[Expression and clinical significance of the AgNOR and PCNA in Barrett's adenocarcinoma and its precancerous lesions]

In order to investigate the expression of AgNOR and PCNA in malignant Barrett's esophagus and benign Barrett's esophagus with or without dysplasia, 50 specimens and biopsies were examined using silver-staining and immunohistochemical methods. The results showed that the expression of AgNOR and PCNA in malignant Barrett's esophagus were higher than those in benign Barrett's esophagus with dysplasia, which were in turn higher than those in benign Barrett's esophagus without dysplasia. The difference between malignant group and other groups was significant. The results suggest that AgNOR and PCNA may be useful as an adjunct in screening patients with Barrett's esophagus for early malignant change, especially in high-grade dysplasia group.

Small changes in cationic substituents of diphenylfuran derivatives have major effects on the binding affinity and the binding mode with RNA helical duplexes

The interactions of dicationic, 2-4, and tetracationic, 5-7, diphenylfuran analogs of 1 (furamidine) with RNA have been analyzed by thermal melting, spectroscopic, viscometric, kinetic and molecular-modeling techniques. The results of these studies indicate that most of the furan derivatives bind to RNA duplexes by intercalation in contrast to their minor-groove binding mode in AT sequences of DNA, but similar to their binding mode in GC rich regions of DNA. The highest affinity for RNA is found for an imidazoline dication, 2. With some substituents which inhibit formation of a strong intercalation complex, the results suggest a non-intercalative type of binding occurs. The non-intercalative binding probably occurs through a complex with the furan derivative bound in the narrow, deep major groove of A-form RNA helices.

Kinetics and products of OH radical addition to baicalin

The reaction of OH radicals with baicalin was studied by pulse and gamma radiolysis in N2O-saturated aqueous solutions. The addition of an OH radical to baicalin produced an intermediate species that shows a maximum UV absorbance band at 420 nm and decays with a unimolecular rate constant of 1.25 x 10(4) s-1 and a bimolecular rate constant of 6.1 x 10(8) mol-1 dm3 s-1. Four major final products were obtained by gamma irradiation, and their structures were identified. Two of them (P1 and P2) are suggested to originate from the unimolecular reaction and the other two (P3 and P4) from the bimolecular reaction of the radicals.

[Clinical application of the bilobed flap with first volardorsal artery in repair of the hand]

We report the successful use of the bilobed flap pedicled with the first volardorsal artery of the hand to repair the defects of the first web, thenar, vola or reconstruct the thumb in ten cases. The flap ranged from 3 cm x 10 cm to 5 cm x 13 cm. The width of the pedicle was 1.5-2.5 cm. The size of each lobe was 2 cm x 3.5 cm to 3 cm x 6 cm. The article discusses the anatomy of the flap, operation method and indications.

Assay of pancreatic lipase with the surface acoustic wave sensor system

A new type of surface acoustic wave sensor system for assaying the activity of pancreatic lipase has been proposed. The assay of this enzyme is based on the change in conductance of the solution caused by the release of a fatty acid, using triolein as a substrate. A linear relationship between frequency response and enzyme concentration is obtained. Kinetic parameters of pancreatic lipase, i.e., the Michaelis constant for triolein and the corresponding maximum initial rate, are estimated to be 5.46 mM and 7551.6 Hz/min, respectively. The effects of temperature and pH value are also investigated.

Quantitative magnetic resonance flow and diffusion imaging in porous media

Quantitative flow and diffusion measurements have been made for water in model porous media, using magnetic resonance micro-imaging methods. The samples consisted of compacted glass beads of various sizes down to 1 mm diameter. Typical flow and diffusion images exhibited a spatial resolution of 117 microns x 117 microns and velocities in the range 1-2 mm/s. Comparison of volume flow rates calculated from the flow velocity maps with values measured directly yielded good agreement in all cases. There was also good agreement between the mean diffusion coefficient of water calculated from the diffusion maps and the bulk diffusion coefficient for pure water at the same temperature. In addition, the mean diffusion coefficient did not depend on the pore sizes in the bead diameter range of 1-3 mm. Our results also show that partial volume effects can be compensated by appropriate thresholding of the images prior to the final Fourier transformation in the flow-encoding dimension.

Failure to detect Trichinella spiralis p43 in isolated host nuclei and in irradiated larvae of infected muscle cells which express the infected cell phenotype

