Vortex dynamics and frequency splitting in vertically coupled nanomagnets

We explored the dynamic response of a vortex core in a circular nanomagnet by manipulating its dipole-dipole interaction with another vortex core confined locally on top of the nanomagnet. A clear frequency splitting is observed corresponding to the gyrofrequencies of the two vortex cores. The peak positions of the two resonance frequencies can be engineered by controlling the magnitude and direction of the external magnetic field. Both experimental and micromagnetic simulations show that the frequency spectra for the combined system is significantly dependent on the chirality of the circular nanomagnet and is asymmetric with respect to the external bias field. We attribute this result to the strong dynamic dipole-dipole interaction between the two vortex cores, which varies with the distance between them. The possibility of having multiple states in a single nanomagnet with vertical coupling could be of interest for magnetoresistive memories.

Nontuberculous mycobacteria in gastrostomy fed patients with cystic fibrosis

Multi-drug resistant Mycobacterium abscessus complex (MABSC) is a form of Nontuberculous mycobacteria (NTM) of special, international concern in Cystic Fibrosis (CF). We hypothesised that gastric juice and percutaneous endoscopic gastrostomy (PEG) feeding devices might yield MABSC isolates. Gastric juice and sputa from sixteen adult PEG fed CF patients and five replaced PEG tubes were studied. Bacterial and fungal isolates were cultured. Mycobacterium were identified by rpoB, sodA and hsp65 gene sequencing and strain typed using variable number tandem repeat. Bacteria and/or fungi grew from all gastric juice, sputa and PEG samples. MABSC were detected in 7 patients. Five had MABSC in their sputum. Two had an identical MABSC strain in their sputum and gastric juice and one had the same strain isolated from their PEG tube and sputum. Two patients who were sputum sample negative had MABSC isolated in their gastric juice or PEG tube. MABSC were therefore identified for the first time from a gastric sample in a minority of patients. We conclude that gastric juice and PEG-tubes may be a potential source of MABSC isolates in CF patients, and these findings warrant further study.

Population-based study demonstrating an increase in colorectal cancer in young patients

BACKGROUND

New Zealand has among the highest rates of colorectal cancer in the world and is an unscreened population. The aim of this study was to determine the trends in incidence and tumour location in the New Zealand population before the introduction of national colorectal cancer screening.

METHODS

Data were obtained from the national cancer registry and linked to population data from 1995 to 2012. Incidence rates for colorectal cancer by sex, age (less than 50 years, 50-79 years, 80 years or more) and location (proximal colon, distal colon and rectum) were assessed by linear regression.

RESULTS

Among patients aged under 50 years, the incidence of distal colonic cancer in men increased by 14 per cent per decade (incidence rate ratio (IRR 1·14), 95 per cent c.i. 1·00 to 1·30; P = 0·042); the incidence of rectal cancer in men increased by 18 per cent (IRR 1·18, 1·06 to 1·32; P = 0·002) and that in women by 13 per cent (IRR 1·13, 1·02 to 1·26; P = 0·023). In those aged 50-79 years, there was a reduction in incidence per decade of proximal, distal and rectal cancers in both sexes. In the group aged 80 years and over, proximal cancer incidence per decade increased by 19 per cent in women (IRR 1·19, 1·13 to 1·26; P < 0·001) and by 25 per cent in men (IRR 1·25, 1·18 to 1·32; P < 0·001); among women, the incidence of distal colonic cancer decreased by 8 per cent (IRR 0·92, 0·86 to 0·98); P = 0·012), as did that of rectal cancer (IRR 0·92, 0·86 to 0·97; P = 0·005).

CONCLUSION

The increasing incidence of rectal cancer among younger patients needs to be considered when implementing screening strategies.

