Biomedical subjects

A Capasso

Publications and source records attributed to A Capasso.

At least 37 records · Page 2Linked to original sources

PubMed2000

New protopine alkaloids from Aristolochia constricta reduce morphine withdrawal in vitro.

The present study examines the effect of four new protopine alkaloids (1-4) isolated and purified from the aerial parts of Aristolochia constricta (Aristolichiaceae) on morphine withdrawal in vitro. The results of our experiments indicate that the pure compounds (1-4) significantly and in a concentration-dependent manner reduced the morphine withdrawal. The results of the present study suggest that these new protopine alkaloids may be potential anti-addictive agents.

Acetylcholine↗

PubMed2000

Adenosine receptors are involved in the control of acute naloxone-precipitated withdrawal: in vitro evidence.

The effects exerted by adenosine A1 and A2 receptor agonists and antagonists on the acute opiate withdrawal induced by morphine were investigated in vitro. Following a 4 min in vitro exposure to morphine, the guinea-pig isolated ileum exhibited a strong contracture after the addition of naloxone. The P1 adenosine receptor agonist, adenosine, was able to reduce dose-dependently naloxone-precipitaded withdrawal. The same effect was induced by the adenosine A1 receptor agonist, N6-Cyclopentyladenosine (CPA) whereas the selective adenosine A2A receptor agonist CGS 21680 increased the naloxone-precipitated withdrawal phenomenon. Dipyridamole, a blocker of adenosine reuptake, induced a significant reduction of morphine dependence. Caffeine, an adenosine receptor antagonist, significantly increased the naloxone-precipitated withdrawal effect in a concentration dependent manner. The same effect was observed with 8-phenyltheophylline (8PT), an A1 adenosine receptor antagonist, whereas 3,7-dimethyl-1-propargylxanthine (DMPX), an A2 adenosine receptor antagonist, reduced the naloxone-precipitated withdrawal phenomenon. The results of our experiments indicate that both A1 and A2 adenosine receptor agonists and antagonists are able to influence opiate withdrawal in vitro, suggesting an important functional interaction between the adenosine receptors and opioid withdrawal.

Adenosine↗

PubMed2000

Guinea-pigs treated with beta-endorphin fragments DTgammaE and DEgammaE exhibit reduced morphine inhibition of electrically-induced contractions.

The effect exerted by two gamma-endorphin derivatives (DTgammaE and DEgammaE) was investigated on morphine-induced inhibition on the electrically contractions of guinea pig ileum in vitro. Morphine (1x10(-8)-5x10(-8)-1x10(-7) M) dose dependently and significantly reduced the E.C. of guinea pig ileum, IC50=6.5x10(-8) M (Confidence limits: 3.7x10(-8)-9.1x10(-8)). DTgammaE and DEgammaEper se (1x10(-6)-5x10(-6)-1x10(-5) M) did not modify significantly the E.C. of guinea pig ileum. Furthermore, DTgammaE or DEgammaE injection 10-30-60 min before morphine, did not affect the inhibitory effect of morphine on the E.C. of guinea pig ileum. By contrast, ilea from guinea-pigs treated for 4 days with DTgammaE or DEgammaE (1 mg/Kg/i.p.) resulted less sensitive to the inhibitory effect of morphine, IC50=8.3x10(-7) M (Confidence limits: 1.4x10(-6)-3.5x10(-7)) for DTgammaE and IC50=7.7x10(-7) M (Confidence limits: 2.7x10(-6)-8.7x10(-7)) for DEgammaE. Our results indicate that chronic treatment of guinea pigs with DTgammaE or DEgammaE induces a significant reduction of the inhibitory effect of morphine on the E.C. of guinea-pig ileum thus confirming an important functional interaction between gamma-endorphin derivatives and opioid system.

Analgesics, Opioid↗

PubMed1999

Cathepsin D from the liver of the antarctic icefish Chionodraco hamatus exhibits unusual activity and stability at high temperatures1.

