Association of PS1 1/2, ACE I/D, and LRP C/T polymorphisms with Alzheimer's disease in the Chinese population: a meta-analysis of case-control studies

The objective of this study was to assess the associations of presenilin 1 (PS1) 1/2, angiotensin I-converting enzyme (ACE) insertion/deletion (I/D), and low-density lipoprotein receptor-related protein (LRP) C/T polymorphisms with the risk of Alzheimer's disease (AD) in the Chinese population. PS1 1/2, ACE I/D, and LRP C/T, which are commonly investigated polymorphisms, were evaluated to obtain summary estimates regarding their associations with AD. In total, the data from 24 studies (2611 patients with AD and 2822 control subjects from 23 provinces and special districts in China) that were obtained from the Chinese Biomedicine Database, China National Knowledge Infrastructure, PubMed, and Medline were included. Different models (i.e., dominant, recessive, etc.) of these polymorphisms were analyzed using the Cochrane Review Manager. Statistically significant associations among patients with AD for the 1/1 genotype of the PS1 1/2 polymorphism [odds ratio (OR) = 1.77, 95% confidence interval (CI) = 1.03-3.04; P = 0.04] and the I/I genotype of the ACE I/D polymorphism (OR = 2.44, 95%CI = 1.78-3.35; P < 0.01) were identified. Statistically significant associations were also found for the PS1 1/2 polymorphism in both the dominant and recessive genetic models, whereas no association was found for the LRP C/T polymorphism. All studies exhibited heterogeneity (P < 0.05). This meta-analysis suggests that the 1/1 genotype of the PS1 1/2 polymorphism and the I/I genotype of the ACE I/D polymorphism are significantly associated with an increased risk of AD in the Chinese population.

Sustainable synthesis of hollow Cu-loaded poly(m-phenylenediamine) particles and their application for arsenic removal

A new Cu-catalyzed air oxidation method was successfully developed to prepare Cu-loaded poly(m-phenylenediamine) (PmPD) with monomer conversion rates close to 100%.

Search for a light sterile neutrino at Daya Bay

A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9 GW(th) nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512 m and 561 m) and one far (1579 m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the 10(-3) eV(2)<|Δm(41)(2) |< 0.3 eV(2) range. The relative spectral distortion due to the disappearance of electron antineutrinos was found to be consistent with that of the three-flavor oscillation model. The derived limits on sin(2) 2θ(14) cover the 10(-3) eV(2) ≲ |Δm(41)(2)| ≲ 0.1 eV(2) region, which was largely unexplored.

IL-6 gene promoter polymorphisms and risk of coronary artery disease in a Chinese population

We investigated the relationships between single nucleotide polymorphisms (SNPs) of the interleukin (IL)-6 gene 174 G>C (rs1800795), 572 G>C (rs1800796), and 597 G/A (rs1800797) and coronary artery disease (CAD) risk in a Chinese population. This case-control study recruited 296 CAD patients and 327 controls between January 2009 and May 2012. Genotyping of IL-6 174 G>C (rs1800795), 572 G>C (rs1800796), and 597 G/A (rs1800797) was performed on a 384-well plate format using the Sequenom MassARRAY platform. CAD patients were more likely to be older and male, with a higher body mass index, diabetes, and hypertension, and presented higher triglycerides, and lower total cholesterol, low-density lipoprotein-cholesterol, and high-density lipoprotein-cholesterol. We found that the IL-6 174CC genotype was associated with a significantly increased risk of CAD compared to the wild-type GG genotype in a codominant model [odds ratio (95% confidence interval) = 1.94 (1.13-3.37)], whereas IL-6 174 G>C polymorphisms presented an increased risk of CAD in dominant and recessive models. However, we did not find that the IL-6 572 CC and 597 AA genotypes were correlated with an increased risk of CAD. IL-6 174 G>C rs1800795 was associated with CAD risk in a Chinese population. Further large-scale studies are required to determine whether IL-6 SNPs interact with environmental factors in the development of CAD.

