Flagellar motor-switch binding face of CheY and the biochemical basis of suppression by CheY mutants that compensate for motor-switch defects in Escherichia coli

CheY is a response regulator protein of Escherichia coli that interacts with the flagellar motor-switch complex to modulate flagellar rotation during chemotaxis. The switch complex is composed of three proteins, FliG, FliM, and FliN. Recent biochemical data suggest a direct interaction of CheY with FliM. In order to determine the FliM binding face of CheY, we isolated dominant suppressors of fliM mutations in cheY with limited allele specificity. The protein products of suppressor cheY alleles were purified and assayed for FliM binding. Six out of nine CheY mutants were defective in FliM binding. Suppressor amino acid substitutions were mapped on the crystal structure of CheY showing clustering of reduced binding mutations on a solvent-accessible face of CheY, thus revealing a FliM binding face of CheY. To examine the basis of genetic suppression, we cloned, purified, and tested FliM mutants for CheY binding. Like the wild-type FliM, the mutants were also defective in binding to various CheY suppressor mutants. This was not expected if CheY suppressors were compensatory conformational suppressors. Furthermore, a comparison of flagellar rotation patterns indicated that the cheY suppressors had readjusted the clockwise bias of the fliM strains. However, a chemotaxis assay revealed that the readjustment of the clockwise bias was not sufficient to make cells chemotactic. Although the suppressors did not restore chemotaxis, they did increase swarming on motility plates by a process called "pseudotaxis." Therefore, our genetic selection scheme generated suppressors of pseudotaxis or switch bias adjustment. The binding results suggest that the mechanism for this adjustment is the reduction in binding affinity of activated CheY. Therefore, these suppressors identified the switch-binding surface of CheY by loss-of-function defects rather than gain-of-function compensatory conformational changes.

[Production and secretion of interleukin 6 from stimulated peritoneal macrophages of the mouse]

In this paper, a bioassay method involving the interleukin 6 dependent murine hybridoma B9 cell line was used to detect the level of released and cell-associated interleukin 6 in resident peritoneal macrophages from the mouse. The phorbol ester, phorbol 12-myristate 13-acetate (PMA), the calcium ionophores A23187, the chemotactic peptide fMLP and lipopolysaccharide(LPS) were introduced in these experiments as stimulators. PMA, A23187 and fMLP were shown to induce a dose-dependent increase of both released and cell-associated interleukin 6, whereas, LPS caused increase of interleukin 6 activity in supernatants of cultured peritoneal macrophages of the mouse. The effects of PMA and A23187 suggested that the pathway of PKC and calcium is involved in the production and secretion of interleukin 6. The effects of fMLP and LPS provided evidence that they participated in the process of inflammation. The difference between LPS and the other three stimulators in cell-associated interleukin 6 activity might suggest a different mechanism of actions of generation of interleukin 6.

The impact of the neonatal resuscitation program guidelines (NRPG) on the neonatal mortality in a hospital in Zhuhai, China

AIM

The neonatal resuscitation program (NRPG) was first introduced in our hospital to replace the traditional resuscitation (TR) program in 1993. TR has been in existence in China for a long time. The implementation of NRPG was timely in reducing the number of infant mortality and also to disseminate to the many hospitals in China which are still practising TR.

METHOD

A perspective study of 4,751 newborns with 366 asphyxiated babies in a period of 2 years was carried out. A previous sample of 1,722 live births under the TR program was compared as a controlled group statistically.

RESULTS

From August 1993 to August 1995, when NRPG was exclusively implemented in our hospital, only 16 newborns died within 7 days, out of 4,751 births (3.4%) with 2 deaths in the delivery room. Seventeen newborns died within 7 days out of 1,722 births (9.9+) in the TR group, with 10 deaths in the delivery room. From the data shown, it can be clearly seen that perinatal neonatal mortality rate was reduced almost 3 times after NRPG was implemented (chi(2) = 10.54, p < 0.01). The follow-up results of 21 cases of severe asphyxia at 2 months--1 year of age were normal except for one with cerebral palsy.

CONCLUSIONS

Our study showed that NRPG was indeed a very effective and feasible technique during the delivery process in the reduction of neonatal mortality. It is important to disseminate widely the knowledge and technique of NRPG in places where TR is still being widely practiced especially in developing countries.

