Targeted disruption of gp130, a common signal transducer for the interleukin 6 family of cytokines, leads to myocardial and hematological disorders

gp130 is a ubiquitously expressed signal-transducing receptor component shared by interleukin 6, interleukin 11, leukemia inhibitory factor, oncostatin M, ciliary neurotrophic factor, and cardiotrophin 1. To investigate physiological roles of gp130 and to examine pathological consequences of a lack of gp130, mice deficient for gp130 have been prepared. Embryos homozygous for the gp130 mutation progressively die between 12.5 days postcoitum and term. On 16.5 days postcoitum and later, they show hypoplastic ventricular myocardium without septal and trabecular defect. The subcellular ultrastructures in gp130-/- cardiomyocytes appear normal. The mutant embryos have greatly reduced numbers of pluripotential and committed hematopoietic progenitors in the liver and differentiated lineages such as T cells in the thymus. Some gp130-/- embryos show anemia due to impaired development of erythroid lineage cells. These results indicate that gp130 plays a crucial role in myocardial development and hematopoiesis during embryogenesis.

Production of fructosyl lysine oxidase from Fusarium oxysporum S-1F4 on autoclave-browned medium

In Fusarium oxysporum S-1F4, fructosyl lysine oxidase (FLOD) was induced with N epsilon-fructosyl N alpha-Z-lysine (epsilon-FL), which is a model compound of a glycated protein, and the induction was inhibited by the addition of cycloheximide in the growing cells. FLOD formation was greatly enhanced in an autoclave-browned medium containing glucose and L-lysine. Some Amadori compounds formed from glucose and L-lysine during autoclaving were assumed to induce the enzyme. After optimization of the culture conditions, FLOD produced in the browned medium was comparable to that in the medium with epsilon-FL.

Treatment of high-risk acute lymphoblastic leukemia in children using the AL851 and ALHR88 protocols: a report from the Kyushu-Yamaguchi Children's Cancer Study Group in Japan

A total of 125 children, who were diagnosed as having high-risk acute lymphoblastic leukemia (ALL), were treated with two consecutive protocols designated as AL851 (1985-1988) and ALHR88 (1988-1990). All patients received induction therapy consisting of vincristine (VCR), prednisolone (PSL), daunorubicin (DNR), and I-asparaginase (I-Asp). In the ALHR88 protocol, the patients whose blasts in the bone marrow (BM) were > or = 25% on day 14 of induction therapy and who were classified into T-cell type received additional cytosine arabinoside (AraC). After consolidation with intermediate-dose methotrexate (MTX), reinduction therapy including VCR, dexamethasone, and adriamycin followed by high-dose AraC was done for all patients. Intrathecal MTX and 24Gy of cranial irradiation were used to prevent central nervous system leukemia. A maintenance therapy consisting of 6-mercaptopurine, cyclophosphamide, MTX, DNR, VCR, and AraC was administered for 3 years after achieving a complete remission (CR). CR was achieved in 51/55 (92.7%) for AL851 and 68/70 (97.1%) for ALHR88. The 5-year event-free survival rates were 49.1 +/- 6.7% in AL851 and 62.5 +/- 6.1% in ALHR88. The factors related to a poor prognosis were a high initial leukocyte count of greater than 50 x 10(9)/L (P < 0.001), an L2 morphology of leukemic cells by FAB classification (P = 0.009), the chromosomal abnormality (P = 0.004) and high residual leukemic cells in BM (> or = 25%) on day 14 of induction therapy (P < 0.001). Taking these factors into consideration, more intensive protocols were started in 1990 for the patients with high-risk ALL.

