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Biomedical subjects

L Negri

Publications and source records attributed to L Negri.

At least 19 recordsLinked to original sources
PubMed2001

Autoradiographic mapping of the opioid receptor-like 1 (ORL1) receptor in the brains of mu-, delta- or kappa-opioid receptor knockout mice.

The opioid receptor-like 1 (ORL1) receptor shares a high degree of sequence homology with the classical mu-, delta- and kappa-opioid receptors and a functional mutual opposition between these receptors has been suggested. To further address this possible interaction we have used mu-, delta- and kappa-opioid receptor knockout mice to determine autoradiographically if there are any changes in the number or distribution of the ORL1 receptor, labelled with [(3)H]nociceptin, in the brains of mice deficient in each of the opioid receptors. An up-regulation of ORL1 expression was observed across all brain regions in delta-knockouts with cortical regions typically showing a 15-30% increase in binding that was most marked in heterozygous mice. In contrast, ORL1 receptor expression was down-regulated in virtually all brain structures in heterozygous kappa-knockouts although the magnitude of this change was not as great as for the delta-knockouts. No significant alterations in ORL1 receptor expression were observed across brain regions in mu-receptor knockout mice and there were no qualitative differences in ORL1 receptor expression in any groups. These data suggest there are interactions between the ORL1 system and the classical opioid receptors and that the interactions are receptor-specific. The greater differences observed in heterozygous mice suggest that these interactions might be most relevant when there is only partial loss of receptor function.

Animals↗
PubMed2001

Activity of mu- and delta-opioid agonists in vas deferens from mice deficient in MOR gene.

1. Mice lacking the mu-opioid receptor have been recently generated. Centrally mediated responses of mu-opioid agonists are suppressed whereas some of the delta-opioid responses are preserved in these mutant mice. 2. The vas deferens bioassay has been used in this study to investigate the functional activity at a peripheral level of mu- and delta-opioid agonists in mice lacking mu-opioid receptors. 3. The different mu-opioid agonists evaluated, morphine, DAMGO, dermorphin and [Lys(7)]-dermorphin produced an inhibitory response in vas deferens from wild-type mice but had no relevant activity on vas deferens from mutant mice. 4. The selective delta-opioid agonists DPDPE, BUBU, deltorphin I, deltorphin II and [D-Met(2)]-deltorphin induced inhibitory effects in vas deferens from both wild-type and mutant mice. However, the biological activities of these ligands were slightly reduced in preparations from mutant mice. The inhibitory responses of all these delta-opioid agonists were prevented by the administration of the selective delta-opioid antagonist naltrindole. 5. These data indicate that delta-opioid agonists, but not mu-opioid agonists, are biologically active in vas deferens from mice lacking mu-opioid receptors. The decreased response of delta-agonists in mutant mice suggests that some cooperativity may exist between mu- and delta-opioid receptors in these vas deferens preparations.

Analgesics, Opioid↗
PubMed2001

HS-599: a novel long acting opioid analgesic does not induce place-preference in rats.

1. When administered subcutaneously HS-599, a new didehydroderivative of buprenorphine (18,19-dehydrobuprenorphine), produced a long-lasting antinociceptive response in rats. Its potency exceeded twice that of buprenorphine. In the tail-flick test it acted as a full agonist but in the plantar test only as a partial agonist. Whereas the mu-opioid antagonists naloxone and naltrexone antagonized HS-599 antinociception the delta-opioid antagonist naltrindole and the kappa-opioid antagonist nor-binaltorphimine did not. 2. Unlike buprenorphine and morphine, HS-599 never induced conditioned place-preference in rats. 3. In radioligand binding assays, compared with buprenorphine HS-599 had 3 fold higher mu-opioid receptor affinity but lower delta- and kappa-opioid receptor affinity. 4. In isolated guinea-pig ileum preparations, HS-599 only partially inhibited the electrically-stimulated contraction, acting as a partial opioid agonist. When tested against the mu-opioid receptor agonist dermorphin, it behaved as a non-equilibrium antagonist. Conversely, in mouse vas deferens (rich in delta-opioid receptors) and rabbit vas deferens preparations (rich in kappa-opioid receptors) HS-599 acted as a pure equilibrium antagonist, shifting the log-concentration-response curves of the delta-opioid agonist deltorphin I and the kappa-opioid agonist U-69593 to the right. 5. In conclusion, HS-599 is a novel buprenorphine derivative with higher affinity, selectivity and potency than the parent compound, for mu-opioid receptors. It produces intense and long-lasting antinociception and does not induce place-preference in rats.

