| 7932180 |
Ro 25-1553: a novel, long-acting vasoactive intestinal peptide agonist. Part I: In vitro and in vivo bronchodilator studies |
None |
J Pharmacol Exp Ther |
Ro 25-1553: a novel, long-acting vasoactive intestinal peptide agonist. Part I: In vitro and in vivo bronchodilator studies
Abstract
- Ro 25-1553, a cyclic peptide analog of vasoactive intestinal peptide (VIP), was designed to overcome many of the deficiencies inherent in this natural neuropeptide. On isolated guinea pig tracheal smooth muscle, Ro 25-1553 produces concentration-dependent relaxation of contractile responses to a number of different spasmogens. Depending on the contractile stimulus, Ro 25-1553 is 24 to 89 times more potent than VIP as a relaxant of guinea pig trachea. The high potency of Ro 25-1553 extends to studies on isolated, histamine-contracted, human bronchial smooth muscle, where Ro 25-1553 exhibits a 390-fold enhancement over native VIP and is more potent than other bronchodilating drugs, such as the beta 2-adrenoceptor agonists isoproterenol and salbutamol. Ro 25-1553 was shown to displace the radioligand 125I-VIP from rat forebrain membranes with an IC50 value of 4.98 nM, thereby demonstrating that it acts at a VIP receptor. In addition, when tested in a battery of 40 other binding assays (e.g., muscarinic, histamine, LTs, Ca++, TxA2, endothelin, alpha and beta adrenergic, platelet-activating factor, neurokinins, etc.) at concentrations as high as 10 microM, Ro 25-1553 was found to be inactive; thus it appears to be specific for VIP receptors. The potent smooth muscle relaxant activity exhibited in vitro by Ro 25-1553 is also evident after in vivo intratracheal administration or aerosolization of the compound. Pulmonary responses evoked by histamine, leukotriene D4, platelet-activating factor and acetylcholine are inhibited dose-dependently by intratracheally instilled Ro 25-1553 with nearly identical potency (ED50 values ranging from 0.07 micrograms to 0.26 micrograms).(ABSTRACT TRUNCATED AT 250 WORDS)
|
| 7932181 |
Ro 25-1553: a novel, long-acting vasoactive intestinal peptide agonist. Part II: Effect on in vitro and in vivo models of pulmonary anaphylaxis |
None |
J Pharmacol Exp Ther |
Ro 25-1553: a novel, long-acting vasoactive intestinal peptide agonist. Part II: Effect on in vitro and in vivo models of pulmonary anaphylaxis
Abstract
- Studies were conducted to compare the effect of native vasoactive intestinal peptide (VIP), Ro 25-1553 (a cyclic peptide analog of VIP) and salbutamol (a beta2-adrenoceptor agonist) on antigen-induced pathophysiological effects in the guinea pig. Ro 25-1553 and salbutamol (0.01-1.0 microM) prevented antigen-induced contractions of the guinea pig trachea in vitro with IC50 values of 0.07 and 0.05 microM, respectively. VIP (0.01-1.0 microM) had no effect on antigen-induced tracheal contractions. Aerosolized Ro 25-1553 and salbutamol were equipotent in preventing antigen-induced increases in guinea pig lung resistance (IC50 value = 0.0001%), whereas aerosolized VIP (0.1%) was ineffective. Ro 25-1553 (0.1-100 micrograms), instilled intratracheally 2 min before the antigen challenge of buffer-perfused lungs from sensitized guinea pigs, produced a dose-dependent inhibition of bronchoconstrictor, vasoconstrictor and edemagenic responses, whereas intratracheal VIP (100 micrograms) had no effect. Intratracheal salbutamol (0.1-100 micrograms) inhibited antigen-induced responses in a manner comparable to Ro 25-1553. Lung inflammation was assessed as leukocyte accumulation in bronchoalveolar lavage fluid after the antigen provocation. Aerosolized antigen-induced bronchoalveolar lavage eosinophilia (13-fold increase over saline controls) at 6 hr after challenge was prevented in a concentration-dependent manner by pretreatment with nebulized Ro 25-1553 and salbutamol, but not by pretreatment with native VIP. These results indicate that Ro 25-1553 suppresses various pathophysiological features associated with pulmonary anaphylaxis and asthma, including airway reactivity, edema formation and granulocyte accumulation.(ABSTRACT TRUNCATED AT 250 WORDS)
|
| 7932574 |
Self-immolative prodrugs: candidates for antibody-directed enzyme prodrug therapy in conjunction with a nitroreductase enzyme |
10.1021/jm00047a002. |
J Med Chem |