Effect of a novel histamine H2 receptor antagonist, IT-066, on acute gastric injury induced by ischemia-reperfusion in rats, and its antioxidative properties

The effect of a novel histamine H2 receptor antagonist IT-066 (3-amino-4-[4-[4-(1-piperidinomethyl)-2-pyridyloxy]-cis-2-++ +butenylamino]- 3-cyclobutene-1,2-dione hydrochloride), on acute gastric mucosal injury induced by ischemia-reperfusion was investigated from the standpoint of oxygen radical-mediated lipid peroxidation in rats. Ischemia-reperfusion injury was produced in the rat stomach by applying a small vascular clamp to the celiac artery for 30 min and subsequent removal of the clamp for 60 min. The decrease in gastric mucosal blood flow was not influenced by treatment with IT-066. The antiulcer activity of IT-066 was demonstrated in this injury after intragastric ingestion as well as after intravenous injection. IT-066 significantly inhibited this injury in the presence of exogenous HCl. The mucosal protection by IT-066 was not reversed by pretreatment with indomethacin or nitric oxide synthase inhibitor. The increase in lipid peroxides in the gastric mucosa after ischemia-reperfusion was significantly inhibited by the intragastric treatment with IT-066 at doses of 1.0 and 3.0 mg/kg. The total area of erosions closely paralleled the accumulation of lipid peroxide with a significant correlation. A spin trapping method using 5,5-dimethyl-1-pyrroline-N-oxide showed that IT-066 scavenged superoxide radical and hydroxyl radical generated by the hypoxanthine-xanthine oxidase system and the hydrogen peroxide-ferrous iron system, respectively. IT-066 also significantly inhibited the in vitro increase of lipid peroxide in the gastric mucosal homogenates induced by a free radical initiator. These results suggest that the protective effect of IT-066 against ischemia/reperfusion-induced gastric mucosal injury may result in part from its antioxidative properties.

Purification and characterization of a new serine proteinase from Bacillus subtilis with specificity for amino acids at P1 and P2 positions

A proteinase was purified 230-fold to apparent homogeneity from culture filtrates of Bacillus subtilis by a series of column chromatographies on DE52, DEAE-Toyopearl, Cellulofine GC200M, and Mono-Q, using Boc-Ala-Ala-Pro-Ser-pNA as a substrate. The molecular weight of the proteinase was estimated to be 42,000 by SDS-PAGE in the presence of 2-mercaptoethanol. Studies on the substrate specificity with peptide p-nitroanilides and natural peptides revealed that this proteinase preferentially hydrolyzed the peptide bond on the carboxyl-terminal side of either serine or alanine residues at the P1 position and hydrophobic bulky amino acids at P2. It was most active at pH 9.5 for the hydrolysis of Boc-Ala-Ala-Pro-Ser-pNA. The enzyme was inactivated by diisopropyl fluorophosphate (DFP), but not by tosyl-L-phenylalanine chloromethylketone (TPCK) or by EDTA. Based on the reactivity toward substrates and inhibitors, this enzyme differs from elastase- or subtilisin-like proteinase, hence it is a new type of proteinase with specificity for amino acids at P1 and P2 positions.

[Subgingival distribution of periodontopathic bacteria in periodontic patients and susceptibility of these bacteria to minocycline-HCl]

The present study was carried out to examine the distribution of six periodontopathic bacteria in deep periodontal pockets and to reconfirm the effect of Periocline on these periodontopathic bacteria. Samples from sixty-two periodontal pockets were collected at pocket depths of over 4 mm in twenty-one periodontitis patients aged 43 to 75 years. After sampling, Periocline was applied topically to the selected pockets once a week for four weeks and reexamined. The detected rates of the periodontopathic bacteria were Capnocytophaga sputigena (37.1%), Prevotella intermedia (22.6%), Porphyromonas gingivalis (22.6%), Fusobacterium nucleatum (20.1%), Actinobacillus actinomycetemcomitans (9.7%) and Eikenella corrodens (4.8%). The distribution of the bacteria was compound because two or three bacterial species were found to coexist. In view of the MIC of minocycline-HCI for these bacteria, increase of most of the measured bacteria was suppressed by the concentration of drugs, including Periocline. However, clinical strains of P. i. were considered to have low susceptibility to minocycline-HCl. In view of the effect of topical application of drugs, no significant differences were found. From these results, it was suggested that Periocline contained effective concentration of minocycline-HCl.

