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At least 1,099 records · Page 61Linked to original sources
PubMed1978

Inhibition of hepatic demethylation of aminopyrine by oral contraceptive steroids in humans.

The effect of oral contraceptive steroids (OCS) on the rate of hepatic demethylation of 14C-dimethylaminoantipyrine (DAP) was studied directly in healthy young volunteers using a newly developed noninvasive breath analysis technique. After oral administration of a trace dose of DAP the specific activity of 14CO2 in breath was determined during 6 h and expressed as half life. The half life of eighteen female and twelve male control subjects was 2.4 +/- 1.2 h (2 SD) and 2.2 +/- 0.6 h (2 SD), respectively. In seven women starting OCS a progressive prolongation of DAP half life during a single menstrual period was observed. In seventeen women who had taken OCS in 21 day cycles, for more than 3 months, the half life was significantly (P less than 0.001) prolonged (4.4 +/- 2.1 h) when measured after 21 consecutive days of OCS intake. On average, stopping OCS for 7 days or giving phenobarbital in addition to OCS shortened DAP half life significantly (from 4.4 +/- 2.1 h to 3.2 +/- 1.1 h, n = 17, P less than 0.005; and from 4.6 +/- 2.0 h to 3.2 +/- 1.0 h, n = 12, P less than 0.01, respectively). Eight of twelve women on OCS responded to OCS intake and to OCS cessation and phenobarbital, whereas four women did not respond to any of these measures. These data suggest that inhibition of hepatic demethylation of DAP by OCS is time dependent and reversible. The extent of inhibition appears to be an individual characteristic of a given person.

Adult↗
PubMed1993

The electrochemical-proton-gradient-activated states of F0F1 ATPase in plant mitochondria as revealed by detergents.

ATP hydrolysis, triggered by the addition of polyoxyethylene-9-lauryl ether (Lubrol) or lauryldimethylamine oxide (LDAO) to energized plant mitochondria was studied in some details. The membrane disruption was quasi-instantaneous (2-3 s) with both detergents, as shown by the decrease of turbidity and the stopping of respiration. In pea leaf mitochondria, Lubrol triggered ATP hydrolysis in almost the same way as valinomycin plus nigericin, except that the activity was slightly stimulated and became insensitive to carboxyatractyloside. This allowed investigations of ATP hydrolysis without any interference of the ATP/ADP antiporter or the phosphate carrier. Lubrol did not prevent the ATPase from deactivating in pea leaf mitochondria, and did not trigger any ATP hydrolysis in potato tuber mitochondria. At variance with Lubrol, LDAO changed the properties of the F0F1 ATPase. It made the enzyme oligomycin insensitive and froze it in an activated state. The activity was also 5-8-times stimulated in pea leaf mitochondria. Moreover, LDAO revealed an important ATP hydrolase activity when added to energized potato tuber mitochondria. Despite the specific effect of LDAO, the activity triggered by this detergent strongly depended on the energized state of the organelles before detergent addition. From this study, it is concluded that the electrochemical proton gradient is completely necessary to activate the F0F1-ATPase in intact plant mitochondria, as known in chloroplasts and suggested by some reports in animal mitochondria. Moreover, it is suggested that the main difference between the enzymes of pea leaf and potato tuber mitochondria is their rate of deactivation after the collapse of the transmembrane electrochemical potential difference. Finally, when properly used, detergents appear to be a powerful tool to probe the state of the ATPase in intact mitochondria, and maybe in more integrated systems.

Adenosine Triphosphate↗
PubMed1996

The association of different detergents with the photosynthetic reaction center protein of Rhodobacter sphaeroides R26 and the effects on its photochemistry.

Detergent-free reaction centers from Rhodobacter sphaeroides R26 were used to study the solubilization of reaction centers in various detergents and their effects on reaction center photochemistry. 500 +/- 100 n-octyl-beta-D-glucopyranoside or 51 +/- 5 Triton X-100 molecules were associated with one reaction center. For N.N-alkylamine N-oxide detergents with chain lengths in the range from 8-13 carbon atoms, the number of detergent molecules associated with the reaction centers increased with decreasing chain length. The amount of detergent molecules associated with the reaction centers decreased almost tenfold if the pH was increased from pH 6 to pH 10. The addition of 5% 1,2,3-heptanetriol to various detergents lowered the detergent/reaction center ratio by a factor of two compared to that for the pure detergent. The detergent concentration at which solubilization of the reaction center occurs was close to the critical micelle concentration for all detergents studied. The absorption band at 865 nm of the primary donor in the reaction center shifts to 846 nm when detergent was removed from the reaction center; upon resolubilization with various detergents, this band shifts back to 865 nm. In 80-90% of the detergent-free reaction centers, the secondary electron transfer from QA to QB was inhibited: this electron transfer was restored after re-addition of detergent.