Infection by Trichinella spiralis induces host muscle cells to become repositioned within the cell cycle and to lose differentiated skeletal muscle characteristics. Antibodies to a 43-kDa excretory-secretory (ES) protein (p43) also bind to infected host cell nuclei. Neither the identity of these nuclear antigens nor their role in inducing the infected cell phenotype is known. To address these issues, infected cell nuclei were isolated and nuclear antigens analyzed with several antibody preparations to p43. Four antibody preparations to p43 recognized 43-, 45-, 50-, 67- and 71-kDa proteins in ES extracts. The prominent proteins recognized by these antibodies in host nuclear antigen extracts were 71, 79, 86 and 97 kDa. Less prominent proteins of approximately 43 and 45 kDa were detected in nuclear extracts. However, antibodies which specifically recognized p43 failed to bind detectably with in situ and isolated host nuclei and nuclear extracts. Expression of p43 was analyzed in host cells infected by newborn larvae irradiated with 60Co. This treatment prevented expression of detectable levels of p43 in resulting muscle larvae, while infected muscle cells displayed typical infected cell characteristics. However, anti-p43 antibodies which recognized multiple ES and nuclear proteins did stain nuclei of irradiated larva-infected cells, albeit at reduced levels. The results raise doubts that p43 is required for induction of the infected cell phenotype. Nevertheless, nuclear antigens recognized by anti-p53 antibodies remain as candidates for influencing this phenotype.

The interaction of intercalators and groove-binding agents with DNA triple-helical structures: the influence of ligand structure, DNA backbone modifications and sequence

The effects of ligand structure and properties, DNA backbone modifications and DNA sequence on the interaction of a variety of well-known groove-binding agents and intercalators with DNA duplexes and triplexes have been evaluated by thermal melting experiments and molecular modeling. Both methylphosphonate and phosphorothioate substitutions generally destabilize DNA duplexes and triplexes. Modified duplexes can be strongly stabilized by both groove-binding agents and intercalators whereas triplexes are primarily stabilized by intercalators. Of the compounds tested, the intercalators coralyne and quinacrine provide the largest stabilization of the triplex dT19.dA19.dT19. Molecular modeling studies suggest that the large intercalating ring system of coralyne stacks well with the triplex bases whereas the alkylamino side chain of quinacrine fits snugly into the remaining space of the major groove of dT19.dA19.dT19 triplex and forms extensive van der Waals contacts with the thymine methyl groups that line the groove. Converting some of the T.A.T base triples to C+.G.C (e.g. dT19.dA19.dT19 to d(T4C+)3T4.d(A4G)3A4.(T4C)3T4) causes very significant decreases in observed Tm increases for compounds such as quinacrine and coralyne. Although removal of thymine methyl groups and addition of positive charge on substitution of C+.G.C for T.A.T should reduce binding of cationic intercalators, the large difference observed between the pure AT and the mixed sequence triplexes suggest that they may also have differences in structure and properties.

DNA triple-helix specific intercalators as antigene enhancers: unfused aromatic cations

Triple-helical structures involving the interaction of an oligonucleotide third strand with a duplex nucleic acid sequence have recently gained attention as a therapeutic strategy in the "antigene" approach [cf. Helene, C. (1991) Eur. J. Cancer 27, 1466-1471]. This method utilizes the triple helix formed from the cellular duplex and an added third strand to directly regulate the activity of a selected gene. The limited stability of nucleic acid triple-helical interactions, particularly if the third strand has backbone modifications such as methylphosphonate or phosphorothioate substitutions, is a limiting condition for the use of this approach. We have designed and synthesized compounds, on the basis of the following three criteria, that we feel should provide selective interactions and significant stabilization of triplexes: appropriate aromatic surface area for stacking with triplex bases in an intercalation complex, positive charge, and limited torsional freedom in the aromatic system to match the propeller twist of the triple-base interactions in the triplex. A series of quinoline derivatives with an alkylamine side chain at the 4-position and with different aryl substituents at the 2-position has been synthesized as our first compounds. A 2-naphthyl derivative provides significant and selective stabilization of the triplex. In a 0.2 M NaCl buffer, the naphthyl derivative increased the Tm for the triplex (triplex to duplex and third strand transition) by approximately 30 degrees C more than the Tm increase for the duplex (duplex to single strands transition). Spectral changes and energy-transfer results indicate that the naphthyl compound and related derivatives bind to the triplex by intercalation.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunological status and pathology of coxsackie B viral myocarditis and dilated cardiomyopathy

The changes in 15 cases of viral myocarditis and 28 cases of dilated cardiomyopathy were reported and compared, which were the pathological changes of endomyocardial biopsy; NK cells activity; % of peripheral T lymphocytes and its subsets determined by using OKT3,4,8 (OKT3-peripheral total lymphocytes; OKT4-helper cells; OKT8-suppressive cells) monoclonal antibody; values of immunoglobulin IgG, IgA, IgM; titer of coxsackie B antibody neutralization test. And a discussion on their relationship was included.

Flow-selective pulse sequences

A series of pulse sequences is described which selectively excite signals only from flowing spins. The method is based on the binomial selective excitation sequences employed for solvent suppression in NMR spectroscopy, combined with 180 degrees refocusing of chemical shift and static field inhomogeneity effects and the application of bipolar gradients to distinguish stationary from flowing spins. The effectiveness of the method is demonstrated by experiments on a simple flow phantom.

