Binding of ATP to the fructose-2,6-bisphosphatase domain of chicken liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase leads to activation of its 6-phosphofructo-2-kinase

To understand the mechanism by which the activity of the 6-phosphofructo-2-kinase (6PF-2K) of chicken liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase is stimulated by its substrate ATP, we studied two mutants of the enzyme. Mutation of either Arg-279, the penultimate basic residue within the Walker A nucleotide-binding fold in the bisphosphatase domain, or Arg-359 to Ala eliminated the activation of the chicken 6PF-2K by ATP. Binding analysis by fluorescence spectroscopy using 2'(3')-O-(N-methylanthraniloyl)-ATP revealed that the kinase domains of these two mutants, unlike that of the wild type enzyme, showed no cooperativity in ATP binding and that the mutant enzymes possess only the high affinity ATP binding site, suggesting that the ATP binding site on the bisphosphatase domain represents the low affinity site. This conclusion was supported by the result that the affinity of ATP for the isolated bisphosphatase domain is similar to that for the low affinity site in the wild type enzyme. In addition, we found that the 6PF-2K of a chimeric enzyme, in which the last 25 residues of chicken enzyme were replaced with those of the rat enzyme, could not be activated by ATP, despite the fact that the ATP-binding properties of this chimeric enzyme were not different from those of the wild type chicken enzyme. These results demonstrate that activation of the chicken 6PF-2K by ATP may result from allosteric binding of ATP to the bisphosphatase domain where residues Arg-279 and Arg-359 are critically involved and require specific C-terminal sequences.

The difference in the carboxy-terminal sequence is responsible for the difference in the activity of chicken and rat liver fructose-2,6-bisphosphatase

The fructose-2,6-bisphosphatase domain of the bifunctional chicken liver enzyme 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase shares approximately 95% amino acid sequence homology with that of the rat enzyme. However, these two enzymes are significantly different in their phosphatase activities. In this report, we show that the COOH-terminal 25 amino acids of the two enzymes are responsible for the different enzymatic activities. Although these 25 amino acids are not required for the phosphatase activity, their removal diminishes the differences in the activities between the two enzymes. In addition, two chimeric molecules (one consisting of the catalytic core of the chicken bisphosphatase domain and the rat COOH-terminal 25 amino acids, and the other consisting of most of the intact chicken enzyme and the rat COOH-terminal 25 amino acids) showed the same kinetic properties as the rat enzyme. Furthermore, substitution of the residues Pro456Pro457Ala458 of the chicken enzyme with GluAlaGlu, the corresponding sequence in the rat liver enzyme, yields a chicken enzyme that behaves like the rat enzyme. These results demonstrate that the different bisphosphatase activities of the chicken and rat liver bifunctional enzymes can be attributed to the differences in their COOH-terminal amino acid sequences, particularly the three residues.

Transmission/disequilibrium tests for quantitative traits

The transmission/disequilibrium test (TDT) is a powerful method of locating disease genes. The TDT was originally proposed for use in studies of qualitative traits in families with both parents available. Recently, the TDT has been extended to studies of qualitative traits in sibships without parents available and in families with one parent available. It has also been extended for use in studies of quantitative traits in families with both parents available and in sibships with multiple offspring. In this paper, we first propose a new class of TDT-type tests for linkage in the presence of linkage disequilibrium for use in studies of families with both parents available. The TDT of Spielman et al. (1993) for qualitative traits and the TDT of Rabinowitz (1997) for quantitative traits are special cases of the new tests. Second, we propose a new class of TDT-type tests for linkage for use in studies of families with one parent available. Third, we study the validity and the power of the tests using simulations. Finally, we propose a method of combining data from different types of families. The combined test is valuable and allows researchers full use of the available data in detecting linkage between a marker locus and an unobservable quantitative trait locus. An important feature of the tests proposed in this paper is that no assumptions on the distribution of the quantitative traits are needed.

