Delay of squeezing and entanglement using electromagnetically induced transparency in a vapour cell.

We demonstrate experimentally the delay of squeezed light and entanglement using Electromagnetically Induced Transparency (EIT) in a rubidium vapour cell. We perform quadrature amplitude measurements of the probe field and find no appreciable excess noise from the EIT process. From input squeezing of 3.2+/-0.5 dB at low sideband frequencies, we observed the survival of 2.0+/-0.5 dB of squeezing at the EIT output. By splitting the squeezed light on a beam-splitter, we generated biased entanglement between two beams. We transmit one of the entangled beams through the EIT cell and correlate the quantum statistics of this beam with its entangled counterpart. We experimentally observed a 2.2+/-0.5 micros delay of the biased entanglement and obtained a preserved degree of wavefunction inseparability of 0.71+/-0.01, below the unity value for separable states.

Proto-oncogene c-ros codes for a molecule with structural features common to those of growth factor receptors and displays tissue specific and developmentally regulated expression.

A recombinant DNA clone containing cellular sequences homologous to the transforming sequence, v-ros, of avian sarcoma virus UR2 was isolated from a chicken genomic DNA library. Heteroduplex mapping and nucleotide sequencing reveal that the v-ros sequences are distributed in nine exons ranging from 65 to 204 nucleotides on cellular ros (c-ros) DNA over a range of 11 kilobases. Comparison of the deduced amino acid sequences of c-ros and v-ros shows two differences: v-ros contains a three-amino-acid insertion within the hydrophobic domain presumed to be involved in membrane association, and (ii) the carboxyl 12 amino acids of v-ros are completely different from those of the deduced c-ros sequence. The deduced amino acid sequence of c-ros bears striking structural features similar to those of insulin and epidermal growth factor receptors, including the presumed hydrophobic membrane binding domain, amino acids flanking the domain, and the distance between the domain and the catalytic region of the kinase activity. The expression of c-ros appears to be under a very stringent control. When tissues at various stages of chicken development were analyzed, only kidney was found to contain a significant level of c-ros RNA. The level of c-ros RNA in kidney tissue is most abundant in 7- to 14-day-old chickens. Finally, nucleotide sequences of c-ros DNA and UR2-associated helper viral genome at regions corresponding to the gag ros recombination site suggest that the junction has been formed by RNA splicing.

Interference of the simian virus 40 origin of replication by the cytomegalovirus immediate early gene enhancer: evidence for competition of active regulatory chromatin conformation in a single domain.

Replication origins are often found closely associated with transcription regulatory elements in both prokaryotic and eukaryotic cells. To examine the relationship between these two elements, we studied the effect of a strong promoter-enhancer on simian virus 40 (SV40) DNA replication. The human cytomegalovirus (CMV) immediate early gene enhancer-promoter was found to exert a strong inhibitory effect on SV40 origin-based plasmid replication in Cos-1 cells in a position- and dose-dependent manner. Deletion analysis indicated that the effect was exerted by sequences located in the enhancer portion of the CMV sequence, thus excluding the mechanism of origin occlusion by transcription. Insertion of extra copies of the SV40 origin only partially alleviated the inhibition. Analysis of nuclease-sensitive cleavage sites of chromatin containing the transfected plasmids indicate that the chromatin was cleaved at one of the regulatory sites in the plasmids containing more than one regulatory site, suggesting that only one nuclease-hypersensitive site existed per chromatin. A positive correlation was found between the degree of inhibition of DNA replication and the decrease of P1 cleavage frequency at the SV40 origin. The CMV enhancer was also found to exhibit an inhibitory effect on the CMV enhancer-promoter driving chloramphenicol acetyltransferase expression in a dose-dependent manner. Together these results suggest that inhibition of SV40 origin-based DNA replication by the CMV enhancer is due to intramolecular competition for the formation of active chromatin structure.

Frequent gain of copy number on the long arm of chromosome 3 in human cervical adenocarcinoma.

