THE USE OF CORTICOTROPHIN PRODUCTION BY ADENOHYPOPHYSIAL TISSUE IN VITRO FOR THE DETECTION AND ESTIMATION OF POTENTIAL CORTICOTROPHIN RELEASING FACTORS

1977 ◽  
Vol 72 (2) ◽  
pp. 187-193 ◽  
Author(s):  
JULIA C. BUCKINGHAM ◽  
J. R. HODGES
Keyword(s):  
Dose Response ◽  
Posterior Pituitary ◽  
Hypothalamic Extract ◽  
Detection And Estimation ◽  
Releasing Factors ◽  
The Many ◽  
Acth Release

SUMMARY The cytochemical assay for ACTH has been adapted into a method for the detection and determination of potential corticotrophin releasing factors. Of the many putative transmitter substances tested, only the posterior pituitary polypeptides resembled hypothalamic extracts in causing dose-related increases in both pituitary ACTH content and release. Vasotocin was the most active of the compounds studied and, unlike the vasopressins, its dose–response relationships closely resembled those of hypothalamic extracts. The increase in ACTH release induced by hypothalamic extract or vasopressin was reduced by corticosterone, cortisol or progesterone but not by testosterone or oestradiol, but the increase in pituitary ACTH content was not affected by any of these steroids.

Opiate-like naloxone-reversible actions of somatostatin given intracerebrally

1978 ◽  
Vol 56 (2) ◽  
pp. 227-231 ◽  
Author(s):  
M. Rezek ◽  
V. Havlicek ◽  
L. Leybin ◽  
F. S. Labella ◽  
H. Friesen
Keyword(s):  
Opiate Receptors ◽  
Radioreceptor Assay ◽  
Tail Flick ◽  
Significant Activity ◽  
Subsequent Test ◽  
Tail Immersion ◽  
Average Latency ◽  
Releasing Factors

The latency to tail-flick response in the rat was significantly prolonged by cerebro-ventricular infusion of 1.0 μg of somatostatin (SRIF) and more so with 10.0 μg. The D-tryptophan analog was less effective than native SRIF. Pretreatment with naloxone eliminated analgesia but not seizures induced by SRIF. Recording of the EEG activity enabled determination of the specific state of the sleep–waking cycle in which the repeated tail-flick responses were tested: latency was generally longer in both control and test animals when tail immersion was performed during the state of sleep or drowsiness rather than during the awake state. Although animals receiving SRIF were less likely to fall asleep between subsequent test trials, the average latency was actually longer than after control saline infusion when the animals slept more. SRIF, unlike other releasing factors and peptides tested, showed significant activity in an opiate radioreceptor assay. The blockade of SRIF action by naloxone pretreatment, along with binding of SRIF to opiate receptors in vitro, suggest opiate receptors to be involved in the mediation of analgesia observed in present study.

Coreceptor Tropism and Maraviroc Sensitivity of Clonally Derived Ethiopian HIV-1C Strains Using an in-house Phenotypic Assay and Commonly Used Genotypic Methods

2018 ◽  
Vol 16 (2) ◽  
pp. 113-120
Author(s):  
Amare Worku Kalu ◽  
Nigus Fikrie Telele ◽  
Shambhu G Aralaguppe ◽  
Solomon Gebre-Selassie ◽  
Daniel Fekade ◽  
...  
Keyword(s):  
Dose Response ◽  
In Vitro Activity ◽  
Coreceptor Tropism ◽  
Phenotypic Assay ◽  
Subtype B ◽  
Hiv 1 ◽  
Tropism Prediction ◽  
Alternative Regimen