Nociceptin inhibits electric field stimulation-induced cholinergic constrictions in rat airways

AIM

To study the effect of nociceptin (orphanin FQ), a newly discovered heptadecapeptide, on cholinergic constrictions in isolated trachea and bronchus of rat.

METHODS

The electric field stimulation (EFS) induced a monophasic constriction, which was due to an activation of the cholinergic nerves.

RESULTS

Nociceptin 0.001-0.1 mumol/L inhibited cholinergic constriction in a concentration-dependent manner. IC50 (95% of confidence limits) were 0.06 (0.04-0.08) mumol/L and 0.07 (0.05-0.1) mumol/L in tracheae and bronchi respectively. The constrictions inhibited by nociceptin 0.01 mumol/L in traheae and bronchi were (58 +/- 32)% and (60 +/- 26)% respectively compared with the control, in which nociceptin was not applied. After pretreatment with naloxone 0.1 mumol/L, the constrictions were (60 +/- 19)% and (54 +/- 20)% (P > 0.05 vs the above figures). However, the constrictions induced by exogenous acetylcholine were unaffected by nociceptin 0.01 mumol/L. kappa-Opioid receptor agonist, U-50488H (0.01-1 mumol/L) did not affect the EFS-induced cholinergic constrictions in rat airways.

CONCLUSION

Nociceptin inhibits EFS-induced cholinergic constriction, which is not affected by naloxone in rat airways.

Interaction between the conserved region in the C-terminal domain of GRK2 and rhodopsin is necessary for GRK2 to catalyze receptor phosphorylation

The C-terminal domain of G protein-coupled receptor kinases (GRKs) consists of a conserved region and a variable region, and the variable region has been shown to direct the membrane translocation of cytosolic enzymes. The present work has revealed that the C-terminal domain may also be involved in kinase-receptor interaction that is primarily mediated by the conserved region. Truncation of the C-terminal domain or deletion of the conserved region in this domain of GRK2 resulted in a complete loss of its ability to phosphorylate rhodopsin and in an obvious decrease in its sensitivity to receptor-mediated phosphorylation of a peptide substrate. On the contrary, deletion of the betagamma subunit binding region in the C-terminal domain of GRK2 did not significantly alter the ability of the enzyme to phosphorylate rhodopsin. In addition, the recombinant proteins that represent the C-terminal domain and the conserved region of GRK2 could inhibit GRK2-mediated phosphorylation of rhodopsin and receptor-mediated activation of GRK2 but not GRK2-mediated phosphorylation of the peptide substrate. Furthermore, the conserved region as well as the C-terminal domain could directly bind rhodopsin in vitro. These results indicate that the C-terminal domain, or more precisely, the conserved region of this domain, is important for enzyme-receptor interaction and that this interaction is required for GRK2 to catalyze receptor phosphorylation.

[Transmission and genetic effect of ting chromosome in cross progenies from octoploid Tritileymus with 4D nullisomic]

A pair of ting chromosomes (ti) added to 72180 4D nullisomic was subcentral centromere chromosome and was about 1/3-1/4 the size of a chromosome on the average length. It's chromosome configuration was 19.59" (18-20) + 0.46' (0-4) + 0.99" (0-1) + 0.96ti" (0-1) + 0.08ti' (0-2) at PMC MI. The cells with ring ti" account for 96.19%, of which 82.38% were free on each side of the equatorial plane. ti chromosome paired in advance, defered segregation and had no synapsis with a chromosome. When the cross progenies from 72180 4D nullisomic with octoploid Trilileymus were backcrossed to the 4D nullisomic used as the male, the transmitting rate of 2ti chromosome was six times higher than that where the nullisomic was used as the female. The transmitting and loss rates of ti chromosome were 50.38% and 18.34% respectively, and averagely each plant has 0.72 ti chromosome in the cross generations. The appearing rate of ti chromosome was 43.18% in root tip cell and 8.16% in PMC MI of the plants without ti chromosome. When the number of a chromosome was less than 42, the genetic effect of ti chromosome on the quantitative character was significant, while the number of a chromosome was 42, the genetic effect was not apparent.

