Interaction of Epstein-Barr viral (EBV) origin of replication (oriP) with EBNA-1 and cellular anti-EBNA-1 proteins

We have previously shown that 12-O-tetradecanoylphorbol-13-acetate (TPA) which activates expression of the latent genome of the Epstein-Barr virus (EBV) in Burkitt lymphoma cells induces the synthesis of two cellular anti-EBNA-1 competitor proteins, anti-EBNA-1.1 and anti-EBNA-1.2. Both anti-EBNA-1 proteins can uncouple the specific binding of the EBNA-1 to the region required for EBV plasmid maintenance (oriP). Here, we show by DNase I footprinting that the binding sites on oriP for the EBNA-1 and the anti-EBNA-1 proteins were indistinguishable. The proteins bound to the 30-bp tandem repeats of the oriP. Glycerol-gradient centrifugation and gel retardation assay revealed that a 60-kDa protein formed the anti-EBNA-1.1-DNA complex and a 40-kDa protein formed the anti-EBNA-1.2-DNA complex.     

Biomedical applications of tunable diode laser spectrometry: Correlation between breath carbon monoxide and low level blood carboxyhemoglobin saturation

Tunable diode laser spectrometry was used to measure breath carbon monoxide (CO) concentrations in nonsmoking subjects. Corresponding blood carboxyhemoglobin (COHb) saturations between physiological levels and levels after 1 and 8 hours exposure to 9 ppm CO, the maximum permissible concentration in the air under federal regulations, were also determined. A good linear correlation between breath CO and blood COHb saturation for low levels representing ambient conditions was established, with a correlation coefficient better than 0.999 for the means and 0.945 for the individual data points. Similar studies on the other compounds of concern are also possible using tunable diode laser spectrometry, requiring only a breath sample and with no sample preparation. This technique will facilitate fast, noninvasive environmental health effect and biomedical studies.     

Influence of hypoxia on wavelength dependence of differential pathlength and near-infrared quantification

Continuous wave near-infrared spectroscopy (NIRS) measurements of cardiac correlated changes in attenuation in the adult human head were computed using a Fourier analysis technique that eliminates the positive error bias associated with the magnitude of the Fourier coefficient. These attenuation changes were used to determine wavelength dependence of differential pathlength, DP(lambda), at four stages during progressive hypoxia (21, 17, 13 and 9% FIO2) in normal volunteers. The effects of incorporating DP(lambda) into NIRS algorithms to compute relative concentration changes and absolute concentration of oxyhaemoglobin and deoxyhaemoglobin are discussed. Because variations in DP(lambda) are restricted to wavelengths below 780 nm, absolute concentration calculations are influenced by hypoxia-induced changes while relative concentrations are unaffected. However, even accounting for changes in DP(lambda) did not allow computation of physiologically reasonable absolute concentrations of the haemoglobin species.     

Cardiovascular effects of cerebroventricular ouabain perfusion in the adult dog.

Cerebroventricular perfusion with artificial cerebrospinal fluid containing 10(-5) M ouabain was performed in adult dogs in order to describe the time course of the cardiovascular effect of intraventricular ouabain and to evaluate treatments to eliminate the cardiovascular effect. The central effect of ouabain caused a 56% increase in blood pressure above control values and a 35% increase in heart rate with various cardiac arrhythmias. Both alpha- and beta-adrenergic blocking drugs given intravenously.altered the pressure and rate effects ou ouabain, whereas vagotomy attenuated the effect.     

Experimental infection of chimpanzees with antihemophilic (factor VIII) materials: recovery of virus-like particles associated with non-A, non-B hepatitis.

