[Separation of 20(S)-ginsenoside-Rg2 and its 20(R) epimer by reversed phase low pressure column (Rp-18) chromatography]

20(S)-Ginsenoside-Rg2 and its 20(R) epimer were successfully separated using reversed-phase low pressure column (Rp-18) chromatography. The method has proved very convenient and rapid.

[Changes of adrenoceptor density in heart and brain and the reactivity of isolated pulmonary artery ring in atherosclerotic rabbit]

The alpha-adrenoceptor density in cerebral cortex and brain stem as well as the beta-adrenoceptor density in heart were measured by radioligand binding assay in normal rabbits (group 1), atherosclerotic rabbits (group 2) and atherosclerotic rabbits treated orally with aspirin 20 mg/kg daily for 16 wk (group 3). The results showed that the beta-receptor density and the KD values of the hearts among the 3 groups and the alpha-receptor density and KD of brain stem between groups 1 and 2 were not significantly different except that the alpha-receptor density in group 3 was decreased slightly. The number of alpha 1-receptor of cerebral cortex was decreased more in group 2 than that in group 3. The contractile responses of isolated pulmonary artery ring by NE were similar among the 3 groups but the reactivity to 5-HT in group 3 was increased significantly.

Origin of ultraviolet damage in DNA

A novel ultraviolet (u.v.) footprinting technique has been used to analyze the formation of u.v. photoproducts at 250 bases of a 5 S rRNA gene under conditions where the gene is either double or single-stranded. Because many more types of u.v. damage can be detected by the u.v. footprinting technique than has been previously possible, we have been able to examine in detail why certain bases in DNA are damaged by u.v. light while others are not. Our measurements demonstrate that the ability of u.v. light to damage a given base in DNA is determined by two factors, the sequence of the DNA in the immediate vicinity of the photoproduct, and the flexibility of the DNA at the site of the photoproduct. For pyrimidines, the predominant photoreaction in double-stranded DNA involves covalent dimerization between adjacent pyrimidine residues. Dimerization is much easier in melted DNA because the geometrical changes required for adjacent pyrimidine residues to dimerize are easier in single-stranded DNA. The absorption of a u.v. photon cannot simultaneously induce the geometrical changes required for adjacent pyrimidines or other bases to dimerize with one another. Rather, upon the absorption of a u.v. photon, only those thermally excited bases that are in a geometry capable of easily forming a photodimer during excitation, can photoreact. In contrast to adjacent pyrimidines, non-adjacent pyrimidines (pyrimidines flanked on either side by a purine) do not readily form u.v. photoproducts in double-stranded DNA. Because photoreactions at non-adjacent pyrimidine residues are greatly enhanced in single-stranded DNA, their failure to form in double-helical DNA is attributed to torsional constraints imposed by the double helix which make it difficult for non-adjacent pyrimidines to adopt a geometry necessary for photoreaction. Although purines are believed to be resistant to u.v. damage, our measurements demonstrate that at moderate u.v. dosages purines which are flanked on their 5' side by two or more contiguous pyrimidines readily form u.v. photoproducts in double-stranded DNA. Flanking pyrimidines appear to activate purine photoreactions by transferring triplet excitation energy to the purine. Melting of the DNA helix greatly inhibits the ability of flanking pyrimidines to activate purine photoreactions, presumably by disrupting intimate orbital overlap required for triplet transfer.

[Changes of glomerular fixed anionic charge sites in adriamycin nephrosis in rats]

A single intravenous injection of adriamycin (5mg per kg.) into rats induced nephrosis. In the various periods of the model, alterations of glomerular anionic sites stained with colloidal iron were analyzed quantitatively by image analyzer for the first time at home and abroad. The results showed that there was a significant decrease in glomerular anionic charge sites at 3 hours after administration of adriamycin as compared with that of the control animals (P less than 0.01). Marked loss of the anionic charge sites preceded the onset of proteinuria and was steadily increasing along with progress of the disease. The results suggest that loss of glomerular anionic charge sites may play an important role in the development of proteinuria in nephrotic syndrome.