Distribution and properties of fructosyl amino acid oxidase in fungi

Fructosyl amino acid oxidase, and enzyme that can be used for the determination of glycated proteins in blood samples from diabetic patients, was used to screen cultures in our microorganism culture collection. Fructosyl amino acid oxidase was found only in the strains of four genera of fungi, Aspergillus, Fusarium, Gibberella, and Penicillium and exhibited different substrate specificities against fructosyl valine and N epsilon-fructosyl N alpha-Z-lysine. A fructosyl valine-specific enzyme from Penicillium janthinellum AKU3413 was monomeric (M(r), 49,000), was most active at 35 degrees C and pH 8.0, and had a covalently bound flavin adenine dinucleotide as a prosthetic group.

Proton nuclear magnetic resonance studies of the complexation of zinc(II) with glycyl-L-histidylglycine

The complexation of Zn(II) with glycyl-L-histidylglycine and its deuterated derivatives, glycyl-d2-L-histidylglycine and glycyl-L-histidylglycine-d2, was studied by proton nuclear magnetic resonance spectroscopy over the pD range, from 3.4 to 11.0, at 25 degrees C. Addition of Zn(II) to the peptide made the resonances of both imidazole C2-H and C4-H and both methylene-protons of glycyl residues at the amino-terminal and carboxylate end split to three lines in the pD range above 7.0. From the behavior of the C2-H and C4-H chemical shifts, formation of at least two species, in which the imidazole and amino nitrogens coordinated to the metal ion forming a chelate ring, was suggested. Those two species, the ratio of which varied depending on the total concentrations of complexes, seemed to be interconvertible; one referred to as B is a monomer and the other, referred to as C, may be a dimeric or polymeric complex.

The lipid structure of the glycosylphosphatidylinositol-anchored mucin-like sialic acid acceptors of Trypanosoma cruzi changes during parasite differentiation from epimastigotes to infective metacyclic trypomastigote forms

The major acceptors of sialic acid on the surface of metacyclic trypomastigotes, which are the infective forms of Trypanosoma cruzi found in the insect vector, are mucin-like glycoproteins linked to the parasite membrane via glycosylphosphatidylinositol anchors. Here we have compared the lipid and the carbohydrate structure of the glycosylphosphatidylinositol anchors and the O-linked oligosaccharides of the mucins isolated from metacyclic trypomastigotes and noninfective epimastigote forms obtained in culture. The single difference found was in the lipid structure. While the phosphatidylinositol moiety of the epimastigote mucins contains mainly 1-O-hexadecyl-2-O-hexadecanoylphosphatidylinositol, the phosphatidylinositol moiety of the metacyclic trypomastigote mucins contains mostly (approximately 70%) inositol phosphoceramides, consisting of a C18:0 sphinganine long chain base and mainly C24:0 and C16:0 fatty acids. The remaining 30% of the metacyclic phosphatidylinositol moieties are the same alkylacylphosphatidylinositol species found in epimastigotes. In contrast, the glycosylphosphatidylinositol glycan cores of both molecules are very similar, mainly Man alpha 1-2Man alpha 1-2Man alpha 1- 6Man alpha 1-4GlcN. The glycans are substituted at the GlcN residue and at the third alpha Man distal to the GlcN residue by ethanolamine phosphate or 2-aminoethylphosphonate groups. The structures of the desialylated O-linked oligosaccharides of the metacyclic trypomastigote mucin-like molecules, released by beta-elimination with concomitant reduction, are identical to the structures reported for the epimastigote mucins (Previato, J. O., Jones, C., Gonçalves, L. P. B., Wait, R., Travassos, L. R., and Mendoça-Previato, L. (1994) Biochem. J. 301, 151-159). In addition, a significant amount of nonsubstituted N-acetylglucosaminitol was released from the mucins of both forms of the parasite. Taken together, these results indicate that when epimastigotes transform into infective metacyclic trypomastigotes, the phosphatidylinositol moiety of the glycosylphosphatidylinositol anchor of the major acceptor of sialic acid is modified, while the glycosylphosphatidylinositol anchor and O-linked sugar chains remain essentially unchanged.

