MicroRNA-590-5p suppresses the proliferation and invasion of non-small cell lung cancer by regulating GAB1.

OBJECTIVE: Some specific microRNAs (miRNAs) have been identified to regulate the tumorigenesis of non-small cell lung cancer (NSCLC). MiR-590-5p was found to involve in the carcinogenesis of human cancers. This study aims at exploring the role of miR-590-5p in the pathogenesis of NSCLC. PATIENTS AND METHODS: The expressions of miR-590-5p and GAB1 were measured by quantitative Real-Time Polymerase Chain Reaction (qRT-PCR) and Western blot, respectively. The biological functions of miR-590-5p and GAB1 on cell viability and invasion were investigated through MTT and transwell assays. The binding site between miR-590-5p and GAB1 was verified by dual-luciferase reporter gene assay (DLR). RESULTS: MiR-590-5p expression was downregulated in NSCLC. MiR-590-5p overexpression inhibited the proliferation and invasion of NSCLC cells. Furthermore, miR-590-5p was confirmed to directly target GAB1. GAB1 knockdown had the same effect as overexpression of miR-590-5p in NSCLC. Moreover, overexpression of GAB1 partially reversed the suppressive effect of miR-590-5p on NSCLC. CONCLUSIONS: MiR-590-5p suppressed cell proliferation and invasion of NSCLC by inhibiting GAB1 expression, indicating that miR-590-5p was a suppressive miRNA in NSCLC.

Eight polymorphic microsatellite markers for the spotted babylon, Babylonia areolata (Buccinidae).

The spotted babylon, Babylonia areolata, is one of the most extensively cultured marine mollusks in southeast Asia. Eight polymorphic microsatellite markers were developed for this species, from a microsatellite-enriched library. These markers, characterized in 32 individuals from a hatchery population, were polymorphic, with allele numbers ranging from 6 to 18 per locus, expected and observed heterozygosities ranging from 0.68 to 0.94 and 0.56 to 0.81, respectively. One locus (HUBA09) showed significant deviation from Hardy-Weinberg equilibrium, probably due to the presence of null alleles. These microsatellite loci should be useful for future population genetic studies and marker-assisted breeding in this species.

Development and characterization of 60 microsatellite markers in the abalone Haliotis diversicolor.

The abalone, Haliotis diversicolor, is one of the most important mariculture species in southern China. We developed 60 new polymorphic microsatellite markers for H. diversicolor and characterized them in 30 individuals from a cultured population in Sanya, China. All 60 markers were found to be polymorphic. The number of alleles ranged from two to nine per locus, with an average of 4.12/locus. The expected and observed heterozygosities ranged from 0.10 to 0.88 and from 0.07 to 0.87, respectively. Forty-four loci were in Hardy-Weinberg equilibrium. These 44 microsatellite markers should be useful for genome mapping and population genetic studies.

Somatostatin receptor subtype 3 mediates the inhibitory action of somatostatin on gastric smooth muscle cells.

Previous functional studies show that somatostatin (SS) interacts with specific receptors to inhibit relaxation in gastric smooth muscle cells. There are no ligand binding studies, and it is unknown which of the five subtypes of SS receptors mediates the action. Dispersed gastric smooth muscle cells from guinea pig bound both 125I-labeled SS-14 and 125I-D-Phe-Cys-Tyr-D-Trp-Lys-Thr-Cys-Nal-NH2 (where Nal indicates N-naphthylalanine) (cyclo-SS-8), a synthetic peptidase-resistant octapeptide SS analogue. SS-28 and SS-14, cyclo-SS-8, and SS analogue D-Phe-Cys-Phe-D-Trp-Lys-Thr-Cys-Thr-ol [SMS-(201-995) (octreotide)] inhibited 125I-cyclo-SS-8 binding with relative potencies of SS-28 = cyclo-SS-8 = SMS-(201-995) (octreotide), and the binding was not affected by the addition of protease inhibitors. SS-14 caused inhibition only in the presence of protease inhibitors. Ligand analysis demonstrated a two-binding-site model. Analysis of the relationship between biological function and binding suggested the high-affinity sites mediated the relaxant action of SS. 5'-Guanylylimidodiphosphate [Gpp-(NH)p] inhibited binding by reducing the affinity of the high-affinity site. Six SS-8 analogues that distinguish SS subtypes showed that 125I-SS-14 bound to somatostatin receptor subtype 3 (SSTR3). The results demonstrated that gastric smooth muscle cells possess distinct receptors for SS of the SSTR3 subtype. Occupation of these sites inhibits relaxation in gastric smooth muscle cells. Modulation between the high- and low- affinity binding states of SSTR3 is at least partially mediated by activation of guanine nucleotide regulatory proteins.

