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Biomedical subjects

A Brambilla

Publications and source records attributed to A Brambilla.

At least 55 records · Page 3Linked to original sources
PubMed1985

Cholinergic control of gastric acid secretion.

In the perfused stomach preparation of the anaesthetized rat the cholinergic agonists acetylcholine (ACh) and bethanechol stimulated gastric acid secretion. Both agonists produced similar maximal acid output (70 mumols/15 min) when infused intravenously. However, bethanechol was more potent, eliciting half maximal stimulation at 1.98 mumols/kg/h, while the corresponding dose of ACh was 10.95 mumols/kg/h. Secretory responses to either agonist were antagonized in a dose related fashion by blockade of muscarinic receptors with atropine. In contrast, inhibition of nicotinic receptors with hexamethonium produced a striking potentiation of ACh stimulated secretion whilst the bethanechol elicited secretion remained unaffected. In the presence of full nicotinic receptor blockade the ACh response curve was shifted to the left sixfold, half maximal stimulation being produced at 1.79 mumols/kg/h. Cimetidine partially inhibited the secretory responses elicited by either ACh or bethanechol while blockade of adrenoceptors (alpha and beta) did not affect acid output induced by cholinergic agonists. Secretion elicited by ACh is interpreted as being the composite effect of pro-secretory action and an inhibitory mechanism due to the activation of nicotinic receptors. Hexamethonium, through nicotinic receptor blockade, inhibits the restricting mechanism and thus reveals the full stimulatory action of ACh.

Acetylcholine↗
PubMed1985

Pharmacological profile of mifentidine: a novel H2-receptor antagonist.

Mifentidine, a representative compound of a novel class of H2-antagonists, has been investigated for its ability to interact with H2-receptors and to inhibit gastric acid secretion. Affinity estimates (KB) of mifentidine obtained from in vitro studies on cardiac and gastric mucosal histamine (H2) receptors were in the 20-50 nM range. Mifentidine appeared to be endowed with strong anti-secretory properties against histamine-stimulated secretion in the anaesthetized rat and in the conscious dog. Distinct features of mifentidine were considerable bioavailability and duration of anti-secretory effect.

Animals↗
PubMed1985

Nonprotein sulfhydryls as possible components of the protective effect of rosaprostol on the rat gastric mucosa.

Experiments were designed to examine the possibility that nonprotein sulfhydryl groups of the gastric mucosa could participate in the protection of rat gastric mucosa by rosaprostol (the Na salt of 9-hydroxy-8,12 trans-19,20-bis-nor-prostanoic acid). Gastric mucosal lesions and the content of nonprotein sulfhydryls were evaluated after orally administered absolute ethanol. Pretreatment with rosaprostol by gavage prevented gastric lesions and reduced or prevented the decrease of mucosal nonprotein thiols. N-ethylmaleimide, a sulfhydryl blocker, worsened the ethanol-induced gastric lesions and lowered further the non protein thiols. Both variables were improved by the PG analogue and by PGE2. These results suggest a possible role of endogenous nonprotein sulfhydryl groups in the gastric protective effect of rosaprostol.

Animals↗
PubMed1985

Pharmacology of mifentidine, a novel H2-receptor antagonist.

N1-[(4-Imidazolyl)-phenyl]-N2-isopropylformamidine (mifentidine, DA 4577 is a potent and selective H2 antagonist, representative of a new class of compounds, the imidazolylphenyl-formamidines, characterized by a semi-rigid structural conformation. Mifentidine appeared to be a specific and competitive antagonist of several histamine-mediated responses. Thus, in isolated guinea pig atria and ventricles it antagonized histamine chronotropic and dimaprit inotropic effects in a competitive manner providing affinity estimates (pA2) of 7.66 and 7.74, respectively. Mifentidine exerted potent antisecretory effects in: the isolated mouse stomach where it antagonized the acid promoting activity of histamine (EC50 3.28 mumol/l) but not that of bethanechol or db-cAMP (adenosine 3',5'-monophosphate); the lumen perfused stomach of the anaesthetized rat, inhibiting histamine (ED50 0.1 mumol/kg i.v.) and pentagastrin (ED50 0.2 mumol/kg i.v.) stimulated secretion; the pylorus ligated rat (ED50 1.35 mumol/kg i.v.); the gastric fistula dog, reducing the secretagogue effect of pentagastrin (ED50 96 nmol/kg i.v.); the conscious dog equipped with the Heidenhain pouch, where it was effective both following intravenous (ED50 119.7 nmol/kg) and oral administration (ED50 323.8 nmol/kg) in antagonizing histamine action. Mifentidine antisecretory effect, examined in the dog, appeared to last for a significantly longer time than that of ranitidine. Mifentidine was free of cardiovascular effects (on aortic blood pressure and heart rate) when administered repeatedly to the conscious dog at doses far above those needed to suppress acid secretion.

