Biomedical subjects

G Greco

Publications and source records attributed to G Greco.

At least 127 records · Page 7Linked to original sources

PubMed1994

A comparative molecular field analysis model for 6-arylpyrrolo[2,1-d] [1,5]benzothiazepines binding selectively to the mitochondrial benzodiazepine receptor.

A series of 42 6-arylpyrrolo[2,1-d][1,5]benzothiazepines, which we have recently described as selective ligands of the mitochondrial benzodiazepine receptor (MBR) (Fiorini I.; et al. J. Med. Chem. 1994, 37, 1427-1438), have been investigated using the comparative molecular field analysis (CoMFA) approach. The resulting 3D-QSAR model rationalizes the steric and electronic factors which modulate affinity to the MBR with a cross-validation standard error of 0.648 pIC50 unit. A set of seven novel pyrrolobenzothiazepine congeners has successively been synthesized and tested. The CoMFA model forecasts the binding affinity values of these new compounds with a prediction standard error of 0.536.

Animals↗

PubMed1994

Novel ligands specific for mitochondrial benzodiazepine receptors: 6-arylpyrrolo[2,1-d][1,5]benzothiazepine derivatives. Synthesis, structure-activity relationships, and molecular modeling studies.

A novel class of ligands specific for MBR receptors has been identified: 6-arylpyrrolo[2,1-d][1,5]benzothiazepine derivatives. The majority of newly synthesized esters 37-64 as well as some intermediate ketones showed micro- or nanomolar affinity for [3H]PK 11195 binding inhibition. A SAR study on 42 compounds and a molecular modeling approach led to a preliminary structural selectivity profile: the 6,7-double bond, the carbamoyloxy, alcanoyloxy, and mesyloxy side chains at the 7-position, and the prospective chloro substitution at the 4-position seemed to be the most important structural features improving affinity. Therefore, 7-[(dimethylcarbamoyl)oxy]- and 7-acetoxy-4-chloro-6-phenylpyrrolo[2,1-d][1,5]benzothiazepine (43 and 57) were synthesized. With 7-[(dimethylcarbamoyl)oxy]-6-(p-methoxyphenyl)pyrrolo[2,1- d][1,5]benzothiazepine (65), these were the most promising compounds with IC50s of respectively 9, 8, and 9 nM, under conditions where PK 11195 had an IC50 of 2 nM.

Analgesics↗

PubMed1994

Effects of variable selection on CoMFA coefficient contour maps in a set of triazines inhibiting DHFR.

An example of a CoMFA study is described with the aim to discuss one of the major problems of this 3D QSAR method: lack of variable selection. It is shown that the use of nonrelevant energy parameters might produce CoMFA contour maps which poorly reflect the actual nature of the binding site and are in part statistical artefacts. The data set employed in our analysis comprises triazine inhibitors of dihydrofolate reductase (DHFR), isolated from chicken liver, which have already been the object of a QSAR study by other authors. Since three-dimensional structures of triazine-DHFR complexes are known, it was possible not only to reduce ambiguities in the superimposition of the ligands, but also to compare the resulting CoMFA contour maps with the enzyme active site.

Amino Acid Sequence↗

PubMed1994

Morphological and pathogenetic aspects of proliferative vitreo-retinopathy. A histological and immunohistochemical study.

Proliferative vitreo-retinopathy (PVR) and subretinal membrane proliferation are the most common complication and cause of failure in retinal-detachment (RD) surgery. In this study, material withdrawn from 21 patients was observed. The vitreal taps of 16 bulbs affected by PVR and which had undergone vitrectomy, along with 5 bulbs obtained by enucleation, were stained with Hematoxylin Eosin and studied immunohistochemically. The cells involved in this proliferative tissue include macrophages, cellular elements of pigmented epithelium origin, fibroblasts and myofibroblasts. From the examination of enucleated bulbs, we can easily recognize that the cellular components of the membrane are represented by fibroblasts, capillaries, and occasional macrophages; meanwhile, PE cells remain at the base of the newly formed tissue.

Adult↗

PubMed1994

The importance of secondary anchor residue motifs of HLA class I proteins: a chemometric approach.

