Sodium vacancy ordering and the co-existence of localized spins and itinerant charges in NaxCoO2

The sodium cobaltate family (NaxCoO2) is unique among transition metal oxides because the Co sits on a triangular lattice and its valence can be tuned over a wide range by varying the Na concentration x. Up to now detailed modeling of the rich phenomenology (which ranges from unconventional superconductivity to enhanced thermopower) has been hampered by the difficulty of controlling pure phases. We discovered that certain Na concentrations are specially stable and are associated with superlattice ordering of the Na clusters. This leads naturally to a picture of co-existence of localized spins and itinerant charge carriers. For x = 0.84 we found a remarkably small Fermi energy of 87 K. Our picture brings coherence to a variety of measurements ranging from NMR to optical to thermal transport. Our results also allow us to take the first step towards modeling the mysterious ``Curie-Weiss'' metal state at x = 0.71. We suggest the local moments may form a quantum spin liquid state and we propose experimental test of our hypothesis.Comment: 16 pages, 5 figure

Antitumor effects of B3-PE and B3-lysPE40 in a nude mouse model of human breast cancer and the evaluation of B3-PE toxicity in monkeys

B3 is a tumor-reactive monoclonal antibody (mAb) that binds to a limited number of normal tissues.Immunotoxins made with B3 coupled to either Pseudomonas exotoxin (PE) or recombinant forms of PE with a deletion of the cell-binding domain (LysPE40) have been shown to cause complete tumor regression in nude mice bearing a rapidly growing A431 (L. H. Pai et al., Proc. Natl. Acad. Sci. USA, 88: 3358-3362, 1991) human epidermoid carcinoma. In this study we show that an immunotoxin composed of mAb B3 when chemically coupled to LysPE40 (B3-LysPE40) led to complete regression of a slowly growing breast cancer, MCF-7, in nude mice when given i.v. every other day for five doses. mAb B3 coupled to native PE also produced significant regression of the MCF-7 tumor. The reactivity of mAb B3 was evaluated using an immunohistochemical method on the two responsive tumors, MCF-7 and A431, and compared with a typical human colon carcinoma specimen that has B3 antigen on its surface. The results showed that both A431 and MCF-7 xenograft tumors have similar reactivity to B3 when compared with the human colon carcinoma specimen. To evaluate the toxicity of B3-PE in primates, Cynomolgus monkeys received escalating doses of B3-PE i.v. on Days 1, 3, and 5. Based on antibody localization studies using frozen sections of normal human and monkey tissue, gastric, trachea, and bladder mucosal injury could have occurred. However, no clinical signs of injury or histological damage to these organs were seen at the doses administered. Chemical hepatitis due to PE was transient and well tolerated at doses up to 50 μg/kg for three doses. The lethal dose was about 100 μg/kg, and the cause of death was liver necrosis, as shown by necropsy. We conclude that m Ab B3, when coupled to PE40 or PE, can produce strong antitumor activity in vivo. The similar level of reactivity of the B3 antibody in our tumor models with a surgical specimen of a human colon carcinoma and the toxicity study in monkeys indicate that therapeutic doses of B3-PE and B3-LysPE40 can be delivered without causing toxicity to normal organs that express B3 antigen. Although both B3-PE and B3-LysPE40 have antitumor activity in nude mice bearing a human xenograft, B3-LysPE40 is better tolerated and should be further evaluated as a therapeutic agent for cancer patients

Within-Subject Variability of Interferon-g Assay Results for Tuberculosis and Boosting Effect of Tuberculin Skin Testing: A Systematic Review

Background: Variability in interferon-gamma release assays (IGRAs) results for tuberculosis has implications for interpretation of results close to the cut-point, and for defining thresholds for test conversion and reversion. However, little is known about the within-subject variability (reproducibility) of IGRAs. Several national guidelines recommend a twostep testing procedure (tuberculin skin test [TST] followed by IGRA) for the diagnosis of LTBI. However, the effect of a preceding TST on subsequent IGRA results has been reported in studies with apparently conflicting results. Methodology/Findings: We conducted a systematic review to synthesize evidence on within-subject variability of IGRA results and the potential boosting effect of TST. We searched several databases and reviewed citations of previous reviews on IGRAs. We included studies using commercial IGRAs, in addition to non-commercial versions of the ELISPOT assay. Four studies, fulfilling our predefined criteria, examined within-subject variability and 13 studies evaluated TST effects on subsequent IGRA responses. Meta-analysis was not considered appropriate because of heterogeneity in study methods, assays, and populations. Although based on limited data, within-subject variability was present in all studies but the magnitude varied (16-80%) across studies. A TST induced ‘‘boosting’ ’ of IGRA responses was demonstrated in several studies and although more pronounced in IGRA-positive (i.e. sensitized) individuals, also occurred in a smaller but not insignificant proportion of IGRA-negative subjects. The TST appeared to affect IGRA responses only after 3 days and may apparentl

