scholarly journals Insect cardioactive peptides. I. Distribution and molecular characteristics of two cardioacceleratory peptides in the tobacco hawkmoth, Manduca sexta

1985 ◽  
Vol 114 (1) ◽  
pp. 365-379 ◽  
Author(s):  
N. J. Tublitz ◽  
J. W. Truman
Keyword(s):  
Manduca Sexta ◽  
Isolated Heart ◽  
Gel Filtration ◽  
Biochemical Properties ◽  
Molecular Characteristics ◽  
Molecular Weights ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Pharate Adult

Using an in vitro heart bioassay, the pharmacological and biochemical properties of two cardioactive peptides derived from neural tissues of the moth, Manduca sexta, were analysed. Gel filtration of ventral nerve cords (VNC) from pharate adults identified two cardioacceleratory peptides (CAP1 and CAP2) with apparent molecular weights of 1000 and 500 Da, respectively. Both CAPs were localized to the abdominal perivisceral organs, the major neurohaemal release sites in the insect VNC. Pulse application of CAP1 or CAP2 on the in vitro Manduca heart produced a dose-dependent increase in rate but had no effect on beat amplitude. The threshold dose for the action of each peptide on the isolated heart bioassay was less than 0.05 abdominal nerve cord equivalents. Both CAPs were present in the pharate adult VNC of several other Lepidopteran species. Neither CAP1 nor CAP2 was detected in the prepupal VNC of Manduca sexta.

scholarly journals Insect cardioactive peptides. II. Neurohormonal control of heart activity by two cardioacceleratory peptides in the tobacco hawkmoth, Manduca sexta

1985 ◽  
Vol 114 (1) ◽  
pp. 381-395 ◽  
Author(s):  
N. J. Tublitz ◽  
J. W. Truman
Keyword(s):  
Heart Rate ◽  
Manduca Sexta ◽  
Gel Filtration ◽  
Dependent Manner ◽  
Heart Activity ◽  
High Potassium ◽  
Calcium Dependent ◽  
Dose Dependent Increase ◽  
Dose Dependent

The physiological characteristics of two cardioacceleratory peptides (CAPs) were analysed in the tobacco hawkmoth, Manduca sexta, to determine if either CAP functioned as a cardioregulatory neurohormone. In vivo heart recordings from pharate and newly emerged adults revealed a dramatic increase in heart rate associated with wing-spreading behaviour. Bioassay of whole blood taken from wing-spreading (WS) animals indicated the presence of a stage-specific, blood-borne cardioacceleratory factor(s). Gel filtration of WS blood identified two cardioacceleratory factors which co-eluted with the two CAPs. A depletion of the ventral nerve cord levels of both CAPs was observed during WS behaviour. Measurements of blood CAP levels showed that the peak CAP titres were coincident with the initiation of WS behaviour. Experimental manipulations that delayed the onset of WS behaviour also prevented CAP release. High potassium incubation evoked the release of both CAPs in a calcium-dependent manner. In vivo injections of CAP1 or CAP2 caused a dose-dependent increase in heart rate. These results confirm the hypothesis that both CAPs function as cardioregulatory neurohormones during wing-spreading behaviour in Manduca sexta.

Soluble Thrombomodulin Purified from Human Urine Exhibits a Potent Anticoagulant Effect In Vitro and In Vivo

1995 ◽  
Vol 73 (05) ◽  
pp. 805-811 ◽  
Author(s):  
Yasuo Takahashi ◽  
Yoshitaka Hosaka ◽  
Hiromi Niina ◽  
Katsuaki Nagasawa ◽  
Masaaki Naotsuka ◽  
...  
Keyword(s):  
Human Urine ◽  
Specific Activity ◽  
Anticoagulant Activity ◽  
Rabbit Lung ◽  
Soluble Thrombomodulin ◽  
Molecular Weights ◽  
Dose Dependent Fashion ◽  
Dose Dependent