Animals↗
PubMed1984

Can pharmacologic hyperprolactinemia and breast-suction induce lactation in women with normal menstrual cycles?

Six women--age range 21/24--with regular ovulatory cycles, voluntarily underwent with L-Sulpiride (100 mg/die) from the 5th to the 19th day of the cycle. On the 13th, 14th and 15th day of therapy breast suction by syringe breast-pump was performed on each woman every 6 hours and for 4' from either breast. Milk secretion was poor and showed no noticeable increase in the three days of breast suction. L-Sulpiride-induced hyperprolactinemia combined with nipple stimulation-induced increased PRL secretion failed to stimulate milk secretion at a level comparable with physiologic lactation in puerperium.

Adult↗
PubMed1982

PRL action on E2 ovarian secretion.

5 Amenorrhea hyperprolactinemic women in previous intermittent treatment with bromocryptine, received bromocryptine for three periods of 5, 4, 3 days; each treatment phase was followed by a ten days suspension. During treatment and during suspension FSH, LH, PRL and E2 were tested. There was no significative variation of FSH and LH; PRL lowered during treatment and reached basal values during suspension. Ovarian response (E2) varies with PRL levels. There was a statistically significative negative correlation between PRL and 17-beta-E2.

Adult↗
PubMed1982

Gastric antisecretory, antiulcer and cytoprotective properties of 9-hydroxy-19,20-bis-nor-prostanoic acid in experimental animals.

9-Hydroxy-19,20-bis-nor-prostanoic acid (IBI-C83) was evaluated on gastric acid secretion and gastric lesions induced in laboratory animals by a variety of experimental conditions: compound IBI-C83 is proved effective in decreasing basal, histamine- and pentagastrin-stimulated total acid output in rats and in pentagastrin perfused dogs. The concentration of N-acetylneuraminic acid in the gastric fluid, a marker of mucus secretion, is enhanced in rats by IBI-C83. This drug prevents gastric damage induced by non-steroidal antiinflammatory compounds such as acetylsalicylic acid, indometacin and phenylbutazone, gastric ulcers following pylorus ligation, and facilitates healing of the gastric ulcers evoked by subserosal injection of acetic acid. A prominent feature of IBI-C83 is its capacity to protect the rat from gastric damage elicited by necrotizing agents such as absolute ethanol, hydrochloric acid and hypertonic saline. This property, called "cytoprotection" and common to naturally occuring prostaglandins, is independent on the antisecretory activity of IBI-C83 and is not shared, at least in the reported experimental models, by the H2-receptor antagonist cimetidine. In spite of the prostaglandin-like properties displayed in its cytoprotective activity, compound IBI-C83 does not affect cardiovascular functions, gastrointestinal transit and uterine motility.

Animals↗
PubMedDate not supplied

The effect of DAU 6215, a novel 5HT-3 antagonist, in animal models of anxiety.

The aim of the present study was to evaluate the effect of DAU 6215 (N-(endo-8-methyl-8-azabicyclo[3.2.1]oct-3-yl)-2, 3-dihydro-2-oxo-1H-benzimidazol-1-carboxamide, hydrochloride), which is a 5HT-3 receptor antagonist, chemically different from the other 5HT-3 antagonists, on a wide variety of animal models sensitive to anxiolytics. Nine animal models were used. DAU 6215 was active in reducing (i) aversion to a brightly lit environment in the light/dark exploratory test in mice, (ii) unpleasant properties of an aversive drug in rats (naloxone-induced place aversion), and (iii) aggressiveness in monkeys. DAU 6215 was effective at doses ranging (a) between 10 and 1000 micrograms/kg given i.p. in mice, (b) between 15 and 30 micrograms/kg given s.c. in rats and (c) between 1 and 10 micrograms/kg given orally in monkeys. DAU 6215 was inactive in (iv) the elevated plus maze, (v) conflict test and (vi) emotional hypophagia in rats and in (vii) the four plates test, (viii) staircase test and (ix) stress-induced hyperthermia in mice. Diazepam was active in all tests. In contrast to diazepam, DAU 6215 did not induce place preference, suggesting the possible lack of addictive properties.

