Charge state specific facile gas-phase cleavage of Asp 75-Met 76 peptide bond in the alpha-chain of human apohemoglobin probed by electrospray ionization mass spectrometry

Herein, we present the first example of charge state specific facile gas-phase cleavage of an aspartic acid-methionine peptide linkage. This cleavage (Asp 75-Met 76) was observed in the alpha-chain of human adult hemoglobin (Hb) and was probed by electrospray ionization mass spectrometry. This specific conformational and/or charge density dependent dissociation was observed primarily in the [M + 11H]11+ and [M + 12H]12+ species. A mechanism involving an intramolecular proton transfer from the protonated carboxyl side chain of Asp 75 to the neighboring Met 76 residue yielding an anhydride moiety at the C-terminal of the Asp 75 is proposed. Dramatic differences in dissociation of [M + 13H]13+ and [M + 14H]14+ species were observed.

Antiproliferative properties of polyamine analogues: a structure-activity study

A basis set of polyamine analogues was designed and synthesized. These compounds were used to initiate a systematic investigation of the role of chain length, terminal nitrogen alkyl group size, and symmetry of the methylene backbone in the antineoplastic properties of polyamine analogues. New synthetic methods predicated on our earlier polyamine fragment synthesis are described for accessing the tetraamines of interest. An unsymmetrically substituted diamine reagent, N-(tert-butoxycarbonyl)-N,N'-bis(mesitylenesulfonyl)-1,4-diaminobu tane, was developed for entry into unsymmetrical tetraamines. All of the tetraamines synthesized were first evaluated in a murine leukemia L1210 cell IC50 assay at 48 and 96 h. In an attempt to correlate this behavior with some aspect of polyamine metabolism, each compound was tested for its ability to compete with spermidine for the polyamine uptake apparatus, its impact on the polyamine biosynthetic enzymes ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (AdoMetDC), and its effect on the polyamine-catabolizing enzyme spermidine/spermine N1-acetyltransferase (SSAT) and on polyamine pools. While there was no obvious correlation between the 48 and 96 h IC50's and the impact of the analogues on polyamine metabolism, there were other structure-activity relationships. Correlations were observed to exist between chain length and IC50's and between terminal alkyl substituents and impact on Ki, ODC, and AdoMetDC. Also, preliminary studies suggest a relationship may exist between the 48 and 96 h IC50 activities and the analogue's chronic toxicity in vivo. Finally, when the overall length of the polyamine backbone was held constant, the symmetry of the methylene chains of the polyamine fragments was shown to be unimportant to the compound's activity.

[Evaluation of two glycolipids from M. tuberculosis in the serodiagnosis of tuberculosis]

Sera from 112 healthy controls and 120 pulmonary tuberculous patients (61 untreated patients and 59 active patients) were assayed, by ELISA, to test the activity of IgG and IgM antibodies against antigen of 2, 3-diacyl-trehalose-2'-sulphate (SL IV) a phenolglycolipid antigen (PGLTb1) and purified protein derivative (PPD) from M. tuberculosis. Respectively, for SL IV-IgG-ELISA, SL IV-IgM-ELISA, PGLTb1-IgG-ELISA, PGLTb1-IgM-ELISA, PPD-IgG-ELISA, the specificities were of 96.43, 96.43, 96.43, 96.43 and 95.53%; the sensitivities were of 51.67, 32.50, 14.17, 18.33 and 33.33%; the efficiencies were of 73.28, 63.36, 53.88, 56.03 and 62.93%; the predictive values for a positive result were of 96.87, 86.67, 80.95, 84.62 and 88.64%. Among the three antigens tested, SL IV was found to be better than PGLTb1 and PPD.

Cardiorespiratory responses to low-intensity heart rate-controlled exercise in female subjects