Translating colorectal cancer genetics into clinically useful biomarkers

Colorectal cancer (CRC) is a major health problem worldwide accounting for over a million deaths annually. While many patients with Stage II and III CRC can be cured with combinations of surgery, radiotherapy and chemotherapy, this is morbid costly treatment and a significant proportion will suffer recurrence and eventually die of CRC. Increased understanding of the molecular pathogenesis of CRC has the potential to identify high risk patients and target therapy more appropriately. Despite increased understanding of the molecular events underlying CRC development, established molecular techniques have only produced a limited number of biomarkers suitable for use in routine clinical practice to predict risk, prognosis and response to treatment. Recent rapid technological developments, however, have made genomic sequencing of CRC more economical and efficient, creating potential for the discovery of genetic biomarkers that have greater diagnostic, prognostic and therapeutic capabilities for the management of CRC. This paper reviews the current understanding of the molecular pathogenesis of CRC, and summarizes molecular biomarkers that surgeons will encounter in current clinical use as well as those under development in clinical and preclinical trials. New molecular technologies are reviewed together with their potential impact on the understanding of the molecular pathogenesis of CRC and their potential clinical utility in classification, diagnosis, prognosis and targeting of therapy.

Microbiological profiles of sputum and gastric juice aspirates in Cystic Fibrosis patients

Gastro-Oesophageal Reflux (GOR) is a key problem in Cystic Fibrosis (CF), but the relationship between lung and gastric microbiomes is not well understood. We hypothesised that CF gastric and lung microbiomes are related. Gastric and sputum cultures were obtained from fifteen CF patients receiving percutaneous endoscopic gastrostomy feeding. Non-CF gastric juice data was obtained through endoscopy from 14 patients without lung disease. Bacterial and fungal isolates were identified by culture. Molecular bacterial profiling used next generation sequencing (NGS) of the 16S rRNA gene. Cultures grew bacteria and/or fungi in all CF gastric juice and sputa and in 9/14 non-CF gastric juices. Pseudomonas aeruginosa(Pa) was present in CF sputum in 11 patients, 4 had identical Pa strains in the stomach. NGS data from non-CF gastric juice samples were significantly more diverse compared to CF samples. NGS showed CF gastric juice had markedly lower abundance of normal gut bacteria; Bacteroides and Faecalibacterium, but increased Pseudomonas compared with non-CF. Multivariate partial least squares discriminant analysis demonstrated similar bacterial profiles of CF sputum and gastric juice samples, which were distinct from non-CF gastric juice. We provide novel evidence suggesting the existence of an aerodigestive microbiome in CF, which may have clinical relevance.

The effect of intrauterine infusion of dextrose on clinical endometritis cure rate and reproductive performance of dairy cows

The main objective of this study was to evaluate the intrauterine administration use of 200 mL of 50% dextrose solution as a treatment against clinical endometritis (CE); CE cure rate and reproductive performance were evaluated. Additionally, the association of several relevant risk factors, such as retained placenta (RP), metritis, CE, anovulation, hyperketonemia, and body condition score with reproductive performance, early embryonic mortality, and CE were evaluated. A total of 1,313 Holstein cows housed on 4 commercial dairy farms were enrolled in the study. At 7±3 DIM cows were examined for metritis and had blood collected to determine serum β-hydroxybutyrate concentration. To determine if cows had ovulated at least once before 44±3 DIM, the presence of a corpus luteum was evaluated by ovarian ultrasonography at 30±3 DIM and at 44±3 DIM. At 30±3 DIM, CE was diagnosed using the Metricheck device (SimcroTech, Hamilton, New Zealand); cows with purulent or mucopurulent vaginal discharge were diagnosed as having CE. Cows diagnosed with CE (n=175) were randomly allocated into 2 treatment groups: treatment (intrauterine infusion of 200 mL of 50% dextrose) or control (no infusion). Clinical endometritis cows were re-evaluated as described above at 44±3 DIM, and cows that were free of purulent or mucopurulent vaginal discharge were considered cured. Intrauterine infusion of dextrose tended to have a detrimental effect on CE cure rate, and treatment did not have an effect on first-service conception rate and early embryonic mortality. A multivariable Cox's proportional hazard model was performed to evaluate the effect of several variables on reproductive performance; the variables RP, CE, parity, anovulation, and the interaction term between parity and anovulation were associated with hazard of pregnancy. Cows that did not have RP or CE were more likely to conceive than cows that were diagnosed with RP or CE. Cows that had RP were at 3.36 times higher odds of losing their pregnancy than cows that did not have RP. In addition, cows diagnosed with CE were at 2.16 higher odds of losing their pregnancy than cows without CE. In conclusion, intrauterine infusion of 200 mL of 50% dextrose solution as a treatment for CE had a strong statistical tendency to decrease CE cure rate, did not improve first-service conception rate and early embryonic mortality, and did not decrease calving-to-conception interval.

