Synthesis of heptanuclear Ni4Dy3 coordination aggregate using tridentate ligand: X-ray structure, magnetism and theoretical studies

The Schiff base ligand, 2-(((2-hydroxybenzyl)imino)methyl)phenol (H2L) having ONO donor centres are utilized to synthesize {Ni4Dy3} coordination aggregate following the support of six benzoate bridging groups. Sequential addition of Dy(NO3)3·6H2O and NiCl2·6H2O to H2L followed by PhCO2Na completes the coordination driven aggregation of heptanuclear Na[Ni4Dy3(L)4(μ3-OH)4(μ1,1,3,3-PhCO2)2(μ1,3-PhCO2)4(CH3OH)4]∙CH2Cl2·9H2O (1) having 2,3,6M7 − 1 topology. Two adjacent perpendicular inverse Ni2Dy2 partial di-cubane units sharing a common vertex through the central DyIII ion resulted a new structural arrangement within the Ni − Dy family of coordination aggregates. The complex shows no slow magnetic relaxation under zero applied fields and only shows a very weak field dependent magnetization. The DFT calculations revealed weak ferromagnetic exchange between benzoato-bridged NiII ions, whereas the CASSCF calculations were used to identify magnetic anisotropy in NiII and DyIII ions resulting in low-lying excited states of DyIII ions with significant probability for the quantum tunneling of the magnetization, which rationalize the observed fast dynamics in the magnetic properties

A quantitative PCR (TaqMan) assay for pathogenic Leptospira spp

Background: Leptospirosis is an emerging infectious disease. The differential diagnosis of leptospirosis is difficult due to the varied and often "flu like" symptoms which may result in a missed or delayed diagnosis. There are over 230 known serovars in the genus Leptospira. Confirmatory serological diagnosis of leptospirosis is usually made using the microscopic agglutination test (MAT) which relies on the use of live cultures as the source of antigen, often performed using a panel of antigens representative of local serovars. Other techniques, such as the enzyme linked immunosorbent assay (ELISA) and slide agglutination test (SAT), can detect different classes of antibody but may be subject to false positive reactions and require confirmation of these results by the MAT. Methods: The polymerase chain reaction (PCR) has been used to detect a large number of microorganisms, including those of clinical significance. The sensitivity of PCR often precludes the need for isolation and culture, thus making it ideal for the rapid detection of organisms involved in acute infections. We employed real-time (quantitative) PCR using TaqMan chemistry to detect leptospires in clinical and environmental samples. Results and Conclusions: The PCR assay can be applied to either blood or urine samples and does not rely on the isolation and culture of the organism. Capability exists for automation and high throughput testing in a clinical laboratory. It is specific for Leptospira and may discriminate pathogenic and non-pathogenic species. The limit of detection is as low as two cells

Leptospirosis serology in the Common Brushtail Possum (Trichosurus vulpecula) from urban Sydney, Australia

The common brushtail possum (Trichosurus vulpecula) is indeed a common marsupial in major cities of Australia. This species is known to be susceptible to leptospirosis and often lives in close contact with humans, raising concerns about the potential for transmission of this disease in urban areas. A total of 192 brushtail possum blood samples were collected from 136 individuals in suburban areas of metropolitan Sydney from November 2002 to November 2004. Sera were screened against a reference panel of 21 Leptospira spp. using the microscopic agglutination test. Leptospiral antibodies were detected in 9.6% (13/136) of tested brushtail possums and represented two serovars; antibodies to Leptospira interrogans serovar Hardjo were most frequently identified (11/136). A representative of the exotic serogroup Ballum, most likely serovar Arborea, was found in two of 136 brushtail possums. Exposure to leptospirosis seemed to be associated with age, as older animals had a higher incidence, but there was no distinction in relation to gender. Antibody prevalence varied between the different sampling sites and seropositive animals were clustered and restricted to a few sites. These data support the possible role of brushtail possums as a maintenance host for Leptospira spp. in urban environments and also identified them as a previously unknown and potential source of serovar Arborea