This study compares selected cardiorespiratory responses of six healthy females during exercise on rowing (R), cycle (C) and arm (A) ergometers. Their mean +/- sd age, mass and height were 22.3 +/- 3.0 years, 55.3 +/- 6.3 kg and 161.5 +/- 7.4 cm, respectively. Subjects reported to the laboratory on three separate days without engaging in intense physical activity the day prior to testing. Subjects sat quietly for five minutes on an ergometer prior to a 15 minute, steady-state exercise bout. Target heart rate during the exercise period was set at 115 bpm, and was monitored continually with workload adjustments applied to the ergometers to ensure that the target rate was maintained. CO2 rebreathing using the Sensormedics Horizon MMC was performed twice at steady-state exercise and averaged to examine changes in Q and SV. A one-way repeated measures ANOVA revealed that at similar levels of heart rate (R = 114.0 +/- 2.8; C = 116.0 +/- 2.8; A = 114.8 +/- 6.9 bpm) there were significantly lower Q and SV during arm ergometry (8.43 +/- 0.93 l/min and 72.61 +/- 7.82 ml) than rowing (13.01 +/- 1.61 l/min and 111.57 +/- 13.52 ml) and cycle (11.10 +/- 2.19 l/min and 88.23 +/- 21.94 ml) ergometry, and there were no significant differences in Q and SV between rowing and cycling. These results suggest that arm work during low intensity steady-state aerobic exercise is associated with a reduced stroke volume which is probably related to a reduced venous return during arm work in comparison to other types of exercise.

Protein kinase C activation inhibits cytokine-induced nitric oxide synthesis in vascular smooth muscle cells

Vascular smooth muscle cells (SMC) respond by relaxation to nitric oxide (NO) released from the endothelium which expresses a constitutive, Ca(2+)-dependent NO synthase (cNOS). SMC can, however, produce NO themselves upon stimulation by proinflammatory cytokines which induce expression of an inducible, Ca(2+)-independent NO synthase (iNOS). Protein kinase C represents another important second messenger system involved in the regulation of SMC contraction. We have investigated iNOS expression and NO synthesis in rat vascular SMC treated with the cytokines, IFN gamma and TNF alpha, in the presence or absence of the activator of protein kinase C, beta-phorbol-12-myristate 13-acetate (PMA). Treatment with PMA did not induce any significant accumulation of nitrite, a major stable metabolite of NO, in SMC. When added simultaneously with the cytokines, PMA significantly reduced nitrite accumulation induced by cytokine stimulation in a dose-dependent fashion. This inhibitory effect was mediated by activation of PKC since calphostin C, a specific PKC inhibitor, abolished the PMA effect. Further analysis of iNOS mRNA with a rat iNOS cDNA probe demonstrated that addition of PMA reduced expression of SMC iNOS mRNA, indicating that the antagonism in induction of NO synthesis between PMA and the proinflammatory cytokines acts on the transcriptional level. The inhibitory effect of PMA may be mediated via induction of a suppressor of iNOS expression, since pretreatment with PMA reduced NO production after subsequent treatment with cytokines. These observations suggest that activation of the PKC pathway is involved in a negative regulation of iNOS gene expression and this is compatible with the observation that vascular SMC contraction can be induced by PKC activation.

Enterokinase, the initiator of intestinal digestion, is a mosaic protease composed of a distinctive assortment of domains

Enterokinase is a protease of the intestinal brush border that specifically cleaves the acidic propeptide from trypsinogen to yield active trypsin. This cleavage initiates a cascade of proteolytic reactions leading to the activation of many pancreatic zymogens. The full-length cDNA sequence for bovine enterokinase and partial cDNA sequence for human enterokinase were determined. The deduced amino acid sequences indicate that active two-chain enterokinase is derived from a single-chain precursor. Membrane association may be mediated by a potential signal-anchor sequence near the amino terminus. The amino terminus of bovine enterokinase also meets the known sequence requirements for protein N-myristoylation. The amino-terminal heavy chain contains domains that are homologous to segments of the low density lipoprotein receptor, complement components C1r and C1s, the macrophage scavenger receptor, and a recently described motif shared by the metalloprotease meprin and the Xenopus A5 neuronal recognition protein. The carboxyl-terminal light chain is homologous to the trypsin-like serine proteases. Thus, enterokinase is a mosaic protein with a complex evolutionary history. The amino acid sequence surrounding the amino terminus of the enterokinase light chain is ITPK-IVGG (human) or VSPK-IVGG (bovine), suggesting that single-chain enterokinase is activated by an unidentified trypsin-like protease that cleaves the indicated Lys-Ile bond. Therefore, enterokinase may not be the "first" enzyme of the intestinal digestive hydrolase cascade. The specificity of enterokinase for the DDDDK-I sequence of trypsinogen may be explained by complementary basic-amino acid residues clustered in potential S2-S5 subsites.