The effect of nanoparticle permeation on the bulk rheological properties of mucus from the small intestine

The effectiveness of delivering oral therapeutic peptides, proteins and nucleotides is often hindered by the protective mucus barrier that covers mucosal surfaces of the gastrointestinal (GI) tract. Encapsulation of active pharmaceutical ingredients (API) in nanocarriers is a potential strategy to protect the cargo but they still have to pass the mucus barrier. Decorating nanoparticles with proteolytic enzymes has been shown to increase the permeation through mucus. Here we investigate the effect of poly(acrylic acid) (PAA) nanoparticles decorated with bromelain (BRO), a proteolytic enzyme from pineapple stem, on the bulk rheology of mucus as well as non-decorated poly(lactic-co-glycolic acid) (PLGA) nanoparticles. Porcine intestinal mucus from the small intestine was incubated for 30min in the presence of PLGA nanoparticles or polyacrylic nanoparticles decorated with bromelain (PAA-BRO). The effect of nanoparticles on the rheological properties, weight of gel, released glycoprotein content from mucus as well as the viscosity of liquid removed was assessed. Treatment with nanoparticles decreased mucus gel strength with PAA-BRO reducing it the most. PAA-BRO nanoparticles resulted in the release of increased glycoprotein from the gel network whereas mucus remained a gel and exhibited a similar breakdown stress to control mucus. Therefore it would be possible to use bromelain to increase the permeability of nanoparticles through mucus without destroying the gel and leaving the underlying mucosa unprotected.

Discovery of Time Variation of the Intensity of Molecular Lines in IRC+10216 in The Submillimeter and Far Infrared Domains

We report on the discovery of strong intensity variations in the high rotational lines of abundant molecular species towards the archetypical circumstellar envelope of IRC+10216. The observations have been carried out with the HIFI instrument on board Herschel and with the IRAM 30-m telescope. They cover several observing periods spreading over 3 years. The line intensity variations for molecules produced in the external layers of the envelope most probably result from time variations in the infrared pumping rates. We analyze the main implications this discovery has on the interpretation of molecular line emission in the envelopes of Mira-type stars. Radiative transfer calculations have to take into account both the time variability of infrared pumping and the possible variation of the dust and gas temperatures with stellar phase in order to reproduce the observation of molecular lines at different epochs. The effect of gas temperature variations with stellar phase could be particularly important for lines produced in the innermost regions of the envelope. Each layer of the circumstellar envelope sees the stellar light radiation with a different lag time (phase). Our results show that this effect must be included in the models. The sub-mm and FIR lines of AGB stars cannot anymore be considered as safe intensity calibrators.