An outbreak of leptospirosis in North Queensland, Australia January to May, 1999

The World Health Organization/Food and Agriculture Organization Collaborating Center for Reference and Research on Leptospirosis, Western Pacific Region, is part of Queensland Health Scientific Services, Queensland Health. In 1999 there was a marked increase in human leptospirosis notifications in North Queensland. Australia, over the period of January to May. There were 216 notifications for the state of Queensland in 1999, compared with 108 in 1998 and 64 in 1997. By April 1999, the Reference Laboratory and Queensland Health's Tropical Public Health Unit (TPHU), Cairns, had reported an outbreak of leptospirosis in North Queensland. Notifications reported for the North Queensland Health districts of Cairns, Tablelands and Innisfail were the highest, with the majority involving workers in the banana industry. The outbreak resulted from infections with a number of serovars, mostly attributed to serovars Australis and Zanoni. Sixty leptospiral isolates were obtained from human cases in North Queensland during the outbreak. The hospitalization rate was in excess of 50%. The Queensland Health's TPHU has implemented a program to educate target industries and the community on the risks and prevention strategies associated with leptospirosis

Leptospiral antibodies in flying foxes in Australia

The sera of 271 pteropid bats (or flying foxes) collected from Queensland, New South Wales, Western Australia, and the Northern Territory were screened against a reference panel of 21 Leptospira spp. using the microscopic agglutination test (MAT). Sera were collected from December 1997 through August 1999. The MAT panel represented those serovars previously isolated in Australia, as well as exotic serovars found in neighboring countries. Leptospiral antibodies were detected in 75 (28%) of the sera and represented seven serovars, one of which, L. interrogans serovar cynopteri has been regarded as exotic to Australia. Sixty sera were reactive to one serovar, 12 sera were reactive to two serovars, and three sera were reactive to three serovars. The L. kirschneri serovar australis was most frequently identified (60.2%). The findings suggest a previously unrecognized role of pteropid bats in the natural history of leptospirosis. The potential exists for establishment of infection in new host species, the transmission of new serovars to known host species, and for changes in virulence of leptospires as a result of passage through these species

Synthesis and characterization of two self-assembled [Cu6Gd3] and [Cu5Dy2] complexes exhibiting the magnetocaloric effect, slow relaxation of magnetization, and anticancer activity

Two new paths for coordination driven self-assembly reactions under the binding support of 2-((1-hydroxy-2-methylpropan-2-ylimino)methyl)-6-methoxyphenol (H2L) have been discovered from the reactions of Cu(ClO4)2·6H2O, NEt3 and GdCl3/DyCl3·6H2O in MeOH/CHCl3 (2 : 1) medium. A similar synthetic protocol is useful to provide two different types of self-aggregated molecular clusters [Cu6Gd3(L)3(HL)3(μ3-Cl)3(μ3-OH)6(OH)2]ClO4·4H2O (1) and [Cu5Dy2(L)2(HL)2(μ-Cl)2(μ3-OH)4(ClO4)2(H2O)6](ClO4)2·2NHEt3Cl·21H2O (2). The adopted reaction procedure established the importance of the HO− and Cl− ions in the mineral-like growth of the complexes, derived from solvents and metal ion salts. In the case of complex 1, one GdIII center has been trapped at the central position of the core upheld by six μ3-OH and three μ3-Cl groups, whereas for complex 2 one CuII center was trapped using four μ3-hydroxo and two μ-chlorido groups. The magnetothermal behavior of 1 has been examined for a magnetocaloric effect of −ΔSm = 11.3 J kg−1 K−1 at 2 K for ΔH = 7 T, whereas the magnetic susceptibility measurements of 2 showed slow magnetic relaxation with Ueff = 15.8 K and τ0 = 9.8 × 10−7 s in zero external dc field. Cancer cell growth inhibition studies proved the potential of both the complexes with interestingly high activity for the Cu6Gd3 complex against human lung cancer cells. Both complexes 1 and 2 also exhibited DNA and human serum albumin (HSA) binding abilities in relation to the involved binding sites and thermodynamics.</p