Self-immolative prodrugs: candidates for antibody-directed enzyme prodrug therapy in conjunction with a nitroreductase enzyme
Abstract
- The synthesis and properties of some prodrug candidates for antibody-directed enzyme prodrug therapy (ADEPT) are described. These compounds have been designed to generate the corresponding active drug upon interaction with a bacterial nitroreductase that can be conjugated to antibodies that recognize tumor-selective antigens. The active drugs included in the study are actinomycin D, mitomycin C, doxorubicin, 4-bis(2-chloroethyl)aminoaniline and 4-bis(2-chloroethyl)aminophenol. The prodrugs were all 4-nitrobenzyloxycarbonyl derivatives of these drugs, which upon enzymatic reduction, generated the drug through self-immolation of the 4-(hydroxyamino)benzyloxycarbonyl group. In the case of actinomycin D, the ratio of the dose required between drug and prodrug to give the same cytotoxicity was greater than 100. The prodrug was also much less toxic (20-100x) than actinomycin D to mice in vivo. Therefore this self-immolative prodrug has a potential application in the treatment of cancer using an ADEPT-type approach.
|
| 7932590 |
Influence of lipophilicity on the biological activity of cyclic pseudopeptide NK-2 receptor antagonists |
10.1021/jm00047a020. |
J Med Chem |
Influence of lipophilicity on the biological activity of cyclic pseudopeptide NK-2 receptor antagonists
Abstract
- A series of cyclic pseudopeptides of the formula cyclo(Leu psiCH2NHXaa-Gln-Trp-Phe-beta Ala), where Xaa represents the residue of an alpha-amino acid, has been synthesized in order to establish the role of the Xaa side chain for tachykinin NK-2 receptor antagonist activity. Syntheses have been carried out in solid phase with either Fmoc or Boc strategy. The antagonist potency on NK-2 receptors in the hamster isolated trachea (HT) and the rabbit isolated pulmonary artery (RPA) bioassays increases with Xaa lipophilicity; cyclo(Leu psiCH2NHCha-Gln-Trp-Phe-beta Ala) and cyclo(Leu psiCH2NHAsp(NHBzl)-Gln-Trp-Phe-beta Ala) resulted in being the two most active antagonists (pA2 = 9.06 and 9.26 on HT, respectively). A significant linear correlation was found between pA2 values determined in HT and RPA bioassays and capacity factors measured in reversed phase HPLC. The comparison between the biological activities of cyclic hexapeptides containing or not containing the aminomethylene moiety proved the crucial role of the pseudopeptide bond for determining high antagonist potency at the NK-2 receptor.
|
| 7940951 |
Synergistic effects of cyclosporin analogs--A, D, G, IMM-125--with rapamycin and/or brequinar |
None |
Transplant Proc |
Synergistic effects of cyclosporin analogs--A, D, G, IMM-125--with rapamycin and/or brequinar
Abstract
|
| 7945238 |
Identification of one- and two-chain forms of trypsinogen 1 produced by a human gastric adenocarcinoma cell line |
10.1042/bj3030187. |
Biochem J |
Identification of one- and two-chain forms of trypsinogen 1 produced by a human gastric adenocarcinoma cell line
Abstract
- It has previously been reported that two kinds of human gastric adenocarcinoma cell lines (STKM-1 and MKN28) secrete a trypsin-like enzyme. In this study, four molecular forms of the enzyme (26, 25, 24 and 23 kDa on non-reducing SDS/PAGE) were purified from the serum-free conditioned medium of STKM-1 cells. Analysis of N-terminal amino acid sequences showed that the 26 kDa protein was a two-chain form of trypsinogen 1 which had been produced by proteolytic cleavage of the Arg107-Val108 bond of trypsinogen 1, and the 24 kDa protein was the one-chain form of trypsinogen 1. The 25 and 23 kDa proteins were the activated forms of the two-chain and one-chain trypsinogen 1 respectively. Isoelectric focusing gave pI values of 6.3 and 6.6 for the 26 kDa two-chain form and the 24 kDa one-chain form of trypsinogen 1 respectively. Comparison of the proteolytic activities indicated that the one-chain trypsin 1 had amidolytic activity about four times higher than that of the two-chain enzyme.
|
| 7954658 |
Expression of mRNA for atrial natriuretic peptide receptor guanylate cyclase (ANPRA) in human retina. |
10.1007/bf02088585 |
Cell. Mol. Neurobiol. |
Expression of mRNA for atrial natriuretic peptide receptor guanylate cyclase (ANPRA) in human retina.