We analyzed genomic aberrations in 20 cervical adenocarcinomas by comparative genomic hybridization (CGH). Most tissue samples (85%) showed DNA copy number changes; gains were more common than losses. The most consistent region of chromosomal gain was mapped to chromosome arm 3q, found in 70% of the cases, with a minimal common region of 3q28-ter. Other recurrent amplifications of genetic material were detected on 17q (45%), 1p (30%), 1q (25%), and 11q (20%). High-level copy number increases were found in chromosomal regions 3q27-ter and 9pter-13. DNA losses were seldom observed, occurring primarily in underrepresented regions of chromosome arms 4q, 13q, and 18q. The presence of high-risk human papilloma virus genomes in the cervical adenocarcinoma samples was detected in 90% of the cases. However, there was no correlation between human papilloma virus type and the pattern of genomic changes. This study is the first report of CGH analysis in human cervical adenocarcinoma. Among the major genomic alterations, our results demonstrate the importance of DNA copy increases of chromosome arm 3q in the development of cervical adenocarcinoma and identify other amplified chromosomal regions that are also associated with cervical carcinogenesis.

Induction of pulmonary fibrosis in organ-cultured rat lung by cadmium chloride and transforming growth factor-beta1.

Cadmium chloride (CdCl2) exposure has been reported to induce pulmonary fibrosis in rats. Accumulating evidence has shown that cytokines play a pivotal role in the excessive production of connective tissue components in pulmonary fibrosis. In this report, rat lung slice cultures were used to study the synergistic involvement of transforming growth factor-beta1 (TGF-beta1) in CdCl2-induced alveolar fibrosis. Rat lung slices were maintained at the interphase of air and medium on a polyester mesh stretched on a plastic scaffold. Treatment of lung slices with 2.5, 5 or 10 microM CdCl2 for 7 days resulted in 85, 40 and 6% respectively for relative survival. Under these culture conditions, CdCl2 alone did not induce alveolar fibrosis in rat lung slices. However, in the presence of 0.5 ng/ml TGF-beta1, CdCl2 at a dose ranging from 1 to 5 microM increased the thickness of alveolar septa. Furthermore, the thickness of alveolar septa in lung slices treated with CdCl2 was dose-dependently increased by the presence of TGF-beta1. The thickened alveolar septa were apparently due to the deposition of excessive extracellular matrix, as revealed by trichrome stain and ultrastructural examination. Our results also show that fibrogenic activity induced by the combined treatment with CdCl2 and TGF-beta1 can be reduced by co-treatment with 200 microg/ml lambda-carrageenan, a TGF-beta1 inhibitor. Therefore, the present results indicate that TGF-beta1 can synergistically stimulate the fibrogenic activity in lung tissue subsequent to CdCl2 injury.

[Effects of nasal continuous positive airway pressure on patients with obstructive sleep apnea syndrome].

To evaluate the efficacy of nasal continuous positive airway pressure (CPAP) on patients with obstructive sleep apnea syndrome, 20 patients with moderate to severe obstructive sleep apnea syndrome (respiratory disturbance index greater than or equal to 20) were studied. The patients were evaluated using the Grass polysomnograph model 78 during an overnight sleep one to two weeks apart with and without a nasal CPAP produced by 10 to 15 cm of water. The results showed that nasal CPAP significantly reduced the respiratory disturbance index (RDI) (p less than 0.001) and the desaturation index (p less than 0.001), and significantly raised the lowest oxygen saturation level. Nasal CPAP not only reduced RDI, but also improved the respiratory patterns during obstructive apnea events by shifting the obstructive apnea events to hypopnea events. Nasal CPAP also significantly decreased the relative time spent in stage 1 NREM sleep (p less than 0.001), and increased the relative time spent in stages 3+4 NREM and REM sleep (p less than 0.05). Most of the patients also felt better the morning after using nasal CPAP. Nasal CPAP significantly reduced the frequency and duration of apnea and the degree of nocturnal oxygen desaturation, and improved the respiratory patterns during obstructive apnea events, as well as the sleep architecture in obstructive sleep apnea patients. We conclude that nasal CPAP is effective in moderate to severe obstructive sleep apnea syndrome patients.

Using a focus group study to explore perceptions of health-promoting self-care in community-dwelling older adults.

The purpose of this study was to explore perceptions of health-promoting self-care in community-dwelling older adults. A focus group was conducted to obtain the perceptions and experiences of older adults concerning health-promoting self-care in their daily lives. Twenty-one volunteers from a Golden-Age Association in Kaohsiung City, including 10 males and 11 females, agreed to participate in this study. The mean age of the participants was 73.5 years, with ages ranging from 67 to 83. Three focus group sessions were held and 21 participants participated in all three sessions. Each focus group session lasted from 2.5 to 3 hours. The sessions were audio tape recorded and then verbatim transcripts were used for content analysis. Through a peer discussion, 51 behavioral units were extracted and categorized as five major themes including "balancing", "initiating", "regularizing", "socializing", and "sublimating". The findings can contribute to basic nursing knowledge related to health-promoting self-care and provide the basis for designing nursing strategies to enhance health-promoting self-care for older adults in the community.