First Report of Aphelenchoides besseyi Causing White Tip Disease of Rice in Jilin Province, China

White tip disease of rice caused by the plant-parasitic nematode Aphelenchoides besseyi is an important domestic quarantine issue causing heavy yield losses of rice. During a survey for rice diseases in 2013, suspect white tip disease of rice was observed in the cities of Changchun and Gongzhuling, Jinlin Province, China. Leaf tips of susceptible rice varieties were white or yellow, becoming brown or black as necrosis set in. Tips of developing leaves were twisted and wrinkled. The flag leaf became twisted above the panicle until development was inhibited. General stunting of the plant accompanied leaf injury. Panicles were severely reduced and produced small deformed kernels while spikelets were reduced in number. Maturity of panicles was delayed, and secondary panicles arising from the lower nodes of the panicle were sterile. Nematodes were isolated from rice grains of diseased panicles. Key morphological features were determined for females and males. Measurements of females (n = 15) were: body length 612.50 to 735.00 μm (mean 673.75 μm), body width 17.37 to 22.21 μm (mean 19.79 μm), esophagus to gland 64.44 to 68.07 μm (mean 66.26 μm), and tail 34.41 to 41.29 μm (mean 37.85 μm). Females had a relatively short ovary with oocytes arranged in several lines; posterior uterine branch two to four times as long as body width; and tail tapering, conoid, with terminus bearing a mucro with four processes arranged in a shape somewhat that of a star. Measurements of males (n = 22) were: body length 483.39 to 580.00 μm (mean 531.70 μm), body width 14.46 to 17.12 μm (mean 15.79 μm), esophagus to gland 63.97 to 66.42 μm (mean 65.20 μm), and tail 30.38 to 36.45 μm (mean 33.41 μm). Males had a curved tail about 180° when relaxed, three pairs of ventrosubmedian papillae with the first one adanal, spicula curved with a slight basal process, and terminus bearing four mucrones arranged variably. Both males and females had lateral field occupying one fourth of the body width, marked by four incisures; delicate cephalic framework; small spear with moderate-size basal knobs; excretory pore was anterior to nerve ring; and intestine joined to esophagus immediately behind median bulb (3). All morphological data and characters were consistent with A. besseyi. Molecular diagnosis as A. besseyi was confirmed after DNA was extracted from nematodes (n = 16) and the templates were used in PCR analysis. The internal transcribed spacer region (ITS) of rDNA was amplified with primers TW81 and AB28 (2). The size of PCR product was 842 bp, and this sequence (KJ009342) was submitted to GenBank and was 98% similar with that of A. besseyi isolates from India (JF826519, JF93390, JF826517, JF826518) and Russia (EU186069). Molecular identification was further confirmed by amplifying part of the ITS region and part of the 5.8 gene of rDNA using the A. besseyi-specific primers BSF and BSR (1). The amplification yielded a 312-bp product specific to A. besseyi. Morphological and molecular data confirmed that the pathogen responsible for white tip disease in Changchun and Gongzhuling was A. besseyi. While this nematode has been reported from many rice-producing areas in China, this is the first detection of A. besseyi in Jilin Province, China. References: (1) R. Q. Cui et al. Plant Quarantine (Chinese) 24:10-12, 2010. (2) S. A. Subbotin et al. Nematology 2:153, 2000. (3) G. Thorne. Principles of Nematology. McGraw-Hill, New York, 1972.

Polymorphism, Expression of Natural Resistance-associated Macrophage Protein 1 Encoding Gene (NRAMP1) and Its Association with Immune Traits in Pigs

Natural resistance-associated macrophage protein 1 encoding gene (NRAMP1) plays an important role in immune response against intracellular pathogens. To evaluate the effects of NRAMP1 gene on immune capacity in pigs, tissue expression of NRAMP1 mRNA was observed by real time quantitative polymerase chain reaction (PCR), and the results revealed NRAMP1 expressed widely in nine tissues. One single nucleotide polymorphism (SNP) (ENSSSCG00000025058: g.130 C>T) in exon1 and one SNP (ENSSSCG00000025058: g.657 A>G) in intron1 region of porcine NRAMP1 gene were demonstrated by DNA sequencing and PCR-RFLP analysis. A further analysis of SNP genotypes associated with immune traits including contain of white blood cell (WBC), granulocyte, lymphocyte, monocyte (MO), rate of cytotoxin in monocyte (MC) and CD4/CD8 T lymphocyte subpopulations in blood was carried out in four pig populations including Large White and three Chinese indigenous breeds (Wannan Black, Huai pig and Wei pig). The results showed that the SNP (ENSSSCG00000025058: g.130 C>T) was significantly associated with level of WBC % (p = 0.031), MO% (p = 0.024), MC% (p = 0.013) and CD4(-)CD8(+) T lymphocyte (p = 0.023). The other SNP (ENSSSCG00000025058: g.657 A>G) was significantly associated with the level of MO% (p = 0.012), MC% (p = 0.019) and CD4(-)CD8(+) T lymphocyte (p = 0.037). These results indicate that the NRAMP1 gene can be regarded as a molecular marker for genetic selection of disease susceptibility in pig breeding.