Cytochrome c Group↗
PubMed1972

Effect on reproductive organs of three clomiphene analogues.

1. The oestrogenic properties of four triphenylethylene compounds were compared. They can be listed as follows in order of their oestrogenic potency: 1-[p-(beta-diethylaminoethoxy)-phenyl]-2-nitro-1,2-diphenylethylene (E.I.P.W. 111) > clomiphene > 1-[p-(beta-dimethylaminoethoxy)-phenyl]-2-nitro-1, 2-diphenylethylene (E.I.P.W. 113)> 1-[p-(beta-diethylaminoethoxy)-phenyl]-1,2-diphenylethylene (E.I.P.W. 103). The oestrogenic potency of compound E.I.P.W. 111 was found to be about 1/10th of that of oestradiol.2. Compound E.I.P.W. 111 is partially antioestrogenic but not progesteronic in nature. It has no androgenic effect.

Animals↗
PubMed1972

A quantitative study of the anticholinergic action of several tricyclic antidepressants on the rat isolated fundal strip.

1. Investigations were carried out on the antagonism of the action of carbamylcholine chloride on the isolated fundus of the rat stomach by several tricyclic antidepressants.2. The anticholinergic potency of the compounds was in the order: GP 45437>amitriptyline>protriptyline>desmethylimipramine>opipramol. All of the antagonists were less effective than atropine.3. Statistical analysis was carried out to determine whether the theory of competitive antagonism would fit the data obtained.

Amitriptyline↗
PubMed1973

Cyclopentolate in treatment of sarin miosis.

1. Six young male volunteers were exposed to sarin vapour (isopropyl methyl phosphonofluoridate) at a concentration of 0.5 mg/m(3) for 30 min (concentration time (Ct) 15 (mg min)/m(3)).2. The resulting clinical syndrome was treated by instilling 0.06 ml of a 1% solution of cyclopentolate into the conjunctival sac.3. Visual acuity, retinoscopy, objective and subjective refraction and pupil sizes were noted before the trial, after exposure to sarin and after treatment with cyclopentolate.4. No appreciable difference was demonstrated between the control objective retinoscopy values and those obtained after cyclopentolate treatment of the clinical syndrome induced by sarin. Reduced near visual acuity was observed in some subjects treated with cyclopentolate as compared with acuity after exposure to sarin alone, considered to be due to the partial cycloplegia produced by treatment. Visual acuity after exposure to sarin alone was improved in some instances by the miosis produced.5. It is suggested that unless full dark adaptation is a consideration, treatment of the ophthalmic condition resulting from exposure to this dosage of sarin should be reserved for those experiencing distressing ocular symptoms.

Adult↗
PubMed1974

Pharmacology of M & B 18,706, a drug which selectively reduces decerebrate rigidity.

1 (+/-)-10-(3-Dimethylamino-2-methylpropyl)-2-valeroylphenothiazine hydrochloride (M & B 18,706) has been compared with dimethothiazine, chloropromazine, diazepam and baclofen for potency in reducing decerebrate rigidity in the cat and rat and for activity in causing ataxia or sedation.2 When given intravenously M & B 18,706 had seven times the potency of dimethothiazine and one-half the potency of chlorpromazine in reducing the rigidity of the intercollicular decerebrate cat. When administered orally M & B 18,706 and chlorpromazine were equi-potent in reducing rigidity but M & B 18,706 was less effective than chlorpromazine in producing ataxia in this species.3 In the rat, M & B 18,706 had one-quarter the potency of chlorpromazine for reducing decerebrate rigidity but had from 1/20th to 1/200th its potency in tests for sedative or tranquillizing activity.4 M & B 18,706, like dimethothiazine and chlorpromazine, had little effect on the rigidity of ischaemic decerebrate cats and failed to inhibit polysynaptic spinal reflexes.5 M & B 18,706 had intravenous potency comparable to chlorpromazine in reducing the pressor action of noradrenaline in the spinal cat.

Adrenergic alpha-Antagonists↗
PubMed1974

A comparison of the actions of some drugs on decerebrate rigidity, muscle spindle activity and alpha-adrenoceptors.

