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A Iacoangeli

Publications and source records attributed to A Iacoangeli.

8 recordsLinked to original sources
PubMed2000

Measurement of a Peak in the Cosmic Microwave Background Power Spectrum from the North American Test Flight of Boomerang.

We describe a measurement of the angular power spectrum of anisotropies in the cosmic microwave background (CMB) at scales of 0&fdg;3 to 5 degrees from the North American test flight of the Boomerang experiment. Boomerang is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a long-duration balloon flight. During a 6 hr test flight of a prototype system in 1997, we mapped more than 200 deg(2) at high Galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26&arcmin; and 16&farcm;5 FWHM, respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of 1 degrees with an amplitude 70 µK(CMB).

Journal Article↗
PubMed2000

A flat Universe from high-resolution maps of the cosmic microwave background radiation

The blackbody radiation left over from the Big Bang has been transformed by the expansion of the Universe into the nearly isotropic 2.73 K cosmic microwave background. Tiny inhomogeneities in the early Universe left their imprint on the microwave background in the form of small anisotropies in its temperature. These anisotropies contain information about basic cosmological parameters, particularly the total energy density and curvature of the Universe. Here we report the first images of resolved structure in the microwave background anisotropies over a significant part of the sky. Maps at four frequencies clearly distinguish the microwave background from foreground emission. We compute the angular power spectrum of the microwave background, and find a peak at Legendre multipole Ipeak = (197 +/- 6), with an amplitude delta T200 = (69 +/- 8) microK. This is consistent with that expected for cold dark matter models in a flat (euclidean) Universe, as favoured by standard inflationary models.

Journal Article↗
PubMed2000

The ionophore monensin inhibits mouse polyomavirus DNA replication and destabilizes viral early mRNAs.

Monensin is a ionophore compound with different biological activities. It raises the intralysosomal pH, it binds the plasma membranes particularly at the level of the cisternal system of the Golgi apparatus. It causes imbalance in the intramembrane ion traffic and inhibits export of secretory proteins at membrane level. Monensin blocks endocytosis and therefore impedes entry of toxic molecules. The drug also inhibits viral proliferation of RNA and DNA viruses such as vesicular stomatitis, influenza and human polyomaviruses. In this report we show that monensin effectively abolishes viral DNA replication of mouse polyomavirus. Results show that the half life of viral early mRNAs is significantly reduced in the presence of the drug. Therefore we suggest that the reduction of viral DNA synthesis is a consequence of the reduced intranuclear pool of viral early antigens.

Animals↗
PubMed1997

Apoptosis dependent decrease of the intramembrane ion traffic in cultured mouse fibroblasts shown by conductivity dispersion.

We have investigated the intramembranal ion traffic in apoptotic 3T6 cells in culture. Apoptosis was induced by various treatments, such as serum deprivation, high density growth and hydrogen peroxide at subnecrotic doses. Cell death was assessed by nucleosomal DNA fragmentation, single cell electrophoresis, immunofluorescence and histological staining. To study the modifications of membrane structure and function, we adopted a well established biophysical strategy based on the measurement of the electrical conductivity of cell suspensions, as a function of the frequency of the electrical field applied to the sample. A comparison between the conductivity of normal and apoptotic cell suspensions shows that programmed cell death causes a decrease of membrane conductivity which indicates a diminished intramembranal ion traffic. Our results strongly suggest that one of the early events in the triggering of apoptosis is represented by an overall reduction of plasma membrane function. Finally, our results are in agreement with the idea that the nucleus is not the sole target of the apoptotic process.

Animals↗
PubMed1996

Electrical conductivity dispersion as a probe of membrane modifications in mouse polyomavirus infected cells in culture.

In this report we investigate the inhibition of membrane conductivity, due to the murine polyomavirus infection in permissive cells in culture. We define experimental conditions to have reproducible results and demonstrate that the intensity of the effects on the cell membrane, depends upon the virus titer used in the infection. Finally, the virus dependent effects disappear if the infection is performed in the presence of a drug that inhibits polymavirus DNA replication.

Animals↗
PubMed1995

Role of mouse polyomavirus late region in the control of viral DNA replication: a review.

The genome of polyomaviruses is divided into two coding regions: the early and the late region. A relatively short regulatory sequence, encompassing the origin of viral DNA replication (ori), separates the two regions encoding the structural genes. In mouse polyomavirus (Py) in particular, the early DNA codes for three antigens: large, middle and small T-antigen (L-T, M-T and S-T, respectively). Large T antigen binds ori and thus regulates both viral DNA transcription and replication. Middle T antigen has been shown to mediate malignant transformation in non-permissive cells in vitro. No defined function has been assigned to the small T antigen although this gene product is thought to act synergistically both with L- and M-T antigens. The viral late region of Py encodes also three different genes whose products form the viral capsid during the productive infection cycle in permissive cells. Py early region was thought to be the only part of the genome necessary to code for proteins of functional and regulatory significance. The viral late region, on the other hand, was for a long time considered a simple reservoir of structural information, since it codes for capsid proteins and was supposedly devoid of functional control properties. This short review is focused on recent works from our and other laboratories, reporting evidence that in Py also the late region has a functional role since late sequences are involved in the control of viral DNA replication and in capsid assembly. Results indicating that this might be true for the cognate simian virus SV40 will be also reviewed.

Animals↗