Spectral measurement of electron antineutrino oscillation amplitude and frequency at Daya Bay

A measurement of the energy dependence of antineutrino disappearance at the Daya Bay reactor neutrino experiment is reported. Electron antineutrinos (ν¯(e)) from six 2.9  GW(th) reactors were detected with six detectors deployed in two near (effective baselines 512 and 561 m) and one far (1579 m) underground experimental halls. Using 217 days of data, 41 589 (203 809 and 92 912) antineutrino candidates were detected in the far hall (near halls). An improved measurement of the oscillation amplitude sin(2)2θ(13)=0.090(-0.009)(+0.008) and the first direct measurement of the ν¯(e) mass-squared difference |Δm(ee)2|=(2.59(-0.20)(+0.19))×10(-3)  eV2 is obtained using the observed ν¯(e) rates and energy spectra in a three-neutrino framework. This value of |Δm(ee)2| is consistent with |Δm(μμ)2| measured by muon neutrino disappearance, supporting the three-flavor oscillation model.

Production and characterization of recombinant glucose oxidase from Aspergillus niger expressed in Pichia pastoris

Recombinant glucose oxidase from Aspergillus niger expressed in Pichia pastoris by fed-batch fermentation was purified and assessed with 1·26 purification fold to homogeneity using Q-Sepharose F.F. chromatography. The enzyme was determined by SDS-PAGE and gradient PAGE, which showed a dimeric form of 150 kDa. The purified rGOD was proved to be a glycoprotein, and the content of which was estimated to be 36·7 and 25·14% by phenol-sulfuric acid and anthrone-sulfuric acid methods. Characteristics demonstrated that the highest activity was in pH 6·0 at 40°C and was stable at a broad pH range from 4·0 to 9·0 at 55°C or below. The optimum substrate for this enzyme was d-glucose, and the Km was 21·06 mmol l(-1) as well as the Vmax was 359 μmol min(-1) mg(-1). rGOD possessed high resistance to various chemicals except for Hg(2+), Fe(2+), Ag(+), Cu(2+), 1,4-dithiothreitol, sodium dodecyl sulfate and ascorbic acid. In addition, the inhibitors also exhibited intensive fluorescence quenching effect on rGOD.

SIGNIFICANCE AND IMPACT OF THE STUDY

Glucose oxidase is a very important enzyme produced by several species. However, large-scale applications have always been postponed by its complexity in fermentation and purification. Our research focused on developing new purification strategy of recombinant GOD from A. niger expressed in P. pastoris. Here, we described this novel one-step purification method and subsequent research in the characteristics of rGOD which showed different results from previous work. These can open new opportunities to increase its application.

Facile and large-scale synthesis of poly(m-phenylenediamine) nanobelts with high surface area and superior dye adsorption ability

PmPD nanobelts with high adsorption performance have been synthesized by using CTAP as oxidants.

Limits on spin-dependent WIMP-nucleon cross sections from 225 live days of XENON100 data

We present new experimental constraints on the elastic, spin-dependent WIMP-nucleon cross section using recent data from the XENON100 experiment, operated in the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 224.6 live days×34 kg of exposure acquired during 2011 and 2012 revealed no excess signal due to axial-vector WIMP interactions with 129Xe and 131Xe nuclei. This leads to the most stringent upper limits on WIMP-neutron cross sections for WIMP masses above 6 GeV/c², with a minimum cross section of 3.5×10(-40) cm² at a WIMP mass of 45 GeV/c², at 90% confidence level.

ER stress-mediated apoptosis induced by celastrol in cancer cells and important role of glycogen synthase kinase-3β in the signal network

HeLa cells treated with celastrol, a natural compound with inhibitive effect on proteasome, exhibited increase in apoptotic rate and characteristics of apoptosis. To clarify the signal network activated by celastrol to induce apoptosis, both the direct target proteins and undirect target proteins of celastrol were searched in the present study. Proteasome catalytic subunit β1 was predicted by computational analysis to be a possible direct target of celastrol and confirmed by checking direct effect of celastrol on the activity of recombinant human proteasome subunit β1 in vitro. Undirect target-related proteins of celastrol were searched using proteomic studies including two-dimensional electrophoresis (2-DE) analysis and iTRAQ-based LC-MS analysis. Possible target-related proteins of celastrol such as endoplasmic reticulum protein 29 (ERP29) and mitochondrial import receptor Tom22 (TOM22) were found by 2-DE analysis of total cellular protein expression profiles. Further study showed that celastrol induced ER stress and ER stress inhibitor could ameliorate cell death induced by celastrol. Celastrol induced translocation of Bax into the mitochondria, which might be related to the upregulation of BH-3-only proteins such as BIM and the increase in the expression level of TOM22. To further search possible target-related proteins of celastrol in ER and ER-related fractions, iTRAQ-based LC-MS method was use to analyze protein expression profiles of ER/microsomal vesicles-riched fraction of cells with or without celastrol treatment. Based on possible target-related proteins found in both 2-DE analysis and iTRAQ-based LC-MS analysis, protein–protein interaction (PPI) network was established using bioinformatic analysis. The important role of glycogen synthase kinase-3β (GSK3β) in the signal cascades of celastrol was suggested. Pretreatment of LiCL, an inhibitor of GSK3β, could significantly ameliorate apoptosis induced by celastrol. On the basis of the results of the present study, possible signal network of celastrol activated by celastrol leading to apoptosis was predicted.