Comparison of standard locked-ward treatment versus open-ward rehabilitation treatment for chronic schizophrenic patients. A one-year controlled trial in Canton

A priority for psychiatric rehabilitation workers in China is to develop less-restrictive methods for managing the estimated 2500 chronically institutionalised patients who are symptomatically stable and have adequate psychosocial functioning but have no family members who are able or willing to take them home. We transferred 45 chronic schizophrenic male in-patients to an open-door rehabilitation ward where they were given as much freedom as possible and encouraged to take part in occupational, social, and recreational activities. The Nurses Observation Scale for Inpatient Evaluation (NOSIE) was used to compare the psychosocial functioning of the 43 patients who completed the year-long trial with that of 43 similar patients who received standard in-patient treatment on a locked ward. Over the year, the experimental group showed a significant improvement in overall functioning, whereas the control group showed no improvement. These findings suggest that open-door rehabilitation wards situated within the hospital can mobilise latent psychosocial functioning and may be a good method for re-introducing chronic schizophrenic patients in China back into the community.

Cellular regulation of nitrate uptake in denitrifying Flexibacter canadensis

Nitrate uptake and its regulation were investigated using an ion-specific nitrate electrode for denitrifying Flexibacter canadensis under anaerobic conditions. Glucose supported a greater rate of nitrate uptake than did glycerol, glutamate, lactose, cellobiose, or ethanol. Nitrate uptake closely approximated Michaelis--Menten kinetics; the estimated Ks(glucose) and apparent Km(nitrate) for nitrate uptake were 21 and 44 microM, respectively. Nitrate disappearance was correlated with nitrite accumulation, and nitrate had an inhibitory effect on nitrite reduction. Oxygen inhibition of nitrate uptake increased as the percent air saturation increased, and reversed readily as the percent air saturation decreased. The minimal air saturation showing inhibition of nitrate uptake was about 2-4%. Azide and cyanide completely inhibited nitrate uptake. No nitrate uptake was observed in cells grown in the presence of 1 or 5 mM tungstate (no added molybdate). When molybdate (100-200 microM) was present in the medium, nitrate uptake was exhibited by organisms grown with 1 mM, but not with 5 mM, tungstate, indicating that nitrate uptake was dependent on the presence of an active nitrate reductase, and that competition between tungsten and molybdenum occurred during the formation of nitrate reductase. Nitrite production from nitrate by whole cells but not cell-free extracts was inhibited by 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone, indicating that nitrate and (or) nitrite transport depended upon the electrochemical proton gradient.

[Study on antibacterial protein from human urinary bladder mucosa]

Acid-soluble extract of human bladder mucosal surface was obtained by washing out the bladder of accidentally dead male human with 1% acetic acid in the presence of proteinase inhibitors. Acid urea polyacrylamide gel electrophoresis (AU-PAGE) indicated that the acid-soluble extract had more than 10 main protein bands, but the currently known antibiotic peptides, e. g., Lysozyme and defensins, were not found in this extract. The quantitation assay of lysozyme showed that lysozyme only amounted to 2.2 microgram per milligram protein. When tested for antibacterial activity by using ultrasensitive radial diffusion assay, the acid-soluble extract effectively killed E. coli ML-35P. The antibacterial activity of the acid-soluble extract was further analysed by gel overlay technique and the result showed that one main protein band, which was referred to as human bladder protein (HBP), was potently antibacterial against E. coli ML-35P. The HBP accounted for 4% of the total acid-soluble extract protein. These results suggest that the presence of antibacterial protein in the bladder mucosa may be the molecular base of the bladder antibacterial defence mechanisms.

Among a range of transition metals and ligands vanadium.desferroxamine excels in accelerating reactivity of ferrocytochrome c toward molecular oxygen

Despite early knowledge of the requirement for metals in the reactions of ferrocytochrome c with oxygen, the relative effectiveness of metals and the factors that modulate effectiveness remain unknown. We have compared the catalytic power of five metals and report the effects of pH and ligand on their effectiveness as catalysts. Catalysis by metal ions was greatest at higher pH, where the rate of aerobic oxidation was lowest. Iron (Fe2+), copper (Cu2+), vanadium(V) (V(V)), manganese (Mn2+), and aluminum (Al3+) were tested in combination with EDTA, ADP, histidine, or desferrioxamine (Des) at pH 2.6, 3.2, and 4.0. At pH 2.6, only vanadium(V) increased the initial rate of the oxidation of ferrocytochrome c (by 6.2-fold). At pH 4.0, however, all the metals markedly stimulated the oxidation of cytochrome c. The order of effectiveness was V(V).Des >> Cu.ADP2+ > Fe.EDTA2+ > Mn.Des2+ > Al.EDTA3+ (where the stated ligand represents the most stimulating one for a given metal). At pH 3.2 the metal complexes had intermediate effects, with vanadium again being the most effective. The preeminence of vanadium among the metals is novel. Where the heme crevice is closed (pH 4), transition metal ions mediated almost all of the reduction of oxygen, while at the lowest pH (2.6) transition metal ions were largely unnecessary. Vanadium(V) was the most active of the metals at all values of pH and the only metal to accelerate the oxidation of ferrocytochrome c at pH 2.6. Understanding of the range of biological actions of vanadium will not be complete without a knowledge of its redox reactivity within the components of biological systems.