Bronchodilating effects of bambuterol on bronchoconstriction in guinea pigs

AIM

To study the effects of bambuterol (Bam) on bronchoconstriction in guinea pigs.

METHODS

Bronchospasm induced by histamine aerosol, lung resistance (RL) and dynamic lung compliance (Cdyn) changes induced by ovalbumin aerosol in vivo, isolated resting lung parenchyma strips, and carbamylcholine-induced tracheal constriction in vitro in guinea pig were investigated.

RESULTS

Bam dose-dependently prolonged the time to histamine-induced collapse, ED50 values (95% confidence limits) of Bam intragastric gavage (i.g.) after 1 h, 4 h, and 24 h were 0.74 (0.60-0.91), 0.75 (0.61-0.91) and 1.00 (0.77-1.30) mg.kg-1, respectively. Bam 2 or 10 mg.kg-1 i.g. 2 h before ovalbumin aerosol partly or almost completely inhibited bronchial challenge of ovalbumin-induced change of RL and Cdyn. Bam 0.1-1.0 mumol.L-1 gave a weak relaxation on isolated tracheal strips induced by carbamylcholine and failed to relax the isolated resting lung parenchyma strips in guinea pig.

CONCLUSION

Bam showed a long-acting bronchodilation by its slow metabolism in vivo.

A preliminary analysis of antineoplastic activity of parvovirus MVMp NS-1 proteins

Human gastric cancer MKN-45 cells were transfected with pULB 3238, a plasmid carrying MVMp NS-1 gene with its original P4 promoter replaced by the glucocorticoid inducible promoter MMTV-LTR. After the integration and expression of NS-1 gene, some of the transfectants died, while others remained alive, but the growth features of survived cells were changed. For further study on the antineoplastic function of parvoviral NS-1 protein in vivo, transgenic mice carrying NS-1 genes were established by conventional method. Among 4 founders, one of them was found to be able to transmit the transgene to around 50% of their offsprings. RT-PCR was performed to indicate the expression of NS-1 gene in transgenic mice and its mRNA appeared in a variety of tissues. The expression of integrated NS-1 gene may correlate with the decreased incidence of tumor induced in vivo by chemical carcinogens.

Low concentration of inducer favors production of active form of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase in Escherichia coli

Expression of chicken and rat liver bifunctional enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase, in Escherichia coli encountered two common problems: the chicken enzyme was liable to proteolysis and the rat enzyme was prone to form inclusion bodies. Reducing the rate of protein synthesis by lowering either growth temperature or isopropyl-beta-D-thiogalactopyranoside (IPTG) concentration alleviated these two problems. Growth at 22 degrees C was optimum for expression of both enzymes. The optimum range of IPTG concentration for expression was 0.1-1 microM for the chicken liver bifunctional enzyme and 10 microM for rat liver enzyme. The components of growth medium also influenced the production. Compared with Luria-Bertani medium, an enriched medium-tryptone-phosphate medium-tripled the production of the active enzymes. Addition of glucose (0.2%) doubled the expression level of active chicken liver enzyme, but reduced the production of active rat liver enzyme to half the maximal level, while the phosphate in tryptone-phosphate medium had no effect on the production of the two enzymes.

Linkage of replication to start by the Cdk inhibitor Sic1

In Saccharomyces cerevisiae, three G1 cyclins (Clns) are important for Start, the event committing cells to division. Sic1, an inhibitor of C1b-Cdc28 kinases, became phosphorylated at Start, and this phosphorylation depended on the activity of Clns. Sic1 was subsequently lost, which depended on the activity of Clns and the ubiquitin-conjugating enzyme Cdc34. Inactivation of Sic1 was the only nonredundant essential function of Clns, because a sic1 deletion rescued the inviability of the cln1 cln2 cln3 triple mutant. In sic1 mutants, DNA replication became uncoupled from budding. Thus, Sic1 may be a substrate of Cln-Cdc28 complexes, and phosphorylation and proteolysis of Sic1 may regulate commitment to replication at Start.

