Three new DNA helicases from Saccharomyces cerevisiae

At least six DNA helicases have been identified during fractionation of extracts from the yeast Saccharomyces cerevisiae. Three of those, DNA helicases B, C, and D, have been further purified and characterized. DNA helicases B and C co-purified with DNA polymerase delta through several chromatographic steps, but were separated from the polymerase by hydrophobic chromatography. DNA helicase D co-purified with Replication Factor C over seven chromatographic steps, and was only separated from it by glycerol gradient centrifugation in the presence of 0.2 M NaCl. All three helicases are DNA dependent ATPases with Km values for ATP of 190 microM, 325 microM, and 60 microM for DNA helicases B, C, and D, respectively. Their DNA helicase activities are comparable. They are 5'-3' helicases and have pH optima of 6.5-7 and Mg2+ optima of 1-2 mM. However, they differ in the nucleotide requirement for helicase action. Whereas all three helicases preferred ATP, dATP, UTP, CTP, and dCTP as cofactors, DNA helicase C also used GTP, but not dTTP. On the other hand, DNA helicase D used dTTP, but not GTP, and DNA helicase B used neither nucleotide as cofactor. These studies allowed us to conclude that DNA helicases B, C, and D are not only distinct enzymes, but also different from two previously identified yeast DNA helicases, the RAD3 protein and ATPase III.

Treatment of 100 cases of nerve deafness with injectio radix salviae miltiorrhizae

100 cases of nerve deafness were treated with Injectio Radix Salviae Miltiorrhizae by i.v. drip, and additional drugs that promoted blood circulation were used according to symptom differentiation. Results were 28 cases cured, 45 cases improved, and 27 cases failed, for a total effective rate of 73%.

Clonal and antigenic analysis of serogroup A Neisseria meningitidis with particular reference to epidemiological features of epidemic meningitis in the People's Republic of China

Representative strains of serogroup A Neisseria meningitidis were chosen from all major meningitis epidemics worldwide since 1960 and subjected to analysis for the electrophoretic variation of 15 cytoplasmic allozymes and four outer membrane proteins. The 290 strains defined 84 unique electrophoretic types which were classified in nine subgroups. Tests with monoclonal antibodies specific for conserved pilin epitopes showed that the class I, IIa, and IIb epitopes were uniform within the subgroups. Similarly, the subgroups were uniform for expression of different variable regions of class 1 outer membrane protein, with a few minor exceptions. Many of the bacteria tested were isolated in the People's Republic of China, and the epidemiology of Chinese epidemics of meningococcal meningitis is described. The analysis approaches a global description of epidemic meningitis caused by serogroup A meningococci in the past 30 years.

Formation of the excited ferryl species following Fenton reaction

A concomitant chemiluminescence burst can be detected when hydrogen peroxide is injected into the solution containing either free or chelated ferrous iron. The duration of the burst is slightly longer than the time for the oxidation of Fe2+. The luminescence intensity is a quadratic function of the initial concentration of H2O2 and is dependent on Fe2+ concentration. The scavengers of hydroxyl radical effectively inhibit, while the previously added ferric ions enhance, the luminescence. It is proposed that the excited species responsible for the luminescence is created by the reaction of hydroxyl radical with ferric iron. The theoretical analysis based on such a mechanism can fairly well interpret the experimental observation. The present study suggests that an excited ferryl species may be formed in Fenton reaction.