[A seroepidemiological study on sexually transmitted HBV infection]

A seroepidemiological study on HBV infection was conducted among female prostitutes in houses of detention in Guangzhou and Fuzhou in 1989, 1990 to understand the situation of sexually transmitted HBV infection in selected areas of China, and prevalence of HBV infection in sexual misbehavior populations. The incidence of HBV infection was 84.82% among the population, and 21.6% was HBsAg positive. The prevalence of HBsAg was significantly higher in prostitutes than in pregnant women. The results show that there is a relatively serious HBV infection in prostitutes in certain cities along coastal region in China.

Role of the NH2-terminal domain of angiotensin II (ANG II) and [Sar1]angiotensin II on conformation and activity. NMR evidence for aromatic ring clustering and peptide backbone folding compared with [des-1,2,3]angiotensin II

The role of the NH2 termini of angiotensin II (ANG II) and [Sar1]ANG II on conformation and activity were examined by proton NMR two-dimensional-J-correlated spectroscopy and one-dimensional nuclear Overhauser effect studies in the relatively nonpolar "receptor-simulating" environment provided by dimethyl sulfoxide-d6, using the biologically inactive COOH-terminal pentapeptide [des1,2,3]ANG II as control. Irradiation of C alpha H, C2H, and C4H proton resonances in ANG II and [Sar1]ANG II resulted in enhancements of Tyr and Phe ring proton resonances, indicating that the three aromatic rings cluster together. Very strong enhancements (17-22%) of the C alpha Y proton resonance in ANG II and [Sar1]ANG II upon irradiation of the C alpha H proton resonance, and vice versa, revealed that a Tyr-Ile-His bend is a predominant feature of the conformation of the two agonists. In contrast, saturation of the C alpha H and C alpha Y proton resonances in the control pentapeptide [des-1,2,3]ANG II did not produce, respectively, any C alpha Y or C alpha H proton nuclear Overhauser effect enhancement, illustrating the absence of a Tyr-Ile-His bend in the truncated ANG II peptide. The present findings indicate that the NH2-terminal domain of ANG II appears to have an essential role in generating the biologically active charge relay conformation of the hormone.

Activation-induced exposure of the thrombin anion-binding exosite. Interactions of recombinant mutant prothrombins with thrombomodulin and a thrombin exosite-specific antibody

The activation of serine protease zymogens involves conformational changes that increase the affinity of substrate binding and the activity of the catalytic center. The activation of prothrombin is particularly complex and requires several cleavages in the proenzyme region in addition to the conserved activation cleavage after Arg320. To understand how these cleavages lead to the exposure of the thrombin anion-binding exosite, a major macromolecular recognition site, interactions of recombinant human prothrombin derivatives with thrombomodulin, and an exosite-specific antibody were studied by competition binding and immunoprecipitation. By either method, the anion-binding exosite is not functional on prethrombin 2, which is cleaved after Arg271 and lacks fragment 1.2, nor on meizothrombin, which is cleaved only after Arg320. In contrast, the exosite is fully exposed on meizothrombin des-F1, which is cleaved after both Arg320 and Arg155 and therefore lacks amino-terminal fragment 1 (F1). Thus, two events are required to create the exosite. First, cleavage after Arg320 causes conformational changes that are much more extensive than those accompanying the activation of trypsinogen. Second, removal of amino-terminal F1 is necessary, perhaps to relieve steric hindrance. These results indicate that the F1 fragment regulates access to the thrombin exosite. The properties of meizothrombin des-F1 suggest that this prothrombin derivative could have a biological function.