First-order liquid-liquid phase transition in cerium

We report the first experimental observation of a liquid-liquid phase transition in the monatomic liquid metal cerium, by means of in situ high-pressure high-temperature x-ray diffraction experiments. At 13 GPa, upon increasing temperature from 1550 to 1900 K high-density liquid transforms to a low-density liquid, with a density difference of 14%. Theoretic models based on ab initio calculations are built to investigate the observed phase behavior of the liquids at various pressures. The results suggest that the transition primarily originates from the delocalization of f electrons and is deemed to be of the first order that terminates at a critical point.

Dark matter results from 225 live days of XENON100 data

We report on a search for particle dark matter with the XENON100 experiment, operated at the Laboratori Nazionali del Gran Sasso for 13 months during 2011 and 2012. XENON100 features an ultralow electromagnetic background of (5.3 ± 0.6) × 10(-3) events/(keV(ee) × kg × day) in the energy region of interest. A blind analysis of 224.6 live days × 34 kg exposure has yielded no evidence for dark matter interactions. The two candidate events observed in the predefined nuclear recoil energy range of 6.6-30.5 keV(nr) are consistent with the background expectation of (1.0 ± 0.2) events. A profile likelihood analysis using a 6.6-43.3 keV(nr) energy range sets the most stringent limit on the spin-independent elastic weakly interacting massive particle-nucleon scattering cross section for weakly interacting massive particle masses above 8 GeV/c(2), with a minimum of 2 × 10(-45) cm(2) at 55 GeV/c(2) and 90% confidence level.

Systematic review of the efficacy of cilostazol, naftidrofuryl oxalate and pentoxifylline for the treatment of intermittent claudication

BACKGROUND

A systematic review and network meta-analysis was undertaken to consider the evidence for the efficacy and tolerability of placebo, cilostazol, naftidrofuryl oxalate and pentoxifylline in patients with intermittent claudication due to peripheral arterial disease (PAD).

METHODS

MEDLINE, Embase, Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Conference Proceedings, BIOSIS, National Research Register and MetaRegister databases were searched. Eligible studies were randomized controlled trials (RCTs) and published systematic reviews of patients with intermittent claudication due to PAD and whose symptoms persisted despite a period of conservative management. Study selection was conducted by one reviewer with involvement from a clinician. Data were extracted by one reviewer with no blinding to authors or journal, and checked by a second reviewer. Outcome measures were maximum walking distance (MWD) and pain-free walking distance (PFWD).

RESULTS

The review identified 1876 citations; 26 RCTs met the inclusion criteria for the systematic review. Eleven trials provided data relevant for the meta-analysis. Naftidrofuryl oxalate was ranked first for both MWD and PFWD (probability of 0·947 and 0·987, respectively, of being the best treatment) followed by cilostazol and pentoxifylline. For naftidrofuryl oxalate, cilostazol and pentoxifylline, MWD increased by 60 (95 per cent credible interval 20 to 114) per cent, 25 (11 to 40) per cent and 11 (-1 to 24) per cent respectively relative to placebo, and PFWD increased by 49, 13 and 9 per cent.

CONCLUSION

Naftidrofuryl oxalate and cilostazol are both effective treatments for claudication; naftidrofuryl oxalate is likely to be the most effective, with minimal serious adverse events.