[Determination of puerarin in plasma by high performance liquid chromatography]

A high performance liquid chromatography with fluorescence detection has been developed for determination of puerarin in plasma using a column of YWG-C16 (10 microns) and mobile phase of methanol (450 ml)-water (522.5 ml)-0.1 mol.L-1 phosphate buffer (pH 7.4, 27.5 ml). The preparation of samples was as follows: Transfer 0.1 ml of plasma into a 1 ml stoppered glass tube containing daidzein as internal standard, add 0.4 ml of absolute alcohol to deproteinize the plasma, vortex for 2 min, centrifuge for 15 min at 2800 r.min-1 and inject 20 microliters of the supernatant into the HPLC column. Linear calibration curve was obtained by plotting concentration vs peak height ratio over the range 0.03-12.00 micrograms.ml-1 with a correlation coefficient of 0.999. The average recovery of puerarin was 95.3% and the average RSD was 4.8%. The minimum detectable quantity of puerarin was 0.04 ng, equivalent to 10 ng.ml-1 plasma. This method is highly sensitive, specific, simple and rapid. The plasma concentration-time course of puerarin given i.v. 2.25 mg.kg-1 to two dogs determined by this method was found to fit a two-compartments open model with T1/2 alpha of 6.0 min and T1/2 beta of 57.4 min.

Ethnopharmacology of bear gall bladder: I

Both bear and pig bile solutions were shown to have anti-inflammatory, anticonvulsion and analgesic effects, and also to prolong the survival time of mice in hypoxic conditions. It is possible that pig gall bladders could be developed as an alternative to bear gall bladders for uses in certain prescriptions of Chinese medicine.

Antiinflammatory effects of Tremulacin, a Salicin-related substance isolated from Populus tomentosa Carr. leaves

Tremulacin was shown to inhibit carrageenan-induced paw edema in rats and croton oil-induced ear edema in mice. It was also found to inhibit peritoneal leucocyte migration in rats and acetic acid-induced writhing responses in mice. Experiments with isolated longitudinal muscle strips of sensitized guinea pig ileum showed that tremulacin decreased the biosynthesis of Slow Reaction Substance of Anaphylaxis. Tremulacin exerted inhibitory effects on leukotriene B4 biosynthesis in intrapleural leucocytes. These results suggest that the mechanism of antiinflammatory actions of tremulacin is relevant to inhibition of 5-lipoxygenase activity. This is quite different from non-steroid antiinflammatory drugs, such as aspirin, which inhibits prostaglandin synthesis and being a cyclooxygenase inhibitor.

Optical perfect-shuffle network implementation by use of an ordinary imaging system and holographic gratings

We describe an approach to achieve the optical perfect-shuffle interconnection network in an ordinary optical imaging system; a holographic grating is inserted in the proper position, and a corresponding spatial filter is inserted in its back focal plane. This approach is simple, and the space-bandwidth product of the optical system can be better utilized. As an experimental demonstration, the perfectshuffle interconnection network is shown in one and in two dimensions.

[Effect of liuwei dihuang granules, pills and decoction on contents of cAMP, E2, T, Zn and Cu in plasma of renal yin deficient patients]

Experiments showed that in patients of renal yin deficiency who took orally Liuwei Dihuang granules for 4 weeks, the contents of cAMP, E2, Zn and Cu were found mankedly lower, but the contents of T mankedly higher than before using the drugs. This indicates that the granules are equally effective as pills and decoction.

[Determination of glyciphosphoramide and its metabolite in plasma and the pharmacokinetics in rats after oral administration]