Objectives:Genotypic Tropism Testing (GTT) tools are generally developed based on HIV-1 subtype B (HIV-1B) and used for HIV-1C as well but with a large discordance of prediction between different methods. We used an established phenotypic assay for comparison with GTT methods and for the determination of in vitro maraviroc sensitivity of pure R5-tropic and dual-tropic HIV-1C.Methods:Plasma was obtained from 58 HIV-1C infected Ethiopians. Envgp120 was cloned into a luciferase tagged NL4-3 plasmid. Phenotypic tropism was determined by in house method and the V3 sequences were analysed by five GTT methods. In vitro maraviroc sensitivity of R5-tropic and dual-tropic isolates were compared in the TZMbl cell-line.Results:The phenotypes were classified as R5 in 92.4% and dual tropic (R5X4) in 7.6% of 79 clones. The concordance between phenotype and genotype ranged from 64.7% to 84.3% depending on the GTT method. Only 46.9% of the R5 phenotypes were predicted as R5 by all GTT tools while R5X4 phenotypes were predicted as X4 by four methods, but not by Raymond’s method. All six tested phenotypic R5 clones, as well as five of six of dual tropic clones, showed a dose response to maraviroc.Conclusion:There is a high discordance between GTT methods, which underestimates the presence of R5 and overestimates X4 strains compared to a phenotypic assay. Currently available GTT algorithms should be further improved for tropism prediction in HIV-1C. Maraviroc has an in vitro activity against most HIV-1C viruses and could be considered as an alternative regimen in individuals infected with CCR5-tropic HIV-1C viruses.

ETUDE DE L'ACTION DU FACTEUR HYPOTHALAMIQUE LRF (LH-RELEASING FACTOR) CHEZ LE RAT IN VIVO & IN VITRO

1967 ◽  
Vol 55 (3) ◽  
pp. 481-496 ◽  
Author(s):  
Marian Jutisz ◽  
Annette Bérault ◽  
Marie-Anne Novella ◽  
Geneviève Ribot
Keyword(s):  
Dose Response ◽  
Crude Extract ◽  
Response Curve ◽  
Assay Method ◽  
Hypothalamic Extract ◽  
Rat Pituitary ◽  
Pituitary Glands ◽  
Releasing Effect

ABSTRACT A highly purified ovine LH-releasing factor (LRF) was obtained by a modification of the method previously described. After the fractionation of a crude hypothalamic extract on a Sephadex G-25 column, the LRF fraction was desalted and partially purified by chromatography on a Dowex 50 × 12 column and on an Amberlite CG 4B column. The last step of this method, chromatography on a CMC column, gave a purification of about 1600 times with respect to the crude extract. The action of this highly purified LRF preparation was studied on rat pituitary glands in vivo and in vitro. The method used in vivo was the evaluation of the LH-releasing effect of LRF in chronically ovariectomized, steroid-blocked rats (Ramirez & McCann 1963 b). A procedure was developed which allows a 4-fold concentration of the plasma LH from these rats, so that it can be assayed by a 4-point assay method. In the in vitro method, the pituitary glands of ovariectomized steroidblocked rats (Schally & Bowers 1964 a) were incubated in a Krebs-Ringer buffer with or without LRF, and the LH released into the medium was assayed using the O.A. A.D. method of Parlow. A dose-response curve was established between the log doses of LRF and the amount of LH released. This method can be used as a sensitive and specific assay for LRF. It was shown that a dose of 1.22 μg of LRF releases approximately 5 μg of LH per mg of pituitary tissue. This is about double of the amount of this hormone originally present in the pituitary glands of these rats (2.7 μg/mg). This leads us to the conclusion that the excess of this hormone was probably synthetized during the process of incubation. The amount of steroids injected as a blocking agents, appears to be very important for both in vivo and in vitro tests.