Targeted therapy via oral administration of attenuated Salmonella expression plasmid-vectored Stat3-shRNA cures orthotopically transplanted mouse HCC

The development of RNA interference-based cancer gene therapies has been delayed due to the lack of effective tumor-targeting delivery systems. Attenuated Salmonella enterica serovar Typhimurium (S. Typhimurium) has a natural tropism for solid tumors. We report here the use of attenuated S. Typhimurium as a vector to deliver shRNA directly into tumor cells. Constitutively activated signal transducer and activator of transcription 3 (Stat3) is a key transcription factor involved in both hepatocellular carcinoma (HCC) growth and metastasis. In this study, attenuated S. Typhimurium was capable of delivering shRNA-expressing vectors to the targeted cancer cells and inducing RNA interference in vivo. More importantly, a single oral dose of attenuated S. Typhimurium carrying shRNA-expressing vectors targeting Stat3 induced remarkably delayed and reduced HCC (in 70% of mice). Cancer in these cured mice did not recur over 2 years following treatment. These data demonstrated that RNA interference combined with Salmonella as a delivery system may offer a novel clinical approach for cancer gene therapy.

Pressure tunes electrical resistivity by four orders of magnitude in amorphous Ge2Sb2Te5 phase-change memory alloy

Ge-Sb-Te-based phase-change memory is one of the most promising candidates to succeed the current flash memories. The application of phase-change materials for data storage and memory devices takes advantage of the fast phase transition (on the order of nanoseconds) and the large property contrasts (e.g., several orders of magnitude difference in electrical resistivity) between the amorphous and the crystalline states. Despite the importance of Ge-Sb-Te alloys and the intense research they have received, the possible phases in the temperature-pressure diagram, as well as the corresponding structure-property correlations, remain to be systematically explored. In this study, by subjecting the amorphous Ge(2)Sb(2)Te(5) (a-GST) to hydrostatic-like pressure (P), the thermodynamic variable alternative to temperature, we are able to tune its electrical resistivity by several orders of magnitude, similar to the resistivity contrast corresponding to the usually investigated amorphous-to-crystalline (a-GST to rock-salt GST) transition used in current phase-change memories. In particular, the electrical resistivity drops precipitously in the P = 0 to 8 GPa regime. A prominent structural signature representing the underlying evolution in atomic arrangements and bonding in this pressure regime, as revealed by the ab initio molecular dynamics simulations, is the reduction of low-electron-density regions, which contributes to the narrowing of band gap and delocalization of trapped electrons. At P > 8 GPa, we have observed major changes of the average local structures (bond angle and coordination numbers), gradually transforming the a-GST into a high-density, metallic-like state. This high-pressure glass is characterized by local motifs that bear similarities to the body-centered-cubic GST (bcc-GST) it eventually crystallizes into at 28 GPa, and hence represents a bcc-type polyamorph of a-GST.

Observation of electron-antineutrino disappearance at Daya Bay

The Daya Bay Reactor Neutrino Experiment has measured a nonzero value for the neutrino mixing angle θ(13) with a significance of 5.2 standard deviations. Antineutrinos from six 2.9 GWth reactors were detected in six antineutrino detectors deployed in two near (flux-weighted baseline 470 m and 576 m) and one far (1648 m) underground experimental halls. With a 43,000 ton-GWth-day live-time exposure in 55 days, 10,416 (80,376) electron-antineutrino candidates were detected at the far hall (near halls). The ratio of the observed to expected number of antineutrinos at the far hall is R=0.940±0.011(stat.)±0.004(syst.). A rate-only analysis finds sin(2)2θ(13)=0.092±0.016(stat.)±0.005(syst.) in a three-neutrino framework.

A systematic review and economic evaluation of cilostazol, naftidrofuryl oxalate, pentoxifylline and inositol nicotinate for the treatment of intermittent claudication in people with peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) is a condition in which there is blockage or narrowing of the arteries that carry blood to the legs and arms. It is estimated to affect around 4.5% of people aged between 55 and 74 years within the UK. The most common symptom of PAD is intermittent claudication (IC), characterised by pain in the legs on walking that is relieved with rest.

OBJECTIVE

To assess the effectiveness and cost-effectiveness of cilostazol, naftidrofuryl oxalate, pentoxifylline and inositol nicotinate, compared with no vasoactive drugs, for IC due to PAD in adults whose symptoms continue despite a period of conventional management.

DATA SOURCE

Electronic bibliographic databases were searched during April to June 2010 (MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, The Cochrane Library databases, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Conference Proceedings Citation Index, BIOSIS Previews).