Glyciphosphoramide (GPA) is one of the anticancer agents belonging to the group of phosphoramide mustard. It has apparent antitumor effects in some animal models and in clinical trials against breast cancer, lymphosarcoma, uterocervical cancer and cancerous ulcer with good results. In this paper, the determination procedure of GPA and its metabolite using nitrobenzylpyridine (NBP) method is reported. The absorbance of the coloured products from the reaction of hydrolyzed or metabolized GPA with NBP was measured at 570 nm and 564 nm, respectively. The linearity of the reaction for GPA and its metabolite was established over the range of 6.25-100 micrograms/ml water or plasma. The plasma of rats and mice was found to be able to metabolize GPA to form alkylating agent (s) which react with NBP, but that of rabbits cannot. The plasma concentration-time curve of metabolite obtained after oral administration of GPA (100 mg/kg) in rats was shown to fit a two compartment open model with the following parameters: T1/2 beta = 44.5 min, T1/2 alpha = 3.16 min, T1/2 Ka = 2.14 min, T1/2Km = 0.0644 min, Tmax = 7.57 min, Cmax = 55.8 micrograms/ml, AUC = 2827. 39 micrograms/ml.min, K21 = 0.09663/min, K10 = 0.03535/min, K12 = 0.1030/min, Vc = 1.00 L/kg, Vd = 2.07 L/kg, CLt = 2.12 L/h. Kidney was found to be the main organ for GPA metabolite elimination. About one fourth of the given dose was excreted in urine within 24 h with the main portion excreted in the first 2 h.

[Pharmacokinetics of puerarin in rats, rabbits, and dogs]

The puerarin was determined by HPLC with fluorescence detection. The plasma concentration-time course of puerarin in rats and dogs after iv was best fitted to a two-compartment open model, while that in rabbits was best fitted to a three-compartment open model. Species specificity was found among rats, rabbits, and dogs, calculated with compartment model program. The T1/2 beta after iv puerarin 9 mg.kg-1 in rats, rabbits, and dogs were 11, 21, and 67 min, respectively. There were no significant differences in pharmacokinetic parameters after iv 4.5-30 mg.kg-1 to rabbits and dogs.

Avian species-specific tandem repeats contain nuclear protein binding sites

Three avian highly repetitive tandem repeats were identified and examined. These repeats had similar unit lengths (about 42 bp long) but completely different sequences each containing particular protein binding sites. Each of these repeats was found within only one of the five closely related genera studied.

[Expression of human hepatoma associated antigen in relation to the cell cycle]

The expression of human hepatoma associated antigen A25 in relation to the different stages of cell cycle is reported as studied by monoclonal antibody and flow cytometry methods. A25 antigen was found to express all the four human hepatoma cell lines we tested. Hepatoma cell line PUMC-H1 expressed the antigen at higher levels than SMMC-7721 and QGY-7703 whereas BEL-7402 expressed at lower levels. Further studies showed that the cell lines PUMC-H1, SMMC-7721 and QGY-7703 were found to be at the similar stages of cell cycle while QGY-7703 was different from these three cell lines by having more cells in S state but fewer cells in G0-G1 stages. In the same cell line, A25 was expressed during all cell cycle stages though at different levels. It was expressed at the lowest level in G0-G1 stages, a slightly higher level in S stage and the highest in G2-M stage. The results in this paper suggest that the expression of A25 is related to the stage of cell cycle in the same cell line but not related to the stage of cell cycle in different cell lines with similar tissue origin.

Avian tandem repeats: nuclear protein binding sites and the origins of short tandem repetitive DNAS

A 14 bp repeat isolated from the genome of a Mallard duck (Anas platyrhynchos) and a 13 bp repeat isolated from the genome of a Muscovy duck (Cairina moschata) were both tandem and genus-specific. There were 2.1 x 10(6) copies of the 14 bp repeat in the Mallard duck genome and 1.3 x 10(6) copies of the 13 bp repeat in the Muscovy duck genome. These two repeats were not obviously homologous but each contains different transcription protein binding sites. Experimentally, the two repeats were also observed to bind nuclear proteins specifically. A sequence-selective mechanism for the expansion of short tandem repeats from single ancestral sequences containing nuclear protein binding sites is presented.

