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Biomedical subjects

C Martini

Publications and source records attributed to C Martini.

At least 73 records · Page 4Linked to original sources
PubMed1998

Fluorescent probes for adenosine receptors: synthesis and biology of N6-dansylaminoalkyl-substituted NECA derivatives.

New fluorescent ligands for adenosine receptors are described; these compounds were obtained by the insertion, in the N6 position of NECA (a potent adenosine agonist), of dansylaminoalkyl moieties with alkyl spacers of increasing carbon chain length (from 3 to 12). Among them, the compound with a C6 alkyl spacer proved to be the most interesting one, showing a marked selectivity for the A1 receptor subtype; furthermore, in fluorescence microscopy assays it proved to be able to visualize and localize this receptor subtype at the level of the molecular layer of the rate cerebellar cortex.

Adenosine-5'-(N-ethylcarboxamide)↗
PubMed1998

Characterization of sulfonylurea receptors in isolated human pancreatic islets.

Current information on pancreatic islet sulfonylurea receptors has been obtained with laboratory animal pancreatic beta cells or stable beta-cell lines. In the present study, we evaluated the properties of sulfonylurea receptors of human islets of Langherans, prepared by collagenase digestion and density-gradient purification. The binding characteristics of labeled glibenclamide to pancreatic islet membrane preparations were analyzed, displacement studies with several oral hypoglycemic agents were performed, and these latter compounds were tested as for their insulinotropic action on intact human islets. [3H]glibenclamide saturable binding was shown to be linear at < or =0.25 mg/ml protein; it was both temperature and time dependent. Scatchard analysis of the equilibrium binding data at 25 degrees C indicated the presence of a single class of saturable, high-affinity binding sites with a Kd value of 1.0+/-0.07 nM and a Bmax value of 657+/-48 fmol/mg of proteins. The displacement experiments showed the following rank order of potency of the oral hypoglycemic agents we tested: glibenclamide = glimepiride > tolbutamide > chlorpropamide >> metformin. This binding potency order was parallel with the insulinotropic potency of the evaluated compounds.

ATP-Binding Cassette Transporters↗
PubMed1998

Effects of long-term treatment with Serenoa repens (Permixon) on the concentrations and regional distribution of androgens and epidermal growth factor in benign prostatic hyperplasia.

BACKGROUND: The n-hexane lipido-sterol extract of Serenoa repens (LSESr, Permixon, Pierre Fabre Medicament, Castres, France), a phytotherapeutic agent used in the treatment of benign prostatic hyperplasia (BPH), has a multisite mechanism of action including inhibition of types 1 and 2 5alpha-reductase and competitive binding to androgen receptors in prostatic cells. Here, the response of testosterone (T), dihydrotestosterone (DHT), and epidermal growth factor (EGF) in BPH tissue of patients treated with LSESr (320 mg/day for 3 months) is analyzed. METHODS: BPH samples were sectioned in periurethral, subcapsular, and intermediate regions: in each region T, DHT, and EGF were determined by radioimmunoassay after purification on celite columns or Sep-pak C18 cartridges. RESULTS: In the untreated group, T, DHT, and EGF presented the highest concentrations in the periurethral region (615 +/- 62 (SE) pg/g tissue, 7,317 +/- 551 pg/g tissue, and 20.9 +/- 3.3 ng/g tissue, respectively) with respect to the peripheral subcapsular region (425 +/- 45 pg/g tissue, 4,215 +/- 561 pg/g tissue, and 10.8 +/- 1.4 ng/g tissue, respectively). In the LSESr-treated group, a statistically significant reduction was observed, mainly in the periurethral region of DHT (2,363 +/- 553 pg/g tissue, P < 0.001) and EGF (6.98 +/- 2.48 ng/g tissue, P < 0.01), with increased T values (1,023 +/- 101 pg/g tissue, P < 0.001). CONCLUSIONS: The decrease of DHT and the rise of T in BPH tissue of patients treated with Permixon confirms the capacity of this drug to inhibit in vivo 5alpha-reductase in human pathological prostate. A marked decrease of EGF, associated with DHT reduction, was also observed. These biochemical effects, similar to those obtained with finasteride, are particularly evident in the periurethral region, whose enlargement is responsible for urinary obstruction, with respect to the subcapsular region. A possible speculation is that the preferential reduction of DHT and EGF content in the periurethral region is involved in the clinical improvement of the obstructive symptoms in BPH during LSESr therapy.