REVIEW METHODS

Effectiveness outcomes sought were maximal walking distance (MWD), pain-free walking distance (PFWD), ankle-brachial pressure index, cardiovascular events, mortality, adverse events (AEs) and health-related quality of life (HRQoL). A narrative synthesis was provided for all outcomes and a network meta-analysis was undertaken for the walking distance outcomes. A Markov model was developed to assess the relative cost-effectiveness of the interventions from a NHS perspective over a lifetime. The model has three states: vasoactive drug treatment, no vasoactive drug treatment and death. Each 1-week cycle, patients may continue with the drug, discontinue the drug or die. Regression analysis was undertaken to model the relationship between MWD and utility so that a cost per quality-adjusted life-year (QALY) outcome measure could be presented. Univariate and probabilistic sensitivity analyses were undertaken. All costs and outcomes were discounted at 3.5%.

RESULTS

Twenty-six randomised controlled trials were identified that met the inclusion criteria for the clinical effectiveness review. There was evidence that walking distance outcomes were significantly improved by both cilostazol and naftidrofuryl oxalate; the 95% credible intervals for the difference from placebo in the logarithm mean change MWD from baseline were 0.108 to 0.337 and 0.181 to 0.762, respectively. It was not possible to include inositol nicotinate within the meta-analysis of MWD and PFWD owing to the lack of 24-month data; however, the shorter-term data did not suggest a significant effect. AEs were minor for all drugs and included headaches and gastrointestinal difficulties. The incidence of serious adverse events (SAEs), including cardiovascular events and mortality, was not increased by the vasoactive drugs compared with placebo; however, most studies had a relatively short follow-up time to address this outcome. HRQoL data were limited. Two studies of limited quality were identified within the review of cost-effectiveness. The de novo model developed suggests that naftidrofuryl oxalate dominates cilostazol and pentoxifylline and has a cost per QALY gained of around £6070 compared with no vasoactive drug. This result is reasonably robust to changes within the key model assumptions. Inositol nicotinate was not included within the main analysis owing to lack of data. However, it is unlikely to be considered to be cost-effective due to its high acquisition cost (£900 vs £100-500 per year for the other drugs).

CONCLUSIONS

Naftidrofuryl oxalate and cilostazol both appear to be effective treatments for this patient population, with minimal SAEs. However, naftidrofuryl oxalate is the only treatment that is likely to be considered cost-effective. The long-term effectiveness is uncertain and hence a trial comparing cilostazol, naftidrofuryl oxalate and placebo beyond 24 weeks would be beneficial. Outcomes associated with naftidrofuryl oxalate could also be compared with those associated with supervised exercise programmes and angioplasty.

Positron emission tomography (PET) and magnetic resonance imaging (MRI) for the assessment of axillary lymph node metastases in early breast cancer: systematic review and economic evaluation

BACKGROUND

Breast cancer is the most common type of cancer in women. Evaluation of axillary lymph node metastases is important for breast cancer staging and treatment planning.

OBJECTIVES

To evaluate the diagnostic accuracy, cost-effectiveness and effect on patient outcomes of positron emission tomography (PET), with or without computed tomography (CT), and magnetic resonance imaging (MRI) in the evaluation of axillary lymph node metastases in patients with newly diagnosed early-stage breast cancer.

DATA SOURCES

A systematic review of literature and an economic evaluation were carried out. Key databases (including MEDLINE, EMBASE and nine others) plus research registers and conference proceedings were searched for relevant studies up to April 2009. A decision-analytical model was developed to determine cost-effectiveness in the UK.

REVIEW METHODS

One reviewer assessed titles and abstracts of studies identified by the search strategy, obtained the full text of relevant papers and screened them against inclusion criteria. Data from included studies were extracted by one reviewer using a standardised data extraction form and checked by a second reviewer. Discrepancies were resolved by discussion. Quality of included studies was assessed using the quality assessment of diagnostic accuracy studies (QUADAS) checklist, applied by one reviewer and checked by a second.