Cloning, sequence, and expression of a cDNA encoding hamster UDP-GlcNAc:dolichol phosphate N-acetylglucosamine-1-phosphate transferase

UDP-GlcNAc:dolichol phosphate N-acetylglucosamine-1-phosphate transferase (GPT) catalyzes the initial reaction required for synthesis of dolichol-P-P-oligosaccharides. We report here on the sequence and expression of a full-length cDNA clone encoding hamster GPT. The cDNA predicts a protein of 408 amino acid residues including 10 hydrophobic segments. Several portions of the hamster GPT sequence constituting one-third of the protein have 60% or greater identity with yeast GPT, and one-half of the conserved sequence falls within the hydrophobic segments. In addition, hamster GPT has two copies of a putative dolichol recognition sequence recently identified in three yeast enzymes that interact with dolichol. The protein lacks KDEL or DEKKMP-type carboxyl-terminal ER sorting sequences. When expressed in COS-1 cells, the cDNA causes a 5-7-fold increase of GPT activity in membrane fractions. The activity was completely inhibitable by tunicamycin, and the primary product was shown to be GlcNAc-pyrophosphoryldolichol. This cDNA represents the first enzyme of the dolichol-oligosaccharide biosynthetic pathway to be cloned from a vertebrate source and demonstrates structural homology between the enzymes of the yeast and mammalian pathways.

[Immunosuppressive effect of cultured Cordyceps sinensis on cellular immune response]

The immunosuppressive effect of cultured Cordyceps sinensis (Bei Lin Capsule) was studied in vitro and in vivo. When the drug was added from 0.6 mg/ml to 5 mg/ml a significant dose-dependent inhibition effect was shown in the following immune reactions of mice (P less than 0.05-0.01): phagocytic function of peripheral blood leucocytes assayed by chemiluminescence; mitogenic response of spleen lymphocytes to Con A; mixed lymphocyte culture and LPS induced interleukin-1 release of macrophages. The survival rate of mice spleen lymphocytes cultured with Cordyceps sinensis 5 mg/ml in 37 degrees C 5% CO2 for 5 days was more than 80%. Cordyceps sinensis 4 g/kg daily significantly prolonged the mice skin allograft survival time (12.7 +/- 2.2 days v.s. 8.3 +/- 0.7 days in the control, P less than 0.01) and its immunosuppressive effect was close to that of Cyclosporin A 5 mg/kg daily on skin allograft.

[The pharmacological activities of musk. III. On the mechanisms of its anti-inflammatory activities]

The water soluble fraction (WSF) of musk was shown to decrease the vitamin C content of the adrenal gland in mice and to increase plasma corticosterone levels in rats. The anti-inflammatory effect of WSF was not affected by hypophysectomy in the rat but was completely abolished by adrenalectomy in mice, indicating that the adrenal gland may play an important role in mediating the anti-inflammatory effect of musk. The WSF was capable of inhibiting ADP or collagen-induced platelet aggregation in rats. In the meantime, there was a potentiation of immunohemolysis in mice and an elevation of the plasma level of cAMP in rats. The implications of these changes in the anti-inflammatory effects of musk are discussed.

Amplification and molecular cloning of the hamster tunicamycin-sensitive N-acetylglucosamine-1-phosphate transferase gene. The hamster and yeast enzymes share a common peptide sequence

The first step in the assembly of the dolichol-linked oligosaccharides required for asparagine-linked glycosylation in eukaryotes is catalyzed by a tunicamycin-sensitive, dolichol phosphate-dependent N-acetylglucosamine-1-phosphate transferase (GPT). A fragment of the gene encoding the enzyme from Chinese hamster ovary (CHO) cells was partially cloned and characterized by a novel strategy. By stepwise selection, CHO cells were made 80-fold resistant to tunicamycin and found to have 10-fold elevated levels of GPT activity. Using a cloned segment of the yeast ALG-7 gene, which encodes the putative GPT from yeast, an amplified gene was identified by Southern blotting of the CHO DNA and a 6.6-kilobase segment of the gene was molecularly cloned. A family of RNA molecules in the 2.0-2.2-kilobase range identified with a probe from this gene was overexpressed in the resistant cells. The cloned DNA revealed a 24-amino acid residue sequence that was 92% conserved with the corresponding yeast sequence.

Vasovasostomy with use of medical needle as a support

Between May 1981 and December 1985 we performed vasovasostomy using a needle as a support in 43 patients who had undergone vasectomy for family planning. The operation is simple with little surgical trauma and few complications. All 39 patients who underwent semen analysis had return of spermatozoa. Pregnancy resulted in 27 of 34 patients (79.41 per cent) who attempted conception. The results were satisfactory. The procedure is described, and the complication and success rates are analyzed.