Abstract
- 1. Guanylate cyclase plays an important role in the visual cycle. Here we report the mRNA expression for the atrial natriuretic peptide receptor type A form of guanylate cyclase (ANPRA) in human retina. 2. Polymerase chain reaction using two sets of primers on the cDNAs reverse-transcribed from human retinal poly(A)+ RNA amplified two products under two different reaction conditions. The primers used in the reaction were designed from the reported sequence of human placental ANPRA cDNA. 3. Sequencing of the amplified products showed 100% sequence homology to the human placental ANPRA gene. Northern blot analysis indicated the presence of a 4.4-kb ANPRA mRNA in human retina, similar to that present in human brain.
|
| 7955174 |
Inhibition of integrin function by a cyclic RGD-containing peptide prevents neointima formation |
10.1161/01.cir.90.5.2203. |
Circulation |
Inhibition of integrin function by a cyclic RGD-containing peptide prevents neointima formation
Abstract
- RGD-containing peptides are able to prevent binding of ligands to certain integrins such as alpha IIb beta 3 (glycoprotein IIb/IIIa) and alpha v beta 3 and as such are inhibitors for platelet aggregation and smooth muscle cell migration, both of which are involved in neointima formation.\n \n \n \n \n Hamster carotid arteries were damaged, and neointima formation was determined at different time points. G4120, a cyclic RGD-containing peptide, was administered continuously intravenously by an implanted osmotic pump. Neointima formation was inhibited dose dependently. The inhibition was strongest when treatment was started before the vascular injury and continued for the full observation period. Treatment started after the damage and maintained until neointima assessment or started before and stopped earlier was less effective.\n \n \n \n \n Inhibition of integrin function by an RGD-containing peptide results in reduction of the development of a neointima. This effect is due both to an early event, which could be due to inhibition of secretion of PDGF by the platelets with blocked alpha IIb beta 3, and to a late event, possibly by interference with smooth muscle cell alpha v beta 3.
|
| 7957926 |
Expression of two variants of the human mu opioid receptor mRNA in SK-N-SH cells and human brain |
10.1016/0014-5793(94)01129-x |
FEBS Lett |
Expression of two variants of the human mu opioid receptor mRNA in SK-N-SH cells and human brain
Abstract
- A partial mu opioid receptor gene was isolated from a human genomic library using a mouse delta opioid receptor cDNA as a probe. Using information from this genomic clone and the published human mu receptor, MOR1, a cDNA was isolated from SK-N-SH mRNA that codes for a variant of the MOR1 mRNA, MOR1A. The presence of MOR1A is also shown in human brain using RT-PCR. MOR1A differs from MOR1 in that the 3' terminal intron has not been removed. An in-frame termination codon is found four amino acids after the 5' consensus splice site, making MOR1A eight amino acids shorter than MOR1. Both receptors show similar ligand binding and coupling to cAMP in CHO-K1 cells. The C-terminal differences between MOR1 and MOR1A could have effects on receptor coupling or receptor transport and localization.
|
| 7961627 |
In vivo conversion of L-serine to D-alanine in a ribosomally synthesized polypeptide |
None |
J Biol Chem |
In vivo conversion of L-serine to D-alanine in a ribosomally synthesized polypeptide
Abstract
- In the course of characterizing the bacteriocin lactocin S and its encoding gene, we discovered three alanine-for-serine substitutions which, apparently, is a violation of the genetic code. Subsequent chiral analysis of lactocin S hydrolysates revealed a correlation between D-alanine content and the three substitutions, implying a conversion of L-serine to D-alanine in lactocin S maturation. In order to explain this observation, we suggest a sequence of events initiated by the dehydration of serine, which is common in the biosynthesis of the lanthionine-containing polycyclic lantibiotics (Schnell, N., Entian, K.-D., Schneider, U., Götz, F., Zähner, H., Kellner, R. & Jung, G. (1988) Nature 333, 276-278; Jung, G. (1991) Angew, Chem. Int. Ed. Engl. 30, 1051-1068; Bierbaum, G. & Sahl, H.-G. (1993) Zentralbl. Bakteriol. 278, 1-22) and completed by the stereospecific reduction of dehydroalanine residues. The occurrence of non-lanthionine alpha-carbon stereoinversion in lactocin S maturation substantiates the hypothetical alpha-epimerization scheme originally put forward by Bycroft (Bycroft, B. W. (1969) Nature 224, 595-597), and we propose a revision of this model to accommodate the lactocin S-type stereoinversion. Lactocin S is the first prokaryotic exception to the rule that only L-amino acids are included in ribosomally synthesized peptides.