Targeted mutation in the Fas gene causes hyperplasia in peripheral lymphoid organs and liver

Fas, a type I membrane protein that transduces an apoptotic signal, is expressed in lymphocytes as well as in various tissues such as the liver, lung and heart. The mouse lymphoproliferation (lpr) mutation is a leaky mutation in Fas. By means of gene targeting, we generated a mouse strain which is completely deficient in Fas. In addition to the massive production of lymphocytes, the Fas-null mice showed substantial liver hyperplasia, which was accompanied by the enlargement of nuclei in hepatocytes. The Fas system seems to play a role in the apoptotic process to maintain homeostasis of the liver as well as the peripheral lymphoid organs.

Intrathecal administration of N-methyl-D-aspartate receptor antagonist reduces the minimum alveolar anaesthetic concentration of isoflurane in rats

We have studied the effect of intrathecal administration of N-methyl-D-aspartate (NMDA) receptor antagonists on the minimum alveolar anaesthetic concentration (MAC) of isoflurane in rats. In Wistar rats fitted with indwelling intrathecal catheters, we determined the MAC of isoflurane after administration of a competitive NMDA receptor antagonist, APV (0.01, 0.1, 1.0, 10, 30 micrograms), a non-competitive NMDA receptor antagonist, MK801 (0.1, 1.0, 10, 30 micrograms). NMDA (0.01, 0.1, 1.0, 10, 30 micrograms) and saline. APV at all doses except 0.01 micrograms decreased MAC by 17.1-32% (P < 0.001 and P < 0.0001). Although MK801 at 10 and 30 micrograms reduced MAC by 24.3-31.7% (P < 0.001 and P < 0.0001), lower doses did not affect MAC. Intrathecal administration of NMDA reversed these decreases in MAC, but not to control values with APV 10 and 30 micrograms and MK801 30 micrograms. We suspect that NMDA and NMDA receptor antagonists play important roles in the spinal cord in determining the MAC of isoflurane.

Development of potent serotonin-3 (5-HT3) receptor antagonists. II. Structrue-activity relationships of N-(1-benzyl-4-methylhexahydro-1H-1,4- diazepin-6-yl)carboxamides

Our studies on 4-amino-5-chloro-2-ethoxybenzamides led to the discovery that the N-(1,4-dimethylhexahydro-1H-1,4-diazepin-6-yl)benzamide 9 and the 1-benzyl-4-methylhexahydro-1H-1,4-diazepine analogue 10 are potent serotonin-3 (5-HT3) receptor antagonists. Structure-activity relationship (SAR) studies on the influence of the aromatic nucleus of 9 and 10 upon inhibition of the von Bezold-Jarisch reflex in rats are described. Heteroaromatic rings such as pyrrole, thiophene, furan, pyridine, pyridazine, 1,2-benzisoxazole, indole, quinoline, and isoquinoline rings showed weak 5-HT3 receptor antagonistic activity. Within this series, use of the 1H-indazole ring as an aromatic moiety led to a substantial increase of the activity; the 1H-indazolylcarboxamides 54, 57, 97, and 102 showed potent 5-HT3 receptor antagonistic activity. The optimal compound identified via extensive SAR studies was N-(1-benzyl-4-methylhexahydro-1H-1,4-diazepin-6-yl)-1H-indaz ole-3- carboxamide (54), whose effect was superior to that of the corresponding benzamide 10 and essentially equipotent to those of ondanbsetron (1) and granisetron (4).

