Molecular characterization of Mycobacterium bovis strains isolated from cattle and humans by spoligotyping and 24-locus MIRU-VNTR, and prevalence of positive IGRA in slaughterhouse workers in Southern Turkey.

Background: Mycobacterium bovis is a zoonotic member of the Mycobacterium tuberculosis complex with a wide range of hosts, mainly cattle. Molecular epidemiological studies should be conducted to determine the transmission route, zoonotic risk factors, and phylogenetic relationships of M. bovis strains. Aims: This study aimed to characterize bovine and human M. bovis isolates by molecular methods. Methods: Molecular characterization and clonal relationship of strains isolated from tissue and organ samples of 76 cattle with positive tuberculin tests were collected from a slaughterhouse, and four M. bovis strains isolated from clinical materials of patients with suspected pulmonary TB isolates were analyzed using 24-locus MIRU-VNTR and spoligotyping methods. QuantiFERON-TB Gold Plus (QFT-Plus; Qiagen) was used to determine the prevalence of latent TB infection among 21 slaughterhouse personnel including 7 veterinarians, 12 butchers, 1 caretaker, and 1 veterinary technician. Results: SB0288/SIT685 type was detected in both cattle and humans by the spoligotyping method. When evaluating MIRU-VNTR, the presence of a 100% compatible pattern between human and bovine isolates was not detected, but some human samples were found to be 91.6% similar to a bovine sample. In addition, 21 slaughterhouse workers were screened with the interferon gamma-released assay (IGRA) and a 23.8% positivity was detected. Conclusion: Clonal similarity was determined between the bovine and human isolates using the MIRU-VNTR and spoligotyping methods and IGRA positivity in the occupational group suggested that M. bovis might be associated with pulmonary tuberculosis in humans.

Comparison of convensional and molecular methods used to determine Leishmania species.

Leishmaniasis is a multisystem disease, and have a broad spectrum ranging from skin lesions to systemic disease. Therefore diagnosis must be supported with laboratory results. We analyzed 153 smears, aspiration, blood and bone narrow samples collected from patients suspected with cutaneous and visceral leishmaniasis. The specificity and sensitivity of the four methods (culture, smear, miniexon-PCR-RFLP and ITS1-PCR-RFLP) were detected and Leishmania species were determined. The ITS1-PCR-RFLP method was found that the highest sensitivity and specifity. L. infantum and L. tropica were identified by molecular methods from samples. As a result, ITS-1-PCR has a high sensitivity and specificity and easily applicable method. However, it requires the miniexon-PCR or ITS1 sequencing the discrimination of the L. donovani complex. L. infantum is a agent both visceral and cutaneous leishmaniasis in our region.

A controlled trial of erythromycin and UDCA in premature infants during parenteral nutrition in minimizing feeding intolerance and liver function abnormalities.

OBJECTIVE: To compare the effectiveness of oral erythromycin versus ursodeoxycholic acid (UDCA) treatment in preventing feeding intolerance and liver function abnormalities. STUDY DESIGN: A prospective, double blind, randomized, controlled trial in which three groups of preterm infants (birth weight <1500 g) were randomized to erythromycin (12.5 mg kg(-1) per day), UDCA (5 mg kg(-1) every 6 h) or placebo treatment. During the period 352 infants were admitted to our unit of which 75 infants whose parents accepted participation were enrolled in the study. Full enteral feeding or intestinal failure-associated liver disease was considered as the primary outcome measures. RESULTS: Time to achieve full feeding after beginning the treatment was significantly shorter in the erythromycin group (P=0.014). γ-Glutamyl transpeptidase levels in the placebo group were significantly higher than in the intervention groups (P=0.001). GTT level was slightly lower in UDCA groups than erythromycin. CONCLUSION: Oral erythromycin was most effective in facilitating enteral feeding and UDCA was most effective in preventing cholestasis in very low birth weight infants. Prophylactic usage of UDCA could be considered in infants with prolonged parenteral nutrition.

Ferromagnetic fractional quantum Hall states in a valley-degenerate two-dimensional electron system.