Analgesics, Opioid↗
PubMed2001

Haemolysis due to active venous drainage during cardiopulmonary bypass: comparison of two different techniques.

To facilitate mini-access for cardiac surgery, two different methods of active venous drainage are used: vacuum assisted drainage and centrifugal pump aspiration on the venous line. The aim of this study was to compare the haemolysis produced using these two techniques. From June to December 1999, 50 consecutive patients were operated on using a ministernotomy. All of these patients had valvular surgery for either valve repair or valve replacement (9 MVRepair, 11 MVR, 29 AVR, 1 AVR + MVR). They were randomized into two groups: Group A, 25 patients who underwent surgery where vacuum assisted drainage was used, and Group B, 25 patients where kinetic asssisted venous drainage with centrifugal pump venous aspiration was used. Patient characteristics of both groups were similar for age, gender, body weight, body surface area, height, cardiopulmonary bypass (CPB) time, aortic crossclamp time, priming volume, cardioplegia volume, haemoglobin concentration, haematocrit, serum creatinine, bilirubin, lactate dehydrogenase (LDH), serum glutamic oxaloacetic transaminase (sGOT), serum glutamic pyruvic transaminase (sGPT), aptoglobin, reticulocytes, and platelet count. We checked all these laboratory parameters preoperatively, at the end of CPB, and 2 and 24 h after operation. We also checked haemoglobinuria at these same time points. We assessed blood loss at 6, 12, and 24 h after the operation and calculated total postoperative bleeding. There was a tendency towards a greater increase in LDH, sGOT and sGPT in Group A more than in Group B, but these data did not reach statistical significance. Platelet count was always lower in Group A and aptoglobin increased in Group A more than in Group B. More patients in Group A had haemoglobinuria. These findings indicate that haemolysis is increased more in patients treated with vacuum assisted drainage, when compared to the rise in haemolysis in those treated with centrifugal pump venous drainage. Total bleeding is also greater in Group A.

Adult↗
PubMed2000

Pharmacology of amphibian opiate peptides.

In 1980 the skin of certain frogs belonging to the genus Phyllomedusinae was found to contain two new peptides that proved to be selective mu-opioid agonists, and named dermorphins. Since 1987 deltorphins, a family of highly selective delta-opioid peptides were identified either by cloning of the cDNA from frog skins or isolation of the peptides. The distinctive feature of opioid peptides is the presence of a naturally occurring D-enantiomer at the second position in their common N-terminal sequence, Tyr-D-Xaa-Phe. The discovery of the amphibian opiate peptides, provided new insights into the functional role of the mu- and delta-opiate systems. It also provided models for novel analgesics with enhanced therapeutic benefits and reduced toxicity.

Animals↗
PubMed2000

[Doppler color ultrasonography in the diagnosis of erectile dysfunction of vascular origin].

The aim of this paper is to evaluate whether echo-color Doppler diagnostics allows to detect the different evolutionary stages of arteriopathy affecting the cavernous arteries of the penis. 124 patients with erectile deficiency were examined. All of them were evaluated by andrologic and psychologic anamnesis. An echo-color Doppler examination was performed on cavernous arteries before (basal) and after (dynamic) an injection of Prostaglandin E1 (10 micrograms). The penile circulation has been observed for twenty minutes after the injection to detect anomalous collateral vessels of the cavernous arteries. The population was divided into 4 groups according to the basal and dynamic peak systolic velocity (PSV). Cardiovascular risk factor incidence in patients with normal basal and dynamic PSV values (group A) and in patients with pathologic basal and dynamic PSV values (group C) is 10% and 44% respectively (p < 0.002). Psychologic disorder in group A and C is 41% and 26% respectively (p < 0.05). Patients with pathologic basal PSV and normal dynamic PSV (group B) show an intermediate (26%) incidence of cardiovascular disorders as compared to A and C. Anomalous side branches are equally represented in A and B (41% and 38%) and to a lesser extent in C (26%). Based on anamnestic and instrumental data, Group B ranges at an intermediate position between A and C. In this group, the presence of incipient arteriopathy affecting the penile circulation may be suspected. The ability to detect patients with vascular diseases still at a subclinical stage, as it already happens for other organs, would allow a prompt therapeutic action.