In this paper we report a chemometric approach to Quantitative Structure-Activity Relationship (QSAR) analysis applied to a study of the binding of peptides to Major Histocompatibility Complex (MHC) class I proteins. Peptides which possess the known primary anchor residue motif for HLA-B27 binding do not necessarily bind to HLA-B27 proteins. Secondary anchor residues are also involved, but it is not yet clear which amino acids are required or in which positions. A classic approach to this problem would be to synthesize multiple peptides each varying by a single amino acid from a starting peptide, and test them for their binding properties. Not only is this approach inefficient, but it is essentially unable to provide information about possible mutual interactions of amino acid residues in different positions. Using a statistical design to select the most informative compounds to use in the QSAR study, it was possible to analyse the effects on HLA-B27 peptide binding of different amino acids in four positions by means of only nine peptides. The relative binding activity of these peptides could then be modeled mathematically to provide information about the relative contribution of each of the four positions and to suggest a new peptide with high binding affinity. Our results demonstrate the usefulness of the chemometric strategy for studying peptides of interest in molecular immunology.

Amino Acid Sequence↗

PubMed1994

The peptide-binding specificity of HLA-B27 subtype (B*2705) analyzed by the use of polyalanine model peptides.

Model peptides have been used to quantitate the effect on HLA-B*2705 binding of the spacing between primary anchor residues, the type of amino acid accepted in the P9 anchor position, and the type of amino acid accepted in the "secondary anchor positions" P3 and P7. Peptide binding was measured by the HLA class I alpha-chain-refolding assay. The results obtained show that (a) Among the model peptides differing in the spacing between anchor residues, the nonamer with Arg in P2 and Lys in P9 (R2, K9) has the maximum binding with B*2705 molecule. The decamer, with an extra Ala inserted between Arg and Lys (R2, K10), has much lower binding, and still lower binding is observed for the octamer, where an Ala is removed (R2, K8). (b) Besides the "classic" Lys and Arg, several other aminoacids such as Tyr, Leu, Ala, and Gln can be accepted in P9, but with significant differences in binding affinity. (c) Different amino acids in P3 have an influence on peptide binding. Trp and Phe have a favorable influence, whereas Lys and Val appear to hinder the binding. Some variations are seen also for different amino acids in P7.

Amino Acid Sequence↗

PubMed1994

[Echocardiography in the early diagnosis of acute rejection in patients with heart transplant].

The aim of our study was to assess the sensibility and specificity of Doppler echocardiographic evaluation of left ventricular diastolic function during acute cardiac rejection. We studied 34 patients who had undergone a recent heart transplant and compared the echocardiographic results with the histologic findings. We considered the following parameters of left ventricular filling: early peak of mitral flow velocity; pressure half-time (PHT); isovolumic relaxation time (IVRT). We divided the patients into two groups according to the histologic findings: Group I (25 patients who had at least 1 episode of mild-moderate rejection), Group II (6 patients without documented rejection after at least three consecutive biopsies). Three patients with clinically evident rejection were excluded from the analysis. In Group I cardiac rejection was associated with a statistically significant decrease in IVRT (p < 0.0005), without significant changes in heart rate and in the early peak of mitral flow velocity. In Group II Doppler parameters remained unchanged. These variations were not associated with changes in echocardiographic morphologic parameters and in parameters of ventricular systolic function. IVRT and PHT returned to normal values after adequate immunosuppressive treatment. Considering variations of IVRT and PHT of at least 20%, we obtained a sensibility of 88% for isolated variations of PHT and a specificity of 93% for consensual variations of PHT and IVRT. Therefore, the assessment of the left ventricular diastolic function by Doppler echocardiography represents a safe and non-invasive method for an early detection of acute cardiac rejection.

Acute Disease↗

PubMed1994

[Antiphospholipid antibody syndrome].

