Synthesis and biological activities of angiotensin II, Sarilesin, and Sarmesin analogues containing Aze or Pip at position 7

Analogues of [Sar1]angiotensin II, Sarilesin (type I antagonist), and Sarmesin (type II antagonist) with L-azetidine-2-carboxylic acid (Aze) and L-pipecolic acid (Pip) at position 7 have been prepared by the solid-phase method, purified by reverse-phase HPLC, and bioassayed in the rat uterus. Analogues of the superagonist [Sar1]ANGII with Aze or Pip at position 7 and sarcosine (Sar) or aminoisobutyric acid (Aib) at position 1 had high intrinsic activity in the rat isolated uterus assay (34-184%). Analogues of Sarilesin ([Sar1,Ile8]ANGII) with Aze or Pip at position 7 and Sar or Aib at position 1 retained high antagonist activity (pA2 = 7.1-8.3). Analogues of Sarmesin ([Sar1,Tyr-(OMe)4]ANGII) with Aze and Pip at position 7 had pA2 values of 7.4 and 6.5, respectively. [Aze7]-ANGII and [Pip7]ANGII had low activities (12% and 1%, respectively), and deletion of Sar at position 1 of Sarmesin analogues abolished binding (or affinity) as judged from pA2 values. Nuclear Overhauser effect (NOE) spectroscopy studies of [Sar1,Aze7]ANGII in DMSO-d6 have indicated a clustering of the three aromatic rings (Tyr, His, Phe) and proximity of Sar C alpha and Arg C delta protons to the Tyr/Phe ring protons. These data emphasize that replacement of Pro with the lower and higher homologs Aze and Pip does not greatly alter the structural requirements necessary for expression of agonist or antagonist activity, when sarcosine occupies position 1, but not when Asp occupies position 1, suggesting that there is an intimate relationship between the N-terminal and penultimate residues of the molecule in the biologically active conformation of the molecule.

Effects of rhynchophylline on motor activity of mice and serotonin and dopamine in rat brain

Rhynchophylline (Rhy) reduced the spontaneous motor activity and enhanced the sedative and hypnotic effects of sodium pentobarbital in mice. The effects of Rhy on serotonin (5-HT) and dopamine (DA) concentrations in rat brain, and the release of 5-HT and DA from the regional brain slices were studied by a fluorescence detector. Rhy increased the 5-HT content in the hypothalamus and cortex, but reduced the DA concentrations in the cortex, amygdala, and spinal cord. Rhy promoted the release of endogenous DA from 4 brain regions. The release of 5-HT was increased in 2 brain regions and decreased in hypothalamus slice. However, Rhy inhibited the release of both 5-HT and DA evoked by high potassium.

Structure-function relationships of the thrombin-thrombomodulin interaction

Thrombomodulin is an anticoagulant protein cofactor that modulates the substrate specificity of thrombin and promotes the cleavage of protein C. The structure-function relationships of the thrombin-thrombomodulin interaction have been explored by recombinant DNA and protein chemistry methods. Thrombomodulin binds to thrombin at an anion-binding exosite on the carboxyl-terminal side of the substrate binding cleft. This interaction interferes with the recognition and cleavage of fibrinogen, factor V, and the platelet thrombin receptor. Binding to thrombomodulin also protects thrombin from inhibition by heparin cofactor II. The major thrombin binding site on thrombomodulin consists of EGF-like domains 5 and 6. In addition, EGF-like domain 4 is required for thrombomodulin to accelerate the activation of protein C. Some thrombomodulin molecules contain a chondroitin sulfate moiety attached to a Ser/Thr-rich domain adjacent to the cell membrane. This modification is not required for the cofactor activity of thrombomodulin, but appears to contribute to 'direct anticoagulant' activity--the ability of thrombomodulin to inhibit fibrinogen clotting, factor V activation, and platelet activation. The chondroitin sulfate moiety of thrombomodulin also can affect the rate of thrombin inhibition by antithrombin III, possibly by competing with heparin for the heparin binding site on thrombin. Detailed understanding of these interactions could lead to new strategies for the treatment of bleeding or thrombotic disorders.