Interaction of galanin fragments with galanin receptors on isolated smooth muscle cells from guinea pig stomach: identification of a novel galanin receptor subtype.

From structure-function studies it has been proposed that two subtypes of receptors may mediate galanin's actions in the gastrointestinal tract and other tissues and their effects can be either direct or neurally mediated. We have recently demonstrated that isolated gastric smooth muscle cells possess high-affinity galanin receptors, activation of which increases AMP and causes relaxation. Because this cell system contains no neural elements, contains a single class of galanin receptors and allows binding to be correlated with function, it is a good system to investigate peptide requirements for cell activation. Porcine galanin (p-Gal) and rat galanin (r-Gal) were equipotent to the NH2-terminal fragments r,p-Gal(1-10), r,p-Gal(1-15), r,p-Gal(1-20), p-Gal(2-29) and p-Gal(3-29) at inhibiting binding of 125I-galanin to gastric smooth muscle cells from guinea pig (Kd 5-8 nM). The midmolecule fragment p-Gal(9-25) and the long COOH-terminal fragment r-Gal(9-29) were equipotent and 25-fold less potent than p-Gal. Acetylation of r-Gal(9-29) increased potency to that of p-Gal. The short COOH-terminal fragment, p-Gal(21-29) and r-Gal(21-29), had very low affinity (Kd 3 microM). Each peptide alone (1 microM) caused no effect on cell length, but inhibited carbachol-induced contraction. The inhibition was 81% to 92% for r-Gal or p-Gal, r,p-Gal(1-10), r,p-Gal(1-15), r,p-Gal(1-20), p-Gal(2-29), p-Gal(3-29) and Ac-r-Gal(9-29); 47% for p-Gal(9-25) and r-Gal(9-29); and 16% to 17% for p-Gal(21-29).(ABSTRACT TRUNCATED AT 250 WORDS)

A ten-year observation on experimental infection of periodic Brugia malayi in man.

This paper reports the results of 10 years of observations on the clinical manifestations, pathology and immunity to filariasis and aetiological biology of filariae in three volunteers (first author and his family members) who were inoculated experimentally with infective larvae of periodic Brugia malayi in 1981. The changes in clinical symptoms and signs were recorded systematically. Microfilariae were first detected at 41 and 46 weeks after inoculation in two subjects and remained detectable in small numbers until 8-8.5 years after infection. The microfilarial density fluctuated at 1-2 mf 120 microliters-1. Thereafter no microfilariae were detected in 12 blood sample examinations, suggesting that the adult reproductive period of periodic B. malayi could last up to 8-9 years in the human body. Eosinophilia occurred mainly before and at the initial stage of microfilaraemia. An increase in the lymphocytes was observed to some extent at 2-156 weeks after infection. Biopsy at the inoculation site 6 weeks after inoculation showed infiltration of the lymph node by inflammatory cells, mainly eosinocytes, lymphocytes and monocytes. Lymphangiectasis and lymphostasis were observed in both limbs and pelvic regions by lymphangiogram taken 11 weeks after inoculation. Antibodies against B. malayi first appeared at 2-5 weeks after infection, peaked at 12-56 weeks and thereafter declined gradually. Subjects A and C became antibody free but subject B remained positive to antibody against B. malayi 10 years after infection. E-rosette forming lymphocytes became lower than normal at 11 weeks and recovered to normal within 10 years after infection.

