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J W Black - One of the best experts on this subject based on the ideXlab platform.
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the pharmacology of cimetidine a new histamine h2 receptor antagonist
British Journal of Pharmacology, 2010Co-Authors: R W Brimblecombe, W A M Duncan, Graham J Durant, Charon R Ganellin, M E Parsons, J W BlackAbstract:Burimamide and metiamide which have been described previously (Black, Duncan, Durant, Ganellin & Parsons, 1972; Black, Duncan, Emmett, Ganellin, Hesselbo, Parsons & Wyllie, 1973) are histamine H2-receptor antagonists. This communication describes some aspects of the pharmacology of cimetidine (N-cyano-N′-methyl-N″[2-(5- methyl-4-imidazolyl-methylthio)ethyl] guanidine; SK&F 92334), a new H2-receptor antagonist. In vitro the compound antagonizes the actions of histamine on isolated guinea-pig atrium and isolated electrically-stimulated rat uterus with KB values of 7.9 × 10−7m and 8.1 × 10−7m respectively, corresponding to pA2 values of 6.1 on each tissue. At very high concentrations cimetidine antagonizes the actions of isoprenaline on atrium and uterus and the actions of histamine and carbachol on isolated guinea-pig ileum but the results are not consistent with competitive antagonism at β-adrenoceptors, histamine H1-receptors or muscarinic receptors. The effects of cimetidine on gastric acid secretion have been studied in a number of preparations. The results are summarized in Table 1. In all preparations cimetidine was approximately equiactive in inhibiting histamine and pentagastrin-stimulated acid secretion but less effective in inhibiting carbachol-stimulated secretion. Basal secretion was also inhibited. In Heidenhain pouch dogs the blood levels to give 50% inhibition of maximally-stimulated gastric secretion (EC50) were approximately 1–2 µm and the half-life of the compound about one hour. Table 1 The effects of cimetidine on gastric acid secretion In male human volunteers cimetidine given intravenously has been shown to inhibit histamineor pentagastrin-stimulated gastric secretion with an EC50 of about 2.5 μm and a half-life of about two hours. In chronic toxicity studies metiamide has been shown at high doses to produce kidney damage and agranulocytosis in some dogs (Brimblecombe, Duncan & Walker, 1973). In tests so far carried out cimetidine at equivalent doses has not shown similar toxicity.
Haruo Ohnishi - One of the best experts on this subject based on the ideXlab platform.
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gastric antisecretory effect of frg 8813 a new histamine h2 receptor antagonist in rats and dogs
European Journal of Pharmacology, 1993Co-Authors: Masahiro Shibata, Tetsuaki Yamaura, Niro Inaba, Sadayoshi Onodera, Yuriko Chida, Haruo OhnishiAbstract:FRG-8813, a new histamine H2 receptor antagonist, was examined for antisecretory effects and compared with famotidine and cimetidine in rats and dogs. In pylorus-ligated and lumen-perfused rats, FRG-8813 given i.v. reduced basal gastric acid secretion and the acid secretion evoked by histamine, tetragastrin, bethanechol, and 2-deoxy-D-glucose in a dose-dependent manner. The i.v. antisecretory activity of FRG-8813 was equivalent to or slightly less than that of famotidine and the intraduodenal (i.d.) activity was greater than that of cimetidine. The duration of action of FRG-8813 was substantially longer than that of farmotidine and cimetidine for both i.v. and i.d. routes. The i.v. ED40 values for the histamine- and tetragastrin-evoked responses and the i.v. ED30 value for the bethanechol-evoked response were 0.15, 0.09 and 0.43 mg2kg, respectively. In Heidenhain pouch dogs, when the three H2 antagonists were given i.v. or orally, the relative antisecretory potency of the compounds was similar to that in rats. The long-lasting antisecretory effect of FRG-8813 was also observed, and the i.v. ED50 values for histamine-, tetragastrin- and bethanechol-evoked responses were 0.1, 0.24 and 1.0 mg/kg, respectively. Comparison of the parenteral and enteral potencies indicated that FRG-8813 has a lower bioavailability than famotidine and cimetidine in rats and dogs. These data suggest that FRG-8813 has a potent and long-lasting antisecretory effect with a far greater potency than cimetidine and with a slightly lower potency than famotidine.