[Ilexonin A may be a slow calcium channel blocker]

Ilexonin A is an effective compound isolated from Ilex pubescens Hook. et Arn. It has been used in the clinic to treat cardiovascular diseases such as cerebral embolism and myocardial infarction. Experimental studies have shown that it inhibited thrombosis, platelet adhesion, and platelet aggregation and 5-HT release induced by collagen, ADP or A23187 in vitro and in vivo. The inhibitory effect of platelet aggregation induced by A23187 was reduced by adding CaCl2 (1mM) to the medium. It suggests that the effects of llexonin A on platelet function are possibly related to calcium. The present experiments were designed to investigate the effects of Ilexonin A on thrombin-induced Ca2+ fluxes of platelets, in which quin-2 was used to measure the cytoplasmic Ca2+ concentration. The results indicated that the free calcium concentrations of resting platelets and the platelets activated by thrombin were 78.65 +/- 7.74 nM and 871.10 +/- 123.63 nM respectively. After adding EGTA (lmM) to the medium, the calcium concentrations reduced to 34.75 +/- 7.77 nM and 50. 86 +/- 7.44 nM. Ilexonin A and verapamil markedly inhibited the thrombin induced Ca2+ influx. The IC50 was 76.8 microM and 67.5 microM respectively. But both had no effect on thrombin-induced Ca2+ release from dense tubular system. It suggests that Ilexonin A acts most likely as a calcium slow channel blocker.

[Effects of hyperlipidemic sera and lipoproteins on prostacyclin synthesis by rabbit aortic smooth muscle cells]

Effects of hyperlipidemic sera(HLS), serum high density lipoprotein (HDL) and low density lipoprotein (LDL) were studied on synthesis of prostacyclin (PGI2) by rabbit aortic smooth muscle cells (SMC) in culture. The results indicated that HDL induced a dose-dependent increase in synthesis of PGI2 by SMC. Although LDL at comparable cholesterol concentrations of HDL also induced increase in PGI2 synthesis in a dose-dependent pattern, the extent was much less than that of HDL. SMC incubated with HDL and hyperlipid + aspirin treated serum synthesized less PGI2 as compared with that incubated with normal serum, while SMC incubated with hyperlipid + 8501 treated serum produced, an amount of PGI2 closed to that after incubation with normal serum, it suggested that 8501 may stimulate directly PGI2 synthetase in SMC.

Genomic footprinting in mammalian cells with ultraviolet light

A simple and accurate genomic primer extension method has been developed to detect ultraviolet footprinting patterns of regulatory protein-DNA interactions in mammalian genomic DNA. The technique can also detect footprinting or sequencing patterns introduced into genomic DNA by other methods. Purified genomic DNA, containing either damaged bases or strand breaks introduced by footprinting or sequencing reactions, is first cut with a convenient restriction enzyme to reduce its molecular weight. A highly radioactive single-stranded DNA primer that is complementary to a region of genomic DNA whose sequence or footprint one wishes to examine is then mixed with 50 micrograms of restriction enzyme-cut genomic DNA. The primer is approximately 100 bases long and contains 85 radioactive phosphates, each of specific activity 3000 Ci/mmol (1 Ci = 37 GBq). A simple and fast method for preparing such primers is described. Following brief heat denaturation at 100 degrees C, the solution of genomic DNA and primer is cooled to 74 degrees C and a second solution containing Taq polymerase (Thermus aquaticus DNA polymerase) and the four deoxynucleotide triphosphates is added to initiate primer extension of genomic DNA. Taq polymerase extends genomic hybridized primer until its polymerization reaction is terminated either by a damaged base or strand break in genomic DNA or by the addition of dideoxynucleotide triphosphates in the polymerization reaction. The concurrent primer hybridization-extension reaction is terminated after 5 hr and unhybridized primer is digested away by mung bean nuclease. Primer-extended genomic DNA is then denatured and electrophoresed on a polyacrylamide sequencing gel, and radioactive primer extension products are revealed by autoradiography. By using this method we demonstrate that it is possible to footprint with ultraviolet light, in intact monkey cells, regulatory protein--DNA interactions along a single copy of a simian virus 40 viral genome integrated into the monkey genome.