Smooth muscle cells from guinea pig stomach possess high-affinity galanin receptors that mediate relaxation.

Galanin-like immunoactivity occurs in nerves and plexi in muscle layers throughout gastrointestinal tract including the stomach. Galanin can affect gastric emptying and contraction or relaxation of gastric muscle in different species. The aim of this study was to investigate the direct effect of galanin on dispersed gastric smooth muscle cells and to characterize any galanin receptors that mediated any effect. Dispersed gastric smooth muscle cells were prepared from guinea pig stomach by collagenase digestion. Porcine galanin (p-galanin; 1 microM) did not stimulate contraction when present alone; however, p-galanin (1 microM) inhibited carbachol-induced contraction with a half-maximal effect at 7 nM. p-Galanin (1 microM) increased cellular adenosine 3',5'-cyclic monophosphate (cAMP) content by 10 s and caused a maximal increase of 80% over basal. 125I-galanin (porcine) bound to dispersed cells in a time- and temperature-dependent manner. Binding was saturable, reversible, and specific. Binding of 125I-galanin was inhibited almost equally by porcine and rat galanin (Ki = 6-8 nM) but was not inhibited by the galanin-associated peptide [preprogalanin-(108-123)]. The fragment galanin-(1-16) was equally potent to rat galanin; however, the fragment galanin-(9-29) was 56-fold less potent (Ki = 370 nM). Computer analysis demonstrated there were two binding sites for p-galanin on gastric smooth muscle cells, a high-affinity site (Kd = 2.6 nM) with low capacity (Bmax = 175 fmol/mg protein) and a low-affinity site (Kd = 150 nM) with large capacity (Bmax = 3,611 fmol/mg protein).(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric smooth muscle cells possess two classes of endothelin receptors but only one alters contraction.

Endothelin (ET)-like immunoreactivity and ET binding sites are widely distributed in the gastrointestinal tract, and ET causes contraction of stomach muscle strips. To determine whether ETs could interact with gastric smooth muscle cells directly and alter function, we measured binding of 125I-ET-1, 125I-ET-2, and 125I-ET-3 to dispersed gastric smooth muscle cells from guinea pig and their abilities to alter cell length. Each ligand bound in a time- and temperature-dependent manner, which was specific and saturable. Analysis of the dose-inhibition curves of both ET-1 and ET-3 for binding of each ligand indicated the presence of two classes of receptors, one class (ETA receptor) with a high affinity for ET-1 and ET-2 but a low affinity for ET-3, and the other (ETB receptor) with a high affinity for ET-1, ET-2, and ET-3. The ligands were rapidly internalized by both receptors; however, it was greater with ETA receptors. ET-1 stimulated muscle contraction (50% effective concentration approximately 2 nM), whereas ET-3 did not stimulate contraction or cause relaxation. These results demonstrate that gastric smooth muscle cells possess two classes of ET receptors. One type (ETA) has a high affinity for ET-1 and ET-2 and a low affinity for ET-3, and receptor occupation results in rapid ligand internalization and muscle contraction; the other type (ETB) has a high affinity for ET-1, ET-2, and ET-3, and receptor occupation results in a lesser degree of ligand internalization than the ETA receptor and does not alter contractile behavior.

Characterization of somatostatin receptor subtypes controlling rat gastric acid and pancreatic amylase release.