The antiphospholipid antibody syndrome may develop both in patients with Systemic Lupus Erythematosus and as a primary disease, i.e. in the absence of both clinical manifestations and specific antibodies of Systemic Lupus Erythematosus. The primary syndrome is characterized by one of the following clinical manifestations: recurrent thromboembolic events, spontaneous abortions, immune thrombocytopenia, associated with laboratory signs such as the presence of anticardiolipin antibodies, lupus anticoagulant and/or antiphospholipid antibodies. Thrombosis by antiphospholipid antibodies is due to endothelial damage rather than to vasculitis. Several mechanisms have been postulated to explain the thrombotic effect of these antibodies. Anticoagulants, both dicumarol and heparin, associated with prednisone, are the classic therapy. High doses of immunoglobulins, plasmapheresis, immunoadsorbent plasmapheresis have also been used. Corticosteroids in bolus, possibly associated with cyclophosphamide also in bolus and plasmapheresis can be tried in more severe cases.

Adrenal Cortex Hormones↗

PubMed1993

Combined interleukin 1 beta/interleukin 2 treatment in mice: synergistic myelostimulatory activity and protection against cyclophosphamide-induced myelosuppression.

We have studied the effects of single and combined treatment with interleukin 1 beta (IL-1 beta) and interleukin 2 (IL-2) on spleen and bone marrow hematopoiesis in normal mice. Injection of IL-1 beta alone was followed by a significant increase in the number of granulocytes in spleen and progenitors (burst-forming units-erythroid and colony-forming units-granulomonocytic) in both spleen and bone marrow, s compared to control mice. In contrast, IL-2 alone induced only a slight increase in the number of marrow colony-forming units-granulomonocytic and had no significant effect on spleen progenitors. Repeated injections of both IL-1 beta and IL-2 resulted in a synergistic increase in spleen weight and splenocyte number, as compared to mice treated with the single cytokine regimen; in particular, the combined treatment induced a marked rise in the number of neutrophilic granulocytes and erythroblasts, whereas splenic lymphocytes were not affected. This regimen also caused a synergistic increase in the number of spleen and marrow progenitor cells: a time-course analysis showed an elevation in numbers of both burst-forming units-erythroid and colony-forming units-granulomonocytic, first in marrow (day 10) and subsequently in spleen (day 18). Combined IL-1 beta/IL-2 treatment dampened the decrease and accelerated the recovery of myeloid cells after cyclophosphamide injection, whereas the single cytokine regimen was not effective. Similarly, the rebound of WBC (especially neutrophilic granulocytes) after cyclophosphamide treatment was markedly enhanced by the combined treatment, whereas the single cytokine regimen was ineffective. These results, indicating a myelostimulatory effect by the combined cytokine regimen, together with our previous observations showing a synergistic antitumor activity by IL-1/IL-2 treatment in experimental mouse tumors (V. Ciolli et al., J. Exp. Med., 173: 313-322, 1991), may provide the basis for the development of new combination therapies with cytokines and antiblastic agents in the treatment of cancer patients.

Animals↗

PubMed1993

Computer-aided structure-affinity relationships in a set of piperazine and 3,8-diazabicyclo[3.2.1]octane derivatives binding to the mu-opioid receptor.

Molecular modeling studies were carried out on a set of piperazine and 3,8-diazabicyclo[3.2.1]octane derivatives with the aim to highlight the main factors modulating their affinity for the mu-opioid receptor. Structure-affinity relationships were developed with the aid of molecular mechanics and semiempirical quantum-mechanics methods. According to our proposed pharmacodynamic model, the binding to the mu-receptor is promoted by the following physico-chemical features: the presence of hydrocarbon fragments on the nitrogen ring frame capable of interacting with one of two hypothesized hydrophobic receptor pockets; a 'correct' orientation of an N-propionyl side chain so as to avoid a sterically hindered region of the receptor; the possibility of accepting a hydrogen bond from a receptor site complementary to the morphine phenol oxygen.

Bridged Bicyclo Compounds↗

PubMed1993

Use of the hydrogen bond potential function in a comparative molecular field analysis (CoMFA) on a set of benzodiazepines.

The results of the GRID-Comparative Molecular Field Analysis (CoMFA) were compared with those of the SYBYL-CoMFA in a study of benzodiazepines. The results demonstrate that the hydrogen bonding function using the GRID H2O probe in a CoMFA can successfully describe the hydrophobic effects of substituents without any bias or preconcept of their effects in the development.