Animals↗
PubMedDate not supplied

Medicinal chemistry of muscarinic agonists for the treatment of dementia disorders.

Alzheimer disease (AD) is a neurodegenerative disorder lacking an effective therapy. The etiology is controversial and among different drug strategies, the cholinergic approach has gained great interest owing to biochemical and pharmacological evidence of the crucial role of acetylcholine in cognitive functions. Several attempts exploiting the boosting of the cholinergic system are currently under way. Inhibitors of the acetylcholinesterase enzyme sustain the availability of the natural transmitter by limiting its removal from the synapse. In a different approach, exogenous agonists may substitute acetylcholine itself. In this way the issue of the extensive cholinergic cell loss occurring in AD and leading to a reduction of cholinergic functions, could be advantageously bypassed. Moreover the discovery of different muscarinic receptor subtypes, most notably the M1 subtype as that involved in the postsynaptic transmission, has offered new opportunities to face the problem in a very specific way. In this line of research, we have now identified BIMC 182 as a new functionally selective M1 agonist. Whereas its affinity for the different receptor subtypes is almost similar (radioreceptor binding), its functional selectivity is pointed out by specific "in vitro" models. BIMC 182 behaves as a full agonist at M1 (rat superior cervical ganglion, pD2 4.8) and as a partial agonist at M2 and M3 sites (g.p. heart pD2 = 5.4 and g.p. ileum pD2 = 4.5). The agonist profile is further confirmed in hm1 transfected CHO cells where the compound stimulates PI turnover. BIMC 182 penetrates well the brain as shown by the increase in the energy of the low frequency band (theta waves) in the cortical EEG of rabbits (3 mg/kg i.v.).(ABSTRACT TRUNCATED AT 250 WORDS)

Alzheimer Disease↗
PubMedDate not supplied

DAU 6215, a novel 5-HT3 receptor antagonist, improves performance in the aged rat in the Morris water maze task.

The effects of the new 5-HT3 receptor antagonist, DAU 6215, on aged rats' cognition were assessed in the Morris water maze task. Task performance of aged animals that received acutely the dose of 10 micrograms/kg IP was not different than that of their aged controls treated with the vehicle. Conversely, a repeated IP administration of 10 micrograms/kg DAU 6215 for 3 weeks significantly improved task performance of the aged animals as compared to that displayed by the old rats treated with the vehicle.

Aging↗
PubMedDate not supplied

Immunologic reconstitution by interleukin-2: facts and open questions.

Interleukin-2 (IL-2), one of the most potent immunoregulatory and inflammatory cytokines, is being tested in phase III clinical trials in order to demonstrate its efficacy in combination with current antiviral agents in preventing the occurrence of opportunistic infections and death in individuals infected by the human immunodeficiency virus (HIV). In the meantime, its capacity to boost the number of CD4+ T cells in peripheral blood has been confirmed by a number of individual phase I/II trials conducted in different countries by independent investigators. In the face of this remarkable result, little is known of the effects exerted by this cytokine once administered to infected individuals in terms of its impact on different immunologic functions. The recent acquisitions on the important role played by latently infected cells in in vivo infection in reinitiating HIV replication and cytopathicity once antiviral therapy is suspended or becomes suboptimal, has shed new light on the possibility of utilizing immunologic strategies, including IL-2, for eradicating the virus from latent reservoirs. Results from a clinical trial conducted at our Institute indicate a decrease in lymphocyte-associated HIV DNA after IL-2 administration, supporting this hypothesis.

Anti-HIV Agents↗
PubMedDate not supplied

A model for studying saliva secretion in the conscious dog.

Parotid saliva secretion was studied in conscious dogs in which a chronic fistula of the parotid duct was provoked by a simple surgical procedure. To validate the technique employed, the responsiveness of the gland to various stimuli was examined. The volume of secretion was measured as well as the concentrations of Na+, K+ and calcium. Secretion was elicited by administering bethanechol i.v. or by feeding a meat meal. These stimuli, applied repetitively in the same animal, evoked reproducible secretory responses. In addition, the dose-response curve to bethanechol could also be constructed. The parotid secretion is controlled by muscarinic receptor activation, as illustrated by atropine blockade and its insensitivity to adrenergic drugs. The preparation is a versatile model which allows to investigate secretion evoked by both direct and reflex activation. The advantages of the preparation, which avoids invasive techniques, are accurate measurements and reproducible responses over long periods in a conscious animal.

Animals↗