An examination of the binding characteristics of a large number of somatostatin analogues with respect to the five known somatostatin receptor subtypes has recently resulted in the discovery of several peptides with some selectivity for types 2, 3, and 4 and little affinity for type 1 or 5 receptor. A panel of these peptides has thus far implicated type 2 receptors in the inhibition of release of pituitary growth hormone and type 4 receptors in inhibiting pancreatic insulin release. In the present article, we have examined the inhibitory effects of the same group of peptides on in vivo rat gastric acid and pancreatic amylase release and binding to rat pancreatic acinar cells. The type 2-selective ligand NC-8-12 was a potent inhibitor of gastric acid release (EC50s in the 1.5 nM region) whereas the type 4-selective ligand, DC-23-99, elicited little response. However, some involvement of type 3 receptors could not be ruled out because the type 3-selective analogue, DC-25-20, exhibited inhibitory effects at higher dose levels (EC50 > 10 nM). Conversely, the type 4 analogue was a potent inhibitor of amylase release (EC50 1.1 nM) whereas the type 3 analogue had no significant effects at doses tested. DC-23-99 also bound with high affinity to rat acinar cells (EC50 3.8 nM), whereas DC-25-20 exhibited more than 10-fold less affinity. Thus, these two major biological functions of somatostatin appear to be controlled by different receptors and, furthermore, effects on both endocrine and exocrine pancreas appear to be type 4 receptor mediated.

Galanin-induced relaxation in gastric smooth muscle cells is mediated by cyclic AMP.

Galanin has numerous effects on gastrointestinal motility in different species; however, its cellular basis of action in mediating these effects is unclear. Dispersed gastric smooth muscle cells have been shown to possess high-affinity galanin receptors that increase cAMP and cause relaxation. Recent studies show some smooth muscle relaxants such as VIP cause relaxation by both cAMP-dependent and -independent mechanisms. It is unknown if galanin's cellular basis of relaxation is similar or different from that of VIP. To investigate galanin's relaxant effect and compare it to VIP's effect, dispersed smooth muscle cells from guinea pig stomach were prepared by collagenase digestion. The mean length in resting cells was 110 +/- 2 microns and, with carbachol treatment, contracted to 89 +/- 2 microns. VIP and galanin alone had no effect on cell length, but each caused a dose-dependent inhibition of carbachol-induced contraction and both had an EC50 of 3-7 nM. Galanin (1 microM) and VIP (1 microM) increased cellular cAMP from 118 +/- 10 pmol/10(6) cells in control to 212 +/- 14 and 214 +/- 12 pmol/10(6) cells, respectively. The protein kinase A inhibitor, Rp-cAMPS, at 100 microM, completely inhibited the relaxant effect of an EC50 concentration of galanin (3 nM), but only inhibited that by VIP by 80% (p < 0.05). Adding the nitric oxide inhibitor, L-NNA (NG-nitro-L-arginine), at 100 microM did not alter the length of resting cells or inhibit carbachol-induced contraction. However, L-NNA (100 microM) decreased VIP-induced relaxation by 45%, whereas it had no effect on galanin-induced relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)

Chimeric galanin analogs that function as antagonists in the CNS are full agonists in gastrointestinal smooth muscle.

Galanin has numerous effects on gastrointestinal smooth muscle. However, because of the lack of specific inhibitors, it is not known which are physiological and which are pharmacological. This study investigates the ability of two chimeric galanin analogs, [# 1-galantide = (M-15) = [galanin (1-13)-substance P(5-11)] and #2-M-35[galanin(1-13)bradykinin (2-9)], which were recently reported to function as galanin-receptor antagonists in the CNS, to interact with galanin receptors on rat jejunal muscle strips or dispersed smooth muscle cells from guinea pig stomach. In both systems each chimeric analog had agonist activity and was as efficacious as galanin. Cross-desensitization experiments demonstrated that in the jejunal muscle strips, both chimeric analogs were causing muscle contraction by interacting with the galanin receptor. In dispersed smooth muscle cells, galanin, as well as each chimeric analog, caused muscle relaxation, whereas substance P and bradykinin both caused muscle contraction. Each chimeric analog was equipotent to galanin in inhibiting binding of 125I-galanin, and there was close agreement between their abilities to occupy the galanin receptor and cause relaxation. Each chimeric analog also activated adenylate cyclase and increased cAMP characteristic of relaxants. These studies demonstrate these chimeric analogs will not be useful for defining the physiological role of galanin in altering gastrointestinal motility, because they function as full galanin-receptor agonists instead of as galanin-receptor antagonists.