SummaryWe examined the anticoagulant activity of two major molecules of soluble thrombomodulin purified from human urine. The apparent molecular weights of these urinary thrombomodulins (UTMs) were 72,000 and 79,000, respectively. Both UTMs showed more potent cofactor activity for protein C activation [specific activity >5,000 thrombomodulin units (TMU)/mg] than human placental thrombomodulin (2,180 TMU/mg) and rabbit lung thrombomodulin (1,980 TMU/mg). The UTMs prolonged thrombin-induced fibrinogen clotting time (>1 TMU/ml), APTT (>5 TMU/ml), TT (>5 TMU/ml) and PT (>40 TMU/ml) in a dose-dependent fashion. These effects appeared in the concentration range of soluble thrombomodulins present in human plasma and urine. In the rat DIC model induced by thromboplastin, administration of UTMs by infusion (300-3,000 TMU/kg) restored the hematological abnormalities derived from DIC in a dose-dependent fashion. These results demonstrate that UTMs exhibit potent anticoagulant and antithrombotic activities, and could play a physiologically important role in microcirculation.

scholarly journals Complexing of the CD-3 subunit by a monoclonal antibody activates a microtubule-associated protein 2 (MAP-2) serine kinase in Jurkat cells

1989 ◽  
Vol 262 (2) ◽  
pp. 449-456 ◽  
Author(s):  
C Hanekom ◽  
A Nel ◽  
C Gittinger ◽  
A Rheeder ◽  
G Landreth
Keyword(s):  
T Cells ◽  
Time Course ◽  
Gel Filtration ◽  
Maximal Activity ◽  
Jurkat Cells ◽  
Serine Kinase ◽  
Transient Activation ◽  
Normal Human ◽  
Dose Dependent

Treatment of Jurkat T-cells with anti-CD-3 monoclonal antibodies resulted in the rapid and transient activation of a serine kinase which utilized the microtubule-associated protein, MAP-2, as a substrate in vitro. The kinase was also activated on treatment of Jurkat cells with phytohaemagglutinin, but with a different time course. The activation of the MAP-2 kinase by anti-CD-3 antibodies was dose-dependent, with maximal activity observed at concentrations of greater than 500 ng/ml. Normal human E-rosette-positive T-cells also exhibited induction of MAP-2 kinase activity during anti-CD-3 treatment. The enzyme was optimally active in the presence of 2 mM-Mn2+; lower levels of activity were observed with Mg2+, even at concentrations up to 20 mM. The kinase was partially purified by passage over DE-52 Sephacel with the activity eluting as a single peak at 0.25 M-NaCl. The molecular mass was estimated to be 45 kDa by gel filtration. The activation of the MAP-2 kinase was probably due to phosphorylation of this enzyme as treatment with alkaline phosphatase diminished its activity. These data demonstrate that the stimulation of T-cells through the CD-3 complex results in the activation of a novel serine kinase which may be critically involved in signal transduction in these cells.

scholarly journals Characterization of proteins from the cytoskeleton of Giardia lamblia

1983 ◽  
Vol 59 (1) ◽  
pp. 81-103 ◽  
Author(s):  
R. Crossley ◽  
D.V. Holberton
Keyword(s):  
Molecular Weight ◽  
Sodium Dodecyl Sulphate ◽  
Giardia Lamblia ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Molecular Size ◽  
Molecular Weights

Proteins from the axonemes and disc cytoskeleton of Giardia lamblia have been examined by sodium dodecyl sulphate/polyacrylamide gel electrophoresis. In addition to tubulin and the 30 X 10(3) molecular weight disc protein, at least 18 minor components copurify with the two major proteins in Triton-insoluble structures. The most prominent minor bands have the apparent molecular weights of 110 X 10(3), 95 X 10(3) and 81 X 10(3). Protein of 30 X 10(3) molecular weight accounts for about 20% of organelle protein on gels. In continuous 25 mM-Tris-glycine buffer it migrates mostly as a close-spaced doublet of polypeptides, which are here given the name giardins. Giardia tubulin and giardin have been purified by gel filtration chromatography in the presence of sodium dodecyl sulphate. Well-separated fractions were obtained that could be further characterized. Both proteins are heterogeneous when examined by isoelectric focusing. Five tubulin chains were detected by PAGE Blue 83 dye-binding after focusing in a broad-range ampholyte gel. Giardin is slightly less acidic than tubulin. On gels it splits into four major and four minor chains with isoelectric points in the pI range from 5.8 to 6.2. The amino acid composition of the giardin fraction has been determined, and compared to Giardia tubulin and a rat brain tubulin standard. Giardins are rich in helix-forming residues, particularly leucine. They have a low content of proline and glycine; therefore they may have extensive alpha-helical regions and be rod-shaped. As integral proteins of disc microribbons, giardins in vivo associate closely with tubulin. The properties of giardins indicate that in a number of respects - molecular size, charge, stoichiometry - their structural interaction with tubulin assemblies will be different from other tubulin-accessory protein copolymers studied in vitro.