EcoPlex: Empowering compact wireless sensor platforms via roaming and interoperability support

Abstract—EcoPlex is an infrastructure that enables simple wireless platforms to participate seamlessly in a feature-rich, wireless ad hoc network. EcoPlex consists of gateways that are responsible for handoff support for mobility and high data rate without burdening the simple nodes to implement multi-hop protocols. The gateways also create virtual identities for simpler nodes to enable their participation in the feature-rich network without adding complexity to them. We demonstrate the feasibility of this idea with the ultra-compact wireless sensor platform called Eco to participate as virtual nodes in a fully general ZigBee network. Experimental results show EcoPlex to be efficient and scalable. The enhanced mobility and interoperability are added to the Eco platform at the infrastructure level, all with minimal node complexity. I

Uloga testova otpuštanja interferona gama u nadzoru nad tuberkulozom

Tuberculosis is still one of the major global public health threats. Countries with low incidence must focus on exhausting the reservoir of future cases by preventing reactivation. Therefore, it is important to identify and effectively treat those individuals who have latent tuberculosis infection and who may develop active disease. The tuberculin skin test has been the standard for detection of immune response against M. tuberculosis since the beginning of the 20th century. The new millennium has brought advancement in the diagnosis of latent tuberculosis infection. The name of the new blood test is interferon-gamma release assay (IGRA). Croatia is a middle-incidence country with a long decreasing trend and developed tuberculosis control. To reach low incidence and finally eliminate tuberculosis, its tuberculosis programme needs a more aggressive approach that would include intensive contact investigation and treatment of persons with latent tuberculosis infection. This article discusses the current uses of IGRA and its role in tuberculosis control.Tuberkuloza je i danas jedan od vodećih javnozdravstvenih problema. Zemlje s niskom incidencijom fokusiraju se na iscrpljivanje rezervoara budućih slučajeva sprječavanjem reaktivacije bolesti. To se odnosi na traženje i učinkovito liječenje infi ciranih osoba, primarno onih koje su u riziku od obolijevanja nakon infekcije. Tuberkulinski test je od početka 20. stoljeća bio standard u otkrivanju imunosnog odgovora na kontakt s Mycobacterium tuberculosis. Novo tisućljeće donijelo je određeni napredak u obliku novih testova za dijagnozu latentne tuberkulozne infekcije, krvne testove otpuštanja interferona gama. Hrvatska je zemlja srednje incidencije tuberkuloze s dugogodišnjim silaznim trendom i razvijenim protutuberkuloznim aktivnostima. U težnji prema niskoj incidenciji i u konačnici eliminaciji tuberkuloze potrebne su opsežnije aktivnosti unutar državnog programa nadzora nad tuberkulozom, uključujući intenzivnu obradu kontakata i probir na postojanje latentne tuberkulozne infekcije. Ovaj rad razmatra trenutačnu uporabu IGRE (engl. interferon - gamma release assay) i njezinu ulogu u nadzoru nad tuberkulozom

Risk Factors Associated with Positive QuantiFERON-TB Gold In-Tube and Tuberculin Skin Tests Results in Zambia and South Africa

INTRODUCTION: The utility of T-cell based interferon-gamma release assays for the diagnosis of latent tuberculosis infection remains unclear in settings with a high burden of tuberculosis. OBJECTIVES: To determine risk factors associated with positive QuantiFERON-TB Gold In-Tube (QFT-GIT) and tuberculin skin test (TST) results and the level of agreement between the tests; to explore the hypotheses that positivity in QFT-GIT is more related to recent infection and less affected by HIV than the TST. METHODS: Adult household contacts of tuberculosis patients were invited to participate in a cross-sectional study across 24 communities in Zambia and South Africa. HIV, QFT-GIT and TST tests were done. A questionnaire was used to assess risk factors. RESULTS: A total of 2,220 contacts were seen. 1,803 individuals had interpretable results for both tests, 1,147 (63.6%) were QFT-GIT positive while 725 (40.2%) were TST positive. Agreement between the tests was low (kappa = 0.24). QFT-GIT and TST results were associated with increasing age (adjusted OR [aOR] for each 10 year increase for QFT-GIT 1.15; 95% CI: 1.06-1.25, and for TST aOR: 1.10; 95% CI 1.01-1.20). HIV positivity was less common among those with positive results on QFT-GIT (aOR: 0.51; 95% CI: 0.39-0.67) and TST (aOR: 0.61; 95% CI: 0.46-0.82). Smear positivity of the index case was associated with QFT-GIT (aOR: 1.25; 95% CI: 0.90-1.74) and TST (aOR: 1.39; 95% CI: 0.98-1.98) results. We found little evidence in our data to support our hypotheses. CONCLUSION: QFT-GIT may not be more sensitive than the TST to detect risk factors associated with tuberculous infection. We found little evidence to support the hypotheses that positivity in QFT-GIT is more related to recent infection and less affected by HIV than the TST