Benzodiazepines↗

PubMed1993

Incidence of stroke in young adults in the Reggio Emilia area, northern Italy.

A retrospective epidemiological study on the first episode of stroke in young adults aged 15-44 years was carried out in the territory of the Local Health Unit No. 9 in Reggio Emilia (46,491 km2), Italy, from 1987 to 1989. 29 patients were identified: 17 were affected with cerebral infarction and 12 with hemorrhage. All young patients were discharged with diagnostic codes 430-438 according to the International Classification of Disease, i.e. the criteria of the World Health Organisation for stroke definition. All patients had computed tomography or necropsy. The average annual incidence rate per 100,000 population aged 15-44 for all strokes was 13.6 and the 95% confidence interval (CI 95%) was 9.1-19.6. The general population of the same age on January 1, 1987, was 69,845 and 71,920 on December 31, 1989; the incidence rate of stroke was 14.0 for males (CI 95% 7.9-2.3) and 13.2 (CI 95% 7.1-22.2) for females. The average annual incidence rates were 8.0 (CI 95% 4.7-12.2) for cerebral infarction (8.4, CI 95% 3.9-16 for males, 7.6, CI 95% 3.3-14.9 for females), 5.6 (CI 95% 2.9-9.9) for cerebral hemorrhage and 2.8 (CI 95% 1.0-6.1) for both subarachnoid (SAH) and intracerebral hemorrhage (ICH). Based on angiography or necropsy findings, aneurysms or arteriovenous malformations were present in 83% of the patients with SAH and in 66% of the patients with ICH. The 1-month fatality ratio was 0 for cerebral infarction, 50% for SAH and 33% for ICH.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Isolation and characterization of a metastatic Eb-like tumor variant highly responsive to interleukin (IL)-2 and to combination cytokine therapy with IL-2/IL-1 beta and IL-1 beta/interferon-alpha/beta.

In this study, we describe the origin and characterization of a new metastatic tumor cell line (p11-R-Eb) obtained after i.p. passages of the nonmetastatic Eb lymphoma cells into DBA/2 mice. The p11-R-Eb cells exhibited the same morphology and in vitro growth properties and chromosome markers as the original Eb cells. FACS analysis of the p11-R-Eb cells also revealed a close similarity to the Eb cells. Moreover, the p11-R-Eb cells were specifically killed by anti-Eb cytotoxic lymphocytes. In spite of all these characteristics of the Eb line, p11-R-Eb cells metastasized to the liver when injected i.v. or s.c. in DBA/2 mice. Peritumoral interleukin (IL)-2 treatment resulted in a potent antitumor response in DBA/2 mice transplanted s.c. with p11-R-Eb cells. In contrast, the same IL-2 regimen did not significantly increase the survival time of mice transplanted with the highly metastatic ESb cell line. Combined IL-1/IL-2 treatments of established p11-R-Eb tumors resulted in a synergistic antitumor effect and in tumor regression in 70% of the injected mice. Similarly, combined peritumoral treatment with IL-1 and interferon-alpha/beta, which were poorly effective or ineffective as single cytokine therapy, resulted in a marked antitumor effect, and 30% of the mice were cured. Spleen cells from IL-1/IL-2-treated p11-R-Eb-cell-injected mice showed a marked antitumor activity when assayed in a Winn assay with homologous tumor cells. This antitumor activity was eliminated by preincubation of spleen cells with antibodies to CD4 and complement and markedly inhibited by anti-asialo GM1 antibodies. P11-R-Eb cells represent, therefore, a new tumor model which may be useful for investigating the relevant mechanisms which need to be activated to achieve a potent antitumor response to cytokine therapy in the DBA/2 mouse host.

Animals↗

PubMed1993

Synthesis and neurokinin antagonist activity of 2-benzylidene- and 2-benzyl-3-benzylamino quinuclidines.

Molecular modeling studies based on the potent NK-1 antagonist CP-96,345 led us to the identification of some 2-benzylidene- and 2-benzyl-3-benzylaminoquinuclidine derivatives as potential antagonists at the NK receptor subtypes. The synthesized compounds, whose Z/E isomerism has been defined by X-ray analysis, show only moderate potency on the three neurokinin receptors. The possible reasons of the low potency exhibited by the tested compounds are discussed.