Modulating a modulator: biogenic amines at subthreshold levels potentiate peptide-mediated cardioexcitation of the heart of the tobacco hawkmoth Manduca sexta.

1994 ◽  
Vol 197 (1) ◽  
pp. 377-391 ◽  
Author(s):  
K R Prier ◽  
O H Beckman ◽  
N J Tublitz
Keyword(s):  
Cyclic Amp ◽  
Manduca Sexta ◽  
Biogenic Amine ◽  
Molecular Mechanisms ◽  
Adult Heart ◽  
The Central Nervous System ◽  
Messenger System ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Dependent Mechanism

The central nervous system of the moth Manduca sexta contains a group of myoregulatory neuropeptides, the CAPs (Cardioacceleratory Peptides), which cause a physiologically important, dose-dependent increase in heart rate during wing inflation and flight in adult moths. We report here that the response of the adult heart to a subset of the CAPs, the CAP2S, is potentiated nearly twofold in the chronic presence of subthreshold levels of the biogenic amine octopamine or near-threshold levels of the biogenic amine serotonin. Subthreshold levels of the CAP2S fail to alter the response of the heart to octopamine. We have begun to investigate the molecular mechanisms underlying this potentiation. Previous work on the adult heart has shown that the CAP2s act through an inositol-1,4,5-trisphosphate second-messenger system. Here, we demonstrate that the cardioexcitatory effects of the two amines, in contrast to those of the CAP2S, are both mediated by cyclic AMP. Application to the heart of either 10(-5) moll-1 octopamine or 10(-6)moll-1 serotonin elicits a threefold increase in intracellular cyclic AMP levels. The CAP2S have no effect on cyclic AMP levels in the heart. These results illustrate a mechanism by which the effectiveness of a neurohormone can be increased with minimal cost to the animal. In Manduca sexta, subthreshold levels of octopamine are found in the haemolymph during wing inflation and flight. Thus, it is possible that octopamine up-regulates the effects of CAP2 via a cyclic-AMP-dependent mechanism during these activities.

Stimulation of HCO3- transport in isolated proximal bullfrog duodenum by prostaglandins

1980 ◽  
Vol 239 (3) ◽  
pp. G198-G203 ◽  
Author(s):  
G. Flemstrom
Keyword(s):  
Electrical Potential ◽  
Potential Difference ◽  
Electrical Potential Difference ◽  
Morphological Examination ◽  
Minimal Concentration ◽  
Dependent Transport ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Stimulation Of

An in vitro preparation of proximal duodenum from the bullfrog transported alkali into the luminal solution (approximately 1 mueq x h-1 x cm-2) and generated a transepithelial electrical potential difference (5-10 mV, lumen negative). Transport was inhibited by 2,4-dinitrophenol (10(-5) M), CN- (5 X 10(-3) M), indomethacin (5 X 10(-5) M), and acetazolamide (5 X 10(-3) M) indicating that metabolism is required. Both alkali transport and the electrical potential difference showed a dose-dependent increase on administration of the prostaglandins E2, 16,16-dimethyl E2, and F2 alpha. The minimal concentration stimulating transport was lower with the E-type prostaglandins (10(-8) M than with F2 alpha (10(-6) M), and the former also produced greater maximal responses. In addition to metabolic-dependent transport of alkali, there was passive transmucosal migration of HCO3-, amounting to approximately 40% of basal (unstimulated) transport and sensitive to variation of the transmucosal hydrostatic pressure. Morphological examination showed that the preparation is devoid of Brunner glands. Stimulation of duodenal epithelial HCO3- transport by prostaglandins may contribute to their previously demonstrated ability to prevent duodenal ulceration.