A molecular mechanics investigation of RNA complexes. I. Ethidium intercalation in an HIV-1 TAR RNA sequence with an unpaired adenosine

Nucleic acid complexes with ethidium intercalated into different sites in a segment of HIV-1 TAR RNA with an unpaired A base, along with corresponding complexes with a normal RNA sequence without an unpaired base were studied by molecular mechanics energy minimization methods. Different intercalation geometries as well as different orientations of the ethidium molecule in the intercalation sites were tested. A general binding affinity enhancement for the ethidium binding to the bulge sequence compared with the normal RNA segment was obtained. With the unpaired adenosine base stacked in the duplex, the binding site adjacent to the 3' side of the bulge was found to be the most energetically favorable binding site, and the intercalation site 5' to the bulge in the same sequence is much less favorable. Unique correlated backbone conformational changes on binding of ethidium to the intercalation site 3' to the bulge were found to relieve backbone strains caused by the stacking of the unpaired base into the helix. These backbone conformational changes present a plausible molecular basis for the experimentally observed ethidium binding preference in this bulge RNA segment (L.S. Ratmeyer, R. Vinayak, G. Zon and W.D. Wilson, J. Med. Chem. 35, 966, 1992).

Laser photolysis of cytosine, cytidine and dCMP in aqueous solution

Laser photolysis of cytosine and cytosine derivatives (cytidine and 2'-deoxycytidine-5'-monophosphate) using acetone as a sensitizer have been carried out in aqueous solution using a KrF laser. The absorption spectra of triplet states of cytosine and cytosine derivatives have been observed for the first time. From detailed kinetic analyses, the reaction mechanisms including triplet-triplet excitation transfer, and intramolecular excitation transfer within the exciplex arising from the interaction of triplet acetone with cytosine and cytosine derivatives, have been suggested. Accordingly, a series of kinetic parameters have also been obtained.

Heterogeneity among heat-labile enterotoxins produced by porcine enterotoxigenic Escherichia coli

The heat-labile enterotoxins (LT) produced by various porcine strains (LTp) of enterotoxigenic Escherichia coli were purified to homogeneity and their molecular properties were compared with each other. By double gel diffusion and rabbit skin permeability test, LTps from WT-1 (LTp-WT-1) and BO-149 (LTp-BO-149) strains were antigenically and biologically identical. By polyacrylamide gel electrophoresis with sodium dodecyl sulfate (SDS), the mobilities of A and B subunits of LTp (BO-149) were identical to those of LTp (WT-1). However, on polyacrylamide gel electrophoresis without SDS, LTp (BO-149) and LTp (WT-1) differed in mobility, suggesting their molecular differences. Though the pI value of the B subunit of LTp (BO-149) was identical to that of LTp (WT-1), the pI value of the A subunit of LTp (BO-149) was higher than that of LTp (WT-1). These data suggest that there is molecular heterogeneity among LTps produced by the two porcine enterotoxigenic Escherichia coli strains.

Clinical and experimental observations on treatment of peptic ulcer with wei yang an (easing peptic-ulcer) capsule

The therapeutic effects of peptic ulcer treated with cimetidine and Wei Yang An were compared clinically and experimentally by the double blind method. Results showed that the effects of the two are similar, but the long-term effect of Wei Yang An was better. Wei Yang An was also good for most cimetidine resistant ulcers, with few side effect. Animal experiment showed that Wei Yang An inhibited the ulcers.

Evidence that combined thromboxane A2 and serotonin receptor blockade might prevent coronary artery thrombosis and the conversion from chronic to acute coronary heart disease syndromes

Evidence that combined thromboxane A2 and serotonin blockade may prevent coronary artery thrombosis and the conversion from chronic to acute coronary heart disease syndromes is considered. Available data from clinical and experimental animal studies are consistent with the hypothesis that interference with thromboxane and serotonin's contributions to platelet aggregation and dynamic coronary artery constriction might prevent the conversion from chronic to acute disorders, including the development of unstable angina and myocardial infarction in some patients at risk. Substantial protection preventing the conversion from stable to unstable angina and myocardial infarction may very well require both thromboxane and serotonin receptor antagonists or the combination of a thromboxane synthesis inhibitor and receptor antagonist with a serotonin receptor antagonist. Future clinical studies should test this hypothesis directly.

Chinese intellectuals and science: a history of the Chinese Academy of Sciences (CAS)

The Chinese Academy of Sciences, founded in 1949 – the same year as the People's Republic of China – has attempted to use science to speed up technological, economic, and defense-related development, as well as the entire process of modernization. At' the same time, political structures on the development of science have hampered scientific output and kept it to a level that was far below what might have been expected from the creative potential of China's scientists.

Early in this century, when modern science was brought to China by foreign missionaries and by scientists and students returning from abroad, only a few people in the country were engaged in scientific research. In 1928 and 1929, two state-run comprehensive research establishments were founded: the Academia Sinica, consisting mainly of scientists who had studied in the United States, and the Peking Academy, consisting mainly of European-trained scientists. Two decades later, a month after the proclamation of the People's Republic of China, a single national scientific research body was founded: the Chinese Academy of Sciences (CAS). This article will review the contribution and status of the CAS, its successes and its failures in the ensuing forty years.