Sequential 1H NMR assignments and secondary structure of the kringle domain from urokinase

The sequence-specific 1H NMR assignments of the 89-residue recombinant kringle domain from human urokinase are presented. These were achieved primarily by utilizing TOCSY and NOESY spectra in conjunction with COSY spectra recorded at 500 MHz and 600 MHz. Regular secondary structure elements have been derived from a qualitative interpretation of nuclear Overhauser enhancement, JNH alpha coupling constant, and amide proton exchange data. Two helices have been identified. One helix, involving Ser40-Gly46, corresponds to that reported for t-PA kringle 2 (Byeon et al., 1991), but does not exist in other kringles with known structures. The second helix, in the region Asn26-Gln33, is thus far unique to the urokinase kringle. Three antiparallel beta-sheets and three tight turns have also been identified, which correspond exactly to those identified in t-PA kringle 2 both in solution and in the crystalline state (de Vos et al., 1992). Despite the very different ligand binding properties of the urokinase kringle, NOE data indicate that the tertiary fold of the molecule conforms closely to that found for other kringles.

Modulation of endogenous ADP-ribosylation in rat brain

Endogenous ADP-ribosylation of proteins was measured in homogenates, membranes, and cytosol from rat brain regions. Several proteins were ADP-ribosylated in homogenates, especially a 49 kDa protein. Sodium nitroprusside, a source of nitric oxide, particularly enhanced the ADP-ribosylation of 47 kDa and 39 kDa proteins. Levels of basal and sodium nitroprusside-stimulated ADP-ribosylated proteins were similar, but not identical, in homogenates from the cerebral cortex, hippocampus, striatum, thalamus and cerebellum. In neonatal cerebral cortex, ADP-ribosylation of an additional 110 kDa protein was detected and this was also enhanced by sodium nitroprusside. ADP-ribosylation of the 110 kDa protein was evident one and two days after birth, but not at five days and later. Each protein demonstrated unique sensitivities to sodium nitroprusside and rates of ADP-ribosylation. Cyclic GMP did not mimic the effects of sodium nitroprusside. Mg2+ inhibited ADP-ribosylation of the 49 kDa and 47 kDa proteins but had a smaller effect on the 39 kDa protein. ADP-ribosylation in the cytosol predominantly affected only a single protein of 39 kDa, and this was stimulated by sodium nitroprusside and by addition of cofactors necessary for activation of nitric oxide synthase. Several proteins in membranes were ADP-ribosylated and the 49 and 47 kDa proteins were released from the membranes coincidentally with ADP-ribosylation. The predominate substrates of endogenous ADP-ribosylation did not appear to be substrates for pertussis toxin-induced ADP-ribosylation. These and previously published results indicate that nitric oxide generated from sodium nitroprusside or endogenous sources may have modulatory effects through regulation of the endogenous ADP-ribosylation of proteins.

[A comparative study of coronary arteriography and myocardial emission computed tomography in the diagnosis of coronary heart disease]

Both coronary arteriography (CAG) and myocardial emission computed tomography (ECT) were performed in 58 patients. According to CAG findings and clinical manifestations, 47 patients were diagnosed as coronary heart disease (CHD), while 11 not. CAG was abnormal in 39 patients of the 47. The sensitivity and specificity of CAG were 83% and 100% respectively. The diagnosis of CHD was made without any doubt in patients with abnormal CAG. The sensitivity of ECT was 97.9%, the specificity only 45.5%, and the predictive value of negative ECT 83.3%. Therefore, abnormal ECT should be closely related to the clinical manifestations in order to evaluate its significance and a normal ECT may rule out CHD with more reliability.

Cloning hybridomas in a reversible three-dimensional alginate matrix

Alginate is a transparent polymer of guluronic and mannuronic acids that provide a favorable microenvironment for cell growth. Alginate gelation is calcium dependent and temperature independent. To facilitate the isolation of stable and productive antibody-producing hybridomas, we have developed a technique of cloning hybridomas in the three-dimensional alginate matrix. To provide cavities for hybridoma growth, we encorporated 10-15% (v/v) gelatin into the alginate prior to gelation. We have cloned more than 90 monoclonal antibody-producing hybridomas using the alginate matrix. The alginate matrix is readily reversible with the addition of a calcium chelator. The alginate matrix permits efficient cloning in limited incubator space, without the use of a feeder layer, and with minimal amount of medium. The transparent matrix also permits easy screening for clonality and growth.

