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Biomedical subjects

L D'Angelo

Publications and source records attributed to L D'Angelo.

At least 55 records · Page 3Linked to original sources
PubMed1987

Depressant action of oxybutynin on the contractility of intestinal and urinary tract smooth muscle.

Experiments were carried out in-vitro using segments of guinea-pig ileum, taenia caeci, ureter and detrusor. In the ileum, oxybutynin (30, 100 nM) competitively antagonized acetylcholine-induced contractions but did not alter those induced by histamine. Higher concentrations of oxybutynin (up to 10 microM) induced a non-competitive depression of responses to both agonists and caused a parallel shift to the right of the Ca2+-induced contractions in taenia caeci strips bathed in a Ca2+-free, high-K+ medium. In the ureter, oxybutynin (1-10 microM) impaired rhythmic muscular contractions in normal medium and after CaCl2 addition in Ca2+-free medium. Similarly to verapamil (10, 30 microM), oxybutynin (10, 30 microM) depressed both the cholinergic and non-adrenergic, non-cholinergic components of the electrically-induced contractions of detrusor strips. It is concluded that oxybutynin has anticholinergic properties and, at higher concentrations, exerts a direct spasmolytic activity possibly mediated by blockade of the transmembrane Ca2+ fluxes responsible for smooth muscle contraction.

Acetylcholine↗
PubMed1986

Infectious disease problems in adolescents.

Although adolescents are a generally healthy group, infection can create significant morbidity and occasional mortality. As in all patients, early diagnosis and treatment can shorten the duration of infection and limit complications. Physicians should provide teenage patients with guidance necessary to prevent transmission and recurrence.

Adolescent↗
PubMed1985

Psychosis and seizures following the injection of penicillin G procaine. Hoigne's syndrome.

Psychosis and/or seizures following the administration of intramuscular penicillin G procaine have not been reported in the pediatric literature to our knowledge. This omission is regrettable in light of the frequency with which this treatment is indicated as therapy for gonococcal infections. We report clinical data from four patients afflicted by this reaction known as Hoigne's syndrome. The dramatic and unexpected manifestation of this condition calls for an immediate diagnosis to proceed with the appropriate treatment.

Adolescent↗
PubMed1985

Subsensitivity of enteric cholinergic neurones to alpha 2-adrenoceptor agonists after chronic sympathetic denervation.

The concentration-effect relationships of noradrenaline, dopamine and clonidine in inhibiting resting and stimulated acetylcholine output have been studied in intact and in sympathetically denervated preparations of guinea pig isolated distal colon. The order of potencies for the inhibition of resting acetylcholine release in intact preparations was clonidine greater than dopamine greater than noradrenaline while the order of intrinsic activities was noradrenaline greater than dopamine greater than clonidine. Sympathetic denervation was able to modify the potency of either clonidine, dopamine and noradrenaline. Noradrenaline was 6 times more potent in inhibiting resting acetylcholine release in denervated than in intact preparations, while clonidine and dopamine underwent a 18-fold and a 11-fold decrease in potency after denervation. The potency of clonidine relative to noradrenaline was 110 in intact preparations and only 1.2 in denervated organs. The intrinsic activities of noradrenaline, dopamine and clonidine were almost unchanged in denervated organs. A dose-dependent facilitatory effect of yohimbine on both the resting acetylcholine output and the peristaltic reflex could be observed in intact but not in sympathetically denervated preparations at concentrations ranging from 2.5 X 10(-8) M to 2.5 X 10(-7) M. Yohimbine was able to counteract the inhibitory effect of dopamine and to remove the inhibitory effect of periarterial nerve stimulation on both acetylcholine release and the peristaltic reflex. Our results are consistent with the existence of a tonic physiological modulation of enteric cholinergic neurones by postganglionic sympathetic fibres. The order of potencies of adrenoceptor agonists and the antagonism by yohimbine is consistent with such a modulation being entirely carried out through alpha 2-heteroceptors.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1985

Telephone transmission of fetal monitor data.

A telephone system was established to transmit fetal monitor data to a tertiary center from small rural hospitals with limited experience in interpreting such tracings. This type of program fosters sound obstetric management and appropriate therapeutic intervention of monitored patients in rural areas. We believe that similar service can be established by other tertiary hospitals.

Female↗
PubMed1984

Changes in sensitivity to the inhibitory effects of adrenergic agonists on intestinal motor activity after chronic sympathetic denervation.

