Maximizing T c by tuning nematicity and magnetism in FeSe1-x S x superconductors.

A fundamental issue concerning iron-based superconductivity is the roles of electronic nematicity and magnetism in realising high transition temperature (T c). To address this issue, FeSe is a key material, as it exhibits a unique pressure phase diagram involving non-magnetic nematic and pressure-induced antiferromagnetic ordered phases. However, as these two phases in FeSe have considerable overlap, how each order affects superconductivity remains perplexing. Here we construct the three-dimensional electronic phase diagram, temperature (T) against pressure (P) and isovalent S-substitution (x), for FeSe1-x S x . By simultaneously tuning chemical and physical pressures, against which the chalcogen height shows a contrasting variation, we achieve a complete separation of nematic and antiferromagnetic phases. In between, an extended non-magnetic tetragonal phase emerges, where T c shows a striking enhancement. The completed phase diagram uncovers that high-T c superconductivity lies near both ends of the dome-shaped antiferromagnetic phase, whereas T c remains low near the nematic critical point.

Ambient pressure structural quantum critical point in the phase diagram of (Ca(x)Sr(1-x))(3)Rh(4)Sn(13).

The quasiskutterudite superconductor Sr_{3}Rh_{4}Sn_{13} features a pronounced anomaly in electrical resistivity at T^{*}∼138 K. We show that the anomaly is caused by a second-order structural transition, which can be tuned to 0 K by applying physical pressure and chemical pressure via the substitution of Ca for Sr. A broad superconducting dome is centered around the structural quantum critical point. Detailed analysis of the tuning parameter dependence of T^{*} as well as insights from lattice dynamics calculations strongly support the existence of a structural quantum critical point at ambient pressure when the fraction of Ca is 0.9 (i.e., x_{c}=0.9). This establishes the (Ca_{x}Sr_{1-x})_{3}Rh_{4}Sn_{13} series as an important system for exploring the physics of structural quantum criticality without the need of applying high pressures.

Controllable Rashba spin-orbit interaction in artificially engineered superlattices involving the heavy-fermion superconductor CeCoIn5.

By using a molecular beam epitaxy technique, we fabricate a new type of superconducting superlattices with controlled atomic layer thicknesses of alternating blocks between the heavy-fermion superconductor CeCoIn5, which exhibits a strong Pauli pair-breaking effect, and nonmagnetic metal YbCoIn5. The introduction of the thickness modulation of YbCoIn5 block layers breaks the inversion symmetry centered at the superconducting block of CeCoIn5. This configuration leads to dramatic changes in the temperature and angular dependence of the upper critical field, which can be understood by considering the effect of the Rashba spin-orbit interaction arising from the inversion symmetry breaking and the associated weakening of the Pauli pair-breaking effect. Since the degree of thickness modulation is a design feature of this type of superlattices, the Rashba interaction and the nature of pair breaking are largely tunable in these modulated superlattices with strong spin-orbit coupling.

Post-operative outcomes of atypical femoral subtrochanteric fracture in patients on bisphosphonate therapy.

Management of bisphosphonate-associated subtrochanteric fractures remains opinion- or consensus-based. There are limited data regarding the outcomes of this fracture. We retrospectively reviewed 33 consecutive female patients with a mean age of 67.5 years (47 to 91) who were treated surgically between May 2004 and October 2009. The mean follow-up was 21.7 months (0 to 53). Medical records and radiographs were reviewed to determine the post-operative ambulatory status, time to clinical and radiological union and post-fixation complications such as implant failure and need for second surgery. The predominant fixation method was with an extramedullary device in 23 patients. 25 (75%) patients were placed on wheelchair mobilisation or no weight-bearing initially. The mean time to full weight-bearing was 7.1 months (2.2 to 29.7). The mean time for fracture site pain to cease was 6.2 months (1.2 to 17.1). The mean time to radiological union was 10.0 months (2.2 to 27.5). Implant failure was seen in seven patients (23%, 95 confidence interval (CI) 11.8 to 40.9). Revision surgery was required in ten patients (33%, 95 CI 19.2 to 51.2). A large proportion of the patients required revision surgery and suffered implant failure. This fracture is associated with slow healing and prolonged post-operative immobility.