Conservation of mouse alpha A-crystallin promoter activity in chicken lens epithelial cells

Previous transfection experiments have shown that 162 base pairs (bp) of the 5' flanking sequence of the chicken alpha A-crystallin gene are required for promoter activity in primary chicken lens epithelial cells (PLE), while only 111 bp of the 5' flanking sequence are needed for activity of the mouse alpha A-crystallin promoter in transfected chicken PLE cells or in a SV40 T-antigen-transformed transfected mouse lens epithelial cell line (alpha TN4-1). The effect of site-directed mutations covering positions -111 to -34 of the mouse alpha A-crystallin promoter fused to the bacterial chloramphenicol acetyltransferase (CAT) gene was compared in transfected chicken PLE cells and mouse alpha TN4-1 cells; selected mutations were also examined in a nontransformed rabbit lens epithelial cell line (N/N1003A). In general, the same mutations reduced promoter activity in the transfected lens cells from all three species, although differences were noted. The mutations severely affected regions -111/-106 and -69/-40 regions in all the transfected cells examined; by contrast, mutations at positions -105/-99 and -87/-70 had a somewhat greater effect in the chicken PLE than the mouse alpha TN4-1 cells, while mutations of the -93/-88 sequence reduced expression in the alpha TN4-1 but not the PLE cells. A partial cDNA with sequence similarity to alpha A-CRYPB1 of the mouse has been isolated from a chicken lens library; mouse alpha A-CRYBP1 is a putative transcription factor which binds to the -66/-55 sequence of the mouse alpha A-crystallin promoter.(ABSTRACT TRUNCATED AT 250 WORDS)

Cooperative effects of C/EBP-like and NF kappa B-like binding sites on rat serum amyloid A1 gene expression in liver cells

Serum amyloid A (SAA) is a major acute-phase protein synthesized and secreted mainly by the liver. In response to inflammation, its expression is increased by 1000-fold, primarily because of a 200-fold increase in the rates of SAA gene transcription. We have shown that when 304 bp of 5' flanking region of the rat SAA1 gene is fused to a reporter gene, the chloramphenicol acetyltransferase (CAT) gene, CAT activity is induced in a cell-specific manner in response to conditioned media prepared from activated mixed lymphocyte cultures and recombinant interleukin-1. In this study, deletion of the SAA1 promoter to -120 bp with respect to the transcriptional start site did not diminish promoter activity; however, deletion to -94 bp renders the promoter completely inactive. Functional analysis have demonstrated that a 66-bp DNA fragment spanning -138 bp to -73 bp could confer cytokine responsiveness to a heterologous thymidine kinase promoter. Within this 66-bp responsive element resided an NF kappa B-like-binding site and a C/EBP-like-binding site. Although each binding site alone could confer responsiveness when stimulated with conditioned media and TPA, the response was much weaker than that observed when both sites were present. Moreover, site-specific mutations of either binding site completely abolished SAA1 promoter activity. Taken together, these results suggest a functional importance for and cooperative interaction of these two nuclear-factor binding sites in the cytokine-induced expression of the rat SAA1 gene.

[Studies on human chorionic gonadotropin (HCG)-binding protein from Pseudomonas maltophilia by ligand blotting assay]

A ligand blotting technique was developed to study the HCG-binding protein from Pseudomonas maltophilia after size separation by SDS-polyacrylamide gel electrophoresis under nonreducing conditions. The separated proteins were transferred to a nitrocellulose sheet, which was subsequently incubated with [125I]iodo HCG, and subjected to determination for radioactivity in gamma-counter. A radioactivity peak equivalent to an M(r) 70000 appeared, which was not observed when the hormone incubation was performed in the presence of an excess of unlabeled HCG. The peak also disappeared when the protein samples were treated with reducing agent, which showed that integrity disulfide bonds of the protein was essential for the protein-hormone interaction. In addition, position of the radioactivity peak which was due to the binding of [125I]iodo HCG to western blots of the HCG-binding protein was corresponding to that of the antibodies against the HCG-binding protein recognizing a 70000 protein on the western blots. These results show that the HCG-binding protein from Pseudomonas maltophilia is an M(r) 70000 protein and that the HCG-binding protein contains at least one disulfide bond essential to its binding activity.