Quantum study of information delay in electromagnetically induced transparency.

Using electromagnetically induced transparency (EIT), it is possible to delay and store light in atomic ensembles. Theoretical modeling and recent experiments have suggested that the EIT storage mechanism can be used as a memory for quantum information. We present experiments that quantify the noise performance of an EIT system for conjugate amplitude and phase quadratures. It is shown that our EIT system adds excess noise to the delayed light that has not hitherto been predicted by published theoretical modeling. In analogy with other continuous-variable quantum information systems, the performance of our EIT system is characterized in terms of conditional variance and signal transfer.

Electron microscopic evidence for the cruciform structure in intracellular SV40 DNA.

The conformation of intracellular SV40 DNA during lytic infection of CV-1 cells was studied by the psoralen crosslinking technique. Analysis of the crosslinked SV40 DNA in the electron microscope revealed a rare population (0.1%) with a cruciform structure at coordinates 0.62 +/- 0.05 or at 0.37 +/- 0.05 of the SV40 genome. The implication of this observation in relation to SV40 DNA replication is discussed.

Visualization of novel simian virus 40 DNA recombination intermediates induced by ultraviolet light irradiation.

Electron microscopic technique was used to examine the structures of SV40 DNA recombination intermediates induced by ultraviolet irradiation as an approach for understanding recombination mechanisms in animal cells. Putative recombination intermediate with the characteristic Holliday junction was observed in both SV40 and CV-1 monkey kidney cell DNA. These results suggest that Holliday recombination intermediate is a common intermediate in eukaryotic as well as prokaryotic recombination pathways. In UV irradiated cells, putative SV40 DNA recombination intermediates with multiple recombining partners were observed. In addition, UV irradiation induced two types of novel joint molecules of SV40 DNA. The first type contains replication intermediates as one of the joint molecules with the putative recombination junction located in the newly replicated DNA arms. The second type of novel joint molecules is represented by of the 'dumbbell' structures with two circular SV40 DNA linked by a linear DNA of varying lengths. The structures of these novel recombination intermediates suggest a strand-invasion mechanism for UV-induced DNA recombination.

Electron microscope analysis of partial denaturation of F factor deoxyribonucleic acid.

Partial denaturation pattern of sex factor deoxyribonucleic acid of Escherichia coli was studied by electron microscopy. Clustering of the adenine-plusthymine-rich regions in one part of the molecule was revealed. The positions of these regions were located on the physical map of F by analyzing the partial denaturation pattern of heteroduplexes between F and F-prime factors with various parts of F sequences deleted.

Involvement of topoisomerases in replication, transcription, and packaging of the linear adenovirus genome.

The role of topoisomerases in the replication of human adenovirus type 5 was investigated with topoisomerase inhibitors. Both topoisomerase I and topoisomerase II inhibitors blocked adenovirus replication when added at the time of infection. Both types of inhibitors induced strand cleavages at specific sites in the adenovirus early templates. The cleavage sites were mapped near the 5' and 3' ends of the genes transcribed early during infection. At late times after infection, camptothecin, a topoisomerase I inhibitor, inhibited adenovirus DNA replication and induced the formation of single- and double-stranded fragments with breakpoints located at defined regions of the viral genome. The topoisomerase II inhibitors, VP-16 (etoposide) and ellipticine, did not block adenovirus DNA replication and did not induce an appreciable amount of double-strand cleavages in the newly synthesized DNA. On the other hand, VP-16 promoted double-strand cleavages at specific sites of nonreplicating adenovirus DNA. The packaging of adenovirus DNA into virus particles, which contain supercoiled adenovirus DNA (M.-L. Wong and M.-T. Hsu, Nucleic Acids Res. 17:3535-3550, 1989), was inhibited by the topoisomerase II inhibitors. Transcription of adenovirus major late genes was inhibited by both topoisomerase I and topoisomerase II inhibitors. In addition, camptothecin caused a premature termination of major late transcription. Electron microscopic analysis showed that adenovirus templates late after infection were arranged in topologically constrained loop domains. Together, these data provide evidence for the requirement of topoisomerase activities in the replication, transcription, and packaging of the linear adenovirus genome.