Anomalous upper critical field in CeCoIn5/YbCoIn5 superlattices with a Rashba-type heavy Fermion interface.

We report a highly unusual angular variation of the upper critical field (H(c2)) in epitaxial superlattices CeCoIn(5)(n)/YbCoIn(5)(5), formed by alternating layers of n and a 5 unit-cell thick heavy-fermion superconductor CeCoIn(5) with a strong Pauli effect and normal metal YbCoIn(5), respectively. For the n=3 superlattice, H(c2)(θ) changes smoothly as a function of the field angle θ. However, close to the superconducting transition temperature, H(c2)(θ) exhibits a cusp near the parallel field (θ=0°). This cusp behavior disappears for n=4 and 5 superlattices. This sudden disappearance suggests the relative dominance of the orbital depairing effect in the n=3 superlattice, which may be due to the suppression of the Pauli effect in a system with local inversion symmetry breaking. Taking into account the temperature dependence of H(c2)(θ) as well, our results suggest that some exotic superconducting states, including a helical superconducting state, might be realized at high magnetic fields.

Distribution of atypical fractures and cortical stress lesions in the femur: implications on pathophysiology.

INTRODUCTION: Some authors have hypothesised that atypical femur fractures occur due to tensile mechanism of failure. We studied the distribution of such lesions along the femur shaft to determine if they concentrate in regions that are subject to tensile loading. METHODS: From May 2004 to March 2010, radiological reviews of 48 patients aged 69 +/- 10.4 (range 47-92) years with atypical femoral fractures and lesions were performed. The absolute distance of each lesion from the greater trochanter and the ratio of the distance of each lesion from the greater trochanter expressed as a percentage of the entire femur length were measured. RESULTS: All periosteal reactions and cortical stress lesions occurred in the lateral cortex. There were 35 right femoral lesions (28 complete fractures and seven cortical stress reactions), with a median distance of 108.3 +/- 54.0 (range 67.0-270.4) mm from the greater trochanter and a median ratio of 23.9 +/- 11.7 (range 15.7-58.6) percent of the entire femoral length. There were 38 left femoral lesions (27 complete fractures and 11 cortical stress reactions), with a median distance of 109.9 +/- 43.1 (range 73.6-246.2) mm from the greater trochanter and a median ratio of 24.4 +/- 9.1(range 16.3-51.1) percent of the entire femoral length. CONCLUSION: Based on previously established femoral shaft loading characteristics, atypical lesions were clustered at the region of maximal tensile loading. No lesion occurred in regions that were subject to compressive loading. This unique distribution supports a tensile mechanism of failure in such lesions.

Quantum oscillations in the anomalous phase in Sr3Ru2O7.

We report measurements of quantum oscillations detected in the putative nematic phase of Sr3Ru2O7. Improvements in sample purity enabled the resolution of small amplitude de Haas-van Alphen (dHvA) oscillations between two first order metamagnetic transitions delimiting the phase. Two distinct frequencies were observed, whose amplitudes follow the normal Lifshitz-Kosevich profile. Variations of the dHvA frequencies are explained in terms of a chemical potential shift produced by reaching a peak in the density of states, and an anomalous field dependence of the oscillatory amplitude provides information on domains.

Exclusion of acute pulmonary embolism: computed tomography pulmonary angiogram or D-dimer?

INTRODUCTION: The aim of our study was to determine the accuracy of the D-dimer test in the exclusion of pulmonary embolism. METHODS: In 2006, 446 patients at our hospital underwent computed tomography pulmonary angiogram (CTPA) for the exclusion of pulmonary embolism. We selected patients with a clinical suspicion of pulmonary embolism, and who underwent both a CTPA examination and a D-dimer test performed within a period of five days. Pregnant women, patients with an allergy to intravenous contrast and those who were on anticoagulant therapy were excluded. Based on our criteria, 219 cases were selected. D-dimer test was performed using an immunoturbidimetric assay. A cut-off value of 500 ng/ml was selected as the upper limit to exclude thrombosis. RESULTS: There were 42 patients positive for pulmonary embolism on CTPA and all had elevated D-dimer values. There were 177 patients negative for pulmonary embolism on CTPA and 49 of them had normal D-dimer values. The sensitivity and specificity of the D-dimer test was 100.0 percent (95 percent confidence interval [CI] 91.6-100.0) and 27.7 percent (95 percent CI 21.2-34.9), respectively. The likelihood ratio for a positive test and negative test was 1.38 and 0, respectively. CONCLUSION: The D-dimer test is suitable for screening patients with a clinical suspicion of pulmonary embolism. The indiscriminate use of CTPA results in unnecessary testing and elevates healthcare costs. Clinicians are urged to give due consideration to a D-dimer test result prior to requesting a CTPA examination.