Mutagenesis of thrombin selectively modulates inhibition by serpins heparin cofactor II and antithrombin III. Interaction with the anion-binding exosite determines heparin cofactor II specificity

Thrombin is a multifunctional serine protease that plays a critical role in hemostasis. Thrombin is inhibited by the serpins antithrombin III and heparin cofactor II in a reaction that is dramatically accelerated by glycosaminoglycans. The structural basis of the interaction with these inhibitors was investigated by introducing single amino acid substitutions into the anion-binding exosite (R68E, R70E) and unique insertion loops (K52E, K154A) of thrombin. The rate of inhibition of these recombinant thrombins by antithrombin III and heparin cofactor II was determined in the absence and presence of glycosaminoglycan. The second order rate constant (k2) for inhibition by antithrombin III without heparin was 3.7 x 10(5) M-1 min-1 for wild-type thrombin; rates for the mutant thrombins varied less than 2-fold. For inhibition by antithrombin III with heparin, the rate constant was 4.5 x 10(8) M-1 min-1 for wild-type thrombin with no significant differences between any of the recombinant thrombins. In contrast, the rate constant for inhibition by heparin cofactor II without glycosaminoglycan was 4.3 x 10(4) M-1 min-1 for wild-type thrombin; rates were 10-fold slower for thrombin K52E and 2- to 3-fold slower for thrombins R68E and R70E. The rate constants for inhibition of wild-type thrombin by HCII in the presence of heparin or dermatan sulfate were 9.2 x 10(8) M-1 min-1 and 9.0 x 10(8) M-1 min-1, respectively. Compared to wild-type thrombin, the rate of inhibition by HCII with glycosaminoglycan was 5- to 15-fold slower for thrombins K52E and R70E and 50- to over 100-fold slower for thrombin R68E. Thrombin K154A was inhibited by heparin cofactor II with rates similar to wild-type thrombin in all assays. These results suggest that heparin cofactor II interacts with residue Lys-52 in the proposed S1' subsite and with residues Arg-68 and Arg-70 in the anion-binding exosite of thrombin, and that these interactions contribute to the molecular basis of heparin cofactor II specificity for thrombin.

Localization of the single-stranded DNA binding site in the thrombin anion-binding exosite

Single-stranded DNA molecules containing a 15-nucleotide consensus sequence have been reported to inhibit thrombin activity. The mechanism of the inhibition was studied using a consensus 15-mer oligonucleotide and two recombinant mutant thrombins: the anion-binding exosite mutant thrombin R70E, and thrombin K154A, in which the mutation was located in a surface loop outside of the exosite. The consensus 15-mer oligonucleotide inhibited both fibrinogen-clotting and platelet-activation activities of plasma-derived thrombin, recombinant wild type thrombin, and mutant thrombin K154A in a sequence-specific and dose-dependent manner, whereas it did not inhibit either activity of mutant thrombin R70E. The 15-mer oligonucleotide also inhibited thrombomodulin-dependent protein C activation by plasma-derived thrombin. In competition equilibrium binding experiments, binding of 125I-labeled diisopropyl phosphoryl-thrombin to thrombomodulin was completely inhibited by the consensus 15-mer oligonucleotide with a Kd value of 2.68 +/- 0.16 nM. These results suggest that Arg-70 in the anion-binding exosite of thrombin is a key determinant for interaction with specific single-stranded DNA molecules, and that binding of single-stranded DNA molecules to the exosite prevents the interaction of thrombin with fibrinogen, the platelet thrombin receptor, and thrombomodulin.

Effects of ligands on reduction of oxygen by vanadium(IV) and vanadium(III)

V(IV) and V(III) reduce molecular oxygen with increasing rates as the pH is raised from 6.0 to 7.4. Under all conditions tested, V(IV) is the more efficient reductant. EDTA and ATP generally inhibit the reduction of oxygen by V(III) and V(IV). In contrast, desferrioxamine accelerates the reduction of oxygen by V(IV) but with decreasing effectiveness at pH 7.4 compared to pH 6.0, while desferrioxamine accelerates the reduction of oxygen by V(III) only at pH 6.0. Histidine enhances the reduction of oxygen by V(IV) at pH 7.0 and 7.4. The observed rates of oxygen reduction by V(III) and V(IV) imply that the intracellular distribution of vanadium among its redox states reflects not an equilibrium but a steady state.