Structural analysis of CGRP receptors on gastric smooth muscle and pancreatic acinar cells.

Calcitonin gene-related peptide (CGRP) immunoreactivity is widely distributed in the central nervous system and gastrointestinal (GI) tract, and specific receptors have been described on many GI tissues. In the present study, we compared CGRP receptors on gastric smooth muscle cells with those on pancreatic acini from guinea pig with the use of chemical cross-linking techniques combined with various enzymatic digestions. 125I-labeled rat CGRP-I demonstrated temperature-dependent saturable binding to both acinar and gastric smooth muscle cell membranes. After binding, membranes were incubated with 1 mM disuccinimidyl suberate (DSS), solubilized with sodium dodecyl sulfate (SDS), and subjected to SDS-polyacrylamide gel electrophoresis. Cross-linked radioactivity was analyzed by autoradiography. A single broad radioactive band [molecular weight (M(r)) 57,000] was seen on cell membranes from both tissues and after cross-linking to intact cells. These bands were not altered by addition of dithiothreitol. This radioactive band was not detected without DSS present or with addition of 10 microM rCGRP-I. rCGRP-I inhibited cross-linking with half-maximal inhibition of 32 nM with membranes from both tissues, and there was a close correlation between its ability to inhibit binding and to inhibit cross-linking. Cross-linking was not inhibited by non-CGRP related peptides. With membranes from both tissues, N-glycanase digestion increased the mobility of the original band. Neuraminidase digestion only slightly increased the mobility of the original band; however, the subsequent addition of O-glycanase showed no additional effect on both membranes. Endoglycosidase H digestion had no effect in either tissue. The present results demonstrate that on both tissues the cell membrane receptor for CGRP is an N-linked sialoglycoprotein. The apparent M(r) of this sialoglycoprotein is 57,000, and this polypeptide does not contain disulfide-linked subunits or O-linked carbohydrates.

Neutral endopeptidase (EC 3.4.24.11) modulates the contractile effects of neuropeptides on muscle cells from the guinea-pig stomach.

The objectives of this investigation were to characterize neuropeptide-degrading enzymes on the surface of gastric muscle cells and to determine their physiological function. Neutral endopeptidase (NEP, EC 3.4.24.11) activity was measured using the fluorogenic substrate glutaryl-Ala-Ala-Phe-4-methoxy-2-naphthylamine. The NEP inhibitors phosphoramidon and DL-thiorphan (1 microM) inhibited degradation of the substrate by gastric muscle membranes by 100% and by freshly dispersed gastric muscle cells by 55-60%. The phosphoramidon or DL-thiorphan-inhibitable activity, attributed to NEP, of membranes was 112 +/- 4.0 pmol h-1 (micrograms protein)-1 and of cells was 4.2 +/- 0.8 nmol h-1 (10(6) cells)-1. This activity was associated with membranes prepared from cells and was not detected in the cytoplasm or in the cell incubation solution. Gastric muscle membranes were fractionated by electrophoresis and analysed by Western blotting using two NEP antisera. Both antisera recognized a protein in membranes with an electrophoretic mobility identical to that of recombinant human NEP and an apparent molecular mass of approximately 95 kDa. Neuropeptides were degraded by membranes with specific activities in the order of [Leu5]enkephalin > [Met5]enkephalin > gastrin-releasing peptide-10 (GRP-10) > [D-Ala2][Leu5]enkephalin > somatostatin-14. Phosphoramidon and DL-thiorphan similarly inhibited the degradation of GRP-10 (mean of 35% inhibition), somatostatin-14 (57%) and the aminopeptidase-resistant analogue, [D-Ala2][Leu5]enkephalin (75%). When aminopeptidases were inhibited with amastatin (10 microM) phosphoramidon inhibited degradation of [Leu5]enkephalin (54%) and [Met5]enkephalin (100%). Phosphoramidon increased the potency of the contractile effects of neuropeptides on muscle cells by > 280-fold for somatostatin-14, 17-fold for GRP-10, 18-fold for [Met5]enkephalin and 14-fold for [Leu5]enkephalin. The results show that an NEP-like enzyme on the surface of gastric muscle cells degrades and inactivates enkephalins, GRP-10 and somatostatin-14 and acts in a manner analogous to that of acetylcholinesterase in the neuromuscular junction of skeletal muscle.