Microarray analysis of multiple candidate genes and associated plasma proteins for nephropathy secondary to type 2 diabetes among Chinese individuals.

AIMS/HYPOTHESIS: Evolving research suggests that common and rare alleles jointly constitute the genetic landscape of complex disease. We studied the association between 43 pathway-related candidate genes with 'intermediate phenotype' (i.e. corresponding plasma protein) and diabetic nephropathy in a customised microarray of 1,536 SNPs. METHODS: In this case-control study of type 2 diabetic Chinese individuals with and without diabetic nephropathy, cases (n = 545) were defined on the basis of a spot urinary albumin/creatinine ratio (ACR) > 113 mg/mmol; the value for controls (n = 503) was ACR < 3.3 mg/mmol. Genotyping was performed using Illumina GoldenGate assay. RESULTS: No single nucleotide polymorphism (SNP) remained significant in single locus analysis after correction for multiple testing. Therefore, we explored the best approximately 1% SNPs. Of these 13 SNPs, four clustered to a 5' end NADPH oxidase homologue 4 (NOX4) haplotype (GGCC frequency = 0.776) with estimated OR for diabetic nephropathy of 2.05 (95% CI 1.04-4.06) (heterozygous) and 2.48 (1.27-4.83) (homozygous) (p = 0.0055). The haplotype was correlated with plasma Cu/Zn superoxide dismutase (SOD) concentration, suggesting increased oxidative burden. Endothelin-1 SNP (rs1476046G>A, frequency = 0.252) was correlated with plasma C-terminal pro-endothelin-1 concentrations with an estimated OR for diabetic nephropathy of (heterozygous) 1.26 (0.96-1.66) and (homozygous) 1.87 (1.13-3.12) (p = 0.0072). Nitric oxide synthase 1 (NOS1) 5' haplotype (TGTC frequency = 0.38) also revealed a suggestive association with diabetic nephropathy: heterozygous 1.26 (0.95-1.67), homozygous 1.57 (1.04-2.35) (p = 0.0073). A rare NADPH oxidase homologue 1 (NOX1)-coding non-synonymous SNP (Arg315His, frequency = 0.006) was found exclusively among cases. CONCLUSIONS/INTERPRETATION: Our preliminary observations suggest that common haplotypes from NOX4 and endothelin-1 SNP correlated with plasma Cu/Zn SOD and C-terminal pro-endothelin-1 concentrations, respectively, and might have conferred diabetic nephropathy susceptibility. Common NOS1 and rare NOX1 variants also revealed a suggestive association with diabetic nephropathy. Future studies to validate our observation are needed.

Knee locking secondary to osteochondral fracture of the patella: an unusual presentation.

Acute locking is a sign of internal derangement of the knee and is an orthopaedic surgical emergency. Differential diagnoses of this condition are torn meniscus, intra-articular loose bodies and torn anterior cruciate ligament. We present a 15-year-old schoolboy who developed acute locking of the knee during dancing. Arthroscopy revealed that he had sustained an osteochondral fracture of the patella and the loose fragment from it caused locking of the knee. That this was not pseudo-locking was confirmed by examination of the knee under anaesthesia. Locking of the knee by a loose osteochondral fragment following acute dislocation of the patella, though rare, should be considered as a possible cause of true locking.

Angiotensin receptor antagonist vs. angiotensin-converting enzyme inhibitor in Asian subjects with type 2 diabetes and albuminuria - a randomized crossover study.