Physiologic comparison and validation of Stairobic stepping with bench stepping

To compare the oxygen cost of submaximal exercise on the Stairobic stepping (SS) machine with bench stepping (BS), 12 healthy men and women (mean age 23 years) underwent six different five minute exercise bouts that were randomly assigned. Tests were conducted using standard open circuit calorimetry. SS at 40 and 60 st/min was equal to BS at 20 st/min and SS at 80 st/min was equal to BS at 30 st/min for VE and RER. VO2 was equal at 20 st/min (BS) and 60 st/min (SS), and 30 st/min (BS) and 80 st/min (SS). Stairobic MET (SM) displayed values over-estimated actual MET (AM) values at the two lowest SS rates and under-estimated the AM value at the highest SS rate. Forty-eight observations of the MET response of SS were conducted and analyzed (BMDP2R) in a forward stepping solution. The multiple regression equation calculated for AM was: AM = -0.567 + -0.012 (WT) + 0.063 (rate) + 0.612 (SM) with an adjusted R2 of 0.82 and a SEE of 0.90. The physiologic cost of BS was approximately equal to SS at two to three times the BS rate of stepping.

Genomic sequence and chromosomal location of human interleukin-11 gene (IL11)

The genomic sequence of human interleukin-11 (IL11) has been isolated based on its sequence homology with a cDNA clone encoding primate IL11. The human IL11 genomic sequence is 7 kb in length and consists of five exons and four introns. The IL11 gene has been localized to the long arm of human chromosome 19 at band 19q13.3-q13.4 by in situ hybridization. Several potential transcriptional control sequences that may play an important role in the control of IL11 gene expression have been identified within the 5'-flanking region of the human IL11 gene. The 5'-flanking region of the human IL11 gene contains sequences similar to those present in the 5'-regulatory regions of other cytokine genes. Four repeats of a 30-bp DNA segment were found in the fourth intron, and several copies of ATTTA and Alu repetitive sequences were identified in the 3'-noncoding region of the human IL11 gene. A DNA sequence (ACATGGCAAAACCC) that has 71% similarity with the IL1-responsive element of the IL6 gene was found in the 3'-flanking region of the human IL11 gene. The two polyadenylation sites located at nucleotide positions 6762 and 5591 correspond to the 2.5- and 1.5-kb IL11 transcripts expressed in IL1-induced PU-34 cells. The availability of the human IL11 genomic sequence should aid in studies of the regulatory mechanisms of IL11 gene expression in different cell types and the role of IL11 expression in the hematopoietic microenvironment.

[Investigation of microbicidal activity of neutrophil defensins against leptospires]

Defensins play an important role in oxygen-independent microbicidal mechanisms of neutrophils. They are effective against many bacteria, fungi and enveloped viruses. However, the effect of defensins upon leptospires has not been studied. In the present report, human defensins (i.e. HNP, a mixture of HNP1, HNP2 and HNP3 were prepared from human polymorphonuclear neutrophils by chromatography on Sephadex G-100 and then on Biogel P-10. Rabbit defensin NP1 was purified from rabbit peritoneal granulocytes by preparative acid urea polyacrylamide gel electrophoresis. By using the most-probable-number procedure, HNP and NP1 were tested in vitro for the killing of leptospira interrogans serogroup icteroheamorrhagiae serovar lai strain 017. NP1 was highly effective. When leptospires of strain 017 were incubated with 1 microgram/ml of NP1 at 30 degrees C for 4 hours, > 99% of these organisms were killed. HNP was less potent than NP1, and at 50 micrograms/ml, it killed > 90% of leptospires. As is also the case for the killing of bacteria, NP1 was active against leptospires in nutrient-free buffer, whereas HNP required the addition of glucose. The data suggest that defensins could play a major role in the killing of leptospires by neutrophils.

Ligand specificity of human thrombomodulin. Equilibrium binding of human thrombin, meizothrombin, and factor Xa to recombinant thrombomodulin