Role of neutrophil-mediated inflammation in aspirin-induced gastric mucosal injury

The objectives of this study were to determine the roles of neutrophil-endothelial cell interactions and oxygen-derived free radicals in the pathogenesis of aspirin-induced gastric mucosal injury in rats. Oral administration of acidified aspirin (200 mg/kg) resulted in linear hemorrhagic erosions and an increase in myeloperoxidase activity, an index of neutrophil infiltration, in the gastric mucosa. Aspirin-induced gastric damage and the increase in myeloperoxidase activity were significantly inhibited by the injection of anti-CD11a, anti-CD11b, anti-intercellular adhesion molecule-1 monoclonal antibodies, and the combination of superoxide dismutase and catalase, which are scavengers of active oxygen species. These results suggest that neutrophil-endothelial adhesive interactions, which occur via CD11a/ CD18- and CD11b/CD18-dependent interactions with intercellular adhesion molecule-1, and oxygen-derived free radicals produced by neutrophils are implicated in the production of aspirin-induced gastric mucosal injury.

Growth Kinetics of Thiobacillus thiooxidans on the Surface of Elemental Sulfur

The growth kinetics of Thiobacillus thiooxidans on elemental sulfur in batch cultures at 30(deg)C and pH 1.5 was studied by measuring the time courses of the concentration of adsorbed cells on sulfur, the concentration of free cells suspended in liquid medium, and the amount of sulfur oxidized. As the elemental sulfur was oxidized to sulfate ions, the surface concentration of adsorbed cells per unit mass of sulfur approached a maximum value (maximum adsorption capacity of sulfur particles) whereas the concentration of free cells continued to increase with time. There was a close relationship between the concentrations of free and adsorbed cells during the microbial sulfur oxidation, and the two cell concentrations were well correlated by the Langmuir isotherm with adsorption equilibrium constant K(infA) and maximum adsorption capacity X(infAm) of 2.10 x 10(sup-9) ml per cell and 4.57 x 10(sup10) cells per g, respectively. The total concentration of free and adsorbed cells increased in parallel with the amount of sulfate formed. The total growth on elemental sulfur gave a characteristic growth curve in which a linear-growth phase followed the period of an initial exponential phase. The batch rate data collected under a wide variety of inoculum levels (about 10(sup5) to 10(sup8) cells per ml) were consistent with a kinetic model assuming that the growth rate of adsorbed bacteria is proportional to the product of the concentration, X(infA), of adsorbed cells and the fraction, (theta)(infV), of adsorption sites unoccupied by cells. The kinetic and stoichiometric parameters appearing in the model were estimated from the experimental data, and the specific growth rate, (mu)(infA), and growth yield, Y(infA), were 2.58 day(sup-1) and 2.05 x 10(sup11) cells per g, respectively. The proposed model and the parameter values allowed us to predict quantitatively the surface attachment of T. thiooxidans cells on elemental sulfur and the bacterial growth in both initial exponential and subsequent linear phases. The transition from exponential to linear growth was a result of two competing factors: an increase in the adsorbed-cell concentration, X(infA), permitted a decrease in the unoccupied-site fraction, (theta)(infV).

A dopamine D3 receptor agonist, 7-OH-DPAT, causes vomiting in the dog

R(+)7-hydroxy-N,N-di-n-propyl-2-aminotetralin (R(+)-7-OH-DPAT), a selective dopamine D3 receptor agonist, (0.03-0.3 mg/kg, s.c.) dose-relatedly caused emesis, whereas S (-)-7-OH-DPAT at even 1 mg/kg did not induce emesis in dogs. Apomorphine (0.03-0.3 mg/kg, s.c.) or quinpirole (0.03-0.1 mg/kg, s.c.) also caused emesis in a dose-dependent manner. The potency of R(+)-7-OH-DPAT in inducing emesis was the same as that of apomorphine and quinpirole. On the other hand, SKF-38393 (1 and 3 mg/kg, s.c.), a selective D1 receptor agonist, failed to induce emesis in dogs. The emesis induced by R(+)-7-OH-DPAT (0.3 mg/kg, s.c.) was inhibited by S(-)-eticlopride (0.01-0.1 mg/kg, s.c.), a potent D2 and D3 receptor antagonist but not by SCH-23390 (1 mg/kg, s.c.), a selective D1 receptor antagonist or clozapine (1 mg/kg, s.c.), a D4 receptor antagonist. These results indicate that dopamine D3 receptors play an important role in the genesis of emesis in dogs.