|
| 7964174 |
Isolation of antimicrobial peptides from avian heterophils |
10.1002/jlb.56.5.661. |
J Leukoc Biol |
Isolation of antimicrobial peptides from avian heterophils
Abstract
- Five bactericidal peptides (chicken heterophil peptides CHP1 and CHP2; turkey heterophil peptides THP1, THP2, and THP3) were purified from avian heterophil granules. All peptides were cationic and rich in cysteine, arginine, and lysine. The complete amino acid sequence, consisting of 39 amino acids, was determined for CHP1. This peptide had a molecular weight of 4481 as determined by mass spectrometry. Partial NH2-terminal amino acid sequences were obtained for the remaining peptides. Both chicken peptides and THP1 shared sequence homology at 22 residues and a cysteine motif which was similar to that of bovine beta-defensins. THP2 and THP3 were homologous to each other but were not homologous to the other three and had a unique cysteine motif. Peptides CHP1, CHP2, and THP1 killed Staphylococcus aureus and Escherichia coli in vitro, whereas THP2 and THP3 killed only S. aureus in vitro.
|
| 7972045 |
Special evolution of neurohypophysial hormones in cartilaginous fishes: asvatocin and phasvatocin, two oxytocin-like peptides isolated from the spotted dogfish (Scyliorhinus caniculus) |
10.1073/pnas.91.23.11266. |
Proc Natl Acad Sci U S A |
Special evolution of neurohypophysial hormones in cartilaginous fishes: asvatocin and phasvatocin, two oxytocin-like peptides isolated from the spotted dogfish (Scyliorhinus caniculus)
Abstract
- In contrast to most vertebrate species that possess one oxytocin-like hormone and one vasopressin-like hormone, a few groups, such as marsupials or cartilaginous fishes, are endowed with two peptides of either or both types, suggesting possible gene duplications. We have now isolated two oxytocin-like hormones from the pituitary of the spotted dogfish Scyliorhinus caniculus (suborder Galeoidei). Microsequencing as well as chromatographic and pharmacological comparisons with synthetic peptides show that these peptides are Asn4,Val8oxytocin (asvatocin) and Phe3,Asn4,Val8-oxytocin (phasvatocin). Asvatocin and phasvatocin display oxytocic activity on rat uterus, about 80 and 5 milliunits per nmol, respectively, and virtually no pressor activity on anesthetized rats. They occur in roughly equal molar amounts in the gland; vasotocin is also present in a proportional amount that is lower by about a factor of 20. In addition to the duality, conservative amino acid substitutions are observed in the two oxytocic peptides in positions 4 (Gln-4-->Asn) and 8 (Leu-8-->Val), when compared with oxytocin. Furthermore, replacement of the isoleucine residue found in position 3 of all other oxytocin-like hormones by phenylalanine in phasvatocin is exceptional; it determines a dramatic decrease of the oxytocic activity. Preservation of the C-terminal-amidated nonapeptide pattern in the 12 vertebrate neurohypophysial hormones known to date suggests that both precursors and processing enzymes have coevolved tightly. On the other hand, whereas the great evolutionary stability of the mature hormones (generally observed in vertebrates) suggests a strict messenger-receptor coevolution, the exceptional diversity found in cartilaginous fishes (six oxytocin-like peptides identified out of eight known) might be due to a looseness of selective constraints, perhaps in relationship with their specific urea osmoregulation.