THE RELEASE OF CORTICOTROPHIN BY ANTERIOR PITUITARY TISSUE IN VITRO

1955 ◽  
Vol 33 (1) ◽  
pp. 408-415 ◽  
Author(s):  
Murray Saffran ◽  
A. V. Schally
Keyword(s):  
Anterior Pituitary ◽  
Brain Cortex ◽  
Test System ◽  
Posterior Pituitary ◽  
Acetyl Choline ◽  
Pituitary Tissue ◽  
Hypothalamic Tissue ◽  
Stimulation Of ◽  
Acth Release

The release of ACTH by rat anterior pituitary tissue in vitro was used as a test system for the detection of factors that stimulate ACTH-release. The results indicate that:1. Epinephrine or arterenol, added by themselves, are without effect.2. Hypothalamic tissue alone is also ineffective.3. The combination of hypothalamic tissue with epinephrine or arterenol increases the release of ACTH about threefold.4. Brain cortex can replace hypothalamus.5. Liver cannot replace neural tissue; acetyl choline and serotonin cannot replace epinephrine or arterenol.6. The greatest stimulation of ACTH-release (six- to eight-fold) occurs with posterior pituitary tissue plus arterenol. The arterenol may be replaced by hypothalamus or sphingosine, but not by dopamine (3,4-dihydroxyphenylethylamine), which is structurally similar to arterenol.7. The posterior pituitary is probably involved in the response of the anterior pituitary–adrenocortical system to stress.

2. Determination of in vitro dose response for some vasoactive substances on mammary arteries from lactating sows

1997 ◽  
Vol 50 (1-2) ◽  
pp. 163-164
Author(s):  
H. Busk ◽  
K. Jakobsen ◽  
M.T. Sørensen ◽  
M.O. Nielsen ◽  
E.O. Mikkelsen
Keyword(s):  
Dose Response ◽  
Vasoactive Substances ◽  
Mammary Arteries ◽  
Lactating Sows

THE RELEASE OF CORTICOTROPHIN BY ANTERIOR PITUITARY TISSUE IN VITRO

1955 ◽  
Vol 33 (3) ◽  
pp. 408-415 ◽  
Author(s):  
Murray Saffran ◽  
A. V. Schally
Keyword(s):  
Anterior Pituitary ◽  
Brain Cortex ◽  
Test System ◽  
Posterior Pituitary ◽  
Acetyl Choline ◽  
Pituitary Tissue ◽  
Hypothalamic Tissue ◽  
Stimulation Of ◽  
Acth Release

The release of ACTH by rat anterior pituitary tissue in vitro was used as a test system for the detection of factors that stimulate ACTH-release. The results indicate that:1. Epinephrine or arterenol, added by themselves, are without effect.2. Hypothalamic tissue alone is also ineffective.3. The combination of hypothalamic tissue with epinephrine or arterenol increases the release of ACTH about threefold.4. Brain cortex can replace hypothalamus.5. Liver cannot replace neural tissue; acetyl choline and serotonin cannot replace epinephrine or arterenol.6. The greatest stimulation of ACTH-release (six- to eight-fold) occurs with posterior pituitary tissue plus arterenol. The arterenol may be replaced by hypothalamus or sphingosine, but not by dopamine (3,4-dihydroxyphenylethylamine), which is structurally similar to arterenol.7. The posterior pituitary is probably involved in the response of the anterior pituitary–adrenocortical system to stress.

scholarly journals Evaluation of the Antioxidant Activity of Stalk and Fruit of Solanum aethiopicum L. (Solanaceae)

2020 ◽  
pp. 6-12
Author(s):  
Kady Diatta ◽  
William Diatta ◽  
Alioune Dior Fall ◽  
Serigne Ibra Mbacké Dieng ◽  
Amadou Ibrahima Mbaye ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Aqueous Extract ◽  
Reducing Power ◽  
Ethanol Extract ◽  
New Drugs ◽  
Solanum Aethiopicum ◽  
Dpph Method ◽  
The Many