Aged↗
PubMed1998

N'-Phenylindol-3-ylglyoxylohydrazide derivatives: synthesis, structure-activity relationships, molecular modeling studies, and pharmacological action on brain benzodiazepine receptors.

A series of N'-phenylindol-3-ylglyoxylohydrazides, isosters of the N-benzylindol-3-ylglyoxylamide derivatives previously described by us, were synthesized and tested for their ability to displace [3H]Ro 15-1788 from bovine brain membranes. These compounds were designed with the aim of obtaining products which could exert an in vivo activity, thanks to a higher hydrosolubility and consequently a better bioavailability. Affinity was restricted to the derivatives unsubstituted in the 5 position of the indole nucleus (1, 6, 9, 12, 15, 18, 23, and 26), with Ki values ranging from 510 to 11 nM. The most active compounds (6, 9, 23, and 29) proved to be effective in antagonizing pentylenetetrazole-induced seizures. Molecular modeling studies were performed to rationalize the lack of affinity of hydrazides with a chloro or a nitro group in the 5 position of the indole nucleus. It was hypothesized that the conformational preference of the hydrazide side chain, characterized by a gauche disposition of lone pairs and substituents about the N-N bond, prevents all hydrazides from binding to the receptor similarly to other classes of indole analogues previously investigated. The potency of 5-H hydrazides was attributed to a binding mode which is not feasible for 5-Cl and 5-NO2 counterparts. This theoretical model of ligand-receptor interaction permitted a more stringent interpretation of structure-affinity relationships of hydrazides and of recently described benzylamide derivatives (Da Settimo et al. J. Med. Chem. 1996, 39, 5083-5091).

Animals↗
PubMed1998

Neurotoxicity of interferon-alpha in melanoma therapy: results from a randomized controlled trial.

BACKGROUND: The objective of this study was to evaluate the neurologic and quality of life impact of low dose adjuvant interferon (IFN)-alpha immunotherapy in patients with malignant melanoma metastatic to regional lymph nodes after radical surgery. METHODS: One hundred and thirteen patients were randomized to receive IFN-alpha, 3 x 10(6) IU three times weekly by subcutaneous injection for 36 months or until melanoma recurrence (IFN group), or to act as controls (CTR group). Seventy-five of these patients (66%) entered the toxicity study and underwent formal neurologic, neuropsychologic, psychologic, and quality of life assessments. Patients were assessed at baseline and after 1, 3, 6, and 12 months of follow-up. For each variable, maximum worsening of symptoms from baseline was considered as a response variable. The differences between the two groups regarding this variable were evaluated by means of the Hodges-Lehmann median unbiased point estimates and their 95% confidence interval. RESULTS: A significant degree of action tremor was found in eight patients in the IFN group and in none of the controls. No differences were found during psychiatric evaluation and for cognitive tests. There was a greater increase in anxiety in the IFN group on both trait and state anxiety. With regard to quality of life the analysis showed a significant worsening of at most one level on only three questionnaire items and on the fatigue scale. CONCLUSIONS: Neurologic dysfunction associated with IFN therapy was mild. Psychiatric symptoms and neuropsychologic impairment were not found. Levels of fatigue and anxiety were increased in the IFN group but without a sizable impact on quality of life measures.

Adult↗
PubMed1998

2'-C-Methyl analogues of selective adenosine receptor agonists: synthesis and binding studies.