Omari Naima - One of the best experts on this subject based on the ideXlab platform.
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Effects of colocynth alkaloids and glycosides on Wistar rats fed high-fat diet. A biochemical and morphological study
2017Co-Authors: Birem Zahia, Tabani Khadidja, Lahfa Farid, Djaziri Rabah, Hadjbekkouche Fatima, Ahmed Koceir El-hadj, Omari NaimaAbstract:Introduction. In traditional medicine, Citrullus colocynthis is used to treat diabetes, hyperlipidemia, cardiovascular diseases, inflammation, and oxidative stress, all of which can appear when a diet rich in vegetable fats, such as palm oil, is continuously consumed. Such high-fat diets are chronic stressors of the hypothalamic–pituitary–adrenal axis. The objective of our study was to analyze and evaluate the effects of colocynth total alkaloids and glycosides on metabolic, hormonal, and structural disorders of the adrenal medulla in Wistar rats fed a high-fat diet. Material and methods. Twenty six Wistar rats were distributed as follows: six control animals received a standard laboratory diet; twenty experimental rats received the standard laboratory diet supplemented with palm oil — the high-fat diet (HFD). After seven months of this diet, the HFD group was subdivided into rats treated for the next 2 months with either alkaloid extract (HFD-ALk group) or ethanol extract of glycosides (HFD-GLc) or animals on HFD only. Plasma metabolites and ACTH concentrations were measured by standard methods. Sections of adrenal medulla were stained by Heidenhain-Azan method and Sudan Black. Results. The adrenal medulla of the HFD rats showed prominent structural changes, such as hypertrophy of chromaffin and ganglion cells, vacuolation, inflammatory foci, and fibrosis. The biochemical and hormonal parameters were significantly improved in the HFD rats treated with alkaloid and glycoside extracts of Citrullus colocynthis. Moreover, the morphological changes of the adrenal medulla were attenuated in HFD-ALk and HFD-Glc rats. Conclusions. The results of the study indicate that phytotherapy using Citrullus colocynthis alkaloids may correct metabolic and hormonal perturbations as well as adrenal medulla structure of rats maintained on HFD. (Folia Histochemica et Cytobiologica 2017, Vol. 55, No. 2, 74–85
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Effects of colocynth alkaloids and glycosides on Wistar rats fed high-fat diet. A biochemical and morphological study
'VM Media SP. zo.o VM Group SK', 2017Co-Authors: Birem Zahia, Tabani Khadidja, Lahfa Farid, Djaziri Rabah, Hadjbekkouche Fatima, Koceir, El-hadj Ahmed, Omari NaimaAbstract:Introduction. In traditional medicine, Citrullus colocynthis is used to treat diabetes, hyperlipidemia, cardiovascular diseases, inflammation, and oxidative stress, all of which can appear when a diet rich in vegetable fats, such as palm oil, is continuously consumed. Such high-fat diets are chronic stressors of the hypothalamic–pituitary–adrenal axis. The objective of our study was to analyze and evaluate the effects of colocynth total alkaloids and glycosides on metabolic, hormonal, and structural disorders of the adrenal medulla in Wistar rats fed a high-fat diet. Material and methods. Twenty six Wistar rats were distributed as follows: six control animals received a standard laboratory diet; twenty experimental rats received the standard laboratory diet supplemented with palm oil — the high-fat diet (HFD). After seven months of this diet, the HFD group was subdivided into rats treated for the next 2 months with either alkaloid extract (HFD-ALk group) or ethanol extract of glycosides (HFD-GLc) or animals on HFD only. Plasma metabolites and ACTH concentrations were measured by standard methods. Sections of adrenal medulla were stained by Heidenhain-Azan method and Sudan Black. Results. The adrenal medulla of the HFD rats showed prominent structural changes, such as hypertrophy of chromaffin and ganglion cells, vacuolation, inflammatory foci, and fibrosis. The biochemical and hormonal parameters were significantly improved in the HFD rats treated with alkaloid and glycoside extracts of Citrullus colocynthis. Moreover, the morphological changes of the adrenal medulla were attenuated in HFD-ALk and HFD-Glc rats. Conclusions. The results of the study indicate that phytotherapy using Citrullus colocynthis alkaloids may correct metabolic and hormonal perturbations as well as adrenal medulla structure of rats maintained on HFD.