Thrombomodulin is an endothelial glycoprotein that serves as a cofactor for protein C activation. To examine the ligand specificity of human thrombomodulin, we performed equilibrium binding assays with human thrombin, thrombin S205A (wherein the active site serine is replaced by alanine), meizothrombin S205A, and human factor Xa. In competition binding assays with CV-1(18A) cells expressing cell surface recombinant human thrombomodulin, recombinant wild type thrombin and thrombin S205A inhibited 125I-diisopropyl fluorophosphate-thrombin binding with similar affinity (Kd = 6.4 +/- 0.5 and 5.3 +/- 0.3 nM, respectively). However, no binding inhibition was detected for meizothrombin S205A or human factor Xa (Kd greater than 500 nM). In direct binding assays, 125I-labeled plasma thrombin and thrombin S205A bound to thrombomodulin with Kd values of 4.0 +/- 1.9 and 6.9 +/- 1.2 nM, respectively. 125I-Labeled meizothrombin S205A and human factor Xa did not bind to thrombomodulin (Kd greater than 500 nM). We also compared the ability of thrombin and factor Xa to activate human recombinant protein C. The activation of recombinant protein C by thrombin was greatly enhanced in the presence of thrombomodulin, whereas no significant activation by factor Xa was detected with or without thrombomodulin. Similar results were obtained with thrombin and factor Xa when human umbilical vein endothelial cells were used as the source of thrombomodulin. These results suggest that human meizothrombin and factor Xa are unlikely to be important thrombomodulin-dependent protein C activators and that thrombin is the physiological ligand for human endothelial cell thrombomodulin.

[Effects of rhynchophylline and isorhynchophylline on blood pressure and blood flow of organs in anesthetized dogs]

In anesthetized thoracotomized dogs, rhynchophylline (Rhy 5 mg.kg-1, iv) reduced the mean arterial pressure (MAP), heart rate (HR), and coronary blood flow (CBF) by 1.16 +/- s 0.67 kPa, 19 +/- 12 beats/min, and 0.12 +/- 0.04 ml.min-1.g-1, whereas isorhynchophylline (Isorhy 1 mg.kg-1, iv) reduced the parameters by 3.58 +/- 0.19 kPa, 26 +/- 18 beats/min, and 0.10 +/- 0.04 ml.min-1.g-1, respectively. In unthoracotomized dogs, Rhy (10 mg.kg-1, iv) decreased renal blood flow (RBF) by 0.35 +/- 0.16 ml.min-1.g-1, but did not change the MAP. Isorhy (5 mg.kg-1, iv) reduced the MAP by 3.44 +/- 1.44 kPa, but the RBF remained unaffected. These results indicated that the hypotensive effect of Isorhy in a dosage not affecting RBF was more potent than that of Rhy.

Desferrioxamine enhances the reactivity of vanadium (IV) and vanadium (V) toward ferri- and ferrocytochrome c

Ligands, especially desferrioxamine, affect the rate at which vanadium reduces or oxidizes cytochrome c. Whether reduction or oxidation occurs, and how fast, depends on the nature of the ligand, the state of reduction of the vanadium, the pH (6.0, 7.0, or 7.4), and the availability of oxygen. In general, oxidation of ferrocytochrome c was favored by (1) low pH, (2) an oxidized state of the vanadium, (3) the presence of oxygen, and (4) more strongly binding ligands (desferrioxamine much greater than histidine = ATP greater than EDTA greater than albumin greater than aquo). Thus, at pH 6.0, desferrioxamine accelerated the V(V)-catalyzed ferrocytochrome c oxidation 160-fold aerobically, and 3500-fold anaerobically. In general, strongly binding ligands slowed oxidations, especially at higher pH. Desferrioxamine was unique among the five ligands in that it not only accelerated oxidation of ferrocytochrome c at pH 6.0, but at pH 7.4 the redox balance shifted to the point where it paradoxically reduced ferricytochrome c. V(V) is an improbable electron donor, but desferrioxamine will reduce cytochrome c, and V(V) accelerates this process. Oxidation of cytochrome c by V(V):desferrioxamine was faster anaerobically, and reduction by V(IV):desferrioxamine was faster aerobically. Although V(V) did not oxidize ferrocytochrome c at pH 7.4, V(IV) did, provided oxygen and desferrioxamine were both present. V(IV):desferrioxamine almost completely reduced ferricytochrome c, and this reduction was followed by a slow, progressive oxidation. This latter oxidation of cytochrome c is mediated by active species generated in the reaction between V(IV):desferrioxamine and oxygen, because none of these reagents alone can induce oxidation at a comparable rate. The mediating species were transient, and generated in reactions with oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)

Does the difference of the properties of trisaccharide-BSA conjugate (NT-P-BSA) of Mycobacterium leprae phenolic glycolipid influence on its seroreactivity?