RESULTS

Forty-five citations relating to 35 studies were included in the clinical effectiveness review: 26 studies of PET and nine studies of MRI. Two studies were included in the cost-effectiveness review: one of PET and one of MRI. Of the seven studies evaluating PET/CT (n = 862), the mean sensitivity was 56% [95% confidence interval (CI) 44% to 67%] and mean specificity 96% (95% CI 90% to 99%). Of the 19 studies evaluating PET only (n = 1729), the mean sensitivity was 66% (95% CI 50% to 79%) and mean specificity 93% (95% CI 89% to 96%). PET performed less well for small metastases; the mean sensitivity was 11% (95% CI 5% to 22%) for micrometastases (≤ 2 mm; five studies; n = 63), and 57% (95% CI 47% to 66%) for macrometastases (> 2 mm; four studies; n = 111). The smallest metastatic nodes detected by PET measured 3 mm, while PET failed to detect some nodes measuring > 15 mm. Studies in which all patients were clinically node negative showed a trend towards lower sensitivity of PET compared with studies with a mixed population. Across five studies evaluating ultrasmall super-paramagnetic iron oxide (USPIO)-enhanced MRI (n = 93), the mean sensitivity was 98% (95% CI 61% to 100%) and mean specificity 96% (95% CI 72% to 100%). Across three studies of gadolinium-enhanced MRI (n = 187), the mean sensitivity was 88% (95% CI 78% to 94%) and mean specificity 73% (95% CI 63% to 81%). In the single study of in vivo proton magnetic resonance spectroscopy (n = 27), the sensitivity was 65% (95% CI 38% to 86%) and specificity 100% (95% CI 69% to 100%). USPIO-enhanced MRI showed a trend towards higher sensitivity and specificity than gadolinium-enhanced MRI. Results of the decision modelling suggest that the MRI replacement strategy is the most cost-effective strategy and dominates the baseline 4-node sampling (4-NS) and sentinel lymph node biopsy (SLNB) strategies in most sensitivity analyses undertaken. The PET replacement strategy is not as robust as the MRI replacement strategy, as its cost-effectiveness is significantly affected by the utility decrement for lymphoedema and the probability of relapse for false-negative (FN) patients.

LIMITATIONS

No included studies directly compared PET and MRI.

CONCLUSIONS

Studies demonstrated that PET and MRI have lower sensitivity and specificity than SLNB and 4-NS but are associated with fewer adverse events. Included studies indicated a significantly higher mean sensitivity for MRI than for PET, with USPIO-enhanced MRI providing the highest sensitivity. However, sensitivity and specificity of PET and MRI varied widely between studies, and MRI studies were relatively small and varied in their methods; therefore, results should be interpreted with caution. Decision modelling based on these results suggests that the most cost-effective strategy may be MRI rather than SLNB or 4-NS. This strategy reduces costs and increases quality-adjusted life-years (QALYs) because there are fewer adverse events for the majority of patients. However, this strategy leads to more FN cases at higher risk of cancer recurrence and more false- positive (FP) cases who would undergo unnecessary axillary lymph node dissection. Adding MRI prior to SLNB or 4-NS has little effect on QALYs, though this analysis is limited by lack of available data. Future research should include large, well-conducted studies of MRI, particularly using USPIO; data on the long-term impacts of lymphoedema on cost and patient utility; studies of the comparative effectiveness and cost-effectiveness of SLNB and 4-NS; and more robust UK cost data for 4-NS and SLNB as well as the cost of MRI and PET techniques.

FUNDING

This study was funded by the Health Technology Assessment programme of the National Institute of Health Research.

Positron emission tomography (PET) and magnetic resonance imaging (MRI) for the assessment of axillary lymph node metastases in early breast cancer: systematic review and economic evaluation

BACKGROUND

Breast cancer is the most common type of cancer in women. Evaluation of axillary lymph node metastases is important for breast cancer staging and treatment planning.

OBJECTIVES

To evaluate the diagnostic accuracy, cost-effectiveness and effect on patient outcomes of positron emission tomography (PET), with or without computed tomography (CT), and magnetic resonance imaging (MRI) in the evaluation of axillary lymph node metastases in patients with newly diagnosed early-stage breast cancer.

DATA SOURCES

A systematic review of literature and an economic evaluation were carried out. Key databases (including MEDLINE, EMBASE and nine others) plus research registers and conference proceedings were searched for relevant studies up to April 2009. A decision-analytical model was developed to determine cost-effectiveness in the UK.

REVIEW METHODS

One reviewer assessed titles and abstracts of studies identified by the search strategy, obtained the full text of relevant papers and screened them against inclusion criteria. Data from included studies were extracted by one reviewer using a standardised data extraction form and checked by a second reviewer. Discrepancies were resolved by discussion. Quality of included studies was assessed using the quality assessment of diagnostic accuracy studies (QUADAS) checklist, applied by one reviewer and checked by a second.