The concentration-effect relationships of adrenergic agonists in inhibiting muscular tone, carbachol-induced contraction of circular muscle strips and nerve-mediated motor activity during the peristaltic reflex have been studied in intact and sympathetically denervated preparations of isolated guinea-pig colon. The order of potencies of adrenergic agonists was different for muscular and nerve-mediated effects, being clonidine greater than noradrenaline greater than methoxamine greater than isoprenaline for the inhibition of peristalsis and isoprenaline greater than noradrenaline greater than methoxamine greater than clonidine for the relaxation of circular muscle. Denervation supersensitivity was specific for the adrenergic agonists and developed both to the muscular and nerve-mediated effects, involving both alpha and beta receptors. The degree of potentiation was similar for noradrenaline and isoprenaline when measured for the muscular effects but was significantly higher for noradrenaline than for isoprenaline or methoxamine when measured for peristalsis inhibition. No potentiation could be observed for papaverine and for the muscular effects of methoxamine and phenylephrine. The increase in potency of noradrenaline ranged from a 26-fold increase for the inhibition of propulsion velocity to a 2.5-fold increase for the inhibition of carbachol-induced contraction. A much narrower range was observed for isoprenaline. Potentiation could also be observed for the inhibitory effect of noradrenaline on acetylcholine release. Clonidine was the most potent agonist against peristaltic reflex and the weakest agonist in relaxing circular muscle. Denervated preparations became subsensitive to the inhibitory effect of clonidine on peristaltic reflex. The potency of clonidine relative to noradrenaline was 488 in intact preparations and only 3.1 in denervated organs.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1983

Reduction of phenytoin clearance caused by cimetidine.

The effect of cimetidine on the disposition kinetics of phenytoin was investigated in 7 healthy volunteers. Each subject received a single intravenous dose of phenytoin on two occasions, in the control state, and during concurrent treatment with cimetidine 1 200 mg/day for 6 days. A slight but statistically significant decrease both in the rate of elimination and total body clearance of phenytoin was observed during the administration of cimetidine. The effect is probably due to inhibition of metabolism.

Adult↗
PubMed1983

Midazolam and sleep in insomniac patients.

The effects of midazolam (15 and 30 mg p.o.) on the sleep of insomniac patients were assessed by means of polysomnographic recordings. As compared with placebo, 15 mg midazolam significantly increased non-REM sleep while other objective measures of insomnia were only slightly modified. At the 30 mg dose, midazolam significantly decreased total wake time and wake time after sleep onset. On the other hand, total sleep and non-REM sleep time were increased. No development of tolerance was observed following 2 weeks of drug use.

Adult↗
PubMed1983

Dilazep: an inhibitor of adenosine uptake with intrinsic calcium antagonistic properties.

Concentrations of dilazep which were ineffective in altering the muscular tone of the guinea-pig taenia caeci (0.03, 0.3 microM) or the phasic mechanical activity of the rabbit proximal ileum (0.03 microM) markedly potentiated the inhibitory action of adenosine on both these parameters. Dilazep, 0.3 microM or greater, dose-dependently inhibited the mechanical activity of the proximal ileum. This inhibitory action was probably mediated by more than one mechanism, as shown by the fact that theophylline (50, 100 microM) antagonized the effect at lower dilazep concentrations (up to 3 microM) leaving essentially unchanged the response to higher concentrations (6, 10 microM). Similarly, the responses to low doses of dilazep were reduced after desensitization of the organ to adenosine, whilst the responses to higher doses were unaffected by this procedure. In a Ca2+-free, high-K+ medium, dilazep (1-10 microM) caused a parallel shift to the right of the Ca2+-induced contractions of the guinea-pig taenia caeci. Adenosine showed only slight Ca2+-antagonistic properties within the mM range of concentrations. These findings suggest that, at the higher concentration tested, dilazep exhibits Ca2+-antagonistic properties unrelated to its adenosine-mediated mode of action.

Adenosine↗
PubMed1982

Sleep laboratory study of the effects of midazolam in insomniac patients.

The effects of midazolam, a short-acting imidazobenzodiazepine, on the sleep cycle of insomniac patients were assessed by means of polygraphic recordings. Baseline placebo nights were compared with drug (30 mg p.o.) and placebo withdrawal nights. The compound was effective in inducing and maintaining sleep on short- and intermediate-term administration. Tolerance was not observed following two weeks of drug use. Subjective reports corroborated the effectiveness of midazolam as a hypnotic. In regard to its effects on sleep stages, midazolam markedly decreased Stage 3 and abolished Stage 4 sleep, while Stage 2 was augmented. REM sleep percentage was not significantly affected. Withdrawal of midazolam was followed by rebound insomnia, in which sleep latency, total wake time and wake time after sleep onset were increased above baseline. Side-effects related to midazolam administration included headache, muscular weakness and dizziness. They were mild and wore off 1-2 hours after awakening.

Adult↗
PubMed1982

Effects of desensitization to adenosine 5'-triphosphate and adenosine on non-adrenergic inhibitory responses in the circular muscle of rabbit colon.

An approximate eight fold desensitization of the circular coat of the distal rabbit colon to adenosine 5'-triphosphate (ATP) and adenosine could be achieved by repeatedly exposing the organ to relatively low concentrations (10-100 microM) of these compounds. The desensitization was specific and reversible after prolonged washing. It could be overcome by increasing the concentrations of the purine agonists. Dipyridamole potentiated the non-adrenergic inhibition in response to transmural stimulation but failed to influence the caudad relaxation evoked by radial distension. Desensitization to ATP and adenosine (and to ATP + adenosine simultaneously) did not affect the non-adrenergic inhibition in response to radial distension or transmural stimulation. These results suggest that neither ATP nor adenosine are the final transmitters mediating the non-adrenergic inhibitory responses in the distal colon of the rabbit.

Adenosine↗