primary breast cancer appears to provide a survival benefit for highly selected patients.

Management of exposed, infected implant-based breast reconstruction and strategies for salvage.

INTRODUCTION: Complications of implant-based breast reconstruction are rare but mastectomy flap necrosis and peri-implant infection are the most frequent and remain an important cause of early implant failure. This study aimed to compare the results of three different management strategies employed to deal with these complications at our institution. PATIENTS AND METHODS: A consecutive series of 71 infected/exposed prostheses in 68 patients over a 20-year period were analysed. Management strategies included explantation and delayed reconstruction, implant salvage and explantation and immediate autologous reconstruction. RESULTS: Only 19 of 45 (42%), managed with implant removal, went on to delayed reconstruction. Methods of delayed reconstruction were distributed equally between implant-only, implant and autologous tissue and autologous-only reconstructions. The implant was successfully salvaged in nine cases, but reducing the implant size or introducing new tissue as a flap increased the success from 45% to 53%. Three patients with infected implant-only breast reconstruction underwent explantation and immediate conversion to autologous-only reconstructions. CONCLUSIONS: All the three interventions reviewed here have their place in the management of infected implant-based breast reconstructions. It is noteworthy that following implant removal, the likelihood of the patient proceeding to delayed reconstruction of any kind is similar to the likelihood of successful salvage (42% vs. 45%). This study population had high numbers of exposed implants in irradiated fields. Reducing implant size or introducing new tissue in the form of a flap increases the chances of successful implant salvage. In the presence of mild infection, removal of exposed/infected implants and immediate conversion to an autologous-only reconstruction can prove to be successful.

Inhalation injury associated with smoking, alcohol and drug abuse: an increasing problem.

This study investigated the association of inhalation injury (IHI) with smoking, alcohol and drug abuse in patients admitted to the Welsh Centre for Burns between 1995 and 2006. Common characteristics of these individuals were identified and contrasted with inhalation injury not associated with these social factors. Two hundred and fourteen patients were identified with inhalation injury. Ninety-two of these were associated with smoking, alcohol abuse and/or drug abuse. The proportion of IHI cases associated with smoking remained stable but IHI associated with alcohol and drug abuse increased dramatically over the course of the study and if current trends continue will increase further in future years. This study also showed that IHI associated with smoking alcohol and drug abuse were found to be largely caused by housefires and deliberate self-harm, and occurred between 22:00 and 05:59 h. These results were in sharp contrast with IHI not associated with these factors.

Pilot study of the effects of local pressure on microvascular function in the diabetic foot.

AIM: The aim of the study was to determine whether areas of the diabetic foot that experience high pressures during normal activity also demonstrate reductions in cutaneous microvascular flow and/or endothelial function. METHODS: Sixteen patients with diabetes mellitus and eight healthy, age-matched control subjects were recruited. Maps of dynamic pressure on the plantar aspect of both feet were recorded during a normal gait cycle, and the skin microvascular blood flow response to the endothelium-dependent vasodilator acetylcholine was assessed at the sites of highest and lowest plantar pressure over the metatarsal heads. RESULTS: Patients with diabetes had higher plantar pressures than control subjects (P = 0.002), but there were no significant differences in basal skin blood flow or acetylcholine response between the groups. In the patients, baseline flow was increased (P = 0.041) but the acetylcholine response reduced (P = 0.03) at the high-pressure compared with the low-pressure site; this was most apparent in those who were particularly at risk of ulceration due to high plantar pressures. CONCLUSIONS: Chronically raised plantar pressure in the diabetic foot is associated with increased basal skin blood flow, compared with lower pressure areas on the same foot. Further work is required to determine whether, and under what conditions, this additional hyperaemia is protective or maladaptive. In addition, high-pressure areas have a reduced responsiveness to an endothelium-dependent vasodilator, although the clinical significance of these changes is not clear.

Growth factors in the treatment of diabetic foot ulcers.

BACKGROUND: Chronic foot ulceration is a major source of morbidity in diabetic patients. Despite traditional comprehensive wound management, including vascular reconstruction, there remains a cohort of patients with non-responding wounds, often resulting in amputation. These wounds may benefit from molecular manipulation of growth factors to enhance the microcirculation. METHODS: A review of the current literature was performed using Pubmed, with secondary references obtained from key articles. RESULTS AND CONCLUSION: There has been a generally disappointing clinical outcome from growth factor trials, although topical platelet-derived growth factor has shown significant benefit and should be considered in non-healing, well perfused ulcers after failure of conventional wound care. The modulatory role of the extracellular matrix in the cellular response to growth factors and data from regenerative-type fetal wound healing are further areas of interest. The chemical induction of microvessel formation may become a future therapeutic option.

Tongue protrusion strength and fatiguability: relationship to apnoea/hypopnoea index and age.

The sleep apnoea/hypopnoea syndrome (SAHS) is characterized by retroglossal or retropalatal narrowing. The site of obstruction, and the fact that negative pressure in the upper airway increases retroglossal airway size, suggests that tongue muscles may play a role in the maintenance of upper airway patency. We therefore hypothesized that tongue protrusion strength and fatiguability may be predictors of apnoea/hypopnoea index, vary with age and may be different in SAHS patients and normal subjects. Maximal strength (Fmax) and fatiguability (measured as the total time subjects were able to maintain 50% Fmax on three consecutive occasions separated by 30 s) were assessed using a force transducer in 98 consecutive apnoeic/hypopnoeic male patients referred to our laboratory for sleep studies [apnoea/hypopnoea index (AHI) range 3-130/h, age range 30-74 y]. Fmax and fatiguability were also compared in 15 male SAHS patients (mean AHI 20/h) and 15 nonsnoring male subjects matched for age, body mass index and fat free mass. A further 26 SAHS patients had tongue protrusion strength/fatiguability measured before, during and after a night's sleep. Log AHI was only weakly correlated with Fmax (r=- 0.21; P=0.03) and age (r=0.23; P=0.025), but not to fatiguability (P > 0.05). Comparison between SAHS and nonsnoring subjects did not demonstrate significant differences in Fmax (P=0.1) or fatiguability (P=0.1). There was no evidence of a change in muscle strength (P > 0.05) or fatigue (P > 0.05) during the course of a night's sleep. We conclude that tongue protrusion strength and fatiguability are unlikely to be important factors in the pathogenesis of SAHS.