Determination of twist and handedness of a 39-base pair segment of DNA in solution.

For DNA in solution, there have been two methods for measuring the helical periodicity. One method examines the ladder of discrete bands formed in the electrophoretic pattern of supercoiled DNA. Such a ladder is assumed to reflect the set of differently linked covalently closed molecules. The other method measures the lengths of partial nuclease digestions of DNA segments affixed to flat surfaces. Neither method, however, is able to measure the absolute handedness. X-ray diffraction of DNA oligonucleotides can determine the handedness, but the DNA must necessarily be crystallized. We have developed a new method for determining the helical parameters of a segment of DNA in solution. It is the first non-crystallographic method that can directly determine both the helical periodicity and the absolute handedness of DNA. The results obtained using this method are consistent with the classical Watson-Crick right-handed double helical model.

Psoralen-cross-linking study of the organization of intracellular adenovirus nucleoprotein complexes.

We used the psoralen-cross-linking technique to investigate the structures of adenovirus nucleoprotein complexes during infection. At late times after infection, three types of psoralen cross-linking patterns were observed. A high cross-linking pattern (type I), with about one cross-link in every 10 to 17 base pairs, was found for the newly synthesized and the bulk of the adenovirus late chromatin. Viral templates involved in replication, transcription, and recombination were all found to exhibit this cross-linking pattern. These results suggest that there is no nucleosome-like organization in the unpackaged late adenovirus nucleoprotein complexes. The second type of cross-linking pattern (type II) had a low cross-linking density of about one cross-link in every 700 to 1,000 base pairs. This cross-linking pattern was found to be associated with the viral DNA in the mature virus particles. The sequences at the termini of the virion DNAs, however, were found to have higher cross-linking densities, as shown by electron microscopy. The third type of cross-linking pattern (type III) was composed of a mixture of various proportions of type I and type II patterns in a single molecule. This mixed cross-linking pattern suggests that these molecules are virion assembly intermediates, with viral DNA being partially packaged in the virus particles. The organization of adenovirus nucleoprotein complexes at early times after infection was analyzed by the gel electrophoresis technique following digestion of the DNA with a restriction enzyme that was inhibited by cross-links. Our data suggest that the viral nucleoprotein complexes at early times after infection have accessibility to psoralen cross-linking between the virion DNA and the late viral nucleoprotein complexes. The observed cross-linking density of the early nucleoprotein complex DNA, however, was inconsistent with the nucleosomelike organization suggested by previous investigators.

Evidence for variation of supercoil densities among simian virus 40 nucleoprotein complexes and for higher supercoil density in replicating complexes.

The distribution of DNA topoisomers in intracellular simian virus 40 DNA was analyzed by gel electrophoresis. The results suggested that DNA extracted from 70S chromatin had a different superhelical density distribution as compared with the DNA obtained from virions or virion assembly intermediates. The heterogeneity of simian virus 40 viral DNA superhelical density at a late time after infection was partly due to increased virion production and partly due to the intrinsic heterogeneity of the superhelical density of DNA extracted from virions. Using two-dimensional gel electrophoretic analysis we also showed that simian virus 40 DNA templates used for DNA replication have a higher average superhelical density than the bulk of intracellular viral DNA.

Ellipticine increases the superhelical density of intracellular SV40 DNA by intercalation.

We investigated the in vivo effect of ellipticine, a mammalian topoisomeraseII(topoII) inhibitor, on SV40 DNA topology. In contrast to epipodophyllotoxins, ellipticine did not cause significant double stranded cleavage of intracellular SV40 DNA. Furthermore, ellipticine reduced cleavage induced by epipodophyllotoxins, VP16 and VM26. Unexpectedly, ellipticine dramatically increased the superhelical density of a fraction of intracellular SV40 DNA. Several lines of evidence suggest that the formation of this highly supercoiled DNA species (Ih form DNA) is not due to the inhibition of topoII per se, but is the result of intercalation by ellipticine in a subfraction of the intracellular SV40 chromatin followed by the fixation of DNA linking number by a topoisomerase activity. Based on the linking number change and the known unwinding angle of ellipticine, the intercalation density was calculated as one ellipticine molecule per 10-20 bp in the Ih DNA. This result suggests the existence of different populations of intracellular SV40 chromatin with respect to the accessibility to ellipticine intercalation.