The sugar content of the trisaccharide-BSA conjugate of the phenolic glycolip I of Mycobacterium leprae (NT-P-BSA) increased with the increase of the molar ratio of the trisaccharide to BSA used in the coupling reaction. The difference of the sugar content in NT-P-BSA did not give the influence on the seroreactivity and specificity in ELISA for both IgM and IgG class antibodies. During the course of the coupling reaction, about half amount of BSA was converted to dimeric form. However, there were no differences of the activity and specificity between monomeric form and dimeric form of NT-P-BSA. Based on these results, it was concluded that any lot of NT-P-BSA with variety of sugar content can be used in ELISA without any difference of the seroreactivity.

Common intragenic and extragenic polymorphisms of blood coagulation factors VIII and IX are different in Chinese and Caucasian populations

In order to examine the possibilities of carrier detection and prenatal diagnosis in hemophilia A and B in the Chinese region of Suzhou, we analyzed four different RFLPs within the factor IX gene and two intragenic RFLPs and one extragenic RFLP for the factor VIII gene. The results obtained show important differences between the Chinese and Caucasian populations. No polymorphism was found within the factor IX gene in the Chinese population and the informativity obtained for the factor VIII gene was quite different between the two populations for each RFLP studied.

BP-1/6C3 expression defines a differentiation stage of transformed pre-B cells and is not related to malignant potential

BP-1 antibody recognizes a cell surface molecule related to the zinc-dependent metallopeptidases that is expressed during a narrow window early in B cell differentiation. Expression of the same molecule, as originally recognized by the mAb 6C3, is widely accepted to be associated with the complete malignant transformation of pre-B lymphoid cells. We have examined BP-1/6C3 expression in a panel of established Abelson virus-transformed cells that includes both cells analogous to pre-B cells and to less differentiated B lineage cells that have not yet completed Ig H chain gene rearrangement. This analysis reveals that many of the less differentiated transformants do not express BP-1/6C3 for an extended culture period. In contrast, virtually all transformants that are analogous to normal pre-B cells express the determinant early in their culture history. The BP-1/6C3 negative transformants are fully tumorigenic in syngeneic mice, demonstrating that BP-1/6C3 expression is not required for complete malignant transformation. Our data thus suggest that the pattern of BP-1/6C3 expression in Abelson virus-transformed cells mimics that observed in normal cells and is indicative of a differentiation event unrelated to the malignant potential of the cells.

[Effect of blood-activating and stasis-removing drugs on hypercoagulability data in nephrotic syndrome]

Platelet aggregation test (PAgT), plasma factor VIII related antigen (VIII R:Ag) and kaolin partial thromboplastic time (KPTT) in 32 nephrotic children were determined.

RESULTS

(1) PAgT induced by ADP and adrenaline which included 1 minute and 5 minute aggregation rate in the patients (30. 78 +/- 7.44%, 72.56 +/- 18.09%, 22.16 +/- 9.24%, 67.53 +/- 22.32%) was significantly increased (P less than 0.02-0.001) as compared with the normal control group (30.65 +/- 8.38%, 57.98 +/- 13.60%, 18.14 +/- 7.33%, 55.92 +/- 16.10%) except 1 minute aggregation rate induced by ADP (P greater than 0.05). (2) VIII R:Ag and KPTT in patients (226.97 +/- 50.47%, 32.04 +/- 5.88 sec) were obviously different (P less than 0.001, P less than 0.02) from the normal control group (107.11 +/- 24.55%, 35.42 +/- 5.00 sec). The results suggested that PAgT, VIII R:Ag and KPTT could be used as laboratory data reflecting the hypercoagulable state in nephrotic children. According to their age, sex and the clinical types of nephrotic syndrome, 24 nephrotic children with abnormality of PAgT, VIII R:Ag and KPTT were random divided into group 1 given prednisone only and group 2 given prednisone, blood-activating and stasis-removing drugs.

RESULTS

the difference of PAgT, VIII R:Ag and KPTT in two groups between pre- and post-treatment was significant statistically (P less than 0.05-P less than 0.001). The decline in PAgT and VIII R:Ag was faster in group 2 than in group 1 (P less than 0.05-P less than 0.01). The results showed that blood-activating and stasis-removing drugs were likely to improve abnormal PAgT and VIII R:Ag in nephrotic children.