1 The relative potencies of methotrimeprazine, (+)-methotrimeprazine, (+/-)-10-(3-dimethylamino-2-methylpropyl)-2-valeroyl phenothiazine hydrochloride (M & B 18,706) and (+)-M & B 18,706 in reducing the pressor action of noradrenaline in the spinal cat, reducing intercollicular decerebrate rigidity, and muscle spindle afferent activity have been studied.2 Methotrimeprazine was eight times as potent as (+)-methotrimeprazine in reducing the pressor action of noradrenaline and six times as potent in reducing decerebrate rigidity. M & B 18,706 was also eight times as potent as (+)-M & B 18,706 in reducing the pressor action of noradrenaline and six times as potent in reducing decerebrate rigidity.3 For the above compounds and chlorpromazine there was a significant correlation between the effective doses for the inhibition of the pressor action of noradrenaline and for the reduction of decerebrate rigidity.4 The doses which reduced decerebrate rigidity were similar to those that reduced muscle spindle afferent discharge. It is likely that these drugs reduce decerebrate rigidity by inhibiting fusimotor activity.5 Desipramine increased decerebrate rigidity and increased spindle afferent discharge.6 It is thought that the phenothiazine derivatives studied reduce decerebrate rigidity and spindle afferent discharge by inhibiting receptors for noradrenaline in the central nervous system.

Animals↗
PubMed1974

The nature of the binding between LSD and a 5-HT receptor: a possible explanation for hallucinogenic activity.

1 (+)-Lysergic acid diethylamide (LSD) mimicked 5-hydroxytryptamine (5-HT) in its ability to stimulate fluid secretion, to change transepithelial and intracellular potentials as well as to increase the cyclic 3',5'-adenosine monophosphate (cyclic AMP) concentrations of isolated salivary glands of Calliphora.2 Unlike 5-HT, LSD disengages slowly from the receptor and fluid secretion continues despite repeated washing.3 Both 5-HT and tryptamine prevented LSD from acting on the glands.4 LSD bound to the receptor was slowly displaced when glands were treated with agonists (tryptamine) or antagonists (gramine).5 The property of LSD which permits it to function as an agonist despite remaining tightly bound to the receptor is discussed as a possible basis for its profound effects within the central nervous system.

Alkaloids↗
PubMed1975

Local anaesthetic and antiarrhythmic properties of an aminosteroid: 3alpha-dimethyl-amino-5alpha-androstan-2beta-ol-17-one (Org. NA 13).

1. The aminosteroid Org. NA13 (3alpha-dimethylamino-5alpha-androstan-2beta-ol-17-one) was shown to be a more potent local anaesthetic than lignocaine in rats and guinea-pigs. 2. Experimental arrhythmias induced in mice by chloroform, in rats by aconitine and in dogs by coronary artery ligation were corrected by Org. NA13 at doses from 10 to 50 mg/kg intravenously. 3. In contrast to lignocaine, other local anaesthetics and beta-adrenoceptor blocking drugs, Org. NA 13 did not show any activity against the arrhythmias induced by ouabian in dogs. 4. The acute toxicity in whole animals and myocardial toxicity in the rabbit isolated atrium appeared to be less than that observed with lignocaine.

Acetylcholine↗
PubMed1991

Lymphocyte transformation and thiuram sensitization.

The use of a lymphocyte transformation test (LTT) to confirm allergic contact dermatitis from thiurams has been investigated. The responses of peripheral blood mononuclear cells (PBMC) from thiuram-sensitive and non-sensitive individuals following culture with dimethylcarbamoyl-protein (human serum albumin; HSA) and dimethylthiocarbamoyl-HSA conjugates has been compared. Only PBMC from those patients who were patch-test-positive with thiuram-mix and sensitized to tetramethylthiuram monosulphide (TMTM) or TMTM and tetramethylthiuram disulphide (TMTD) exhibited significant proliferative responses to these conjugates. Thiuram-patch-test-negative patients and control donors with no history of allergic contact dermatitis failed to mount a significant response to any concentration of either conjugate. Two of the thiuram-sensitive patients were also nickel-patch-test-positive, and PBMC isolated from these donors, but not from nickel-patch-test-negative patients, proved positive in a nickel LTT. The data reveal that relevant hapten-protein conjugates are capable of provoking specific human lymphocyte proliferative responses in vitro, and that, using this technique, the LTT can, in principle, be used for the investigation and/or diagnosis of skin sensitization to lipophilic contact allergens.

Cell Division↗