Cathepsin D was purified to homogeneity from the liver of Antarctic icefish by anion-exchange chromatography followed by affinity chromatography on concanavalin-A Sepharose. The purified enzyme showed a molecular mass of 40 kDa and displayed optimal activity at pH 3.0 with a synthetic chromogenic substrate. The N-terminal sequence of this proteinase was determined by automated Edman degradation and was used to design a primer for use in reverse-transcriptase polymerase chain reaction. The open reading frame of the cloned cDNA encoded an aspartic proteinase, which contained the experimentally determined N-terminal sequence. The predicted sequence (396 residues) had a high similarity with those of cathepsin D from various vertebrate sources, but was considerably different from that of nothepsin, a distinct aspartic proteinase described previously from Antarctic fish [1]. Determination of kinetic parameters for substrate hydrolysis showed that, at temperatures between 8 and 50 degrees C, the icefish cathepsin D had a higher specificity constant (kcat/Km) than human cathepsin D. The stability of both enzymes was measured at 50 degrees C and half-lives of 55 and 3 min were derived for icefish and human cathepsin D, respectively.

Amino Acid Sequence↗

PubMed1999

Further studies on the involvement of the arachidonic acid cascade in the acute dependence produced by mu, kappa and delta opioid agonists in isolated tissues.

The effects of phospholipase A2, cyclooxygenase-1, cyclooxygenase-2, and 5-lipoxygenase inhibitors on acute opiate withdrawal induced by selective mu, kappa and delta receptor agonists was investigated in vitro. After a 4 min in vitro exposure to D-Ala2-N-methyl-Phe-Gly5-ol)enkephalin (DAMGO; a highly selective mu agonist) and trans(+/-)-3,4-dichloro-N-methyl-N-(2(1pyrrolidynyl)-cyclohexyl)-+ ++benzeneacetamid (U50-488H; a highly selective K agonist) a strong contraction of the guinea pig isolated ileum was observed after the addition of naloxone. This effect was also observed when rabbit isolated jejunum was pretreated with deltorphin (a highly selective delta agonist). Mepacrine (a phospholipase A2 inhibitor), tolmetin (a selective cyclooxygenase-1 inhibitor) and meloxicam (a selective cyclooxygenase-2 inhibitor) treatment before or after DAMGO or U50-488H were able to both prevent and reverse the naloxone-induced contraction after exposure to the opioid agonists, in a concentration-dependent fashion. In addition, nordihydroguaiaretic acid (a 5-lipooxygenase inhibitor) was able to block the naloxone-induced contraction following exposure to DAMGO or U50-488H if injected either before or after the opioid agonist. In contrast, mepacrine, tolmetin, meloxicam and nordihydroguaiaretic acid did not affect the naloxone-induced contraction after exposure to deltorphin. The results of the present study confirm and extend a previous study performed with morphine indicating that arachidonic acid and its metabolites (prostaglandins and leukotrienes) are involved in the development of opioid withdrawal induced by selective mu and kappa opioid agonists whereas no effects were observed on withdrawal induced by the selective delta opioid agonist deltorphin.

Animals↗

PubMed1999

GABAB receptors are involved in the control of acute opiate withdrawal in isolated tissue.

1. The effects exerted by GABAB receptor agonists and antagonists on the acute opiate withdrawal induced by mu and k receptor agonists were investigated in vitro. 2. Following a 4 min in vitro exposure to morphine (less selective mu agonist), DAGO (highly selective mu agonist) and U50-488H (highly selective k agonist) the guinea-pig isolated ileum exhibited a strong contracture after the addition of naloxone. 3. The selective GABAB receptor agonist, baclofen, at concentration of 5 x 10(-9) - 1 x 10(-8) - 5 x 10(-8) M was able to reduce dose-dependently the naloxone-induced contracture after exposure to mu (morphine and DAGO) and k (U50-488H) opiate agonists. 4. Pretreatment with phaclofen (5 x 10(-9) - 1 x 10(-8) - 5 x 10(-8) M), a selective GABAB receptor antagonist, inhibited dose dependently baclofen antagonism on responses to both mu and k agonists. 5. The results of our experiments indicate that GABAB receptors are involved in the control of opiate withdrawal in vitro, confirming an important functional interaction between the GABAergic system and opioid withdrawal.

