Lentiviral manipulation of gene expression in human adult and embryonic stem cells

Human stem cells could revolutionize the field of medicine by providing a diverse range of cell types for tissue replacement therapies and drug discovery. To achieve this goal, genetic tools need to be optimized and developed for controlling and manipulating stem cells ex vivo. Here we describe a lentiviral delivery system capable of high infection rates in human mesenchymal and embryonic stem cells. The lentiviral backbone was modified to express mono- and bi-cistronic transgenes and was also used to deliver short hairpin ribonucleic acid for specific silencing of gene expression in human stem cells. We show that lentiviral transduction can be used to alter gene expression without altering the genes' ability to differentiate in vitro. These vectors will enable rapid analysis of gene function in stem cells and permit the generation of knock-in / knock-out models of human disease in the rapidly developing field of gene therapy

Adjustable mount for electro-optic transducers in an evacuated cryogenic system

The invention is an adjustable mount for positioning an electro-optic transducer in an evacuated cryogenic environment. Electro-optic transducers are used in this manner as high sensitivity detectors of gas emission lines of spectroscopic analysis. The mount is made up of an adjusting mechanism and a transducer mount. The adjusting mechanism provided five degrees of freedom, linear adjustments and angular adjustments. The mount allows the use of an internal lens to focus energy on the transducer element thereby improving the efficiency of the detection device. Further, the transducer mount, although attached to the adjusting mechanism, is isolated thermally such that a cryogenic environment can be maintained at the transducer while the adjusting mechanism remains at room temperature. Radiation shields also are incorporated to further reduce heat flow to the transducer location

Determination of C-reactive protein in female dogs with benign and malignant mammary tumors

Indexación: ScieloSUMMARY The aim of this study was to determine C-reactive protein levels in dogs with benign and malignant mammary tumors. Thirty female dogs, with ages ranging between 6 and 15 years and with no distinction of breed were used for this purpose. The animals were divided into 3 different groups of 10 dogs each: Group 1 (control), Group 2 (benign mammary tumor) and Group 3 (malignant mammary tumor). The neoplasias were classified histologically and C-reactive protein (CRP) levels were analyzed using a human turbidimetric immunoassay validated for dogs. Group 3 had the highest values (mean: 8.2 mg/L; median: 7.1 mg/L) of C-reactive protein compared with the other groups (P < 0.05). According to a discriminant analysis, a female dog with a mammary tumor and CRP values ≥ 8 mg/L has a 61% or greater probability of this tumor being malignant. Key words: C-reactive protein, mammary tumors, malignant. RESUMEN El objetivo de este estudio fue determinar los niveles séricos de proteína C-reactiva en caninos con neoplasias mamarias benignas y malignas. Se determinaron concentraciones séricas de proteína C-reactiva en 30 hembras caninas con edades entre 6 y 15 años, sin discriminación de raza y no esterilizadas. Los animales fueron divididos en tres grupos de 10 individuos cada uno: grupo 1 (control), grupo 2 (neoplasia mamaria benigna) y grupo 3 (neoplasia mamaria maligna). Las neoplasias mamarias fueron clasificadas mediante estudio histopatológico en benignas o malignas. Los niveles séricos de proteína C-reactiva se determinaron a partir de un ensayo inmunoturbidimétrico de uso humano validado en caninos. El grupo 3 fue el que presentó los valores más altos (media 8,2 mg/L, mediana 7,1 mg/L) de proteína C-reactiva con respecto a los otros dos grupos (P < 0,05). De acuerdo con un análisis discriminante, una perra con neoplasia mamaria y valores de CRP ≥ 8 mg/L tiene una probabilidad de un 61% o más de que ésta sea maligna. Palabras clave: proteína C-reactiva, neoplasia mamaria, maligna

Progress in thin film GaAs solar cells

Solar cells using polycrystalline films of gallium arsenid

Contact-induced apical asymmetry drives the thigmotropic responses of Candida albicans hyphae

Acknowledgements We thank Marco Thiel for assistance with data interpretation, Peter Sudbery for the provision of strains and Jeremy Craven for useful discussions. This work was supported by a BBSRC-DTG to D. D. T., NIH award DK083592 to F. J. B. and P. A. J., and a Royal Society URF UF080611 and MRC NIRG 90671 to A. C. B.Non peer reviewedPublisher PD

The 1997 event in the Crab pulsar revisited

A complex event observed in the radio pulses from the Crab pulsar in 1997 included echoes, a dispersive delay, and large changes in intensity. It is shown that these phenomena were due to refraction at the edge of a plasma cloud in the outer region of the Crab Nebula. Several similar events have been observed, although in less detail. It is suggested that the plasma cloud is in the form of filaments with diameter around 3 x 10^11m and electron density of order 10^4 cm-3Comment: 5 pages 4 figs Accepted by MNRA

Vitamin D toxicity of dietary origin in cats fed a natural complementary kitten food

Case series summary This case series describes two young sibling cats and an additional unrelated cat, from two separate households, that developed hypercalcaemia associated with hypervitaminosis D. Excessive vitamin D concentrations were identified in a natural complementary tinned kitten food that was fed to all three cats as part of their diet. In one of the cases, there was clinical evidence of soft tissue mineralisation. The hypercalcaemia and soft tissue mineralisation resolved following withdrawal of the affected food and medical management of the hypercalcaemia. Relevance and novel information This case series demonstrates the importance of obtaining a thorough dietary history in patients presenting with hypercalcaemia and the measurement of vitamin D metabolites when investigating such cases. Complementary foods may have the potential to induce nutritional toxicity even when fed with complete, nutritionally balanced diets

The Effect of Crystallization on the Pulsations of White Dwarf Stars

We consider the pulsational properties of white dwarf star models with temperatures appropriate for the ZZ Ceti instability strip and with masses large enough that they should be substantially crystallized. Our work is motivated by the existence of a potentially crystallized DAV, BPM 37093, and the expectation that digital surveys in progress will yield many more such massive pulsators. A crystallized core makes possible a new class of oscillations, the torsional modes, although we expect these modes to couple at most weakly to any motions in the fluid and therefore to remain unobservable. The p-modes should be affected at the level of a few percent in period, but are unlikely to be present with observable amplitudes in crystallizing white dwarfs any more than they are in the other ZZ Ceti's. Most relevant to the observed light variations in white dwarfs are the g-modes. We find that the kinetic energy of these modes is effectively excluded from the crystallized cores of our models. As increasing crystallization pushes these modes farther out from the center, the mean period spacing between radial overtones increases substantially with the crystallized mass fraction. In addition, the degree and structure of mode trapping is affected. The fact that some periods are strongly affected by changes in the crystallized mass fraction while others are not suggests that we may be able to disentangle the effects of crystallization from those due to different surface layer masses.Comment: 18 pages, 5 figures, accepted on 1999 July 2 for publication in the Astrophysical Journa