[Study on antibacterial proteins from rabbit bladder mucosa]

Acid-soluble extract of rabbit bladder mucosa was obtained by washing out the bladder of normal female New Zealand rabbit with 1% acetic acid in the presence of proteinase inhibitors. Acid urea polyacrylamide electrophoresis (AU-PAGE) analysis indicated that the extract had more than 10 main protein bands. The currently-known antibiotic peptides, e. g. lysozyme and defensin-like molecules were not found in this material. When tested for antibacterial activity by using ultrasensitive radial diffusion assay, the acid-soluble extract effectively killed E. coli ML-35P. The gel overlay assay showed that the anti-bacterial activity of the acid-soluble extract was relevant to two protein bands referred to as rabbit bladder protein 1 (Rab BP-1) and rabbit bladder protein 2 (Rab BP-2). The Rab BP-1 and Rab BP-2 accounted for 2.5% and 1.2% of the total acid-soluble extract proteins, respectively. These results suggest that the long recognized ability of the normal rabbit bladder wall to kill adherent E. coli may result from the presence of endogenous antibacterial proteins associated with its mucosa.

Widespread tissue distribution of aminopeptidase A, an evolutionarily conserved ectoenzyme recognized by the BP-1 antibody

Early B-lineage cells in mice express a cell surface glycoprotein, recognized by the BP-1 and 6C3 monoclonal antibodies, that has been identified as aminopeptidase A (APA E.C.3.4.11.7). In the present studies we obtained evidence by DNA "zoo-blot" analysis that the APA gene is highly conserved. This ectoenzyme catalyzes the removal of N-terminal Glu- and Asp-residues to convert angiotensin II to angiotensin III, a degradation step important in local regulation of blood pressure in mammals. To gain further insight into the physiology of this molecule, which is shared between immune and vascular systems, we examined the tissue distribution of BP-1 mRNA using a cDNA probe and of the protein antigen using the BP-1 antibody for immunohistology. APA transcripts were present in all tissues examined. Abundant BP-1/APA was found in the intestinal brush border of the small intestine, renal glomeruli, proximal renal tubules, pulmonary alveolar walls and vascular endothelium in many organs. Other tissues containing the BP-1 antigen included stromal cells in the thymus cortex, bile canaliculi in liver, gall bladder epithelium, interlobular ducts in pancreas, the ovarian theca interna, basement membrane of the epididymis and the splanchnopleure in placenta. APA enzyme activities have been identified in most of these locations, in keeping with identification of the BP-1/6C3 antigen as APA. The data suggest this ectopeptidase may serve diverse physiologic roles in a broad spectrum of tissues.

Hyperactive recombination in the mitochondrial DNA of the natural death nuclear mutant of Neurospora crassa

In Neurospora crassa, a recessive mutant allele of a nuclear gene, nd (natural death), causes rapid degeneration of the mitochondrial DNA, a process that is manifested phenotypically as an accelerated form of senescence in growing and stationary mycelia. To examine the mechanisms that are involved in the degradation of the mitochondrial chromosome, several mitochondrial DNA restriction fragments unique to the natural-death mutant were cloned and characterized through restriction, hybridization, and nucleotide sequence analyses. All of the cloned DNA pieces contained one to four rearrangements that were generated by unequal crossing-over between direct repeats of several different nucleotide sequences that occur in pairs and are dispersed throughout the mitochondrial chromosome of wild-type Neurospora strains. The most abundant repeats, a family of GC-rich sequences that includes the so-called PstI palindromes, were not involved in the generation of deletions in the nd mutant. The implication of these results is that the nd allele hyperactivates a general system for homologous recombination in the mitochondria of N. crassa. Therefore, the nd+ allele either codes for a component of the complex of proteins that catalyzes recombination, and possibly repair and replication, of the mitochondrial chromosome or specifies a regulatory factor that controls the synthesis or activity of at least one enzyme or ancillary factor that is affiliated with mitochondrial DNA metabolism.

Endopolygalacturonase in Apples (Malus domestica) and Its Expression during Fruit Ripening

The activity of polygalacturonase (PG) has been detected in ripe McIntosh apples (Malus domestica Borkh. cv McIntosh) both by enzyme activity measurement and immunoblotting using an anti-tomato-PG antibody preparation. PG activity increased during fruit ripening and remained steady, or decreased slightly, after 5 months of controlled atmospheric storage. The enzyme had a relative molecular weight of 45,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 56,000 to 61,000 when determined by gel filtration. Viscosity and reducing end group measurements with a commercial pectin preparation showed that the enzyme is endo acting. In RNA and DNA blot hybridization experiments, a full-length tomato PG cDNA hybridized with the apple RNA and DNA, showing the identity of genes encoding the activity of the enzyme in tomato and apple.

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.