|
| 7979397 |
Generation of hydroxyl radicals during dismutation of superoxide by SOD model compounds |
10.1006/abbi.1994.1488. |
Arch Biochem Biophys |
Generation of hydroxyl radicals during dismutation of superoxide by SOD model compounds
Abstract
- The reactivities of copper(II) complexes with cimetidine (Cim) and cyclo(histidylhistidyl) (CyHH), both of which are SOD model compounds, toward active oxygen species such as superoxide (O2-) and hydrogen peroxide (H2O2) were investigated by electron spin resonance-spin trapping and thiobarbituric acid methods. At physiological pH values, low concentrations of Cu(II) complexes (0.025 mM) with Cim and CyHH could scavenge O2-, but high concentrations of these compexes (0.25 mM) yielded hydroxyl radicals (.OH) during dismutation of O2-. These Cu(II) complexes could directly react with H2O2 to yield .OH. From these results, it is indicated that .OH formed during the dismutation of O2- by high concentration of SOD model compounds may be caused by the reaction of H2O2 generated form dismutation of O2- with Cu(II) complexes. Further, DNA single-stranded breakage was observed during the reactions of H2O2 with these Cu(II) complexes.
|
| 7983039 |
Two naturally occurring mutations in the kinase domain of insulin receptor accelerate degradation of the insulin receptor and impair the kinase activity |
None |
J Biol Chem |
Two naturally occurring mutations in the kinase domain of insulin receptor accelerate degradation of the insulin receptor and impair the kinase activity
Abstract
- We identified two novel heterozygous missense mutations of the insulin receptor gene: the Asp1179 mutation in one family and the Leu1193 mutation in two unrelated families with extreme insulin resistance. In these patients, the number of insulin receptors on the cell surface was found to be markedly decreased by insulin binding and surface labeling studies in transformed lymphocytes. Insulin binding to the transfected COS 7 cells and Rat-1 cells with both mutant cDNAs was also decreased to 5-31% of normal, and the mutant insulin receptors showed a markedly decreased kinase activity. Although biosynthetic labeling studies revealed that both mutant receptors were synthesized as 190-kDa proreceptors, the degradation of the mutant proreceptors was 2-fold faster than that of the wild type proreceptors. However, the degradation rate of the mutant receptors on the cell surface was comparable to that of wild type insulin receptor. These results suggest that the Asp1179 and Leu1193 mutations in the kinase domain are unique in causing decreased insulin receptor number on the cell surface by accelerated intracellular degradation, and that insulin resistance in these patients is mainly due to the decreased receptor number rather than impaired kinase activity.
|
| 7987372 |
Arg8vasotocin excites neurones in the dorsal vagal complex in vitro: evidence for an action through novel class(es) of CNS receptors |
10.1111/j.1365-2826.1994.tb00602.x. |
J Neuroendocrinol |
Arg8vasotocin excites neurones in the dorsal vagal complex in vitro: evidence for an action through novel class(es) of CNS receptors
Abstract
- Using extracellular recordings from brainstem slices in vitro, it was demonstrated that a high proportion (38/56) of neurones in the dorsal vagal complex of dioestrus, virgin female rats exhibit an excitatory response to [Arg8]-vasotocin (AVT). Pharmacological characterization suggests that these responses cannot be entirely explained by interaction with either of the currently known classes of central receptors for oxytocin (OT) and vasopressin (V1a). Comparison of the responses with those to the OT receptor-specific agonist [Thr4,Gly7]-OT (TGOT), showed that not all neurones that responded to TGOT also responded to AVT (3/27). Furthermore, while the effects of 10(-7) M TGOT could be blocked either by the broad-spectrum antagonist d(CH2)5[d-Tyr(OEt)2,Val4,Cit8]-vasopressin or by the selective OT receptor antagonist d(CH2)5[Tyr(Me)2,Thr4,Orn8,Tyr-NH2(9)]-vasotocin, these peptides did not completely block the responses to AVT, indicating that AVT is unlikely to act through the central OT receptor. The responses to AVT and [Arg8]-vasopressin (AVP) indicated the presence of at least 2 classes of receptor with which these agonists could act. Of 42 neurones tested with both AVP and AVT, responded to AVP in the absence of a response to AVT, while 7/42 responded to AVT without a response to AVP. This might be explained by AVP acting through only the V1 receptor, while AVT acts through both the V1 and its own novel class of receptor. This was substantiated by the fact that two OT/V1 receptor antagonists, d(CH2)5[d-Tyr(OEt)2,Val4,Cit8]-VP and d(CH2)5[Tyr(Me)2,Tyr-NH2(9)]-AVP, were unable to block completely all the responses to AVT at a dose which suppressed responses to both AVP and TGOT.(ABSTRACT TRUNCATED AT 250 WORDS)
|