BACKGROUND: Subjects with type 2 diabetes mellitus (T2DM) and albuminuria are at risk for progressive diabetic nephropathy. The relative blood pressure lowering and antialbuminuric efficacy of angiotensin receptor antagonist (ARB) vs. angiotensin-converting enzyme (ACE) inhibitor has not been well studied. METHODS: Forty-one ARB- and ACE inhibitor-naive T2DM subjects with albuminuria (>30 mg/g creatinine) were given either 50 mg of losartan (ARB) or 20 mg of quinapril (ACE inhibitor) (50% maximum dose) for 4 weeks, with a 4-week wash-out period in-between interventions in a crossover fashion. The order of intervention was randomized. The primary endpoint was the reduction of blood pressure and albuminuria. Secondary endpoint was changes in plasma transforming growth factor beta (TGF-beta). RESULTS: Among the 41 subjects, 66% were male. The mean age (s.d.) was 52 (10) years, and duration of diabetes was 8 (14) years. Blood pressure reduction (though not statistically significant) was similar on both interventions [systolic: losartan 3 (15) vs. quinapril 2 (13) mmHg, p = 0.52; diastolic: losartan 1 (9) vs. quinapril 2 (8) mmHg, p = 0.55]. However, amelioration of albuminuria [mean (s.e.)] was significantly greater with losartan [losartan vs. quinapril: -93 (82) vs. -49 (65) mg/g, p = 0.02]. There was no change in plasma TGF-beta levels [mean (s.d.)] on either treatment, losartan [before 12.1 (8.9) vs. after 11.9 (9.6) ng/ml, p = 0.68] and quinapril [11.1 (7.9) vs. 11.1 (7.8) ng/ml, p = 0.87). CONCLUSION: In Asian subjects with T2DM and albuminuria, 4 weeks of losartan therapy at 50 mg daily appeared to have greater antialbuminuric effect than 20 mg of quinapril.

Subtrochanteric insufficiency fractures in patients on alendronate therapy: a caution.

We carried out a retrospective review over ten months of patients who had presented with a low-energy subtrochanteric fracture. We identified 13 women of whom nine were on long-term alendronate therapy and four were not. The patients treated with alendronate were younger, with a mean age of 66.9 years (55 to 82) vs 80.3 years (64 to 92) and were more socially active. The fractures sustained by the patients in the alendronate group were mainly at the femoral metaphyseal-diaphyseal junction and many had occurred after minimal trauma. Five of these patients had prodromal pain in the affected hip in the months preceding the fall, and three demonstrated a stress reaction in the cortex in the contralateral femur. Our study suggests that prolonged suppression of bone remodelling with alendronate may be associated with a new form of insufficiency fracture of the femur. We believe that this finding is important and indicates the need for caution in the long-term use of alendronate in the treatment of osteoporosis.

Oxidative burden in prediabetic and diabetic individuals: evidence from plasma coenzyme Q(10).

AIM: Individuals with diabetes and prediabetes are at risk of vascular injury. However, the exact mechanisms are unclear. The mitochondria mobile electron carrier coenzyme Q(10) (CoQ(10)) is a potent lipophilic antioxidant. We hypothesize that oxidative stress, detectable as changes in plasma CoQ(10) concentrations and composition, plays an important role in vascular disease in diabetes. METHODS: We measured plasma CoQ(10) concentrations (including reduced ubiquinol and oxidized ubiquinone subfractions) in 60 subjects with normal glucose tolerance [NGT; fasting plasma glucose (FPG) < 5.5 mmol/l], 63 with impaired fasting glucose (IFG; FPG 5.6-6.9 mmol/l) and 69 with Type 2 diabetes (DM; FPG > 6.9 mmol/l). RESULTS: In men and women, the total CoQ(10)/total cholesterol ratio was reduced in DM (mean +/-sd) [male (M) 0.09 +/- 0.04; female (F) 0.07 +/- 0.04] compared with NGT (0.29 +/- 0.08; 0.21 +/- 0.07) and IFG (0.27 +/- 0.07; 0.23 +/- 0.07) (DM vs. NGT and IFG P = 0.001). A stepwise reduction in the plasma ubiquinol fraction (ubiquinol/total CoQ10) was observed from NGT (M 0.93 +/- 0.06; F 0.95 +/- 0.06) compared with IFG (0.43 +/- 0.25; 0.41 +/- 0.15) and DM (0.24 +/- 0.11; F 0.29 +/- 0.16) (DM vs. IFG vs. NGT P = 0.001). In contrast, the plasma ubiquinone/ubiquinol ratio increased from NGT (M 0.08 +/- 0.07, F 0.06 +/- 0.08) to IFG (2.14 +/- 1.84, 1.75 +/- 1.04) to DM (4.77 +/- 4.88, 3.81 +/- 3.71) (DM vs. IFG vs. NGT P = 0.001). These differences remained after adjusting for age, body mass index and FPG. CONCLUSIONS: The change in CoQ(10) with increasing FPG concentration suggests an increase in oxidative burden, already evident in the prediabetic IFG individuals. This increase in oxidative stress might contribute to the increased risk of vascular disease.