2'-C-Methyl analogues of selective adenosine receptor agonists such as (R)-PIA, CPA, CCPA, NECA, and IB-MECA were synthesized in order to further investigate the subdomain that binds the ribose moiety. Binding affinities of these new compounds at A1 and A2A receptors in bovine brain membranes and at A3 in rat testis membranes were determined and compared. It was found that the 2'-C-methyl modification resulted in a decrease of the affinity, particularly at A2A and A3 receptors. When such modification was combined with N6-substitutions with groups which induce high potency and selectivity at A1 receptors, the high affinity was retained and the selectivity was increased. Thus, 2-chloro-2'-C-methyl-N6-cyclopentyladenosine (2'-Me-CCPA), which displayed a Ki value of 1.8 nM at A1 receptors, was selective for A1 vs A2A and A3 receptors by 2166- and 2777-fold, respectively, resulting in one of the most potent and A1-selective agonists so far known. In functional assay, this compound inhibited forskolin-stimulated adenylyl cyclase activity with an IC50 value of 13.1 nM, acting as a full agonist.

Adenosine↗
PubMed1998

Organizational aspects of donor procurement activity in the North Italy Transplant programme (NITp).

In Italy, organ procurement is insufficient to meet patient need. The aim of this study was to estimate the potential donor pool, quantify nonused donors, identify causes of nonretrieval, and evaluate the impact of some hospital organizational problems on organ procurement. In 1995 a questionnaire was sent to 103 intensive care units (ICUs) in 92 hospitals of the NITp area. Out of 432 potential donors identified, 239 (55.3%) were used. Causes of nonretrieval included family refusal (51.7%), clinical reasons (43.9%) and organizational problems (4.4%). In comparison with 1990 and 1993 data, a higher percentage of donors were used and the donors lost for organizational reasons had decreased significantly, while no significant differences were observed in the number of donors lost for family refusal and for clinical reasons. The marked improvement in donor procurement in NITp from 1990 to 1995 was probably as result of measures aimed at motivating ICU personnel and solving their organizational difficulties.

Humans↗
PubMed1998

Synthesis and A1 and A2A adenosine binding activity of some pyrano[2,3-c]pyrazol-4-ones.

A series of pyrano[2,3-c]pyrazol-4-ones was synthesized and evaluated for bovine brain adenosine A1 and A2A receptor binding affinity. Substituents at positions 5 and/or 6 were varied in order to define the structure-activity relationships in these new kinds of adenosine receptor ligands. The most selective and potent ligand among the reported compounds was the 1,4-dihydro-1-phenyl-3-methyl-6-(3-aminophenyl)-pyrano[2,3-c]pyraz ol-4-one 11 which showed a 27-fold selectivity for A1 receptor and a Ki value of 84 nM.

Animals↗
PubMed1998

1,2,3-Triazolo[1,5-a][1,4]- and 1,2,3-triazolo[1,5-a]-[1,5]benzodiazepine derivatives: synthesis and benzodiazepine receptor binding.

This paper reports the synthesis of new 1,2,3-triazolo[1,4]benzodiazepine and 1,2,3-triazolo[1,5]benzodiazepine derivatives and their evaluation toward benzodiazepine receptors. Receptor affinity gradually and remarkably increases by moving the nitrogen atom of the central ring from position 3 through 4 to position 5, to give the most effective compound 6a (Ki = 150 nM). N-methylation of the diazepine ring (7a) lowers receptorial binding. Introduction of a chlorine atom on the benzene ring doubles the Ki value (6b) which remains unaltered by the N-methylation (7b).

Animals↗
PubMed1998

ACTH-mediated glucocorticoid and mineralocorticoid production is inhibited by an inositolphosphoglycan and a glycosylphosphatidylinositol-phospholipase C is activated by the hormone in mammalian adrenocortical cells.