Metabolic and Pharmacologic Interaction of Ethanol and Metronidazole in the Rat

1972 ◽  
Vol 50 (6) ◽  
pp. 476-484 ◽  
Author(s):  
H. Kalant ◽  
A. E. LeBlanc ◽  
M. Guttman ◽  
J. M. Khanna
Keyword(s):  
Incidental Finding ◽  
Repeated Administration ◽  
Volatile Material ◽  
Alcohol Dehydrogenase Activity ◽  
Liver Homogenates ◽  
Dose Dependent Increase ◽  
Dose Dependent ◽  
Concentration Curves ◽  
Central Depressant

Metronidazole, added in vitro, did not act either as an inhibitor or as a substrate for the alcohol dehydrogenase activity of rat liver homogenates. Concentration curves of ethanol and acetaldehyde in the blood after an oral dose of ethanol were not altered by pretreatment with metronidazole; in contrast, disulfiram caused marked elevation of acetaldehyde levels. When given once only, metronidazole (or possibly a metabolite of it) exerted a mild central depressant effect of its own and produced a dose-dependent increase in the intoxicant effect of ethanol. After repeated administration of metronidazole, synergism with ethanol was not seen. An incidental finding was the production of a volatile material during incubation of solutions containing NAD, which gives an acetone-like peak in gas-liquid chromatograms.

scholarly journals Effect of glucose on fermentation heat in sheep rumen fluid in vitro

1986 ◽  
Vol 56 (1) ◽  
pp. 305-311 ◽  
Author(s):  
A. Arieli
Keyword(s):  
Heat Production ◽  
High Glucose ◽  
Infinite Dilution ◽  
Rumen Fluid ◽  
Heat Production Rate ◽  
Sheep Rumen ◽  
Effect Of Glucose ◽  
Dose Dependent Increase ◽  
Dose Dependent

1. Heat production rate (H) of rumen fluid was measured in a direct calorimeter, Basal H of samples of 15 ml rumen fluid mixed with 45 ml buffer was 0.4 mW/ml rumen fluid.2. Addition of glucose (0.4–6.4 mg/sample) was followed by a dose-dependent increase in H. Maximal H was 1.1 rnW/ml and lasted up to 5 min, returning thereafter to the basal level.3. Expression of fermentation heat (Hf; kJ/mol substrate added) against glucose dose indicated an asymptotic dose response.4. Maximal Hf(at infinite dilution) agreed with stoichiometric calculations whereas minimal Hfsuggested a partial fermentation of the substrate at a high-glucose dose in the rumen environment.

scholarly journals Establishment and characterization of human B-cell lymphoma cell lines using B-cell growth factor

Blood ◽  
1990 ◽  
Vol 75 (6) ◽  
pp. 1311-1318 ◽  
Author(s):  
RJ Ford ◽  
A Goodacre ◽  
I Ramirez ◽  
SR Mehta ◽  
F Cabanillas
Keyword(s):  
Growth Factor ◽  
Cell Growth ◽  
B Cell ◽  
Cell Lines ◽  
Lymphoma Cells ◽  
B Cell Growth Factor ◽  
Hodgkin's Lymphomas ◽  
Dose Dependent Increase ◽  
Dose Dependent

B-cell non-Hodgkin's lymphomas (NHL-B) have been difficult to establish in long-term cell culture using standard techniques. We report the establishment of five representative cell lines from high grade NHL-B using B-cell growth factor (BCGF). The five NHL-B cell lines display the morphologic, immunophenotypic, genotypic, and biologic characteristics of the lymphoma cells present in the original diagnostic specimen. The cell lines showed at least a sevenfold dose- dependent increase in proliferation in vitro over background in the presence of BCGF. Other putative B-cell growth-stimulating cytokines showed no significant proliferative activity or were inhibitory in some cases. NHL-B cell lines secreted growth factor(s) into culture supernatants that mediated at least a fivefold dose-dependent increase in cell proliferation in autochthonous lymphoma cells and a 10-fold or greater stimulation in growth factor-dependent normal B cell lines in vitro. The cell lines show monoclonal rearrangements of IgH genes and nonrandom chromosomal abnormalities characteristic of NHL-B, while the expression of Epstein-Barr virus associated antigen (EBNA-I) is present in two of the five cell lines. The studies show that lineage-specific growth factors may be used to establish neoplastic B cell lines in vitro, which are important experimental systems for cellular and molecular studies in the NHL-B.

Sign in / Sign up

Export Citation Format

Share Document