Animals↗

PubMed1999

Effect of somatostatin and its antagonist on morphine analgesia in mice.

AIM: To study the effects of somatostatin (SST) and its antagonist cyclo-(7-aminoheptanoyl-Phe-D-Trp-Lys-Thr [Bzl]) (SSA) on morphine-induced analgesia. METHODS: The pain assays were the hot plate and the tail flick test. RESULTS: SST or SSA per se administered intracerebrally at the doses of 0.1 and 1 mg/mouse did not change the pain threshold of mice both in the hot plate and in the tail flick test. However, at the higher dose (10 mg/mouse), SST and SSA decreased the pain threshold in the tail flick test only. SST and SSA administered at the dose of 0.1 mg/mouse did not change morphine-induced analgesia. By contrast, SST and SSA at the doses of 1 and 10 mg/mouse reduced morphine analgesia effects both in the hot plate as well as in the tail flick test. CONCLUSION: Our results indicate that SSA as well as SST may be useful in studying pain mechanisms.

Analgesia↗

PubMed1998

The role of nitric oxide in the development of opioid withdrawal induced by naloxone after acute treatment with mu- and kappa-opioid receptor agonists.

The present study investigated the possible role of nitric oxide (NO) in the development of the withdrawal contractures of guinea pig isolated ileum after acute activation of mu- and kappa-opioid receptors. After a 4-min in vitro exposure to morphine (mu-opioid receptor preferring, but not selective, agonist), [D-Ala2-N-methyl-Phe4-Gly5-ol-]enkephalin (DAMGO; highly selective mu-opioid receptor agonist), or trans(+/-)-3,4-dichloro-N-methyl-N-2(1-pyrrolidynyl)cyclohexyl-ben zeneacetamide (U50-488H; highly selective kappa-opioid receptor agonist), the guinea-pig isolated ileum exhibited a strong contracture after the addition of naloxone. L-N(G)-nitro arginine methyl ester (3-300 microM) injected 10 min before the opioid receptor agonists was able dose dependently to reduce the naloxone-induced contraction after exposure to mu- and kappa-opioid receptor agonists whereas D-N(G)-nitro arginine methyl ester at the same concentrations did not affect it. The inhibitory effect of L-N(G)-nitro arginine methyl ester on morphine, DAMGO and U50-488H withdrawal was dose dependently reversed by L-arginine (3-300 microM) but not by D-arginine. Finally, glyceryl trinitrate on its own (3-300 microM) significantly increased the naloxone-induced contraction after exposure to mu- and kappa-opioid receptor agonist and it was also able to reverse the inhibition of opioid withdrawal caused by L-N(G)-nitro arginine methyl ester. These results provide evidence that NO has a role in the development of opioid withdrawal and that mu- or kappa-opioid receptors are involved.

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

PubMed1998

Cadmium-induced differential accumulation of metallothionein isoforms in the Antarctic icefish, which exhibits no basal metallothionein protein but high endogenous mRNA levels.

Reverse transcriptase-mediated PCR has been used to isolate two distinct metallothionein (MT) cDNA species from RNA extracted from icefish liver, namely MT-I and MT-II. Northern blot analysis with these cDNA species revealed that significant endogenous levels of MT mRNA were present in liver tissues of normal animals despite the fact that no MT protein could be found accumulating in the same tissue. However, multiple injections of CdCl2 induced high levels of both MT mRNA and MT protein. Sequence analysis of the cDNA species that were present after cadmium injection revealed the presence of both isoforms. Quantification of the MT-I and MT-II transcripts from normal and heavy-metal-treated fish showed an alteration in the ratio of the MT isoform transcripts. Endogenous transcripts consisted mostly of MT-II, whereas the MT-I transcript was preferentially accumulated only in response to the cadmium salt. The protein encoded by each cDNA isoform was isolated from the heavy-metal-treated fish and the availability of the specific MT mRNA for translation was demonstrated by translation in vitro. These results show that: (1) there is a discrepancy between the significant endogenous levels of MT mRNA and the absence of MT protein; (2) the accumulation of MT in icefish liver can be triggered by heavy metals; (3) genes encoding distinct MT isoforms are differentially regulated by heavy metals.

