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Biomedical subjects

D Oliva

Publications and source records attributed to D Oliva.

107 records · Page 6Linked to original sources
PubMed1984

Binding sites for 3H-LTC4 in membranes from guinea pig ileal longitudinal muscle.

Leutriene (LTC4) is one of the components of Slow Reacting Substance of Anaphylaxis (SRS-A) and is a potent constrictor of guinea pig ilea. The contraction is likely to be a receptor-mediated process. Here we report the existence of specific binding sites for 3H-LTC4 in a crude membrane preparation from guinea pig ileal longitudinal muscle. At 4 degrees C in the presence of 20 mM Serine-borate, binding increases linearly with protein concentration, reaches equilibrium in 10 minutes, and is reversible upon addition of 3 x 10(-5) M unlabelled LTC4. The dissociation curve is consistent with the existence of more than one class of binding site. Ca++ and Mg++ greatly enhance the binding of 3H-LTC4 at equilibrium. In the presence of 5 mM CaCl2 and MgCl2 not only LTC4 (IC50 10(-7)M), but also LTD4 (albeit with much lower affinity, IC50 = 6 x 10(-5) M) and the SRS-A antagonist FPL 55712 (IC50 = 10(-5) M) can compete with 3H-LTC4 for its binding sites. FPL 55712 only displaces 60-70% of the total amount bound, while LTC4 displaces 90-95%. These studies indicate that multiple classes of binding sites exist for 3H-LTC4 in guinea pig ileal longitudinal muscle, and that at least part of these binding sites might be related to the ability of LTC4 to contract guinea pig ilea.

Animals↗
PubMed1984

Pharmacological studies on the mode of action of flavoxate.

Previous studies on the mode of action of flavoxate have shown that the drug exerts a selective and direct muscle relaxant activity. In order to study the mode of action of flavoxate, the following activities were investigated: calcium blocking, inhibition of cyclic AMP phosphodiesterase (PDE), local anaesthetic activity, the effects on the synthesis and release of prostaglandins. In the K+-depolarized guinea-pig taenia coli, contracted by CaCl2, flavoxate and papaverine showed a moderate calcium antagonistic activity. Anticholinergic drugs, such as atropine and emepronium, did not exert a similar action. The antispasmodic activity of a drug can be correlated with inhibition of cyclic AMP phosphodiesterase, and since papaverine is a potent PDE inhibitor, we tested flavoxate for this activity. Flavoxate exerted a PDE inhibitory activity about three and five times greater than that of aminophylline in tissues homogenates of guinea-pig ureter and urinary bladder, respectively. It also showed the same local anaesthetic activity of lidocaine. Finally, the synthesis and release of prostaglandins by urinary bladder muscle in vitro have been investigated before and after treatment with flavoxate. Myolytic activity of papaverine and flavoxate do not involve inhibition of prostaglandins synthesis in rat urinary bladder in vitro. Therefore, the mode of action of flavoxate can be related to a superimposition of myotropic, calcium antagonistic and local anaesthetic activity.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1983

Properties of cytosolic proteins that confer vasoactive intestinal polypeptide-sensitivity to rat brain adenylate cyclase.

Rat brain cortex, caudate nucleus and cerebellum contain one or more factors that confer Vasoactive Intestinal Polypeptide (VIP)-, dopamine (DA)- and norepinephrine (NE)-sensitivity to adenylate cyclase in the absence of added GTP. These factors also stimulate the basal activity of the enzyme. The activity is found in a 100 000 X g supernatant; has an apparent molecular weight greater than 450 000 daltons; is inactivated by pronase, alkaline phosphatase and ammonium sulphate, and partially degraded by trypsin; and is stable to heat and acidic treatment. The effect of the factors is additive with that of guanosine-5'-triphosphate (GTP), and is not abolished by guanosine 5'-0-(2-thiodiphosphate) (GDP-beta-S). These results suggest that stimulation of adenylate cyclase by VIP, and most likely by DA and NE, can be modulated by soluble proteins.

Adenylyl Cyclases↗
PubMed1982

VIP stimulates ACTH release and adenylate cyclase in human ACTH-secreting pituitary adenomas.

The effect of vasoactive intestinal polypeptide (VIP) on in vitro ACTH release and adenylate cyclase activity was investigated in human ACTH-secreting pituitary adenomas from 4 patients with Cushing's disease and 2 patients with Nelson's syndrome. In all the tumors tested, VIP elicited a dose-dependent stimulation of hormone release from adenoma fragments (90-247% at 10-7 M VIP) and of cAMP formation in membrane preparations (75-140% at 3 X 10-6 M VIP). Therefore a role of VIP in the control of ACTH secretion in human ACTH-secreting adenomas is suggested; a cAMP-dependent mechanism of action can also be hypothesized.

Adenoma↗
PubMed1981

[Anesthesia, blood glucose, insulin and plasma renin. Experimental research with althesin, thiopental and ketamine].

In the rat, narcotic doses of Althesin injected intraperitoneally did not modify blood glucose concentration nor plasma insulin concentration. On the contrary a reduction of blood glucose concentration, associated with an increase of plasma insulin concentration was observed when narcotic doses of thiopental and ketamine were. Plasma renin concentration decreased after injection of Althesin and thiopental while increased after injection of ketamine.

Alfaxalone Alfadolone Mixture↗
PubMedDate not supplied

Combined effects of vasoactive intestinal peptide and dopamine on adenylate cyclase in prolactin-secreting cells.