Non-A, non-B viral hepatitis was transmitted to four colony-born chimpanzees by infusion of three lots of antihemophilic factor (factor VIII) implicated in the transmission of non-A, non-B hepatitis to two human recipients. All four inoculated animals showed histopathological evidence of viral hepatitis, and all demonstrated significant ALT elevations between seven and one-half weeks after inoculation. Acute-phase plasma from one of the infected chimpanzees (no. 771) was shown to induce non-A, non-B hepatitis in two other chimpanzees approximately three weeks after their inoculation. In addition, an acute-phase open liver wedge biopsy obtained from animal no. 771 was processed and examined by immune electron microscopy (IEM) for virus-like particles with convalescent serum from a serologically confirmed case of non-A, non-B hepatitis. Twenty-five to 30 nm (mean = 27 nm) diameter virus-like particles that were either "full" or "empty" were identified in this liver preparation by IEM. Two additional chimpanzees inoculated with a cesium chloride gradient fraction of an isopycnically banded liver homogenate (animal no. 771) also developed elevated ALT activity two to two and one-half weeks later. Our findings have experimentally verified that commercially produced factor VIII materials can induce non-A, non-B hepatitis in champanzees and that the disease can be subpassaged in these animals by inoculation of either acute-phase plasma or liver. These results also provide evidence for the association of 27 nm-diameter virus-like particles with non-A, non-B viral hepatitis.     

Hypoplasia of the cerebellar vermis and corpus callosum in thrombocytopenia with absent radius syndrome on MRI studies

Thrombocytopenia with absent radius (TAR) syndrome is infrequently (7%) associated with mental retardation. In those cases, the mental deficiency is presumed to be a consequence of intracranial hemorrhage due to the thrombo-cytopenia. We report on 2 infants with TAR syndrome. One had developmental delay with evidence of cerebral dysgenesis by magnetic resonance imaging (MRI). Such findings have not been noted in the literature, but may not have been investigated in most cases. The other infant with TAR syndrome, who has had normal psychomotor development, has a normal brain on MRI scan. Detailed neuroimaging studies, preferably MRI, should be considered in the evaluation of patients with TAR syndrome, especially when there are documented signs of developmental delay, with or without a history of intracranial hemorrhage. © 1994 Wiley-Liss, Inc.     

Controlled alterations in the physical and biological properties of R17 bacteriophage induced by gunaidine hydrochloride

The effects of guanidine hydrochloride on the physical and biological properties of R17 phage were studied to ascertain how these effects relate to the structure of the phage particle. The dialysis of phage against 3.0 M guanidine at 4 C resulted in a loss of infectivity and subtle changes in the sedimentation properties of the resulting non-infectious particles. Upon increasing the temperature of the reaction from 4 C to 37 C, additional physical modifications were found to occur in a sequential manner, giving rise to three unique particle forms followed by the eventual breakdown of phage structure. These three modified phage forms were found to have S values of 78, 58, and 44, respectively, to contain all three macromolecules characteristic of R17 phage, and to have the buoyant density of normal phage. The RNA of these particles were sensitive to RNase, and negative stains readily penetrated their interior, suggesting that changes had occurred in the capsid. The 44S particles in particular were found to be highly unstable as judged by electron microscopic and analytical ultracentrifugational studies. Various stages in the disassembly of these particles were identified.Protein fragments directly released from 44S particles were found to be morphologically similar to 11S subunits produced during the breakdown of phage in higher concentrations of guanidine. The morphological identify of the subunits released from 44S particles and the 11S protein subunits was supported by the similarity of the two types of subunits in forming branched chains, in the arrangement of subunits within the chains, and by their cosedimentation in sucrose gradients.Further analysis of the 11S subunits showed the following characteristics: (1) three morphological configurations with the most common form having dimensions of 106 × 50 Å; (2) a sedimentation rate of 10.5–11.4S; (3) molecular weight of 240,000 daltons. On the basis of these properties and on the known properties of phage coat protein, a model is proposed to explain the structure of these subunits and their possible relalationship to the structure of the phage particle. Additional support for the proposed model of phage structure is provided by electron microscopic observations and the recently discovered functions of the A (maturation) protein.