Use of polymerase chain reaction epitope tagging for protein tagging in Saccharomyces cerevisiae

Epitope tagging is the insertion of a short stretch of amino acids constituting an epitope into another protein. Tagged proteins can be identified by Western, immunoprecipitation and immunofluorescence assays using pre-existing antibodies. We have designed vectors containing the URA3 gene flanked by direct repeats of epitope tags. We use the polymerase chain reaction (PCR) to amplify the tag-URA3-tag cassette such that the ends of the PCR fragments possess homology to the gene of interest. In vivo recombination is then used to direct integration of the fragment to the location of interest, and transformants are selected by their Ura+ phenotype. Finally, selection for Ura- cells on 5-fluoro-orotic acid plates yields cells where recombination between the repeated epitopes has 'popped out' the URA3 gene, leaving a single copy of the epitope at the desired location. PCR epitope tagging (PET) provides a rapid and direct technique for tagging that does not require any cloning steps. We have used PET to tag three Saccharomyces cerevisiae proteins, Cln1, Sic1 and Est1.

Inhibitory effect of tetrandrine on C fiber activation-induced contractions in trachea and bronchus of guinea pig

AIM

To study the inhibitory effects of tetrandrine (Tet) on an activation of the sensory nervous C fibers in isolated trachea and bronchus of guinea pig.

METHOD

The electric field stimulation induced a phase II contraction of the preparations, which was due to an activation of the C fifers. The effects of Tet on phase II contraction were analyzed.

RESULTS

Tet 0.3-30 mumol.L(-1) inhibited phase II contractions in a concentration-dependent manner. That phase II contractions inhibited by Tet 1 mumol.L(-1) were 40 +/- 38% and 75 +/- 22% of control in tracheae and bronchi respectively. After pretreatment with chlorphenamine or atropine phase II contraction were still reduced by Tet 1 mumol.L(-1), inhibitory rates being 70 +/- 16% and 64 +/- 16% of control, respectively. The contractile responses of the preparations to exogenous substance P, however, were unaffected by treatment with Tet 1 mumol.L(-1).

CONCLUSION

Tet 1 mumol.L(-1) inhibits phase II contraction, related to the inhibition of local release of neuropeptides from C fibers of guinea pig airway.

Mediator difference in contractions between trachea and bronchus of guinea pig induced by stimulation of C-fibers in vitro

In trachea and bronchus of guinea pig in vitro, electric field stimulation (EFS) induced a rapid contraction (phase I) followed by a long-lasting contraction (phase II). The pretreatments of chlorphenamine (Chl) 1 mumol.L-1 and disodium cromoglycate (Cro) 10 mumol.L-1 reduced the tracheal contraction of phase II from 49 +/- 23 mg and 34 +/- 18 mg to 27 +/- 21 and 18 +/- 12 mg, respectively. The contractile responses of the tracheae to increasing concentrations of substance P (SP) 0.1-3.0 mumol.L-1 were reduced by the pretreatment of Cro 10 mumol.L-1 (P < 0.01). On the contrary, the contractile responses of the bronchi were not inhibited by Cro or Chl but were inhibited by pretreatment of atropine 1 mumol.L-1 from 61 +/- 36 mg to 36 +/- 15 mg. These results show that there are different mechanisms in the EFS-induced contractions between the trachea and bronchus; that different mediators amplify the phase II contractions.

[Acute side effect of postoperative radiotherapy in malignant head and neck neoplasm]

From August 1989 to May 1991,160 patients with malignancies of the head and neck region were treated by surgery and postoperative radiotherapy.Seventy seven patiens underwent resection of the primary lesion combined with neck dissection and 83 patients had resecton of the primary lesion only before radiotherapy.After irradiation 33.8% (54/160) patients developed edema in face and neck,13.1%(21/160) patients developed headache.The style of neck dissection (unilateral,bilateral or no neck dessection) did significantly influence the rates of the acute side effect(P<0.01).The interval between surgery and radiotherapy and radiation dose were not important influential factors(P>0.05).The clinical manifestations,possible mechanism and prevention of the acuter side effect is presented.