An improved method for large-scale purification of recombinant human glucagon

Glucagon was expressed in Escherichia coli as a fusion protein including the glucagon sequence [Ishizaki et al. (1992), Appl. Microbiol. Biotechnol. 36, 483-486]. The high-level expression of a protein in E. coli often results in an insoluble aggregate called an inclusion body containing a fusion protein. In our previous report [Yoshikawa et al. (1992), J. Protein Chem. 11, 517-525], we solubilized this inclusion body by using guanidinium chloride. However, the existence of denaturant caused problems such as a low proteolytic activity for transforming the fusion protein into glucagon and complicated purification methods. We tried to improve the method to enable large-scale purification. At alkaline pH, the inclusion body could be solubilized to a high concentration and cleaved by amino acid-specific endopeptidases. By utilizing isoelectric precipitations as a new economical purification method for glucagon from intermediates, the glucagon obtained was shown to be over 99.5% pure by analytical RP-HPLC. The yield was almost equal that of our previous method, and the glucagon produced was chemically and biochemically equivalent to natural glucagon.

[Relations between chest CT and pathologic findings in pulmonary infarction associated with lung cancer]

Chest radiographic (mainly CT), and pathological findings in pulmonary infarction associated with lung cancer were studied to obtain information useful for the interpretation of CT findings, and to help determine the cause of infarction. Sixteen cases of lung infarction were chosen from among 518 cases of lung cancer. All patients were operated on between January 1980 and December 1990. Sixteen surgical cases and one autopsy case all with evidence of lung cancer and infarction were chosen. There were 13 men and 4 women with a mean age of 56 years. Adenocarcinoma was found in 8 cases, squamous cell carcinoma in 6, adenosquamous carcinoma in 2, and small cell carcinoma in 1. Chest radiographs and CT revealed infarction shadows in 8 of the 16 cases. Typical CT findings for pulmonary infarction were: shadows located in the same lobe and periphery as the cancer; ill-defined, 10-25 mm nodular shadows; and lesions located both in the subpleural zone and apart from the pleura. Lesion counts in each area were about the same. Observation of one patient for 2 months revealed a decrease in the size of the nodular shadows and clarification of their margins. In most cases, centrally extended cancer resulted in vascular stenosis and infarction.

Characterization of the 5'-flanking region and chromosomal assignment of the human brain natriuretic peptide gene

Brain natriuretic peptide (BNP) is a cardiac hormone that occurs predominantly in the ventricle, and synthesis and secretion of BNP are greatly augmented in patients with congestive heart failure and in animal models of ventricular hypertrophy. In order to elucidate the molecular mechanisms underlying the human BNP gene expression in the heart, the human BNP gene was isolated from a size-selected genomic minilibrary. The 1.9-kb human BNP 5'-flanking region (-1813 to +110) contained an array of putative cis-acting regulatory elements. Various lengths of the cloned 5'-flanking sequences were linked upstream to the bacterial chloramphenicol acetyltransferase (CAT) gene, and their promoter activities were assayed. The 1.9-kb promoter region showed a high-level CAT activity in cultured neonatal rat ventricular cardiocytes. When the CT-rich sequences (-1288 to -1095) were deleted, the high-level activity was reduced to approximately 30%. The 399-bp BNP 5'-flanking region (-289 to +110) showed approximately 10% activity of the 1.9-kb region. Furthermore, using human-rodent somatic hybrid cell lines, the BNP gene was assigned to human chromosome 1, on which the atrial natriuretic peptide gene is localized. The present study leads to a better understanding of the molecular mechanisms for the human BNP gene expression in the heart.