Richard Knight - One of the best experts on this subject based on the ideXlab platform.
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isolated visual symptoms at onset in sporadic creutzfeldt jakob disease the clinical phenotype of the Heidenhain variant
British Journal of Ophthalmology, 2005Co-Authors: Sarah Cooper, Katy Murray, C A Heath, R G Will, Richard KnightAbstract:Background: The Heidenhain variant of sporadic Creutzfeldt-Jakob disease (sCJD) is commonly understood to represent cases with early, prominent visual complaints. The term is clarified to represent those who present with isolated visual symptoms. This group may pose diagnostic difficulties and often present to ophthalmologists where they may undergo needless invasive procedures. Method: A retrospective review of 594 pathologically proved sCJD cases referred to the UK National CJD Surveillance Unit over a 15 year period to identify Heidenhain cases. Results: 22 cases had isolated visual symptoms at onset with a mean illness duration of 4 months. The mean age at disease onset was 67 years. Most displayed myoclonus, pyramidal signs, and a delay in the onset of dementia for some weeks. 17 (77%) were referred initially to ophthalmology. Two underwent cataract extraction before diagnosis. All tested cases were homozygous for methionine at codon 129 of the prion protein gene. Conclusions: This rare, but clinically distinct, group of patients with sCJD may cause diagnostic difficulties. Because ocular intervention carries with it the risk of onward transmission awareness of this condition among ophthalmologists is important.
R W Brimblecombe - One of the best experts on this subject based on the ideXlab platform.
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the pharmacology of cimetidine a new histamine h2 receptor antagonist
British Journal of Pharmacology, 2010Co-Authors: R W Brimblecombe, W A M Duncan, Graham J Durant, Charon R Ganellin, M E Parsons, J W BlackAbstract:Burimamide and metiamide which have been described previously (Black, Duncan, Durant, Ganellin & Parsons, 1972; Black, Duncan, Emmett, Ganellin, Hesselbo, Parsons & Wyllie, 1973) are histamine H2-receptor antagonists. This communication describes some aspects of the pharmacology of cimetidine (N-cyano-N′-methyl-N″[2-(5- methyl-4-imidazolyl-methylthio)ethyl] guanidine; SK&F 92334), a new H2-receptor antagonist. In vitro the compound antagonizes the actions of histamine on isolated guinea-pig atrium and isolated electrically-stimulated rat uterus with KB values of 7.9 × 10−7m and 8.1 × 10−7m respectively, corresponding to pA2 values of 6.1 on each tissue. At very high concentrations cimetidine antagonizes the actions of isoprenaline on atrium and uterus and the actions of histamine and carbachol on isolated guinea-pig ileum but the results are not consistent with competitive antagonism at β-adrenoceptors, histamine H1-receptors or muscarinic receptors. The effects of cimetidine on gastric acid secretion have been studied in a number of preparations. The results are summarized in Table 1. In all preparations cimetidine was approximately equiactive in inhibiting histamine and pentagastrin-stimulated acid secretion but less effective in inhibiting carbachol-stimulated secretion. Basal secretion was also inhibited. In Heidenhain pouch dogs the blood levels to give 50% inhibition of maximally-stimulated gastric secretion (EC50) were approximately 1–2 µm and the half-life of the compound about one hour. Table 1 The effects of cimetidine on gastric acid secretion In male human volunteers cimetidine given intravenously has been shown to inhibit histamineor pentagastrin-stimulated gastric secretion with an EC50 of about 2.5 μm and a half-life of about two hours. In chronic toxicity studies metiamide has been shown at high doses to produce kidney damage and agranulocytosis in some dogs (Brimblecombe, Duncan & Walker, 1973). In tests so far carried out cimetidine at equivalent doses has not shown similar toxicity.