Effect of lung inflation on regional lung expansion in supine and prone rabbits

At functional residual capacity, lung expansion is more uniform in the prone position than in the supine position. We examined the effect of positive airway pressure (Paw) on this position-dependent difference in lung expansion. In supine and prone rabbits postmortem, we measured alveolar size through dependent and nondependent pleural windows via videomicroscopy at Paw of 0 (functional residual capacity), 7, and 15 cmH2O. After the chest was opened, alveolar size was measured in the isolated lung at several transpulmonary pressures (Ptp) on lung deflation. Alveolar mean linear intercept (Lm) was measured from the video images taken in situ. This was compared with those measured in the isolated lung to determine Ptp in situ. In the supine position, the vertical Ptp gradient increased from 0.52 cmH2O/cm at 0 cmH2O Paw to 0.90 cmH2O/cm at 15 cmH2O Paw, while the vertical gradient in Lm decreased from 2.17 to 0.80 microns/cm. In the prone position, the vertical Ptp gradient increased from 0.06 cmH2O/cm at 0 cmH2O Paw to 0.35 cmH2O/cm at 15 cmH2O Paw, but there was no change in the vertical Lm gradient. In anesthetized paralyzed rabbits in supine and prone positions, we measured pleural liquid pressure directly at 0, 7, and 15 cmH2O Paw with dependent and nondependent rib capsules. Vertical Ptp gradients measured with rib capsules were similar to those estimated from the alveolar size measurements. Lung inflation during mechanical ventilation may reduce the vertical nonuniformities in lung expansion observed in the supine position, thereby improving gas exchange and the distribution of ventilation.

Effect of positive airway pressure on capillary transit time in rabbit lung

We used fluorescence videomicroscopy to measure the passage of fluorescent dye through the subpleural microcirculation of the lung. With the rabbit in the left lateral decubitus position, the subpleural microcirculation was viewed either through a transparent parietal pleural window located in the superior part of the chest or directly with the chest open. There was no physical contact with the chest or lung. The rabbit was anesthetized, paralyzed, and mechanically ventilated with 100% O2. The dye was injected into the right ventricle during a 2-min apneic period to eliminate lung movement due to ventilation. The video signal of the passage of the dye was analyzed frame by frame by use of digital image processing to compensate for cardiogenic oscillations of the lung surface. Gray scale levels of an arteriole and adjacent venule were measured every 1/30 s. Capillary transit time was determined from the difference between the concentration-weighted mean time values of the arteriolar and venular dye dilution curves. We studied the effect of airway pressure (0-20 cmH2O) on transit time. Cardiac output was measured at different airway pressures by the thermal dilution technique. Capillary transit time averaged 0.60 s at functional residual capacity. Right ventricular-to-arteriolar transit time was four times as large as the capillary transit time. An increase in airway pressure from 0-5 to 20 cmH2O resulted in a fourfold increase in both capillary and arterial transit times and a threefold decrease in cardiac output.

Regional variations in lung expansion in rabbits: prone vs. supine positions

We studied the vertical gradient in lung expansion in rabbits in the prone and supine body positions. Postmortem, we used videomicroscopy to measure the size of surface alveoli through transparent parietal pleural windows at dependent and nondependent sites separated in height by 2-3 cm at functional residual capacity (FRC). We compared the alveolar size measured in situ with that measured in the isolated lungs at different deflationary transpulmonary pressures to obtain transpulmonary pressure (pleural surface pressure) in situ. The vertical gradient in transpulmonary pressure averaged 0.48 +/- 0.16 (SD) cmH2O/cm height (n = 10) in the supine position and 0.022 +/- 0.014 (SD) cmH2O/cm (n = 5) in the prone position. In mechanically ventilated rabbits, we used the rib capsule technique to measure pleural liquid pressure at different heights of the chest in prone and supine positions. At FRC, the vertical gradient in pleural liquid pressure averaged 0.63 cmH2O/cm in the supine position and 0.091 cmH2O/cm in the prone position. The vertical gradients in pleural liquid pressure were all less than the hydrostatic value (1 cmH2O/cm), which indicates that pleural liquid is not generally in hydrostatic equilibrium. Both pleural surface pressure and pleural liquid pressure measurements show a greater vertical gradient in the supine than in the prone position. This suggests a close relationship between pleural surface pressure and pleural liquid pressure. Previous results in the dog and pony showed relatively high vertical gradients in the supine position and relatively small gradients in the prone position. This behavior is similar to the present results in rabbits. Thus the vertical gradient is independent of animal size and might be related to chest shape and weight of heart and abdominal contents.