Adult↗
PubMed1999

Bv8, a small protein from frog skin and its homologue from snake venom induce hyperalgesia in rats.

From skin secretions of Bombina variegata and Bombina bombina, we isolated a small protein termed Bv8. The sequence of its 77 amino acids was established by peptide analysis and by cDNA cloning of the Bv8 precursor. Bv8 stimulates the contraction of the guinea-pig ileum at nanomolar concentrations. The contraction is not inhibited by a variety of antagonists. Injection of a few micrograms of Bv8 into the brain of rats elicits, as assessed by the tail-flick test and paw pressure threshold, a marked hyperalgesia which lasts for about 1 h. Bv8 is related to protein A, a component of the venom of the black mamba. After i.c.v. injection, protein A is even more active than Bv8 in inducing hyperalgesia.

Amino Acid Sequence↗
PubMed1999

Effects of antisense oligonucleotides on brain delta-opioid receptor density and on SNC80-induced locomotor stimulation and colonic transit inhibition in rats.

1. To reduce the density of delta-opioid receptor protein, five antisense phosphorothioate oligodeoxynucleotides (aODN), targeting the three exons of rat delta-opioid receptor mRNA (DOR), were injected twice daily for 4 days or continuously infused for 7 days into brain lateral ventricles (i.c.v.) of Sprague-Dawley rats. Rats acting as controls were infused or injected with a mismatch sequence (mODN) of each aODN. The density of opioid receptors in rat brain membranes was measured by saturation binding experiments using selective ligands for delta, mu and kappa opioid receptors. 2. aODNs injected twice a day for 4 days left rat brain delta-opioid receptor density unchanged. The ODN targeting the DOR nucleotide sequence 280 - 299 (aODN280 - 299, exon 2), decreased brain delta-opioid receptor density significantly more than aODNs targeting exon 1 (aODN239 - 258), exon 2 (aODN361 - 380), or exon 3 (aODN741 - 760) (to 52% vs 79, 72, and 68%). None of the aODNs to the DOR changed the brain density of mu- or k-opioid receptors. 3. When in a novel environment (but not when kept in their home cages), the locomotor activity of aODN280 - 299 treated rats was significantly lower than that of saline or mODN treated rats. The delta-opioid agonist SNC80 (5 mg kg-1, s.c.) significantly and potently stimulated locomotion and delayed colonic propulsion in saline- and mODN-infused rats, but left motor behaviour and colonic transit of delta-knockdown rats unchanged. 4. The baseline nociceptive threshold and the antinociceptive response to morphine were unchanged in delta-knockdown rats.

Analgesics, Opioid↗
PubMed1999

Perineal floor efficiency in sexually potent and impotent men.

Given the knowledge that the ischiocavernous and bulbocavernous muscles are involved in the erection of the penis, we studied the voluntary contractile activity of the perineal floor muscles in sexually potent and impotent men to investigate whether or not a different muscular efficiency can be found in these subjects. The activity of perineal floor muscles was studied in 76 sexually potent men and in 97 impotent men matched by age. A further group of 217 older impotent men was also studied to verify the impact of age on the efficiency of perineal floor contraction. The average myoelectrical activity of 24 maximized contractions of the perineum was measured in microV by anal plug electromyography. Perineal floor muscle contraction was significantly higher (P = 0.0007) in potent than in impotent men matched by age. In addition, in older impotent men the less perineal floor efficiency was also negatively correlated to age (r = -0.21, P = 0.002). Our results clearly demonstrated that a reduction of contractile activity of perineal muscles may be related to erectile dysfunction in younger men and an additional influence of age on perineal floor efficiency can be present in older impotent men.