Background: The use of plants for healing dates back to very remote times. Nowadays with the accession of new diseases plants are increasingly used for the formulation of new drugs able to overcome the many diseases (cancer, atherosclerosis) often caused by the disorder of the system prooxidant/antioxidant. Aim/Objective: On the strength of this observation, the research of an antioxidant plant is essential, hence the aim of this study, which is to determine the antioxidant activity of the stalk and the fruit of Solanum aethiopicum L. Methods: The fruits and stalk were washed, cut into fine slats, then dried in the incubator for three days and finally crushed into powder. An extraction by decoction with ethanol (stalks and fruits) and water (fruit) was subsequently carried out to obtain three extracts (ethanol and water). Antioxidant activity was evaluated through the FRAP method, and the trapping of radical DPPH. Results: For the FRAP method, at the highest concentration (1 mg/ml) the aqueous extract of the fruit (74.84±2.97%) has a higher reducing power compared to those of the ethanolic extracts of the fruit (70.15 ± 5.72%) and the stalk (49.85 ± 2.11%). These reducing powers, although significant, remain lower than those of tannic acid (89.95±0.007%). And finally, for the DPPH method, the aqueous extract of the fruit is more effective in reducing free radical DPPH with a IC50= 162±33 µg/ml, follow up by ethanol extract from the stalk (IC50= 360± 90 µg/ml) and finally ethanol extract from the fruit (IC50= 362.5± 23.5 µg/ml). These results confirm the in vitro antioxidant activity of the studied parts of Solanum aethiopicum. Conclusion: Prospective studies could focus on acute and subacute toxicities and the determination of the molecules responsible for the activity.

STUDIES ON THE CORTICOTROPHIN RELEASING ACTIVITY OF A POSTERIOR PITUITARY EXTRACT

1981 ◽  
Vol 89 (3) ◽  
pp. 423-429 ◽  
Author(s):  
S. C. KIRKLAND ◽  
M. L. ELLISON
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Active Material ◽  
Posterior Pituitary ◽  
Pituitary Extract ◽  
Corticotrophin Releasing Factor ◽  
Rat Pituitary ◽  
Posterior Pituitary Gland ◽  
Releasing Factors ◽  
Acth Release

The posterior pituitary gland is considered to be a source of a corticotrophin releasing factor(s) distinct from vasopressin. In this study, the corticotrophin releasing activity of a commercial posterior pituitary extract (Pitressin) and synthetic vasopressin were compared, using a perfused rat pituitary monolayer system. Pitressin was shown to have approximately twice the releasing activity than could be accounted for by its vasopressin content. Fractionation of the posterior pituitary extract, using high pressure liquid chromatography, showed it to contain active material co-eluting with synthetic vasopressin, and at least three other corticotrophin releasing factors. The releasing activity of the most active of these factors was investigated and was found to stimulate ACTH release in a dose-related manner.

STUDIES ON ECTOPIC ACTH-PRODUCING TUMOURS.

1976 ◽  
Vol 82 (1) ◽  
pp. 183-192 ◽  
Author(s):  
H. Yamamoto ◽  
Y. Hirata ◽  
S. Matsukura ◽  
H. Imura ◽  
M. Nakamura ◽  
...  
Keyword(s):  
Dose Response ◽  
Arginine Vasopressin ◽  
Response Curve ◽  
Assay Method ◽  
Ectopic Acth ◽  
Ectopic Production ◽  
Releasing Factors ◽  
Incubation Method ◽  
Tumour Extract

ABSTRACT In order to elucidate whether ectopic ACTH-producing tumours elaborate corticotrophin-releasing factors (CRF)-like materials, the CRF-like activity of tumour extracts was measured by the in vitro pituitary incubation method. Seven out of 12 tumour extracts with suspected ACTH-producing tumours showed CRF-like activity. No correlation was found between ACTH and CRF-like activities in tumour extracts in which both activities were present. The dose-response curve of a tumour extract was almost parallel to that of crude CRF (NIAMDD) and clearly different from those of lysine-8-vasopressin and arginine-vasopressin, both of which showed CRF-like activity by this assay method. Trypsin digestion considerably lowered the CRF-like activity of a tumour extract. These results suggest that ectopic production of CRF-like substance(s) occurs more frequently than was supposed previously, especially in ACTH-producing tumours.

Sign in / Sign up

Export Citation Format

Share Document