RESULTS

Forty-five citations relating to 35 studies were included in the clinical effectiveness review: 26 studies of PET and nine studies of MRI. Two studies were included in the cost-effectiveness review: one of PET and one of MRI. Of the seven studies evaluating PET/CT (n = 862), the mean sensitivity was 56% [95% confidence interval (CI) 44% to 67%] and mean specificity 96% (95% CI 90% to 99%). Of the 19 studies evaluating PET only (n = 1729), the mean sensitivity was 66% (95% CI 50% to 79%) and mean specificity 93% (95% CI 89% to 96%). PET performed less well for small metastases; the mean sensitivity was 11% (95% CI 5% to 22%) for micrometastases (≤ 2 mm; five studies; n = 63), and 57% (95% CI 47% to 66%) for macrometastases (> 2 mm; four studies; n = 111). The smallest metastatic nodes detected by PET measured 3 mm, while PET failed to detect some nodes measuring > 15 mm. Studies in which all patients were clinically node negative showed a trend towards lower sensitivity of PET compared with studies with a mixed population. Across five studies evaluating ultrasmall super-paramagnetic iron oxide (USPIO)-enhanced MRI (n = 93), the mean sensitivity was 98% (95% CI 61% to 100%) and mean specificity 96% (95% CI 72% to 100%). Across three studies of gadolinium-enhanced MRI (n = 187), the mean sensitivity was 88% (95% CI 78% to 94%) and mean specificity 73% (95% CI 63% to 81%). In the single study of in vivo proton magnetic resonance spectroscopy (n = 27), the sensitivity was 65% (95% CI 38% to 86%) and specificity 100% (95% CI 69% to 100%). USPIO-enhanced MRI showed a trend towards higher sensitivity and specificity than gadolinium-enhanced MRI. Results of the decision modelling suggest that the MRI replacement strategy is the most cost-effective strategy and dominates the baseline 4-node sampling (4-NS) and sentinel lymph node biopsy (SLNB) strategies in most sensitivity analyses undertaken. The PET replacement strategy is not as robust as the MRI replacement strategy, as its cost-effectiveness is significantly affected by the utility decrement for lymphoedema and the probability of relapse for false-negative (FN) patients.

LIMITATIONS

No included studies directly compared PET and MRI.

CONCLUSIONS

Studies demonstrated that PET and MRI have lower sensitivity and specificity than SLNB and 4-NS but are associated with fewer adverse events. Included studies indicated a significantly higher mean sensitivity for MRI than for PET, with USPIO-enhanced MRI providing the highest sensitivity. However, sensitivity and specificity of PET and MRI varied widely between studies, and MRI studies were relatively small and varied in their methods; therefore, results should be interpreted with caution. Decision modelling based on these results suggests that the most cost-effective strategy may be MRI rather than SLNB or 4-NS. This strategy reduces costs and increases quality-adjusted life-years (QALYs) because there are fewer adverse events for the majority of patients. However, this strategy leads to more FN cases at higher risk of cancer recurrence and more false- positive (FP) cases who would undergo unnecessary axillary lymph node dissection. Adding MRI prior to SLNB or 4-NS has little effect on QALYs, though this analysis is limited by lack of available data. Future research should include large, well-conducted studies of MRI, particularly using USPIO; data on the long-term impacts of lymphoedema on cost and patient utility; studies of the comparative effectiveness and cost-effectiveness of SLNB and 4-NS; and more robust UK cost data for 4-NS and SLNB as well as the cost of MRI and PET techniques.

FUNDING

This study was funded by the Health Technology Assessment programme of the National Institute of Health Research.

Cost-effectiveness of MRI and PET imaging for the evaluation of axillary lymph node metastases in early stage breast cancer

BACKGROUND

UK guidelines for breast cancer recommend axillary nodal assessment via surgical methods such as sentinel lymph node biopsy (SLNB). However, these procedures are associated with adverse effects such as lymphoedema. Magnetic resonance imaging (MRI) and positron emission tomography (PET) are non-invasive imaging techniques. The aim of this study is to evaluate the cost-effectiveness of MRI and PET compared with SLNB for assessment of axillary lymph node metastases in newly-diagnosed early stage breast cancer patients in the UK.

METHODS

An individual patient discrete-event simulation model was developed in SIMUL8(®) to estimate the lifetime costs and benefits of replacing SLNB with MRI or PET, or adding MRI or PET before SLNB. Effectiveness outcomes were derived from a recent systematic review; patient utilities and resource use data were sourced from the literature.

RESULTS

Based on our analysis the baseline SLNB strategy is dominated by the strategies of replacing SLNB with either MRI or PET. The strategy of replacing SLNB with MRI has the highest total quality-adjusted life years (QALYs) and lowest total costs. However, clinical evidence for MRI is based on a limited number of small studies and replacing SLNB with MRI or PET leads to more false-positive and false-negative cases. The strategy of adding MRI before SLNB is cost-effective, but subject to greater uncertainty.

CONCLUSIONS

Based on this analysis the most cost-effective strategy is to replace SLNB with MRI. However, further large studies using up-to-date techniques are required to obtain more accurate data on the sensitivity and specificity of MRI.