Effect of human growth hormone on the proliferation of human fetal islet cells in vitro.

In this study it was shown that 1000 micrograms/L hGH in serum-free medium promoted the attachment, spreading and formation of monolayer of islet cells. The radioactivity test indicated that hGH significantly stimulated the DNA synthesis of islet cells (P < 0.001). Furthermore, after 48 h exposure to hGH (1000 micrograms/L), both the insulin contents and release of islet cells significantly increased (P < 0.001); hGH also enhanced the responsiveness of fetal islet cells to high-concentration glucose plus theophylline stimulation (P < 0.001). However, the effect of hGH in the medium containing 10% newborn calf serum was not so prominent in comparison with that in the serum-free medium. The morphologic assay for mitotic cells showed a combination of 1000 micrograms/L hGH and 10% serum was the most efficient for inducing the mitosis, the mitotic index being 5.95%. We conclude that hGH is an important growth factor for human islet cells.

A primary role for protein kinase A in smooth muscle relaxation induced by adrenergic agonists and neuropeptides.

Many studies suggest that smooth muscle relaxation caused by beta-adrenergic agents and various neuropeptides occurs as a result of an increase in cellular adenosine 3',5'-cyclic monophosphate (cAMP). However, the evidence is indirect, and furthermore does not demonstrate that an increase in cAMP is essential for mediating relaxation. To define more clearly the role of cAMP in receptor-mediated smooth muscle relaxation, we used a specific competitive antagonist of the action of cAMP on protein kinase A, (R)-p-adenosine 3',5'-cyclic phosphorothioate [(R)-p-cAMPS], and its S isomer, (S)-p-cAMPS, which functions as a cAMP agonist. In gastric smooth muscle cells from guinea pig, (S)-p-cAMPS caused a dose-related relaxation [50% inhibitory concentration (IC50) 86 +/- 59 nM]. Vasoactive intestinal peptide (VIP) produced smooth muscle cell relaxation (IC50 2.3 +/- 0.8 nM) through occupation of specific VIP receptors. (R)-p-cAMPS inhibited VIP-induced relaxation, with a rightward shift in the VIP dose-response curve, suggesting competitive antagonism. Furthermore, (R)-p-cAMPS inhibited relaxation induced by other agents that increase cellular cAMP (isoproterenol, calcitonin gene-related peptide, and glucagon) but not that induced by ATP or sodium nitroprusside. (R)-p-cAMPS had no effect on contraction stimulated by carbachol, cholecystokinin, or substance P. These data demonstrate that activation of protein kinase A is primarily responsible for mediating gastrin smooth muscle relaxation produced by adrenergic agents and various neuropeptides.

Characterization of opioid receptors on smooth muscle cells from guinea pig stomach.