[Hepatic carcinoma treated by hepatic arterial embolization using 131I and chemotherapeutic agent gelatin microspheres: report of 9 cases]

Nine patients with inoperable hepatoma were treated by using hepatic arterial embolization 131I and chemotherapeutic agent gelatin microsphere (131I-CA-GM). The emission CT after operation detected that the microspheres were concentrated on tumor area. The ratio between the radioactivity in tumor and that in liver was 4.1:1. A case died of ictopic embolization; the others survived 3, 4, 5, 19, 24, 7, 8, and 12 months respectively. Three of them were still alive. 131I-CA-GM has triple anticarcinogenic actions, including the arterial occlusion, targeting chemotherapy and internal radiation. The microspheres can selectively accumulate in the tumor artery and can be easily traced by gamma-camera or emission CT. 131I-CA-GM is a hopeful embolic agent for the treatment of liver cancer, but some problems about ectopic arterial embolization should be further studied.

[Comparative studies on LH/CG receptor from rat testes and hCG-binding protein from Pseudomonas maltophilia by antibodies against the hCG-binding protein]

An indirect immunoprecipitation experiment was developed to characterize the antigenic determinants of the hCG-binding protein and the rat testicular LH/CG receptor. The hCG-binding protein preincubated with 125I iodo hCG was immunologically precipitated by the antibodies against the hCG-binding protein in the presence of goat anti-rabbit IgG. Similarly, the LH/CG receptor solubilized with 1% triton X-100 from the rat testes was also immunoprecipitated by the antibodies. Furthermore, the antibodies did not inhibit the binding of 125I iodo hCG to the hCG-binding protein or to the solubilized rat testicular LH/CG receptor. From these results it can be concluded that there exists the sharing of antigenic determinants between the hCG-binding protein from Pseudomonas maltophilia and the LH/CG receptor from the rat testes and that the antibodies specifically recognize the antigenic determinants outside the hCG-binding sites on the rat testicular LH/CG receptor. Therefore, the antibodies against the hCG-binding protein are of potential applications to studies on structure and function of the mammalian LH/CG receptors.

Assignment of genes encoding a unique cytokine (IL12) composed of two unrelated subunits to chromosomes 3 and 5

IL12 (formerly NKSF or CLMF) is a unique cytokine composed of two unrelated disulfide-linked subunits. The larger 40-kDa subunit (p40) is a member of the cytokine receptor family, and the smaller 35-kDa subunit (p35) is related to IL6 and GCSF. The chromosomal localization of these two subunits was determined by PCR analysis of DNA from rodent-human hybrids. More refined mapping was obtained by PCR analysis of hybrids containing translocation chromosomes and for p40, by analysis of radiation hybrids. The subunits map to different chromosomes: p40 (IL12B) to 5q31-q33 and p35 (IL12A) to 3p12-3q13.2.

A bioassay for derivatives of qinghaosu (artemisinin)

A sensitive bioassay was developed for measuring the serum antimalarial activity for qinghaosu (artemisinin) derivatives. This should assist in the formulation of optimum regimens for the treatment of P. falciparum malaria.

[Pharmacological studies on erzhi pills]

The experimental results show that Erzhi Pills can markedly increase the weights of immunological organs in mice and antagonize the immunosuppressive action of prednisolone. The diameter of SRID precipitating ring, the hemolytic ability of PFC and the clearance rate of i.v. charcoal particles in mice can all be increased by the pills. Erzhi Pills also protect mice from CCl4 intoxication. Steamed Ligustrum lucidum has the same action as Erzhi Pills.