In the present paper, we report that an inositolphosphoglycan (IPG), derived from a Trypanosoma cruzi glycoinositolphosphoceramide (LPPG), is able to inhibit ACTH-mediated accumulation of a glucocorticoid, cortisol, in calf adrenocortical cells. This IPG is also able to inhibit the stimulation by ACTH of the production of the main glucocorticoid, corticosterone and the main mineralocorticoid, aldosterone, in rat adrenocortical cells. Nitrous acid deamination confirmed that IPG is responsible for this inhibition. In order to study the involvement of glycosylphosphatidylinositol (GPI) in ACTH response in rat adrenal cortex, the activation of a phospholipase that hydrolyzes GPI (GPI-PLC) was evaluated. It was found that the release of alkaline phosphatase, a GPI-anchored enzyme, to the extracellular medium is increased in rat adrenocortical cells by ACTH treatment. In addition, ACTH stimulates the release of ceramide from the glycoinositolphosphoceramide purified from T. cruzi. These data suggest that ACTH activates a GPI-PLC in rat adrenal cortex, which is in agreement with our previous data in calf adrenocortical cells; thus, the hydrolysis of GPI provoked by ACTH takes place in different mammals and the IPG released could inhibit ACTH-mediated synthesis of aldosterone, corticosterone and cortisol.

Adrenal Cortex↗
PubMed1998

Chemical modification of the dihydropyridines binding sites by lysine reagent, pyridoxal 5'-phosphate.

Treatment of rabbit brain membranes of the DHP binding sites of L-type Ca2+ channel with lysine-specific reagent resulted in a time- and concentration-dependent loss of [3H]nitrendipine binding activity. Following exposure to the maximum concentration of PLP (100 mM), [3H]nitrendipine binding was inhibited by up to 96.5%. Scatchard analysis of the binding data indicated that treatment with PLP resulted in a loss of [3H]nitrendipine binding sites with no effect on binding affinity. Considerable protection against PLP inactivation was obtained by nifedipine. These results indicate that lysine residue plays a critical role in maintaining the DHP-binding sites in a conformation capable of ligand binding.

Animals↗
PubMed1998

A2a adenosine receptors: guanine nucleotide derivative regulation in porcine striatal membranes and digitonin soluble fraction.

We report the characterization of A2a adenosine receptors (A2aARs) in porcine striatal membranes and their solubilization (25%) by the detergent digitonin. After solubilization, the drug specificity and equilibrium [3H]CGS-21680 ([3H]2-(4-(2-carboxyethyl)phenylethylamino)-5'-N-ethyl-carboxamido -adenosine) binding parameters were virtually identical to those obtained in intact membranes, indicating a conservation of the binding site after the removal of receptors from their lipid environment. Gel filtration on a calibrated Superdex 200 HR column revealed a main [3H]CGS-21680 binding peak with an apparent molecular weight of 171,000+/-9000 Da. In membranes, Scatchard analysis of saturation data carried out in a wide range of radioligand concentration (1-100 nM) resulted in a biphasic curve and, in accordance with the two binding sites model, yielded a Kd1 = 7.4+/-0.5 and Kd2 = 53.1+/-3.6 nM, a Bmax1 = 186+/-15 fmol/mg protein and a Bmax2 = 285+/-20 fmol/mg protein, respectively. In the presence of guanosine-5'-O-(3-thiotriphosphate) (GTPgamma[S]) a shift from two affinity states to a single one was evidenced (Kd = 28.5+/-5.9 nM) and a Bmax value of 504+/-10 fmol/mg protein found. In the soluble extract, only one high-affinity state was detected (Kd = 19.3+/-1.1 nM and Bmax = 285+/-20 fmol/mg protein) and, in the presence of GTPgamma[S]), a two site model likewise provided a significantly (P < 0.01) better fit (Kd1 = 13.9+/-1.2 nM and Kd2 = 72.1+/-6.9 nM, Bmax1 = 125+/-10 fmol/mg protein and Bmax2 = 375+/-19 fmol/mg protein, respectively). These results suggest a close relation between the receptor and G protein solubilized as a functional unit and open the way to its purification.

Adenosine↗
PubMed1998

Megestrol acetate for anorexia in patients with far-advanced cancer: a double-blind controlled clinical trial.