Amino Acid Sequence↗

PubMed1998

Prevention of left ventricular hypertrophy by ACE-inhibitor, ramipril in comparison with calcium-channel antagonist, felodipine.

This perspective study was performed to demonstrate the prevention of left ventricular hypertrophy by ACE-inhibitor, ramipril, in hypertensives of recent onset. Thirty-four hypertensive patients, treated with ramipril (group I), and 32 controls who received another frequently employed drug (the calcium channel-antagonist, felodipine (group II), were evaluated. Neither of two groups received any anti-hypertensive drug and did not suffer from left ventricular hypertrophy. All selected patients underwent M-mode echocardiography for measuring the following parameters: diastolic diameter of left ventricle, (DDLV); systolic diameter of left ventricle (SDLV); inter-ventricular septum (IVS); thickness of the posterior wall (PW); and left ventricular mass index (LVMI). Two anti-hypertensive drugs reduce systemic hypertension the same way. But, in hypertensives receiving ramipril (group I), the echocardiographic parameters of the left ventricle increased non-significantly. On the other hand, in those treated with felodipine (II group), these parameters significantly changed. The mechanisms of non-increase in cardiac and non-cardiac proteins, due to the ACE-inhibitors, are illustrated.

Adult↗

PubMed1998

Rational design of dynorphin A analogues with delta-receptor selectivity and antagonism for delta- and kappa-receptors.

Substitution of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic) in place of Gly2 in dynorphin A-(1-13)-NH2 and -(1-11)-NH2 (DYN) analogues (1 and 2) decreased the affinity to the kappa, delta, and mu receptors, and kappa selectivity. The analogue [D-Ala2, des-Gly3]DYN (4), a chimera between deltorphin/dermorphin N-terminal tripeptide and DYN, was virtually inactive for kappa-sites while the affinities for delta- and mu-receptors remained essentially unchanged. The doubly substituted analogue [2',6'-dimethyl-L-tyrosine (Dmt1)-Tic2]DYN (3) exhibited high delta-affinity (Ki=0.39 nM) while mu- and kappa-affinities were only an order of magnitude less (4-5 nM). Bioactivity of [Tic2]DYN peptides (1-3) on guinea-pig ileum and rabbit jejunum revealed potent delta- and kappa-antagonism, while the delta agonist potency of 4 was comparable to DYN. Thus, conversion from a kappa-agonist to antagonist occurred with the inclusion of Tic into DYN analogues, similar to the appearance of antagonist properties with delta- and mu-opioid agonists containing a Tic2 residue.

Analgesics, Opioid↗

PubMed1998

Phytochemical and pharmacological studies of Guettarda acreana.

The present study examines the effects of the extracts [petroleum ether, CHCl3, CHCl3/MeOH (9:1) and MeOH], partially purified fractions and pure compounds from Guettarda acreana on the electrically induced contractions (E.C.I.) of the isolated guinea-pig ileum. The results of the experiments indicate that CHCl3/MeOH (9:1), MeOH extract, and the MeOH soluble part from CHCl3/MeOH extract tested at concentrations of 1.2, 2.5, and 5 micrograms/ml, dose-dependently reduced the guinea-pig ileum contractions. Furthermore, some partially purified fractions I-IV from the MeOH extract, each tested at the same concentrations of the extracts, and some pure compounds (6 x 10(-6), 3 x 10(-6), 1 x 10(-6) M) isolated from the above fractions significantly reduced, in a dose-dependent manner, the electrical contractions of the ileum. The active compounds were identified as the known indole alkaloids strictosidic acid, lyalosidic acid, 5 alpha-carboxystrictosidine, strictosidine, and sickingine, as well as the known quinic acid derivatives 5-caffeoylquinic acid, 4,5-dicaffeoylquinic acid, and shikimic acid by spectral data. Two known quinovic acid glycosides and a new triterpenic glycoside, quinovic acid 3 beta-O-alpha-rhamnopyranosyl-(1-->3)-(beta-glucopyranosyl-(1-->6)-beta- glucopyranoside, were also isolated and their structures established by NMR and M5 data.