Grating-encoded multichannel photorefractive incoherent-to-coherent optical conversion

A dynamic multichannel incoherent-to-coherent optical converter based on the photorefractive effect of SBN:Ce is described. A number of grating-encoded input images, illuminated by incoherent light, are projected onto the crystal to yield photoinduced phase gratings. Coherent positive replicas of these images are simultaneously reconstructed by a coherent read beam. A simple theoretical description of this converter and corresponding experimental results are presented.

B----A transitions within a 5 S ribosomal RNA gene are highly sequence-specific

The UV footprinting technique has been used to detect and map, at single nucleotide resolution, the formation of A conformations within a sea urchin 5S ribosomal RNA gene. Increasing amounts of the dehydrating agent, trifluorethanol, were used to induce the B----A transition. Our measurements argue that the B----A transition is highly sequence-specific. Fourteen different sequences within a fragment of DNA bearing the 5 S gene were found to undergo the B----A transition independently of one another. There is a striking relationship between the midpoint of the B----A transition for each stretch of DNA and its (G+C) content. DNA sequences at the boundary between A and B conformations do not appear to be significantly distorted. A (dAdT)8 tract at the 3' end of the 5 S gene undergoes the B----A transition in two cooperative steps suggesting that for some sequences the B----A transition may actually proceed through the formation of a previously unidentified intermediate. Although the sequence specificity of the B----A transition may be exploited by regulatory proteins when they bind DNA, our measurements argue that binding of the Xenopus laevis transcription factor 111A to 5 S genes does not.

Studies of the proliferation and differentiation of immature myeloid cells in vitro. I. Chronic myelogenous leukemia

Immature cells prepared from chronic myelogenous leukemic patients in the chronic or blastic phase of their disease were placed into suspension culture in vitro and studied over a 2-week period. Regardless of the status of the disease, the immature cells proliferated and maintained good viability. In contrast, evolution of the disease toward blastic crisis was associated with a progressive loss in the ability of the immature cells to differentiate. Cell proliferation and differentiation were independent of added growth factors.

Studies of the proliferation and differentiation of immature myeloid cells in vitro. II. Acute myelogenous leukemia

Immature myeloid cells prepared from patients with AML were placed into suspension culture and studied over a 2-week period. Cell numbers usually fell and viability was not well maintained. Some degree of differentiation was observed in most cultures. Considering these observations, together with those derived from parallel studies of immature CML cells, the data suggest that AML cells are more dependent than CML cells on environmental conditions for the maintenance of cell viability and proliferation. This is especially the case for AML cells obtained at the time of initial diagnosis. On the other hand, AML cells and myeloid blastic crisis CML cells are similar with respect to their apparent greater ability to differentiate in vitro than in vivo. The addition of recombinant hemopoietins to the suspension cultures of AML cells is associated with either increased proliferation or differentiation but not both. The cells of different patients respond differently to the different hemopoietins and the different hemopoietins produce different affects in cultures of cells obtained from the same patient.

Uracil-DNA glycosylase inhibitor gene of bacteriophage PBS2 encodes a binding protein specific for uracil-DNA glycosylase

The uracil-DNA glycosylase inhibitor gene (ugi) of the Bacillus subtilis bacteriophage PBS2 has been subcloned to a 720-base pair DNA fragment contained in pZW2-0.7 and its nucleotide sequence determined. Using nucleotide deletion analysis, we have located the cloned ugi gene along with potential regulatory elements. A promoter-like region (-10 and -35 consensus sequences) similar to other B. subtilis genes and the Shine-Dalgarno sequence characteristic of Gram-positive bacteria were both identified upstream from the initiator AUG codon. A 17-nucleotide exact inverted repeat followed by runs of adenine and thymine residues was positioned almost immediately downstream of the ochre codon. The ugi gene product was identified on sodium dodecyl sulfate-polyacrylamide gels using Escherichia coli minicells containing pZW2-0.7 and by recovering uracil-DNA glycosylase inhibitor activity following electrophoresis. The ugi gene codes for an acidic polypeptide of 9,477 molecular weight (84 amino acids) whose electrophoretic mobility was greater than predicted for a protein of this size. The mode of inhibition did not appear to involve a catalytic process nor did it directly involve inhibitor-DNA interaction. Rather, the inhibitor protein was shown to bind physically to the E. coli uracil-DNA glycosylase, forming a 36,000 molecular weight complex. This complex seems to be reversible, since inhibitor activity was recovered after heat treatment of the complex. In addition, we demonstrated that the inhibitor protein is active against uracil-DNA glycosylases isolated from several diverse biological sources but inactive against E. coli deoxyuridine triphosphatase, DNA polymerase I, and DNA polymerase alpha, beta, and gamma.