On the basis of opioid-stimulated contraction of dispersed gastric smooth muscle cells it has been suggested that these cells possess opioid receptors of three subtypes: kappa (kappa), mu (mu), and delta (delta). We have used selective peptidase-resistant radioligands, agonists and antagonists, to examine receptor subtypes on dispersed gastric smooth muscle cells from guinea pigs prepared by collagenase digestion. The kappa-agonist U-50488H, the mu-agonist [D-Ala2,N-Me-Phe4,Gly5-ol]enkephalin (DAGO), and the delta-agonist [D-Pen2,Pen5]enkephalin (DPDPE) each caused muscle contraction. The concentrations required to caused half-maximal contraction were U50488H (6 pM) greater than DAGO (13 pM) greater than DPDPE (6 nM). The abilities of these agonists to inhibit binding of [3H]U-69593 (kappa-preferring) by 50% were U50488H (43 nM) greater than DAGO (43 microM) greater than DPDPE (200 microM). Their abilities to inhibit binding of [3H]naloxone (mu-preferring) by 50% were DAGO (0.2 microM) greater than U50488H (10 microM) greater than DPDPE (greater than 100 microM). No binding could be detected with the delta-selective ligand [3H]DPDPE. The kappa-preferring antagonist Mr2266 (10 nM) preferentially inhibited contraction stimulated by the kappa-agonist U50488H, and naltrexone (10 nM) (mu-selective antagonist) preferentially inhibited contraction stimulated by the mu-agonist DAGO. ICI 174864 (200 microM; delta-selective antagonist) had no effect on contraction stimulated by mu-, kappa-, or delta-agonists. Contraction stimulated by the delta-agonist DPDPE was inhibited by both kappa- and mu-receptor antagonists. Studies on the effect of the antagonists on binding of [3H]naloxone and [3H]U69593 also provided evidence for kappa- and mu-sites but nor for delta-sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Actions of somatostatins on gastric smooth muscle cells.

The effects of somatostatin-28, somatostatin-14, and a synthetic somatostatin octapeptide analogue, D-Phe-Cys-Tyr-D-Trp-Lys-Thr-Cys-Nal-NH2 (cyclo SS-8) were examined on contraction of dispersed gastric smooth muscle cells from guinea pigs. The somatostatins did not cause contraction of gastric smooth muscle cells, nor did they inhibit carbachol-stimulated contraction. However, they reversed vasoactive intestinal peptide (VIP)-induced inhibition (relaxation) of carbachol-stimulated contraction. Somatostatin-28 had a half-maximal effect (EC50) at 1.6 +/- 0.8 nM, cyclo SS-8 at 0.6 +/- 0.3 nM, but somatostatin-14 had no effect even when used in concentrations as high as 1 microM. Incubation of muscle cells with peptidase inhibitors phosphoramidon (1 microM) plus amastatin (10 microM) had no effect on the EC50 of somatostatin-28 or cyclo SS-8 but increased the potency of somatostatin-14 greater than 1,000-fold. When peptides were incubated with muscle cells and the products applied to high-performance liquid chromatography, cyclo SS-8 was not degraded, but somatostatin-14 was rapidly degraded when present alone, and the addition of peptidase inhibitors partially inhibited the degradation. Cyclo SS-8 had its maximal effect at 0.5-1 min and inhibited relaxation induced by VIP, isoproterenol, glucagon, or dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP). Cyclo SS-8 partially inhibited the increase in VIP-stimulated cAMP. Preincubation with pertussis toxin blocked the inhibitory action of cyclo SS-8 on VIP or DBcAMP-induced relaxation. These results indicate that gastric smooth muscle cells rapidly degrade somatostatin-14 and suggest that muscle cell peptidases could have a major effect on the actions of somatostatin-14.(ABSTRACT TRUNCATED AT 250 WORDS)

Observations on experimental infection of periodic Brugia malayi in man.

Three volunteers were inoculated with different numbers of infective larvae of periodic Brugia malayi from an artificially infected Meriones unguiculatus. At different times after inoculation, the volunteers developed clinical manifestations such as chills, fever, cough, asthma, skin itching, edema, adenolymphangitis and eosinophilia. Microfilaremia was first detected at 41 and 46 weeks after inoculation in two subjects. At 11 weeks, the percentage of E-rosette forming lymphocytes in these subjects was below the normal level. Specific antibody was first detected in three volunteers at 2, 3 and 5 weeks after inoculation, respectively, and increased to various extent at 12-16 weeks, but decreased in varying degrees at 44-56 weeks. The results also showed that antibody titres fluctuated at different periods of infection.