Adolescent↗
PubMed1999

Differential knockdown of delta-opioid receptor subtypes in the rat brain by antisense oligodeoxynucleotides targeting mRNA.

Two antisense oligodeoxynucleotides (A-ODN), targeting delta-opioid receptor mRNA (DOR) and two mismatch ODN sequences (mODN) were continuously infused for 24 days into the lateral brain ventricles of Wistar rats. The density of delta-opioid receptors in rat brain homogenates was measured by saturation binding experiments using four selective ligands, two agonists ([D-Ala2, Glu4]-deltorphin and DPDPE) and two antagonists (Dmt-Tic-OH and naltrindole), and by immunoblotting SDS solubilized receptor protein. In brain membranes of mODN or saline-infused rats, the rank order of delta-opioid receptor density, calculated by Bmax values of the four delta-opioid receptor ligands, was: [D-Ala2, Glu4]deltorphin approximately Dmt-Tic-OH approximately naltrindole (86-118 fmo/mg protein) > DPDPE (73.6+/-6.3 fmol/mg protein). At the end of the 24 day infusion of A-ODN targeting DOR nucleotide sequence 280299 (A-ODN280-299), the Bmax of DPDPE (62.4+/-3.2 fmol/mg protein) was significantly higher than that of Dmt-Tic-OH (31.5+/-3.9 fmol/mg protein). Moreover, both the Kd value for DPDPE saturation binding and the Ki value for Dmt-Tic-OH displacement by DPDPE were halved. In contrast, an A-ODN treatment targeting exon 3 (A-ODN741-760) decreased the specific binding of [D-Ala2, Glu4]deltorphin and Dmt-Tic-OH significantly less (67%-81%) than the binding of DPDPE (53%), without changes in DPDPE Ki and KD values. No A-ODN treatment modified the specific binding of the micro-opioid agonist DAMGO and of the k-selective opioid receptor ligand U69593. On the Western blot of solubilized striatum proteins, A-ODN(280-299) and A-ODN(741-760) downregulated the levels of the DOR protein, whereas the corresponding mODN were inactive. The 24-day infusion of A-ODN(280-299) inhibited the rat locomotor response to [D-Ala2, Glu4]deltorphin but not to DPDPE. Intracerebroventricular (i.c.v.) infusion of A-ODN(741-760) reduced the locomotor responses to both delta-opioid receptor agonists, whereas mODN infusion never affected agonist potencies. In conclusion, these results demonstrate that 24-day continuous i.c.v. infusion of A-ODN targeting the nucleotide sequence 280-299 of DOR can differentially knockdown delta1 and delta2 binding sites in the rat brain.

Animals↗
PubMed1999

Divided vertical banded gastroplasty either for correction or as a first-choice operation.

BACKGROUND: Staple-line disruption may occur after vertical banded gastroplasty (VBG). METHODS: Since May 1996, the authors have performed the gastric restrictive procedure divided VBG, as described by MacLean, as a first-choice operation and not only as correction for staple-line breakdown. Divided VBG was done in 111 patients, 32 as correction after staple-line disruption and 79 as a first choice, 29 of them by hand-assisted laparoscopy with the dexterity pneumosleeve. RESULTS: Weight loss and nutritional status have been very satisfactory. Operating time for the standardized operation has been no longer than 60 minutes. CONCLUSION: Divided VBG, especially if done by hand-assisted laparoscopy using the dexterity pneumosleeve, is a valid restrictive procedure.

Adult↗
PubMed1998

Activity of the delta-opioid receptor is partially reduced, whereas activity of the kappa-receptor is maintained in mice lacking the mu-receptor.