Relationship between common functional polymorphisms of the p22phox gene (-930A > G and +242C > T) and nephropathy as a result of Type 2 diabetes in a Chinese population.

OBJECTIVE: Genetic determinants are important in diabetic nephropathy (DN). Oxidative stress has also emerged as an important pathogenic factor in DN and vascular NADH oxidase is a major source of reactive oxygen species (ROS). Previous small studies reported a strong but contradictory association between functional genetic variation of p22(phox), an important subcomponent of NADH oxidase, and DN. We investigated the association between two common functional single nucleotide polymorphisms (SNPs) (-930 A > G and +242 C > T) and DN in a much larger group of Chinese patients with Type 2 diabetes mellitus (T2DM). RESEARCH DESIGN AND METHODS: Case-control study of Chinese subjects with long-standing T2DM (> 10 years). Cases (n = 306) were subjects with a spot urinary albumin : creatinine ratio (ACR) of > 113 mg/mmol or elevated serum creatinine. Control subjects (n = 306) had ACR < 3.3 mg/mmol and normal serum creatinine. Genotyping was carried out by standard PCR and restriction fragment length polymorphism analysis. RESULTS: Gender distribution, age, duration of diabetes and HbA(1c) were similar in cases and control subjects. Distribution of genotypes in the control subjects for both SNPs was consistent with the Hardy-Weinberg equilibrium. Distribution of genotypes did not differ significantly between cases and control subjects for both polymorphisms-+2424C > T: cases CC 84.6%, CT 15.0%, TT 0.4% and control subjects CC 87.6%, CT 11.8%, TT 0.6% (P = 0.45); -930 A > G: cases AA 40.5%, AG 41.8%, GG 17.7% and control subjects AA 38.2%, AG 49.0%, GG 12.8% (P = 0.12). Distribution of alleles was also similar-+2424 C > T: cases C 92.2%, T 7.8% and control subjects C 93.5%, T 6.5% (P = 0.66); -930 A > G cases A 61.4%, G 38.6% and control subjects A 62.7%, G 37.3% (P = 0.38). We estimated that our study has approximately 80% power to detect a relative risk of 1.65 (for +242 C > T) and 1.35 (for -930 A > G) conferred by the minor allele, respectively. CONCLUSIONS: In contrast with previous small studies, our data suggest that these SNPs do not confer significantly increased susceptibility to DN secondary to T2DM in Chinese subjects.

Childhood acute pancreatitis in a children's hospital.

OBJECTIVE: To analyse the cases of acute pancreatitis presented to a children's hospital in Singapore. METHODS: Clinical charts of all children, aged under 18 years, who presented to our hospital for the first time with pancreatitis (ICD search criteria = 577.x) between the period of 1998 and mid-2002 were reviewed. Parameters analysed included presenting features, aetiology of the acute pancreatitis, length of hospital stay, complications, treatment and outcome. RESULTS: There were 12 cases in the review period, and the attributable causes in these cases were, in descending order, trauma, drug-induced, anatomical anomalies, poisoning and idiopathic. Of interest were two patients whose pancreatitis were results of child abuse. The most common symptoms were abdominal pain (n=11) and vomiting (n=7), though only five patients localised the pain to the epigastrium. Abdominal tenderness could be elicited in all the patients. Eleven had evidence of acute pancreatitis from computerised tomography (CT) whilst the twelfth was diagnosed with ultrasonography. The peak amylase levels amongst these patients were not high, with a median of 512.5 U/L. In the acute stage, only one patient required operative intervention whilst the remainder were managed conservatively. The mean length of hospital stay was 12.41 +/- 4.54 days. The complications encountered included pseudocyst formation, ascites, hypocalcaemia, pleural effusion and coagulopathy. CONCLUSIONS: The diagnosis of acute pancreatitis in children can be difficult. This is often due to ambiguous symptoms, signs and laboratory results. CT and ultrasound are essential investigations in the diagnosis and subsequent follow-up.