Normally cycling and latch bridges in venous smooth muscle

We have studied the mechanical properties of the crossbridges of canine saphenous venous smooth muscle during activation by electrical stimulation. A length-tension relationship study showed that at optimal length (1o) the maximum isometric tension (Po) developed was 87.9 mN/mm2. Resting tension at 1o was only 6% Po, which indicates a very compliant muscle. Active tension was observed at muscle lengths greater than 0.3 1o. The maximum shortening capacity was 0.65 1o. Force-velocity and series elastic characteristics were determined by the method of quick release to a set of load clamps applied during the course of an isometric contraction. The data were fitted by the hyperbolic Hill equation. Estimated maximum shortening velocity at zero load (Vo) an index of the crossbridge cycling rate) was 0.26 1o/s which was attained early in the contraction (5 s after the stimulation). A 11.9% decline in Vo was observed at the plateau of the contraction which occurred at 15 s. The stress (sigma)-strain (epsilon) curve for the series elastic component could be approximated by the equation sigma = B[exp(A epsilon)-1], where A = 76.51 (1/1o), B = 2.89 mN/mm2 at 5 s and A = 61.49 (1/1o), B = 1.85 mN/mm2 at 15 s. Like other smooth muscles, in general, saphenous vein develops considerable isometric tension and has a high shortening capacity but a low shortening velocity. The reduction in shortening velocity that occurs after 5 s in an isometric contraction is probably due to the development of so-called latch bridges.

Ticlopidine in China: comparative study on the effect of two dose levels on bleeding time and platelet function in healthy volunteers

The compared inhibitory effects of two dose levels of ticlopidine (250 and 500 mg/day) on bleeding time and platelet function in Chinese volunteers have been studied in a placebo-controlled study. Ticlopidine exerted several significant effects: namely prolongation of bleeding time, inhibition of ADP-induced platelet aggregation, reduction of the thromboxane B2 synthesis induced by collagen as well as by ADP. The daily dose of 250 mg did not show significantly different effects as compared to the western, usually recommended daily dose of 500 mg. At the daily dose of 500 mg, adverse reactions occurred more frequently than at the daily dose of 250 mg, but no serious side effects necessitating discontinuation of treatment, or abnormalities in hematological and liver function parameters were observed at these two dose levels. In Chinese people, ticlopidine therapy should be administered at a daily dose of 250 mg.

Changes in arachidonic acid metabolite patterns in alloxan-induced diabetic rats

The vasodepressor responses to intravenous injections of arachidonic acid, and the formation of its metabolites, were studied in rats made diabetic 1 or 2 weeks after a 1-dose alloxan treatment. Arachidonic acid dose-dependently decreased the diastolic blood pressure in normal animals, but this hypotensive effect was significantly weaker in 2-week postalloxan-treated rats. Indometacin abolished arachidonic-acid-induced depressor responses in both normal and diabetic animals. Hypotension induced by sodium nitroprusside was of the same magnitude in non-diabetic and insulin deficient rats. Plasma levels of thromboxane B2 were significantly increased in both the 1- and 2-week diabetic rats, being greater in the latter group; those of 6-keto-PGF1 alpha remained unchanged during the 2-week diabetic period. It is concluded that the attenuation by diabetes of depressor responses to arachidonic acid could be due to changes in the thromboxane/prostacyclin balance, with thromboxane formation being elevated whereas prostacyclin generation remains unaffected.

How rapid are the internal reactions of the ubiquinol:cytochrome c 2 oxidoreductase?