Animals↗

PubMed1998

Flavonoids reduce morphine withdrawal in-vitro.

The effects of quercetin, flavone, catechin and chrysin on the naloxone-precipitated withdrawal contracture of the acute morphine-dependent guinea-pig ileum have been investigated in-vitro. After 4 min in-vitro exposure to morphine a strong contracture of guinea-pig isolated ileum was observed after the addition of naloxone. All the flavonoids, injected 10 min before morphine at concentrations between 10(-7) and 10(-5) M, were capable of blocking naloxone-induced contracture after exposure to morphine in a concentration-dependent fashion. IC50 values calculated for quercetin, flavone, catechin and chrysin were 2.7 x 10(-6), 7.3 x 10(-7), 8.5 x 10(-7) and 5.3 x 10(-6) M, respectively. These results suggest that flavonoids might play an important role in the control of morphine withdrawal.

Acetylcholine↗

PubMed1998

p53 mutations and DNA ploidy in colorectal adenocarcinomas.

The p53 tumour suppressor gene has an important role in the the maintenance of genome stability and its mutational inactivation may be at the origin of aneuploidy in cancer cells. The aim of this study was to determine whether p53 mutations were associated to DNA aneuploidy, as assessed by flow cytometry, in colorectal adenocarcinomas. Analysis of p53 mutations spectrum of the sorted nuclei was done by Denaturing Gradient Gel Electrophoresis (DGGE) and DNA sequencing. Overall, we studied 20 adenocarcinomas, the corresponding control mucosa, and 7 lymph node metastases. Five tumours (25%) were DNA diploid, while 15 tumours (75%) were composed of DNA aneuploid and diploid subpopulations. DNA diploid control mucosa and adenocarcinomas showed no p53 mutations, while 60% of the tumours with DNA aneuploidy had p53 mutations. Therefore, p53 mutations occurred significantly more often in DNA aneuploid than in DNA diploid tumours (p < 0.04, Fisher's exact test). Incidences of DNA aneuploidy and p53 mutations in lymph node metastases were 60 and 86%, respectively. In all tumours showing a p53 mutation, the wild-type allele was not or only bearly visible in DNA aneuploid cells suggesting that, in such cells, aneuploidy is accompanied by complete p53 functional inactivation. The present observations suggest that p53 mutations may have a role in the origin of aneuploidy at late stages of colorectal carcinogenesis.

Adenocarcinoma↗

PubMed1998

[Flow cytometry in prostate cancer. Evaluation of its feasibility for biopsy specimens and correlation with grading].

BACKGROUND: Pathologic staging and grading are the most important prognostic factors in prostatic cancer. Unfortunately, pathologic staging needs to be evaluated by surgical procedures; moreover, the proposed grading systems are largely based upon subjective histopathologic evaluations. In recent years, these problems have been approached with flow cytometry (FCM). The present study evaluates the significance of DNA ploidy of prostatic carcinoma assessed by FCM. MATERIALS AND METHODS: Microscopic slides from 132 core needle biopsies and 22 surgical specimens of prostatic carcinoma were reviewed and classified according to Gleason's score modified by Epstein et al. Formalin-fixed, paraffin-embedded tissue samples were prepared for FCM evaluation using standard techniques. Adequate histograms were obtained from 113 biopsies (85.6%) and from all the surgical specimens (100%). RESULTS: Among the 113 biopsy specimens, a statistically significant correlation was found between DNA ploidy and Epstein's grading, since high-grade neoplasms accounted for 40.38% of non-diploid cases and only for 21.33% of diploid cases (chi square = 5.8; p = 0.05). Moreover, tetraploid tumors were defined as a separate FCM category with an absolute prevalence (65.52%) of non-high grade neoplasms (chi square = 5.9; p = 0.05). Although not submitted to statistical analysis, data collected from surgical specimens showed similar distribution. CONCLUSIONS: DNA ploidy assessment by FCM is a viable procedure in the majority of needle biopsy tissue samples of prostatic carcinoma; it may produce prognostic parameters with greater objectivity than conventional histologic grading.