Amino Acid Sequence↗

PubMed1993

Synthesis and muscarinic receptor binding profiles of antagonist benzotriazole derivatives.

A series of benzotriazole derivatives were synthesized and tested in order to determine their activities for muscarinic receptor subtypes (M1, M2 and M3). Binding affinities were measured as KI values by competition against [3H]-N-methylscopolamine in rat cortex, atria and ileum. Pharmacological in vitro tests were performed on isolated tissue preparations (rabbit vas deferens, guinea pig atria and ileum); the compounds showed antimuscarinic activity. The synthesized ligands were characterized by moderate activity; however, some of them displayed interesting selectivity profiles (M2/M1 and M2/M3); particularly, the selectivity exhibited by the benzotriazole derivative 14b was quite similar to that observed for AF-DX 116, a typical M2 specific antagonist.

Animals↗

PubMed1993

[Percutaneous valvuloplasty in mitral stenosis].

Since May 1991 to July 1992, 83 patients (mean age 49 +/- 13 years, 17 males and 66 females) underwent percutaneous mitral valvuloplasty according to Inoue's technique. Following Wilkins' criteria echo-score was < or = 8 in 46 patients and mono-commissural calcifications were present in 8 cases. Sixteen (19%) patients had previous surgical mitral commissurotomy and 15 (18%) had previous embolic events. The indications for the procedure were given on the basis of the echo-score (ideal cases with score < or = 8). All patients but 2 were successfully treated. Two patients who developed mitral regurgitation grade 3+/4+ were referred to elective surgery. Mitral valve area increased from 1.1 +/- 0.2 to 2 +/- 0.3 cm2 (p < 0.001) and transvalvular pressure gradient fell from 16 +/- 5 to 6 +/- 3 mmHg (p < 0.001). Patients with previous surgical commissurotomy had a lower increase in mitral valve area than patients without previous surgery (p < 0.02). Patients with echo-score > 8 presented a more evident increase in mitral regurgitation than patients with good valvular anatomy, even if this difference was not significant. At 6 and 12 month follow-up respectively 2 and 1 restenosis occurred, but in 1 of these cases the residual valvular area was > 1.5 cm2. The authors conclude that in selected patients with mitral stenosis percutaneous mitral valvuloplasty seems to be an effective and safe treatment. Furthermore, immediate and middle-term results show that this technique can be performed without adjunctive risks and with satisfactory results also in cases of no ideal clinical and/or valvular conditions (echo-score > 8, previous surgical commissurotomy, history of embolism, mono-commissural calcifications).

Adult↗

PubMed1993

Chiari osteotomy in association with intertrochanteric osteotomy in adults.

The authors report the results obtained in 34 adult patients suffering from early degenerative arthritis of the hip following mixed dysplasia in which the reduction in the central-edge angle and the increase in the acetabular index is associated with modification of the neck-shaft angle and/or femoral anteversion. These patients underwent a combined Chiari iliac osteotomy (C.I.O.) and intertrochanteric osteotomy (In.O.). The results indicate that, when the indications and technique are respected, C.I.O. associated with In.O. is a reliable surgical method.

Adult↗

PubMed1991

Recurrent and new tumours during conservative treatment of bilateral retinoblastoma.

Conservative treatment of retinoblastoma is a combination of different therapeutic modalities: radiotherapy, photocoagulation, cryocoagulation, chemotherapy. The choice of the most suitable treatment depends on the stage of the disease. The evaluation of the regression and quiescence of tumoral foci after radiotherapy, Xenon photocoagulation or cryocoagulation is based on a purely subjective examination of the ophthalmoscopic aspects which are common to various types of treatment. Frequently, degenerative changes of the tumour mass are difficult to differentiate from actual recurrence. Recurrences generally start at the edge of the scar or within the scar, while new retinal tumours are observed far from the original tumour, sometimes near the ora serrata. The authors discuss the regression patterns and the ophthalmoscopic and clinical aspects of recurrent and new tumours and report their personal experience on the therapeutic approach.

Antineoplastic Agents↗