We study a two-dimensional electron system where the electrons occupy two conduction band valleys with anisotropic Fermi contours and strain-tunable occupation. We observe persistent quantum Hall states at filling factors nu=1/3 and 5/3 even at zero strain when the two valleys are degenerate. This is reminiscent of the quantum Hall ferromagnet formed at nu=1 in the same system at zero strain. In the absence of a theory for a system with anisotropic valleys, we compare the energy gaps measured at nu=1/3 and 5/3 to the available theory developed for single-valley, two-spin systems, and find that the gaps and their rates of rise with strain are much smaller than predicted.

Correlated states of electrons in wide quantum wells at low fillings: the role of charge distribution symmetry.

Magnetotransport measurements on electrons confined to a 57-nm-wide, GaAs quantum well reveal that the correlated electron states at low Landau level fillings (nu) display a remarkable dependence on the symmetry of the electron charge distribution. At a density of 1.93 x 10;{11} cm;{-2}, a developing fractional quantum Hall state is observed at the even-denominator filling nu = 1/4 when the distribution is symmetric, but it quickly vanishes when the distribution is made asymmetric. At lower densities, as we make the charge distribution asymmetric, we observe a rapid strengthening of the insulating phases that surround the nu = 1/5 fractional quantum Hall state.

Evidence for developing fractional quantum Hall states at even denominator 1/2 and 1/4 fillings in asymmetric wide quantum wells.

We report the observation of developing fractional quantum Hall states at Landau level filling factors nu = 1/2 and 1/4 in electron systems confined to wide GaAs quantum wells with significantly asymmetric charge distributions. The very large electric subband separation and the highly asymmetric charge distribution at which we observe these quantum Hall states, together with the fact that they disappear when the charge distribution is made symmetric, suggest that these are one-component states, possibly described by the Moore-Read Pfaffian wave function.

Dependence of effective mass on spin and valley degrees of freedom.

We measure the effective mass (m) of interacting two-dimensional electrons confined to an AlAs quantum well while we change the conduction-band valley occupation and the spin polarization via the application of strain and magnetic field, respectively. Compared to its band value, m is enhanced unless the electrons are fully valley- and spin-polarized. Incidentally, in the fully spin- and valley-polarized regime, the electron system exhibits an insulating behavior.

Effective mass suppression in dilute, spin-polarized two-dimensional electron systems.

We report effective mass (m*) measurements, via analyzing the temperature dependence of the Shubnikov-de Haas oscillations, for dilute, interacting, two-dimensional electron systems (2DESs) occupying a single conduction-band valley in AlAs quantum wells. When the 2DES is partially spin-polarized, m* is larger than its band value, consistent with previous results on various 2DESs. However, as we fully spin-polarize the 2DES by subjecting it to strong parallel magnetic fields, m* is unexpectedly suppressed and falls even below the band mass.

Anomalous giant piezoresistance in AlAs 2D electron systems with antidot lattices.

An AlAs two-dimensional electron system patterned with an antidot lattice exhibits a giant piezoresistance effect at low temperatures, with a sign opposite to the piezoresistance observed in the unpatterned region. We suggest that the origin of this anomalous giant piezoresistance is the nonuniform strain in the antidot lattice and the exclusion of electrons occupying the two conduction-band valleys from different regions of the sample. This is analogous to the well-known giant magnetoresistance effect, with valley playing the role of spin and strain the role of magnetic field.

Valley susceptibility of an interacting two-dimensional electron system.

We report direct measurements of the valley susceptibility, the change of valley population in response to an applied symmetry-breaking strain, in an AlAs two-dimensional electron system. As the two-dimensional density is reduced, the valley susceptibility dramatically increases relative to its band value, reflecting the system's strong electron-electron interaction. The increase has a remarkable resemblance to the enhancement of the spin susceptibility and establishes the analogy between the spin and valley degrees of freedom.

Dependence of persistent gaps at landau level crossings on relative spin.

We report measurements of the quantum Hall state energy gap at avoided crossings between Landau levels originating from different conduction band valleys in AlAs quantum wells. These gaps exhibit an approximately linear dependence on the magnetic field over a wide range of fields and filling factors. More remarkably, we observe an unexpected dependence of the gap size on the relative spin orientation of the crossing levels, with parallel-spin crossings exhibiting larger gaps than antiparallel-spin crossings.