Adenocarcinoma↗

PubMed1997

A novel white laccase from Pleurotus ostreatus.

Two laccase isoenzymes (POXA1 and POXA2) produced by Pleurotus ostreatus were purified and fully characterized. POXA1 and POXA2 are monomeric glycoproteins with 3 and 9% carbohydrate content, molecular masses of about 61 and 67 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis, of about 54 and 59 kDa by gel filtration in native conditions, and of 61 kDa by matrix-assisted laser desorption ionization mass spectrometry (only for POXA1) and pI values of 6.7 and 4.0, respectively. The N terminus and three tryptic peptides of POXA1 have been sequenced, revealing clear homology with laccases from other microorganisms, whereas POXA2 showed a blocked N terminus. The stability of POXA2 as a function of temperature was particularly low, whereas POXA1 showed remarkable high stability with respect to both pH and temperature. Both enzymes oxidize syringaldazine and ABTS (2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) together with a variety of different substituted phenols and aromatic amines with the concomitant reduction of oxygen, but POXA1 is unable to oxidize guaiacol. Both enzymes were strongly inhibited by sodium azide and thioglycolic acid but not by EDTA. UV/visible absorption spectra, atomic adsorption, and polarographic data indicated the presence of 4 copper atoms/mol of POXA2 but only one copper, two zinc, and one iron atoms were found/mol of POXA1. The neutral pI and the anomalous metal content of POXA1 laccase render this enzyme unique in its structural characteristics. The lack of typical absorbance at 600 nm allows its classification as a "white" laccase.

Amino Acid Sequence↗

PubMed1997

Design of mu selective opioid dipeptide antagonists.

We have recently designed potent delta selective opioid antagonist dipeptides on the basis of a simple conformational analysis. Following a similar procedure we found a mu selective dipeptide antagonist, 2,6-dimethyl-Tyr-D-Phe-NH2. Although its selectivity is not as high as those of the quoted delta selective dipeptides it has good in vitro activity and looks very promising for further development since the 2,6-dimethyl-Tyr-D-Phe message, like the delta selective 2,6-dimethyl-Tyr-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid counterpart, seems able to impart antagonism to longer peptides.

Animals↗

PubMed1997

Synthesis and pharmacological activity of deltorphin and dermorphin-related glycopeptides.

The solid phase procedure, based on the Fmoc chemistry, was used to prepare some opioid deltorphin (H-Tyr-D-Ala-Phe-Asp-Val-Val-Gly-NH2, DEL C) and dermorphin (H-Tyr-D-Ala-Phe-Gly-Tyr-Pro-Ser-NH2, DER) analogues in which a D-glucopyranosyl moiety is beta-O-glycosidically linked to a Thr4 or Thr7 side chain. Their activities were determined in binding studies based on displacement of mu- and delta-receptor selective radiolabels from rat brain membrane synaptosomes, in guinea pig ileum and rabbit jejenum bioassays, and, in vivo, by a mouse tail-flick test after intracerebroventricular (icv) and subcutaneous (sc) administrations. The glyco analogues modified at position 4 displayed low opioid properties, while Thr7-glycosylated peptides retained high delta- or mu-selectivity and remarkable activity in vivo. In particular, as systemic antinociceptive agents, the latter glucoside-bearing compounds were more potent than the parent unglycosylated peptide counterparts, showing a high blood to brain rate of influx which may be due to the glucose transporter GLUT-1.

Amino Acid Sequence↗