Impact of an asthma carepath on the management of acute asthma exacerbations.

INTRODUCTION: Clinical pathways are being developed to standardise the management of acute asthma with the aim of improving asthma care. We evaluated the impact of an asthma carepath (CP), developed and instituted at a large community-based teaching hospital. MATERIALS AND METHODS: Case records of consecutive asthma cases were reviewed after the implementation of a new asthma CP (November 1999 to March 2000). Data from July to October 1998 were used as historical control data [pre-carepath (pre-CP)]. Data collected included patient demographics, investigations performed, treatment prescribed, use of peak expiratory flow rate (PEFR) monitoring, length of stay (LOS) and asthma relapse rates. RESULTS: One hundred and eighteen consecutive cases treated according to CP were compared with 67 pre-CP controls. There was no significant difference between the two groups with regard to LOS, use of PEFR monitoring, use of systemic steroids in hospital or asthma relapse after discharge (P > 0.05). A significant decrease in sputum tests (34.3% pre-CP versus 18.6% CP, P = 0.017) and use of antibiotics (62.7% pre-CP versus 30.4% CP, P < 0.001) was observed for patients on CP. The proportion of patients who had their salbutamol reviewed (49.3% pre-CP versus 73.7% CP, P = 0.001) and oxygen reviewed (25.8% pre-CP versus 73.8% CP, P = 0.004) was also significantly higher for cases on CP. CONCLUSION: Although the asthma CP did not significantly reduce LOS or early relapse, it was associated with a significant reduction of the use of sputum tests and antibiotics. Review of salbutamol and oxygen as treatment was also more likely.

An audit of patients with rheumatic disease requiring medical intensive care.

INTRODUCTION: Medical intensive care for patients with rheumatic disease is usually complicated by significant morbidity and mortality. The aims of this study were to examine the reasons for admission, the outcomes of these patients and the possible prognostic factors in an Asian cohort. MATERIALS AND METHODS: This was a retrospective study of the case records of 29 admissions to the medical intensive care unit (MICU) of Tan Tock Seng Hospital (TTSH) from August 1999 to August 2000. RESULTS: There were 28 patients admitted, of whom 1 had a repeat admission. The majority of these patients were young (mean age 38.9 +/- 16.3 years) and 71.4% were females. Twenty patients (71.4%) had systemic lupus erythematosus (SLE). The main reasons for admission were infection/sepsis syndrome (n = 18), hypotension (n = 16) and acute respiratory failure (n = 14). The observed in-hospital mortality was 64.3%, which was higher than the predicted risk of hospital death of 47.3%. Infection contributed to 55.6% of deaths. The patients who died had a longer mean duration of the rheumatic disease, higher APACHE II scores, higher rates of hypertension and hyperlipidaemia, higher doses of steroid and immunosuppressive therapy and more organ failures. Renal failure and acute respiratory distress syndrome were the two most common organ failures in patients who died. CONCLUSION: Many of our critically-ill patients with rheumatic disease were young females with good functional status. Despite the high mortality, they should be aggressively treated because infection and acute respiratory failure are potentially reversible.

A case report of Aspergillus hypersensitivity syndrome with obstructing bronchial aspergillosis.

INTRODUCTION: A 62-year-old Indian male with diabetes mellitus presented with atypical, overlap features of Aspergillus hypersensitivity syndrome and obstructing bronchial aspergillosis. CLINICAL PICTURE: He was febrile and tachypnoeic with diffuse crepitations and wheezing. Chest X-ray was normal but eosinophil count was 2900/mm3 and Ig E > 10,000 IU/ml. TREATMENT AND OUTCOME: He responded initially to high dose steroid therapy but deteriorated subsequently from extensive mucus plugging of the bronchial tree which resulted in respiratory failure and death. He was HIV-negative. CONCLUSION: Culture and histologic examination of bronchoscopically identified tracheobronchial mucus plugs should be performed as early treatment may be life-saving.