Purification and characterization of multiple forms of the pineapple-stem-derived cysteine proteinases ananain and comosain.

A mixture of ananain (EC 3.4.22.31) and comosain purified from crude pineapple stem extract was found to contain numerous closely related enzyme forms. Chromatographic separation of the major enzyme forms was achieved after treatment of the mixture with thiol-modifying reagents: reversible modification with 2-hydroxyethyl disulphide provided enzyme for kinetic studies, and irreversible alkylation with bromotrifluoroacetone or iodoacetamide gave enzyme for structural analyses by 19F-n.m.r. and electrospray mass spectrometry respectively. Structural and kinetic analyses revealed comosain to be closely related to stem bromelain (EC 3.4.22.32), whereas ananain differed markedly from both comosain and stem bromelain. Nevertheless, differences were seen between comosain and stem bromelain in amino acid composition and kinetic specificity towards the epoxide inhibitor E-64. Differences between five isolatable alternative forms of ananain were characterized by amidolytic activity, thiol stoichiometry and accurate mass determinations. Three of the enzyme forms displayed ananain-like amidolytic activity, whereas the other two forms were inactive. Thiol-stoichiometry determinations revealed that the active enzyme forms contained one free thiol, whereas the inactive forms lacked the reactive thiol required for enzyme activity. M.s. provided direct evidence for oxidation of the active-site thiol to the corresponding sulphinic acid.

Investigation of sequence homology in a group of type-II restriction/modification isoschizomers.

We have dissected the cloned PstI M and R genes to make DNA hybridization probes spanning most of the sequence. These subclones, and also the intact sequence, were used to search for nucleic acid homology by Southern blot in the DNA from twelve organisms which produce PstI isoschizomers. One of these probes, a 206-bp fragment from the N-terminal domain of the endonuclease, showed significant hybridisation in four strains (Escherichia coli strains RFL48, RFL49 and RFL83, and Streptomyces albus P). No significant hybridisation was detected with other parts of the PstI sequences. We have used computer similarity searches to look for homology between the PstI proteins and the known sequences of other type-II systems that recognise different sites. We postulate a possible recognition domain within the M.PstI methyltransferase based on similarity to the M.PaeR7 and M.TaqI methyltransferases.

Heterogeneity of insulin action in muscle: influence of blood flow.

The influence of blood flow (BF) and basal neuromotor tone on in vivo insulin-stimulated glucose uptake (Rg') in muscle was examined using the euglycemic clamp plus deoxyglucose/glucose tracer (insulin action) and labeled microsphere (BF) techniques. Anesthesia was used to produce perturbations in BF and/or activity compared with conscious rats. An index of muscle glycolytic flux (Gf) was estimated from Rg' in excess of glycogen synthesis. Gf and glycogen synthesis were significantly increased in soleus and red gastrocnemius (RG) during insulin infusion (150 mU/l) in conscious rats. Rg' was related to muscle BF in conscious rats (r = 0.92). In anesthetized rats, Rg' and BF were reduced in soleus, RG, red quadriceps, and plantaris (e.g., soleus 69%, P less than 0.001, and 80%, P less than 0.001, respectively). However, it is unlikely that Rg' and BF are causally related because fractional extraction of glucose by muscle was low (approximately 9%); fractional extraction increased during anesthesia (17%, P less than 0.01); BF but not Rg' was reduced by anesthesia in extensor digitorum longus, white gastrocnemius, and white quadriceps; and reduced Rg' during anesthesia in soleus and RG was mainly due to reduced GF. In conclusion, BF is not a major contributor to the heterogeneity in insulin-stimulated glucose uptake among individual muscles under basal conditions. These data suggest that neuromotor tone may indirectly influence the magnitude of muscle glucose uptake during insulin elevation via a substrate switching effect. This may give rise to a significant increase in glycolytic flux of glucose in those muscles that exhibit elevated activity even at rest (e.g., soleus).(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo insulin sensitivity in the rat determined by euglycemic clamp.

Our aim was to develop the glucose clamp (GC) technique in the conscious rat for assessment of in vivo insulin sensitivity. A 2-h euglycemic GC could be performed in chronically cannulated rats using 625 microliter blood. Overnight-fasted rats were infused with porcine insulin (1.67 mU . kg-1 . h-1). Insulin levels of 41 +/- 2 (SE) mU/liter were produced in rats aged 91 +/- 4 days with a 60- to 120-min glucose infusion rate (GIR60-120) of 10.6 +/- 0.6 mg . kg-1 . min-1 (n = 9) during euglycemia. GIR60-120 was significantly (P less than 0.025) reduced in rats aged greater than 130 days (mean, 169 +/- 16 days) to 7.7 +/- 1.2 mg . kg-1 . min-1 (n = 7). Metabolic clearance rate of porcine insulin (46 +/- 3 ml . kg-1 . min-1) and GIR60-120 compared with plateau plasma insulin levels are higher than values reported in humans. The latter may be due to suppression of a higher basal hepatic glucose production or increased potency of porcine compared with native insulin. We conclude that the GC can be accomplished in the rat. When combined with tracer administration and subsequent killing, it should provide a quantitative in vivo measurement of insulin sensitivity in individual tissues.