Active and passive heat stress similarly compromise tolerance to a simulated hemorrhagic challenge

Passive heat stress increases core and skin temperatures and reduces tolerance to simulated hemorrhage (lower body negative pressure; LBNP). We tested whether exercise-induced heat stress reduces LBNP tolerance to a greater extent relative to passive heat stress, when skin and core temperatures are similar. Eight participants (6 males, 32 ± 7 yr, 176 ± 8 cm, 77.0 ± 9.8 kg) underwent LBNP to presyncope on three separate and randomized occasions: 1) passive heat stress, 2) exercise in a hot environment (40°C) where skin temperature was moderate (36°C, active 36), and 3) exercise in a hot environment (40°C) where skin temperature was matched relative to that achieved during passive heat stress (∼38°C, active 38). LBNP tolerance was quantified using the cumulative stress index (CSI). Before LBNP, increases in core temperature from baseline were not different between trials (1.18 ± 0.20°C; P > 0.05). Also before LBNP, mean skin temperature was similar between passive heat stress (38.2 ± 0.5°C) and active 38 (38.2 ± 0.8°C; P = 0.90) trials, whereas it was reduced in the active 36 trial (36.6 ± 0.5°C; P ≤ 0.05 compared with passive heat stress and active 38). LBNP tolerance was not different between passive heat stress and active 38 trials (383 ± 223 and 322 ± 178 CSI, respectively; P = 0.12), but both were similarly reduced relative to active 36 (516 ± 147 CSI, both P ≤ 0.05). LBNP tolerance is not different between heat stresses induced either passively or by exercise in a hot environment when skin temperatures are similarly elevated. However, LBNP tolerance is influenced by the magnitude of the elevation in skin temperature following exercise induced heat stress.

Visualizing domain wall and reverse domain superconductivity

In magnetically coupled, planar ferromagnet-superconductor (F/S) hybrid structures, magnetic domain walls can be used to spatially confine the superconductivity. In contrast to a superconductor in a uniform applied magnetic field, the nucleation of the superconducting order parameter in F/S structures is governed by the inhomogeneous magnetic field distribution. The interplay between the superconductivity localized at the domain walls and far from the walls leads to effects such as re-entrant superconductivity and reverse domain superconductivity with the critical temperature depending upon the location. Here we use scanning tunnelling spectroscopy to directly image the nucleation of superconductivity at the domain wall in F/S structures realized with Co-Pd multilayers and Pb thin films. Our results demonstrate that such F/S structures are attractive model systems that offer the possibility to control the strength and the location of the superconducting nucleus by applying an external magnetic field, potentially useful to guide vortices for computing application.

When superconductivity emerges in a thin superconductor grown on a ferromagnet, it does so in an array of interacting superconducting and normally conducting channels. Maria Iavarone and colleagues use scanning tunnelling microscopy to image how these channels form and interact.

Survival of myeloma patients following the introduction of thalidomide as a second-line therapy: a retrospective study at a single New Zealand centre

AIM

This retrospective study compares the overall survival (OS) of multiple myeloma (MM) patients following treatment at a New Zealand hospital over a period in which novel therapies were available but restricted, almost exclusively, to thalidomide as a second-line therapy.

METHODS

Clinical, laboratory and OS data were collected on 361 MM patients who were treated at Christchurch Hospital during 2000-2010. Patients were subdivided according to the clinical criteria used to determine front-line treatment decisions. Older patients (age ≥66, n = 180) generally received standard-dose chemotherapy without autologous stem cell transplant (SCT) and formed one group. Younger patients were further subdivided according to whether they received autologous SCT (n = 89), allogeneic SCT (n = 24) or no SCT (n = 68).

RESULTS

Older patients had a significantly shorter OS (P < 0.0001) than younger patients (median OS = 25 vs 78 months) however treated. Analysis of relative survival demonstrated that the increased mortality of older patients was greater than that attributable to normal ageing. Younger patients who received no transplant had a significantly shorter OS (P < 0.0001) than those who received autologous SCT or allogeneic SCT with 5-year survivals of 38%, 70% and 72% respectively. Use of novel therapies was significantly higher in younger than older patients (60% vs 47%, P = 0.011).

CONCLUSIONS

The front-line treatment groupings of hospital MM patients had significantly different survivals. The OS of SCT ineligible patients remains poor despite the introduction of thalidomide.