Previous pharmacological studies have indicated the possible existence of functional interactions between mu-, delta- and kappa-opioid receptors in the CNS. We have investigated this issue using a genetic approach. Here we describe in vitro and in vivo functional activity of delta- and kappa-opioid receptors in mice lacking the mu-opioid receptor (MOR). Measurements of agonist-induced [35S]GTPgammaS binding and adenylyl cyclase inhibition showed that functional coupling of delta- and kappa-receptors to G-proteins is preserved in the brain of mutant mice. In the mouse vas deferens bioassay, deltorphin II and cyclic[D-penicillamine2, D-penicillamine5] enkephalin exhibited similar potency to inhibit smooth muscle contraction in both wild-type and MOR -/- mice. delta-Analgesia induced by deltorphin II was slightly diminished in mutant mice, when the tail flick test was used. Deltorphin II strongly reduced the respiratory frequency in wild-type mice but not in MOR -/- mice. Analgesic and respiratory responses produced by the selective kappa-agonist U-50,488H were unchanged in MOR-deficient mice. In conclusion, the preservation of delta- and kappa-receptor signaling properties in mice lacking mu-receptors provides no evidence for opioid receptor cross-talk at the cellular level. Intact antinociceptive and respiratory responses to the kappa-agonist further suggest that the kappa-receptor mainly acts independently from the mu-receptor in vivo. Reduced delta-analgesia and the absence of delta-respiratory depression in MOR-deficient mice together indicate that functional interactions may take place between mu-receptors and central delta-receptors in specific neuronal pathways.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗
PubMed1998

A new opioid peptide predicted from cloned cDNAs from skin of Pachymedusa dacnicolor and Agalychnis annae.

We have isolated a cDNA encoding a precursor of dermorphin from the skin of Pachymedusa dacnicolor. Besides four copies of this opioid peptide, the deduced sequence also contains the genetic information for a novel peptide Tyr-Ile-Phe-His-Leu-Met-Asp-NH2. This differs from Met-deltorphin by the presence of Ile at position 2. In a related precursor from the skin of Agalychnis annae, the sequence of this peptide is in the 3'-untranslated region of the cloned cDNA. From earlier results we predict that in skin peptides the second residue is D-allo-Ile. We have synthesized this and related peptides with different D-amino acids, and determined their delta agonist activity. The peptide with D-nor-Leu binds with high affinity to delta receptors, while that with D-allo-Ile is about 100 times less active.

Amino Acid Sequence↗
PubMed1998

Respiratory and cardiovascular effects of the mu-opioid receptor agonist [Lys7]dermorphin in awake rats.

1. Changes in respiratory variables, arterial blood pressure and heart rate were studied in awake rats after injection of the opioid peptide [Lys7]dermorphin and its main metabolites, [1-5]dermorphin and [1-4]dermorphin. 2. Fifteen minutes after injection, doses of [Lys7]dermorphin producing antinociception (i.c.v., 36-120 nmol; s.c., 0.12-4.7 micromol kg(-1)) significantly increased respiratory frequency and minute volume of rats breathing air or hypoxic inspirates. This respiratory stimulation was reversed to depression by the 5-HT receptor antagonist ritanserin (2 mg kg(-1), s.c.), was blocked by naloxone (0.1 mg kg(-1), s.c.), significantly reduced by the mu1 opioid receptor antagonist naloxonazine (10 mg kg(-1), s.c., 24 h before) but unaffected by peripherally acting opioid antagonist naloxone methyl bromide (3 mg kg(-1), s.c.). Forty five minutes after injection, doses of the peptide producing catalepsy (s.c., 8.3-14.2 micromol kg(-1), i.c.v., 360 nmol) significantly reduced respiratory frequency and volume of rats breathing air and blocked the hypercapnic ventilator response of rats breathing from 4% to 10% CO2. I.c.v. administration of [1-5]dermorphin and [1-4]dermorphin (from 36 to 360 nmol) never stimulated respiration but significantly reduced basal and CO2-stimulated ventilation. Opioid respiratory depression was only antagonized by naloxone. 3. In awake rats, [Lys7]dermorphin (0.1-1 mg kg(-1), s.c.) decreased blood pressure. This hypotensive response was abolished by naloxone, reduced by naloxone methyl bromide and unaffected by naloxonazine. 4. In conclusion, the present study indicates that analgesic doses of [Lys7]dermorphin stimulate respiration by activating central mu1 opioid receptors and this respiratory stimulation involves a forebrain 5-hydroxytryptaminergic excitatory pathway.

Analgesia↗