[Effect of tolmetin on responsiveness of isolated guinea pig tracheal smooth muscles]

Tolmetin directly relaxed the isolated guinea pig tracheal smooth muscles, increased the muscle responsiveness to histamine or carbachol and enhanced the tracheal Schultz-Dale reaction. Prostaglandin E2 synthesized by cyclooxygenase was transformed into prostaglandin B2 (PGB2) with alkali, PGB2 and the lipoxygenase metabolite leukotriene B4 (LTB4) were measured by high-performance liquid chromatography, whereas slow-reacting substance of allergy (SRS-A) was determined by bioassay. Tolmetin showed inhibitory effects on prostaglandin E2 synthesis, with the IC50 being 30 mumol/L, but no effect on LTB4 synthesis (up to 100 mumol/L). SRS-A release was potentiated by tolmetin at 10 and 50 mumol/L. The effects of tolmetin on arachidonic acid metabolism may be responsible for its effects on tracheal smooth muscles. It is suggested that asthma attacks may be induced or enhanced by tolmetin in patients with asthma.

[Epithelioid sarcoma--immunohistochemical and ultrastructural study]

Five cases of epithelioid sarcoma are reported, of which four were studied by immunohistochemistry and one by electron microscopy. Immunohistochemically, the results of cytokeratin showed that these four cases were positive to different degrees by polyclonal cytokeratin and three out of four revealed positive results with low molecular weight cytokeratin monoclonal antibody. Two cases were positive with carcinoembryonic antigen and the other two were negative. The immunohistochemical stain was helpful for differential diagnosis from other sarcomas, such as malignant fibrous histiocytoma and rhabdomyosarcoma. By electron microscopy, tumor cells could be divided into light and dark cells which possessed more or less cell organelles, intermediate microfilaments in the cytoplasm and numerous pinocytic vesicles lying along the cell membrane. The occasional presence of poorly developed desmosomes or the absence of tonofibril bundles and glandular structures can rule out the diagnosis of carcinoma. One of these cases was originally diagnosed as metastatic carcinoma to the skin by light microscopy, which was refuted by electron microscopy, and the keratin positive reaction by immunohistochemistry was helpful for the diagnosis of epithelioid sarcoma. Therefore, the authors suggest that immunohistochemical and electron microscopic studies be used for diagnosing difficult cases of epithelioid sarcoma. From our observation, we consider that the cells of epithelioid sarcoma may derive from undifferentiated mesenchymal cells possessing the potentials of differentiating into synovioblasts, histiocytes or fibroblasts.

Fertility and some determinants of fertility decline in Huaibei Plain, Anhui province, China, 1982

This paper examines the level and trend of fertility in Huaibei Plain, Anhui province, China, since 1950 and considers some determinants of fertility decline. The data used are from the 1/1000 survey of China which was conducted by the Family Planning Commission in 1982.

Fertility decline among younger women (aged under 30) is largely due to later age at marriage, the marriage pattern of Huaibei Plain having changed from early and universal marriage to later and universal marriage. Current use of contraception suggests that the family planning programme, in particular the one-child policy (1979), has been the major determinant in fertility decline. The greatest decline in marital fertility occurred among women aged 35+ and is primarily due to contraceptive practice and induced abortion.