Development of potent serotonin-3 (5-HT3) receptor antagonists. I. Structure-activity relationships of 2-alkoxy-4-amino-5-chlorobenzamide derivatives

A new series of 2-alkoxy-4-amino-5-chlorobenzamide derivatives bearing five- to seven-membered heteroalicyclic rings in the amine moiety was synthesized and evaluated for serotonin-3 (5-HT3) receptor antagonistic activity by assaying the ability to antagonize the von Bezold-Jarisch reflex in rats. The five- to seven-membered heteroalicycles comprise pyrrolidine, morpholine, 1,4-thiazine, piperidine, piperazine, 1,4-oxazepine, 1,4-thiazepine, azepine, and 1,4-diazepine rings. Among them, some benzamide derivatives having a 1,4-diazepine ring showed a potent 5-HT3 receptor antagonistic activity. In particular, 4-amino-5-chloro-N-(1,4-dimethylhexahydro-1H-1,4-diazepin-6- yl)-2- ethoxybenzamide (96) and the 1-benzyl-4-methylhexahydro-1H-1,4-diazepine analogue 103 showed potent 5-HT3 receptor antagonistic activity without 5-HT4 receptor binding affinity.

Synthesis and structure-activity relationships of 4-amino-5-chloro-2-ethoxybenzamides with six- and seven-membered heteroalicycles as potential gastroprokinetic agents

A new series of 4-amino-5-chloro-2-ethoxybenzamides 3b--f and 5--8 bearing six- and seven-membered heteroalicycles was prepared and evaluated for gastroprokinetic activity. Compounds 3b--e, derived by replacement of the morpholine oxygen of 4-amino-N-[(4-benzyl-2-morpholinyl)methyl]-5- chloro-2-ethoxybenzamide (3a) with other atoms (sulfur, nitrogen and carbon), generally exhibited a potent gastric emptying activity. N-(4-Benzyl-3-morpholinyl)methylbenzamide (5a) and its analogues 5b--e had weaker activity. However, N-(4-benzyl-3-morpholinyl)ethylbenzamide 8 was as potent as 3a. Benzamides 6a--e, having seven-membered heteroalicycles, showed fairly potent activity. Molecular superimpositions of 5a, 6a and 8 upon 3a using computer graphics suggested that the direction of the N-benzyl group greatly influences the gastric emptying activity, whereas the location of the alicyclic nitrogen is less critical.

Aspirin-induced, neutrophil-mediated injury to vascular endothelium

Previous studies indicate that aspirin can promote neutrophil (PMN) adhesion to endothelial cells and neutrophil-mediated endothelial cell detachment. The objectives of the present study were to determine whether PMN adhesion is a prerequisite for aspirin-induced, PMN-mediated endothelial cell detachment and whether neutrophil-derived oxidants and/or proteases are responsible for the cell detachment. Human PMNs were added to confluent monolayers of human umbilical vein endothelial cells (HUVEC) and coincubated with or without aspirin at a clinically relevant concentration (300 micrograms/ml). Aspirin-activated PMNs induced endothelial cell detachment, but not cell lysis. Endothelial cell detachment was always preceded by retraction of endothelial cells within the monolayer. The aspirin-induced, neutrophil-mediated cell detachment was prevented by a monoclonal antibody directed against CD11/CD18 adhesion integrins on PMNs. Elastase inhibitors, but not superoxide dismutase or catalase, prevented both endothelial cell retraction and detachment. If aspirin-activated neutrophils were allowed to migrate across the monolayers, endothelial cell retraction or detachment did not occur. These studies indicate that aspirin-induced, PMN-mediated endothelial cell retraction and detachment requires PMN adhesion to the target cells and is due to neutrophil-derived elastase. Endothelial cell retraction, induced by activated neutrophils, may represent an exaggeration of a normal physiologic event, i.e., neutrophil emigration.