VIP stimulates adenylate cyclase activity of male and female rat anterior pituitaries and human prolactinomas, while dopamine inhibits the enzyme activity of female rat pituitaries and prolactinomas. A dopamine inhibited cyclase can be detected also in male rats provided the enzyme activity is increased by VIP. The analysis of the dose-response curves for one agent (VIP or dopamine) in the absence or in the presence of the other indicates that the two agents exhibit a different pattern of interaction in the different systems. In fact, in female rat pituitaries and in human prolactinomas, the curves for dopamine +/- VIP and for VIP +/- dopamine were parallel, indicating that the two agents exherted their effects independently from one another. On the contrary, in male rat pituitaries, the curves were definitively non parallel, that is, the inhibitory effect of dopamine was greatly amplified by VIP. In no case was the apparent affinity (EC50) of one agent modified by the presence of the other. It is concluded that two different modes of interaction between stimulatory and inhibitory neurohormones might exist at the level of adenylate cyclase from anterior pituitary cells.

Adenoma↗
PubMedDate not supplied

Using multiple microswitches to promote different responses in children with multiple disabilities.

We examined the use of multiple microswitches to enhance different responses and environmental control with two boys with multiple disabilities. Four and three microswitches were used for the two boys, respectively. The microswitches were introduced individually. Once responding was established, two or three microswitches would be simultaneously available to allow the boys a wider range of response opportunities and a greater, more differentiated environmental input. Data showed that both boys learned to respond to the individual microswitches. The simultaneous availability of two or three microswitches promoted high levels of cumulative responding. Implications of the findings are discussed.

Adolescent↗
PubMedDate not supplied

Evaluating a computer system used as a microswitch for word utterances of persons with multiple disabilities.

PURPOSE: To assess the effectiveness of a computer system used as a microswitch for word utterances of two adults with multiple disabilities. The system combined a new control software programme with a commercially available speech recognition programme. METHOD: Nine word utterances were targeted for each participant. The participant's emission of those utterances triggered the occurrence of related (favourite) stimuli during the intervention and the post-intervention check. RESULTS: Intervention data showed that (1) the participants increased the frequencies of the target utterances and (2) the computer system recognized about 80% of those utterances correctly, providing the participants with high levels of favourite stimulation. The post-intervention check showed comparable data with both participants. CONCLUSIONS: The computer system proved an adequate microswitch for word utterances. Based on this evidence, microswitch programmes could be extended beyond the use of conventional motor responses.

Abnormalities, Multiple↗
PubMedDate not supplied

Enabling a person with multiple disabilities and minimal motor behaviour to control environmental stimulation with chin movements.

PURPOSE: To assess whether a young man with multiple disabilities and minimal motor behaviour would learn to control environmental stimulation using chin movements and a mechanical microswitch. METHOD: The study was carried out according to an ABAB design in which A represented baseline and B intervention phases. The chin movements controlled the stimulation only during the intervention phases. A 2-month post-intervention check was conducted. RESULTS: The man increased the frequency of his chin movements, thus increasing the level of environmental stimulation, during the intervention phases. This performance was maintained at the post-intervention check. CONCLUSION: The use of chin movements is a practical strategy for enabling individuals with minimal motor movements to control environmental stimulation. Future research should examine whether similar types of movements may enable some individuals to control voice-output communication devices.

Abnormalities, Multiple↗
PubMedDate not supplied

An optic micro-switch for an eyelid response to foster environmental control in children with minimal motor behaviour.

This study assessed whether two children (11.9- and 9.7-years-old) with profound multiple disabilities and minimal motor behaviour could learn to control environmental stimulation using an eyelid response with a newly developed micro-switch. The response consisted of raising the eyelid markedly (i.e. by looking upward or opening the eyes widely). The micro-switch developed for this target response consisted of an electronically regulated optic sensor mounted on an eyeglasses' frame. Data showed that the children learned the target eyelid response to activate the micro-switch and to increase their level of environmental stimulation. Responding was largely maintained at a 2-month post-intervention check. These results indicate that continued work in this area has positive implications for the rehabilitation of children with most serious disabilities.

Child↗
PubMedDate not supplied

Micro-switch programmes for students with multiple disabilities and minimal motor behaviour: assessing response acquisition and choice.

This study assessed (a) whether three girls with multiple disabilities and minimal motor behaviour could acquire pairs of responses taught through micro-switch-based programmes and (b) how the girls would eventually choose between those responses. In relation to the choice issue, a response-choice analysis was conducted to find out whether possible differences in performance rates for the two responses were due to the stimuli linked to them and/or to potential response preferences. Results indicated that all three girls succeeded in the acquisition of the two responses programmed for them and showed clear response choices. The choices seemed to be largely motivated by the stimuli linked to the responses. Implications of these findings were discussed, including the need to assess their generality and extend the scope of the work in this area.

Adolescent↗
PubMedDate not supplied

[The capillary hemangioma of the stomach: an unusual cause of haemorrhage. Case report].

Gastric haemorrhages are common clinical emergencies which often directly involve the surgeon in diagnosis and treatment; among these, rare vascular neoplasms deserve particular attention. The Authors report a rare case of benign vascular tumour of the stomach, a capillary angioma. After a literature review they highlight the importance of specific exams to reveal these small neoformations which, generally, show up clinically with acute bleeding, which may be severe, and which may not be discovered if the clinical evaluation is not very detailed. The surgical excision supported by a frozen sections is the most effective treatment.

Endoscopy, Digestive System↗