The aim of this study was to evaluate a low-dose regimen of megestrol acetate (MA; 320 mg/day) on appetite in advanced cancer patients. Out-patients with far-advanced non-hormone responsive tumours and loss of appetite were randomised in a phase III trial, with two consecutive phases: a 14-day double-blind placebo controlled phase (phase A) and a 76-day open phase (phase B). During phase A, patients were treated with MA, two 160 mg tablets/day, or placebo. In phase B, the MA dose was titrated to clinical response in both groups. Appetite, food intake, body weight, performance status, mood and quality of life were evaluated with standardised measures; patients' global judgement about treatment efficacy was also requested. Of 42 patients entering the study, 33 (17 MA and 16 placebo) were evaluable for efficacy. The appetite score improved significantly with MA after 7 days (P = 0.0023), and this effect was still significant at 14 days (P = 0.0064). Patients judged the treatment with MA effective in 88.2% of cases (14th day), whilst placebo was considered effective by 25% (P = 0.0003). None of the other measures showed significant changes during treatment. The remarkable effect on appetite evident after 7 days, without serious side-effects, shows that MA can produce significant subjective effects at a low-dose even in patients with far-advanced disease.

Adolescent↗
PubMed1998

Surgical treatment of abdominal aortic aneurysm in association with horseshoe kidney. Three case reports and a review of technique.

Horseshoe kidney is a rare congenital anomaly that can create various technical problems during surgery for repair of abdominal aortic aneurysm. The diagnosis of this anomaly should be confirmed preoperatively in order to plan surgical strategy. Nowadays, in more than 90% of all cases, ultrasonography, contrast computerized tomography, urography, and angiography are the best instrumental methods of detecting this anomaly in association with abdominal aortic aneurysm. The transperitoneal approach assures the best exposure of the kidney, the ureters, the aneurysm, and both iliac vessels, but the renal isthmus can pose a problem in reimplanting aberrant renal arteries. When it is known preoperatively that renal revascularization should be performed, the left extraperitoneal approach is a better choice. In any event, the coexistence of horseshoe kidney and abdominal aortic aneurysm does not preclude the treatment of the latter. In elective surgery of abdominal aortic aneurysm, the morbidity and mortality rates in the presence of horseshoe kidney are much the same as those in the presence of normal kidneys. The best results in this kind of surgery are obtained by adapting one's surgical technique to each anatomical variant that is encountered.

Aortic Aneurysm, Abdominal↗
PubMed1998

Prevalence of asthma and asthma-like symptoms in an adult population sample from Verona. ECRHS Verona. European Community Respiratory Health Survey.

The aim of the study was to assess the prevalence of asthma and asthma-like symptoms in the general population of Verona. A screening questionnaire, with seven questions on respiratory symptoms, was sent by mail to 3000 randomly selected subjects, aged 20-44 yrs. After three subsequent mailings, nonresponders were interviewed by telephone. The overall response rate was 92%. At least one respiratory symptom was reported by 44% subjects. The prevalence of the most frequent symptoms differed according to the type of contact: early respondents (i.e. those who responded by mail) were more likely to report symptoms than late respondents (i.e. those who were interviewed by telephone). Wheezing was reported by 11.3% of males and 8.0% of females (p < 0.01). The allergic rhinitis and hay-fever prevalence was 16.9% with no differences owing to sex or age. The prevalence of an "episode of asthma" (defined as a self-reported attack of asthma or treatment for asthma) and of "current asthma" (defined as a self-reported attack of asthma, treatment for asthma or wheezing other than due to a cold with dyspnoea in the last 12 months) was 4.1 and 4.7%, respectively. No differences were found on the basis of age and sex. The prevalence of asthma was greater in urban (5.0%) than in suburban (2.7%) areas (p < 0.05), where lower pollution levels were registered. The greater prevalence in urban areas suggests that some factors related to the urban environment could play a role in the development of asthma and asthma-like disorders.

Adult↗