The temperature dependence of the partial reactions leading to turn-over of the UQH2:cyt c 2 oxidoreductase of Rhodobacter sphaeroides have been studied. The redox properties of the cytochrome components show a weak temperature dependence over the range 280-330 K, with coefficients of about 1 m V per degree; our results suggest that the other components show similar dependencies, so that no significant change in the gradient of standard free-energy between components occurs over this temperature range. The rates of the reactions of the high potential chain (the Rieske iron sulfur center, cytochromes c 1 and c 2, reaction center primary donor) show a weak temperature dependence, indicating an activation energy < 8 kJ per mole for electron transfer in this chain. The oxidation of ubiquinol at the Qz-site of the complex showed a strong temperature dependence, with an activation energy of about 32 kJ mole(-1). The electron transfer from cytochrome b-566 to cytochrome b-561 was not rate determining at any temperature, and did not contribute to the energy barrier. The activation energy of 32 kJ mole(-1) for quinol oxidation was the same for all states of the quinone pool (fully oxidized, partially reduced, or fully reduced before the flash). We suggest that the activation barrier is in the reaction by which ubiquinol at the catalytic site is oxidized to semiquinone. The most economical scheme for this reaction would have the semiquinone intermediate at the energy level indicated by the activation barrier. We discuss the plausibility of this simple model, and the values for rate constants, stability constant, the redox potentials of the intermediate couples, and the binding constant for the semiquinone, which are pertinent to the mechanism of the ubiquinol oxidizing site.

Immune responses in mice to different noncovalent complexes of meningococcal B polysaccharide and outer membrane proteins

Noncovalent complexes of meningococcal group B polysaccharide and outer membrane proteins (OMPs) from serotypes 2a, 2b, 6, 8, and 15 were made either by coextraction of the two components from culture supernatants or by separate preparation of both OMPs and B polysaccharide with subsequent mixing of the two components. The former method showed a markedly greater degree of binding of B polysaccharide to OMPs, a less heterogeneous composition of OMPs, and a lower lipopolysaccharide content. Immunization of mice with these complexes showed that a higher degree of binding of B polysaccharide to OMPs resulted in a higher anti-B response. Western blotting (immunoblotting) and solid-phase radioimmunoassay techniques confirmed that antibody cross-reactions occur among OMP serotypes. The occurrence of common T-cell determinants between OMP serotypes was suggested when mice primed with a type 6 OMP complex and challenged with a homologous or heterologous serotype complex responded with significantly higher anti-B titers than unprimed animals. These memory T cells persisted for at least 12 months in mice.

Assessing the risks of releasing recombinant Streptomyces in soil

Streptomyces spp. are soil microorganisms that are important in decomposition of organic matter in soil. Genetic exchange among Streptomyces species is known to occur readily both on agar and in soil in the laboratory and evidence indicates that transfer of genes from released recombinant Streptomyces to native soil streptomycetes also occurs. Minimal data are available on the environmental effects of such gene transfer.

Multibeam coupling in photorefractive SBN:Ce

Theoretical and experimental results are presented for simultaneous multibeam coupling in photorefractive SBN:Ce. Within a single crystal, multiple signals are amplified through a coupling process that employs a single pump. The coupling gain of each signal results from coupling both between the pump and the signal and between different signals. The amount of gain that each signal receives is dependent on the intensity of the incident signal; thus a competition for the gain exists among the various signals.

Differential expression of cellular oncogenes during rat liver development

The expression of a number of proto-oncogenes (myc, erb B, Ha-ras, bas, rel, mos, sis, myb, ki-ras, fms, src and fos) was studied in developing rat liver. Northern blot hybridization shows that cellular counterpart of erb B, Ha-ras, and fos oncogenes were in an early stage of liver development, and the expressions of these proto-oncogenes gradually decreased as the liver developed, while c-myc transcript was found only in the rat fetal liver. The transcripts of these oncogenes were found in high level in Morris hepatoma 7777. Bas proto-oncogene was found in high expression at early stages of rat liver development but was not in hepatoma 7777. The expression of other proto-oncogenes studied (src, fm, rel, mos, sis, myb and ki-ras) did not change significantly during liver development and was almost the same in hepatoma and normal adult liver. Southern blot analysis demonstrates that gene amplification and apparent gene rearrangement were not responsible for the change in expression of erb B, Ha-ras, myc and fos proto-oncogenes. Our study gives further evidence that erb B, myc, Ha-ras and fos proto-oncogenes are involved in the control of cell growth and in the process of rat hepatocarcinogenesis.